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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
P:\Mpls\23 MN\27\23271514 2017 CWRMP SW Modeling Updates\WorkFiles\Imperviousness Analysis\Imperviousness Analysis Summary.docx
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
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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
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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%
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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
P:\Mpls\23 MN\27\23271514 2017 CWRMP SW Modeling Updates\WorkFiles\Imperviousness Analysis\Imperviousness Analysis Summary.docx
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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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
P:\Mpls\23 MN\27\23271514 2017 CWRMP SW Modeling Updates\WorkFiles\Imperviousness Analysis\Imperviousness Analysis Summary.docx
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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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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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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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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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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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
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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.
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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
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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
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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.
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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.
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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.
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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
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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.
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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.
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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