HomeMy WebLinkAboutAppendix D3 Edina_2018_CWRMP_July-2018_Final2018 Comprehensive Water
Resources Management Plan
July 2018
4300 MarketPointe Drive, Suite 200
Minneapolis, MN 55435
952-832-2600 | www.barr.com
Barr Engineering Co.
2018 Comprehensive Water Resources Management Plan: City of Edina
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P:\Mpls\23 MN\27\23271514 2017 CWRMP SW Modeling Updates\WorkFiles\2018 Final
CWRMP\Edina_2018_CWRMP_July2018_Final.docx
City of Edina
2018 Comprehensive Water Resources Management Plan
July 2018
Contents
1.0 Executive Summary ........................................................................................................................................................... 1-1
1.1 Problems, Issues, and Potential Solutions ............................................................................................... 1-2
1.1.1 Water Resources Implementation Program ........................................................................ 1-2
1.1.2 Runoff Management and Flood Control ............................................................................... 1-2
1.2 Flood Risk Reduction Strategy ..................................................................................................................... 1-2
1.3 Clean Water Strategy ....................................................................................................................................... 1-4
2.0 Introduction and Physical Setting ............................................................................................................................... 2-1
2.1 Plan Purposes ..................................................................................................................................................... 2-1
2.2 Physical Setting .................................................................................................................................................. 2-2
2.2.1 Drainage Patterns ........................................................................................................................... 2-2
2.2.2 Watershed Management Organizations ............................................................................... 2-3
2.2.2.1 Minnehaha Creek Watershed District ................................................................................. 2-3
2.2.2.2 Nine Mile Creek Watershed District .................................................................................... 2-3
2.2.3 Land Use ............................................................................................................................................ 2-3
2.2.4 Soils ...................................................................................................................................................... 2-4
2.2.5 Topography ...................................................................................................................................... 2-4
2.2.6 Water Quality ................................................................................................................................... 2-4
2.2.6.1 Water Quality Monitoring ....................................................................................................... 2-4
2.2.6.2 Lakes ................................................................................................................................................. 2-4
2.2.6.3 Creeks ............................................................................................................................................... 2-5
2.2.6.4 Impaired Waters and Total Maximum Daily Loads ....................................................... 2-7
2.2.7 Parks, Recreation, and Natural Resources Open Space ............................................... 2-10
2.2.8 Public Utilities ............................................................................................................................... 2-10
2.2.9 Fish and Wildlife Habitat .......................................................................................................... 2-11
2.2.10 Unique Features and Scenic Areas ....................................................................................... 2-13
2.2.11 Pollutant Sources ......................................................................................................................... 2-13
2.2.11.1 Investigation and Cleanup Sites......................................................................................... 2-13
2.2.11.2 Tank Sites and Leak Sites ...................................................................................................... 2-14
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2.2.11.3 Individual Sewage Treatment Systems ........................................................................... 2-14
2.2.12 Groundwater ................................................................................................................................. 2-14
3.0 Policies for Water Resources Management ............................................................................................................ 3-1
3.1 Runoff Management and Flood Protection ............................................................................................ 3-1
3.1.1 Runoff Management and Flood Protection Background ............................................... 3-1
3.1.2 Runoff Management and Flood Protection Policies......................................................... 3-3
3.1.2.1 Minimum Principle Structure Elevations ........................................................................... 3-5
3.1.2.2 Below-Grade Garages and Parking Adjacent to Flood-Prone Areas ..................... 3-6
3.1.2.3 Stormwater Management Design Standards .................................................................. 3-7
3.2 Floodplain Management ................................................................................................................................ 3-8
3.3 Water Quality ................................................................................................................................................... 3-10
3.3.1 Water Quality Background ...................................................................................................... 3-10
3.3.2 Water Quality Management Policies ................................................................................... 3-12
3.3.2.1 Water Quality Management Standards .......................................................................... 3-14
3.4 Erosion and Sediment Control .................................................................................................................. 3-14
3.4.1 Erosion and Sediment Control Policies ............................................................................... 3-14
3.5 Wetlands ............................................................................................................................................................ 3-14
3.5.1 Wetlands Policies ......................................................................................................................... 3-14
3.6 Natural Resources .......................................................................................................................................... 3-15
3.7 Groundwater .................................................................................................................................................... 3-16
3.8 Education Program ........................................................................................................................................ 3-16
3.9 NPDES Considerations ................................................................................................................................. 3-17
4.0 Methodology for Modeling ........................................................................................................................................... 4-1
4.1 Methodology for Hydrologic/Hydraulic Modeling .............................................................................. 4-1
4.1.1 Hydrologic Modeling .................................................................................................................... 4-1
4.1.1.1 Watershed Data ........................................................................................................................... 4-1
4.1.1.2 Rainfall Data .................................................................................................................................. 4-4
4.1.1.3 Infiltration Data ............................................................................................................................ 4-4
4.1.1.4 Depression Storage Data ......................................................................................................... 4-5
4.1.1.5 Overland Flow Roughness ....................................................................................................... 4-5
4.1.2 Hydraulic Modeling ....................................................................................................................... 4-5
4.1.2.1 Storm Sewer Network ............................................................................................................... 4-5
4.1.2.2 Tailwater Effects ........................................................................................................................... 4-6
4.1.2.3 Overland Flow Network ............................................................................................................ 4-7
4.1.3 Stormwater System Analysis ...................................................................................................... 4-7
4.1.3.1 Problem Areas Selection Process ......................................................................................... 4-9
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4.2 Methodology for Water Quality Modeling .......................................................................................... 4-10
4.2.1 Watershed Characteristics ....................................................................................................... 4-10
4.2.1.1 Impervious Fraction ................................................................................................................. 4-11
4.2.1.2 Pervious Curve Number ........................................................................................................ 4-12
4.2.1.3 Other P8 Watershed Input Parameters ........................................................................... 4-12
4.2.2 Treatment Device Characteristics .......................................................................................... 4-12
4.2.2.1 Dead Storage ............................................................................................................................. 4-12
4.2.2.2 Live Storage ................................................................................................................................ 4-13
4.2.2.3 Other P8 Treatment Device Input Characteristics ...................................................... 4-13
4.2.3 Precipitation and Temperature Data ................................................................................... 4-14
4.2.4 Selection of Other P8 Model Parameters .......................................................................... 4-14
4.2.4.1 Time Step, Snowmelt, and Runoff Parameters ............................................................ 4-14
4.2.4.2 Particle File Selection .............................................................................................................. 4-15
4.2.4.3 Passes through the Storm File ............................................................................................ 4-15
4.2.5 Stormwater System Analysis ................................................................................................... 4-15
5.0 Nine Mile Creek—North ................................................................................................................................................. 5-1
5.1 General Description of Drainage Area ...................................................................................................... 5-1
5.1.1 Drainage Patterns ........................................................................................................................... 5-1
5.1.1.1 Mirror Lake ..................................................................................................................................... 5-1
5.1.1.2 Highlands Lake ............................................................................................................................. 5-1
5.1.1.3 Hawkes Lake .................................................................................................................................. 5-2
5.1.1.4 Mud Lake (Bredesen Park) ....................................................................................................... 5-2
5.1.1.5 Nine Mile North ........................................................................................................................... 5-3
5.2 Stormwater System Results ........................................................................................................................... 5-3
5.2.1 Hydrologic/Hydraulic Modeling Results ............................................................................... 5-3
5.2.2 Water Quality Modeling Results ............................................................................................... 5-4
5.3 Implementation Considerations .................................................................................................................. 5-4
5.3.1 Flood Protection Projects ............................................................................................................ 5-4
5.3.1.1 Maloney Avenue and Tyler Court (ML_35 and ML_19) ............................................... 5-5
5.3.1.2 Between Leslee Lane and Kaymar Drive (MD_22) ......................................................... 5-5
5.3.1.3 Parkwood Road and Schaefer Road (MD_28, MD_29, and MD_35) ...................... 5-6
5.3.1.4 Schaefer Road and View Lane (MD_38) ............................................................................. 5-6
5.3.1.5 Nine Mile Village Townhomes (MD_49) ............................................................................ 5-7
5.3.1.6 Hawkes Lake and Upstream Surrounding Area (HL_1, HL_11c, HL_11w, HL_49,
and HL_12) ..................................................................................................................................... 5-7
5.3.2 Construction/Upgrade of Water Quality Basins ................................................................. 5-8
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5.3.2.1 MD_15 .............................................................................................................................................. 5-8
5.3.2.2 NMN_27 .......................................................................................................................................... 5-8
5.3.2.3 NMN_24 .......................................................................................................................................... 5-8
5.3.2.4 NMN_49 .......................................................................................................................................... 5-9
5.3.2.5 MD_3 ................................................................................................................................................ 5-9
6.0 Nine Mile Creek—Central ............................................................................................................................................... 6-1
6.1 General Description of Drainage Area ...................................................................................................... 6-1
6.1.1 Drainage Patterns ........................................................................................................................... 6-1
6.1.1.1 Colonial Ponds ............................................................................................................................. 6-1
6.1.1.2 Indian Pond ................................................................................................................................... 6-1
6.1.1.3 Nine Mile Central ........................................................................................................................ 6-2
6.2 Stormwater System Results ........................................................................................................................... 6-2
6.2.1 Hydrologic/Hydraulic Modeling Results ............................................................................... 6-2
6.2.2 Water Quality Modeling Results ............................................................................................... 6-3
6.3 Implementation Considerations .................................................................................................................. 6-3
6.3.1 Flood Protection Projects ............................................................................................................ 6-3
6.3.1.1 Antrim Road and Chapel Drive (NMC_41) ........................................................................ 6-4
6.3.1.2 Ridgeview Drive (NMC_106 and NMC_107) .................................................................... 6-4
6.3.1.3 West 66th Street and Naomi Drive (NMC_71, NMC_74, and NMC_103) .............. 6-4
6.3.2 Construction/Upgrade of Water Quality Basins ................................................................. 6-5
7.0 Lake Cornelia/Lake Edina/Adam’s Hill ....................................................................................................................... 7-1
7.1 General Description of Drainage Area ...................................................................................................... 7-1
7.1.1 Drainage Patterns ........................................................................................................................... 7-1
7.1.1.1 North Cornelia .............................................................................................................................. 7-1
7.1.1.2 South Lake Cornelia ................................................................................................................... 7-2
7.1.1.3 Lake Edina ...................................................................................................................................... 7-2
7.1.1.4 Adam’s Hill Pond ......................................................................................................................... 7-2
7.2 Stormwater System Results ........................................................................................................................... 7-2
7.2.1 Hydrologic/Hydraulic Modeling Results ............................................................................... 7-2
7.2.2 Water Quality Modeling Results ............................................................................................... 7-3
7.3 Implementation Considerations .................................................................................................................. 7-3
7.3.1 Flood Protection Projects ............................................................................................................ 7-4
7.3.1.1 Valley View and Southdale Road Neighborhood (LE_34, LE_36, and LE_43) ..... 7-4
7.3.1.2 Southwest Corner of TH 62 and TH 100 (NC_7, NC_8, NC_13, NC_11, NC_12,
NC_14, NC_15, NC_16, and NC_20) ..................................................................................... 7-6
7.3.2 Construction/Upgrade of Water Quality Basins ................................................................. 7-6
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7.3.2.1 LE_38 ................................................................................................................................................. 7-7
7.3.2.2 NC_88 ............................................................................................................................................... 7-7
8.0 Nine Mile Creek South ..................................................................................................................................................... 8-1
8.1 General Description of Drainage Area ...................................................................................................... 8-1
8.1.1 Drainage Patterns ........................................................................................................................... 8-1
8.1.1.1 Centennial Lakes .......................................................................................................................... 8-1
8.1.1.2 South Pond (Border Basin) ...................................................................................................... 8-1
8.1.1.3 Nine Mile South ........................................................................................................................... 8-2
8.2 Stormwater System Results ........................................................................................................................... 8-2
8.2.1 Hydrologic/Hydraulic Modeling Results ............................................................................... 8-2
8.2.2 Water Quality Modeling Results ............................................................................................... 8-3
8.3 Implementation Considerations .................................................................................................................. 8-3
8.3.1 Flood Protection Projects ............................................................................................................ 8-3
8.3.1.1 West 70th Street and West Shore Drive (NMS_38 and NMS_50) ............................ 8-4
8.3.1.2 Centennial Lakes (CL_1) ............................................................................................................ 8-4
8.3.2 Construction/Upgrade of Water Quality Basins ................................................................. 8-5
8.3.2.1 West 77th Street and TH 100 .................................................................................................. 8-5
8.3.2.2 NMS_76 ........................................................................................................................................... 8-6
8.3.2.3 NMS_104 ......................................................................................................................................... 8-6
8.3.2.4 NMS_72 and NMS_74 ................................................................................................................ 8-6
8.3.2.5 SP_1 (South Pond/Border Basin) ........................................................................................... 8-6
9.0 Nine Mile South Fork ....................................................................................................................................................... 9-1
9.1 General Description of Drainage Area ...................................................................................................... 9-1
9.1.1 Drainage Patterns ........................................................................................................................... 9-1
9.1.1.1 Arrowhead Lake ........................................................................................................................... 9-1
9.1.1.2 Indianhead Lake ........................................................................................................................... 9-1
9.1.1.3 Pawnee Pond ................................................................................................................................ 9-2
9.1.1.4 Eden Prairie .................................................................................................................................... 9-2
9.1.1.5 Braemar Arena/Public Works ................................................................................................. 9-2
9.1.1.6 Nine Mile South Fork ................................................................................................................. 9-2
9.2 Stormwater System Results ........................................................................................................................... 9-3
9.2.1 Hydrologic/Hydraulic Modeling Results ............................................................................... 9-3
9.2.2 Water Quality Modeling Results ............................................................................................... 9-3
9.3 Implementation Considerations .................................................................................................................. 9-4
9.3.1 Flood Protection Projects ............................................................................................................ 9-4
9.3.1.1 McCauley Trail West (AH_6).................................................................................................... 9-4
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9.3.1.2 Sally Lane and Valley View Road (NMSB_52, NMSB_69, and NMSB_77) ............. 9-5
9.3.2 Construction/Upgrade of Water Quality Basins ................................................................. 9-5
9.3.2.1 NMSB_3 and NMSB_2 ............................................................................................................... 9-6
9.3.2.2 NMSB_12 ........................................................................................................................................ 9-6
9.3.2.3 NMSB_86 ........................................................................................................................................ 9-6
9.3.2.4 NMSB_7 ........................................................................................................................................... 9-7
9.3.2.5 NMSB_85 ........................................................................................................................................ 9-7
10.0 Southwest Ponds (Dewey Hill Road Area) ............................................................................................................ 10-1
10.1 General Description of Drainage Area ................................................................................................... 10-1
10.1.1 Drainage Patterns ........................................................................................................................ 10-1
10.1.1.1 Southwest Ponds ...................................................................................................................... 10-1
10.1.1.2 Nine Mile I-494 ......................................................................................................................... 10-1
10.2 Stormwater System Results ........................................................................................................................ 10-2
10.2.1 Hydrologic/Hydraulic Modeling Results ............................................................................ 10-2
10.2.2 Water Quality Modeling Results ............................................................................................ 10-2
10.3 Implementation Considerations ............................................................................................................... 10-3
10.3.1 Flood Protection Projects ......................................................................................................... 10-3
10.3.1.1 Gleason Road and Bonnie Brae Drive (SWP_24) ......................................................... 10-3
10.3.2 Construction/Upgrade of Water Quality Basins .............................................................. 10-4
11.0 TH 169 North .................................................................................................................................................................... 11-1
11.1 General Description of Drainage Area ................................................................................................... 11-1
11.1.1 Drainage Patterns ........................................................................................................................ 11-1
11.2 Stormwater System Results ........................................................................................................................ 11-1
11.2.1 Hydrologic/Hydraulic Modeling Results ............................................................................ 11-1
11.2.2 Water Quality Modeling Results ............................................................................................ 11-2
11.3 Implementation Considerations ............................................................................................................... 11-2
11.3.1 Flood Protection Projects ......................................................................................................... 11-2
11.3.2 Construction/Upgrade of Water Quality Basins .............................................................. 11-3
12.0 Northeast Minnehaha Creek ...................................................................................................................................... 12-1
12.1 General Description of Drainage Area ................................................................................................... 12-1
12.1.1 Drainage Patterns ........................................................................................................................ 12-1
12.1.1.1 Morningside ............................................................................................................................... 12-1
12.1.1.2 Minnehaha Creek North ........................................................................................................ 12-1
12.1.1.3 Edina Country Club .................................................................................................................. 12-2
12.2 Stormwater System Results ........................................................................................................................ 12-2
12.2.1 Hydrologic/Hydraulic Modeling Results ............................................................................ 12-2
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12.2.2 Water Quality Modeling Results ............................................................................................ 12-3
12.3 Implementation Considerations ............................................................................................................... 12-3
12.3.1 Flood Protection Projects ......................................................................................................... 12-3
12.3.1.1 Indianola Avenue South of West 50th Street (MHN_72) .......................................... 12-4
12.3.1.2 Halifax Avenue South (MHN_84, MHN_3, MHN_4, MHN_56, MHN_89, MHN_55,
MHN_61, MHN_62, MHN_87, MHN_90, and MHN_2) .............................................. 12-4
12.3.1.3 Morningside/Weber Park (MS_26, MS_25, MS_41, MS_32, MS_44, MS_24,
MS_15, MS_52, MS_53, MS_2, MS_38, MS_40, MS_54, MS_31, MS_33, MS_39a,
and MS_39b) .............................................................................................................................. 12-6
12.3.1.4 Edinbrook Lane and Westbrook Lane (MHN_79) ....................................................... 12-7
12.3.1.5 North of Morningside Road between Lynn Avenue and Crocker Avenue
(MS_22) ......................................................................................................................................... 12-8
12.3.1.6 Branson Street between West 44th Street and Morningside Road (MS_3, MS_48,
and MS_7) .................................................................................................................................... 12-8
12.3.2 Construction/Upgrade of Water Quality Basins .............................................................. 12-9
13.0 Southeast Minnehaha Creek ...................................................................................................................................... 13-1
13.1 General Description of Drainage Area ................................................................................................... 13-1
13.1.1 Drainage Patterns ........................................................................................................................ 13-1
13.1.1.1 Lake Pamela ................................................................................................................................ 13-1
13.1.1.2 Minnehaha Creek South ........................................................................................................ 13-1
13.1.1.3 Melody Lake ............................................................................................................................... 13-2
13.2 Stormwater System Results ........................................................................................................................ 13-2
13.2.1 Hydrologic/Hydraulic Modeling Results ............................................................................ 13-2
13.2.2 Water Quality Modeling Results ............................................................................................ 13-3
13.3 Implementation Considerations ............................................................................................................... 13-3
13.3.1 Flood Protection Projects ......................................................................................................... 13-3
13.3.1.1 East Golf Terrace Heights Neighborhood ...................................................................... 13-4
13.3.1.2 Concord and West 58th Street (MHS_59, MHS_26, MHS_58, MHS_42, MHS_53,
and MHS_17) .............................................................................................................................. 13-5
13.3.2 Construction/Upgrade of Water Quality Basins .............................................................. 13-6
13.3.3 Stream Improvement Projects ................................................................................................ 13-7
13.3.3.1 Minnehaha Creek Reach 14 Stream Restoration ........................................................ 13-7
14.0 Northwest Minnehaha Creek ..................................................................................................................................... 14-1
14.1 General Description of Drainage Area ................................................................................................... 14-1
14.1.1 Drainage Patterns ........................................................................................................................ 14-1
14.1.1.1 TH 100 ........................................................................................................................................... 14-1
14.1.1.2 Hopkins ........................................................................................................................................ 14-1
14.1.1.3 Interlachen .................................................................................................................................. 14-1
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14.2 Stormwater System Results ........................................................................................................................ 14-2
14.2.1 Hydrologic/Hydraulic Modeling Results ............................................................................ 14-2
14.2.2 Water Quality Modeling Results ............................................................................................ 14-3
14.3 Implementation Considerations ............................................................................................................... 14-3
14.3.1 Flood Protection Projects ......................................................................................................... 14-3
14.3.1.1 Blake Road South and Spruce Road (HO_4) ................................................................. 14-4
14.3.2 Construction/Upgrade of Water Quality Basins .............................................................. 14-4
15.0 Issues and Implementation Program ...................................................................................................................... 15-1
15.1 Flood Protection and Runoff Management ......................................................................................... 15-1
15.1.1 Flood protection and runoff management infrastructure ........................................... 15-2
15.1.2 Flood protection and runoff management programs .................................................. 15-3
15.1.2.1 Assessing Risk ............................................................................................................................ 15-3
15.1.2.2 Communicating Risk ............................................................................................................... 15-3
15.1.2.3 Land Use Controls .................................................................................................................... 15-3
15.1.2.4 Technical Assistance ............................................................................................................... 15-4
15.1.3 Flood Risk Reduction Strategy ............................................................................................... 15-4
15.1.3.1 Implementation Approaches ............................................................................................... 15-4
15.1.3.2 Opportunity Identification/Prioritization........................................................................ 15-5
15.2 Clean Water .................................................................................................................................................... 15-20
15.2.1 Clean Water Infrastructure ..................................................................................................... 15-20
15.2.2 Clean Water Programs ............................................................................................................ 15-20
15.2.2.1 Community Engagement .................................................................................................... 15-21
15.2.2.2 Pollution Prevention ............................................................................................................. 15-21
15.2.2.3 Pollution Source Controls ................................................................................................... 15-22
15.2.2.4 Lake and Pond Management ............................................................................................ 15-23
15.2.3 Clean Water Strategy ............................................................................................................... 15-27
15.2.3.1 Implementation Approach ................................................................................................. 15-28
15.2.3.2 Opportunity Identification and Prioritization ............................................................. 15-28
15.3 Stormwater Infrastructure ......................................................................................................................... 15-30
15.3.1 Operation and Maintenance of Stormwater Systems ................................................. 15-31
15.3.1.1 Private Stormwater Facilities ............................................................................................. 15-31
15.3.1.2 Publicly Owned Stormwater Facilities ........................................................................... 15-31
15.3.1.3 Maintenance of Storm Sewer and Culvert Inlets ...................................................... 15-31
15.3.1.4 Maintenance of Ponding Facilities .................................................................................. 15-32
15.3.1.5 Riprap and Filter Areas......................................................................................................... 15-32
15.3.1.6 Adequacy of the Maintenance Program ...................................................................... 15-32
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15.4 Management Approach............................................................................................................................. 15-32
15.4.1 Coordination with Watershed Districts ............................................................................. 15-34
15.4.1.1 Regulation ................................................................................................................................. 15-34
15.4.1.2 Data and Information ........................................................................................................... 15-34
15.4.1.3 Land Use Planning Opportunities ................................................................................... 15-35
15.4.1.4 Implementation Partnership Opportunities ................................................................ 15-36
15.4.2 Development Review Process and Land Use Planning .............................................. 15-37
15.4.3 Prioritization ................................................................................................................................ 15-38
15.4.4 Resources ...................................................................................................................................... 15-39
15.4.5 Financial Considerations ......................................................................................................... 15-39
15.4.6 Utility funding ............................................................................................................................. 15-40
15.4.7 Policy Issues ................................................................................................................................. 15-41
15.5 Plan Update and Amendment Procedure .......................................................................................... 15-42
16.0 Wetlands ............................................................................................................................................................................ 16-1
16.1 City of Edina Wetlands Inventory—1999 .............................................................................................. 16-1
16.1.1 Delineation ..................................................................................................................................... 16-1
16.1.2 Dominant Vegetation ................................................................................................................ 16-2
16.1.3 Wetland Functional Assessment............................................................................................ 16-2
16.1.3.1 Hydrology .................................................................................................................................... 16-2
16.1.3.2 Vegetative Diversity ................................................................................................................ 16-2
16.1.3.3 Wildlife Habitat ......................................................................................................................... 16-3
16.1.3.4 Fishery Habitat .......................................................................................................................... 16-3
16.1.3.5 Flood/Stormwater Attenuation .......................................................................................... 16-3
16.1.3.6 Water Quality Protection ...................................................................................................... 16-3
16.1.3.7 Shoreline Protection ............................................................................................................... 16-3
16.1.3.8 Aesthetics/Recreation/Education and Science ............................................................ 16-4
16.1.4 Wetland Sensitivity to Stormwater Input ........................................................................... 16-4
16.2 MCWD FAW—2003 ....................................................................................................................................... 16-7
16.2.1 Delineation and Inventory ....................................................................................................... 16-7
16.2.2 Critical Wetland Resources ...................................................................................................... 16-7
16.2.3 Wetland Susceptibility to Stormwater ................................................................................ 16-8
16.2.4 Wetland Management Classification ................................................................................... 16-8
16.3 Circular 39 Wetland Classification ........................................................................................................... 16-8
16.3.1 Type 1: Seasonally Flooded Basin, Floodplain Forest ................................................... 16-8
16.3.2 Type 2: Wet Meadow, Fresh Wet Meadow, Wet to Wet-Mesic Prairie, Sedge
Meadow, and Calcareous Fen ................................................................................................ 16-9
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16.3.3 Type 3: Shallow Marsh ............................................................................................................... 16-9
16.3.4 Type 4: Deep Marsh .................................................................................................................... 16-9
16.3.5 Type 5: Shallow Open Water................................................................................................... 16-9
16.3.6 Type 6: Shrub Swamp; Shrub Carr, Alder Thicket ........................................................... 16-9
16.3.7 Type 7: Wooded Swamps; Hardwood Swamp, Coniferous Swamp ........................ 16-9
16.4 Cowardin Wetland Classification ........................................................................................................... 16-10
16.4.1 System............................................................................................................................................ 16-10
16.4.2 Subsystem .................................................................................................................................... 16-11
16.4.3 Class, Subclass ............................................................................................................................ 16-11
16.4.4 Water Regime ............................................................................................................................. 16-12
16.4.5 Special Modifiers ....................................................................................................................... 16-13
16.5 Public Waters ................................................................................................................................................. 16-13
17.0 References ......................................................................................................................................................................... 17-1
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List of Tables
Table 1.1 Strategies and Potential Actions for Addressing Local and Regional Flood Issues .............................. 1-3
Table 2.1 Summer (June-September) Average Total Phosphorus Concentrations for Edina Lakes................... 2-6
Table 2.2 City of Edina waterbodies on MPCA's 303(d) Impaired Waters List ........................................................... 2-8
Table 2.3 Fishery and Aquatic Invasive Species Information .......................................................................................... 2-12
Table 3.1 Source of the Best Available 1-Percent-Annual Chance Flood Elevations throughout the City
of Edina ................................................................................................................................................................................ 3-3
Table 3.2 Strategies and Potential Actions for Addressing Local and Regional Flood Issues ........................... 3-10
Table 4.1 Land Use Impervious Fraction Assumptions for Hydrologic Modeling ..................................................... 4-3
Table 4.2 Horton Infiltration Parameters ................................................................................................................................... 4-5
Table 4.3 Roughness Coefficient Assumptions ....................................................................................................................... 4-6
Table 4.4 Land Use Impervious Fraction Assumptions for Water Quality Modeling ............................................ 4-11
Table 4.5 Infiltration Assumptions for Water Quality Modeling ................................................................................... 4-13
Table 5.1 Major Watersheds within the Nine Mile Creek—North Drainage Basin ................................................... 5-1
Table 5.2 Watershed Modeling Results for Subwatersheds in the Nine Mile Creek—North Drainage
Basin .................................................................................................................................................................................. 5-10
Table 5.3 Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek—
North Drainage Basin.................................................................................................................................................. 5-15
Table 6.1 Major Watersheds within the Nine Mile Creek—Central Drainage Basin ................................................. 6-1
Table 6.2 Watershed Modeling Results for Subwatersheds in the Nine Mile Creek—Central Drainage
Basin ..................................................................................................................................................................................... 6-6
Table 6.3 Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek—
Central Drainage Basin .................................................................................................................................................. 6-9
Table 7.1 Major Watersheds within the Lake Cornelia/Lake Edina/Adam’s Hill Drainage Basin ......................... 7-1
Table 7.2 Watershed Modeling Results for Subwatersheds in the Lake Cornelia/Lake Edina/Adam’s Hill
Drainage Area ................................................................................................................................................................... 7-8
Table 7.3 Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Lake Cornelia/Lake
Edina/Adam’s Hill Drainage Area ........................................................................................................................... 7-12
Table 8.1 Major Watersheds within the Nine Mile Creek—South Drainage Basin ................................................... 8-1
Table 8.2 Watershed Modeling Results for Subwatersheds in the Nine Mile Creek—South Drainage
Basin ..................................................................................................................................................................................... 8-7
Table 8.3 Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek—
South Drainage Basin.................................................................................................................................................. 8-10
Table 9.1 Major Watersheds within the Nine Mile South Fork Drainage Basin ......................................................... 9-1
Table 9.2 Watershed Modeling Results for Subwatersheds in the Nine Mile South Fork Drainage Basin...... 9-8
Table 9.3 Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile South
Fork Drainage Basin ..................................................................................................................................................... 9-11
Table 10.1 Major Watersheds within the Southwest Ponds Drainage Basin .............................................................. 10-1
Table 10.2 Watershed Modeling Results for Subwatersheds in the Southwest Ponds Drainage Basin .......... 10-5
City of Edina 2018 Comprehensive Water Resources Management Plan
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Table 10.3 Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Southwest Ponds
Drainage Basin ............................................................................................................................................................... 10-7
Table 11.1 Major Watershed within the TH 169 North Drainage Area ......................................................................... 11-1
Table 11.2 Watershed Modeling Results for Subwatersheds in the TH 169 North Drainage Basin .................. 11-4
Table 11.3 Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the TH 169 North
Drainage Basin ............................................................................................................................................................... 11-5
Table 12.1 Major Watersheds within the Northeast Minnehaha Creek Drainage Basin ........................................ 12-1
Table 12.2 Watershed Modeling Results For Subwatersheds n the Northeast Minnehaha Creek Drainage
Basin ................................................................................................................................................................................ 12-10
Table 12.3 Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Northeast
Minnehaha Creek Drainage Basin ........................................................................................................................ 12-13
Table 13.1 Major Watersheds within the Southeast Minnehaha Creek Drainage Basin ........................................ 13-1
Table 13.2 Watershed Modeling Results For Subwatersheds n the Southeast Minnehaha Creek Drainage
Basin .................................................................................................................................................................................. 13-8
Table 13.3 Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Southeast
Minnehaha Creek Drainage Basin ........................................................................................................................ 13-11
Table 14.1 Major Watersheds within the Northwest Minnehaha Creek Drainage Basin ....................................... 14-1
Table 14.2 Watershed Modeling Results For Subwatersheds n the Northwest Minnehaha Creek Drainage
Basin .................................................................................................................................................................................. 14-5
Table 14.3 Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Northwest
Minnehaha Creek Drainage Basin .......................................................................................................................... 14-7
Table 15.1 Water Resources Implementation Program ...................................................................................................... 15-6
Table 15.2 Potential Implementation Activities (including Capital Improvements) ............................................... 15-12
Table 15.3 Level of Potential Lake Management Activity by Service Level ............................................................... 15-26
Table 15.4 City staff support activities and alternative methods related to Table 15.3 ....................................... 15-26
Table 15.5 Potential Funding Sources for Plan Implementation ................................................................................... 15-40
Table 16.1 Susceptibility of Wetlands to Degradation by Stormwater Impacts ........................................................ 16-5
Table 16.2 Management Recommendations for Each Wetland Sensitivity Classification ..................................... 16-6
Table 16.3 MnDNR Public Waters within Edina .................................................................................................................... 16-14
City of Edina 2018 Comprehensive Water Resources Management Plan
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List of Figures
Figure 2.1 Major Drainage Areas ................................................................................................................................................. 2-15
Figure 2.2 Land Use Classification ............................................................................................................................................... 2-16
Figure 2.3 Edina Soils Classification ............................................................................................................................................ 2-17
Figure 2.4 Water Quality Monitoring Stations ....................................................................................................................... 2-18
Figure 2.5 Edina Parks and Recreational Areas ...................................................................................................................... 2-19
Figure 2.6 Threatened and Endangered Species ................................................................................................................... 2-20
Figure 5.1 Nine Mile Creek—North Drainage Basin ............................................................................................................ 5-31
Figure 5.2 Nine Mile Creek—North Major Watersheds...................................................................................................... 5-32
Figure 5.3 Nine Mile Creek—North Hydraulic Model Results ......................................................................................... 5-33
Figure 5.4 Nine Mile Creek—North Water Quality Modeling Results .......................................................................... 5-34
Figure 6.1 Nine Mile Creek—Central Drainage Basin .......................................................................................................... 6-19
Figure 6.2 Nine Mile Creek—Central Major Watersheds ................................................................................................... 6-20
Figure 6.3 Nine Mile Creek—Central Hydraulic Model Results ....................................................................................... 6-21
Figure 6.4 Nine Mile Creek—Central Water Quality Modeling Results........................................................................ 6-22
Figure 7.1 Lake Cornelia/Lake Edina/Adam's Hill Drainage Basin .................................................................................. 7-30
Figure 7.2 Lake Cornelia/Lake Edina/Adam's Hill Major Watersheds ........................................................................... 7-31
Figure 7.3 Lake Cornelia/Lake Edina/Adam's Hill Hydraulic Model Results ............................................................... 7-32
Figure 7.4 Lake Cornelia/Lake Edina/Adam's Hill Water Quality Modeling Results ................................................ 7-33
Figure 8.1 Nine Mile Creek—South Drainage Basin ............................................................................................................ 8-22
Figure 8.2 Nine Mile Creek—South Major Watersheds ..................................................................................................... 8-23
Figure 8.3 Nine Mile Creek—South Hydraulic Model Results ......................................................................................... 8-24
Figure 8.4 Nine Mile Creek—South Water Quality Modeling Results .......................................................................... 8-25
Figure 9.1 Nine Mile South Fork Drainage Basin .................................................................................................................. 9-22
Figure 9.2 Nine Mile South Fork Major Watersheds ............................................................................................................ 9-23
Figure 9.3 Nine Mile South Fork Hydraulic Model Results ............................................................................................... 9-24
Figure 9.4 Nine Mile South Fork Water Quality Modeling Results ................................................................................ 9-25
Figure 10.1 Southwest Ponds Drainage Basin ........................................................................................................................ 10-13
Figure 10.2 Southwest Ponds Major Watersheds .................................................................................................................. 10-14
Figure 10.3 Southwest Ponds Hydraulic Model Results ..................................................................................................... 10-15
Figure 10.4 Southwest Ponds Water Quality Modeling Results ...................................................................................... 10-16
Figure 11.1 TH 169 North Drainage Basin .................................................................................................................................. 11-7
Figure 11.2 TH 169 North Major Watersheds ........................................................................................................................... 11-8
Figure 11.3 TH 169 North Hydraulic Model Results ............................................................................................................... 11-9
Figure 11.4 TH 169 North Water Quality Modeling Results.............................................................................................. 11-10
Figure 12.1 Northeast Minnehaha Creek Drainage Basin .................................................................................................. 12-26
Figure 12.2 Northeast Minnehaha Creek Major Watersheds ........................................................................................... 12-27
Figure 12.3 Northeast Minnehaha Creek Hydraulic Model Results ............................................................................... 12-28
City of Edina 2018 Comprehensive Water Resources Management Plan
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Figure 12.4 Northeast Minnehaha Creek Water Quality Modeling Results ................................................................ 12-29
Figure 13.1 Southeast Minnehaha Creek Drainage Basin .................................................................................................. 13-22
Figure 13.2 Southeast Minnehaha Creek Major Watersheds ........................................................................................... 13-23
Figure 13.3 Southeast Minnehaha Creek Hydraulic Model Results ............................................................................... 13-24
Figure 13.4 Southeast Minnehaha Creek Water Quality Modeling Results ................................................................ 13-25
Figure 14.1 Northwest Minnehaha Creek Drainage Basin ................................................................................................. 14-14
Figure 14.2 Northwest Minnehaha Creek Major Watersheds .......................................................................................... 14-15
Figure 14.3 Northwest Minnehaha Creek Hydraulic Model Results .............................................................................. 14-16
Figure 14.4 Northwest Minnehaha Creek Water Quality Modeling Results ............................................................... 14-17
Figure 15.1 City-Owned Property ................................................................................................................................................ 15-43
Figure 16.1 Wetlands within the City of Edina ........................................................................................................................ 16-16
Figure 16.2 Wetlands Classification ............................................................................................................................................ 16-17
List of Appendices, Attachments, or Exhibits
Appendix A City of Edina Imperviousness Assumptions for Stormwater Modeling
Appendix B Summary of Nine Mile Creek and Minnehaha Creek Modeling Approach
Appendix C Legacy Flood Protection Projects
Appendix D List of Pond Improvement Recommendations
Appendix E Aquatic Vegetation Prioritization List
Appendix F Modified Minnesota Routine Assessment Method for Evaluating Wetland Functions
(MnRAM) Version 2.0
Appendix G GIS Wetlands Inventory Database
City of Edina 2018 Comprehensive Water Resources Management Plan xv
Certifications
I hereby certify that this report was prepared by me or under my direct supervision and that I am a duly
License Professional Engineer under the laws of the State of Minnesota.
5/24/2018
Janna M. Kieffer
PE #: 43571
Date
City of Edina 2018 Comprehensive Water Resources Management Plan xvi
Acronyms
Acronym Description
BMPs Best Management Practices
CAMP Citizen Assisted Monitoring Program
CFS Cubic Feet per Second
CIP Capital Improvement Program
CWA Clean Water Act
CWRMP Comprehensive Water Resources Management Plan
EPA United States Environmental Protection Agency
FAW Functional Assessment of Wetlands (MCWD)
FEMA Federal Emergency Management Agency
GIS Geographic Information Systems
IBI Index of Biotic Integrity
ISTS Individual Sewage Treatment Systems
LGU Local Government Unit
MCWD Minnehaha Creek Watershed District
MnRAM Minnesota Routine Assessment Method
MnDNR Minnesota Department of Natural Resources
MnDOT Minnesota Department of Transportation
MPCA Minnesota Pollution Control Agency
MS4 Municipal Separate Storm Sewer System
MUSA Metropolitan Urban Service Area
NGVD29 National Geodetic Vertical Datum of 1929
NMCWD Nine Mile Creek Watershed District
NOAA National Oceanic and Atmospheric Administration
NPDES National Pollutant Discharge Elimination System
NURP Nationwide Urban Runoff Program
NWI National Wetlands Inventory
PWI Public Waters Inventory
RCP Reinforced-Concrete Pipe
SCS Soil Conservation Service
SSURGO Soil Survey Geographic Database
SWMM Stormwater Management Model
SWPPP Stormwater Pollution Prevent Plan/Program
TBD To Be Determined
City of Edina 2018 Comprehensive Water Resources Management Plan
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TH Trunk Highway
TMDL Total Maximum Daily Load
TSS Total Suspended Solids
UAA Use Attainability Analysis
USFWS United States Fish and Wildlife Service
VIC Voluntary Investigation and Clean-up
WCA Wetland Conservation Act
WMO Watershed Management Organization
City of Edina 2018 Comprehensive Water Resources Management Plan 1-1
1.0 Executive Summary
This plan provides the City of Edina with a Comprehensive Water Resource Management Plan (CWRMP).
The plan was developed to address current and future stormwater issues, especially those related to
future development and redevelopment. The plan addresses stormwater runoff management and flood
control, water quality management, and wetlands protection through establishment of stormwater
planning policies and recommendations.
The City of Edina developed its first CWRMP in 2003. The original CWRMP is referenced throughout this
document as the 2003 CWRMP. The CWRMP was then updated in 2011.
This CWRMP is composed of Section 1.0: Executive Summary and 16 additional sections, which are
described as follows:
Section 2.0: Introduction and Physical Setting—presents background information regarding
the City, general watershed information, and plan purposes.
Section 3.0: Policies for Water Resources Management presents background information,
goals, policies and design standards covering runoff management and flood control, water quality
management, erosion and sediment control, wetlands, floodplain management, recreation,
habitat and shoreland management, groundwater, the City’s education goals, and National
Pollutant Discharge Elimination System (NPDES) considerations.
Section 4.0: Methodology for Modeling—describes the data, methods and assumptions used
for the stormwater analyses.
Section 5.0 through Section 14.0: Major Drainage Area Descriptions and
Recommendations—describes the general drainage area, drainage patterns within the area, the
stormwater system analysis and results, and implementation recommendations for each of the
following 10 major drainage areas in the City: Nine Mile Creek- North, Nine Mile Creek- Central,
Nine Mile Creek- South, Lake Cornelia/Lake Edina/Adam’s Hill, Nine Mile South Fork, Southwest
Ponds, Trunk Highway (TH) 169 North, Northeast Minnehaha, Southeast Minnehaha, and
Northwest Minnehaha.
Section 15.0: Issues and Implementation Program—describes the programs and activities
that support each of the core services (runoff management, flood control, and clean water
services) and some of the policy issues around the provision and growth of service. This chapter
also discusses resources, financial considerations, and implementation priorities.
City of Edina 2018 Comprehensive Water Resources Management Plan 1-2
Section 16.0: Wetlands—Discusses the wetland inventories completed for the City of Edina and
the assessment methodologies and results.
Section 17.0: References
1.1 Problems, Issues, and Potential Solutions
This section summarizes the City’s 2018 - 2028 water resources implementation program, and potential
stormwater management improvements identified in Section 5.0 through Section 14.0 of the plan.
1.1.1 Water Resources Implementation Program
This plan serves as a master plan for the City’s water resources management and storm drainage system.
The City will work with residents to implement structural (capital) improvements and non-structural
programs to address existing water resource problems within the City and to prevent future problems
from occurring. The implementation program identifies the programs and improvements, and provides
cost estimates for budgeting purposes. Table 15.1 presents the City’s water resource-related
implementation program, which includes the City’s non-structural (administration) programs and
structural (capital) improvement program. Prioritization of the projects listed in the table will occur as part
of the forthcoming Clean Water Strategy and Flood Risk Reduction Strategy.
1.1.2 Runoff Management and Flood Control
The hydrologic and hydraulic modeling analyses of the current stormwater system identified several areas
throughout the City where the desired 1-percent-annual chance level of protection may not be provided.
These problem areas and potential solutions are discussed in detail in Section 5.0 through Section 14.0
and are summarized and prioritized in Table 15.2. In addition to evaluating the level of protection
provided by the current stormwater system, the level of service provided was also evaluated. From this
analysis, it was determined that the storm sewer throughout many areas of the City is not currently
providing the desired 10-year level of service. The areas where the storm sewer does not offer sufficient
capacity and street flow occurs during a 10-percent-annual-chance event are depicted in figures in
Section 5.0 through Section 14.0 .The capacity of these storm sewer systems should be evaluated and
upgraded as opportunities arise.
1.2 Flood Risk Reduction Strategy
As part of this 10-year plan, the City of Edina will develop a Flood Risk Reduction Strategy that outlines a
plan for working toward reducing flood risk, where appropriate, and meeting its stormwater management
goals for providing a 1-percent-annual-chance (100-year) level of protection where possible. The strategy
will identify and characterize flood problems throughout the city and identify strategies and infrastructure
improvements to address flood-prone areas. The strategy will include preparation of planning-level cost
estimates to help understand the potential financial investment required to meet the City’s flood
protection goals and the anticipated timeframe for implementation.
City of Edina 2018 Comprehensive Water Resources Management Plan
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The Flood Risk Reduction Strategy will detail the City’s approach to addressing flood-prone areas based
on implementation categories described in Section 15.1.3.1.
The Flood Risk Reduction Strategy will focus on identification and prioritization of flood reduction efforts.
The City will seek to maximize cost effectiveness and capitalize on coinciding opportunities, such as
planned street reconstruction, redevelopment, availability of land, and other planned infrastructure
improvement projects. Consideration will also be given to achieving additional “co-benefits”, such as
water quality improvements, open space expansion, and wildlife habitat improvement.
When completed, the Flood Risk Reduction Strategy will be included as an amendment to this CWRMP.
The City recognizes that addressing regional and local flood issues throughout the community will require
multiple strategies and many actions implemented over a generational time frame. The City will employ
the strategies and associated actions summarized in Table 1.1 for addressing flood issues.
Table 1.1 Strategies and Potential Actions for Addressing Local and Regional Flood Issues
Strategies Potential Actions
Modify the flood
Plan, preserve and reclaim flood storage (new public and private stormwater
plans, deeds, easements, open space)
Maintain and increase green space
Maintain and increase storage (ponds, underground chambers, streets,
depressions)
Protect flow paths and emergency overflows
Manipulate timing of peak flow
Divert water
Control rate of peak flow
Detain and slowly release flow
Reuse water for beneficial purposes
Employ Green Infrastructure (GI) and Low Impact Development (LID) standards
Modify susceptibility Elevate structures
Reduce impacts
Floodproof structures
Enforce substantial improvement limits
Elevate utilities
Encourage flood insurance
Encourage preparedness planning
Encourage resilient landscaping
Provide risk audits
Limit infiltration and inflow to the sanitary system
Maintaining existing floodplain infrastructure
City of Edina 2018 Comprehensive Water Resources Management Plan
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1.3 Clean Water Strategy
As part of this 10-year plan, the City of Edina will develop a clean water implementation strategy that
outlines a plan for working toward meeting its clean water goals. The strategy will address the City’s
approach to meeting the pollutant reduction targets identified through the TMDL and WRAPS process.
The strategy will also determine pollutant load reduction targets for nondegradation of water bodies that
are not impaired and identify an approach for achieving these stormwater management targets. The clean
water implementation strategy will be a 5-year strategy that identifies regular “good housekeeping”
stormwater practices and clean water capital improvement projects (CIP) to achieve the goals, including
quantification of pollutant removals and preparation of planning-level cost estimates. This information will
be used for planning, as well as assessment of cost-benefit for project prioritization. The implementation
strategy will be developed in coordination with street reconstruction projects, redevelopment, and other
opportunities. Annual or biennial reporting will be included in the strategy to quantify movement toward
the City’s goals and track activities for the City’s annual SWPPP and MS4 reporting.
The Clean Water Strategy will define clean water goals, the cost and pace of achievement, and plan
implementation opportunities based on implementation categories described in Section 15.2.3.1.
When completed, the Clean Water Strategy will be included as an amendment to this CWRMP.
Each of the clean water improvement opportunity categories identified above have opportunities for
partnership with other entities, such as private land owners, watershed districts, non-profit organizations,
or other local governmental entities.
City of Edina 2018 Comprehensive Water Resources Management Plan
2-1
2.0 Introduction and Physical Setting
2.1 Plan Purposes
This plan provides the City of Edina with a Comprehensive Water Resource Management Plan (CWRMP).
The plan was developed to address current and future stormwater issues, especially those related to
future development and redevelopment. The plan addresses stormwater runoff management and flood
control, water quality management, and wetlands protection through establishment of stormwater
planning policies and recommendations.
The first goal of this CWRMP is to provide stormwater runoff management and flood control. Design
criteria have been adopted to ensure that a proper level of service for stormwater management and level
of protection from flooding, per the 1969 Floodplain Management Act, is provided to residents of the
City. The established design criteria are discussed in Section 3.1. The current storm sewer system
throughout the City has been analyzed using computer models and recommendations to improve runoff
management and flood control have been made. Discussion on the stormwater analyses and the resulting
implementation recommendations is included in Section 4.0 through Section 14.0.
The second goal of the CWRMP is to provide water quality management for the water bodies throughout
the City. Water quality management policies and design standards have been established to protect the
water quality of the waterbodies within the City. These policies and design criteria are discussed in
Section 3.3. A water quality model was used to simulate the generation and transport of pollutants
through the waterbodies within the City. The model results were used to make recommendations for
upgrades to water quality basins throughout the City to maintain and improve the pollutant removal
efficiency from these basins. This analysis and the resulting implementation recommendations are
discussed in Section 4.0 through Section 14.0.
The third goal of the CWRMP is to provide wetland protection throughout the City. The City of Edina’s
goal is to achieve no net loss of wetlands, including acreage, functions, and values. To achieve this goal,
policies have been established to protect the wetlands within the City. These policies are included in
Section 3.5. To provide a basis for wetland protection efforts, an inventory and assessment of all the
wetlands within the City was completed. The wetland inventory and assessment identified wetland
location, size, type, wetland classification, dominant wetland vegetation, function, and value for each
wetland. General management recommendations are included based on the wetland sensitivity to
stormwater degradation. The inventory and assessment is discussed in Section 16.0.
This plan will assist the City of Edina in defining and implementing a comprehensive and environmentally
sound system of surface water management. It is intended to be used as a tool to:
1. Plan for projects and other water management activities so as to correct existing problems and
prevent foreseeable future problems from occurring.
City of Edina 2018 Comprehensive Water Resources Management Plan
2-2
2. Assist the City in considering water resource impacts resulting from variances to the City’s long-
range land use plan.
3. Enable the City to grow/redevelop in a systematic and orderly manner while protecting its vital
water resources.
In order to accomplish these objectives, the plan considers a specific array of land uses within the City
limits. If and when land uses change, this plan provides the means to (1) address the proposed changes;
(2) determine the impact of the changes on the City’s infrastructure, flooding, and natural resources; and
(3) determine the actions needed within the proposed areas of land use change to prevent undesirable
impacts.
2.2 Physical Setting
2.2.1 Drainage Patterns
The City of Edina covers an area of approximately 16 square miles. There are two stream systems that flow
through the City: Nine Mile Creek and Minnehaha Creek. The northeast corner of the City drains to
Minnehaha Creek, which enters the City limits northwest of West 44th Street and Trunk Highway (TH) 100
and flows in a southeasterly direction through the City, exiting
near West 54th Street and York Avenue. The southwest corner
of the City drains to the South Fork of Nine Mile Creek
through a series of storm sewer networks, ditches, and
stormwater detention basins. The remainder of the City drains
to the North Fork of Nine Mile Creek, which enters the Edina
City limits in the northwest corner of the City near the
intersection of TH 169 and Londonderry Road and meanders in a southeasterly direction through the City
and exits the City limits near the intersection of TH 100 and Interstate 494 (I-494).
For the purposes of this study, the City was divided into several major drainage areas based on drainage
patterns. These drainage areas are depicted in Figure 2.1 and listed below:
• Nine Mile Creek- North
• Nine Mile Creek- Central
• Lake Cornelia/Lake Edina/Adam’s Hill Pond
• Nine Mile Creek- South
• Nine Mile South Fork
• Southwest Ponds
• TH 169 North
• Northeast Minnehaha Creek
• Southeast Minnehaha Creek
• Northwest Minnehaha Creek
Various maps related to the City of
Edina can be found online at the
City’s “Maps” page:
https://www.edinamn.gov/894/Maps
City of Edina
2018 Comprehensive Water Resources Management Plan
2-3
Section 5.0 through Section 14.0 discuss the drainage patterns within each of these drainage areas and
describe the recommended stormwater system improvements for each area. In some cases, the drainage
areas may include portions of adjoining cities, including Hopkins, Minnetonka, Eden Prairie, Bloomington,
Richfield, and Minneapolis. The 10 drainage basins listed above were subdivided into major watersheds
and subwatersheds. Watershed divides were originally determined as part of the 2003 CWRMP using air-
flown 2-foot topographic data. For this plan update, watershed divides were reviewed and, in some cases,
were updated using newer data topographic data (2011 MnDNR LiDAR elevation data).
2.2.2 Watershed Management Organizations
Edina lies within two major watersheds: the Minnehaha Creek watershed and Nine Mile Creek watershed.
As a result, two watershed management organizations cover Edina, each with its own governing body.
Additional information on the Minnehaha Creek Watershed District and Nine Mile Creek Watershed
District is provided below.
2.2.2.1 Minnehaha Creek Watershed District
The Minnehaha Creek Watershed District (MCWD) spans approximately 180 square miles and consists of
27 cities and three townships on the western edge of the Twin Cities area. The watershed includes eight
major creeks, including Minnehaha Creek which meanders through the northeastern part of Edina. The
MCWD also includes 129 lakes, including Lake Harvey and Melody Lake, and thousands of wetlands. The
MCWD adopted their most recent watershed management plan (Minnehaha Creek Watershed District
Watershed Management Plan) on January 11, 2018.
More information is available at the MCWD website: www.minnehahacreek.org.
2.2.2.2 Nine Mile Creek Watershed District
The Nine Mile Creek Watershed District (NMCWD) is approximately 50 square miles and encompasses the
land area draining to Nine Mile Creek, including portions of Bloomington, Eden Prairie, Edina, Hopkins,
Minnetonka, and Richfield. Portions of the North Fork and South Fork of Nine Mile Creek flow through
Edina. The NMCWD also includes over 20 lakes, including Lake Edina, Lake Cornelia, Arrowhead Lake,
Indianhead Lake, Hawkes Lake, Highlands Lake, and Mirror Lake, and many wetlands. The NMCWD
adopted their most recent watershed management plan (Nine Mile Creek Watershed District Water
Management Plan) on October 18, 2017.
More information is available at the NMCWD’s website: http://www.ninemilecreek.org/
2.2.3 Land Use
The city of Edina is fully urbanized. Less than 1 percent of the developable area within the city, not
including wetland, floodplain, or park land uses, remains available for development. Figure 2.2 shows the
land use classifications for the city. The 2009 Edina Comprehensive Plan provides additional information
about the existing and projected (2020) land uses in the city. An updated projected land use map (2030)
will be prepared as part of the City’s upcoming comprehensive plan effort. The projected 2030 land use
map will be provided online via the City’s “Maps” page, when available.
City of Edina 2018 Comprehensive Water Resources Management Plan
2-4
2.2.4 Soils
The infiltration capacity of soils affects the amount of direct runoff resulting from rainfall. Soils with a
higher infiltration rate have a lower runoff potential. Conversely, soils with low infiltration rates produce
high runoff volumes and high peak runoff rates. According to the Hennepin County soil survey, the
underlying soils in the City of Edina are predominantly classified as hydrologic soil group B, with moderate
infiltration rates. The underlying soils in the southern portions of the City are classified as hydrologic soil
group A, characterized by high infiltration rates. The underlying soils surrounding the floodplain of Nine
Mile Creek and Minnehaha Creek and around many of the natural wetlands within the City are classified
as hydrologic soil group D, with very slow infiltration rates. Figure 2.3 depicts the hydrologic soils group
classification for soils within the City of Edina.
2.2.5 Topography
The topography of the City varies from relatively flat land along portions of Nine Mile Creek and
Minnehaha Creek to very hilly land in the southwest portion of the City. Generally the topography
throughout the City consists of moderately rolling hills. The elevations generally vary from 980 to 880 feet
(National Geodetic Vertical Datum of 1929 or NGVD 29) at the divide between the Minnehaha Creek and
Nine Mile Creek watersheds to elevations between 812 and 850 feet where each creek exits the City.
The City of Edina has older 2-foot contour data (Markhurd, 2000) coverage for the entire City; this
information was used for the 2003 CWRMP and is available from the City Engineering Department. The
MnDNR has newer (2011) and higher resolution Light Detection and Ranging (LiDAR) topographic data
that was used for this plan update.
2.2.6 Water Quality
2.2.6.1 Water Quality Monitoring
2.2.6.2 Lakes
While the City of Edina does not have a water quality monitoring program, several lakes and streams
within the city are monitored periodically by watershed districts and volunteer programs. The NMCWD
conducts periodic monitoring of several lakes within the city, including Arrowhead Lake, Lake Cornelia,
Lake Edina, Indianhead Lake, and Mirror Lake. The NMCWD’s lake monitoring program includes analysis
of a range of parameters, including phosphorus, nitrogen, chlorophyll a, chlorides, clarity/transparency,
temperature, pH, specific conductivity and dissolved oxygen. In addition, the NMCWD typically completes
phytoplankton (algae) and zooplankton monitoring and conducts early-summer and late-summer aquatic
plant (macrophyte) surveys.
In addition to the lake monitoring data collected by the NMCWD, water quality data has also been
collected for several lakes by citizen monitoring volunteers as part of the Metropolitan Council’s Citizen-
Assisted Monitoring Program (CAMP). The lakes within the city that have been monitored as part of CAMP
include Pamela, Cornelia, Edina, Harvey, and Hawkes lakes. The locations of these lakes are shown in
Figure 2.4. Volunteer monitoring through the CAMP program has historically been funded by the
watershed districts.
City of Edina 2018 Comprehensive Water Resources Management Plan
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A summary of the historic summer average total phosphorus concentrations for the monitored lakes in
Edina is provided in Table 2.1. The summary reflects the data collected by both the NMCWD and the
Metropolitan Council CAMP over the most recent ten years when data was collected. As can be seen in
the table, the available data is limited for many of the Edina lakes. It should be noted that lakes and ponds
are dynamic, so that relatively infrequent sampling cannot provide a complete picture of the status of the
water body in question. The situation is further complicated by the impossibility of inferring statistically
significant trends from relatively few water quality sampling results. A minimum of about 10 (summer
average) data points is thought to be required to reliably identify a water quality trend.
2.2.6.3 Creeks
The NMCWD has two continuous flow monitoring stations within or near Edina; one along the North Fork
of Nine Mile Creek at the Metro Boulevard crossing, and another along the South Fork of Nine Mile Creek
at the 78th Street crossing, just south of the city boundary with Bloomington (Figure 2.4). The monitoring
stations collect data on stream flow and several water quality parameters, including turbidity, nutrients,
and chlorides. The water quality monitoring data is available from the NMCWD upon request.
The MCWD has two monitoring stations along Minnehaha Creek; one near the intersection of West 56th
Street and Woodland Drive, just west of France Avenue, and another at Mill Pond, upstream of Browndale
Dam. The west 56th Street station has consistently been monitored since 2009. MCWD had a third station,
just below Browndale Dam, beginning in 1996. This station was discontinued in 2016.
Continuous stream level data is collected to determine stream flow at the Mill Pond station. Instantaneous
discharge and water quality samples are collected bi-weekly at the West 56th Street station. Samples are
analyzed bi-weekly for total phosphorus and total suspended solids (TSS), and monthly for chloride
during the months of March-October. E. coli is collected weekly during the months of April – October.
Samples are analyzed monthly during the winter (November-February).
City of Edina 2018 Comprehensive Water Resources Management Plan
2-6
Table 2.1 Summer (June-September) Average Total Phosphorus Concentrations for Edina Lakes
Lake Year
Summer Average
Total Phosphorus
Concentration
(µg/L)
Data Collection Entity 1,2
North Lake Cornelia
2007 211 MCES CAMP
2008 153 NMCWD and MCES CAMP
2009 111 MCES CAMP
2013 165 NMCWD and MCES CAMP
2014 84 MCES CAMP
2015 139 NMCWD and MCES CAMP
2016 114 NMCWD
Average 144
South Lake Cornelia
2008 150 NMCWD
2013 114 NMCWD
2015 122 NMCWD
2016 149 NMCWD
Average 134
Mirror Lake
2004 119 NMCWD
2012 104 NMCWD
Average 112
Arrowhead Lake
2011 52 NMCWD
2014 65 NMCWD
Average 58
Indianhead Lake
2011 53 NMCWD
2014 61 NMCWD
Average 57
Harvey Lake 2011 53 CAMP
Average 53
Pamela Lake
2004 78 CAMP
2005 73 CAMP
Average 76
Lake Edina
2008 120 NMCWD
2012 146 NMCWD
2015 85 NMCWD
Average 117
1 Metropolitan Council Environmental Services (MCES) Citizen Assisted Monitoring Program (CAMP) for
Lakes
2 Nine Mile Creek Watershed District (NMCWD) lake monitoring program
City of Edina 2018 Comprehensive Water Resources Management Plan
2-7
2.2.6.4 Impaired Waters and Total Maximum Daily Loads
The federal Clean Water Act (CWA) requires states to adopt water quality standards to protect the nation’s
waters. Water quality standards designate beneficial uses for each waterbody and establish criteria that
must be met within the waterbody to maintain the water quality necessary to support its designated
use(s). Section 303(d) of the CWA requires each state to identify and establish priority rankings for waters
that do not meet the water quality standards. The list of impaired waters, or 303(d) list, is updated by the
state every two years.
For impaired waterbodies, the CWA requires the development of a total maximum daily load (TMDL). A
TMDL is a threshold calculation of the amount of a pollutant that a waterbody can receive and still meet
water quality standards. A TMDL establishes the pollutant loading capacity within a waterbody and
develops an allocation scheme amongst the various contributors, which include point sources, non-point
sources and natural background, as well as a margin of safety. As a part of the allocation scheme a waste
load allocation is developed to determine allowable pollutant loadings from individual point sources
(including loads from storm sewer networks), and a load allocation also establishes allowable pollutant
loadings from non-point sources and natural background levels in a waterbody.
Impaired waters located within the City of Edina, as identified by the MPCA’s 2016 Proposed Impaired
Waters List, include: Lake Cornelia (North Basin), Lake Edina, Nine Mile Creek and Minnehaha Creek. The
Draft 2018 Impaired Waters list also includes Lake Cornelia (South Basin) and the portion of Nine Mile
Creek between Metro Boulevard and an unnamed wetland. These waterbodies are listed in Table 2.2
along with the affected MPCA designated use, the pollutant or stressor that is not meeting the MPCA
water quality criteria, and the MPCA target for starting and completing the TMDL process.
The MPCA is using a systematic watershed approach to address impaired waters and TMDLs, whereas
intensive water quality monitoring and assessments are being conducted in each of the states 80 major
watersheds during a 10-year cycle. The MPCA developed a process termed Watershed Restoration and
Protection Strategy (WRAPS) to identify and address water quality threats in each major watershed. The
four primary steps of the WRAPS process include 1) monitoring water quality and collecting data,
2) assessing the data, 3) developing strategies to restore and protect water bodies within the watershed,
and 4) conducting restoration and protection projects. TMDLs are conducted for impaired water bodies as
part of the WRAPS process.
The MPCA initiated a WRAPS process in the Nine Mile Creek watershed in 2016, with completion
anticipated in 2017. The City of Edina is participating in the process as a stakeholder. An anticipated
outcome of the process is an approved TMDL for Lake Cornelia (North and South basins), Lake Edina, and
Nine Mile Creek. The MPCA will likely conduct a WRAPS process (and TMDL) in the Minnehaha Creek
watershed during 2020-2024, based on the schedule identified in the 2016 Proposed Impaired Waters list.
Following TMDL completion, the TMDL requirements will be incorporated into the City’s NPDES Phase II
MS4 permit. It may also be necessary to amend the City’s CWRMP to incorporate future TMDL
requirements.
City of Edina 2018 Comprehensive Water Resources Management Plan
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Table 2.2 City of Edina waterbodies on MPCA's 303(d) Impaired Waters List
Reach/Waterbody Description Affected Use Pollutant or Stressor
Target Dates for
Starting/Completing
TMDL
Lake Cornelia (North
Basin) 1 Aquatic
Recreation
Nutrient/Eutrophicat
ion Biological
Indicators
2014/2019
Lake Cornelia (South
Basin)2 Aquatic
Recreation
Nutrient/Eutrophicat
ion Biological
Indicators
2014/2019
Lake Edina1 Aquatic
Recreation
Nutrient/Eutrophicat
ion Biological
Indicators
2014/2019
Nine Mile Creek1 Headwaters to
Minnesota River Aquatic Life Fish Bioassessments 2014/2019
Nine Mile Creek2
Metro Boulevard to
end of unnamed
wetland
Aquatic Life
Aquatic
macroinvertebrate
bioassessments
2024/2029
Nine Mile Creek2
Metro Boulevard to
end of unnamed
wetland
Aquatic Life Fish Bioassessments 2024/2029
Minnehaha Creek1 Lake Minnetonka to
Mississippi River Aquatic Life
Aquatic
Macroinvertebrate
Bioassessments
2020/2024
Minnehaha Creek1 Headwaters to
Minnesota River Aquatic Life Fish Bioassessments 2020/2024
Minnehaha Creek1 Lake Minnetonka to
Mississippi River
Aquatic
Recreation Fecal Coliform 2007/2012
Minnehaha Creek1 Lake Minnetonka to
Mississippi River Aquatic Life Chloride 2007/2012
Minnehaha Creek1 Lake Minnetonka to
Mississippi River Aquatic Life Dissolved Oxygen 2020/2024
1 Information based on the 2016 proposed impaired waters list, sent to USEPA for approval on January 4, 2017.
2 Information based on the draft 2018 impaired waters list, submitted for EPA approval on April 4, 2018.
Nine Mile Creek
Nine Mile Creek is currently on the 303(d) Impaired Waters List for an aquatic life impairment due to a fish
biota impairment. In 2009, the MPCA and NMCWD began development of a TMDL to address the biotic
impairment. The City of Edina participated as a stakeholder in the TMDL process. The TMDL included a
biological stressor identification study to determine the causes of the Nine Mile Creek biological
impairment for fish (MPCA, 2010). The study concluded:
City of Edina 2018 Comprehensive Water Resources Management Plan
2-9
• The probable cause of impairment on the South Fork of Nine Mile Creek is inadequate dissolved
oxygen. Although the impairment can be caused by numerous stressors, the data suggests that
inadequate dissolved oxygen is the most prominent of the stressors, followed by excess sediment
and inadequate base flow.
• The probable causes of impairment on the North Fork of Nine Mile Creek are inadequate
dissolved oxygen and excess sediment.
In 2004, the MPCA determined that Nine Mile Creek did not meet the chloride standard for streams and
listed Nine Mile Creek as impaired. A TMDL was completed in 2010 to identify management measures to
reduce chloride levels in Nine Mile Creek. The study determined that a 63% reduction in the existing
watershed chloride load estimated for Nine Mile Creek would be required, to be achieved through
management of road salt inputs from both road authorities and commercial and private applicators.
Minnehaha Creek
Minnehaha Creek is currently on the 303(d) list for several impairments, including an aquatic life
impairment due to fish biota, aquatic macroinvertebrates, chloride, and dissolved oxygen and an aquatic
recreation impairment due to fecal coliform.
Lake Hiawatha, located on Minnehaha Creek downstream of the City of Edina, is also on the impaired
waters list for excess nutrients and eutrophication biological indicators. The MPCA and MCWD initiated
the TMDL development process in 2009 to address an E. coli bacteria impairment (originally listed as fecal
coliform) in Minnehaha Creek and a nutrient impairment in downstream Lake Hiawatha. The City of Edina
participated in the stakeholder process. The TMDL, approved in 2014, includes a categorical E. coli
wasteload allocation for all MS4s within the watershed and a 50% total phosphorus load reduction target
to Minnehaha Creek (MPCA, 2013).
The chloride impairment for Minnehaha Creek is being addressed as part of the Twin Cities Metropolitan
Area Chloride Total Maximum Daily Load Study (MPCA, 2016).
The MPCA’s 2016 proposed 303(d) list also includes an aquatic life impairment for Minnehaha Creek due
to low dissolved oxygen levels.
Lake Cornelia
In 2004–2005, the NMCWD completed a draft use attainability analysis (UAA) for Lake Cornelia, which is a
scientific assessment of a water body’s physical, chemical, and biological condition (Barr Engineering,
2006). The study included a water quality assessment and prescription of protective and/or remedial
measures for the lake and its tributary watershed. In 2010, the NMCWD updated the study based on
additional lake water quality data, to verify the conclusions of the draft UAA and evaluate several
additional remedial measures to improve lake water quality.
Lake Cornelia (North Basin) is included on the MPCA’s 2016 Proposed Impaired Waters list for excess
nutrients and eutrophication biological indicators; Lake Cornelia (South Basin) is also included on the
City of Edina 2018 Comprehensive Water Resources Management Plan
2-10
MPCA’s Draft 2018 Impaired Waters list. The Lake Cornelia impairments are to be addressed as part of the
WRAPS process being led by the MPCA and NMCWD, with a targeted TMDL completion date of 2019. The
City of Edina will partner with the NMCWD in implementing potential remedial measures for the lake(s)
and its watershed recommended as part of the NMCWD UAA and MPCA WRAPS to improve the quality of
Lake Cornelia.
Lake Edina
Lake Edina is included on the MPCA’s Impaired Waters list for excess nutrients and eutrophication
biological indicators. The Lake Edina impairment is to be addressed as part of the WRAPS process being
led by the MPCA and NMCWD, with a targeted TMDL completion date of 2019. The City of Edina will
partner with the NMCWD in identifying and implementing potential remedial measures for the lake and
its watershed recommended following the MPCA WRAPS process to improve the quality of Lake Edina.
Other Downstream Waterbodies
There are also impaired lakes and streams outside the City that receive stormwater from Edina and will be
the subject of TMDL studies, including Lake Hiawatha, the Mississippi and Minnesota Rivers, and Lake
Pepin. The City has been assigned a wasteload allocation to address the Lake Hiawatha TMDL. The City
may need to amend the CWRMP to implement future requirements related to any downstream body.
2.2.7 Parks, Recreation, and Natural Resources Open Space
The City of Edina has numerous community parks, neighborhood parks, and other public open space
recreational areas. Figure 2.5 shows the numerous parks and recreational areas within the City of Edina.
Lakes, ponds, and creeks are often key attractions in public parks; examples within Edina include Arden
Park, Bredesen Park, Pamela Park, Rosland Park, Utley Park, Centennial Lakes Park, and Weber Woods
Park. The City of Edina currently owns and maintains approximately 350 acres of natural resource open
space areas, which includes 148 acres along the Nine Mile Creek right-of-way and 23 acres along the
Minnehaha Creek right-of-way. The city is basically fully developed, and is therefore no longer actively
acquiring additional property to develop as park land or open space. However, the City plans to retain all
of the current publicly owned park land and consider any additional property that may be offered in the
future as potential additional park property. The City will also seek to acquire additional park and open
space land as more private land becomes available for public acquisition.
2.2.8 Public Utilities
Edina is completely within the Metropolitan Council’s designated Metropolitan Urban Service Area
(MUSA). The MUSA is the area in the seven county metro area in which the Metropolitan Council ensures
that regional services and facilities are provided or planned. The City of Edina provides sanitary sewer and
water service throughout the City.
City of Edina 2018 Comprehensive Water Resources Management Plan
2-11
2.2.9 Fish and Wildlife Habitat
The water bodies and open spaces interspersed throughout the City provide habitat for numerous fish
and wildlife species, including birds, mammals, and reptiles. Ducks and geese are present in large
numbers at lakes, wetlands, and open water areas. Vegetative cover in the undeveloped open areas
support many mammalian species such as deer, raccoon, squirrels, fox, chipmunks, and rabbits. The
wetlands in Edina provide habitat for a variety of aquatic species including snakes, turtles, and frogs.
The Minnesota Department of Natural Resources (MnDNR) has completed fishery surveys of four lakes
within the City of Edina. The most recent surveys were of Lake Cornelia in 2010 and Centennial Lake in
2011. Both of these lakes are part of the MnDNR’s Fishing in the Neighborhood program. Lake Cornelia,
Centennial Lake, and Indianhead Lake have been stocked by the MnDNR in recent years. Arrowhead Lake
was observed to be infested with the invasive aquatic plant Eurasian Watermilfoil; Minnehaha Creek was
observed to be infested with invasive Eurasian Watermilfoil, Flowering Rush, and Zebra Mussels. Table 2.3
summarizes the available fishery survey, stocking, and aquatic invasive species information available for
the water bodies within the City of Edina.
City of Edina 2018 Comprehensive Water Resources Management Plan
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Table 2.3 Fishery and Aquatic Invasive Species Information
Water Resource
Survey
Year
Fishery 1
Stocking 2
Dominant Fish
Species
Invasive Species 3
and Year Species Was First
Confirmed
Lakes
Lake Cornelia
2005 Bluegill: 2001-2005 Bluegill, Black
Crappie, Carp
N/A
2010
Bluegill: 2007-2012, 2014-2016
Black Crappie: 2014
Hybrid Sunfish: 2014
Pumpkinseed Sunfish: 2014
Black Bullhead N/A
Arrowhead Lake 1995 Bluegill: 1994 Largemouth Bass: date unknown Black Bullhead, Green Sunfish Eurasian Watermilfoil (1995)
Centennial Lake
2006 Bluegill: 2001-2006, Largemouth Bass: 2002-2006 Black Bullhead, Green Sunfish
N/A
2011
Bluegill: 2007-2012, 2014-16
Black Crappie: 2017
Largemouth Bass: 2007-2009, 2014
Northern Pike: 2007-2010, 2013-2014
Pumpkinseed Sunfish: 2016
Black Bullhead,
Hybrid Sunfish
N/A
Indianhead Lake N/A
Bass: 2008
Black Crappie: 2008 Bluegill: 2008-2009 Walleye: 2008
N/A N/A
Streams
Minnehaha Creek N/A N/A N/A Eurasian Watermilfoil (1989),
Flowering Rush (2009), Zebra Mussels (2010)
Meadowbrook
(connected to Minnehaha Creek) N/A N/A N/A Zebra Mussels (2010)
Edina Mill Pond
(connected to Minnehaha Creek) N/A N/A N/A
Zebra Mussels (2010)
1 – Fisheries information from the MnDNR LakeFinder website (http://www.dnr.state.mn.us/lakefind/)
2 – Stocking reports available for 1998-2016 from the MnDNR LakeFinder website (http://www.dnr.state.mn.us/lakefind/)
3 – Invasive species information from MnDNR Infested Waters List website
(http://www.eddmaps.org/midwest/tools/infestedwaters/)
City of Edina 2018 Comprehensive Water Resources Management Plan
2-13
2.2.10 Unique Features and Scenic Areas
The MnDNR Natural Heritage Program and Nongame Wildlife Program maintain a database of rare plant
or animal species and significant natural features. This database includes only one record of a rare or
threatened species observance in Edina; a Blanding’s Turtle (Emydoidea Blandingii) was observed in 1989
in the southeast portion of the City (see Figure 2.6). The Blanding’s Turtle was classified as a threatened
species in Minnesota in 1984.
Other information was reviewed to determine whether other unique features area present in Edina. Based
on this review, no Outstanding Resource Value Waters (Minnesota Rules 7050.0180), Designated Scientific
and Natural Areas (Minn. Stat. 86A.05), State Wildlife Management Areas (Minn. Stat. 86A.05), or State
Aquatic Management Areas (Minn. Stat 86A.05) are located within the City of Edina.
2.2.11 Pollutant Sources
The MPCA’s “What’s in My Neighborhood” online application provides a variety of environmental
information for communities. The interactive web map provides information about environmental permits
issues by the MPCA, registrations and notifications required by the MPCA, and investigations of
potentially contaminated properties undertaken by the MPCA or its partners. The map shows the
approximate locations of registered storage tanks, leak sites, hazardous waste generators, dump sites,
Superfund sites, and Minnesota Pollution Control Agency (MPCA) Voluntary Investigation and Cleanup
(VIC) sites, as obtained from the Hennepin County Department of Environmental Services. The Hennepin
County Department of Environmental Services should be contacted for details about specific sites, since
many of the sites have been cleaned up or are in the clean-up process.
2.2.11.1 Investigation and Cleanup Sites
Dump sites include both unpermitted and permitted dump sites. Unpermitted dump sites are historic
landfills that never held a valid permit from the MPCA. Generally, these dump sites existed prior to the
MPCA’s permitting program, which was initiated in 1967. Unpermitted dump sites were often old farm or
municipal disposal sites that accepted household waste.
The MPCA VIC Program is a non-petroleum brownfield program that provides technical assistance and
administrative or legal assurances for individuals or businesses seeking to investigate or clean-up
contaminated property and to bring contaminated land back into productive use.
There is currently one MPCA Superfund Site within the City of Edina. This site is the Edina Well Field.
Additional information on this site can be obtained from the MPCA. In the early 2000s, the City of Edina
detected elevated levels of vinyl chloride in Municipal Well Number 7. Preliminary investigations found
several volatile organic compounds in nearby groundwater resulting in the City discontinuing use of Well
Number 7 in October 2003. Well Number 7 came online again after a high-capacity treatment plant
(Water Treatment Facility No. 6) was built at the Danen’s Building (5116 Brookside Avenue) in 2012. The
plant is equipped with an aeration system specially designed to filter out vinyl chloride. The City regularly
tests for vinyl chloride and Edina’s water meets the criteria set forth by the Environmental Protection
Agency.
City of Edina 2018 Comprehensive Water Resources Management Plan
2-14
2.2.11.2 Tank Sites and Leak Sites
Tank sites include registered petroleum tank facilities, both underground and above ground. Leak sites
are locations where a release of petroleum products has occurred from a tank system. Leak sites can occur
from aboveground or underground tank systems, or from spills at tank facilities. A leak can result from an
accident or from activities that occurred over a long period of time. Many of the known leak sites are
related to releases from underground fuel oil tanks.
2.2.11.3 Individual Sewage Treatment Systems
If properly functioning, individual sewage treatment systems (ISTS) typically do not impact the water
quality of surface or ground water resources. However, improperly functioning systems can negatively
impact water resources and are a source of ground and surface water contamination. City records indicate
that there are five known ISTS throughout the City.
2.2.12 Groundwater
The City of Edina operates two separate water systems: the Morningside water system and the Edina
water system. The Morningside system is supplied with treated surface water from the City of
Minneapolis; the City of Edina does not appropriate any surface water for its municipal water supply. The
water supply for the Edina system is groundwater, obtained from 18 groundwater wells, ranging in depth
from 450 to 1,100 feet. The City’s current groundwater appropriation permit limits the City’s groundwater
pumping to 17,500 gallons per minute or 3,000,000,000 gallons per year.
Wellhead protection programs are intended to help prevent contamination of public drinking water
supplies. The City’s Wellhead Protection Plan is available online. Part II of the Wellhead Protection plan
includes results of the City’s Potential Contaminant Source Inventory (PCSI). Wellhead Protection
information can also be found on the City’s Interactive Water Resources Map.
Mud Lake
Lake Cornelia
Lake Edina
Mirror Lake
Arrowhead Lake
Indianhead Lake
Highlands Lake
Melody Lake
Lake Pamela
Harvey Lake
Hawkes Lake
Centennial Lakes
Min
n
e
h
a
h
a
Cr
e
ek
Nine Mile Creek - North
Nine MileCreek - Central
Nine MileCreek - South
SoutheastMinnehaha Creek
SouthwestPonds
NorthwestMinnehaha Creek
Nine Mile -South Fork
Lake Cornelia/Lake Edina/Adam's Hill
NortheastMinnehaha Creek
TH 169North
£¤169
100
62
100
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4567158
456731NorthBranchN
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reek
SouthBranc h N ine Mile
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eekMinneapolisMinneapolis
HopkinsHopkins
Eden PrairieEden Prairie
RichfieldRichfield
BloomingtonBloomington
MinnetonkaMinnetonka
Saint Louis ParkSaint Louis Park
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FIGURE 2.1
0 3,000
Feet
!;N
Streets and Highways
Creek/Stream
Lake/Pond
City of Edina Boundary
Imagery Source: MnGeo 2016
Mud Lake
Lake Cornelia
Lake Edina
Mirror Lake
Arrowhead Lake
Indianhead Lake
Highlands Lake
Melody Lake
Lake Pamela
Harvey Lake
Hawkes Lake
Centennial Lakes
Min
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a
h
a
Cr
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4567158
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NorthBranchNineMileCreek
SouthBranc h N ine Mile
C
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eekMinneapolisMinneapolis
HopkinsHopkins
Eden PrairieEden Prairie
RichfieldRichfield
BloomingtonBloomington
MinnetonkaMinnetonka
Saint Louis ParkSaint Louis Park
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FIGURE 2.2
0 3,000
Feet
!;N
Land Use Classification
Agricultural
Natural/Park/Open
Developed Parkland
Golf Course
Very Low Density Residential
Low Density Residential
Medium Density Residential
High Density Residential
Institutional
Institutional - High Imperv.
Airport
Highway
Roads
Commercial
Industrial/Office
Other
Open Water
Wetland
Graded Pit
Streets and Highways
Creek/Stream
City of Edina Boundary
Imagery Source: MnGeo, 2016
1Data Source: City of Edina, 2000
1
Mud Lake
Lake Cornelia
Lake Edina
Mirror Lake
Arrowhead Lake
Indianhead Lake
Highlands Lake
Melody Lake
Lake Pamela
Harvey Lake
Hawkes Lake
Centennial Lakes
Min
n
e
h
a
h
a
Cr
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ek
£¤169
100
62
100
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4567158
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SouthBranc h N ine Mile
C
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HopkinsHopkins
Eden PrairieEden Prairie
RichfieldRichfield
BloomingtonBloomington
MinnetonkaMinnetonka
Saint Louis ParkSaint Louis Park
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FIGURE 2.3
0 3,000
Feet
!;N
Hydrologic Soil Groups
A - High infiltration rates.
Low runoff Potential.
B - Moderate infiltration rates.
Low to medium runoff potential.
C - Slow infiltration rates.Medium to high runoff potential.
D - Very slow infiltration rates.
High runoff potential.
Water
Streets and Highways
Creek/Stream
City of Edina Boundary
Imagery Source: MnGeo, 2016
^_
^_
^_
^_
^_
^_
^_
^_
¸#
¸#
¸#
Mud Lake
Lake Cornelia
Lake Edina
Mirror Lake
Arrowhead Lake
Indianhead Lake
Highlands Lake
Melody Lake
Lake Pamela
Harvey Lake
Hawkes Lake
Centennial Lakes
Min
n
e
h
a
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a
Cr
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£¤169
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Nine Mile CreekWatershed District
Minnehaha CreekWatershed District
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r
eekMinneapolisMinneapolis
HopkinsHopkins
Eden PrairieEden Prairie
RichfieldRichfield
BloomingtonBloomington
MinnetonkaMinnetonka
Saint Louis ParkSaint Louis Park
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FIGURE 2.4
0 3,000
Feet
!;N
¸#MCWD StreamMonitoring Station1
¸#NMCWD Stream
Monitoring Stations1
^_Lake Water Quality
Sampling Locations1
Watershed District Boundary
Streets and Highways
Creek/Stream
Lake/Pond
City of Edina Boundary
Imagery Source: MnGeo, 2016
1Monitoring is conducted periodicallyby NMCWD, MCWD, and CAMP
Volunteers. Watershed district monitoring is on a rotating basis
based on each district plan. Volunteer monitoring sites are
subject to change.
North
B
ranchNineMileCreek
SouthBranc h Nine Mile
C
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eekMud Lake
Lake Cornelia
Lake Edina
Mirror Lake
Arrowhead Lake
Indianhead Lake
Highlands Lake
Melody Lake
Lake Pamela
Harvey Lake
Hawkes Lake
Centennial Lakes
M
in
ne
h
a
h
a
C
r
ee
k£¤169
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62
100
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456731
Braemar Park (Courtney Fields)
Bredesen Park
Rosland Park
Pamela Park
Lewis Park
Highlands Park
Walnut Ridge Park
T. Lea Todd Park
Open Space 1
Heights Park
Garden Park
Heights Park
Lincoln Drive Floodplain
Van Valkenburg Park
Fred Richards Golf Course
Arden Park
Krahl Hill
Creek Valley School Park
Lake Edina Park
Normandale Park
Weber Field Park
Arneson Acres Park
Countryside Park
Weber Woods
Centennial Lakes Park
Open Space 2
Open Space 3
Centennial Lakes Park
Alden Park
Utley Park
Open Space 2
Moore Property
Pamela Park
York Park
Yorktown Park
Centennial Lakes Park
Cornelia School Park
Wooddale Park
Strachauer Park
Garden Park
Open Space 5
Fox Meadow Park
Kojetin Park
Edinborough Park
Arden Park
Garden Park
McGuire Park
Fox Meadow Park
Birchcrest Park
Sherwood Park
Garden Park Addition
Melody Lake Park
Chowen Park
Open Space 2
Centennial Lakes Park
St. John's Park
Tingdale Park
York Park
Browndale Park
York Park
Frank Tupa Park
Grandview Square
Open Space 6
MinneapolisMinneapolis
HopkinsHopkins
Eden PrairieEden Prairie
RichfieldRichfield
BloomingtonBloomington
MinnetonkaMinnetonka
Saint Louis ParkSaint Louis Park
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FIGURE 2.5
0 3,000
Feet
!;N
Park/Recreational Area
Streets and Highways
Creek/Stream
Lake/Pond
City of Edina Boundary
Imagery Source: MnGeo, 2016
Mud Lake
Lake Cornelia
Lake Edina
Mirror Lake
Arrowhead Lake
Indianhead Lake
Highlands Lake
Melody Lake
Lake Pamela
Harvey Lake
Hawkes Lake
Centennial Lakes
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HopkinsHopkins
Eden PrairieEden Prairie
RichfieldRichfield
BloomingtonBloomington
MinnetonkaMinnetonka
Saint Louis ParkSaint Louis Park
Barr Footer: ArcGIS 10.4.1, 2017-10-03 09:45 File: I:\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_2_6_Threatened_and_Endangered_Species.mxd User: EMATHREATENED ANDENDANGERED SPECIESComprehensiveWater ResourcesManagement PlanCity of Edina, Minnesota
FIGURE 2.6
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NHIS Rare Natural Features
Vertebrate Animal
Community
Vascular Plant
Animal Assemblage
Streets and Highways
Creek/Stream
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City of Edina Boundary
Imagery Source: MnGeo, 2016
Data Source:Natural Heritage Information
System Rare Features DataCopyright 2017 State of Minnesota,Department of Natural Resources
City of Edina 2018 Comprehensive Water Resources Management Plan 3-1
3.0 Policies for Water Resources Management
3.1 Runoff Management and Flood Protection
3.1.1 Runoff Management and Flood Protection Background
Just as watershed models are used to define problem areas within the drainage system, design criteria
(standards for design) are used to define solutions to the problems. Municipal drainage systems provide
service (removal of runoff water) and protection (control of flood levels). It is useful to have criteria for
both the level of service and the level of protection to be provided by the drainage system. In addition,
at ponds and low-lying areas it is common to add a factor of
safety in the form of added elevation above the projected flood
level (freeboard) or extra volume.
It is important to understand the difference between flood control
level of service and level of protection when designing and
analyzing stormwater systems.
Level of service is defined as the capacity provided by a municipal drainage system to remove runoff and
prevent significant interference with normal daily transportation, commerce, or access that might result
from a rainstorm. For example, gutters might run full, but when the runoff arrives at a catch basin it would
enter the catch basin and be carried away by the storm sewer. Intersections would not be inundated to an
extent that adversely impacts driving conditions, right-of-way would be undamaged, and public
infrastructure would operate normally. The modern standard of practice is usually that systems be
designed for the “10-year” (10-percent-annual chance) storm event, which means that there is roughly a
10 percent probability in any year that the system will be overtaxed and unable to meet these criteria. In
many communities, older systems were designed for smaller storm events such as a “2-year” event or a
“5-year” event. Intersection flooding is common in these areas.
Level of protection is defined as the capacity provided by a municipal drainage system to prevent
property damage and assure a reasonable degree of public safety following a rainstorm. For example,
runoff might bypass a catch basin and collect in low-lying areas such as intersections, but would not cause
flood damage to structures. Accumulated water might temporarily interfere with traffic or access, but
right-of-way should be undamaged and public infrastructure should operate normally. Safety should not
be significantly threatened, assuming persons use common sense and don’t drive into the standing water
or try to walk or swim in fast-flowing water. The stormwater system must have the capacity (in terms of
pipe capacity, overland overflow capacity, or detention volume) to limit the flood elevation to acceptable
levels for an event representing the protection criteria.
Flood frequency data is often also described in terms of a percentage of risk, or annual exceedance
probability. For example, the 100-year frequency flood inundation area represents an area that has a 1-
percent chance of flooding for any given year (1-percent-annual-chance flood). Structures located within
the 1-percent-annual-chance flood inundation area have a 26 percent chance of flooding during the life
Plan and policy supporting
documentation can be found
online through the “Edina Docs”
Water Resources Library:
http://edinadocs.edinamn.gov/
City of Edina 2018 Comprehensive Water Resources Management Plan
3-2
of a standard 30-year mortgage. Federal and state programs use criteria based on the 1-percent-annual-
chance flood event to define the floodplain along rivers and streams, and cities and other drainage
authorities commonly extend this standard to other areas. A 1-percent-annual-chance event is also a
common standard for design of detention basins. A 1-percent-annual-chance design for a ponding area
means the pond has adequate volume to hold the 1-percent probable runoff and infers that adjacent
structures will be above the level of the ponded water.
However, the criterion for level of protection has broader application. In addition to ponding areas, lakes,
and streams, this criterion should be applied to all locations served by the drainage system where there
are depressed intersections or other areas subject to temporary, unplanned flooding.
In 2013, the National Oceanic and Atmospheric Administration’s (NOAA’s) National Weather Service
(NWS) published new precipitation frequency estimates (“Atlas 14”) for the state of Minnesota and other
Midwestern states (NOAA, 2013). The Atlas 14 precipitation frequency estimates, which are the estimated
rainfall depths for various rainfall durations and exceedance probabilities, replace the precipitation
estimates published in Technical Paper No. 40 Rainfall Frequency Atlas of the United States (“TP 40”) (U.S.
Department of Commerce, 1961). The Atlas 14 rainfall frequency estimates indicate a significant increase
in the depth of the 50-year and 100-year frequency rainfall events (i.e., rainfall events with exceedance
probabilities of 2% and 1%, respectively) across Minnesota and neighboring states, as compared with
TP 40 estimates. For the Minneapolis/St. Paul area, the increases in 24-hour duration precipitation depths
over TP 40 are as high 25%. These precipitation depth increases are of concern, as they can have serious
implications for how stormwater systems are designed and managed.
Since the 2013 release of Atlas 14, the Nine Mile Creek Watershed District has updated their hydrologic
and hydraulic models to reflect the updated precipitation frequency estimates and has adopted revised
flood management elevations. The City of Edina has also updated their hydrologic and hydraulic models
to reflect Atlas 14 precipitation. However, FEMA’s effective Flood Insurance Rate Map (FIRM) and Flood
Insurance Study (FIS) within the city of Edina are still based on TP-40 rainfall depths. Table 3.1 identifies
the source of the best available 1-percent-annual-chance flood elevations for various portions of the City
at the time of this plan development.
City of Edina 2018 Comprehensive Water Resources Management Plan
3-3
Table 3.1 Source of the Best Available 1-Percent-Annual Chance Flood Elevations throughout the City of Edina
Area Best Available Flood Elevation Information/Modeling Source of Precipitation Frequency Estimates Owner
Nine Mile Creek corridor NMCWD Atlas 14 Flood Management
Elevations and associated XP-SWMM Model(s) Atlas 14 NMCWD
Minnehaha Creek corridor FEMA Effective Flood Insurance Rate Map
(FIRM) and Flood Insurance Study (FIS) TP-40 MCWD
City of Edina, with
exception of Nine Mile
Creek and Minnehaha
Creek corridor areas
City of Edina 2017 CWRMP or subsequent XP-
SWMM model updates Atlas 14 City of Edina
3.1.2 Runoff Management and Flood Protection Policies
The following sections present the City of Edina’s policies and design standards that address runoff
management and flood control. In addition to the policies discussed below, the City has entered into
water resource management related agreements with watershed
districts and adjacent cities.
• City of Bloomington: for the area of the Border Basin
• City of Eden Prairie: for the area along Washington Avenue
• City of Richfield: for the outlet from Adam’s Hill Pond
• City of Hopkins: for the area east of Blake Road and along TH
169
• City of St Louis Park: for Meadowbrook Golf Course and
Morningside area
• Minnehaha Creek Watershed District: for Arden Park, Pamela Park Water Quality Improvements,
and the 2014 Memorandum of Understanding outlining spheres of collaboration
• Nine Mile Creek Watershed District: for the Edina Streambank Stabilization project and Pentagon
Park assessment and planning (in cooperation with the City of Bloomington).
The City adopts the following general runoff management and flood protection policies (Sections 3.1.2.1
through 3.1.2.3 provide specific policies and standards):
1. No flow rate increases in already overtaxed stormwater systems.
2. The City will place a high priority on providing 1-percent-annual-chance level of protection for
the City’s stormwater detention and conveyance systems, where detention is provided (e.g., low
point intersections, ponds, planned flood area, etc.). The City will require new stormwater systems
Water resource management-
related agreements that the City
has entered with other public
and private organizations can be
found online through the “Edina
Docs” Water Resources Library:
http://edinadocs.edinamn.gov/
City of Edina 2018 Comprehensive Water Resources Management Plan
3-4
to provide 1-percent-annual-chance level of protection. Existing systems (conveyance and
detention) that currently do not provide 1-percent-annual-chance level of protection will be
modified to provide 1-percent-annual-chance level of protection when feasible. Potential
additions and modifications to the stormwater system are discussed in Section 5.0 through
Section 14.0 and summarized in Table 15.2.
3. The City will require new stormwater conveyance systems to provide a 10-percent-annual-chance
(10-year) level of service. Existing stormwater conveyance systems that currently do not provide a
10-percent-annual-chance level of service will be modified, as opportunities arise and as feasible.
4. For new development and redevelopment, peak flow rates will be limited in accordance with the
applicable rules of the Nine Mile Creek Watershed District and Minnehaha Creek Watershed
District.
5. It is the City’s standard practice to provide a 10-percent-annual-chance level of service and 1-
percent-annual-chance level of protection for the City’s stormwater conveyance systems, where
feasible. However, some existing stormwater
conveyance systems have capacity limitations and
cannot be guaranteed to provide the discharge
capacity where private storm sewer systems tie into
the trunk system.
6. The City will determine the applicable 1-percent-
annual-chance flood elevation(s) by using the best
information available at the time. For regional flood
areas, the applicable 1-percent-annual-chance flood
elevation will be based on FEMA’s effective Flood
Insurance Rate Map (FIRM) and Flood Insurance
Study (FIS), flood management elevations adopted
by the respective watershed district, or hydrologic
and hydraulic model(s) developed by the respective
watershed district, whichever is higher. For local
flood areas, the applicable 1-percent-annual-chance
flood elevation will be based on the City’s 2018
CWRMP or subsequent XP-SWMM model updates.
The applicable 1-percent-annual-chance flood
elevations are subject to change due to periodic
model updates that incorporate additional or more
accurate information and may differ from the flood
elevations identified in this plan.
For a regional flood area, the
applicable 1-percent-annual chance
flood elevation (also called the
Special Flood Hazard Area) is based
on the higher of FEMA’s effective
Flood Insurance Rate Map (FIRM)
and Flood Insurance Study (FIS),
flood management elevations
adopted by the respective watershed
district, or hydrologic and hydraulic
model(s) developed by the
respective watershed district.
A local flood area is the area below
the modeled 1-percent-annual
chance flood elevation for areas
outside of the regional flood area.
These areas are described in detail in
Sections 5-14 of this plan.
Generally, regional flood conditions
tend to persist longer than local
flood conditions.
City of Edina 2018 Comprehensive Water Resources Management Plan
3-5
7. The applicable 1-percent-annual-chance flood elevation will be based on a 24-hour duration
precipitation event, unless an event of another duration is determined to result in a higher flood
elevation.
8. The City will allow outlets from landlocked basins only when such outlets are at or above the 1-
percent-annual-chance floodplain, are consistent with state and federal regulations, and the
downstream, riparian, and habitat impacts of such outlets have been analyzed and no detrimental
impacts result. An exception to this policy is the City will allow an outlet below the 1-percent-
annual-chance floodplain elevation in situations where public safety is threatened and/or
inundation of principle structures would be likely if the outlet is at a higher elevation.
3.1.2.1 Minimum Principle Structure Elevations
To prevent flooding of principle (non-detached) structures, the City will implement the following
standards in addition to the Floodplain Overlay Districts ordinance (City Code Chapter 36, Article 10).
1. New principle structures, additions, and other
permanent fixtures including heating and air
conditioning ventilation systems must have a lowest
floor elevation at least two feet above the
applicable 1-percent-annual-chance flood elevation
if one or more of the following conditions exist:
a. The structure is within or adjacent to a
regional flood area;
b. The structure is within a local flood area
subject to regional tailwater effects;
c. The structure is within a local flood area that
is land-locked;
d. The City Engineer determines the structure
to be at significant risk due to seepage.
2. New principle structures that are not subject to
3.1.2.1 (1) and are adjacent to a ponding basin must
have a lowest floor elevation at least two feet
above the ponding basin outlet elevation. New
principle structures that require a watershed district
permit must conform to their minimum elevation
standards.
Ponding basin describes an area
used for long term or extended flood
storage, for example detention
basins/ponds, retention
basins/ponds, infiltration basins,
natural waterbodies, or other areas
that provide flood storage either by
design or naturally.
Temporary storage area describes
an area used for short term,
temporary flood storage, for
example backyard depression areas,
streets, parking lots, or other areas
that provide temporary short term
flood storage either by design or
naturally.
Lowest floor elevation is the floor
elevation of the lowest enclosed area
(including basement).
Lowest entry elevation is the lowest
opening of a structure, for example
windows, window well sill elevations,
or walkout elevations.
City of Edina 2018 Comprehensive Water Resources Management Plan 3-6
3.New principle structures, additions, and other permanent fixtures including heating and air
conditioning ventilation systems must have a lowest entry elevation at least two feet above the
applicable 1 percent-annual-chance flood elevation if one or more of the following conditions
exist:
a.The structure is within or adjacent to a local flood area;
b.The structure is within or adjacent to a temporary storage area, emergency overflow, or
stormwater conveyance; the 1-percent-annual-chance flood elevation of the temporary
storage area, emergency overflow, or stormwater conveyance at the point where the
temporary storage area, emergency overflow, or stormwater conveyance is closest to the
structure applies.
4.New principle structures, additions, and other permanent fixtures including heating and air
conditioning ventilation systems that are within or adjacent to a surface conveyance must have a
lowest entry elevation at least two feet above the modeled 1 percent-annual-chance flood
elevation at the point where the surface conveyance is closest to the structure applies.
5.New principle structures, additions, and other permanent fixtures including heating and air
conditioning that are within or adjacent to a landlocked basin must have a lowest floor elevation
that is at least two feet above the water level resulting from two concurrent 1-percent-annual
chance, 24-hour rainfall events or two feet above the 1-percent-annual chance 10-day snowmelt,
whichever is higher. In either case, the starting elevation of the basin/waterbody prior to the
runoff event should be established by one of the following:
i.Existing Ordinary High Water level established by the MnDNR;
ii.Annual water balance calculation approved by the City;
iii.Local observation well records, as approved by the City; or
iv.Mottled soil.
Note: The landlocked basin 1-percent-annual-chance flood elevation may be lowered by creating
new storage, excavating an overflow swale or installing an outlet pipe at an overflow point.
3.1.2.2 Below-Grade Garages and Parking Adjacent to Flood-Prone Areas
To prevent flooding of below-grade garages and parking facilities, the City will implement the following
design standards:
1.Construction of below-grade parking garages in residential structures in local flood and regional
flood areas is prohibited.
City of Edina 2018 Comprehensive Water Resources Management Plan 3-7
For further guidance including
requirements and certification of
below-grade parking garages, review
the following;
•FEMA’s Technical Bulletin 6-
93, “Below-Grade Parking
Requirements for Buildings
Located in Special Flood
Hazard Areas”
•FEMA’s Technical Bulletin 3-
93, “Non-Residential
Floodproofing – Requirements
and Certification”.
2.Construction of below-grade parking garages in mixed-use and non-residential structures in local
flood and regional flood areas is permitted, provided the structure (including the parking garage)
is flood proofed to two feet above the applicable 1-percent-annual-chance flood elevation in
accordance with the following design standards:
a.Together with associated utility and
sanitary facilities, the structure must be
designed so that below two feet above
the 1-percent-annual-chance flood
elevation the structure is watertight
with walls substantially impermeable to
the passage of water and with structural
components having the capability of
resisting hydrostatic and hydrodynamic
loads and effects of buoyancy.
b.A Floodproofing Certificate and
Inspection and Maintenance Plan must
be provided by a registered
professional engineer or architect.
c.A floodproofing design that entails
human intervention, such as the
installation of flood gates or flood
shields, will require a Flood Emergency
Operation Plan.
3.1.2.3 Stormwater Management Design Standards
The City adopts the following design standards for all new stormwater management systems (i.e., basins,
storm sewers, etc.):
1.All ponding basins, temporary storage areas, and basin outlet pipes should be designed to
collectively detain and convey the flows from the critical 1-percent-annual-chance storm (1-
percent-annual-chance level of protection). The critical storm represents a storm of a given runoff
duration that produces the greatest discharge or detention storage volume, as appropriate.
Ponding basins should be designed to contain the flows from
the 1-percent-annual-chance storm without overtopping.
2.All lateral storm sewer systems, including catch basin grates,
should be designed to convey flows from the 10-percent-
annual-chance storm (10-year level of service).
3.Where practical and physically possible, regional ponding
basins and temporary storage areas, as opposed to individual
onsite ponding basins and temporary storage areas, are
preferred to reduce flooding, to control discharge rates, and
to provide necessary storage volumes.
The City has begun
development of an inventory of
public and private stormwater
management facilities which can
be found online via the City’s
interactive water resources map:
https://www.barr.com/maps/edi
na/index.html#/
City of Edina 2018 Comprehensive Water Resources Management Plan
3-8
4. Stormwater retention (volume control) is required by both the Nine Mile Creek Watershed District
and Minnehaha Creek Watershed District. Applicable design criteria are available from each
respective watershed district.
5. All new constructed slopes within the 1-percent-annual-chance storage volume of a stormwater
management system should be designed in accordance with current design standards.
6. All ponding basins and temporary storage areas should have a protected and stable emergency
overflow conveyance or structure to prevent undesired flooding resulting from extreme storms or
plugged outlet conditions. The emergency overflow conveyance should be protected with
permanent, non-degrading erosion control materials (i.e., riprap or geosynthetics), where feasible.
7. Each ponding basin and temporary storage area should have an access for maintenance
purposes.
3.2 Floodplain Management
The floodplain of a stream can be defined as that area adjacent to a stream which is inundated during
times of flood. More specifically, the Minnesota Floodplain Management Act of 1969 defines the
floodplain as that area adjoining a watercourse which is subject to inundation by a flood of 1-percent-
annual chance. Under the provisions of this act, local governmental units are required to adopt floodplain
management ordinances which will include “the delineation of floodplains and floodways, the
preservation of the capacity of the floodplain to carry and discharge regional floods, minimization of flood
hazards, and the regulation of the use of land in the floodplain.” Under the provisions of the required
ordinances, no major alteration to existing structures, no new fill and no floodplain use which would
unreasonably constrict flood flows will be allowed in the floodplain unless further provisions are made to
fully compensate any detrimental effects.
The following policies regarding floodplain regulation with the City of Edina have been adopted:
1. The City will work to maintain no net loss of floodplain storage and will manage local and
regional floodplains to maintain critical 100-year flood storage volumes.
2. The City will reduce the risk and consequence of flooding through the enforcement of
engineering standards and the Floodplain Districts Overlay ordinance.
a. The City defines the regional flood as the 1-percent-annual-chance floodplain as shown in
FEMA’s Flood Insurance Rate Maps and Flood Insurance Study, consistent with Edina City
Code floodplain districts overlay ordinance Chapter 36, Article X.
b. The City defines local flooding as flood-prone areas that are outside of the regional flood
area, and applies to all land within the City of Edina.
Note: A description of the model inputs for regional and local flood elevations is provided in
Section 4.0.
City of Edina 2018 Comprehensive Water Resources Management Plan
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3. The floodplain of Nine Mile Creek is defined as that area lying below the 100-year NMCWD
Management Elevations as identified in the Nine Mile Creek Water Management Plan, October
2017, available on their website at www.ninemilecreek.org. The floodplain of Minnehaha Creek is
defined as that area lying below the 1-percent-annual-chance flood elevations as shown in the
Federal Emergency Management Agency (FEMA) Flood Insurance Study for Hennepin County,
Minnesota All Jurisdictions, November 2016.
4. The floodplain requirements of the Nine Mile Creek Watershed District and the Minnehaha Creek
Watershed District are applicable.
5. The City will communicate local and regional flood risk to stakeholders.
6. The City recognizes that addressing regional and local flood issues throughout the community
will require multiple strategies and many actions implemented over a generational time frame.
The City will employ the strategies and associated actions summarized in Table 3.2 for addressing
flood issues.
City of Edina 2018 Comprehensive Water Resources Management Plan
3-10
Table 3.2 Strategies and Potential Actions for Addressing Local and Regional Flood Issues
Strategies Potential Actions
Modify the flood
Plan, preserve and reclaim flood storage (new public and private stormwater
plans, deeds, easements, open space)
Maintain and increase green space
Maintain and increase storage (ponds, underground chambers, streets,
depressions)
Protect flow paths and emergency overflows
Manipulate timing of peak flow
Divert water
Control rate of peak flow
Detain and slowly release flow
Reuse water for beneficial purposes
Employ Green Infrastructure (GI) and Low Impact Development (LID) standards
Modify susceptibility Elevate structures
Reduce impacts
Floodproof structures
Enforce substantial improvement limits
Elevate utilities
Encourage flood insurance
Encourage preparedness planning
Encourage resilient landscaping
Provide risk audits
Limit infiltration and inflow to the sanitary system
Maintaining existing floodplain infrastructure
3.3 Water Quality
The streams, ponds, lakes, and wetlands in the City of Edina are an important community asset. These
resources supply aesthetic and recreational benefits, in addition to providing wildlife habitat and refuge.
The City recognizes the need to assure adequate water quality in the water bodies within the city and will
take steps to protect and improve these resources. The City of Edina will manage the City’s water
resources so that the beneficial uses of lakes, streams, ponds, and wetlands remain available to the
community. Such beneficial uses may include aesthetic appreciation, wildlife habitat protection, nature
observation, and recreational activities.
3.3.1 Water Quality Background
Within the City of Edina, there are over two hundred water bodies, ranging in size from lakes to small
stormwater detention basins. Historically, as the city developed, these lakes and ponds have been used for
stormwater runoff detention in association with flood protection efforts. Unfortunately, the urbanization
City of Edina 2018 Comprehensive Water Resources Management Plan
3-11
of a watershed often accelerates the degradation of water bodies through a natural process known as
eutrophication. Nonpoint pollution associated with stormwater runoff creates adverse impacts; the degree
of impact dependent upon the water body’s natural ability to remove, absorb, or process the pollutants
through chemical, physical, or biological processes. Poor water quality usually indicates a situation where
the resource receives more nutrients, or other pollutants, than can be processed naturally.
Urban stormwater runoff carries a variety of pollutants that affect water quality. These contaminants are
generated through the activities in different residential, commercial, and industrial land developments
within a watershed. During storm or snowmelt events, these pollutants quickly wash off and are carried to
downstream waters. As development increases and activities change and intensify, the concentrations and
types of contaminants increase accordingly.
Phosphorus and suspended sediments are recognized as being particularly detrimental to the health of
lakes and streams in Minnesota. As a result, the City’s watershed management and land development
policies are directed mainly at controlling the amount of phosphorus and sediment that reaches the water
bodies within the city. Many other pollutants are transported by the same processes that convey
phosphorus. Therefore, phosphorus reduction measures for stormwater runoff may also reduce the flow
of other pollutants to water resources within the city.
Suspended sediment in runoff is a major source of phosphorus because dissolved phosphorus frequently
adsorbs to small particles in the suspended sediment. Because much of the phosphorus reaching water
bodies from runoff is transported with the suspended sediment load, efforts to control sediment also help
to reduce phosphorus loading. Suspended sediment carried by stormwater runoff typically consists of fine
particles of soil, dust, dirt, organic material, and undissolved fertilizer. Suspended sediment loads can also
carry heavy metals, oils, and other pollutants. High volumes of suspended sediment reaching water bodies
can be the result of:
• Runoff from city streets, buildings, parking lots, and other impervious areas, which washes
accumulated sediment from those areas.
• Runoff from urban areas with higher flows and higher velocities, which in turn causes channel and
swale erosion.
• Runoff from construction sites with poor erosion and sediment control or with poorly maintained
sediment control facilities.
Chloride is another pollutant in stormwater runoff that can be detrimental to the health of lakes and
streams in Minnesota. Chloride is a salt found in most waters; however, elevated levels of chloride in
surface water can harm aquatic organisms. High chloride levels in lakes and streams usually occur in
relation to winter snowmelt due to the wide-spread application of road salt during winter-weather
conditions. Nine Mile Creek and Minnehaha Creek have both been identified by the Minnesota Pollution
Control Agency (MPCA) as impaired due to excessive chloride levels (see Section 2.2.6 for more details).
City of Edina 2018 Comprehensive Water Resources Management Plan
3-12
Stormwater can also convey harmful bacteria, often called pathogens, into local lakes and streams.
Ingestion of pathogens by humans can lead to gastrointestinal illnesses such as severe diarrhea or nausea,
as well as headaches and fatigue. Two bacterial groups often used as “indicator organisms” for detection
of pathogenic organisms are fecal coliform and E. coli bacteria. Fecal coliform and E. coli bacteria found in
lakes and streams can originate from human, pet, livestock, or wildlife waste. Minnehaha Creek has been
identified by the MPCA as impaired due to excess levels of bacteria (see Section 2.2.6 for more details).
Lakes and streams are often monitored for the presence of specific pollutants, such as phosphorus,
suspended sediment, or dissolved oxygen, to assess the quality of the waterbody. Another means to
assess the health of a waterbody is through biological monitoring, which tracks the health of plant, insect,
small organism, and fish communities. Several measures of a biological community related to the diversity
and types of species present are assessed to develop an Index of Biological Integrity (IBI). For fish, for
example, these measures may include feeding, reproduction, tolerance to human disturbance, abundance,
and condition. An IBI score can then be used to assess the health and integrity of the waterbody. Nine
Mile Creek and Minnehaha Creek have both been identified by the Minnesota Pollution Control Agency
(MPCA) as biologically impaired (see Section 2.2.6 for more details).
Algae (phytoplankton) are small aquatic plants that derive energy from sunlight and dissolved nutrients
found in lake water. While algae are generally considered beneficial for lakes in that they form the base of
a lake’s food web, over-abundance of algae can hinder lake health and cause poor water clarity. Typical
algal blooms are comprised of green algae, which although can be a nuisance, are generally not harmful.
Blue-green algal blooms, on the other hand, can be harmful. Blue-green algae, often described as looking
like pea soup or spilled green paint, are not actually algae but types of bacteria called cyanobacteria.
These bacteria can produce algal toxins that can pose a health threat for pets and people when
concentrations become high enough. Blue green algae thrive in warm, shallow, nutrient-rich lakes.
3.3.2 Water Quality Management Policies
The City adopts the following general water quality management policies:
1. The City will review, permit, and enforce standards for construction activities to prevent
pollution and make progress toward water quality goals.
2. The City will work to heighten community awareness of water quality management through
education and training to reduce pollution sources including, but not limited to, chloride.
3. The City will engage the community in decision-making and encourage active participation in
solving water resources problems.
4. The City will manage its water resources so that the beneficial uses of streams, wetlands,
ponds, and lakes remain available to the community.
City of Edina 2018 Comprehensive Water Resources Management Plan
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5. The City will conduct targeted street sweeping and encourage other forms of upstream
pollutant reduction in areas closer to the source of such pollutants.
6. The City will encourage use of regional detention areas as opposed to individual on-site
detention to reduce flooding, control discharge rates, and provide for water quality
management.
7. As required by the Nine Mile Creek Watershed District and Minnehaha Creek Watershed
Districts, stormwater retention is required. The rules of the Nine Mile Creek Watershed District
and Minnehaha Creek Watershed District are adopted by reference and can be found on the
appropriate watershed district website.
8. As required by the Nine Mile Creek Watershed District, stormwater runoff must be treated to
achieve at least 60 percent annual removal efficiency for phosphorus and at least 90 percent
annual removal efficiency for total suspended solids.
9. The City will implement stormwater management requirements for single and double
dwelling units as described in City Code, chapter 10 and for site plans associated with
commercial, multifamily, and multiuse as described in City Code, chapter 36.
10. The City will work with the MPCA, Nine Mile Creek Watershed District, and Minnehaha Creek
Watershed District to implement the recommendations and/or requirements of existing or
future WRAPS and TMDL(s) throughout the city.
11. The City will work with Nine Mile Creek Watershed District, Minnehaha Creek Watershed
District, and lake associations to study the health of waterbodies and plan activities for
protecting and improving waterbodies.
12. The City will target improvements to address pollutant loading from watershed sources, and
partner with watershed districts and lake associations to address internal phosphorus loads.
13. The City will promote and protect a diverse, native population of aquatic vegetation that
contributes to a balanced ecosystem through partnerships with watershed districts and lake
associations.
14. The City will conduct management of invasive aquatic species where the management
strategy has a measurable clean water benefit.
15. The City will encourage the use of low-impact site design for development and
redevelopment within the city.
16. The City will, where feasible, apply low-impact site design principles for City-sponsored
improvement projects.
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3.3.2.1 Water Quality Management Standards
Stormwater Retention/Detention System Standards
Stormwater retention/detention facilities must be designed according to the most current technology as
reflected in the Minnesota Stormwater Manual (MPCA, 2005) or the applicable Nine Mile Creek Watershed
District or Minnehaha Creek Watershed District rules, whichever applies to the site.
Construction Site Standards
The requirements of the National Pollutant Discharge Elimination System (NPDES) Municipal Separate
Storm Sewer Systems (MS4) General Permit and the City’s Stormwater Pollution Prevention Program
(SWPPP) are applicable (see Section 15.2.2 for more details).
3.4 Erosion and Sediment Control
The City’s goals regarding erosion and sediment control are to protect the capacity of the City’s
stormwater management system, prevent flooding, maintain water quality by preventing erosion and
sedimentation from occurring, and correct existing erosion and sedimentation problems.
3.4.1 Erosion and Sediment Control Policies
The following policies are adopted by the City of Edina:
1. The City requires erosion and sediment controls and submittal of erosion and sediment control
plans for proposed construction activities.
2. Erosion and sediment controls shall conform to the requirements of the Nine Mile Creek
Watershed District or Minnehaha Creek Watershed District, depending on project location.
3. The City will direct that entities proposing construction projects that disturb more than 1 acre of
land will need to apply for coverage under the MPCA’s General NPDES Construction Stormwater
Permit.
3.5 Wetlands
The City of Edina’s goal is to achieve no net loss of wetlands, including acreage, functions, and values. Due
to the developed nature of the city, all of the wetlands within the city are used for clean water and flood
protection purposes. Where practical, opportunities to improve the functions, values, biological diversity,
and acreage of existing wetlands should be sought.
3.5.1 Wetlands Policies
The City adopts the following policies relating to wetlands within the city:
1. The City discourages wetland alteration. Unavoidable wetland alterations must be mitigated in
conformance with the Wetland Conservation Act (WCA) requirements and the requirements of
the Nine Mile Creek Watershed District or Minnehaha Creek Watershed District, and must be
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guided by the following principles, in descending order: avoid the impact, minimize the impact,
rectify the impact, reduce or eliminate the impact over time, and compensate for the impact.
2. The Nine Mile Creek Watershed District and the Minnehaha Creek Watershed District are the local
government units (LGU) responsible for administering the Wetland Conservation Act in the City of
Edina. The City will work in conjunction with the Nine Mile Creek Watershed District and the
Minnehaha Creek Watershed District on issues pertaining to wetland alterations within the city
boundary.
3. The City will support watershed districts and other agencies in their efforts to maintain and
periodically update the wetland inventory data and the wetland management classifications
provided in this plan.
4. The City will partner with watershed districts to restore previously existing wetlands and enhance
existing wetlands.
5. The City will involve the appropriate regulatory agencies (MPCA, U.S. Army Corps of Engineers,
and the MnDNR) in the planning of any proposed water quality or flood control facilities
identified in this plan that may be located within a wetland.
6. The City will provide buffer zones of native vegetation, where feasible, around ponds and
wetlands to provide habitat. The City will work with the Nine Mile Creek Watershed District and
Minnehaha Creek Watershed District to educate the public regarding wetland protection and the
importance of creating and maintaining vegetative buffers. Land use and property ownership may
limit the ability to provide buffer zones.
7. The City encourages the minimization of water level fluctuations (bounce), where feasible, in
wetlands or detention basins to prevent adverse habitat changes.
3.6 Natural Resources
The City’s goals are to protect and enhance fish and wildlife habitat, soils and native landscapes. To
accomplish this objective, the City adopts the following policies:
1. Cooperate with other units of government to complete habitat and recreation corridor
connections (trails and greenways).
2. Maintain, enhance, or provide new habitat as part of wetland modification, stormwater facility
construction, Parks redevelopment, or other appropriate projects.
3. Encourage alternative landscape designs that increase beneficial habitat, wildlife and clean water ;
promote infiltration and vegetative water use, decrease detrimental wildlife uses (such as beaver
dams, goose overabundance), protect water control facilities, stabilize soils with deep roots near
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the shoreline, stabilize soils for water quality or recreational opportunity ,and minimize irrigation
demand and chemical control.
3.7 Groundwater
The City’s goal is to protect the quality and quantity of groundwater resources. The City adopts the
following groundwater policies:
1. The City will encourage groundwater recharge and protect recharge areas from potential sources
of contamination. The City will provide increased greenspace, native vegetation, and pond “dead”
storage wherever possible and appropriate to allow for the infiltration of stormwater runoff and
promote groundwater recharge.
2. The City will encourage use of grassed waterways to maximize infiltration where not detrimental
to groundwater supplies.
3. The City will implement groundwater quality and quantity protection measures outlined in the
City’s Wellhead Protection Plan, Part II (2013).
4. The City will address unused unsealed private wells through the permitting process.
5. The City will review and adopt as necessary a water sustainability ordinance that is protective of
groundwater quality and quantity.
6. The City will investigate, and implement where feasible, water reuse projects.
7. The City will promote awareness of groundwater resource issues through public education and
information programs.
3.8 Education Program
The City of Edina believes public education is an important and effective method to control non-point
source pollution since it emanates from broad reaches of the landscape. A public education program
raises citizen awareness regarding pollutant sources in everyday life from all types of property. The City
will educate its residents, businesses, industries and staff concerning pollutant reduction, best
management practices, the link between daily housekeeping activities and the condition of the City of
Edina’s water resources, and awareness of natural resources in general. The City will also seek to inform its
residents, businesses, industries and staff of initiatives, projects, etc. completed by the community that
address the City’s education goals.
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Education and housekeeping practices are especially important in urban settings since there is limited
land available to provide water quality treatment facilities. The City of Edina will develop and distribute
educational materials to the general public and targeted groups regarding:
• Natural resources within and adjacent to the city
• Importance of pollutant reduction in stormwater runoff
• City ordinances, policies and programs pertaining to water resources
• Reducing fertilizer/herbicide use
• Reducing chloride use for snow and ice management
• Lawn care practices that prevent organic debris from reaching storm sewer systems
• Household and automobile hazardous waste disposal
• Problems with pet waste and proper disposal
• Litter control
• Recycling and trash disposal
• Composting, leaf collection, and grass clippings
• Residential stormwater drainage
• Native vegetation
• Public area maintenance
• Alternative landscaping methods
• Plantings in buffer zones along wetlands, lakes, and streams
• Car washing
• Reporting illicit discharges
• Water conservation
• Sealing unused private wells
Information will be distributed via the City’s newsletter, the City Extra email notification service, local
newspapers, cable television, social media, workshops, and any other appropriate media.
3.9 NPDES Considerations
Under the federal 1987 Clean Water Act revision, discharges of pollutants into waters of the United States
are prohibited without a permit under the National Pollutant Discharge Elimination System (NPDES)
program. Traditionally, this program concentrated on discharges from industries and publicly owned
treatment plants. In 1990, the EPA promulgated rules establishing Phase I of the NPDES Stormwater
Program in an effort to reduce the water quality impact of stormwater drainage systems on receiving
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water bodies. Phase I of the program regulates stormwater runoff from municipal separate storm sewer
systems (MS4s) generally serving populations of 100,000 or greater, construction activities disturbing five
acres of land or greater, and various industrial activities. In 1999, the Phase II Rule of the NPDES
Stormwater Program extended the coverage of the NPDES program to operation of “small” MS4s in
urbanized areas and operation of small construction sites. Through the use of NPDES permits, these
operations are required to implement programs and practices to control polluted stormwater runoff.
Because the City of Edina is located in an “urbanized area”, as defined by the Bureau of the Census, it is
covered under the Phase II NPDES Stormwater Program. Operators of Phase II small MS4s in Minnesota
were required to apply for coverage under the Small Municipal Separate Storm Sewer Systems (MS4s)
General Permit by March 10, 2003. Under this permit, MS4s are required to develop and implement a
Storm Water Pollution Prevention Program (SWPPP), which must contain the following six control
measures, at a minimum:
1. Public education and outreach on stormwater impacts.
2. Public involvement and public participation.
3. Illicit discharge detection and elimination.
4. Construction site stormwater runoff control.
5. Post-construction stormwater runoff control in new development and redevelopment.
6. Pollution prevention and good housekeeping for municipal operations.
The SWPPP must include Best Management Practices (BMPs) and measurable goals for each of the six
control measures. An annual report detailing the implementation of the control measures for the previous
calendar year must be submitted to the MPCA by June 30 of each year. Water resource management
activities undertaken by the City of Edina through the implementation of this plan exceed the minimum
standards required by the MS4 general permit. Additional information on how the City’s activities align
with the NPDES Phase II MS4 General Permit and SWPPP is provided in Section 15.2.2.
A stormwater conveyance map that meets the standards of the MS4 permit can be found online via the
City’s interactive water resources map. Additional metadata associated with the stormwater conveyance
system is available from the City upon request.
A map showing an inventory of facilities and operations is provided in the City’s SWPPP.
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4.0 Methodology for Modeling
4.1 Methodology for Hydrologic/Hydraulic Modeling
The U.S. EPA’s Stormwater Management Model (SWMM), with a computerized graphical interface
provided by XP Software (XP-SWMM), was chosen as the computer modeling package for this study.
XP-SWMM uses rainfall and watershed characteristics to generate local runoff, which is routed through
pipe and overland flow networks. The model can account for detention in ponding areas, backflow in
pipes, surcharging of manholes, as well as tailwater conditions that may exist and affect upstream storage
or pipe flows. The 5000 node version of XP-SWMM 2014, was used to model the storm sewer, ponding
and overland flow systems within the City of Edina. The City storm sewer system was split into two XP-
SWMM models: one model that reflects the parts of Edina that drain to Minnehaha Creek and one that
reflects the parts of Edina that drain to Nine Mile Creek, with overflow connections between the two
where necessary.
4.1.1 Hydrologic Modeling
Three major types of information are required by XP-SWMM for hydrologic modeling: (1) watershed data,
(2) rainfall data, and (3) infiltration data. This data is used by XP-SWMM to generate inflow hydrographs at
various points into the storm sewer, ponding, and overland flow networks. The following sections describe
each of these data.
4.1.1.1 Watershed Data
The amount of runoff from a watershed depends on numerous factors, including the total watershed area,
the soil types within the watershed, the percent of impervious area, the runoff path through the
watershed, and the slope of the land within the watershed. ESRI’s ArcMap geographic information systems
(GIS) software was used extensively in assessing the above mentioned characteristics of each watershed
within the City. The software also allowed mapping of the drainage network for the area.
Watershed Area
The watershed delineation was based on watersheds delineated for the 2003 CWRMP that were then
modified using newer data including the MnDNR LiDAR elevation data collected in 2011, the updated City
storm sewer GIS data (provided by the City in 2016), and newer aerial imagery. In certain cases, the
watershed divides were field verified. A total of 1,474 separate watersheds were delineated for this
CWRMP update.
Land Use Data
The percent of impervious area within each watershed was estimated using land use data provided by the
City of Edina (Figure 2.2). An electronic land use coverage was provided by the City for the 2003/2011
CWRMPs. For areas outside of the Edina City limits that were included in the model, such as small portions
of Eden Prairie, Bloomington, Hopkins, St. Louis Park, Minneapolis, and Richfield, land use data based on
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the 2010 Metropolitan Council aerial photographs was used. Land use within the study area was divided
into the designations shown in Table 4.1.
The land use information provided by the City categorized residential land use as single-family residential
or multiple-family residential. For modeling purposes, these residential categories were further broken
down based on the density of housing units within the area. The City’s electronic land use coverage and
aerial imagery was used in ArcMap to determine the density of the residential areas. The single-family
residential areas were further categorized as very low density residential (<1 unit/acre) or low density
residential (1-4 units/acre). The areas categorized as multiple-family residential by the City were broken
down into the following categories: low density residential (1-4 units/acre), medium density residential
(4-8 units/acre), and high density residential (>8 units/acre).
The land use type “Other” is new to the analysis for this CWRMP update. The “Other” land use type
essentially reflects railroad corridors and is about 20% impervious.
The land use categories were used to estimate the total and “directly-connected” impervious fractions for
each subwatershed within the study area. The total impervious fraction of a watershed represents the
portion of the watershed that is covered by an impervious surface. The “directly-connected” impervious
fraction represents the impervious surfaces that are hydraulically connected to a stormwater conveyance
system. For example, if a rooftop drains onto an adjacent pervious area such as a yard, it is not a “directly-
connected” impervious area. However, if a rooftop drains onto a driveway, which drains to the street and
then to a stormwater catch basin, the rooftop would be a “directly-connected” impervious area.
A separate study estimating the total impervious fraction and the “directly-connected” impervious fraction
for each land use type was completed in October 2016 (City of Edina Imperviousness Assumptions for
Stormwater Modeling, Barr Engineering, 2016; also attached in Appendix A) using the land use layer from
the City, and a 2011 gridded impervious layer of the City from the University of Minnesota. Resulting
imperviousness for each land use type throughout the City are listed in Table 4.1. The “directly-
connected” imperviousness for each watershed was calculated as an area-weighted average of the
different land use types existing within the watershed.
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Table 4.1 Land Use Impervious Fraction Assumptions for Hydrologic Modeling
Land Use Designation
Total
Impervious %
Directly-Connected
Impervious %
Commercial 85% 80%
Developed Park 30% 20%
Golf Course 5% 2%
High Density Residential 65% 50%
Highway 65% 65%
Industrial/Office 75% 75%
Institutional 60% 30%
Institutional - High Imperviousness 80% 70%
Low Density Residential 40% 25%
Medium Density Residential 50% 40%
Natural/Park/Open 2% 0%
Open Water 100% 100%
Other 20% 20%
Very Low Density Residential 25% 15%
Wetland 100% 100%
Watershed Width and Slope
The SWMM Runoff Non-linear Reservoir Method was used as the hydrograph generation technique for
this project. This method computes outflow as the product of velocity, depth and a watershed width
factor. The watershed “width” in XP-SWMM is defined as twice the length of the main drainage channel,
with adjustments made for watersheds that are skewed (i.e., the areas on both sides of the main drainage
channel are not equal). This factor is a key parameter in determining the shape of the hydrograph for each
watershed and is often used as a calibration parameter. To determine the width parameter, the main
drainage channel for each watershed was digitized in ArcMap and a customized ArcMap script was used
to calculate the width based on the skew of the drainage path within the subwatershed. For this CWRMP
update, the widths of unchanged or slightly modified watersheds were left the same. Only in watersheds
where the boundary was significantly modified or the watershed was subdivided were the widths
recalculated using the method described above.
The average slope (feet/feet) for each watershed was calculated in ArcMap using the electronic gridded
topographic LiDAR data. The slope was then determined for each grid cell by calculating the steepest
slope in any direction. The average of all of the gridded slope values within each watershed was then used
as the representative slope of the watershed.
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4.1.1.2 Rainfall Data
Storm events for several return periods were analyzed in this study: the 1-percent-annual-chance 24-hour
storm, the 10-percent-annual-chance ½ hour storm, and the 1-percent-annual-chance 10-day snowmelt
event. For the 1-percent-annual-chance return period, a nested distribution was applied to a total rainfall
depth of 7.47 inches, based on the National Oceanic and Atmospheric Administration’s Atlas 14 Volume 8
precipitation frequency curves. A nested distribution was selected to be consistent with the XP-SWMM
models of Nine Mile Creek and Minnehaha Creek which are incorporated in the City’s model as tailwater
conditions. For the snowmelt event, a longer 10-day distribution that has historically been used was
applied to a total of 7.2 inches with no losses (generating 7.2 inches of runoff). A precipitation depth of
1.65 inches was used for the 10-percent-annual-chance ½ hour storm,
4.1.1.3 Infiltration Data
Soils
Soils data for the City of Edina was obtained through two sources: the 2012 Natural Resources
Conservation Service Soil Survey Geographic (SSURGO) Database and the soils layer used for the
modeling effort associated with the 2003 CWRMP.
The hydrologic soil group (HSG) designation classifies soils into groups (A, B, C, and D) based on the
infiltration capacity of the soil (well drained, sandy soils are classified as “A” soils; poorly drained, clayey
soils are classified as “D” soils). When a HSG designation was not included in the new SSURGO soils
database, the 2003 CWRMP HSGs were used. For the 2003 modeling effort, when a HSG designation was
not included in the soils database, the soil description was used to estimate the HSG. If a soil description
was unavailable, the most dominant soil group in the vicinity was assumed. Although all soil types are
represented in the City (Figure 2.2), the predominant soil type in the City is Type B (sandy loam).
Horton Infiltration
Infiltration was simulated in the XP-SWMM models using the Horton Infiltration equation. This equation is
used to represent the exponential decay of infiltration capacity of the soil that occurs during heavy storm
events. The soil infiltration capacity is a function of the following variables: Fc (minimum or ultimate value
of infiltration capacity), Fo (maximum or initial value of infiltration capacity), k (decay coefficient), and time.
The actual values of Fc, Fo, and k are dependent upon soil, vegetation, and initial moisture conditions prior
to a rainfall event. Because it was not feasible to obtain this detailed information for each subwatershed
through field samples, it was necessary to make assumptions based on the various soil types throughout
the City. Table 4.2 summarizes the Horton infiltration values used for each Hydrologic Soil Group to
calculate composite infiltration parameters for each subwatershed. The values shown in the table are
based on suggested values in the Stormwater Management Model, Version 4: User’s Manual, U.S. EPA,
1988. Composite Fc and Fo values were calculated for each subwatershed based on the fraction of each
soil type within the subwatershed. Global databases containing the infiltration parameters for each
subwatershed were developed and imported into the XP-SWMM models.
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Table 4.2 Horton Infiltration Parameters
Hydrologic Soil Group Fo (in/hr) Fc (in/hr) k (1/sec)
A 5 0.38 0.00115
B 3 0.23 0.00115
C 2 0.1 0.00115
D 1 0.03 0.00115
4.1.1.4 Depression Storage Data
Depression storage represents the volume (in inches) that must be filled with rainfall prior to the
occurrence of runoff in XP-SWMM. It characterizes the loss or "initial abstraction" caused by such
phenomena as surface ponding, surface wetting, interception and evaporation. Separate depression
storage input values are required in XP-SWMM for pervious and impervious areas.
The depression storage assumptions used for the models were based on the values used in the
XP-SWMM model developed for the Nine Mile Creek Watershed District Bloomington Use Attainability
Analysis, Barr Engineering, 2001. For this model, the depression storage was estimated by plotting total
precipitation for several measured rainfall events at a Bloomington continuous recording precipitation
gage versus runoff from several Bloomington monitoring sites. A regression of the data yielded a y-
intercept that was assumed to be the depression storage (in inches). Based on this analysis, the assumed
impervious depression storage was 0.06 inches and the pervious depression storage was 0.17 inches.
XP-SWMM also uses a “Zero Detention Storage” parameter to account for areas that generate immediate
runoff (i.e., water surface areas). This parameter was estimated for each subwatershed by dividing the
water surface area by the directly connected impervious surface area.
4.1.1.5 Overland Flow Roughness
The SWMM Runoff Non-linear Reservoir Method requires an estimate of the roughness of both pervious
and impervious areas in the watershed. These values were calibrated in the Nine Mile Creek Watershed
District Bloomington Use Attainability Analysis (Barr Engineering, 2001) and were used in previous
CWRMPs as well as this CWRMP. The values for impervious area and for pervious area are 0.200 and
0.355, respectively.
4.1.2 Hydraulic Modeling
4.1.2.1 Storm Sewer Network
Data detailing the storm sewer network within the City of Edina was provided by the City. An electronic
GIS feature dataset provided detailed information on the storm sewer system, including the type of pipe
(material of construction), invert elevations, pipe sizes, pipe lengths, and manhole rim elevations. Where
this data was incomplete, additional information was obtained from other sources such as construction
plans, field surveys, or previous modeling efforts. All elevations entered into the model reflect the
National Geodetic Vertical Datum of 1929 (NGVD29).
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Assumptions
A variety of pipe types are used throughout the City. The assumptions used for the roughness coefficient
(Manning’s “n”) for each pipe type are listed in Table 4.3.
Table 4.3 Roughness Coefficient Assumptions
Pipe Type Abbreviation Assumed Roughness Coefficient
Corrugated Metal Pipe CMP 0.024
Clay - 0.015
Steel - 0.015
Ductile Iron Pipe DIP 0.014
Reinforced-Concrete Pipe RCP 0.013
Poly Vinyl Chloride PVC 0.01
High Density Polyethylene HDPE 0.008
Outlets from ponding areas that may be inlet controlled were modeled in XP-SWMM assuming a groove
end projecting concrete pipe inlet condition. This allowed XP-SWMM to determine the controlling flow
condition in the outlet pipe (i.e., is the flow in the pipe controlled by the inlet size, barrel capacity, or
tailwater conditions) and accurately estimate the pond’s water surface elevation.
Surface inundation, or flooding, occurs when the runoff from the watershed exceeds the capacity of the
storm sewer system to convey the stormwater downstream. Capacity of the storm sewer system can be
limited by either the capacity of the storm sewer pipes or the inlet capacity (i.e., flow through catch basins
and other minor roadway inlets into storm sewer pipes). For most of the city, the XP-SWMM model does
not include inlet capacity, due to the high-level of detail required. Therefore, model results reflect the
capacity of the storm sewer system and may not fully characterize the existing flood risk where inlet
capacity is restrictive. Inlet capacity was modeled for certain areas of the city were additional detailed
analysis was performed. Tables *.3 in Sections 5.0 through 14.0 identify where inlet capacity was
modeled.
4.1.2.2 Tailwater Effects
For the portion of the City that drains to Nine Mile Creek, the City XP-SWMM model incorporated the
relevant portions of the Nine Mile Creek XP-SWMM model to more accurately account for tailwater
impacts from the creek.
For the portion of the City that drains to Minnehaha Creek, the City XP-SWMM model uses the tailwater
elevations (stage hydrographs) along the creek system as boundary conditions for each corresponding
storm event (i.e., the Minnehaha Creek model provided by Wenck Associates is not integrated into the
City model, but the creek model is used to establish boundary conditions). A more detailed description of
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the Nine Mile Creek and Minnehaha Creek model development, as well as a description of how the
tailwater conditions were incorporated into the City of Edina models is provided in Appendix B.
4.1.2.3 Overland Flow Network
Overland flow networks were entered into the XP-SWMM models because preliminary modeling results
indicated that water was being routed out of the systems and lost (i.e., manholes and ponding areas
would surcharge and the model assumed the water disappeared once it exceeded the respective spill
crest elevation). An iterative process was used by adding storage and overland flow network data until all
of the stormwater had been accounted for by XP-SWMM. Data for the overland flow network were
primarily based on MnDNR 2011 LiDAR elevation data (ground surface), and in some cases, site visits or
storm sewer data from the City.
Storage was also added to XP-SWMM nodes based on the MnDNR 2011 LiDAR elevation. The storage
curves were defined as depth-area tables, at depth increments of 0.2 feet. Initially, storage was added only
to the XP-SWMM nodes representing ponds or backyard depression areas. After the initial model runs,
storage was added to subwatersheds where ponding or surface inundation occurs (e.g., parking lots).
Overland flow paths were added with the following characteristics:
Overland flow along streets
• Trapezoidal channels
• Bottom width = 16 feet (approx. ½ street width), or 32 feet if the entire street is flowing
• Side slopes = 1H:1V
• Manning’s “n” for the surface flow channels was set equal to 0.014 for flow down paved streets
• Channel depth = 1 foot
Natural overland flow paths
• Trapezoidal channels
• Bottom width = variable based on topographic information. Typically an estimate of 10 feet was
used.
• Side slopes = variable based on topographic information. Typically 5H:1V was used.
• Manning’s “n” = 0.035 where overland flow was clearly over vegetated areas or onto boulevards.
• Channel depth = 1 foot or deeper where necessary.
4.1.3 Stormwater System Analysis
Ten- and 1-percent-annual-chance frequency flood analyses were performed for all of the major drainage
basins. The 10-percent-annual-chance analysis was based on a ½-hour storm with 1.65 inches of rain. The
1-percent-annual-chance analysis was based on a 24-hour storm event with 7.47 inches of rain. Tables *.2
present the watershed information and the results for the 10- and 1-percent-annual-chance frequency
hydrologic analyses.
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The results of the 10- and 1-percent-annual-chance frequency hydraulic analyses for each of the major
drainage basins is summarized in Tables *.3. The column headings in Tables *.3 are defined as follows:
Subwatershed or Node—XP-SWMM node identification label—Each XP-SWMM node represents a
manhole, catch basin, pond, or other junction within the stormwater system.
Type of Storage—Defines the type of storage at storage node locations.
Outlet Elevation—The control elevation of the outlet.
Flood Elevation—The maximum water elevation reached in the given pond/manhole for each
referenced event.
Flood Bounce—The fluctuation of the water level within a given pond for each referenced event.
Figures *.3 illustrate the results of the 10- and 1-percent-annual-chance frequency hydraulic analyses.
Each figure depicts the drainage basin boundary, subwatershed boundaries, the modeled storm sewer
network, surcharge conditions for the XP-SWMM nodes (typically manholes), and the flood-prone areas
identified in the modeling analyses.
One objective of the hydraulic analyses was to evaluate the level of service provided by the current storm
sewer system. The level of service was examined by determining the surcharge conditions of the manholes
and catch basins within the storm sewer system during the 10- and 1-percent-annual-chance frequency
storm events. An XP-SWMM node was considered surcharged if the hydraulic grade line at that node
breached the ground surface (rim elevation). Surcharging is typically the result of limited downstream
capacity and tailwater impacts. The XP-SWMM nodes depicted on Figures *.3 were color-coded based on
the modeled surcharge conditions. The green nodes signify no surcharging occurred during the 10- or
1-percent-annual-chance storm events, the yellow nodes indicate surcharging during the 1-percent-
annual-chance event, and the red nodes identify that surcharging is likely to occur during both the
10- and 1-percent-annual-chance frequency storm events. Figures *.3 illustrate that several XP-SWMM
nodes within each major drainage basin are predicted to surcharge during both the 10- and 1-percent-
annual-chance event. This means that in any year there is a greater than 10 percent probability that the
system will be overburdened and unable to meet the desired level of service at these locations. These
manholes and catch basins are more likely to become inundated during the smaller, more frequent storm
events of various durations.
Another objective of the hydraulic analyses was to evaluate the level of protection offered by the current
stormwater system. Level of protection is defined as the pipe and overland overflow capacity provided by
a municipal drainage system to prevent property damage and assure a reasonable degree of public safety
following a rainstorm. A 1-percent-annual-chance event is recommended as a standard for the design of
stormwater management basins. To evaluate the level of protection of the stormwater system within each
major drainage area, the 1-percent-annual-chance frequency flood elevations for the ponding basins and
depressed areas were compared to the approximate low elevations of structures surrounding each basin.
The approximate low elevations were determined using the 2011 MnDNR LiDAR elevation data in ArcMap.
The LiDAR elevation may not be representative of the actual lowest elevation, therefore a field survey
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would need to be conducted to determine potential impacts. The inundation areas predicted to
potentially impact structures during the 1-percent-annual-chance storm event are shown in Figures *.3.
Discussion and recommended improvement considerations for these areas are included in Sections 5.0
through 14.0.
4.1.3.1 Problem Areas Selection Process
The Atlas 14 XP-SWMM modeling analysis identified many locations throughout the city where the
1-percent-annual-chance flood elevations appears to impact roadways and/or structures. As part of this
plan, some of these flood-prone areas were evaluated further (at varying levels of detail) to better
understand the problem(s) and identify potential improvement options. The discussion below summarizes
the approach taken to identify and categorize the most severe flood-prone areas throughout the city.
The criteria summarized below were used to identify and categorize the most severe flood-prone areas
throughout the city, based on the potential to impact City infrastructure, buildings, and/or homes. The
inundation areas were given a score based on meeting some or all of the following criteria that are based
on 1-percent-annual-chance flood event modeling results (except where otherwise noted):
• 1 point for each potentially impacted residential home
• 1 point for each potentially impacted apartment building
• 1 point for each potentially impacted commercial building, as defined by a GIS structure layer
provided by the City
• 1 point for road flooding for roads identified as an evacuation route, as defined by an evacuation
route GIS layer provided by the City
• 1 point for each area where the depth of flooding over a road is greater than or equal to 2 feet,
and the road is not an evacuation route, with evacuation routes defined by a GIS layer provided
by the City
• 1 point for each area where a public building (school, church, fire station, daycare) is potentially
impacted with public buildings defined by a GIS layer provided by the City
• 1 point for each area where the flooding problem is a regional problem (versus flooding in a
backyard depression area with no outlet)
• 2 points for each area where the flooding from the 10-percent-annual-chance precipitation event
is similar to the 1-percent-annual-chance precipitation event, indicating higher probability of
impacts
• 2 to 14 points based on the duration of flooding during the 1-percent-annual-chance
precipitation event. Areas where the lowest structure is potentially impacted for a short time (less
than 1 hour) received 2 points, whereas areas where the lowest structure is potentially impacted
for a long time (greater than 72 hours) received 14 points.
• 3 points for any area that impacts a water facility (treatment, wells, towers, etc.), as identified by a
GIS layer provided by the City
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The top 80 flood-prone areas were identified (“registered”) as most severe, based on the criteria
presented above. In general, inundation areas that potentially impacted less than five residential homes
with no other criterion did not register within the top approximately 80 identified flood-prone areas.
The registered flood-prone areas were reviewed further; five areas were selected to be studied in detail
and another 20 areas were selected for a screening-level review. The identification process was objective,
data-driven, and was collaborative between City staff and Barr Engineering staff. The resulting 25 flood-
prone areas that were identified for further study during this 2018 CWRMP update are discussed in
Sections 5.0 through 14.0. Detailed study of the five areas consisted of evaluating the nature of the
problem based on modeling results, and identifying and modeling potential improvement options to
reduce flood risk, including combinations of the proposed improvement options. For the 20 flood-prone
areas selected for a screening level analysis, a desktop review was conducted to assess the nature of the
problem and identify potential improvement options (without additional modeling analysis).
The remaining registered flood-prone areas that weren’t evaluated in detail or at a screening level are
included for future evaluation. Inundation areas that didn’t register in the top 80 areas are not described
further in the narrative of this plan; however, they are shown on inundation maps in Sections 5.0 through
14.0
4.2 Methodology for Water Quality Modeling
Water quality modeling was not updated for the 2018 CWRMP. The following sections are based on the
work completed for the 2003 CWRMP. As described in Section 15.2.3, the City will be developing a Clean
Water strategy to target and prioritize pollutant reduction.
P8 (Program for Predicting Polluting Particle Passage through Pits, Puddles and Ponds, IEP, Inc., 1990) is a
computer model used for predicting the generation and transport of stormwater runoff pollutants in
urban watersheds. The P8 model was used in this study to simulate the hydrology and phosphorus loads
introduced from the watershed of each pond and the transport of phosphorus throughout the stormwater
system. P8 is a useful diagnostic tool for evaluating and designing watershed improvements and BMPs.
The model requires user input on watershed characteristics, pond attributes, local precipitation and
temperature, and other parameters relating to water quality and pond removal performances.
4.2.1 Watershed Characteristics
Examination of the watershed characteristics for each pond being modeled involved assessment of soil
type, land use and residential density, and the impervious fraction of the land in the watershed. ArcMap
software was used extensively in assessing the watershed characteristics. The software also allowed
mapping of the drainage network for the area.
In P8, pervious and impervious areas are modeled separately. Runoff volumes from pervious areas are
computed using the Soil Conservation Service (SCS) Curve Number method. Runoff from impervious areas
begins once the cumulative storm rainfall exceeds the specified depression storage, with the runoff rate
equal to the rainfall intensity.
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4.2.1.1 Impervious Fraction
Because P8 calculates runoff separately from pervious and impervious areas, it was necessary to
determine the impervious fraction of each watershed. For the P8 model, the impervious fraction included
only the directly-connected impervious area, the impervious surfaces that are “connected” directly to a
stormwater conveyance system, where stormwater does not cross over pervious areas. The directly-
connected impervious fraction was calculated for each watershed based on the land use(s) within the
watershed and impervious fraction assumptions for each land use. The assumptions made for the total
impervious fraction and directly-connected impervious fraction for each land use for the water quality
modeling are listed in Table 4.4.
Table 4.4 Land Use Impervious Fraction Assumptions for Water Quality Modeling
Land Use Designation Total Impervious %
Directly-Connected
Impervious %
Commercial 90% 80%
Golf Course 5% 2%
Highway 50% 50%
Industrial/Office 90% 80%
Institutional 40% 20%
Institutional- High Imperviousness 70% 50%
Natural/Park/Open 2% 0%
Open Water 100% 0%
Residential- Very Low Density 12% 8%
Residential- Low Density 40% 20%
Residential- Medium Density 55% 30%
Residential- High Density 70% 40%
Wetlands 0% 0%
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4.2.1.2 Pervious Curve Number
Watershed runoff volumes from pervious areas are computed in P8 using the SCS Curve Number method.
Thus, it was necessary to determine a pervious curve number for each watershed. The soil type(s) within
each watershed were determined and a pervious curve number was selected for the watershed based on
the soil type, land use, and hydrologic conditions (e.g., if watershed soils are Type B and pervious areas
comprise grassed areas with >75 percent cover, then a curve number of 61 would be selected). The
pervious curve number was then weighted with the indirect (i.e., unconnected) impervious area in each
subwatershed as follows:
()()[]Area) (PerviousArea Impervious Indirect
Number)] Curve (Pervious* Area) [(Pervious +(98)] * Area Impervious Indirect[ = CNwt +
4.2.1.3 Other P8 Watershed Input Parameters
Outflow Device Number: The Device Number of the device receiving runoff from the watersheds was
selected to match the pond or manhole node ID used for the hydrologic/hydraulic modeling.
Swept/Not Swept: An “Unswept” assumption was made for the entire impervious watershed area. A
Sweeping Frequency of 0 was selected. Selected parameters were placed in the “Unswept” column since a
sweeping frequency of 0 was selected.
Depression Storage = 0.03 (P8 default value)
Impervious Runoff Coefficient = 0.94 (P8 default value)
4.2.2 Treatment Device Characteristics
The treatment devices in P8 provide collection, storage, and/or treatment of watershed discharges. A
variety of treatment devices can be modeled in P8, including detention ponds (wet or dry), infiltration
basins, swales and buffers, aquifers, and pipe/manholes. For this study, nearly all ponds were modeled as
detention basins. The user-defined characteristics of these ponds are described in the following sections.
4.2.2.1 Dead Storage
Detailed information pertaining to the permanent pool storage volume (dead storage) was only available
for a small number of the ponds that were modeled. Pond depth data for the ponds in the Mirror Lake
watershed was available as a result of pond surveys being performed for the Draft Mirror Lake Use
Attainability Analysis (Barr Engineering, 2004). Pond depth information for Indianhead Lake was available
from the MnDNR. Where detailed information on pond depths was not available, it was necessary to make
assumptions. The surface area of each pond was determined from the 2-foot topographic information
provided by the City. Where detailed information was not available, pond depths were estimated based
on the type of wetland, which was determined in the wetland inventory process. An average depth of
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4 feet was typically assumed for Type 5 wetlands; 2 feet for Type 3 and Type 4 wetlands; 0.5 feet for
Type 1, 2, 6, and 7 wetlands.
4.2.2.2 Live Storage
The flood pool storage volume (live storage) for each pond was calculated in ArcMap using the electronic
topographic data provided by the City. The live storage represents the storage volume between the
normal water elevation and the flood elevation. The overflow elevation from each pond was determined
from the 2-foot topographic data. The live storage volume was then calculated in ArcMap based on the
slope of the flood pool.
4.2.2.3 Other P8 Treatment Device Input Characteristics
Infiltration Rate (in/hr): An infiltration rate was entered only for land-locked detention ponds. The rates
applied were dependent upon the type of soil surrounding each pond. The infiltration rates used for each
soil type are listed in Table 4.5.
Table 4.5 Infiltration Assumptions for Water Quality Modeling
Hydrologic Soil Group
Infiltration Rate Assumption
for Dead Storage Areas
[in/hr]
Infiltration Rate Assumption
for Live Storage Areas
[in/hr]
A 0.02 0.06
B 0.015 0.05
C 0.015 0.02
D 0.005 0.01
• Orifice Diameter and Weir Length: The orifice diameter or weir length of the pond outlet was
determined from storm sewer system data provided by the City of Edina. For landlocked basins,
the overflow was represented as a weir, with the weir length estimated using ArcMap and
available topographic information.
• Particle Removal Scale Factor: 0.3 for ponds less than 2 feet deep and 1.0 for all ponds 3 feet
deep or greater. For ponds with normal water depths between 2 and 3 feet, a particle removal
factor of 0.6 was selected. These factors were selected based on development of a similar P8
model for the Round Lake Use Attainability Analysis (Barr Engineering, 1999).
• Pipe/Manhole— Time of Concentration: The time of concentration for each pipe/manhole
device was determined and entered here. Time of concentration was determined in accordance
with Kirpich’s method (Schwab et al., 1993).
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4.2.3 Precipitation and Temperature Data
The P8 model requires hourly precipitation and daily temperature data; long-term data can be used so
that watersheds and BMPs can be evaluated for varying hydrologic conditions. Hourly precipitation data
was obtained from the Minneapolis-St. Paul International Airport for October 1994 through September
1995 (1995 water year, which represents average yearly precipitation). Average daily temperature data was
obtained from the National Weather Service site at the Minneapolis-St. Paul International Airport.
4.2.4 Selection of Other P8 Model Parameters
4.2.4.1 Time Step, Snowmelt, and Runoff Parameters
• Time Steps per Hour (Integer) = varied. This parameter varied between each P8 model.
Selection was based upon the number of time steps required to eliminate continuity errors
greater than 2 percent.
• Minimum Inter-Event Time (Hours) = 10. The selection of this parameter was based upon an
evaluation of storm hydrographs from the summer of 1999 to determine which storms should be
combined and which storms should be separated to accurately depict runoff from the lake’s
watershed. Precipitation data from 1999 was used for the analysis due to the high frequency of
storms during the summer, particularly during July.
• Snowmelt Factors—Melt Coef (Inches/Day-Deg-F) = 0.03. The P8 model predicts snowmelt
runoff beginning and ending earlier than observed snowmelt. The lowest coefficient of the
recommended range was selected to minimize the disparity between observed and predicted
snowmelt (i.e., the coefficient minimizes the number of inches of snow melted per day and
maximizes the number of snowmelt runoff days).
• Snowmelt Factors— Scale Factor for Max Abstraction = 1. This factor controls the quantity of
snowmelt runoff (i.e., controls losses due to infiltration). Selection of this factor was based upon
other calibrated P8 models developed for lakes within the metropolitan area (Reference Glen
Lake, Smetana Lake).
• Growing Season AMC-II = .05 and AMC-III = 100. Selection of this factor was based upon
calibration efforts for the P8 model developed for the Glen Lake Use Attainability Analysis (Barr
Engineering, 1999). In development of this calibrated model, it was observed that the model
accurately predicted runoff water volumes from monitored watersheds when the Antecedent
Moisture Condition II was selected (i.e., curve numbers selected by the model are based upon
antecedent moisture conditions). Modeled water volumes were less than observed volumes when
Antecedent Moisture Condition I was selected, and modeled water volumes exceeded observed
volumes when Antecedent Moisture Condition III was selected. The selected parameters direct the
model to only use Antecedent Moisture Condition I when less than 0.05 inches of rainfall occur
during the 5 days prior to a rainfall event and to only use Antecedent Moisture Condition III if
more than 100 inches of rainfall occur within 5 days prior to a rainfall event, thus causing the
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model to simulate Antecedent Moisture Condition II throughout the majority of the simulation
period.
4.2.4.2 Particle File Selection
The NURP50.PAR file was selected for the P8 models. The NURP 50 particle file represents typical
concentrations and the distribution of particle settling velocities for a number of stormwater pollutants.
The component concentrations in the NURP 50 file were calibrated to the 50th percentile (median) values
compiled in the U.S. EPA’s Nationwide Urban Runoff Program (NURP).
4.2.4.3 Passes through the Storm File
The number of passes through the storm file was determined after the model had been set up and a
preliminary run completed. The selection of the number of passes through the storm file was based upon
the number required to achieve model stability. Multiple passes through the storm file were required
because the model assumes that dead storage waters contain no pollutants. Consequently, the first pass
through the storm file results in lower pollutant loading than occurs with subsequent passes. Stability
occurs when subsequent passes do not result in a change in pollutant concentration in the pond waters.
To determine the number of passes to select, the model was run with five passes and 10 passes. A
comparison of pollutant predictions for all devices was evaluated to determine whether changes occurred
between the two scenarios. If there is no difference between five and 10 passes, five passes is sufficient to
achieve model stability. This parameter was determined for all of the P8 model areas and no differences
were noted between five and 10 passes. Therefore, it was determined that five passes through the storm
file resulted in model stability for these models.
4.2.5 Stormwater System Analysis
The effectiveness of the stormwater system in removing stormwater pollutants such as phosphorus was
analyzed using the P8 water quality model. The P8 model simulates the hydrology and phosphorus loads
introduced from each pond’s watershed and the transport of phosphorus throughout the stormwater
system. Since site-specific data on pollutant wash-off rates and sediment characteristics were not
available, it was necessary to make assumptions based on national average values. Because of these
assumptions and lack of in-lake water quality data for model calibration, the analysis of modeling results
was based on the percent of phosphorus removed and not on actual phosphorus concentrations.
Figures *.4 depict the results of the water quality modeling for each of the major drainage basins. The
figure shows the fraction of total phosphorus removal for each water body as well as the cumulative total
phosphorus removal in the watershed. The individual water bodies are colored various shades of blue,
indicating the percent of the total annual mass of phosphorus entering the water body that is removed
(through settling). It is important to note that the percent of phosphorus removed is based on total
phosphorus, including phosphorus in the soluble form. Therefore, the removal rates in downstream ponds
will likely decrease due to large soluble fractions of incoming phosphorus that could not settle in
upstream ponds. The watersheds are depicted in various shades of gray, indicating the cumulative total
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phosphorus removal achieved. The cumulative percent removal represents the percent of the total annual
mass of phosphorus entering the watershed that is removed by the pond and all upstream ponds.
Ponds that had an average annual total phosphorus removal rate of 60 percent or greater under average
climatic conditions were considered to be performing well. For ponds with total phosphorus removal
below 60 percent, the permanent pool storage volume was analyzed to determine whether additional
capacity is necessary. Based on recommendations from the MPCA publication Protecting Water Quality in
Urban Areas (March 2000), the permanent pool for detention ponds should be equal to or greater than
the runoff from a 2.0-inch rainfall, plus sediment storage for at least 25 years of accumulation. This
recommended permanent pool storage volume was calculated for each pond with less than 60 percent
total phosphorus removal and compared to the existing storage volume.
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5.0 Nine Mile Creek—North
5.1 General Description of Drainage Area
Figure 5.1 depicts the Nine Mile Creek—North drainage basin. The Nine Mile Creek—North drainage area
is located in the northwest portion of Edina. The drainage basin encompasses approximately 2,050 acres
that ultimately drain to the stretch of Nine Mile Creek between the intersection of the North fork with
TH 169 and TH 62.
5.1.1 Drainage Patterns
The stormwater system within this drainage area comprises storm sewers, ponding basins, wetlands,
drainage ditches, and overland flow paths. The Nine Mile Creek—North drainage basin has been divided
into several major watersheds based on the drainage patterns. These major watersheds are depicted in
Figure 5.2. Each major watershed has been further delineated into numerous subwatersheds. The naming
convention for each subwatershed is based on the major watershed where it is located. Table 5.1 lists
each major watershed and the associated subwatershed naming convention.
Table 5.1 Major Watersheds within the Nine Mile Creek—North Drainage Basin
Major Watershed
Subwatershed Naming
Convention Number of Subwatersheds Drainage Area (acres)
Mirror Lake ML_## 40 288
Highlands Lake HI_## 23 276
Hawkes Lake HL_## 54 336
Mud Lake MD_## 51 432
Nine Mile North NMN_## / EdCrk## 91 718
5.1.1.1 Mirror Lake
The Mirror Lake watershed is located in the northwest portion of Edina. The 288-acre watershed contains
six ponding basins of varying sizes that drain to Mirror Lake via storm sewer. There are also three
landlocked ponds within the watershed. The Mirror Lake watershed is almost entirely residential area, with
the exception of a few subwatersheds that are a part of the Interlachen Country Club golf course. Mirror
Lake spans approximately 26.5 acres. The water level of the lake is controlled at an elevation of
approximately 904 feet by a pumped outlet (4 cfs) on the southwest side of the lake. The pumped outlet
flows in a southwest direction and eventually connects to the storm sewer system along Blake Road.
5.1.1.2 Highlands Lake
The Highlands Lake watershed is located east of Mirror Lake and north of Vernon Avenue. This 276-acre
watershed is bordered on the north by Interlachen Boulevard and portions of the Interlachen Country
Club golf course. The Highlands Lake watershed has been delineated into 23 subwatersheds, with land use
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characterized by residential areas, part of the Interlachen golf course, several ponding basins that
ultimately drain to Highlands Lake, a wetland area directly east of the lake, Highlands Park directly south
of the lake, and a portion of the drainage from Highlands Elementary School. Highlands Lake spans
approximately 10.6 acres. The water level of Highlands Lake is controlled at elevation of 888.5 feet by a
pumped outlet (approximately 1 cfs). The lift station was installed in 1994 and is located in the southwest
corner of Highlands Park, near the intersection of Ayrshire Boulevard and Glengarry Parkway. Water from
the pumped outlet flows south, connecting with the storm sewer system along Vernon Avenue, which
discharges into Hawkes Lake.
5.1.1.3 Hawkes Lake
The Hawkes Lake watershed is located south of the Highlands Lake watershed. The 336-acre watershed
comprises 54 subwatersheds. Land use within the watershed includes residential (low and high density),
institutional, open space/parks, and a small commercial area. Portions of Highland Elementary and
Countryside Elementary drain to Hawkes Lake. Garden Park is also located within this watershed. There are
several ponding basins within the watershed that drain to Hawkes Lake via drainage ditches and storm
sewer systems. Hawkes Lake spans approximately 8.7 acres. A pumped outlet at an elevation of 888 feet
prevents flooding conditions in Hawkes Lake. However, the average water level for this lake between the
period of 1963 to 2001 is 885.5 feet (MnDNR Lake Finder webpage
http://www.dnr.state.mn.us/lakefind/index.html). The pumped outlet, located on the western side of the
lake near the intersection of Wycliffe Road and Merold Drive, discharges southwest into the Mud Lake
watershed.
5.1.1.4 Mud Lake (Bredesen Park)
The Mud Lake watershed spans an area of approximately 432 acres and is composed of
51 subwatersheds. The land use within the Mud Lake watershed is predominantly residential (ranging
from very low to medium density). The watershed has a complex drainage system characterized by
numerous ponding basins connected by storm sewer and a unique diversion structure that routes
stormwater from the northwest portion of the watershed to the North Fork of Nine Mile Creek or Mud
Lake, depending on the amount of precipitation and the water level of the pond near the structure. The
diversion structure is located within a manhole on Blake Road, between Saxony Road and Jeffrey Lane,
and receives water from the upstream Blake Road storm sewer system and Mirror Lake outlet. The
structure controls the amount of incoming water that flows southward toward Mud Lake or into the pond
directly west of Blake Road and encircled by Knoll Drive (Knoll Pond). A small orifice in the structure
directs flows from small precipitation events southward to Mud Lake. A weir structure within the manhole
directs larger stormwater flows into the adjacent Knoll Pond. During large rain events, stormwater will
continue to flow into Knoll Pond until the water level within the pond has equalized with the weir
elevation; at that point, the remainder of the water will drain south towards Mud Lake. In the event that
inflow to Knoll Pond from upstream watersheds surpasses the capacity of the normal outlet to the North
Fork of Nine Mile Creek, the diversion structure will act as a second overflow from the pond, directing
water to Mud Lake.
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Mud Lake is a meandered lake located just east of the North Fork of Nine Mile Creek, between TH 62 and
Vernon Avenue. The lake and surrounding wetlands are part of Bredesen Park. The park spans an area of
approximately 126 acres and is a mix of open water, wet marsh, and floating bog. Mud Lake outlets to the
North Fork of Nine Mile Creek just north of TH 62 through a culvert at elevation 849 feet.
5.1.1.5 Nine Mile North
The Nine Mile North watershed encompasses the area in northwest Edina that drains directly to the
floodplain of the North Fork of Nine Mile Creek. The floodplain within this area is relatively flat and is
characterized by wetland conditions. The Nine Mile North watershed is bounded by TH 169 on the west
and Schaeffer Road on the east, extending north to Malibu Drive and south to TH 62. The 718-acre
watershed consists of 91 subwatersheds that drain to the creek through a series of storm sewer systems
and stormwater detention ponds. There are a wide range of land uses within the watershed, including
residential (very low density, low density, and medium density), industrial, commercial, highway, wetlands,
and natural/park area.
5.2 Stormwater System Results
5.2.1 Hydrologic/Hydraulic Modeling Results
The 10- and 1-percent-annual-chance flood analyses were performed for the Nine Mile Creek—North
drainage basin. The 10-percent-annual-chance analysis was based on a ½-hour storm with 1.65 inches of
rain. The 1-percent-annual-chance analysis was based on a 24-hour storm event with 7.47 inches of rain
and on a 10-day snowmelt event with 7.2 inches of runoff; the higher resulting flood level of the two
events was chosen for the 1-percent-annual-chance analysis Table 5.2 presents the watershed
information and results for the 10- and 1-percent-annual-chance frequency hydrologic analyses for the
Nine Mile Creek—North basin. A more detailed description of the stormwater system analysis is provided
in Section 4.1.3.
The results of the 10- and 1-percent-annual-chance frequency hydraulic analysis for the Nine Mile
Creek—North drainage basin are summarized in Table 5.3.
Figure 5.3 illustrates the results of the 1-percent-annual-chance frequency hydraulic analyses. The figure
depicts the Nine Mile Creek—North drainage basin boundary, subwatershed boundaries, the modeled
storm sewer network, and the 1-percent-annual-chance flood inundation areas identified in the modeling
analyses.
Figure 5.3 illustrates that several modeled storm sewer junctions (i.e., manholes or catchbasins) within the
Nine Mile Creek—North drainage basin are predicted to surcharge during both the 10- and 1-percent-
annual-chance events. This means that in any year there is a greater than 10 percent probability that the
system will be overburdened and unable to convey all of the stormwater through the storm sewer system
at these locations. These manholes and catch basins are more likely to become inundated during the
smaller, more frequent storm events of various durations.
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To evaluate the level of protection of the stormwater system within the Nine Mile Creek—North drainage
area, the 1-percent-annual-chance flood elevations for the ponding basins and depressed areas were
compared to the elevations of structures surrounding each basin. The areas predicted to potentially flood
and threaten structures during the 1-percent-annual-chance storm event are shown on Figure 5.3.
Discussion and recommended improvement considerations for these areas are included in Section 5.3.
5.2.2 Water Quality Modeling Results
The effectiveness of the stormwater system in removing stormwater pollutants such as phosphorus was
analyzed using the P8 water quality model. The P8 model simulates the hydrology and phosphorus loads
introduced from each pond’s watershed and the transport of phosphorus throughout the stormwater
system. A more detailed description of the stormwater system analysis is provided in Section 4.1.3.
Figure 5.4 depicts the results of the water quality modeling for the Nine Mile Creek—North drainage
basin. The figure shows the fraction of total phosphorus removal for each water body as well as the
cumulative total phosphorus removal in the watershed.
5.3 Implementation Considerations
The 2017 XP-SWMM hydrologic and hydraulic modeling analyses and the 2003 P8 water quality analysis
helped identify locations throughout the watershed where improvements to the City’s stormwater
management system may be warranted. The following sections discuss potential improvement options
identified as part of the modeling analyses. As opportunities to address identified flooding issues and
improve water quality arise (e.g., street reconstruction projects or public facilities improvements), the City
will use a comprehensive approach to stormwater management. This approach will include consideration
of infiltration or volume retention practices to address flooding and/or improve water quality, reduction of
impervious surfaces, increased storm sewer capacity where necessary and feasible to alleviate flooding,
construction and/or expansion of water quality basins, and implementation of other stormwater BMPs to
reduce pollutant loading to downstream waterbodies.
5.3.1 Flood Protection Projects
The 2017 Atlas 14 hydrologic and hydraulic modeling analyses identified several locations within the Nine
Mile Creek—North drainage basin where the 1-percent-annual-chance flood elevations may impact
structures or public safety. Several of these problem areas, and potential corrective measures, were
evaluated as part of this plan development and are discussed in more detail in this section. There may be
additional flood-prone areas within the drainage basin that warrant further analysis— see Figure 5.3 for
the 1-percent-annual-chance flood inundation areas.
The 2003 hydrologic and hydraulic modeling analyses also identified several locations within the Nine
Mile Creek—North drainage basin where the 1-percent-annual-chance level of protection was not
provided by the stormwater system, based on TP-40 precipitation frequency estimates. The discussions
related to those areas have been carried over to Appendix C of this plan, along with a short summary of
what has been done in those areas since 2003.
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5.3.1.1 Maloney Avenue and Tyler Court (ML_35 and ML_19)
On either side of Tyler Court, south of Maloney Avenue, there are local depressions with inlets and outlets
draining to Mirror Lake. Stormwater runoff from a drainage area of approximately 29 acres discharges into
this area. These depressions are drained by a 24-inch pipe. However, downstream, at the intersection of
Arthur Street and Waterman Avenue, the pipe flowing east toward Mirror Lake is reduced to 18 inches.
Modeling results indicate that the 1-percent-annual-chance flood elevation in this area (940.0 feet west of
Tyler Court and 938.1 feet east of Tyler Court) exceeds the low house elevations at 505, 509, and 513 Tyler
Court (surveyed at 932.9, 933.1, and 934.07 feet, respectively in 2003) and the apparent low elevations at
500 and 508 Tyler Court. Additionally, the 1-percent-annual-chance flood elevation is more than 2 feet
higher than the low elevation on Tyler Court, with the duration of the impacts more than 60 hours, based
on a 24-hour duration storm event. This area was also identified as an area of concern in the 2003 and
2009 CWRMPs.
The flooding problem in this area is primarily related to the capacity of the storm sewer system between
this area and Mirror Lake. To alleviate a portion of the flooding problem, it is recommended that the
18-inch pipe flowing east from the Arthur Street and Waterman Avenue intersection be upgraded to a
larger pipe. There are currently no potentially impacted principle structures around Mirror Lake during the
1-percent-annual-chance 24-hour storm event, which is more critical than the 10-day snowmelt event.
Therefore, the additional conveyance of water to Mirror Lake does not appear to create problems
downstream. Further analysis is needed to balance reducing impacts in this area without creating impacts
around Mirror Lake.
5.3.1.2 Between Leslee Lane and Kaymar Drive (MD_22)
A backyard depression area exists between the properties on the south side of Leslee Lane and north side
of Kaymar Drive. The depression area collects stormwater from a drainage area of approximately 10 acres
with 6.4 acres directly contributing. A 15-inch pipe extends southward into the backyard depression area
from Leslee Lane, collecting stormwater from the low area, and continues west toward Jeffrey Lane. This
system eventually connects with the Blake Road South system at the intersection of Blake Road South and
Kaymar Drive. During the 1-percent-annual-chance 24-hour storm event, flow is restricted in the 15-inch
pipe and water pools in the backyard depression area to a peak flood level of 916.8 feet. Eventually, the
water overflows to the west between 6104 Jeffrey Lane and 6017 Leslee Lane. Based on the LiDAR data
and the approximate building footprints, it appears that seven principle structures may be impacted
(6016–6028 Kaymar Drive and 6001–6009 Leslee Lane). This area was also identified as an area of concern
in the 2003 and 2009 CWRMPs.
To reduce the backyard flooding, it is recommended that the size of both the 15-inch pipe draining the
backyard depression and the downstream 18-inch pipe be increased to increase discharge capacity. It is
also recommended that the surface overflow from this area to Jeffrey Lane be lowered if existing or future
road grades allow for it. At a minimum, the existing surface overflow should be maintained.
City of Edina 2018 Comprehensive Water Resources Management Plan
5-6
5.3.1.3 Parkwood Road and Schaefer Road (MD_28, MD_29, and MD_35)
A small, 0.5-acre stormwater detention pond is located just northwest of the intersection of Schaefer Road
and Parkwood Road. The outlet from the pond is a 12-inch pipe that drains south to Parkwood Road, east
toward Blake Road, and then south toward the wet pond along Knoll Drive. During the peak of the 1-
percent-annual-chance 24-hour storm event, inundation occurs along Parkwood Road due to
downstream pipe capacity restrictions and overflows to the south between 6213 and 6217 Parkwood
Road (approximately 936.5 feet based on LiDAR data). As the water level rises along Parkwood Road, flow
from the detention pond west of Schaefer is reduced due to tailwater effects. The detention pond then
fills up, overtopping Schaefer Road to the east, at an elevation of approximately 937.6 feet, to another
stormwater detention basin in MD_29. Inundation from the 1-percent-annual-chance event appears to
impact four principle structures within this area: 6216 and 6217 Parkwood Road, 6316 Westwood Court,
and 5316 Schaefer Road. This area was also identified as an area of concern in the 2003 and 2009
CWRMPs.
Due to the presence of downstream flood-prone structures, increasing downstream pipe capacity is not
recommended. Review of LiDAR data and approximate building footprints indicates there may be impacts
to the principle structures identified above. A survey of the low entry elevations of these structures is
recommended. It is also recommended that the surface overflows across Schaefer Road, between 6213
and 6217 Parkwood Road, and between 6212 and 6216 Parkwood Road be maintained or slightly lowered
during any future road improvement projects in this area. Underground storage may be an option to
reduce flood risk in this area. In particular, Parkwood Road has a significant depression area. If Parkwood
Road is reconstructed it could be regraded to have positive drainage to the east with storage under
Parkwood Road. Soil maps indicate that the soils here are “B” soils, with moderate infiltration capacity. The
effectiveness of underground storage could be optimized by allowing infiltration from the bottom of the
underground system.
5.3.1.4 Schaefer Road and View Lane (MD_38)
Adjacent to Bredesen Park on the west side, where View Lane, Schaefer Road, and Killarney Lane South
meet, there is a backyard depression with a private lift station. Surface overflow to the east, between 6008
and 6012 Schaefer Road, occurs at an elevation of approximately 867.5 feet (based on LiDAR data), which
is higher than the 1-percent-annual-chance flood level. This particular area has a history of flooding and
of private efforts to reduce flooding. Modeling results indicate that during the 1-percent-annual-chance
24-hour storm event, runoff from the MD_38 watershed would drain to the backyard depression, resulting
in a peak flood level of 865.0 feet, and may impact 6021 View Lane and 6016–6032 Schaefer Road.
It is recommended that a gravity outlet be installed from the backyard depression area to Bredesen Park
to lower the flood elevation in the depression area. This proposed gravity outlet would supplement or
replace the private lift station. Due to the larger area of Bredesen Park, and the relatively small volume of
water that would be conveyed from the backyard depression, the impact to flood elevations in Bredesen
Park would likely be negligible. Further analysis is warranted to verify.
City of Edina 2018 Comprehensive Water Resources Management Plan
5-7
5.3.1.5 Nine Mile Village Townhomes (MD_49)
The Nine Mile Village Townhomes are located east of Bredesen Park, across Villa Lane. Flood water
overtops Villa Lane (surface overflow at approximately 857.3 feet) during the 1-percent-annual-chance
24-hour storm event, with water flowing down Sandpiper Court towards several townhomes. These
townhomes may be impacted at the 1-percent-annual-chance flood level (857.7 feet). Water can then
overflow from MD_49, traveling southeast to a pond around Colonial Church (CO_2). Modeling results
indicate that the peak flood level of the waterbodies within Bredesen Park during this event is 858.2 feet.
Construction of a berm on the west side of Villa Lane is recommended to prevent surface overflows from
waterbodies within Bredesen Park to the Nine Mile Village Townhomes. Potential surface overflows from
Bredesen Park should be directed towards the low area between Sandpiper Court and Red Fox Lane,
which eventually flows to the ponds around Colonial Church. If the opportunity arises, additional surface
grading within the Nine Mile Village Townhomes complex, particularly in the southeast corner where
MD_49 overflows into CO_2, should be considered to promote drainage of the local contributing
watershed through a surface overflow.
5.3.1.6 Hawkes Lake and Upstream Surrounding Area (HL_1, HL_11c, HL_11w, HL_49, and HL_12)
Hawkes Lake is in the Nine Mile Creek watershed, south of Vernon Avenue South and west of Tracy
Avenue. The lake has many inlet points from all directions and one pumped outlet. The pumped outlet
drains through a gravity system under Merold Drive to the south, crosses Amy Drive, and eventually
discharges to a wetland area (subwatershed MD_3) within Bredesen Park. The 1-percent-annual-chance
flood level of Hawkes Lake (HL_1) and the immediately surrounding area is determined by the 10-day
snowmelt event (894.1 feet). The 1-percent-annual-chance flood level of HL_12 to the east of Hawkes Lake
is determined by the 24-hour precipitation event (903.1 feet). Based on modeling results, LiDAR data, and
approximate building footprints, there are nine principle structures around Hawkes Lake (5621, 5625,
5629, and 5701 Wycliffe Road, 5708 and 5705 Warden Avenue, 5717 Hawkes Drive, and 5712 and 5716
Tracy Avenue), six principle structures immediately north of Vernon Avenue South (5533, 5537, and 5604
Dundee Road, 5532, 5536, and 5541 Mirror Lakes Drive), and one principle structure near Warden Avenue
(5537 Warden Avenue) that are potentially impacted at the 1-percent-annual-chance flood level.
It is recommended that capacity of the pumped outlet and the downstream gravity storm sewer system
be increased to reduce flood risk around Hawkes Lake; however, this may require that the capacity be
increased all the way downstream to Bredesen Park, where the downstream impacts are expected to be
minimal. The capacity of the storm sewer systems draining to Hawkes Lake, particularly from north of
Vernon Avenue South and from Warden Avenue, should also be increased to alleviate flooding in the
areas upstream of Hawkes Lake. Providing additional flood storage within the city-owned parcel in
subwatershed MD_15 could be considered to mitigate the additional flows to Bredesen Park, if needed,
assuming flood elevations in MD_15 aren’t increased and the existing surface overflow elevation is
maintained or lowered. A cursory analysis of this option was completed by the city in 2015 in preparation
for the city’s 2016 street reconstruction project (Countryside H).
City of Edina 2018 Comprehensive Water Resources Management Plan
5-8
5.3.2 Construction/Upgrade of Water Quality Basins
The 2003 P8 modeling analysis indicated that under average conditions the annual removal of total
phosphorus from several ponds in the Nine Mile Creek—North drainage area was predicted to be below
the desired 60 percent removal rate. For those ponds with total phosphorus removal below 60 percent,
the permanent pool storage volume was analyzed to determine whether additional capacity is necessary.
The ponds with deficiencies in total phosphorus removal and permanent pool volume are listed below
(and are also summarized in Appendix D), with recommended pond upgrades.
Construction of new or expansion of existing water quality basins is one way to increase pollutant removal
prior to stormwater reaching downstream waterbodies. Many additional techniques are available to
reduce pollutant loading, including impervious surface reduction or disconnection, implementation of
infiltration or volume-retention BMPs, installation of underground stormwater treatment structures and
sump manholes, and other good housekeeping practices such as street sweeping. As opportunities arise,
the City will consider all of these options to reduce the volume and improve the quality of stormwater
runoff.
5.3.2.1 MD_15
Pond MD_15 is located just north of the 5904, 5908, and 5912 Sun Road properties, south of Amy Drive.
The pond receives runoff from an area of approximately 25 acres. Pond MD_15 outlets to the storm sewer
system along Sun Road via an 18-inch RCP pipe. The pond is a Type 5 wetland and was assumed to have
an average depth of 4 feet. Based on this depth assumption and the 2-foot topographic information for
the pond, the current permanent pool storage is 1.1 acre-feet. This is less than the MPCA-recommended
storage volume for detention basins. It is recommended that an additional 0.3 acre-feet of dead storage
volume be provided to meet the MPCA design criteria for detention basins.
5.3.2.2 NMN_27
Pond NMN_27 is located northeast of the TH 62 and TH 169 intersection. The pond is south of Langford
Court, directly east of Lincoln Road, and northwest of Waterford Court. The pond receives runoff from an
area of approximately 37 acres, including drainage from TH 169 and Lincoln Drive. The pond is a Type 5
wetland and was assumed to have an average depth of 4 feet. Based on this depth assumption and the
2-foot topographic information for the pond, the current permanent pool storage volume is 1.7 acre-feet.
This is less than the MPCA-recommended storage volume for Pond NMN_27. It is recommended that an
additional 1.4 acre-feet of dead storage volume be provided to meet the MPCA design criteria for
detention basins.
5.3.2.3 NMN_24
Pond NMN_24 is located between Waterford Court and Habitat Court, downstream and to the southeast
of Pond NMN_27. The pond receives runoff from a 5-acre watershed. The pond is a Type 4 wetland and
was assumed to have an average depth of 2 feet. Based on this depth assumption and the 2-foot
topographic information for the pond, the current permanent pool storage volume is 1.7 acre-feet. This is
greater than the MPCA-recommended storage volume for detention basins; however, because water
City of Edina 2018 Comprehensive Water Resources Management Plan
5-9
quality modeling results indicate that the total phosphorus removal in Pond NMN_24 is below desired
levels, it is recommended that the depth of the pond be increased to 4 feet to improve removal efficiency.
5.3.2.4 NMN_49
Pond NMN_49 is a sedimentation basin located directly west of the 5521 Malibu Drive property. The
sedimentation basin receives runoff from a watershed of approximately 6 acres, in addition to incoming
flows from the upstream sedimentation basin (NMN_48). Pond NMN_49 discharges to the North Fork of
Nine Mile Creek. Based on storm sewer information from the City, a 2-foot average depth was assumed.
Considering this depth assumption and the 2-foot topographic data for the pond area, the current
permanent pool storage volume is 0.14 acre-feet. Compared to the calculated MPCA-recommended
storage volume for Pond NMN_49, this is not an adequate amount of permanent pool storage for this
basin. It is recommended that 0.2 acre-feet of dead storage volume be added to meet the MPCA design
criteria for detention basins.
5.3.2.5 MD_3
Pond MD_3 is located in Bredesen Park, directly east of the parking area off Olinger Boulevard. Pond
MD_3 receives runoff from a 48-acre watershed, in addition to discharges from ponds MD_15 and MD_13.
The pond is a Type 5 wetland and was assumed to have an average depth of 4 feet. Based on this depth
assumption and 2-foot topographic information for the pond area, the current permanent pool storage
volume is 4.7 acre-feet—greater than the MPCA-recommended storage volume for detention ponds.
However, because water quality modeling results indicate that the total phosphorus removal in Pond
MD_3 is below desired levels, it is recommended that the pond be excavated to remove accumulated
sediment its depth increased to improve removal efficiency.
Table 5.2
Watershed Modeling Results for Subwatersheds in the Nine Mile Creek - North Drainage Area
1 The 1%-Annual-Chance (100-Year) 10-day snowmelt event is defined as 7.2 inches of runoff
Watershed ID
Total Area
(ac)
% Impervious
Area
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
EdCrk1 17.1 11 133 8.5 3.2 10.2 66 4.3
EdCrk2 8.4 20 76 3.8 1.6 5.0 38 1.8
EdCrk3 71.6 47 415 37.5 13.4 43.0 194 19.5
EdCrk5 45.9 51 336 25.0 8.7 27.5 164 13.3
EdCrk6 5.5 21 49 2.5 1.0 3.3 24 1.2
EdCrk7 23.1 34 209 11.8 4.4 13.9 107 6.1
EdCrk7c 5.0 8 51 2.4 1.0 3.0 27 1.2
HI_1 38.7 46 256 20.9 7.3 23.2 122 11.1
HI_10 42.4 25 264 19.0 8.0 25.4 114 9.1
HI_11 3.5 25 34 1.6 0.7 2.1 17 0.8
HI_12 15.8 25 114 7.0 3.0 9.4 51 3.4
HI_13 26.1 27 195 12.4 4.9 15.6 92 6.1
HI_14 4.6 25 43 2.1 0.9 2.7 21 1.0
HI_15 10.4 25 80 4.7 2.0 6.2 37 2.2
HI_16 9.5 25 51 4.2 1.8 5.7 21 2.0
HI_17 6.2 16 39 3.0 1.2 3.7 18 1.5
HI_18 21.3 11 107 10.6 4.0 12.8 48 5.3
HI_19 4.5 12 27 2.1 0.9 2.7 12 1.0
HI_2 4.2 23 42 2.0 0.8 2.5 22 1.0
HI_20 18.4 12 95 10.0 3.5 11.1 45 5.2
HI_21 2.7 14 25 1.5 0.5 1.6 13 0.8
HI_22 2.2 30 23 1.2 0.4 1.3 12 0.7
HI_3 8.4 25 65 3.9 1.6 5.0 31 1.9
HI_4 11.0 25 80 4.9 2.1 6.6 36 2.3
HI_5 8.0 33 71 4.4 1.5 4.8 37 2.4
HI_6 9.5 25 77 5.3 1.8 5.7 39 2.8
HI_7 7.0 25 52 3.1 1.3 4.2 23 1.5
HI_7a 5.2 25 48 2.3 1.0 3.1 24 1.1
HI_8 8.3 25 69 3.7 1.6 5.0 32 1.8
HI_9 8.2 25 43 3.6 1.5 4.9 18 1.7
HL_1 25.5 45 213 13.0 4.8 15.3 104 6.7
HL_10 2.7 24 23 1.3 0.5 1.6 11 0.6
HL_11c 2.3 25 25 1.0 0.4 1.4 13 0.5
HL_11e 5.0 25 49 2.2 0.9 3.0 25 1.1
HL_11w 22.5 19 211 10.0 4.3 13.5 106 4.7
HL_12 12.5 25 93 5.8 2.4 7.5 43 2.8
HL_13 2.2 39 23 1.0 0.4 1.3 12 0.5
HL_14 4.4 25 44 2.0 0.8 2.7 23 1.0
HL_15 0.8 25 8 0.3 0.1 0.4 5 0.2
HL_16 4.8 26 43 2.2 0.9 2.9 21 1.0
HL_17 1.3 27 15 0.6 0.3 0.8 8 0.3
HL_18 3.1 25 26 1.4 0.6 1.8 12 0.7
HL_19 1.1 25 11 0.5 0.2 0.7 6 0.2
HL_2 5.6 25 49 2.5 1.1 3.4 24 1.2
HL_20 4.5 25 33 2.0 0.8 2.7 15 0.9
HL_21 11.7 16 73 4.7 2.2 7.0 28 2.0
HL_23 4.4 29 40 2.0 0.8 2.7 20 1.0
HL_25 2.2 25 19 0.9 0.4 1.3 8 0.4
HL_26 8.6 25 66 3.9 1.6 5.2 30 1.8
HL_27 1.2 25 11 0.6 0.2 0.7 6 0.3
HL_28 5.6 49 51 3.0 1.1 3.4 26 1.6
HL_29 15.5 30 130 7.9 2.9 9.3 65 4.1
HL_29a 0.2 20 2 0.1 0.0 0.1 1 0.1
HL_29b 6.4 20 57 3.3 1.2 3.8 29 1.7
HL_3 6.8 25 37 3.0 1.3 4.1 15 1.4
HL_30 2.6 25 24 1.2 0.5 1.6 12 0.6
HL_31 6.9 26 54 3.1 1.3 4.1 25 1.5
HL_32 1.0 17 11 0.4 0.2 0.6 6 0.2
HL_33 4.3 33 43 2.0 0.8 2.6 22 1.0
HL_34 1.7 25 16 0.7 0.3 1.0 8 0.4
24-Hour Precipitation Event
10%-Annual-Chance (10-Year)Watershed Information 1%-Annual-Chance (100-Year)
24-Hour Precipitation Event 10-day Snowmelt Event1
1%-Annual-Chance (100-Year)
Table 5.2
Watershed Modeling Results for Subwatersheds in the Nine Mile Creek - North Drainage Area
1 The 1%-Annual-Chance (100-Year) 10-day snowmelt event is defined as 7.2 inches of runoff
Watershed ID
Total Area
(ac)
% Impervious
Area
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
24-Hour Precipitation Event
10%-Annual-Chance (10-Year)Watershed Information 1%-Annual-Chance (100-Year)
24-Hour Precipitation Event 10-day Snowmelt Event1
1%-Annual-Chance (100-Year)
HL_35 4.5 25 44 2.1 0.8 2.7 23 1.0
HL_35a 0.6 31 7 0.3 0.1 0.3 4 0.1
HL_36 12.8 30 88 5.8 2.4 7.7 39 2.8
HL_37 4.6 22 42 2.1 0.9 2.8 21 1.0
HL_38 0.7 42 9 0.4 0.1 0.4 5 0.2
HL_39 16.0 30 128 7.4 3.0 9.6 60 3.6
HL_4 5.6 25 44 2.5 1.1 3.3 21 1.2
HL_40 17.5 25 143 8.1 3.3 10.5 69 4.0
HL_41 1.7 25 18 0.8 0.3 1.0 10 0.4
HL_42 11.2 25 100 5.0 2.1 6.7 49 2.4
HL_43 5.0 50 46 2.6 0.9 3.0 24 1.4
HL_44 2.4 52 25 1.3 0.5 1.4 13 0.7
HL_45 6.8 25 57 3.0 1.3 4.1 27 1.5
HL_46 3.0 25 29 1.4 0.6 1.8 15 0.7
HL_46a 0.8 25 9 0.4 0.2 0.5 5 0.2
HL_47 16.2 40 140 7.9 3.1 9.7 69 4.0
HL_48 4.6 55 47 2.4 0.9 2.8 24 1.2
HL_49 4.4 25 39 2.0 0.8 2.7 19 1.0
HL_5 1.8 25 18 0.8 0.3 1.1 9 0.4
HL_50 11.2 38 83 5.5 2.1 6.7 39 2.7
HL_6 3.3 25 29 1.5 0.6 2.0 15 0.8
HL_7 3.8 25 31 1.7 0.7 2.3 15 0.8
HL_8 14.0 28 89 6.3 2.6 8.4 38 3.0
HL_9 6.6 35 57 3.2 1.3 4.0 28 1.6
MD_1 33.3 67 165 19.1 6.1 20.0 79 10.5
MD_10 1.0 20 10 0.4 0.2 0.6 5 0.2
MD_11 6.9 2 36 2.9 1.3 4.2 15 1.3
MD_12 14.0 25 108 6.3 2.7 8.4 50 3.0
MD_13 12.4 38 100 6.0 2.3 7.4 48 3.0
MD_14 8.6 24 68 3.9 1.6 5.1 32 1.9
MD_15 6.7 33 48 3.7 1.3 4.0 24 2.0
MD_16 5.2 25 45 2.6 1.0 3.1 23 1.3
MD_17 6.6 25 47 3.1 1.3 4.0 22 1.5
MD_18 2.3 24 18 1.0 0.4 1.4 9 0.5
MD_19 5.2 30 45 2.4 1.0 3.1 21 1.2
MD_2 12.5 40 109 6.8 2.4 7.5 56 3.6
MD_20 12.9 25 86 5.8 2.4 7.7 38 2.8
MD_21 9.1 43 73 4.4 1.7 5.5 35 2.2
MD_22 6.4 25 58 3.0 1.2 3.8 29 1.5
MD_23 2.2 25 19 1.0 0.4 1.3 10 0.5
MD_24 3.0 25 25 1.4 0.6 1.8 12 0.7
MD_25 7.9 52 71 4.0 1.5 4.7 35 2.1
MD_26 2.8 23 24 1.2 0.5 1.7 12 0.6
MD_27 18.0 25 140 8.0 3.4 10.8 64 3.8
MD_28 5.8 25 33 2.6 1.1 3.5 14 1.2
MD_29 11.9 22 76 5.2 2.3 7.2 32 2.4
MD_3 6.6 18 44 3.4 1.3 4.0 21 1.7
MD_30 1.9 25 19 0.8 0.4 1.1 10 0.4
MD_31 5.6 25 44 2.5 1.1 3.3 20 1.2
MD_32 5.1 25 24 2.2 1.0 3.1 10 1.0
MD_33 2.7 25 29 1.2 0.5 1.6 15 0.6
MD_34 3.0 25 15 1.3 0.6 1.8 6 0.6
MD_35 4.8 21 44 2.1 0.9 2.9 22 1.0
MD_36 7.0 19 64 3.2 1.3 4.2 32 1.5
MD_37 2.8 19 29 1.2 0.5 1.7 15 0.6
MD_38 6.1 25 50 2.8 1.2 3.7 24 1.3
MD_39 6.3 19 51 2.7 1.2 3.8 24 1.3
MD_4 13.7 50 115 7.6 2.6 8.2 58 4.1
MD_40 11.2 27 71 5.2 2.1 6.7 32 2.6
MD_41 8.4 25 75 4.0 1.6 5.0 38 2.0
Table 5.2
Watershed Modeling Results for Subwatersheds in the Nine Mile Creek - North Drainage Area
1 The 1%-Annual-Chance (100-Year) 10-day snowmelt event is defined as 7.2 inches of runoff
Watershed ID
Total Area
(ac)
% Impervious
Area
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
24-Hour Precipitation Event
10%-Annual-Chance (10-Year)Watershed Information 1%-Annual-Chance (100-Year)
24-Hour Precipitation Event 10-day Snowmelt Event1
1%-Annual-Chance (100-Year)
MD_42 10.4 25 78 4.7 2.0 6.3 36 2.2
MD_43 8.8 25 58 3.9 1.7 5.3 25 1.8
MD_44 1.3 25 12 0.6 0.3 0.8 6 0.3
MD_45 7.8 25 50 3.4 1.5 4.7 21 1.6
MD_46 6.9 24 51 3.1 1.3 4.1 23 1.5
MD_47 5.2 36 47 2.5 1.0 3.1 23 1.2
MD_48 6.4 23 61 2.8 1.2 3.8 30 1.4
MD_48a 16.7 22 122 7.4 3.2 10.0 55 3.5
MD_49 5.2 23 42 2.5 1.0 3.1 21 1.3
MD_5 1.4 18 14 0.8 0.3 0.9 8 0.4
MD_50 53.4 63 250 30.3 9.7 32.0 118 16.5
MD_6 6.1 24 45 3.0 1.2 3.7 21 1.5
MD_7 7.9 31 56 3.6 1.5 4.8 25 1.8
MD_8 10.5 31 54 4.8 2.0 6.3 23 2.3
MD_9 4.6 25 36 2.2 0.9 2.7 18 1.1
ML_1 53.9 53 476 27.5 10.2 32.3 233 14.3
ML_10 6.7 25 55 2.9 1.3 4.0 25 1.3
ML_11 1.8 14 18 0.8 0.3 1.1 9 0.4
ML_12 2.5 22 20 1.1 0.5 1.5 9 0.5
ML_12a 1.6 25 17 0.7 0.3 1.0 9 0.3
ML_13 9.2 17 56 4.0 1.7 5.5 24 1.8
ML_14 0.9 25 10 0.4 0.2 0.5 5 0.2
ML_15 11.1 40 89 5.3 2.1 6.7 42 2.7
ML_16 8.1 55 66 4.2 1.5 4.8 32 2.2
ML_17 7.0 20 55 3.0 1.3 4.2 25 1.4
ML_18 14.2 21 122 6.2 2.7 8.5 59 3.0
ML_19 5.3 22 48 2.4 1.0 3.2 24 1.2
ML_2 13.2 36 115 6.3 2.5 7.9 56 3.1
ML_20 5.2 27 40 2.4 1.0 3.1 18 1.1
ML_21 15.9 18 95 6.9 3.0 9.5 40 3.2
ML_22 3.1 25 27 1.4 0.6 1.9 13 0.7
ML_23 0.9 25 10 0.4 0.2 0.6 5 0.2
ML_24 2.1 20 21 0.9 0.4 1.3 10 0.4
ML_25 4.3 25 40 1.9 0.8 2.6 20 0.9
ML_26 7.1 33 59 3.3 1.3 4.2 28 1.6
ML_27 2.9 18 24 1.3 0.6 1.8 11 0.6
ML_28 13.0 36 104 6.1 2.5 7.8 48 3.0
ML_29 3.7 24 35 1.7 0.7 2.2 17 0.8
ML_29a 2.3 25 24 1.0 0.4 1.4 12 0.5
ML_3 1.2 17 9 0.5 0.2 0.7 4 0.2
ML_30 10.7 23 82 4.7 2.0 6.4 37 2.2
ML_31 14.7 11 101 6.1 2.8 8.8 44 2.8
ML_32 3.8 63 42 2.1 0.7 2.3 22 1.1
ML_33 0.7 20 7 0.3 0.1 0.4 4 0.1
ML_34n 4.3 27 40 2.1 0.8 2.6 20 1.1
ML_34s 4.8 33 52 2.3 0.9 2.9 27 1.1
ML_35 7.1 15 48 3.0 1.3 4.2 21 1.4
ML_38 8.0 10 48 3.8 1.5 4.8 22 1.9
ML_4 1.7 24 17 0.8 0.3 1.0 8 0.4
ML_40 13.7 13 85 6.8 2.6 8.2 40 3.4
ML_5 3.8 18 32 1.7 0.7 2.3 15 0.8
ML_6 3.5 26 29 1.6 0.7 2.1 14 0.8
ML_7 2.2 23 22 1.0 0.4 1.3 11 0.5
ML_8 8.7 23 71 3.8 1.6 5.2 33 1.8
ML_9 2.9 23 22 1.3 0.6 1.7 10 0.6
NMN_10 2.5 25 22 1.1 0.5 1.5 11 0.5
NMN_11 1.0 23 11 0.5 0.2 0.6 6 0.2
NMN_13 5.3 23 36 2.3 1.0 3.2 16 1.1
NMN_14 4.3 25 31 1.9 0.8 2.6 14 0.9
NMN_15 4.8 25 40 2.2 0.9 2.9 19 1.0
Table 5.2
Watershed Modeling Results for Subwatersheds in the Nine Mile Creek - North Drainage Area
1 The 1%-Annual-Chance (100-Year) 10-day snowmelt event is defined as 7.2 inches of runoff
Watershed ID
Total Area
(ac)
% Impervious
Area
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
24-Hour Precipitation Event
10%-Annual-Chance (10-Year)Watershed Information 1%-Annual-Chance (100-Year)
24-Hour Precipitation Event 10-day Snowmelt Event1
1%-Annual-Chance (100-Year)
NMN_16 3.0 25 30 1.4 0.6 1.8 15 0.7
NMN_17 2.9 24 28 1.3 0.6 1.8 14 0.6
NMN_18 4.7 24 36 2.1 0.9 2.8 17 1.0
NMN_19 18.1 25 143 8.1 3.4 10.9 66 3.9
NMN_20 10.6 12 78 4.5 2.0 6.3 35 2.0
NMN_21 0.6 25 6 0.3 0.1 0.3 3 0.1
NMN_22 0.6 25 7 0.3 0.1 0.4 3 0.2
NMN_23 3.9 37 35 1.8 0.7 2.3 17 0.9
NMN_24 4.1 49 42 2.2 0.8 2.5 22 1.2
NMN_25 0.7 25 7 0.3 0.1 0.4 3 0.1
NMN_26 5.9 25 52 2.7 1.1 3.5 26 1.3
NMN_27 2.6 47 28 1.3 0.5 1.5 15 0.7
NMN_28 6.7 40 49 3.2 1.3 4.0 22 1.6
NMN_29 0.6 27 6 0.3 0.1 0.3 3 0.1
NMN_3 1.3 15 15 0.7 0.3 0.8 8 0.3
NMN_31 4.0 40 31 2.0 0.8 2.4 15 1.0
NMN_32 20.8 67 155 11.4 3.9 12.5 75 6.1
NMN_33 7.4 42 55 3.7 1.4 4.5 26 1.9
NMN_34 2.9 41 32 1.4 0.5 1.7 17 0.7
NMN_35 5.4 25 50 2.6 1.0 3.2 26 1.3
NMN_36 9.0 25 76 4.1 1.7 5.4 36 1.9
NMN_37 13.3 25 108 6.0 2.5 8.0 50 2.8
NMN_38 36.2 24 180 15.9 6.8 21.7 74 7.4
NMN_39 8.1 23 68 3.6 1.5 4.9 32 1.7
NMN_40 3.9 78 38 2.2 0.7 2.3 20 1.2
NMN_41 9.3 67 73 5.1 1.8 5.6 36 2.8
NMN_42 11.0 71 64 6.0 2.1 6.6 30 3.2
NMN_43 12.8 25 107 5.8 2.4 7.7 51 2.8
NMN_44 6.1 25 39 2.7 1.1 3.6 17 1.3
NMN_45 2.9 24 25 1.3 0.5 1.7 12 0.7
NMN_46 2.5 22 23 1.2 0.5 1.5 12 0.6
NMN_47 3.7 25 30 1.7 0.7 2.2 15 0.9
NMN_48 0.4 1 4 0.2 0.1 0.3 2 0.1
NMN_49 0.9 18 8 0.5 0.2 0.6 4 0.2
NMN_50 17.8 33 142 8.3 3.4 10.7 66 4.1
NMN_51 0.8 25 8 0.4 0.2 0.5 4 0.2
NMN_52 0.3 43 4 0.2 0.1 0.2 2 0.1
NMN_53 0.6 63 7 0.3 0.1 0.4 4 0.2
NMN_54 2.4 64 28 1.3 0.5 1.5 15 0.7
NMN_55 4.7 36 43 2.2 0.9 2.8 21 1.1
NMN_56 8.0 19 62 3.5 1.5 4.8 29 1.6
NMN_57 3.0 25 28 1.5 0.6 1.8 14 0.7
NMN_58 4.9 25 36 2.2 0.9 2.9 16 1.0
NMN_59 3.5 65 39 1.9 0.7 2.1 21 1.0
NMN_60 34.1 15 212 16.4 6.5 20.5 98 8.1
NMN_61 8.3 25 71 3.7 1.6 5.0 34 1.8
NMN_62a 0.8 15 6 0.3 0.1 0.4 3 0.1
NMN_62b 9.0 16 74 3.9 1.7 5.4 35 1.8
NMN_62c 3.9 18 38 1.8 0.7 2.4 19 0.9
NMN_62d 1.6 15 16 0.7 0.3 0.9 8 0.4
NMN_62e 4.6 46 48 2.4 0.9 2.7 26 1.2
NMN_62f 0.5 17 4 0.2 0.1 0.3 2 0.1
NMN_63a 2.9 19 29 1.3 0.6 1.8 15 0.6
NMN_63b 4.0 17 38 1.7 0.8 2.4 19 0.8
NMN_63c 2.7 27 27 1.2 0.5 1.6 14 0.6
NMN_64 15.4 39 139 7.4 2.9 9.2 68 3.7
NMN_65 4.6 23 43 2.1 0.9 2.8 22 1.0
NMN_66 7.9 23 67 3.6 1.5 4.8 32 1.7
NMN_67 10.5 25 90 4.7 2.0 6.3 43 2.3
NMN_68 2.3 18 19 1.0 0.4 1.4 10 0.5
Table 5.2
Watershed Modeling Results for Subwatersheds in the Nine Mile Creek - North Drainage Area
1 The 1%-Annual-Chance (100-Year) 10-day snowmelt event is defined as 7.2 inches of runoff
Watershed ID
Total Area
(ac)
% Impervious
Area
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
24-Hour Precipitation Event
10%-Annual-Chance (10-Year)Watershed Information 1%-Annual-Chance (100-Year)
24-Hour Precipitation Event 10-day Snowmelt Event1
1%-Annual-Chance (100-Year)
NMN_7 11.6 25 94 5.2 2.2 6.9 44 2.5
NMN_70 4.0 25 37 1.8 0.8 2.4 18 0.9
NMN_71 6.1 24 54 2.7 1.2 3.6 26 1.3
NMN_72 7.0 25 60 3.1 1.3 4.2 29 1.5
NMN_73 10.0 36 68 4.7 1.9 6.0 31 2.3
NMN_74 3.4 80 36 1.9 0.6 2.0 19 1.1
NMN_75 14.7 32 88 6.7 2.8 8.8 38 3.2
NMN_76 10.5 38 84 5.0 2.0 6.3 39 2.5
NMN_77 7.6 37 60 3.6 1.4 4.6 28 1.8
NMN_78 6.4 25 37 2.9 1.2 3.8 16 1.4
NMN_8 6.7 25 48 3.0 1.3 4.0 21 1.4
NMN_80 8.2 15 61 3.5 1.6 4.9 27 1.6
NMN_81 1.9 33 20 1.0 0.4 1.1 11 0.5
NMN_82 8.9 25 65 4.0 1.7 5.3 29 1.9
NMN_83 3.0 25 25 1.4 0.6 1.8 12 0.7
NMN_84 7.1 25 46 3.2 1.3 4.2 20 1.5
NMN_85 7.5 19 43 3.4 1.4 4.5 19 1.7
NMN_9 9.6 25 53 4.9 1.8 5.8 24 2.5
NMN_90 3.0 37 30 1.5 0.6 1.8 16 0.7
Table 5.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - North
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1098 916.0 914.1
1100 915.9 914.0
1113.1 965.9 965.7
1114.1 964.1 964.1
1115.1 957.0 957.0
1119 931.1 929.6
1121.1 916.4 916.0
1122.1 914.8 914.6
1124.1 922.5 922.2
1127 925.1 925.1
1130.1 917.5 915.9
1131 914.9 914.5
1141 939.2 939.3
1144 916.0 915.8
1154 street 894.1 ¹ 893.0
1168 894.9 894.7
124 917.2 914.6
126 916.1 911.2
128 913.1 909.8
129 908.0 904.7
134 910.9 910.2
137 907.3 906.8
138 907.5 906.8
1386 917.2 914.0
1387 917.2 914.0
139 907.9 907.0
140 908.1 906.9
141 street 908.2 906.8
143 904.6 903.6
145 899.5 899.2
1454 925.8 925.8
1455 921.8 921.7
1467 978.9 977.2
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
Table 5.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - North
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
1468 976.7 976.4
1469 975.1 975.1
1475 951.7 951.1
1477 952.5 951.6
1478 953.9 950.9
1480 949.4 949.2
1481 947.6 947.4
1482 940.8 940.4
1484 936.7 936.5
150 908.4 906.3
152 908.1 906.4
153 907.6 906.3
157 898.5 898.4
1607 899.3 899.3
1622 911.5 909.7
1625 923.1 920.0
1626 923.3 922.0
1627 928.8 928.7
1628 936.8 936.8
1629 939.2 938.6
1630 940.5 939.5
1631 941.6 940.4
1632 942.4 941.0
1633 942.5 941.0
1634 942.5 941.0
1636 943.1 941.5
172 894.6 ¹ 889.6
174 905.1 902.8
1743 920.0 918.8
1745 depression 860.4 860.3
175 896.7 896.4
1750 866.5 865.3
1752 866.5 865.5
Table 5.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - North
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
1762 879.5 878.5
1774 878.9 874.4
178 922.7 922.4
1785 914.5 913.8
1794 930.2 930.2
1795 941.6 941.1
1797 941.6 941.1
1798 940.8 938.5
1810 888.5 884.3
1815 891.8 890.2
1817 914.5 911.2
1818 914.3 913.3
183 907.2 906.0
185 905.7 905.1
186 901.2 900.7
187 894.6 ¹ 889.6
188 ditch/byd 909.1 905.5
189 909.2 905.5
190 909.6 908.9
193 904.5 904.5
194 903.2 903.2
195 894.6 894.6
1950 912.9 912.9
197 870.8 870.5
198 865.8 865.5
202 864.8 864.0
203 864.8 864.5
204 862.4 861.5
209 879.2 878.2
210 879.2 878.6
211 879.2 878.9
212 879.2 878.8
214 877.8 877.5
Table 5.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - North
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
215 874.2 873.9
2158 863.5 863.4
2162 918.6 918.3
2174 902.0 901.7
224_NMN 860.9 860.7
226_NMN 861.0 860.6
2274 907.5 904.9
228 863.6 863.2
229 859.4 858.8
2290 916.2 914.1
2292 919.2 918.8
230 858.8 858.7
2394 903.9 903.7
2395 908.9 908.8
2411 925.3 925.0
2412 925.4 925.4
2417 939.3 936.5
242 863.1 863.0
245 938.8 937.9
246.1 937.3 936.7
247.1 937.4 934.9
250 921.4 921.0
2504 885.5 884.6
2505 890.1 890.1
2506 903.7 903.7
2507 920.4 920.4
2508 894.9 894.8
2509 907.5 906.6
2512 921.2 921.2
2515 937.4 935.2
2517 894.9 893.2
252.1 918.6 918.0
2520 938.2 935.4
Table 5.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - North
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
2521 948.0 947.9
2522 948.1 947.9
2527 919.3 919.1
2528 918.5 918.4
2531 902.0 899.4
2532 911.6 906.1
2534 ditch 865.8 864.5
2538 927.1 928.5
2539 910.7 910.4
2540 929.7 929.6
2541 922.2 922.2
2549 933.0 930.1
255 915.4 914.2
2550 936.0 930.1
2551 936.2 929.2
2552 971.1 968.2
2553 973.8 973.6
258 909.3 908.8
260 899.3 899.1
261 897.6 897.3
262 890.9 890.6
264_NMN 866.2 865.9
267 890.5 890.2
268_NMN 885.6 885.6
269_NMN 878.1 876.0
2699 907.7 907.3
270 878.1 876.0
2701 hwy ditch 906.3 905.6
2702 896.4 896.3
2706 902.3 901.1
2709 902.3 901.2
2710 902.3 901.2
2712 902.3 901.2
Table 5.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - North
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
2718 916.1 915.5
2719 911.5 909.7
2726 899.8 899.8
275 862.0 861.9
278.1 942.3 942.3
279.1 941.6 941.6
280.1 941.0 941.0
281 938.7 938.7
2822 894.6 891.9
2824 896.8 895.1
2847 879.5 879.2
2848 879.3 878.9
2849 879.3 878.3
285 935.9 935.9
2850 879.2 877.6
2851 878.8 877.2
2853 893.7 892.9
2854 895.9 894.9
2855 897.8 896.9
2856 906.0 903.2
2857 908.0 904.3
286 935.8 935.8
287 931.6 931.6
289 918.8 917.4
2908 868.4 868.1
2915 894.6 ¹ 891.4
2916 894.6 ¹ 889.6
292 912.0 911.6
293 910.2 910.2
294 910.0 909.9
295 909.7 909.5
2956 858.2 855.8
296 909.5 909.0
Table 5.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - North
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
2961 858.2 855.4
297 909.4 908.9
298 938.0 938.0
584 938.3 937.5
585.1 937.3 936.7
587.1 934.0 933.4
591 918.9 918.4
592 918.9 918.4
596 914.6 911.8
597 914.2 911.7
598 913.4 911.5
599 907.5 907.3
600 892.8 892.6
601 877.1 876.7
603 866.5 865.4
609.1 872.8 872.3
611.1 870.6 870.2
627 863.6 860.9
629 878.0 877.2
631 892.2 892.1
639 884.9 884.2
641 876.4 875.6
651.1 874.9 873.6
652 874.7 873.9
654 874.9 874.1
655 876.3 874.0
656 878.6 874.1
658 884.5 884.4
663.1 892.7 892.6
667 890.1 890.1
674 908.4 908.2
675.1 912.5 912.2
676.1 915.1 913.8
Table 5.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - North
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
CBMH_432 902.4 901.2
CBMH_433 901.5 900.1
EdCrk1 creek 878.7 874.3
EdCrk2 873.2 871.7
EdCrk2a 875.4 873.0
EdCrk2b 874.3 872.6
EdCrk2c 873.7 872.1
EdCrk3 creek 868.3 866.4
EdCrk3a 873.0 871.5
EdCrk5 pond 858.5 866.5 8.0 864.7 6.2
EdCrk6 863.2 859.1
EdCrk6a 866.4 862.0
EdCrk6b 863.5 859.8
EdCrk6b_1 865.4 860.9
EdCrk6c 863.4 859.2
EdCrk6d 863.4 859.1
EdCrk7 creek 858.2 855.4
EdCrk7a 859.9 856.9
EdCrk7b 859.4 856.9
EdCrk7c 858.8 856.3
EdCrk7d 858.4 856.0
EdCrk7d_1 858.4 856.0
EdCrk7e 858.3 855.7
EdCrk7e_1 858.3 855.6
EdCrk7f 858.3 855.6
EdCrk7g 858.3 855.6
EdCrk7h 858.2 855.4
HI_1 pond 888.4 894.1 ¹ 5.7 891.5 3.1
HI_10 street/lot 894.1 ¹ 893.0
HI_11 925.6 925.2
HI_12 903.1 902.9
HI_13 wetland 885.3** 889.1 ¹ 3.8 886.5 1.2
HI_14 street 901.1 897.3
Table 5.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - North
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
HI_15 cul-de-sac 902.9 902.6
HI_16 906.4 906.1
HI_17 pond 901.0 903.0 2.0 902.5 1.5
HI_18 pond 899.6 902.3 2.7 901.2 1.6
HI_19 depression 914.5 912.5
HI_2 894.1 891.6
HI_20 pond 899.6 903.8 4.2 901.5 1.9
HI_21 depression 903.8 901.5
HI_22 pond 901.0 903.4 2.4 902.1 1.1
HI_3 pond 899.6 902.1 2.5 901.8 2.2
HI_4 street/park 894.1 ¹ 893.0
HI_5 pond 888.3 894.3 6.0 891.7 3.4
HI_6 ditch 902.7 901.8
HI_7 911.8 911.6
HI_7a 911.3 911.0
HI_8 902.2 901.9
HI_9 908.2 908.0
HL_1 pond 885.5 894.6 ¹ 9.1 889.6 4.1
HL_10 street 908.2 905.8
HL_11c street 894.9 893.4
HL_11e street 894.9 892.1
HL_11w street 895.2 894.5
HL_12 street 908.6 906.8
HL_13 wetland 904.0** 907.7 3.7 906.2 2.2
HL_14 byd 909.6 908.9
HL_15 907.8 905.7
HL_16 street 908.1 906.3
HL_17 900.6 898.7
HL_18 byd 903.4 901.9
HL_19 street 914.3 913.4
HL_1A 894.6 ¹ 889.6
HL_2 street 902.2 901.5
HL_20 902.7 902.6
Table 5.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - North
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
HL_21 byd 898.0 895.9
HL_23 street 911.8 911.1
HL_25 byd 898.0 895.8
HL_26 street 899.1 897.9
HL_27 cul-de-sac 926.3 925.6
HL_28 pond 898.2 907.6 9.4 904.4 6.2
HL_29 depression 910.0 908.1
HL_29a 907.8 907.4
HL_29b ball field 911.2 910.8
HL_3 byd 908.0 907.7
HL_30 street/yd 918.8 918.7
HL_31 street 930.6 929.0
HL_32 street 907.7 904.4
HL_33 913.0 912.8
HL_34 914.3 914.1
HL_35 wetland 906.9 917.2 10.3 912.6 5.7
HL_35a 939.1 938.6
HL_36 byd 924.4 919.9
HL_37 911.8 908.6
HL_38 914.6 910.5
HL_39 pond 902.2** 908.7 ¹ 6.5 904.7 2.5
HL_4 street 897.4 897.2
HL_4$I 897.1 897.1
HL_40 wetland 899.7 907.0 7.3 901.1 1.4
HL_41 ditch 920.0 918.7
HL_42 925.3 925.0
HL_43 street 913.7 912.0
HL_44 wetland 904.6 908.2 3.6 905.2 0.6
HL_45 908.8 905.9
HL_46 894.6 ¹ 889.6
HL_46a 909.8 905.5
HL_47 byd 917.2 916.6
HL_48 929.5 928.1
Table 5.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - North
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
HL_49 byd 894.9 892.3
HL_5 917.5 912.2
HL_50 pond 927.8** 933.2 ¹ 5.4 930.5 2.7
HL_6 911.4 911.2
HL_7 937.6 937.5
HL_8 pond 901.9 908.1 6.2 906.1 4.2
HL_9 pond 905.4 908.8 3.4 907.0 1.6
MD_1 pond 851.5 858.2 6.7 855.4 3.9
MD_10 street 861.6 861.4
MD_11 pond 853.0 858.2 5.2 855.4 2.4
MD_12 863.2 862.9
MD_13 pond 876.0 879.2 3.2 876.7 0.7
MD_14 street 861.5 861.1
MD_15 pond 859.8 864.4 4.6 863.7 3.9
MD_16 871.8 871.7
MD_17 862.0 861.7
MD_18 878.1 876.0
MD_19 889.2 888.3
MD_2 pond 854.0 858.2 4.2 854.5 0.5
MD_20 905.6 905.4
MD_21 pond 889.8 891.5 1.7 890.7 0.9
MD_22 byd 916.8 915.7
MD_23 byd 919.2 917.9
MD_24 byd 915.4 913.7
MD_25 pond 910.0 916.2 6.2 912.0 2.0
MD_26 931.2 931.1
MD_27 street/yd 916.2 914.5
MD_28 pond 936.0 939.3 3.3 938.4 2.4
MD_29 pond 935.0 938.5 3.5 937.7 2.7
MD_3 pond 854.0 858.5 4.5 856.4 2.4
MD_30 byd 940.7 940.2
MD_31 street 918.9 918.4
MD_32 byd 921.0 920.7
Table 5.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - North
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
MD_33 928.0 927.8
MD_34 932.0 931.4
MD_35 street 937.3 936.7
MD_36 street 861.3 858.6
MD_37 street 863.3 863.2
MD_38 byd 865.0 863.9
MD_39 pond 935.5 939.1 3.6 938.0 2.5
MD_4 creek 860.8 860.6
MD_40 street/field 879.4 879.0
MD_41 street 865.3 865.0
MD_42 888.9 888.6
MD_43 932.6 932.3
MD_44 918.9 917.3
MD_45 922.6 922.2
MD_46 ditch 873.0 869.3
MD_47 885.4 879.9
MD_48 939.3 938.6
MD_48a street/yd 939.2 938.3
MD_49 857.7 857.3
MD_5 867.1 864.1
MD_50 wetland 850.0 858.2 8.2 855.4 5.4
MD_6 street 863.8 863.6
MD_7 pond 859.0 862.5 3.5 860.1 1.1
MD_8 865.7 865.1
MD_9 862.2 860.8
ML_1 pond 908.5 911.5 3.0 909.7 1.2
ML_10 929.7 929.4
ML_11 street 931.1 929.2
ML_12 street 941.3 937.4
ML_12a 935.9 934.4
ML_13 park 931.1 930.1
ML_14 942.9 941.0
ML_15 pond 939.5 940.9 1.4 937.4 -2.1
Table 5.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - North
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
ML_16 pond 936.8 940.8 4.0 938.5 1.7
ML_17 street 942.0 941.1
ML_18 914.5 913.8
ML_19 byd 938.2 935.3
ML_2 pond 908.4 914.5 6.1 911.6 3.2
ML_20 937.4 937.2
ML_21 street/byd 941.4 939.6
ML_22 941.4 940.7
ML_23 934.3 932.8
ML_24 914.3 911.8
ML_25 914.3 912.1
ML_26 pond 939.1** 941.3 2.2 939.4 0.3
ML_27 pond 948.1 953.2 5.1 952.1 4.0
ML_28 pond 935.1** 939.0 ¹ 3.9 937.2 2.1
ML_29 byd 936.4 936.1
ML_29a byd 936.4 936.0
ML_3 pond 941.2 943.8 2.6 942.5 1.3
ML_30 941.3 940.9
ML_31 depression 916.2 914.6
ML_32 pond 908.4 914.5 6.1 911.6 3.2
ML_33 945.6 942.8
ML_34n byd 943.2 943.1
ML_34s byd 944.1 943.7
ML_35 street 940.0 939.5
ML_38 pond 916.1 919.1 3.0 916.7 0.6
ML_4 street 945.9 940.6
ML_40 pond 916.1 918.7 2.6 916.6 0.5
ML_5 923.1 919.8
ML_6 pond 939.7 942.7 3.0 941.2 1.5
ML_7 byd 932.3 931.2
ML_8 911.5 909.7
ML_9 depression 969.2 968.3
N16 916.8 916.3
Table 5.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - North
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
N20 866.8 866.2
N25 863.4 863.1
N265 872.7 871.3
N32 949.2 949.1
N5 920.3 920.2
N6 928.4 928.1
N76 863.5 863.5
N92 913.5 909.4
NMN_10 866.7 866.5
NMN_11 street 862.5 861.1
NMN_13 873.3 864.6
NMN_14 868.9 868.5
NMN_15 street 866.5 865.5
NMN_16 869.1 868.6
NMN_17 860.2 859.7
NMN_18 street 862.3 860.2
NMN_19 876.4 876.0
NMN_20 ditch 884.9 884.3
NMN_21 890.3 888.5
NMN_22 882.7 882.2
NMN_23 byd 874.8 874.1
NMN_24 pond 885.0 888.9 3.9 888.5 3.5
NMN_25 891.3 891.0
NMN_26 867.0 866.8
NMN_27 pond 891.0 896.4 5.4 896.1 5.1
NMN_28 875.2 873.3
NMN_29 891.9 891.5
NMN_3 street 866.4 862.0
NMN_31 street 879.3 878.0
NMN_32 hwy ditch 907.6 907.3
NMN_33 882.6 882.4
NMN_34 905.4 905.3
NMN_35 869.6 868.7
Table 5.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - North
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
NMN_36 871.9 871.5
NMN_37 street 872.3 871.8
NMN_38 877.5 877.0
NMN_39 882.9 882.7
NMN_40 895.9 890.5
NMN_41 street 878.0 877.3
NMN_42 878.8 878.1
NMN_43 883.3 883.0
NMN_44 880.6 880.2
NMN_45 884.0 883.9
NMN_46 880.8 880.6
NMN_47 879.7 879.5
NMN_48 creek 878.9 874.4
NMN_49 creek 879.1 874.3
NMN_50 pond 895.4** 898.6 ¹ 3.2 896.9 1.5
NMN_51 cul-de-sac 871.8 869.0
NMN_52 874.7 872.0
NMN_53 920.1 917.6
NMN_54 hwy ditch 901.2 900.5
NMN_55 pond 909.0 909.1 0.1 907.3 -1.7
NMN_56 street/ditch 866.5 864.7
NMN_57 863.7 861.0
NMN_58 street 891.3 891.2
NMN_59 hwy ditch 908.1 907.2
NMN_60 creek 878.5 874.2
NMN_61 street 883.5 882.0
NMN_62a cul-de-sac 910.4 905.0
NMN_62b 924.0 915.6
NMN_62c pond 884.2 891.1 6.9 889.8 5.6
NMN_62d depression 891.0 890.2
NMN_62e pond 885.8 890.8 5.0 889.3 3.5
NMN_62f 919.2 919.0
NMN_63a 930.5 930.3
Table 5.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - North
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
NMN_63b pond 920.4 921.4 1.0 921.1 0.7
NMN_63c byd 910.9 910.2
NMN_64 street 880.7 880.4
NMN_65 892.4 890.1
NMN_66 939.6 939.3
NMN_67 893.3 892.9
NMN_68 byd 949.8 949.7
NMN_7 892.8 892.5
NMN_70 street 952.3 950.9
NMN_71 961.7 961.5
NMN_72 954.3 951.2
NMN_73 basin 878.6 877.0
NMN_74 basin 905.7 ¹ 903.7
NMN_75 pond 912.7 914.7 2.0 914.0 1.3
NMN_76 pond 905.3 908.1 2.8 905.6 0.3
NMN_77 pond 916.4 918.4 2.0 917.9 1.5
NMN_78 970.7 966.9
NMN_8 868.1 867.8
NMN_80 940.2 936.4
NMN_81 byd 977.5 977.4
NMN_82 975.6 975.5
NMN_83 980.4 978.5
NMN_84 pond 917.6 919.3 1.7 919.1 1.5
NMN_85 946.1 945.8
NMN_9 byd 866.6 866.2
NMN_90 street 874.8 873.9
Node271 866.5 864.7
£¤212
£¤169
100
4567158
Vernon Ave Blake Rd Tracy Ave Interlachen Blvd Olinger Rd Gleason Rd Schaefer Rd MudLake
MirrorLake
HighlandsLake
HawkesLake
HopkinsHopkins
MinnetonkaMinnetonka
Eden PrairieEden Prairie
Saint Louis ParkSaint Louis Park
North Bran c h Nine MileCreek
EdCrk3
ML_1 HI_1
MD_50
HI_10
EdCrk5
MD_1
HL_1
HI_13
NMN_38
NMN_60
HI_18
EdCrk7
HI_20
HL_11w
HL_40
HI_12
HL_8
MD_27
HL_47
NMN_32
HL_39
HL_29
ML_21
EdCrk1
ML_2
MD_4
HI_4
ML_31
NMN_19
NMN_50
ML_18
MD_2
MD_48a
ML_40
MD_12
HL_36
HI_6
ML_28
HL_12MD_20
NMN_64
HL_21
MD_8
MD_13
HI_15
NMN_75
HL_50
HI_3
HL_42
HI_8
MD_29
HI_9
ML_15 HI_5
HI_16
ML_30
MD_40
NMN_37
NMN_7
ML_8
NMN_43
MD_42
HI_7
ML_13
MD_7
HL_26
NMN_9
NMN_42
MD_21
HL_3
NMN_20
MD_43NMN_76
HL_9
MD_14
ML_16
ML_38
MD_41
NMN_73
EdCrk2
MD_25
MD_3
MD_45
NMN_41
NMN_36
HL_31
ML_26
ML_35
HL_45
HL_2
HI_17
MD_6
HL_4
MD_11
ML_10
MD_46
NMN_80
MD_15
MD_17
NMN_62b
NMN_66
MD_22
MD_48
NMN_77
MD_39
NMN_85
NMN_33
HL_28
HL_29b
NMN_72
MD_28
NMN_28
ML_19 ML_20
HI_14
MD_9
HL_43
HI_19
EdCrk6
MD_19
HL_16
MD_16
MD_49
MD_32NMN_44
HL_48
HL_37HL_7
HL_20
MD_35
HL_14
HL_23
ML_5
HL_11e HL_33
NMN_35
ML_34s
NMN_13
ML_6
NMN_58
ML_32
NMN_15
NMN_55
ML_34n
ML_9
HL_18
ML_22
ML_27
NMN_47
HL_10
HL_44
NMN_67
NMN_82 ML_17
MD_36
NMN_61
NMN_39
NMN_56
NMN_8 MD_38
HI_7a
HI_2NMN_84
MD_31
NMN_78
MD_47
NMN_71
NMN_26
HL_35
HL_49
ML_25
HL_6
EdCrk7c
HI_11
NMN_18
ML_29
NMN_65
NMN_14
NMN_24
NMN_62e
NMN_70
NMN_31
HL_46
NMN_23
NMN_40
HI_21
MD_24
MD_34
NMN_62c
NMN_59
NMN_63b
NMN_74
HL_30
MD_37
MD_26
ML_7
MD_33
ML_12
HI_22
NMN_16
NMN_90
NMN_57
NMN_83
NMN_17
NMN_45
NMN_34
HL_25
HL_5
MD_18
HL_13
ML_24
HL_11c
NMN_63a
MD_23
NMN_27
ML_4
ML_29a
NMN_46
NMN_10
NMN_54
NMN_63c
ML_11
NMN_68
MD_30
HL_41
HL_34
MD_5
NMN_81
ML_12a
ML_3
HL_17
MD_44
HL_27
NMN_3
HL_19
NMN_62d
HL_32
MD_10
ML_23
ML_14
NMN_11
HL_15
HL_38
NMN_49 HL_46a
ML_33
NMN_51
NMN_62a
NMN_25
NMN_53
NMN_22
HL_35a
NMN_29NMN_21
NMN_62f
NMN_48
NMN_52
HL_29a
Barr Footer: ArcGIS 10.4.1, 2017-09-21 08:58 File: I:\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_5_1_NMC_North_Drainage_Basins.mxd User: EMANINE MILE CREEK - NORTH DRAINAGE BASINComprehensiveWater ResourcesManagement PlanCity of Edina, Minnesota
FIGURE 5.1
0 1,200
Feet
!;N
Nine Mile Creek - NorthDrainage Basin
Subwatershed
Streets and Highways
Creek/Stream
City of Edina Boundary
Lake/Wetland
Imagery Source: MnGeo; 2016
£¤212
£¤169
100
4567158
Vernon Ave Blake Rd Tracy Ave Interlachen Blvd Olinger Rd Gleason Rd Schaefer Rd MudLake
MirrorLake
HighlandsLake
HawkesLakeNine Mile North
Mud Lake
Mirror Lake
Hawkes Lake
Highlands Lake
HopkinsHopkins
MinnetonkaMinnetonka
Eden PrairieEden Prairie
Saint Louis ParkSaint Louis Park
North Bran c h Nine MileCreek
Barr Footer: ArcGIS 10.4.1, 2017-09-21 09:02 File: I:\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_5_2_NMC_North_Major_Watersheds.mxd User: EMANINE MILE CREEK - NORTH MAJOR WATERSHEDSComprehensiveWater ResourcesManagement PlanCity of Edina, Minnesota
FIGURE 5.2
0 1,200
Feet
!;N
Nine Mile Creek - NorthDrainage Basin
Major Watershed
Hawkes Lake
Highlands Lake
Mirror Lake
Mud Lake
Nine Mile North
Subwatershed
Streets and Highways
Creek/Stream
City of Edina Boundary
Lake/Wetland
Imagery Source: MnGeo; 2016
City of Edina 2018 Comprehensive Water Resources Management Plan
5-33
Figure 5.3 Nine Mile Creek—North Hydraulic Model Results
This is a large drawing (34x44).
Due to the paper and size and file size, this figure is included as a stand-alone PDF.
Nine M il e Creek
HopkinsHopkins
MinnetonkaMinnetonka
Eden PrairieEden Prairie
St. Louis ParkSt. Louis Park
ML_1
MD_50
MD_1
HI_1
HL_1
MD_4
ML_16
MD_25
HI_13
MD_1
MD_50
ML_28
HL_44
ML_15
NMN_50
MD_2
ML_2
HI_18
HL_28
MD_21
NMN_75
ML_32
NMN_76
HI_5
MD_13
HI_20
ML_40
MD_2
MD_4
ML_26
MD_3MD_2
NMN_77
NMN_62
MD_11
HL_9
HL_50
HL_39
NMN_24
MD_7
HL_40
ML_38
MD_15
NMN_55
HL_24
ML_19
MD_28
HL_13
NMN_27
MD_2
NMN_84
MD_29
HI_17
NMN_20
NMN_63
HL_25
NMN_73
MD_39
ML_6
HI_21 HI_22
NMN_74
ML_3
ML_27
NMN_49
NMN_48
Barr Footer: ArcGIS 10.4.1, 2017-09-21 07:57 File: \\barr.com\gis\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_5_4_NMC_North_Water_Quality.mxd User: rcs2NINE MILE CREEK NORTHWATER QUALITY MODELING RESULTSComprehensive Water ResourceManagement PlanCity of Edina, Minnesota
FIGURE 5.4
1,200 0 1,200Feet
!;N
400 0 400Meters
Percent TP Removal in Water Body*This number represents the percent of the total annual massof phosphorus entering the water body that is removed.
Cumulative TP Removal in Watershed*This number represents the percent of the total annual massof phosphorus entering the watershed and upstream watershedsthat is removed in the pond and all upstream ponds.
*Data based on results of 2003 P8 modeling.
0 - 25% (Poor/No Treatment)
25 - 40% (Moderate Removal)
40 - 60% (Good Removal)
60 - 100% (Excellent Removal)
0 - 25% (Poor/No Treatment)
25 - 40% (Moderate Removal)
40 - 60% (Good Removal)
60 - 100% (Excellent Removal)
Area Draining Directly to the NorthFork of Nine Mile Creek
Flow Direction
Imagery Source: USDA 2016 NAIP via MnGeo
City of Edina 2018 Comprehensive Water Resources Management Plan
6-1
6.0 Nine Mile Creek—Central
6.1 General Description of Drainage Area
Figure 6.1 depicts the Nine Mile Creek—Central drainage basin. The Nine Mile Creek—Central drainage
basin is located in the central portion of Edina and encompasses 1,236 acres that ultimately drain to the
stretch of the North Fork of Nine Mile Creek between TH 62 and West 70th Street.
6.1.1 Drainage Patterns
The stormwater system within this drainage area comprises storm sewers, ponding basins, drainage
ditches, and overland flow paths. The Nine Mile Creek—Central drainage basin has been divided into
three major watersheds based on the drainage patterns. These major watersheds are depicted in
Figure 6.2. Each major watershed has been further delineated into many subwatersheds. The naming
convention for each subwatershed is based on the major watershed where it is located Table 6.1 lists each
major watershed and the associated subwatershed naming convention.
Table 6.1 Major Watersheds within the Nine Mile Creek—Central Drainage Basin
Major Watershed
Subwatershed Naming
Convention Number of Subwatersheds Drainage Area (acres)
Colonial Ponds CO_## 13 115
Indian Pond IP_## 4 24
Nine Mile Central NMC_## 129 1097
6.1.1.1 Colonial Ponds
The Colonial Ponds watershed is located in central Edina and encompasses approximately 115 acres. The
watershed is bordered by TH 62 to the south, Villa Lane on the west, extends northward to Benton
Avenue, and slightly eastward past Westridge Boulevard. Six stormwater detention ponds are located
within the watershed. The most downstream detention basin is located just south of the Colonial Church
(subwatershed CO_1) and outlets to the North Fork of Nine Mile Creek via a 48-inch culvert under TH 62.
The land use within the watershed is primarily residential, with the exception of the Colonial Church
property and adjacent Countryside Park.
6.1.1.2 Indian Pond
The Indian Pond watershed is located in central Edina, southwest of Creek Valley Elementary School. The
24-acre watershed is characterized by a single storm sewer system that drains to Indian Pond. Indian Pond
is a land-locked basin. In the unlikely event of overflow from this pond, which would occur at an
approximate elevation of 897 feet, the overflow would discharge to the intersection of Indian Hills Pass
and Cherokee Trail. It would then be picked up by the Gleason Road storm sewer system and eventually
City of Edina 2018 Comprehensive Water Resources Management Plan
6-2
discharge to the North Fork of Nine Mile Creek, just northwest of the Edina High School complex. The
land use within the Indian Pond watershed is low-density residential.
6.1.1.3 Nine Mile Central
The Nine Mile Central watershed is also located in central Edina and spans approximately 1,097 acres.
Stormwater within the watershed drains to the North Fork of Nine Mile Creek between TH 62 and West
70th Street via a network of ponding basins and storm sewer. The watershed extends north to the
intersection of Hansen Road and West 56th Street and includes the area north of TH 62 that drains to the
storm sewer system along the Soo Line railroad. The Soo Line storm sewer system flows beneath TH 62
and eventually discharges to the creek near the intersection of Valley Lane and Limerick Lane. The
watershed is bordered by West 70th Street on the south, Gleason Road on the west, and TH 100 on the
east. There are five stormwater detention basins within the Nine Mile Central watershed. The watershed
has been delineated into 129 subwatersheds, with land use characterized by residential areas, the Edina
High School complex, freeway, several parks, the Soo Line Railroad, several ponding basins, and the
floodplain of the North Fork of Nine Mile Creek.
6.2 Stormwater System Results
6.2.1 Hydrologic/Hydraulic Modeling Results
The 10- and 1-percent-annual-chance flood analyses were performed for the Nine Mile Creek—Central
drainage basin. The 10-percent-annual-chance analysis was based on a ½-hour storm with 1.65 inches of
rain. The 1-percent-annual-chance analysis was based on a 24-hour storm event with 7.47 inches of rain
and on a 10-day snowmelt event with 7.2 inches of runoff; the higher resulting flood level of the two
events was chosen for the 1-percent-annual-chance analysis Table 6.2 presents the watershed
information and the results for the 10- and 1-percent-annual-chance hydrologic analyses for the Nine
Mile Creek—Central basin. A more detailed description of the stormwater system analysis is provided in
Section 4.1.3.
The results of the 10- and 1-percent-annual-chance hydraulic analyses for the Nine Mile Creek—Central
drainage basin are summarized in Table 6.3.
Figure 6.3 illustrates the results of the 10- and 1-percent-annual-chance hydraulic analyses. The figure
depicts the Nine Mile Creek—Central drainage basin boundary, subwatershed boundaries, the modeled
storm sewer network, surcharge conditions for the XP-SWMM nodes (typically manholes), and the flood-
prone areas identified in the modeling analyses.
To evaluate the level of protection of the stormwater system within the Nine Mile Creek—Central
drainage area, the 1-percent-annual-chance frequency flood elevations for the ponding basins and
depressed areas were compared to the low elevations of structures surrounding each basin. The areas
predicted to potentially flood and threaten structures during the 1-percent-annual-chance storm event
are shown on Figure 6.3. Discussion and recommended improvement considerations for these areas are
included in Section 6.3.
City of Edina 2018 Comprehensive Water Resources Management Plan
6-3
6.2.2 Water Quality Modeling Results
The effectiveness of the stormwater system in removing stormwater pollutants such as phosphorus was
analyzed using the P8 water quality model. The P8 model simulates the hydrology and phosphorus loads
introduced from each pond’s watershed and the transport of phosphorus throughout the stormwater
system. A more detailed description of the stormwater system analysis is provided in Section 4.1.3.
Figure 6.4 depicts the results of the water quality modeling for the Nine Mile Creek—Central drainage
basin. The figure shows the fraction of total phosphorus removal for each water body as well as the
cumulative total phosphorus removal in the watershed.
6.3 Implementation Considerations
The 2017 XP-SWMM hydrologic and hydraulic modeling analyses and 2003 P8 water quality analysis
helped identify locations throughout the watershed where improvements to the City’s stormwater
management system may be warranted. The following sections discuss potential improvement options
identified as part of the modeling analyses. As opportunities to address identified flooding issues and
improve water quality arise (e.g., street reconstruction projects or public facilities improvements), the City
will use a comprehensive approach to stormwater management. This approach will include consideration
of infiltration or volume retention practices to address flooding and/or improve water quality, reduction of
impervious surfaces, increased storm sewer capacity where necessary to alleviate flooding, construction
and/or expansion of water quality basins, and implementation of other stormwater BMPs to reduce
pollutant loading to downstream waterbodies.
6.3.1 Flood Protection Projects
The 2017 hydrologic and hydraulic modeling analyses identified several locations within the Nine Mile
Creek—Central drainage basin where the 1-percent-annual-chance level of protection is not provided by
the current stormwater system. The problem areas identified in 2017 are discussed below.
As part of the 2017 modeling analyses, potential corrective measures were identified for problem areas.
These preliminary corrective measures are also discussed below. As the City evaluates flooding issues and
potential system modifications in these areas, other potential modifications, including (but not limited to)
volume-retention practices, increases in conveyance capacity, and/or stormwater infiltration (where soils
are conducive) will be given consideration.
The 2003 hydrologic and hydraulic modeling analyses also identified several locations within the Nine
Mile Creek—Central drainage basin where the 1-percent-annual-chance level of protection was not
provided by the stormwater system, based on TP-40 precipitation frequency estimates. The discussions
related to those areas have been carried over to Appendix C of this plan, along with a short summary of
what has been done in those areas since 2003.
City of Edina 2018 Comprehensive Water Resources Management Plan
6-4
6.3.1.1 Antrim Road and Chapel Drive (NMC_41)
A depression exists in the backyards of the homes between Antrim Road and Erin Terrace, south of Chapel
Drive. The backyard depression has a 12-inch CMP outlet that connects to the existing storm sewer
system on Chapel Drive. Modeling results indicate that the 1-percent-annual-chance flood elevation
(943.3 feet) in this area is determined by the 24-hour precipitation event and may exceed up to five low
principle structure- elevations, based on LiDAR data and approximate building footprint information. The
problem is caused by the limited capacity of the 12-inch pipe and the capacity of the surface overflow
between homes (approximate elevation of 942.5 feet based on LiDAR).
It is recommended that a survey of low house elevations be conducted at 5901 and 5905 Chapel Drive,
and 6812–6820 Antrim Road to determine potential flood impacts. Flood-proofing measures on the
individual properties could be considered for those that are demonstrated to be impacted. Additionally,
the natural surface overflow north to Chapel Drive between 5901 and 5905 Chapel Drive should be
maintained, and potentially lowered if feasible. Increasing the capacity of the outlet pipe is not
recommended due to the long length of pipe (approximately 5,000 feet) between NMC_41 and the
ultimate discharge, Nine Mile Creek. Increasing the capacity at any point may require increasing the
capacity in all downstream pipes from that point.
6.3.1.2 Ridgeview Drive (NMC_106 and NMC_107)
A depression exists in the backyards of the homes along Ridgeview Road, adjacent to the Soo Line
railroad tracks south of West 66th Street. The backyard depression is not connected to a storm sewer
pipe, but does have a private lift station in NMC_107. Modeling results indicate that the flood elevation
from the 1-percent-annual-chance 24-hour storm event (846.0 in NMC_106 and 844.5 in NMC_107) may
exceed the low house elevations of 10 principle structures, based on LiDAR data and approximate
building footprints. The results of the 24-hour precipitation event and the 10-day snowmelt event are
nearly identical. It is recommended that a survey of low house elevations be conducted at 6700–6716
Ridgeview Road and 6808–6824 Ridgeview Road to determine potential for flood impacts. This area was
also identified as an area of concern in the 2003 and 2009 CWRMPs.
The problem is due to the land-locked nature of these subwatersheds and the limited capacity of the
private lift station. It is recommended that a gravity storm sewer system with a backflow preventer be
installed that conveys stormwater from the backyard depression areas to Nine Mile Creek (on the other
side of the railroad tracks). Finally, a storm sewer pipe could be added and connected to the existing
storm sewer system at the intersection of Tifton Drive and Ridgeview Drive (upstream invert of existing
system is approximately 840.7 feet).
6.3.1.3 West 66th Street and Naomi Drive (NMC_71, NMC_74, and NMC_103)
During intense rainstorms, flooding problems have historically occurred at the low-lying intersection of
West 66th Street and Naomi Drive. The backyard depression area in the rear of the homes on the east and
west sides of Naomi Drive and Normandale Park have also been subject to flooding. Stormwater overflow
from the West 66th Street and Naomi Drive intersection flows into the adjacent Normandale Park storage
City of Edina 2018 Comprehensive Water Resources Management Plan
6-5
area (ball field). The intersection and ball field are eventually drained by a 33-inch trunk storm sewer
system that flows northwest to the low area along Warren Avenue and, eventually, west to the North Fork
of Nine Mile Creek. Modeling results indicate that the 1-percent-annual-chance flood elevation (863.9 feet
in NMC_103 and 863.8 feet in NMC_71 and NMC_74) exceeds the low house elevation of up to nine
principle structures (6600 and 6604 Naomi Drive, 6605–6617 Naomi Drive, 6608 and 6612 Kenney Place,
and 5177 West 66th Street).
The backyard depression area behind the Naomi Drive homes is drained by a 15-inch culvert that
connects to the 15-inch pipe heading north from Circle Drive Pond. During periods of intense rainfall, the
water in this system backs up and flows south into Circle Drive Pond. A flap gate has been installed on the
culvert draining the backyard depression area to prevent backflow from inundating the area. However,
with the flap gate closed, there is no outlet from this area and the backyard storage volume is not
sufficient to prevent flooding of the structures along Naomi Drive.
This flooding problem has been analyzed in the past and recommendations to alleviate the flooding were
made, in which case some were implemented. The recommendations to add additional outlet capacity to
the backyard depression area via a pumped outlet to the Normandale Park storage area or a separate
gravity system flowing west to the North Fork of Nine Mile Creek, have not been implemented but should
be considered further. If the recommendation to install a gravity outlet under the railroad tracks from
NMC_106 and NMC_107 is implemented, additional storm sewer could be installed to connect this area to
NMC_106. If a pumped outlet is installed to drain the backyard area, it will be necessary to add additional
storage capacity in Normandale Park.
6.3.2 Construction/Upgrade of Water Quality Basins
The 2003 P8 modeling analysis indicated that under average conditions the annual removal of total
phosphorus from several ponds in the Nine Mile Creek—Central drainage area was predicted to be below
the desired rate of 60 percent. For those ponds with total phosphorus removal below 60 percent, the
permanent pool storage volume was analyzed to determine whether additional capacity was necessary.
Based on the MPCA-recommended permanent pool storage volume for detention basins, all of the basins
were found to have sufficient dead storage volume. As a result, no specific recommendations for water
quality basin upgrades in the Nine Mile Creek—Central drainage basin are being made at this time.
Construction of new or expansion of existing water quality basins is one way to increase pollutant removal
prior to stormwater reaching downstream waterbodies. Many additional techniques are available to
reduce pollutant loading, including impervious surface reduction or disconnection, implementation of
infiltration or volume-retention BMPs, installation of underground stormwater treatment structures and
sump manholes, and other good housekeeping practices such as street sweeping. As opportunities arise,
the City will consider all of these options to reduce the volume and improve the quality of stormwater
runoff.
Table 6.2
Watershed Modeling Results for Subwatersheds in the Nine Mile Creek - Central Drainage Area
1 The 1%-Annual-Chance (100-Year) 10-day snowmelt event is defined as 7.2 inches of runoff
Watershed ID
Total Area
(ac)
% Impervious
Area
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
CO_1 16.8 46 133 9.1 3.2 10.1 66 4.8
CO_10 4.9 29 43 2.3 0.9 2.9 21 1.1
CO_11 3.0 25 31 1.3 0.6 1.8 16 0.6
CO_12 6.6 23 56 3.4 1.3 4.0 28 1.8
CO_13 23.0 25 129 10.2 4.3 13.8 55 4.9
CO_2 5.9 38 47 3.3 1.1 3.5 24 1.8
CO_3 0.5 50 5 0.2 0.1 0.3 3 0.1
CO_4 8.2 23 45 3.9 1.5 4.9 20 1.9
CO_5 7.5 32 38 4.0 1.4 4.5 18 2.1
CO_6 13.7 25 93 6.6 2.6 8.2 43 3.3
CO_7 5.3 32 54 2.5 1.0 3.2 28 1.2
CO_8 8.5 25 72 3.8 1.6 5.1 34 1.8
CO_9 11.0 25 82 4.9 2.1 6.6 37 2.3
IP_1 5.8 34 52 2.4 1.1 3.4 22 1.1
IP_2 11.7 21 89 4.4 2.2 7.0 33 1.9
IP_3 4.2 25 39 1.7 0.8 2.5 16 0.7
IP_4 1.9 24 17 0.7 0.4 1.1 7 0.3
NMC_10 8.7 28 78 4.1 1.6 5.2 38 2.0
NMC_100 9.4 25 64 4.2 1.8 5.6 28 2.0
NMC_101 30.8 25 199 14.1 5.8 18.5 88 6.8
NMC_102 1.2 25 12 0.6 0.2 0.7 7 0.3
NMC_103 4.1 25 38 2.0 0.8 2.5 19 1.0
NMC_104 24.3 65 270 14.1 4.6 14.6 146 7.8
NMC_105 2.9 47 33 1.6 0.5 1.7 18 0.9
NMC_106 3.3 24 31 1.6 0.6 2.0 16 0.8
NMC_107 1.6 24 16 0.7 0.3 0.9 8 0.4
NMC_108 7.8 25 51 3.4 1.5 4.6 22 1.6
NMC_109 1.5 26 13 0.6 0.3 0.9 5 0.3
NMC_11 7.7 20 70 2.9 1.5 4.6 29 1.3
NMC_110e 6.2 25 64 2.8 1.2 3.7 33 1.3
NMC_110n 8.2 25 74 3.7 1.6 4.9 36 1.8
NMC_110w 3.2 25 34 1.4 0.6 1.9 18 0.7
NMC_111 11.7 25 97 5.3 2.2 7.0 46 2.6
NMC_112 9.3 51 89 4.8 1.8 5.6 45 2.5
NMC_113a 7.1 24 62 3.3 1.4 4.3 31 1.6
NMC_113b 4.9 23 47 2.3 0.9 3.0 24 1.1
NMC_113BP 2.0 4 12 0.9 0.4 1.2 6 0.5
NMC_113c 4.2 24 34 1.9 0.8 2.5 16 0.9
NMC_113d 2.8 25 18 1.2 0.5 1.7 8 0.6
NMC_113e 4.0 24 34 1.8 0.8 2.4 16 0.9
NMC_113f 5.2 23 47 2.3 1.0 3.1 23 1.1
NMC_114 2.8 60 29 1.5 0.5 1.7 15 0.8
NMC_115 16.3 24 125 7.3 3.1 9.8 57 3.5
NMC_116 10.2 25 77 4.6 1.9 6.1 35 2.2
NMC_117 41.8 25 304 18.8 7.9 25.1 137 9.0
NMC_117a 19.4 24 118 8.5 3.7 11.6 50 4.0
NMC_118 11.3 22 79 5.3 2.1 6.8 37 2.6
NMC_119 2.4 23 26 1.1 0.5 1.4 14 0.5
NMC_12 8.7 26 42 3.8 1.6 5.2 18 1.8
NMC_120 8.0 26 58 4.3 1.5 4.8 29 2.3
NMC_121 1.7 25 16 0.8 0.3 1.0 8 0.4
NMC_122 27.3 25 172 12.1 5.2 16.4 74 5.7
NMC_13 3.0 30 31 1.6 0.6 1.8 16 0.8
NMC_14 3.6 25 24 1.7 0.7 2.1 11 0.8
NMC_15 0.7 36 8 0.3 0.1 0.4 4 0.2
NMC_16 8.4 25 48 3.5 1.6 5.0 19 1.6
NMC_17 7.5 24 64 3.3 1.4 4.5 30 1.6
NMC_18 1.7 25 17 0.7 0.3 1.0 8 0.3
NMC_19 5.5 25 49 2.2 1.0 3.3 21 1.0
NMC_20 3.2 36 29 1.5 0.6 1.9 15 0.8
Watershed Information 1%-Annual-Chance (100-Year)1%-Annual-Chance (100-Year)10%-Annual-Chance (10-Year)
24-Hour Precipitation Event 10-day Snowmelt Event1 24-Hour Precipitation Event
Table 6.2
Watershed Modeling Results for Subwatersheds in the Nine Mile Creek - Central Drainage Area
1 The 1%-Annual-Chance (100-Year) 10-day snowmelt event is defined as 7.2 inches of runoff
Watershed ID
Total Area
(ac)
% Impervious
Area
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Watershed Information 1%-Annual-Chance (100-Year)1%-Annual-Chance (100-Year)10%-Annual-Chance (10-Year)
24-Hour Precipitation Event 10-day Snowmelt Event1 24-Hour Precipitation Event
NMC_21 2.3 28 17 0.9 0.4 1.4 6 0.4
NMC_22 4.1 27 38 1.9 0.8 2.5 19 0.9
NMC_23 5.8 25 56 2.6 1.1 3.5 28 1.3
NMC_24 7.3 25 47 3.2 1.4 4.4 20 1.5
NMC_25 1.8 26 18 0.8 0.3 1.1 9 0.4
NMC_26 4.4 29 37 2.0 0.8 2.6 18 1.0
NMC_27 5.5 25 42 2.5 1.1 3.3 19 1.2
NMC_28 8.2 63 46 4.6 1.5 4.9 22 2.5
NMC_29 9.6 24 45 4.1 1.8 5.7 18 1.9
NMC_30 19.3 25 127 8.5 3.7 11.6 55 4.0
NMC_31 2.1 25 21 0.9 0.4 1.2 11 0.4
NMC_32 12.0 29 68 5.4 2.3 7.2 29 2.6
NMC_34 2.1 25 22 0.9 0.4 1.2 11 0.4
NMC_35 5.4 25 46 2.6 1.0 3.2 23 1.3
NMC_36 5.6 25 50 2.5 1.1 3.4 24 1.2
NMC_37 1.8 25 19 0.8 0.3 1.1 10 0.4
NMC_38 2.8 25 23 1.2 0.5 1.7 11 0.6
NMC_39 12.7 25 81 5.6 2.4 7.6 35 2.7
NMC_4 2.0 25 19 0.8 0.4 1.2 9 0.3
NMC_40 2.2 25 24 1.1 0.4 1.3 13 0.6
NMC_41 6.4 25 51 2.9 1.2 3.8 24 1.4
NMC_42 10.1 27 74 4.5 1.9 6.1 33 2.2
NMC_43 2.8 25 27 1.3 0.5 1.7 14 0.6
NMC_44 4.0 43 36 2.0 0.8 2.4 18 1.0
NMC_45 5.6 25 63 2.6 1.1 3.4 34 1.3
NMC_46 24.8 30 171 11.3 4.7 14.9 75 5.5
NMC_47 3.4 30 37 1.6 0.6 2.0 20 0.8
NMC_48 0.8 57 9 0.4 0.2 0.5 5 0.2
NMC_49 8.5 25 68 3.8 1.6 5.1 31 1.8
NMC_5 4.0 29 33 1.8 0.8 2.4 16 0.9
NMC_50 10.6 25 76 4.7 2.0 6.3 34 2.2
NMC_51 9.7 25 73 4.3 1.8 5.8 33 2.1
NMC_52 9.7 25 73 4.4 1.8 5.8 34 2.1
NMC_53 2.2 25 13 1.0 0.4 1.3 6 0.5
NMC_54 10.1 25 78 4.7 1.9 6.1 37 2.3
NMC_55 8.8 25 59 3.9 1.7 5.3 26 1.9
NMC_56 11.2 25 92 5.1 2.1 6.7 44 2.5
NMC_57 5.8 24 37 2.6 1.1 3.5 16 1.2
NMC_58 4.3 25 36 1.9 0.8 2.6 17 0.9
NMC_59 1.1 25 13 0.5 0.2 0.7 7 0.2
NMC_6 3.9 27 32 1.6 0.7 2.3 14 0.7
NMC_60 5.2 21 41 2.9 1.0 3.1 21 1.5
NMC_61 6.4 25 52 3.1 1.2 3.8 26 1.6
NMC_62 13.2 25 90 6.3 2.5 7.9 42 3.1
NMC_63 8.5 25 66 3.8 1.6 5.1 31 1.8
NMC_64 3.6 24 34 1.6 0.7 2.1 17 0.8
NMC_65 8.1 24 64 3.8 1.5 4.8 31 1.9
NMC_66 8.1 25 58 3.6 1.5 4.8 26 1.7
NMC_67 6.5 25 65 3.0 1.2 3.9 33 1.5
NMC_68 3.3 25 29 1.5 0.6 1.9 14 0.7
NMC_69 6.6 25 58 3.0 1.3 4.0 28 1.4
NMC_7 13.2 25 103 6.2 2.5 7.9 50 3.1
NMC_70 7.8 33 65 3.9 1.5 4.7 32 2.0
NMC_71 6.4 25 49 3.0 1.2 3.8 23 1.4
NMC_72 1.0 25 11 0.5 0.2 0.6 6 0.2
NMC_73 3.3 25 28 1.5 0.6 2.0 14 0.7
NMC_74 8.0 21 48 3.7 1.5 4.8 21 1.8
NMC_75 6.4 25 51 2.9 1.2 3.9 23 1.4
NMC_76 1.9 25 18 0.9 0.4 1.2 9 0.4
NMC_77 13.8 37 111 6.5 2.6 8.3 52 3.2
Table 6.2
Watershed Modeling Results for Subwatersheds in the Nine Mile Creek - Central Drainage Area
1 The 1%-Annual-Chance (100-Year) 10-day snowmelt event is defined as 7.2 inches of runoff
Watershed ID
Total Area
(ac)
% Impervious
Area
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Watershed Information 1%-Annual-Chance (100-Year)1%-Annual-Chance (100-Year)10%-Annual-Chance (10-Year)
24-Hour Precipitation Event 10-day Snowmelt Event1 24-Hour Precipitation Event
NMC_78 4.6 25 41 2.0 0.9 2.7 20 1.0
NMC_79 0.4 24 5 0.2 0.1 0.2 3 0.1
NMC_80 2.2 24 20 1.0 0.4 1.3 10 0.5
NMC_81 3.0 32 23 1.4 0.6 1.8 10 0.7
NMC_82 2.9 25 25 1.3 0.5 1.7 12 0.6
NMC_83 3.7 26 35 1.7 0.7 2.2 18 0.8
NMC_84 6.9 31 54 3.4 1.3 4.1 26 1.7
NMC_85 2.0 25 21 1.0 0.4 1.2 11 0.5
NMC_86 9.5 26 75 4.5 1.8 5.7 36 2.2
NMC_87 1.1 65 13 0.6 0.2 0.7 7 0.4
NMC_88 1.8 50 22 0.9 0.3 1.1 13 0.5
NMC_89 9.0 58 99 4.7 1.7 5.4 52 2.4
NMC_9 1.7 34 18 0.9 0.3 1.0 9 0.5
NMC_90 14.3 25 117 6.8 2.7 8.6 57 3.4
NMC_91 5.2 25 34 2.4 1.0 3.1 15 1.2
NMC_92 2.1 65 23 1.2 0.4 1.3 13 0.7
NMC_93 2.0 65 22 1.1 0.4 1.2 12 0.6
NMC_94 6.6 65 68 3.6 1.3 4.0 35 1.9
NMC_95 7.0 25 59 3.1 1.3 4.2 28 1.5
NMC_96 15.6 25 118 7.1 3.0 9.4 54 3.4
NMC_97 6.1 25 52 2.7 1.2 3.7 25 1.3
NMC_98 7.5 25 66 3.5 1.4 4.5 33 1.7
NMC_99 4.2 25 38 1.9 0.8 2.5 19 0.9
Table 6.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - Central
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
100 878.7 877.4
301 883.3 882.9
305 879.1 878.7
307 865.4 864.5
308 864.9 863.6
310 856.6 856.0
327 856.1 855.8
329 858.7 858.3
332 866.2 865.8
335 869.5 869.3
336 872.8 871.6
338 879.0 878.6
340 885.2 884.7
341 887.1 885.8
343 888.3 886.6
348 885.0 884.6
349 891.2 891.0
350 896.2 896.0
351 910.2 910.0
352 911.5 911.3
354 913.5 913.2
356 914.3 914.1
357 915.5 915.3
359 920.6 920.4
369 857.9 857.5
371 865.5 865.2
373 873.3 873.1
374 888.9 888.7
375 893.4 893.2
378 876.9 876.8
379 875.5 875.4
380 875.5 875.3
382 863.6 863.4
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
Table 6.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - Central
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
384 863.6 863.4
385 862.0 860.8
386 862.0 860.7
392 851.8 851.2
393 846.9 845.4
396 852.3 850.6
397 854.8 853.1
398 858.9 857.2
399 862.8 860.4
401 866.7 863.3
402 866.5 863.3
403 866.5 863.3
405 866.5 863.5
406 866.5 863.6
409 863.9 861.8
410 863.9 860.5
411 864.2 860.7
412 864.5 860.8
416 893.6 893.0
417 861.3 859.6
418 852.5 850.7
420 894.4 894.0
421 903.1 903.0
425 867.0 866.7
426 871.6 870.5
427 874.1 872.7
428 875.3 872.9
430 877.7 876.8
431 880.1 880.0
433 886.0 885.9
435 851.3 849.4
438 854.8 852.6
440 863.8 860.1
Table 6.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - Central
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
443 863.8 862.7
445 905.3 904.9
454 905.1 903.5
458 905.0 903.4
459 902.7 901.2
460 899.5 898.3
463 919.9 919.4
466 941.6 941.3
468 938.7 936.8
472 922.0 921.5
475 918.8 918.2
476 918.4 916.7
477 918.0 915.0
479 908.6 908.1
480 895.6 895.0
482 896.2 895.8
483 905.4 905.3
488 840.2 837.7
492 875.9 873.1
493 869.9 869.6
494 867.1 866.5
496 854.3 853.2
499 843.2 842.9
501 839.0 838.6
526 892.9 891.6
527 892.8 890.3
528 892.8 890.0
663 905.1 904.3
1609 874.5 874.4
1826 886.0 885.8
1827 899.7 898.3
1828 908.0 903.8
1915 868.2 867.3
Table 6.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - Central
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
1918 922.3 921.8
1919 922.0 921.7
1921 906.2 906.1
1923 909.3 909.0
1926 941.6 941.3
1927 941.4 941.2
1929 927.2 927.1
1930 940.3 940.2
1935 888.8 888.2
1936 888.8 888.2
1941 846.5 846.4
2072 871.6 871.3
2086 922.1 917.6
2088 951.5 945.9
2271 883.8 883.6
2272 896.9 896.7
2429 850.6 848.5
2431 863.8 862.6
2432 878.5 878.2
2433 887.1 884.0
2434 889.1 886.6
2556 896.1 894.7
2559 886.9 886.4
2560 884.4 883.9
2561 877.4 877.0
2563 861.6 861.2
2565 851.5 850.7
2566 850.5 850.0
2569 854.9 854.5
2570 parking lot 854.9 854.5
2579 905.1 904.0
2580 905.1 903.6
2921 857.1 857.0
Table 6.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - Central
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
2922 857.1 857.0
2923 857.1 857.0
2924 857.2 857.0
7269 915.1 911.2
7271 906.5 904.4
CBMH_131 904.6 904.2
CBMH_132 905.0 904.7
CBMH_136 904.5 904.3
CBMH_138 904.5 904.3
CO_1 pond 845.7 854.5 8.8 850.7 5.0
CO_10 parking lot 855.1 854.3
CO_11 street 857.8 857.1
CO_12 street/lot 854.9 854.5
CO_13 892.8 892.4
CO_2 pond 849.3 854.5 5.2 850.8 1.5
CO_3 pond 848.5 855.2 6.7 851.8 3.3
CO_4 pond 849.0 855.2 6.2 851.7 2.7
CO_5 pond 847.7** 854.5 6.8 850.8 3.1
CO_6 street 864.3 862.4
CO_7 pond 855.0 857.7 2.7 855.6 0.6
CO_8 890.5 890.0
CO_9 866.9 866.3
EdCrk10 creek 851.1 849.5
EdCrk11 846.0 845.2
EdCrk11a 849.6 848.3
EdCrk11b 849.2 848.1
EdCrk11c 848.4 847.4
EdCrk11c_1 847.8 847.1
EdCrk11c_2 847.4 846.6
EdCrk11c_3 847.3 846.6
EdCrk11d 846.7 845.9
EdCrk12 creek 844.5 844.0
EdCrk13 839.8 837.5
Table 6.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - Central
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
EdCrk13a 840.4 838.0
EdCrk13b 840.2 837.8
EdCrk13c 840.2 837.7
EdCrk13d 840.2 837.7
EdCrk13e 840.2 837.7
EdCrk14 834.6 832.6
EdCrk14a 836.6 834.4
EdCrk14b 834.6 832.8
EdCrk14c 834.6 832.7
EdCrk14d 834.6 832.6
EdCrk8 853.5 851.1
EdCrk8a 853.9 852.0
EdCrk8b 853.7 851.7
EdCrk9 creek 853.5 850.7
IP_1 pond 880.3** 890.5 ¹ 10.2 883.6 3.3
IP_2 street 894.0 892.5
IP_3 892.8 889.9
IP_4 byd 888.8 ¹ 886.0
N302 837.6 837.4
N310 862.2 861.5
N312 888.8 888.2
N315 860.1 860.0
NMC_10 859.4 859.2
NMC_100 street 847.4 847.0
NMC_101 841.3 841.0
NMC_102 byd 853.1 851.1
NMC_103 byd 863.9 860.5
NMC_104 860.6 860.1
NMC_105 hwy ditch 886.8 886.3
NMC_106 byd 846.0 845.8
NMC_107 byd 844.5 843.7
NMC_108 918.8 918.1
NMC_109 888.1 886.3
Table 6.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - Central
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
NMC_11 891.1 890.9
NMC_110e street/yard 904.5 904.0
NMC_110n street 905.4 905.2
NMC_110w street 904.5 904.3
NMC_111 street/byd 905.7 905.5
NMC_112 pond 901.0 905.0 4.0 904.2 3.2
NMC_113a byd 903.7 903.1
NMC_113b byd 905.0 903.4
NMC_113BP field 905.1 903.4
NMC_113c byd 903.3 902.4
NMC_113d 903.3 901.9
NMC_113e 893.0 892.0
NMC_113f 893.1 891.8
NMC_114 pond 900.0 905.1 5.1 903.5 3.5
NMC_115 street 905.1 903.4
NMC_116 byd 922.8 922.4
NMC_117 street 905.7 904.3
NMC_117a 917.0 915.4
NMC_118 park 872.1 870.5
NMC_119 byd 921.7 ¹ 919.5
NMC_12 889.2 887.5
NMC_120 street/yd 863.8 860.2
NMC_121 street 905.1 903.5
NMC_122 street 905.1 903.4
NMC_13 field/school 888.1 886.4
NMC_14 street 871.4 871.0
NMC_15 878.3 878.0
NMC_16 878.3 878.1
NMC_17 street 888.6 887.6
NMC_18 street 913.6 913.3
NMC_19 884.8 884.4
NMC_20 byd 853.1 851.4
NMC_21 cul-de-sac 922.6 922.4
Table 6.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - Central
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
NMC_22 941.1 941.0
NMC_23 street 857.3 857.1
NMC_24 910.4 910.0
NMC_25 street 941.6 941.3
NMC_26 929.4 928.7
NMC_27 922.2 921.9
NMC_28 hwy ditch 857.4 854.5
NMC_29 byd 922.8 922.4
NMC_30 942.0 941.5
NMC_31 912.1 912.0
NMC_32 880.6 880.2
NMC_34 935.4 935.3
NMC_35 street 870.7 870.3
NMC_36 street 907.5 907.4
NMC_37 938.3 936.1
NMC_38 971.4 967.8
NMC_39 917.8 913.9
NMC_4 912.4 912.0
NMC_40 cul-de-sac 841.9 841.0
NMC_41 byd 943.3 942.9
NMC_42 street 948.6 948.3
NMC_43 street 944.6 944.1
NMC_44 pond 940.8 944.6 3.8 942.9 2.1
NMC_45 street/yd 854.3 854.2
NMC_46 street/lot 904.3 904.1
NMC_47 street/lot 921.4 921.2
NMC_48 864.3 855.9
NMC_49 street 920.8 920.7
NMC_5 945.2 945.1
NMC_50 904.7 900.1
NMC_51 871.4 870.8
NMC_52 street 850.9 850.6
NMC_53 868.3 868.1
Table 6.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - Central
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
NMC_54 street 862.0 860.8
NMC_55 874.9 874.6
NMC_56 863.6 863.4
NMC_57 863.6 862.9
NMC_58 905.6 905.4
NMC_59 885.5 883.3
NMC_6 920.6 920.4
NMC_60 street 850.5 850.0
NMC_61 854.1 853.8
NMC_61$I 850.2 848.6
NMC_62 street 854.5 854.2
NMC_63 street 866.8 863.4
NMC_64 byd 863.4 861.9
NMC_65 street/yd 853.7 853.3
NMC_66 street/yd 859.4 859.0
NMC_67 street 872.1 871.4
NMC_68 885.6 885.5
NMC_69 906.1 906.0
NMC_69$I 898.6 898.6
NMC_7 866.2 865.2
NMC_70 pond 861.6 864.2 2.6 862.4 0.8
NMC_71 street 863.8 862.6
NMC_72 918.4 912.8
NMC_73 909.1 909.0
NMC_73$I 909.0 904.9
NMC_74 park 863.8 862.5
NMC_75 901.4 896.7
NMC_76 866.9 866.7
NMC_77 pond 857.5 861.3 3.8 859.6 2.1
NMC_78 street 903.2 902.5
NMC_79 864.3 862.7
NMC_80 byd 877.7 874.7
NMC_81 882.8 882.5
Table 6.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - Central
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
NMC_82 street 877.7 876.9
NMC_83 918.5 918.4
NMC_84 hwy ditch 863.8 861.0
NMC_85 street 872.8 872.1
NMC_86 street/yard 863.8 860.3
NMC_87 hwy ditch 857.4 856.3
NMC_88 890.5 889.8
NMC_89 918.2 917.9
NMC_9 byd 853.1 851.1
NMC_90 871.0 870.7
NMC_91 869.2 868.8
NMC_92 hwy ditch 857.4 853.6
NMC_93 hwy ditch 857.4 856.5
NMC_94 hwy ditch 857.4 854.5
NMC_95 street 836.6 836.1
NMC_96 845.7 845.4
NMC_97 837.8 837.5
NMC_98 840.0 839.4
NMC_99 878.1 877.9
Node393 899.5 897.9
Node394 896.3 895.4
£¤212
62
100
4567158
Gleason Rd Valley View Rd Hansen Rd Ridgeview Dr Valleyview Rd MudLake
HawkesLake
NorthBranchNine MileCreek
NMC_3
NMC_1
NMC_117
CO_13
NMC_101
NMC_46
CO_1
NMC_122
NMC_104
IP_2
CO_6
NMC_30
CO_9
NMC_117a
NMC_96
NMC_7
NMC_90
NMC_77
NMC_115
NMC_62
NMC_39
CO_8
NMC_32
CO_4
NMC_56
CO_5
NMC_111
NMC_50
IP_1 NMC_118
NMC_54
NMC_42
NMC_51
NMC_52
NMC_29
NMC_33
NMC_86
NMC_116
NMC_89
NMC_55
NMC_12
NMC_10
CO_2
NMC_49
NMC_63
NMC_16
NMC_112
NMC_100
CO_12
NMC_65
NMC_66 NMC_74
NMC_11
NMC_70
CO_7
IP_3
NMC_98
NMC_17
NMC_24
NMC_120
NMC_95
NMC_84
NMC_108
NMC_110n
NMC_94
NMC_69
NMC_75
NMC_71
NMC_41
NMC_61
NMC_47
NMC_97
CO_10
NMC_57
NMC_36
NMC_45
NMC_27
NMC_35
NMC_60
NMC_91
NMC_5
NMC_78
NMC_6
NMC_26
NMC_58
NMC_99
NMC_22
NMC_44
NMC_83
NMC_14IP_4
NMC_68
NMC_13
NMC_81
NMC_82
NMC_38
NMC_114
NMC_53
NMC_85
NMC_28 NMC_67
NMC_23
NMC_113a
NMC_19
NMC_110e
NMC_113f
NMC_113b
CO_11
NMC_103
NMC_64
NMC_113c
NMC_73
NMC_113e
NMC_20
NMC_106NMC_43
NMC_105
NMC_110w
NMC_21
NMC_4
NMC_113d
NMC_40
NMC_80
NMC_119
NMC_92
NMC_31
NMC_34
NMC_93
NMC_76
NMC_9
NMC_88
NMC_25
NMC_37
NMC_18
NMC_121
NMC_113BP
NMC_107
NMC_109
NMC_59
NMC_87
NMC_102 NMC_72
NMC_48NMC_15
CO_3
NMC_79
Barr Footer: ArcGIS 10.4.1, 2017-09-21 09:10 File: I:\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_6_1_NMC_Central_Drainage_Basins.mxd User: EMANINE MILE CREEK - CENTRALDRAINAGE BASINComprehensiveWater ResourcesManagement PlanCity of Edina, Minnesota
FIGURE 6.1
0 1,000
Feet
!;N
Nine Mile Creek - CentralDrainage Basin
Subwatershed
Streets and Highways
Creek/Stream
City of Edina Boundary
Lake/Wetland
Imagery Source: MnGeo; 2016
£¤212
62
100
4567158
Gleason Rd Valley View Rd Hansen Rd Ridgeview Dr Valleyview Rd MudLake
HawkesLake
Nine Mile Central
Colonial Ponds
Indian Pond
NorthBranchNine MileCreek
Barr Footer: ArcGIS 10.4.1, 2017-09-21 09:13 File: I:\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_6_2_NMC_Central_Major_Watersheds.mxd User: EMANINE MILE CREEK - CENTRALMAJOR WATERSHEDSComprehensiveWater ResourcesManagement PlanCity of Edina, Minnesota
FIGURE 6.2
0 1,000
Feet
!;N
Nine Mile Creek - CentralDrainage Basin
Major Watershed
Colonial Ponds
Indian Pond
Nine Mile Central
Subwatershed
Streets and Highways
Creek/Stream
City of Edina Boundary
Lake/Wetland
Imagery Source: MnGeo; 2016
City of Edina 2018 Comprehensive Water Resources Management Plan
6-21
Figure 6.3 Nine Mile Creek—Central Hydraulic Model Results
This is a large drawing (34x44).
Due to the paper and size and file size, this figure is included as a stand-alone PDF.
NMC_112 NMC_112
NMC_114
CO_7
CO_2
CO_5
IP_1
CO_3
CO_4
CO_1
NMC_70
NMC_77
NMC_44
N i n e M ile Creek
Barr Footer: ArcGIS 10.4.1, 2017-09-21 07:57 File: \\barr.com\gis\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_5_4_NMC_North_Water_Quality.mxd User: rcs2NINE MILE CREEK CENTRALWATER QUALITY MODELING RESULTSComprehensive Water ResourceManagement PlanCity of Edina, Minnesota
FIGURE 6.4
1,200 0 1,200Feet
!;N
400 0 400Meters
Percent TP Removal in Water Body*This number represents the percent of the total annual massof phosphorus entering the water body that is removed.
Cumulative TP Removal in Watershed*This number represents the percent of the total annual massof phosphorus entering the watershed and upstream watershedsthat is removed in the pond and all upstream ponds.
*Data based on results of 2003 P8 modeling.
0 - 25% (Poor/No Treatment)
25 - 40% (Moderate Removal)
40 - 60% (Good Removal)
60 - 100% (Excellent Removal)
0 - 25% (Poor/No Treatment)
25 - 40% (Moderate Removal)
40 - 60% (Good Removal)
60 - 100% (Excellent Removal)
Imagery Source: USDA 2016 NAIP via MnGeo
Area Draining Directly to the NorthFork of Nine Mile Creek
Flow Direction
City of Edina 2018 Comprehensive Water Resources Management Plan
7-1
7.0 Lake Cornelia/Lake Edina/Adam’s Hill
7.1 General Description of Drainage Area
Figure 7.1 depicts the Lake Cornelia/Lake Edina/Adam’s Hill drainage basin. This drainage basin is located
in the southeast portion of Edina and encompasses 1,477 acres.
7.1.1 Drainage Patterns
This chapter discusses four major watersheds within the drainage basin: North Lake Cornelia, South Lake
Cornelia, Lake Edina, and the Adam’s Hill Pond drainage area. These major watersheds are depicted in
Figure 7.2. North and South Lake Cornelia ultimately drain to Lake Edina, which outlets into the North
Fork of Nine Mile Creek. The Adam’s Hill drainage area includes those watersheds within the City of Edina
that drain to the Adam’s Hill stormwater detention basin in Richfield. This drainage area was analyzed in
conjunction with the North Cornelia watershed because the storm sewer systems draining to North Lake
Cornelia and Adam’s Hill Pond are adjoined at the intersection of 69th Street and York Avenue. Each of the
four major watersheds have been further delineated into numerous subwatersheds. The naming
convention for each subwatershed is based on the major watershed where it is located. Table 7.1 lists
each major watershed and the associated subwatershed naming convention. The stormwater system
within these drainage basins comprises storm sewers, ponding basins, drainage ditches, and overland flow
paths.
Table 7.1 Major Watersheds within the Lake Cornelia/Lake Edina/Adam’s Hill Drainage Basin
Major Watershed
Subwatershed Naming
Convention
Number of
Subwatersheds
Drainage Area
(acres)
Lake Cornelia—North NC_## 162 863
Lake Cornelia—South SC_## 9 112
Lake Edina LE_## 48 394
Adam's Hill (Richfield) AHR_## 20 108
7.1.1.1 North Cornelia
North Lake Cornelia has a large watershed, encompassing 863 acres. The North Cornelia watershed has
been delineated into 162 subwatersheds and is characterized by several ponding basins within the
watershed. Land use within this watershed comprises a large commercial area (including the Southdale
Shopping Center), portions of TH 62 and TH 100, residential areas (high and low density), parks, wetlands,
and open water. The majority of the runoff from the highly impervious commercial area drains through
the France Avenue and West 66th Street storm sewer system and discharges into the Point of France pond,
located just northeast of the West 66th Street and Valley View Road intersection. The Point of France pond
drains to the Swimming Pool Pond west of Valley View Road, which typically drains to North Lake
Cornelia. During large storms, such as the 1-percent-annual-chance event, when North Lake Cornelia
City of Edina 2018 Comprehensive Water Resources Management Plan
7-2
nears its capacity, the Swimming Pool Pond will flow northward through two 60-inch culverts located
under TH 62 that connect the Swimming Pool Pond with the Brookview Pond, just north of TH 62. An
outlet control structure on the north side of this pond allows flows to the north into Lake Pamela when
the water elevation reaches 863.3 feet.
North Lake Cornelia covers approximately 29 acres and serves as a recreation area for the City of Edina.
The lake outlets to South Lake Cornelia through a 12-inch culvert beneath West 66th Street.
7.1.1.2 South Lake Cornelia
The South Lake Cornelia watershed is located south of the North Lake Cornelia watershed. The 112-acre
watershed comprises 9 subwatersheds, with two stormwater detention areas in addition to Lake Cornelia.
The land use within the watershed is low-density residential and open water.
South Lake Cornelia spans approximately 32 acres. The normal elevation of the lake is controlled by a weir
structure at 859 feet. Discharge from South Cornelia flows southward through a 54-inch system for
approximately 1,000 feet, where it connects with a 21-inch system at the intersection of Dunberry Lane
and Cornelia Drive. This system ultimately drains to Lake Edina. During extreme storm events, such as the
1-percent-annual-chance event, the 21-inch pipe at Dunberry Lane and Cornelia Drive restricts flow,
resulting in flow northward through the 54-inch system and into South Lake Cornelia.
7.1.1.3 Lake Edina
The Lake Edina watershed is located south of the Lake Cornelia drainage basins. The watershed
encompasses approximately 394 acres and has been delineated into 48 subwatersheds. Land use within
the watershed is mainly low-density residential, with smaller portions of high density residential,
commercial, institutional (Cornelia Elementary School), park, wetland, and open water. A wetland along
the west side of Lake Edina, directly east of TH 100, receives runoff from an area of approximately
40 acres. Flow from this wetland discharges into Lake Edina via a weir structure and pipe system.
Lake Edina spans an area of approximately 23 acres. The normal elevation of the lake is controlled by a
weir structure at 822 feet. Discharge from Lake Edina flows through a 36-inch system underneath TH 100
and into the North Fork of Nine Mile Creek.
7.1.1.4 Adam’s Hill Pond
The Adam’s Hill drainage area discussed in this analysis includes the 108-acre area within the City of Edina
that drains to the Adam’s Hill Pond in Richfield. The outlet from Adam’s Hill Pond is a pumped outlet that
discharges 10 cfs to Centennial Lakes.
7.2 Stormwater System Results
7.2.1 Hydrologic/Hydraulic Modeling Results
The 10- and 1-percent-annual-chance flood analyses were performed for the Lake Cornelia/Lake
Edina/Adam’s Hill drainage basins. The 10-percent-annual-chance analysis was based on a ½-hour storm
City of Edina 2018 Comprehensive Water Resources Management Plan
7-3
with 1.65 inches of rain. The 1-percent-annual-chance analysis was based on a 24-hour storm with
7.47 inches of rain and on a 10-day snowmelt event with 7.2 inches of runoff; the higher resulting flood
level of the two events was chosen for the 1-percent-annual-chance analysis. Table 7.2 presents the
watershed information and the results for the 10- and 1-percent-annual-chance hydrologic analyses. A
more detailed description of the stormwater system analysis is provided in Section 4.1.3.
The results of the 10- and 1-percent-annual-chance hydraulic analyses for the Lake Cornelia/Lake
Edina/Adam’s Hill drainage areas are summarized in Table 7.3.
Figure 7.3 illustrates the results of the 10- and 1-percent-annual-chance hydraulic analyses. The figure
depicts the boundaries of the drainage areas, subwatershed boundaries, the modeled storm sewer
network, surcharge conditions for the XP-SWMM nodes (typically manholes), and the flood-prone areas
identified in the modeling analyses.
Figure 7.3 illustrates that several XP-SWMM nodes within the Lake Cornelia/Lake Edina/Adam’s Hill
drainage areas are predicted to surcharge during both the 10- and 1-percent-annual-chance events. This
means that in any year there is a greater than 10 percent probability that the system will be overburdened
and unable to meet the desired level of service at these locations. These manhole and catch basins are
more likely to become inundated during the smaller, more frequent storm events of various durations.
To evaluate the level of protection of the stormwater system within the Lake Cornelia/Lake Edina/Adam’s
Hill drainage areas, the 1-percent-annual-chance flood elevations for the ponding basins and depressed
areas were compared to the low elevations of structures surrounding each basin. The areas predicted to
potentially flood and threaten structures during the 1-percent-annual-chance storm event are shown on
Figure 7.3.
Discussion and recommended improvement considerations for these areas are included in Section 7.3.
7.2.2 Water Quality Modeling Results
The effectiveness of the stormwater system in removing stormwater pollutants such as phosphorus was
analyzed using the P8 water quality model. The P8 model simulates the hydrology and phosphorus loads
introduced from each pond’s watershed and the transport of phosphorus throughout the stormwater
system. A more detailed description of the stormwater system analysis is provided in Section 4.1.3.
Figure 7.4 depicts the results of the water quality modeling for the Lake Cornelia/Lake Edina/Adam’s Hill
drainage areas. The figure shows the fraction of total phosphorus removal for each water body as well as
the cumulative total phosphorus removal in the watershed.
7.3 Implementation Considerations
The 2017 XP-SWMM hydrologic and hydraulic modeling analyses and 2003 P8 water quality analysis
helped identify locations throughout the watershed where improvements to the City’s stormwater
management system may be warranted. The following sections discuss potential improvement options
City of Edina 2018 Comprehensive Water Resources Management Plan
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identified as part of the modeling analyses. As opportunities to address identified flooding issues and
improve water quality arise (e.g., street reconstruction projects or public facilities improvements), the City
will use a comprehensive approach to stormwater management. This approach will include consideration
of infiltration or volume retention practices to address flooding and/or improve water quality, reduction of
impervious surfaces, increased storm sewer capacity where necessary to alleviate flooding, construction
and/or expansion of water quality basins, and implementation of other stormwater BMPs to reduce
pollutant loading to downstream waterbodies.
7.3.1 Flood Protection Projects
The 2017 hydrologic and hydraulic modeling analyses identified several locations within the Lake Cornelia,
Lake Edina, and Adam’s Hill drainage basin where the 1-percent-annual-chance level of protection is not
provided by the current stormwater system. The problem areas identified in 2017 are discussed below.
As part of the 2017 modeling analyses, potential corrective measures were identified for the problem
areas. These preliminary corrective measures are also discussed below. As the City evaluates flooding
issues and potential system modifications in these areas, other potential modifications, including (but not
limited to) implementation of volume-retention practices, increases in conveyance capacity, and/or
stormwater infiltration (where soils are conducive) will be given consideration.
The 2003 hydrologic and hydraulic modeling analyses identified several locations within the Lake Cornelia,
Lake Edina, and Adam’s Hill drainage basin where the 1-percent-annual-chance level of protection was
not provided by the stormwater system, based on TP-40 precipitation frequency estimates. The
discussions related to those areas have been carried over to Appendix C of this plan, along with a short
summary of what has been done in those areas since 2003.
7.3.1.1 Valley View and Southdale Road Neighborhood (LE_34, LE_36, and LE_43)
A significant local depression exists along Southdale Road south of West 68th Street, extending westward
to Dawson Lane and eastward to Valley View Road. Under existing conditions, the low areas at Southdale
Road and Valley View Road are drained by a 36-inch pipe that conveys runoff to the storm sewer system
along Cornelia Drive. The lowest point along Southdale Road is approximately 862.8 feet, and the surface
overflow from this area, to the southeast along West 70th Street, is approximately 869.5 feet. The 1-
percent-annual-chance flood elevation for this area (866.6 feet) inundates Dawson Lane, Southdale Road
and Valley View Road, portions of which would be under more than 2 feet of water, and may impact up to
28 principle structures (not counting sheds or other smaller outbuildings).
The flooding problem in this area is primarily related to the capacity of the existing storm sewer system,
which is controlled in part by the size of the local drainage pipe and partly due to tailwater conditions in
the downstream storm sewer system on Cornelia Drive. High flow velocities through smaller 24-inch pipes
under West 72nd Street result in significant friction losses that limit outflow and back up water in the
Cornelia Drive storm sewer system. Additionally, surface overflows from Valley View Road occur at West
68th Street, contributing additional runoff to the low area along Southdale Road. Proposed solutions to
the flooding problem are to reduce or eliminate inflow from Valley View Road and to increase the
City of Edina 2018 Comprehensive Water Resources Management Plan
7-5
discharge capacity from the Southdale Road low area. Detailed modeling of proposed improvements was
performed as part of this Plan update; the results are described below.
Surface overflow from Valley View Road at West 68th Street could be reduced or eliminated by preventing
surface overflows to Valley View Road from the properties south of West 69th Street (LE_43, NC_119) and
raising West 68th Street at the intersection with Valley View Road. These proposed flood reduction
measures would decrease the 1-percent-annual-chance peak water surface elevation in the Southdale
Road low area by 0.1 feet, preventing flood impacts from only one principle structure. This indicates that
while surface overflow from Valley View Road contributes to the problem in this area, the volume of
runoff is small in comparison to local drainage.
Stormwater is conveyed from the Southdale Road low area via a 36-inch pipe to the west. Upon reaching
the intersection of Dunberry Lane and Cornelia Drive, water flows north to South Lake Cornelia through a
54-inch pipe and over a weir, despite the storm sewer sloping south to West 70th Street. This is part of the
storm sewer design, using South Lake Cornelia for storage before it peaks due to regional flooding. To
evaluate improvement options, the capacity of the storm sewer system under Cornelia Drive between
South Cornelia and Dunberry Lane was doubled (both the pipe and weir), and the pipe under Dunberry
Lane and Southdale Road was increased to a 54-inch pipe. The resulting 1-percent-annual-chance peak
water surface elevation in the Southdale Road low area decreased by 0.7 feet (LE_34 and LE_36), which
appears to protect 14 residences from impacts, based on LiDAR data and approximate building footprints.
It should be noted that the individual measures of doubling the capacity of the Cornelia Drive pipe or the
weir at South Cornelia had marginal impacts (0.0 to 0.2 feet reduction) on the Southdale Road
neighborhood.
To evaluate improvement options, the capacity of the storm sewer system south of West 70th Street was
also increased to reduce friction losses. The resulting 1-percent-annual-chance peak water surface
elevation in the Southdale Road neighborhood decreased by about 0.2 feet, which appears to protect four
principle structures from impacts based on LiDAR data and approximate building footprints. However, the
added capacity to the south had a negative impact on Lake Edina, raising the peak water surface elevation
by 0.3 feet.
Other flood improvement measures, contingent on proposed and future development east of Valley View
Road and throughout the larger area, are possible. Additional pipe capacity under Valley View Road and
West 66th Street to Lake Cornelia and/or storage in public land along Valley View Road may be available. If
capacity and/or storage is available, additional storm sewer could be installed to connect the Southdale
Road low area to the Valley View Road storm sewer system, draining this area to North Lake Cornelia.
Raising the surface overflow elevation from North Lake Cornelia to South Lake Cornelia along West 66th
Street is another option for consideration, as this could reduce the flood elevation in South Lake Cornelia.
City of Edina 2018 Comprehensive Water Resources Management Plan
7-6
7.3.1.2 Southwest Corner of TH 62 and TH 100 (NC_7, NC_8, NC_13, NC_11, NC_12, NC_14, NC_15, NC_16, and NC_20)
A portion of the Normandale Park neighborhood southwest of the TH 62 and TH 100 interchange and
north of West 66th Street drains to North Lake Cornelia via a storm sewer pipe under TH 100. There are
several depressions within this area that include portions of Warren, Mildred, Rolf, Tingdale, Wilryan, and
Josephine Avenues. Peak water surface elevations in these low areas from the 1-percent-annual-chance
24-hour storm event may impact up to 22 principle structures in the area north of West 64th Street
between Mildred Avenue and Josephine Avenue, not counting sheds or other smaller outbuildings, based
on LiDAR data and approximate building footprints.
The flooding problem in this area is primarily related to the capacity of the storm sewer system that
conveys stormwater from this area to North Lake Cornelia, particularly one 30-inch pipe segment running
from west to east under Parnell Avenue along West 65th Street, where the friction losses are significant
under full pipe flow conditions. The limited capacity raises upstream flood elevations. Additionally, the
number of catch basins limits the flow that can enter the storm sewer system. When the inlets and/or
storm sewer system are overwhelmed, water pools in the depression areas, impacting structures that are
below the surface overflow elevations.
A few alternatives were evaluated that moderately reduced the 1-percent-annual-chance flood elevations,
but did not significantly reduce the number of potentially impacted principle structures. Those alternatives
were focused on increasing the size of the 30-inch pipe segment, and on increasing the number of inlets
north of West 64th Street. The additional pipe capacity had a significant local impact on the east side of
TH 100, but did not have positive impacts far upstream.
One of the most effective improvement alternative evaluated for this area is the addition of underground
storage under the five streets north of West 64th Street. As these streets are reconstructed in the future,
the addition of storage should be considered. Assuming installation of 500 lineal feet of 20-foot wide and
3-foot deep storage, the 1-percent-annual-chance flood elevations in NC_7, NC_8, NC_11, and NC_13 are
each decreased by approximately 1 foot, potentially preventing impacts to more than 10 principle
structures. Another effective improvement alternative evaluated is increasing the pipe capacity of the
trunk storm sewer system from Wilryan Avenue (subwatershed NC_9) to North Lake Cornelia. This
alternative lowers the 1-percent-annual-chance flood elevation, also potentially preventing impacts to
about 10 principle structures.
7.3.2 Construction/Upgrade of Water Quality Basins
The 2003 P8 modeling analysis indicated that under average conditions the annual removal of total
phosphorus from several ponds in the Lake Cornelia/Lake Edina drainage area was predicted to be below
the desired 60 percent removal rate. For ponds with total phosphorus removal below 60 percent, the
permanent pool storage volume was analyzed to determine whether additional capacity was necessary.
The ponds with deficiencies in total phosphorus removal and permanent pool volume are listed below
(and are also summarized in Appendix D), with recommended pond upgrades.
City of Edina 2018 Comprehensive Water Resources Management Plan
7-7
Construction of new or expansion of existing water quality basins is one way to increase pollutant removal
prior to stormwater reaching downstream waterbodies. Many additional techniques are available to
reduce pollutant loading, including impervious surface reduction or disconnection, implementation of
infiltration or volume-retention BMPs, installation of underground stormwater treatment structures and
sump manholes, and other good housekeeping practices such as street sweeping. As opportunities arise
the City will consider all of these options to reduce the volume and improve the quality of stormwater
runoff.
7.3.2.1 LE_38
Pond LE_38 is located along the west side of Lake Edina, directly east of TH 100 (primarily within the
Minnesota Department of Transportation [MnDOT] right-of-way). The pond receives runoff from an area
of approximately 36 acres. Flow from this pond is discharged into Lake Edina via a weir structure and pipe
system. Based on the recommended storage volume discussed above, Pond LE_38 is deficient in
permanent pool storage volume. It is recommended that an additional 1.4 acre-feet of dead storage
volume be provided to meet the MPCA design criteria for detention basins.
7.3.2.2 NC_88
Pond NC_88 is located southeast of the intersection of York Avenue and West 64th Street. This basin has
two pumped outlets, with discharge eventually entering both the Point of France Pond and the Swimming
Pool Pond. Based on the MPCA-recommended storage volume for detention basins, there is not an
adequate amount of permanent pool storage in this basin. However, since the predicted total phosphorus
removal rate from this pond is approximately 50 percent and the pumped stormwater leaving this basin
will receive additional water quality treatment through several subsequent ponding basins,
recommendations for additional dead-storage volume are not being made at this time.
Table 7.2
Watershed Modeling Results for Subwatersheds in the Lake Cornelia/Lake Edina/Adam's Hill Drainage Area
1 The 1%-Annual-Chance (100-Year) 10-day snowmelt event is defined as 7.2 inches of runoff
Watershed ID
Total Area
(ac)
% Impervious
Area
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
AHR_1 3.4 27 23 1.4 0.6 2.1 9 0.6
AHR_10 1.2 80 10 0.7 0.2 0.7 5 0.4
AHR_11 7.8 79 40 4.2 1.4 4.7 18 2.3
AHR_12 4.8 80 38 2.7 0.9 2.9 18 1.4
AHR_13 2.1 79 15 1.1 0.4 1.3 7 0.6
AHR_14 8.5 50 67 4.0 1.6 5.1 28 1.9
AHR_15 9.2 54 78 4.4 1.8 5.5 34 2.2
AHR_16 4.2 50 39 2.0 0.8 2.5 18 1.0
AHR_17 3.0 50 27 1.4 0.6 1.8 12 0.7
AHR_18 2.4 80 15 1.3 0.4 1.4 7 0.7
AHR_19 1.0 80 11 0.5 0.2 0.6 6 0.3
AHR_2 2.8 54 31 1.3 0.5 1.7 15 0.7
AHR_20 10.5 42 74 4.6 2.0 6.3 30 2.2
AHR_21 1.9 70 20 1.0 0.4 1.2 10 0.5
AHR_3 4.3 49 36 2.0 0.8 2.5 16 1.0
AHR_4 24.1 46 149 10.8 4.5 14.5 59 5.2
AHR_5 4.9 40 42 2.1 0.9 3.0 17 1.0
AHR_6 1.4 73 11 0.7 0.3 0.8 5 0.4
AHR_7 1.1 32 13 0.5 0.2 0.7 6 0.2
AHR_8 9.3 78 56 5.0 1.7 5.6 26 2.7
LE_1 47.0 64 291 26.1 8.8 28.2 141 14.1
LE_10 4.6 25 42 2.2 0.9 2.7 22 1.1
LE_10a 42.1 25 259 18.6 8.0 25.2 110 8.8
LE_11 2.8 25 21 1.3 0.5 1.7 10 0.6
LE_12 8.7 25 56 3.8 1.6 5.2 24 1.8
LE_13 6.1 25 46 2.7 1.2 3.6 21 1.3
LE_14 3.0 25 31 1.4 0.6 1.8 16 0.6
LE_15 4.2 28 38 1.9 0.8 2.5 18 0.9
LE_16 4.8 26 36 2.1 0.9 2.9 16 1.0
LE_17 12.5 25 78 5.5 2.4 7.5 33 2.6
LE_18 1.8 25 11 0.7 0.3 1.0 4 0.3
LE_19 2.9 8 22 1.2 0.5 1.7 10 0.5
LE_2 3.8 27 34 1.7 0.7 2.2 17 0.8
LE_20 8.1 64 78 4.3 1.5 4.9 40 2.3
LE_21 4.7 23 35 2.1 0.9 2.8 16 1.0
LE_23 2.7 25 22 1.2 0.5 1.6 10 0.6
LE_24 23.5 39 161 11.0 4.5 14.1 71 5.4
LE_25 2.9 25 28 1.3 0.5 1.7 14 0.6
LE_26 12.9 30 102 5.9 2.4 7.7 47 2.8
LE_27 3.5 65 39 1.9 0.7 2.1 21 1.0
LE_28 17.0 25 113 7.9 3.2 10.2 51 3.8
LE_29 6.0 25 48 2.7 1.1 3.6 22 1.3
LE_3 3.9 30 33 1.8 0.7 2.3 16 0.9
LE_30 15.3 26 70 6.7 2.8 9.2 29 3.1
LE_31 7.7 25 68 3.5 1.5 4.6 33 1.7
LE_32 3.8 25 33 1.7 0.7 2.3 16 0.8
LE_33 7.1 25 64 3.2 1.4 4.3 31 1.5
LE_34 19.5 25 123 8.6 3.7 11.7 52 4.1
LE_35 1.8 38 15 0.8 0.3 1.1 7 0.4
LE_36 4.0 25 15 1.6 0.7 2.4 6 0.7
LE_37 1.2 65 13 0.7 0.2 0.7 7 0.3
LE_38 5.9 43 61 3.3 1.1 3.5 32 1.8
LE_39 1.0 65 10 0.5 0.2 0.6 5 0.3
LE_4 9.1 27 74 4.3 1.7 5.5 36 2.1
LE_40 5.8 28 40 2.6 1.1 3.5 17 1.3
LE_41 0.9 65 8 0.5 0.2 0.5 4 0.3
LE_43 5.2 74 41 2.7 1.0 3.1 19 1.5
LE_44 2.9 25 25 1.4 0.5 1.7 12 0.7
LE_45 2.4 25 23 1.1 0.4 1.4 11 0.5
LE_5 10.6 26 80 4.8 2.0 6.4 36 2.3
Watershed Information 1%-Annual-Chance (100-Year)1%-Annual-Chance (100-Year)10%-Annual-Chance (10-Year)
24-Hour Precipitation Event 10-day Snowmelt Event1 24-Hour Precipitation Event
Table 7.2
Watershed Modeling Results for Subwatersheds in the Lake Cornelia/Lake Edina/Adam's Hill Drainage Area
1 The 1%-Annual-Chance (100-Year) 10-day snowmelt event is defined as 7.2 inches of runoff
Watershed ID
Total Area
(ac)
% Impervious
Area
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Watershed Information 1%-Annual-Chance (100-Year)1%-Annual-Chance (100-Year)10%-Annual-Chance (10-Year)
24-Hour Precipitation Event 10-day Snowmelt Event1 24-Hour Precipitation Event
LE_51 13.1 22 67 5.7 2.5 7.9 28 2.6
LE_52 6.0 25 59 2.7 1.1 3.6 30 1.3
LE_53 6.5 25 65 2.9 1.2 3.9 33 1.4
LE_54 8.6 21 66 3.8 1.6 5.2 30 1.8
LE_6 8.3 25 62 3.8 1.6 5.0 29 1.9
LE_7 10.9 25 55 5.0 2.0 6.6 23 2.4
LE_8 2.1 25 21 1.0 0.4 1.3 11 0.5
LE_9 4.8 25 43 2.2 0.9 2.9 22 1.1
MPLS_130 3.8 25 42 1.7 0.7 2.3 22 0.8
NC_10 4.1 30 34 1.9 0.8 2.5 16 0.9
NC_100 1.5 80 13 0.8 0.3 0.9 7 0.4
NC_101 15.7 80 104 8.6 2.9 9.4 48 4.6
NC_101R 4.8 100 16 2.9 0.8 2.9 8 1.6
NC_102 3.8 80 27 2.1 0.7 2.3 12 1.1
NC_103 2.1 80 13 1.2 0.4 1.3 6 0.6
NC_104 6.5 34 64 2.8 1.2 3.9 30 1.3
NC_105 1.3 25 13 0.5 0.3 0.8 5 0.2
NC_106 6.4 80 35 3.5 1.2 3.9 16 1.9
NC_106a 6.6 90 41 3.8 1.2 4.0 20 2.1
NC_106aP 1.8 100 8 1.1 0.3 1.1 4 0.6
NC_106aR 3.9 100 12 2.3 0.7 2.3 5 1.3
NC_106R 2.1 100 9 1.3 0.4 1.3 4 0.7
NC_107 1.5 80 13 0.8 0.3 0.9 6 0.4
NC_108 1.0 80 9 0.6 0.2 0.6 4 0.3
NC_109 1.1 80 11 0.6 0.2 0.7 6 0.3
NC_11 9.0 26 68 4.0 1.7 5.4 31 1.9
NC_110 1.8 80 18 1.0 0.3 1.1 9 0.5
NC_111 5.8 79 44 3.2 1.1 3.5 20 1.7
NC_112 7.4 80 52 4.0 1.4 4.4 24 2.2
NC_113 11.3 80 82 6.2 2.1 6.7 38 3.4
NC_114 2.1 80 20 1.1 0.4 1.2 10 0.6
NC_115 2.2 80 22 1.2 0.4 1.3 11 0.6
NC_117 1.5 24 16 0.7 0.3 0.9 8 0.4
NC_118 1.3 23 14 0.6 0.2 0.8 7 0.3
NC_119 1.2 80 12 0.6 0.2 0.7 6 0.3
NC_12 7.5 25 57 3.3 1.4 4.5 26 1.6
NC_120 1.9 52 22 0.9 0.4 1.1 11 0.5
NC_121 2.1 80 15 1.1 0.4 1.2 7 0.6
NC_122 3.3 80 35 1.8 0.6 2.0 19 1.0
NC_123 4.1 95 27 2.4 0.8 2.5 13 1.4
NC_123R 2.4 100 7 1.4 0.4 1.4 3 0.8
NC_125 1.9 78 19 1.0 0.4 1.1 10 0.5
NC_126 2.7 65 29 1.4 0.5 1.6 15 0.7
NC_127 2.8 25 28 1.3 0.5 1.7 14 0.6
NC_128 3.3 65 37 1.7 0.6 2.0 19 0.9
NC_129 3.8 80 40 2.1 0.7 2.3 20 1.1
NC_13 2.5 25 25 1.1 0.5 1.5 13 0.5
NC_131 1.7 79 17 0.9 0.3 1.0 9 0.5
NC_132 6.7 59 72 3.3 1.3 4.0 37 1.7
NC_133 3.8 63 41 2.0 0.7 2.3 22 1.1
NC_134 1.6 65 19 0.8 0.3 1.0 10 0.4
NC_135 2.9 25 23 1.3 0.5 1.7 10 0.6
NC_136 5.2 25 37 2.3 1.0 3.1 16 1.1
NC_137 2.0 79 20 1.1 0.4 1.2 10 0.6
NC_138 1.0 61 12 0.5 0.2 0.6 7 0.3
NC_139 4.8 78 30 2.6 0.9 2.8 14 1.4
NC_14 5.2 25 50 2.3 1.0 3.1 25 1.1
NC_140 2.1 79 18 1.2 0.4 1.3 9 0.6
NC_141 2.6 80 17 1.4 0.5 1.6 8 0.8
NC_142 7.9 46 58 3.8 1.5 4.7 26 1.9
Table 7.2
Watershed Modeling Results for Subwatersheds in the Lake Cornelia/Lake Edina/Adam's Hill Drainage Area
1 The 1%-Annual-Chance (100-Year) 10-day snowmelt event is defined as 7.2 inches of runoff
Watershed ID
Total Area
(ac)
% Impervious
Area
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Watershed Information 1%-Annual-Chance (100-Year)1%-Annual-Chance (100-Year)10%-Annual-Chance (10-Year)
24-Hour Precipitation Event 10-day Snowmelt Event1 24-Hour Precipitation Event
NC_143 1.4 80 9 0.8 0.3 0.8 4 0.4
NC_144 7.7 80 65 4.3 1.5 4.6 32 2.3
NC_145 3.3 25 23 1.5 0.6 2.0 10 0.7
NC_146 9.8 70 83 5.1 1.9 5.9 39 2.7
NC_147 0.4 70 5 0.2 0.1 0.3 3 0.1
NC_148 0.8 37 9 0.5 0.2 0.5 5 0.3
NC_149 3.5 79 33 1.9 0.7 2.1 17 1.0
NC_15 4.7 25 39 2.1 0.9 2.8 18 1.0
NC_151 0.7 80 8 0.4 0.1 0.4 4 0.2
NC_152 1.7 80 16 1.0 0.3 1.0 8 0.5
NC_153 2.6 80 25 1.4 0.5 1.6 13 0.8
NC_154 5.1 80 42 2.8 1.0 3.1 20 1.5
NC_155 0.6 80 5 0.3 0.1 0.3 2 0.2
NC_156 3.4 80 32 1.9 0.6 2.0 16 1.0
NC_157 5.5 25 48 2.5 1.1 3.3 23 1.2
NC_158 2.2 25 22 1.1 0.4 1.3 11 0.6
NC_16 5.6 26 46 2.5 1.1 3.3 22 1.2
NC_17 1.8 25 18 0.8 0.3 1.1 10 0.4
NC_18 8.9 25 63 4.0 1.7 5.4 28 1.9
NC_19 7.8 30 64 3.5 1.5 4.7 30 1.7
NC_2 11.5 55 98 6.0 2.2 6.9 48 3.1
NC_20 2.0 28 15 0.9 0.4 1.2 7 0.4
NC_21 7.2 62 67 3.8 1.4 4.3 33 2.0
NC_22 5.8 21 49 2.8 1.1 3.5 24 1.4
NC_23 3.8 65 43 2.1 0.7 2.3 23 1.1
NC_24 6.3 28 55 2.9 1.2 3.8 27 1.4
NC_25 7.7 26 71 3.5 1.5 4.6 35 1.7
NC_26 1.9 65 22 1.0 0.4 1.2 12 0.6
NC_27 12.4 64 135 6.6 2.4 7.5 72 3.5
NC_28 1.1 65 13 0.6 0.2 0.7 7 0.3
NC_29 0.7 58 7 0.3 0.1 0.4 4 0.2
NC_3 16.2 56 146 9.4 3.1 9.7 75 5.2
NC_30 21.7 61 156 11.7 4.1 13.0 75 6.2
NC_31 6.6 27 56 3.0 1.3 4.0 27 1.4
NC_32 6.4 65 49 3.4 1.2 3.9 23 1.8
NC_33 2.5 60 29 1.3 0.5 1.5 15 0.7
NC_34 1.0 65 11 0.5 0.2 0.6 6 0.3
NC_35 10.6 25 86 4.7 2.0 6.3 40 2.3
NC_36 14.1 25 101 6.3 2.7 8.5 45 3.0
NC_37 2.2 23 20 1.0 0.4 1.3 10 0.5
NC_38 3.9 18 33 1.8 0.7 2.3 17 0.9
NC_39 4.7 28 40 2.1 0.9 2.8 19 1.0
NC_4 12.7 73 92 7.0 2.4 7.6 44 3.8
NC_40 7.0 29 50 3.2 1.3 4.2 22 1.5
NC_41 7.8 66 63 4.2 1.5 4.7 30 2.2
NC_42 8.3 65 35 4.3 1.5 4.9 15 2.3
NC_43 14.0 29 108 6.3 2.6 8.4 50 3.1
NC_44 2.8 70 26 1.5 0.5 1.7 13 0.8
NC_45 1.8 27 19 0.8 0.3 1.1 10 0.4
NC_46 15.2 29 64 6.7 2.8 9.1 27 3.1
NC_47 3.2 53 29 1.6 0.6 1.9 14 0.8
NC_48 8.2 25 62 3.7 1.6 4.9 28 1.7
NC_49 1.9 25 20 0.9 0.4 1.1 11 0.4
NC_5 8.6 60 75 4.5 1.6 5.2 37 2.4
NC_50 3.3 25 32 1.6 0.6 2.0 16 0.8
NC_51 3.7 61 37 1.9 0.7 2.2 19 1.0
NC_52 7.6 25 68 3.5 1.4 4.6 33 1.7
NC_53 2.2 25 18 1.0 0.4 1.3 9 0.5
NC_54 5.6 53 43 2.8 1.1 3.3 20 1.4
NC_55 2.5 15 22 1.2 0.5 1.5 11 0.6
Table 7.2
Watershed Modeling Results for Subwatersheds in the Lake Cornelia/Lake Edina/Adam's Hill Drainage Area
1 The 1%-Annual-Chance (100-Year) 10-day snowmelt event is defined as 7.2 inches of runoff
Watershed ID
Total Area
(ac)
% Impervious
Area
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Watershed Information 1%-Annual-Chance (100-Year)1%-Annual-Chance (100-Year)10%-Annual-Chance (10-Year)
24-Hour Precipitation Event 10-day Snowmelt Event1 24-Hour Precipitation Event
NC_56 16.0 27 109 7.2 3.0 9.6 48 3.4
NC_57 4.8 80 37 2.7 0.9 2.9 17 1.4
NC_58 11.6 25 94 5.2 2.2 7.0 44 2.5
NC_59 20.7 27 143 9.3 3.9 12.4 63 4.4
NC_6 5.1 55 51 2.6 1.0 3.0 26 1.4
NC_60 4.4 25 36 2.0 0.8 2.7 17 0.9
NC_61 2.1 25 21 0.9 0.4 1.2 10 0.4
NC_62 61.8 59 342 34.1 11.5 37.1 163 18.3
NC_63 1.7 31 18 0.9 0.3 1.0 10 0.5
NC_64 3.8 25 28 1.7 0.7 2.3 13 0.8
NC_65 2.2 65 26 1.3 0.4 1.3 14 0.7
NC_66 1.8 65 20 1.0 0.3 1.1 10 0.5
NC_67 1.4 29 13 0.6 0.3 0.9 7 0.3
NC_68 1.9 65 22 1.0 0.4 1.1 12 0.6
NC_69 2.0 76 20 1.1 0.4 1.2 10 0.6
NC_7 5.4 26 43 2.4 1.0 3.3 20 1.2
NC_70 2.5 25 25 1.1 0.5 1.5 13 0.5
NC_71 1.6 44 17 0.8 0.3 0.9 9 0.4
NC_72 0.8 47 9 0.4 0.2 0.5 5 0.2
NC_73 1.7 55 18 0.8 0.3 1.0 10 0.4
NC_74 1.1 25 12 0.5 0.2 0.7 6 0.2
NC_75 5.1 44 49 2.6 1.0 3.1 25 1.4
NC_76 1.2 65 14 0.6 0.2 0.7 7 0.3
NC_77 0.9 80 10 0.5 0.2 0.5 5 0.3
NC_78 3.1 31 27 1.7 0.6 1.9 14 0.9
NC_79 3.3 25 25 1.5 0.6 2.0 11 0.7
NC_8 3.3 26 21 1.5 0.6 2.0 9 0.7
NC_80 1.1 65 12 0.5 0.2 0.6 7 0.3
NC_81 6.2 73 56 3.3 1.2 3.7 27 1.8
NC_82 7.6 28 53 3.4 1.4 4.5 23 1.6
NC_83 2.8 72 24 1.5 0.5 1.7 11 0.8
NC_84 5.9 62 62 2.9 1.1 3.5 31 1.5
NC_85 7.8 50 48 3.6 1.5 4.7 20 1.8
NC_86 9.9 50 75 4.6 1.9 5.9 31 2.2
NC_87 2.7 76 28 1.4 0.5 1.6 14 0.8
NC_88 20.8 47 166 9.5 3.9 12.5 69 4.6
NC_89 5.2 76 47 2.8 1.0 3.1 23 1.5
NC_9 1.3 33 14 0.6 0.2 0.7 7 0.3
NC_90 5.2 80 35 2.9 1.0 3.1 16 1.6
NC_91 1.6 80 17 0.9 0.3 0.9 9 0.5
NC_92 3.4 28 31 1.4 0.6 2.0 13 0.6
NC_93 7.8 26 50 3.4 1.5 4.7 21 1.6
NC_94 4.2 28 33 1.9 0.8 2.5 15 0.9
NC_95 9.1 25 65 4.0 1.7 5.4 29 1.9
NC_96 10.2 25 67 4.5 1.9 6.1 29 2.1
NC_97 10.6 51 90 5.1 2.0 6.4 41 2.6
NC_98 1.6 25 16 0.7 0.3 0.9 8 0.3
NC_99 12.6 65 81 6.3 2.4 7.5 35 3.3
SC_1 55.3 72 376 30.6 10.4 33.2 180 16.6
SC_2 14.4 30 119 6.7 2.7 8.6 57 3.3
SC_3 11.6 30 100 5.3 2.2 6.9 48 2.6
SC_4 12.4 25 100 5.6 2.3 7.4 47 2.7
SC_5 2.8 25 25 1.5 0.5 1.7 13 0.8
SC_6 1.9 25 19 0.9 0.4 1.2 10 0.4
SC_7 6.0 25 44 2.7 1.1 3.6 20 1.3
SC_8 1.4 25 13 0.6 0.3 0.8 7 0.3
SC_9 6.6 25 52 3.0 1.2 3.9 25 1.4
Table 7.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Lake Cornelia/Lake
Edina/Adam's Hill Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
98 876.4 875.9
99 866.3 865.6
687 868.4 867.9
693 874.6 874.5
694 877.2 876.1
696 939.3 938.6
697 939.1 937.9
698 938.3 937.0
699 938.2 936.9
700 937.6 936.3
701 936.9 935.7
703 936.1 936.5
711 923.2 920.9
712 922.2 919.8
715 street 917.8 915.4
718 913.6 911.9
719 909.5 907.9
720 868.6 868.6
721 867.4 867.3
722 867.2 866.9
723 867.0 866.2
725 864.8 863.4
727 869.1 868.6
728 869.8 869.3
734 865.6 865.2
738 912.9 912.7
741 892.4 892.0
742 882.1 879.6
743 878.4 873.8
747 868.6 868.6
749 869.6 869.2
755 882.0 881.8
760 888.8 888.7
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
Table 7.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Lake Cornelia/Lake
Edina/Adam's Hill Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
762 895.1 894.7
766 867.1 867.0
768 868.3 867.8
769 869.2 868.3
771 869.2 868.3
776 866.3 865.3
777 865.9 864.7
778 865.4 863.9
779 865.0 863.4
782 868.0 866.7
783 867.6 866.4
785 866.3 865.8
793 868.0 867.5
796 867.6 866.0
797 868.2 866.8
798 867.9 866.4
805 864.8 863.1
808 866.0 863.9
809 866.7 865.3
813 867.4 866.2
816 868.6 867.3
818 869.8 868.1
819 street 869.9 868.3
820 869.9 868.6
821 869.9 868.9
822 869.9 868.9
823 869.9 869.0
824 878.5 875.8
825 875.6 873.1
826 875.6 872.3
830 873.7 870.8
831 880.5 879.5
838 864.6 860.8
Table 7.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Lake Cornelia/Lake
Edina/Adam's Hill Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
839 864.5 862.2
841 864.5 863.0
842 864.7 863.4
843 865.2 863.7
844 865.7 863.9
846 868.2 866.0
848 866.2 864.6
849 866.2 864.6
850 866.2 864.7
851 866.3 864.8
852 866.3 864.9
853 866.5 865.0
855 866.6 865.4
856 866.6 865.9
859 866.6 865.7
860 866.1 865.4
861 865.1 864.9
863 862.2 862.1
868 847.2 846.5
869 844.7 844.1
871 838.4 838.4
874 832.1 831.4
876 831.9 831.0
879 830.8 828.8
880 830.7 828.2
881 830.6 827.3
883 827.6 825.6
886 830.5 828.9
889 833.6 833.3
909 854.5 852.3
914 859.4 858.7
1369 864.8 863.0
1373 868.3 868.1
Table 7.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Lake Cornelia/Lake
Edina/Adam's Hill Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
1377 878.9 878.4
1379 877.1 876.7
1381 874.8 874.5
1390 879.9 878.9
1391 878.9 878.0
1393 877.0 876.1
1487 862.5 857.8
1488 859.9 856.4
1489 857.0 854.8
1490 853.8 852.4
1491 850.3 849.2
1553 878.9 878.7
1555 877.4 876.7
1557 872.5 872.2
1558 868.0 864.9
1560 869.1 867.2
1563 865.9 863.4
1564 860.3 859.2
1566 858.9 855.0
1567 856.2 850.7
1568 853.2 846.0
1569 854.1 850.5
1570 854.0 848.4
1576 879.8 879.0
1577 878.9 878.2
1578 878.9 878.1
1579 878.9 878.0
1581 878.0 877.0
1582 877.6 876.7
1583 877.3 876.5
1584 876.3 875.8
1586 870.0 867.7
1587 867.7 866.5
Table 7.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Lake Cornelia/Lake
Edina/Adam's Hill Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
1681 873.9 873.3
1833 872.0 870.9
1834 869.9 869.4
1972 826.4 823.9
1997 865.0 864.4
2020 884.5 884.5
2021 882.7 882.3
2027 876.8 876.2
2057 874.9 872.3
2062 875.0 873.6
2063 875.2 873.9
2065 875.2 874.1
2066 876.7 876.5
2067 874.9 874.7
2068 874.9 874.5
2138 867.1 865.9
2143 869.9 869.4
2144 869.7 869.4
2148 858.6 856.2
2150 869.1 867.4
2153 860.1 855.0
2154 860.5 855.1
2155 859.1 855.0
2171 872.7 872.6
2172 872.7 872.7
2186 868.1 867.5
2188 874.6 872.8
2189 878.6 877.8
2215 874.7 869.5
2216 874.7 870.2
2217 874.7 872.0
2219 875.1 874.3
2220 875.9 875.0
Table 7.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Lake Cornelia/Lake
Edina/Adam's Hill Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
2221 877.9 878.9
2222 878.1 879.4
2223 879.2 879.2
2224 874.7 872.2
2225 874.7 873.1
2228 874.7 873.5
2229 874.7 872.2
2230 880.7 874.6
2232 874.9 874.2
2233 874.9 874.1
2234 874.9 874.5
2238 880.3 880.0
2240 876.3 875.7
2286 881.6 881.2
2299 878.7 876.3
2300 873.9 872.0
2301 873.5 871.5
2302 873.1 871.1
2303 872.9 870.8
2304 872.1 870.1
2305 879.8 877.8
2306 877.8 876.9
2307 877.1 876.9
2308 877.2 877.0
2312 875.1 873.1
2313 878.8 876.9
2314 878.7 876.1
2315 878.7 875.9
2315.1 860.5 859.7
2316 858.5 857.9
2317 878.5 875.0
2317.1 856.5 856.1
2318 878.3 874.6
Table 7.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Lake Cornelia/Lake
Edina/Adam's Hill Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
2319 854.2 854.0
2320 852.3 852.2
2321 848.9 848.9
2324 876.5 875.5
2327 881.2 880.6
2329 882.8 882.7
2332 880.4 879.9
2333 881.1 880.6
2334 881.5 880.9
2336 881.6 881.0
2337 881.6 880.9
2338 881.6 880.9
2340 877.3 876.4
2345 917.2 914.5
2347 917.4 913.9
2350 919.2 916.5
2351 917.8 914.2
2352 918.7 914.7
2354 919.7 915.4
2355 920.5 915.9
2356 920.5 917.3
2357 922.9 918.9
2358 924.2 920.6
2360 877.0 875.4
2373.1 874.0 874.0
2374.1 872.9 872.9
2375 872.5 872.5
2376.1 872.5 872.5
2377 872.4 872.3
2386 872.3 871.8
2388 878.9 878.0
2466 870.8 869.4
2467 873.4 873.2
Table 7.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Lake Cornelia/Lake
Edina/Adam's Hill Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
2469 869.9 869.3
2472 872.1 869.4
2473 874.9 873.1
2476 870.4 863.8
2477 866.3 862.1
2761 880.8 878.2
2769 866.9 865.5
2779 881.7 881.2
2780 881.4 880.8
2781 881.7 881.0
2786 879.0 877.6
2796 870.0 869.5
2800 868.7 866.3
2801 860.5 859.4
2802 860.7 860.2
2803 861.0 860.8
2811 896.3 896.2
2813 895.4 895.2
2816 866.1 862.5
2817 865.3 862.6
2818 874.9 873.3
2819 872.6 872.5
2829 841.9 841.2
2839 827.3 825.8
2841 876.0 874.6
2842 875.9 874.8
2844 875.8 875.2
2845 875.9 874.9
2879 880.3 877.4
2903 877.1 876.9
2904 877.1 876.7
2913 875.9 875.0
2968 874.7 871.1
Table 7.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Lake Cornelia/Lake
Edina/Adam's Hill Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
2066$I 875.2 874.7
2262a 861.6 860.7
2373.1$I 873.5 873.4
2374.1$I 872.3 872.3
2375$I 872.2 872.2
2376.1$I 872.1 872.1
2377$I 869.9 869.0
747$I 867.1 867.1
AHR_1 842.3 838.6
AHR_10 869.1 867.6
AHR_11 street 869.0 867.1
AHR_12 parking lot 876.7 876.1
AHR_13 872.7 872.5
AHR_14 parking lot 864.4 864.2
AHR_15 street/lot 863.7 862.7
AHR_16 863.7 861.7
AHR_17 parking lot 854.3 854.1
AHR_18 872.0 867.1
AHR_19 874.8 874.1
AHR_2 street 860.1 858.4
AHR_20 parking lot 864.8 862.8
AHR_21 873.3 873.2
AHR_3 parking lot 861.2 860.8
AHR_4 street 854.0 847.3
AHR_5 path 852.3 844.1
AHR_6 865.1 861.9
AHR_7 866.6 862.4
AHR_8 street 866.7 864.7
CBMH_2 828.7 827.2
CBMH_6 830.6 829.1
CBMH_7 830.8 829.9
LE_1 lake 822.0 826.4 4.4 824.0 2.0
LE_10 street 830.6 828.8
Table 7.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Lake Cornelia/Lake
Edina/Adam's Hill Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
LE_10a street 831.0 830.5
LE_11 831.6 830.4
LE_12 833.9 833.4
LE_13 street 832.1 831.4
LE_14 street 860.6 860.4
LE_15 841.1 840.8
LE_16 859.3 857.7
LE_17 836.5 836.1
LE_18 859.2 858.8
LE_19 dry pond 854.2 850.9
LE_2 840.3 840.0
LE_20 dry pond 843.0 841.8
LE_21 street 854.5 851.9
LE_23 830.9 829.5
LE_24 street 854.2 852.5
LE_25 856.2 855.9
LE_26 school/park 858.8 857.9
LE_27 840.6 840.0
LE_28 street 873.9 873.3
LE_29 street 857.1 855.8
LE_3 835.2 834.6
LE_30 street 866.8 866.1
LE_31 street 873.2 870.7
LE_32 866.4 864.4
LE_33 street 864.5 862.7
LE_34 street 866.6 865.3
LE_35 866.6 866.4
LE_36 byd 866.6 865.3
LE_37 835.5 835.5
LE_38 wetland 822.2 827.3 5.1 825.9 3.7
LE_39 834.9 834.8
LE_4 street 832.6 832.2
LE_40 864.1 863.9
Table 7.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Lake Cornelia/Lake
Edina/Adam's Hill Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
LE_40$I 864.0 863.8
LE_41 hwy ditch 829.6 828.7
LE_43 street 866.6 865.9
LE_44 byd 871.3 ¹ 870.0
LE_45 byd 868.0 867.7
LE_5 841.8 841.6
LE_51 byd 840.5 ¹ 835.7
LE_52 street 840.6 839.8
LE_53 street 830.6 827.2
LE_54 park 847.4 ¹ 844.2
LE_6 street 834.0 833.7
LE_7 byd 831.1 830.4
LE_8 street 829.0 825.8
LE_9 street 828.2 827.9
MH_1034 829.5 826.6
MH2061 875.0 873.3
MPLS_130 byd 887.0 ¹ 885.5
N507 884.4 884.2
N510 873.2 873.2
N529 861.0 861.0
N530 cul-de-sac 912.5 912.5
N534 868.5 868.4
N543 858.7 857.6
NC_10 931.1 930.7
NC_100 parking lot 883.9 883.9
NC_100$I 881.1 878.1
NC_101 parking lot 875.7 874.2
NC_101a parking lot 883.1 881.3
NC_101R rooftop 900.0 900.0
NC_102 parking lot 881.1 879.9
NC_103 880.0 878.1
NC_104 street 876.7 876.4
NC_105 876.9 876.1
Table 7.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Lake Cornelia/Lake
Edina/Adam's Hill Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
NC_106 parking lot 878.7 875.6
NC_106a parking lot 877.5 876.2
NC_106aP parking lot 900.0 900.0
NC_106aR rooftop 900.0 900.0
NC_106b underground 881.6 881.2
NC_106R rooftop 900.0 900.0
NC_107 street 878.6 875.4
NC_108 street 877.1 876.9
NC_109 street 876.7 874.6
NC_11 street 936.7 935.5
NC_110 parking lot 878.7 878.4
NC_111 878.8 876.9
NC_112 parking lot 870.5 869.9
NC_113 parking lot 868.9 867.6
NC_114 parking lot 876.2 875.9
NC_115 878.9 877.8
NC_117 864.8 863.2
NC_118 865.4 863.1
NC_119 ditch 869.7 869.4
NC_12 street 935.3 935.1
NC_12$I 933.2 933.7
NC_120 868.2 866.8
NC_121 parking lot 876.8 875.7
NC_121ds 876.7 875.7
NC_122 875.6 875.2
NC_122a underground 877.4 876.5
NC_123 underground 881.6 879.4
NC_123R rooftop 900.0 900.0
NC_124a 884.5 884.4
NC_124c underground 881.2 879.5
NC_125 875.9 875.2
NC_126 877.7 876.9
NC_127 882.5 879.7
Table 7.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Lake Cornelia/Lake
Edina/Adam's Hill Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
NC_128 street 869.1 868.0
NC_129 878.8 878.6
NC_129$I 875.0 872.8
NC_13 street 939.2 938.8
NC_131 depression 871.6 868.5
NC_132 hwy ditch 874.7 872.2
NC_133 street 878.5 877.6
NC_134 876.2 875.5
NC_135 byd 909.9 ¹ 908.0
NC_136 870.2 870.0
NC_137 869.6 866.3
NC_138 869.2 868.7
NC_139 876.5 874.4
NC_14 street 932.8 932.6
NC_140 883.3 883.1
NC_141 parking lot 869.9 869.3
NC_142 street 875.9 874.8
NC_143 street 876.5 874.7
NC_144 878.9 878.6
NC_145 byd 880.1 878.8
NC_146 882.9 880.3
NC_147 parking lot 876.6 876.5
NC_148 868.2 865.9
NC_149 875.2 875.0
NC_15 street 928.7 928.2
NC_15$I 925.7 923.6
NC_150 875.2 874.1
NC_151 parking lot 883.5 882.9
NC_152 882.0 881.9
NC_153 loading dock 881.7 881.0
NC_154 879.4 878.5
NC_155 883.9 881.3
NC_156 parking lot 881.2 880.8
Table 7.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Lake Cornelia/Lake
Edina/Adam's Hill Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
NC_157 street 884.5 880.7
NC_158 byd 881.8 880.9
NC_16 street 928.7 927.0
NC_17 914.8 913.0
NC_18 875.0 874.6
NC_19 street/yard 918.5 916.5
NC_2 pond 863.0 866.3 3.3 865.3 2.3
NC_20 street 928.7 927.1
NC_21 910.1 905.7
NC_22 street 866.8 865.5
NC_23 921.4 919.0
NC_24 street 875.9 875.6
NC_25 881.9 881.8
NC_26 hwy ditch 869.3 868.3
NC_27 889.9 889.4
NC_28 hwy ditch 869.7 868.8
NC_28_CB 869.6 868.5
NC_29 874.5 874.5
NC_29$I 872.9 872.9
NC_3 pond 862.9 866.3 3.4 865.9 3.0
NC_30 pond 862.9 866.3 3.4 865.7 2.8
NC_31 897.7 897.5
NC_32 893.6 893.0
NC_33 888.8 888.7
NC_34 879.4 879.3
NC_34_IN 880.7 880.2
NC_35 896.3 896.0
NC_36 913.3 913.1
NC_37 869.7 863.9
NC_38 street 865.5 865.1
NC_39 street 869.6 869.3
NC_4 pond 862.9 867.2 4.3 866.3 3.4
NC_40 street/byd 869.2 868.3
Table 7.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Lake Cornelia/Lake
Edina/Adam's Hill Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
NC_41 hwy ditch 916.5 913.5
NC_42 hwy ditch 897.4 897.3
NC_43 depression 894.5 894.2
NC_44 925.4 922.0
NC_45 byd 918.7 916.6
NC_46 street 919.2 915.0
NC_47 byd 918.7 916.5
NC_48 869.5 869.1
NC_49 street 867.6 866.0
NC_5 pond 864.5 868.3 3.8 866.9 2.4
NC_50 byd 877.3 877.0
NC_51 872.4 871.4
NC_52 873.5 873.3
NC_53 895.2 894.9
NC_54 869.0 866.9
NC_55 byd 878.2 877.3
NC_56 street 878.5 878.1
NC_57 878.0 874.0
NC_58 877.3 877.1
NC_59 905.0 904.7
NC_6 pond 864.2** 867.7 3.5 866.0 1.8
NC_60 street 869.2 869.0
NC_61 byd 867.1 866.6
NC_62 pond 859.0 864.8 5.8 863.1 4.1
NC_63 street 870.1 869.7
NC_64 byd 873.7 872.2
NC_65 hwy ditch 867.6 866.3
NC_66 868.0 867.0
NC_67 889.2 889.1
NC_68 871.5 868.2
NC_69 hwy ditch 869.0 867.4
NC_7 street 939.5 939.3
NC_70 street 868.1 867.6
Table 7.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Lake Cornelia/Lake
Edina/Adam's Hill Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
NC_71 hwy ditch 867.3 866.3
NC_72 pond 860.2** 864.8 4.6 863.1 2.9
NC_73 street 868.1 866.8
NC_74 870.1 869.5
NC_75 street 867.1 865.9
NC_76 868.2 866.9
NC_77 876.9 873.0
NC_78 pond 859.3** 864.8 5.5 863.1 3.8
NC_79 869.3 868.9
NC_8 byd 939.5 938.1
NC_80 876.8 874.8
NC_81 879.5 877.4
NC_82 street 874.7 874.5
NC_83 parking lot 876.0 875.6
NC_84 hwy ditch 874.7 873.5
NC_85 parking lot 880.9 880.7
NC_86 street 880.5 879.5
NC_87 883.6 883.4
NC_88 pond 862.0 873.9 11.9 871.0 9.0
NC_89 street 876.0 875.6
NC_9 935.1 936.5
NC_90 881.0 879.0
NC_91 street 883.8 883.0
NC_92 park 880.1 879.9
NC_93 880.2 878.8
NC_94 880.8 880.6
NC_95 street 884.0 883.6
NC_96 885.6 885.4
NC_97 street 880.5 879.5
NC_98 886.4 881.2
NC_99 street 880.5 879.5
NC-124b underground 883.4 882.5
Node396 872.0 871.9
Table 7.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Lake Cornelia/Lake
Edina/Adam's Hill Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
Node397 868.7 868.7
Node399 877.2 876.0
Node400 877.7 875.8
Node401 877.2 875.9
Node402 877.3 875.9
Node403 877.4 875.9
Node404 877.5 875.8
Node405 878.5 875.7
Node414 881.0 879.8
Node415 879.6 879.0
Node419 869.0 869.0
Node420 874.9 874.8
Node421 874.9 874.7
Node423 870.8 870.8
Node426 875.4 875.0
Node429 884.1 883.8
Node430 883.5 882.8
Node431 883.4 882.4
Node432 880.0 880.0
Node433 881.2 879.5
Node434 874.5 874.5
Node436 876.8 876.8
Node437 880.4 879.9
Node438 883.8 883.7
Node439 883.7 883.4
Node440 881.7 880.1
Node441 881.5 879.5
Node442 881.4 879.0
Node443 881.2 878.4
Node444 877.8 876.5
Node564 865.3 861.5
Node565 865.3 860.9
Node567 865.3 861.9
Table 7.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Lake Cornelia/Lake
Edina/Adam's Hill Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
Node568 865.3 860.9
Node571 866.3 865.9
Node572 864.8 863.1
SC_1 lake 859.0 864.6 5.6 860.5 1.5
SC_2 dry pond 873.2 871.8
SC_3 pond 874.7 878.5 3.8 876.7 2.0
SC_4 868.3 867.9
SC_5 street 867.0 865.3
SC_6 cul-de-sac 881.5 873.9
SC_7 street 867.5 866.5
SC_8 street 865.9 862.6
SC_9 street/byd 865.0 864.8
To_MHS_53 884.1 884.0
62
100
456717
456753
456731
Wooddale Ave Parklawn Ave Brookview Ave W 70th St
Adam's HillPond
Lake Edina
South Lake Cornelia
North Lake Cornelia
RichfieldRichfield
MinneapolisMinneapolis
N o r t h B r anch N i n eMileCreek
SC_1
NC_62
LE_1
LE_10a
LE_24
AHR_4
NC_30
LE_28
LE_34
NC_88
NC_59
NC_3
SC_2
LE_30
NC_56
NC_46
NC_4
SC_4
NC_101
NC_36
LE_7
LE_51
SC_3
NC_43
LE_26
NC_2
LE_5
LE_17
NC_99
NC_27
LE_4
NC_58
LE_6
NC_97
NC_35
NC_5
NC_96
NC_86
NC_113
LE_12
NC_11
LE_54
NC_95
AHR_8
NC_18
AHR_20
LE_20
NC_146
NC_42 NC_48
LE_31
SC_9
NC_41
NC_85
AHR_15
NC_19
NC_25
LE_33
NC_52
NC_82
NC_12
SC_7
NC_124
AHR_14
NC_21
NC_106a
NC_40
NC_106
LE_53
NC_142
AHR_11
NC_31
LE_13
NC_112
NC_7 NC_32
LE_29
LE_52
NC_24
NC_144
LE_40
LE_9
NC_6
NC_132
NC_22NC_16
LE_43
NC_90
NC_14
NC_89
NC_111
LE_3 LE_21
AHR_5
NC_57
NC_39
NC_15
NC_121
LE_15
NC_123
NC_93
AHR_3
NC_10
NC_139
AHR_12LE_32
NC_51
AHR_16
SC_5
AHR_1
NC_133
NC_47
LE_44
LE_11
NC_149
NC_156
LE_23
NC_83
NC_122
SC_6 NC_153
NC_103
LE_38
NC_81
NC_84 NC_104
NC_54
NC_75
LE_16
LE_10
LE_2
NC_157
NC_150
NC_136
NC_60
LE_36
NC_94NC_8
NC_38
NC_23
NC_64
NC_154
LE_27
NC_101R
NC_129
NC_92
NC_79
NC_50
LE_14
NC_78
LE_25
LE_19
NC_145
NC_128
NC_102
NC_44
AHR_2
LE_8
NC_87
NC_33
NC_106aR
LE_45
MPLS_130
NC_70
AHR_17
NC_55
NC_135
NC_13
NC_127 NC_126
NC_141
NC_65
NC_37
NC_53
NC_61
AHR_18
NC_20
NC_69
NC_26
NC_158
NC_68
NC_155
NC_49
LE_35
LE_18
NC_140
NC_45
NC_114
NC_66
NC_17
AHR_13
NC_123R
NC_137
SC_8
NC_63 NC_73
NC_120
AHR_21
NC_125
NC_98
NC_110
NC_71
NC_91
NC_106R
NC_152
NC_9
NC_100
NC_115
NC_131
NC_67
NC_134
AHR_6
NC_106aP
LE_37
NC_117 NC_76 NC_143
NC_105
NC_28
NC_74
NC_118 NC_107
AHR_7
LE_39
NC_80
AHR_10
NC_119
NC_108
NC_34
NC_109NC_77
LE_41
NC_138
AHR_19
NC_72
NC_148
NC_29
NC_116
NC_151
NC_147
Barr Footer: ArcGIS 10.4.1, 2017-09-21 11:51 File: \\barr.com\gis\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_7_1_Cornelia_Drainage_Basins.mxd User: rcs2ComprehensiveWater ResourcesManagement PlanCity of Edina, Minnesota
FIGURE 7.1
0 1,200
Feet
!;N
Lake Cornelia/Lake Edina/Adam's Hill Drainage Basin
Subwatershed
Streets and Highways
Creek/Stream
City of Edina Boundary
Lake/Wetland
Imagery Source: MnGeo; 2016
LAKE CORNELIA/LAKE EDINA/ADAM'S HILL MAJOR WATERSHEDS
62
100
456717
456753
456731
Wooddale Ave Parklawn Ave Brookview Ave W 70th St
Lake Cornelia - North
Lake Edina
Lake Cornelia - South
Adam's Hill (Richfield)
RichfieldRichfield
MinneapolisMinneapolis
N o r t h B r anch N i n eMileCreek
Lake Edina
South Lake Cornelia
North Lake Cornelia
Barr Footer: ArcGIS 10.4.1, 2017-09-21 14:38 File: I:\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_7_2_Cornelia_Major_Watersheds.mxd User: EMAComprehensiveWater ResourcesManagement PlanCity of Edina, MinnesotaFIGURE 7.2
0 1,200
Feet
!;N
Lake Cornelia/Lake Edina/Adam's Hill Drainage Basin
Major Watershed
Adam's Hill (Richfield)
Lake Cornelia - North
Lake Cornelia - South
Lake Edina
Subwatershed
Streets and Highways
Creek/Stream
City of Edina Boundary
Lake/Wetland
Imagery Source: MnGeo; 2016
LAKE CORNELIA/LAKE EDINA/ADAM'S HILL PONDMAJOR WATERSHEDS
Adam's HillPond
City of Edina 2018 Comprehensive Water Resources Management Plan
7-32
Figure 7.3 Lake Cornelia/Lake Edina/Adam's Hill Hydraulic Model Results
This is a large drawing (34x44).
Due to the paper and size and file size, this figure is included as a stand-alone PDF.
NC_5
NC_6
NC_2 NC_30
NC_62NC_78
NC_72
NC_88
NC_4
SC_3
LE_38
LE_1
LE_44
NC_135
SC_2
LE_54LE_51
NC_130
SC_1
SC_1
NC_3
NC_3
RichfieldRichfield
MinneapolisMinneapolis
NineMileCreek
Barr Footer: ArcGIS 10.4.1, 2017-09-21 08:24 File: \\barr.com\gis\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_7_4_Lk_Cornelia_Water_Quality.mxd User: rcs2LAKE CORNELIA/LAKE EDINAWATER QUALITY MODELING RESULTSComprehensive Water ResourceManagement PlanCity of Edina, Minnesota
FIGURE 7.4
1,200 0 1,200Feet
!;N
400 0 400Meters
Percent TP Removal in Water Body*This number represents the percent of the total annual massof phosphorus entering the water body that is removed.
Cumulative TP Removal in Watershed*This number represents the percent of the total annual massof phosphorus entering the watershed and upstream watershedsthat is removed in the pond and all upstream ponds.
*Data based on results of 2003 P8 modeling.
0 - 25% (Poor/No Treatment)
25 - 40% (Moderate Removal)
40 - 60% (Good Removal)
60 - 100% (Excellent Removal)
0 - 25% (Poor/No Treatment)
25 - 40% (Moderate Removal)
40 - 60% (Good Removal)
60 - 100% (Excellent Removal)
Imagery Source: USDA 2016 NAIP via MnGeo
Flow Direction
City of Edina 2018 Comprehensive Water Resources Management Plan
8-1
8.0 Nine Mile Creek South
8.1 General Description of Drainage Area
Figure 8.1 depicts the Nine Mile Creek—South drainage basin, located in the southeast portion of Edina.
The drainage basin encompasses approximately 1,177 acres that ultimately drain to the North Fork of
Nine Mile Creek between West 70th Street and the south Edina City limits.
8.1.1 Drainage Patterns
The stormwater system within this drainage area comprises storm sewers, ditches, overland flow paths,
wetlands, and ponding basins. The Nine Mile Creek—South drainage basin has been divided into several
major watersheds based on the drainage patterns. These major watersheds are depicted on Figure 8.2.
Each major watershed has been further delineated into many subwatersheds. The naming convention for
each subwatershed is based on the major watershed where it is located Table 8.1 lists each major
watershed and the associated subwatershed naming convention.
Table 8.1 Major Watersheds within the Nine Mile Creek—South Drainage Basin
Major Watershed
Subwatershed Naming
Convention Number of Subwatersheds Drainage Area (acres)
Centennial Lakes CL_## 42 208
South Pond SP_## 19 211
Nine Mile South NMS_## / EdCrk## 109 758
8.1.1.1 Centennial Lakes
The 208-acre Centennial Lakes watershed is located in southeast Edina and drains to Centennial Lakes.
The watershed is bordered by West 69th Street on the north, West 78th Street on the south, France Avenue
on the west, and York Avenue on the east. Runoff from France Avenue between West 69th Street and just
south of Gallagher Drive drains to Centennial Lakes. France Avenue drainage south of Gallagher Drive
flows to the South Pond. The watershed is characterized by mainly commercial and high-density
residential land use. Centennial Lakes spans 9.5 acres, stretching south from Gallagher Drive to Minnesota
Drive, and receives runoff from the direct watershed as well as flow from Adam’s Hill Pond (10 cfs). The
normal elevation of Centennial Lakes is 838 feet, controlled by a weir structure that discharges to the
South Pond.
8.1.1.2 South Pond (Border Basin)
The South Pond is located on the border between Edina and Bloomington, just west of the intersection of
Minnesota Drive and West 77th Street. The watershed draining to the South Pond encompasses 211 acres.
The land use within the watershed is entirely commercial and industrial, thus highly impervious. In
addition to the runoff from the direct watershed, the South Pond receives flow from Centennial Lakes. The
City of Edina 2018 Comprehensive Water Resources Management Plan
8-2
South Pond was categorized as a Type 4 wetland in the wetland inventory, a shallow (0.5 to 3 foot),
marshy wetland with vegetation such as grasses, cattails, and bulrushes. The normal elevation of the
South Pond is controlled at 814.5 feet by a weir structure. Discharge from the South Pond flows west
through the storm sewer system along Viking Drive and eventually discharges to the North Fork of Nine
Mile Creek.
8.1.1.3 Nine Mile South
The Nine Mile South watershed encompasses the area that drains to the North Fork of Nine Mile Creek
between West 70th Street and the southern border of Edina. The 758-acre watershed extends to Cahill
Road to the west, France Avenue to the east, West 66th Street to the north, and West 78th Street to the
south. The watershed is characterized by multiple land uses, including residential, commercial, industrial,
highway, and golf course. The portion of the watershed west of the North Fork of Nine Mile Creek is
almost entirely commercial and industrial, thus highly impervious. The northern portion is low-density
residential. The southeast portion consists mainly of high-density residential buildings, a large commercial
and industrial area, and the Fred Richards Golf Course. The golf course is characterized by a series of
ponding basins that receive runoff from an area of approximately 183 acres. Discharge from the golf
course ponds flows southward through a storm sewer system located between the 4700 and 4660 West
77th Street properties. This system connects to the trunk system that flows westward from the South Pond
to the North Fork of Nine Mile Creek.
8.2 Stormwater System Results
8.2.1 Hydrologic/Hydraulic Modeling Results
The 10- and 1-percent-annual-chance flood analyses were performed for the Nine Mile Creek- South
drainage basin. The 10-percent-annual-chance analysis was based on a ½-hour storm with 1.65 inches of
rain. The 1-percent-annual-chance analysis was based on a 24-hour storm event with 7.47 inches of rain
and on a 10-day snowmelt event with 7.2 inches of runoff; the higher resulting flood level of the two
events was chosen for the 1-percent-annual-chance analysis Table 8.2 presents the watershed
information and the results for the 10- and 1-percent-annual-chance hydrologic analyses. A more detailed
description of the stormwater system analysis is provided in Section 4.1.3.
The results of the 10- and 1-percent-annual-chance hydraulic analyses for the Nine Mile Creek—South
drainage basin are summarized in Table 8.3.
Figure 8.3 illustrates the results of the 10- and 1-percent-annual-chance hydraulic analyses. The figure
depicts the boundaries of the drainage areas, subwatershed boundaries, the modeled storm sewer
network, surcharge conditions for the XP-SWMM nodes (typically manholes), and the flood-prone areas
identified in the modeling analyses.
Figure 8.3 illustrates that several XP-SWMM nodes within the Nine Mile Creek—South drainage basin are
predicted to surcharge during both the 10- and 1-percent-annual-chance events. This means that in any
year there is a greater than 10 percent probability that the system will be overburdened and unable to
City of Edina 2018 Comprehensive Water Resources Management Plan
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meet the desired level of service at these locations. These manholes and catch basins are more likely to
become inundated during the smaller, more frequent storm events of various durations.
To evaluate the level of protection of the stormwater system within the Nine Mile Creek—South drainage
basin, the 1-percent-annual-chance flood elevations for the ponding basins and depressed areas were
compared to the low elevations of structures surrounding each basin.. The areas predicted to potentially
flood and threaten structures during the 1-percent-annual-chance storm event are shown on Figure 8.3.
Discussion and recommended improvement considerations for these areas are included in Section 8.3.
8.2.2 Water Quality Modeling Results
The effectiveness of the stormwater system in removing stormwater pollutants such as phosphorus was
analyzed using the P8 water quality model. The P8 model simulates the hydrology and phosphorus loads
introduced from each pond’s watershed and the transport of phosphorus throughout the stormwater
system. A more detailed description of the stormwater system analysis is provided in Section 4.1.3.
Figure 8.4 depicts the results of the water quality modeling for the Nine Mile Creek—South drainage
basin. The figure shows the fraction of total phosphorus removal for each water body as well as the
cumulative total phosphorus removal in the watershed. Implementation Considerations
8.3 Implementation Considerations
The 2017 XP-SWMM hydrologic and hydraulic modeling analyses and 2003 P8 water quality analysis
helped identify locations throughout the watershed where improvements to the City’s stormwater
management system may be warranted. The following sections discuss potential improvement options
identified as part of the modeling analyses. As opportunities to address identified flooding issues and
improve water quality arise (e.g., street reconstruction projects or public facilities improvements), the City
will use a comprehensive approach to stormwater management. This approach will include consideration
of infiltration or volume retention practices to address flooding and/or improve water quality, reduction of
impervious surfaces, increased storm sewer capacity where necessary to alleviate flooding, construction
and/or expansion of water quality basins, and implementation of other stormwater BMPs to reduce
pollutant loading to downstream waterbodies.
8.3.1 Flood Protection Projects
The 2017 hydrologic and hydraulic modeling analyses identified several locations within the Nine Mile
Creek—South drainage basin where the 1-percent-annual-chance level of protection is not provided by
the current stormwater system. The problem areas identified in 2017 are discussed below.
As part of the 2017 modeling analyses, potential corrective measures were identified for problem areas.
These preliminary corrective measures are also discussed below. As the City evaluates flooding issues and
potential system modifications in these areas, other potential modifications, including (but not limited to)
implementation of volume-retention practices, increases in conveyance capacity, and/or stormwater
infiltration (where soils are conducive) will be given consideration.
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The 2003 hydrologic and hydraulic modeling analyses identified several locations within the Nine Mile
Creek –South drainage basin where the 1-percent-annual-chance level of protection was not provided by
the stormwater system, based on TP-40 precipitation frequency estimates. The discussions related to
those areas have been carried over to Appendix C of this plan, along with a short summary of what has
been done in those areas since 2003.
8.3.1.1 West 70th Street and West Shore Drive (NMS_38 and NMS_50)
Approximately 42 acres drain to the local depression at the intersection of West 70th Street and West
Shore Drive. A 36-inch storm sewer drains this intersection to the west to approximately TH 100, where
the storm sewer size increases to 42-inch and 48-inch pipes and eventually drains to Nine Mile Creek.
Water pools in this intersection until it reaches the surface overflow elevation of approximately 869.4 feet
(according to LiDAR data) and flows west. The 1-percent-annual-chance flood level is determined by the
24-hour precipitation event and is 869.4 feet. Four principle structures (4701 West 70th Street, and 6905
through 6913 West Shore Drive) are potentially impacted at this intersection and the depth of flooding is
approximately 2.0 feet.
Additional flow capacity is needed in the West 70th Street system. Additionally, in conjunction with future
road reconstruction, a second option would be to lower the high elevation along West 70th Street to the
west of the intersection. This would allow for the pooled water to overflow at a lower elevation and limit
the peak flooding elevation and extents. Another potential option to reduce flood risk at this intersection
is to divert high flows within the existing storm sewer system along West 70th Street southward to the low
area in Arnesen Acres Park (LE_54). Further analysis is warranted.
8.3.1.2 Centennial Lakes (CL_1)
Centennial Lake is located in the southeast portion of Edina, east of France Avenue and north of
Interstate 494 (I-494) within Centennial Lakes Park. Approximately 208 acres drain to Centennial Lake.
Water levels in the lake are controlled by a 25-foot long weir structure at elevation 838.04 feet, with a 60-
inch pipe that conveys runoff to the Border Basin (SP_1) and eventually to the North Fork of Nine Mile
Creek. Modeling results indicate that during the 1-percent-annual-chance 24-hour storm event the peak
flood level is 842.3 feet.
The storage options around this area are limited and the overall capacity of the outlet could be enlarged
to pass more water through the system. However, current flood levels downstream are already elevated
and increasing drainage capacity from Centennial Lakes Park may cause further impacts downstream. It is
recommended that a survey be conducted to determine low entry elevations for structures adjacent to
Centennial Lake. Given the existing flood issues downstream of Centennial Lakes and limited potential for
upstream storage, flood-proofing may be the most appropriate strategy to address flood risk in this area.
It appears that the structures along the north part of Centennial Lakes have a minimal number of entry
locations directly adjacent to the lake; flood proofing may not be necessary in this area. Toward the south
end of Centennial Lakes, there are several structures with low entries facing the lake. A 3-foot floodwall
around the lake would provide approximately 1 foot of freeboard above the 1-percent-annual-chance
flood level.
City of Edina 2018 Comprehensive Water Resources Management Plan
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Additional storage could also be created in Centennial Lakes by drawing the lake down during dry periods
in anticipation of storm events. This could be accomplished in a number of ways. The current weir
structure could be modified to include a small orifice below the existing weir crest. The orifice could be
fitted with a gate valve for periodic use if preferred. Alternatively, the valve could be fitted with automatic
controls that are based on weather prediction. Another approach could be periodically pumping the lake
level down using a small lift station near the outlet, which could be controlled manually or automatically
based on weather prediction.
8.3.2 Construction/Upgrade of Water Quality Basins
The 2003 P8 modeling analysis indicated that under average conditions the annual removal of total
phosphorus from several ponds in the Nine Mile Creek—South drainage area was below the desired
60 percent removal rate. For ponds with total phosphorus removal below 60 percent, the permanent pool
storage volume was analyzed to determine whether additional capacity was necessary. The ponds with
deficiencies in total phosphorus removal and permanent pool volume are listed below (and are also
summarized in Appendix D), with recommended pond upgrades.
Construction of new or expansion of existing water quality basins is one way to increase pollutant removal
prior to stormwater reaching downstream waterbodies. Many additional techniques are available to
reduce pollutant loading, including impervious surface reduction or disconnection, implementation of
infiltration or volume-retention BMPs, installation of underground stormwater treatment structures and
sump manholes, and other good housekeeping practices such as street sweeping. As opportunities arise,
the City will consider all of these options to reduce the volume and improve the quality of stormwater
runoff.
A large portion of stormwater runoff from the Nine Mile Creek—South drainage basin drains through the
storm sewer system directly to the North Fork of Nine Mile Creek without any water quality treatment
prior to entering the creek. The large area draining directly to the Creek (approximately 500 acres) is
depicted on Figure 8.4. To remove pollutants and improve the quality of the discharge to Nine Mile
Creek, it is recommended that the City consider installation of a water quality treatment basin upstream of
the discharge location at West 77th Street and TH 100 (discussed in additional detail below), as well as
other water quality treatment techniques as opportunities arise.
8.3.2.1 West 77th Street and TH 100
The southwest portion of the Nine Mile Creek—South drainage basin is an industrial, highly impervious
area. Stormwater from this area is collected via storm sewer and discharged to the North Fork of Nine
Mile Creek without any water quality treatment. Construction of a water quality basin in the southwest
quadrant of the intersection of TH 100 and West 77th Street is being considered to provide some pollutant
removal prior to discharge. The basin will receive runoff from an area of approximately 50 acres along
Industrial Boulevard. Based on the MPCA-recommended design criteria for permanent pool storage in
detention basins, the total required dead storage volume for this basin is 4.4 acre-feet.
City of Edina 2018 Comprehensive Water Resources Management Plan
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8.3.2.2 NMS_76
Pond NMS_76 is located on the east side of the Fred Richards Golf Course, just northwest of the
intersection of West 76th Street and Parklawn Avenue. The pond receives runoff from an area of
approximately 120 acres. The pond outlets to Pond NMS_104 via a 108-inch “round equivalent” arch pipe.
The pond is a Type 5 wetland and was assumed to have an average depth of 4 feet. Based on this
assumed depth and the 2-foot topographic data, the permanent pool storage volume was estimated to
be 4.4 acre-feet in 2004. According to NURP pond design standards, this storage volume is inadequate. In
2008, the City removed approximately 0.9 acre-feet of sediment from Pond NMS_76. To upgrade the
pond to meet the NURP standards, an additional 1.6 acre-feet of dead storage volume is recommended.
8.3.2.3 NMS_104
Pond NMS_104 is located along the southeast border of the Fred Richards Golf Course, just north of the
parking lot for the Pentagon Park office complex. In addition to runoff from adjacent parking lots, this
detention basin receives discharge from Pond NMS_76. Based on the wetland inventory, the pond is a
Type 5 wetland and was assumed to have an average depth of 4 feet. Pond NMS_104 is connected to the
downstream pond NMS_72 by two 30-inch equalizer pipes. According to MPCA recommendations, there
is not an adequate amount of permanent pool storage in this basin. It is recommended that an additional
0.2 acre-feet of dead storage volume be provided.
8.3.2.4 NMS_72 and NMS_74
Ponds NMS_72 and NMS_74 are located within the Fred Richards Golf Course, connected by a 36-inch
equalizer pipe. Pond NMS_72 is upstream of NMS_74 and receives discharge from Pond NMS_79 and
NMS_104, as well as runoff from the 7-acre direct watershed. Pond NMS_74 receives discharge from
NMS_72 in addition to runoff from the 6.5-acre direct watershed. Based on the wetland inventory, both
ponds are Type 5 wetlands and were assumed to have an average depth of 4 feet. Considering this depth
and the 2-foot topographic information, the permanent pool storage volume of each pond is greater than
the MPCA-recommended volume for detention ponds. However, because water quality modeling results
indicate that the total phosphorus removal in Ponds NMS_72 and NMS_74 is below desired levels, it is
recommended that the depth of the ponds be increased to improve removal efficiency.
8.3.2.5 SP_1 (South Pond/Border Basin)
Pond SP_1 is located on the border between Edina and Bloomington, just west of the intersection of
Minnesota Drive and West 77th Street. In addition to stormwater runoff from a large, highly impervious
215-acre watershed, Pond SP_1 receives discharge from Centennial Lakes. The water level in Pond SP_1 is
controlled by a weir structure. Discharge from the pond flows to the North Fork of Nine Mile Creek on the
west side of TH 100, just south of the West 77th Street crossing. The pond is a Type 4 wetland and was
assumed to have an average depth of 2 feet. Based on this depth and the pond area from the 2-foot
topographic data, the existing dead storage volume was calculated to be 6.8 acre-feet, which is less than
the MPCA-recommended permanent pool storage volume for this basin. It is recommended that an
additional 19.6 acre-feet of dead storage volume be provided to meet the MPCA design criteria for
detention basins and improve the efficiency of total phosphorus removal.
Table 8.2
Watershed Modeling Results for Subwatersheds in the Nine Mile Creek - South Drainage Area
1 The 1%-Annual-Chance (100-Year) 10-day snowmelt event is defined as 7.2 inches of runoff
Watershed ID
Total Area
(ac)
% Impervious
Area
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
CL_1 56.0 69 446 29.0 10.6 33.6 201 15.2
CL_10 0.9 50 10 0.4 0.2 0.6 5 0.2
CL_11 1.4 70 17 0.7 0.3 0.9 9 0.4
CL_12 1.5 35 16 0.6 0.3 0.9 8 0.3
CL_13 8.4 66 64 4.3 1.6 5.0 29 2.3
CL_14 3.8 42 31 1.8 0.7 2.3 14 0.9
CL_15 3.0 27 25 1.2 0.6 1.8 10 0.5
CL_16 3.9 67 38 2.0 0.7 2.4 18 1.1
CL_17 2.6 75 27 1.4 0.5 1.6 14 0.8
CL_18 1.9 65 22 1.0 0.4 1.1 12 0.5
CL_19 1.6 46 17 0.7 0.3 0.9 9 0.3
CL_1a 1.2 50 12 0.6 0.2 0.7 6 0.3
CL_20 11.7 50 89 5.4 2.2 7.0 37 2.7
CL_21 1.9 75 21 1.0 0.4 1.1 11 0.5
CL_22 2.7 75 23 1.4 0.5 1.6 11 0.8
CL_23 3.8 75 32 2.0 0.7 2.3 15 1.1
CL_25 5.0 72 48 2.7 0.9 3.0 24 1.4
CL_27 9.5 80 54 5.2 1.8 5.7 25 2.8
CL_3 8.2 50 66 3.8 1.5 4.9 28 1.9
CL_35 2.9 80 33 1.6 0.6 1.7 18 0.9
CL_38 5.3 51 48 2.5 1.0 3.1 21 1.2
CL_4 3.3 46 34 1.5 0.6 2.0 17 0.7
CL_48 8.9 80 74 4.9 1.7 5.3 36 2.7
CL_49 4.3 80 39 2.4 0.8 2.6 19 1.3
CL_5 7.5 44 53 3.4 1.4 4.5 22 1.6
CL_50 3.8 80 34 2.1 0.7 2.3 16 1.1
CL_51 5.2 80 48 2.9 1.0 3.1 24 1.5
CL_52 1.6 80 17 0.9 0.3 1.0 9 0.5
CL_53 4.6 80 33 2.5 0.9 2.8 15 1.4
CL_53a 1.1 80 10 0.6 0.2 0.7 5 0.3
CL_53b 2.0 80 20 1.1 0.4 1.2 10 0.6
CL_54 3.2 72 35 1.7 0.6 1.9 18 0.9
CL_55 5.8 80 48 3.2 1.1 3.5 23 1.7
CL_56 4.6 79 45 2.5 0.9 2.7 23 1.4
CL_57 3.2 58 29 1.7 0.6 1.9 14 0.9
CL_58 0.9 80 11 0.5 0.2 0.6 6 0.3
CL_59 0.7 80 8 0.4 0.1 0.4 4 0.2
CL_60 1.5 80 15 0.8 0.3 0.9 8 0.4
CL_61 3.4 80 31 1.9 0.7 2.1 15 1.0
CL_62 0.9 80 9 0.5 0.2 0.6 4 0.3
CL_8 1.8 50 19 0.8 0.3 1.1 9 0.4
CL_9 2.4 50 19 1.1 0.5 1.4 8 0.5
EdCrk17 7.8 73 91 4.5 1.5 4.7 50 2.5
EdCrk18 4.8 75 55 2.8 0.9 2.9 30 1.6
EdCrk19 4.3 53 45 2.4 0.8 2.6 24 1.3
EdCrk20 23.4 66 163 13.5 4.4 14.0 80 7.5
NMS_10 4.7 76 44 2.8 0.9 2.8 23 1.6
NMS_100 3.4 70 34 2.0 0.6 2.1 18 1.1
NMS_101 2.4 75 21 1.3 0.4 1.4 11 0.7
NMS_102 2.8 20 25 1.4 0.5 1.7 13 0.7
NMS_103 8.2 19 60 4.4 1.6 4.9 30 2.3
NMS_104 6.3 57 63 3.6 1.2 3.8 33 2.0
NMS_105 2.8 75 26 1.6 0.5 1.7 13 0.9
NMS_106 3.5 75 32 1.9 0.7 2.1 16 1.0
NMS_107 3.2 74 30 1.8 0.6 1.9 15 1.0
NMS_108 12.8 80 74 7.3 2.4 7.7 36 4.0
NMS_11 4.0 80 30 2.4 0.8 2.4 15 1.3
NMS_12 4.4 80 33 2.6 0.8 2.6 16 1.4
NMS_13 10.9 80 81 6.3 2.1 6.6 40 3.5
NMS_14 11.1 69 79 6.1 2.1 6.7 38 3.3
Watershed Information 1%-Annual-Chance (100-Year)1%-Annual-Chance (100-Year)10%-Annual-Chance (10-Year)
24-Hour Precipitation Event 10-day Snowmelt Event1 24-Hour Precipitation Event
Table 8.2
Watershed Modeling Results for Subwatersheds in the Nine Mile Creek - South Drainage Area
1 The 1%-Annual-Chance (100-Year) 10-day snowmelt event is defined as 7.2 inches of runoff
Watershed ID
Total Area
(ac)
% Impervious
Area
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Watershed Information 1%-Annual-Chance (100-Year)1%-Annual-Chance (100-Year)10%-Annual-Chance (10-Year)
24-Hour Precipitation Event 10-day Snowmelt Event1 24-Hour Precipitation Event
NMS_15 7.7 75 65 4.3 1.5 4.6 33 2.3
NMS_16 9.0 80 67 5.1 1.7 5.4 33 2.8
NMS_18 5.8 75 49 3.2 1.1 3.5 24 1.7
NMS_19 1.2 80 11 0.7 0.2 0.7 6 0.4
NMS_20 5.4 75 50 3.1 1.0 3.2 26 1.7
NMS_21 3.1 75 28 1.6 0.6 1.8 13 0.9
NMS_22 8.7 77 79 5.1 1.6 5.2 41 2.8
NMS_23 0.5 29 5 0.3 0.1 0.3 3 0.2
NMS_24 3.3 25 24 1.5 0.6 2.0 11 0.7
NMS_25 6.4 74 45 3.4 1.2 3.8 20 1.8
NMS_26 3.2 52 31 1.5 0.6 1.9 14 0.8
NMS_27 17.9 79 118 10.2 3.4 10.7 58 5.6
NMS_28 23.0 68 155 12.5 4.3 13.8 73 6.7
NMS_29 12.2 68 100 6.3 2.3 7.3 46 3.3
NMS_30 10.2 75 48 5.6 1.9 6.1 22 3.0
NMS_31 17.0 78 105 9.8 3.2 10.2 52 5.4
NMS_31a 2.0 75 22 1.1 0.4 1.2 12 0.6
NMS_32 8.7 74 62 5.1 1.6 5.2 31 2.8
NMS_33 2.3 73 26 1.3 0.4 1.4 14 0.7
NMS_34 0.6 71 7 0.4 0.1 0.4 4 0.2
NMS_35 0.6 63 6 0.3 0.1 0.3 3 0.2
NMS_36 1.2 53 14 0.7 0.2 0.7 8 0.4
NMS_37 10.4 71 91 5.5 2.0 6.2 44 2.9
NMS_38 24.2 25 129 10.6 4.5 14.5 53 5.0
NMS_39 7.0 65 48 3.9 1.3 4.2 23 2.1
NMS_4 3.8 77 35 2.2 0.7 2.3 18 1.3
NMS_40 21.8 55 165 11.2 4.1 13.0 78 5.8
NMS_41 6.9 31 65 3.2 1.3 4.2 32 1.6
NMS_42 3.9 80 25 2.1 0.7 2.3 12 1.2
NMS_43 3.4 81 34 2.0 0.6 2.0 18 1.1
NMS_44 5.0 37 56 2.3 0.9 3.0 29 1.1
NMS_45 6.7 75 59 3.7 1.3 4.0 28 2.0
NMS_46 7.2 25 68 3.2 1.4 4.3 34 1.6
NMS_47 14.1 25 93 6.2 2.7 8.4 40 3.0
NMS_48 4.6 25 38 2.1 0.9 2.8 18 1.0
NMS_49 11.2 25 90 5.0 2.1 6.7 42 2.4
NMS_5 2.0 75 22 1.2 0.4 1.2 12 0.7
NMS_50 17.9 25 104 7.9 3.4 10.7 44 3.7
NMS_51 14.6 75 71 7.8 2.7 8.8 31 4.1
NMS_52 5.7 20 42 2.7 1.1 3.4 20 1.3
NMS_53 3.5 63 34 2.0 0.7 2.1 18 1.1
NMS_54 1.3 48 14 0.6 0.2 0.8 8 0.3
NMS_55 9.0 62 74 4.8 1.7 5.4 36 2.5
NMS_56 2.9 80 29 1.6 0.6 1.8 14 0.9
NMS_57 11.4 75 61 6.4 2.1 6.9 29 3.5
NMS_58 5.8 75 51 3.2 1.1 3.5 25 1.7
NMS_59 1.3 64 15 0.7 0.2 0.8 8 0.4
NMS_6 13.5 77 85 7.3 2.5 8.1 39 3.9
NMS_60 1.6 76 17 0.9 0.3 1.0 9 0.5
NMS_61 0.8 75 9 0.4 0.2 0.5 5 0.2
NMS_62 6.6 76 40 3.6 1.2 3.9 19 1.9
NMS_63 4.9 64 44 2.7 0.9 2.9 22 1.4
NMS_64 17.7 75 99 9.7 3.3 10.6 46 5.2
NMS_65 2.4 75 21 1.4 0.4 1.4 11 0.8
NMS_66 4.5 43 34 2.0 0.8 2.7 14 1.0
NMS_67 1.9 52 19 0.9 0.4 1.1 9 0.4
NMS_68 2.5 25 26 1.0 0.5 1.5 12 0.4
NMS_69 4.5 42 40 2.1 0.9 2.7 18 1.0
NMS_7 16.1 78 84 9.1 3.0 9.7 40 4.9
NMS_70 11.6 51 69 5.4 2.2 7.0 28 2.6
Table 8.2
Watershed Modeling Results for Subwatersheds in the Nine Mile Creek - South Drainage Area
1 The 1%-Annual-Chance (100-Year) 10-day snowmelt event is defined as 7.2 inches of runoff
Watershed ID
Total Area
(ac)
% Impervious
Area
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Watershed Information 1%-Annual-Chance (100-Year)1%-Annual-Chance (100-Year)10%-Annual-Chance (10-Year)
24-Hour Precipitation Event 10-day Snowmelt Event1 24-Hour Precipitation Event
NMS_71 4.4 78 30 2.4 0.8 2.6 14 1.3
NMS_72 7.3 12 48 3.9 1.4 4.3 23 2.1
NMS_73 6.7 50 53 3.3 1.3 4.0 24 1.6
NMS_74 6.5 19 44 3.6 1.2 3.9 22 1.9
NMS_75 5.3 68 48 3.1 1.0 3.2 25 1.7
NMS_76 10.8 39 91 5.8 2.0 6.5 46 3.1
NMS_77 7.2 39 50 3.3 1.4 4.3 21 1.6
NMS_78 2.5 50 21 1.2 0.5 1.5 9 0.6
NMS_79 6.6 9 37 3.6 1.2 4.0 18 1.9
NMS_8 2.9 75 32 1.6 0.6 1.7 16 0.8
NMS_80 3.5 60 33 1.7 0.7 2.1 16 0.9
NMS_81 11.5 55 92 5.6 2.2 6.9 41 2.9
NMS_82 7.8 25 61 3.1 1.5 4.7 24 1.4
NMS_83 3.6 25 29 1.5 0.7 2.1 13 0.7
NMS_84 11.8 12 64 5.9 2.2 7.1 29 2.9
NMS_85 3.1 74 18 1.7 0.6 1.8 9 0.9
NMS_86 3.1 25 30 1.3 0.6 1.9 14 0.6
NMS_87 1.1 25 10 0.4 0.2 0.6 5 0.2
NMS_88 3.6 26 31 2.0 0.7 2.2 16 1.1
NMS_89 7.2 69 50 3.8 1.3 4.3 22 2.0
NMS_90 6.7 50 58 3.1 1.3 4.0 25 1.5
NMS_91 4.0 73 34 2.1 0.8 2.4 16 1.1
NMS_92 6.3 80 47 3.5 1.2 3.8 22 1.9
NMS_93 5.1 70 45 2.8 1.0 3.0 22 1.5
NMS_94 1.3 25 13 0.7 0.2 0.8 7 0.3
NMS_95 8.0 80 65 4.7 1.5 4.8 33 2.6
NMS_96 5.8 80 42 3.4 1.1 3.5 21 1.9
NMS_97 9.4 80 71 5.5 1.8 5.6 35 3.1
NMS_98 6.8 25 45 3.0 1.3 4.0 20 1.4
NMS_99 4.4 35 45 2.1 0.8 2.6 23 1.0
SP_1 89.8 80 312 51.8 15.3 53.9 147 28.4
SP_10 3.7 77 30 2.2 0.7 2.2 15 1.2
SP_11 5.6 80 34 3.1 1.0 3.3 16 1.7
SP_12 3.5 75 29 1.9 0.7 2.1 13 1.0
SP_13 4.6 80 38 2.6 0.9 2.7 19 1.4
SP_14 0.9 78 9 0.5 0.2 0.5 5 0.3
SP_15 4.6 75 49 2.5 0.9 2.7 26 1.3
SP_16 7.7 79 42 4.2 1.4 4.6 19 2.2
SP_17 7.0 80 40 4.2 1.3 4.2 20 2.3
SP_18 8.5 79 91 4.6 1.6 5.1 48 2.5
SP_2 2.0 80 23 1.1 0.4 1.2 12 0.6
SP_3 3.8 80 38 2.1 0.7 2.3 19 1.1
SP_4 2.6 75 27 1.4 0.5 1.6 14 0.8
SP_5 11.6 80 100 6.9 2.2 7.0 51 3.8
SP_6 28.4 80 167 16.5 5.3 17.1 82 9.1
SP_7 14.9 80 130 8.5 2.8 9.0 66 4.6
SP_8 1.2 80 12 0.7 0.2 0.7 6 0.4
SP_9 10.4 75 74 5.8 2.0 6.2 36 3.2
SP_9a 0.5 76 6 0.3 0.1 0.3 3 0.2
Table 8.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - South
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1005 823.0 821.0
1006 822.8 820.6
1010 822.7 820.3
1011 822.7 820.1
1012 822.7 820.0
1014 822.7 819.9
1015 822.7 819.8
1016 822.7 819.7
1017 822.7 819.8
1019 822.7 820.9
1020 823.1 822.1
1021 822.7 820.7
1025 street 822.7 819.5
1029 822.7 819.3
1222 838.3 838.3
1227 831.8 831.8
1229 830.6 830.6
1230 829.6 829.2
1234 828.3 827.9
1237 827.5 824.8
1238 827.4 824.7
1239 829.9 829.9
1239$I 827.3 824.5
1242 829.2 828.9
1245 833.8 832.9
1248 828.8 826.1
1250 828.2 824.6
1254 823.5 820.0
1492 847.1 843.7
1493 845.1 842.7
1498 842.3 840.4
1500 851.7 847.5
1503 845.2 841.5
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
Table 8.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - South
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
1513 840.8 837.7
1515 837.3 832.8
1516 836.6 831.0
1517 835.8 830.8
1518 834.9 830.8
1519 833.7 830.9
1520 833.2 831.2
1521 835.8 835.6
1522 834.6 832.9
1523 833.8 831.7
1528 842.0 840.0
1529 837.8 836.9
1530 836.0 835.5
1531 834.7 833.9
1534 861.6 855.9
1536 861.2 855.2
1538 861.0 854.5
1539 857.9 852.3
1540 856.5 851.4
1542 854.1 849.4
1544 849.8 846.9
1545 844.5 841.2
1547 863.4 856.1
1549 861.8 853.5
1550 858.8 852.7
1683 853.6 846.3
1685 853.1 846.1
1696 839.3 839.0
1713 844.1 840.8
1718 861.8 856.0
1719 861.4 856.2
1726 863.9 857.7
1840 street 853.7 847.9
Table 8.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - South
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
1841 854.0 849.7
1842 854.3 850.9
1843 854.9 852.7
1847 827.7 826.9
1851 street 831.0 828.8
1852 833.1 831.5
1901 838.8 836.5
1902 842.2 839.0
1905 824.1 823.2
1907 821.9 819.3
1910 827.1 826.0
1913 827.8 827.4
2069 872.9 872.6
2102 882.6 881.9
2106 821.9 819.4
2108 821.9 819.6
2256 857.2 850.4
2258 854.7 847.2
2259 853.2 845.8
2260 853.6 846.1
2260a 863.7 862.7
2262 852.4 845.4
2263 851.1 845.0
2264 849.6 844.4
2361 847.6 843.7
2362 846.5 843.1
2363 844.9 842.3
2364 843.5 840.5
2370 859.3 859.0
2372 860.9 856.5
2373 862.4 862.0
2374 862.4 862.0
2376 868.8 868.7
Table 8.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - South
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
2379 867.0 866.2
2383 870.5 870.4
2389 853.1 846.0
2442 832.7 826.2
2446 845.6 845.4
2448 821.9 819.3
2584 830.9 830.6
2587 842.3 836.0
2588 840.7 835.6
2590 839.1 832.8
2591 833.5 827.8
2737 822.7 820.7
2738 822.7 820.7
2739 822.7 820.7
2744 822.9 821.1
2746 828.3 826.9
2748 824.7 822.2
2752 858.3 855.6
2753 858.2 853.2
2755 858.6 853.7
2784 836.5 836.0
2788 822.7 820.7
2789.1 822.7 820.7
2820 street 827.7 824.7
2821 829.3 827.9
2860 860.6 856.8
2861 860.6 857.8
2862 860.8 858.6
2863 860.8 859.0
2864 860.9 859.6
2866 833.1 827.4
2882 822.7 820.2
2884.1 822.1 819.1
Table 8.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - South
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
2886 828.0 827.2
2887 828.1 827.4
2889 828.8 827.9
2892 829.7 828.9
2893 829.7 829.0
2894 829.7 829.0
2896 845.5 845.3
2897 844.6 841.9
2898 843.9 841.9
2899 843.6 841.9
2909 832.1 830.4
2910 831.6 830.7
2911 833.7 833.2
2932 828.4 828.3
2933 832.0 831.4
2934 834.9 834.5
2973.1 822.7 819.3
2974.1 822.7 819.3
898 866.7 866.5
899 866.5 866.3
901 863.4 863.0
903 859.0 854.9
935 863.6 862.1
936 855.7 855.3
937 850.6 849.9
940 860.4 860.4
941 847.7 847.4
942 846.7 845.3
944 846.4 844.7
947 842.6 840.2
948 836.2 834.8
951 844.8 844.0
955 870.1 868.4
Table 8.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - South
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
956 862.8 862.6
958 858.6 858.4
959 846.2 845.8
968 834.5 833.3
972 832.1 831.8
973 831.3 830.4
975 829.8 829.1
976 828.8 828.0
978 827.0 825.8
982 832.6 832.3
983 836.2 835.7
986 826.1 824.9
987 826.1 824.8
990 826.1 825.7
992 828.0 826.5
993 829.0 826.8
996 826.7 826.5
CL_1 pond 838.0 842.3 4.3 840.4 2.4
CL_10 847.0 844.8
CL_11 842.3 840.4
CL_12 851.5 845.7
CL_13 861.3 855.0
CL_14 861.8 856.2
CL_15 cul-de-sac 861.1 860.1
CL_16 863.6 853.7
CL_17 parking lot 850.1 848.9
CL_18 856.8 851.2
CL_19 street 852.9 848.2
CL_1a street 861.7 861.6
CL_20 855.8 850.8
CL_21 862.6 854.0
CL_22 parking lot 864.6 859.2
CL_23 864.9 859.8
Table 8.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - South
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
CL_25 street 860.7 855.8
CL_27 street/lot 857.9 852.8
CL_3 856.8 855.8
CL_35 869.1 868.9
CL_38 parking lot 858.9 858.1
CL_4 850.5 845.3
CL_48 parking lot 865.8 859.8
CL_49 862.5 862.4
CL_5 865.2 859.6
CL_50 parking lot 870.8 870.6
CL_51 parking lot 862.1 860.1
CL_52 862.4 862.0
CL_53 848.6 844.1
CL_53a 851.7 851.4
CL_53b 853.9 851.2
CL_54 858.2 852.5
CL_55 866.1 865.8
CL_56 street 852.9 845.5
CL_57 street 854.1 846.4
CL_58 street 853.1 845.9
CL_59 856.0 855.2
CL_60 parking lot 873.4 873.3
CL_61 parking lot 867.4 866.0
CL_61old 867.4 866.0
CL_62 868.0 867.9
CL_8 parking lot 854.1 849.5
CL_9 852.6 848.6
EdCrk15 828.6 825.5
EdCrk15a 830.7 829.2
EdCrk15b 829.2 826.9
EdCrk15c 828.7 825.5
EdCrk16 828.3 825.0
EdCrk16a 828.6 825.4
Table 8.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - South
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
EdCrk16b 828.5 825.2
EdCrk16c 828.5 825.1
EdCrk17 827.2 824.2
EdCrk17a 827.4 824.6
EdCrk18 creek 826.4 822.8
EdCrk18a 826.8 823.6
EdCrk19 creek 823.7 820.5
EdCrk19a_1 825.4 821.4
EdCrk20 821.7 818.8
EdCrk20a 822.3 819.8
EdCrk20b 821.9 819.3
FID5954 834.2 832.8
FID6262 847.9 847.2
FID6580 867.8 865.4
N399 860.0 859.3
N403 821.9 819.6
N409 830.3 830.2
N416 830.7 830.1
N435 859.7 859.3
N436 825.3 825.0
NMS_10 street 821.9 821.0
NMS_100 street 821.9 819.3
NMS_101 parking lot 832.9 829.0
NMS_102 byd 827.8 827.3
NMS_103 pond 818.2 823.2 5.0 822.2 4.0
NMS_104 pond 818.3 823.2 4.9 822.2 3.9
NMS_105 831.5 831.3
NMS_106 parking lot 839.7 835.5
NMS_107 ditch 842.0 839.2
NMS_108 street/lot 822.7 820.6
NMS_11 street/lot 822.7 820.8
NMS_12 parking lot 822.7 820.1
NMS_13 street/lot 822.4 819.3
Table 8.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - South
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
NMS_14 parking lot 834.9 834.4
NMS_15 830.8 830.2
NMS_16 street/lot 828.8 825.6
NMS_18 street/lot 834.0 833.4
NMS_19 parking lot 822.7 820.1
NMS_20 street 834.0 833.8
NMS_21 parking lot 831.3 829.5
NMS_22 street 822.7 820.7
NMS_23 pond 818.2 823.2 5.0 822.2 4.0
NMS_24 street/byd 829.7 829.2
NMS_25 837.7 837.4
NMS_26 835.6 835.3
NMS_27 parking lot 828.0 825.4
NMS_28 wetland 825.0 829.2 4.2 827.9 2.9
NMS_29 ditch 837.0 836.0
NMS_30 parking lot 828.4 827.9
NMS_31 parking lot 827.7 826.9
NMS_31a pond 824.2 827.7 3.5 826.9 2.7
NMS_32 832.1 830.4
NMS_33 street 831.3 825.6
NMS_34 827.2 824.2
NMS_35 828.5 825.9
NMS_36 830.0 828.7
NMS_37 844.1 843.9
NMS_38 street 869.4 868.0
NMS_39 831.4 831.3
NMS_4 824.6 824.4
NMS_40 pond 836.3 844.6 8.3 843.4 7.1
NMS_41 886.4 886.2
NMS_42 street/lot 830.8 830.3
NMS_43 parking lot 822.7 820.2
NMS_44 831.6 829.9
NMS_45 831.1 830.9
Table 8.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - South
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
NMS_46 884.0 883.8
NMS_47 street 848.2 847.8
NMS_48 street 844.5 843.6
NMS_49 street 845.2 844.8
NMS_5 828.1 823.0
NMS_50 street 869.4 866.7
NMS_51 parking lot 833.2 832.4
NMS_52 826.5 825.9
NMS_53 parking lot 829.2 828.9
NMS_54 845.6 845.5
NMS_55 street 844.6 841.7
NMS_56 parking lot 828.7 828.4
NMS_57 parking lot 828.9 828.1
NMS_58 parking lot 828.4 827.7
NMS_59 street 845.5 845.2
NMS_6 parking lot 840.3 839.9
NMS_60 street 850.8 846.3
NMS_61 838.5 836.2
NMS_62 street 828.4 827.9
NMS_63 hwy ditch 825.7 825.3
NMS_64 field 835.7 835.4
NMS_65 parking lot 833.8 833.5
NMS_66 841.9 839.1
NMS_67 838.9 838.5
NMS_68 836.7 836.4
NMS_69 830.0 829.4
NMS_7 street/lot 830.7 827.7
NMS_70 street 826.2 825.0
NMS_71 839.2 838.9
NMS_72 pond 818.2 823.2 5.0 822.2 4.0
NMS_73 831.8 831.4
NMS_74 pond 818.2 823.2 5.0 822.2 4.0
NMS_75 parking lot 824.6 822.5
Table 8.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - South
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
NMS_76 pond 818.8 826.0 7.2 824.7 5.9
NMS_77 street 828.3 827.2
NMS_78 street 828.3 827.4
NMS_79 pond 818.2 823.2 5.0 822.2 4.0
NMS_8 843.0 839.4
NMS_80 parking lot 827.7 827.6
NMS_81 847.6 847.4
NMS_82 836.0 835.5
NMS_83 street 834.5 833.2
NMS_84 field 826.2 825.1
NMS_85 829.7 828.5
NMS_86 835.9 835.6
NMS_87 834.5 833.8
NMS_88 pond 818.2 823.2 5.0 822.2 4.0
NMS_89 827.0 826.3
NMS_90 839.9 836.7
NMS_91 843.6 843.4
NMS_92 830.8 830.5
NMS_93 street 826.1 824.8
NMS_94 street 832.3 831.5
NMS_95 street/lot 822.7 820.7
NMS_96 parking lot 823.1 822.2
NMS_97 parking lot 822.7 820.0
NMS_98 street 870.2 870.0
NMS_99 845.9 845.6
SP_1 pond 814.7 822.7 8.0 820.3 5.6
SP_10 street 824.6 824.4
SP_11 parking lot 829.6 828.4
SP_12 838.2 838.1
SP_13 loading dock 827.9 827.6
SP_14 823.2 821.3
SP_15 834.5 832.4
SP_16 parking lot 829.6 828.9
Table 8.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile Creek - South
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
SP_17 parking lot 826.2 823.4
SP_18 parking lot 834.9 833.5
SP_2 850.9 850.7
SP_3 839.8 835.8
SP_4 837.4 832.9
SP_5 street 822.7 820.5
SP_6 824.5 822.1
SP_7 831.2 829.6
SP_8 parking lot 843.4 841.8
SP_9 parking lot 823.9 822.6
SP_9a depression 823.7 822.3
§¨¦494
62
100
456717
456731
456728
W 77th St
Parklawn Ave
W American Blvd
Hazelton Rd Normandale Rd Minnesota Dr
Dewey Hill Rd
BloomingtonBloomington
RichfieldRichfield
NorthBra nc h N in e Mile C reek
SP_1
CL_1
SP_6
NMS_38
EdCrk20
NMS_28
SP_7
NMS_3
NMS_40
NMS_7
NMS_27
NMS_50
NMS_64
SP_5
NMS_31
SP_9
NMS_6
CL_20
NMS_51
NMS_47
CL_3
NMS_29
CL_27
NMS_84
NMS_70
NMS_81
CL_5
CL_48
NMS_57
NMS_108
NMS_14
NMS_13
CL_13
NMS_76
SP_18
NMS_37
NMS_30
SP_16
NMS_97
NMS_16
SP_17
NMS_22
NMS_95
NMS_82
NMS_15
CL_55
NMS_103 NMS_72
NMS_46
NMS_77
SP_11
NMS_39
NMS_41
NMS_98
NMS_45
NMS_73
CL_38
NMS_90
CL_51
NMS_79
NMS_74
NMS_25
NMS_92
CL_53
NMS_75
CL_56
NMS_58
NMS_18
NMS_96
SP_13
NMS_52
NMS_104
NMS_93
CL_16
CL_4
CL_50
CL_23
NMS_63
CL_14
SP_10
CL_61
NMS_12
NMS_71
NMS_4
EdCrk19
NMS_11
SP_4
NMS_42
CL_9
NMS_88
NMS_83
CL_17
NMS_21
NMS_107
NMS_49
NMS_55
NMS_32
EdCrk17
NMS_89
NMS_62
CL_25
SP_3
SP_15
CL_49
NMS_20
NMS_44
EdCrk18
NMS_10
NMS_48
NMS_69
NMS_66
NMS_99
SP_12
CL_57
CL_54
NMS_91
CL_15
CL_35
NMS_53
NMS_80
CL_22NMS_43
NMS_8
NMS_24
NMS_26
NMS_86
NMS_85
NMS_106
SP_2
NMS_100
NMS_56
CL_8
NMS_68
NMS_78
NMS_105
NMS_102
CL_21
CL_18NMS_5
NMS_65
NMS_33
CL_53b
NMS_101
CL_52
CL_19
CL_12
CL_60
NMS_67
CL_11
SP_8NMS_31a
NMS_60
CL_1a
NMS_94
NMS_54NMS_59
CL_53a
CL_62
CL_58NMS_36
CL_10
NMS_19 SP_14
NMS_87 CL_59
NMS_61
SP_9a
NMS_34
NMS_35
NMS_23
Centennial Lakes
Barr Footer: ArcGIS 10.4.1, 2017-09-21 11:53 File: \\barr.com\gis\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_8_1_NMC_South_Drainage_Basins.mxd User: rcs2FIGURE 8.1
0 1,200
Feet
!;N
Nine Mile Creek - SouthDrainage Basin
Subwatershed
Streets and Highways
Creek/Stream
City of Edina Boundary
Lake/Wetland
Imagery Source: MnGeo; 2016
NINE MILE CREEK - SOUTHDRAINAGE BASINComprehensiveWater ResourcesManagement PlanCity of Edina, Minnesota
§¨¦494
62
100
456717
456731
456728
W 77th St
Parklawn Ave
W American Blvd
Hazelton Rd Normandale Rd Minnesota Dr
Dewey Hill Rd
Nine Mile South
South Pond
Centennial Lakes
BloomingtonBloomington
RichfieldRichfield
NorthBra nc h N in e Mile C reek
Centennial Lakes
Barr Footer: ArcGIS 10.4.1, 2017-09-21 11:55 File: \\barr.com\gis\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_8_2_NMC_South_Major_Watersheds.mxd User: rcs2FIGURE 8.2
0 1,200
Feet
!;N
Nine Mile Creek - SouthDrainage Basin
Major Watershed
Centennial Lakes
Nine Mile South
South Pond
Subwatershed
Streets and Highways
Creek/Stream
City of Edina Boundary
Lake/Wetland
Imagery Source: MnGeo; 2016
NINE MILE CREEK - SOUTHMAJOR WATERSHEDSComprehensiveWater ResourcesManagement PlanCity of Edina, Minnesota
City of Edina 2018 Comprehensive Water Resources Management Plan
8-24
Figure 8.3 Nine Mile Creek—South Hydraulic Model Results
This is a large drawing (34x44).
Due to the paper and size and file size, this figure is included as a stand-alone PDF.
NMS_76NMS_79
NMS_88
NMS_72NMS_103
NMS_104
SP_1
NMS_23
NMS_40
NMS_28
NMS_84
NMS_74
NMS_74
CL_1
CL_1
AH_1
BloomingtonBloomington
RichfieldRichfield
NineMi leCreek
Barr Footer: ArcGIS 10.4.1, 2017-09-21 08:35 File: \\barr.com\gis\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_8_4_NMC_South_Water_Quality.mxd User: rcs2NINE MILE CREEK SOUTHWATER QUALITY MODELING RESULTSComprehensive Water ResourceManagement PlanCity of Edina, Minnesota
FIGURE 8.4
1,200 0 1,200Feet
!;N
400 0 400Meters
Percent TP Removal in Water Body*This number represents the percent of the total annual massof phosphorus entering the water body that is removed.
Cumulative TP Removal in Watershed*This number represents the percent of the total annual massof phosphorus entering the watershed and upstream watershedsthat is removed in the pond and all upstream ponds.
*Data based on results of 2003 P8 modeling.
0 - 25% (Poor/No Treatment)
25 - 40% (Moderate Removal)
40 - 60% (Good Removal)
60 - 100% (Excellent Removal)
0 - 25% (Poor/No Treatment)
25 - 40% (Moderate Removal)
40 - 60% (Good Removal)
60 - 100% (Excellent Removal)
Imagery Source: USDA 2016 NAIP via MnGeo
Area Draining Directly to the NorthFork of Nine Mile Creek
Flow Direction
City of Edina 2018 Comprehensive Water Resources Management Plan
9-1
9.0 Nine Mile South Fork
9.1 General Description of Drainage Area
Figure 9.1 depicts the drainage area to the South Fork of Nine Mile Creek and the individual
subwatersheds within this area. The Nine Mile South Fork drainage basin is located in the southwest
corner of Edina and includes a small portion of Eden Prairie. Several land-locked lakes are located within
this drainage basin, including Arrowhead Lake and Indianhead Lake. These areas would become tributary
to the South Fork of Nine Mile Creek only under extreme flooding circumstances (storms greater than the
1-percent-annual-chance storm event).
9.1.1 Drainage Patterns
The stormwater system within this drainage area comprises storm sewers, ditches, overland flow paths,
wetlands, and ponding basins. The Nine Mile South Fork drainage basin has been divided into several
major watersheds based on the drainage patterns. These major watersheds are depicted on Figure 9.2.
Each major watershed has been further delineated into many subwatersheds. The naming convention for
each subwatershed is based on the major watershed where it is located Table 9.1 lists each major
watershed and the associated subwatershed naming convention.
Table 9.1 Major Watersheds within the Nine Mile South Fork Drainage Basin
Major Watershed
Subwatershed Naming
Convention
Number of
Subwatersheds
Drainage Area
(acres)
Arrowhead Lake AH_## 31 178
Indianhead IH_## 12 108
Pawnee Pond PA_## 13 39
Eden Prairie EP_## 2 217
Braemar Arena/Public Works BA_## 4 27
Nine Mile South Fork NMSB_## / BRCrk## 99 816
9.1.1.1 Arrowhead Lake
The Arrowhead Lake watershed extends north of TH 62 and is bordered on the west side by TH 169 and
generally bordered on the east and south side by Indian Hills Road/Pass. Land use in the 178-acre
watershed mainly single family residential; however, portions of TH 62 and the TH 62/TH 169 intersection
are tributary to the lake. Within the watershed there are three stormwater detention basins that ultimately
drain to Arrowhead Lake. Arrowhead Lake is a land-locked basin covering approximately 22 acres.
9.1.1.2 Indianhead Lake
The Indianhead Lake watershed is located southeast of Arrowhead Lake. Within the 108-acre watershed,
there are two stormwater detention basins in addition to the lake. The residential watershed ultimately
City of Edina 2018 Comprehensive Water Resources Management Plan
9-2
drains to Indianhead Lake via storm sewer networks and overland flow channels. Indianhead Lake is a
land-locked basin covering approximately 14 acres.
9.1.1.3 Pawnee Pond
The Pawnee Pond watershed is approximately 39 acres. The watershed is a residential area consisting of
two stormwater detention basins, Pawnee Pond, and a smaller basin east of the intersection of Apache
Road and Sally Lane. The Pawnee Pond is located directly north of Apache Road, bordered by Indian Way
West on the west, Pawnee Road on the east, and Indian Hills Road on the north. The normal elevation of
Pawnee Pond is controlled at an elevation of 862 feet by a pumped outlet. The outflow from Pawnee
Pond flows westerly through a cross-culvert beneath TH 169, then south on the west side of TH 169, and
ultimately into the Braemar Branch of Nine Mile Creek.
9.1.1.4 Eden Prairie
The Eden Prairie watershed consists of approximately 217 acres of land west of TH 169 that drains to the
South Fork of Nine Mile Creek via the Braemar Branch of Nine Mile Creek. Stormwater runoff from this
area flows through a succession of storm sewer systems and ponding basins, eventually outletting to the
drainage way that flows south along the west side of TH 169. The Eden Prairie watershed boundaries were
based on the watershed divides from the Nine Mile Creek Watershed District Water Management Plan
(May 1996). Land use within this area consists mainly of industrial and office property.
9.1.1.5 Braemar Arena/Public Works
The Braemar Arena/Public Works watershed includes drainage from the south parking lot of the Braemar
Arena, Braemar Boulevard, and the Public Works and Public Safety Training Site. The remaining portion of
the Braemar Sports Complex parking lot that does not drain to the south drains westerly to the TH 169
drainage system. The 27-acre Braemar Arena/Public Works watershed drains south through a storm sewer
system to a 0.24-acre stormwater detention pond. The water level of this detention pond is controlled at
an elevation of 846 feet by a 24-inch-diameter outlet pipe that discharges south to the floodplain of the
South Fork of Nine Mile Creek.
9.1.1.6 Nine Mile South Fork
The Nine Mile South Fork watershed is composed of 99 subwatersheds that drain through the drainage
system of the Braemar Golf Course, ultimately discharging to the South Fork of Nine Mile Creek. The
816-acre watershed has a wide range of land uses, including residential, industrial, wetlands, open
area/park, and the golf course. The stormwater system throughout this area is characterized by storm
sewer, ditches, ponds, and overland flow networks. The extent of the Nine Mile South Fork watershed
spans west of TH 169, where drainage from the Washington Avenue storm sewer system combines with
flows from the Eden Prairie and Pawnee Pond watersheds. This stormwater flows easterly under TH 169
through a large culvert, midway between Hamilton Road and West 69th Street, and discharges to the
Braemar Branch of Nine Mile Creek. The Braemar Branch drains southward through Braemar Park towards
the Braemar Golf Course. The Braemar Branch flows through several ponding basins on the west side of
the golf course before discharging to the South Fork. Stormwater from the remaining portion of the Nine
City of Edina 2018 Comprehensive Water Resources Management Plan
9-3
Mile South Fork watershed flows through a series of storm sewer pipes, wetlands, and ponds on the east
side of the Braemar Golf Course before reaching the South Fork of Nine Mile Creek.
9.2 Stormwater System Results
9.2.1 Hydrologic/Hydraulic Modeling Results
The 10- and 1-percent-annual-chance flood analyses were performed for the Nine Mile South Fork
Watershed. The 10-percent-annual-chance analysis was based on a ½-hour storm with 1.65 inches of rain.
The 1-percent-annual-chance analysis was based on a 24-hour storm event with 7.47 inches of rain and
on a 10-day snowmelt event with 7.2 inches of runoff; the higher resulting flood level of the two events
was chosen for the 1-percent-annual-chance analysis. Table 9.2 presents the watershed information and
the results for the 10- and 1-percent-annual-chance hydrologic analyses. A more detailed description of
the stormwater system analysis is provided in Section 4.1.3.
The results of the 10- and 1-percent-annual-chance hydraulic analyses for the Nine Mile South Fork
drainage area are summarized in Table 9.3.
Figure 9.3 illustrates the results of the 10- and 1-percent-annual-chance hydraulic analyses. The figure
depicts the Nine Mile South Fork drainage area boundary, subwatershed boundaries, the modeled storm
sewer network, surcharge conditions for the XP-SWMM nodes (typically manholes), and the flood-prone
areas identified in the modeling analyses.
Figure 9.3 illustrates that several XP-SWMM nodes within the Nine Mile South Fork drainage area are
predicted to surcharge during both the 10- and 1-percent-annual-chance events. This means that in any
year there is a greater than 10 percent probability that the system will be overburdened and unable to
meet the desired level of service at these locations. These manholes and catch basins are more likely to
become inundated during the smaller, more frequent storm events of various durations.
To evaluate the level of protection of the stormwater system within the Nine Mile South Fork drainage
area, the 1-percent-annual-chance flood elevations for the ponding basins and depressed areas were
compared to the low elevations of structures surrounding each basin.. The areas predicted to potentially
flood and threaten structures during the 1-percent-annual-chance storm event are shown on Figure 9.3.
Discussion and recommended improvement considerations for these areas are included in Section 9.3.
9.2.2 Water Quality Modeling Results
The effectiveness of the stormwater system in removing stormwater pollutants such as phosphorus was
analyzed using the P8 water quality model. The P8 model simulates the hydrology and phosphorus loads
introduced from each pond’s watershed and the transport of phosphorus throughout the stormwater
system. A more detailed description of the stormwater system analysis is provided in Section 4.1.3.
City of Edina 2018 Comprehensive Water Resources Management Plan
9-4
Figure 9.4 depicts the results of the water quality modeling for the Nine Mile South Fork drainage basin.
The figure shows the fraction of total phosphorus removal for each water body as well as the cumulative
total phosphorus removal in the watershed.
9.3 Implementation Considerations
The 2017 XP-SWMM hydrologic and hydraulic modeling analyses and 2003 P8 water quality analysis
helped identify locations throughout the watershed where improvements to the City’s stormwater
management system may be warranted. The following sections discuss potential improvement options
identified as part of the modeling analyses. As opportunities to address identified flooding issues and
improve water quality arise (e.g., street reconstruction projects or public facilities improvements), the City
will use a comprehensive approach to stormwater management. This approach will include consideration
of infiltration or volume retention practices to address flooding and/or improve water quality, reduction of
impervious surfaces, increased storm sewer capacity where necessary to alleviate flooding, construction
and/or expansion of water quality basins, and implementation of other stormwater BMPs to reduce
pollutant loading to downstream waterbodies.
9.3.1 Flood Protection Projects
The 2017 hydrologic and hydraulic modeling analyses identified several locations within the Nine Mile
South Fork drainage basin where the 1-percent-annual-chance level of protection is not provided by the
current stormwater system. The problem areas identified in 2017 are discussed below.
As part of the 2017 modeling analyses, potential corrective measures were identified for the problem
areas. These preliminary corrective measures are also discussed below. As the City evaluates flooding
issues and potential system modifications in these areas, other potential modifications, including (but not
limited to) implementation of volume-retention practices, increases in conveyance capacity, and/or
stormwater infiltration (where soils are conducive) will be given consideration.
The 2003 hydrologic and hydraulic modeling analyses also identified several locations within the Nine
Mile South Fork drainage basin where the 1-percent-annual-chance level of protection was not provided
by the stormwater system, based on TP-40 precipitation frequency estimates. The discussions related to
those areas have been carried over to Appendix C of this plan, along with a short summary of what has
been done since 2003.
9.3.1.1 McCauley Trail West (AH_6)
A stormwater pond located behind 6533–6545 McCauley Trail West and 6301 Timber Trail receives runoff
from approximately 39.3 acres with approximately 13 acres being direct drainage, mostly north of TH 62.
The pond has a 21-inch gravity drain outlet that discharges to land-locked Arrowhead Lake. There is a
pumped outlet (Lift Station 8) that appears to be in place to draw the pond down below the outlet
elevation, but the pump capacity appears to be very minor compared to the gravity drain capacity.
Without definitive information on the pump capacity, and due to its relatively small size, this pump was
City of Edina 2018 Comprehensive Water Resources Management Plan
9-5
not included in the modeling. Modeling results indicate that the 1-percent-annual-chance flood elevation
(885.0 feet) may impact up to nine principle structures for a duration of approximately 6 hours.
Several options to alleviate flooding in this area should be considered, including providing additional
outlet capacity and storing additional water upstream. An increase in discharge capacity from the pond
could likely reduce the number of principle structures potentially impacted in AH_6 without creating
impacts to principle structures around Arrowhead Lake. The 1-percent-chance annual flood elevation in
downstream Arrowhead Lake is well below the low houses adjacent to the lake. Additionally, the critical 1-
percent-annual-chance event for Arrowhead Lake is the 1-percent-annual-chance 10-day snowmelt—not
the 24-hour storm event. A restrictive outlet upstream of TH 62 could also be implemented to store more
water in AH_3 during a precipitation event and limit the amount of water contributing to AH_6. A
restrictive outlet, without changing the invert, would allow for AH_3 to drain dry between events. Finally,
there are some options for creating additional stormwater storage. In subwatershed AH_9, there is room
for additional regrading work to create additional storage.
9.3.1.2 Sally Lane and Valley View Road (NMSB_52, NMSB_69, and NMSB_77)
The ravine located in the backyards of the homes between Sally Lane and McCauley Trail South receives
stormwater flows from a 436-acre tributary area that includes portions of Eden Prairie and Edina. This
ravine, which is the headwaters of the Braemar Branch of Nine Mile Creek, crosses under Valley View Road
through a 6-foot by 11.7-foot box culvert. Modeling results indicate that the 1-percent-annual-chance
flood elevations along this ravine may impact up to 19 principle structures (6713–6721 Sioux Trail, 6800–
7008 Sally Lane, 7016, 7020, and 7028 Sally Lane).
The storm sewer system at the Paiute Pass and Sally Lane intersection collects stormwater from a total
drainage area of approximately 27 acres. The system discharges into the Braemar Branch, west of Sally
Lane, via two 24-inch pipes. Flooding issues at the intersection of Sally Lane and Paiute Pass were
analyzed in 2013 (Project STS-406). However, that work was focused on the intersection and not the
backyards of the principle structures along Sally Lane that are affected by high water levels within the
ravine. Some of the recommendations from the 2013 analysis to reduce flood risk at this intersection were
implemented as part of the 2016 street reconstruction project.
There are several options that should be considered to reduce flood risk in the backyard ravine area,
including increasing capacity of the Braemar Branch culvert under Valley View Road and providing
additional flood storage in the tributary drainage area. It is recommended that the City work with the
NMCWD to evaluate potential impacts of increasing the capacity under Valley View Road. It is also
recommended that the City work with the City of Eden Prairie and Nine Mile Creek Watershed District to
identify opportunities for increased flood storage upstream of the Braemar Branch.
9.3.2 Construction/Upgrade of Water Quality Basins
The 2003 P8 modeling analysis predicted that under average conditions the annual removal of total
phosphorus from several ponds in the Nine Mile South Fork drainage area would be below the desired
60 percent removal rate. For those ponds with total phosphorus removal below 60 percent, the
City of Edina 2018 Comprehensive Water Resources Management Plan
9-6
permanent pool storage volume was analyzed to determine whether additional capacity was necessary.
The ponds with deficiencies in total phosphorus removal and permanent pool volume are listed below
(and are also summarized in Appendix D), with recommended pond upgrades.
Construction of new or expansion of existing water quality basins is one method to increase the pollutant
removal achieved prior to stormwater reaching downstream waterbodies. Many additional techniques are
available to reduce pollutant loading, including impervious surface reduction or disconnection,
implementation of infiltration or volume-retention BMPs, installation of underground stormwater
treatment structures and sump manholes, and other good housekeeping practices such as street
sweeping. As opportunities arise, the City will consider all of these options to reduce the volume and
improve the quality of stormwater runoff.
9.3.2.1 NMSB_3 and NMSB_2
Pond NMSB_3 is located on the Braemar Golf Course, southeast of the intersection of Valley View Road
and Braemar Boulevard. This pond receives stormwater from an immediate watershed of approximately
21 acres, as well as discharge from the Braemar Branch. The Braemar Branch drains an area of
approximately 259 acres and flow from Pond NMSB_33 to the east. The pond is a Type 5 wetland and was
assumed to have an average depth of 4 feet. Pond NMSB_2 is downstream of Pond NMSB_3 and
connected by a 30-inch equalizer pipe. Pond NMSB_2 receives stormwater from an immediate watershed
of approximately 5 acres, as well as the flow from NMSB_3. This pond is also a Type 5 wetland and was
assumed to have an average depth of 4 feet.
Based on modeling results, the annual removal of total phosphorus from these two ponds was predicted
to be below 60 percent. Consequently, the MPCA-recommended permanent pool storage volume for
these ponds was calculated and compared to the existing dead storage volume. For the permanent pool
volume analysis, the two ponds were considered as one. Based on this assumption, the ponds are
deficient in dead storage volume. We recommend that an additional 1.2 acre-feet of dead storage volume
be provided to these two ponds to meet the MPCA design criteria for detention basins.
9.3.2.2 NMSB_12
Pond NMSB_12 is located on the Braemar Golf Course, approximately 700 feet southwest of the
clubhouse. The pond receives stormwater runoff from the direct watershed of approximately 12 acres, in
addition to flow from the upstream wetland NMSB_56. According to the wetland inventory, the pond is a
Type 5 wetland and assumed to have an average depth of 4 feet. Based on this depth and the 2-foot
topographic information, the current permanent pool storage volume is greater than the MPCA-
recommended volume for detention ponds. It is recommended that the basin be maintained on a regular
basis to ensure the removal efficiency is maintained.
9.3.2.3 NMSB_86
Pond NMSB_86 is located on the Braemar Golf Course, directly south of the clubhouse parking lot. Pond
NMSB_86 is a small pond that receives stormwater runoff from a direct watershed of approximately
21 acres, as well as discharge from the upstream pond (NMSB_57). The pond discharges directly to the
City of Edina 2018 Comprehensive Water Resources Management Plan
9-7
South Fork of Nine Mile Creek via a 30-inch pipe. Based on modeling results, the annual removal of total
phosphorus from Pond NMSB_86 was predicted to be well below 60 percent. According to the
MPCA-recommended storage volume for detention basins, there is not an adequate amount of
permanent pool storage in this basin. It is recommended that 0.15 acre-feet of dead storage volume be
added to meet the MPCA design criteria for detention basins.
9.3.2.4 NMSB_7
Pond NMSB_7 is located on the Braemar Golf Course on the north side of Braemar Boulevard. Pond
NMSB_7 is a small detention pond that receives stormwater runoff from a 2.4-acre watershed in addition
to discharge from an upstream wetland (NMSB_90). Pond NMSB_7 discharges to Pond NMSB_85 via a
24-inch pipe. Based on Braemar Golf Course design plans, Pond NMSB_7 was assumed to be shallow, with
an average depth of 2.3 feet. Using this depth assumption and the pond area from the 2-foot topographic
information, the current permanent pool storage volume was calculated to be 0.6 acre-feet. This volume is
greater than the MPCA-recommended storage volume for detention ponds. However, because the water
quality modeling results indicate that the total phosphorus removal in Pond NMSB_7 is below 60%, it is
recommended that the depth of the pond be increased to 4 feet to improve removal efficiency.
9.3.2.5 NMSB_85
Pond NMSB_85 is located on the Braemar Golf Course, downstream of Pond NMSB_7, on the north side of
Braemar Boulevard. Pond NMSB_85 receives stormwater runoff from a 67.5-acre watershed, as well as
discharge from Pond NMSB_7 and discharge from a backyard depression area northeast of the
intersection of Gleason Road and Dewey Hill Road (NMSB_15). According to the wetlands inventory, the
pond is Type 5 and was assumed to have an average depth of 4 feet. Based on this depth assumption and
the pond area from the 2-foot topographic data, the current permanent pool storage volume is 1.3 acre-
feet. This storage volume is less than the MPCA-recommended storage volume for detention basins. It is
recommended that an additional 1.2 acre-feet of dead storage volume be provided to meet the MPCA
design criteria for detention basins.
Table 9.2
Watershed Modeling Results for Subwatersheds in the Nine Mile South Fork Drainage Area
1 The 1%-Annual-Chance (100-Year) 10-day snowmelt event is defined as 7.2 inches of runoff
Watershed ID
Total Area
(ac)
% Impervious
Area
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
AH_1 50.2 57 394 24.4 9.5 30.1 171 12.4
AH_10 2.0 19 20 0.7 0.4 1.2 9 0.3
AH_11 1.3 26 12 0.7 0.2 0.8 6 0.4
AH_12 1.5 25 16 0.7 0.3 0.9 8 0.3
AH_13 4.3 20 33 2.2 0.8 2.6 16 1.1
AH_15 1.2 25 11 0.5 0.2 0.7 6 0.3
AH_16 0.4 28 5 0.2 0.1 0.3 3 0.1
AH_17 4.9 25 40 1.9 0.9 2.9 16 0.8
AH_18 2.3 26 21 1.1 0.4 1.4 11 0.5
AH_19 6.4 25 47 2.5 1.2 3.8 18 1.1
AH_20 6.4 15 60 2.3 1.2 3.8 25 1.0
AH_21 6.9 16 62 2.6 1.3 4.2 25 1.1
AH_22 8.6 15 64 3.1 1.6 5.2 23 1.3
AH_23 5.9 22 52 2.7 1.1 3.5 26 1.3
AH_24 3.3 38 28 1.5 0.6 2.0 13 0.7
AH_25 4.6 57 39 2.6 0.9 2.8 20 1.4
AH_26 4.2 24 36 1.9 0.8 2.5 17 0.9
AH_27 1.5 25 13 0.6 0.3 0.9 6 0.3
AH_28 4.8 65 45 2.8 0.9 2.9 23 1.5
AH_29 5.9 53 59 3.4 1.1 3.6 31 1.8
AH_3 6.4 53 71 3.4 1.2 3.8 39 1.8
AH_30 4.1 25 36 1.8 0.8 2.4 18 0.9
AH_31 1.7 25 18 0.7 0.3 1.0 9 0.3
AH_32 7.1 65 57 4.1 1.3 4.2 29 2.3
AH_33 3.1 65 30 1.8 0.6 1.9 16 1.0
AH_4 1.1 34 12 0.6 0.2 0.7 6 0.3
AH_5 3.7 25 28 1.5 0.7 2.2 11 0.7
AH_6 13.0 34 112 6.1 2.5 7.8 54 3.0
AH_7 5.6 65 50 3.3 1.1 3.4 26 1.8
AH_8 0.6 41 7 0.4 0.1 0.4 4 0.2
AH_9 5.2 60 53 2.8 1.0 3.1 27 1.5
BA_1 5.9 47 43 2.8 1.1 3.5 19 1.4
BA_2 3.1 80 23 1.7 0.6 1.9 11 1.0
BA_3 9.1 11 67 3.5 1.7 5.4 26 1.4
BA_6 8.6 11 70 3.4 1.6 5.1 31 1.5
BRCrk12 13.4 6 64 5.0 2.5 8.0 21 2.0
BRCrk13 14.0 4 77 5.3 2.7 8.4 27 2.2
BRCrk15 35.1 11 84 14.5 6.2 21.1 33 6.3
BRCrk16 31.2 16 137 15.5 5.8 18.7 60 7.7
BRCrk17 41.2 39 341 21.3 7.8 24.7 170 11.1
BRCrk18 13.5 42 87 7.4 2.5 8.1 42 3.9
BRCrk3 37.3 34 279 19.3 7.1 22.4 136 10.0
BRCrk4 14.2 18 103 7.1 2.7 8.5 50 3.6
EP_1 95.6 76 437 52.2 17.3 57.4 196 28.0
EP_2 121.8 74 405 67.0 20.6 73.1 185 35.9
IH_1 38.3 52 287 18.2 7.2 22.9 123 9.1
IH_10 6.6 21 55 2.5 1.3 4.0 22 1.1
IH_11 2.7 31 21 1.1 0.5 1.6 9 0.5
IH_12 6.3 25 45 2.5 1.2 3.8 17 1.1
IH_13 5.1 22 44 2.0 1.0 3.1 18 0.8
IH_14 5.0 37 40 2.1 0.9 3.0 16 1.0
IH_15 2.9 26 28 1.2 0.6 1.8 13 0.6
IH_3 18.5 18 127 6.8 3.5 11.1 45 2.8
IH_5 1.4 25 13 0.6 0.3 0.8 6 0.2
IH_6 15.1 21 127 5.8 2.9 9.1 50 2.5
IH_7 1.0 25 10 0.4 0.2 0.6 4 0.2
IH_8 4.7 25 40 2.0 0.9 2.8 18 0.9
NMSB_10 0.3 4 2 0.1 0.1 0.2 1 0.1
NMSB_11 1.4 2 14 0.6 0.3 0.8 7 0.3
NMSB_13 8.1 20 68 3.4 1.5 4.8 31 1.5
Watershed Information 1%-Annual-Chance (100-Year)1%-Annual-Chance (100-Year)10%-Annual-Chance (10-Year)
24-Hour Precipitation Event 10-day Snowmelt Event1 24-Hour Precipitation Event
Table 9.2
Watershed Modeling Results for Subwatersheds in the Nine Mile South Fork Drainage Area
1 The 1%-Annual-Chance (100-Year) 10-day snowmelt event is defined as 7.2 inches of runoff
Watershed ID
Total Area
(ac)
% Impervious
Area
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Watershed Information 1%-Annual-Chance (100-Year)1%-Annual-Chance (100-Year)10%-Annual-Chance (10-Year)
24-Hour Precipitation Event 10-day Snowmelt Event1 24-Hour Precipitation Event
NMSB_14 5.9 25 48 2.6 1.1 3.5 22 1.2
NMSB_15 2.4 25 22 1.0 0.4 1.4 10 0.5
NMSB_16 2.8 24 24 1.3 0.5 1.7 11 0.6
NMSB_17 7.6 23 65 3.1 1.5 4.6 28 1.4
NMSB_18 8.0 25 14 2.7 1.3 4.8 6 1.1
NMSB_19 6.9 26 60 3.0 1.3 4.2 28 1.4
NMSB_20 11.6 7 66 4.3 2.2 7.0 23 1.7
NMSB_21 3.4 28 13 1.4 0.6 2.0 5 0.6
NMSB_22 9.3 27 65 4.0 1.8 5.6 27 1.8
NMSB_23 7.6 25 58 3.0 1.4 4.5 22 1.3
NMSB_24 2.0 65 23 1.1 0.4 1.2 12 0.6
NMSB_25 1.4 25 15 0.6 0.3 0.8 7 0.2
NMSB_26 6.7 25 46 2.7 1.3 4.0 18 1.2
NMSB_27 4.0 25 38 1.7 0.8 2.4 19 0.8
NMSB_28 2.4 25 11 0.9 0.5 1.5 4 0.4
NMSB_29 3.2 25 14 1.2 0.6 1.9 5 0.5
NMSB_30 15.5 25 94 6.1 2.9 9.3 35 2.7
NMSB_31 5.1 24 48 2.0 1.0 3.0 21 0.9
NMSB_32 6.6 25 51 2.6 1.2 3.9 19 1.1
NMSB_34 8.4 22 61 3.2 1.6 5.0 22 1.4
NMSB_35 3.1 20 21 1.2 0.6 1.9 8 0.5
NMSB_36 3.9 24 31 1.6 0.7 2.4 13 0.7
NMSB_37 4.7 25 42 1.9 0.9 2.8 17 0.8
NMSB_38 1.3 25 11 0.6 0.3 0.8 5 0.3
NMSB_39 5.1 25 47 2.0 1.0 3.0 20 0.9
NMSB_40 3.4 23 31 1.4 0.6 2.0 14 0.6
NMSB_41 6.0 8 35 2.3 1.1 3.6 13 0.9
NMSB_42 4.5 22 45 1.9 0.9 2.7 22 0.9
NMSB_43 6.7 22 52 2.8 1.3 4.0 22 1.2
NMSB_44 0.6 3 7 0.3 0.1 0.4 4 0.1
NMSB_45a 4.6 33 39 2.3 0.9 2.8 19 1.2
NMSB_45b 2.3 0 15 0.8 0.4 1.4 5 0.3
NMSB_46 1.2 65 14 0.6 0.2 0.7 7 0.3
NMSB_47 2.7 2 20 1.0 0.5 1.6 8 0.4
NMSB_49 0.6 53 7 0.3 0.1 0.3 4 0.2
NMSB_5 24.6 6 42 8.9 4.3 14.8 15 3.4
NMSB_50 1.9 67 22 1.0 0.4 1.1 12 0.5
NMSB_51 3.4 65 39 1.8 0.6 2.0 21 1.0
NMSB_57 20.6 15 137 8.8 3.9 12.4 59 4.0
NMSB_58 3.6 25 36 1.4 0.7 2.1 16 0.6
NMSB_59 3.8 25 36 1.5 0.7 2.3 15 0.7
NMSB_6 1.7 14 14 0.7 0.3 1.0 7 0.3
NMSB_62 7.3 6 35 2.9 1.4 4.4 13 1.2
NMSB_63 2.7 65 32 1.4 0.5 1.6 17 0.7
NMSB_64 2.7 65 32 1.4 0.5 1.6 17 0.7
NMSB_65 1.3 65 16 0.7 0.3 0.8 9 0.4
NMSB_66 10.0 24 67 3.9 1.9 6.0 25 1.7
NMSB_67 5.8 18 51 2.2 1.1 3.5 20 0.9
NMSB_7 2.4 16 18 1.1 0.5 1.5 9 0.6
NMSB_70 2.9 23 27 1.2 0.5 1.7 12 0.5
NMSB_71 5.6 65 63 3.1 1.1 3.3 34 1.7
NMSB_72 8.5 22 61 3.3 1.6 5.1 24 1.4
NMSB_73 69.6 73 293 37.3 12.5 41.8 128 19.8
NMSB_74 0.7 26 8 0.3 0.1 0.4 4 0.1
NMSB_75 1.6 25 15 0.6 0.3 1.0 7 0.3
NMSB_76 1.4 22 12 0.6 0.3 0.9 5 0.3
NMSB_78 5.6 25 44 2.2 1.1 3.4 18 1.0
NMSB_79 1.2 29 12 0.7 0.2 0.7 6 0.4
NMSB_8 9.8 16 63 4.0 1.9 5.9 26 1.8
NMSB_80 0.5 66 6 0.3 0.1 0.3 3 0.1
Table 9.2
Watershed Modeling Results for Subwatersheds in the Nine Mile South Fork Drainage Area
1 The 1%-Annual-Chance (100-Year) 10-day snowmelt event is defined as 7.2 inches of runoff
Watershed ID
Total Area
(ac)
% Impervious
Area
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Watershed Information 1%-Annual-Chance (100-Year)1%-Annual-Chance (100-Year)10%-Annual-Chance (10-Year)
24-Hour Precipitation Event 10-day Snowmelt Event1 24-Hour Precipitation Event
NMSB_81 0.6 65 7 0.3 0.1 0.3 4 0.2
NMSB_82 2.6 22 21 1.0 0.5 1.6 8 0.4
NMSB_83 10.7 25 60 4.5 2.0 6.4 24 2.0
NMSB_84 3.1 25 28 1.3 0.6 1.8 14 0.6
NMSB_85 16.7 9 88 7.5 3.2 10.0 38 3.6
NMSB_86 20.7 2 54 7.3 3.8 12.4 18 2.8
NMSB_87 8.8 75 81 4.8 1.7 5.3 40 2.6
NMSB_88 1.8 76 21 1.0 0.3 1.1 11 0.5
NMSB_90 29.8 35 201 14.7 5.6 17.9 93 7.4
NMSB_91 2.4 25 23 0.9 0.4 1.4 10 0.4
NMSB_92 0.4 25 4 0.1 0.1 0.2 2 0.1
NMSB_93 0.9 34 10 0.4 0.2 0.5 5 0.2
NMSB_94 4.7 25 32 1.8 0.9 2.8 12 0.8
NMSB_95 5.9 25 47 2.3 1.1 3.5 18 1.0
NMSB_96 1.6 27 15 0.6 0.3 1.0 6 0.3
NMSB_97 6.8 23 46 2.6 1.3 4.1 17 1.1
NMSB_98 0.9 26 8 0.4 0.2 0.5 3 0.2
NMSB_99 4.4 25 34 1.7 0.8 2.7 13 0.8
PA_1 7.7 41 72 3.4 1.5 4.6 32 1.6
PA_10 2.2 25 23 0.9 0.4 1.3 10 0.4
PA_11 1.0 25 11 0.4 0.2 0.6 5 0.2
PA_12 2.1 25 17 0.8 0.4 1.3 7 0.4
PA_13 0.6 25 6 0.2 0.1 0.3 3 0.1
PA_2 1.6 23 15 0.6 0.3 1.0 6 0.3
PA_3 8.6 18 66 3.2 1.6 5.1 25 1.3
PA_4 1.5 25 14 0.6 0.3 0.9 6 0.3
PA_5 2.6 25 27 1.0 0.5 1.6 12 0.5
PA_6 3.9 31 33 1.6 0.7 2.3 14 0.8
PA_7 1.5 25 15 0.6 0.3 0.9 7 0.3
PA_8 3.9 25 31 1.5 0.7 2.3 12 0.7
PA_9 1.7 25 19 0.7 0.3 1.0 9 0.3
Table 9.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile South Fork
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1034 890.8 890.5
1035 876.5 876.3
1036 869.0 868.8
1037 868.4 868.1
1038 868.3 867.9
1042 867.0 866.9
1043 864.4 864.3
1045 862.9 862.7
1047 861.8 861.0
1048 861.7 861.0
1049 861.7 861.0
1052 861.8 861.0
1053 861.8 861.0
1059 851.2 850.9
1060 853.5 851.9
1061 854.4 853.0
1062 871.3 864.4
1063 877.9 874.0
1064 878.6 877.7
1068 881.3 880.5
1071 845.0 844.7
1075 860.1 859.1
1077 844.9 844.9
1080 883.8 881.5
1081 884.6 881.4
1083 883.2 879.8
1085 880.7 879.2
1092 963.8 958.1
1093 942.4 942.2
1094 930.5 930.3
1095 902.0 901.7
1096 892.2 885.6
1098.1 street 883.2 877.4
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
Table 9.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile South Fork
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
1100.1 901.7 895.2
1101 887.6 879.9
1102 882.7 877.0
1103 881.7 876.4
1104 880.1 875.4
1105 875.8 872.6
1106 874.1 871.5
1109 865.6 863.4
1111 845.1 845.1
1256 883.9 883.7
1257 873.0 871.4
1260 844.6 844.2
1261 844.6 844.2
1593 889.7 889.0
1644 876.9 874.3
1651 885.0 884.7
1654 890.7 889.6
1656 894.5 894.4
1872.1 841.0 840.1
1879 870.6 866.9
1880 896.2 889.2
1881 918.6 918.4
1883 854.7 854.5
1885 856.2 856.0
1886 856.9 856.7
1932 884.1 883.9
2081 853.0 852.8
2204 868.0 864.1
2205 868.0 864.3
2209 845.0 844.2
2242 858.2 856.8
2244 860.4 859.7
2246 876.2 870.3
Table 9.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile South Fork
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
2247 877.5 872.9
2400 890.5 890.0
2401 887.6 886.9
2402 881.6 879.8
2405 870.8 867.7
2407 870.3 869.9
2409 869.7 868.7
2437 888.3 887.8
2571 885.0 883.1
2596 872.0 871.1
2603 886.8 884.9
2604 887.5 885.7
2605 887.8 885.9
2619 841.2 840.3
2622 843.5 842.7
2637 888.0 886.0
2639 904.9 904.8
2641 886.9 885.1
2643 885.5 883.6
2644 886.2 886.1
2646 868.0 865.2
2647 869.3 867.2
2648 868.2 866.3
2649 869.5 869.1
2650 868.6 867.6
2652 878.4 877.8
2653 882.6 882.7
2655 889.8 886.8
2656 887.5 886.2
2657 884.9 884.0
2659 868.8 868.2
2660 hwy ditch 868.9 864.8
2661 867.9 863.8
Table 9.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile South Fork
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
2673 882.0 880.8
2676 875.4 875.4
2677 873.3 873.1
2679 879.0 878.7
2694 845.1 844.3
2695 845.8 845.2
2704 889.6 889.0
2727 873.2 870.4
2728 873.8 872.4
2729 874.8 872.8
2730 877.1 874.2
2731 869.0 866.4
2733 841.2 840.1
2868 885.0 884.8
2869 885.0 884.8
2870 885.0 884.8
2871 885.0 884.8
2874 844.4 844.1
2875 844.4 844.0
2947 888.1 886.2
513.1 874.3 873.5
514 street 874.3 873.8
516 872.2 871.5
519 887.2 887.0
520 888.0 887.8
521 891.6 891.4
523 871.3 869.6
534.1 880.0 875.1
536 street 880.6 874.9
537 880.3 874.0
539 875.8 871.1
541 869.2 867.1
543.1 880.6 878.0
Table 9.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile South Fork
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
546 870.1 868.3
548.1 871.2 868.4
549 869.0 868.1
552 884.3 884.3
553 883.5 883.5
555 882.3 878.9
560 950.9 946.4
561 879.9 ¹ 877.5
564 884.6 882.7
565 883.9 881.9
566 881.2 879.6
570 885.0 881.4
571 885.9 884.0
575 887.4 886.9
576 887.5 886.8
578 887.3 886.6
580 886.3 885.7
581 885.4 884.3
AH_1 lake 875.8* 879.9 ¹ 4.1 877.5 1.7
AH_10 955.5 953.4
AH_11 886.9 886.4
AH_12 byd 888.1 886.2
AH_13 school yard 887.7 887.3
AH_15 depression 887.6 886.8
AH_16 street 886.8 886.3
AH_17 895.1 894.9
AH_18 892.1 891.9
AH_19 885.0 884.7
AH_20 885.4 885.2
AH_21 883.3 882.9
AH_22 882.3 881.8
AH_23 889.5 889.1
AH_24 893.9 892.2
Table 9.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile South Fork
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
AH_25 hwy ditch 888.1 886.2
AH_26 905.2 905.1
AH_27 byd 892.6 892.5
AH_28 hwy ditch 888.0 886.1
AH_29 hwy ditch 888.2 886.7
AH_3 hwy ditch 885.0 884.8
AH_30 street 905.6 903.7
AH_31 byd 885.0 883.1
AH_32 hwy ditch 887.9 886.0
AH_33 888.7 888.6
AH_4 pond 885.5 886.4 0.9 886.2 0.7
AH_5 street 885.0 880.9
AH_6 pond 880.0 885.0 5.0 883.1 3.1
AH_7 hwy ditch 889.2 887.9
AH_8 885.0 883.1
AH_9 parking lot 888.2 887.4
BA_1 879.2 875.6
BA_2 892.9 887.3
BA_3 873.1 867.0
BA_6 pond 846.0 854.1 8.1 849.9 3.9
BRCrk1 832.8 831.8
BRCrk10 pond 840.2 845.0 4.8 844.2 4.0
BRCrk10.1 pond 840.2 844.9 4.7 844.2 4.0
BRCrk11 pond 840.2 843.6 3.4 843.4 3.2
BRCrk12 842.7 841.7
BRCrk12a 843.5 842.6
BRCrk12b 842.8 841.8
BRCrk12c 842.7 841.7
BRCrk13 838.8 838.6
BRCrk13a 842.7 841.7
BRCrk13b 842.7 841.6
BRCrk13c 842.0 841.1
BRCrk13d 838.9 838.7
Table 9.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile South Fork
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
BRCrk13e 838.9 838.7
BRCrk14 creek 832.6 831.5
BRCrk15 pond 827.2 832.6 5.4 831.2 4.0
BRCrk16 pond 827.2 832.6 5.4 831.2 4.0
BRCrk16a 832.6 831.2
BRCrk16b 832.6 831.2
BRCrk17a 832.6 831.2
BRCrk17b 832.6 831.2
BRCrk17c 832.6 831.2
BRCrk17d 832.6 831.2
BRCrk17e 832.6 831.2
BRCrk17f 832.6 831.2
BRCrk17g 832.6 831.2
BRCrk17h 832.5 831.1
BRCrk18 pond 827.8 832.6 4.8 831.2 3.4
BRCrk2 832.6 832.4
BRCrk3 creek 832.5 831.3
BRCrk4 creek 832.6 831.2
BRCrk5 861.8 859.9
BRCrk5a 861.9 860.4
BRCrk5b 861.9 860.1
BRCrk6 861.4 859.0
BRCrk7 859.8 857.0
BRCrk7a 860.7 858.0
BRCrk8 850.8 849.8
BRCrk8a 857.6 856.0
BRCrk8b 854.7 853.6
BRCrk8c 852.7 852.2
BRCrk9 creek 848.1 847.5
EP_1 pond 865.4 872.1 6.7 871.3 5.9
EP_2 ponds 892.2 890.0
FID4816 888.1 886.2
FID6047 865.6 865.5
Table 9.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile South Fork
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
FID6048 865.6 865.4
FID6049 865.6 865.3
FID6050 865.5 865.2
FID6121 870.6 869.3
IH_1 lake 863.7* 867.6 ¹ 3.9 865.0 1.3
IH_10 895.7 894.2
IH_11 876.8 874.0
IH_12 street 878.8 878.6
IH_13 880.4 880.1
IH_14 pond 869.8 875.0 5.2 873.7 3.9
IH_15 921.6 921.5
IH_3 depression 872.9 869.9
IH_5 street 874.3 873.5
IH_6 street 875.0 873.7
IH_7 street 874.7 874.6
IH_8 894.0 893.9
MH_5039 859.2 857.9
MH_5040 858.9 857.5
MH_5042 858.2 856.6
MH_5050 860.3 859.4
MH_5051 861.2 860.5
N669 864.0 863.7
N671 882.0 882.0
N672 862.1 862.1
N722 886.2 886.1
N723 885.6 883.6
N724 882.0 882.0
NMSB_10 840.8 840.0
NMSB_11 842.3 842.0
NMSB_13 street 870.6 866.9
NMSB_14 858.6 858.4
NMSB_15 byd 844.8 843.2
NMSB_16 844.6 844.5
Table 9.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile South Fork
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
NMSB_17 844.6 844.3
NMSB_18 883.1 877.9
NMSB_19 903.5 903.3
NMSB_20 depression 847.0 846.7
NMSB_21 943.5 943.2
NMSB_22 street 882.7 878.8
NMSB_23 street 885.0 881.2
NMSB_24 hwy ditch 876.8 876.3
NMSB_25 932.8 929.6
NMSB_26 street 880.7 871.8
NMSB_27 byd 881.1 879.3
NMSB_28 877.2 869.8
NMSB_29 874.5 868.5
NMSB_30 street 870.6 869.3
NMSB_31 street 866.1 865.8
NMSB_32 861.8 861.6
NMSB_34 byd 875.3 ¹ 869.9
NMSB_35 wetland 880.0 883.5 3.5 881.5 1.5
NMSB_36 848.1 847.7
NMSB_37 street 858.2 854.0
NMSB_38 street 977.6 977.1
NMSB_39 853.4 852.1
NMSB_40 847.0 846.8
NMSB_41 depression 843.9 843.0
NMSB_42 853.3 852.8
NMSB_43 street 856.9 856.7
NMSB_44 street 841.2 840.3
NMSB_45a facility 887.4 884.2
NMSB_45b sports dome 881.5 881.2
NMSB_46 hwy ditch 861.4 859.4
NMSB_47 street 841.2 840.1
NMSB_49 866.9 866.9
NMSB_5 pond 835.6 841.2 5.6 840.2 4.6
Table 9.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile South Fork
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
NMSB_50 hwy ditch 867.1 866.2
NMSB_51 hwy ditch 877.9 877.1
NMSB_57 pond 835.6 840.5 4.9 839.9 4.3
NMSB_58 896.6 896.4
NMSB_59 byd 866.8 866.5
NMSB_6 pond 835.9 842.6 6.7 841.4 5.5
NMSB_62 pond 835.6 841.1 5.5 840.2 4.6
NMSB_63 hwy ditch 870.3 868.7
NMSB_64 hwy ditch 870.7 867.2
NMSB_65 hwy ditch 868.4 865.6
NMSB_66 street 867.9 867.7
NMSB_67 street 910.1 909.9
NMSB_7 pond 836.3 841.3 5.0 840.3 4.0
NMSB_70 byd 863.1 862.9
NMSB_71 hwy ditch 867.9 863.3
NMSB_72 864.4 864.3
NMSB_73 ditch 867.9 863.7
NMSB_74 862.0 860.4
NMSB_75 street 874.6 873.2
NMSB_76 862.9 862.1
NMSB_78 864.1 863.7
NMSB_79 868.0 867.2
NMSB_8 pond 842.4 845.0 2.6 844.2 1.8
NMSB_80 876.1 876.1
NMSB_81 hwy ditch 869.1 866.1
NMSB_82 depression 879.4 878.8
NMSB_83 street 861.8 861.1
NMSB_84 street 861.8 861.1
NMSB_85 creek 841.2 840.3
NMSB_86 pond 828.4 834.8 6.4 833.4 5.0
NMSB_87 wetland 863.0 867.9 4.9 865.2 2.2
NMSB_88 880.9 880.6
NMSB_90 wetland 839.0 845.0 6.0 844.2 5.2
Table 9.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Nine Mile South Fork
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
NMSB_91 street 871.0 868.2
NMSB_92 870.8 868.4
NMSB_93 883.0 883.0
NMSB_94 871.7 871.6
NMSB_95 871.2 871.0
NMSB_96 street 871.0 870.5
NMSB_97 871.7 871.2
NMSB_98 894.7 894.5
NMSB_99 depression 872.6 871.3
PA_1 pond 864.0 869.2 5.2 867.1 3.1
PA_10 893.6 893.3
PA_11 byd 884.0 882.0
PA_12 street 880.6 875.3
PA_13 byd 890.0 ¹ 888.5
PA_2 byd 886.8 885.6
PA_3 street 877.0 875.9
PA_4 byd 873.9 870.1
PA_5 890.2 889.9
PA_6 pond 872.5 877.6 5.1 875.2 2.7
PA_7 depression 880.4 878.0
PA_8 street/byd 879.8 873.1
PA_9 wetland 885.0** 889.7 4.7 887.2 2.2
§¨¦494
£¤21262
4567158
Indian
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Braemer Blvd Flying Cloud Dr
Eden PrairieEden Prairie
BloomingtonBloomington
MinnetonkaMinnetonka
NorthBranchNineMileCreek
SouthBran ch N i ne M il e Creek
EP_2
EP_1
AH_1
IH_1
NMSB_73
BRCrk3
BRCrk17
BRCrk15
IH_3
BRCrk16
IH_6
NMSB_90
NMSB_5
NMSB_68
NMSB_3
AH_6
NMSB_86
NMSB_57
NMSB_4
BRCrk4
NMSB_85
BA_3
BRCrk13
NMSB_30
PA_3
BRCrk18
BA_6
BRCrk12
PA_1
NMSB_45
AH_22
NMSB_12
NMSB_20
NMSB_8
AH_3
IH_10
NMSB_83
BA_1
IH_12
AH_32
NMSB_66
AH_21
AH_7
IH_8
NMSB_22
AH_20
AH_9
NMSB_87
AH_23
NMSB_72 NMSB_34
IH_13
NMSB_13
IH_14
NMSB_18
NMSB_23
AH_17
PA_8
NMSB_19
PA_6
AH_28
NMSB_43
AH_25
NMSB_32
AH_13
AH_26
NMSB_41
NMSB_14
NMSB_95
AH_30
NMSB_67NMSB_78
NMSB_2
BA_2
NMSB_39
NMSB_33
IH_15
NMSB_37
NMSB_94
NMSB_77
AH_33
NMSB_59
NMSB_35
PA_2
NMSB_17
AH_19
AH_29
NMSB_62
NMSB_97
NMSB_26
NMSB_69
AH_5
NMSB_45a
NMSB_71
NMSB_52
NMSB_31
PA_5
AH_24
NMSB_42
IH_11
NMSB_99
NMSB_27
NMSB_36
NMSB_58
NMSB_40
NMSB_51
NMSB_21
PA_10
AH_18
NMSB_29
PA_12
PA_9
NMSB_84NMSB_70
AH_10
NMSB_16
IH_5
NMSB_7
NMSB_63
NMSB_64
NMSB_47
PA_4
NMSB_82
PA_7
AH_31
NMSB_28
NMSB_91
NMSB_15
AH_12
AH_27
NMSB_45b
NMSB_24
AH_4
AH_11
NMSB_6
NMSB_50
IH_7
NMSB_88
AH_15
NMSB_96
NMSB_75
PA_11
NMSB_76
NMSB_11
NMSB_25
NMSB_38
NMSB_65
NMSB_79
NMSB_46
AH_8
NMSB_93
NMSB_98
PA_13
NMSB_74
AH_16
NMSB_44
NMSB_49
NMSB_80
NMSB_92
NMSB_10
Arrowhead Lake
Indianhead Lake
Barr Footer: ArcGIS 10.4.1, 2017-09-21 11:57 File: \\barr.com\gis\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_9_1_NMC_South_Fork_Drainage_Basins.mxd User: rcs2FIGURE 9.1
0 1,200
Feet
!;N
Nine Mile - South ForkDrainage Basin
Subwatershed
Streets and Highways
Creek/Stream
City of Edina Boundary
Lake/Wetland
Imagery Source: MnGeo; 2016
NINE MILE - SOUTH FORKDRAINAGE BASINComprehensiveWater ResourcesManagement PlanCity of Edina, Minnesota
§¨¦494
£¤21262
4567158
Indian
H
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R
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Braemer Blvd Flying Cloud Dr
Nine Mile South Fork
Eden Prairie Arrowhead Lake
Indianhead
Pawnee Pond
Braemer Arena/Public Works
Eden PrairieEden Prairie
BloomingtonBloomington
MinnetonkaMinnetonka
NorthBranchNineMileCreek
SouthBran ch N i ne M il e Creek
Arrowhead Lake
Indianhead Lake
Barr Footer: ArcGIS 10.4.1, 2017-09-21 12:10 File: \\barr.com\gis\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_9_2_NMC_South_Fork_Major_Watersheds.mxd User: rcs2FIGURE 9.2
0 1,200
Feet
!;N
Nine Mile - South ForkDrainage Basin
Major Watershed
Arrowhead Lake
Braemer Arena/Public Works
Eden Prairie
Indianhead
Nine Mile South Fork
Pawnee Pond
Subwatershed
Streets and Highways
Creek/Stream
City of Edina Boundary
Lake/Wetland
Imagery Source: MnGeo; 2016
NINE MILE - SOUTH FORKMAJOR WATERSHEDSComprehensiveWater ResourcesManagement PlanCity of Edina, Minnesota
City of Edina 2018 Comprehensive Water Resources Management Plan
9-24
Figure 9.3 Nine Mile South Fork Hydraulic Model Results
This is a large drawing (34x44).
Due to the paper and size and file size, this figure is included as a stand-alone PDF.
PA_1
PA_6
NMSB_2 NMSB_6
NMSB_7
NMSB_5
NMSB_62
NMSB_86
NMSB_34
NMSB_59
NMSB_15
NMSB_33NMSB_3
NMSB_3 NMSB_85
NMSB_85
NMSB_12
NMSB_12
NMSB_57
NMSB_57
EP_2A
NMSB_90 NMSB_8
EP_2B
EP_1
PA_9
IH_1
IH_14
AH_4
AH_6
AH_1
AH_32
BA_6
SouthB r a n c h NineMile C re e k
N ort h B r a nch NineMil
e
Creek
BloomingtonBloomington
Eden PrairieEden Prairie
MinnetonkaMinnetonka
Barr Footer: ArcGIS 10.4.1, 2018-03-26 11:28 File: I:\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_9_4_NMC_South_Fork_Water_Quality.mxd User: EMANINE MILE CREEK SOUTH FORKWATER QUALITY MODELING RESULTSComprehensive Water ResourceManagement PlanCity of Edina, Minnesota
FIGURE 9.4
1,200 0 1,200Feet
400 0 400Meters
Percent TP Removal in Water Body*This number represents the percent of the total annual massof phosphorus entering the water body that is removed.
Cumulative TP Removal in Watershed*This number represents the percent of the total annual massof phosphorus entering the watershed and upstream watershedsthat is removed in the pond and all upstream ponds.
*Data based on results of 2003 P8 modeling.
0 - 25% (Poor/No Treatment)
25 - 40% (Moderate Removal)
40 - 60% (Good Removal)
60 - 100% (Excellent Removal)
0 - 25% (Poor/No Treatment)
25 - 40% (Moderate Removal)
40 - 60% (Good Removal)
60 - 100% (Excellent Removal)
Imagery Source: USDA 2016 NAIP via MnGeo
Area Draining Directly to the SouthFork of Nine Mile Creek
Flow Direction
City of Edina 2018 Comprehensive Water Resources Management Plan
10-1
10.0 Southwest Ponds (Dewey Hill Road Area)
10.1 General Description of Drainage Area
Figure 10.1 depicts the drainage area to the Southwest Ponds drainage basin and the individual
subwatersheds within this area. The Southwest Ponds watershed is located in southwest Edina, bordered
by West 70th Street to the north, West 78th Street to the south, Gleason Road on the west, and the Soo
Line railroad on the east. The drainage basin encompasses approximately 461 acres that ultimately drain
to the South Fork of Nine Mile Creek south of West 78th Street.
10.1.1 Drainage Patterns
The stormwater system within this drainage area comprises storm sewers, ditches, overland flow paths,
wetlands, and ponding basins. The Southwest Ponds drainage basin has been divided into two major
watersheds based on the drainage patterns. These major watersheds are depicted on Figure 10.2. Each
major watershed has been further delineated into numerous subwatersheds. The naming convention for
each subwatershed is based on the major watershed where it is located. Table 10.1 lists each major
watershed and the associated subwatershed naming convention.
Table 10.1 Major Watersheds within the Southwest Ponds Drainage Basin
Major Watershed
Subwatershed
Naming Convention
Number of
Subwatersheds
Drainage Area
(acres)
Southwest Ponds SWP_## 67 411
Nine Mile—I-494 NM494_## 7 50
10.1.1.1 Southwest Ponds
The Southwest Ponds watershed encompasses approximately 411 acres. The land use within the
watershed is mainly low- and medium-density residential, in addition to the commercial and industrial
area along Cahill Road and Lewis Park (the eastern portion of the watershed). The watershed is
characterized by a series of ponding basins that outlet to the South Fork of Nine Mile Creek via a storm
sewer system that travels south from the intersection of West 78th Street and Delaney Boulevard and
discharges to a detention pond north of I-494. Discharge from this detention pond flows beneath I-494
and enters the South Fork of Nine Mile Creek.
10.1.1.2 Nine Mile I-494
The Nine Mile I-494 watershed encompasses approximately 50 acres. The land use within the watershed is
mainly low- and medium-density residential. There is one stormwater detention basin within the
watershed. The watershed ultimately drains to the South Fork of Nine Mile Creek through a storm sewer
system that discharges to the creek southeast of the intersection of Marth Court and West 78th Street, on
the north side of I-494
City of Edina 2018 Comprehensive Water Resources Management Plan
10-2
10.2 Stormwater System Results
10.2.1 Hydrologic/Hydraulic Modeling Results
The 10- and 1-percent-annual-chance flood analyses were performed for the Southwest Ponds drainage
basin. The 10-percent-annual-chance event was based on a ½-hour storm with 1.65 inches of rain. The
1-percent-annual-chance analysis was based on a 24-hour storm event with 7.47 inches of rain and on a
10-day snowmelt event with 7.2 inches of runoff; the higher resulting flood level of the two events was
chosen for the 1-percent-annual-chance analysis. Table 10.2 presents the watershed information and the
results for the 10- and 1-percent-annual-chance hydrologic analyses for the Southwest Ponds basin. A
more detailed description of the stormwater system analysis is provided in Section 4.1.3.
The results of the 10- and 1-percent-annual-chance hydraulic analysis for the Southwest Ponds drainage
basin are summarized in Table 10.3.
Figure 10.3 illustrates the results of the 10- and 1-percent-annual-chance hydraulic analyses. The figure
depicts the Southwest Ponds drainage basin boundary, subwatershed boundaries, the modeled storm
sewer network, surcharge conditions for the XP-SWMM nodes (typically manholes), and the flood-prone
areas identified in the modeling analyses.
Figure 10.3 illustrates that several XP-SWMM nodes within the Southwest Ponds drainage basin are
predicted to surcharge during both the 10- and 1-percent-annual-chance event. This means that in any
year there is a greater than 10 percent probability that the system will be overburdened and unable to
meet the desired level of service at these locations. These manholes and catch basins are more likely to
become inundated during the smaller, more frequent storm events of various durations.
To evaluate the level of protection of the stormwater system within the Southwest Ponds drainage area,
the 1-percent-annual-chance flood elevations for the ponding basins and depressed areas were
compared to the low elevations of structures surrounding each basin. The areas predicted to potentially
flood and threaten structures during the 1-percent-annual-chance storm event are shown on Figure 10.3.
Discussion and recommended improvement considerations for these areas are included in Section 10.3.
10.2.2 Water Quality Modeling Results
The effectiveness of the stormwater system in removing stormwater pollutants such as phosphorus was
analyzed using the P8 water quality model. The P8 model simulates the hydrology and phosphorus loads
introduced from each pond’s watershed and the transport of phosphorus throughout the stormwater
system. A more detailed description of the stormwater system analysis is provided in Section 4.1.3.
Figure 10.4 depicts the results of the water quality modeling for the Southwest Ponds drainage basin. The
figure shows the fraction of total phosphorus removal for each water body as well as the cumulative total
phosphorus removal in the watershed.
City of Edina 2018 Comprehensive Water Resources Management Plan
10-3
10.3 Implementation Considerations
The 2017 XP-SWMM hydrologic and hydraulic modeling analyses and 2003 P8 water quality analysis
helped identify locations throughout the watershed where improvements to the City’s stormwater
management system may be warranted. The following sections discuss potential improvement options
identified as part of the modeling analyses. As opportunities to address identified flooding issues and
improve water quality arise (e.g., street reconstruction projects or public facilities improvements), the City
will use a comprehensive approach to stormwater management. This approach will include consideration
of infiltration or volume retention practices to address flooding and/or improve water quality, reduction of
impervious surfaces, increased storm sewer capacity where necessary to alleviate flooding, construction
and/or expansion of water quality basins, and implementation of other stormwater BMPs to reduce
pollutant loading to downstream waterbodies.
10.3.1 Flood Protection Projects
The 2017 hydrologic and hydraulic modeling analyses identified several locations within the Southwest
Ponds drainage basin where the 1-percent-annual-chance level of protection is not provided by the
current stormwater system. The problem areas identified in 2017 are discussed below.
As part of the 2017 modeling analyses, potential corrective measures were identified for problem areas.
These preliminary corrective measures are also discussed. As the City evaluates flooding issues and
potential system modifications in these areas, other potential modifications, including (but not limited to)
implementation of volume-retention practices, increases in conveyance capacity, and/or stormwater
infiltration (where soils are conducive) will be given consideration.
The 2003 hydrologic and hydraulic modeling analyses also identified several locations within the
Southwest Ponds drainage basin where the 1-percent-annual-chance level of protection was not provided
by the stormwater system, based on TP-40 precipitation frequency estimates. The discussions related to
those areas have been carried over to Appendix C of this plan, along with a short summary of what has
been done since 2003.
10.3.1.1 Gleason Road and Bonnie Brae Drive (SWP_24)
A local depression exists in the backyards of the homes along Gleason Road, Bonnie Brae Drive, and Hyde
Park Drive, with a single 18-inch outlet positioned east. The outlet size increases to 30 inches before the
pipes discharge to the existing wet pond to the east. This pipe size increase was part of a 2015 street
reconstruction project. Modeling results indicate that flooding would occur in the backyard depression
during the 1-percent-annual-chance 24-hour storm event, with a peak flood level of 842.3 feet. Based on
LiDAR data and building footprints, two principle structures are potentially impacted by this flooding
(7501 and 7505 Gleason Road), and two principle structures are nearly potentially impacted (7436 and
7500 Hyde Park Drive). The problem is mostly caused by the limited capacity of the remaining 18-inch
storm sewer pipe.
City of Edina 2018 Comprehensive Water Resources Management Plan
10-4
The first recommendation is to survey the potentially impacted principle structures to verify the impact. If
the impacts exist, flood-proofing these eight principle structures may be the most cost-effective solution.
Alternatively, additional flood storage could be created in the City-owned parcels south of Bonnie Brae
Drive, and storm sewer could be added to connect the backyard depression to the new storage. Finally,
the remaining portion of the existing storm sewer pipe that has not be upsized could be modified to add
more outlet capacity.
10.3.2 Construction/Upgrade of Water Quality Basins
The 2003 P8 modeling analysis indicated that under average conditions the annual removal of total
phosphorus from several ponds in the Southwest Ponds drainage area was below the desired 60 percent
rate. For those ponds with total phosphorus removal below 60 percent, the permanent pool storage
volume was analyzed to determine whether additional capacity is necessary. Based on the MPCA-
recommended permanent pool storage volume for detention basins, all of the basins were found to have
sufficient dead storage volume. As a result, no specific recommendations for water quality basin upgrades
in the Southwest Ponds drainage basin are being made at this time.
Construction of new or expansion of existing water quality basins is one method to increase the pollutant
removal achieved prior to stormwater reaching downstream waterbodies. Many additional techniques are
available to reduce pollutant loading, including impervious surface reduction or disconnection,
implementation of infiltration or volume-retention BMPs, installation of underground stormwater
treatment structures and sump manholes, and other good housekeeping practices such as street
sweeping. As opportunities arise, the City will consider all of these options to reduce the volume and
improve the quality of stormwater runoff.
Table 10.2
Watershed Modeling Results for Subwatersheds in the Southwest Ponds Drainage Area
1 The 1%-Annual-Chance (100-Year) 10-day snowmelt event is defined as 7.2 inches of runoff
Watershed ID
Total Area
(ac)
% Impervious
Area
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
NM494_1 9.5 24 79 3.7 1.8 5.7 32 1.6
NM494_2 5.5 23 46 2.2 1.0 3.3 20 1.0
NM494_3 7.1 16 51 2.7 1.4 4.3 19 1.2
NM494_4 5.3 35 47 2.5 1.0 3.2 22 1.2
NM494_5 12.9 26 94 5.4 2.4 7.7 38 2.4
NM494_6 7.8 28 69 3.2 1.5 4.6 30 1.5
NM494_7 2.1 25 19 0.9 0.4 1.3 9 0.5
SWP_1 4.2 48 39 2.2 0.8 2.5 20 1.1
SWP_10 4.5 44 39 2.0 0.8 2.7 17 1.0
SWP_11 2.6 40 20 1.1 0.5 1.5 8 0.5
SWP_12 2.0 36 20 0.9 0.4 1.2 10 0.4
SWP_13 1.3 17 14 0.6 0.3 0.8 7 0.3
SWP_14 2.7 24 25 1.3 0.5 1.6 13 0.7
SWP_15 0.7 25 4 0.3 0.1 0.4 2 0.2
SWP_16 4.4 40 35 2.1 0.8 2.6 16 1.0
SWP_17 2.8 40 11 1.2 0.5 1.7 5 0.6
SWP_18 3.3 25 32 1.6 0.6 2.0 17 0.8
SWP_19 6.4 25 62 3.2 1.2 3.8 32 1.7
SWP_2 13.3 50 120 6.9 2.5 8.0 60 3.6
SWP_20 3.6 25 33 1.8 0.7 2.1 17 0.9
SWP_21 2.9 25 30 1.2 0.5 1.7 15 0.6
SWP_22 6.3 25 49 2.6 1.2 3.8 20 1.2
SWP_23 3.3 25 32 1.3 0.6 2.0 14 0.6
SWP_24 3.9 25 25 1.7 0.7 2.3 10 0.8
SWP_25 2.9 25 26 1.4 0.6 1.8 13 0.7
SWP_26 3.1 25 26 1.5 0.6 1.9 13 0.8
SWP_27 8.2 5 49 2.8 1.6 4.9 15 1.0
SWP_28 8.9 10 66 3.3 1.7 5.3 25 1.3
SWP_29 4.6 48 44 2.3 0.9 2.8 22 1.1
SWP_3 29.2 29 220 13.2 5.5 17.5 99 6.3
SWP_30 2.5 37 18 1.1 0.5 1.5 7 0.5
SWP_31 11.0 56 92 5.8 2.1 6.6 45 3.1
SWP_32 23.6 69 185 12.5 4.5 14.1 87 6.6
SWP_33 2.3 40 20 1.1 0.4 1.3 10 0.6
SWP_34 16.8 31 146 8.2 3.2 10.0 72 4.1
SWP_35 11.3 37 93 5.7 2.2 6.8 45 2.9
SWP_36 7.7 25 74 3.2 1.5 4.6 35 1.5
SWP_37 2.3 48 21 1.2 0.4 1.4 11 0.6
SWP_38 4.7 25 42 1.9 0.9 2.8 18 0.8
SWP_39 13.0 25 110 5.2 2.5 7.8 46 2.3
SWP_4 13.0 41 116 6.6 2.5 7.8 58 3.4
SWP_40 2.6 44 27 1.3 0.5 1.6 13 0.6
SWP_41 2.5 65 28 1.3 0.5 1.5 14 0.7
SWP_42 4.3 51 33 2.0 0.8 2.6 14 1.0
SWP_43 3.7 60 29 1.8 0.7 2.2 13 0.9
SWP_44 2.4 71 19 1.4 0.5 1.5 9 0.7
SWP_45 1.4 74 11 0.8 0.3 0.8 5 0.4
SWP_46 6.2 56 50 3.2 1.2 3.7 24 1.6
SWP_46x 5.4 72 46 3.0 1.0 3.3 23 1.6
SWP_47 21.5 27 122 9.3 4.1 12.9 49 4.2
SWP_48 0.8 30 9 0.3 0.2 0.5 5 0.2
SWP_49 3.7 25 35 1.5 0.7 2.2 16 0.7
SWP_5 6.5 61 72 3.5 1.2 3.9 39 1.9
SWP_50 8.4 25 66 3.4 1.6 5.0 27 1.5
SWP_51 6.9 25 52 2.8 1.3 4.1 21 1.3
SWP_52 8.2 25 70 3.3 1.6 4.9 29 1.5
SWP_53 13.5 25 96 5.6 2.6 8.1 39 2.5
SWP_54 12.3 25 108 4.9 2.3 7.4 45 2.2
SWP_55 3.5 25 30 1.5 0.7 2.1 14 0.7
SWP_56 7.5 25 62 3.3 1.4 4.5 28 1.5
Watershed Information 1%-Annual-Chance (100-Year)1%-Annual-Chance (100-Year)10%-Annual-Chance (10-Year)
24-Hour Precipitation Event 10-day Snowmelt Event1 24-Hour Precipitation Event
Table 10.2
Watershed Modeling Results for Subwatersheds in the Southwest Ponds Drainage Area
1 The 1%-Annual-Chance (100-Year) 10-day snowmelt event is defined as 7.2 inches of runoff
Watershed ID
Total Area
(ac)
% Impervious
Area
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Watershed Information 1%-Annual-Chance (100-Year)1%-Annual-Chance (100-Year)10%-Annual-Chance (10-Year)
24-Hour Precipitation Event 10-day Snowmelt Event1 24-Hour Precipitation Event
SWP_57 1.6 40 16 0.7 0.3 0.9 7 0.3
SWP_58 2.0 40 19 1.0 0.4 1.2 10 0.5
SWP_59 7.2 51 66 3.9 1.4 4.3 34 2.1
SWP_59a 4.6 40 40 2.1 0.9 2.8 18 1.0
SWP_6 5.1 25 34 2.1 1.0 3.0 14 0.9
SWP_60 9.8 39 50 4.5 1.8 5.9 21 2.2
SWP_61 5.3 25 46 2.2 1.0 3.2 20 1.0
SWP_62 1.7 25 17 0.7 0.3 1.0 8 0.3
SWP_63 6.9 13 44 2.6 1.3 4.2 16 1.1
SWP_64 2.1 68 21 1.2 0.4 1.3 11 0.7
SWP_66 4.6 25 29 1.8 0.9 2.7 11 0.8
SWP_7 1.7 36 16 0.8 0.3 1.0 8 0.4
SWP_8 2.6 39 26 1.2 0.5 1.5 13 0.6
SWP_9 2.2 25 24 1.0 0.4 1.3 12 0.4
Table 10.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Southwest Ponds Drainage
Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1171 937.5 936.6
1172 932.9 930.2
1173 928.7 927.3
1174 924.0 922.9
1175 923.9 921.6
1176 921.4 919.7
1177 914.2 914.1
1178 897.4 897.2
1180 884.1 883.6
1182 886.6 886.3
1183 890.2 890.0
1184 894.7 894.4
1185 897.1 896.9
1186 880.9 877.1
1187 871.2 868.4
1188 854.5 854.3
1190 848.8 847.4
1191 847.1 845.5
1192 845.2 843.1
1193 842.8 840.1
1197 842.5 842.5
1198 846.4 846.4
1205 837.7 834.6
1207 836.3 833.8
1208 834.9 833.1
1210 834.6 833.1
1211 834.4 833.1
1212 834.4 833.1
1215 834.4 833.1
1216 834.4 833.1
1219 837.7 835.7
1267 844.4 843.2
1270 841.2 839.9
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
Table 10.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Southwest Ponds Drainage
Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
1271 841.0 839.5
1276 845.1 842.2
1277 street 846.4 843.4
1283 832.1 831.7
1285 831.1 829.8
1286 830.8 829.4
1289 838.1 837.5
1290 841.1 838.2
1291 841.1 838.3
1292 841.4 839.2
1295 842.7 841.0
1296 842.7 840.7
1299 835.0 834.9
1306 834.0 833.4
1310 834.4 831.9
1318 830.1 829.0
132 837.8 835.0
1322 834.3 831.7
1326 825.8 825.8
1327 825.3 825.3
1328 825.1 825.1
1330 822.5 822.2
1344 834.4 832.8
1350 835.9 834.3
1354 833.1 831.2
1356 832.0 829.7
1660 901.9 901.4
1661 924.2 920.4
1662 938.7 934.4
1663 949.2 944.8
1665 925.1 923.0
1667 927.6 924.9
1676 834.8 834.6
Table 10.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Southwest Ponds Drainage
Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
1678 834.4 833.1
1856 845.6 845.4
1857 846.1 845.8
1859 846.4 843.7
1860 846.4 844.9
1866 845.3 844.0
1894 825.5 825.5
1895 827.2 827.0
2424 838.0 837.5
2425 837.9 837.5
2426 837.8 837.5
2492 834.4 833.1
2494 ditch 944.3 940.2
2497 835.4 834.0
2498 835.4 833.6
2499 834.5 833.4
BRCrk17 832.0 830.8
BRCrk17.1 830.3 829.2
ED7131 834.4 832.8
FID1348 839.8 838.0
FID6116 923.2 921.0
FID6117 934.5 929.6
FID6453 832.0 829.4
NM494_2 841.1 838.0
NM494_3 837.7 837.5
NM494_4 pond 828.2 833.7 5.6 831.7 3.6
NM494_5 832.0 831.3
NM494_6 833.5 833.0
NM494_7 byd 842.0 840.4
NMS_60 street 850.8 846.3
SWP_1 pond 827.0 827.1 0.1 827.0 0.0
SWP_10 pond 830.1 833.6 3.5 831.8 1.7
SWP_11 ditch 839.0 837.9
Table 10.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Southwest Ponds Drainage
Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
SWP_12 depression 832.0 829.4
SWP_13 833.3 830.0
SWP_14 pond 828.5 834.4 5.9 831.9 3.4
SWP_15 834.4 831.9
SWP_16 street 834.3 834.0
SWP_17 street 834.4 831.9
SWP_18 847.8 847.5
SWP_19 845.4 845.2
SWP_2 pond 828.0 828.3 0.3 828.1 0.1
SWP_20 street 838.2 837.9
SWP_21 street 834.4 832.5
SWP_22 street 845.3 844.0
SWP_23 851.8 851.7
SWP_24 byd 842.3 840.9
SWP_25 street 840.7 838.7
SWP_26 street 844.9 843.6
SWP_27 846.4 845.8
SWP_28 street 845.0 842.1
SWP_29 street 825.1 824.9
SWP_3 pond 836.5 839.7 3.2 837.9 1.4
SWP_30 street 827.9 827.7
SWP_31 pond 827.1** 829.3 ¹ 2.2 828.1 1.0
SWP_32 ditch 838.1 837.8
SWP_33 depression 839.6 ¹ 837.9
SWP_34 pond 828.0 834.4 6.4 833.1 5.1
SWP_35 pond 828.0 834.4 6.4 832.8 4.8
SWP_36 byd 835.6 835.3
SWP_37 pond 835.4** 835.4 0.0 833.3 -2.1
SWP_38 835.7 835.3
SWP_39 857.5 857.2
SWP_3OUT2 839.7 837.9
SWP_4 pond 828.6 834.0 5.4 832.4 3.8
SWP_40 pond 828.1** 837.7 9.6 835.5 7.4
Table 10.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Southwest Ponds Drainage
Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
SWP_41 840.3 833.7
SWP_42 837.6 833.6
SWP_43 836.9 833.2
SWP_44 835.8 832.8
SWP_45 street 834.4 833.4
SWP_46 street/lot 834.4 832.9
SWP_46x parking lot 834.4 832.9
SWP_47 pond 832.0 837.7 5.7 835.7 3.7
SWP_48 street 834.4 832.8
SWP_49 958.4 958.3
SWP_5 pond 828.0 834.4 6.4 831.9 3.9
SWP_5_OUT 834.4 831.9
SWP_50 898.8 898.5
SWP_51 851.6 851.1
SWP_52 depression 945.0 940.1
SWP_53 street 851.1 849.9
SWP_54 884.7 884.6
SWP_55 street 941.5 939.8
SWP_56 884.8 884.5
SWP_57 pond 836.0 839.1 ¹ 3.1 837.4 1.4
SWP_58 depression 840.6 ¹ 839.5
SWP_59 wetland 828.7 831.8 3.1 830.6 1.9
SWP_59a street/lot 836.0 835.8
SWP_6 byd 842.7 842.3
SWP_60 parking lot 837.7 835.7
SWP_61 street 842.7 840.7
SWP_62 byd 845.0 ¹ 842.7
SWP_63 depression 834.9 833.0
SWP_64 parking lot 835.7 835.2
SWP_66 street 849.4 849.1
SWP_7 834.0 830.7
SWP_8 street 835.1 834.9
SWP_9 depression 829.6 ¹ 827.7
Table 10.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Southwest Ponds Drainage
Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
WBlmCrk1a 828.0 827.4
WBlmCrk1b 826.7 826.2
§¨¦494
100
456728 Gleason Rd W 70th St Cahill Rd Dewey Hill Rd
78th St
BloomingtonBloomington North
B
ra
n
c
h
NineMileCreek
SouthB ranch Nine Mile Creek
SWP_3
SWP_32
SWP_47
SWP_34
SWP_2
SWP_4
SWP_53
SWP_39
SWP_54
NM494_5
SWP_35
SWP_31
SWP_60
SWP_28
NM494_1
SWP_50
SWP_52
SWP_27
SWP_36
SWP_56
SWP_5
SWP_59
NM494_6
SWP_63
SWP_51
NM494_3
SWP_19
SWP_22
SWP_46
SWP_6
SWP_61
NM494_2
NM494_4
SWP_46x
SWP_1
SWP_38
SWP_29
SWP_66
SWP_10
SWP_16
SWP_42
SWP_59a
SWP_49
SWP_43
SWP_55
SWP_18SWP_26
SWP_25
SWP_14
SWP_40
SWP_11
SWP_9
SWP_44
SWP_37
SWP_33 SWP_58
SWP_7
SWP_57
SWP_24
SWP_20
SWP_23
SWP_8
SWP_21
SWP_17
SWP_41
SWP_30
SWP_64
SWP_12
NM494_7
SWP_62
SWP_45
SWP_13
SWP_48
SWP_15
Barr Footer: ArcGIS 10.4.1, 2017-09-21 12:11 File: \\barr.com\gis\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_10_1_SW_Ponds_Drainage_Basins.mxd User: rcs2FIGURE 10.1
0 800
Feet
!;N
Southwest PondsDrainage Basin
Subwatershed
Streets and Highways
Creek/Stream
City of Edina Boundary
Lake/Wetland
Imagery Source: MnGeo; 2016
SOUTHWEST PONDSDRAINAGE BASINComprehensiveWater ResourcesManagement PlanCity of Edina, Minnesota
§¨¦494
100
456728 Gleason Rd W 70th St Cahill Rd Dewey Hill Rd
78th St
Southwest Ponds
Nine Mile - 494
BloomingtonBloomington North
B
ra
n
c
h
NineMileCreek
SouthB ranch Nine Mile Creek
Barr Footer: ArcGIS 10.4.1, 2017-09-21 12:12 File: \\barr.com\gis\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_10_2_SW_Ponds_Major_Watersheds.mxd User: rcs2FIGURE 10.2
0 800
Feet
!;N
Southwest PondsDrainage Basin
Major Watersheds
Nine Mile - 494
Southwest Ponds
Subwatershed
Streets and Highways
Creek/Stream
City of Edina Boundary
Lake/Wetland
Imagery Source: MnGeo; 2016
SOUTHWEST PONDSMAJOR WATERSHEDSComprehensiveWater ResourcesManagement PlanCity of Edina, Minnesota
City of Edina 2018 Comprehensive Water Resources Management Plan
10-15
Figure 10.3 Southwest Ponds Hydraulic Model Results
This is a large drawing (34x44).
Due to the paper and size and file size, this figure is included as a stand-alone PDF.
NM494_4
SWP_40
SWP_47
SWP_37
SWP_34
SWP_35
SWP_3
SWP_3
SWP_14
SWP_5
SWP_59SWP_4
SWP_2
SWP_10
SWP_31
SWP_1
SWP_33 SWP_58
SWP_57
SWP_9
Nine
M
ile
C
ree
k
N i n e MileCreek
Barr Footer: ArcGIS 10.4.1, 2018-03-26 11:28 File: I:\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_10_4_SW_Ponds_Water_Quality_Rev052014.mxd User: EMASOUTHWEST PONDSWATER QUALITY MODELING RESULTSComprehensive Water ResourceManagement PlanCity of Edina, Minnesota
FIGURE 10.4
600 0 600Feet
200 0 200Meters
Percent TP Removal in Water Body*This number represents the percent of the total annual massof phosphorus entering the water body that is removed.
Cumulative TP Removal in Watershed*This number represents the percent of the total annual massof phosphorus entering the watershed and upstream watershedsthat is removed in the pond and all upstream ponds.
*Data based on results of 2003 P8 modeling.
0 - 25% (Poor/No Treatment)
25 - 40% (Moderate Removal)
40 - 60% (Good Removal)
60 - 100% (Excellent Removal)
0 - 25% (Poor/No Treatment)
25 - 40% (Moderate Removal)
40 - 60% (Good Removal)
60 - 100% (Excellent Removal)
Imagery Source: USDA 2016 NAIP via MnGeo
Area Draining Directly to the SouthFork of Nine Mile Creek
Flow Direction
City of Edina 2018 Comprehensive Water Resources Management Plan
11-1
11.0 TH 169 North
11.1 General Description of Drainage Area
Figure 11.1 depicts the TH 169 North drainage area and the individual subwatersheds within this area.
The TH 169 North drainage area is located in the northwest corner of Edina. The drainage area
encompasses approximately 141 acres that ultimately drain to the TH 169 drainage system.
11.1.1 Drainage Patterns
The stormwater system within this drainage area comprises storm sewers, ditches, overland flow paths,
and ponding basins. Stormwater from this drainage area ultimately flows to the TH 169 storm sewer
system at several locations along TH 169 between the intersection of the highway with Malibu Drive and
the Edina City limits. The TH 169 North drainage basin has only one major watershed, also referred to as
TH 169 North (Figure 11.2). The drainage area has been delineated into 24 subwatersheds. Table 11.1
describes the naming convention for subwatersheds within the drainage area. Land use within the
drainage area includes low-density residential, open area, Van Valkenburg Park, and a small commercial
area.
Table 11.1 Major Watershed within the TH 169 North Drainage Area
Major Watershed
Subwatershed Naming
Convention Number of Subwatersheds Drainage Area (acres)
TH 169 North 169N_## 24 141
11.2 Stormwater System Results
11.2.1 Hydrologic/Hydraulic Modeling Results
The 10-percent-annual-chance and 1-percent-annual-chance flood analyses were performed for the
TH 169 North drainage area. The 10-percent-annual-chance analysis was based on a ½-hour storm with
1.65 inches of rain. The 1-percent-annual-chance analysis was based on a 24-hour storm event with
7.47 inches of rain and on a 10-day snowmelt event with 7.2 inches of runoff; the higher resulting flood
level of the two events was chosen for the 1-percent-annual-chance analysis. Table 11.2 presents the
watershed information and the results for the 10- and 1-percent-annual-chance hydrologic analyses for
the TH 169 North drainage area. A more detailed description of the stormwater system analysis is
provided in Section 4.1.3.
The results of the 10- and 1-percent-annual-chance hydraulic analysis for the TH 169 North drainage area
are summarized in Table 11.3.
Figure 11.3 illustrates the results of the 10- and 1-percent-annual-chance hydraulic analyses. The figure
depicts the TH 169 North drainage area boundary, subwatershed boundaries, the modeled storm sewer
City of Edina 2018 Comprehensive Water Resources Management Plan
11-2
network, surcharge conditions for the XP-SWMM nodes (typically manholes), and the flood-prone areas
identified in the modeling analyses.
Figure 11.3 illustrates that several XP-SWMM nodes within the TH 169 North drainage area are predicted
to surcharge during both the 10- and 1-percent-annual-chance events. This means that in any year there
is a greater than 10 percent probability that the system will be overburdened and unable to meet the
desired level of service at these locations. These manholes and catch basins are more likely to become
inundated during the smaller, more frequent storm events of various durations.
To evaluate the level of protection of the stormwater system within the TH 169 North drainage area, the
1-percent-annual-chance flood elevations for the ponding basins and depressed areas were compared to
the low elevations of structures surrounding each basin. At this time, none of the areas in the TH 169
North drainage area have been evaluated for flood protection improvements.
11.2.2 Water Quality Modeling Results
The effectiveness of the stormwater system in removing stormwater pollutants such as phosphorus was
analyzed using the P8 water quality model. The P8 model simulates the hydrology and phosphorus loads
introduced from each pond’s watershed and the transport of phosphorus throughout the stormwater
system. A more detailed description of the stormwater system analysis is provided in Section 4.1.3.
Figure 11.4 depicts the results of the water quality modeling for the TH 169 North drainage area. The
figure shows the fraction of total phosphorus removal for each water body as well as the cumulative total
phosphorus removal in the watershed.
11.3 Implementation Considerations
The 2017 XP-SWMM hydrologic and hydraulic modeling analyses and 2003 P8 water quality analysis
helped identify locations throughout the watershed where improvements to the City’s stormwater
management system may be warranted. The following sections discuss potential improvement options
identified as part of the modeling analyses. As opportunities to address identified flooding issues and
improve water quality arise (e.g., street reconstruction projects or public facilities improvements), the City
will use a comprehensive approach to stormwater management. This approach will include consideration
of infiltration or volume retention practices to address flooding and/or improve water quality, reduction of
impervious surfaces, increased storm sewer capacity where necessary to alleviate flooding, construction
and/or expansion of water quality basins, and implementation of other stormwater BMPs to reduce
pollutant loading to downstream waterbodies.
11.3.1 Flood Protection Projects
The 2017 hydrologic and hydraulic modeling analyses identified several locations within the TH 169 North
drainage basin where the 1-percent-annual-chance level of protection is not provided by the current
stormwater system. However, at this time, none of those areas have been evaluated further to identify
possible improvement options. It is recommended that those areas be evaluated in the future.
City of Edina 2018 Comprehensive Water Resources Management Plan
11-3
11.3.2 Construction/Upgrade of Water Quality Basins
The 2003 P8 modeling analysis indicated that under average conditions the predicted annual removal of
total phosphorus from Pond 169N_16 in the TH 169 North drainage area was below the desired
60 percent removal rate. The permanent pool storage volume was analyzed to determine whether
additional capacity was necessary. Based on the MPCA-recommended volume of permanent pool storage
for removal of particulate phosphorus, the basin was found to have sufficient dead storage volume. As a
result, no specific recommendations for water quality basin upgrades in the TH 169 North drainage area
are being made at this time.
Construction of new or expansion of existing water quality basins is one method to increase the pollutant
removal achieved prior to stormwater reaching downstream waterbodies. Many additional techniques are
available to reduce pollutant loading, including impervious surface reduction or disconnection,
implementation of infiltration or volume-retention BMPs, installation of underground stormwater
treatment structures and sump manholes, and other good housekeeping practices such as street
sweeping. As opportunities arise, the City will consider all of these options to reduce the volume and
improve the quality of stormwater runoff.
Table 11.2
Watershed Modeling Results for Subwatersheds in the TH 169 North Drainage Area
1 The 1%-Annual-Chance (100-Year) 10-day snowmelt event is defined as 7.2 inches of runoff
Watershed ID
Total Area
(ac)
% Impervious
Area
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
169N_1 4.1 25 35 1.9 0.8 2.5 17 0.9
169N_10 6.4 24 56 2.9 1.2 3.9 27 1.4
169N_11 8.5 25 59 3.8 1.6 5.1 26 1.8
169N_12 13.1 15 93 5.6 2.5 7.8 42 2.6
169N_13 12.0 12 76 5.0 2.3 7.2 32 2.3
169N_14 3.3 25 31 1.5 0.6 2.0 16 0.7
169N_15 7.7 0 51 3.1 1.5 4.6 22 1.3
169N_16 2.4 32 23 1.1 0.4 1.4 12 0.5
169N_17 19.5 17 137 8.3 3.7 11.7 60 3.9
169N_18 2.5 78 27 1.5 0.5 1.5 14 0.8
169N_18a 2.5 24 26 1.1 0.5 1.5 14 0.5
169N_19 4.2 10 35 1.7 0.8 2.5 16 0.8
169N_2 1.0 25 11 0.5 0.2 0.6 6 0.2
169N_20 7.4 25 58 3.3 1.4 4.4 27 1.6
169N_21 3.2 25 19 1.4 0.6 1.9 8 0.7
169N_22 5.3 67 52 2.9 1.0 3.2 27 1.6
169N_23 6.5 0 45 2.7 1.2 3.9 20 1.2
169N_3 2.0 25 17 0.9 0.4 1.2 8 0.4
169N_4 9.4 25 61 4.3 1.8 5.7 27 2.1
169N_5 3.1 28 29 1.4 0.6 1.8 15 0.7
169N_6 1.0 22 12 0.4 0.2 0.6 6 0.2
169N_7 3.6 31 29 1.7 0.7 2.1 14 0.9
169N_8 2.1 25 21 0.9 0.4 1.2 11 0.5
169N_9 10.2 23 58 4.4 1.9 6.1 24 2.1
Watershed Information 1%-Annual-Chance (100-Year)1%-Annual-Chance (100-Year)10%-Annual-Chance (10-Year)
24-Hour Precipitation Event 10-day Snowmelt Event1 24-Hour Precipitation Event
Table 11.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the TH 169 North Drainage
Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
124.1 938.5 938.3
1395 940.8 938.6
1399_e byd 939.7 938.6
1400_e 937.7 934.2
1401_e 937.4 933.4
1402_e 937.0 932.5
1406_e 924.5 922.7
1413_e 932.8 932.3
1416 915.8 914.7
1416_e 928.1 927.9
1420 912.7 912.6
1427_e 932.6 932.3
1428 909.5 908.0
1428_e 929.9 929.7
1429_e 923.9 923.5
1433 913.9 912.7
1434 913.9 912.7
1435_e 924.5 924.1
1436_e 921.0 920.7
1437_e 910.5 910.5
1439_e 911.1 908.6
1440_e 905.9 904.7
1441_e 905.9 904.6
167.1 918.6 917.9
168 street 918.5 917.5
169N_1 914.9 913.9
169N_10 926.1 925.9
169N_11 922.8 922.4
169N_12 935.5 935.1
169N_13 916.4 916.0
169N_14 byd 939.6 938.5
169N_15 depression 932.9 932.6
169N_16 pond 914.4 924.8 10.4 922.9 8.5
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
Table 11.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the TH 169 North Drainage
Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
169N_17 927.1 926.7
169N_18 street 905.9 904.6
169N_18a street 915.5 915.4
169N_19 910.3 910.0
169N_2 953.1 953.0
169N_20 935.1 934.9
169N_21 930.5 930.2
169N_22 street 911.4 910.7
169N_23 depression 913.9 912.8
169N_3 927.5 923.4
169N_4 byd 930.7 930.3
169N_5 street 918.3 917.5
169N_6 975.0 974.4
169N_7 street/byd 918.3 917.1
169N_8 947.2 943.2
169N_9 street 922.6 922.2
309 927.5 923.5
312 918.9 918.3
534 916.8 914.6
548 912.4 910.6
621 925.5 925.3
TH169_2 927.5 923.5
£¤169
Maloney Ave Van Buren Ave Washington Ave Interlachen Blvd
HopkinsHopkins
169N_17
169N_12169N_13
169N_9
169N_4
169N_11
169N_15
169N_20
169N_23
169N_10
169N_22
169N_1
169N_19
169N_7
169N_5
169N_14
169N_21
169N_18
169N_8
169N_16
169N_3
169N_18a
169N_2
169N_6
Barr Footer: ArcGIS 10.4.1, 2017-09-21 12:13 File: \\barr.com\gis\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_11_1_TH169_Ponds_Drainage_Basins.mxd User: rcs2FIGURE 11.1
0 500
Feet
!;N
TH 169 NorthDrainage Basin
Subwatershed
Streets and Highways
Creek/Stream
City of Edina Boundary
Lake/Wetland
Imagery Source: MnGeo; 2016
TH 169 NORTHDRAINAGE BASINComprehensiveWater ResourcesManagement PlanCity of Edina, Minnesota
£¤169
Maloney Ave Van Buren Ave Washington Ave Interlachen Blvd
TH 169 North
HopkinsHopkins
Barr Footer: ArcGIS 10.4.1, 2017-09-22 12:16 File: I:\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_11_2_TH169_Ponds_Major_Watersheds.mxd User: jrvFIGURE 11.2
0 500
Feet
!;N
TH 169 NorthDrainage Basin
Major Watershed
TH 169 North
Subwatershed
Streets and Highways
Creek/Stream
City of Edina Boundary
Lake/Wetland
Imagery Source: MnGeo; 2016
TH 169 NORTHMAJOR WATERSHEDSComprehensiveWater ResourcesManagement PlanCity of Edina, Minnesota
City of Edina 2018 Comprehensive Water Resources Management Plan
11-9
Reserved for:
Figure 11.3 TH 169 North Hydraulic Model Results
This is a large drawing (34x44).
Due to the paper and size and file size, this figure is included as a stand-alone PDF.
169N_16
169N_15
HopkinsHopkins
Barr Footer: ArcGIS 10.4.1, 2017-09-22 12:14 File: I:\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_11_4_TH169_Ponds_Water_Quality.mxd User: jrvTH 169 NORTHWATER QUALITY MODELING RESULTSComprehensive Water ResourceManagement PlanCity of Edina, Minnesota
FIGURE 11.4
400 0 400Feet
!;N
150 0 150Meters
Percent TP Removal in Water Body*This number represents the percent of the total annual massof phosphorus entering the water body that is removed.
Cumulative TP Removal in Watershed*This number represents the percent of the total annual massof phosphorus entering the watershed and upstream watershedsthat is removed in the pond and all upstream ponds.
*Data based on results of 2003 P8 modeling.
0 - 25% (Poor/No Treatment)
25 - 40% (Moderate Removal)
40 - 60% (Good Removal)
60 - 100% (Excellent Removal)
0 - 25% (Poor/No Treatment)
25 - 40% (Moderate Removal)
40 - 60% (Good Removal)
60 - 100% (Excellent Removal)
Imagery Source: USDA 2016 NAIP via MnGeo
Flow Direction
City of Edina 2018 Comprehensive Water Resources Management Plan
12-1
12.0 Northeast Minnehaha Creek
12.1 General Description of Drainage Area
Figure 12.1 depicts the Northeast Minnehaha Creek drainage area and the individual subwatersheds
within this area. The Northeast Minnehaha Creek drainage basin is located in the northeast corner of
Edina. This watershed contains a limited number of ponds and no lakes.
12.1.1 Drainage Patterns
The stormwater system within this drainage area comprises storm sewers, ponding basins, wetlands,
drainage ditches, and overland flow paths. The Northeast Minnehaha Creek basin has been divided into
several major watersheds, based on the drainage patterns. These major watersheds are depicted on
Figure 12.2. Each major watershed has been further delineated into numerous subwatersheds. The
naming convention for each subwatershed is based on the major watershed where it is located.
Table 12.1 lists each major watershed and the associated subwatershed naming convention.
Table 12.1 Major Watersheds within the Northeast Minnehaha Creek Drainage Basin
Major Watershed
Subwatershed Naming
Convention Number of Subwatersheds Drainage Area (acres)
Morningside MS_## 59 232
Minnehaha Creek North MHN_## / MHC_## 97 564
Edina Country Club ECC_## 15 116
12.1.1.1 Morningside
The 232-acre Morningside watershed is located in the northeast corner of Edina, primarily north of West
44th Street. Land use in this watershed, which includes Weber Park, is primarily single-family residential.
The Edina trunk storm sewer system through this area connects to the incoming St. Louis Park system just
southeast of Susan Lindgren Elementary School (Natchez Avenue and 41st Street). From this junction the
system runs east to the east side of Weber Park and an inlet/outlet to the Weber Park pond. The
inlet/outlet allows stormwater to flow into the basin until the head differential between the basin and
trunk sewer system results in a discharge from the basin. From the Weber Park Pond, the system drains
north to St. Louis Park and then east to connect with the Minneapolis system, eventually draining to Lake
Calhoun.
12.1.1.2 Minnehaha Creek North
The Minnehaha Creek North watershed lies primarily east of Minnehaha Creek, west of France Avenue,
north of West 54th Street and south of West 44th Street. There are only two wetlands within this 564-acre
watershed and no ponds; all other areas discharge directly to Minnehaha Creek. Land use is primarily
City of Edina 2018 Comprehensive Water Resources Management Plan
12-2
single-family residential; however, there is some commercial land adjacent to France Avenue. There is very
little open space in this watershed except for areas directly adjacent to Minnehaha Creek.
12.1.1.3 Edina Country Club
The Edina Country Club watershed is a small 116-acre watershed that encompasses the Edina Country
Club golf course and areas east of the Country Club to Minnehaha Creek. The watershed area outside of
the golf course is low-density residential and contains no ponds or wetlands; all areas discharge directly
to Minnehaha Creek. There are no known pipes connecting the ponds of the Edina Country Club to the
adjacent storm sewer network along Wooddale Avenue.
12.2 Stormwater System Results
12.2.1 Hydrologic/Hydraulic Modeling Results
The 10-, and 1-percent-annual-chance flood analyses were performed for the Northeast Minnehaha Creek
drainage basin. For the Minnehaha Creek North and the Edina Country Club drainage areas, the storm
sewers were evaluated using 10- and 1-percent-annual-chance storm events. The 10-percent-annual-
chance analysis was based on a ½-hour storm with 1.65 inches of rain. The 1-percent-annual-chance
analysis was based on a 24-hour storm event with 7.47 inches of rain and on a 10-day snowmelt event
with 7.2 inches of runoff; the higher resulting flood level of the two events was chosen for the 1-percent-
annual-chance analysis. Table 12.2 presents the watershed information and the results for the 10-, and
1-percent-annual-chance hydrologic analyses for the Northeast Minnehaha Creek basin. A more detailed
description of the stormwater system analysis is provided in Section 4.1.3.
The results of the 10-, and 1-percent-annual-chance hydraulic analyses for the Northeast Minnehaha
Creek drainage basin are summarized in Table 12.3.
Figure 12.3 illustrates the results of the 10-, and the 1-percent-annual-chance hydraulic analyses. The
figure depicts the Northeast Minnehaha Creek drainage basin boundary, subwatershed boundaries, the
modeled storm sewer network, surcharge conditions for the XP-SWMM nodes (typically manholes), and
the flood-prone areas identified in the modeling analyses.
Figure 12.3 illustrates that several XP-SWMM nodes within the Northeast Minnehaha Creek drainage
basin are predicted to surcharge during the 10- and 1-percent-annual-chance events. This means that in
any year there is a greater than 10-percent probability that the system will be overburdened and unable
to meet the desired level of service at these locations. These manholes and catch basins are more likely to
become inundated during the smaller, more frequent storm events of various durations.
To evaluate the level of protection of the stormwater system within the Northeast Minnehaha Creek
drainage area, the 1-percent-annual-chance flood elevations for the ponding basins and depressed areas
were compared to the low elevations of structures surrounding each basin. The areas predicted to
potentially flood and threaten structures during the 1-percent-annual-chance storm event are shown on
Figure 12.3.
City of Edina 2018 Comprehensive Water Resources Management Plan
12-3
Discussion and recommended improvement considerations for these areas are included in Section 12.3.
12.2.2 Water Quality Modeling Results
The effectiveness of the stormwater system in removing stormwater pollutants such as phosphorus was
analyzed using the P8 water quality model. The P8 model simulates the hydrology and phosphorus loads
introduced from each pond’s watershed and the transport of phosphorus throughout the stormwater
system. A more detailed description of the stormwater system analysis is provided in Section 4.1.3.
Figure 12.4 depicts the results of the water quality modeling for the Northeast Minnehaha Creek drainage
basin. The figure shows the fraction of total phosphorus removal for each water body as well as the
cumulative total phosphorus removal in the watershed.
12.3 Implementation Considerations
The 2017 XP-SWMM hydrologic and hydraulic modeling analyses and 2003 P8 water quality analysis
helped identify locations throughout the watershed where improvements to the City’s stormwater
management system may be warranted. The following sections discuss potential improvement options
identified as part of the modeling analyses. As opportunities to address identified flooding issues and
improve water quality arise (e.g., street reconstruction projects or public facilities improvements), the City
will use a comprehensive approach to stormwater management. This approach will include consideration
of infiltration or volume retention practices to address flooding and/or improve water quality, reduction of
impervious surfaces, increased storm sewer capacity where necessary to alleviate flooding, construction
and/or expansion of water quality basins, and implementation of other stormwater BMPs to reduce
pollutant loading to downstream waterbodies.
12.3.1 Flood Protection Projects
The 2017 hydrologic and hydraulic modeling analyses identified several locations within the Northeast
Minnehaha Creek drainage basin where the 1-percent-annual-chance level of protection is not provided
by the current stormwater system. The problem areas identified in 2017 are discussed below.
As part of the 2017 modeling analyses, potential corrective measures were identified for problem areas.
These preliminary corrective measures are also discussed below. As the City evaluates the flooding issues
and potential system modifications in these areas, other potential modifications, including (but not limited
to) implementation of volume-retention practices, increases in conveyance capacity, and/or stormwater
infiltration (where soils are conducive) will be given consideration.
The 2003 hydrologic and hydraulic modeling analyses also identified several locations within the
Northeast Minnehaha Creek drainage basin where the 1-percent-annual-chance level of protection was
not provided by the stormwater system, based on TP-40 precipitation frequency estimates. The
discussions related to those areas have been carried over to Appendix C of this plan, along with a short
summary of what has been done since 2003.
City of Edina 2018 Comprehensive Water Resources Management Plan
12-4
12.3.1.1 Indianola Avenue South of West 50th Street (MHN_72)
There is a local depression area south of West 50th Street along Indianola Avenue, which is drained by an
existing 12-inch pipe that connects to the trunk storm sewer system on West 50th Street. Modeling results
indicate that the 1-percent-annual-chance flood elevation (884.6 feet) may impact several structures in
the area, including a single family home (5021 Indianola Avenue), an apartment building (4121 W 50th
Street), and a public building (4201 W 50th Street). In addition to the potential impacts to structures, the
flood elevation exceeds the low elevation on Indianola Avenue by more than 2 feet. The flooding problem
is primarily related to the limited flow capacity of the storm sewer system—partly due to the size of the
existing pipe and number of inlets and partly due to water levels in the trunk storm sewer system that can
restrict flows.
There are several options that should be considered to reduce flood risk in this area, including installing
underground flood storage and increasing discharge capacity. Underground storage (with sufficient inlet
capacity) would reduce the flood elevation by storing flows that exceed the capacity of the existing storm
sewer system and infiltrating a portion of the runoff. Planning-level soil maps indicate that the soils in this
area are “A” soils with a high potential for infiltration. A few potential locations for installing underground
storage include the grassed field and parking lot on the east side of Indianola Avenue (0.3 acres), the
parking lot of Mercy Commons Covenant Church (0.5 acres), and the parking lot north of West 50th Street
(0.5 acres). Adding additional flow capacity, either by increasing the size of the outlet pipe and the
downstream storm sewer system to Minnehaha Creek, or by installing additional storm sewer, would also
reduce the flood elevation. If new storm sewer were installed, it could potentially be routed to the existing
storm sewer system under Halifax Avenue South. This option, however, would be contingent on
addressing the flooding problems in the Halifax area Section 12.3.1.2.
12.3.1.2 Halifax Avenue South (MHN_84, MHN_3, MHN_4, MHN_56, MHN_89, MHN_55,
MHN_61, MHN_62, MHN_87, MHN_90, and MHN_2)
Halifax Avenue South is in the Northeast Minnehaha Creek drainage area, east of Minnehaha Creek and
north of West 54th Street. The roadway, from West 54th Street up to and including West 52nd Street, is
undulating with two main low depression areas along the roadway that extend onto the adjacent
properties. The first low area is located at approximately 5320 Halifax Avenue South and the second at
approximately 5240 Halifax Avenue South. These two low areas are drained by an existing 18-inch RCP
storm sewer system. Pooled water in these two areas would have to rise high enough to flow over the
downstream crest in the road before these areas could drain. The controlling crest elevations of the
roadway at each of these areas are 879.1 feet and 879.7 feet, respectively. There is another significant
depression area at the intersection of Halifax Avenue South and West 52nd Street, with a surface overflow
elevation at approximately 878 feet to the southwest between 5200 and 5204 Halifax Avenue South. The
size of the trunk storm sewer increases to 48-inch at the intersection of Halifax Avenue and West 52nd
Street, where the storm sewer system runs along West 52nd Street to Minnehaha Creek.
Modeling results indicate that the 1-percent-annual-chance flood elevations (878.3 feet in the low areas
along Halifax Avenue South and 878.4 feet at the intersection of Halifax Avenue South and West 52nd
Street) may impact approximately 29 principle structures in this area based on LiDAR and approximate
City of Edina 2018 Comprehensive Water Resources Management Plan
12-5
building footprint data. South of West 52nd Street, these principle structures are 5300-5308, 5316, 5324,
5208-5200, 5201, and 5317-5301, 5229-5241 Halifax Avenue South, and 5200 Gorgas Avenue. Calvary
Church on the west side of France Avenue may also be impacted. North of West 52nd Street, these
principle structures are 5137-5129 and 5128-5120 Halifax Avenue South, and 5128-5112 Indianola
Avenue.
The flooding problem in this area is primarily related to the restricted storm sewer inlet capacity along
Halifax Avenue South; under existing conditions, the portion of storm sewer along Halifax Avenue South
between West 54th Street and West 52nd Street has only eight catch basins, allowing a total of
approximately 12 cfs to enter into the storm sewer system. Because the storm sewer inlet capacity is
limited, the depression areas along the road fill up until the water can overflow the controlling elevations,
which are high enough to cause impacts to the surrounding principle structures. The flooding problem is
also in part due to capacity restrictions in the downstream most pipes discharging to Minnehaha Creek.
The problem does not appear to be tailwater induced because the peak elevation in the creek at this
location is approximately 864.5 feet, roughly 14 feet lower than the peak elevation on Halifax Avenue
South.
Several system modifications were evaluated to reduce flood elevations in the Halifax Avenue South area.
The most effective improvement option is to increase the inlet capacity of the storm sewer system along
Halifax Avenue to allow more stormwater to enter the storm sewer system during. This improvement
option lowers the peak flood elevation by 0.5-1.5 feet and reduces the number of potentially impacted
principle structures in half. Peak runoff rates from each individual subwatershed in this area range from
about 20-40 cfs during the 1-percent-annual-chance 24-hour precipitation event, so providing sufficient
inlet capacity may require installation of many more catch basin inlets than typical or different catch basin
types altogether.
A second improvement option that was evaluated was regrading portions of Halifax Avenue South and
West 52nd Street to remove the controlling road crest elevations that result in the inundation of the
roadway and principle structures. This option may not be feasible for the foreseeable future because the
roadway was recently reconstructed. The potential reduction in the flood elevation would depend on the
final controlling elevations after regrading.
Another option to reduce the flood elevation(s) is installing additional gravity storm sewer to some of the
low areas near West 54th Street. In particular, subwatershed MHN_87 (backyard depression) has no piped
outlet and MHN_90 has only two catch basins. Installation of additional storm sewer running south along
Halifax to West 54th Street, then west to Minnehaha Creek, can lower the flood elevation by approximately
1.5 to 2.0 feet, preventing impacts to three principle structures within the MHN_87 subwatershed. For this
improvement scenario, a 30-inch pipe was assumed to drain the backyard depression area in
subwatershed MHN_87 and an 18-inch pipe was assumed for the MHN_90 subwatershed, both of which
tied into a new 36-inch pipe at West 54th Street to Minnehaha Creek.
City of Edina 2018 Comprehensive Water Resources Management Plan
12-6
12.3.1.3 Morningside/Weber Park (MS_26, MS_25, MS_41, MS_32, MS_44, MS_24, MS_15, MS_52, MS_53, MS_2, MS_38, MS_40, MS_54, MS_31, MS_33, MS_39a, and MS_39b)
The Morningside/Weber Park area is in the far northeastern corner of Edina, bordering St. Louis Park to
the north and Minneapolis to the east. The area is characterized by numerous backyard depressions and
several large low-lying areas, including Weber Park. There are two large stormwater detention basins in
the area, one located just north of West 42nd Street between Lynn Avenue and Kipling Avenue, and the
other located just north of West 42nd Street and west of France Avenue South (in Weber Park). The area is
drained by a piped outlet that conveys stormwater to Lake Calhoun in Minneapolis. The storm sewer and
detention basins in this area were originally designed for the 2-percent-annual-chance (50-year) storm
event using TP-40 rainfall frequency estimates. Portions of this area have experienced flood problems
historically.
Model results indicate that approximately 65 principle structures and Calvin Christian School may be
impacted by the 1-percent-annual-chance flood elevations within this area. In the west part of this area,
the flood elevation is approximately 872.1 feet (MS_26). In the southwest part of this area, the flood
elevation is approximately 871.7 feet (MS_15). In the southeast part of this area, the flood elevation is
approximately 870.1 feet (MS_52). In MS_40 and MS_39a and MS_39b, the flood elevation is 870.0 feet. In
the smaller depressions without outlets to storm sewer such as MS_58, MS_20, MS_22, MS_57, MS_17, and
MS_24, the peak flood elevations are 872.9 feet, 877.3 feet, 872.4 feet, 902.5 feet, 902.5 feet, and 872.1
feet respectively. Flood elevations in subwatersheds MS_20 and MS_22 are controlled by the 10-day
snowmelt event, while flood elevations in the remaining subwatersheds are controlled by the 24-hour
duration event.
The flood problem within this area is primarily related to insufficient outlet capacity from the area and
limited flood storage volume. To sufficiently lower water levels in this area would require the addition of
at least 35 acre-feet below some of the lowest lying areas in Morningside/Weber Park. Restricted storm
sewer pipe capacity within the Morningside/Weber Park area is a tertiary and much smaller problem,
localized to a few small areas.
Several flood improvement options were evaluated to reduce flood elevations in this area. One of the
most effective improvement options is to provide additional discharge capacity from this area to Lake
Calhoun or to another receiving water body. The addition of two 48-inch pipes from Weber Park lowers
water levels by approximately 2 feet in Weber Park and about 0.5 feet in some areas south of West 42nd
Street (e.g., MS_15, MS_18, MS_50, MS_52, and MS_53). This improvement option reduces the number of
potentially impacted principle structures by 8 structures.
Another potential flood improvement option is to add new pipes to convey runoff from subwatersheds
MS_15, MS_2, and MS_53 to the main trunk storm sewer under West 42nd Street, and double the flow
capacity of the trunk system along West 42nd Street. The additional and upsized pipes could reduce the
peak flood elevations by 0.5 to 1.5 feet, reducing the number of potentially impacted principle structures
in that immediate area by 7 structures. However, additional capacity in the upstream storm sewer system
City of Edina 2018 Comprehensive Water Resources Management Plan
12-7
could result in increased flood elevations in the low-lying area in and near Weber Park, negatively
impacting the surrounding principle structures. A closer evaluation would be needed to determine the
best pipe sizes to balance the benefit with the other impacts.
Another potential improvement option is to increase flood storage capacity in this area. In the ball fields
north of West 42nd Street and east of Grimes Avenue South, there is about 6 acres that could be lowered
with the intent of adding additional storage. Also, the approximately 3-acre wooded area east of Calvin
Christian School could be regraded to add storage, if necessary. Model results indicate that the additional
storage reduces the peak flood elevations by 2.0 to 3.0 feet in the Weber Park area. However, because
many of the structures in this area are so low, the corresponding reduction in the number of potentially
impacted structures was only 10 principle structures.
Several of the subwatersheds impacted by the 1-percent-annual-chance flood elevations are backyard
depression areas that do not have outlets. Flood elevations in these areas could be reduced by installing
outlets from these areas to existing storm sewer. Subwatersheds that have sufficient elevation above the
downstream flood levels are MS_20, MS_57, and MS_17, for example.
Flood problems in this area has been evaluated before and by others, including a feasibility study
conducted in 2006 by Barr Engineering and a recent analysis by University of Minnesota students as a
senior design capstone project. The best improvement option still appears to be providing additional
outlet capacity to Minneapolis. The City will consider working with the City of Minneapolis regarding the
feasibility of installing additional storm sewer to Lake Calhoun to reduce flood risk in the
Morningside/Weber Park area.
12.3.1.4 Edinbrook Lane and Westbrook Lane (MHN_79)
There is a backyard depression west of TH 100 and southeast of the intersection of Edinbrook Lane and
Westbrook Lane that receives runoff from subwatershed MHN_79, the watershed to the west (MHN_78),
and TH 100. The depression has a 21-inch piped outlet to the TH 100 storm sewer system and a surface
overflow north at approximately 893.6 feet, adjacent to 5005 Edinbrook Lane. Modeling results indicate
that the 1-percent-annual-chance flood elevation (892.5 feet) may impact three principle structures (5013
Edinbrook Lane and 4801–4805 Westbrook Lane), and may very nearly impact three other principle
structures (5009 and 5017 Edinbrook Lane, and 4811 Westbrook Lane), based on LiDAR and approximate
building footprint data. The modeling results suggest the flooding problem is not driven by the water
level in Minnehaha Creek. Instead, it is primarily related to the quantity of water coming into the
depression from west of MHN_79 (MHN_78) and from backflow from the TH 100 storm sewer system.
There are several options that should be considered to reduce flood risk in this area, including diverting
flows to reduce the volume of water to the low area and/or improving outlet conditions. The runoff
contributing from MHN_78, which has a peak flow rate of over 50 cfs, could be rerouted through new
storm sewer pipes running north under Westbrook Lane to Minnehaha Creek. Alternatively, the surface
overflow could be made more efficient (e.g., a concrete flume with vegetation cleared) and the elevation
could be lowered. However, this second option may require purchasing 5005 Edinbrook Lane. The City will
City of Edina 2018 Comprehensive Water Resources Management Plan
12-8
also consider working with MnDOT to evaluate options to reduce or eliminate flow into this area from the
TH 100 storm sewer system, with a backflow preventer or by increasing the conveyance capacity in the
TH 100 system, for example. Finally, all of the potentially impacted principle structures in this area could
be acquired so that the area could be used and possibly improved as a dry basin for storage and,
potentially, a water quality treatment basin. Soil maps show that the soils in this area are “B” soils with
moderate potential for infiltration.
12.3.1.5 North of Morningside Road between Lynn Avenue and Crocker Avenue
(MS_22)
There is a backyard depression north of Morningside Road between Lynn Avenue and Crocker Avenue.
The depression is land-locked, with a surface overflow to the east (adjacent to 4226 Crocker Avenue) at
approximately 875.8 feet, which is about 5 feet above the approximate low principle structure elevations
in this area. The 1-percent-annual-chance flood elevation (872.4 feet) is determined by the 10-day
snowmelt event and may impact up to six principle structures (4226–4236 Crocker Avenue), based on
LiDAR data and approximate building footprints.
It is recommended that a survey be conducted to determine low entry elevations for these seven principle
structures. If the survey indicates that these principle structures are potentially impacted by the 1-percent-
annual-chance flood elevation, it is recommended that a storm sewer outlet be installed in this backyard
depression. A new storm sewer could connect to either the existing system on Crocker Avenue or Lynn
Avenue, which both drain to the trunk storm sewer on West 42nd Street and ultimately to Weber Park
Pond. Additional pipe capacity downstream to Weber Park Pond and, potentially, additional storage in
Weber Park may also be required with this option due to other flood concerns within this general area.
Access to the backyard depression for installation of a new pipe may be challenging due to the developed
nature of the neighborhood and private property ownership.
12.3.1.6 Branson Street between West 44th Street and Morningside Road (MS_3, MS_48, and MS_7)
There are local depression areas along Branson Street and in the backyards north and south of Branson
Street just west of Grimes Avenue. Branson Street (MS_48) and the backyard area to the north (MS_3)
have catch basins and are drained by a 15-inch pipe originating at Branson Street and connecting north
to the storm sewer system on Morningside Road. The backyard depression to the south (MS_7) is land-
locked and does not have a piped outlet. It is hydraulically connected via surface overflows between 4303,
4301, and 4215 Branson Street at approximately 901.5 feet (according to LiDAR data). In addition, the
storm sewer system on West 44th Street surcharges during the 1-percent-annual-chance 24-hour storm
event; as a result, stormwater flows from West 44th Street into the backyard depression area (MS_7). At the
1-percent-annual-chance flood level, there are 12 principle structures that are potentially impacted and
Branson Street will have approximately 2 feet of water in its lowest spot. This area was also identified as
an area of concern in the 2003 and 2009 CWRMPs.
It is recommended that one or more inlets be installed in the backyard depression areas, pipes be added,
and pipe sizes increased north to the existing storm sewer system under Morningside Road. The addition
City of Edina 2018 Comprehensive Water Resources Management Plan
12-9
of an inlet to MS_7 with a connection to the pipe system on West 44th Street was evaluated, but this
alternative would require the entire pipe system along West 44th Street and Morningside Avenue to be
upgraded. Additional flow capacity in the storm sewer system to Weber Park Pond and, potentially,
additional storage in Weber Park may be required with this option due to other flood concerns within this
general area. Other considerations include adding additional storage capacity in this area. Storage could
be added in MS_7 by lowering the backyard depression. Alternatively, in the event of street
reconstruction, the low area of Branson Street could be raised and underground storage could be added
under Branson Street and Oakdale Avenue (up to approximately 700 linear feet). Underground storage
under Oakdale Avenue could intercept runoff from the upper parts of the MS_48 watershed.
12.3.2 Construction/Upgrade of Water Quality Basins
The 2003 P8 modeling analysis indicated that under average conditions the predicted annual removal of
total phosphorus from the ponds and wetlands in the Northeast Minnehaha Creek drainage area is
greater than the desired 60 percent removal rate. As a result, no specific recommendations are given for
the construction or upgrade of water quality basins in this watershed.
Many techniques are available to reduce pollutant loading from stormwater runoff, including impervious
surface reduction or disconnection, implementation of infiltration or volume-retention BMPs, installation
of underground stormwater treatment structures and sump manholes, and other good housekeeping
practices such as street sweeping. As opportunities arise, the City will consider all of these options to
reduce the volume and further improve the quality of stormwater runoff from this drainage area.
Table 12.2
Watershed Modeling Results for Subwatersheds in the Minnehaha Northeast Drainage Area
1 The 1%-Annual-Chance (100-Year) 10-day snowmelt event is defined as 7.2 inches of runoff
Watershed ID
Total Area
(ac)
% Impervious
Area
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
MS_1 0.5 23 4 0.3 0.1 0.3 2 0.2
MS_10 3.3 48 35 1.6 0.6 1.9 18 0.8
MS_11 1.5 80 16 0.9 0.3 0.9 9 0.5
MS_13 4.8 25 17 2.0 0.9 2.9 7 0.9
MS_14 1.4 27 13 0.6 0.3 0.8 6 0.3
MS_15 1.2 25 12 0.5 0.2 0.7 6 0.3
MS_16 4.0 25 21 1.7 0.8 2.4 9 0.8
MS_17 2.2 25 19 1.0 0.4 1.3 9 0.5
MS_18 2.3 25 16 1.0 0.4 1.4 7 0.5
MS_19 3.2 25 22 1.4 0.6 1.9 9 0.7
MS_2 10.0 25 57 4.4 1.9 6.0 24 2.1
MS_20 5.4 21 44 2.4 1.0 3.3 21 1.2
MS_21 5.0 25 28 2.2 0.9 3.0 12 1.1
MS_22 4.8 25 37 2.1 0.9 2.9 17 1.0
MS_23 1.4 23 9 0.8 0.3 0.8 4 0.4
MS_24 2.0 25 20 1.1 0.4 1.2 10 0.6
MS_25 1.0 22 7 0.5 0.2 0.6 4 0.3
MS_26 4.3 25 38 2.4 0.8 2.6 19 1.3
MS_27 4.0 25 28 1.8 0.8 2.4 13 0.9
MS_28 1.7 25 18 0.8 0.3 1.0 9 0.4
MS_29 4.0 25 25 1.9 0.8 2.4 11 1.0
MS_3 3.3 25 23 1.5 0.6 2.0 10 0.7
MS_30 5.9 25 34 2.8 1.1 3.5 15 1.4
MS_31 6.0 23 37 3.2 1.1 3.6 18 1.7
MS_32 3.6 25 22 1.9 0.7 2.2 10 0.9
MS_33 5.4 26 38 2.5 1.0 3.3 17 1.2
MS_34 3.4 25 23 1.5 0.6 2.1 10 0.7
MS_35 3.8 25 22 1.7 0.7 2.3 9 0.8
MS_36 1.8 25 10 0.8 0.3 1.1 4 0.4
MS_37 2.2 25 18 1.0 0.4 1.3 9 0.5
MS_38 1.5 27 13 0.7 0.3 0.9 7 0.4
MS_39a 5.5 32 42 3.0 1.0 3.3 21 1.6
MS_39b 8.7 24 52 4.3 1.6 5.2 24 2.2
MS_4 3.7 25 34 1.7 0.7 2.2 16 0.8
MS_40 12.0 43 74 6.4 2.3 7.2 35 3.3
MS_41 0.9 21 6 0.5 0.2 0.5 3 0.3
MS_42 4.4 25 26 1.9 0.8 2.6 11 0.9
MS_43 5.2 25 40 2.3 1.0 3.1 19 1.1
MS_44 1.1 23 10 0.6 0.2 0.7 5 0.3
MS_45 2.1 25 21 1.0 0.4 1.2 11 0.5
MS_46 5.5 13 27 2.4 1.0 3.3 11 1.1
MS_47 4.3 25 17 1.9 0.8 2.6 7 0.8
MS_48 10.2 25 38 4.4 1.9 6.1 16 2.0
MS_49 5.3 25 44 2.4 1.0 3.1 21 1.2
MS_5 3.3 25 26 1.5 0.6 2.0 12 0.7
MS_50 3.3 25 25 1.5 0.6 2.0 12 0.7
MS_51 6.9 25 36 3.0 1.3 4.1 15 1.4
MS_52 4.5 25 36 2.0 0.9 2.7 17 1.0
MS_53 1.0 25 10 0.5 0.2 0.6 5 0.2
MS_54 10.1 37 51 4.8 1.9 6.1 22 2.3
MS_55 6.7 27 19 3.2 1.1 4.0 8 1.5
MS_56 0.8 25 6 0.3 0.1 0.5 3 0.2
MS_57 1.8 25 18 0.8 0.3 1.1 9 0.4
MS_58 2.8 11 24 1.5 0.5 1.7 12 0.7
MS_59 1.8 25 14 0.8 0.3 1.1 7 0.4
MS_6 4.2 22 21 1.8 0.8 2.5 8 0.8
MS_7 4.8 25 32 2.1 0.9 2.9 14 1.0
MS_8 3.8 25 29 1.7 0.7 2.3 13 0.8
MS_9 2.5 25 24 1.1 0.5 1.5 12 0.5
MHN_1 10.7 32 87 5.1 2.0 6.4 42 2.5
24-Hour Precipitation Event
10%-Annual-Chance (10-Year)Watershed Information 1%-Annual-Chance (100-Year)
24-Hour Precipitation Event 10-day Snowmelt Event1
1%-Annual-Chance (100-Year)
Table 12.2
Watershed Modeling Results for Subwatersheds in the Minnehaha Northeast Drainage Area
1 The 1%-Annual-Chance (100-Year) 10-day snowmelt event is defined as 7.2 inches of runoff
Watershed ID
Total Area
(ac)
% Impervious
Area
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
24-Hour Precipitation Event
10%-Annual-Chance (10-Year)Watershed Information 1%-Annual-Chance (100-Year)
24-Hour Precipitation Event 10-day Snowmelt Event1
1%-Annual-Chance (100-Year)
MHN_10 1.3 25 10 0.6 0.2 0.8 4 0.3
MHN_11 6.7 47 58 3.5 1.3 4.0 29 1.9
MHN_12 2.2 25 20 1.1 0.4 1.3 10 0.6
MHN_13 7.2 25 37 3.2 1.4 4.3 15 1.5
MHN_14 5.9 25 38 2.6 1.1 3.5 16 1.2
MHN_15 5.4 25 35 2.4 1.0 3.2 15 1.1
MHN_16 8.5 25 39 3.7 1.6 5.1 16 1.7
MHN_17 9.9 25 50 5.0 1.8 5.9 22 2.5
MHN_18 2.6 25 13 1.4 0.5 1.5 6 0.8
MHN_19 7.1 25 59 3.4 1.3 4.2 29 1.7
MHN_2 1.4 25 12 0.7 0.3 0.9 6 0.3
MHN_20 8.9 25 40 4.4 1.6 5.3 18 2.2
MHN_21 5.4 25 44 2.7 1.0 3.3 22 1.4
MHN_22 5.7 25 36 3.2 1.1 3.4 18 1.7
MHN_23 9.9 25 78 5.2 1.9 6.0 39 2.7
MHN_24 5.6 25 37 2.8 1.1 3.4 17 1.4
MHN_25 1.8 25 16 0.8 0.3 1.1 8 0.4
MHN_26 2.4 25 25 1.1 0.4 1.4 13 0.5
MHN_27 0.6 30 5 0.3 0.1 0.3 3 0.2
MHN_28 0.5 21 4 0.3 0.1 0.3 2 0.1
MHN_29 7.6 25 71 3.4 1.4 4.6 35 1.6
MHN_3 3.6 29 31 1.6 0.7 2.1 15 0.8
MHN_30 4.7 25 26 2.1 0.9 2.8 11 1.0
MHN_31 7.8 25 61 3.5 1.5 4.7 28 1.7
MHN_32 9.6 25 72 4.6 1.8 5.8 34 2.3
MHN_33 5.2 25 46 2.3 1.0 3.1 22 1.1
MHN_34 4.5 25 38 2.0 0.8 2.7 18 1.0
MHN_35 1.2 25 12 0.5 0.2 0.7 6 0.3
MHN_36 3.5 29 26 1.6 0.7 2.1 12 0.8
MHN_37 0.7 41 8 0.3 0.1 0.4 5 0.2
MHN_38 2.0 51 17 1.0 0.4 1.2 8 0.5
MHN_39 5.3 54 37 2.7 1.0 3.2 17 1.4
MHN_4 3.4 25 14 1.4 0.6 2.0 6 0.7
MHN_40 14.8 22 75 6.4 2.8 8.9 30 2.9
MHN_41 2.4 25 24 1.1 0.4 1.4 12 0.5
MHN_42 6.1 25 31 2.7 1.1 3.6 13 1.3
MHN_43 6.0 25 33 2.7 1.1 3.6 14 1.3
MHN_44 10.7 25 39 4.7 1.9 6.4 16 2.2
MHN_46 5.5 25 59 2.6 1.0 3.3 31 1.3
MHN_47 1.1 25 10 0.5 0.2 0.7 5 0.2
MHN_48 3.4 34 33 1.6 0.6 2.1 17 0.8
MHN_49 1.4 25 15 0.6 0.3 0.8 8 0.3
MHN_5 7.7 25 60 3.4 1.5 4.6 28 1.6
MHN_50 8.4 25 40 3.7 1.6 5.0 17 1.7
MHN_51 2.6 25 26 1.2 0.5 1.6 13 0.6
MHN_52 1.6 25 16 0.8 0.3 0.9 8 0.4
MHN_53 3.7 25 22 1.6 0.7 2.2 9 0.8
MHN_54 1.3 25 9 0.6 0.2 0.8 4 0.3
MHN_55 2.7 25 17 1.2 0.5 1.6 7 0.6
MHN_56 2.1 44 23 1.0 0.4 1.3 12 0.5
MHN_57 1.5 79 12 0.8 0.3 0.9 6 0.5
MHN_58 5.3 75 48 2.9 1.0 3.2 24 1.5
MHN_59 1.3 80 13 0.7 0.3 0.8 6 0.4
MHN_6 3.9 25 24 1.7 0.7 2.4 10 0.8
MHN_60 0.6 25 7 0.3 0.1 0.4 4 0.2
MHN_60b 1.7 25 18 0.8 0.3 1.0 9 0.4
MHN_61 3.9 48 34 2.0 0.7 2.4 16 1.0
MHN_62 6.7 57 68 3.6 1.3 4.0 35 1.9
MHN_63 2.8 80 23 1.6 0.5 1.7 11 0.9
MHN_64 4.6 25 24 2.0 0.9 2.7 10 0.9
Table 12.2
Watershed Modeling Results for Subwatersheds in the Minnehaha Northeast Drainage Area
1 The 1%-Annual-Chance (100-Year) 10-day snowmelt event is defined as 7.2 inches of runoff
Watershed ID
Total Area
(ac)
% Impervious
Area
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
24-Hour Precipitation Event
10%-Annual-Chance (10-Year)Watershed Information 1%-Annual-Chance (100-Year)
24-Hour Precipitation Event 10-day Snowmelt Event1
1%-Annual-Chance (100-Year)
MHN_65 14.0 30 110 6.7 2.7 8.4 53 3.4
MHN_66 12.7 38 103 6.4 2.4 7.6 50 3.3
MHN_67 2.1 3 8 0.8 0.4 1.3 3 0.3
MHN_68 0.8 25 9 0.4 0.2 0.5 4 0.2
MHN_69 21.9 25 189 10.0 4.2 13.2 92 4.9
MHN_69B 6.4 31 64 3.0 1.2 3.8 33 1.5
MHN_7 3.8 25 21 1.7 0.7 2.2 9 0.8
MHN_71 6.5 27 19 2.9 1.1 3.9 8 1.3
MHN_72 8.8 34 57 3.8 1.7 5.3 23 1.8
MHN_73 2.1 76 15 1.1 0.4 1.2 7 0.6
MHN_74 15.0 25 80 6.8 2.8 9.0 34 3.3
MHN_76 2.1 80 19 1.1 0.4 1.2 9 0.6
MHN_77 2.3 80 14 1.3 0.4 1.4 6 0.7
MHN_78 9.7 31 75 4.5 1.8 5.8 34 2.2
MHN_79 2.9 29 31 1.3 0.6 1.8 17 0.7
MHN_79a 0.7 31 9 0.3 0.1 0.4 5 0.2
MHN_8 2.8 24 31 1.3 0.5 1.7 17 0.6
MHN_80 8.9 28 64 4.0 1.7 5.4 29 1.9
MHN_81 2.0 63 18 1.0 0.4 1.2 9 0.6
MHN_82 3.3 62 28 1.6 0.6 2.0 12 0.8
MHN_83 5.3 2 21 2.0 1.0 3.1 8 0.8
MHN_84 4.6 62 37 2.4 0.9 2.8 17 1.2
MHN_85 2.0 27 20 0.9 0.4 1.2 10 0.4
MHN_86 1.7 25 13 0.8 0.3 1.0 6 0.4
MHN_87 4.3 25 40 1.9 0.8 2.5 20 0.9
MHN_88 3.5 25 25 1.6 0.7 2.1 11 0.7
MHN_89 7.7 26 51 3.4 1.5 4.6 22 1.6
MHN_9 14.6 23 103 7.4 2.8 8.8 50 3.8
MHN_90 2.5 30 19 1.1 0.5 1.5 9 0.6
MHN_91 0.9 25 8 0.4 0.2 0.6 4 0.2
ECC_1 5.3 8 38 2.2 1.0 3.2 17 1.0
ECC_10 2.8 11 24 1.3 0.5 1.7 12 0.6
ECC_11 3.3 14 26 1.4 0.6 2.0 12 0.6
ECC_12 1.7 25 17 0.8 0.3 1.0 9 0.4
ECC_13 1.8 25 18 1.0 0.3 1.1 9 0.5
ECC_14 3.4 13 31 1.4 0.6 2.0 15 0.7
ECC_15 4.7 2 25 1.9 0.9 2.8 10 0.8
ECC_2 4.0 20 24 1.7 0.8 2.4 10 0.8
ECC_3 8.4 11 53 3.5 1.6 5.0 22 1.6
ECC_4 8.7 8 49 3.8 1.6 5.2 21 1.8
ECC_5 15.6 3 43 5.8 2.9 9.4 15 2.3
ECC_6 10.2 6 62 4.0 1.9 6.1 24 1.7
ECC_7 31.6 2 118 13.4 5.9 18.9 47 6.1
ECC_8 4.6 2 30 1.8 0.9 2.7 12 0.8
ECC_9 10.1 5 59 4.3 1.9 6.1 25 2.0
MHC_100a 4.9 64 58 2.6 0.9 2.9 32 1.4
MHC_100b 2.2 64 25 1.2 0.4 1.3 13 0.6
MHC_100c 2.5 64 29 1.3 0.5 1.5 16 0.7
Table 12.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Northeast Minnehaha Creek
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
184 885.2 885.1
1608 871.5 869.9
1610 906.1 904.3
1611 904.6 902.1
1612 900.0 899.1
1617 896.0 895.6
1618 873.9 871.9
1619 871.0 870.7
1620 871.0 870.6
1621 870.4 869.4
1624 871.0 869.6
1626 870.0 868.2
1628 870.0 868.2
1629 870.0 868.2
1633 870.0 868.2
1634 870.0 868.2
1636 880.4 880.3
1637 876.9 876.8
1638 874.9 874.7
1640 874.9 874.7
1642 903.1 902.3
1645 899.9 898.7
1648 892.6 892.5
1649 879.6 878.6
1651 875.1 874.9
1653 871.9 869.7
1654 875.4 871.7
1656 872.1 869.9
1659 870.1 869.1
1661 869.4 867.4
1663 869.8 867.8
1669 889.5 887.5
1671 887.0 882.2
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
1%-Annual-Chance (100-Year)
Storm Event Results
24-Hour Precipitation Event
Table 12.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Northeast Minnehaha Creek
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
1%-Annual-Chance (100-Year)
Storm Event Results
24-Hour Precipitation Event
1681 887.2 887.2
1682 889.4 889.4
1684 886.9 886.9
1685 882.0 882.0
1687 882.5 882.5
1689 880.2 880.2
1691 880.3 879.0
1692 880.4 879.8
1693 880.4 876.7
1694 880.4 876.3
1695 880.3 877.1
1697 880.3 877.1
1702 878.3 878.0
1704 882.0 882.0
1705 881.0 881.0
1714 868.9 868.9
1718 892.8 892.8
1721 884.4 884.1
1722 889.5 889.5
1728 895.1 894.8
1729 895.1 894.8
1731 895.1 894.8
1732 895.1 894.9
1736 894.0 894.0
1741 895.1 894.7
1744 895.5 895.3
1870 893.4 893.2
1872 881.6 880.9
2151 896.2 896.1
2152 892.2 892.1
2153 890.0 888.5
2154 900.2 899.7
2235 882.6 882.6
Table 12.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Northeast Minnehaha Creek
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
1%-Annual-Chance (100-Year)
Storm Event Results
24-Hour Precipitation Event
2237 867.8 867.8
2257 874.1 873.5
2378 901.6 899.9
2384 870.0 868.2
2385 885.4 885.4
2387 876.3 875.9
2389 875.9 873.3
2390 878.6 878.6
2394 873.7 871.7
2397 880.0 880.0
2398 880.3 877.1
2400 884.3 884.3
2401 883.2 883.2
2402 881.7 881.7
2403 880.8 880.8
2404 880.3 880.3
2406 888.9 ¹ 888.4
2412 877.9 877.9
2430 897.4 897.3
2431 895.2 895.2
2432 894.6 894.6
2459 886.2 886.1
1681$I 881.0 880.5
1682$I 880.2 879.7
1684$I 878.8 878.3
1685$I 877.8 877.3
1687$I 875.6 875.1
1689$I 875.5 875.6
1691$I 877.8 876.3
1692$I 877.2 876.1
1693$I 876.9 876.1
1694$I 876.3 876.0
1695$I 876.2 876.0
Table 12.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Northeast Minnehaha Creek
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
1%-Annual-Chance (100-Year)
Storm Event Results
24-Hour Precipitation Event
1697$I 875.0 875.3
1702$I 875.4 875.4
1704$I 874.9 874.2
1705$I 874.4 873.1
1714$I 868.2 867.5
1718$I 879.6 879.6
1721$I 881.9 881.9
1722$I 884.2 883.9
1728$I 888.9 ¹ 887.9
1729$I 888.9 ¹ 887.9
1731$I 888.9 ¹ 887.8
1732$I 888.9 ¹ 887.7
1736$I 888.9 ¹ 887.7
1741$I 892.2 891.6
1744$I 888.9 ¹ 887.7
184$I 872.2 872.2
2235$I 871.6 870.0
2237$I 866.9 865.9
2385$I 872.6 872.6
2387$I 870.4 870.4
2390$I 874.0 872.3
2397$I 878.8 877.5
2398$I 876.7 876.1
2400$I 880.0 880.0
2401$I 879.4 878.5
2402$I 878.6 877.0
2403$I 878.4 876.9
2404$I 878.2 876.6
2412$I 875.5 875.5
ECC_1 byd 899.5 898.7
ECC_10 street 877.8 876.8
ECC_11 street/lot 885.4 884.9
ECC_12 cul-de-sac 877.7 870.9
Table 12.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Northeast Minnehaha Creek
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
1%-Annual-Chance (100-Year)
Storm Event Results
24-Hour Precipitation Event
ECC_13 cul-de-sac 869.1 869.0
ECC_14 street 894.0 893.8
ECC_15 street 874.6 874.3
ECC_2 pond 898.6** 899.5 0.9 899.3 0.7
ECC_3 pond 898.8** 904.4 ¹ 5.6 900.3 1.5
ECC_4 pond 899.9** 905.7 5.8 903.5 3.6
ECC_5 pond 888.9** 888.9 0.0 888.9 0.0
ECC_6 pond 909.0** 912.5 3.5 911.8 2.8
ECC_7 byd 887.1 ¹ 884.4
ECC_8 byd 886.3 885.3
ECC_9 pond 904.1** 905.8 1.7 905.5 1.4
FID1916 902.5 900.9
FID1917 893.2 890.4
FID1918 893.1 890.3
FID1921 893.0 890.1
FID1922 892.8 889.9
FID1923 892.3 888.9
FID1924 892.4 889.7
FID1934 873.5 872.6
FID1955 876.2 874.6
FID1956 876.4 874.6
FID2079 895.1 894.8
FID2079$I 889.3 889.3
FID2333 889.6 889.6
FID2333$I 888.9 ¹ 887.7
FID2335 894.6 894.6
FID2335$I 888.9 ¹ 887.7
FID2343 893.1 893.1
FID2343$I 888.9 ¹ 887.7
FID2344 893.5 893.5
FID2344$I 888.9 ¹ 887.7
FID2427 889.7 889.4
FID2427$I 878.7 878.7
Table 12.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Northeast Minnehaha Creek
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
1%-Annual-Chance (100-Year)
Storm Event Results
24-Hour Precipitation Event
FID3003 884.6 884.3
FID3003$I 877.8 877.8
FID36 895.3 895.0
FID36$I 888.9 ¹ 887.7
FID4142 895.1 894.8
FID4142$I 889.3 889.3
FID4537 883.2 ¹ 881.9
FID4545 902.3 902.3
FID4760 884.6 884.3
FID4760$I 877.8 877.8
FID4762 884.6 884.3
FID4762$I 878.6 878.6
FID57 892.7 889.8
FID58 896.3 893.9
FID6024 884.4 884.1
FID6024$I 882.0 882.0
FID6025 884.4 884.1
FID6025$I 882.0 882.0
FID6248 870.0 868.3
FID6467 872.5 871.5
FID6614 897.7 896.5
FID6618 901.6 899.7
FID6621 901.7 900.5
FID68 893.4 893.4
FID68$I 887.3 887.3
FID6840 891.1 891.1
FID6841 890.5 890.5
FID6842 888.9 ¹ 887.7
FID6846 888.9 ¹ 887.7
FID6869 909.8 909.6
FID6874 899.5 896.1
FID6880 902.6 898.7
FID6881 928.7 928.7
Table 12.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Northeast Minnehaha Creek
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
1%-Annual-Chance (100-Year)
Storm Event Results
24-Hour Precipitation Event
FID7169 903.3 902.4
LS7 882.1 880.9
LS7a 890.8 889.3
MH-2 868.5 866.2
MHC_100a hwy ditch 896.5 893.5
MHC_100b hwy ditch 891.9 890.3
MHC_100c hwy ditch 888.9 ¹ 887.7
MHN_1 pond 867.8** 878.3 ¹ 10.5 872.7 4.9
MHN_10 street 885.4 885.2
MHN_10$I 885.0 885.0
MHN_11 pond 870.2** 876.8 6.6 873.9 3.7
MHN_12 byd 880.5 880.4
MHN_13 street 885.8 885.7
MHN_13$I 884.8 884.5
MHN_14 street 884.4 884.1
MHN_14$I 882.6 882.5
MHN_15 street 889.2 888.9
MHN_15$I 880.9 880.9
MHN_16 street 889.7 889.4
MHN_16$I 878.1 878.1
MHN_17 street 892.1 891.6
MHN_17$I 885.0 885.0
MHN_18 byd 898.2 898.1
MHN_19 street 895.1 894.8
MHN_19$I 888.9 ¹ 887.7
MHN_2 street 878.3 878.0
MHN_2$I 875.4 875.3
MHN_20 street 895.1 894.8
MHN_20$I 890.6 890.6
MHN_21 street 895.2 895.0
MHN_21$I 892.4 892.4
MHN_22 street 894.5 894.4
MHN_22$I 893.0 892.5
Table 12.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Northeast Minnehaha Creek
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
1%-Annual-Chance (100-Year)
Storm Event Results
24-Hour Precipitation Event
MHN_23 street 895.1 894.7
MHN_23$I 895.1 894.7
MHN_24 street 895.1 894.8
MHN_24$I 888.9 ¹ 888.1
MHN_25 street 895.3 895.1
MHN_25$I 888.9 ¹ 887.7
MHN_26 street 889.7 889.6
MHN_27 creek 872.1 871.4
MHN_27$I 870.4 870.4
MHN_28 creek 872.9 872.2
MHN_28$I 868.3 868.3
MHN_29 892.2 892.1
MHN_3 street 878.5 878.2
MHN_3$I 875.7 874.3
MHN_30 street 888.9 ¹ 888.5
MHN_31 street 888.9 ¹ 888.3
MHN_32 street 897.2 897.1
MHN_32$I 897.2 897.1
MHN_33 street 889.7 889.5
MHN_33$I 888.9 ¹ 888.2
MHN_34 street 893.0 892.6
MHN_35 street 889.4 887.9
MHN_36 creek 890.0 889.0
MHN_37 street 891.1 891.0
MHN_38 yard 892.7 892.6
MHN_39 street 899.8 899.6
MHN_4 street 880.5 880.2
MHN_4$I 874.3 874.3
MHN_40 street/byd 890.2 888.7
MHN_41 byd 894.0 ¹ 892.0
MHN_42 street 867.0 866.9
MHN_42$I 867.0 866.4
MHN_43 street 892.2 892.1
Table 12.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Northeast Minnehaha Creek
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
1%-Annual-Chance (100-Year)
Storm Event Results
24-Hour Precipitation Event
MHN_43$I 888.7 888.7
MHN_44 street 894.5 894.2
MHN_44$I 888.8 ¹ 888.6
MHN_46 street 900.2 895.8
MHN_47 street 905.4 901.7
MHN_48 897.0 896.9
MHN_49 byd 887.8 885.2
MHN_5 street 872.5 872.2
MHN_5$I 869.9 867.3
MHN_50 street/byd 889.0 888.8
MHN_50$I 885.5 885.1
MHN_51 street 895.5 895.3
MHN_51$I 888.9 ¹ 887.7
MHN_52 street 895.1 894.8
MHN_52$I 888.9 ¹ 887.7
MHN_53 street 884.6 884.3
MHN_53$I 877.3 877.2
MHN_54 street 884.6 884.3
MHN_54$I 877.7 877.7
MHN_55 street/yd 878.4 878.1
MHN_55$I 873.9 872.1
MHN_56 street 880.3 879.3
MHN_56$I 880.1 878.4
MHN_57 street 887.3 887.1
MHN_57$I 879.5 879.0
MHN_58 street/lot 882.8 882.3
MHN_58$I 882.9 882.3
MHN_59 street 885.0 884.8
MHN_59$I 881.0 881.0
MHN_6 street/yd 884.6 884.3
MHN_6$I 877.1 877.1
MHN_60 creek 887.6 ¹ 886.7
MHN_60b street 894.2 894.1
Table 12.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Northeast Minnehaha Creek
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
1%-Annual-Chance (100-Year)
Storm Event Results
24-Hour Precipitation Event
MHN_61 byd 877.4 876.9
MHN_61R 879.8 879.7
MHN_61R$I 876.5 874.8
MHN_62 street 878.3 878.0
MHN_62$I 875.5 875.5
MHN_63 street 881.6 881.5
MHN_63$I 876.1 874.4
MHN_64 street 889.5 885.2
MHN_65 byd 878.1 ¹ 874.7
MHN_66 pond 869.4** 875.7 6.3 872.0 2.6
MHN_67 creek 889.1 882.1
MHN_68 byd 878.3 ¹ 874.0
MHN_69 street 892.3 889.6
MHN_69B byd 917.2 917.0
MHN_7 street 884.6 884.3
MHN_7$I 877.6 877.6
MHN_71 street 877.4 876.7
MHN_71$I 876.2 874.4
MHN_72 street/lot 884.6 884.3
MHN_72$I 879.4 879.4
MHN_73 street/lot 887.1 886.9
MHN_73$I 881.9 881.4
MHN_74 879.1 878.8
MHN_74$I 879.1 878.8
MHN_76 street/lot 880.4 877.5
MHN_76$I 876.0 875.9
MHN_77 street 880.2 880.0
MHN_77$I 878.1 876.6
MHN_78 street 896.8 896.5
MHN_79 byd 892.5 892.0
MHN_79a hwy ditch 910.7 910.3
MHN_8 creek 887.6 ¹ 885.7
MHN_80 street 891.0 890.5
Table 12.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Northeast Minnehaha Creek
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
1%-Annual-Chance (100-Year)
Storm Event Results
24-Hour Precipitation Event
MHN_81 street 901.1 900.6
MHN_82 street 880.6 880.5
MHN_82$I 877.0 876.4
MHN_83 893.3 892.7
MHN_84 street 880.3 877.5
MHN_84$I 875.2 875.2
MHN_85 street/yd 891.2 889.7
MHN_86 cul-de-sac 874.7 874.6
MHN_87 byd 878.3 877.5
MHN_88 byd 870.9 870.5
MHN_89 street/yd 878.4 878.1
MHN_89$I 872.8 870.9
MHN_9 street 879.9 879.5
MHN_9$I 879.9 879.9
MHN_90 street 878.3 877.9
MHN_90$I 875.8 875.7
MHN_91 byd 884.2 884.0
MS_1 street/yd 872.1 870.3
MS_10 byd 897.6 896.5
MS_11 parking lot 897.4 896.5
MS_13 872.5 870.1
MS_14 byd 903.1 902.1
MS_15 byd 871.7 869.8
MS_16 870.0 868.2
MS_17 byd 902.5 901.5
MS_18 871.0 868.4
MS_19 street/yd 880.6 880.5
MS_2 street 875.2 875.0
MS_20 byd 877.3 ¹ 874.8
MS_21 875.1 874.9
MS_22 byd 872.4 ¹ 870.9
MS_23 street 870.1 869.0
MS_24 byd 872.1 870.3
Table 12.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Northeast Minnehaha Creek
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
1%-Annual-Chance (100-Year)
Storm Event Results
24-Hour Precipitation Event
MS_25 street/yd 872.1 870.3
MS_26 pond 865.0 872.1 7.1 870.3 5.3
MS_27 byd 871.5 869.9
MS_28 byd 871.0 869.6
MS_29 street 870.1 869.0
MS_3 byd 902.2 900.0
MS_30 street 872.8 871.0
MS_31 street 870.0 869.2
MS_32 byd 872.9 871.0
MS_33 street/yd 870.0 868.2
MS_34 street 902.6 900.9
MS_35 street 904.6 903.6
MS_36 street 906.5 904.6
MS_37 street 906.1 905.9
MS_38 parking lot 870.0 868.2
MS_39a field 870.0 868.2
MS_39b field 870.0 865.9
MS_4 902.0 899.6
MS_40 pond 861.6** 870.0 8.4 868.2 6.6
MS_41 street 872.1 870.3
MS_42 street 872.1 870.7
MS_43 street/byd 903.2 902.5
MS_44 street/yd 872.1 870.3
MS_45 872.9 872.6
MS_46 byd 872.9 871.1
MS_47 898.4 896.9
MS_48 street 902.2 900.8
MS_49 street 870.0 868.2
MS_5 903.3 902.4
MS_50 byd 870.0 868.2
MS_51 street 875.8 873.3
MS_52 byd 870.1 868.2
MS_53 byd 871.7 870.2
Table 12.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Northeast Minnehaha Creek
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
1%-Annual-Chance (100-Year)
Storm Event Results
24-Hour Precipitation Event
MS_54 byd 870.0 868.2
MS_55 street 868.4 868.1
MS_56 byd 903.4 902.6
MS_57 byd 902.5 902.2
MS_58 byd 872.9 871.0
MS_59 byd 909.8 909.7
MS_6 street 902.2 901.5
MS_7 byd 902.2 900.6
MS_8 street 903.4 902.6
MS_9 byd 875.5 873.4
N131 868.7 868.1
N133 872.1 870.3
N134 872.1 870.5
N135 871.9 870.2
N136 883.5 873.0
N145 872.1 870.3
N146 872.1 870.3
N147 depression 870.0 868.4
N151 869.3 866.5
N152 872.9 871.0
N235 889.7 889.4
N235$I 878.4 878.4
To_SLP 867.9 865.4
100
456717
456721
W 44th St
W 39th St Wooddale Ave Country Club Rd Mi
n
nehaha
CreekMinneapolisMinneapolis
Saint Louis ParkSaint Louis Park
MHC_3
MHC_2
ECC_7
MHN_69
ECC_5
MHN_74
MHN_9
MHC_1
MHN_40
MS_40
MS_2
MHN_65
MHN_66
MS_48
MS_54
ECC_6
MHN_1
ECC_9
MHN_44
ECC_4
ECC_3
MHN_23
MHN_17
MHN_78
MHN_32
MS_39b
MHN_80
MHN_20
MHN_72
MHN_5
MHN_16
MS_51
MHN_50
MHN_31
MHN_89
MHN_29
MS_31
MHN_13
MHN_19
MS_7
MHN_11
MHN_62
MS_46
MS_20
MS_33
MHN_71
ECC_1
MS_43
MS_21
MHN_42
MS_13
MHN_14
MS_22
MS_39a
MHN_22MHN_24
MS_8
MHN_69B
ECC_8
MS_52
MHN_21
MHN_15
MS_42
MS_4
MHN_58
MS_47
MHN_83
MS_26
MHN_33
ECC_15
MS_27
ECC_2
MS_3
MS_5
MHN_30
MS_35
MHN_84
MHN_64
MHN_6
MHN_34
MS_34
MHN_3
MS_50
MS_10
MHN_61
MHN_53
MS_9
MS_58
MHN_36
MHN_82
ECC_10
MS_18
MS_17
MS_37
MHN_41
MHN_73
ECC_13
MS_55MS_30
MS_49
MS_6
MHN_43
MHN_46
MHN_39
MS_16
MS_29
MS_32
MHN_7
MHN_87
MHC_100a
MS_19
MHN_4
ECC_14
MHN_88
ECC_11
MHN_48
MHN_8
MHN_79
MHN_63
MHN_55
MHN_51
MHN_18
MS_45
MHN_90
MS_24
MHN_26
MHN_77
MS_59
MS_36
MHN_12
MS_57
MHN_56
MHN_67 MHN_76
MHC_100c
MS_28
MHN_81
MHN_38
MHN_85
MS_11
MHN_25
MS_38
ECC_12
MHC_100b
MHN_86
MS_23
MHN_2
MS_14
MHN_52
MHN_57
MS_15
MHN_60b
MHN_49
MS_44
MHN_59MHN_10
MS_53
MHN_54
MHN_35
MS_25
MHN_47
MS_41
MS_56
MHN_91
MHN_68
MS_1
MHN_37
MHN_79a
MHN_60
MHN_27MHN_28
Barr Footer: ArcGIS 10.4.1, 2017-09-21 12:16 File: \\barr.com\gis\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_12_1_MC_Northeast_Drainage_Basins.mxd User: rcs2FIGURE 12.1
0 1,000
Feet
!;N
Northeast Minnehaha CreekDrainage Basin
Subwatershed
Streets and Highways
Creek/Stream
City of Edina Boundary
Lake/Wetland
Imagery Source: MnGeo; 2016
NORTHEAST MINNEHAHA CREEKDRAINAGE BASINComprehensiveWater ResourcesManagement PlanCity of Edina, Minnesota
100
456717
456721
W 44th St
W 39th St Wooddale Ave Country Club Rd Minnehaha
C
r
e
e
kMinnehaha Creek North
Morningside
Edina Country Club
MinneapolisMinneapolis
Saint Louis ParkSaint Louis Park
Barr Footer: ArcGIS 10.4.1, 2017-09-21 12:17 File: \\barr.com\gis\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_12_2_MC_Northeast_Major_Watersheds.mxd User: rcs2FIGURE 12.2
0 1,000
Feet
!;N
Northeast Minnehaha CreekDrainage Basin
Major Watersheds
Edina Country Club
Minnehaha Creek North
Morningside
Subwatershed
Streets and Highways
Creek/Stream
City of Edina Boundary
Lake/Wetland
Imagery Source: MnGeo; 2016
NORTHEAST MINNEHAHA CREEKMAJOR WATERSHEDSComprehensiveWater ResourcesManagement PlanCity of Edina, Minnesota
City of Edina 2018 Comprehensive Water Resources Management Plan
12-28
Reserved for:
Figure 12.3 Northeast Minnehaha Creek Hydraulic Model Results
This is a large drawing (34x44).
Due to the paper and size and file size, this figure is included as a stand-alone PDF.
JP_40JP_26
MHN_1
MHN_66
MHN_11
ECC_6
ECC_5
ECC_9 ECC_4
ECC_3
ECC_2
JP_10
St.St.
Louis ParkLouis Park
MinneapolisMinneapolis
Min nehahaC reek
Barr Footer: ArcGIS 10.4.1, 2018-03-26 11:35 File: I:\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_12_4_MC_Northeast_Water_Quality.mxd User: EMANORTHEAST MINNEHAHA CREEKWATER QUALITY MODELING RESULTSComprehensive Water ResourceManagement PlanCity of Edina, Minnesota
FIGURE 12.4
1,000 0 1,000Feet
300 0 300Meters
Percent TP Removal in Water Body*This number represents the percent of the total annual massof phosphorus entering the water body that is removed.
Cumulative TP Removal in Watershed*This number represents the percent of the total annual massof phosphorus entering the watershed and upstream watershedsthat is removed in the pond and all upstream ponds.
*Data based on results of 2003 P8 modeling.
0 - 25% (Poor/No Treatment)
25 - 40% (Moderate Removal)
40 - 60% (Good Removal)
60 - 100% (Excellent Removal)
0 - 25% (Poor/No Treatment)
25 - 40% (Moderate Removal)
40 - 60% (Good Removal)
60 - 100% (Excellent Removal)
Imagery Source: USDA 2016 NAIP via MnGeo
Area Draining Directly to Minnehaha Creek
Flow Direction
City of Edina 2018 Comprehensive Water Resources Management Plan
13-1
13.0 Southeast Minnehaha Creek
13.1 General Description of Drainage Area
Figure 13.1 depicts the Southeast Minnehaha Creek drainage area and the individual subwatersheds
within this area. The Southeast Minnehaha Creek drainage basin is located in east-central Edina and
contains several ponds, Lake Harvey, Lake Pamela, and Melody Lake.
13.1.1 Drainage Patterns
The stormwater system within this drainage area comprises storm sewers, ponding basins, wetlands,
drainage ditches, and overland flow paths. The Southeast Minnehaha Creek basin has been divided into
several major watersheds based on the drainage patterns. These major watersheds are depicted on
Figure 13.2. Each major watershed has been further delineated into numerous subwatersheds. The
naming convention for each subwatershed is based on the major watershed where it is located.
Table 13.1 lists each major watershed and the associated subwatershed naming convention.
Table 13.1 Major Watersheds within the Southeast Minnehaha Creek Drainage Basin
Major Watershed
Subwatershed Naming
Convention Number of Subwatersheds Drainage Area (acres)
Lake Pamela LP_## 28 279
Minnehaha Creek South MHS_## / MHC_## 90 589
Melody Lake ML_## 16 173
13.1.1.1 Lake Pamela
The Lake Pamela watershed is located in the east central portion of Edina. The entire 279-acre watershed
drains to Lake Pamela and then north to Minnehaha Creek. The land use in this watershed is primarily
low-density residential, with Pamela Park surrounding Lake Pamela. Four stormwater management basins
in this watershed, two on the south end of Lake Pamela and two on the north end, have recently been
constructed to treat stormwater. The two ponds on the north end of the lake also receive runoff from
about half of the Minnehaha Creek South watershed (described below). This runoff is routed through the
ponds, over a weir, to the north bay of Lake Pamela, and finally, to Minnehaha Creek. These ponds were
designed to treat runoff from the Minnehaha Creek South watershed before it is discharged to Minnehaha
Creek. Lake Pamela has been excavated to increase the dead storage volume within the lake for water
quality treatment.
13.1.1.2 Minnehaha Creek South
The Minnehaha Creek South watershed extends from areas just south of the Edina Country Club at Lake
Harvey, west to TH 100 and south to West 54th Street. The land use in this 589-acre watershed is
predominantly low-density residential with some scattered areas of institutional land use. There are no
ponds east of Minnehaha Creek and only a few wet and dry detention ponds in the western half of this
City of Edina 2018 Comprehensive Water Resources Management Plan
13-2
watershed. However, stormwater from most of the western half of the watershed is routed through ponds
and through the northern bay of Lake Pamela before discharging to Minnehaha Creek. Areas directly east
and west of Minnehaha Creek are drained by short storm sewer systems or directly by overland flow.
There is a stormwater control weir in a manhole just east of the intersection of West 58th Street and
Concord Avenue. A pipe leading from the backyard area is part of this system and connects to the
downstream end of the weir-manhole; a flap gate stops water from backing into the pipe. The weir,
located at node 1849, forces water to back into a pipe that discharges to a ball field along Concord
Avenue. This entire system was designed to store water in the ball park and slowly release it back into the
storm sewer system to reduce flood elevations for the nearby principle structures during large storm
events.
13.1.1.3 Melody Lake
Land use in this 173-acre watershed is low-density residential, institutional, and TH 100. The outlet from
Melody Lake is a pumped outlet to the TH 100 drainage system. This system flows north and ultimately
discharges to Minnehaha Creek. The TH 100 storm sewer system was not modeled as part of this study.
13.2 Stormwater System Results
13.2.1 Hydrologic/Hydraulic Modeling Results
The 10-percent-annual-chance and 1-percent-annual-chance flood analyses were performed for the
Southeast Minnehaha Creek drainage basin. The 10-percent-annual-chance analysis was based on a
½ hour storm with 1.65 inches of rain. The 1-percent-annual-chance analysis was based on a 24-hour
storm event with 7.47 inches of rain and on a 10-day snowmelt event with 7.2 inches of runoff; the higher
resulting flood level of the two events was chosen for the 1-percent-annual-chance analysis. Table 13.2
presents the watershed information and the results for the 10- and 1-percent-annual-chance hydrologic
analyses for the Southeast Minnehaha Creek basin. A more detailed description of the stormwater system
analysis is provided in Section 4.1.3.
The results of the 10- and 1-percent-annual-chance hydraulic analyses for the Southeast Minnehaha
Creek drainage basin are summarized in Table 13.3.
Figure 13.3 illustrates the results of the 10- and the 1-percent-annual-chance frequency hydraulic
analyses. The figure depicts the Southeast Minnehaha Creek drainage basin boundary, subwatershed
boundaries, the modeled storm sewer network, surcharge conditions for the XP-SWMM nodes (typically
manholes), and the flood-prone areas identified in the modeling analyses.
Figure 13.3 illustrates that several XP-SWMM nodes within the Southeast Minnehaha Creek drainage
basin are predicted to surcharge during both the 10- and 1-percent-annual-chance events. This means
that in any year there is a greater than 10 percent probability that the system will be overburdened and
unable to meet the desired level of service at these locations. These manholes and catch basins are more
likely to become inundated during the smaller, more frequent storm events of various durations.
City of Edina 2018 Comprehensive Water Resources Management Plan
13-3
To evaluate the level of protection of the stormwater system within the Southeast Minnehaha Creek
drainage area, the 1-percent-annual-chance flood elevations for the ponding basins and depressed areas
were compared to the low elevations of structures surrounding each basin. The areas predicted to
potentially flood and threaten structures during the 1-percent-annual-chance storm event are shown on
Figure 13.3. Discussion and recommended improvement considerations for these areas are included in
Section 13.3.
13.2.2 Water Quality Modeling Results
The effectiveness of the stormwater system in removing stormwater pollutants such as phosphorus was
analyzed using the P8 water quality model. The P8 model simulates the hydrology and phosphorus loads
introduced from each pond’s watershed and the transport of phosphorus throughout the stormwater
system. A more detailed description of the stormwater system analysis is provided in Section 4.1.3.
Figure 13.4 depicts the results of the water quality modeling for the Southeast Minnehaha Creek drainage
basin. The figure shows the fraction of total phosphorus removal for each water body as well as the
cumulative total phosphorus removal in the watershed.
13.3 Implementation Considerations
The 2017 XP-SWMM hydrologic and hydraulic modeling analyses and 2003 P8 water quality analysis
helped identify locations throughout the watershed where improvements to the City’s stormwater
management system may be warranted. The following sections discuss potential improvement options
identified as part of the modeling analyses. As opportunities to address identified flooding issues and
improve water quality arise (e.g., street reconstruction projects or public facilities improvements), the City
will use a comprehensive approach to stormwater management. This approach will include consideration
of infiltration or volume retention practices to address flooding and/or improve water quality, reduction of
impervious surfaces, increased storm sewer capacity where necessary to alleviate flooding, construction
and/or expansion of water quality basins, and implementation of other stormwater BMPs to reduce
pollutant loading to downstream waterbodies.
13.3.1 Flood Protection Projects
The 2017 hydrologic and hydraulic modeling analyses identified several locations within the Southeast
Minnehaha Creek drainage basin where the 1-percent-annual-chance level of protection is not provided
by the current stormwater system. The problem areas identified in 2017 are discussed below.
As part of the 2017 modeling analyses, potential corrective measures were identified for problem areas.
These preliminary corrective measures are also discussed below. As the City evaluates flooding issues and
potential system modifications, other potential modifications, including (but not limited to)
implementation of volume-retention practices, increases in conveyance capacity, and/or stormwater
infiltration (where soils are conducive) will be given consideration.
City of Edina 2018 Comprehensive Water Resources Management Plan
13-4
The 2003 hydrologic and hydraulic modeling analyses also identified several locations within the
Southeast Minnehaha Creek drainage basin where the 1-percent-annual-chance level of protection was
not provided by the stormwater system, based on TP-40 precipitation frequency estimates. The
discussions related to those areas have been carried over to Appendix C of this plan, along with a short
summary of what has been done since 2003.
13.3.1.1 East Golf Terrace Heights Neighborhood
There are several low depression areas within the Golf Terrace Heights neighborhood, including (1) Tower
Street between Fairfax Avenue and Wooddale Avenue and the backyard depressions of the homes along
Tower Street (MHS_75, MHS_76, and MHS_86), (2) the backyard depression north of West 58th Street
between Fairfax Avenue and Wooddale Avenue (MHS_16), and (3) the parking lot of Wooddale Church
and the backyards of homes along West 56th Street (MHS_83). Along Tower Street there are 8 catch basin
inlets with 24-inch pipe, and in the parking lot of Wooddale Church there are 3 catch basin inlets with 15-
inch pipe—both leading to the 24-inch pipe under Wooddale Avenue. In the backyard depression of
MHS_16, there are no inlets and, according to LiDAR data, the surface overflow is between 5712 and 5716
Wooddale Avenue at approximately 880.0 feet.
Modeling results indicate that the 1-percent-annual-chance flood levels are 886.3 feet (MHS_83), 882.4
feet (MHS_75), 880.6 feet (MHS_86), 880.6 feet (MHS_76), and 880.0 feet (MHS_16). For all of these
subwatersheds, except for MHS_16, the 24-hour precipitation event determines the 1-percent-annual-
chance flood level. Based on LiDAR data and approximate building footprints, the 1-percent-annual-
chance flood elevation in subwatershed MHS_83 may impact up to three principle structures (4516, 4520,
and 4524 West 56th Street) in addition to inundating the Wooddale Church parking lot. The 1-percent-
annual-chance flood elevation may impact up to nine principle structures in subwatersheds MHS_75,
MHS_86, and MHS_76 (4519 West 56th Street, 4536–4516 Tower Street, and 4517 and 4513 Tower Street).
Up to six principle structures in subwatershed MHS_16 may be impacted by the 1-percent-annual-chance
flood elevation (5712–5720 Wooddale Avenue and 5709–5717 Fairfax Avenue). The flooding problem is
primarily related to the capacity of the downstream storm sewer system that conveys stormwater east to
Minnehaha Creek. The high flows passing through the single 48-inch pipe east to Minnehaha Creek result
in high velocities, high friction head losses, and a higher surface water profile in this area.
Several system modifications were evaluated to reduce flood elevations in the east portion of the Golf
Terrace Heights neighborhood. The most effective improvement option is to increase the capacity of the
storm sewer system between this area and Minnehaha Creek and install additional inlets to capture peak
flows during large storm events. One drawback to this option is that it would convey more water
downstream to areas with existing flooding issues. However, increasing the capacity of the storm sewer
system is unlikely to affect the peak flood level of Minnehaha Creek due to very different timing of local
flood levels and peak flows along the Minnehaha Creek system. Another option to provide additional
discharge capacity from this area is connecting the existing storm sewer from West 56th Street and
Wooddale Avenue to West 56th Street and Kellogg Avenue. Underground storage with sufficient inlet
capacity under side streets such as West 56th Street, Tower Street, and West Woodland Road should also
City of Edina 2018 Comprehensive Water Resources Management Plan
13-5
be considered to reduce flood risk. Planning-level soil maps show that the soils in this area are “B” soils
with moderate potential for infiltration.
13.3.1.2 Concord and West 58th Street (MHS_59, MHS_26, MHS_58, MHS_42, MHS_53, and MHS_17)
The intersection of Concord Avenue and West 58th Street and surrounding area has experienced flood
problems historically. This low-lying area is drained by the existing storm sewer system. However, when
stormwater flows exceed the capacity of the existing system, water will pool along the roadway and in
adjacent yards until it rises high enough to flow eastward along West 58th Street toward Wooddale
Avenue. In the early-1990s, a stormwater control weir was installed in a manhole just east of the
intersection of West 58th Street and Concord Avenue to reduce the flood risk in this area. The control weir
is designed to divert stormwater to the low area west of Concord Avenue (this area also serves as a
ballfield) during large storm events, storing water and slowly releasing it back into the storm sewer system
once the storm passes.
Atlas 14 model results indicate that the intersection of Concord Avenue and West 58th Street is expected
to be inundated during the 1-percent annual-chance 24-hour storm event, along with portions of West
58th Street east of Concord Avenue, and parts of Ashcroft Avenue and Fairfax Avenue. The 1-percent-
annual-chance flood elevation (882.6 feet) may impact several principle structures between Concord
Avenue and Wooddale Avenue, including 4 structures along Concord Avenue (addresses 5801-5817), 7
structures along Ashcroft Avenue (addresses 5800-5808, 5820, 5801-5809), 2 structures along St. Johns
Avenue (addresses 5805-5809), 6 structures along Fairfax Avenue (5800, 5801, 5724, 5709-5717), and 5
structures along Wooddale Avenue (addresses 5800-5804, 5712-5720), based on LiDAR and approximate
building footprint data. The flooding problem in this area is primarily related to the capacity of the
existing storm sewer system, specifically in the portion that is between Wooddale Avenue and Minnehaha
Creek. High flow velocity through the 48-inch pipe results in significant friction losses that limit outflow
and back water up in the West 58th Street storm sewer system. Significant inflows are contributing to this
one storm sewer line from Concord Avenue north and south of West 58th Street, from Wooddale Avenue
north of West 58th Street, including the neighborhoods between West Woodland Road and Golf Terrace.
Potential improvements to reduce the flood risk in this area include increasing flow capacity in the storm
sewer system between Wooddale Avenue and Minnehaha Creek or creating additional paths for water to
flow to the creek. Detailed modeling of proposed solutions was performed and the results are described
below.
Increased flow capacity: The impact of increasing the flow capacity of the storm sewer pipes
under West 58th Street was evaluated. Tripling the flow capacity from West 58th Street all the way
to Minnehaha Creek reduced the number of potentially impacted principle structures by half,
from 24 to 12, with the most substantial improvements occurring in MHS_42, MHS_53, and
MHS_14.
Diverting storm flows: Several diversion scenarios were evaluated. Diverting runoff from
MHS_53 (intersection of West 58th Street and Ashcroft Avenue) southward along Ashcroft Avenue
City of Edina 2018 Comprehensive Water Resources Management Plan
13-6
to the existing storm sewer system at West 60th Street has similar benefits to the increased flow
capacity improvement option described above with regards to the flood level and number of
potentially impacted structures in the area of Concord Avenue and West 58th Street. Re-routing
storm sewer from West 58th Street and Wooddale Avenue (MHS_65) south to Pamela Park also
has similar benefits to the increased flow capacity improvement option described above with
regards to the flood level and number of potentially impacted structures in the area of Concord
Avenue and West 58th Street. Diverting runoff from MHS_61 (intersection of West 56th Street and
Wooddale Avenue) eastward along West 56th Street to connect to the existing storm sewer at
Kellogg Avenue, instead of routing it south along Wooddale Avenue, has marginal benefits to the
flood level in the area of Concord Avenue and West 58th Street, but did not protect any principle
structures.
The potential improvement alternatives discussed above rely on sending water to Minnehaha Creek more
quickly and using or creating available storage area in Pamela Park. Because the local event in these
subwatersheds peaks much earlier than the regional flood event in Minnehaha Creek, timing may allow
for additional water to be added to the creek and passed downstream before the regional peak comes
through without creating additional impacts to the peak flood level or the number of potentially impacted
structures along the creek. If an alternative is selected that diverts water to Pamela Park, additional
available storage volume may be necessary because there are potentially impacted structures already
adjacent to Pamela Park along West 62nd Street and along Halifax Avenue South.
13.3.2 Construction/Upgrade of Water Quality Basins
When considered individually, the ponds MHS_13, LP_5, and LP_13, and the two bays of Lake Pamela
(LP_14 and LP_26) are removing less that 60 percent of the total phosphorus in stormwater inflows.
Because water from a watershed greater than 500 acres in size is routed through the ponds and the two
bays of Lake Pamela before being discharged to Minnehaha Creek, the cumulative phosphorus removal
by the ponds should be considered. In addition, ponds MHS_13, LP 5, and LP_13 were recently
constructed and designed to function as a treatment train and not individually. On a cumulative basis, the
ponds and Lake Pamela are removing 63 percent of the total phosphorus load from this entire watershed;
as such, it is not necessary to upgrade these ponds.
Because over 60 percent of the total phosphorus in stormwater runoff is being removed by all other
ponds and wetlands in the Southeast Minnehaha Creek watershed, no recommendations are given for the
construction or upgrade of water quality basins in this watershed.
Many techniques are available to reduce pollutant loading from stormwater runoff, including impervious
surface reduction or disconnection, implementation of infiltration or volume-retention BMPs, installation
of underground stormwater treatment structures and sump manholes, and other good housekeeping
practices such as street sweeping. As opportunities arise, the City will consider all of these options to
reduce the volume and further improve the quality of stormwater runoff from this drainage area.
City of Edina
2018 Comprehensive Water Resources Management Plan
13-7
13.3.3 Stream Improvement Projects
13.3.3.1 Minnehaha Creek Reach 14 Stream Restoration
The MCWD’s 2007 Comprehensive Water Resources Management Plan identified a potential capital
improvement project in Edina to implement a stream restoration project on Reach 14 of Minnehaha
Creek. This reach extends from France Avenue to West 54th Street. This project, which incorporated
streambank stabilization, in-stream habitat enhancement, and buffer enhancement, has been completed.
Table 13.2
Watershed Modeling Results for Subwatersheds in the Minnehaha Southeast Drainage Area
1 The 1%-Annual-Chance (100-Year) 10-day snowmelt event is defined as 7.2 inches of runoff
Watershed ID
Total Area
(ac)
% Impervious
Area
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
LP_1 6.5 25 35 2.8 1.2 3.9 14 1.3
LP_10 5.5 25 39 2.5 1.0 3.3 17 1.2
LP_11 11.7 25 81 5.2 2.2 7.0 35 2.5
LP_12 3.6 22 34 1.9 0.7 2.1 18 1.0
LP_13 12.4 25 100 5.6 2.4 7.4 47 2.7
LP_14 26.6 35 178 14.6 5.0 15.9 87 7.8
LP_15 3.8 25 23 1.7 0.7 2.3 10 0.8
LP_16 6.3 25 47 2.8 1.2 3.8 21 1.3
LP_17 16.3 25 114 7.2 3.1 9.8 51 3.4
LP_18 3.9 25 34 1.8 0.7 2.4 16 0.8
LP_19 13.7 25 96 6.1 2.6 8.2 42 2.9
LP_2 6.3 24 58 2.9 1.2 3.8 29 1.4
LP_20 15.6 25 109 6.9 3.0 9.4 48 3.3
LP_21 3.7 25 27 1.7 0.7 2.2 12 0.8
LP_22 9.1 25 70 4.0 1.7 5.4 32 1.9
LP_23 6.0 25 35 2.7 1.1 3.6 15 1.3
LP_24 3.0 25 27 1.5 0.6 1.8 14 0.8
LP_25 4.0 21 34 2.0 0.8 2.4 17 1.0
LP_26 41.3 39 254 22.3 7.8 24.8 121 11.8
LP_27 19.8 25 106 9.6 3.7 11.8 47 4.8
LP_28 1.0 25 6 0.5 0.2 0.6 2 0.2
LP_3 3.2 25 30 1.5 0.6 1.9 15 0.7
LP_4 2.2 25 22 1.0 0.4 1.3 11 0.5
LP_5 8.1 28 71 3.7 1.5 4.8 34 1.8
LP_6 23.0 25 104 10.0 4.3 13.8 43 4.7
LP_7 5.8 25 40 2.6 1.1 3.5 18 1.2
LP_8 9.4 25 74 4.2 1.8 5.6 34 2.0
LP_9 7.0 25 52 3.1 1.3 4.2 24 1.5
MHS_1 1.9 25 7 0.9 0.3 1.1 3 0.5
MHS_10 3.0 25 28 1.6 0.6 1.8 14 0.9
MHS_11 8.2 25 73 3.7 1.6 4.9 35 1.8
MHS_12 10.0 25 63 4.7 1.9 6.0 29 2.3
MHS_13 8.1 25 49 3.6 1.5 4.9 20 1.7
MHS_14 2.2 25 19 1.0 0.4 1.3 9 0.5
MHS_15 4.7 25 39 2.1 0.9 2.8 18 1.0
MHS_16 1.9 25 19 0.8 0.4 1.1 9 0.4
MHS_17 10.2 25 60 4.5 1.9 6.1 25 2.1
MHS_18 1.9 25 14 1.0 0.4 1.1 7 0.5
MHS_19 3.2 35 30 1.5 0.6 1.9 15 0.7
MHS_2 1.6 25 10 0.7 0.3 0.9 4 0.3
MHS_20a 4.0 25 36 1.8 0.8 2.4 17 0.8
MHS_20b 7.0 25 62 3.1 1.3 4.2 30 1.5
MHS_21a 1.5 25 16 0.7 0.3 0.9 8 0.3
MHS_21b 5.2 25 53 2.3 1.0 3.1 28 1.1
MHS_22 23.2 41 122 11.3 4.3 13.9 54 5.7
MHS_23 4.8 50 48 2.4 0.9 2.9 24 1.2
MHS_24 7.0 25 44 3.1 1.3 4.2 19 1.5
MHS_25 6.1 25 35 2.7 1.2 3.7 15 1.3
MHS_26 10.2 27 50 5.0 1.9 6.1 22 2.5
MHS_27 4.3 30 35 2.0 0.8 2.6 16 1.0
MHS_28 4.6 30 32 2.1 0.9 2.8 14 1.0
MHS_29 1.6 25 12 0.7 0.3 1.0 5 0.3
MHS_3 1.5 24 14 0.7 0.3 0.9 7 0.3
MHS_30 1.4 30 12 0.6 0.3 0.8 6 0.3
MHS_31 3.6 25 29 1.6 0.7 2.1 14 0.8
MHS_32 13.4 25 80 6.0 2.5 8.0 34 2.9
MHS_33 2.8 25 14 1.2 0.5 1.7 6 0.6
MHS_34 4.9 25 35 2.2 0.9 2.9 16 1.0
MHS_35 8.2 9 51 3.4 1.6 4.9 21 1.5
MHS_37 1.2 13 6 0.5 0.2 0.7 3 0.2
Watershed Information 1%-Annual-Chance (100-Year)1%-Annual-Chance (100-Year)10%-Annual-Chance (10-Year)
24-Hour Precipitation Event 10-day Snowmelt Event1 24-Hour Precipitation Event
Table 13.2
Watershed Modeling Results for Subwatersheds in the Minnehaha Southeast Drainage Area
1 The 1%-Annual-Chance (100-Year) 10-day snowmelt event is defined as 7.2 inches of runoff
Watershed ID
Total Area
(ac)
% Impervious
Area
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Watershed Information 1%-Annual-Chance (100-Year)1%-Annual-Chance (100-Year)10%-Annual-Chance (10-Year)
24-Hour Precipitation Event 10-day Snowmelt Event1 24-Hour Precipitation Event
MHS_38 0.2 25 3 0.1 0.0 0.1 2 0.1
MHS_39 7.0 25 66 3.4 1.3 4.2 34 1.7
MHS_4 1.8 25 14 0.8 0.3 1.0 6 0.4
MHS_41 3.3 49 36 1.9 0.6 2.0 19 1.0
MHS_42 1.7 25 11 0.9 0.3 1.0 5 0.4
MHS_43 4.3 25 25 1.9 0.8 2.6 11 0.9
MHS_44 2.2 26 15 1.0 0.4 1.3 7 0.5
MHS_45 33.0 25 107 13.9 5.9 19.8 43 6.2
MHS_46 5.6 25 19 2.3 1.0 3.3 8 1.1
MHS_47 7.2 25 64 3.2 1.4 4.3 32 1.5
MHS_47B 3.3 25 31 1.5 0.6 2.0 16 0.7
MHS_48 20.2 26 74 8.7 3.7 12.1 30 4.0
MHS_49 1.8 24 17 0.8 0.3 1.1 9 0.4
MHS_5 6.5 29 59 3.0 1.2 3.9 29 1.4
MHS_50 21.6 25 112 9.5 4.0 12.9 47 4.5
MHS_52 13.3 25 50 5.7 2.4 8.0 20 2.6
MHS_53 13.9 25 66 6.2 2.6 8.4 27 2.9
MHS_55 1.4 25 11 0.7 0.3 0.9 5 0.3
MHS_56 6.0 25 30 2.6 1.1 3.6 13 1.2
MHS_57 24.6 26 127 10.9 4.6 14.8 53 5.1
MHS_57a 2.1 30 21 1.0 0.4 1.3 11 0.5
MHS_58 3.3 30 23 1.6 0.6 2.0 11 0.8
MHS_59 16.0 30 104 7.7 3.0 9.6 47 3.8
MHS_59a 0.6 30 5 0.3 0.1 0.4 3 0.1
MHS_6 2.5 27 21 1.1 0.5 1.5 10 0.5
MHS_60 3.8 25 40 1.7 0.7 2.3 21 0.8
MHS_61 9.4 26 36 4.1 1.7 5.6 15 1.9
MHS_62 10.0 25 34 4.2 1.8 6.0 14 1.9
MHS_63 12.2 31 57 5.5 2.3 7.3 24 2.6
MHS_64 6.7 24 51 3.0 1.3 4.0 24 1.5
MHS_65 5.8 25 44 2.6 1.1 3.5 20 1.2
MHS_66 2.5 25 18 1.2 0.5 1.5 8 0.6
MHS_67 4.4 24 36 2.0 0.8 2.7 17 1.0
MHS_68 4.9 25 44 2.2 0.9 2.9 22 1.1
MHS_69 3.4 25 39 1.5 0.6 2.0 21 0.7
MHS_7 6.5 26 32 2.9 1.2 3.9 13 1.4
MHS_70 1.8 24 13 0.8 0.3 1.1 6 0.4
MHS_71 6.1 25 18 2.5 1.1 3.6 7 1.1
MHS_72 3.4 27 29 1.6 0.6 2.0 14 0.8
MHS_73 2.5 25 22 1.2 0.5 1.5 11 0.6
MHS_74 1.4 25 16 0.7 0.3 0.9 8 0.4
MHS_75 2.0 25 14 0.9 0.4 1.2 6 0.4
MHS_76 2.5 25 22 1.1 0.5 1.5 10 0.5
MHS_77 3.1 25 17 1.3 0.6 1.8 7 0.6
MHS_79 2.1 25 16 1.1 0.4 1.3 8 0.5
MHS_8 5.7 25 59 2.8 1.1 3.4 31 1.4
MHS_80 3.9 25 33 1.7 0.7 2.3 15 0.8
MHS_81 4.8 12 25 2.4 0.9 2.9 11 1.2
MHS_82 2.0 25 13 0.9 0.4 1.2 6 0.5
MHS_83 4.3 27 34 2.0 0.8 2.6 16 1.0
MHS_84 2.4 25 13 1.1 0.5 1.5 5 0.5
MHS_86 2.1 25 14 0.9 0.4 1.3 6 0.4
MHS_87 2.6 25 20 1.1 0.5 1.5 9 0.5
MHS_88 1.8 25 18 0.8 0.3 1.1 9 0.4
MHS_89 0.5 25 5 0.2 0.1 0.3 3 0.1
MHS_9 3.1 25 24 1.5 0.6 1.9 12 0.8
ML_1 3.9 48 34 2.0 0.7 2.4 16 1.0
ML_10 4.0 27 40 1.8 0.8 2.4 20 0.9
ML_11 4.9 25 30 2.2 0.9 3.0 13 1.0
ML_12 9.5 25 55 4.2 1.8 5.7 23 2.0
Table 13.2
Watershed Modeling Results for Subwatersheds in the Minnehaha Southeast Drainage Area
1 The 1%-Annual-Chance (100-Year) 10-day snowmelt event is defined as 7.2 inches of runoff
Watershed ID
Total Area
(ac)
% Impervious
Area
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Watershed Information 1%-Annual-Chance (100-Year)1%-Annual-Chance (100-Year)10%-Annual-Chance (10-Year)
24-Hour Precipitation Event 10-day Snowmelt Event1 24-Hour Precipitation Event
ML_13 42.6 47 146 20.3 7.4 25.5 62 10.0
ML_14 0.4 65 5 0.2 0.1 0.2 3 0.1
ML_15 1.6 30 16 0.7 0.3 1.0 8 0.4
ML_2 7.2 25 64 3.2 1.4 4.3 31 1.5
ML_3 28.2 25 204 12.6 5.3 16.9 91 6.0
ML_3B 8.2 24 81 3.7 1.6 4.9 42 1.8
ML_4 10.8 25 55 4.7 2.0 6.4 22 2.2
ML_5 5.8 25 44 2.6 1.1 3.5 20 1.2
ML_6 4.1 25 30 1.8 0.8 2.4 14 0.9
ML_8 27.8 46 260 13.8 5.3 16.7 129 7.0
ML_9 9.5 23 63 4.2 1.8 5.7 27 2.0
HL_51 3.0 24 23 1.3 0.6 1.8 10 0.6
Table 13.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Southeast Minnehaha Creek
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
102 920.1 919.9
103 913.8 913.7
104 910.7 910.5
109 897.4 897.4
110 896.2 896.2
112 899.8 899.5
113 896.2 894.3
118 910.9 910.9
1219 881.7 878.4
1754 872.6 865.8
1766 862.3 862.3
1767 855.2 ¹ 854.1
1769 874.9 874.9
1775 881.4 881.1
1776 879.6 879.6
1780 882.2 881.9
1784 870.7 870.4
1786 871.0 869.5
1791 864.0 863.2
1793 864.0 863.8
1794 862.9 862.7
1796 862.5 860.5
1808 894.4 894.2
1809 894.4 894.1
1810 894.1 893.8
1811 892.8 892.6
1812 892.0 891.9
1813 891.6 891.4
1814 889.9 889.7
1815 889.1 888.9
1820 891.0 890.0
1822 887.2 887.0
1823 887.3 886.6
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
Table 13.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Southeast Minnehaha Creek
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
1824 884.8 884.5
1826 888.0 887.1
1828 886.8 886.7
1830 881.5 880.5
1833 878.5 877.0
1834 878.4 876.4
1835 881.0 879.9
1836 880.7 877.7
1838 865.0 864.5
1839 862.3 860.1
1840 871.1 869.8
1844 882.6 879.0
1845 882.6 879.3
1846 882.6 879.5
1848 882.6 879.7
1849 882.5 879.9
1854 883.4 883.1
1856 883.0 882.5
1858 882.6 882.0
1859 882.6 880.9
1860 883.9 883.3
1861 884.1 883.8
1862 884.6 884.5
1865 890.6 887.8
1868 894.7 889.5
1993 862.4 860.3
1996 874.6 874.6
2000 862.3 860.1
2003 865.0 864.6
2007 876.4 876.4
2008 879.1 878.7
2009 881.6 880.9
2011 884.4 883.3
Table 13.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Southeast Minnehaha Creek
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
2012 884.4 883.3
2111 866.6 866.3
2112 863.8 863.7
2114 863.6 862.9
2116 863.4 862.4
2118 863.2 861.8
2119 862.3 860.3
2123 862.3 860.1
2125 862.3 860.2
2127 862.3 861.0
2130 865.3 865.0
2131 865.6 865.2
2132 871.0 870.9
2134 867.0 866.8
2136 879.2 879.2
2240 868.1 861.6
2336 871.5 864.6
2338 880.0 879.3
2340 881.7 880.8
2342 882.1 882.1
2374 912.1 911.8
2375 911.1 910.9
2376 907.1 907.0
2425 890.1 889.7
2444 907.9 907.8
2501 901.0 900.9
2502 898.2 898.0
2503 895.7 895.1
2504 895.7 894.9
2512 896.4 896.2
2514 895.7 894.5
2515 895.7 894.5
2516 895.7 895.5
Table 13.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Southeast Minnehaha Creek
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
2517 895.7 895.2
2525 884.4 883.3
2526 884.4 883.3
2527 884.4 883.3
2529 884.4 883.3
2530 884.4 883.3
2531 884.4 883.3
2532 884.4 883.3
2533 884.4 883.3
2534 884.4 883.3
2539 875.1 874.9
2540 875.1 874.9
2541 875.1 874.9
2542 879.1 878.7
2543 879.1 878.7
1769$I 872.9 871.5
1775$I 876.9 876.9
1776$I 874.6 874.6
1780$I 882.2 881.9
2342$I 876.3 876.3
F6561 895.3 894.0
FID1929 893.4 893.2
FID1930 893.1 892.8
FID1931 891.4 891.0
FID1960 883.1 883.1
FID1960$I 877.4 877.3
FID2122 909.4 909.4
FID2124 906.5 906.5
FID2132 881.7 881.4
FID2132$I 877.8 877.7
FID2134 895.0 890.4
FID2471 898.2 896.9
FID-2547 889.3 889.2
Table 13.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Southeast Minnehaha Creek
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
FID2578 913.8 913.6
FID3036 862.1 860.1
FID3037 862.1 860.1
FID325 909.8 909.6
FID326 910.6 909.7
FID396 913.3 913.0
FID4283 868.3 865.3
FID4284 868.3 865.3
FID4300 910.2 910.2
FID4473 907.5 907.5
FID4479 902.0 902.0
FID4481 895.6 895.6
FID4482 896.2 896.2
FID5255 876.7 876.7
FID5256 877.0 877.0
FID5642 895.4 892.1
FID5643 895.2 891.5
FID5644 895.0 891.6
FID6084 906.0 906.0
FID6440 896.2 896.2
FID6560 895.5 892.8
FID6562 895.5 892.1
FID6709 916.7 913.3
FID6710 913.0 911.9
FID6729 912.3 912.3
FID6730 912.0 912.0
FID6731 911.3 911.3
FID6735 915.4 915.4
FID6737 894.4 892.6
FID6738 897.2 897.0
FID6739 908.4 908.4
FID7018 904.8 903.8
FID7027 901.9 900.8
Table 13.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Southeast Minnehaha Creek
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
FID7031 900.7 899.5
FID7032 898.8 898.1
FID7038 897.1 892.5
FID7052 896.9 890.7
FID7054 909.9 909.2
FID7069 897.0 890.7
FID7073 897.0 891.0
FID7075 909.0 908.7
FID7076 906.5 906.4
FID7086 897.0 890.7
FID7088 908.1 907.9
FID7089 908.6 908.4
FID7094 897.1 896.2
FID7095 899.5 899.5
FID7100 909.0 909.0
FID7101 909.3 909.3
FID7102 909.6 909.6
FID7116 903.7 903.7
FID83 868.3 865.3
FIS7122 912.2 912.0
Forebay 862.3 860.1
HL_51 byd 928.9 ¹ 926.9
LP_1 882.4 882.2
LP_10 street 864.7 864.3
LP_11 street 875.1 874.9
LP_12 street 862.3 860.8
LP_13 street 884.4 883.3
LP_14 pond 855.0 862.3 7.3 860.1 5.1
LP_15 street 884.4 883.5
LP_16 street 879.2 879.0
LP_17 street 862.3 860.1
LP_18 street 865.3 865.1
LP_19 street 864.9 864.3
Table 13.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Southeast Minnehaha Creek
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
LP_2 street 862.3 860.1
LP_27 street 884.4 883.2
LP_20 street/yd 891.8 891.6
LP_21 byd 863.9 ¹ 861.3
LP_22 street 863.3 863.1
LP_23 street/byd 884.4 883.3
LP_24 byd 884.4 883.5
LP_25 pond 856.5 862.3 5.8 860.1 3.6
LP_26 pond 856.5 862.3 5.8 860.1 3.6
LP_28 byd 884.4 883.8
LP_3 street 863.2 861.8
LP_4 street 865.7 865.6
LP_5 street 881.2 880.9
LP_6 street 869.7 869.2
LP_7 street 864.1 863.8
LP_8 street 879.5 879.4
LP_9 street 864.7 864.3
MHS_1 868.4 865.9
MHS_10 street 862.5 861.1
MHS_11 street 862.8 862.3
MHS_12 street 864.0 863.3
MHS_13 street 873.0 872.3
MHS_14 byd 881.9 881.0
MHS_15 street/byd 877.9 875.9
MHS_16 byd 880.0 ¹ 878.8
MHS_17 street 882.6 881.3
MHS_17_ori 882.5 878.9
MHS_18 byd 892.1 891.8
MHS_19 pond 884.5 887.7 3.2 886.4 1.9
MHS_2 street 872.4 869.8
MHS_20a street 896.4 896.2
MHS_20b street 894.7 889.4
MHS_21a street 903.9 903.8
Table 13.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Southeast Minnehaha Creek
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
MHS_21b street 897.2 897.1
MHS_22 pond 893.5 895.7 2.2 894.5 1.0
MHS_23 street 887.8 887.7
MHS_24 street 894.3 894.1
MHS_25 depression 895.8 895.7
MHS_26 street/lot 882.6 880.5
MHS_27 byd 882.6 881.7
MHS_28 parking lot 902.0 901.4
MHS_29 byd 895.5 895.4
MHS_3 street 861.1 861.0
MHS_30 889.2 889.0
MHS_31 870.3 870.2
MHS_32 street 881.5 881.2
MHS_32$I 877.6 877.5
MHS_33 street 871.7 871.6
MHS_33$I 871.5 871.5
MHS_34 street 881.4 881.3
MHS_35 pond 894.0** 898.4 4.4 898.2 4.2
MHS_37 street 872.5 872.2
MHS_38 street 862.5 860.5
MHS_39 street 862.5 862.0
MHS_4 byd 875.7 875.3
MHS_41 pond 857.0 862.1 5.1 860.1 3.1
MHS_42 byd 882.6 879.8
MHS_43 street 895.2 895.0
MHS_44 street 884.8 884.5
MHS_45 street 872.6 872.4
MHS_46 street 878.6 878.2
MHS_47 street 880.7 880.3
MHS_47B 894.9 894.9
MHS_48 street 885.4 885.2
MHS_49 street 887.9 887.4
MHS_5 882.8 882.7
Table 13.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Southeast Minnehaha Creek
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
MHS_50 885.0 884.7
MHS_50$I 885.0 884.7
MHS_52 street 876.3 876.1
MHS_53 street 882.7 879.8
MHS_53_orf 882.7 879.7
MHS_55 street 874.6 874.4
MHS_55$I 873.3 872.6
MHS_56 street 877.2 876.4
MHS_56$I 875.2 875.2
MHS_57 street 883.6 883.2
MHS_57a street 898.9 898.9
MHS_58 ditch 882.6 882.0
MHS_59 byd 882.6 880.5
MHS_59a ball field 882.6 880.5
MHS_6 street 888.0 888.0
MHS_60 creek 859.8 859.8
MHS_61 street 884.6 884.4
MHS_62 street 882.1 882.0
MHS_63 858.0 857.7
MHS_64 creek 855.9 855.5
MHS_65 street 885.9 885.7
MHS_66 byd 894.1 892.7
MHS_67 street 867.4 867.2
MHS_68 street 896.1 895.9
MHS_69 street 875.5 873.3
MHS_7 street 868.1 867.8
MHS_70 street 888.5 888.4
MHS_71 street 892.8 892.6
MHS_72 street 875.7 875.3
MHS_73 street 877.3 874.1
MHS_74 byd 872.5 872.3
MHS_75 byd 882.4 881.9
MHS_76 byd 880.6 879.8
Table 13.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Southeast Minnehaha Creek
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
MHS_77 street 882.5 881.5
MHS_79 street 880.9 880.8
MHS_79$I 878.2 878.2
MHS_8 street/yd 862.5 860.5
MHS_80 street 893.9 893.7
MHS_81 pond 856.0 862.3 6.3 860.1 4.1
MHS_82 street 891.0 889.8
MHS_83 street 886.3 886.2
MHS_84 street 888.3 887.6
MHS_86 street/yd 880.6 880.3
MHS_87 880.2 879.7
MHS_88 byd 896.0 895.4
MHS_89 byd 883.4 883.4
MHS_9 street/yd 862.5 860.5
ML_1 street 895.3 894.9
ML_10 byd 915.4 914.4
ML_11 street 935.9 934.4
ML_12 street 936.2 935.5
ML_13 street 896.9 890.7
ML_14 street 911.3 910.9
ML_15 street 911.7 910.5
ML_2 street 906.3 906.1
ML_3 street 899.4 898.7
ML_3B street 918.9 918.8
ML_4 street 916.1 915.9
ML_5 904.9 904.9
ML_6 street 916.7 916.3
ML_8 pond 887.4 894.0 6.6 890.7 3.3
ML_8a 894.5 890.7
ML_9 street 916.4 916.3
N207 882.6 879.7
N30 880.5 877.8
SouthEastP 862.3 860.1
Table 13.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Southeast Minnehaha Creek
Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
To_NC_55 882.7 879.8
Weirnode 862.4 860.2
100
4567158
456717
456721
456731
France Ave Valleyview Rd
Normandale Blvd W 53rd St
W 60th St Mi
n
nehaha
C
r
e
e
kNorthBranchNineMile
Cre
e
kMinneapolisMinneapolis
RichfieldRichfield
LP_26
MHC_4
ML_13
MHC_5
ML_3
ML_8
LP_6
LP_14
MHS_45
LP_27
MHS_57
MHS_22
MHS_50
LP_17
LP_20
MHS_48
LP_19
MHS_59
LP_13
ML_4
LP_11
LP_8
ML_9
MHS_53
MHS_32
MHS_52
LP_5
MHS_63
LP_22
ML_12
LP_9
ML_2
MHS_26
MHS_17
LP_1
MHS_62
MHS_12
LP_2
ML_3B MHS_61
LP_7
ML_1
ML_5
MHS_11
LP_16
MHS_35
MHS_13
LP_23
MHS_7 MHS_5
LP_10
MHS_47
MHS_39MHS_24
MHS_64
MHS_8
ML_11
MHS_20b
MHS_25
MHS_71
ML_6
MHS_56
MHS_65
MHS_46
LP_25
LP_18
LP_3
ML_10
LP_15
MHS_34
LP_21
MHS_68
MHS_15
LP_12
MHS_28
MHS_21b MHS_67
MHS_27
MHS_43
MHS_83
MHS_80
HL_51 MHS_60
MHS_9
MHS_31
LP_4
MHS_58
MHS_41
MHS_19
MHS_10
MHS_47B
MHS_76
MHS_84
MHS_81
MHS_44
MHS_86
MHS_4
MHS_75
MHS_18
MHS_88
MHS_55
MHS_23
LP_24
MHS_20a
MHS_72
MHS_69
MHS_77
MHS_6
MHS_33MHS_87
MHS_66
MHS_73
MHS_14
MHS_1
MHS_79
MHS_82
ML_15
MHS_57a
MHS_16
MHS_70
MHS_49
MHS_2
MHS_3
MHS_42
MHS_29
MHS_74
LP_28
MHS_21a
MHS_37
MHS_30
MHS_59a
MHS_89ML_14
MHS_38
Melody Lake
Lake Pamela
Lake Harvey
Barr Footer: ArcGIS 10.4.1, 2017-09-21 12:17 File: \\barr.com\gis\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_13_1_MC_Southeast_Drainage_Basins.mxd User: rcs2FIGURE 13.1
0 1,000
Feet
!;N
Southeast Minnehaha CreekDrainage Basin
Subwatershed
Streets and Highways
Creek/Stream
City of Edina Boundary
Lake/Wetland
Imagery Source: MnGeo; 2016
SOUTHEAST MINNEHAHA CREEKDRAINAGE BASINComprehensiveWater ResourcesManagement PlanCity of Edina, Minnesota
100
4567158
456717
456721
456731
France Ave Valleyview Rd
Normandale Blvd W 53rd St
W 60th St Mi
n
nehaha
C
reekNineMi l eCre
e
k
Minnehaha Creek South
Lake Pamela
Melody Lake
MinneapolisMinneapolis
RichfieldRichfield
Melody Lake
Lake Pamela
Lake Harvey
Barr Footer: ArcGIS 10.4.1, 2017-09-21 12:18 File: \\barr.com\gis\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_13_2_MC_Southeast_Major_Watersheds.mxd User: rcs2FIGURE 13.2
0 1,000
Feet
!;N
Southeast Minnehaha CreekDrainage Basin
Major Watershed
Lake Pamela
Melody Lake
Minnehaha Creek South
Subwatershed
Streets and Highways
Creek/Stream
City of Edina Boundary
Lake/Wetland
Imagery Source: MnGeo; 2016
SOUTHEAST MINNEHAHA CREEKMAJOR WATERSHEDSComprehensiveWater ResourcesManagement PlanCity of Edina, Minnesota
NorthBranch
City of Edina 2018 Comprehensive Water Resources Management Plan
13-24
Figure 13.3 Southeast Minnehaha Creek Hydraulic Model Results
This is a large drawing (34x44).
Due to the paper and size and file size, this figure is included as a stand-alone PDF.
MHS_35
MHS_22
MHS_19
MHS_41
ML_8
LP_13LP_5
MHS_13
MHS_13
LP_14
LP_26
RichfieldRichfield
MinneapolisMinneapolis
Minnehaha Creek
Barr Footer: ArcGIS 10.4.1, 2018-03-26 11:36 File: I:\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_13_4_MC_Southeast_Water_Quality.mxd User: EMASOUTHEAST MINNEHAHA CREEKWATER QUALITY MODELING RESULTSComprehensive Water ResourceManagement PlanCity of Edina, Minnesota
FIGURE 13.4
1,000 0 1,000Feet
300 0 300Meters
Percent TP Removal in Water Body*This number represents the percent of the total annual massof phosphorus entering the water body that is removed.
Cumulative TP Removal in Watershed*This number represents the percent of the total annual massof phosphorus entering the watershed and upstream watershedsthat is removed in the pond and all upstream ponds.
*Data based on results of 2003 P8 modeling.
0 - 25% (Poor/No Treatment)
25 - 40% (Moderate Removal)
40 - 60% (Good Removal)
60 - 100% (Excellent Removal)
0 - 25% (Poor/No Treatment)
25 - 40% (Moderate Removal)
40 - 60% (Good Removal)
60 - 100% (Excellent Removal)
Imagery Source: USDA 2016 NAIP via MnGeo
Area Draining Directly to Minnehaha Creek
Flow Direction
City of Edina 2018 Comprehensive Water Resources Management Plan
14-1
14.0 Northwest Minnehaha Creek
14.1 General Description of Drainage Area
Figure 14.1 depicts the Northwest Minnehaha Creek drainage basin and the individual subwatersheds
within this area. The Northwest Minnehaha Creek drainage basin is located in the far northwest corner of
Edina, east of the TH 169 North drainage area. This watershed is the smallest of the Minnehaha Creek
watersheds and extends from TH 100 to areas west of the Interlachen Golf Course.
14.1.1 Drainage Patterns
The stormwater system within this drainage area comprises storm sewers, ponding basins, wetlands,
drainage ditches, and overland flow paths. The Northwest Minnehaha Creek basin has been divided into
several major watersheds based on the drainage patterns. These major watersheds are depicted on
Figure 14.2. Each major watershed has been further delineated into numerous subwatersheds. The
naming convention for each subwatershed is based on the major watershed where it is located.
Table 14.1 lists each major watershed and the associated subwatershed naming convention.
Table 14.1 Major Watersheds within the Northwest Minnehaha Creek Drainage Basin
Major Watershed
Subwatershed Naming
Convention Number of Subwatersheds Drainage Area (acres)
TH 100 H100_## 32 150
Hopkins HO_## 25 94
Interlachen EI_## 38 360
14.1.1.1 TH 100
The land use in this 150-acre watershed is primarily commercial and most of the runoff drains to a trunk
storm sewer system along TH 100 that flows north to Minnehaha Creek. The pipe system and ponds
within the Grandview Square development were also incorporated in the hydraulic and water quality
models.
14.1.1.2 Hopkins
The Hopkins watershed is located just south of the City of Hopkins and west of the Interlachen Country
Club. This is a small watershed and consists of 94 acres of total land area. All of the water in this
watershed is routed north by a lift station to a Hopkins storm sewer system. The land use is primarily low-
density residential with several ponds and wetlands.
14.1.1.3 Interlachen
The 360-acre Interlachen watershed consists of the Interlachen Country Club and residential areas
adjacent to the golf course. There are several ponds and wetlands that provide storage and treatment for
City of Edina 2018 Comprehensive Water Resources Management Plan
14-2
runoff in this watershed, but few storm sewer pipes. Water conveyed by the storm sewer system drains
north to Minnehaha Creek. Modeling of the culverts and storm sewer within the Interlachen Country Club
is based on historical reference maps showing proposed pipes connecting the ponds. A survey of actual
field conditions may be warranted in the future to improve the accuracy of model results within this
watershed.
14.2 Stormwater System Results
14.2.1 Hydrologic/Hydraulic Modeling Results
The 10- and 1-percent-annual-chance flood analyses were performed for the Northwest Minnehaha Creek
drainage basin. For the Northwest Minnehaha Creek watersheds, the storm sewers were evaluated using
10- and 1-percent-annual-chance storm events. The 10-percent-annual-chance analysis was based on a
½-hour storm with 1.65 inches of rain. The 1-percent-annual-chance analysis was based on a 24-hour
storm event with 7.47 inches of rain and on a 10-day snowmelt event with 7.2 inches of runoff; the higher
resulting flood level of the two events was chosen for the 1-percent-annual-chance analysis. The storm
sewers in Table 14.2 present the watershed information and the results for the 10- and 1-percent-annual-
chance hydrologic analyses for the Northwest Minnehaha Creek basin. A more detailed description of the
stormwater system analysis is provided in Section 4.1.3.
The results of the 10- and 1-percent-annual-chance hydraulic analysis for the Northwest Minnehaha Creek
drainage basin are summarized in Table 14.3.
Figure 14.3 illustrates the results of the 10- and the 1-percent-annual-chance hydraulic analyses. The
figure depicts the Northwest Minnehaha Creek drainage basin boundary, subwatershed boundaries, the
modeled storm sewer network, surcharge conditions for the XP-SWMM nodes (typically manholes), and
the flood-prone areas identified in the modeling analyses.
Figure 14.3 illustrates that several XP-SWMM nodes within the Northwest Minnehaha Creek drainage
basin are predicted to surcharge during both the 10- and 1-percent-annual-chance events. This means
that in any year there is a greater than 10 percent probability that the system will be overburdened and
unable to meet the desired level of service at these locations. These manholes and catch basins are more
likely to become inundated during the smaller, more frequent storm events of various durations.
To evaluate the level of protection of the stormwater system within the Northwest Minnehaha Creek
drainage area, the 1-percent-annual-chance flood elevations for the ponding basins and depressed areas
were compared to the low elevations of structures surrounding each basin. The areas predicted to
potentially flood and threaten structures during the 1-percent-annual-chance storm event are shown on
Figure 14.3. Discussion and recommended improvement considerations for these areas are included in
Section 14.3.
City of Edina 2018 Comprehensive Water Resources Management Plan
14-3
14.2.2 Water Quality Modeling Results
The effectiveness of the stormwater system in removing stormwater pollutants such as phosphorus was
analyzed using the P8 water quality model. The P8 model simulates the hydrology and phosphorus loads
introduced from each pond’s watershed and the transport of phosphorus throughout the stormwater
system. A more detailed description of the stormwater system analysis is provided in Section 4.1.3.
Figure 14.4 depicts the results of the water quality modeling for the Northwest Minnehaha Creek
drainage basin. The figure shows the fraction of total phosphorus removal for each water body as well as
the cumulative total phosphorus removal in the watershed.
14.3 Implementation Considerations
The 2017 XP-SWMM hydrologic and hydraulic modeling analyses and 2003 P8 water quality analysis
helped identify locations throughout the watershed where improvements to the City’s stormwater
management system may be warranted. The following sections discuss potential improvement options
identified as part of the modeling analyses. As opportunities to address identified flooding issues and
improve water quality arise (e.g., street reconstruction projects or public facilities improvements), the City
will use a comprehensive approach to stormwater management. This approach will include consideration
of infiltration or volume retention practices to address flooding and/or improve water quality, reduction of
impervious surfaces, increased storm sewer capacity where necessary to alleviate flooding, construction
and/or expansion of water quality basins, and implementation of other stormwater BMPs to reduce
pollutant loading to downstream waterbodies.
14.3.1 Flood Protection Projects
The 2017 hydrologic and hydraulic modeling analyses identified several locations within the Northwest
Minnehaha Creek drainage basin where the 1-percent-annual-chance level of protection is not provided
by the current stormwater system. The problem areas identified in 2017 are discussed below.
As part of the 2017 modeling analyses, potential corrective measures were identified for problem areas.
These preliminary corrective measures are also discussed below. As the City evaluates flooding issues and
potential system modifications in these areas, other potential modifications, including (but not limited to)
implementation of volume-retention practices, increases in conveyance capacity, and/or stormwater
infiltration (where soils are conducive) will be given consideration.
The 2003 hydrologic and hydraulic modeling analyses also identified several locations within the
Northwest Minnehaha Creek drainage basin where the 1-percent-annual-chance level of protection was
not provided by the stormwater system, based on TP-40 precipitation frequency estimates. The
discussions related to those areas have been carried over to Appendix C of this plan, along with a short
summary of what has been done since 2003.
City of Edina 2018 Comprehensive Water Resources Management Plan
14-4
14.3.1.1 Blake Road South and Spruce Road (HO_4)
At the southeast corner of Blake Road South and Spruce Road, there is a local depression in the backyard
area with one inlet draining to a 21-inch pipe and a surface overflow at approximately 922.5 feet. The
21-inch pipe draining this area connects to the storm sewer on Spruce Road that eventually discharges to
a wet pond south of Belmore Lane (HO_8) and just west of the Interlachen golf course. The 1-percent-
annual-chance flood elevation of HO_4 (921.9 feet) may impact five principle structures (300–308 John
Street and 301 and 309 Blake Road South), based on LiDAR and approximate building footprint
information.
Further downstream, an 18-inch pipe drains HO_8 to another pond (HO_19) which significantly restricts
the outflow from HO_8 and raises the water level in HO_8. This creates a tailwater effect on the pipes
between HO_4 and HO_8 and limits the outflow from HO_4.
The most likely option to reduce flooding impacts in the backyard depression area is to increase the
downstream pipe capacity. This may also require upsizing the existing lift station in HO_19 (currently
about 500 gpm capacity). There are multiple options to achieve this goal: (1) increase the size of the pipe
connecting the two wet ponds (HO_8 and HO_19), (2) add an additional outlet pipe from the wet pond to
the Interlachen Golf Course where storage is available and no structures can be impacted, or (3) install a
new pipe connecting the existing storm sewer under Spruce Road to the Interlachen Golf Course.
Additional storage could also be created around several small depressions within the golf course. The
feasibility of conveying additional water to the golf course and/or adding storage volume in the golf
course may be low because it is private property.
14.3.2 Construction/Upgrade of Water Quality Basins
Several ponds in this watershed are removing less than 60 percent of the average annual phosphorus load
from stormwater inflows. The light blue ponds on Figure 14.4 are achieving less than 60 percent total
phosphorus removal; however, the cumulative phosphorus removal was greater than 60 percent for all the
subwatersheds. Additional analysis was performed to identify which ponds were functioning properly and
which were functioning poorly. In the P8 model, phosphorus particles are grouped into several fractions.
The unsettleable (dissolved) fraction is called P0. From the mass balance output of the P8 model, the
percent of total phosphorus removal for the other settleable phosphorus fractions was evaluated for the
apparently “non-performing” ponds to determine if the ponds were removing greater than 60 percent of
the settleable phosphorus fractions. From this analysis it was determined that these ponds were removing
greater than 60 percent of the settleable phosphorus and performing adequately. As a result, no ponds in
this watershed require upgrades.
Many techniques are available to reduce pollutant loading from stormwater runoff, including impervious
surface reduction or disconnection, implementation of infiltration or volume-retention BMPs, installation
of underground stormwater treatment structures and sump manholes, and other good housekeeping
practices such as street sweeping. As opportunities arise, the City will consider all of these options to
reduce the volume and further improve the quality of stormwater runoff from this drainage area.
Table 14.2
Watershed Modeling Results for Subwatersheds in the Minnehaha Northwest Drainage Area
1 The 1%-Annual-Chance (100-Year) 10-day snowmelt event is defined as 7.2 inches of runoff
Watershed ID
Total Area
(ac)
% Impervious
Area
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
EI_1 10.2 45 92 5.3 1.9 6.1 47 2.8
EI_10 12.7 44 105 6.2 2.4 7.6 50 3.1
EI_11 1.5 25 11 0.7 0.3 0.9 5 0.3
EI_12 5.1 34 49 2.4 1.0 3.1 25 1.2
EI_13 8.1 30 79 3.7 1.5 4.9 40 1.8
EI_14 11.1 25 65 4.9 2.1 6.7 27 2.3
EI_15 13.3 37 120 6.3 2.5 8.0 59 3.1
EI_16 15.9 26 85 7.0 3.0 9.5 35 3.3
EI_17 3.0 30 27 1.4 0.6 1.8 13 0.7
EI_18 10.5 25 80 4.7 2.0 6.3 36 2.2
EI_19 16.2 55 139 8.8 3.1 9.7 70 4.7
EI_2 17.0 25 138 8.8 3.2 10.2 69 4.5
EI_20 23.5 25 151 10.7 4.4 14.1 67 5.2
EI_21 4.3 38 41 2.2 0.8 2.6 21 1.2
EI_22 3.2 25 26 1.5 0.6 1.9 12 0.7
EI_23 3.7 25 27 1.7 0.7 2.2 12 0.8
EI_24 22.6 31 185 10.7 4.3 13.6 89 5.3
EI_25 7.8 17 72 4.1 1.5 4.7 38 2.1
EI_25a 2.9 6 25 1.0 0.5 1.7 10 0.4
EI_26 5.2 18 39 2.4 1.0 3.1 19 1.1
EI_27 2.7 5 17 1.4 0.5 1.6 8 0.7
EI_28 5.9 10 36 3.1 1.1 3.5 18 1.7
EI_29 9.8 11 67 5.3 1.9 5.9 33 2.8
EI_3 20.6 22 79 10.5 3.7 12.4 35 5.4
EI_30 3.6 5 28 2.0 0.7 2.2 14 1.0
EI_31 6.0 23 52 3.3 1.1 3.6 27 1.8
EI_32 11.9 19 62 6.0 2.2 7.1 28 3.0
EI_33 8.3 2 41 4.1 1.6 5.0 19 2.0
EI_34 15.7 11 64 7.5 2.9 9.4 27 3.6
EI_35 25.2 25 149 11.4 4.8 15.1 64 5.5
EI_36 2.9 25 26 1.3 0.5 1.7 13 0.6
EI_37 1.5 25 14 0.7 0.3 0.9 7 0.3
EI_4 14.6 25 115 6.7 2.8 8.8 54 3.3
EI_5 7.3 25 68 3.3 1.4 4.4 34 1.6
EI_6 1.9 25 16 0.8 0.4 1.1 7 0.3
EI_7 7.8 25 52 3.5 1.5 4.7 23 1.6
EI_8 18.6 25 121 8.2 3.5 11.1 53 3.9
EI_9 3.9 25 30 1.7 0.7 2.3 14 0.8
HO_1 4.7 25 34 2.1 0.9 2.8 15 1.0
HO_10 1.6 25 11 0.7 0.3 0.9 5 0.3
HO_11 1.8 25 16 0.8 0.3 1.1 8 0.4
HO_12 2.0 25 16 0.9 0.4 1.2 7 0.4
HO_13 1.3 25 13 0.6 0.2 0.8 6 0.3
HO_14 2.2 25 17 1.0 0.4 1.3 8 0.5
HO_15 3.3 25 31 1.5 0.6 2.0 15 0.7
HO_15a 1.4 25 15 0.6 0.3 0.8 8 0.3
HO_16 2.7 46 28 1.3 0.5 1.6 15 0.7
HO_17 15.4 25 92 6.8 2.9 9.2 39 3.2
HO_18 2.0 25 14 0.9 0.4 1.2 6 0.4
HO_19 13.0 25 95 5.8 2.5 7.8 43 2.8
HO_2 1.1 21 10 0.5 0.2 0.6 5 0.2
HO_20 0.8 25 9 0.3 0.1 0.5 5 0.2
HO_20a 0.6 25 7 0.3 0.1 0.3 4 0.1
HO_21 0.7 25 8 0.3 0.1 0.4 4 0.2
HO_22 3.7 25 30 1.7 0.7 2.2 14 0.8
HO_3 6.5 25 29 2.8 1.2 3.9 12 1.3
HO_4 2.6 25 22 1.1 0.5 1.5 11 0.5
HO_5 8.2 25 55 3.7 1.6 4.9 24 1.7
HO_6 4.9 25 41 2.2 0.9 3.0 19 1.1
HO_7 1.5 25 13 0.7 0.3 0.9 6 0.3
Watershed Information 1%-Annual-Chance (100-Year)1%-Annual-Chance (100-Year)10%-Annual-Chance (10-Year)
24-Hour Precipitation Event 10-day Snowmelt Event1 24-Hour Precipitation Event
Table 14.2
Watershed Modeling Results for Subwatersheds in the Minnehaha Northwest Drainage Area
1 The 1%-Annual-Chance (100-Year) 10-day snowmelt event is defined as 7.2 inches of runoff
Watershed ID
Total Area
(ac)
% Impervious
Area
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Peak Runoff Rate
(cfs)
Total Volume
Runoff
(ac-ft)
Watershed Information 1%-Annual-Chance (100-Year)1%-Annual-Chance (100-Year)10%-Annual-Chance (10-Year)
24-Hour Precipitation Event 10-day Snowmelt Event1 24-Hour Precipitation Event
HO_8 8.0 37 80 3.8 1.5 4.8 41 1.9
HO_8_19 0.8 3 8 0.3 0.1 0.5 4 0.1
HO_9 3.5 27 17 1.5 0.7 2.1 7 0.7
H100_1 9.2 25 56 4.1 1.7 5.5 24 1.9
H100_10 5.2 30 33 2.4 1.0 3.1 14 1.1
H100_11 0.5 25 4 0.2 0.1 0.3 2 0.1
H100_12 2.4 25 17 1.1 0.5 1.4 7 0.5
H100_13 2.6 50 31 1.4 0.5 1.6 17 0.7
H100_13a 0.8 64 9 0.4 0.1 0.5 5 0.2
H100_13b 1.1 42 12 0.5 0.2 0.6 7 0.3
H100_13c 0.2 65 2 0.1 0.0 0.1 1 0.1
H100_13d 0.6 42 7 0.3 0.1 0.3 4 0.2
H100_14 4.1 70 40 2.3 0.8 2.5 21 1.2
H100_15 5.9 72 66 3.3 1.1 3.6 36 1.8
H100_15a 0.8 77 10 0.5 0.2 0.5 5 0.3
H100_16 12.0 63 125 6.4 2.3 7.2 66 3.4
H100_17 1.8 67 21 0.9 0.3 1.0 11 0.5
H100_18 5.5 66 62 3.0 1.0 3.3 33 1.6
H100_19 10.8 48 107 5.5 2.1 6.5 55 2.9
H100_2 3.6 34 24 1.7 0.7 2.2 10 0.8
H100_20 2.9 65 34 1.6 0.6 1.8 18 0.9
H100_21 0.4 28 5 0.2 0.1 0.2 3 0.1
H100_22 4.0 60 47 2.1 0.8 2.4 26 1.1
H100_23 1.2 56 14 0.6 0.2 0.7 8 0.3
H100_24 5.1 74 57 2.8 1.0 3.1 31 1.5
H100_25 1.0 37 11 0.5 0.2 0.6 6 0.2
H100_26 0.5 25 5 0.2 0.1 0.3 3 0.1
H100_27 0.5 25 6 0.2 0.1 0.3 3 0.1
H100_3 12.4 48 69 6.1 2.3 7.4 31 3.1
H100_4 10.8 65 96 5.8 2.0 6.5 48 3.1
H100_5 14.1 75 83 7.9 2.6 8.5 40 4.3
H100_6 4.2 28 36 1.9 0.8 2.5 17 0.9
H100_7 21.3 34 143 10.9 4.0 12.8 68 5.6
H100_8 0.6 25 6 0.3 0.1 0.4 3 0.1
H100_9 4.5 25 29 2.0 0.9 2.7 12 0.9
Table 14.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Northwest Minnehaha
Creek Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1885 914.4 914.0
1886 914.3 913.8
1889 950.9 949.5
1891 950.4 948.4
1892 949.4 947.7
1893 948.8 947.3
1894 947.6 946.5
1895 947.0 946.1
1896 946.4 945.7
1897 945.3 944.9
1898 943.6 943.3
1906 924.4 923.8
1907 917.8 917.4
1908 906.5 905.7
1911 905.9 905.4
1912 898.0 897.4
1913 894.3 893.3
2156 900.9 900.5
2159 929.5 929.1
2160 930.0 929.7
2161 931.1 930.9
2162 931.2 931.0
2163 942.9 942.8
2173 919.0 918.7
2175 918.2 916.3
2177 892.7 892.2
2183 922.7 919.5
2186 921.9 916.4
2187 919.8 916.2
2188 918.9 916.1
2189 917.3 915.8
2191 916.9 915.8
2200 921.9 921.7
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
Table 14.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Northwest Minnehaha
Creek Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
2203 925.2 923.5
2204 925.2 923.5
2210 925.2 923.5
2214 931.3 931.3
2215 930.0 929.9
2217 925.2 924.7
2218 925.2 924.7
2268 910.8 909.5
2271 912.2 912.1
2344 892.5 892.0
2346 891.8 891.5
2347 891.8 891.5
2348 890.6 890.4
2349 890.4 890.1
2350 890.3 889.9
2351 890.3 ¹ 889.6
2352 890.3 ¹ 889.4
2353 890.3 ¹ 889.3
2356 893.9 892.9
2357 893.9 892.9
2358 893.9 892.9
2364 927.5 927.4
2365 924.1 923.9
2366 920.8 920.5
2367 920.4 920.2
2368 919.5 918.8
2370 919.5 918.1
2372 919.2 917.7
2421 900.6 900.0
2442 923.4 921.9
2443 923.1 920.9
2456 897.4 897.2
2457 895.7 895.6
Table 14.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Northwest Minnehaha
Creek Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
EI_1 pond 887.2 892.4 5.3 891.2 4.1
EI_10 pond 887.9** 890.5 2.6 889.9 2.0
EI_11 cul-de-sac 922.6 917.4
EI_12 pond 912.1** 916.4 4.3 914.5 2.4
EI_13 pond 896.0** 903.0 ¹ 7.0 900.3 4.3
EI_14 street 891.5 889.8
EI_15 street 908.7 908.5
EI_16 902.6 902.1
EI_17 937.0 928.4
EI_18 street 891.7 890.9
EI_19 pond 879.5** 890.3 ¹ 10.8 889.2 9.7
EI_2 street 895.7 895.5
EI_20 field 890.3 ¹ 889.2
EI_21 pond 884.6 890.3 ¹ 5.7 889.2 4.6
EI_22 street 890.2 ¹ 889.2
EI_23 street 892.9 892.7
EI_24 pond 883.5** 890.3 ¹ 6.8 889.2 5.7
EI_25 pond 889.0 893.9 4.9 892.9 3.9
EI_25a byd 893.9 892.9
EI_26 pond 905.8** 910.4 4.6 910.3 4.5
EI_27 pond 901.8** 905.2 3.4 905.0 3.2
EI_28 byd 897.3 896.9
EI_29 pond 898.1 902.1 4.0 901.5 3.4
EI_3 street 893.9 892.9
EI_30 depression 906.1 904.9
EI_31 pond 896.3 898.7 2.4 898.4 2.1
EI_32 pond 906.6 907.1 0.5 906.8 0.2
EI_33 byd 903.9 903.2
EI_34 pond 887.1** 893.9 6.8 892.9 5.8
EI_35 byd 897.3 897.0
EI_36 byd 952.4 952.3
EI_37 byd 948.8 947.0
EI_4 street 892.7 892.5
Table 14.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Northwest Minnehaha
Creek Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
EI_5 street/yd 892.5 892.0
EI_6 street 892.7 892.5
EI_7 street 946.1 945.9
EI_8 street 929.2 928.8
EI_9 921.3 920.7
FID-6920 910.4 909.4
FID2551 915.6 914.8
FID2933 906.9 904.6
FID2934 906.9 904.6
FID2950 906.9 904.6
FID320 918.5 917.5
FID322 912.4 912.1
FID4130 908.2 908.0
FID4404 890.3 889.3
FID5827 925.2 924.5
FID5828 924.6 924.2
FID5864 925.5 924.9
FID6889 907.5 907.2
FID6890 907.7 907.4
FID6892 905.9 902.3
FID6899 906.3 903.1
FID6921 906.7 904.1
FID6926 906.6 904.2
FID6927 909.4 908.2
FID6932 906.6 904.3
FID6940 907.1 904.6
FID6950 908.0 905.7
FID6963 907.1 905.0
FID6969 907.1 905.1
FID6970 907.1 905.1
FID6971 907.1 905.1
FID6979 907.1 905.8
FID6988 910.5 908.5
Table 14.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Northwest Minnehaha
Creek Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
FID6989 907.1 905.4
FID6990 907.1 905.3
FID6992 904.9 904.6
FID7001 908.4 906.5
FID7002 910.6 910.6
FID7005 915.1 914.3
FID7006 909.7 907.4
FID7008 909.8 908.1
FID7011 911.3 908.8
FID7062 912.6 908.8
FID7063 908.0 906.7
H100_1 hwy ditch 950.8 950.6
H100_10 910.9 910.7
H100_11 street 920.9 920.2
H100_12 street 918.5 918.0
H100_13 street 908.0 905.7
H100_13a basin 911.8 910.7
H100_13b street 908.8 908.5
H100_13c 909.6 909.3
H100_13d street 911.4 909.5
H100_14 pond 917.0 919.5 2.5 918.4 1.4
H100_15 street 912.2 910.7
H100_15a 926.2 923.6
H100_16 hwy ditch 905.2 900.9
H100_17 basin 910.4 909.6
H100_18 hwy ditch 906.6 903.7
H100_19 basin/lot 907.0 904.7
H100_2 ditch 951.1 949.9
H100_20 hwy ditch 907.1 905.0
H100_21 907.7 906.3
H100_22 hwy ditch 907.1 905.1
H100_23 hwy ditch 910.9 908.1
H100_24 934.4 934.3
Table 14.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Northwest Minnehaha
Creek Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
H100_25 903.8 903.7
H100_26 915.0 914.9
H100_27 916.6 914.1
H100_3 938.4 938.2
H100_4 pond 928.8 929.3 0.5 929.0 0.2
H100_5 street 914.4 914.0
H100_6 street 915.9 913.7
H100_7 street 908.0 905.7
H100_8 street 919.5 918.2
H100_9 street/byd 913.9 913.7
HO_1 byd 918.4 918.1
HO_10 byd 923.8 923.4
HO_11 street 925.2 923.5
HO_12 street 922.9 922.7
HO_13 921.7 921.6
HO_14 byd 927.8 927.6
HO_15 street 920.0 919.8
HO_15a byd 918.3 918.0
HO_16 pond 917.5 925.2 7.7 923.5 6.0
HO_17 street 925.2 924.2
HO_18 street/yd 925.2 924.1
HO_19 pond 910.6 915.4 4.8 915.0 4.4
HO_2 byd 919.4 917.1
HO_20 street 931.9 931.8
HO_20a street 929.4 929.1
HO_21 byd 945.1 945.0
HO_22 byd 927.0 926.8
HO_3 street 918.0 915.9
HO_4 byd 921.9 916.5
HO_5 street/yd 916.5 915.7
HO_6 street 921.9 921.7
HO_7 street 925.2 923.5
HO_8 pond 912.0 916.5 4.5 915.7 3.7
Table 14.3
Hydraulic Modeling Results for XP-SWMM Subwatersheds/Nodes in the Northwest Minnehaha
Creek Drainage Basin
Flood Elevation
(ft)
Flood Bounce
(ft)
Flood Elevation
(ft)
Flood Bounce
(ft)
1%-Annual-Chance (100-Year)
Storm Event Results
10%-Annual-Chance (10-Year)
Storm Event Results
24-Hour Precipitation Event 24-Hour Precipitation EventSubwatershed or
Node3
Type of
Storage2
Outlet
Elevation
(ft)4
HO_8_19 field 916.4 915.3
HO_9 street 933.9 932.9
N64 919.7 919.7
Node81 892.4 891.3
Node82 892.5 891.8
Node83 street 892.5 891.9
Node84 892.5 891.9
Node85 892.5 892.0
100
4567158
Interlachen Blvd Eden Ave
EI_1
EI_2
EI_4
EI_5
EI_6
EI_7
EI_9
EI_10
EI_11
EI_12
EI_14
EI_15
EI_16
EI_17
EI_18EI_20 EI_23EI_24
EI_22EI_21
EI_13 EI_19
EI_26
EI_27
EI_33
EI_29
EI_3
EI_25EI_34
EI_28
EI_35
EI_8
EI_36
EI_37
H100_1
H100_2
H100_3
H100_6
H100_4
H100_14
H100_5 H100_15
HO_5
HO_9
HO_2
HO_19
HO_12HO_10 HO_4
HO_16
HO_17
HO_7
HO_18HO_21 HO_22
HO_1
HO_6
HO_15
HO_8HO_14
HO_13
HO_20
HO_3
HO_11
EI_25a
H100_15a
EI_32
HO_20a
EI_30
EI_31
HO_8_19
HO_15a
H100_8
H100_12
H100_9
H100_10
H100_13
H100_13b
H100_18
H100_13a
H100_24
H100_13c
H100_19
H100_27
H100_26
H100_25
H100_17
H100_16
H100_23
H100_22
H100_20
H100_7
H100_13d
H100_21
North Branch Nine Mile Creek
Saint LouisSaint Louis
ParkPark
Saint LouisSaint Louis
ParkParkHopkinsHopkins
M innehahaCreek
Barr Footer: ArcGIS 10.4.1, 2017-09-14 15:19 File: I:\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_14_1_MC_Northwest_Drainage_Basins.mxd User: EMAFIGURE 14.1
0 1,000
Feet
!;N
Northwest Minnehaha CreekDrainage Basin
Subwatershed
Streets and Highways
Creek/Stream
City of Edina Boundary
Lake/Wetland
Imagery Source: MnGeo; 2016
NORTHWEST MINNEHAHA CREEKDRAINAGE BASINComprehensiveWater ResourcesManagement PlanCity of Edina, Minnesota
North Branch Nine Mile Creek
Saint LouisSaint Louis
ParkPark
Saint LouisSaint Louis
ParkParkHopkinsHopkins
M innehahaCreek
Hopkins
Interlachen
TH 100
Barr Footer: ArcGIS 10.4.1, 2017-09-21 12:27 File: \\barr.com\gis\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_14_2_MC_Northwest_Major Subwatersheds.mxd User: rcs2FIGURE 14.2
0 1,000
Feet
!;N
Northwest Minnehaha CreekDrainage Basin
Major Watershed
Hopkins
Interlachen
T.H. 100
Subwatershed
Streets and Highways
Creek/Stream
City of Edina Boundary
Lake/Wetland
Imagery Source: MnGeo; 2016
NORTHWEST MINNEHAHA CREEKMAJOR SUBWATERSHEDSComprehensiveWater ResourcesManagement PlanCity of Edina, Minnesota
City of Edina 2018 Comprehensive Water Resources Management Plan
14-16
Reserved for:
Figure 14.3 Northwest Minnehaha Creek Hydraulic Model Results
This is a large drawing (34x44).
Due to the paper and size and file size, this figure is included as a stand-alone PDF.
HO_16
HO_8
HO_19 EI_32
EI_29
EI_31
EI_30
EI_27
EI_26 EI_25 EI_25
EI_1
EI_13 EI_19
EI_24
EI_21
EI_10
EI_12
EI_6
EI_20
H100_4
H100_14
HopkinsHopkins St. LouisSt. Louis
ParkPark
Minn ehahaCre e k
Barr Footer: ArcGIS 10.4.1, 2018-03-26 11:36 File: I:\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_14_4_MC_Northwest_Water_Quality.mxd User: EMANORTHWEST MINNEHAHA CREEKWATER QUALITY MODELING RESULTSComprehensive Water ResourceManagement PlanCity of Edina, Minnesota
FIGURE 14.4
1,000 0 1,000Feet
300 0 300Meters
Percent TP Removal in Water Body*This number represents the percent of the total annual massof phosphorus entering the water body that is removed.
Cumulative TP Removal in Watershed*This number represents the percent of the total annual massof phosphorus entering the watershed and upstream watershedsthat is removed in the pond and all upstream ponds.
*Data based on results of 2003 P8 modeling.
0 - 25% (Poor/No Treatment)
25 - 40% (Moderate Removal)
40 - 60% (Good Removal)
60 - 100% (Excellent Removal)
0 - 25% (Poor/No Treatment)
25 - 40% (Moderate Removal)
40 - 60% (Good Removal)
60 - 100% (Excellent Removal)
Imagery Source: USDA 2016 NAIP via MnGeo
Area Draining Directly to Minnehaha Creek
Flow Direction
City of Edina 2018 Comprehensive Water Resources Management Plan
15-1
15.0 Issues and Implementation Program
The City of Edina provides three core services through its water resources program; runoff management,
flood control, and clean water services. The provision of these services takes place using two primary
strategies, the lifecycle delivery of physical infrastructure, and programmatic activities.
The City also provides a variety of additional water resource services that support the core services,
protect natural resources, and improve recreational opportunities, including lake and pond management,
and wetland and natural resource protection. The provision of these services is provided primarily with
programmatic activities.
This chapter describes the programs and activities that support each of the three core services and some
of the policy issues around the provision and growth of service. This chapter also discusses resources,
financial considerations, and implementation priorities. Table 15.1 summarizes details of the City’s
implementation program activities, including a project description, cost estimate, potential funding
sources, and proposed years of implementation.
Table 15.2 summarizes the potential implementation activities to be undertaken in the next ten years,
including capital improvements. Funding for capital improvements comes primarily from the City’s
Stormwater Utility, as described in Section 15.4.5 Financial Considerations. At the time of this plan’s
writing, the priority area for the Flood Risk Reduction Strategy is the Morningside neighborhood in the
Minnehaha Creek Watershed District and the priority area for the Clean Water Strategy is Lake Cornelia in
the Nine Mile Creek Watershed District. Programmatic activities and capital improvements will be
evaluated in conjunction with strategy development. The City’s Capital Improvement Program will set
forth, by year, details including schedule, estimated cost, and funding source. The Capital Improvement
Program is described further in Section 15.4.3 Prioritization.
15.1 Flood Protection and Runoff Management
Flooding is a concern for the city and its residents due to the threat to public safety and potential for
significant property damages and economic losses. Flooding can cause other damages that are harder to
quantify, including the following:
• Flooding of roads so they are impassable to emergency vehicles and residents
• Reduced redevelopment potential
• Shoreline erosion
• Increased pollutants in stormwater discharges
• Destruction of riparian habitats and vegetation such as grass, shrubs, trees, etc.
City of Edina 2018 Comprehensive Water Resources Management Plan
15-2
• Unavailability of recreational facilities for use by the public (e.g., inundation of shoreline) and/or
restricted recreational use of waterbodies
• Increased demand for emergency services and risk to emergency responders during flood events
• More strain on budgets and personnel for repairing flood-damaged facilities and controlling
public use of facilities during flooding events
• Alterations to the mix and diversity of wildlife species as a result of inundation of habitats
In 2016-2017, the City of Edina updated their hydrologic and hydraulic models to reflect the increased
precipitation frequency estimates for the region based on NOAA’s 2013 Atlas 14 publication. The updated
precipitation frequency depths result in increased flood risk throughout the city. The Atlas 14 hydrologic
and hydraulic modeling and flood risk mapping analysis identified numerous flood-prone locations
throughout the city, including some areas along the creeks, near lakes or wetlands, and areas adjacent to
or within low areas where stormwater pools during large storm events. While many of the flood-prone
areas are localized, some of the flooding problems are more regional in nature.
Beyond Atlas 14, climatologists indicate that large, intense rainfall events are occurring more frequently
and climate change predictions indicate large rainfall events will become more extreme in the future in
this region. These changing rainfall patterns will result in additional flood risk for the city and its residents
and businesses.
The increasing imperviousness trend in urban areas, combined with the increased precipitation due to
climate change and reflected in the NOAA Atlas 14 publication, translates to increased flood risk
throughout the community.
15.1.1 Flood protection and runoff management infrastructure
Municipal stormwater systems provide multiple functions, including runoff management (removal of
stormwater) and flood protection. Design of stormwater infrastructure is guided by the criteria set forth in
Section 3.1 including level of service and the level of protection criteria.
Level of service is defined as the capacity provided by municipal drainage systems to remove runoff and
prevent significant interference with normal daily transportation, commerce, or access that might result
from a rainstorm. For example, gutters might run full, but when the runoff arrives at a catch basin it would
enter the catch basin and be carried away by the storm sewer. Intersections would not be inundated to an
extent that adversely impacts driving conditions, right-of-way would be undamaged, and public
infrastructure would operate normally. Level of protection is defined as the capacity provided by a
municipal drainage system to prevent property damage and assure a reasonable degree of public safety
following a rainstorm. For example, runoff might bypass a catch basin and collect in low-lying areas such
as intersections, but would not cause flood damage to structures. The City applies these design criteria,
where feasible, as part of street reconstruction and other improvement projects. The City also seeks to
apply these design criteria as development or redevelopment occurs. However, some existing stormwater
City of Edina 2018 Comprehensive Water Resources Management Plan
15-3
conveyance systems throughout the city have capacity limitations and cannot be guaranteed to provide
the desired discharge capacity where private storm sewer systems tie into the trunk system. In these
cases, the City will work with private property owners during the redevelopment process to help them
understand capacity limitations of the trunk storm sewer system and associated implications for site
stormwater management.
The City of Edina operates and maintains all of the City’s stormwater facilities, and permits and accepts
connections from private systems. The operation and maintenance of stormwater facilities is an important
part of stormwater management. The City’s stormwater system includes not only pipes and constructed
ponds, but also lakes, wetlands, ditches, swales, and other drainage ways. In addition to more typical
maintenance measures, maintenance of the stormwater system may also mean maintaining or restoring
the ecological characteristics of the natural portions of the stormwater system. Operation and
maintenance of the City’s stormwater system is discussed further in Section 15.3.
15.1.2 Flood protection and runoff management programs
15.1.2.1 Assessing Risk
The City regularly reviews this plan when improvement projects are proposed to evaluate risks and
opportunities for addressing flood issues. The hydrologic and hydraulic models are also continually
updated and consulted as private and public entities other than the City propose projects. Risk
assessments in problem areas based on the models are used to define applicable development and
redevelopment standards, help project owners to understand their risk, and mitigate risk to adjacent
areas.
15.1.2.2 Communicating Risk
Building an understanding of the flooding and drainage risks in the community, both among agencies
and community members, is important for working toward resiliency. When a community understands its
risks, it can take actions to mitigate risk before, during, and after a flood event. The City maintains detailed
maps regarding flooding and drainage issues, both regionally and locally, and intends to share this
information via the City website.
15.1.2.3 Land Use Controls
The Floodplain Districts Overlay Ordinance (City Code Chapter 36) governs some land use decisions
related to floodplain and flood-prone areas for the regional and local flood. The standards are intended
to mitigate flood risk over time as properties redevelop.
Chapter 10 of City Code enables staff to require stormwater management plans on qualifying residential
and commercial sites. The code is intended to protect neighboring lots so that conditions do not get
worse, however, this often means that the already overtaxed public system takes on more volume (see
Policy Issues Section 15.4.7.
City of Edina 2018 Comprehensive Water Resources Management Plan
15-4
15.1.2.4 Technical Assistance
The City has a Certified Floodplain Manager (CFM) to act as the local liaison for FEMA floodplain issues.
The CFM provides technical assistance for Letter of Map Amendments, maintains elevation certificates,
and interprets requirements for development and redevelopment that intersect with the FEMA regulated
floodplain areas.
15.1.3 Flood Risk Reduction Strategy
As part of this 10-year plan, the City of Edina will develop a Flood Risk Reduction Strategy that outlines a
plan for working toward reducing flood risk, where appropriate, and meeting its stormwater management
goals for providing a 1-percent-annual-chance (100-year) level of protection. The strategy will identify and
characterize flood problems throughout the city and identify strategies and infrastructure improvements
to address flood-prone areas. The strategy will include preparation of planning-level cost estimates to
help understand the potential financial investment required to meet the City’s flood protection goals and
the anticipated timeframe for implementation. When completed, the Flood Risk Reduction Strategy will be
included as an amendment to this CWRMP.
At the time of this plan’s writing, the focus area for the Flood Risk Reduction Strategy is the Morningside
neighborhood in the Minnehaha Creek Watershed District.
15.1.3.1 Implementation Approaches
The Flood Risk Reduction Strategy will detail the City’s approach to addressing the flood-prone areas
identified based on Atlas 14 precipitation frequency estimates, which include the following
implementation categories:
• Engineered Improvements- flood risk reduction strategies will be implemented through
engineered capital improvement projects, such as increasing stormwater discharge capacity,
creating additional upstream stormwater storage, diverting stormwater, and/or grading and
landscape modifications. These may occur as standalone flood and drainage projects or in
conjunction with other projects such as neighborhood roadway reconstruction or parks
improvements.
• Anticipated Redevelopment- flood risk reduction strategies will be implemented as
redevelopment occurs, through stormwater infrastructure improvements, grading and landscape
modifications, and/or raising structures above flood elevations.
• Residential Redevelopment- flood risk reduction strategies will be implemented as homes are
remodeled or reconstructed, through private stormwater infrastructure improvements, grading
and landscape modifications, and/or raising structures above flood elevations.
• Incentivized Retrofits- where engineered improvements are cost prohibitive or not feasible due to
site constraints and redevelopment is not anticipated the City may provide incentives to property
owners to conduct grading and landscape modifications or modify structures to reduce flood risk.
City of Edina 2018 Comprehensive Water Resources Management Plan
15-5
• Risk Acceptance- where engineered improvements to reduce flood risk are cost prohibitive or not
feasible due to site constraints, and redevelopment is not anticipated, it may be necessary to
accept a lower level of protection.
Making incremental improvements to address flooding issues throughout the city will require a mix of
capital infrastructure investments, programmatic approaches (development/redevelopment review), and
regular operation and maintenance. Along with the approaches described here, Table 3.2. Strategies and
Potential Actions for Addressing Local and Regional Flood Issues provides a variety of tools for working
towards flood resiliency.
15.1.3.2 Opportunity Identification/Prioritization
The Flood Risk Reduction Strategy will focus on identification and prioritization of flood reduction efforts.
The City will seek to maximize cost effectiveness and capitalize on coinciding opportunities, such as
planned street reconstruction, redevelopment, availability of land, and other planned infrastructure
improvement projects. Consideration will also be given to achieving additional “co-benefits”, such as
water quality improvements, open space expansion, and wildlife habitat improvement.
Development of the Flood Risk Reduction Strategy is identified as an action item in Table 15.1. Potential
flood risk reduction implementation activities are identified in Table 15.2.
_______________________________________________
1 To be determined
City of Edina 2018 Comprehensive Water Resource Management Plan
15-6
Table 15.1 Water Resources Implementation Program
Project Name / Location Description Proposed Improvement Cost Estimate ($)
Proposed
Year Funding Source
Plan Amendments This Water Resources Management Plan
may need to be amended periodically. This plan will be amended as required. As Required As
Required SW Utility
Plan Update/Revision
This Water Resources Management Plan
will expire in 2028 and will need to be
updated/revised to be consistent with
WMO plans and policies and state and
federal rules.
This Plan will be updated to maintain
compliance with state and federal rules
and WMO policies.
100,000 2027-2029 SW Utility
City-wide education and resident
involvement
Create and implement City’s Education
Plan including educational and outreach
tasks called out in the City’s SWPPP.
Maintain level of activity to involve and
educate residents with various water
related issues.
10,000/yr Annual SW Utility
Illicit discharge detection and
elimination
Continue implementation of the SWPPP
Illicit discharge detection and elimination
tasks.
Inventory, mapping, inspection,
enforcement and education. City Staff Annual SW Utility
Interactive GIS water resources
web mapping tool
Annual updates and maintenance
activities for interactive GIS web mapping
tool, as needed.
Web mapping tool will have continued
functionality and reflect most up-to-date
information available.
2,000 Annual SW Utility
Construction site stormwater
runoff control
Maintain construction site stormwater
runoff control program and SWPPP tasks.
Plan review, inspection, enforcement and
education. City Staff Annual SW Utility
Post construction stormwater
management
Maintain the post construction
stormwater management and SWPPP
tasks.
Design standards and review, education. City Staff Annual SW Utility
Street Sweeping Pollution prevention through regular
street sweeping.
Strategic street sweeping in target areas
and at optimal times to minimize
pollution to surface waters.
City Staff
(3000 hours
annually)
Annual SW Utility
_______________________________________________
1 To be determined
City of Edina 2018 Comprehensive Water Resource Management Plan
15-7
Project Name / Location Description Proposed Improvement Cost Estimate ($)
Proposed
Year Funding Source
Storm Drainage System
Maintenance Maintain the storm drainage system.
Structure clean-out, outlet sedimentation
removal, maintenance and training,
inspections and recording with
concentration of efforts in target areas.
City Staff
(1400 hours
annually)
Annual SW Utility
City facility operations and
maintenance Manage city facilities to prevent pollution Regularly inspect facilities and adjust
practices to prevent pollution City Staff Annual SW Utility
Storm Drainage System Inventory Manage inventory of storm sewers,
manholes, catch basins, etc.
Actively manage database. Continue to
incorporate private infrastructure and
stormwater BMPs into inventory. Share
stormwater network on interactive map.
City Staff Ongoing SW Utility
Updates to Hydrologic and
Hydraulic Modeling
Annual updates to City’s stormwater
management system modeling to reflect
infrastructure improvements.
Current, up-to-date modeling results. 28,000/year Annual SW Utility
Impaired Waters Tracking and
Review
Monitor impaired waters list and respond
with review and implementation as
needed per the SWPPP.
The City will remain informed and
responsive to impaired waters issues. City Staff Ongoing SW Utility
Annual SWPPP update and
meeting
Make any needed updates to the City’s
SWPPP and hold an annual public
meeting to receive public input.
Involve residents in water resource issue
development and implementation tasks. City Staff Annual SW Utility
Flooding and drainage
improvements
Opportunistic flooding and drainage
improvements to be addressed in street
reconstruction projects, development /
redevelopment, and other capital
projects.
200,000/yr plus
opportunistic
Capital
Improvement
Projects
Ongoing SW Utility
_______________________________________________
1 To be determined
City of Edina 2018 Comprehensive Water Resource Management Plan
15-8
Project Name / Location Description Proposed Improvement Cost Estimate ($)
Proposed
Year Funding Source
Water Conservation Policy Review
Review and adapt as necessary an
ordinance that is protective of
groundwater quality and quantity. To be determined. City Staff 2018 -
2019 SW Utility
Implementation of Stormwater
Management Ordinance
Adopt and implement a stormwater
management ordinance reflecting the
policies and design standards detailed in
this plan.
To be determined. Related to Flood Risk
Reduction Strategy and Clean Water
Strategy outcomes.
City Staff TBD1 SW Utility
Wellhead Protection Plan
Implement wellhead protection plan and
provide plan updates to MCWD and
NMCWD.
Effectively manage and reduce where
possible the number of potential
contamination sources, namely private
wells, through outreach and development
review.
City Staff Ongoing SW Utility
Water Reuse Potential Investigate water reuse potential as
opportunities arise. To be determined. City Staff Ongoing SW Utility
Infiltration and Inflow reduction Reduce the amount of infiltration and
inflow to the sanitary sewer system.
Reduce the amount of infiltration and
inflow to the sanitary sewer system. 600,000/year Ongoing SW Utility
Implementation of Nine Mile
Creek Chloride TMDL
Implement the requirements of the Nine
Mile Creek Chloride TMDL.
BMPs per the Nine Mile Creek Watershed
Chloride TMDL Report, to be incorporated
into Clean Water Strategy.
City Staff Ongoing
SW Utility/
NMCWD/
Grant Funding
Participation in the NMCWD Lake
Cornelia Use Attainability Analysis
(UAA) update
Partner with the NMCWD to evaluate
potential remedial measures for
improving the water quality of Lake
Cornelia.
To be determined. City Staff 2018 SW Utility
_______________________________________________
1 To be determined
City of Edina 2018 Comprehensive Water Resource Management Plan
15-9
Project Name / Location Description Proposed Improvement Cost Estimate ($)
Proposed
Year Funding Source
Participation in the NMCWD Lake
Edina Use Attainability Analysis
(UAA) development
Partner with the NMCWD to evaluate
potential remedial measures for
improving the water quality of Lake
Edina.
To be determined. City Staff 2018
SW
Utility/NMCWD/
Grant Funding
Participation in Lower Minnesota
River WRAPS
Participate in stakeholder process for
Lower MN River WRAPS including Lake
Cornelia, Lake Edina, and Nine Mile
Creek.
To be determined. City Staff 2017-2019 SW Utility
Implementation of
recommendations from the Lower
Minnesota River WRAPS and
NMCWD UAAs
Partner with the NMCWD to implement
the recommended remedial measures to
improve the water quality of Lake
Cornelia, Lake Edina, Nine Mile Creek.
To be determined and addressed in Clean
Water Strategy. TBD1 2018-2028
SW Utility/
NMCWD/
Grant Funding
Participation in the NMCWD
Mirror Lake Use Attainability
Analysis (UAA) update and
implement recommendations
Partner with the NMCWD to update UAA
and implement recommended remedial
measures to improve the water quality of
Mirror Lake.
To be determined. TBD1 2022
SW Utility/
NMCWD/
Grant Funding
Participation in the NMCWD
Arrowhead and Indianhead Lakes
Use Attainability Analysis (UAA)
update and implement
recommendations
Partner with the NMCWD to update UAA
and implement recommended remedial
measures to improve the water quality of
Arrowhead and Indianhead Lakes.
To be determined. TBD1 2021
SW Utility/
NMCWD/
Grant Funding
Evaluate Zoning Ordinance
Revisions
Evaluate zoning ordinance revisions
needed to incorporate shoreland
management. Revise zoning ordinance as
needed.
City Staff 2018 SW Utility
_______________________________________________ 1 To be determined City of Edina 2018 Comprehensive Water Resource Management Plan 15-10 Project Name / Location Description Proposed Improvement Cost Estimate ($) Proposed Year Funding Source Engineering Standards Development Continue to develop and implement stormwater management design standards. Consider ordinance changes as needed. City Staff 2018-2019 SW Utility Lake and Pond Management – aquatic vegetation Implement lake and pond management policy to manage requests for aquatic vegetation destruction. 45,000/yr Annual SW Utility Stormwater pond evaluation Accessory to Clean Water Strategy. Review of stormwater ponds to determine pollutant removal and develop maintenance schedule. 10,000 2018 SW Utility Flood Risk Reduction Strategy Develop a strategy and plan for working toward reducing flood risk, where appropriate, and meeting stormwater management goals for providing a 1-percent-annual-chance (100-year) level of protection. The strategy will identify and characterize flood problems throughout the city and identify strategies and infrastructure improvements to address flood-prone areas. The strategy will include preparation of planning-level cost estimates to help understand the potential financial investment required to meet the City’s flood protection goals and the anticipated timeframe for implementation. 190,000 2018 SW Utility/Grant Funding
_______________________________________________ 1 To be determined City of Edina 2018 Comprehensive Water Resource Management Plan 15-11 Project Name / Location Description Proposed Improvement Cost Estimate ($) Proposed Year Funding Source Clean Water Strategy Develop a water quality implementation program which outlines a plan for working toward meeting water quality goals. A tool to gain feedback from City Council and set the pace, location, and ultimate goal for clean water. 5-year implementation strategy to be reviewed annually. Identifies water quality CIP and regular housekeeping practices, quantifies pollution removal, provides cost estimates. Determine pollutant load reduction necessary for nondegradation of water bodies. Coordinated with street reconstruction projects, redevelopment, park improvements, and other opportunity areas. Incorporates various TMDLs/WRAPS/UAAs/CWRMP items and various BMPs. Has annual or biannual reporting to quantify movement toward goal – can also be used for annual SWPPP and MS4 reporting. 200,000 2019 - 2020 SW Utility/Grant Funding Arden Park Restoration Enhancements to the park to improve fish passage, wildlife habitat, and water quality. Removing 54th Street dam, re-meandering the creek, adding fishing and recreation accesses, and managing stormater. 4,000,000 2018-2019 SW Utility/ MCWD/Grant Funding
_______________________________________________
In the ID column, D = detailed analysis conducted for flood-prone area (pink)
In the ID column, S = screening level analysis conducted for flood-prone area (yellow)
In the ID column, R = registered flood-prone area: identified as a flood-prone area but not studied further for this CWRMP (blue)
City of Edina 2018 Comprehensive Water Resource Management Plan
15-12
Table 15.2 Potential Implementation Activities (including Capital Improvements)
ID
2018 CWRMP
Section Project Name/Location Proposed Improvement
Nine Mile Creek—North
S1 5.3.1.1 Maloney Avenue and Tyler Court (ML_35
and ML_19)
Upgrade the downstream 18” pipe to a larger pipe.
Create an upstream pipe restriction to limit inflow
and use upstream storage.
S2 5.3.1.2 Between Leslee Lane and Kaymar Drive
(MD_22)
Upgrade the outlet pipes to larger pipes. Lower, or
at least maintain, the surface overflow to Jeffrey
Lane.
S3 5.3.1.3 Parkwood Road and Schaefer Road
(MD_28, MD_29, and MD_35)
Underground storage combined with infiltration (B
soils) under Parkwood Road. Lower, or at least
maintain, the surface overflows between homes.
S4 5.3.1.4 Schaefer Road and View Lane (MD_38) Install a pipe to the east to Bredesen Park.
S5 5.3.1.5 Nine Mile Village Townhomes (MD_49)
Construct a berm on the west side of Villa Lane.
Redirect overflow from Bredesen Park slightly to
the south.
S6 5.3.1.6
Hawkes Lake and Upstream Surrounding
Area (HL_1, HL_11c, HL_11w, HL_49, and
HL_12)
Increase the capacity of the pumped outlet and the
downstream gravity drain. Add storage in the city-
owned parcel in MD_15.
R1 5.2.1 Colonial Church Parking Lot and Colonial
Way (CO_3, CO_4, and CO_10) N/A; to be studied.
R2 5.2.1 Nine Mile Creek, Malibu Drive (NMN_60) N/A; to be studied.
R3 5.2.1 Blake Road South and South Knoll Drive
(MD_24 and MD_25) N/A; to be studied.
R4 5.2.1 Nine Mile Creek, south of Londonderry
Drive, west of Walnut Drive (EdCrk3) N/A; to be studied.
R5 5.2.1 Nine Mile Creek, northwest of Vernon
Avenue South and View Lane (EdCrk5) N/A; to be studied.
R6 5.2.1 Olinger Boulevard and Sun Road (MD_15) N/A; to be studied.
Appendix C Hawkes Drive (HL_2) Construction of overflow swale between homes.
Appendix C 5711 and 5717 Grove St (HL_18) Upgrade to larger pipes.
Appendix C 5516 and 5520 Dundee Rd (HL_25) Perform detailed field survey. Additional pumping
capacity may be required at lift station.
_______________________________________________
In the ID column, D = detailed analysis conducted for flood-prone area (pink)
In the ID column, S = screening level analysis conducted for flood-prone area (yellow)
In the ID column, R = registered flood-prone area: identified as a flood-prone area but not studied further for this CWRMP (blue)
City of Edina 2018 Comprehensive Water Resource Management Plan
15-13
ID
2018 CWRMP
Section Project Name/Location Proposed Improvement
Appendix C Fountain Woods Apartments (NMN_90
and NMN_23)
Privately owned drainage system. Notify owners of
flood potential.
Nine Mile Creek—Central
S7 6.3.1.1 Antrim Road and Chapel Drive (NMC_41)
Survey homes to confirm flooding problem.
Individual flood-proofing. Lower, or at least
maintain, the surface overflow between homes.
S8 6.3.1.2 Ridgeview Drive (NMC_106 and NMC_107)
Survey homes to confirm flooding problem. Install
a gravity system, with a backflow preventer, to Nine
Mile Creek on the other side of the railroad tracks.
Install a pipe to connect to existing storm sewer at
Tifton Drive and Ridgeview Drive.
S9 6.3.1.3 West 66th Street and Naomi Drive
(NMC_71, NMC_74, and NMC_103)
Pumped outlet to Normandale Park, with additional
storage added in the park, or a gravity system to
Nine Mile Creek. Could connect to Nine Mile Creek
through NMC_106 if that proposed improvement is
constructed.
R7 6.2.1 Cherokee Trail (IP_2 and IP_4) N/A; to be studied.
R8 6.2.1 Nine Mile Creek, north of the West 70th
Street crossing (NMC_1) N/A; to be studied.
R9 6.2.1 Valley View Road and Hillside Road
(NMC_84, NMC_86, and NMC_120) Street Reconstruction Project for Edina in 2017.
R10 6.2.1 TH 62 at Nine Mile Creek crossing
(NMC_104) N/A; to be studied.
R11 6.2.1 TH 62 at Tracy Avenue (NMC_28, NMC_94,
NMC_93, NMC_92, and NMC_87) N/A; to be studied.
Appendix C 6005 and 6009 Crescent Dr (manhole 457) Construction of a positive overflow channel.
Appendix C Cherokee Trail and Gleason Backyard
Depression Area (IP_4)
Work with homeowners to evaluate construction of
a low level outlet from landlocked depression.
Appendix C 5339 West 64th Street (NMC_80) Upgrade to larger pipes at Ridgeview Drive and
Valley Lane.
Appendix C Valley View Road and Hillside Road
(NMC_86 and NMC_120) Upgrade to larger pipe.
Lake Cornelia/Lake Edina/Adam’s Hill
D1 7.3.1.1 Southdale Road Neighborhood (LE_34,
LE_36, and LE_43)2 Increase the pipe size and the weir size north to
Lake Cornelia. Prevent flow from Valley View Road
_______________________________________________
In the ID column, D = detailed analysis conducted for flood-prone area (pink)
In the ID column, S = screening level analysis conducted for flood-prone area (yellow)
In the ID column, R = registered flood-prone area: identified as a flood-prone area but not studied further for this CWRMP (blue)
City of Edina 2018 Comprehensive Water Resource Management Plan
15-14
ID
2018 CWRMP
Section Project Name/Location Proposed Improvement
with berms and/or floodwalls. Increase pipe
capacity south to Lake Edina.
D2 7.3.1.2
Southwest Corner of TH 62 and TH 100
(NC_7, NC_8, NC_13, NC_11, NC_12,
NC_14, NC_15, NC_16, and NC_20)2
Increase the pipe capacity of the downstream 30-
inch pipe and adding inlets in the West 64th Street
area. Underground storage under streets north of
West 64th Street. Increase the pipe capacity from
North Cornelia all the way into NC_9.
R12 7.2.1 Garrison Lane and St. Johns Avenue,
northeast (NC_5 and NC_49) N/A; to be studied.
R13 7.2.1 Garrison Lane and St. Johns Avenue,
southeast (NC_2) N/A; to be studied.
R14 7.2.1 South Cornelia, east side (SC_1) N/A; to be studied.
R15 7.2.1 Lake Edina (LE_1, LE_10, and LE_7) N/A; to be studied.
R16 7.2.1 Heatherton Trail (LE_29) N/A; to be studied.
R17 7.2.1 York Avenue South, north of Parklawn
Avenue (AHR_15) N/A; to be studied.
R18 7.2.1 6124 Wilryan Avenue (NC_46 and NC_45) N/A; to be studied.
R19 7.2.1 Hazelton Road and Lynmar Lane (LE_19,
LE_24, and LE_21) N/A; to be studied.
R20 7.2.1 Dunberry Lane and Oaklawn Avenue
(LE_31 and LE_28) N/A; to be studied.
Appendix C Swimming Pool Pond (NC_3)/North Lake
Cornelia (NC_62) Upgrade pipe and outlet structure.
Appendix C Hibiscus Avenue (LE_53, LE_7, and LE_10) Construct positive overflow swale.
Appendix C 6312, 6316, 6321, 6329 Tingdale Ave
(NC_11)
No recommendation at this time. Further analysis
required.
Appendix C St. Johns/Ashcroft and West 64th Street
(NC_40 and NC_26)
Installation of additional pipe to drain TH 62
median ditch and prevent upstream flooding.
Appendix C Barrie Road and Heritage Drive (NC_86,
NC_97, and NC_99_
No recommendation at this time. Reevaluation of
TH 62 system will be required.
Appendix C York Avenue and West 64th Street
(NC_88)
Increase pump capacity. Adjust pump on/off
elevations.
_______________________________________________
In the ID column, D = detailed analysis conducted for flood-prone area (pink)
In the ID column, S = screening level analysis conducted for flood-prone area (yellow)
In the ID column, R = registered flood-prone area: identified as a flood-prone area but not studied further for this CWRMP (blue)
City of Edina 2018 Comprehensive Water Resource Management Plan
15-15
ID
2018 CWRMP
Section Project Name/Location Proposed Improvement
Appendix C TH 62 at France Avenue (NC_132) No recommendation at this time. Reevaluation of
TH 62 system will be required.
Appendix C Parnell Avenue and Valley View Road
(NC_135)
No recommendation at this time. Further analysis
required.
Nine Mile Creek—South
S10 8.3.1.1 West 70th Street and West Shore Drive
(NMS_38)
Increase pipe capacity under West 70th Street.
Regrade/lower the surface overflow along West
70th Street to the west. Add storage in Arnesan
Park (LE_54) and install connecting pipe.
S11 8.3.1.2 Centennial Lakes (CL_1) Flood proof individual low entries. A floodwall (~3
feet) around the lake at the southern end.
R21 8.2.1 City of Edina Building, Metro Boulevard
(NMS_51) N/A; to be studied.
R22 8.2.1
West 73rd Street, west of TH 100
(NMS_28, NMS_53, NMS_3, NMS_57,
NMS_30, NMS_62, NMS_27, NMS_56,
NMS_58, and NMS_65)
N/A; to be studied.
R23 8.2.1 Parklawn Avenue (NMS_77, NMS_70, and
NMS_93) N/A; to be studied.
R24 8.2.1 Oaklawn Avenue and Gilford Drive
(NMS_94 and LE_13) N/A; to be studied.
R25 8.2.1 France Avenue South and West 72nd
Street (CL_58, CL_56, and CL_57) N/A; to be studied.
Appendix C 7001 and 7025 France Avenue (CL_51) No recommendation at this time.
Nine Mile South Fork
S12 9.3.1.1 McCauley Trail West (AH_6)
Increase pump and pipe capacity to Aarowhead
Lake. Raise the control elevation upstream in AH_3
to store water upstream. Create additional
connected storage in AH_9 and/or AH_13.
S13 9.3.1.2 Sally Lane and Valley View Road
(NMSB_52, NMSB_69, and NMSB_77)
Increase the size of the culvert under Valley View
Road. Work with the NMCWD to store water
upstream west of TH 169.
_______________________________________________
In the ID column, D = detailed analysis conducted for flood-prone area (pink)
In the ID column, S = screening level analysis conducted for flood-prone area (yellow)
In the ID column, R = registered flood-prone area: identified as a flood-prone area but not studied further for this CWRMP (blue)
City of Edina 2018 Comprehensive Water Resource Management Plan
15-16
ID
2018 CWRMP
Section Project Name/Location Proposed Improvement
R26 9.2.1 Between Gleason Road and Mark Terrace
Circle (NMSB_27) N/A; to be studied.
R27 9.2.1
7122 Tupa Drive, 7117 Gleason Road, and
7116 Gleason Road (NMSB_13 and
NMSB_30)
N/A; to be studied.
Appendix C 6309 Post Lane (AH_31) Construction of two control structures to restrict
flow through the existing storm sewer system.
Appendix C Braemar Golf Course (NMSB_62) No recommendation at this time. Further analysis
required.
Appendix C 7009 and 7013 Sally Lane Backyard
Depression Area (NMSB_70) None. Analyzed in STS-406.
Southwest Ponds
S14 10.3.1.1 Gleason Road and Bonnie Brae Drive
(SWP_24)
Survey homes to confirm flooding problem.
Individual flood-proofing of potentially impacted
homes. Create additional storage in the city-owned
parcels south of Bonnie Brae Drive.
R28 10.2.1 Kemrich Drive and Shannon Drive
(SWP_53 and SWP_66) N/A; to be studied.
R29 10.2.1
Dewey Hill Road, west of Cahill Road
(SWP_21, SWP_48, SWP_5, SWP_34,
SWP_35, SWP_15, SWP_14, and SWP_4)
N/A; to be studied.
Appendix C 7411 Coventry Way (SWP_14) Installation of flap gate.
Appendix C 7317 Cahill Road (SWP_46) No recommendation at this time. Further analysis
required.
Appendix C 7709 Stonewood Court (NM494_4) Upgrade to larger pipes.
Northeast Minnehaha Creek
D3 12.3.1.2
Halifax Avenue South (MHN_84, MHN_3,
MHN_4, MHN_56, MHN_89, MHN_55,
MHN_61, MHN_62, MHN_87, MHN_90,
and MHN_2)2
Regrade Halifax to remove the depressions and
pooling areas; allow positive drainage north and
west to Minnehaha Creek. Add additional outlets
from backyard depressions (MHN_87, MHN_61,
and MHN_62), potentially south to 54th Street.
D4 12.3.1.3
Weber Park (MS_26, MS_25, MS_41,
MS_32, MS_44, MS_24, MS_15, MS_53,
MS_2, MS_38, MS_40, MS_54, MS_31,
MS_33, MS_39a, and MS_39b)2
Add capacity out of Weber Park to Lake Calhoun.
Increase capacity in the south storm sewer area to
Weber Park. Add substantial storage in Weber Park,
ballfields, and potentially in Weber Woods.
_______________________________________________
In the ID column, D = detailed analysis conducted for flood-prone area (pink)
In the ID column, S = screening level analysis conducted for flood-prone area (yellow)
In the ID column, R = registered flood-prone area: identified as a flood-prone area but not studied further for this CWRMP (blue)
City of Edina 2018 Comprehensive Water Resource Management Plan
15-17
ID
2018 CWRMP
Section Project Name/Location Proposed Improvement
S15 12.3.1.1 Indianola Avenue South of West 50th
Street (MHN_72)
Underground storage and infiltration (A soils) with
sufficient inlet capacity. Enlarge downstream pipes
to Minnehaha Creek, while not creating
downstream impacts.
S16 12.3.1.4 Edinbrook Lane and Westbrook Lane
(MHN_79)
Reroute flow from MHN_78. Improve, and possibly
lower, the surface overflow to the north. Purchase
the homes to create storage and infiltration (B
soils).
S17 12.3.1.5 North of Morningside Road between Lynn
Avenue and Crocker Avenue (MS_22)
Survey homes to confirm flooding problem. Add an
inlet in the backyard area and connect to existing
storm sewer under Crocker Avenue or Lynn
Avenue.
S18 12.3.1.6
Branson Street between West 44th Street
and Morningside Road (MS_3, MS_48, and
MS_7)
Add inlets and connecting pipes in the backyard
depression areas. Increase pipe sizes under
Morningside Road. Add storage in MS_7. Add
underground storage under Branson Street and
Oakdale Avenue.
R30 12.2.1
West 50th Street and Arden Avenue
(MHN_6, MHN_7, MHN_72, MHN_53, and
MHN_54)
N/A; to be studied.
R31 12.2.1 Country Club Road and Casco Avenue
(MHN_16) N/A; to be studied.
R32 12.2.1
Minnehaha Creek, southeast of Wooddale
Avenue and West 50th Street (MHC_3 and
MHN_27)
N/A; to be studied.
R33 12.2.1 Minnehaha Creek, southwest of TH 100
and West 44th Street (MHC_1) N/A; to be studied.
R34 12.2.1 Minnehaha Creek, southeast of TH 100
and West 44th Street (MHC_2) N/A; to be studied.
R35 12.2.1 Scott Terrace and West 42nd Street
(MS_52)
May be addressed with the Weber Park proposed
improvements.
R36 12.2.1 Townes Road and West 48th Street (White
Oaks) White Oaks Area, studied in 2013-2014, STS-406.
_______________________________________________
In the ID column, D = detailed analysis conducted for flood-prone area (pink)
In the ID column, S = screening level analysis conducted for flood-prone area (yellow)
In the ID column, R = registered flood-prone area: identified as a flood-prone area but not studied further for this CWRMP (blue)
City of Edina 2018 Comprehensive Water Resource Management Plan
15-18
ID
2018 CWRMP
Section Project Name/Location Proposed Improvement
R37 12.2.1 TH 100 near Harvey Lake (H100_20 and
H100_22) N/A; to be studied.
R38 12.2.1
Bridge Street and Moorland Avenue and
Edina Boulevard (MHN_25, MHN_52,
MHN_51, MHN_19, MHN_24, MHN_23,
and MHN_22)
N/A; to be studied.
Appendix C 4000 West 42nd Street and 4100, 4104,
and 4108 France Ave (MS_40)
Implement recommendations of the 2006 Weber
Park Pond Feasibility Study.
Appendix C 4308 France Ave (MS_17) Work with homeowners to evaluate installation of
gravity system to drain backyard depression area.
Appendix C Arden Avenue (MHN_14) No recommendations at this time.
Southeast Minnehaha Creek
D5 13.3.1.2
Concord and West 58th Street (MHS_59,
MHS_26, MHS_58, MHS_42, MHS_53, and
MHS_17)2
Add capacity east of Wooddale Avenue or reroute
some areas directly to the creek. Additional storage
in Pamela Park.
S19 13.3.1.1
Tower Street (MHS_75, MHS_86, and
MHS_76), between Fairfax Avenue and
Wooddale Avenue (MHS_16), and North
of 56th Street (MHS_83)
Add inlets in these areas and increase downstream
capacity to Minnehaha Creek. Add parallel pipe
network from West 56th Street and Wooddale
Avenue to West 56th Street and Kellogg Avenue.
Underground storage and infiltration under side
streets.
R39 13.2.1 Minnehaha Creek, north of Pamela Park
(MHC_4, MHS_8, and MHS_9) N/A; to be studied.
R40 13.2.1 Woodcrest Drive and Backyard Pond
(MHC_4, MHS_10, MHS_12, and MHS_41) N/A; to be studied.
R41 13.2.1 South end of Pamela Park, West 62nd
Street (LP_26, LP_17, and LP_22) N/A; to be studied.
R42 13.2.1 East side of Pamela Park, Halifax Avenue
South (LP_14, LP_10, LP_9, and LP_7) N/A; to be studied.
R43 13.2.1 West 61st Street, between Xerxes Avenue
South and York Avenue South (MPLS_130) N/A; to be studied.
Appendix C 6213 Ewing Ave (LP_15) Upgrade to larger pipes.
Appendix C 3600 West Fuller Street (MHS_4) Installation of a catch basin in backyard depression
and storm sewer along Beard Avenue.
_______________________________________________
In the ID column, D = detailed analysis conducted for flood-prone area (pink)
In the ID column, S = screening level analysis conducted for flood-prone area (yellow)
In the ID column, R = registered flood-prone area: identified as a flood-prone area but not studied further for this CWRMP (blue)
City of Edina 2018 Comprehensive Water Resource Management Plan
15-19
ID
2018 CWRMP
Section Project Name/Location Proposed Improvement
Appendix C 5605, 5609, 5613, 5617, 5621, 5625, and
5629 South Beard Avenue (MHS_79) Upgrade to larger pipes. Install catch basin in alley.
Appendix C 5837, 5833, 5829, and 5825 South Chowen
Ave (LP_24)
Installation of a catch basin in backyard depression
area.
Appendix C Chowen Avenue and West 60th Street
(LP_27)
Perform detailed survey/verification of storm sewer
to verify pipe sizes, inverts, and low point of entry.
Appendix C
5912, 5916, 5920, 5924, 5928 Ashcroft
Avenue and 5925 Concord Avenue
(MHS_51)
Pumped or gravity outlet of 3 cfs capacity.
Appendix C 5840 and 5836 Ashcroft Avenue (MHS_89) Work with homeowners to evaluate installation of
catch basin from backyard depression.
Appendix C
5609 and 5605 Dalrymple Road (MHS_24),
and 5610 and 5612 St. Andrews Avenue
(MHS_66)
Construct surface overflow swale (1) or upgrade to
larger pipes (2).
Appendix C 5701 Dale Avenue (ML_12) Upgrade to larger pipes.
Appendix C 5213 and 5217 Richwood Drive (ML_7) Perform detailed field survey of wetland storage.
Further analysis required.
Northwest Minnehaha Creek
S20 14.3.1.1 Blake Road South and Spruce Road
(HO_4)
Increase downstream pipe capacity: (1) increase
pipe connecting HO_8 and HO_19, or (2) add
additional outlet to the Interlachen Golf Course
from the wet pond (HO_8) or from the existing
storm sewer under Spruce Road. Add
depressions/storage in the golf course to offset
additional water.
R44 14.2.1 Annaway Drive and Interlachen Country
Club (EI_3, EI_25, EI_25a, and EI_34) N/A; to be studied.
R45 14.2.1 Annaway Drive, Merilane Avenue, and
Mait Lane (EI_1, EI_2, EI_4, and EI_5) N/A; to be studied.
Appendix C Interlachen Landlocked Area
Construct/raise embankment between landlocked
wetland and Meadowbrook Golf Course. Develop
management plan for pumped outlet.
City of Edina 2018 Comprehensive Water Resources Management Plan
15-20
15.2 Clean Water
The streams, ponds, lakes, and wetlands in the City of Edina are an important community asset. These
resources supply aesthetic and recreational benefits, in addition to providing wildlife habitat and refuge.
The City recognizes the need to protect and improve these resources and strives to manage the City’s
water resources so that the beneficial uses of its lakes, streams, ponds and wetlands remain available to
the community. Protection and improvement of these resources encompasses operating and maintaining
the City’s existing clean water infrastructure, implementing programs to educate and engage the
community, developing and implementing pollution reduction strategies, and completing capital
improvements.
15.2.1 Clean Water Infrastructure
Municipal stormwater systems provide multiple functions, including water quality protection. Ponds and
other water quality treatment facilities remove pollutants such as sediment and phosphorus from
stormwater prior to the stormwater being discharged to downstream water resources. Much of the city of
Edina was developed prior to significant focus on protecting the quality of surface waters. As a result,
stormwater from large portions of the city discharges directly to wetlands, lakes, or the creeks. In fact,
many of the natural wetlands within the city serve a stormwater management function, providing rate
control and pollutant removal benefits to waters downstream. The City’s stormwater system also includes
many constructed stormwater ponds and water quality treatment facilities that provide pollutant removal
to protect the downstream waterbodies. While the majority of the existing water quality treatment
facilities are stormwater ponds, the City also owns and operates numerous underground hydrodynamic
separators (also termed grit chambers), sump manholes, surface bioretention basins, and underground
storage and infiltration facilities.
The City is responsible for operation and maintenance of the public stormwater system, including water
quality treatment facilities. Stormwater facilities constructed on private property are generally the
responsibility of the private property owner, which includes operating and maintaining the facilities in
proper condition, consistent with the original performance design standards. The City of Edina periodically
inspects public water quality treatment facilities to ensure they are functioning properly and providing the
desired benefits, and will begin inspecting private facilities. Additional information regarding operation
and maintenance of public and private stormwater infrastructure is provided in Section 15.3.
15.2.2 Clean Water Programs
The City of Edina seeks to protect and improve its water resources through implementation of several
clean water programs, including promoting community engagement, pollution prevention through site
reviews and implementation of city ordinances, policies, and design standards during and after
construction, pollution source control, lake and pond management, and implementing stormwater best
management practices. These programs accomplish minimum regulatory standards and, in many areas,
move beyond the minimum standard. Details regarding the measurable goals, implementation schedule,
and responsible parties for the minimum standards as required by the MS4 permit can be found in the
City of Edina’s SWPPP.
City of Edina 2018 Comprehensive Water Resources Management Plan
15-21
15.2.2.1 Community Engagement
Community engagement is a key component in a successful stormwater management program. The City
recognizes that an informed residency is necessary to make progress toward meeting water resources
goals. Programmatic activities are designed to build a culture of water resources stewardship necessary to
influence change on the landscape. Residents value water resources and City staff seek to involve them in
addressing issues through informing, educating, and promoting participation.
The City has developed and is implementing a public education and engagement plan to distribute
information and conduct outreach activities regarding the impacts of stormwater discharges on water
bodies. The City’s education and engagement plan identifies the audience involved, educational goals,
activities used to reach goals, activity implementation plans, and available performance measures that can
be used to determine success in reaching educational goals.
The community engagement plan also includes working collaboratively with the local watershed districts
in distributing educational materials and promoting/supporting outreach programs.
Annually, the City hosts an opportunity for the public to comment on the SWPPP and water resource
programs, although comments may be submitted at any time of the year. This has been done as a
standalone meeting or in addition to another engagement event. Notice of the meeting date, time,
location, and materials is distributed through various communication channels including the local
newspaper. Oral and written input from the public regarding water resources programs will be sincerely
considered and adjustments will be made where appropriate.
The City also hosts a booth at the annual Open Streets on 50th event with the help of Master Water
Steward volunteers to engage the public in water resources topics.
A presentation of issues, future activities, and completed projects is also brought to the Edina Energy and
Environment Commission with the Annual Water Resources Coordinator’s report.
15.2.2.2 Pollution Prevention
Site Plan Review and Design Standards
The City of Edina has adopted the control policies discussed in the Runoff Management and Flood
Protection—Section 3.1; Water Quality—Section 3.3; and the Erosion and Sediment Control—Section 3.4
sections to promote pollutant prevention and/or reduction from new development and redevelopment
areas. These policies are enforced through the site plan review process and through permits issued by the
City or respective watershed district.
The City of Edina also addresses runoff problems with sound planning procedures. Land use and zoning
ordinances promote improved water quality by guiding the growth and redevelopment of the community
away from sensitive areas and by restricting certain types of growth to areas that can support it without
compromising water quality.
City of Edina 2018 Comprehensive Water Resources Management Plan
15-22
Pollution Prevention Practices
Pollution prevention and good housekeeping practices can ensure a reduction in the amount and type of
pollution that is discharged to downstream water resources from streets, parking lots, open spaces, and
storage and vehicle maintenance areas. Many pollution prevention practices are incorporated into the
City’s infrastructure operation and maintenance program (see Section 15.3). Other practices that the City
implements are more programmatic in nature, including the following:
1. Employee training on incorporation of pollution prevention techniques into municipal operations
such as park and open space maintenance, fleet and building maintenance, road salt application,
new construction and land disturbances, and stormwater system maintenance.
2. Periodically evaluating city landscaping and lawn-care practices, which may include the use of
fertilizers, pesticides, herbicides, lawn mowing, grass clipping collection, mulching and
composting, and developing or modifying practices to reduce stormwater pollution.
3. Periodically reviewing practices and policies related to road salt applications, including
consideration of alternative products, calibration of equipment, inspection of vehicles and staff
training to reduce pollutants from road deicing activities.
4. Evaluating, annually inspecting, and modifying (if necessary) current management practices for all
exposed stockpiles, storage, and materials located within City-owned property.
5. Continuing the City’s street sweeping program, including evaluation and identification of
potential program improvements, and implementation of changes, as necessary, to reduce
stormwater pollutants.
15.2.2.3 Pollution Source Controls
Illicit Discharge Detection and Elimination
Identification of stormwater pollutant sources includes identification of illicit pollutant discharges and
nonpoint sources throughout the city. An illicit pollutant discharge is defined as a non-permitted point
source of pollutants that is discharged to the storm sewer system at a specific location. Illicit discharges
can enter a storm sewer system directly (through wastewater piping mistakenly or deliberately connected
to the storm drains) or indirectly (through infiltration from cracked/leaking sanitary systems, spills
collected by drain outlets, or other contaminants such as paint or oil dumped directly into a storm drain).
To prevent the harmful effects of illicit discharges, a number of management practices have been
developed to implement and enforce a program to detect and eliminate illicit discharges into the City’s
stormwater system. The City’s illicit discharge detection and elimination program includes the following
components:
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1. An annually-updated storm sewer system map showing the location of all City-owned storm
sewer pipes (24-inch diameter or greater), outfalls, locations where discharge leaves the City, and
water bodies.
2. Periodic review of existing City ordinances relating to illicit discharges and develop/adopt an illicit
discharge ordinance as necessary.
3. Expansion of the City’s program to detect and reduce all forms of non-stormwater discharges and
continuation of inspection for illicit discharge during the outfall and pond inspections.
4. Distribution of educational materials to residents and providing illicit discharge educational
information or annual training for City staff.
Construction Site Stormwater Runoff Control
Runoff management from construction sites minimizes the amount of sediment and other pollutants
entering the water bodies within the city. The City implements the erosion control policies identified in
Section 3.4, including the following activities:
1. Permits for land disturbing activities consider erosion and sediment control.
2. Construction site operators must provide a phone number, website, and point of contact for the
public to report stormwater pollution issues.
3. Construction site operators must conform to MPCA, watershed district, and City ordinances
pertaining to erosion and sediment controls and waste controls.
The City enforces erosion and sediment control and stormwater management on lots >1 acre in size, and
has limited stormwater, erosion and sediment control standards for sites under 1 acre associated with
grading or demolition permits. The City also requires that project applicants or owners contact the
NMCWD or MCWD to determine if watershed district permits are required.
15.2.2.4 Lake and Pond Management
The City has established policies to guide its management of lakes and other water resources within the
city (Section 3.3 and Section 3.5) and works closely with the watershed districts to protect and improve
the quality of these resources. This generally includes participating in water quality studies and planning
activities within the watershed districts and other agencies and implementing stormwater management
practices and programs to reduce pollutant contributions. In 2014, the City established a lake and pond
management policy to manage residents’ requests for lake management activities, which tend to focus on
aquatic vegetation management. The policy establishes a system to prioritize the waterbodies, defines
management service levels, and lays out a process to involve shoreline owners in waterbody management.
The City encourages residents to form Lake Associations and lake groups to advocate for management of
waterbodies. An association is a voluntary organization made up of people who own land on or near a
body of water. Land owners often form an association when they are concerned about issues regarding
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the quality or use of the body of water and want to deal with them in an organized manner. Lake groups
are less formal and may be more appropriate for some smaller waterbodies. In some cases, a formal or
informal group is required for a waterbody to be eligible for services under the lake and pond
management policy, which is mostly centered around aquatic vegetation management.
Forming an association has several benefits, including:
• At a minimum of once per year, a meeting is held to discuss topics related to the waterbody. This
approach encourages representation of all stakeholders and decisions that are based on the
majority. Grant opportunities and petitions have more merit when brought forth by a coordinated
group that represents the majority.
• Recommendations for treatment come from local residents instead of city staff. An association
meets with members to gather feedback and recommend annual treatment. The association
Board of Directors would then request that the city coordinate treatment and special assess costs
back to the special assessment district. Alternatively, the group could operate independently of
the city to coordinate and pay for services on their own. Local ordinances and DNR permit
requirements would still apply.
• Information can be shared between the city and the association more effectively.
• Organizing around the shared resource can build a culture of water stewardship. Associations may
opt to organize a block party or lead an education campaign.
The organization can potentially organize and fund additional elective activities. Examples might include a
social event or special study.
Aquatic Vegetation
Aquatic vegetation has an important place in the ecosystem of lakes and ponds. It provides food and
shelter to fish and wildlife, and uses phosphorus for its growth, isolating it from the water column and
limiting algae growth. While aquatic vegetation is beneficial to aquatic life and water quality, it can also be
a detriment to recreation and sometimes aesthetics, especially when excess nutrients cause overgrowth.
Aquatic Vegetation Treatment Request Process
The City manages requests for aquatic vegetation treatment using the following system established to
prioritize the waterbodies, define management service levels, and lay out a process to involve shoreline
owners in waterbody management:
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Step 1: Use the following classification to determine the points awarded based on waterbody size.
Size Points Awarded
• Large (10+ acres) 4
• Medium (5-9.9 acres) 3
• Small (2.5-4.9 acres) 2
• Tiny (1-2.4 acres) 1
• <1 acre Not eligible for
management by City
Step 2: Use the following classification to determine the points awarded based on water quality of the
water body.
Water Quality Points Awarded
• 303(d) Impaired Waters List 4
• Drains directly to impaired water or a
waterbody which meets water quality goals and
is in protection mode
3
• Data shows that waterbody does not meet
applicable state or watershed water quality
goals
2
• No data 0
Step 3: Sum points awarded from Steps 1 and 2.
Step 4: Use the following classification to determine initial service level based on points awarded.
Service Level Points Required
• High 7-8
• Medium 5-6
• Low 3-4
• None 0-2
Step 5: If any of the following apply, the service level can be raised*:
• forming an informal lake group or formalized lake association with 50% plus one of the
shoreline properties represented , or
• providing significant public access and use
*Water bodies may only move up one service level, even if they have both an association and public access.
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The system described above is used to define the City’s management service level for a given lake. The
service level for many waterbodies have already been determined and can be accessed online via the
City’s Water Resources Library and is also provided in Appendix E. Contact the City for the most up-to-
date list. Table 15.3 identifies the level of potential lake management activity, depending on the
established service levels.
Table 15.3 Level of Potential Lake Management Activity by Service Level
City-Funded Activities Additional Elective Services*
Service
Level
Whole lake
algae
treatment
(as
permitted/
required)
Invasive
aquatic
plant
treatment**
Lake
study (up
to 2 lakes
per year)
City staff
support
(see
Table 15.4
below)
DNR
Permits
and
Facilitation
Aquatic
vegetation
management
Alternative
methods
(see
Table 15.4
below)
DNR
permits
and
facilitation
High Yes Yes Yes Yes Yes Yes Yes Yes
Medium Yes Yes Yes Yes Yes No No No
Low Yes Yes No Yes Yes No No No
None At City’s discretion, lowest priority No No No
*Cost of elective services are special assessed to property tax bill. This option requires a formalized lake association,
registered as a nonprofit organization in the state of Minnesota, as described in the policy.
**Invasive aquatic plant treatment will be pursued to the extent that it limits the spread, fits within budget, cost/benefit
analysis supports it, and has a clean water benefit. Invasive aquatic plant treatment will not be completed solely to
accomplish a recreation or aesthetic goal.
Table 15.4 City staff support activities and alternative methods related to Table 15.3
City staff support activities (related to Table 15.3 above): Alternative methods (related to Table 15.3 above)
Association/group formation All alternative methods (such as barley straw, floating
treatment wetlands, etc.) are elective services.
Education There may be some cost share available from the city.
Facilitate data collection
Facilitate group projects
Technical resource
Duckweed Management
The City will not participate in destruction or removal of duckweed for recreational or aesthetic purposes.
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Cattail Management
The City will only manage cattails such that they don’t obstruct water flow. The City will not participate in
destruction or removal of cattails for recreational or aesthetic purposes.
Requesting a Lake Study
Requests for lake studies must be submitted in writing to the City’s Water Resources Coordinator. The
request must meet the following criteria:
• Come from a formal or informal group, representing the majority of residents. Where there is a
formal group, the board may submit a request on behalf of the group. Where there is an informal
group, signatures from representatives of 50% plus one properties surrounding the resource must
provide a signature in support of the request.
• Identify what the group hopes to accomplish with a lake study, specifically indicating what
questions they hope to have answered.
• Waterbodies will be eligible for lake studies once every 5-year period.
• Requests for lake studies will expire after 9 months.
• Requests will be received on a first come, first served basis with new applicants receiving
preference.
• Lake study scope will be limited by annual budget.
• Up to two lake studies will be funded per year, contingent upon annual budget.
15.2.3 Clean Water Strategy
As part of this 10-year plan, the City of Edina will develop a clean water implementation strategy that
outlines a plan for working toward meeting its clean water goals. The strategy will address the City’s
approach to meeting the pollutant reduction targets identified through the TMDL and WRAPS process.
The strategy will also determine pollutant load reduction targets for nondegradation of water bodies that
are not impaired and identify an approach for achieving these stormwater management targets. The clean
water implementation strategy will be a 5-year strategy that identifies regular “good housekeeping”
stormwater practices and clean water capital improvement projects (CIP) to achieve the goals, including
quantification of pollutant removals and preparation of planning-level cost estimates. This information will
be used for planning, as well as assessment of cost-benefit for project prioritization. The implementation
strategy will be developed in coordination with street reconstruction projects, redevelopment, and other
opportunities. Annual or biennial reporting will be included in the strategy to quantify movement toward
the City’s goals and track activities for the City’s annual SWPPP and MS4 reporting. When completed, the
Clean Water Strategy will be included as an amendment to this CWRMP.
At the time of this plan’s writing, the focus area for the Clean Water Strategy is Lake Cornelia in the Nine
Mile Creek Watershed District.
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15.2.3.1 Implementation Approach
The Clean Water Strategy will define clean water goals, the cost and pace of achievement, and plan
implementation opportunities including the following categories:
• Redevelopment- implementation of stormwater management rules as part of redevelopment
• Redevelopment- expansion of site or regional stormwater management beyond compliance with
stormwater management rules
• Retrofit- implementation of stormwater management as part of City street reconstruction projects
on public land
• Retrofit- targeted implementation of stormwater management BMPs for improving water quality
of an impaired water body. These BMPs may require land acquisition.
• Retrofit- implementation of stormwater management BMPs in partnership with other public- or
non-profit land owners
• Re-design/re-purpose- implementation of stormwater management BMPs as part of city
improvement projects (e.g., park improvements, city facility improvements)
Each of the clean water improvement opportunity categories identified above have opportunities for
partnership with other entities, such as private land owners, watershed districts, non-profit organizations,
or other local governmental entities.
15.2.3.2 Opportunity Identification and Prioritization
The City will pursue clean water improvements that maximize cost effectiveness and capitalize on
coinciding opportunities, such as planned street reconstruction, redevelopment efforts, availability of land,
or other planned infrastructure improvement projects. Consideration will also be given to achieving
additional “co-benefits”, such as flood risk reduction, recharge of shallow groundwater aquifers, wildlife
habitat improvement, and groundwater conservation.
BMP Cost Effectiveness
Stormwater best management practices (BMPs) have a wide range of cost effectiveness, depending on
factors such as the suitability of soils for infiltration of stormwater and the availability and cost of land.
Soil Suitability for Infiltration
Infiltration-based stormwater BMPS are often most effective in reducing stormwater volume and pollutant
loading to downstream water bodies. Infiltration describes a process where stormwater runoff seeps into
the soil. Because the water stays near to where it lands, the volume of runoff (and associated pollutants)
delivered downstream is reduced. Infiltration also recharges groundwater and treats stormwater through
natural filtration. This is particularly valuable when lakes, wetlands, or trout resources are downstream.
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Infiltration-based stormwater BMPs are not very practical in soils with low infiltration capacity, such as
tight silts or clays, where the infiltration rate is severely limited. Infiltration is also not recommended in
locations where soils are contaminated, within sensitive drinking water recharge areas, where
groundwater is shallow (less than three feet below the surface) or where karst features or bedrock are
prominent.
As part of its Clean Water Strategy, the City will conduct a desktop analysis to identify and prioritize
locations where implementation of infiltration-based stormwater BMPs is feasible. Favorable locations
would include areas where soil conditions are conducive and negative impacts are unlikely. The analysis
may also include identification of areas where the potential for flood-risk can be reduced. These locations
would then be prioritized based on an analysis of total construction and maintenance costs, availability of
land, and infiltration benefits, including consideration of downstream water body. Prioritized locations
could become part of the City’s future BMP implementation program.
Land Availability
Given that the City of Edina is essentially fully developed, the availability of land for implementation of
stormwater management practices is limited. Installing stormwater BMPs in city-owned right-of-way is
often challenging due to limited space and conflicts with existing utilities and infrastructure. Beyond the
right-of-way, the primary city-owned land consists of parkland. While implementation of stormwater
BMPs in the City’s parks can be cost effective, the parkland within the City is in high demand, with an ever
increasing demand for programmed athletic fields, which severely limits the availability of land for
stormwater management practices. There may be opportunities to retrofit stormwater BMPs on existing
privately-owned sites; however, parking requirements or demand can severely restrict the available land
for stormwater BMPs. As redevelopment occurs throughout the city, there is significant opportunity to
implement site-based or regional stormwater management practices. However, development densities
appear to be generally increasing, and parking requirements and other site constraints are limiting the
feasibility of implementing above-ground stormwater management practices.
Given the limited availability of land for installing conventional, above-ground stormwater BMPs, many
private landowners and water managers are pursuing underground BMPs that can be installed within
right-of-way and/or parking areas. While these BMPs are desirable to many because they allow for co-
exist with other site uses, the cost for underground stormwater practices is higher than above ground.
There is also concern about the maintenance costs and feasibility of the underground systems.
Co-benefits of BMPs
The City’s Clean Water Strategy will also consider achievement of additional “co-benefits”, such as flood
risk reduction, recharge of shallow groundwater aquifers, wildlife habitat improvement, and groundwater
conservation.
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Reuse
Studies can evaluate effective ways of reusing rainwater, stormwater, greywater, wastewater, and industrial
water. Reuse is important because it helps the City achieve its stormwater management goals, conserve
water, meet permit requirements, develop sustainable water supplies, reduce costs, and improves the
City’s triple bottom line.
Identifying water reuse opportunities often begins by asking the following questions:
• Who uses water?
• Where is there a lot of water?
• Where is there a high water demand?
• What is the quality of available water?
• What level of water quality is needed to meet the end user’s needs?
• Is reuse technically feasible? Qualitatively feasible?
The City will conduct a desktop analysis to identify and prioritize locations where stormwater reuse
systems could be implemented Table 15.1. A geographic information system (GIS) screening-level
analysis could be performed to identify potential reuse opportunities within the City—matching water
sources to water needs. For example, both water sources and water users can be identified by mapping
publicly available data (e.g., NPDES discharge permit data and appropriations permit data,
respectively). GIS can also help identify potential sources of water in close proximity to potential users
(including parks and golf courses that need water for irrigation). Other potentially useful data includes
soils data (permeability, salinity), topography, storm sewer and sanitary sewer data, utilities data
(gas/communication/power utilities), groundwater data, water supply well data, and water sales data.
15.3 Stormwater Infrastructure
Infrastructure for flooding and drainage as well as for clean water are discussed in this section together
because of the overlapping services that some components of the system provide. Components of these
systems may be publicly or privately owned.
Runoff management and flood protection infrastructure generally includes pipes, inlets, ponds, lift
stations, natural water bodies and outlet controls, temporary inundation areas, and local and regional
flood storage areas, among others. Runoff management and flood protection infrastructure also includes
sump drains (providing a dual purpose with the sanitary sewer infiltration and inflow program), and curb
and gutter (providing dual purpose with erosion sediment control and road maintenance),, among others.
Clean water infrastructure generally includes underground hydrodynamic separators (also termed grit
chambers), sump manholes, ponds, underground storage and infiltration facilities, and bioretention
basins, among others.
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15.3.1 Operation and Maintenance of Stormwater Systems
The stormwater system includes not only pipes and constructed ponds, but also lakes, wetlands, ditches,
swales, and other drainage ways. In addition to more typical maintenance measures, maintenance of the
stormwater system may also mean maintaining or restoring the ecological characteristics of the natural
portions of the stormwater system. The City of Edina recognizes that maintenance of all of the City’s
stormwater facilities is an important part of stormwater management. Proper maintenance will ensure that
the stormwater system provides the necessary flood control and water quality treatment.
15.3.1.1 Private Stormwater Facilities
Owners of private stormwater facilities are responsible for maintaining the facilities in proper condition,
consistent with the original performance design standards. Responsibilities include removal and proper
disposal of all settled materials from ponds, sumps, grit chambers, and other devices, including settled
solids. There is a need for a program to ensure private stormwater facilities are properly maintained so
that they continue to provide the intended level of flooding, drainage, and clean water services. This
policy gap is described further in Section 15.4.7.
15.3.1.2 Publicly Owned Stormwater Facilities
The City of Edina is responsible for performing the maintenance of the stormwater facilities under City
ownership. Average facility condition and performance is currently unknown, and there is an unknown
liability of deferred maintenance.
The City will also notify the owners of other publicly owned stormwater facilities if scheduled maintenance
is needed according to periodic site inspections or maintenance plans on file. The Minnesota Department
of Transportation is responsible for maintaining road ditches, storm sewer, and culverts along
U.S. Highway 169, State Highway 100, and State Highway 62. Hennepin County is responsible for
maintaining right-of-way, storm sewer, and culverts along CR 17 (France Avenue), CR 31 (York Avenue),
CR 158 (Vernon Avenue), and CR 20 (Interlachen Boulevard).
The City will develop an inventory and maintain a database for all private and public stormwater facilities
within the City of Edina to assist in determining maintenance requirements. The City will regularly inspect
and maintain key components of the public system, including storm sewer and culvert inlets, overflow
drainage swales, stormwater ponding and water quality treatment basins, and riprap-protected banks,
storm sewer, and culvert outlets.
15.3.1.3 Maintenance of Storm Sewer and Culvert Inlets
For safety reasons and to prevent pipe plugging, trash racks are typically installed on storm sewer and
culvert inlets. These trash racks prevent people from entering the pipes and keep large debris from
becoming lodged in the pipes. If not inspected and maintained, the trash racks will become plugged with
debris such as branches, leaves, and other materials carried by storm flows. Even if partially plugged,
additional flooding can occur. The City recognizes the importance of, and performs, periodic removal of
collected debris from system trash racks, catchbasins, and inlets.
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15.3.1.4 Maintenance of Ponding Facilities
Stormwater ponding and water quality treatment facilities perform a desirable function by settling
sediment out of the stormwater. However, if accumulated sediments are not periodically removed, such
basins can experience a significant loss in necessary stormwater detention capacity and sediment storage
volume. Also, if left unattended, these facilities can become overgrown with unwanted vegetation that
could reduce their effectiveness and hinder access for periodic maintenance.
The City of Edina periodically inspects stormwater storage basins and water quality treatment facilities to
look for excessive sediment build-up, collected debris, and unwanted vegetation. If problems are noted,
maintenance is then warranted. For sedimentation basins, if 25% of the sediment storage volume is filled
with sediment, the basin should be dredged to provide its originally designed sediment storage volume.
Overflow swales can turn into steep eroding channels if an ongoing erosion problem is not stabilized and
the area restored. Typical stabilization materials could include permanent geotextile erosion-control
material or riprap accompanied by a properly designed filter material. Erosion problems are identified and
addressed by the City’s maintenance program.
In general, vegetation in existing ponding facilities should be allowed to grow naturally on the side slopes
of the basin and should not be mowed. This practice will allow ponding facilities to act like natural
wetland areas by providing nearby upland wildlife habitat.
15.3.1.5 Riprap and Filter Areas
Riprap and filter areas along banks, in overflow swales, or around storm sewer or culvert outlets, need
periodic maintenance. Riprap is placed in those locations to prevent damage that would result from highly
erosive flow velocities. If not periodically maintained, significant erosion will occur resulting in pipe
damage, downstream sediment problems, and potential safety issues. The City will annually inspect riprap
areas and perform the necessary maintenance.
15.3.1.6 Adequacy of the Maintenance Program
The City of Edina is responsible for maintaining its stormwater system including storm sewer pipes, ponds,
pond inlets and outlets, and channels. The City will continue and expand upon its operation and
maintenance activities to ensure its systems function as designed. The City’s operation and maintenance
program is closely tied with the City’s implementation of its NPDES Phase II MS4 Permit. The City’s
operation and maintenance program is incorporated in the implementation program.
15.4 Management Approach
The City will actively apply the water resources management policies and implement the programs and
projects identified in this Comprehensive Water Resources Management Plan by:
• Applying the policies and Plan to all clean water and flood improvements, including those
involving operations, maintenance, improvements, and qualifying private
development/redevelopment.
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• Leveraging all sources of clean water funding and actively pursuing grants, cost-sharing
opportunities, project partnerships and other new or special funding sources as applicable.
• Drawing on technical support and feedback from partner agencies, organizations, and groups.
• Embracing a systems approach to solve water resources problems; considering multiple uses,
sources, and waste streams of water.
• Advocating for water resources strategies consistent with this plan when a local land use decision
is under the jurisdiction of another agency.
• Adapting to new knowledge and challenges, using the best science to guide decision-making.
• Coordinating efforts with supporting plans and programs;
o Current Edina Comprehensive Plan
o Living Streets Plan
o Source Water Protection Plan
o Wellhead Protection Plan
o Stormwater Pollution Prevention Plan and Municipal Separate Storm Sewer System (MS4)
permit
o Nine Mile Creek Watershed District Water Management Plan
o Minnehaha Creek Watershed District Water Management Plan
o Minnehaha Creek Watershed District’s ‘Guide: Community Adaptation Planning for Changing
Landscapes and Climate’
o Hennepin County’s Natural Resources Strategic Plan
o Residential and commercial permitting
Beyond prioritizing and allocating resources to accomplish the minimum standard as required by the
City’s MS4 permit and SWPPP, this plan aims to prioritize projects and budgets to meet defined levels of
service, where achievable. The Clean Water Strategy and Flood Risk Reduction Strategy identified in this
plan will set out specific goals, priorities, and associated costs to better describe the investment needed
for the City to achieve its defined level of service.
The rate of progress in meeting the desired level of service will be determined by resources, funding,
opportunities, and policy alignment.
15.4.1 Coordination with Watershed Districts
15.4.1.1 Regulation
The City of Edina manages stormwater to protect life, property, waterbodies within the city, and receiving
waters outside the city. However, the City relies heavily on the NMCWD and MCWD for implementation of
water resource protection rules and requirements. The City defers LGU authority to the NMCWD and
MCWD for floodplain management and drainage alterations, wetlands management, stormwater
management, erosion and sediment control, waterbody crossings and structures, shoreline and
streambank improvements, and sediment removal.
The City of Edina also defers LGU authority for the WCA to the NMCWD and MCWD. This includes
requiring and verifying that all projects impacting wetlands meet the requirements of the Minnesota WCA.
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The Board of Water and Soil Resources serves as both a state administrator of the programs associated
with the WCA, as well as providing technical assistance to LGUs administering the WCA.
15.4.1.2 Data and Information
The MCWD and NMCWD collect and maintain numerous regional data collections and models that are
made available for use by the City of Edina. Below is a list of data and models available from one or both
of the watershed districts and a brief description of how the City has or will utilize these resources.
Hydrology and hydraulics (H&H) model – provides information on regional flood elevations and
hydraulics. The City has used the NMCWD Atlas 14 H&H model to evaluate impacts from proposed
drainage modifications and as a base for the 2017 Atlas 14 model updates completed to support this
CWRMP. The City used the MCWD H&H model for estimating Atlas 14 tailwater conditions in Minnehaha
Creek for the City’s 2017 Atlas 14 model updates conducted to support this CWRMP (see Appendix B).
Atlas 14 Flood Elevations– provide information on base flood elevations for development and
redevelopment. The City relies on the NMCWD and MCWD to provide 1-percent-annual-chance flood
elevations for Regional Flood Areas throughout the city. While the MCWD has not yet published Atlas 14
flood elevations for Minnehaha Creek, the City of Edina looks forward to utilizing these values when
available to consistently provide flood protection based on Atlas 14 precipitation frequency estimates
citywide.
MCWD Functional Assessment of Wetlands (FAW) – provides data on wetland functions and
values, establishes management classifications based on quality and sensitivity, and identifies restoration
opportunities for wetlands within the Minnehaha Creek watershed (Hennepin Conservation District, 2003).
The City incorporated the results of the FAW into its 2011 and 2018 CWRMP (see Section 16.2).
Stream Assessments – provide data on biological and physical condition of streams. The NMCWD
collects benthic macroinvertebrate and fish samples annually from the North Fork of Nine Mile Creek near
Metro Boulevard in Edina and conducts periodic physical condition assessments. This information has
been used to identify changes in stream water quality that may be caused by nonpoint source pollution
and provide a more complete understanding of overall stream health. Specifically, the data was used to
complete the Nine Mile Creek biological stressor identification study (MPCA, 2010) and design the Edina
Streambank Restoration project being constructed by NMCWD in 2017-2018. The MCWD has conducted
limited periodic biological monitoring of Minnehaha Creek (e.g., Zebra Mussel monitoring, fishery survey)
and project-specific physical condition assessments within Edina.
Hydrologic and Water Quality Data Reports – provide data on water quality, water quantity, and
ecological integrity conditions and trends for District resources. The NMCWD and MCWD collect and
analyze hydrologic (stream flows, lake levels) and water quality data at numerous locations within Edina,
including Minnehaha Creek (downstream of the Browndale Dam), North Fork of Nine Mile Creek (at Metro
Boulevard), and numerous lakes. This information is used by the City to track water quality conditions and
trends and identify the need for additional lake and watershed management.
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Educational Resources – provide education and outreach information regarding water resources best
management practices. The City has utilized the information and trainings offered by the MCWD and
NMCWD to support and bolster their education program.
15.4.1.3 Land Use Planning Opportunities
The MCWD Watershed Management Plan (2018) and NMCWD Water Management Plan (2017) both
highlight the desire to more closely integrate land use planning and water resource management to
capitalize on opportunities to improve water resources as development and redevelopment occurs. Given
that land use planning lies primarily with the cities, achievement of this goal will require close
coordination and partnership between the watershed districts (WDs) and cities.
Coordination Plan
To achieve the level of coordination and communication required to successfully capitalize on
opportunities to improve water resources as part of land use planning, the city will strive to conduct the
following activities:
• Participate in an annual meeting to review water resource plan implementation, to be coordinated
by the WDs. Parties will discuss how the WDs can receive notice of and consult on land use,
infrastructure, park and recreation, and capital improvement planning efforts.
• Transmit the annual NPDES MS4 report to WDs (mutual transmittal, if applicable)
• Notify the WDs of the following:
• Updates to road and infrastructure implementation programs. The City annually
produces a map of anticipated road reconstruction and road maintenance projects
for the next five years.
• Updates to park and recreation plans.
• Institution and completion of small area plans and other focused development or
redevelopment actions.
• Significant alterations within the City MS4 system (to maintain currency of the WD
watershed-wide hydrology and hydraulics model).
• Updates to the Capital Improvement Plan.
• Partnership or coordination as to public communications and education.
The WDs are asked to complete the following activities:
• District notice to the City regarding watershed management plan amendments and annual capital
improvement program updates.
To capture CIP and budget planning, the annual meeting should occur early in the second quarter. The
annual meeting will involve the City’s Community Development Director, Economic Development
Manager, Engineering Director, Engineering Services Manager, and Water Resources Coordinator. The City
welcomes and will accommodate requests from the WDs for additional meetings and communications
that spur from the annual meeting. For elements the City and WDs identify for coordination, specific
City of Edina
2018 Comprehensive Water Resources Management Plan
15-36
communication plans and schedules will be made. The Water Resources Coordinator will facilitate
communication among appropriate parties based on the scope of the item.
Conversations around water resources planning occur continuously throughout the year and are guided
by this plan. It is common for various stakeholders across the community (public agencies, non-profit
organizations, citizen groups, city departments, and private entities) to be involved in work that has
prominent or nuanced water resources implications. Some of the challenges of coordinating water
resources planning include the number of stakeholders involved, balancing funding priorities, community
attitudes, and the fact that plans and projects are often owned by others (and may have different
schedules, values, and service targets). Due to the dynamic nature of various concurrent activities and
planning efforts, maps of anticipated road reconstruction, potential park improvements, capital
infrastructure investment/reinvestment, priority water resources issues, and private development are not
provided here, but will be prepared ahead of each annual meeting. Spatial analysis tools allow for these
pieces of information to be integrated annually, efficiently incorporating the best available information.
The City and WDs have a history of partnership. The past successes have largely been the result of strong
working relationships that promote regular conversations. The City is eager to continue and expand
cooperative work in the following areas:
• CIP and budget planning: The City’s process for this is described in more detail in section 15.4.3.
Internal review begins in second quarter, drafts are available for comment in third quarter, and
City Council takes action in December of each year.
• Private development and redevelopment: It’s common for large projects to go through a sketch
plan review with City Council. The City will share known upcoming projects at the annual meeting.
As WD staff develop relationships with the community and economic development staff at the
City, they can regularly and informally check in with the City to stay abreast of private
development and redevelopment activity. The City will facilitate a coordination meeting with
private developers and the WDs at the request of the WDs. For projects that do not go through a
sketch plan review, the City will inform permit applicants of the potential need for a WD permit
and, when one is required, will not issue a City permit until the WD permit application has been
made.
• Public development and redevelopment: Described in more detail in section 15.4.1.4. Because of
our strong working relationship with the WDs, the City is continually seeking opportunities for
coordination. This occurs through informal conversations as opportunities arise. Any future efforts
including small area plans or other planning activity will be shared at the annual meeting.
• Operation and maintenance: The City will inform the WDs of illicit discharges in a timely manner
and share a summary of the illicit discharge detection and elimination program at each annual
meeting. Additionally, the City will share its MS4 inspection results at each annual meeting.
• Regulatory enforcement: As described in 15.4.1.1.
• Education and engagement: As described in 15.4.1.2., the City will share its education and
engagement calendar at each annual meeting. The City asks the WDs to continue to cross-
promote and partner on events.
City of Edina
2018 Comprehensive Water Resources Management Plan
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In 2014, the City and Minnehaha Creek Watershed District initiated a Memorandum of Understanding
(MOU) to describe the common goal of clean water among the agencies and outline spheres of
collaboration in a number of areas including public education and outreach, development oversight,
integrated capital improvements, and planning coordination. A copy of the MOU is available in the City’s
Water Resources Library.
15.4.1.4 Implementation Partnership Opportunities
The City will work closely with the NMCWD and MCWD to identify and implement water resource
protection or improvement partnership projects. While some opportunities may be associated with
development and redevelopment, other opportunities will be focused on land owned by the City.
Figure 15.1 shows the city-owned parcels throughout the city. Upcoming opportunities for water
resource management or improvement partnerships associated with City-owned park and property
redevelopment include:
Minnehaha Creek Watershed
• Arden Park: Clean water and drainage issues, civic engagement
• Weber Park: Flooding issues (and clean water co-benefits opportunity), civic engagement
• Grandview Green: Stormwater management, regional planning, permitting, civic engagement
Nine Mile Creek Watershed
• Pentagon Park: Flooding issues (and clean water co-benefits opportunity), rule administration
planning, civic engagement
• Lake Cornelia: Clean water and flooding issues, civic engagement
• Lake Edina: Clean water and flooding issues, civic engagement
This CWRMP lays out a framework for working toward incremental improvement in water resource issues
through the Flood Risk Reduction Strategy and Clean Water Strategy. At the time of this plan’s writing, the
focus area for the Flood Risk Reduction Strategy is the Morningside neighborhood in the Minnehaha
Creek Watershed District and the focus area for the Clean Water Strategy is Lake Cornelia in the Nine Mile
Creek Watershed District. The City invites the watershed districts to be involved in the development of
these strategies for each of these focus areas.
15.4.2 Development Review Process and Land Use Planning
The City utilizes its Development Review process to address stormwater management and ensure water
resource protection within the City. Engineering staff review development and redevelopment proposals
to ensure that the stormwater management policies and standards detailed in Section 3.0 of this plan are
met. Engineering staff also consult the City’s Wellhead Protection Plan to ensure that development and
redevelopment proposals are in line with the protective measures established for the City’s sensitive
groundwater resources.
City of Edina
2018 Comprehensive Water Resources Management Plan
15-38
Staff from the City’s planning department review development and redevelopment proposals with the
guidance of the City's long-range Comprehensive Plan and Zoning Ordinance. In addition to
incorporating the policies and design standards of this CWRMP, the Edina Comprehensive Plan (City of
Edina, 2008) includes policies, principles, and guidelines that integrate water resources protection and
management with land use planning. Among these include the City’s land use policy to “grow and
develop in a sustainable manner that will protect its high quality natural environment, promote energy
efficiency and conservation of natural resources” and to “maintain the current open space and wetlands
acreage and seek to expand it whenever possible”. The Comprehensive Plan encourages reductions in
impervious surfaces and associated stormwater runoff from redevelopment sites and parking lot design
that promotes stormwater infiltration, and also encourages protection and improvement of urban forests,
which provides stormwater management benefits, among others.
Additionally, the Edina Comprehensive Plan includes procedures for planning, programming, and
implementing transportation infrastructure, sewer and water infrastructure, and park, recreation, and
natural area management. These plans coincide with the timing of the local comprehensive planning
timeline and support the Transportation, Water Resources, and Parks & Trails elements of the
comprehensive plan.
The City’s zoning ordinance is used by staff in the planning department to guide development and
redevelopment within the city. The zoning ordinance establishes required setbacks from naturally
occurring lakes, ponds, and streams. In some cases, the buffer requirements of the watershed districts
may be more stringent, upon which the watershed district requirements supersede. The City’s zoning
ordinance also addresses development within the floodplain districts of the city.
Small Area Plans outline a long-range vision for land use and development in a very specific area of the
City based on input from residents and business representatives. A list of completed and upcoming Small
Area Plans is available on the City’s website, www.EdinaMN.gov/657/Small-Area-Plans.
The city of Edina is basically fully developed; thus land alteration activities are primarily of a
redevelopment nature. As the city redevelops, the City utilizes the policies of the Edina Comprehensive
Plan, the zoning ordinance, and this CWRMP to encourage low-impact site design. The City also relies on
implementation of the rules and regulations of the NMCWD and MCWD.
15.4.3 Prioritization
Prioritization of projects occurs within the City’s Capital Improvement Program and budget and is
determined by the City Council with guidance from Staff and the Comprehensive Water Resources
Management Plan policies and implementation activities.
Top priority projects will be those that:
• Have measurable, long term improvements to water quality, especially for waterbodies that are
on the 303(d) Federal List of Impaired Waters or have data suggesting that the resource is not
meeting clean water goals.
City of Edina
2018 Comprehensive Water Resources Management Plan
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• Measurably reduce risks of flooding.
• Combine clean water and flood resiliency benefits.
• Solve drainage problems and reduce risk or consequence of flood, while maintaining or
improving water quality.
• Provide the most service for the least cost.
The City’s Capital Improvement Program is a five-year plan for capital improvements that is updated
annually. The CIP process includes analyzing projects contributing to public health and welfare, projects
helping to maintain and improve the efficiency of the existing systems, and projects that define a future
need within the community.
The City implemented a two-year budget cycle process which takes an alternating year approach to the
operating budget and CIP processes. While both the operating budget and CIP are reviewed every year,
the majority of the planning, focus and effort will alternate between the two.
During even-numbered years, the City’s focus will be on the CIP. Extra efforts are dedicated to reviewing
the projects in the CIP and prioritizing them based on information available at the time. The operating
budget is reviewed but only updated if necessary.
During odd-numbered years, the City’s focus will be on the operating budget. Extra efforts are dedicated
to citizen engagement processes and a two-year operating budget. The CIP is reviewed but only updated
if necessary.
During 2018, the City will develop the 2019-2023 CIP, with opportunities for public review and comment.
City Council formally adopts a CIP near the end of every even-numbered year.
A copy of the most current Capital Improvement Plan is available on the City’s website at
http://www.edinamn.gov/273/Finance.
15.4.4 Resources
The resources available to implement the Comprehensive Water Resources Management Plan include:
• City staff and equipment.
• Partnerships that leverage technical assistance, funding, and accomplish multiple overlapping
goals.
• Coordination of project planning and implementation across City departments and with private
development and redevelopment.
• Investments in stormwater management by others, driven by regulatory demand.
15.4.5 Financial Considerations
Implementation of the proposed regulatory controls, programs and improvements that are identified in
the plan will have a financial impact on the City. To establish how significant this impact will be, a review
of the means and ability of the City to fund these controls, programs, and improvements is necessary.
Table 15.5 lists potential sources of revenue for implementation of the water resources management
efforts outlined in this plan.
City of Edina 2018 Comprehensive Water Resources Management Plan 15-40
Table 15.5 Potential Funding Sources for Plan Implementation
Description of Funding Sources Revenue Generated
1. Revenue generated by City’s Stormwater Utility.$1,800,000/yr
2. Special assessments for local improvements made under the
authority granted by Minnesota Statutes Chapter 429.
Variable depending on activities
undertaken
3.Revenue generated by the Watershed Management Special Tax
Districts provided for under Minnesota Statutes Chapter 473.882.
Variable depending on activities
undertaken
4.For projects being completed by or in cooperation with
NMCWD and MCWD, project funds could be obtained from watershed
district levies associated with their administrative funds, construction
funds, preliminary funds, repair and maintenance funds or survey and
data acquisition funds, as provided for in Minnesota Statutes Chapter
103D.905.
Variable depending on activities
undertaken
5. Grant monies that may be secured from various local, regional,
County, State, or Federal agencies. This would include MnDOT, MPCA,
Metropolitan Council, the MnDNR, and others.
Variable depending on activities
undertaken
6.Other Sources: These may be other sources of funding for
stormwater activities such as tax increment financing, state aid, etc. The
City will continue to explore additional revenue sources as they become
available.
Variable
7. Tax abatement.
15.4.6 Utility funding
The stormwater utility fund was created to manage storm water runoff quality in concert with the local
watershed. City projects often include repair and maintenance of drainage systems, stormwater ponds,
and outlets structures. Single family residential properties pay a fixed quarterly fee. Commercial property
owners are charged based on the amount of impervious surface that does not allow rainwater to be
absorbed into the ground. Over time, capital costs for the storm water system have increased to meet
state standards intended to improve water quality.
To date, the stormwater utility has been able to keep up with improvements mandated by the state;
however, complying with the minimum standard hasn’t enabled the City to reach clean water goals and
sets out a timeline for accomplishing the goals that is far from reach. In order to see measurable
improvements in flood protection, drainage, and clean water services, the City will need to begin to plan
financially for significant improvements to the system, beyond the minimum standard for annual
operations and maintenance. As the City and Watershed Districts continue to evaluate and develop plans
City of Edina 2018 Comprehensive Water Resources Management Plan 15-41
for polluted waterways, there will be pressure to generate more revenue to fund stormwater management
systems.
15.4.7 Policy Issues
Solving flooding, drainage, and clean water issues in the City will require a variety of tools, practices, and
partners. Various agencies are involved with flooding and clean water services or constrain or are affected
by the provision of these services. Coordinating policies among various stakeholders including watershed
districts, MPCA, DNR, city departments, and others will make delivery of these services more achievable.
Some remaining policy issues that have been identified include:
•A need to understand the pace of progress and the investment needed to solve flooding,
drainage, and clean water issues. Statewide there have been small moves in solving these
problems. Technical obstacles (such as which practices are the most efficient, how to implement
them, assurances that they are working as intended), as well as political obstacles (such as how
much the city or other agencies are willing to invest and on what timeline) remains to be
determined.
•Alignment of the watershed district’s monitoring programs to include in-lake and BMP level
monitoring necessary to confirm designed outcomes, set goals for pollution reduction, and
prioritize future implementation.
•A need to plan surface water outcomes in public infrastructure topics. Elevating the focus of
flooding, drainage, and clean water issues in improvement projects as well as regular operation
and maintenance. This should be driven by a defined service level.
•Development of a program for inspection and maintenance of private stormwater BMPs. The City
will engage with the watershed districts to determine if a cooperative framework where the City
inspects private stormwater BMPS and the watershed districts enforce their maintenance
agreements is feasible.
•Aging infrastructure and deferred maintenance trends represent liability that stresses existing
budgets. While much of the vast network of catchbasins, ponds, outlets, and other stormwater
infrastructure on both the public and private side are made of durable materials and have long
design lives, they do require maintenance and will require reinvestment to continue to provide
service.
•Land use policies are connected to local flood risk. Increasing impervious cover and an already
overtaxed public system make it difficult to keep up with local flood issues.
•Flooding, drainage, and clean water services often compete for resources. The public demand for
each service varies greatly. Without defined service levels, resources are often allocated to solve
drainage issues or small flood issues while larger flood issues and clean water issues remain
City of Edina 2018 Comprehensive Water Resources Management Plan
15-42
unresolved. An example of this is the public demand for pumping of lakes and ponds to manage
water levels. Defining the levels of each service is necessary to make progress toward goals.
• A need to build an understanding of flooding, drainage, and clean water issues among city
departments to better incorporate water resources planning into city operations (parks,
neighborhood roadway reconstruction, planning, economic development, permitting and
development review).
City staff will continue to work with its decision-makers and partners to resolve these issues and/or
conflicts, where possible. However, many of these remaining issues are challenging problems that may
take significant time and effort to address.
15.5 Plan Update and Amendment Procedure
It is the intention of the City to have this CWRMP reviewed and approved by the NMCWD and MCWD.
Once approved, no significant changes to this plan can be made without the approval of the proposed
revisions by the watershed districts within the City that are affected by the change. Significant changes to
the local plan shall be made known to the following parties:
• City Manager, Director of Public Works, and City Engineer
• Affected Watershed District within the City
• Metropolitan Council
• City Council
Following notification of the above parties, they shall have 60 days to comment on the proposed
revisions. Failure to respond within 60 days constitutes approval. Upon receipt of approvals from the
affected watershed districts within the City, any proposed amendments will be considered approved.
Minor changes to the Plan shall be defined as changes that do not modify the goals, policies, or
commitments expressly defined in this plan by the City. Adjustment to subwatershed boundaries will be
considered minor changes provided that the change will have no significant impact on the rate or quality
in which stormwater runoff is discharged from the City boundaries. Minor changes to this plan can be
made by the staff at the City without outside review.
This CWRMP will guide the City of Edina’s activities through 2028 or until superseded by adoption and
approval of a subsequent CWRMP. Amendments to the CWRMP will be completed in accordance with
MCWD and NMCWD watershed plans, consistent with 8410.0160.
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Open Space 1
Heights Park
Garden Park
Heights Park
Lincoln Drive Floodplain
Van Valkenburg Park
Fred Richards Golf Course
Arden Park
Krahl Hill
Creek Valley School Park
Lake Edina Park
Normandale Park
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Arneson Acres Park
Countryside Park
Weber Woods
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Open Space 2
Open Space 3
Centennial Lakes Park
Alden Park
Utley Park
Open Space 2
Moore Property
Pamela Park
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York Park
Yorktown Park
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Cornelia School Park
Wooddale Park
Strachauer Park
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Fox Meadow Park
Kojetin Park
Edinborough Park
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Tingdale Park
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Frank Tupa Park
Grandview Square
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MinneapolisMinneapolis
HopkinsHopkins
RichfieldRichfieldEden PrairieEden Prairie
MinnetonkaMinnetonka
Saint Louis ParkSaint Louis Park
BloomingtonBloomington
Barr Footer: ArcGIS 10.6, 2018-05-22 11:14 File: I:\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_15_1_City_Owned_Property.mxd User: smsCITY-OWNED PROPERTYComprehensiveWater ResourcesManagement PlanCity of Edina, Minnesota
FIGURE 15.1
0 3,000
Feet
!;N
City-Owned Property
Park/Recreational Area
Streets and Highways
Creek/Stream
Lake/Pond
City of Edina Boundary
Imagery Source: MnGeo, 2016
City of Edina 2018 Comprehensive Water Resources Management Plan
16-1
16.0 Wetlands
The wetlands in the City of Edina are an important community asset. These resources supply aesthetic and
recreational benefits, in addition to providing wildlife habitat and refuge. To protect the wetlands in the
City of Edina, a goal of no net loss of wetland functions and values has been adopted.
To provide a basis for wetland protection efforts, a planning-level inventory and field assessment of all the
wetlands within the City was completed in 1999. The wetland inventory identified wetland location,
approximate size, type, wetland classification, dominant wetland vegetation, function, and value. In 2003,
the MCWD developed a Functional Assessment of Wetlands (FAW) to provide a comprehensive inventory
and assessment of existing wetland functions within the district. The City adopts the MCWD FAW for
portions of the City within the Minnehaha Creek Watershed. Figure 16.1 depicts the wetlands that were
identified and assessed as part of these two wetland inventories, which are discussed in further detail in
subsequent sections. Note that the wetlands identified within the MCWD are based on the 2003 FAW, and
the remainder are based on the City’s 1999 planning-level inventory. As projects that could impact
wetlands arise, the City will complete updated assessments as needed and in cooperation with watershed
districts, pursuant to Section 3.5.1 Wetlands Policies.
16.1 City of Edina Wetlands Inventory—1999
In order to compile detailed wetland data and assess the functions for hundreds of wetlands based on a
short field visit to each wetland, a wetland assessment methodology was needed to allow for rapid
assessment of wetlands while maximizing the integrity and value of the data. The most common wetland
assessment methodology used in Minnesota has been the Minnesota Routine Assessment Method for
Evaluating Wetland Functions commonly referred to as "MnRAM." A modified version of MnRAM 2.0 was
used for the wetland inventory in the City of Edina, which was completed in 1999. A copy of the modified
version of MnRAM 2.0 is included in Appendix F. Copies of the modified MnRAM field data sheets for
each wetland have been compiled into a Wetlands Field Investigation document. The results of the
wetlands inventory and assessment are provided in a GIS wetlands inventory database, included as
Appendix G.
16.1.1 Delineation
During the summer of 1999, a wetland inventory was conducted within the City of Edina. The inventory
consisted of field inspecting each wetland in the City and mapping the approximate wetland boundary in
general accordance with the routine determination method as specified in the U.S. Army Corps of
Engineers Wetlands Delineation Manual, 1987. Existing wetland maps (MnDNR Protected Waters and
Wetlands maps and National Wetland Inventory [NWI] maps), SCS soil survey maps, and aerial
photographs were used as baseline information to assist in the identification of wetland areas.
Additionally, USFWS Cowardin and Circular 39 classifications were assigned to each wetland during field
inspections.
City of Edina 2018 Comprehensive Water Resources Management Plan
16-2
16.1.2 Dominant Vegetation
The dominant vegetation within each wetland was characterized during the field inspection process using
the modified version of MnRAM 2.0. For each wetland, the percent of the site occupied by the various
vegetation communities for each stratum (open water, floating leafed community, emergent community,
herbaceous community, shrub community, and tree community) were recorded, along with the dominant
species present for each stratum. Where invasive and exotic species were encountered, the species and
the percent areal coverage were also recorded. In addition, the plant community types and quality level
were noted for each wetland.
16.1.3 Wetland Functional Assessment
The modified version of MnRAM 2.0 used for the wetland inventory in the City of Edina included a list of
questions for a number of assessment categories. Those questions all measure some unique characteristic
of the wetland. Each wetland functional rating was determined loosely based on the user guidance
provided for each function in MnRAM 2.0. The modified version of MnRAM 2.0 assesses the wetland
functions and values described below.
16.1.3.1 Hydrology
A wetland’s hydrologic regime or hydroperiod is the seasonal pattern of the wetland water level which is
like a hydrologic signature of each wetland type. It defines the rise and fall of a wetland’s surface and
subsurface water. The constancy of the seasonal patterns from year to year ensures a reasonable stability
for the wetland (Mitsch and Gosselink, 2000). The ability of the wetland to maintain a hydrologic regime
characteristic of the wetland type is dependent upon wetland soil and vegetation characteristics, land use
within the wetland, land use within the upland watershed contributing to the wetland, and wetland
inlet/outlet configuration. Maintenance of the hydrologic regime is important for maintaining a
characteristic vegetative community, and is closely associated with other functions including flood
attenuation, water quality and groundwater interaction. The hydrology of each wetland was rated
subjectively based on the extent of hydrologic alteration. This evaluation focused primarily on the
presence or absence of directed stormwater, outlets, and ditching along with upland watershed
characteristics.
16.1.3.2 Vegetative Diversity
The vegetative diversity rating is based primarily on the diversity of vegetation within the wetland in
comparison to an undisturbed condition for that wetland type. The vegetative diversity value of each
wetland was assessed and rated based loosely on the ratings in MnRAM 2.0 with additional emphasis
placed on invasive species and multiple communities and vegetative strata. The results of this assessment
are included in the GIS wetlands inventory database. An exceptional rating typically reflects one of the
following conditions: (1) highly diverse wetlands with virtually no non-native species, (2) rare or critically
impaired wetland communities in the watershed, or (3) the presence or previous siting of rare, threatened,
or endangered plant species. A high rating indicates the presence of diverse, native wetland species and a
City of Edina 2018 Comprehensive Water Resources Management Plan
16-3
lack of non-native or invasive species. Wetlands that rate low are primarily dominated by non-native
and/or invasive species.
16.1.3.3 Wildlife Habitat
The ability of a wetland to support various wildlife species is difficult to determine due to the specific
requirements of the many potential wildlife species that utilize wetlands. This function determines the
value of a wetland for wildlife in a more general sense, and not based on any specific species. The
characteristics evaluated to determine the wildlife habitat function include: surrounding land use
conditions, the interspersion of wetlands in the area, barriers to wildlife movement, rare wetland types,
special habitats, and the presence of rare or listed species.
16.1.3.4 Fishery Habitat
The ability of the wetland to support fisheries is determined based on the hydrologic connectivity to a
native game fishery. Wetlands without a direct hydrologic connection to a waterbody supporting fish are
determined to not provide this function. Wetlands rated high are lacustrine or riverine and provide
spawning/nursery habitat, or refuge for native game fish. Wetlands rated medium may support native
minnow populations but not native gamefish. Low quality wetlands include those with an intermittent
hydrologic connection to a waterbody with a native fishery.
16.1.3.5 Flood/Stormwater Attenuation
A wetland’s ability to provide flood storage and/or flood wave attenuation is dependent on many
characteristics of the wetland and contributing watershed. Characteristics of the subwatershed that affect
the wetlands ability to provide flood storage and attenuation include: soil types, land use and resulting
stormwater runoff volume, sediment delivery from the subwatershed, and the abundance of wetlands and
waterbodies in the subwatershed. Parameters used to assess the ability of the wetlands to provide flood
storage and/or flood wave attenuation included: flood/stormwater management levels; presence and
connectivity of channels; and most importantly outlet configuration.
16.1.3.6 Water Quality Protection
This assessment rates the wetland’s ability and opportunity to improve water quality. The level of
functioning is determined based on runoff characteristics, wetland configuration, vegetation,
sedimentation processes, and nutrient cycling. Runoff characteristics that are evaluated include: land use
in the upstream watershed, the stormwater delivery system to the wetland, sediment delivery
characteristics, and the extent, condition, and width of upland buffer. The ability of the wetland to remove
sediment from stormwater is determined by wetland configuration, emergent vegetation, and overland
flow characteristics. Indicators that a wetland has been affected by nutrient loading include the presence
of monotypic vegetation and/or algal blooms.
16.1.3.7 Shoreline Protection
Shoreline protection is typically evaluated only for those wetlands adjacent to lakes, streams, or deep
water habitats. The function is rated based on the wetlands opportunity and ability to protect the
City of Edina 2018 Comprehensive Water Resources Management Plan
16-4
shoreline; i.e., wetlands located in areas frequently experiencing large waves and high currents have the
best opportunity to protect the shore. In addition, shore areas with sandy soils and little vegetation or
shallow-rooted vegetation will benefit the most from shoreline wetlands. The wetland width, vegetative
cover, and resistance of the vegetation to erosive forces determine the wetland’s ability to protect the
shoreline. This function is rated based on the potential for bank erosion due to wave action and
characteristics of the bank along with the wetland vegetation characteristics.
16.1.3.8 Aesthetics/Recreation/Education and Science
The aesthetics/recreation/education and science function and value of a wetland could be evaluated
based on the wetland’s visibility, accessibility, evidence of recreational uses, evidence of human influences
(e.g. noise and air pollution) and any known educational or cultural purposes. Accessibility of the wetland
is key to its aesthetic or educational appreciation. While dependent on accessibility, a wetland's functional
level could be evaluated by the view it provides observers. Distinct contrast between the wetland and
surrounding upland may increase its perceived importance. Also, diversity of wetland types or vegetation
communities may increase its functional level as compared to monotypic open water or vegetation. This
wetland value was rated using best professional judgment based primarily on observable recreational
uses and potential educational benefits.
16.1.4 Wetland Sensitivity to Stormwater Input
Stormwater runoff carries soil particles, nutrients, and contaminants which can change the ecological
balance of the receiving water body. Changes in the volume or rate of stormwater entering or discharging
from the water body can also change the ecological balance. Change in the ecological balance of a
wetland often results in changes in the water quality, changes in animal and fish habitat, replacement of
native vegetation with invasive and tolerant plant species, and/or other impacts to the wetland’s functions
and values.
The state guidance document (State of Minnesota, Stormwater Advisory Group, June 1997) developed a
classification for determining the susceptibility of wetlands to degradation by stormwater input. This
classification relates wetland type to a rating of susceptibility as shown in Table 16.1. Wetlands such as
bogs and fens can be easily degraded by changes in the stormwater inflows and are designated as highly
susceptible. On the other hand, floodplain forests can tolerate relatively significant changes in the
chemical and physical characteristics of stormwater inflow without degradation and are therefore slightly
susceptible. Commonly observed shallow marshes and wet meadows dominated by cattail and reed
canary grass (respectively) have a moderate susceptibility to stormwater fluctuations.
Field notes recorded during the wetland delineations were used to determine the wetland susceptibility
classification for each wetland. The susceptibility of each wetland to degradation by stormwater input was
assessed and categorized as high, moderate, or least susceptible. Table 16.2 lists management
recommendations for wetlands within each sensitivity classification. The sensitivity rating of each wetland
is included in the GIS wetland inventory data tables.
City of Edina 2018 Comprehensive Water Resources Management Plan
16-5
Table 16.1 Susceptibility of Wetlands to Degradation by Stormwater Impacts
Highly Susceptible
Wetland Types:1
Moderately Susceptible
Wetland Types:2
Slightly Susceptible
Wetland Types:3
Least Susceptible
Wetland Types:4
Sedge Meadows Shrub-carrsa Floodplain Forestsa Gravel Pits
Open Bogs Alder Thicketsb Fresh (Wet) Meadowsb Cultivated Hydric Soils
Coniferous Bogs Fresh (Wet) Meadowsc, e Shallow Marshesc Dredged Material/Fill
Material Disposal Sites
Calcareous Fens Shallow Marshesd, e Deep Marshesc
Low Prairies Deep Marshesd, e
Lowland Hardwood
Swamps
Seasonally Flooded
Basins
1 Special consideration must be given to avoid altering these wetland types. Inundation must be avoided. Water
chemistry changes due to alteration by stormwater impacts can also cause adverse impacts. Note: All scientific
and natural areas and pristine wetland should be considered in this category regardless of wetland type.
2 a., b., c. Can tolerate inundation from 6 inches to 12 inches for short periods of time. May be completely dry in
drought or late summer conditions.
d. Can tolerate +12 inches inundation, but adversely impacted by sediment and/or nutrient loading and
prolonged high water levels.
e. Some exceptions.
3 a. Can tolerate annual inundation of 1 to 6 feet or more, possibly more than once/year.
b. Fresh meadows which are dominated by reed canary grass.
c. Shallow marshes dominated by reed canary grass, cattail, giant reed or purple loosestrife.
4 These wetlands are usually so degraded that input of urban stormwater may not have adverse impacts.
Notes: Appendix F (the “source” of this table) contains a more complete description of wetland characteristics
under each category. Pristine wetlands are those that show little disturbance from human activity.
Source: “Stormwater and Wetlands: Planning and Evaluation Guidelines for Addressing Potential Impacts of Urban
Stormwater and Snow Melt Runoff on Wetlands,” State of Minnesota. Stormwater Advisory Group, June 1997.
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Table 16.2 Management Recommendations for Each Wetland Sensitivity Classification
High Moderate Least
Special consideration must be given
to avoid altering these wetland
types. Inundation must be avoided.
Water chemistry due to alteration by
stormwater impacts can also cause
adverse impacts.
These wetlands can tolerate only
moderate alterations in hydrology.
They have very good wildlife
habitat value and a relatively
diverse plant community. They will
tolerate an additional 6 inches of
inundation, but will be adversely
impacted by sediment and/or
nutrient loading and prolonged
high water levels.
These wetlands are usually so
degraded that input of urban
stormwater may not have adverse
impacts.
Maintain the existing Stormwater
Bounce or degree of water level
fluctuation.
Maintain the existing Stormwater
Bounce or degree of water level
fluctuation. Limit the maximum
addition of water to 6 inches.
No limit for Stormwater Bounce or
degree of water level fluctuation.
Maintain the existing Discharge
Rate.
Maintain the existing Discharge
Rate.
Maintain or decrease the existing
Discharge Rate.
For 1 and 2-year storm events,
maintain existing inundation
periods.
For 1 and 2-year storm events,
maintain existing inundation
periods. Limit maximum inundation
to 1 additional day.
For 1 and 2-year storm events,
maintain existing inundation periods.
Limit maximum inundation to an
additional 7 days.
For 10-percent-annual-chance storm
events and greater, maintain existing
inundation periods.
For 10-percent-annual-chance
storm events and greater, maintain
existing inundation periods. Limit
maximum inundation to an
additional 7 days.
For 10-percent-annual-chance storm
events and greater, maintain existing
inundation periods. Limit maximum
inundation to an additional 21 days.
Do not change the outlet control
elevation.
Do not change the outlet control
elevation.
May raise outlet control elevation
up to 4 feet above existing outlet
elevation.
For landlocked wetlands, keep the
Run-out control elevations above
the delineated wetland edge.
For landlocked wetlands, keep the
Run-out control elevations above
the delineated wetland edge.
For landlocked wetlands, keep the
Run-out control elevations above the
delineated wetland edge.
Recommendation: If not already
implemented, a preservation
program should be initiated. Active
protection from invasive plant
species should begin. Purple
Loosestrife, reed canary grass, and
hybrid cattail should be eradicated
from these wetlands.
Recommendation: These wetlands
have good potential to restore
native plant communities. It is well
worth the effort to control invasive
species (especially purple
loosestrife) in these wetlands.
Recommendation: These wetlands
could be altered to improve
stormwater storage and to improve
water quality and not severely impact
the wetland quality.
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16.2 MCWD FAW—2003
In 2001-2003, the MCWD undertook an FAW within the entire MCWD, which covers the northeast portion
of the City of Edina. This assessment included the evaluation of the majority of wetlands within the MCWD
including the verification the presence of a wetland, the mapping of the approximate wetland boundary,
and assessment of wetland functions. The following sections discuss the FAW in more detail.
16.2.1 Delineation and Inventory
The 2003 wetland assessment evaluated the wetlands identified in the Hennepin Conservation District
Comprehensive Wetland Inventory (HCWI) that were greater than one-quarter acre in size. Most of the
wetlands greater than approximately one-quarter acre in size were inventoried and field evaluated, to
determine if the area was actually a wetland. The inventory identified wetland vegetation, type, location
and boundaries, size, groundwater interaction, function, restoration potential, as well as the presence of
buffers, invasive or nuisance vegetation, and rare/unique features. Wetland functions were evaluated
using a variant of the MnRAM. Restoration potential was estimated based on wetland size, property
ownership, and ease of restoration.
Additionally, USFWS Cowardin and Circular 39 classifications were assigned to each wetland during field
inspections.
Wetlands identified on the HCWI that are smaller than one-quarter acre in size were originally identified
using historic aerial photos, infrared photos, soil types, NWI and PWI data, and Hennepin County
Mosquito Control maps but were not field verified or assessed as part of the 2003 MCWD FAW. These
wetlands have been included in the City’s updated wetland inventory for the portion of the City within the
MCWD, but may not have complete information available.
16.2.2 Critical Wetland Resources
Wetlands in the MCWD were evaluated for designation as critical resources based on several features
defined in the Minnesota Statutes. These critical wetland resources are classified by the MCWD into the
Preserve management classification. Criteria for designating wetlands as critical resources are as follows:
• Outstanding Resource Value Waters (Minn. Rules 7050.0180)
• Designated Scientific and Natural Areas (Minn. Rules 86A.05)
• Wetlands with known occurrences of threatened or endangered species (Minn. Stat. 84.0895)
• State Wildlife Management Areas (Minn. Stat. 86A.05)
• State Aquatic Management Areas (Minn. Stat. 86A.05)
• Calcareous Fens (Minn. Rules 8420.1010 through 8420.1060)
• High priority areas for wetland preservation, enhancement, restoration, and establishment (Minn.
Rules 8420.0350, subpart 2)
• Designated historic or archaeological sites
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16.2.3 Wetland Susceptibility to Stormwater
The state guidance document Stormwater and Wetlands: Planning and Evaluation Guidelines for
Addressing Potential Impacts of Urban Stormwater and Snow-Melt Runoff on Wetlands (State of
Minnesota, Stormwater Advisory Group, June 1997) developed a methodology for determining the
susceptibility of wetlands to degradation by stormwater input. This methodology relates wetland type to a
level of susceptibility as shown in Table 16.1. The MCWD used this methodology to identify those
wetlands susceptible to degradation by stormwater.
16.2.4 Wetland Management Classification
Based on the results of the field evaluation and its resource significance and susceptibility to stormwater
input, each wetland within the MCWD was assigned to one of four categories: Preserve, Manage 1,
Manage 2, or Manage 3. Preserve wetland are the highest quality wetlands or have been identified as
important wetland resources. The MCWD management classification of each wetland is included in the
GIS wetland inventory data tables.
16.3 Circular 39 Wetland Classification
The Wetlands of the United States was published in 1959 by the USFWS and is commonly referred to as
"Circular 39" (Shaw and Fredine, 1959). The Circular 39 Wetland Classification System was the first method
that the USFWS used to classify wetland basins in the U.S. It is composed of 20 wetland types of which 7
are found in the City of Edina. A general description of each wetland type is provided below.
As part of the City of Edina’s 1999 wetland inventory and the 2003 MCWD FAW, Circular 39 classifications
were assigned to each wetland during field inspections. Figure 16.2 shows the wetlands classification
within the City. The Circular 39 classification for each wetland within the City is included in the GIS
wetlands inventory database.
16.3.1 Type 1: Seasonally Flooded Basin, Floodplain Forest
Soil is covered with water or is waterlogged during variable seasonal periods but usually is well-drained
during much of the growing season. This type is found both in upland depressions and in overflow
bottomlands. In uplands, basins or flats may be filled with water during periods of heavy rain or melting
snow.
Vegetation varies greatly according to season and duration of flooding: from bottomland hardwoods to
herbaceous plants. Where the water has receded early in the growing season, smartweeds, wild millet, fall
panicum, redroot cyperus, and weeds (i.e., marsh elder, ragweed, and cockleburs) are likely to occur.
Shallow basins that are submerged only very temporarily usually develop little or no wetland vegetation.
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16.3.2 Type 2: Wet Meadow, Fresh Wet Meadow, Wet to Wet-Mesic Prairie, Sedge Meadow, and Calcareous Fen
Soil is usually without standing water during most of the growing season but is waterlogged within at
least a few inches of the surface. Meadows may fill shallow basins, sloughs, or farmland sags, or these
meadows may border shallow marshes on the landward side. Vegetation includes grasses, sedges, rushes
and various broad-leaved plants. In the North, representative plants are Carex, rushes, redtop, reed
grasses, manna grasses, prairie cordgrass, and mints. Other wetland plant community types include low
prairies, sedge meadows, and calcareous fens.
16.3.3 Type 3: Shallow Marsh
Soil is usually waterlogged early during the growing season and may often be covered with as much as
6 inches or more of water. These marshes may nearly fill shallow lake basins or sloughs, or may border
deep marshes on the landward side. These are common as seep areas on irrigated lands. Vegetation
includes grasses, bulrushes, spike rushes, and various other marsh plants such as cattails, arrowhead,
pickerelweed, and smartweeds. Common representatives in the North are reed, whitetop, rice cutgrass,
Carex, and giant bur reed.
16.3.4 Type 4: Deep Marsh
Soil is usually covered with 6 inches to 3 feet or more of water during the growing season. These deep
marshes may completely fill shallow lake basins, potholes, limestone sinks and sloughs, or they may
border open water in such depressions. Vegetation includes cattails, reeds, bulrushes, spike rushes and
wild rice. In open areas, pondweeds, naiads, coontail, watermilfoils, waterweeds, duckweed, water lilies, or
spatterdocks may occur.
16.3.5 Type 5: Shallow Open Water
Shallow ponds and reservoirs are included in this type. Water is usually less than 10-feet deep and is
fringed by a border of emergent vegetation similar to open areas of Type 4. Vegetation (mainly at water
depths less than 6 feet) includes pondweeds, naiads, wild celery, coontail, watermilfoils, muskgrass,
waterlilies, and spatterdocks.
16.3.6 Type 6: Shrub Swamp; Shrub Carr, Alder Thicket
The soil is usually waterlogged during the growing season and is often covered with as much as 6 inches
of water. Shrub swamps occur mostly along sluggish streams and occasionally on flood plains. Vegetation
includes alders, willows, buttonbush, dogwoods and swamp-privet.
16.3.7 Type 7: Wooded Swamps; Hardwood Swamp, Coniferous Swamp
The soil is waterlogged at least to within a few inches of the surface during the growing season and is
often covered with as much as 1 foot of water. Wooded swamps occur mostly along sluggish streams, on
old riverine oxbows, on floodplains, on flat uplands, and in very shallow lake basins. Forest vegetation
includes tamarack, arborvitae (cedar), black spruce, balsam fir, red maple, and black ash. Northern
City of Edina 2018 Comprehensive Water Resources Management Plan
16-10
evergreen swamps usually have a thick ground covering of mosses. Deciduous swamps frequently support
beds of duckweeds, smartweeds, and other herbs.
16.4 Cowardin Wetland Classification
The Classification of Wetlands and Deepwater Habitats of the United States was published by the USFWS in
1979 (Cowardin et al., 1979). This wetland classification methodology was used to classify wetlands in the
development of the NWI maps beginning in the late 1970s and early 1980s. The structure of the
classification is hierarchical progressing from Systems and Subsystems, at the most general levels, to
Classes, Subclasses, and Dominance Types at the most specific levels. A general description of the
hierarchical structure is provided below.
As part of the City of Edina’s 1999 wetland inventory and the 2003 MCWD FAW, Cowardin wetland
classifications were assigned to each wetland during field inspections. The Cowardin classification for each
wetland within the City is included in the GIS wetlands inventory database.
16.4.1 System
The term System refers to a complex of wetlands and deep water habitats that share the influence of
similar hydrologic, geomorphologic, chemical, or biological factors. The primary systems found in Edina
are Palustrine, Lacustrine, and Riverine while Marine and Estuarine Systems are not found in the City.
L: Lacustrine (lakes and deep ponds) - Lacustrine Systems include wetlands and deep water
habitats with all of the following three characteristics:
1. Situated in a topographic depression or a dammed river channel;
2. Lacking trees, shrubs, persistent emergents, emergent mosses or lichens with greater than 30
percent areal coverage;
3. Total area exceeds 8 hectares (20 acres).
Basins or catchments less than 8 hectares in size are also included if they have at least one of the
following characteristics:
• A wave-formed or bedrock feature forms all or part of the shoreline boundary; or
• The catchment has, at low water, a depth greater than 2 meters (6.6 feet) in the deepest
part of the basin.
P: Palustrine (shallow ponds, marshes, swamps and sloughs) - Palustrine Systems include all
non-tidal wetlands dominated by trees, shrubs, persistent emergents, emergent mosses or
lichens.
R: Riverine (rivers, creeks and streams) - Riverine Systems are contained in natural or artificial
channels periodically or continuously containing flowing water. Upland islands or Palustrine
wetlands may occur in the channel, but they are not part of the Riverine System.
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16.4.2 Subsystem
The term Subsystem refers to a further subdivision of Systems into more specific categories. The
Palustrine System has no subsystems associated with it while Lacustrine Systems have two Subsystems
and Riverine Systems have four, of which only one applies in the City of Edina. Each Subsystem is unique
for the System to which it applies.
L1: Limnetic - Extends outward from Littoral boundary and includes deep water habitats within the
Lacustrine System.
L2: Littoral - Extends from shoreward boundary to 2 meters (6 feet) below annual low water or to the
maximum extent of non-persistent emergents, if these grow at greater than 2 meters.
R2: Lower Perennial
16.4.3 Class, Subclass
The wetland Class is the highest taxonomic unit below the Subsystem level. The Class code describes the
general appearance of the habitat in terms of either the dominant life form of the vegetation or the
physiography and composition of the substrate. Life forms (e.g. trees, shrubs, emergents) are used to
define classes because they are easily recognizable, do not change distribution rapidly, and have
traditionally been used to classify wetlands. Finer differences in life forms are recognized at the Subclass
level.
Mixed classes are used as sparingly as possible, under two main conditions: (1) The wetland contains two
or more distinct cover types each encompassing at least 30 percent areal coverage of the highest life
form, but is too small in size to allow separate delineation of each cover type; and (2) The wetland
contains two or more classes or subclasses each comprising at least 30 percent areal coverage so evenly
interspersed that separate delineation is not possible at the scale used for classification. Mixed subclasses
are also allowed and follow the same rules for mixed classes (Cowardin et al., 1979).
AB: Aquatic Bed—Includes wetlands and deep water habitats dominated by plants that grow
principally on or below the surface of the water for most of the growing season in most years.
Subclasses include: AB1 = Algal, AB2 = Aquatic Moss, AB3 = Rooted Vascular, AB4 = Floating
Vascular, AB5 = Unknown Submergent, and AB6 = Unknown Surface.
EM: Emergent—Characterized by erect, rooted, herbaceous hydrophytes, excluding mosses and
lichens. This vegetation is present for most of the growing season in most years.
Subclasses include: EM1 = Persistent (plants that normally remain standing at least until the
beginning of the next growing season), and EM2 = Nonpersistent (plants which fall to the surface
of the substrate or below the surface of the water at the end of the growing season).
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FO: Forested—Woody vegetation greater than 6 meters (20 feet) tall.
Subclass determination is based on: which type represents more than 50 percent of the areal
canopy coverage during the leaf-on period. Subclasses include: FO1 = Broad-leaved Deciduous,
FO2 = Needle-leaved Deciduous, FO3 = Broad-leaved Evergreen, FO4 = Needle-leaved
Evergreen, FO5 = Dead, FO6 = Deciduous, and FO7 = Evergreen.
SS: Scrub/Shrub—Woody vegetation less than 6 meters (20 feet) tall. The species include true shrubs,
young trees (saplings) or trees that are small or stunted because of environmental conditions.
Subclass determination is based on: which type represents more than 50 percent of the areal
canopy coverage during the leaf-on period and include: SS1 = Broad-leaved Deciduous,
SS2 = Needle-leaved Deciduous, SS3 = Broad-leaved Evergreen, SS4 = Needle-leaved Evergreen,
SS5 = Dead, SS6 = Deciduous (used if deciduous woody vegetation cannot be identified on aerial
photography as either Broad-leaved or Needle-leaved), and SS7 = Evergreen (used if evergreen
woody vegetation cannot be identified on aerial photography as either Broad-leaved or
Needle-leaved).
UB: Unconsolidated Bottom—Includes all wetlands and deep water habitats with at least 25 percent
cover of particles smaller than stones (less than 6-7 cm.), and a vegetative cover less than 30 percent.
16.4.4 Water Regime
Precise description of hydrologic characteristics requires detailed knowledge of the duration and timing of
surface inundation, both yearly and long-term, as well as an understanding of groundwater fluctuations.
Because such information is seldom available, the water regimes that, in part, determine characteristic
wetland and deep water plant and animal communities are described here in only general terms
(Cowardin, et al., 1979). Water regimes are grouped under two major categories, Tidal and Nontidal. The
Tidal Water Regime does not occur in the City so is not described here.
A: Temporarily Flooded—Surface water present for brief periods during the growing season,
but the water table usually lies well below the soil surface. Plants that grow both in uplands and
wetlands are characteristic of this water regime. The temporarily flooded regime also includes
wetlands where water is present for variable periods without detectable seasonal periodicity.
Weeks, months, or even years may intervene between periods of inundation. The dominant plant
communities under this regime may change as soil moisture conditions change.
B: Saturated—The substrate is saturated to the surface for extended periods during the growing
season, but surface water is seldom present.
C: Seasonally Flooded—Surface water is present for extended periods especially early in the
growing season, but is absent by the end of the growing season in most years. When surface
water is absent, the water table is often near the land surface. The water table after flooding
ceases is highly variable, extending from saturated to a water table well below the ground surface.
City of Edina 2018 Comprehensive Water Resources Management Plan
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F: Semipermanently Flooded—Surface water persists throughout the growing season in most
years. When surface water is absent, the water table is usually at or very near the land surface.
G: Intermittently Exposed—Surface water is present throughout the year except in years of
extreme drought.
H: Permanently Flooded—Water covers the land surface throughout the year in all years.
Vegetation is composed of obligate hydrophytes.
16.4.5 Special Modifiers
Many wetlands and deep water habitats are man-made and natural ones have been modified to some
degree by the activities of man or beavers. Since the nature of these modifications often greatly influences
the character of such habitats, special modifying terms have been included here to emphasize their
importance (Cowardin, et al., 1979).
b: Beaver—Created or modified by a beaver dam.
d: Partly Drained—The water level has been artificially lowered, but he area is still classified as
wetland because soil moisture is sufficient to support hydrophytes. Drained areas are not
considered wetland if they can no longer support hydrophytes.
f: Farmed—The soil surface has been mechanically or physically altered for production of crops,
but hydrophytes will become reestablished if farming is discontinued.
h: Diked/Impounded—Created or modified by a barrier or dam which purposefully or
unintentionally obstructs the outflow of water. Both man-made and beaver dams are included.
r: Artificial—Refers to substrates classified as Rock Bottom, Unconsolidated Bottom, Rocky
Shore, and Unconsolidated Shore that were emplaced by humans, using either natural materials
such as dredge spoil or synthetic materials such as discarded automobiles, tires, or concrete.
s: Spoil—Refers to the placement of spoil materials which have resulted in the establishment of
wetland.
x: Excavated—Lies within a basin or channel excavated by humans.
16.5 Public Waters
The MnDNR has designated certain waters of the state as public waters (Minn. Rules 6115.1060). MnDNR
“Public Waters Inventory (PWI)” maps show public waters within the City. A MnDNR permit is required for
work that would alter the course, current, or cross-section of a designated public water. PWI maps show
public waters as one of the following: public water basin; public water wetland; public water watercourse;
or, public ditch/altered natural watercourse.
City of Edina 2018 Comprehensive Water Resources Management Plan 16-14
Table 16.3 lists the MnDNR Public Waters within the city. The table includes the MnDNR identifier for
each pond, as well as the corresponding subwatershed for this stormwater study. Public water basins are
identified with a number and the letter “P”. Public water wetlands are identified with a number and the
letter “W”. Public wetlands include, and are limited to, Type 3, 4, and 5 wetlands that have been
designated as public waters and are 2½ acres or more in size (10 acres in unincorporated areas).
Public water courses and ditches in Edina include:
•Minnehaha Creek
•North Fork of Nine Mile Creek
•South Fork of Nine Mile Creek
•Braemar Branch of Nine Mile Creek
Table 16.3 MnDNR Public Waters within Edina
Waterbody ID
Public Waters
Class Public Waters Name
Corresponding
Subwatershed ID(s)
27002801 P Cornelia (North) NC_62
27002802 P Cornelia (South) SC_1
27002900 P Lake Edina LE_1
27004100 P Edina Mill Pond MHC_ 2
27004400 P Indianhead Lake IH_1
27004500 P Arrowhead Lake AH_1
27005000 P Bredesen MD_50, MD_1
27005400 P Meadowbrook Lake
27005500 P Mirror Lake ML_1, ML_32
27005600 P Hawkes Lake HL_1
27066600 W EI_19
27066700 W EI_1
27066800 P Highlands Park Pond HI_1
27066900 W Melody Lake ML_8
27067000 W Lake Harvey MHS_22
27067100 P Birchcrest NMC_112
27067200 W CO_1
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Waterbody ID
Public Waters
Class Public Waters Name
Corresponding
Subwatershed ID(s)
27067300 P Heights NMC_1
27067400 W NMC_77
27067500 P Pamela Pond LP_14, LP_26
27067600 W NC_5
27067700 W Nancy NC_2
27067800 W NC_30
27067900 W NC_3
27068000 W NC_4
27078000 W EI_32
27078100 W ML_28
27078200 W ML_16
27079900 W NMN_76, NMN_55
27080000 W NMN_75
27080100 W NMN_50
27080200 W MD_25
27080300 W MD_21
27080400 W EdCrk3
27080500 W NMN_24
27080600 W Pauly's Pond AH_6
27080700 W Garrison Pond EP_2
27080800 W EP_2
27101300 W
BRCrk4, BRCrk15, BRCrk16,
BRCrk17, BRCrk18, NMSB_12
27103800 W SWP_3
27103900 W SWP_5, SWP_14, SWP_35
27104000 W SWP_1, SWP_2, SWP_4
27104100 W NMS_3
27110600 W EdCrk5
Mud Lake
Lake Cornelia
Lake Edina
Mirror Lake
Arrowhead Lake
Indianhead Lake
Highlands Lake
Melody Lake
Lake Pamela
Harvey Lake
Hawkes Lake
Centennial Lakes
Min
n
e
h
a
h
a
Cr
e
ek
£¤169
100
62
100
456717 456731
4567158
456731
Nine Mile CreekWatershed District
Minnehaha CreekWatershed District
North
B
ranchNineMileCreek
SouthBranc h N i ne Mile
C
r
eekMinneapolisMinneapolis
HopkinsHopkins
Eden PrairieEden Prairie
RichfieldRichfield
BloomingtonBloomington
MinnetonkaMinnetonka
Saint Louis ParkSaint Louis Park
Barr Footer: ArcGIS 10.4.1, 2017-10-31 10:05 File: I:\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_16_1_Wetlands.mxd User: smsWETLANDSComprehensiveWater ResourcesManagement PlanCity of Edina, Minnesota
FIGURE 16.1
0 3,000
Feet
!;N
Lake/Wetland
Watershed District Boundary
Streets and Highways
Creek/Stream
City of Edina Boundary
Imagery Source: MnGeo, 2016
Mud Lake
Lake Cornelia
Lake Edina
Mirror Lake
Arrowhead Lake
Indianhead Lake
Highlands Lake
Melody Lake
Lake Pamela
Harvey Lake
Hawkes Lake
Centennial Lakes
Minne
h
a
h
a
C
r
e
e
k£¤169
100
62
100
456717 456731
4567158
456731
Nine Mile CreekWatershed District
Minnehaha CreekWatershed District
No
rth
B
ranchNineMileCreek
SouthBranch N i ne MileCreek
Min n eapolisMin n eapolis
Hopkin sHopkin s
Eden PrairieEden Prairie
RichfieldRichfield
Bloomin gtonBloomin gton
Min n eton kaMin n eton ka
Sain t Louis ParkSain t Louis Park
Barr Footer: ArcGIS 10.4.1, 2017-10-31 10:07 File: I:\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_16_2_Wetland_Classifications.mxd User: smsWETLAND CLASSIFICATIONSComprehensiveWater ResourcesManagement PlanCity of Edina, Minnesota
FIGURE 16.2
0 3,000
Feet
!;N
Watershed District Boun dary
Streets an d Highways
City of Edin a Boun dary
Wetlan d T ype*
Un classified
T ype 1
T ype 1 Predomin an t + Others
T ype 2
T ype 2 Predomin an t + Others
T ype 3
T ype 3 Predomin an t + Others
T ype 4
T ype 5
T ype 5 Predomin an t + Others
T ype 6
T ype 7
T ype 7 Predomin an t + Others
Imagery Source: Mn Geo, 2016
*Based on the Fish an d Wildlife ServiceCircular 39 Classification System.
Wetlan ds within the Min n ehaha CreekWatershed District were iden tified an dassessed in 2005 as part of theMin n ehaha Creek Fun ction al Assessmen tof Wetlan ds. Wetlan ds located in theremain in g portion of the city wereiden tified an d assessed in 1999 as partof the City of Edin a’s wetlan d in ven tory.
City of Edina
2018 Comprehensive Water Resources Management Plan
17-1
17.0 References
Barr Engineering Company, 1999a. Glen Lake Use Attainability Analysis.
Barr Engineering Company, 1999b. Round Lake Use Attainability Analysis.
Barr Engineering Company, 2001. Bloomington Use Attainability Analysis. Prepared for Nine Mile Creek
Watershed District.
Barr Engineering Company, 2004. Draft Mirror Lake Use Attainability Analysis.
Barr Engineering Company, 2006. Draft Lake Cornelia Use Attainability Analysis.
Barr Engineering Company, 2016. City of Edina Imperviousness Assumptions for Stormwater Modeling.
Prepared for City of Edina.
City of Edina, 2009. Edina Comprehensive Plan.
Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe, 1979. Classification of Wetlands and Deepwater
Habitats of the United States. U.S. Fish and Wildlife Service, FWS/OBS-79/31.
Federal Emergency Management Agency (FEMA), 2016. Flood Insurance Study for Hennepin County, MN
All Jurisdictions.
Hennepin Conservation District, 2003. Functional Assessment of Wetlands, Minnehaha Creek Watershed
District.
Minnehaha Creek Watershed District, 2007. Minnehaha Creek Watershed District Comprehensive Water
Resources Management Plan.
Minnehaha Creek Watershed District, 2018. Minnehaha Creek Watershed District Watershed Management
Plan.
Minnesota Department of Natural Resources, 1999. Minnesota Routine Assessment Method for Evaluating
Wetland Functions (MnRAM).
Minnesota Pollution Control Agency (MPCA), 2000. Protecting Water Quality in Urban Areas, March 2000.
Minnesota Pollution Control Agency (MPCA), 2005. Minnesota Stormwater Manual.
Minnesota Pollution Control Agency (MPCA), 2010. Nine Mile Creek Biological Stressor Identification.
Prepared by Barr Engineering Company.
Minnesota Pollution Control Agency (MPCA), 2013. Minnehaha Creek E. coli Bacteria Total Maximum Daily
Load. Prepared by Tetra Tech, Inc.
Minnesota Pollution Control Agency (MPCA), 2016. Twin Cities Metropolitan Area Chloride Total Maximum
Daily Load Study. Prepared by MPCA and LimnoTech.
City of Edina
2018 Comprehensive Water Resources Management Plan
17-2
Mitsch, W.J. and J.G. Gosselink, 2000. Wetlands.
Nine Mile Creek Watershed District, 2017. Nine Mile Creek Watershed District Water Management Plan.
National Oceanic and Atmospheric Administration, 2013. Atlas 14 Volume 8 - Precipitation-Frequency Atlas
of the United States, Midwestern States.
Schwab, G.O., D. Fangmeier, W. Elliot, and R. Frevert, 1993. Soil and Water Conservation Engineering.
Shaw, S.P., and C.G. Fredine, 1959. Wetlands of the United States: Their Extent and Their Value to
Waterfowl and Other Wildlife. U.S. Fish and Wildlife Service. Circular 39.
State of Minnesota, Stormwater Advisory Group, 1997. Stormwater and Wetlands: Planning and Evaluation
Guidelines for Addressing Potential Impacts of Urban Stormwater and Snow Melt Runoff on Wetlands.
June 1997.
U.S. Army Corps of Engineers Wetlands Delineation Manual, 1987.
U.S. Department of Commerce, Weather Bureau, 1961. “Technical Paper No. 40. Rainfall Frequency Atlas of
the United States.”
U.S. Environmental Protection Agency, 1988. Stormwater Management Model, Version 4: User’s Manual.
Appendices
Appendix A City of Edina Imperviousness Assumptions for Stormwater Modeling
Appendix B Summary of Nine Mile Creek and Minnehaha Creek Modeling Approach
Appendix C Legacy Flood Protection Projects
Appendix D List of Pond Improvement Recommendations
Appendix E Aquatic Vegetation Prioritization List
Appendix F Modified Minnesota Routine Assessment Method for Evaluating
Wetland Functions (MnRAM) Version 2.0
Appendix G GIS Wetlands Inventory Database
Appendix A
City of Edina Imperviousness Assumptions for Stormwater Modeling
Barr Engineering Co. 4300 MarketPointe Drive, Suite 200, Minneapolis, MN 55435 952.832.2600 www.barr.com
Technical Memorandum
To: Jessica Wilson and Ross Bintner From: Cory Anderson, Sarah Stratton, and Janna Kieffer Subject: City of Edina Imperviousness Assumptions for Stormwater Modeling Date: October 25, 2016 Project: 23/27-0354.00 BCO 160
1.0 Introduction
Redevelopment throughout the City of Edina (City), particularly the rebuilding of older homes with newer,
larger homes, has raised questions about the imperviousness assumptions used for stormwater modeling.
Therefore, as directed by the City, Barr evaluated the most recent imperviousness data throughout
different neighborhoods of the city to help determine if the assumptions that were previously used for
stormwater modeling are representative of current conditions. This memo documents the findings of this
imperviousness assessment, referred to herein as the “2016 analysis”.
There are two forms of imperviousness: (1) “Total Impervious” which represents the total area of
impervious surfaces such as pavement, roof tops, etc., and (2) “Directly Connected Impervious” which
represents the area of impervious surface from which water flows directly into storm sewer or water
bodies. The Directly Connected Impervious area is the area that is most important for hydrologic
modeling. The majority of this memo discusses the Total Impervious, and Section 5.0 discusses methods
for converting from Total Impervious area to Directly Connected Impervious area. Table 1 provides a
summary of the imperviousness assumptions used for modeling associated with both the 2003 and 2011
CWRMPs (2003/2011 CWRMPs).
Table 1 Imperviousness assumptions from the 2003/2011 CWRMPs
Land Use Type Total Impervious %
Directly Connected
Impervious %
Ratio of Directly
Connected to Total
Commercial 90% 80% 0.889
Developed Park Not previously used Not previously used N/A
Golf Course 5% 2% 0.400
High Density Residential 70% 40% 0.571
Highway 50% 50% 1.000
Industrial/Office 90% 80% 0.889
Institutional 40% 20% 0.500
Institutional - High Imperviousness 70% 50% 0.714
Low Density Residential 40% 20% 0.500
Medium Density Residential 55% 30% 0.545
Natural/Park/Open 2% 0% 0.000
Open Water 100% 100% 1.000
To: Jessica Wilson and Ross Bintner From: Cory Anderson, Sarah Stratton, and Janna Kieffer Subject: City of Edina Imperviousness Assumptions for Stormwater Modeling Date: October 25, 2016 Page: 2
P:\Mpls\23 MN\27\23271514 2017 CWRMP SW Modeling Updates\WorkFiles\Imperviousness Analysis\Imperviousness Analysis Summary.docx
Land Use Type Total Impervious %
Directly Connected
Impervious %
Ratio of Directly
Connected to Total
Other Not previously used Not previously used N/A
Very Low Density Residential 12% 8% 0.667
Wetland 100% 100% 1.000
2.0 Data Sources
The main data source for this 2016 analysis is the 2011 Twin Cities impervious surface area dataset
developed by the University of Minnesota (reference [1]). This geographic information system (GIS)
dataset is a 30-meter resolution raster (grid) of impervious surface classification for the seven-county Twin
Cities Metropolitan Area. The values in this GIS layer represents total imperviousness, not directly
connected imperviousness. The impervious surface classification was created using a combination of
multi-temporal Landsat (satellite) data and Light Detection and Ranging (LiDAR) data. This raster data set
is shown in Figure 1.
Barr analyzed the imperviousness data by land use type and neighborhood. This approach allowed us to
review the range of results by neighborhood for imperviousness of each land use type. A neighborhood
analysis was performed (as opposed to a parcel analysis) due to the larger grid size of the imperviousness
raster dataset (i.e., the U of M’s imperviousness data is too coarse for a parcel-level analysis). The City
provided the neighborhood GIS layer containing 45 neighborhoods throughout the city (Figure 2
(reference [2]).
The land use data utilized for this analysis was the same land use data provided by the City for the
2003/2011 CWRMPs (reference [3]). Using the same land use data allowed us to analyze results with the
understanding that changes were strictly based on the changing imperviousness within the city. The land
use data is shown in Figure 3.
3.0 Analysis Methods
The neighborhood and land use type polygon GIS layers were intersected to define smaller polygons of
land use type within each neighborhood. Zonal statistics were then used to calculate the average raster
cell value for each land use type within each neighborhood (Table 2). Additionally, the area of each land
use type within each neighborhood was calculated to understand which land use types are more
prevalent in each neighborhood (Table 3). The data from Table 2 and Table 3 were then used to create a
histogram of imperviousness and a cumulative area function to understand the range of imperviousness
for each land use type. Figure 4 also shows the average and range of the resulting imperviousness values
of all neighborhoods by land use type. These results are presented and discussed in Section 4.0.
CahillBraemar Hills
Countryside
Parkwood Knolls
Concord
Southdale
Bredesen Park
Lake Cornelia
Indian Hills
Highlands
Dewey Hill
Creek Valley
Todd Park
Birchcrest
Grandview
Presidents
The Heights
Prospect Knolls
Parklawn
South Cornelia
Melody Lake
Arden Park
Normandale Park
Pentagon Park
Morningside
Pamela Park
Lake Edina
Fox Meadow Golf Terrace Heights
Country ClubInterlachen Park
Chowen Park
Indian Trails
Hilldale
Promenade
Rolling Green
Brookview Heights
Edinborough
Minnehaha Woods
Strachauer Park
White Oaks
Centennial Lakes
Sunny Slope
Creek Knoll
50th and France
Source: Esri, DigitalGlobe, GeoEye, i-cubed, USDA, USGS, AEX,Getmapping, Aerogrid, IGN, IGP, and the GIS User Community
PERCENT IMPERVIOUSNESS2011 U OF M DATASETImperviousness AnalysisCity of Edina
FIGURE 1
Barr Footer: ArcGIS 10.4, 2016-09-16 16:52 File: I:\Client\Edina\Projects\CRWMP_Update_2017\Maps\Meetings\Percent Imperviousness.mxd User: cda1 0 1
Miles
!;N
Percent ImperviousnessHigh : 100 Low : 0
Edina Neighborhoods
Note: Raster grid cells with0% imperviousness aretransparent and the backgroundimagery is visible.
§¨¦494§¨¦494
£¤212
£¤169
£¤169
100
62
7
10062
7
456728
456717
456753
456734
456731
45673
4567158
456720
456732
456761
CahillBraemar Hills
Countryside
Parkwood Knolls
Concord
Southdale
Bredesen Park
Lake Cornelia
Indian Hills
Highlands
Dewey Hill
Creek Valley
Todd Park
Birchcrest
Grandview
Presidents
The Heights
Prospect Knolls
Parklawn
South Cornelia
Melody Lake
Arden Park
Pentagon Park
Morningside
Pamela Park
Lake Edina
Fox Meadow Golf Terrace Heights
Country ClubInterlachen Park
Chowen Park
Normandale Park
Indian Trails
Hilldale
Promenade
Rolling Green
Brookview Heights
Edinborough
Minnehaha Woods
Strachauer Park
White Oaks
Centennial Lakes
Sunny Slope
Creek Knoll
50th and France
Source: Esri, DigitalGlobe, GeoEye, i-cubed, USDA, USGS, AEX,Getmapping, Aerogrid, IGN, IGP, and the GIS User Community
EDINA NEIGHBORHOODSImperviousness AnalysisCity of Edina
FIGURE 2
Barr Footer: ArcGIS 10.4, 2016-09-16 16:24 File: I:\Client\Edina\Projects\CRWMP_Update_2017\Maps\Meetings\Edina Neighborhoods.mxd User: cda1 0 1
Miles
!;N
Edina Neighborhoods
Streets and Highways
Interstate Highway
US Highway
State Trunk Highway
County State-Aid Highway
Source: Esri, DigitalGlobe, GeoEye, i-cubed, USDA, USGS, AEX,Getmapping, Aerogrid, IGN, IGP, and the GIS User Community
LAND USE TYPEImperviousness AnalysisCity of Edina
FIGURE 3
Barr Footer: ArcGIS 10.4, 2016-09-16 16:44 File: I:\Client\Edina\Projects\CRWMP_Update_2017\Maps\Meetings\Land Use Map.mxd User: cda1 0 1
Miles
!;N
Edina Neighborhoods
Land Use
Natural/Park/Open
Developed Parkland
Golf Course
Very Low Density Residential
Low Density Residential
Medium Density Residential
High Density Residential
Institutional
Institutional - High Imperviousness
Highway
Commercial
Industrial/Office
Other
Open Water
Wetland
Table 2 - Mean total imperviousness by land use type within each neighborhood
Commercial
Developed
Park Golf Course
High Density
Residential Highway
Industrial/
Office Institutional
Institutional -
High
Imperviousness
Low Density
Residential
Medium
Density
Residential
Natural/Park/
Open
Open
Water Other
Very Low
Density
Residential Wetland Average
% Impervious
Legend
50th and France 87.3 72.6 52.0 61.8 86.5
Arden Park 64.6 0.0 34.3 63.4 39.4 32.6 65.6 7.3 100.0 36.6 100.0
Birchcrest 48.9 68.1 32.8 18.4 100.0 21.0 36.9 90.0
Braemar Hills 66.7 3.5 63.3 69.3 54.8 27.9 14.2 100.0 12.5 100.0 29.7 80.0
Bredesen Park 72.2 4.6 40.9 61.8 33.7 42.1 5.6 100.0 100.0 46.4 70.0
Brookview Heights 71.8 59.7 30.9 12.6 100.0 21.3 100.0 37.9 60.0
Cahill 72.4 49.9 74.1 60.4 63.5 24.3 100.0 41.9 100.0 70.5 50.0
Centennial Lakes 88.0 41.3 60.0 83.0 100.0 76.9 40.0
Chowen Park 42.2 38.9 7.7 100.0 38.6 30.0
Concord 53.2 38.6 53.6 60.6 35.3 19.4 100.0 100.0 45.5 20.0
Country Club 33.8 65.6 38.0 100.0 41.1 10.0
Countryside 22.3 37.7 32.7 28.6 49.1 25.7 100.0 18.8 100.0 32.0 0.0
Creek Knoll 62.2 34.2 76.7 14.9 100.0 36.9
Creek Valley 12.8 39.6 30.8 27.7 2.0 100.0 100.0 36.9
Dewey Hill 6.5 65.5 32.0 41.2 11.8 100.0 100.0 39.3
Edinborough 64.5 63.1 57.9 64.5 76.3 34.0 47.9 57.0
Fox Meadow 19.6 28.9 51.4 6.9 100.0 21.6 37.4
Golf Terrace Heights 65.6 27.5 7.2 68.3 61.3 35.1 100.0 28.7
Grandview 80.0 42.0 46.8 59.0 46.5 66.6 37.7 54.0 100.0 44.7 50.4
Highlands 12.5 26.0 35.3 28.4 10.7 100.0 27.8 100.0 31.8
Hilldale 0.0 21.5 100.0 100.0 39.7
Indian Hills 62.8 30.5 56.3 27.6 100.0 18.1 100.0 38.0
Indian Trails 65.8 56.0 71.7 28.6 4.6 13.3 100.0 33.5
Interlachen Park 57.5 6.6 25.8 100.0 100.0 17.6
Lake Cornelia 60.2 34.1 60.6 48.1 33.5 11.3 100.0 100.0 45.2
Lake Edina 90.7 9.2 0.0 62.4 34.6 15.2 100.0 100.0 43.9
Melody Lake 53.4 44.5 30.3 3.1 100.0 23.7 33.7
Minnehaha Woods 56.2 4.4 16.7 34.6 71.5 34.7 100.0 100.0 35.4
Morningside 68.2 15.2 45.1 32.1 2.7 15.4 100.0 100.0 32.3
Normandale Park 10.0 53.5 43.0 31.6 10.0 100.0 24.5 100.0 34.0
Pamela Park 72.0 8.4 59.0 59.2 37.1 28.0 100.0 100.0 35.9
Parklawn 77.2 6.7 61.9 72.8 26.7 100.0 51.6
Parkwood Knolls 66.4 19.7 47.5 59.0 29.5 51.7 3.6 100.0 22.1 100.0 31.7
Pentagon Park 78.0 40.4 60.5 71.3 0.0 100.0 75.2
Presidents 13.8 63.1 56.5 29.5 24.8 100.0 29.1
Promenade 80.2 52.8 63.6 73.8 71.9
Prospect Knolls 57.4 17.1 34.3 52.2 27.4 45.7 0.4 100.0 100.0 29.7
Rolling Green 17.4 21.4 100.0 100.0 27.1
South Cornelia 76.9 58.2 34.3 39.0 30.7 41.0
Southdale 81.2 67.7 59.0 60.7 84.5 49.9 100.0 76.1
Strachauer Park 7.1 55.5 39.7 39.1
Sunny Slope 39.8 68.7 75.0 29.4 100.0 41.0
The Heights 64.0 15.2 74.3 39.2 30.9 45.1 8.6 16.0 100.0 33.3
Todd Park 37.4 12.5 60.9 31.0 39.0 22.8 100.0 100.0 37.2
White Oaks 40.6 44.5 30.3 47.8 100.0 100.0 36.0
Commercial
Developed
Park Golf Course
High Density
Residential Highway
Industrial/
Office Institutional
Institutional -
High
Imperviousness
Low Density
Residential
Medium
Density
Residential
Natural/Park/
Open
Open
Water Other
Very Low
Density
Residential Wetland
Maximum 90.7 67.7 40.4 72.6 71.8 83.0 75.0 84.5 60.4 76.7 34.7 100.0 44.7 27.8 100.0
Minimum 37.4 0.0 0.0 38.6 37.7 52.2 16.7 56.3 21.4 2.7 0.0 100.0 16.0 12.5 100.0
Average 77.6 18.7 5.4 58.7 53.8 71.7 41.7 71.6 31.7 42.6 10.5 100.0 31.3 20.1 100.0
Table 3 - Area (acres) of each land use type within each neighborhood
Commercial
Developed
Park Golf Course
High Density
Residential Highway
Industrial/
Office Institutional
Institutional -
High
Imperviousness
Low Density
Residential
Medium
Density
Residential
Natural/Park/
Open
Open
Water Other
Very Low
Density
Residential Wetland
Total Acres of
Neighborhood
50th and France 18.91 0.97 0.004 0.06 20
Arden Park 8.87 0.003 0.60 4.40 2.48 114.16 1.98 12.47 6.20 151
Birchcrest 25.23 3.95 150.04 2.73 4.76 3.91 191
Braemar Hills 31.69 263.86 28.79 32.89 23.17 134.46 91.91 23.33 4.42 43.16 678
Bredesen Park 2.72 12.57 44.07 40.70 125.31 52.99 104.13 17.25 97.77 497
Brookview Heights 13.80 5.28 144.99 2.56 3.01 2.51 5.88 178
Cahill 64.78 26.48 255.13 0.26 0.03 7.41 4.52 14.58 5.43 379
Centennial Lakes 38.64 13.35 17.48 18.10 10.05 98
Chowen Park 1.26 176.30 4.25 1.33 183
Concord 1.87 3.97 28.21 48.29 192.44 1.15 17.91 1.38 295
Country Club 5.74 1.49 164.24 8.68 180
Countryside 35.12 14.79 42.68 355.49 5.11 1.98 17.09 4.60 4.05 481
Creek Knoll 2.83 33.47 1.05 13.15 4.27 55
Creek Valley 18.36 21.55 97.42 73.60 18.11 0.95 35.28 265
Dewey Hill 16.17 12.15 111.44 60.86 16.00 20.62 1.48 239
Edinborough 8.36 0.39 43.10 16.01 6.79 10.32 12.70 98
Fox Meadow 0.25 132.88 5.58 10.21 27.29 20.89 197
Golf Terrace Heights 5.92 5.57 127.51 18.80 7.81 130.09 10.04 306
Grandview 25.54 0.13 28.21 9.59 23.51 20.87 77.02 1.32 0.40 3.17 190
Highlands 13.72 0.30 12.26 226.84 19.85 16.89 10.81 4.34 305
Hilldale 0.74 59.42 5.42 12.99 79
Indian Hills 28.33 3.83 6.20 166.68 42.64 88.49 0.98 337
Indian Trails 5.69 13.63 14.02 88.52 4.76 22.82 0.18 150
Interlachen Park 1.96 153.62 53.14 13.46 0.88 223
Lake Cornelia 0.12 30.50 0.15 29.27 289.09 14.18 66.43 8.32 438
Lake Edina 2.06 14.78 0.07 11.31 112.77 7.03 25.43 0.58 174
Melody Lake 6.72 0.31 157.97 4.35 8.51 3.00 181
Minnehaha Woods 0.02 1.06 3.69 132.39 1.14 0.67 1.06 1.58 142
Morningside 7.90 12.08 7.79 192.01 10.28 6.02 3.15 0.82 240
Normandale Park 14.07 31.98 0.05 155.17 6.51 0.79 4.75 3.71 217
Pamela Park 4.98 51.10 0.01 3.89 153.82 0.08 4.08 10.94 229
Parklawn 28.42 38.14 58.45 7.95 0.77 4.91 139
Parkwood Knolls 11.34 20.33 4.76 3.68 369.33 18.96 42.00 30.65 118.87 4.30 624
Pentagon Park 86.52 0.26 6.88 49.05 0.18 2.53 145
Presidents 5.11 1.24 2.89 135.05 35.08 0.77 180
Promenade 59.92 8.69 42.49 9.46 121
Prospect Knolls 0.17 19.23 0.56 0.67 174.03 36.74 10.25 4.13 0.51 246
Rolling Green 0.26 126.78 4.65 5.31 137
South Cornelia 8.75 11.01 22.24 167.28 2.71 212
Southdale 248.23 0.15 61.71 12.39 13.86 8.14 3.24 348
Strachauer Park 5.89 7.85 101.19 115
Sunny Slope 0.35 6.11 0.07 55.82 8.01 70
The Heights 0.03 7.83 0.05 4.06 171.32 2.15 6.00 1.35 10.07 203
Todd Park 8.58 15.52 6.41 129.88 14.22 0.33 0.05 16.02 191
White Oaks 0.19 0.05 61.87 1.33 0.23 4.95 69
Commercial
Developed
Park Golf Course
High Density
Residential Highway
Industrial/
Office Institutional
Institutional -
High
Imperviousness
Low Density
Residential
Medium
Density
Residential
Natural/Park/
Open
Open
Water Other
Very Low
Density
Residential Wetland
Maximum 248 51 264 62 44 255 97 21 369 61 104 66 15 119 98
Minimum 0.02 0.003 0.07 0.01 1.24 0.05 0.004 3.95 0.26 0.03 0.08 0.05 1.35 4.42 0.18
Total Acres in Edina 683 315 602 272 404 456 312 52 5416 227 446 396 38 266 309
To: Jessica Wilson and Ross Bintner From: Cory Anderson, Sarah Stratton, and Janna Kieffer Subject: City of Edina Imperviousness Assumptions for Stormwater Modeling Date: October 25, 2016 Page: 8
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4.0 Results
The average imperviousness for each land use type and the range of imperviousness among
neighborhoods is shown in Figure 4. The imperviousness values assumed for the 2003/2011 CWRMPs are
also shown in Figure 4. For some land use types such as Golf Course, Highway, Institutional, and
Institutional – High Imperviousness, the 2016 analysis average value matches very closely with the
2003/2011 CWRMPs assumed value. For others, such as Commercial, High Density Residential, and
Industrial/Office, the 2003/2011 CWRMPs assumed value is substantially higher when compared to the
results of this 2016 analysis. For a few other land use types, such as Natural/Park/Open and Very Low
Density Residential, the 2003/2011 CWRMPs assumptions appear to be low compared to the results of the
2016 analysis.
Low and Medium Density Residential land use types both have wide ranges of imperviousness based on
the 2016 analysis, and the 2003/2011 CWRMPs assumptions are on the high end of these new results.
Open Water and Wetland land use types are 100% in both the 2003/2011 CWRMPs and this 2016 analysis;
those will not change. Land use types Developed Park and Other were not used previously.
The following figures (Figure 5 through Figure 17) show the resulting histograms of each of the land use
types.
Figure 4 - Average and range of imperviousness within all neighborhoods by land use type
0
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100
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To: Jessica Wilson and Ross Bintner From: Cory Anderson, Sarah Stratton, and Janna Kieffer Subject: City of Edina Imperviousness Assumptions for Stormwater Modeling Date: October 25, 2016 Page: 10
P:\Mpls\23 MN\27\23271514 2017 CWRMP SW Modeling Updates\WorkFiles\Imperviousness Analysis\Imperviousness Analysis Summary.docx
Figure 5 Percent impervious histogram of the Commercial land use type
Figure 6 Percent impervious histogram of the Developed Park land use type
0%
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0% - 5%5% - 10%10% - 15%15% - 20%20% - 25%25% - 30%30% - 35%35% - 40%40% - 45%45% - 50%50% - 55%55% - 60%60% - 65%65% - 70%70% - 75%75% - 80%80% - 85%85% - 90%90% - 95%95% - 100%Fraction of Total Land Use AreaNumber of NeighborhoodsPercent Impervious (U of M 2011 data)
Commercial; N = 27 Neighborhoods
Total Commercial area in Edina = 683 acres
2003/2011 CWRMP Total Imp% = 90%
2003/2011 CWRMP Directly Connected Imp% = 80%
0%
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Developed Park; N = 27 Neighborhoods
Total Developed Park area in Edina = 315 acres
2003/2011 CWRMP Total Imp% = N/A
2003/2011 CWRMP Directly Connected Imp% = N/A
To: Jessica Wilson and Ross Bintner From: Cory Anderson, Sarah Stratton, and Janna Kieffer Subject: City of Edina Imperviousness Assumptions for Stormwater Modeling Date: October 25, 2016 Page: 11
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Figure 7 Percent impervious histogram of the Golf Course land use type
Figure 8 Percent impervious histogram of the High Density Residential land use type
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Golf Course; N = 13 Neighborhoods
Total Golf Course area in Edina = 602 acres
2003/2011 CWRMP Total Imp% = 5%
2003/2011 CWRMP Directly Connected Imp% = 2%
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0% - 5%5% - 10%10% - 15%15% - 20%20% - 25%25% - 30%30% - 35%35% - 40%40% - 45%45% - 50%50% - 55%55% - 60%60% - 65%65% - 70%70% - 75%75% - 80%80% - 85%85% - 90%90% - 95%95% - 100%Fraction of Total Land Use AreaNumber of NeighborhoodsPercent Impervious (U of M 2011 data)
High Density Residential; N = 12 Neighborhoods
Total High Density Residential area in Edina = 272 acres
2003/2011 CWRMP Total Imp% = 70%
2003/2011 CWRMP Directly Connected Imp% = 40%
To: Jessica Wilson and Ross Bintner From: Cory Anderson, Sarah Stratton, and Janna Kieffer Subject: City of Edina Imperviousness Assumptions for Stormwater Modeling Date: October 25, 2016 Page: 12
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Figure 9 Percent impervious histogram of the Highway land use type
Figure 10 Percent impervious histogram of the Industrial/Office land use type
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0% - 5%5% - 10%10% - 15%15% - 20%20% - 25%25% - 30%30% - 35%35% - 40%40% - 45%45% - 50%50% - 55%55% - 60%60% - 65%65% - 70%70% - 75%75% - 80%80% - 85%85% - 90%90% - 95%95% - 100%Fraction of Total Land Use AreaNumber of NeighborhoodsPercent Impervious (U of M 2011 data)
Highway; N = 25 Neighborhoods
Total Highway area in Edina = 404 acres
2003/2011 CWRMP Total Imp% = 50%
2003/2011 CWRMP Directly Connected Imp% = 50%
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Industrial/Office; N = 13 Neighborhoods
Total Industrial/Office area in Edina = 456 acres
2003/2011 CWRMP Total Imp% = 90%
2003/2011 CWRMP Directly Connected Imp% = 80%
To: Jessica Wilson and Ross Bintner From: Cory Anderson, Sarah Stratton, and Janna Kieffer Subject: City of Edina Imperviousness Assumptions for Stormwater Modeling Date: October 25, 2016 Page: 13
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Figure 11 Percent impervious histogram of the Institutional land use type
Figure 12 Percent impervious histogram of the Institutional – High Imperviousness land use type
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0% - 5%5% - 10%10% - 15%15% - 20%20% - 25%25% - 30%30% - 35%35% - 40%40% - 45%45% - 50%50% - 55%55% - 60%60% - 65%65% - 70%70% - 75%75% - 80%80% - 85%85% - 90%90% - 95%95% - 100%Fraction of Total Land Use AreaNumber of NeighborhoodsPercent Impervious (U of M 2011 data)
Institutional; N = 20 Neighborhoods
Total Institutional area in Edina = 312 acres
2003/2011 CWRMP Total Imp% = 40%
2003/2011 CWRMP Directly Connected Imp% = 20%
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Institutional -High Imperviousness; N = 5 Neighborhoods
Total Institutional -High Imperviousness area in Edina = 52 acres
2003/2011 CWRMP Total Imp% = 70%
2003/2011 CWRMP Directly Connected Imp% = 50%
To: Jessica Wilson and Ross Bintner From: Cory Anderson, Sarah Stratton, and Janna Kieffer Subject: City of Edina Imperviousness Assumptions for Stormwater Modeling Date: October 25, 2016 Page: 14
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Figure 13 Percent impervious histogram of the Low Density Residential land use type
Figure 14 Percent impervious histogram of the Medium Density Residential land use type
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0% - 5%5% - 10%10% - 15%15% - 20%20% - 25%25% - 30%30% - 35%35% - 40%40% - 45%45% - 50%50% - 55%55% - 60%60% - 65%65% - 70%70% - 75%75% - 80%80% - 85%85% - 90%90% - 95%95% - 100%Fraction of Total Land Use AreaNumber of NeighborhoodsPercent Impervious (U of M 2011 data)
Low Density Residential; N = 41 Neighborhoods
Total Low Density Residential area in Edina = 5416 acres
2003/2011 CWRMP Total Imp% = 40%
2003/2011 CWRMP Directly Connected Imp% = 20%
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0% - 5%5% - 10%10% - 15%15% - 20%20% - 25%25% - 30%30% - 35%35% - 40%40% - 45%45% - 50%50% - 55%55% - 60%60% - 65%65% - 70%70% - 75%75% - 80%80% - 85%85% - 90%90% - 95%95% - 100%Fraction of Total Land Use AreaNumber of NeighborhoodsPercent Impervious (U of M 2011 data)
Medium Density Residential; N = 17 Neighborhoods
Total Medium Density Residential area in Edina = 227 acres
2003/2011 CWRMP Total Imp% = 55%
2003/2011 CWRMP Directly Connected Imp% = 30%
To: Jessica Wilson and Ross Bintner From: Cory Anderson, Sarah Stratton, and Janna Kieffer Subject: City of Edina Imperviousness Assumptions for Stormwater Modeling Date: October 25, 2016 Page: 15
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Figure 15 Percent impervious histogram of the Natural/Park/Open land use type
Figure 16 Percent impervious histogram of the Other land use type
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0% - 5%5% - 10%10% - 15%15% - 20%20% - 25%25% - 30%30% - 35%35% - 40%40% - 45%45% - 50%50% - 55%55% - 60%60% - 65%65% - 70%70% - 75%75% - 80%80% - 85%85% - 90%90% - 95%95% - 100%Fraction of Total Land Use AreaNumber of NeighborhoodsPercent Impervious (U of M 2011 data)
Natural/Park/Open; N = 29 Neighborhoods
Total Natural/Park/Open area in Edina = 446 acres
2003/2011 CWRMP Total Imp% = 2%
2003/2011 CWRMP Directly Connected Imp% = 0%
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0% - 5%5% - 10%10% - 15%15% - 20%20% - 25%25% - 30%30% - 35%35% - 40%40% - 45%45% - 50%50% - 55%55% - 60%60% - 65%65% - 70%70% - 75%75% - 80%80% - 85%85% - 90%90% - 95%95% - 100%Fraction of Total Land Use AreaNumber of NeighborhoodsPercent Impervious (U of M 2011 data)
Other; N = 8 Neighborhoods
Total Other area in Edina = 38 acres
2003/2011 CWRMP Total Imp% = N/A
2003/2011 CWRMP Directly Connected Imp% = N/A
To: Jessica Wilson and Ross Bintner From: Cory Anderson, Sarah Stratton, and Janna Kieffer Subject: City of Edina Imperviousness Assumptions for Stormwater Modeling Date: October 25, 2016 Page: 16
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Figure 17 Percent impervious histogram of the Very Low Density Residential land use type
Table 4 shows the fraction of the area throughout the city in which the imperviousness from this 2016
analysis is below the assumptions used for the 2003/2011 CWRMPs. In other words, high numbers in
Table 4 suggest that the previously used assumptions are conservative with respect to runoff volume
because they may be overestimating the imperviousness of the land use type in some areas within Edina.
Percentages in Table 4 around 40% to 50% suggest that imperviousness is underestimated for about half
the area, and therefore, overestimated for the other half of the area. Low percentages in Table 4 (e.g., Very
Low Density Residential) suggest that the previous assumptions in the 2003/2011 CWRMPs for associated
land use types may be too low, and consideration should be given for increasing those imperviousness
values.
Table 4 Percent of total area of Edina where new average imperviousness value is below 2003/2011 CWRMP values
Land Use Type
Percent of Area below 2003/2011
CWRMP Imperviousness value
Commercial ~100%
Developed Park Not previously used
Golf Course ~44%
High Density Residential ~100%
Highway ~41%
Industrial/Office ~100%
Institutional ~60%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0
0.5
1
1.5
2
2.5
0% - 5%5% - 10%10% - 15%15% - 20%20% - 25%25% - 30%30% - 35%35% - 40%40% - 45%45% - 50%50% - 55%55% - 60%60% - 65%65% - 70%70% - 75%75% - 80%80% - 85%85% - 90%90% - 95%95% - 100%Fraction of Total Land Use AreaNumber of NeighborhoodsPercent Impervious (U of M 2011 data)
Very Low Density Residential; N = 6 Neighborhoods
Total Very Low Density Residential area in Edina = 266 acres
2003/2011 CWRMP Total Imp% = 12%
2003/2011 CWRMP Directly Connected Imp% = 8%
To: Jessica Wilson and Ross Bintner From: Cory Anderson, Sarah Stratton, and Janna Kieffer Subject: City of Edina Imperviousness Assumptions for Stormwater Modeling Date: October 25, 2016 Page: 17
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Land Use Type
Percent of Area below 2003/2011
CWRMP Imperviousness value
Institutional - High Imperviousness ~60%
Low Density Residential ~100%
Medium Density Residential ~98%
Natural/Park/Open < 18%
Open Water ~100%
Other Not previously used
Very Low Density Residential < 10%
Wetland ~100%
A discussion of the results for four different land use types is presented here to provide guidance for
interpreting the results.
• Open Water: This land use type, by definition is 100% impervious. Therefore, the imperviousness
values of this 2016 analysis match the 2003/2011 CWRMPs and do not need to be adjusted.
• Commercial: There are 27 neighborhoods that contain the Commercial land use type. The total
area of Commercial land use is about 680 acres, with nearly 250 acres of Commercial land use
falling within the Southdale neighborhood. There are five neighborhoods with imperviousness
less than 60%, and there is one neighborhood with imperviousness greater than 90%. However,
those extremes comprise only about 13 acres of the 680 total acres of Commercial land use. Close
to 50% of the area of Commercial land use is less than 80% impervious, and about 90% of the
Commercial land use area is below 85% impervious. Finally, essentially all of the Commercial land
use area is less than 90% impervious. Therefore, the assumption of 90% impervious used in the
2003/2011 CWRMPs for Commercial land use may be overestimated. Alternatively, 90%
impervious can be thought of as a conservative assumption with respect to runoff volume.
• Institutional: There are 20 neighborhoods that contain the Institutional land use type. The total
area of Institutional land use is about 310 acres, with nearly 190 acres of Institutional land use
within the Concord, Countryside, and Creek Valley neighborhoods. There is one neighborhood
with imperviousness less than 20%, and there are two neighborhoods with imperviousness
greater than 70%. However, those extremes comprise only about 13 acres of the 310 total acres of
Institutional land use. Roughly 60% of the area of Institutional land use is less than 40%
impervious. Therefore, the assumption of 40% impervious used in the 2003/2011 CWRMPs for
Institutional land use is right in the middle of the imperviousness results of the 2016 analysis.
• Very Low Density Residential: There are six neighborhoods that contain the Very Low Density
Residential land use type. The total area of Very Low Density Residential land use is almost 270
acres, with about 230 acres of Very Low Density Residential land use within the Indian Hills, Indian
Trails, and Parkwood Knolls neighborhoods. The three neighborhoods between 15% and 25%
impervious make up about 85% of the Very Low Density Residential area. Close to 50% of the
total area of Very Low Density Residential land use is less than about 20% impervious, and about
To: Jessica Wilson and Ross Bintner From: Cory Anderson, Sarah Stratton, and Janna Kieffer Subject: City of Edina Imperviousness Assumptions for Stormwater Modeling Date: October 25, 2016 Page: 18
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95% of the Very Low Density Residential land use area is below 25% impervious. There are no
neighborhoods with imperviousness less than 12%. Therefore, the assumption of 12% impervious
used in the 2003/2011 CWRMPs for Very Low Density Residential land use may be
underestimated which is consistent with the assumption that increasing development has
impacted imperviousness. However, the increase in imperviousness does not appear to be
significant enough to make the imperviousness values for this land use type consistent with the
imperviousness values for the Low Density Residential land use type. There is still a difference in
the imperviousness values of these two land use types.
5.0 Conversion from Total Imperviousness to Directly Connected Imperviousness
Sections 1.0 – 4.0 of this memo have discussed total imperviousness for each land use type. However,
what is important for hydrologic modeling is the directly connected imperviousness which is similar to
effective impervious area. A July 2015 report on effective impervious area suggests that these terms are
slightly different (reference [4]). The report describes how the effective impervious area is usually less,
about 80% to 90% of the directly connected impervious area. Two possible approaches for converting
from total to directly connected imperviousness are listed below.
First, the simplest approach for converting the total imperviousness described in Section 4.0 to directly
connected imperviousness is to simply use the same conversion ratios (ratio of directly connected to total)
used in the 2003/2011CWRMPs as shown in Table 1 and then apply some engineering judgment to the
results. For example, if the total imperviousness of Commercial land use was changed from 90% to 80%,
and the same ratio was then used to convert total imperviousness to directly connected imperviousness
(0.889), the result for Commercial land use would be 71%, or potentially rounded to 70% directly
connected imperviousness.
Second, an alternative method is proposed in a report by John Gulliver and others at the University of
Minnesota (reference [4]). The proposed method of determining the directly connected impervious area
fraction in ungauged urban watersheds is summarized in the following steps:
• Extract total imperviousness from land use and the hydrologic soil groups from the SSURGO data
set and calculate the weighted average saturated hydraulic conductivity of the soil.
• Estimate the actual curve number of the watershed as a function of total imperviousness and the
saturated hydraulic conductivity.
• Determine the fraction of effective impervious area as a function of the actual curve number.
• Assume that the effective impervious area is roughly 85% of the directly connected impervious
area, and scale up the values to account for this difference with a factor of 1.176 (or 0.85-1).
To: Jessica Wilson and Ross Bintner From: Cory Anderson, Sarah Stratton, and Janna Kieffer Subject: City of Edina Imperviousness Assumptions for Stormwater Modeling Date: October 25, 2016 Page: 19
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The approach suggested in the paper by Gulliver could be followed to determine the directly connected
impervious area for the purposes of the 2017 XP-SWMM modeling. However, there are some concerns
about the applicability of the paper to this modeling. First, much of the method relies on regression
equations that do not account for the spread in the data and the error bars, which appear to be relatively
significant. Second, the suggested approach is likely more useful for simpler hydrologic modeling
methods, such as the rational method. In XP-SWMM, hydrologic factors such as depression storage and
infiltration parameters based on soil type are treated as independent inputs. In the method described in
the paper, it appears that these other hydrologic factors are implicitly included in the estimated value of
effective impervious area. Therefore, we do not recommend using this approach to estimate
imperviousness for the 2017 XP-SWMM modeling.
6.0 Consequences and Risks
Understanding the consequences and risks of over- or under-estimating the imperviousness can help
determine an appropriate value for each land use type in the city of Edina. Figure 18 is a simple diagram
to help illustrate this decision making process. Currently, there is a range of imperviousness throughout
the city, and it varies by land use type (residential versus commercial versus park space, etc.). Accounting
for the trend that the city is becoming more impervious, it is reasonable to expect that in the near future,
the imperviousness will be higher than what it is today. However, with policies and regulations being put
in place to limit the increase in imperviousness and to offset any additional imperviousness being created
(e.g., using stormwater BMPs), the long term outlook is much more uncertain.
If the current imperviousness is used in the modeling for the 2017 CWRMP, then the risk is that it will
likely be outdated and too low in the near future. The consequence is that flooding of structures may
increase, stormwater infrastructure may be undersized, and the level of service provided by the City will
decrease creating frustration within the community.
If the current trend of increasing imperviousness is extended into the future, the risk is that the
imperviousness will be overestimated. The consequence is that more locations may be identified as flood
risk locations and may require expensive updates to infrastructure. The flooding of structures may
decrease because the stormwater infrastructure will generally be oversized. The level of service will
increase, but it will come at a significant and potentially unnecessary cost to the community.
Finally, choosing an imperviousness value that is higher than the current average, but one that captures
the current trend of increasing imperviousness without extending it too far into the future may be the
best selection. Risk of over- or under-estimating the imperviousness still exists, but the consequences may
be less because the error in the selected value will likely be less. Therefore, for each land use type,
selecting a value that is higher than 80% to 90% of the total area of that land use type is expected to be a
reasonably protective, yet still accurate value.
To: Jessica Wilson and Ross Bintner From: Cory Anderson, Sarah Stratton, and Janna Kieffer Subject: City of Edina Imperviousness Assumptions for Stormwater Modeling Date: October 25, 2016 Page: 20
P:\Mpls\23 MN\27\23271514 2017 CWRMP SW Modeling Updates\WorkFiles\Imperviousness Analysis\Imperviousness Analysis Summary.docx
Figure 18 Total imperviousness estimation; consequences and risks diagram
current
status
likely
future
???
current
trend
low total imperviousness high
Consequences and risks
•Flood risk
•Infrastructure size
•Level of service current range of
imperviousness
likely near future range of
imperviousness
To: Jessica Wilson and Ross Bintner From: Cory Anderson, Sarah Stratton, and Janna Kieffer Subject: City of Edina Imperviousness Assumptions for Stormwater Modeling Date: October 25, 2016 Page: 21
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7.0 Conclusions
An analysis of the imperviousness throughout the city of Edina for multiple land use types was completed
using the most recent available imperviousness data set. For some of the land use types, the
imperviousness has historically been over- or under-estimated, and for others, the current value has been
estimated very well. The values for total imperviousness were updated based on the 2016 imperviousness
analysis and consideration of the risks and consequences presented in the previous section.
Recommended total imperviousness values for stormwater modeling associated with the 2017 CWRMP
are listed in Table 5. Additionally, after discussion with City staff concerning the trends in residential
development throughout the city, recommendations for updates to the directly connected
imperviousness are also presented in Table 5. For most of the land use types, the recommended total
imperviousness for the 2017 CWRMP is at or above the average imperviousness of the 2016 analysis. The
two exceptions to this are the “Natural/Park/Open” and “Other” (essentially a railroad corridor) land use
types. In both cases, these land use polygons tend to be small and narrow and the analysis was highly
affected by the adjacent land use polygons which were often Industrial/Office or Commercial and were
raising the average imperviousness. A closer look at the aerial imagery within the small and narrow land
use polygons representing Natural/Park/Open and Other justifies using lower numbers for the total
imperviousness.
Table 5 Summary of imperviousness values and recommendation for impervious assumptions for the 2017 CWRMP update
Land Use Type
Total
Area
(acres)
Imperviousness Value Assumptions (%)
2003/2011
CWRMPs
2016 Imperviousness
Analysis
Recommended for
2017 CWRMP
Total Directly
Connected
Total
(Range)
Total
(Average)
Total Directly
Connected
Commercial 683 90% 80% 37% - 91% 78% 85% 80%
Developed Park 315 not previously used 0% - 68% 19% 30% 20%
Golf Course 602 5% 2% 0% - 40% 5% 5% 2%
High Density Residential 272 70% 40% 39% - 73% 59% 65% 50%
Highway 404 50% 50% 38% - 72% 54% 65% 65%
Industrial/Office 456 90% 80% 52% - 83% 72% 75% 75%
Institutional 312 40% 20% 17% - 75% 42% 60% 30%
Institutional - High
Imperviousness
52 70% 50% 56% - 85% 72% 80% 70%
Low Density Residential 5,416 40% 20% 21% - 60% 32% 40% 25%
Medium Density
Residential
227 55% 30% 3% - 77% 43% 50% 40%
Natural/Park/Open 446 2% 0% 0% - 35% 11% 2% 0%
Open Water 396 100% 100% N/A 100% 100% 100%
Other 38 not previously used 16% - 45% 32% 20% 20%
Very Low Density
Residential
266 12% 8% 13% - 29% 20% 25% 15%
Wetland 309 100% 100% N/A 100% 100% 100%
To: Jessica Wilson and Ross Bintner From: Cory Anderson, Sarah Stratton, and Janna Kieffer Subject: City of Edina Imperviousness Assumptions for Stormwater Modeling Date: October 25, 2016 Page: 22
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8.0 References
[1] Remote Sensing and Geospatial Analysis Laboratory, University of Minnesota, Marvin Bauer, "Twin
Cities Metropolitan Area Land Cover Classification and Impervious Surface Area by Landsat Remote
Sensing: 2011 Update," St. Paul, MN, 2011.
[2] City of Edina, "Neighborhood Layer," Edina, MN, 2016.
[3] City of Edina, "Land Use Data," 2000.
[4] J. S. Gulliver, A. Ebrahimian and B. N. Wilson, "Determination of Effective Impervious Area in Urban
Watersheds," Minnesota Department of Transportation, St. Paul, Minnesota, July, 2015.
Appendix B
Summary of Nine Mile Creek and Minnehaha Creek Modeling Approach
Barr Engineering Co. 4300 MarketPointe Drive, Suite 200, Minneapolis, MN 55435 952.832.2600 www.barr.com
Technical Memorandum
To: Jessica Vanderwerff Wilson and Ross Bintner From: Cory Anderson and Sarah Stratton Subject: History of Nine Mile Creek and Minnehaha Creek Model Development and
Incorporation of Tailwater Conditions into the Edina XP-SWMM models Date: September 22, 2017 Project: 23/27-1514.00 c: Janna Kieffer
The City of Edina updated its Comprehensive Water Resources Management Plan (CWRMP) in 2017. As
part of this update, 10 previously developed XP-SWMM models of the city were updated. The storm
sewer data (City’s GIS layer provided in June 2016), soils information (2012 Natural Resources
Conservation Service Soil Survey Geographic (SSURGO) data), imperviousness (reflecting 2011 University
of Minnesota imperviousness raster data), and watershed divides and detention storage (2011 Minnesota
DNR LiDAR) were all updated in the XP-SWMM models to reflect newer data.
In addition to updating the data in the 10 XP-SWMM models that cover the city, the models were merged
together so that there is now one model covering the areas of Edina draining to Nine Mile Creek, and one
model covering the areas of Edina draining to Minnehaha Creek. The details of the model construction are
described in the 2017 CWRMP.
This memo provides some historical context for how Nine Mile Creek and Minnehaha Creek were
previously modeled and also describes the methodology used to account for each creek within the City of
Edina XP-SWMM modeling updated for the 2017 CWRMP.
1.0 Nine Mile Creek Methodology
An XP-SWMM model of Nine Mile Creek was developed by Barr in 2005 for the Nine Mile Creek
Watershed District to determine the 1%-annual-chance flood (100-yr flood) elevations along the creek.
Due to the large size of the Nine Mile Creek watershed (~50 square miles) and the detail of the modeling
to be done (e.g. 3065 subwatersheds), the study area was split into 15 different “city” models and one
creek model.
Watershed drainage divides (subwatersheds) were delineated using 2-foot topography data provided by
each of the cities that the creek flows through, with the exception of the South Fork of Nine Mile Creek
that passes through the City of Eden Prairie. The City of Eden Prairie did not have 2-foot topography data
at the time the model was developed, therefore watersheds delineated for that portion of the model are
less detailed. For the entire stretch of the creek itself, surveyed cross-sections were used to estimate the
To: Jessica Vanderwerff Wilson and Ross Bintner From: Cory Anderson and Sarah Stratton Subject: History of Nine Mile Creek and Minnehaha Creek Model Development and Incorporation of Tailwater
Conditions into the Edina XP-SWMM models Date: September 22, 2017 Page: 2
backwater effects of the bridges and culverts and to reflect variations in the stream valley topography. All
of the cross-sections within the different reaches of Nine Mile Creek were surveyed within the channel
banks and extended on the floodplain using 2-foot topography to define the changes in slopes for the
large overbank areas. In the City of Eden Prairie where 2-foot topography data was unavailable, full cross-
sections (stream channel and overbanks) for that stretch of the creek were surveyed. Road crossing
information was obtained primarily through survey; plan sheets were reviewed as available. Loss
coefficients for bridges, other channel obstructions, channel roughness, and overbank roughness
(Manning’s “n”) were estimated by field inspection and photographs. Lakes and large wetland areas that
have a consistent water surface elevation along Nine Mile Creek were modeled as storage areas in the XP-
SWMM model.
The peak flood flow that was predicted by the XP-SWMM model was compared to the expected peak flow
using the National Flood Frequency Program (NFF) regional regression analysis on Nine Mile Creek as a
QA/QC measure. Flows were compared on the north fork of Nine Mile Creek at Highway 169, Highway
62, and Interstate 494. The peak flows calculated for the three different locations using the regional
regression were all within 11% of the peak hydraulically routed flow calculated using XP-SWMM. Since
the standard error for the 1%-annual-chance recurrence interval using NFF is 54%, the flows calculated by
XP-SWMM are reasonable.
Two other precipitation events were used to calibrate and validate the model. The calibration event was
in April 2004, and the amount of precipitation varied throughout the watershed. Therefore, average
precipitation amounts were calculated by major watershed and were used in the appropriate models.
Flows for the calibration event were compared to monitored flows at four different locations throughout
the watershed—one location on the North Fork of the Creek, one location on the South Fork of the Creek,
and two locations on the Lower Valley portion of the Creek (below the confluence of the North Fork and
South Fork).
The validation event was in June 2003 and the amount of precipitation was also varied throughout the
watershed. Therefore, average precipitation amounts were calculated by major watershed and were used
in the appropriate models. The water surface elevation for the validation event was also compared to a
monitored water surface elevation at Normandale Lake (the confluence of the North Fork and South Fork
of Nine Mile Creek).
Simulating storm events using 15 different city models and one creek model required an iterative process
to account for overflows and tailwater conditions between models. Each city model had numerous points
of outflow into the creek. XP-SWMM creates a hydrograph at each outflow point and each outflow point
from the city model was assigned an inflow point in the creek model. Since some of the inflow points
had several outflow points attached to it (not a 1:1 ratio) it was necessary to sum the hydrographs created
To: Jessica Vanderwerff Wilson and Ross Bintner From: Cory Anderson and Sarah Stratton Subject: History of Nine Mile Creek and Minnehaha Creek Model Development and Incorporation of Tailwater
Conditions into the Edina XP-SWMM models Date: September 22, 2017 Page: 3
by XP-SWMM. An Excel macro was used to sum hydrographs so there would be one hydrograph for each
inflow point into the creek. The hydrographs were input into the creek model as text files.
In some of the city models, there was overflow out of the model into a different city model. These points
were treated similar to the outflow into the creek. A hydrograph was created by XP-SWMM and then
imported into the downstream city model. In cases where more than one overflow went into a single
downstream system, the hydrographs were summed.
For larger events (100-yr and 500-yr) it was necessary to consider the tailwater elevation in the creek.
When the creek model was run XP-SWMM saved the elevation versus time data for each node that had
inflow from a city model. These elevations were imported back into the city models at locations where
there was outflow to the creek. This replaced the original downstream condition (free outfall) with the
actual downstream elevation in the creek at that outlet. The city models then needed to be re-run to
determine new hydrographs. The hydrographs were again summed where necessary and imported into
the creek model. The creek model was re-run, and a new tail-water file was created. The process was
repeated until the elevation in the creek stabilized.
The model of Nine Mile Creek (including all of the associated city models) was updated by Barr in 2014 to
reflect Atlas 14 precipitation depths.
Faster computing times and newer versions of XP-SWMM have now made it more feasible to combine the
city models and creek model into one model.
Prior to combining the models (for this 2017 CWRMP update), the modeling connection between Nine
Mile Creek and the XP-SWMM models of the city was time-consuming and required iterations between
model runs to properly determine boundary conditions. Therefore, to remove the iteration process that
was necessary, the nodes and links of the Nine Mile Creek model were merged directly into the city
model. This created one complete model of the areas of Edina draining to Nine Mile Creek including the
creek itself, extending from Hopkins northwest of Edina down through Bloomington southeast of Edina.
However, the input data associated with the creek nodes and links was not updated with any new data.
Because the creek nodes and links were included in the overall city model contributing to Nine Mile Creek,
the modeled storm events could be routed through all of the runoff nodes in the model to determine the
runoff hydrographs, and through the hydraulic layer nodes and links to route the storm events through
both the creek and the city. The iteration process is no longer necessary to determine flood levels in the
creek or in the nodes adjacent to the city that might be affected by creek tailwater levels.
To: Jessica Vanderwerff Wilson and Ross Bintner From: Cory Anderson and Sarah Stratton Subject: History of Nine Mile Creek and Minnehaha Creek Model Development and Incorporation of Tailwater
Conditions into the Edina XP-SWMM models Date: September 22, 2017 Page: 4
2.0 Minnehaha Creek Methodology
The previous XP-SWMM models developed for the city of Edina did not account for tailwater conditions
from Minnehaha Creek. Previously, any areas of Edina that drained to Minnehaha Creek through storm
sewer assumed that those areas could freely drain to the creek. This assumption may reflect actual
conditions for some areas along the creek and/or for some shorter duration storm events, but may not be
true for other lower-lying areas adjacent to the creek or for longer duration storm events.
The XP-SWMM models of Minnehaha Creek and its upstream contributing area were developed by EOR
for the Minnehaha Creek Watershed District (MCWD) in 2003. The methodology used for developing
these models is provided on MCWD’s website (Hydrologic, Hydraulic, and Pollutant Loading Study, 2003).
For this 2017 CWRMP modeling effort, the Minnehaha Creek XP-SWMM models were provided by Wenck
(MCWD’s engineer) in August 2016. Wenck provided two XP-SWMM models – one for the Upper
Watershed of Minnehaha Creek (the upper watershed down to Lake Minnetonka at Gray’s Bay Dam) and
one for the stretch of Minnehaha Creek below Lake Minnetonka at Gray’s Bay Dam). The Upper
Watershed model determines the outflow from Lake Minnetonka to Minnehaha Creek.
The models provided by Wenck used TP-40 1%-annual-chance precipitation event inputs. Barr then
updated the two Minnehaha Creek models with the Atlas 14 1%-annual-chance precipitation event to be
consistent with the Atlas 14 1%-annual-chance precipitation event depths and nested distribution used
for the other Edina XP-SWMM models. The two Minnehaha Creek models provided by Wenck were also
re-run for other events (Atlas 14 10%-annual-chance precipitation and 1%-annual-chance snowmelt). No
other model changes were made.
The separation of the models has been maintained (i.e., the Minnehaha Creek model provided by Wenck
is not combined with the City of Edina model). Therefore, to account for Minnehaha Creek tailwater
conditions, user-defined stage hydrographs were extracted from the Minnehaha Creek model for each
modeled event and were included as downstream boundary conditions at all model node locations where
Edina subwatersheds drain to Minnehaha Creek.
Appendix C
Legacy Flood Protection Projects
Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-1
2011 CWRMP
Plan Section Title 2011 CWRMP Text Status notes
Nine Mile Creek-North
5.3.1.1 Hawkes Drive (HL_2)
Hawkes Drive is a cul-de-sac on the east side of Hawkes Lake. A low area exists along
this street, south of the intersection with Hawkes Terrace. Two catch basins are located
in this low area, which connect to the 12-inch storm sewer system that discharges into
Hawkes Lake. During the 100-year frequency storm event, the 12-inch storm sewer
does not provide enough capacity and street flooding occurs in the low area along
Hawkes Drive to an elevation of 902.3 MSL. Based on the 2-foot topographic
information, flood waters from the street will flow west via overland flow toward the
Lake at an elevation above 902 MSL. To ensure that the flooding does not encroach
upon the homes at 5713 and 5717 Hawkes Drive, a positive overland flow swale should
be constructed between the homes.
Addressed in 2012 Street reconstruction with 4 inlets and a 12” RCP to 18” HDPE pipe burst improvement.
5.3.1.2 5711 & 5717 Grove Street
(HL_18)
A depression area exists in the backyards of 5711 and 5717 Grove Street. Stormwater
from a 3-acre subwatershed (HL_18) drains to this depression area. A 21-inch storm
sewer system runs through the backyard area and flows northward to Grove Street. A
beehive structure is located at the low point in the backyard area to collect the
stormwater. During the 100-year frequency storm event, the 21-inch system does not
provide sufficient capacity, and water pools in the backyard depression area. The
predicted 100-year frequency flood elevation is 904.4 MSL. This flood elevation is
slightly higher than the low house elevations for 5711 and 5717 Grove Street, which
were surveyed at 903.6 MSL and 903.5 MSL, respectively. To decrease the 100-year
frequency flood elevation in the backyard depression area and provide a 100-year level
of protection, it is recommended that the 21-inch pipe system spanning from the
backyard depression area to Grove Street be upgraded to 24-inch pipes. This change
would decrease the calculated 100-year flood elevation to 903.5 MSL without causing
negative effects upstream or downstream.
This flood issue was evaluated as part of the 2015 street reconstruction project.
Pipes were upsized in 2015 Countryside H Neighborhood Roadway Improvement (ENG 15-4). Improvement
included a 21”RCP to 24” pipe burst and upsize to 28” RCP arch pipe.
Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-2
2011 CWRMP
Plan Section Title 2011 CWRMP Text Status notes
5.3.1.3
5516 & 5520 Dundee
Road (HL_25)
West of 5516 and 5520 Dundee Road, a depression area is located that collects
stormwater during precipitation events. Due to past flooding problems, a lift station
was installed in this backyard area to pump stormwater east to Dundee Road, where
the stormwater flows southward down Dundee Road until it reaches the gravity storm
sewer system. The current lift station has a pumping capacity of approximately 150
gpm. For the XP-SWMM analysis, the available storage volume in the backyard
depression area and the elevation at which the pump turns on/off were based on the
2-foot topographic data. Based on this information, the calculated 100-year frequency
flood elevation is 897.2 MSL. This elevation is higher than the surveyed low house
elevations for 5516 and 5520 Dundee Road, 894.26 MSL and 895.67 MSL, respectively.
Comparison of the field survey data with the 2-foot topographic data leads to
uncertainty of the accuracy of the topographic information in this area. It is
recommended that a detailed field survey be performed to determine the accuracy of
the topographic data and storage assumptions in this area. If it is determined that the
topographic data used was accurate, it is recommended that additional pump capacity
be added to the lift station to prevent the structures at 5516 and 5520 Dundee Road
from incurring flood damage. Another option to alleviate flooding in the backyard
depression area is to create a positive overland flow swale toward the pond that is
located approximately 400 feet north of the 5516 Dundee Road property. Based on
the 2-foot topographic data, the overland flow swale would begin near the property
line between 5516 and 5512 Dundee Road.
There have not been any studies or improvements completed for this area. Considered for study as part of
STS-406, but dropped due to cost.
Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-3
2011 CWRMP
Plan Section Title 2011 CWRMP Text Status notes
5.3.1.4 505, 509, & 513 Tyler
Court (ML_19)
An inundation area is located east of the homes along Tyler Court, south of Maloney
Avenue and west of Arthur Street. Stormwater runoff from a drainage area of
approximately 29 acres discharges into this dry basin. A 24-inch storm sewer system
drains this area. The 24-inch system flows south and west to Arthur Street, then south
to the intersection of Arthur Street and Waterman Avenue. At this intersection, the
pipe flowing east toward Mirror Lakes is reduced to an 18-inch pipe. Due to the
restricted pipe capacity at Arthur Street and Waterman Avenue, flow in the system
draining the dry basin reverses during intense rainfall events such as the 100-year
frequency event, and the basin is inundated. During the 100-year frequency storm
event, the dry basin reaches a flood elevation of 936.6 MSL. This flood elevation is
considerably higher than the low house elevations at 505, 509, and 513 Tyler Court,
surveyed at 932.9 MSL, 933.1 MSL, and 934.07 MSL, respectively. To alleviate a portion
of the flooding problem, it is recommended that the 18-inch pipe flowing east from
the Arthur Street and Waterman Avenue intersection be upgraded to a larger pipe. By
upgrading to a 24-inch pipe, runoff from Waterman Avenue and Arthur Street will not
back up into the dry pond and the 100-year frequency flood elevation of the pond
would decrease to 934.7 MSL. To further alleviate the flooding problem, it will be
necessary to perform a more detailed analysis on the system that drains the backyard
inundation area.
No studies or improvements completed to date. Included as a current flood protection project in Section
5.3.1.1.
5.3.1.5 6009 Leslee Lane (MD_22)
A backyard depression area exists between the properties on the south side of Leslee
Lane and north side of Kaymar Drive. The depression area collects stormwater from a
drainage area of approximately 6.4 acres. A 15-inch storm sewer system extends
southward into the backyard depression area from Leslie Lane, collecting stormwater
from the low area, and continues to the west toward Jeffrey Lane. This system
eventually connects with the Blake Road system at the intersection of Blake Road and
Kaymar Drive. During the 100-year frequency storm event, flow is restricted in the
15-inch system and water pools in the backyard depression area behind 6009 Leslee
Lane. The predicted 100-year frequency flood elevation in this area is 916.7 MSL.
Based on the 2-foot topographic data, it appears that this flood elevation will impact
the structure at 6009 Leslee Lane. To alleviate the backyard flooding and prevent
property damage at 6009 Leslie Lane, it is recommended that the 15-inch pipe draining
the backyard depression and the downstream 18-inch pipe be upgraded to 24-inch
diameter pipes. This would result in a predicted 100-year frequency flood elevation of
915.8 in the backyard depression area.
There have not been any studies or improvement projects completed for this area. Included as a current flood
protection project in Section 5.3.1.2.
Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-4
2011 CWRMP
Plan Section Title 2011 CWRMP Text Status notes
5.3.1.6. 5316 Schaefer Road
(MD_28)
A small, 0.5-acre stormwater detention pond is located just northwest of the
intersection of Schaefer Road and Parkwood Road. The outlet to the pond is a 12-inch
system that drains south to Parkwood Road and then east toward Blake Road. During
the peak of the 100-year frequency storm, the flow in the 12-inch system is reversed
and all the stormwater from subwatershed MD_28 and MD_48 flows into the pond. As
the water elevation of the pond increases to an elevation of approximately 938 MSL
during storm events, water will overtop Schaefer Road and flow east through a
drainage swale that leads to another stormwater detention basin. However, before the
flood water from the pond overtops the road, the pond will extend well into the yard
of 5316 Schaefer Road, encroaching upon the structure. The 100-year frequency flood
level of the pond is 939.0 MSL. Although based on the 2-foot topographic data it
appears that the structure at 5316 Schaefer Road will not be affected by a 100-year
rainfall event, it is recommended that an overflow across the road be maintained or
slightly lowered during any future road improvement projects in this area.
There have not been any studies or improvement projects completed for this area. Included as a current flood
protection project in Section 5.3.1.3.
5.3.1.7
Fountain Wood
Apartments (NMN_90 &
NMN_23)
The NMN_90 subwatershed encompasses an area of approximately 3 acres. The
subwatershed includes the townhomes on Wellesley Place north of Vernon Avenue and
a portion of the Fountain Woods apartment complex. The low spot in the watershed is
located in the southwest corner of the Fountain Woods parking lot, near the parking
entrance/exit for buildings 6650 and 6710. During the 100-year frequency storm
event, stormwater pools in this area, reaching a flood elevation of 876.6 MSL. Field
survey data indicates that this flood elevation will impact the two garage entrances for
buildings 6650 and 6710, both recorded at 872.1 MSL.
The Fountain Woods Apartments drainage system is a privately maintained drainage
system. It is recommended that the owners of the apartment complex be notified of
this potential problem and recommend that they may wish to make modifications to
their system to alleviate potential flooding problems.
There have not been any studies or improvement projects completed for this area.
Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-5
2011 CWRMP
Plan Section Title 2011 CWRMP Text Status notes
Nine Mile Creek-Central
6.3.1.1 6005 & 6009 Crescent
Drive (manhole 457)
Stormwater runoff from subwatershed NMC_110 collects at a low area along Crescent
Drive. Stormwater is collected at two catchbasins located on both sides of the street at
6013 Crescent Drive and flows eastward through an 18-inch storm sewer that connects
with the trunk system that flows south along the SOO Line railroad tracks. During
intense rainstorms, such as the 100-year frequency event, flow through the 18-inch
system is restricted due to high flows entering the larger trunk system from the east.
Due to the restricted flow, water pools in the street along Crescent Drive and
eventually overtops the street and flows eastward between the homes toward a
backyard depression area behind the homes of 6001, 6005, 6009, and 6013 Crescent
Drive. As a result of the overland flow from Crescent Drive, this backyard depression
area becomes inundated. The 100-year frequency flood elevation within this
depression area is 903.0 MSL. This flood elevation is higher than the low house
elevations at 6005 and 6009 Crescent Drive, which were surveyed at 902.2 MSL.
Based on the 2-foot topographic information, it appears that water in the backyard
depression area will drain southward through a ditch along the west side of the
railroad tracks, once it reaches elevation of 902.6 MSL. To alleviate the flooding
potential, it is recommended that a gravity channel be constructed from the
depression area to the ditch along the west side of the railroad tracks at an elevation
lower than the low house elevation of 902.2 MSL. This will allow the depression area to
drain and alleviate flooding at 6005 and 6009 Crescent Drive.
Barr modeled proposed upsizing, but it made very little difference due to high tailwater.
This flood issue was evaluated as part of the 2012 street reconstruction project.
Pipes were upsized in 2012 Countryside Neighborhood Reconstruction (ENG 12-3).
Ponding in the low area along the railroad tracks was reviewed in relation to the Forslin Pond/Birchcrest Pond
analysis conducted prior to the 2017 street reconstruction project. The recommendation stands (but
details/elevations should be re-evaluated, as well as potential downstream impacts).
6.3.1.2
Cherokee Trail & Gleason
Backyard Depression Area
(IP_4)
A backyard depression area exists east of Cherokee Trail, just southwest of the
intersection of Cherokee Trail and Gleason Road. This is currently a land-locked area.
During the 100-year frequency storm event, the flood elevation in this backyard area
reaches 887.8 MSL. This flood elevation is slightly higher than the low house elevation
at 6529 Cherokee Trail, which was surveyed at 887.34 MSL. To alleviate this flooding
problem, it is recommended that a low level outlet be constructed.
There have not been any studies or improvement projects completed for this area.
Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-6
2011 CWRMP
Plan Section Title 2011 CWRMP Text Status notes
6.3.1.3 5339 West 64th Street
(NMC_80)
A backyard depression area exists south of West 64th Street and west of Ridgeview
Drive, just east of the SOO Line railroad tracks. Stormwater from the direct
subwatershed (NMC_80) and overflow from West 64th Street collects in the depression
area, where it enters an 18-inch storm sewer system through an intake structure.
During the 100-year frequency storm event, the backyard depression is inundated with
stormwater and the flood elevation rises to 875.7 MSL. This flood elevation is slightly
higher than the low house elevation at 5339 West 64th Street, surveyed at 875.4 MSL.
To alleviate the flooding problem and provide a 100-year level of protection, it is
recommended that the two 18-inch pipes (pipes 293 and 294) that connect the
backyard depression area to the storm sewer system at the intersection of Ridgeview
Drive and Valley Lane be upgraded to 24-inch pipes. This upgrade would result in a
100-year flood elevation of 875.3 MSL, thus lower than the low house elevation at 5339
West 64th Street.
There have not been any studies or improvement projects completed for this area.
6.3.1.4
Valley View Road &
Hillside Road (NMC_86,
NMC_120)
The streets and homes in the area around the intersection of Valley View Road and
Hillside Road are situated in a low depression area. Storm sewer in this area collects
the stormwater, which flows southward underneath T.H. 62, and eventually connects
with the SOO Line railroad system and discharges into the North Fork of Nine Mile
Creek. During large rain events, such as the 100-year frequency event, the capacity of
the storm sewer system in this area is inadequate, and this area and the nearby ditch
on the north side of T.H. 62 are inundated with stormwater. The 100-year flood
elevation is 862.0 MSL for subwatersheds NMC_86 and NMC_120. Based on the 2-foot
topographic information, these flood elevations will affect several structures in the
area, including 6309 and 6313 Hillside Road and 6328 Valley View Road.
Flooding problems have historically been encountered in this area. Past analysis of the
problem concluded that no solutions to the problem were feasible. However, the flood
elevations in this area can be decreased by upgrading the 24-inch pipe that spans from
Valley View Road to the north ditch of T.H. 62 (pipe 303p) to a 36-inch pipe. This
would decrease the 100-year frequency flood elevations of NMC_86 and NMC_120 to
859.9 MSL and 860.2 MSL, respectively.
This flood issue was evaluated as part of the 2012 Countryside street reconstruction project. Significant
flooding occurred in this area as a result of the August 30-31, 1977 rainfall event (7+ inches of rainfall in a 4
hour time period), and a detailed analysis was completed following the flooding. At that time, they identified
that the best solution would be for the City to consider purchasing the impacted homes, as options for
remedying the problem through infrastructure improvements were extremely limited. Pipe upgrade options
were evaluated in 2012, but made minimal impacts due to the high tailwater conditions in the MnDOT ROW.
This issue was evaluated again in 2016 for ENG 17-5. Upsizing of existing pipes and installation of parallel
pipes were analyzed and deemed infeasible as part of this project. Existing pipe sizes will be maintained with
current reconstruction project.
Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-7
2011 CWRMP
Plan Section Title 2011 CWRMP Text Status notes
6.3.1.5
West 66th Street & Naomi
Drive Area (NMC_71,
NMC_103)
Flooding problems have historically been encountered during intense rainstorms at the
low-lying intersection of West 66th Street and Naomi Drive, as well as the in the
backyard depression area in the rear of the homes on the east side of Naomi Drive.
Stormwater overflow from the 66th Street and Naomi Drive intersection flows into the
adjacent Normandale Park storage area (ball field). The intersection and ball field are
eventually drained by a 33-inch trunk storm sewer system that flows northwest to the
low area along Warren Avenue and eventually westward to the North Fork of Nine Mile
Creek. Based on the XP-SWMM analysis, the 100-year flood elevation at the West
66th Street and Naomi Drive intersection (subwatershed NMC_71) and the adjacent
storage area in Normandale Park reaches 864.8 MSL.
The backyard depression area behind the Naomi Drive homes is drained by a 15-inch
culvert that connects to the 15-inch storm sewer flowing north from Circle Drive Pond.
During periods of intense rainfall, the flow in this system backs up, thus flowing
southward into Circle Drive Pond. A flapgate has been installed on the culvert draining
the backyard depression area to prevent backflow from inundating the area. However,
with the flapgate closed, there is no outlet from this area and the backyard storage
volume is not sufficient to prevent flooding of the structures along Naomi Drive. The
100-year frequency flood elevation for this depression area (subwatershed NMC_103)
is 859.6 MSL. This flood elevation is over 2 feet higher than the low house elevation at
6605 Naomi Drive (857.7 MSL) and slightly less than 2 feet above the low house
elevation at 6609 Naomi Drive (857.9 MSL).
This flooding problem has been analyzed in the past and recommendations to alleviate
the flooding were made, in which case some were implemented. However, the
recommendation to add additional outlet capacity to the backyard depression area, via
a pumped outlet to the Normandale Park storage area or a separate gravity system
flowing west to the North Fork of Nine Mile Creek, has not yet been implemented. To
ensure a 100-year level of protection, it is recommended that additional outlet capacity
be provided for this area. If a pumped outlet is installed to drain the backyard area, it
will be necessary to add additional storage capacity in Normandale Park.
There have not been any studies or improvement projects completed for this area. Included as a current flood
protection project in Section 6.3.1.3.
Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-8
2011 CWRMP
Plan Section Title 2011 CWRMP Text Status notes
6.3.1.6
6712, 6716, 6720
Ridgeview Drive
(NMC_106)
Subwatershed NMC_106 is a 3.3-acre drainage area, characterized by a drainage swale
that extends for nearly 1,200 feet through numerous backyards between Ridgeview
Drive and the SOO Line railroad tracts, flowing southward. The stormwater pools in a
depression area behind 6712, 6716, and 6720 Ridgeview Drive. During large storm
events such as the 100-year frequency rainstorm, this backyard area is inundated. The
100-year frequency flood elevation of this depression area is 845.9 MSL. Based on the
2-foot topographic data, this flood elevation will encroach upon the structures at 6712,
6716, and 6720 Ridgeview Drive. To alleviate this flooding problem, it is recommended
that a gravity storm sewer system be installed that discharges stormwater from the
backyard area to the North Fork of Nine Mile Creek.
There have not been any studies or improvement projects completed for this area. Included as a current flood
protection project in Section 6.3.1.2.
6.3.1.7
6808, 6812, 6816, 6820
Ridgeview Drive
(NMC_107)
A backyard depression area exists at the 6808, 6812, 6816, and 6820 Ridgeview Drive
properties, just east of the SOO Line railroad tracks. The depression area is landlocked
and thus becomes inundated with stormwater during large rainstorm events such as
the 100-year frequency event. Flooding has historically occurred in this area. The
100-year frequency flood elevation in this backyard area is 843.6 MSL. Based on the
2-foot topographic data, this flood elevation will potentially affect structures at 6808,
6812, 6816, and 6820 Ridgeview Drive. To alleviate the flooding conditions in this
backyard depression area, it is recommended that an outlet system be constructed to
flow west and discharge to the floodplain of the North Fork of Nine Mile Creek.
There have not been any studies or improvement projects completed for this area. Included as a current flood
protection project in Section 6.3.1.2.
Lake Cornelia/Lake Edina/Adam’s Hill
7.3.1.1
Swimming Pool Pond
(NC_3)/North Lake
Cornelia (NC_62)
During the design process for the West 66th Street drainage improvements, a detailed
analysis of the storm water system was performed that included the entire Lake
Cornelia drainage area. The system was modeled based on several recommended
improvements, many of which have been since implemented. One recommendation
was to replace the 18-inch RCP pipe and orifice structure between the Swimming Pool
Pond and North Lake Cornelia with a 42-inch equivalent RCP arch pipe. A 20-foot weir
control structure was recommended to be installed at the inlet to this pipe. The
overland flow elevation between these two areas was recommended to be lowered to
863.5 MSL
This flooding area was re-evaluated in 2014-2015. City chose not to move forward because it required the
raising of the 66th Street Causeway as an integral improvement so that risk wasn’t transferred to South
Cornelia.
Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-9
2011 CWRMP
Plan Section Title 2011 CWRMP Text Status notes
7.3.1.2 Hibiscus Avenue (LE_53,
LE_7, LE_10)
Stormwater runoff from a 48.5-acre subwatershed (LE_53) collects at the intersection of
Hibiscus Avenue and West Shore Drive. Along the south side of this intersection, two
catchbasins connect to the 54-inch storm sewer system that discharges into Lake
Edina. Due to the lack of inlet capacity at this intersection, the stormwater that does
not enter the storm sewer system flows west along Hibiscus Avenue toward the low
area near 4708, 4709, and 4713 Hibiscus Avenue. A separate storm sewer system exists
at this low area along Hibiscus, with two catchbasins on the street to allow water into
the system. This system extends upstream, collecting runoff from the backyard
depression area behind 4708 and 4712 Hibiscus Avenue. During the 100-year
frequency event, the low area in the street becomes inundated with stormwater runoff
from the watersheds directly tributary to this system and from the excess runoff
coming from West Shore Drive (subwatershed LE_53). The street flooding causes the
system to back up and reverse flow into the backyard depression area. The 100-year
flood elevation in the street and in the backyard depression area reaches
approximately 831.1 MSL. This flood elevation has the potential to affect structures at
4704, 4708, 4712, 4716 Hibiscus Avenue on the north side and 4705 Hibiscus on the
south side of the street.
To alleviate this problem and ensure a 100-year level of protection is provided, it is
recommended that a positive overflow drainage way be constructed between the low
area of the street and Lake Edina. This will allow the street to drain and prevent the
system from backing up into the backyard depression area. An option of adding
additional inlet capacity to the trunk 54-inch system at the intersection of West Shore
Drive and Hibiscus Avenue was considered; however, the 54-inch storm sewer system
drains nearly 200 acres in addition to the 48.5 acres from subwatershed LE_53 and is
already at full capacity. Adding additional inlet capacity at the intersection of West
Shore Drive and Hibiscus Avenue would cause additional street flooding problems at
upstream locations.
This flood issue was evaluated as part of the 2013 street reconstruction project.
Pipes were upsized as part of the 2013 Lake Edina Neighborhood Roadway Improvements (ENG 13-4).
7.3.1.3
6312, 6316, 6321,
6329 Tingdale Avenue
(NC_11)
A depression area exists along Tingdale Avenue, between West 63rd and West
64th Streets. Two catchbasins are located at the low portion of the street, collecting
stormwater runoff. During the 100-year frequency storm event, the flood elevation at
this location reaches 936.5 MSL. A field survey determined that this flood elevation
would potentially impact egress windows at 6312 and 6316 Tingdale Avenue
(935.24 MSL and 935.20 MSL, respectively).
There have not been any studies or improvement projects completed for this area.
Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-10
2011 CWRMP
Plan Section Title 2011 CWRMP Text Status notes
7.3.1.4
St. Johns/Ashcroft and
West 64th Street (NC_40,
NC_26)
A low area exists directly north of North Lake Cornelia, encompassing portions of
T.H. 62 and West 64th Street between Ashcroft Lane and St. Johns Avenue. The storm
sewer system in this depression area includes two catchbasins on West 64th Street and
several inlets along T.H. 62, including an inlet in the grassed median of T.H. 62. During
extreme storm events such as the 100-year frequency event, this area is inundated with
stormwater runoff, receiving flows from the subwatersheds directly tributary to the
system, as well as flow not captured by the storm sewer system at the intersection of
Ashcroft and West 64th Street (40 cfs) and excess T.H. 62 flows not collected upstream
(160 cfs). Because of the topography and the slope of the highway at this location,
during intense rainstorm events water from the highway will flow north toward the low
area on West 64th Street. The 100-year frequency flood elevation for the highway and
West 64th Street area is 868.1 MSL. At this flood elevation, the entire stretch of West
64th Street between Ashcroft Lane and St. Johns Avenue will be inundated, in addition
to the highway and backyard area just north of West 64th Street, endangering
structures at 6336 St. Johns Avenue and 6329 Ashcroft Lane.
To alleviate this situation, it is recommended that an additional pipe be installed at the
low point in the T.H. 62 median that would drain to North Lake Cornelia. A 24-inch
pipe would decrease the 100-year frequency flood elevation of this depression area to
867.7 MSL and alleviate the flooding concerns for 6336 St. Johns Avenue and 6329
Ashcroft Lane.
This area was evaluated as part of the STS-406 project (2013-2014).
No improvements have been completed for this flood protection project. Will consider the improvement if
HWY 62 is rebuilt.
7.3.1.5
Barrie Road and Heritage
Drive (NC_86, NC_97,
NC_99)
A depression area exists at the intersection of Barrie Road and Heritage Drive and
extends south of the intersection along Barrie Road to West 65th Street. Stormwater
from this area is collected by storm sewer and flows northward, eventually connecting
with the T.H. 62 system. During large storm events, this large depression area is
inundated, causing street and parking lot flooding. The calculated flood elevation for
the 100-year frequency storm event is 879.8 MSL. The low elevations of several
properties in this area were surveyed to determine if this flood level would encroach
upon and potentially cause damage to any structures. The field survey identified only
one property at 6328 Barrie Road with a 878.6 MSL walkout patio elevation, with a low
elevation below the 100-year frequency flood level.
The analysis of this system determined that the flooding problem in this area results
from lack of capacity of the T.H. 62 system. As large stormwater flows enter the T.H. 62
storm sewer system from the highway, flow into that system from Barrie Road and
Heritage Drive is restricted. To alleviate this problem, it will be necessary to re-
examine the capacity of the T.H. 62 storm sewer system.
This area was evaluated as part of the STS-406 project (2013-2014).
No improvements have been completed for this flood protection project.
Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-11
2011 CWRMP
Plan Section Title 2011 CWRMP Text Status notes
7.3.1.6 York Avenue and West
64th Street (NC_88)
A stormwater detention basin is located southeast of the intersection of York Avenue
and West 64th Street. This basin has two pumped outlets, one which discharges to the
west and one that discharges to the east. The outlet to the west is controlled by two
pumps, each with an approximate pumping rate of 500 gpm (1.1 cfs). For the XP-
SWMM model, it was assumed that the first pump on the west side turns on as the
water elevation reaches 863 MSL, with the second pump turning on at water elevation
864 MSL. It was assumed the pumps turn off at water elevation 862 MSL. The pumped
discharge flows west through a forcemain and connects to the gravity system along
Barrie Road. The outlet to the east is also controlled by two 500 gpm pumps. Similar
to the west outlet, it was assumed that the first pump on the east side turns on as the
water elevation reaches 863 MSL, with the second on at elevation 864 MSL and both
pumps off when the water level recedes to 862 MSL. Discharge from this outlet flows
south along Xerxes Avenue, eventually connecting into the West 66th Street system.
The predicted 100-year flood elevation for this detention basin is 870.9 MSL. Based on
the 2-foot topographic information, if flood waters reach this elevation the structure at
6415 York Avenue would be affected and potentially the structure at 6455 York
Avenue. To prevent these structures from incurring flood damage, the pump capacity
from the system should be increased. It is recommended that the capacity of both the
east and west lift stations be upgraded to 1500 gpm (approximately 3 cfs) each. It is
also recommended that the pumps turn on at water elevation 862.5 and off at
861.5 MSL. With implementation of these recommendations, the predicted 100-year
frequency flood elevation is 870 MSL, providing a level of protection for these
structures.
This area was evaluated as part of the STS-406 project (2013-2014).
No improvements have been completed for this flood protection project.
7.3.1.7 T.H. 62 at France Avenue
(NC_132)
The modeling results indicated that isolated flooding would occur along T.H. 62 during
a 100-year frequency storm event. Specifically, flooding would occur on T.H. 62 near
the France Avenue crossing. The 100-year frequency flood elevation of this area is
873.2 MSL. To correct this problem, it will be necessary to re-examine the capacity of
the T.H. 62 storm sewer system.
Adjacent areas were evaluated as part of the STS-406 project (2013-2014). Although flooding in this
subwatershed was not specifically addressed, improvement alternatives proposed in STS-406 may also reduce
the flood elevation in NC_132. No improvements have been completed for this flood protection project.
7.3.1.8 Parnell Avenue and Valley
View Road (NC_135)
A backyard depression area exists between the blocks of Ryan Avenue and Parnell
Avenue, just south of Valley View Road. The backyard depression area collects
stormwater from its direct subwatershed of approximately 3 acres. The area is
currently not connected to the storm sewer system. The predicted 100-year frequency
flood elevation for this area is 910.2 MSL. Based on the 2-foot topographic data, this
flood elevation would potentially impact the structures at 4801 and 4809 Valley View
Road and 6112 Parnell Avenue.
There have not been any studies or improvement projects completed for this area.
Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-12
2011 CWRMP
Plan Section Title 2011 CWRMP Text Status notes
Nine Mile Creek-South
8.3.1.1 7001 & 7025 France
Avenue (CL_51)
A depression area exists at the properties of 7001 and 7025 France Avenue. The
depression area is drained by an 18-inch storm sewer pipe that connects into the trunk
system along France Avenue. During intense storm events, such as the 100-year
frequency storm, high flows through the France Avenue trunk system restrict the
drainage from the depression area and the area becomes inundated with stormwater.
The 100-year frequency flood elevation for this depression area is 862.6 MSL. Flooding
problems have been historically noted in this area. A flapgate was added to the
collection pipe at this area to prevent the France Avenue system from backing up and
causing further inundation. However, with the flapgate closed, there is no outlet from
this area and the storage volume in the parking lot is not sufficient to prevent flooding
of the structures. Prior to construction of the bank currently located on this property,
the property owner was informed of the flooding potential. No recommendations to
alleviate the flooding are being made at this time.
There have not been any studies or improvement projects completed for this area.
Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-13
2011 CWRMP
Plan Section Title 2011 CWRMP Text Status notes
Nine Mile South Fork
9.3.1.1 6309 Post Lane (AH_31)
A depression area exists in the backyard area of 6309 Post Lane. The depression area
receives stormwater from a direct watershed of 1.7 acres. Stormwater collected in the
depression area enters a 30-inch storm sewer system through a catchbasin located at
the low point of the backyard. Upstream of the backyard depression area, the 30-inch
system receives stormwater from the T.H. 62 and T.H. 169 interchange and discharge
from the Arrowhead Pointe pond (AH_4). During intense rain storms, such as the
100-year frequency event, the capacity of the 30-inch system is limited from upstream
drainage, preventing the backyard area from being drained. Under current conditions,
the 100-year frequency flood elevation in the backyard depression area is 883.4 MSL.
This flood elevation is above the low entry of the home at 6309 Post Lane, surveyed at
880.6 MSL.
To alleviate the flooding of the backyard area, it is necessary to restrict the flow in the
30-inch system from upstream drainage areas during the time period of the backyard
inundation. Currently, stormwater from the T.H. 62 and T.H. 169 interchange is
collected in a series of ditches and enters the 30-inch storm sewer system through a
flared end section on the north side of T.H. 62 (subwatershed AH_25) and a
catchbasin/manhole inlet on the southeast side of the interchange (subwatershed
AH_29). To retard the flow in the 30-inch system during the time period of the
backyard inundation, it is recommended that a control structure be installed at the
catchbasin/manhole inlet in the ditch southeast of the T.H. 62 and T.H. 169 interchange
(node AH_29). The control structure should consist of a 6-inch orifice at elevation
882 MSL to allow low flows through during smaller storm events and to allow the
ditches to completely drain. A 6-foot weir at elevation 887 MSL will restrict high flows
through the system during the time period of the backyard inundation and take
advantage of available temporary storage in the highway ditches.
In addition, it is recommended that the control structure from the Arrowhead Pointe
pond (AH_4) be modified to restrict flow from the pond during the time period of the
backyard inundation. It is recommended that the control structure consist of a 4-inch
diameter orifice at elevation 884 MSL and a 6-foot weir at elevation 887 MSL. With
implementation of these recommendations, the resulting 100-year frequency flood
elevation in the backyard depression area is 880.5 MSL, below the low entry elevation
at 6309 Post Lane.
There have not been any studies or improvement projects completed for this area.
9.3.1.2 Braemar Golf Course
(NMSB_62)
The predicted 100-year flood elevation of the NMSB_62 watershed is 840.9 MSL.
Based on the 6-foot topographic information from the City, it appears that this flood
level will impact the Executive Course clubhouse at the Braemar Golf Course.
Anecdotal information suggests this structure has been affected by flood waters in the
past.
There have not been any studies or improvement projects completed for this area. Recent improvements
have been constructed at Braemar Golf Course, including significant re-grading. The NMCWD or City models
have not been revised to reflect the updated grading at Braemar.
Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-14
2011 CWRMP
Plan Section Title 2011 CWRMP Text Status notes
9.3.1.3
Paiute Pass & Sally Lane
Intersection (NMSB_83,
NMSB_84)
The storm sewer system at the Paiute Pass and Sally Lane intersection collects
stormwater from a total drainage area of approximately 27 acres. The system
discharges into the Braemar Branch, west of Sally Lane, via two 24-inch pipes. During
the 10-year and 100-year storm events, the Paiute Pass/Sally Lane intersection is
inundated with stormwater and ponding occurs. Based on topographic information
from the City, ponding will occur in this intersection to Elevation 863.6 MSL. As water
levels rise higher than this, water will begin to encroach upon the homes west of Sally
Lane (7000, 7004, 7008 Sally Lane) and eventually flow to the Braemar Ditch via
overland flow. It is recommended that the topography of this area be examined in
further detail and a controlled positive overflow path be constructed between the
homes if necessary to ensure the homes are protected from flood waters.
This area was evaluated as part of the STS-406 project (2013-2014). Barr worked with the City’s consultant in
evaluating options for storm sewer modifications as part of the local street reconstruction project in the
summer/fall of 2014 to address some of the recommendations from STS-406. New storm sewer was installed
in 2015.
Included as a current flood protection project in Section 9.3.1.2.
9.3.1.4
7009 & 7013 Sally Lane
Backyard Depression Area
(NMSB_70)
A backyard depression area exists behind the homes along Sally Lane and Paiute Pass.
A 12-inch piped outlet exists from this area, draining northward and connecting to the
system along Paiute Pass. During the 100-year storm event, the predicted flood
elevation reaches 864.5 MSL, assuming an overland flow channel from this area. Based
on topographic information from the City, this flood elevation encroaches upon the
homes at 7009 and 7013 Sally Lane. It is recommended that the topography of this
area be further examined to determine the elevation at which the flooded area will
drain west toward Sally Lane via overland flow. If necessary, a controlled positive
overflow should be constructed between the homes to prevent flood water from
damaging the structures.
This area was evaluated as part of the STS-406 project (2013-2014). Barr worked with WSB in evaluating
options for modifications to the storm sewer in this area (specifically NMSB_70) in the summer/fall of 2014.
Pipes were upsized in 2015 Valley View Road Improvements.
Southwest Ponds
10.3.1.1 7411 Coventry Way
(SWP_14)
A small stormwater pond is located in the backyard of 7411 Coventry Way. The small
stormwater pond outlets to a larger pond located directly east, across Delaney
Boulevard (SWP_5) through a 15-inch storm sewer system. During extreme storm
events, such as the 100-year frequency event, the flood elevation of the larger pond
east of Delaney Boulevard increases and flow reverses in the 15-inch system
connecting the two ponds, equalizing the ponds. The 100-year frequency flood
elevation for both ponds (SWP_14 and SWP_5) is 833.6 MSL. Based on the 2-foot
topographic data, this flood elevation would affect the structure at 7411 Coventry Way.
To prevent flooding at 7411 Coventry Way, it is recommended that a flapgate be
installed at the outlet of the small pond to prevent backflow from the larger pond.
With installation of a flapgate, the 100-year frequency flood elevation of the small
pond is 830.6 MSL.
This area was evaluated as part of the STS-406 project (2013-2014).
No improvements have been completed for this flood protection project. Programmed for future CIP.
Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-15
2011 CWRMP
Plan Section Title 2011 CWRMP Text Status notes
10.3.1.2 7317 Cahill Road (SWP_46)
A low depression area exists along Cahill Road just north of the Cahill and Dewey Hill
Road intersection and extends eastward into the parking lot of 7317 Cahill Road.
During intense rainfall events, such as the 100-year frequency storm, this low area
becomes inundated. The 100-year frequency flood elevation in this area is 833.8 MSL.
Based on the 2-foot topographic data, this flood elevation will impact the structure at
7317 Cahill Road. However, because the flood elevations of the two stormwater ponds
in Lewis Park north of Dewey Hill Road (SWP_35 and SWP_34) and the stormwater
pond on the south side of Dewey Hill Road (SWP_5) are nearly as high, options to
reduce the flooding of the road and parking lot of 7317 Cahill Road are limited. It is
recommended that options to lower the flood elevation of this area be further
investigated as road improvement projects are planned in the area in the future.
This area (FilmTech) was evaluated as part of the STS-406 project (2013-2014).
No improvements have been completed for this flood protection project.
10.3.1.3 7709 Stonewood Court
(NM494_4)
A stormwater pond is located northeast of the Stonewood Court and Gleason Road
intersection. The basin is drained by a 12-inch storm sewer pipe with a negative slope
that acts as an inlet and an outlet, depending upon the water level in the pond. The
water level of the pond is controlled by the pipe invert downstream of the outlet on
the west side of Gleason Road at Elevation 828.1 MSL. If the water level in the pond is
below 828.1 MSL, the storm sewer system that collects stormwater from Tanglewood
Court and Gleason Road discharges to the pond. If the water elevation is higher than
828.1 MSL, discharge from the stormwater pond will combine with stormwater from
the Tanglewood Court and Gleason Road system and will continue flowing southward
towards the South Fork of Nine Mile Creek.
During the 100-year frequency storm event, the flood elevation of this stormwater
pond reaches 832.5 MSL. Based on a field survey, this flood elevation will impact the
structure at 7723 Stonewood Court (low house elevation of 831.97 MSL). To protect
this structure from the 100-year flood elevation, it is recommended that the capacity of
the downstream storm sewer system along Stonewood Court be increased. Based on
modeling results, increasing the size of pipes 1011p and 1012p from 12-inch diameter
to 24-inch diameter will reduce the 100-year flood elevation of the stormwater pond to
831.81 MSL, slightly below the low house elevation.
There have not been any studies or improvement projects completed for this area. Programmed for future
CIP.
Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-16
2011 CWRMP
Plan Section Title 2011 CWRMP Text Status notes
Northeast Minnehaha Creek
12.3.1.1
4000 West 42nd Street
and 4100, 4104, and
4108 France Avenue
(MS_40)
A large portion of the Morningside watershed discharges to a pond located on the east
side of Weber Park (Weber Park Pond). This pond was designed to provide protection
for a 50-year storm. The City’s 2004 Comprehensive Water Resources Management Plan
identified the potential for flooding of properties adjacent to the pond, which was
confirmed during a significant rainfall event that occurred in 2005. In 2006, the City
completed a Feasibility Analysis to assess the flooding problem and evaluate options
to minimize the flooding potential. Results of the 2006 analysis indicate that the
predicted high water elevations in the Weber Park Pond for a 50-year and 100-year
frequency flood event, based on existing conditions, are 868.6 ft MSL and 869.0 ft MSL,
respectively. A field survey completed at the time indicates that the low entry
elevations of four homes adjacent to the pond are at or below the predicted 100-year
high water elevation, including 4000 West 42nd Street, 4100 France Avenue, 4104
France Avenue, and 4108 France Avenue.
Based on the feasibility study completed, it was determined that the options to
alleviate the flooding potential for the homes adjacent to the Weber Park pond are
limited due to constraints in the downstream storm sewer system. Adding additional
storage volume to the Weber Park pond would reduce the 100-year flood elevation of
the pond to approximately 868.5 ft MSL. However, this flood elevation is still at or
above the low entry elevation of three of the homes adjacent to the pond. An
additional downstream capacity of 80 cfs would be required to alleviate the flooding at
all adjacent properties under existing pond conditions, which is an expensive option.
Should the City of Minneapolis update their storm sewer system in this area in the
future, Edina will consider working with the City of Minneapolis to incorporate
upgrades sufficient to provide additional capacity for the Morningside area drainage.
The most cost effective option to upgrade to a 100-year level of protection for the
homes currently below the 100-year flood level (4100, 4104, and 4108 France Avenue)
would be to floodproof the affected homes and installation of a pumping station to
drain stormwater runoff from the backyard area of the affected properties during
significant storm events.
This area was evaluated in detail as part of the 2017 CWRMP Update. Included as a current flood protection
project in Section 12.3.1.3.
12.3.1.2 4308 France Avenue
(MS_17)
The low area in the backyard of 4308 France Avenue is inundated to an elevation of
902.5 MSL during the 100-year frequency storm. The results of a field survey indicate
that this water level will potentially impact the house located at 4308 France Avenue.
To protect the structure at 4308 France Avenue, it is recommended that in this
depression area a catch basin be located and connected to the storm sewer system at
the intersection of Scott Terrace and West 42nd Street.
This area was evaluated as part of the STS-406 project (2013-2014).
No improvement projects have been completed for this area.
Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-17
2011 CWRMP
Plan Section Title 2011 CWRMP Text Status notes
12.3.1.3
4300, 4214, and
4212 Branson Street
(MS_3)
A depression in the backyard of 4300, 4214, and 4212 Branson Street is inundated to
an elevation of 900.6 MSL during the 100-year frequency storm event. At this elevation
structures will be affected at 4300, 4214 and 4212 Branson Street. A 15-inch storm
sewer originating at Branson Street flows north and connects to the pipe system on
Morningside Street. It is recommended that a catch basin be placed in the backyard
depression area and pipe 955 upgraded to 24-inch diameter. This will reduce the
100-year frequency storm elevation to 899.5 MSL and protect the structures at 4300,
4214, and 4212 Branson Street.
This area was evaluated in detail as part of the 2017 CWRMP Update. Included as a current flood protection
project in Section 12.3.1.6.
12.3.1.4 4140 and 4150 West
44th Street (MS_7)
A depression in the backyard of 4140 and 4150 West 44th Street is inundated to
900.6 MSL during the 100-year frequency storm as a result of runoff from its tributary
watershed area. In addition, the storm sewer system on West 44th Street surcharges
during the 100-year frequency storm and as a result, water flows from West 44th Street
and into the backyard depression area.
The addition of a catch basin to the backyard of 4140 and 4150 West 44th Street with a
connection to the pipe system on West 44th Street was evaluated, but this alternative
would require that the entire pipe system along West 44th Street and Morningside
Avenue be upgraded. It is recommended that the storage capacity of this backyard
area be increased by 1.4 acre-feet to an elevation of 899.3 MSL to protect the structure
at 4140 and 4150 West 44th Street. This additional storage capacity can be achieved by
lowering the depth of the backyard depression area by approximately 2 feet.
There have not been any studies or improvement projects completed for this area. Included as a current flood
protection project in Section 12.3.1.6.
12.3.1.5 Arden Avenue (MHN_14)
Storm sewer improvements made in 2000 on Bridge Street, Sunny Side Road, and
Arden Avenue were designed to reduce the potential for flooding at the low area on
Arden Avenue just south of Bridge Street. The high water elevation of the 100-year
frequency storm was 884.6 MSL, indicating that during a 100-year storm event the
storm sewer improvements would protect the houses on Arden Avenue with the
exception of the low house at 4611 Arden Avenue.
There have not been any studies or improvement projects completed for this area.
15.2.2.1
White Oaks Landlocked
Area (MHN_1, MHN_49,
MHN_12, MHN_65)
The MCWD Plan identified a landlocked area located in the northeast portion of the
city, generally south of Sunnyside Road and north of West 49th Street, east of Arden
Avenue and west of France Avenue. To assess the flood potential in this landlocked
area, the 100-year, 10-day snowmelt event was simulated in XP-SWMM, assuming
impervious (frozen ground) conditions. Comparison of the modeling results with the
City’s 2-foot topographic information indicates that there is potential for the 100-year
high water levels to impact structures in the following subwatersheds: MHN_1,
MHN_49, MHN_12, MHN_65. To assess the potential for flooding, the City will
complete a field survey to determine the low entry elevations of the potentially
impacted structures and a detailed feasibility study to identify remedial measures, if
necessary.
This area was evaluated as part of the STS-406 project (2013-2014).
No improvements have been completed for this flood protection project.
Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-18
2011 CWRMP
Plan Section Title 2011 CWRMP Text Status notes
Southeast Minnehaha Creek
13.3.1.1 6213 Ewing Avenue
(LP_15)
A depression area on the street adjacent to 6213 Ewing Avenue collects water from a
3.8-acre watershed. The 100-year frequency flood elevation of 884.3 MSL will
potentially impact the structure at 6213 Ewing Avenue. It is recommended that the
diameters of pipes 1696 and 1695 be increased to 18-inches to provide a 100-year
level of protection.
This issue was evaluated in 2015 for ENG 16-3. Upsizing existing pipes was deemed infeasible as part of this
project.
13.3.1.2 3600 West Fuller Street
(MHS_4)
The 100-year frequency flood elevation for the backyard depression area directly
behind 3600 West Fuller Street is 875.4 MSL. A field survey indicates this elevation is
above the low entry (872.6 MSL) at 3600 West Fuller Street. It is recommended that a
catch basin be placed in the backyard depression and connected to a new storm sewer
system installed east along Fuller Street and south along Beard Avenue to Minnehaha
Creek. An existing bituminous drainage channel between Beard Avenue and
Minnehaha Creek at this location appears to be a potential access point to Minnehaha
Creek for the new pipe. The addition of a pipe system and catch basins extending
from Fuller Street to Beard Avenue and then to Minnehaha Creek would provide the
additional benefit of handling the significant street flows that occur on Fuller Street
and Beard Avenue.
There have not been any studies or improvement projects completed for this area.
Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-19
2011 CWRMP
Plan Section Title 2011 CWRMP Text Status notes
13.3.1.3
5605, 5609, 5613, 5617,
5621, 5625, and
5629 South Beard Avenue
(MHS_79)
Water in the alley between Abbott and Beard Avenue and south of West 56th Street
rises to an elevation of 880.1 MSL during the 100-year frequency storm and affects the
garages in this alley. This is the result of water flowing from West 56th Street to the
alley and the limited flow in the pipe leading from the alley to the storm sewer system
located on Beard Avenue. Currently the storm sewer system on Beard Avenue does
not provide a 10-year level of service and is significantly undersized for the 100-year
storm. At the intersection of Beard and West 56th Street, street flow on Beard Avenue
reaches a peak of 97 cfs during the 100-year storm while the pipe carries only a peak
flow of only 4.7 cfs. The street flow then flows on Beard Avenue to Minnehaha Creek.
The following pipe sizes are recommended to protect the structures in the alley during
a 100-year storm:
Pipe 1851p ................................. 12 to 24-inch
Pipe 1852p ................................. 12 to 24-inch
Pipe 1156 ................................... 12 to 24-inch
Pipe 1159 ................................... 27 to 36-inch
Pipe 1158 ................................... 27 to 36-inch
Pipe 1152 ................................... 33 to 36-inch
Pipe 1153 ................................... 15 to 36-inch
An additional catch basin is also required at the low point in the alley. To collect runoff
along West 56th Street before it enters the alley, an additional catch basin is
recommended on the south side of West 56th Street, east of the alley entrance. These
recommendations are not designed to reduce the large street flows that are present on
Beard Avenue during the 100-year storm. Further pipe size increases of the entire
system and the addition of catch basins would be required to significantly reduce the
flow of water along Beard Avenue.
There have not been any studies or improvement projects completed for this area.
13.3.1.4
5837, 5833, 5829,
5825 South Chowen
Avenue (LP_24)
A backyard depression area directly behind 5829 South Chowen Avenue is inundated
to an elevation of 884.6 MSL during the 100-year frequency storm and affects the
structures at 5837 5833, 5829, and 5825 South Chowen Avenue. It is recommended
that a catch basin be placed in the backyard depression area and connected with a
12-inch RCP to the storm sewer node LP_27 located at the intersection of South
Chowen Avenue and West 60th Street.
This area was evaluated as part of the STS-406 project (2013-2014).
There have not been any studies or improvement projects completed for this area. There is potential for this
to be addressed in future neighborhood roadway construction.
13.3.1.5 Chowen Avenue and West
60th Street (LP_27)
A 100-year frequency flood elevation of 883.9 MSL has been calculated at the
intersection of Chowen Avenue and West 60th Street. Although the model shows that
there is the potential for significant flooding in this intersection, a thorough survey of
the storm sewers and structures in this area needs to be completed to verify their size,
invert elevations, and low point of entry.
This area was evaluated as part of the STS-406 project (Part 1) in 2013-2014.
Issue was re-evaluated in 2015 for ENG 16-3. Upsizing existing pipes along Chowen and 61st was analyzed
and deemed infeasible. It was determined this could be solved by additional pipes along 60th and France to
Pamela Park as part of future street reconstruction or stand-alone storm project.
Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-20
2011 CWRMP
Plan Section Title 2011 CWRMP Text Status notes
13.3.1.6
5912, 5916, 5920, 5924,
5928 Ashcroft Avenue and
5925 Concord Avenue
(MHS_51)
Water in the backyard depression area of subwatershed MHS_51 will rise to 882.9 MSL
during the 100-year frequency storm event. This flood elevation will inundate several
of the houses adjacent to the depression. Water frequently ponds in this backyard
depression area and either a pumped or gravity outlet from this area with a 3 cfs
capacity is required to provide a level of protection.
There have not been any studies or improvement projects completed for this area.
13.3.1.7 5840 and 5836 Ashcroft
Avenue (MHS_89)
The houses at 5840 and 5836 Ashcroft Avenue are located in a shallow depression area
that fills with water from a small 0.7-- directly adjacent watershed. The calculated
100-year frequency flood elevation of 884 MSL will inundate the structures at 5840 and
5836 Ashcroft Avenue. It is recommended that a catch basin be placed at this
depression and connected to the adjacent storm sewer system on Concord Avenue
(node MHS_58). This outflow capacity will reduce the flood elevation to 883 MSL and
provide the required level of protection for these structures.
There have not been any studies or improvement projects completed for this area.
13.3.1.8
5609 and 5605 Dalrymple
Road (MHS_24) and 5610
and 5612 St. Andrews
Avenue (MHS_66)
The calculated 100-year frequency flood elevation for the depression on Dalrymple
Road is 895.3 MSL. This flood elevation is above the lowest entry way for both 5609
(low entry at 893.4 MSL) and 5605 (low entry at 893.25) Dalrymple Road. A field survey
of the area indicates that a surface outflow existed between Dalrymple Road and the
backyard area of subwatershed MHS_66 but has been filled. It is recommended that
either this outflow be reestablished or pipes 1784 and 1240 be upgraded to 24-inch
diameter pipes.
The backyard depression area of MHS_66 is inundated to 894.8 MSL during the
100-year frequency flood. This elevation is above the elevation (894.46 MSL) of a back
yard entry to 5610 Andrews Avenue, the basement windowsill (891.44 MSL) at 5612
Andrews Avenue, and the basement windowsill (893.53 MSL) at 5608 Andrews Avenue.
It is recommended that a surface outflow be established between the backyard
depression area and St. Andrews Avenue or pipes 1784 and 1240 be upgraded to
24-inch diameter pipes.
There have not been any studies or improvement projects completed for this area.
13.3.1.9 5701 Dale Avenue (ML_12)
A depression on Dale Avenue, directly adjacent to 5701 Dale Avenue, is inundated to
an elevation of 935.8 MSL during the 100-year frequency storm event. According to a
field survey, the low entry way at 5701 Dale Avenue is at an elevation of 935.5 MSL,
indicating that the storm sewer system on Dale Avenue does not provide a level of
protection for the structure at 5701 Dale Avenue during the 100-year frequency storm
event. It is recommended that the diameter of pipes 1 and 1826 be increased to
24 inches to protect the structure at 5701 Dale Avenue from flooding.
There have not been any studies or improvement projects completed for this area.
13.3.1.10 5213 and 5217 Richwood
Drive (ML_7)
A wetland area behind 5213 and 5217 Richwood Drive receives runoff from a 3-acre
watershed. This wetland receives water from backyard areas, rooftops, and a small
section of Windsor Avenue. During the 100-year frequency storm event the water level
in this wetland rises to 928.6 MSL. This water level is above the elevation of the low
entry for 5213 and 5217 Richwood Drive. It is recommended that the storage capacity
of this wetland area be surveyed and the flooding potential be further evaluated.
This area was evaluated in preparation for the 2012 Richmond Hills Park Neighborhood Improvements. New
storm sewer installed in 2012.
Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-21
2011 CWRMP
Plan Section Title 2011 CWRMP Text Status notes
Northwest Minnehaha Creek
14.3.1.1 Interlachen Landlocked
Area
The MCWD Plan identified a landlocked area located west of T.H. 100 and north of
Vernon Avenue. This area, which encompasses subwatersheds EI_11, EI_12, EI_24,
EI_13, and EI_19, currently drains to a wetland complex (EI_19) just south of
Meadowbrook Golf Course. Two-foot topographic information for the area indicates
that the natural overflow elevation between the landlocked wetland complex and the
Meadowbrook Golf Course is approximately 885 feet M.S.L. Based on the FEMA Flood
Insurance Study for Hennepin County (FEMA, 2004), the 100-year flood level of
Minnehaha Creek as it flows through the golf course is 892 feet M.S.L.
The maximum flood elevation that the City will allow in the wetland area (EI_19) is 888
feet M.S.L. To prevent the backflow of water from the Meadowbrook Golf Course to
the wetland complex (EI_19), it is recommended that an embankment be
constructed/raised between the wetland and the golf course to an elevation of at least
892 feet M.S.L. Upon raising the embankment, a pumped outlet will be required to
keep the flood elevation below 888 feet M.S.L. The City should establish a
management plan to address necessary pumping scenarios. Previous analyses for the
area indicate a 1 cfs pumped outlet would be sufficient.
There have not been any studies or improvement projects completed for this flood protection project.
Appendix D
List of Pond Improvement Recommendations
Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina
D-1
List of Pond Improvement Recommendations
2011 CWRMP
Plan Section Project Name/Location Proposed Improvement
Nine Mile Creek-North
5.3.2.1 Pond MD_15 (Sun Road) Provide additional 0.3 acre-feet of dead storage volume.
5.3.2.2 Pond NMN_27 (Northeast of TH 62 and TH 169) Provide additional 1.4 acre-feet of dead storage volume.
5.3.2.3 Pond NMN_24 (Between Waterford Ct and Habitat Ct) Increase pond depth.
5.3.2.4 Pond NMN_49 (West of 5521 Malibu Drive) Provide additional 0.2 acre-feet of dead storage volume.
5.3.2.5 Pond MD_3 (Bredesen Park, east of parking area) Excavate to remove accumulated sediment.
Lake Cornelia/Lake Edina/Adam’s Hill
7.3.2.1 Pond LE_38 (West of Lake Edina) Provide additional 1.4 acre-feet of dead storage volume within MnDOT right-of-way
Nine Mile Creek-South
8.3.2.1 Subwatershed NMS_1 (Southwest quadrant of the TH 100 and West 77th Street interchange) Construct water quality basin.
8.3.2.2 Pond NMS_76 (Fred Richards Golf Course) Provide additional 2.5 acre-feet of dead storage volume.
8.3.2.3 Pond NMS_104 (Fred Richards Golf Course) Provide additional 0.2 acre-feet of dead storage volume.
8.3.2.4 Ponds NMS_72, NMS_74 (Fred Richards Golf Course) Increase pond depths.
8.3.2.5 Pond SP_1 (Border Basin - West of Minnesota Drive and West 77th St) Provide additional 21.5 acre-feet of dead storage volume.
Nine Mile South Fork
9.3.2.1 Ponds NMSB_3, NMSB_2 (Braemar Golf Course) Provide additional 1.2 acre-feet of dead storage volume.
9.3.2.2 Pond NMSB_12 (Braemar Golf Course) Regular maintenance.
9.3.2.3 Pond NMSB_86 (Braemar Golf Course) Provide additional 0.15 acre-feet of dead storage volume.
9.3.2.4 Pond NMSB_7 (Braemar Golf Course) Increase pond depth.
9.3.2.5 Pond NMSB_85 (Braemar Golf Course) Provide additional 1.2 acre-feet of dead storage volume.
Appendix E
Aquatic Vegetation Prioritization List
Aquatic vegetation services requests - Prioritization ChartThe prioritization list is not comprehensive, and more water bodies may be added. Water bodies may be reclassified using updated information.This prioritization list is used to determine eligibility for aquatic vegetation services.Water Body Tiny Small Medium Large No dataData showing water body does not meet goalsDrains directly to a 303(d) Impaired Water303(d) Impaired Waters ListTotal PointsPublic access and use - raise one service level50% shoreline owner involvement - raise one service levelService Level12 3 4 0 2 3 4Lake Cornelia448Yes Yes (for 2016+)HighMud Lake404YesMediumLake Edina448 HighMirror Lake404LowArrowhead Lake426YesHighIndianhead Lake426YesHighHighlands Lake404YesMediumOtto Pond303LowMelody Lake325YesHighLake Pamela336YesHighHawkes Lake303LowHarvey Lake303LowSwimming Pool Pond336 MediumLong Brake Trail Pond303Yes (for 2015+)MediumLake Nancy336YesHighPoint of France Pond303LowCreek Valley303LowUnnamed (near Parkwood & Knoll)303 LowUnnamed (Schaefer & Harold Woods)303 LowCote Pond202Yes (for 2016+)LowUnnamed (near Nine Mile Village Townhomes)202 NoneIncreased Service LevelSizeWater Quality Last Updated 12/13/2017 Page 1 of 2
Aquatic vegetation services requests - Prioritization ChartThe prioritization list is not comprehensive, and more water bodies may be added. Water bodies may be reclassified using updated information.This prioritization list is used to determine eligibility for aquatic vegetation services.Water Body Tiny Small Medium Large No dataData showing water body does not meet goalsDrains directly to a 303(d) Impaired Water303(d) Impaired Waters ListTotal PointsPublic access and use - raise one service level50% shoreline owner involvement - raise one service levelService LevelIncreased Service LevelSizeWater QualityUnnamed (south of Cote & Long Brake Tr)202 NoneBirchcrest Pond202Yes (for 2017+)LowSouth Pond202 NoneHyde Park Pond/Shannon Pond202Yes (for 2016+)LowWest Garrison Pond202 NoneUnnamed (south of Mirror Lake)202 NoneUnnamed (Blake Rd & Knoll Drive)202 NoneAnnaway Pond202 NonePrescott Pond101Yes (for 2017+)LowEdina incorporated Lake AssociationsArrowhead Lake Association (ALA)Cote PondLake Cornelia groupEdina lake groupsLong Brake Trail PondHyde Park/Shannon Pond groupPrescott Cirlce Pond groupBirchcrest Pond groupThe Indianhead Lake Association (TILA)Friends of Melody Lake (FoML)Lake Nancy Lake Association (LNLA) Last Updated 12/13/2017 Page 2 of 2
Appendix F
Modified Minnesota Routine Assessment Method for Evaluating Wetland Functions (MnRAM) Version 2.0
Appendix G
GIS Wetlands Inventory Database
Data is located in a stand-alone file