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HomeMy WebLinkAboutEdina_2022_WRMP_Final_12152022Water Resources Management Plan December 2022 Amendment Nine Mile Creek near Edina High School 4300 MarketPointe Drive, Suite 200 Minneapolis, MN 55435 952.832.2600 www.barr.com City of Edina Water Resources Management Plan Prepared for City of Edina December 2022 Amendment City of Edina 2022 Water Resources Management Plan i P:\Mpls\23 MN\27\23271799 Edina CWRMP Amendment\WorkFiles\Amended CWRMP\Edina_2022_WRMP_Final_12152022.docx City of Edina Water Resources Management Plan December 2022 Amendment Contents 1.0 Executive Summary ........................................................................................................................................................... 1-1 1.1 Problems, Issues, and Potential Solutions ............................................................................................... 1-2 1.1.1 Water Resources Implementation Program ........................................................................ 1-2 1.1.2 Runoff Management and Flood Control ............................................................................... 1-2 1.2 Flood Risk Management ................................................................................................................................ 1-2 1.3 Clean Water Management ............................................................................................................................ 1-3 2.0 Introduction and Physical Setting ............................................................................................................................... 2-1 2.1 Plan Purposes ..................................................................................................................................................... 2-1 2.2 Physical Setting .................................................................................................................................................. 2-2 2.2.1 Drainage Patterns ........................................................................................................................... 2-2 2.2.1.1 Hydrologic Modeling of Major Drainage Areas ....................................................... 2-3 2.2.2 Watershed Management Organizations ............................................................................... 2-4 2.2.2.1 Minnehaha Creek Watershed District ................................................................................. 2-4 2.2.2.2 Nine Mile Creek Watershed District .................................................................................... 2-4 2.2.3 Land Use ............................................................................................................................................ 2-4 2.2.4 Soils ...................................................................................................................................................... 2-4 2.2.5 Topography ...................................................................................................................................... 2-5 2.2.6 Water Quality ................................................................................................................................... 2-5 2.2.6.1 Water Quality Monitoring ....................................................................................................... 2-5 2.2.6.2 Impaired Waters and Total Maximum Daily Loads ....................................................... 2-8 2.2.7 Wetlands ......................................................................................................................................... 2-12 2.2.7.1 City of Edina Wetlands Inventory—1999 ....................................................................... 2-12 2.2.7.2 MCWD FAW—2003 ................................................................................................................. 2-13 2.2.8 Public Waters ................................................................................................................................ 2-13 2.2.9 Parks, Recreation, and Natural Resources Open Space ............................................... 2-15 2.2.10 Public Utilities ............................................................................................................................... 2-16 2.2.11 Fish and Wildlife Habitat .......................................................................................................... 2-16 2.2.12 Unique Features and Scenic Areas ....................................................................................... 2-18 2.2.13 Pollutant Sources ......................................................................................................................... 2-18 City of Edina 2022 Water Resources Management Plan ii 2.2.13.1 Investigation and Cleanup Sites......................................................................................... 2-18 2.2.13.2 Tank Sites and Leak Sites ...................................................................................................... 2-19 2.2.13.3 Individual Sewage Treatment Systems ........................................................................... 2-19 2.2.14 Groundwater ................................................................................................................................. 2-19 3.0 Water Resources Management and Implementation Program ...................................................................... 3-1 3.1 Water Resources Network: A Combination of Stormwater Assets and Natural Resources 3-1 3.1.1 Public Waters ................................................................................................................................... 3-3 3.1.2 Wetlands ............................................................................................................................................ 3-3 3.1.3 Natural Resources Monitoring and Inspections ................................................................. 3-3 3.2 Stormwater Infrastructure Asset Management ..................................................................................... 3-3 3.2.1 Asset Procurement ......................................................................................................................... 3-4 3.2.2 Asset Ownership ............................................................................................................................. 3-4 3.2.3 Inventory and Inspection ............................................................................................................. 3-5 3.2.4 Operations and Maintenance .................................................................................................... 3-6 3.2.5 Renewal and Replacement ......................................................................................................... 3-8 3.2.6 New and Upgraded Public or Private Assets ....................................................................... 3-8 3.3 Flood Risk Management ................................................................................................................................ 3-9 3.3.1 Flood Risk Reduction Strategy ............................................................................................... 3-10 3.3.2 Flood Risk, Exposure, and Vulnerability .............................................................................. 3-10 3.3.2.1 Vectors for Principal Structure Flood Exposure ........................................................... 3-11 3.3.2.2 Flood Exposure Data and Trends ...................................................................................... 3-12 3.3.3 Sectors of Work ............................................................................................................................ 3-15 3.3.3.1 Infrastructure .............................................................................................................................. 3-16 3.3.3.2 Regulation ................................................................................................................................... 3-16 3.3.3.3 Outreach and Engagement .................................................................................................. 3-17 3.3.3.4 Emergency Services and Public Safety ............................................................................ 3-17 3.4 Clean Water ...................................................................................................................................................... 3-18 3.4.1 Clean Water Infrastructure ....................................................................................................... 3-18 3.4.2 Clean Water Programs .............................................................................................................. 3-19 3.4.2.1 Community Engagement ...................................................................................................... 3-19 3.4.2.2 Pollution Prevention ............................................................................................................... 3-20 3.4.2.3 Pollution Source Controls ..................................................................................................... 3-21 3.4.2.4 Lake and Pond Management .............................................................................................. 3-22 3.4.3 Clean Water Strategy ................................................................................................................. 3-25 3.4.3.1 Implementation Approach ................................................................................................... 3-26 City of Edina 2022 Water Resources Management Plan iii 3.4.3.2 Opportunity Identification and Prioritization ............................................................... 3-26 3.5 Management Approach............................................................................................................................... 3-28 3.5.1 Coordination with Watershed Districts ............................................................................... 3-29 3.5.1.1 Regulation ................................................................................................................................... 3-29 3.5.1.2 Data and Information ............................................................................................................. 3-30 3.5.1.3 Land Use Planning Opportunities ..................................................................................... 3-31 3.5.1.4 Implementation Partnership Opportunities .................................................................. 3-34 3.5.2 Development Review Process and Land Use Planning ................................................ 3-34 3.5.3 Prioritization .................................................................................................................................. 3-35 3.5.4 Resources ........................................................................................................................................ 3-36 3.5.5 Financial Considerations ........................................................................................................... 3-36 3.5.6 Utility funding ............................................................................................................................... 3-37 3.5.7 Coordinated Policy Issues ........................................................................................................ 3-38 3.6 Plan Update and Amendment Procedure ............................................................................................ 3-39 4.0 Policies for Water Resources Management ............................................................................................................ 4-1 4.1 Flood Risk and Stormwater Runoff Management ................................................................................ 4-1 4.1.1 Minimum Principal Structure Elevations ............................................................................... 4-3 4.1.2 Structure Setbacks ......................................................................................................................... 4-5 4.1.3 Below-Grade Garages and Parking ......................................................................................... 4-6 4.1.4 Stormwater Infrastructure Design Standards ...................................................................... 4-6 4.2 Clean Water Services ....................................................................................................................................... 4-7 4.3 Wetlands ............................................................................................................................................................... 4-9 4.4 Natural Resources Restoration and Protection .................................................................................. 4-10 4.5 Groundwater .................................................................................................................................................... 4-10 4.6 Appeal Process ................................................................................................................................................ 4-11 4.7 Water Resources Management Agreements ...................................................................................... 4-11 5.0 References ............................................................................................................................................................................ 5-1 City of Edina 2022 Water Resources Management Plan iv List of Tables Table 2.1 Summer (June-September) Average Total Phosphorus Concentrations for Edina Lakes......... 2-6 Table 2.2 City of Edina Waterbodies on MPCA's 303(d) Impaired Waters List................................................. 2-9 Table 2.3 MnDNR Public Waters within Edina ............................................................................................................ 2-14 Table 2.4 Fishery and Aquatic Invasive Species Information ................................................................................ 2-17 Table 3.1 Source of the Best Available 1-Percent-Annual-Chance Flood Elevations throughout the City of Edina ................................................................................................................................................................... 3-15 Table 3.2 Level of Potential Lake Management Activity by Service Level ....................................................... 3-24 Table 3.3 City Staff Support Activities and Alternative Methods Related to Table 3.2 .............................. 3-25 Table 3.4 Potential Funding Sources for Plan Implementation ........................................................................... 3-37 Table 3.5 Water Resources Implementation Program ............................................................................................ 3-40 Table 3.6 Potential Implementation Activities (including Capital Improvements) ....................................... 3-45 List of Figures Figure 1.1 Sectors of Work and City Goals ....................................................................................................................... 1-3 Figure 2.1 Major Drainage Areas ....................................................................................................................................... 2-20 Figure 2.2 Land Use Classification ..................................................................................................................................... 2-21 Figure 2.3 Edina Soils Classification .................................................................................................................................. 2-22 Figure 2.4 Water Quality Monitoring Stations ............................................................................................................. 2-23 Figure 2.5 Wetland Classifications .................................................................................................................................... 2-24 Figure 2.6 Edina Parks and Recreational Areas ............................................................................................................ 2-25 Figure 2.7 Threatened and Endangered Species ......................................................................................................... 2-26 Figure 3.1 Core Services of Water Resources Program ............................................................................................... 3-1 Figure 3.2 Data from MnDNR Climate Trends Tool .................................................................................................... 3-12 Figure 3.3 Estimates of 100-year 24-hour rainfall depth ......................................................................................... 3-13 Figure 3.4 City-Owned Property ........................................................................................................................................ 3-53 List of Appendices Appendix A Modeling Methods and Hydrologic and Hydraulic Analysis of Drainage Areas Appendix A – Attachment A City of Edina Imperviousness Assumptions for Stormwater Modeling Appendix A – Attachment B Summary of Nine Mile Creek and Minnehaha Creek Modeling Approach Appendix B Legacy Flood Risk Reduction Potential Projects Appendix C List of Potential Pond Improvements City of Edina 2022 Water Resources Management Plan v Acronyms Acronym Description APWA American Public Works Association ASFPM Association of State Floodplain Managers AWWA American Water Works Association BMPs Best Management Practices CAMP Citizen Assisted Monitoring Program CFS Cubic Feet per Second CIP Capital Improvement Program CWA Clean Water Act EOF Emergency Overflow EPA United States Environmental Protection Agency FAW Functional Assessment of Wetlands (MCWD) FEMA Federal Emergency Management Agency GCM Global Climate Model GIS Geographic Information Systems GSI Green Stormwater Infrastructure IAM Infrastructure Asset Management IBI Index of Biotic Integrity IPCC International Panel on Climate Change IPWEA Institute of Public Works Engineering Australasia ISTS Individual Sewage Treatment Systems LGU Local Government Unit MCWD Minnehaha Creek Watershed District MnRAM Minnesota Routine Assessment Method MnDNR Minnesota Department of Natural Resources MnDOT Minnesota Department of Transportation MPCA Minnesota Pollution Control Agency MS4 Municipal Separate Storm Sewer System MUSA Metropolitan Urban Service Area NAI No Adverse Impact NGVD29 National Geodetic Vertical Datum of 1929 NMCWD Nine Mile Creek Watershed District NOAA National Oceanic and Atmospheric Administration NPDES National Pollutant Discharge Elimination System City of Edina 2022 Water Resources Management Plan vi NURP Nationwide Urban Runoff Program NWI National Wetlands Inventory OHWL Ordinary High Water Level PWI Public Waters Inventory RCP Reinforced-Concrete Pipe SCS Soil Conservation Service SSURGO Soil Survey Geographic Database SWMM Stormwater Management Model SWPPP Stormwater Pollution Prevent Plan/Program TBD To Be Determined TH Trunk Highway TMDL Total Maximum Daily Load TSS Total Suspended Solids UAA Use Attainability Analysis USFWS United States Fish and Wildlife Service VIC Voluntary Investigation and Clean-up WCA Wetland Conservation Act WLA Wasteload allocation WMO Watershed Management Organization WRAPS Watershed Restoration and Protection Strategy WRMP Water Resources Management Plan City of Edina 2022 Water Resources Management Plan 1-1 1.0 Executive Summary This plan updates the City of Edina Water Resources Management Plan (WRMP). The plan was developed to address current and future stormwater issues, especially those related to future development and redevelopment. The plan addresses flood risk and stormwater runoff management, clean water services, and natural resources restoration and protection through establishment of water resources planning policies and recommendations for projects and programs. The City of Edina developed its first WRMP in 2003. The WRMP was updated in 2011, 2018, and 2022. Prior iterations of the WRMP are referenced in this document according to year (e.g., 2018 WRMP). This WRMP is composed of Section 1.0: Executive Summary and three main sections, which are described as follows: Section 2.0: Introduction and Physical Setting—presents background information regarding the City, general watershed information, and plan purposes. Section 3.0: Water Resources Management and Implementation Program—describes the programs and activities that support each of the core services (flood risk and stormwater runoff management, clean water services, and natural resources restoration and protection) and some of the policy issues around the provision and growth of service. This chapter also discusses resources, financial considerations, and implementation priorities. Section 4.0: Policies for Water Resources Management presents background information, goals, policies and design standards covering flood risk and stormwater runoff management, clean water services, and natural resources restoration and protection. References are included in Section 5.0. The WRMP also includes several appendices. Appendix A is particularly significant and includes: Appendix A.1: Methodology for Modeling—describes the data, methods and assumptions used for conducting stormwater simulation modeling throughout the city . Appendix A.2 through A.11: Major Drainage Area Descriptions and Recommendations—describes the general drainage area, drainage patterns within the area, the stormwater system modeling analysis and results, and implementation recommendations for each of the following 10 major drainage areas in the City: Nine Mile Creek- North, Nine Mile Creek- Central, Nine Mile Creek- South, Lake Cornelia/Lake Edina/Adam’s Hill, Nine Mile South Fork, Southwest Ponds, Trunk Highway (TH) 169 North, Northeast Minnehaha, Southeast Minnehaha, and Northwest Minnehaha. City of Edina 2022 Water Resources Management Plan 1-2 1.1 Problems, Issues, and Potential Solutions This section summarizes the City’s current and planned water resources implementation program, and potential stormwater management improvements identified in Section 3.0 and Appendix A of the WRMP. 1.1.1 Water Resources Implementation Program This WRMP serves as a master plan for the City’s water resources network, which is a combination of stormwater assets and natural resources. The City will work with residents to implement structural (capital) improvements and non-structural programs to address existing water resource problems within the City and to prevent future problems from occurring. The implementation program identifies the programs and improvements and provides cost estimates for budgeting purposes. Table 3.5 presents the City’s water resource-related implementation program, which includes the City’s non-structural (administration) programs and structural (capital) improvement program. Projects listed in the table are prioritized according to the City’s Flood Risk Reduction Strategy and will be prioritized according to the City’s Clean Water Strategy (when finalized). 1.1.2 Runoff Management and Flood Control The hydrologic and hydraulic modeling analyses of the current stormwater system identified several areas throughout the City where the desired 1-percent-annual chance event (100-year) level of protection may not be provided. These problem areas and potential solutions are discussed in detail in Appendix A and are summarized and prioritized in Table 3.6. In addition to evaluating the level of protection provided by the current stormwater system, the level of service provided was also evaluated. From this analysis, it was determined that the storm sewer throughout many areas of the City is not currently providing the desired 10-percent-annual-chance event (10-year) level of service. The areas where the storm sewer does not offer sufficient capacity and street flow occurs during a 10-percent-annual-chance event may be viewed via the City’s interactive web map. The capacity of these storm sewer systems should be evaluated and upgraded, where feasible, as opportunities arise. 1.2 Flood Risk Management The City of Edina developed a Flood Risk Reduction Strategy that outlines a plan for working toward reducing flood risk. The strategy identifies and characterizes flood problems throughout the city and identifies strategies and infrastructure improvements to address flood-prone areas. The strategy includes preparation of planning-level cost estimates to help understand the potential financial investment required to meet the City’s flood risk reduction goals and the anticipated timeframe for implementation. The Flood Risk Reduction Strategy has been incorporated into this WRMP (see Section 3.3) and details the City’s approach to addressing flood-prone areas based on the sectors of work described in Section 3.3.4 (and illustrated below). City of Edina 2022 Water Resources Management Plan 1-3 Figure 1.1 Sectors of Work and City Goals The City’s Flood Risk Reduction Strategy focuses on identification and prioritization of flood exposure and vulnerability reduction efforts. The City seeks to maximize cost effectiveness and capitalize on coinciding opportunities, such as planned street reconstruction, redevelopment, availability of land, and other planned infrastructure improvement projects. Consideration will also be given to achieving additional “co- benefits”, such as water quality improvements, open space expansion, and ecological restoration. 1.3 Clean Water Management As part of this 10-year plan, the City of Edina will develop a clean water strategy that outlines a plan for working toward meeting its clean water goals. The strategy will address the City’s approach to meeting the pollutant reduction targets identified through the Total Maximum Daily Load (TMDL) and Watershed Restoration and Protection Strategy (WRAPS) process. The strategy will also determine pollutant load reduction targets for nondegradation of water bodies that are not impaired and identify an approach for achieving these stormwater management targets. The clean water implementation strategy will define the City’s goals and identify regular “good housekeeping” stormwater practices and clean water capital improvement projects (CIP) to achieve the clean water goals, including quantification of pollutant removals and preparation of planning-level cost estimates. This information will be used for planning, as well as assessment of cost-benefit for project prioritization. The implementation strategy will be developed in coordination with street reconstruction projects, redevelopment, and other opportunities. Annual or biennial reporting will be included in the strategy to quantify movement toward the City’s goals and will include tracking activities for the City’s annual SWPPP and MS4 reporting. City of Edina 2022 Water Resources Management Plan 1-4 The Clean Water Strategy will define clean water goals, estimate the cost and pace of achievement, and identify implementation opportunities based on implementation categories described in Section 3.4 including: • Redevelopment • Retrofit • Re-design/re-purpose When completed, the Clean Water Strategy will be included as an amendment to this WRMP. Each of the clean water improvement opportunity categories identified above and described in Section 3.4 have opportunities for partnership with other entities, such as private landowners, watershed districts, non- profit organizations, or other local governmental entities. City of Edina 2022 Water Resources Management Plan 2-1 2.0 Introduction and Physical Setting 2.1 Plan Purposes This plan update provides the City of Edina with a Water Resources Management Plan (WRMP). The plan was developed to address current and future stormwater issues, especially those related to future development and redevelopment. The plan addresses flood risk and stormwater runoff management, clean water services, and natural resources restoration and protection through establishment of water resources planning policies and recommendations for projects and programs. The WRMP fulfills the City’s local water planning obligations under Minnesota Statutes 103B.245. The first goal of this WRMP is to provide flood risk management and stormwater runoff management strategies. The City takes action to reduce the risk of losses due to floods, to minimize the impact of floods on human safety, health and welfare, and to restore and preserve the natural and beneficial values served by floodplains. The primary goal for the City’s flood risk management and stormwater runoff management programs is to improve public safety and reduce the exposure of private principal structure to flooding. The flood risk reduction strategy is described further in Section 3.0. The policies are discussed in Section 4.0. The current storm sewer system throughout the City has been analyzed using computer simulation models and recommendations to improve runoff management and reduce flood risk have been made. Discussion on the stormwater modeling analyses and the resulting implementation recommendations is included in Appendix A. The second goal of the WRMP is to document clean water services for the waterbodies throughout the City. Clean water policies and design standards have been established to protect the water quality of the waterbodies within the City. These policies and design standards are discussed in Section 4.2. A water quality model was used to simulate the generation and transport of pollutants through the waterbodies within the City. The model results were used to make recommendations for upgrades to constructed stormwater ponds throughout the City to maintain and improve the pollutant removal efficiency from these stormwater assets. This analysis and the resulting implementation recommendations are discussed in Appendix A. The third goal of the WRMP is to provide natural resources restoration and protection strategies. The City’s goal is to protect and improve natural systems including creeks, lakes, wetlands, and groundwater. To achieve this goal, policies have been established to protect natural resources within the City. These policies are included in Section 4.2 through Section 4.5. This plan will assist the City of Edina in defining and implementing a comprehensive and environmentally sound system of surface water management. It is intended to be used as a tool to: 1. Plan for projects and other water management activities so as to correct existing problems and prevent foreseeable future problems from occurring. City of Edina 2022 Water Resources Management Plan 2-2 2. Assist the City in considering water resource impacts resulting from variances to the City’s long- range land use plan. 3. Enable the City to grow/redevelop in a systematic and orderly manner while protecting its vital water resources. In order to accomplish these objectives, the plan considers a specific array of land uses within the City limits. If and when land uses change, this plan provides the means to (1) address the proposed changes; (2) determine the impact of the changes on the City’s infrastructure, flooding, and natural resources; and (3) determine the actions needed within the proposed areas of land use change to prevent undesirable impacts. Notwithstanding anything to the contrary stated herein, the City of Edina shall have the right to act exclusively in the interest of Public and shall have no duty or obligation of any type or nature whatsoever emanating from this plan to person or class of persons. This plan is intended to describe the existing and proposed physical environment and land use; define drainage areas and the volumes, rates, and paths of stormwater runoff; identify areas and elevations for stormwater storage adequate to meet performance standards; define water quality and water quality protection methods adequate to meet performance standards; identify regulated areas; and set forth an implementation program, including a description of official controls and, as appropriate, a capital improvement program. This plan contains a compilation of goals and policies to achieve Edina's vision for the entire community (not a specific class of persons), as well as implementation steps, which emanate from the goals and policies. This plan is NOT intended to create any obligations with respect to a specific person or class of persons, and therefore DOES NOT create any legally enforceable obligations or duties in the City of Edina on behalf of any person or class of persons. Additionally, the goals and policies stated herein are subject to change in the sole discretion of the City of Edina City Council and therefore this plan does not create any expectation, obligation, or legally enforceable duty with respect to a specific person, class of persons, or the entire public. 2.2 Physical Setting 2.2.1 Drainage Patterns The City of Edina covers an area of approximately 16 square miles. There are two stream systems that flow through the City: Nine Mile Creek and Minnehaha Creek. The northeast corner of the City drains to Minnehaha Creek, which enters the City limits northwest of West 44th Street and Trunk Highway (TH) 100 and flows in a southeasterly direction through the City, exiting near West 54th Street and York Avenue. The southwest corner of the City drains to the South Fork of Nine Mile Creek through a series of storm sewer networks, ditches, and stormwater detention basins. The remainder of the City drains to the North Fork of Nine Mile Creek, which enters the Edina City limits in the northwest corner of the City near the Various maps related to the City of Edina can be found online at the City’s “Maps” page: https://www.edinamn.gov/894/Maps City of Edina 2022 Water Resources Management Plan 2-3 intersection of TH 169 and Londonderry Road and meanders in a southeasterly direction through the City and exits the City limits near the intersection of TH 100 and Interstate 494 (I-494). For water resource planning purposes, the City was divided into several major drainage areas based on drainage patterns. These drainage areas are depicted in Figure 2.1 and listed below: • Nine Mile Creek- North • Nine Mile Creek- Central • Lake Cornelia/Lake Edina/Adam’s Hill Pond • Nine Mile Creek- South • Nine Mile South Fork • Southwest Ponds • TH 169 North • Northeast Minnehaha Creek • Southeast Minnehaha Creek • Northwest Minnehaha Creek 2.2.1.1 Hydrologic Modeling of Major Drainage Areas Appendix A discusses the drainage patterns within each of these major drainage areas and describe the recommended stormwater system improvements for each area. In some cases, the drainage areas may include portions of adjoining cities, including Hopkins, Minnetonka, Eden Prairie, Bloomington, Richfield, and Minneapolis. The 10 major drainage areas listed above were further subdivided into major watersheds and subwatersheds. Watershed divides were originally determined as part of the 2003 WRMP using air- flown 2-foot topographic data. For the 2018 plan update, watershed divides were reviewed and, in some cases, were updated using newer data topographic data (2011 MnDNR LiDAR elevation data). The watershed divides are also updated on an annual basis through the City’s annual stormwater model update process. The City has modeled each of the 10 major drainage areas using the U.S. EPA’s Stormwater Management Model (SWMM), with a computerized graphical interface provided by XP Software/Innovyze (XPSWMM). XPSWMM uses rainfall and watershed characteristics to generate local runoff, which is routed through pipe and overland flow networks. The model can account for detention in ponding areas, backflow in pipes, surcharging of manholes, as well as tailwater conditions that may exist and affect upstream storage or pipe flows. XPSWMM 2014, was used to model the storm sewer, ponding and overland flow systems within the City of Edina. Since 2018, some detailed study areas in the City utilized 2-dimensional (2D) modeling in XPSWMM to add additional detail and more accurately reflect hydrologic and hydraulic conditions. These detailed study areas are maintained in separate models and integrated into the citywide inundation mapping. Additional detail regarding modeling methodology is provided in Appendix A. City of Edina 2022 Water Resources Management Plan 2-4 2.2.2 Watershed Management Organizations Edina lies within two major watersheds: the Minnehaha Creek watershed and Nine Mile Creek watershed. As a result, two watershed management organizations cover Edina, each with its own governing body. Additional information on the Minnehaha Creek Watershed District and Nine Mile Creek Watershed District is provided below. 2.2.2.1 Minnehaha Creek Watershed District The Minnehaha Creek Watershed District (MCWD) spans approximately 180 square miles and consists of 27 cities and three townships on the western edge of the Twin Cities area. The watershed includes eight major creeks, including Minnehaha Creek which meanders through the northeastern part of Edina. The MCWD also includes 129 lakes, including Lake Harvey and Melody Lake, and thousands of wetlands. The MCWD adopted their most recent watershed management plan (Minnehaha Creek Watershed District Watershed Management Plan) on January 11, 2018. More information is available at the MCWD website: www.minnehahacreek.org. 2.2.2.2 Nine Mile Creek Watershed District The Nine Mile Creek Watershed District (NMCWD) is approximately 50 square miles and encompasses the land area draining to Nine Mile Creek, including portions of Bloomington, Eden Prairie, Edina, Hopkins, Minnetonka, and Richfield. Portions of the North Fork and South Fork of Nine Mile Creek flow through Edina. The NMCWD also includes over 20 lakes, including Lake Edina, Lake Cornelia, Arrowhead Lake, Indianhead Lake, Hawkes Lake, Highlands Lake, and Mirror Lake, and many wetlands. The NMCWD adopted their most recent watershed management plan (Nine Mile Creek Watershed District Water Management Plan) on October 18, 2017. More information is available at the NMCWD’s website: http://www.ninemilecreek.org/ 2.2.3 Land Use The city of Edina is fully urbanized. Less than 1 percent of the developable area within the city, not including wetland, floodplain, or park land uses, remains available for development. Figure 2.2 shows the land use classifications for the city. The 2018 Edina Comprehensive Plan provides additional information about the existing and projected (2040) land uses in the city. The projected 2040 land use is provided online via the City’s “Maps” page, when available. 2.2.4 Soils The infiltration capacity of soils affects the amount of direct runoff resulting from rainfall. Soils with a higher infiltration rate have a lower runoff potential. Conversely, soils with low infiltration rates produce high runoff volumes and high peak runoff rates. According to the Hennepin County soil survey, the underlying soils in the City of Edina are predominantly classified as hydrologic soil group B, with moderate infiltration rates. The underlying soils in the southern portions of the City are classified as hydrologic soil group A, characterized by high infiltration rates. The underlying soils surrounding the floodplain of Nine Mile Creek and Minnehaha Creek and around many of the natural wetlands within the City are classified City of Edina 2022 Water Resources Management Plan 2-5 as hydrologic soil group D, with very slow infiltration rates. Figure 2.3 depicts the hydrologic soils group classification for soils within the City of Edina. 2.2.5 Topography The topography of the City varies from relatively flat land along portions of Nine Mile Creek and Minnehaha Creek to very hilly land in the southwest portion of the City. Generally, the topography throughout the City consists of moderately rolling hills. The elevations generally vary from 980 to 880 feet (National Geodetic Vertical Datum of 1929 or NGVD 29) at the divide between the Minnehaha Creek and Nine Mile Creek watersheds to elevations between 812 and 850 feet where each creek exits the City. The City of Edina has older 2-foot contour data (Markhurd, 2000) coverage for the entire City; this information was used for the 2003 WRMP and is available from the City Engineering Department. The MnDNR has newer (2011) and higher resolution Light Detection and Ranging (LiDAR) topographic data that was used for this plan update. 2.2.6 Water Quality 2.2.6.1 Water Quality Monitoring Lake Monitoring While the City of Edina does not have a water quality monitoring program, several lakes and streams within the city are monitored periodically by watershed districts and volunteer programs. The NMCWD conducts periodic monitoring of several lakes within the city, including Arrowhead Lake, Lake Cornelia, Lake Edina, Indianhead Lake, and Mirror Lake. The NMCWD’s lake monitoring program includes analysis of a range of parameters, including phosphorus, nitrogen, chlorophyll a, chlorides, clarity/transparency, temperature, pH, specific conductivity and dissolved oxygen. In addition, the NMCWD typically completes phytoplankton (algae) and zooplankton monitoring and conducts early-summer and late-summer aquatic plant (macrophyte) surveys. In addition to the lake monitoring data collected by the NMCWD, water quality data has also been collected for several lakes by resident monitoring volunteers as part of the Metropolitan Council’s Citizen- Assisted Monitoring Program (CAMP). The lakes within the city that have been monitored as part of CAMP include Pamela, Cornelia, Edina, Harvey, and Hawkes lakes. The locations of these lakes are shown in Figure 2.4. Volunteer monitoring through the CAMP program has historically been funded by the watershed districts. A summary of the historic summer average total phosphorus concentrations for the monitored lakes in Edina is provided in Table 2.1. The summary reflects the data collected by both the NMCWD and the Metropolitan Council CAMP over the most recent ten years when data was collected. As can be seen in the table, the available data is limited for many of the Edina lakes. It should be noted that lakes and ponds are dynamic, so that relatively infrequent sampling cannot provide a complete picture of the status of the water body in question. The situation is further complicated by the impossibility of inferring statistically City of Edina 2022 Water Resources Management Plan 2-6 significant trends from relatively few water quality sampling results. A minimum of about 10 (summer average) data points is thought to be required to reliably identify a water quality trend. Creek Monitoring The NMCWD has two continuous flow monitoring stations within or near Edina; one along the North Fork of Nine Mile Creek at the Metro Boulevard crossing, and another along the South Fork of Nine Mile Creek at the 78th Street crossing, just south of the city boundary with Bloomington (see Figure 2.4). The monitoring stations collect data on stream flow and several water quality parameters, including turbidity, nutrients, and chlorides. The water quality monitoring data is available from the NMCWD upon request. The MCWD has two monitoring stations along Minnehaha Creek; one near the intersection of West 56th Street and Woodland Drive, just west of France Avenue, and another at Mill Pond, upstream of Browndale Dam. The west 56th Street station has consistently been monitored since 2009. MCWD had a third station, just below Browndale Dam, beginning in 1996. This station was discontinued in 2016. Continuous stream level data is collected to determine stream flow at the Mill Pond station. Instantaneous discharge and water quality samples are collected bi-weekly at the West 56th Street station. Samples are analyzed bi-weekly for total phosphorus and total suspended solids (TSS), and monthly for chloride during the months of March-October. E. coli is collected weekly during the months of April – October. Samples are analyzed monthly during the winter (November-February). Table 2.1 Summer (June-September) Average Total Phosphorus Concentrations for Edina Lakes Lake Year Summer Average Total Phosphorus Concentration (µg/L) Data Collection Entity 1,2 North Lake Cornelia 2007 211 MCES CAMP 2008 153 NMCWD and MCES CAMP 2009 111 MCES CAMP 2013 165 NMCWD and MCES CAMP 2014 84 MCES CAMP 2015 139 NMCWD and MCES CAMP 2016 114 NMCWD 2017 197 NMCWD 2020 150 NMCWD 2021 161 NMCWD Average3 141 South Lake Cornelia 2008 150 NMCWD 2013 114 NMCWD 2015 122 NMCWD 2016 149 NMCWD City of Edina 2022 Water Resources Management Plan 2-7 Lake Year Summer Average Total Phosphorus Concentration (µg/L) Data Collection Entity 1,2 2017 174 NMCWD 2020 97 NMCWD 2021 97 NMCWD Average3 121 Mirror Lake 2004 119 NMCWD 2012 104 NMCWD 2019 89 NMCWD 2021 98 NMCWD Average3 97 Arrowhead Lake 2011 52 NMCWD 2014 65 NMCWD 2019 74 NMCWD 2020 80 NMCWD Average3 68 Indianhead Lake 2011 53 NMCWD 2014 61 NMCWD 2019 146 NMCWD 2020 115 NMCWD Average3 94 Harvey Lake 2011 53 CAMP Average3 53 Pamela Lake 2004 78 CAMP 2005 73 CAMP Average3 76 Lake Edina 2008 120 NMCWD 2012 146 NMCWD 2015 85 NMCWD 2017 77 NMCWD 2020 126 NMCWD 2021 189 NMCWD Average3 124 1 Metropolitan Council Environmental Services (MCES) Citizen Assisted Monitoring Program (CAMP) for Lakes 2 Nine Mile Creek Watershed District (NMCWD) lake monitoring program 3 Average based on 10-year period dating from most recent data City of Edina 2022 Water Resources Management Plan 2-8 2.2.6.2 Impaired Waters and Total Maximum Daily Loads The federal Clean Water Act (CWA) requires states to adopt water quality standards to protect the nation’s waters. Water quality standards designate beneficial uses for each waterbody and establish criteria that must be met within the waterbody to maintain the water quality necessary to support its designated use(s). Section 303(d) of the CWA requires each state to identify and establish priority rankings for waters that do not meet the water quality standards. The list of impaired waters, or 303(d) list, is updated by the state every two years. For impaired waterbodies, the CWA requires the development of a total maximum daily load (TMDL). A TMDL is a threshold calculation of the amount of a pollutant that a waterbody can receive and still meet water quality standards. A TMDL establishes the pollutant loading capacity within a waterbody and develops an allocation scheme amongst the various contributors, which include point sources, non-point sources and natural background, as well as a margin of safety. As a part of the allocation scheme a waste load allocation is developed to determine allowable pollutant loadings from individual point sources (including loads from storm sewer networks), and a load allocation also establishes allowable pollutant loadings from non-point sources and natural background levels in a waterbody. Impaired waters located within the City of Edina, as identified by the MPCA’s 2022 Impaired Waters List, include: Lake Cornelia (North Basin), Lake Cornelia (South Basin), Lake Edina, Nine Mile Creek (South Fork), Nine Mile Creek (from headwaters to Metro Boulevard and between Metro Boulevard and an unnamed wetland) and Minnehaha Creek. These waterbodies are listed in Table 2.2 along with the affected MPCA designated use, the pollutant or stressor that is not meeting the MPCA water quality criteria, and the MPCA target for starting and completing the TMDL process. The MPCA is using a systematic watershed approach to address impaired waters and TMDLs, whereas intensive water quality monitoring and assessments are being conducted in each of the states 80 major watersheds during a 10-year cycle. The MPCA developed a process termed Watershed Restoration and Protection Strategy (WRAPS) to identify and address water quality threats in each major watershed. The four primary steps of the WRAPS process include 1) monitoring water quality and collecting data, 2) assessing the data, 3) developing strategies to restore and protect water bodies within the watershed, and 4) conducting restoration and protection projects. TMDLs are conducted for impaired water bodies as part of the WRAPS process. The MPCA completed a WRAPS study addressing the Lower Minnesota River in 2017 that included the Nine Mile Creek watershed. The City of Edina participated in the process as a stakeholder. Building off of the Lower Minnesota River WRAPS, the MPCA completed the Lower Minnesota River Watershed TMDL Part II – Northern Watersheds (MPCA, February 2020). The TMDL addresses Lake Cornelia (North and South basins), Lake Edina, and Nine Mile Creek. TMDL requirements and associated wasteload allocations are incorporated into the City’s NPDES Phase II MS4 permit. The City may amend this WRMP to incorporate future TMDL requirements, as needed. City of Edina 2022 Water Resources Management Plan 2-9 Table 2.2 City of Edina Waterbodies on MPCA's 303(d) Impaired Waters List Reach/Waterbody1 Description Affected Use Pollutant or Stressor Target Dates for Completing TMDL Lake Cornelia (North Basin) Aquatic Recreation Nutrient/Eutrophication Biological Indicators 20222 Lake Cornelia (South Basin) Aquatic Recreation Nutrient/Eutrophication Biological Indicators 20202 Lake Edina Aquatic Recreation Nutrient/Eutrophication Biological Indicators 20222 Nine Mile Creek Headwaters to Metro Boulevard Aquatic Life Fish Bioassessments 2028 Nine Mile Creek Metro Boulevard to end of unnamed wetland Aquatic Life Aquatic macroinvertebrate bioassessments 2028 Nine Mile Creek Metro Boulevard to end of unnamed wetland Aquatic Life Fish Bioassessments 2028 Nine Mile Creek (South Fork) Smetana Lake to Nine Mile Creek Aquatic Life Aquatic macroinvertebrate bioassessments 2024/2028 Nine Mile Creek (South Fork) Smetana Lake to Nine Mile Creek Aquatic Life Fish Bioassessments 2024/2028 Minnehaha Creek Lake Minnetonka to Mississippi River Aquatic Life Aquatic Macroinvertebrate Bioassessments 2024 Minnehaha Creek Headwaters to Minnesota River Aquatic Life Fish Bioassessments 2024 Minnehaha Creek Lake Minnetonka to Mississippi River Aquatic Recreation Fecal Coliform 20133 Minnehaha Creek Lake Minnetonka to Mississippi River Aquatic Life Chloride 20164 Minnehaha Creek Lake Minnetonka to Mississippi River Aquatic Life Dissolved Oxygen 2024 1 Information based on the 2022 impaired waters list, finalized April 29, 2022. 2 Impairment addressed by Lower Minnesota River TMDL – Part II: Northern Watersheds (February, 2020). 3 Impairment addressed by Minnehaha Creek Bacteria and Lake Hiawatha Nutrients TMDL (October, 2013). 4 Impairment addressed by Twin Cities Metro Area Chloride TMDL (February, 2016). City of Edina 2022 Water Resources Management Plan 2-10 Nine Mile Creek Nine Mile Creek is currently on the 303(d) Impaired Waters List for an aquatic life impairment due to a fish biota impairment. In 2009, the MPCA and NMCWD began development of a TMDL to address the biotic impairment. The City of Edina participated as a stakeholder in the TMDL process. The TMDL included a biological stressor identification study to determine the causes of the Nine Mile Creek biological impairment for fish (MPCA, 2010). The study concluded: • The probable cause of impairment on the South Fork of Nine Mile Creek is inadequate dissolved oxygen. Although the impairment can be caused by numerous stressors, the data suggests that inadequate dissolved oxygen is the most prominent of the stressors, followed by excess sediment and inadequate base flow. • The probable causes of impairment on the North Fork of Nine Mile Creek are inadequate dissolved oxygen and excess sediment. In 2004, the MPCA determined that Nine Mile Creek did not meet the chloride standard for streams and listed Nine Mile Creek as impaired. A TMDL was completed in 2010 to identify management measures to reduce chloride levels in Nine Mile Creek. The study determined that a 63% reduction in the existing watershed chloride load estimated for Nine Mile Creek would be required, to be achieved through management of road salt inputs from both road authorities and commercial and private applicators. The NMCWD requires applicants for permit under its stormwater management rule (excluding single family homes) to complete a chloride management plan that designates chloride applicators that are MPCA- certified. More information about the NMCWD’s chloride reduction efforts is available at: https://www.ninemilecreek.org/get-involved/learn/salt-reduction/. The City has also invested in training, public education, technology upgrades, technical assistance, and equipment replacement/retrofits to reduce salt loading. Minnehaha Creek and Lake Hiawatha Minnehaha Creek is currently on the 303(d) list for several impairments, including an aquatic life impairment due to fish biota, aquatic macroinvertebrates, chloride, and dissolved oxygen and an aquatic recreation impairment due to fecal coliform. Lake Hiawatha, located on Minnehaha Creek downstream of the City of Edina, is also on the impaired waters list for excess nutrients and eutrophication biological indicators. The MPCA and MCWD initiated the TMDL development process in 2009 to address an E. coli bacteria impairment (originally listed as fecal coliform) in Minnehaha Creek and a nutrient impairment in downstream Lake Hiawatha. The City of Edina participated in the stakeholder process. The TMDL, approved in 2014, includes a categorical E. coli wasteload allocation for all MS4s within the watershed and a 50% total phosphorus load reduction target to Minnehaha Creek (MPCA, 2013). An individual wasteload allocation of 50%, or 424 lbs total phosphorus from June 1 through September 30, has been assigned to the City. City of Edina 2022 Water Resources Management Plan 2-11 The chloride impairment for Minnehaha Creek is being addressed as part of the Twin Cities Metropolitan Area Chloride Total Maximum Daily Load Study (MPCA, 2016). The MPCA’s 2016 proposed 303(d) list also includes an aquatic life impairment for Minnehaha Creek due to low dissolved oxygen levels. Lake Cornelia Lake Cornelia (North Basin) and Lake Cornelia (South Basin) are included on the MPCA’s 2022 Impaired Waters list for excess nutrients and eutrophication biological indicators. The Lake Cornelia impairments are addressed as part of the Lower Minnesota River WRAPS and TMDL – Part II: Northern Watersheds led by the MPCA and NMCWD and completed in 2020. A wasteload allocation of 93 lbs of total phosphorus reduction from June 1 to September 30 is assigned to the City, corresponding to a 49% reduction in loading. In 2004–2005, the NMCWD completed a draft use attainability analysis (UAA) for Lake Cornelia, which is a scientific assessment of a water body’s physical, chemical, and biological condition (Barr Engineering, 2006). The study included a water quality assessment and prescription of protective and/or remedial measures for the lake and its tributary watershed. In 2010 and again in 2019, the NMCWD updated the UAA based on additional lake water quality data, to verify the conclusions of the prior UAAs and evaluate several additional remedial measures to improve lake water quality (NMCWD, July 2019). In 2020, the NMCWD completed a feasibility study to evaluate potential Lake Cornelia water quality improvement actions (NMCWD, July 2020). The NMCWD performed an in-lake alum treatment in 2020 to reduce internal phosphorus loading from lake sediment and constructed a stormwater filtration BMP in Rosland Park to treat stormwater entering Lake Cornelia. Since 2017, the City has managed curlyleaf pondweed in Lake Cornelia, an invasive species and source of phosphorus. The City of Edina will continue to partner with the NMCWD in implementing potential remedial measures for the lake(s) and its watershed recommended as part of the NMCWD UAA, MPCA WRAPS, and subsequent applicable studies to improve the water quality of Lake Cornelia. Lake Edina Lake Edina is included on the MPCA’s Impaired Waters list for excess nutrients and eutrophication biological indicators. The Lake Edina impairment is addressed as part of the Lower Minnesota River WRAPS and TMDL – Part II: Northern Watersheds led by the MPCA and NMCWD and completed in 2020. A wasteload allocation of 74 lbs of total phosphorus reduction from June 1 to September 30 is assigned to the City, corresponding to a 34% reduction in loading. In 2019, the NMCWD updated the Lake Cornelia UAA to include Lake Edina – the UAA evaluates possible measures to improve lake water quality (NMCWD, July 2019). In 2020, the NMCWD completed a feasibility study to further evaluate potential water quality improvement actions for Lake Edina (NMCWD, July 2020). As of 2022, a stormwater treatment retrofit of Lynmar Basin is under construction in the Lake Edina City of Edina 2022 Water Resources Management Plan 2-12 watershed. Due to Lake Edina’s location downstream of Lake Cornelia, City and NMCWD efforts to improve Lake Cornelia water quality are anticipated to benefit Lake Edina water quality. The City of Edina will continue to partner with the NMCWD in identifying and implementing potential remedial measures for the lake and its watershed recommended in the NMCWD UAA, MPCA WRAPS, and subsequent applicable studies to improve the water quality of Lake Edina. Other Downstream Waterbodies There are also impaired lakes and streams outside the City that receive stormwater from Edina and are the subject of completed or future TMDL studies, including Lake Hiawatha, the Mississippi and Minnesota Rivers, and Lake Pepin. The City has been assigned a wasteload allocation to address the Lake Hiawatha TMDL. The City has also been assigned a categorical wasteload allocation from the South Metro Mississippi River Total Suspended Solids (TSS) TMDL of 154 lbs/acre/year. The City is currently meeting this TSS wasteload allocation. The City is also subject to a 0.35 lbs/acre/year of total phosphorus categorical wasteload allocation stemming from the Lake Pepin and Mississippi River Eutrophication TMLD (MPCA, April 2021). The City may need to amend the WRMP to implement future requirements related to any downstream water body. 2.2.7 Wetlands The wetlands in the City of Edina are an important community asset. These resources supply aesthetic and recreational benefits, in addition to providing wildlife habitat and refuge. To provide a basis for wetland protection efforts, the City completed a planning-level inventory and field assessment of all the wetlands within the City in 1999. In 2003, the MCWD developed a Functional Assessment of Wetlands (FAW) to provide a comprehensive inventory and assessment of existing wetland functions within the district. The City adopts the MCWD FAW for portions of the City within the Minnehaha Creek Watershed. Figure 2.5 depicts the wetlands that were identified and assessed as part of these two wetland inventories. Note that the wetlands identified within the MCWD are based on the 2003 FAW, and the remainder are based on the City’s 1999 planning-level inventory. 2.2.7.1 City of Edina Wetlands Inventory—1999 The City used a modified version of the Minnesota Routine Assessment Method for Evaluating Wetland Functions (commonly referred to as "MnRAM") version 2.0 to assess wetlands in the City. A description of the modified MnRAM version 2.0 and associated field data sheets are included in Appendix F and Appendix G of the 2018 City of Edina Comprehensive Water Resources Management Plan. The City’s 1999 wetland survey evaluated dominant vegetation and the following functions and values: • Hydrology • Vegetative diversity • Wildlife habitat City of Edina 2022 Water Resources Management Plan 2-13 • Fishery habitat • Flood/stormwater attenuation • Water quality protection • Shoreline protection • Aesthetics, recreation, and educational value The City inventory also evaluated the sensitivity of wetlands to stormwater inputs based on wetland type and developed management recommendations for bounce (i.e., water level increase), discharge rate, and inundation period based on wetland sensitivity to stormwater inputs. 2.2.7.2 MCWD FAW—2003 In 2001-2003, the MCWD undertook a FAW within the entire MCWD, which covers the northeast portion of the City of Edina. This assessment included the evaluation of the majority of wetlands within the MCWD including the verification of the presence of a wetland, the mapping of the approximate wetland boundary, and assessment of wetland functions. More information is available from the MCWD at: https://www.minnehahacreek.org/ 2.2.8 Public Waters The MnDNR has designated certain waters of the state as public waters (Minn. Rules 6115.1060). MnDNR “Public Waters Inventory (PWI)” maps show public waters within the City. A MnDNR permit is required for work that would alter the course, current, or cross-section of a designated public water. PWI maps show public waters as one of the following: public water basin; public water wetland; public water watercourse; or, public ditch/altered natural watercourse. Table 2.4 lists the MnDNR Public Waters within the city. The table includes the MnDNR identifier for each pond, as well as the corresponding subwatershed for this stormwater study. Public water basins are identified with a number and the letter “P”. Public water wetlands are identified with a number and the letter “W”. Public wetlands include, and are limited to, Type 3, 4, and 5 wetlands that have been designated as public waters and are 2½ acres or more in size (10 acres in unincorporated areas). More information about public waters classification is available from the MDNR at: https://www.dnr.state.mn.us/waters/watermgmt_section/pwi/maps.html Public water courses and ditches in Edina include: • Minnehaha Creek • North Fork of Nine Mile Creek • South Fork of Nine Mile Creek • Braemar Branch of Nine Mile Creek City of Edina 2022 Water Resources Management Plan 2-14 Table 2.3 MnDNR Public Waters within Edina Waterbody ID Public Waters Class Public Waters or Local Name Corresponding Subwatershed ID(s) Known MnDNR OHWL (vertical datum) 27002801 P Cornelia (North) NC_62 27002802 P Cornelia (South) SC_1 27002900 P Lake Edina LE_1 27004100 P Edina Mill Pond MHC_ 2 27004400 P Indianhead Lake IH_1 863.7 (NGVD29) 27004500 P Arrowhead Lake AH_1 875.8 (NGVD29) 27005000 P Bredesen MD_50, MD_1 27005400 P Meadowbrook Lake Outside City subwatersheds 27005500 P Mirror Lake ML_1, ML_32 27005600 P Hawkes Lake HL_1 27066600 W EI_19 27066700 W Annaway Pond EI_1 27066800 P Highlands Park Pond HI_1 27066900 W Melody Lake ML_8 886.9 (NAVD88) 27067000 W Lake Harvey MHS_22 27067100 P Birchcrest NMC_112 27067200 W CO_1 27067300 P Heights EdCrk11 27067400 W NMC_77 27067500 P Pamela Pond LP_26 27067600 W West Garrison Pond NC_5 27067700 W Nancy NC_2 27067800 W Otto Pond NC_30 27067900 W Swim Pool Pond NC_3 27068000 W Point of France Pond NC_4 27078000 W EI_32 27078100 W ML_28 City of Edina 2022 Water Resources Management Plan 2-15 Waterbody ID Public Waters Class Public Waters or Local Name Corresponding Subwatershed ID(s) Known MnDNR OHWL (vertical datum) 27078200 W ML_16 27079900 W NMN_76, NMN_55 27080000 W NMN_75 27080100 W NMN_50 27080200 W MD_25 27080300 W MD_21 27080400 W EdCrk3 27080500 W Habitat Pond NMN_24 27080600 W Pauly's Pond AH_6 27080700 W Garrison Pond EP_2 27080800 W EP_2 27101300 W BRCrk4, BRCrk14, BRCrk15, BRCrk16, BRCrk17, BRCrk18 27103800 W SWP_3 27103900 W SWP_5, SWP_14, SWP_35 27104000 W SWP_1, SWP_2, SWP_4 27104100 W NMS_3 27110600 W EdCrk5 2.2.9 Parks, Recreation, and Natural Resources Open Space The City of Edina has numerous community parks, neighborhood parks, and other public open space recreational areas. Figure 2.6 shows the numerous parks and recreational areas within the City of Edina. Lakes, ponds, and creeks are often key attractions in public parks; examples within Edina include Arden Park, Bredesen Park, Pamela Park, Rosland Park, Utley Park, Centennial Lakes Park, and Weber Park. The City of Edina currently owns and maintains approximately 350 acres of natural resource open space areas, which includes 148 acres along the Nine Mile Creek right-of-way and 23 acres along the Minnehaha Creek right-of-way. The city is basically fully developed and is therefore no longer actively acquiring additional property to develop as park land or open space. However, the City plans to retain all of the current publicly owned park land and consider any additional property that may be offered in the future as potential additional park property. The City will also seek to acquire additional park and open space land City of Edina 2022 Water Resources Management Plan 2-16 as more private land becomes available for public acquisition. Additional parks information is available in the City’s Comprehensive Plan. 2.2.10 Public Utilities Edina is completely within the Metropolitan Council’s designated Metropolitan Urban Service Area (MUSA). The MUSA is the area in the seven county metro area in which the Metropolitan Council ensures that regional services and facilities are provided or planned. The City of Edina provides sanitary sewer and water service throughout the City. 2.2.11 Fish and Wildlife Habitat The waterbodies and open spaces interspersed throughout the City provide habitat for numerous fish and wildlife species, including birds, mammals, and reptiles. Ducks and geese are present in large numbers at lakes, wetlands, and open water areas. Vegetative cover in the undeveloped open areas support many mammalian species such as deer, raccoon, squirrels, fox, chipmunks, and rabbits. The wetlands in Edina provide habitat for a variety of aquatic species including snakes, turtles, and frogs. The Minnesota Department of Natural Resources (MnDNR) has completed fishery surveys of four lakes within the City of Edina. The most recent surveys were of Lake Cornelia in 2019 and Centennial Lake in 2011. Both of these lakes are part of the MnDNR’s Fishing in the Neighborhood program. Lake Cornelia and Centennial Lake have been stocked by the MnDNR, and Arrowhead Lake and Indianhead Lake have been stocked by residents in cooperation with the MnDNR in recent years. Table 2.3 summarizes the available fishery survey, stocking, and aquatic invasive species information available for the waterbodies within the City of Edina. Invasive species observed within City lakes and Minnehaha Creek (and the year identified, if known) include: • Arrowhead Lake: curlyleaf pondweed, Eurasian watermilfoil (1995), purple loosestrife • Indianhead Lake: curlyleaf pondweed, purple loosestrife, yellow iris • Lake Cornelia: curlyleaf pondweed, Eurasian watermilfoil, purple loosestrife, hybrid cattail, goldfish, common carp • Lake Edina: curlyleaf pondweed, Eurasian watermilfoil, • Lake Nancy: curlyleaf pondweed • Melody Lake: curlyleaf pondweed • Mirror Lake: curlyleaf pondweed • Minnehaha Creek Meadowbrook Creek: zebra mussels (2010) • Minnehaha Creek Mill Pond: Eurasian watermilfoil, purple loosestrife, curlyleaf pondweed zebra mussels (2010) • Minnehaha Creek: Eurasian watermilfoil (1989), flowering rush (2009), zebra mussels (2010) Invasive species information is based on City macrophyte surveys and the MnDNR List of Infested Waters website at: http://www.eddmaps.org/midwest/tools/infestedwaters/ City of Edina 2022 Water Resources Management Plan 2-17 Table 2.4 Fishery and Aquatic Invasive Species Information Water Resource Survey Year Fishery 1 Stocking 2 Dominant Fish Species Lakes Lake Cornelia 2005 Bluegill: 2001-2005 Bluegill, Black Crappie, Carp 2010 Bluegill: 2007-2010 Black Bullhead 2019 Bluegill: 2011-2012, 2014-2016 Black Crappie: 2014 Hybrid Sunfish: 2014 Pumpkinseed Sunfish: 2014 Black Bullhead, Green Sunfish 2020 Bluegill: 2020-2021 Black Bullhead, Green Sunfish, Hybrid Sunfish Arrowhead Lake 1995 Bluegill: 1994 Black Bullhead, Green Sunfish 2021 Bluegill: 2016 Largemouth Bass: 2016 Bluegill Sunfish 2022 Bluegill Sunfish Centennial Lake 2006 Bluegill: 2001-2006, Largemouth Bass: 2002-2006 Black Bullhead, Green Sunfish 2011 Bluegill: 2007-2012, 2014-17, 2020 Black Crappie: 2017 Largemouth Bass: 2007-2009, 2014 Northern Pike: 2007-2010, 2013-2014 Pumpkinseed Sunfish: 2016 Black Bullhead, Hybrid Sunfish Indianhead Lake 2021 Bass: 2008, 2013, 2016 Black Crappie: 2008, 2013, 2016 Bluegill: 2008-2009, 2013, 2016 Hybrid Sunfish: 2016 Walleye: 2008 Black Crappie, Bluegill Sunfish, Hybrid Sunfish 2022 Black Crappie, Bluegill Sunfish Streams Minnehaha Creek N/A N/A N/A Meadowbrook (connected to Minnehaha Creek) N/A N/A N/A Edina Mill Pond (connected to Minnehaha Creek) N/A N/A N/A 1 – Fisheries information from the MnDNR LakeFinder website (http://www.dnr.state.mn.us/lakefind/) 2 – Stocking reports available for 1998-2022 from the MnDNR LakeFinder website (http://www.dnr.state.mn.us/lakefind/) City of Edina 2022 Water Resources Management Plan 2-18 2.2.12 Unique Features and Scenic Areas The MnDNR Natural Heritage Program and Nongame Wildlife Program maintain a database of rare plant or animal species and significant natural features. This database includes only one record of a rare or threatened species observance in Edina; a Blanding’s Turtle (Emydoidea Blandingii) was observed in 1989 in the southeast portion of the City (see Figure 2.7). The Blanding’s Turtle was classified as a threatened species in Minnesota in 1984. Other information was reviewed to determine whether other unique features are present in Edina. Based on this review, no Outstanding Resource Value Waters (Minnesota Rules 7050.0180), Designated Scientific and Natural Areas (Minn. Stat. 86A.05), State Wildlife Management Areas (Minn. Stat. 86A.05), or State Aquatic Management Areas (Minn. Stat 86A.05) are located within the City of Edina. 2.2.13 Pollutant Sources The MPCA’s “What’s in My Neighborhood” online application provides a variety of environmental information for communities. The interactive web map provides information about environmental permits issued by the MPCA, registrations and notifications required by the MPCA, and investigations of potentially contaminated properties undertaken by the MPCA or its partners. The map shows the approximate locations of registered storage tanks, leak sites, hazardous waste generators, dump sites, Superfund sites, and Minnesota Pollution Control Agency (MPCA) Voluntary Investigation and Cleanup (VIC) sites, as obtained from the Hennepin County Department of Environmental Services. The Hennepin County Department of Environmental Services should be contacted for details about specific sites, since many of the sites have been cleaned up or are in the clean-up process. 2.2.13.1 Investigation and Cleanup Sites Dump sites include both unpermitted and permitted dump sites. Unpermitted dump sites are historic landfills that never held a valid permit from the MPCA. Generally, these dump sites existed prior to the MPCA’s permitting program, which was initiated in 1967. Unpermitted dump sites were often old farm or municipal disposal sites that accepted household waste. The MPCA VIC Program is a non-petroleum brownfield program that provides technical assistance and administrative or legal assurances for individuals or businesses seeking to investigate or clean-up contaminated property and to bring contaminated land back into productive use. There is currently one MPCA Superfund Site within the City of Edina. This site is the Edina Well Field. Additional information on this site can be obtained from the MPCA. In the early 2000s, the City of Edina detected elevated levels of vinyl chloride in Municipal Well Number 7. Preliminary investigations found several volatile organic compounds in nearby groundwater resulting in the City discontinuing use of Well Number 7 in October 2003. Well Number 7 came online again after a high-capacity treatment plant (Water Treatment Facility No. 6) was built at the Danen’s Building (5116 Brookside Avenue) in 2012. The plant is equipped with an aeration system specially designed to filter out vinyl chloride. The City regularly tests for vinyl chloride and Edina’s water meets the criteria set forth by the Environmental Protection Agency. City of Edina 2022 Water Resources Management Plan 2-19 2.2.13.2 Tank Sites and Leak Sites Tank sites include registered petroleum tank facilities, both underground and above ground. Leak sites are locations where a release of petroleum products has occurred from a tank system. Leak sites can occur from aboveground or underground tank systems, or from spills at tank facilities. A leak can result from an accident or from activities that occurred over a long period of time. Many of the known leak sites are related to releases from underground fuel oil tanks. 2.2.13.3 Individual Sewage Treatment Systems If properly functioning, individual sewage treatment systems (ISTS) typically do not impact the water quality of surface or ground water resources. However, improperly functioning systems can negatively impact water resources and are a source of ground and surface water contamination. City records indicate that there are four known ISTS throughout the City. 2.2.14 Groundwater The City of Edina operates two separate water systems: the Morningside water system and the Edina water system. The Morningside system is supplied with treated surface water from the City of Minneapolis; the City of Edina does not appropriate any surface water for its municipal water supply. The water supply for the Edina system is groundwater, obtained from 17 groundwater wells, ranging in depth from about 400 to 1,100 feet. The City’s current groundwater appropriation permit limits the City’s groundwater pumping to 17,500 gallons per minute or 3,000,000,000 gallons per year. Wellhead protection programs are intended to help prevent contamination of public drinking water supplies. The City’s Wellhead Protection Plan is available online. Part II of the Wellhead Protection plan includes results of the City’s Potential Contaminant Source Inventory (PCSI). The City provides updates of its Wellhead Protection Plan and associated programs to the MCWD and/or NMCWD, as needed. Wellhead Protection information can also be found on the City’s Interactive Water Resources Map. Mud Lake Lake Cornelia Lake Edina Mirror Lake Arrowhead Lake Indianhead Lake Highlands Lake Melody Lake Lake Pamela Harvey Lake Hawkes Lake Centennial Lakes Min n e h a h a Cr e ek Nine Mile Creek - North Nine MileCreek - Central Nine MileCreek - South SoutheastMinnehaha Creek SouthwestPonds NorthwestMinnehaha Creek Nine Mile -South Fork Lake Cornelia/Lake Edina/Adam's Hill NortheastMinnehaha Creek TH 169North £¤169 100 62 100 456717 456731 4567158 456731NorthBranchN i ne Mile C reek SouthBranc h N ine Mile C r eekM i n n e ap o l i sMinneapolis H o p k i n sHopkins E d e n P r a i r i eEden P r a i r i e R i c hf i e l dRichfield B l oo m in g t o nBloomington M i n n e t o n k aMinnetonka S a i n t L o ui s P a r kSaint L o ui s P a r k Barr Footer: ArcGIS 10.4.1, 2017-09-20 17:37 File: I:\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_2_1_Major_Drainage_Areas.mxd User: EMAMAJOR DRAINAGE AREASWater ResourcesManagement PlanCity of Edina, Minnesota FIGURE 2.1 0 3,000 Feet !;N Streets and Highways Creek/Stream Lake/Pond City of Edina Boundary Imagery Source: MnGeo 2016 Mud Lake Lake Cornelia Lake Edina Mirror Lake Arrowhead Lake Indianhead Lake Highlands Lake Melody Lake Lake Pamela Harvey Lake Hawkes Lake Centennial Lakes Min n e h a h a Cr e ek £¤169 100 62 100 456717 456731 4567158 456731 Ed e n P r a i r i eEden P r a i r i e M i nn e a p o l i sMinneapolis S a i ntSaint L ou i s P a r kLouis P a r k Ri c h f i e l dRichfield M i n n e t on k aMinnetonka Ho p k i n sHopkins B l o o m i n g t o nBloomingtonSouthBranchNineMileCreek NorthBranchNineMileCreek Barr Footer: ArcGIS 10.8.1, 2022-07-27 14:43 File: I:\Client\Edina\Projects\CWRMP_Amendment_2D_Modeling\Maps\Reports\WRMP_July2022\Fig_2_2_Edina_LandUse_Classification.mxd User: vawLAND USE CLASSIFICATIONWater ResourcesManagement PlanCity of Edina, Minnesota FIGURE 2.2 0 3,000 Feet !;N Land Use Classification Golf Course Industrial or Utility Institutional Major Highway Mixed Use Commercial Mixed Use Industrial Mixed Use Residential Multifamily Office Open Water Park, Recreational, or Preserve Retail and Other Commercial Single Family Attached Single Family Detached Undeveloped Streets and Highways Creek/Stream City of Edina Boundary Imagery Source: MnGeo, 2016 Data Source: Metropolitan Council, 2020 1 Mud Lake Lake Cornelia Lake Edina Mirror Lake Arrowhead Lake Indianhead Lake Highlands Lake Melody Lake Lake Pamela Harvey Lake Hawkes Lake Centennial Lakes Min n e h a h a Cr e ek £¤169 100 62 100 456717 456731 4567158 456731 NorthBranchNineMileCreek SouthBranc h N ine Mile C r eekM i n n e ap o l i sMinneapolis H o p k i n sHopkins E d e n P r a i r i eEden P r a i r i e R i c hf i e l dRichfield B l oo m in g t o nBloomington M i n n e t o n k aMinnetonka S a i n t L o ui s P a r kSaint L o ui s P a r k Barr Footer: ArcGIS 10.8.1, 2022-07-27 14:55 File: I:\Client\Edina\Projects\CWRMP_Amendment_2D_Modeling\Maps\Reports\WRMP_July2022\Fig_2_3_Edina_Soils_Classification.mxd User: vawEDINA SOILS CLASSIFICATIONWater ResourcesManagement PlanCity of Edina, Minnesota FIGURE 2.3 0 3,000 Feet !;N Hydrologic Soil Groups A - High infiltration rates. Low runoff Potential. B - Moderate infiltration rates.Low to medium runoff potential. C - Slow infiltration rates. Medium to high runoff potential. D - Very slow infiltration rates.High runoff potential. Not rated or not available Streets and Highways Creek/Stream City of Edina Boundary Imagery Source: MnGeo, 2016 ^_ ^_ ^_ ^_ ^_ ^_ ^_ ^_ ¸# ¸# ¸# Mud Lake Lake Cornelia Lake Edina Mirror Lake Arrowhead Lake Indianhead Lake Highlands Lake Melody Lake Lake Pamela Harvey Lake Hawkes Lake Centennial Lakes Min n e h a h a Cr e ek £¤169 100 62 100 456717 456731 4567158 456731 Nine Mile CreekWatershed District Minnehaha CreekWatershed District NorthBranchNineMileCreek SouthBranc h N ine Mile C r eekM i n n e ap o l i sMinneapolis H o p k i n sHopkins E d e n P r a i r i eEden P r a i r i e R i c hf i e l dRichfield B l oo m in g t o nBloomington M i n n e t o n k aMinnetonka S a i n t L o ui s P a r kSaint L o ui s P a r k Barr Footer: ArcGIS 10.8.1, 2022-07-27 14:59 File: I:\Client\Edina\Projects\CWRMP_Amendment_2D_Modeling\Maps\Reports\WRMP_July2022\Fig_2_4_Water_Quality_Monitoring_Stations.mxd User: vawWATER QUALITYMONITORING STATIONSWater ResourcesManagement PlanCity of Edina, Minnesota FIGURE 2.4 0 3,000 Feet !;N ¸#MCWD StreamMonitoring Station1 ¸#NMCWD StreamMonitoring Stations1 ^_Lake Water QualitySampling Locations1 Watershed District Boundary Streets and Highways Creek/Stream Lake/Pond City of Edina Boundary Imagery Source: MnGeo, 2016 1Monitoring is conducted periodicallyby NMCWD, MCWD, and CAMP Volunteers. Watershed district monitoring is on a rotating basis based on each district plan. Volunteer monitoring sites are subject to change. Mud Lake Lake Cornelia Lake Edina Mirror Lake Arrowhead Lake Indianhead Lake Highlands Lake Melody Lake Lake Pamela Harvey Lake Hawkes Lake Centennial Lakes Minne h a h a C r e e k£¤169 100 62 100 456717 456731 4567158 456731 Nine Mile CreekWatershed District Minnehaha CreekWatershed District No rth B ranchNineMileCreek SouthBranch N i ne MileCreek M i n n e ap o l i sMinneapolis H o p k i n sHopkins E d e n P r a i r i eEden P r a i r i e R i c hf i e l dRichfield B l oo m in g t o nBloomington M i n n e t o n k aMinnetonka S a i n t L o ui s P a r kSaint L o ui s P a r k Barr Footer: ArcGIS 10.4.1, 2017-10-31 10:07 File: I:\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_16_2_Wetland_Classifications.mxd User: smsWETLAND CLASSIFICATIONSWater ResourcesManagement PlanCity of Edina, Minnesota FIGURE 16.2 0 3,000 Feet !;N Watershed District Boundary Streets and Highways City of Edina Boundary Wetland Type* Unclassified Type 1 Type 1 Predominant + Others Type 2 Type 2 Predominant + Others Type 3 Type 3 Predominant + Others Type 4 Type 5 Type 5 Predominant + Others Type 6 Type 7 Type 7 Predominant + Others Imagery Source: MnGeo, 2016 *Based on the Fish and Wildlife ServiceCircular 39 Classification System. Wetlands within the Minnehaha CreekWatershed District were identified andassessed in 2005 as part of theMinnehaha Creek Functional Assessmentof Wetlands. Wetlands located in theremaining portion of the city wereidentified and assessed in 1999 as partof the City of Edina’s wetland inventory. North B ranchNineMileCreek SouthBranc h Nine Mile C r eekMud Lake Lake Cornelia Lake Edina Mirror Lake Arrowhead Lake Indianhead Lake Highlands Lake Melody Lake Lake Pamela Harvey Lake Hawkes Lake Centennial Lakes M in ne h a h a C r ee k£¤169 100 62 100 456717 456731 4567158 456731 Braemar Park (Courtney Fields) Bredesen Park Rosland Park Pamela Park Lewis Park Highlands Park Walnut Ridge Park T. Lea Todd Park Open Space 1 Heights Park Garden Park Heights Park Lincoln Drive Floodplain Van Valkenburg Park Fred Richards Golf Course Arden Park Krahl Hill Creek Valley School Park Lake Edina Park Normandale Park Weber Field Park Arneson Acres Park Countryside Park Weber Woods Centennial Lakes Park Open Space 2 Open Space 3 Centennial Lakes Park Alden Park Utley Park Open Space 2 Moore Property Pamela Park York Park Yorktown Park Centennial Lakes Park Cornelia School Park Wooddale Park Strachauer Park Garden Park Open Space 5 Fox Meadow Park Kojetin Park Edinborough Park Arden Park Garden Park McGuire Park Fox Meadow Park Birchcrest Park Sherwood Park Garden Park Addition Melody Lake Park Chowen Park Open Space 2 Centennial Lakes Park St. John's Park Tingdale Park York Park Browndale Park York Park Frank Tupa Park Grandview Square Open Space 6 M i n n e ap o l i sMinneapolis H o p k i n sHopkins E d e n P r a i r i eEden P r a i r i e R i c hf i e l dRichfield B l oo m in g t o nBloomington M i n n e t o n k aMinnetonka S a i n t L o ui s P a r kSaint L o ui s P a r k Barr Footer: ArcGIS 10.4.1, 2017-10-26 13:47 File: I:\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_2_6_Edina_Parks_and_Recreation_Areas.mxd User: EMAPARKS ANDRECREATIONAL AREASWater ResourcesManagement PlanCity of Edina, Minnesota FIGURE 2.6 0 3,000 Feet !;N Park/Recreational Area Streets and Highways Creek/Stream Lake/Pond City of Edina Boundary Imagery Source: MnGeo, 2016 Mud Lake Lake Cornelia Lake Edina Mirror Lake Arrowhead Lake Indianhead Lake Highlands Lake Melody Lake Lake Pamela Harvey Lake Hawkes Lake Centennial Lakes Min n e h a h a Cr e ek £¤169 100 62 100 456717 456731 4567158 456731 NorthBranchNineMileCreek SouthBranc h N ine Mile C r eekM i n n e ap o l i sMinneapolis H o p k i n sHopkins E d e n P r a i r i eEden P r a i r i e R i c hf i e l dRichfield B l oo m in g t o nBloomington M i n n e t o n k aMinnetonka S a i n t L o ui s P a r kSaint L o ui s P a r k Barr Footer: ArcGIS 10.4.1, 2017-10-26 13:45 File: I:\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_2_7_Threatened_and_Endangered_Species.mxd User: EMATHREATENED ANDENDANGERED SPECIESWater ResourcesManagement PlanCity of Edina, Minnesota FIGURE 2.7 0 3,000 Feet !;N NHIS Rare Natural Features Vertebrate Animal Invertebrate Animal Vascular Plant Animal Assemblage Streets and Highways Creek/Stream Lake/Pond City of Edina Boundary Imagery Source: MnGeo, 2016 Data Source:Natural Heritage InformationSystem Rare Features DataCopyright 2017 State of Minnesota,Department of Natural Resources City of Edina 2022 Water Resources Management Plan 3-1 3.0 Water Resources Management and Implementation Program The City of Edina provides three core services through its water resources program: flood risk and stormwater management, clean water services, and natural resources restoration and protection (Figure 3.1). The provision of these services takes place using two primary strategies: physical infrastructure and programmatic activities. Figure 3.1 Core Services of Water Resources Program This chapter describes the activities that support each of the three core service areas and some of the policy issues around the provision and growth of service. This chapter also discusses resources, financial considerations, and implementation priorities. Table 3.5 summarizes details of the City’s implementation program activities, including a project description, planning level cost estimate, potential funding sources, and estimated schedule for implementation. Table 3.6 summarizes the potential implementation activities to be undertaken in the next ten years, including capital improvements. Funding for capital improvements comes primarily from the City’s Stormwater Utility, as described in Section 3.5.5 Financial Considerations. The City’s Capital Improvement Program will set forth, by year, details including proposed schedule, estimated cost, and funding source. The Capital Improvement Program is described further in Section 3.5.3 Prioritization. 3.1 Water Resources Network: A Combination of Stormwater Assets and Natural Resources All surface water resources present in Edina are part of the City’s water resources network. This broad network generally includes two different, but interconnected, types of water resources. Flood risk and stormwater runoff management Natural resources restoration and protection Clean water services City of Edina 2022 Water Resources Management Plan 3-2 First, under Minnesota Statutes, the City has authority to build, construct, reconstruct, repair, enlarge, improve, or in any other manner obtain stormwater sewer facilities, as well as maintain and operate the facilities inside or outside its corporate limits (Minn. Stat. § 444.075, subd. 1a). The City’s stormwater sewer system includes facilities built for the collection and disposal of stormwater, such as mains, holding ponds/areas, and other appurtenances/related facilities (Minn. Stat. § 444.075, subd. 1(e)). Stormwater sewer system facilities come in various forms, such as roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, designed channels, storm drains, constructed stormwater ponds, and green stormwater infrastructure. Whether these facilities are private or public, above or below ground, they all share one feature in common, they constitute built infrastructure. In short, these facilities are planned, designed, constructed, operated, and maintained to collect, convey or treat stormwater; and prevent or reduce the discharge of pollutants in stormwater. Second, the City is home to a variety of environmental resources, including natural water resources. These natural water systems receive stormwater, but they are not constructed facilities and thus are not part of the stormwater sewer system. Moreover, though natural systems, like creeks, lakes, and wetlands, may provide stormwater retention or conveyance benefits, these natural systems serve ecological functions and provide environmental values to wildlife and people beyond the benefits they provide, if any, for stormwater management. Together these water resources encompass Edina’s water resources network. Although the two types of water resources are distinct, provide different values, and serve different functions, the built infrastructure, which makes up the City’s stormwater sewer system, and the natural water resources, which make up the environmental system, are interconnected in many ways. For example, surface water can flow amongst and between natural and built components, and a surface water feature may interact with groundwater similarly whether the surface water feature is built infrastructure or natural environment. Stormwater assets are designed, built, operated, and maintained to collect, convey or treat stormwater. Examples include roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, designed channels, storm drains, constructed stormwater ponds, and green stormwater infrastructure. Natural resources are naturally occurring surface resources (lakes, ponds, creeks, wetlands) and groundwater that may be managed, protected, and restored consistent with natural processes. Lakes, ponds, creeks, and wetlands receive stormwater but are not part of the stormwater system. City of Edina 2022 Water Resources Management Plan 3-3 3.1.1 Public Waters The MnDNR has designated certain waters of the state as public waters (Minn. Rules 6115.1060). MnDNR “Public Waters Inventory (PWI)” maps show public waters within the City. A MnDNR permit is required for work that would alter the course, current, or cross-section of a designated public water. PWI maps show public waters as one of the following: public water basin; public water wetland; public water watercourse; or, public ditch/altered natural watercourse. Public waters within the City of Edina are identified in Section 2.2.8 and Table 2.4. 3.1.2 Wetlands The wetlands in the City of Edina are an important community asset. To provide a basis for wetland protection efforts, wetland inventories and field assessments have been completed for wetlands within the City (see Section 2.2.7), including the MCWD’s 2003 Functional Assessment of Wetlands (FAW). The City adopts the MCWD FAW for portions of the City within the Minnehaha Creek Watershed. As new wetland information becomes available because of private or public standalone projects, it will be incorporated into the City’s inventory. As projects that could impact wetlands arise, the City will complete updated assessments as needed and in cooperation with watershed districts, pursuant to Section 4.3 Wetlands Policies. Not all wetlands are natural waterbodies. Some constructed stormwater ponds are also classified as wetlands; however, these waterbodies have exceptions that allow for maintenance. 3.1.3 Natural Resources Monitoring and Inspections The City does not have a water monitoring program and instead relies on the programs of the overlying watershed districts for lake and creek water quality and flow monitoring. City staff occasionally walk the reaches of Nine Mile Creek and Minnehaha Creek for the purpose of noting observations of erosion issues, beaver dams, debris jams, illicit discharges, floodplain encroachments, etc. Other natural resource inspections occur on a complaint basis. Often these are related to aquatic vegetation, discussed further in Section 3.2.3.1. 3.2 Stormwater Infrastructure Asset Management Asset Management is defined in international standard ISO55000 by the International Standards Organization (ISO) as “the coordinated activity of an organization to realize value from assets” and an asset as “any item, thing or entity that has potential or actual value to an organization.” Asset management is further described by best practice frameworks from organizations such as Infrastructure Asset Management (IAM), Institute of Public Works Engineering Australasia (IPWEA), American Public Works Association (APWA), and American Water Works Association (AWWA). The stormwater system assets are operated and maintained by trained professionals whose duty is the safety and well-being of the customer. City of Edina 2022 Water Resources Management Plan 3-4 Stormwater infrastructure assets and related programs are managed to understand and react to service level deficits, identify and manage risk, assess condition and take a lifecycle approach to the operation, maintenance and replacement of system components, and monitor system performance. Managing aging infrastructure and adapting to climate change are challenges that the City addresses as it reimagines and renews its stormwater assets. 3.2.1 Asset Procurement Assets are created, acquired, or installed to deliver flood risk reduction, runoff management, and clean water service. Infrastructure for stormwater management and drainage as well as for clean water are discussed in this section together because of the overlapping services that some assets provide. They are planned and created through capital investments, and in the case of most private assets, some are created to meet regulatory requirements. Infrastructure used to provide flood risk and stormwater runoff management generally includes structural or engineered control devices and systems designed to store stormwater such as pipes, inlets, constructed ponds, lift stations, outlet controls, engineered temporary inundation areas, and designed local flood storage areas, among others. Runoff management and flood risk reduction infrastructure also includes sump drains (providing a dual purpose with the sanitary sewer infiltration and inflow program), and curb and gutter (providing dual purpose with erosion sediment control and road maintenance), among others. Infrastructure used to provide clean water services generally includes underground hydrodynamic separators (also termed grit chambers), sump manholes, constructed ponds, underground storage and infiltration facilities, and bioretention basins, among others. Green stormwater infrastructure (GSI) includes engineered systems that mimic natural systems to treat polluted runoff. Examples of GSI features include bioretention basins, bioswales, constructed ponds, and tree trenches. Smart infrastructure uses low-cost “smart” technologies to enhance conventional stormwater infrastructure to provide flood risk reduction and clean water benefits. Sensors and smart technology can be used to analyze forecasts and then proactively, remotely and autonomously control water levels in stormwater infrastructure assets. This approach can be used to detain stormwater longer to enhance pollutant removal, create additional flood storage ahead of a storm, maintain baseflow in creeks, and mimic natural bounce conditions that improve habitat for plants and animals. The Morningside Flood Infrastructure Project in Edina and the Grays Bay Dam operated by MCWD in Minnetonka are examples of smart infrastructure. 3.2.2 Asset Ownership Private Stormwater Assets Owners of private stormwater assets are responsible for operating and maintaining the assets in proper condition, consistent with the original performance design standards and private maintenance agreements with respective watershed districts. Responsibilities include removal and proper disposal of all settled materials from constructed ponds, sumps, grit chambers, and other devices, including settled City of Edina 2022 Water Resources Management Plan 3-5 solids. As of the 2022 major amendment to this plan, the City is in the process of establishing a program to ensure private stormwater assets are properly maintained, so that they continue to provide the intended level of service for flood risk management, drainage, and clean water. The NMCWD requires that maintenance specifics be recorded against the deed of any private property subject to a NMCWD permit. Publicly Owned Stormwater Assets The City of Edina is responsible for performing maintenance on its built infrastructure, i.e., stormwater facilities the City constructed or acquired after construction. The Minnesota Department of Transportation is responsible for maintaining road ditches, storm sewer, and culverts along U.S. Highway 169, State Highway 100, and State Highway 62. Hennepin County is responsible for maintaining right-of-way, storm sewer, and culverts along CR 17 (France Avenue), CR 31 (York Avenue), CR 158 (Vernon Avenue), and CR 20 (Interlachen Boulevard). On County roads, the City is responsible for maintenance of storm sewer pipes and the County is responsible for maintenance of the structures (manholes and catch basins). Edina Public Schools is responsible for all stormwater infrastructure assets on their properties. Watershed Districts are increasingly sharing in the maintenance burden of stormwater assets. Agreements related to construction and maintenance of assets are described in Section 4.7. The NMCWD further requires maintenance agreements for projects subject to a NMCWD permit. The City will also notify the owners of other publicly owned stormwater assets if maintenance is needed according to periodic site inspections or maintenance plans on file. 3.2.3 Inventory and Inspection The City maintains a database of all known private and public stormwater assets in a Geographic Information System (GIS). Routine inspection programs draw from this database and dashboards quickly show the status of the inspection programs. The City routinely inspects assets to assess their condition and programs interventions necessary for continued operation and/or maintenance. Inspections are completed for the following asset groups: • Conveyance assets (pipes, inlets, outlets, manholes, and catch basins) • Structural stormwater assets (filtration/infiltration facilities at the surface or underground, flow control facilities, special pollution control devices, etc.). Green stormwater infrastructure assets (bioretention basins, bioswales, and tree trenches) are also part of this group. • Constructed ponds (a subset of structural stormwater assets) • Private stormwater assets Parts of the stormwater system are regulated through the Municipal Separate Storm Sewer System (MS4) General Permit. Information on how the City meets those requirements is described in the Stormwater Pollution Prevention Program and annual reports to the Minnesota Pollution Control Agency. City of Edina 2022 Water Resources Management Plan 3-6 Inspection protocols are used to determine if assets are functioning and identify preventative or corrective maintenance needs. Inspection results that indicate a need for maintenance are then routed to the appropriate maintenance authority (private, City, or another public owner). 3.2.4 Operations and Maintenance Operations are actions that sustain, modify, alter, or regain system function and provide service or manage risk. System operation is conducted primarily by the trained and certified utility operators from the Public Works Department and natural resource technicians in the Parks Maintenance division. Typical operations consist of a variety of activities such as routine care of high touch system components, CCTV inspection of trouble pipes, jetting and vacuuming of debris, care of vegetation, failure analysis, and other activities necessary to deliver the service level, meet regulatory requirements, and optimize the useful life of an asset. Maintenance is any action that repairs or retains the physical infrastructure assets to meet projected service levels and optimize the lifecycle of an asset. System maintenance is conducted primarily by the trained and certified utility operators from the Public Works Department and natural resource technicians in the Parks Maintenance division. Typical maintenance consists of replacement of worn manhole lids, grouting of manhole rings, spot repair of pipe, refurbishment or replacement of pumps, refurbishment or replacement of electrical control components, replacement of other worn or damaged system components, replacement of plant material, and other minor maintenance. Stormwater Conveyance Assets Stormwater conveyance assets include pipes, inlets, outlets, manholes, catch basins, planned overflows, and streets (curb and gutter) that capture and convey stormwater. To manage risks and to prevent pipe plugging, trash racks are typically installed on storm sewer, pipe inlets, and some outlets. These trash racks prevent people from entering the pipes and help keep large debris from becoming lodged in the pipes. If not inspected and cleaned, the trash racks will become plugged with debris such as branches, leaves, and other materials carried by storm flows. Even partially plugged storm sewer pipes can disrupt the drainage service. The City performs periodic removal of collected debris including ice from system trash racks, catch basins, and inlets. The City performs preventative and corrective maintenance including grouting, ring replacement, and full asset rebuild/replacement. In places prone to erosion, soil may be protected and stabilized by hard-armoring (with riprap or similar product, for example), soft-armoring (with vegetation), or some combination. These strategies are used to prevent damage that would result from highly erosive flow velocities. Periodic inspection and maintenance reduce erosion, pipe damage, Adopt-a-drain – As part of its outreach and engagement sector of work, the City encourages residents to adopt storm drains in their neighborhood and pledge to help keep them free of debris through the adopt-a-drain program. City of Edina 2022 Water Resources Management Plan 3-7 downstream sediment problems, and potential safety issues. Engineered emergency overflows and areas adjacent to stormwater outfalls are routinely inspected and maintained. Structural Stormwater Assets Structural stormwater assets include stationary and permanent infrastructure that are designed, constructed, and operated to control volume or prevent or reduce the discharge of pollutants in stormwater. Structural stormwater assets may detain, retain, infiltrate, or filter stormwater. Green stormwater infrastructure (GSI) assets are also part of this group and include bioretention basins, bioswales, and tree trenches. GSI includes engineered systems that mimic natural systems to treat polluted runoff. These systems are also beneficial for helping communities become more resilient in a changed and changing climate. In 2019, Congress enacted the Water Infrastructure Improvement Act, which defined green infrastructure as “the range of measures that use plant or soil systems, permeable pavement or other permeable surfaces or substrates, stormwater harvest and reuse, or landscaping to store, infiltrate, or evapotranspirate stormwater and reduce flows to sewer systems or to surface waters.” All structural stormwater infrastructure assets, whether conventional “gray” stormwater infrastructure or green stormwater infrastructure, require maintenance. Routine operation and maintenance on vegetated green stormwater infrastructure is similar to general landscape maintenance: removing trash, leaf litter, and debris; keeping plants healthy; and cleaning out accumulated sediment and pollutants. Routine operation and maintenance of filtration infrastructure includes replacing spent filter media and clearing screens of debris. Routine operation and maintenance of permeable pavements includes street sweeping with a regenerative air sweeper system and controlling pollutants, such as sand and deicing salts, at the source. Routine operation and maintenance of underground facilities and pollution control devices includes cleaning out accumulated sediment and pollutants. Constructed Ponds (a subset of structural stormwater assets) Constructed stormwater ponds perform a desirable function by settling sediment and adsorbed pollutants out of the stormwater. However, if accumulated sediments are not periodically removed, such basins can experience a significant loss in necessary stormwater detention capacity and sediment storage volume. Also, if left unattended, these facilities can become overgrown with nuisance vegetation that could reduce their effectiveness and hinder access for periodic maintenance. The City of Edina periodically inspects constructed stormwater ponds to look for excessive sediment build-up, collected debris, erosion, and nuisance vegetation. If problems are noted, maintenance is then planned and performed. Sediment removal is typically planned after approximately 50 percent of the City of Edina 2022 Water Resources Management Plan 3-8 permanent pool capacity has been lost to restore the constructed pond to its originally designed sediment storage volume. Dredged materials are then tested and disposed of appropriately. Engineered emergency overflows associated with constructed ponds can turn into steep eroding channels if an ongoing erosion problem is not stabilized and the area restored. Typical stabilization materials could include permanent geotextile erosion-control material or riprap accompanied by a properly designed filter material. Properly managed vegetation adjacent to constructed ponds can help to stabilize the slopes to reduce erosion and can have a secondary benefit of providing upland wildlife habitat. 3.2.5 Renewal and Replacement Renewal and replacement refers to major repair or replacement of assets at or near the end of their service life. This activity is conducted by the engineers, technicians, and inspectors in the Engineering Department or by consulting engineers, and typically occurs in parallel with the City’s parks development projects, neighborhood street reconstruction program, municipal state aid reconstruction program, or are completed as standalone utility projects. Replacement and renewal projects are bundled by age cohort of road and utility infrastructure or are added to the scope of new infrastructure projects. System components are inspected, and conditions assessed to inform project replacement and repair interventions. Engineers produce project reports and recommend project scopes to the City Council. Projects are bundled and bid for reconstruction and contracts are considered by the City Council. Bundling of projects improves efficiency and customer service through economies of scale and minimizing the duration of disruptions due to renewal. Renewal and replacement decisions assume the infrastructure service remains the same or is replaced with current industry standard materials and components. Typically, projects are a mix between renewal and replacement, and new and upgraded service. 3.2.6 New and Upgraded Public or Private Assets New and upgraded stormwater assets are either entirely new areas or levels of service, or major improvements to the marginal level of service provided by existing infrastructure. Activities associated with evaluating, designing and implementing new or upgraded stormwater assets are generally conducted by engineers, technicians, and inspectors in the Engineering Department, or by engineers employed by private developers as part of land use, community development, or economic development projects. City of Edina 2022 Water Resources Management Plan 3-9 3.3 Flood Risk Management Flooding in Edina is not only common, but also increasing. Though there is a desire for solving flood problems outright through transformational change, the physical constraints of a changing climate, aging infrastructure, expensive capital investment needed, and land use decisions of the past continuously push us to a risk management paradigm in which only incremental change is possible. The factors that are driving increasing flood risk were explored through the development of the Flood Risk Reduction Strategy. The primary and secondary drivers are climate change and aging infrastructure. Well-drained landscapes and imperviousness also matter but are more historical drivers of flood risk. Climate change is making storms more intense and increasing the chance of extended wet periods or drought. Climate change has already and will expose more assets to flooding in the future. This driver is predicted to overwhelm the other drivers in terms of scale. Private and public assets and infrastructure are both exposed and vulnerable. Public infrastructure can define flood exposure for different points in the landscape and serve as a vector for private risk. Public infrastructure assets are old and not capable of meeting the current demand. This is a significant driver as infrastructure provides most stormwater service. Development has connected the landscape to the water to make land well-drained. While this is a major historic driver, it is a minor driver increasing future flood exposure. Most of the drainage and land development decisions have already been made and cannot be unmade. There is additional demand for drainage that can reduce vulnerability, but marginally affects flood exposure downstream. Flood Risk Reduction Strategy (FRRS) In the 2018 plan, the City of Edina committed to developing a Flood Risk Reduction Strategy. A task force of staff and community members worked to come to a shared understanding of what flooding is, what City services are providing value, and what matters, where, and to whom. City Council adopted the Flood Risk Reduction Strategy in April 2020 and it has now been incorporated into this plan via major amendment. City of Edina 2022 Water Resources Management Plan 3-10 Community demand for garages, parking areas, patios, pools, sport courts, and bigger homes has increased the hard cover of soils. Imperviousness drives runoff in small storms and marginally affects flood exposure in large storms. The most significant changes to impervious cover occurred when the community experienced rapid development in the 1940s, 1950s, and 1960s. Recent changes in impervious are relatively small compared to historical changes. 3.3.1 Flood Risk Reduction Strategy The City of Edina’s strategy is to comprehensively reduce the risk of flooding throughout the community. Through this strategy, the City takes action to reduce the risk of flood loss, to minimize the impact of floods on human safety, health and welfare, and to restore and preserve the natural and beneficial values served by floodplains. The primary goal for the City’s flood risk reduction effort is to improve public safety and reduce the exposure of private principal structures to flooding. Flooding is a concern for the city and its residents due to the threat to public safety and potential for significant property damages and economic losses. Flooding can cause other damages that are harder to quantify, including the following: • Flooding of roads so they are impassable to emergency vehicles and residents • Reduced redevelopment potential • Shoreline erosion • Increased pollutants in stormwater discharges • Destruction of riparian habitats and vegetation such as grass, shrubs, trees, etc. • Unavailability of recreational facilities for use by the public (e.g., inundation of shoreline) and/or restricted recreational use of waterbodies • Unavailability of recreation amenities and open spaces in parks that overlap with floodplains • Increased demand for emergency services and risk to emergency responders during flood events • More strain on budgets and personnel for repairing flood-damaged facilities and controlling public use of facilities during flooding events • Alterations to the mix and diversity of wildlife species as a result of inundation of habitats 3.3.2 Flood Risk, Exposure, and Vulnerability Flood risk is defined by climate and physical setting, exposure, and vulnerability. These factors vary with time, and across the landscape, assets, and people that characterize the community. City of Edina 2022 Water Resources Management Plan 3-11 Short term (weather), mid-term (seasonal), and long term (climate). Rainfall varies over time and space. Land use, soils, and topography matter. The degree to which property, homes, buildings, infrastructure, and other assets come into contact with flood water. The degree to which exposed assets, both public and private, are unable to resist flooding and are damaged by floods. Approaches for managing risk include reducing exposure, reducing vulnerability, increasing resilience to changing risks, and preparing, responding, and recovering from floods. The City acknowledges that similar flood risk may affect property owners differently according to owners’ resources available for prevention or repair. 3.3.2.1 Vectors for Principal Structure Flood Exposure Principal structure flood exposure can occur through overland flooding, groundwater seepage, and sanitary backflow. Over the land surface Groundwater seepage Sanitary backflow Surface water flooding can occur when severe storms and prolonged periods of wet weather cause water levels in constructed stormwater features, constructed or natural stormwater conveyances, areas inherently low in the landscape, or natural waterbodies to overflow. Principal structures near waterbodies or in low-lying areas can be at risk of flooding. Flash flooding may occur if existing drainage systems are overwhelmed by extremely heavy and/or intense rain. Urban areas can be particularly vulnerable to flash flooding due to a greater amount of impervious surfaces. Groundwater seepage can also be a source of City of Edina 2022 Water Resources Management Plan 3-12 flooding. This tends to occur after long periods of heavy rain or snowmelt, when more water infiltrates the ground and causes the groundwater to rise above a structure’s foundation level. Sanitary backflow flooding can be caused by a blockage in the City’s sewer system or when structures flood and inflow into the sanitary drains, overwhelming the capacity of the sewer system. This normally occurs when the sanitary sewer pipes are flooded with stormwater as a result of inflow and infiltration (I&I). When this happens, wastewater can flow backwards into principal structures. 3.3.2.2 Flood Exposure Data and Trends According to the Minnesota Department of Natural Resources Climatology Office, Minnesota’s climate is already changing rapidly and will continue to do so for the foreseeable future. The region has gotten much wetter and warmer, driven by more frequent heavy precipitation and warmer winters. The 2010s were the wettest decade on record in Minnesota and projections indicate this trend will continue (Figure 3.2). In addition to heavier precipitation events, the potential for drought will increase in coming decades. Hot weather, including higher summer temperatures and heat waves, has not worsened yet, but it is expected to by mid-century. Figure 3.2 Data from MnDNR Climate Trends Tool https://arcgis.dnr.state.mn.us/ewr/climatetrends/ City of Edina 2022 Water Resources Management Plan 3-13 Hydrologists, engineers, and water resources professionals rely on standardized precipitation data to appropriately size stormwater infrastructure. In 2016-2017, the City’s hydrologic and hydraulic models were updated to reflect the increased precipitation frequency estimates for the region based on NOAA’s 2013 Atlas 14 publication. This replaced the Technical Paper No. 40 Rainfall Frequency Atlas of the United States (“TP 40”) published in 1961 which was developed using available rainfall information from far fewer stations than exist today. It also included the “dust-bowl” years of the 1930s. The majority of the stormwater system was constructed in the 1940s through 1960s when predictions for rainfall amounts were less than they are today. The updated Atlas 14 reports use more observation locations with a longer period of record and use more sophisticated statistical methods. Even so, the updated Atlas 14 publication is still backward-looking and doesn’t consider future precipitation trends due to climate change. The updated Atlas 14 publication showed that across MN and neighboring states, the increases in 24-hour precipitation amounts increased, and in some places by as much as 25%. In Edina, the 1-percent-annual- chance (100-year) 24-hour precipitation amount went from 6 to 7.4 inches (see Figure 3.3). The increase is due to both additional data, some large local events since TP-40 was published, and generally larger precipitation totals occurring since before TP-40. If the observed trend in 1-percent-annual-chance 24-hour events from TP-40 to Atlas 14 were to continue, the future 1-percent-annual-chance rainfall events would be larger in the future, and what is designed today may be less protective in the future. Figure 3.3 Estimates of 100-year 24-hour rainfall depth Shallow groundwater levels are also on the rise due to a combination of consistently above average precipitation and implementation of stormwater infiltration practices across the metro area. Landlocked basin water levels can be particularly vulnerable to increases in precipitation when groundwater is high. Even during short periods of no precipitation, high groundwater levels may persist, resulting in higher-than-normal surface water elevations and increased vulnerability to groundwater seepage in basements. City of Edina 2022 Water Resources Management Plan 3-14 The mid-21st century predictions shown on Figure 3.3 come from a 2014 study by the MCWD and others (Stack et al., 2014): Long-term climate information and forecasts supporting stakeholder-driven adaptation decisions for urban water resources: Response to climate change and population growth. The green, yellow, and red points representing the mid-21st century estimates in Figure 3.3 correspond to the lower bound (optimistic), mean, and upper bound (pessimistic) estimates of the 1-percent-annual-chance rainfall by 2050, respectively. While the IPCC AR6 report published in 2022 ascribed high confidence to statements regarding increases in temperature over the globe, the IPCC AR5 report ascribes only medium confidence in anthropogenic forces contributing to a global-scale intensification of heavy precipitation over the second half of the 20th century. The latest global climate models (GCMs) and downscaled climate change models do not provide high confidence in predicted 1-percent-annual-chance 24-hour rainfall events. Thus, there is still significant uncertainty in the magnitude of future design storms. While this may be true, it is still prudent to expect that storms larger than those designed for presently, will occur in the future. Beyond accepting the consequences that will occur during those larger events, designers may attempt to build in additional resiliency to withstand or effectively manage those larger storms as a precaution against the uncertainty. The Atlas 14 hydrologic and hydraulic modeling and flood risk mapping analysis identified numerous flood-prone locations throughout the City, including some areas along the creeks, near lakes or wetlands, and areas adjacent to or within low areas where stormwater pools during large storm events. Flood risk mapping is available online via the City’s “Maps” page, While many of the flood-prone areas are localized, some of the flooding problems are more regional in nature. Since the 2013 release of Atlas 14, the Nine Mile Creek Watershed District has updated their hydrologic and hydraulic models to reflect the updated precipitation frequency estimates and has adopted revised flood management elevations. The City of Edina has also updated their hydrologic and hydraulic models to reflect Atlas 14 precipitation. However, FEMA’s effective Flood Insurance Rate Map (FIRM) and Flood Insurance Study (FIS) within the City of Edina are still based on TP-40 rainfall depths. As of early 2022 the MnDNR is in the process of studying the Minnehaha Creek watershed to update it with Atlas 14 data. Table 3.1 identifies the source of the best available 1-percent-annual-chance flood elevations for various portions of the City at the time of this plan development. City of Edina 2022 Water Resources Management Plan 3-15 Table 3.1 Source of the Best Available 1-Percent-Annual-Chance Flood Elevations throughout the City of Edina Area Best Available Flood Elevation Information/Modeling Source of Precipitation Frequency Estimates Owner Nine Mile Creek corridor (regional flood area) NMCWD Atlas 14 Flood Management Elevations and associated XPSWMM Model(s) Atlas 14 NMCWD Minnehaha Creek corridor (regional flood area) FEMA Effective Flood Insurance Rate Map (FIRM) and Flood Insurance Study (FIS); MCWD Hydrologic and Hydraulic modeling update (in progress) TP-40; Atlas 14 MCWD City of Edina, with exception of Nine Mile Creek and Minnehaha Creek corridor areas City of Edina WRMP (XPSWMM model updates occur annually to incorporate system changes). Atlas 14 City of Edina Note: Creek corridors and regional basins are considered “regional flood areas” – all areas outside of regional flood areas are considered “local flood areas”; 1-percent-annual-chance flood elevations are available from the City’s interactive web map 3.3.3 Sectors of Work The objective of the flood risk reduction strategy is to reduce exposure to flooding, reduce vulnerability to flooding, and provide equitable access to support for readiness, response, and recovery. Through the following sectors of work, the City will work with the community to comprehensively reduce flood risk. INFRASTRUCTURE: We renew our infrastructure and operate it to reduce risk. We will plan public streets and parks to accept and convey flood waters to reduce the risk and disruption of related city services. REGULATION: We acknowledge competing demands of land use and addressing drainage, groundwater, and surface water issues. We help people solve issues without harming another. OUTREACH AND ENGAGEMENT: We make flood information available and give people tools for flood resilience. EMERGENCY SERVICES: We help people prepare for floods, remove people from harm during floods, and recover after floods. City of Edina 2022 Water Resources Management Plan 3-16 3.3.3.1 Infrastructure Municipal stormwater systems provide multiple functions, including runoff management (removal of stormwater) and flood risk reduction. The system is composed of structural or engineered control devices and facilities to treat, convey, or store polluted stormwater. Stormwater infrastructure asset management is described in more detail in Section 3.2. The City of Edina operates and maintains its stormwater infrastructure and permits and accepts connections from private systems. It is the City’s standard practice to provide a 10-percent-annual-chance level of service and 1-percent-annual-chance level of protection for the City’s stormwater conveyance systems, where feasible. However, some existing stormwater conveyance systems have capacity limitations and cannot be guaranteed to provide the discharge capacity where private storm sewer systems tie into the trunk system. Private systems are discussed further in Section 3.2.2. Enhancing public infrastructure by building new, retrofitting old, and maintaining existing in working condition is a key action to reducing flood exposure. The stormwater system is made up of 127 miles of gravity main pipe ranging from 12-84” in diameter, 6800 manholes, 900 outlets, 38 miles of small diameter sump drain, 11 stormwater lift stations, and one- half mile of stormwater force main. An infographic showing the stormwater system as well as the other major utilities (sanitary sewer and drinking water) is available in Chapter 7 of the 2018 Comprehensive Plan. The majority of the system was constructed in the 1940s through 1960s, with significant additions and extensions occurring after that period. While Edina was experiencing rapid development in the mid twentieth century, stormwater was often routed directly to natural resources instead of an engineered stormwater management asset. Retrofitting the water resources network to direct runoff to stormwater assets and protect natural resources is a challenge – it will take significant capital resources and occur over a generational timeframe. Many city-owned public spaces including parks are in the floodplain. In some cases, these parcels were historically low and not conducive to development. In other cases, spaces have been retrofitted to store and convey stormwater to accommodate other community goals (transportation, buildings, clean water, flood risk reduction, etc.). The 2015 Parks System Strategic Plan acknowledges the climate change threat and proposes strategies to build resilient infrastructure, maintain the flood storage capabilities of the Parks system, and improve water resources. 3.3.3.2 Regulation Redevelopment provides a once-in-a-generation opportunity to build-in resilience. City staff are actively engaged with the development community through regulatory programs and provide technical support to permitted and affected private parties. In response, new structures or additions can be required to meet minimum elevations for low floors (such as basements), and/or low openings (such as the top of windows wells) and/or be built to withstand the forces and intrusion of flood waters (water proofing, drainage systems, foundation drains, sump pumps, sanitary backflow prevention). Another response to City of Edina 2022 Water Resources Management Plan 3-17 redevelopment includes requiring durable flow paths to route water away from structures and regulating impervious cover. Development and redevelopment are managed to reduce flood risk for new and changing properties while not adversely affecting the rights of other property owners. Private developers are not required to take action to benefit downstream properties; however, the City requires that private developers demonstrate ‘no adverse impact’ to downstream properties to ensure the action of any community or property owners, public or private, does not adversely impact others. 3.3.3.3 Outreach and Engagement Building an understanding of the flooding and drainage risks in the community is important for working toward resiliency. When a community understands its risks, it can take actions to mitigate risk before, during, and after a flood event. • The City maintains detailed maps regarding potential flooding and drainage issues, both regionally and locally, and shares this information via the City’s interactive water resources web map. • The City provides advice for reducing flood exposure and vulnerability for property owners and occupants. • The City has a Certified Floodplain Manager (CFM) to act as the local liaison for Federal Emergency Management Agency (FEMA) floodplain issues. The CFM provides technical assistance for Letter of Map Amendments, maintains elevation certificates, and interprets requirements for development and redevelopment that intersect with the FEMA regulated floodplain areas. • The City engages with stakeholders on flood risk reduction strategies, policies, programs, and projects. 3.3.3.4 Emergency Services and Public Safety The City’s role in emergency situations include responding to life, health and safety calls and supporting or restoring the operation of public utilities. Police, Fire, and Public Works perform the majority of emergency services activities related to rescue, restoration of critical services, etc. Planning and Building departments also play a role in recovering from hazards by implementing building codes and standards post-disaster. Critical facilities should be protected from flooding, and accessible and operable during a flood. Critical facilities are any public or private buildings or facilities that, by their nature if damaged, or rendered inoperable or lost during a disaster event, leads to a detrimental loss of health and welfare services within Flood resiliency resources including ‘Actions for Flood Resilient Homes’ factsheets and an interactive ‘What is My Flood Risk?’ map are available at www.EdinaMN.gov/flooding. No Adverse Impact means development projects are mitigated so they do not make conditions worse for others. Development is done in a manner that does not pass the cost of flooding on to others. City of Edina 2022 Water Resources Management Plan 3-18 the community (ASFPM, 2016). Critical facilities in the FEMA regional floodplain are regulated by the Floodplain Overlay Districts Ordinance (City Code, Chapter 36). Critical facilities include: • Police and fire stations • Emergency Operations Centers • Hospitals and other medical and health care facilities • Communications networks such as radio, telephone, and television • Electrical lines, transformers • Commuter rail lines and stations • Retirement homes and senior care centers • Schools • Hazardous materials storage areas • Water and wastewater treatment facilities • Local government offices and facilities necessary for provision of essential services • Emergency shelters • And other facilities determined to be critical by staff 3.4 Clean Water The streams, ponds, lakes, and wetlands in the City of Edina are important community resources. These resources supply aesthetic and recreational benefits, in addition to providing wildlife habitat and other ecological benefits. The City recognizes the need to protect and improve these resources and strives to manage the City’s stormwater infrastructure and assets so that the beneficial uses of its lakes, streams, ponds and wetlands remain available to the community. Protection and improvement of these resources encompasses operating and maintaining the City’s existing assets (see Section 3.2), implementing programs to educate and engage the community, developing and implementing pollution reduction strategies, and completing capital improvements. 3.4.1 Clean Water Infrastructure Municipal stormwater systems provide multiple functions, including water quality protection. Infrastructure used to provide clean water services generally includes underground hydrodynamic separators (also termed grit chambers), sump manholes, constructed ponds, underground storage and infiltration facilities, and bioretention basins, among others. Green stormwater infrastructure (GSI) includes engineered systems that mimic natural systems to treat polluted runoff. Examples of GSI features include bioretention basins, bioswales, constructed ponds, and tree trenches. This infrastructure serves to remove pollutants such as sediment and phosphorus from stormwater prior to the stormwater being discharged to downstream water resources. City of Edina 2022 Water Resources Management Plan 3-19 Much of the city of Edina was developed prior to significant focus on protecting the quality of surface waters. As a result, stormwater from large portions of the city discharges directly to wetlands, lakes, or the creeks without passing through clean water infrastructure. The City is responsible for operation and maintenance of the city-owned public stormwater infrastructure assets, including clean water infrastructure. Stormwater assets constructed on private property are generally the responsibility of the private property owner, which includes operating and maintaining the facilities in proper condition, consistent with the original performance design standards. Additional information regarding operation and maintenance of public and private stormwater infrastructure is provided in Section 3.2. 3.4.2 Clean Water Programs The City of Edina seeks to protect and improve its water resources through implementation of several clean water programs, including promoting community engagement, pollution prevention through site reviews and implementation of city ordinances, policies, and design standards during and after construction, pollution source control, lake and pond management, and implementing stormwater best management practices. These programs accomplish minimum regulatory standards and, in many areas, move beyond the minimum standard. Details regarding the measurable goals, implementation schedule, and responsible parties for the minimum standards as required by the MS4 permit can be found in the City of Edina’s SWPPP. 3.4.2.1 Community Engagement Community engagement is a key component in a successful stormwater management program. The City recognizes that an informed residency is necessary to make progress toward meeting water resources goals. Programmatic activities are designed to build a culture of water resources stewardship necessary to influence change on the landscape. Residents value water resources and City staff seek to involve them in addressing issues through informing, educating, and promoting participation. The City has developed and is implementing a public education and engagement plan to distribute information and conduct outreach activities regarding the impacts of stormwater discharges on water bodies. The City’s education and engagement plan identifies the audience involved, educational goals, activities used to reach goals, activity implementation plans, and available performance measures that can be used to determine success in reaching educational goals. The community engagement plan also includes working collaboratively with the local watershed districts in distributing educational materials and promoting/supporting outreach programs. Annually, the City hosts an opportunity for the public to comment on the SWPPP and water resource programs, although comments may be submitted at any time of the year. This has been done as a standalone meeting or in addition to another engagement event. Notice of the meeting date, time, location, and materials is distributed through various communication channels including the local City of Edina 2022 Water Resources Management Plan 3-20 newspaper. Oral and written input from the public regarding water resources programs will be sincerely considered and adjustments will be made where appropriate. The City also hosts a booth at the annual Open Streets on 50th event with the help of Minnesota Water Steward volunteers to engage the public in water resources topics. A presentation of issues, future activities, and completed projects is also brought to the Edina Energy and Environment Commission with the Annual Water Resources Coordinator’s report. 3.4.2.2 Pollution Prevention Site Plan Review and Design Standards The City of Edina has adopted the policies and performance standards discussed in Section 4.0 to promote pollutant prevention and/or reduction from new development and redevelopment areas. These policies are enforced through the site plan review process and through permits issued by the City or respective watershed district. The City of Edina also addresses runoff problems with sound planning procedures. Land use and zoning ordinances promote improved water quality by guiding the growth and redevelopment of the community away from sensitive areas and by restricting certain types of growth to areas that can support it without compromising water quality. Pollution Prevention Practices Pollution prevention and good housekeeping practices can ensure a reduction in the amount and type of pollution that is discharged to downstream water resources from streets, parking lots, open spaces, and storage and vehicle maintenance areas. Many pollution prevention practices are incorporated into the City’s infrastructure operation and maintenance program (see Section 3.2.3.1). Other practices that the City implements are more programmatic in nature, including the following: 1. Employee training on incorporation of pollution prevention techniques into municipal operations such as park and open space maintenance, fleet and building maintenance, road salt application, new construction and land disturbances, and stormwater system maintenance. 2. Periodically evaluating city landscaping and lawn-care practices, which may include the use of fertilizers, pesticides, herbicides, lawn mowing, grass clipping collection, mulching and composting, and developing or modifying practices to reduce stormwater pollution. 3. Periodically reviewing practices and policies related to road salt applications, including consideration of alternative products, calibration of equipment, inspection of vehicles and staff training to reduce pollutants from road deicing activities. 4. Evaluating, annually inspecting, and modifying (if necessary) current management practices for all exposed stockpiles, storage, and materials located within City-owned property. City of Edina 2022 Water Resources Management Plan 3-21 5. Continuing the City’s street sweeping program, including evaluation and identification of potential program improvements, and implementation of changes, as necessary, to reduce stormwater pollutants. 3.4.2.3 Pollution Source Controls Illicit Discharge Detection and Elimination Identification of stormwater pollutant sources includes identification of illicit pollutant discharges and nonpoint sources throughout the city. An illicit pollutant discharge is defined as a non-permitted point source of pollutants that is discharged to the storm sewer system at a specific location. Illicit discharges can enter a storm sewer system directly (through wastewater piping mistakenly or deliberately connected to the storm drains) or indirectly (through infiltration from cracked/leaking sanitary systems, spills collected by drain outlets, or other contaminants such as paint or oil dumped directly into a storm drain). To prevent the harmful effects of illicit discharges, a number of management practices have been developed to implement and enforce a program to detect and eliminate illicit discharges into the City’s stormwater system. The City’s illicit discharge detection and elimination program includes the following components: 1. An annually-updated storm sewer system map showing the location of all City-owned storm sewer pipes (24-inch diameter or greater), outfalls, locations where discharge leaves the City, and water bodies. 2. Periodic review of existing City ordinances relating to illicit discharges and develop/revise an illicit discharge ordinance as necessary. 3. Expansion of the City’s program to detect and reduce all forms of non-stormwater discharges and continuation of inspection for illicit discharge during the outfall and pond inspections. 4. Distribution of educational materials to residents and providing illicit discharge educational information or annual training for City staff. Construction Site Stormwater Runoff Control Runoff management from construction sites minimizes the amount of sediment and other pollutants entering the water bodies within the city. The City implements the erosion control policies identified in Section 4.2, including the following activities: 1. Permits for land disturbing activities consider erosion and sediment control. 2. Construction site operators must provide a phone number, website, and point of contact for the public to report stormwater pollution issues. 3. Construction site operators must conform to MPCA, watershed district, and City ordinances pertaining to erosion and sediment controls and waste controls. City of Edina 2022 Water Resources Management Plan 3-22 The City enforces erosion and sediment control and stormwater management on lots >1 acre in size, and has limited stormwater, erosion and sediment control standards for sites under 1 acre associated with grading or demolition permits. The City also requires that project applicants or owners contact the NMCWD or MCWD to determine if watershed district permits are required. 3.4.2.4 Lake and Pond Management The City has established policies to guide its management of lakes and other water resources within the city (Section 4.2 and Section 4.4) and works closely with the watershed districts to protect and improve the quality of these resources. This generally includes participating in water quality studies and planning activities within the watershed districts and other agencies and implementing stormwater management practices and programs to reduce pollutant contributions. In 2014, the City established a lake and pond management policy to manage residents’ requests for lake management activities, which tend to focus on aquatic vegetation management. The policy establishes a system to prioritize the waterbodies, defines management service levels, and lays out a process to involve shoreline owners in waterbody management. The City encourages residents to form Lake Associations and lake groups to advocate for management of waterbodies. An association is a voluntary organization made up of people who own land on or near a body of water. Landowners often form an association when they are concerned about issues regarding the quality or use of the body of water and want to deal with them in an organized manner. Lake groups are less formal and may be more appropriate for some smaller waterbodies. In some cases, a formal or informal group is required for a waterbody to be eligible for services under the lake and pond management policy, which is mostly centered around aquatic vegetation management. Forming an association has several benefits, including: • At a minimum of once per year, a meeting is held to discuss topics related to the waterbody. This approach encourages representation of all stakeholders and decisions that are based on the majority. Grant opportunities and petitions have more merit when brought forth by a coordinated group that represents the majority. • Recommendations for treatment come from local residents instead of city staff. An association meets with members to gather feedback and recommend annual treatment. The association Board of Directors would then request that the city coordinate treatment and special assess costs back to the special assessment district. Alternatively, the group could operate independently of the city to coordinate and pay for services on their own. Local ordinances and DNR permit requirements would still apply. • Information can be shared between the city and the association more effectively. • Organizing around the shared resource can build a culture of water stewardship. Associations may opt to organize a block party or lead an education campaign. City of Edina 2022 Water Resources Management Plan 3-23 The organization can potentially organize and fund additional elective activities. Examples might include a social event or special study. Aquatic Vegetation Aquatic vegetation has an important place in the ecosystem of lakes and ponds. It provides food and shelter to fish and wildlife, and uses phosphorus for its growth, isolating it from the water column and limiting algae growth. While aquatic vegetation is beneficial to aquatic life and water quality, it can also be a detriment to recreation and sometimes aesthetics, especially when excess nutrients cause overgrowth. Aquatic Vegetation Treatment Request Process The City manages requests for aquatic vegetation treatment using the following system established to prioritize the waterbodies, define management service levels, and lay out a process to involve shoreline owners in waterbody management: Step 1: Use the following classification to determine the points awarded based on waterbody size. Size Points Awarded • Large (10+ acres) 4 • Medium (5-9.9 acres) 3 • Small (2.5-4.9 acres) 2 • Tiny (1-2.4 acres) 1 • <1 acre Not eligible for management by City Step 2: Use the following classification to determine the points awarded based on water quality of the water body. Water Quality Points Awarded • 303(d) Impaired Waters List 4 • Drains directly to impaired water or a waterbody which meets water quality goals and is in protection mode 3 • Data shows that waterbody does not meet applicable state or watershed water quality goals 2 • No data 0 Step 3: Sum points awarded from Steps 1 and 2. City of Edina 2022 Water Resources Management Plan 3-24 Step 4: Use the following classification to determine initial service level based on points awarded. Service Level Points Required • High 7-8 • Medium 5-6 • Low 3-4 • None 0-2 Step 5: If any of the following apply the service level can be raised*: • forming an informal lake group or formalized lake association with 50% plus one of the shoreline properties represented , or • providing significant public access and use *Water bodies may only move up one service level, even if they have both an association and public access. The system described above is used to define the City’s management service level for a given lake. The service level for many waterbodies have already been determined and can be accessed online via the City’s Water Resources Library. Contact the City for the most up-to-date list. Table 3.2 identifies the level of potential lake management activity, depending on the established service levels. Table 3.2 Level of Potential Lake Management Activity by Service Level City-Funded Activities Additional Elective Services* Service Level Whole lake algae treatment (as permitted/ required) Invasive aquatic plant treatment** Lake study (up to 2 lakes per year) City staff support (see Table 3.3 below) DNR Permits and Facilitation Aquatic vegetation management Alternative methods (see Table 3.3 below) DNR permits and facilitation High Yes Yes Yes Yes Yes Yes Yes Yes Medium Yes Yes Yes Yes Yes No No No Low Yes Yes No Yes Yes No No No None At City’s discretion, lowest priority No No No *Cost of elective services are special assessed to property tax bill. This option requires a formalized lake association, registered as a nonprofit organization in the state of Minnesota, as described in the policy. **Invasive aquatic plant treatment will be pursued to the extent that it limits the spread, fits within budget, cost/benefit analysis supports it, and has a clean water benefit. Invasive aquatic plant treatment will not be completed solely to accomplish a recreation or aesthetic goal. City of Edina 2022 Water Resources Management Plan 3-25 Table 3.3 City Staff Support Activities and Alternative Methods Related to Table 3.2 City staff support activities (related to Table 3.2 above): Alternative methods (related to Table 3.2 above) Association/group formation All alternative methods (such as barley straw, floating treatment wetlands, etc.) are elective services. Education There may be some cost share available from the city. Facilitate data collection Facilitate group projects Technical resource Duckweed Management The City will not participate in destruction or removal of duckweed for recreational or aesthetic purposes. Cattail Management The City will only manage cattails such that they don’t obstruct water flow. The City will not participate in destruction or removal of cattails for recreational or aesthetic purposes. Requesting a Lake Study Requests for lake studies must be submitted in writing to the City’s Water Resources Manager. The request must meet the following criteria: • Come from a formal or informal group, representing the majority of residents. Where there is a formal group, the board may submit a request on behalf of the group. Where there is an informal group, signatures from representatives of 50% plus one properties surrounding the resource must provide a signature in support of the request. • Identify what the group hopes to accomplish with a lake study, specifically indicating what questions they hope to have answered. • Waterbodies will be eligible for lake studies once every 5-year period. • Requests for lake studies will expire after 9 months. • Requests will be received on a first come, first served basis with new applicants receiving preference. • Lake study scope will be limited by annual budget. • Up to two lake studies will be funded per year, contingent upon annual budget. 3.4.3 Clean Water Strategy The City is in the process of developing a clean water strategy that outlines a plan for working toward meeting its clean water goals. The strategy will address the City’s approach to meeting the pollutant reduction targets identified through the TMDL and WRAPS process. The strategy will also determine pollutant load reduction targets for nondegradation of water bodies that are not impaired and identify an City of Edina 2022 Water Resources Management Plan 3-26 approach for achieving these stormwater management targets. The clean water implementation strategy will be a 5-year strategy that identifies regular “good housekeeping” stormwater practices and clean water capital improvement projects (CIP) to achieve the goals, including quantification of pollutant removals and preparation of planning-level cost estimates. This information will be used for planning, as well as assessment of cost-benefit for project prioritization. The implementation strategy will be developed in coordination with street reconstruction projects, redevelopment, and other opportunities. Annual or biennial reporting will be included in the strategy to quantify movement toward the City’s goals and track activities for the City’s annual SWPPP and MS4 reporting. When completed, the Clean Water Strategy will be included as an amendment to this WRMP. 3.4.3.1 Implementation Approach The Clean Water Strategy will define clean water goals, estimate the cost and pace of achievement, and identify implementation opportunities including the following categories: • Redevelopment- implementation of stormwater management rules as part of redevelopment • Redevelopment- expansion of site or regional stormwater management beyond compliance with stormwater management rules • Retrofit- implementation of stormwater management as part of City street reconstruction projects on public land • Retrofit- targeted implementation of stormwater management BMPs for improving water quality of an impaired water body; these BMPs may require land acquisition • Retrofit- implementation of stormwater management BMPs in partnership with other public- or non-profit landowners • Re-design/re-purpose- implementation of stormwater management BMPs as part of city improvement projects (e.g., park improvements, city facility improvements) Each of the clean water improvement opportunity categories identified above have opportunities for partnership with other entities, such as private landowners, watershed districts, non-profit organizations, or other local governmental entities. 3.4.3.2 Opportunity Identification and Prioritization The City will pursue clean water improvements that maximize cost effectiveness and capitalize on coinciding opportunities, such as planned street reconstruction, redevelopment efforts, availability of land, or other planned infrastructure improvement projects. Consideration will also be given to achieving additional “co-benefits”, such as flood risk reduction, recharge of shallow groundwater aquifers, wildlife habitat improvement, and groundwater conservation. City of Edina 2022 Water Resources Management Plan 3-27 BMP Cost Effectiveness Stormwater best management practices (BMPs) have a wide range of cost effectiveness, depending on factors such as the suitability of soils for infiltration of stormwater and the availability and cost of land. Soil Suitability for Infiltration Infiltration-based stormwater BMPS are often most effective in reducing stormwater volume and pollutant loading to downstream water bodies. Infiltration describes a process where stormwater runoff seeps into the soil. Because the water stays near to where it lands, the volume of runoff (and associated pollutants) delivered downstream is reduced. Infiltration also recharges groundwater and treats stormwater through natural filtration. This is particularly valuable when lakes, wetlands, or trout resources are downstream. Infiltration-based stormwater BMPs are not very practical in soils with low infiltration capacity, such as tight silts or clays, where the infiltration rate is severely limited. Infiltration is also not recommended in locations where soils are contaminated, within sensitive drinking water recharge areas, where groundwater is shallow (less than three feet below the surface) or where karst features or bedrock are prominent. As part of its Clean Water Strategy, the City will conduct a desktop analysis to identify and prioritize locations where implementation of infiltration-based stormwater BMPs is feasible. Favorable locations would include areas where soil conditions are conducive and negative impacts are unlikely. The analysis may also include identification of areas where the potential for flood-risk can be reduced. These locations would then be prioritized based on an analysis of total construction and maintenance costs, availability of land, and infiltration benefits, including consideration of downstream water body. Prioritized locations could become part of the City’s future BMP implementation program. Land Availability Given that the City of Edina is essentially fully developed, the availability of land for implementation of stormwater management practices is limited. Installing stormwater BMPs in city-owned right-of-way is often challenging due to limited space and conflicts with existing utilities and infrastructure. Beyond the right-of-way, the primary city-owned land consists of parkland. While implementation of stormwater BMPs in the City’s parks can be cost effective, the parkland within the city is in high demand, with an ever increasing demand for programmed athletic fields, which severely limits the availability of land for stormwater management practices. There may be opportunities to retrofit stormwater BMPs on existing privately-owned sites; however, parking requirements or demand can severely restrict the available land for stormwater BMPs. As redevelopment occurs throughout the city, there is significant opportunity to implement site-based or regional stormwater management practices. However, development densities appear to be generally increasing, and parking requirements and other site constraints are limiting the feasibility of implementing above-ground stormwater management practices. Given the limited availability of land for installing conventional, above-ground stormwater BMPs, many private landowners and water managers are pursuing underground BMPs that can be installed within right-of-way and/or parking areas. While these BMPs are desirable to many because they allow for co- City of Edina 2022 Water Resources Management Plan 3-28 existing with other site uses, the cost for underground stormwater practices is higher than above ground. There is also concern about the maintenance costs and feasibility of the underground systems. Co-benefits of BMPs The City’s Clean Water Strategy will also consider achievement of additional “co-benefits”, such as flood risk reduction, recharge of shallow groundwater aquifers, wildlife habitat improvement, and groundwater conservation. Reuse Studies can evaluate effective ways of reusing rainwater, stormwater, greywater, wastewater, and industrial water. Reuse is important because it helps the City achieve its stormwater management goals, conserve water, meet permit requirements, develop sustainable water supplies, reduce costs, and improves the City’s triple bottom line. Identifying water reuse opportunities often begins by asking the following questions: • Who uses water? • Where is there a lot of water? • Where is there a high water demand? • What is the quality of available water? • What level of water quality is needed to meet the end user’s needs? • Is reuse technically feasible? Qualitatively feasible? The City will conduct a desktop analysis to identify and prioritize locations where stormwater reuse systems could be implemented (see Table 3.5). A geographic information system (GIS) screening-level analysis could be performed to identify potential reuse opportunities within the city—matching water sources to water needs. For example, both water sources and water users can be identified by mapping publicly available data (e.g., NPDES discharge permit data and appropriations permit data, respectively). GIS can also help identify potential sources of water in close proximity to potential users (including parks and golf courses that need water for irrigation). Other potentially useful data includes soils data (permeability, salinity), topography, storm sewer and sanitary sewer data, utilities data (gas/communication/power utilities), groundwater data, water supply well data, and water sales data. 3.5 Management Approach The City will actively apply the water resources management policies and implement the programs and projects identified in this Water Resources Management Plan by: • Applying the policies and Plan to all clean water and flood improvements, including those involving operations, maintenance, improvements, and qualifying private development/redevelopment. City of Edina 2022 Water Resources Management Plan 3-29 • Leveraging all sources of clean water funding and actively pursuing grants, cost-sharing opportunities, project partnerships and other new or special funding sources as applicable. • Drawing on technical support and feedback from partner agencies, organizations, and groups. • Embracing a systems approach to solve water resources problems; considering multiple uses, sources, and waste streams of water. • Advocating for water resources strategies consistent with this plan when a local land use decision is under the jurisdiction of another agency. • Adapting to new knowledge and challenges, using the best science to guide decision-making. • Coordinating efforts with supporting plans and programs; o Current Edina Comprehensive Plan o Edina Climate Action Plan o Parks Strategic Plan o Floodplain Districts Ordinance and National Flood Insurance Program o Living Streets Plan o Source Water Protection Plan o Wellhead Protection Plan o Stormwater Pollution Prevention Plan and Municipal Separate Storm Sewer System (MS4) permit o Nine Mile Creek Watershed District Water Management Plan o Minnehaha Creek Watershed District Water Management Plan o Minnehaha Creek Watershed District’s ‘Guide: Community Adaptation Planning for Changing Landscapes and Climate’ o Hennepin County’s Natural Resources Strategic Plan o Residential and commercial permitting Beyond prioritizing and allocating resources to accomplish the minimum standard as required by the City’s MS4 permit and SWPPP, this plan aims to prioritize projects and budgets to meet defined levels of service, where achievable. The Clean Water Strategy (pending) and Flood Risk Reduction Strategy identified in this plan establish specific goals, priorities, and associated costs to better describe the investment needed for the City to achieve its defined level of service. The rate of progress in meeting the desired level of service will be determined by resources, funding, opportunities, and policy alignment. 3.5.1 Coordination with Watershed Districts 3.5.1.1 Regulation The City of Edina manages stormwater to protect life, property, waterbodies within the city, and receiving waters outside the city. However, the City relies heavily on the NMCWD and MCWD for implementation of water resource protection rules and requirements. The City defers LGU authority to the NMCWD and MCWD for floodplain management and drainage alterations, wetlands management, stormwater management, erosion and sediment control, waterbody crossings and structures, shoreline and streambank improvements, and sediment removal. City of Edina 2022 Water Resources Management Plan 3-30 The City of Edina also defers LGU authority for the WCA to the NMCWD and MCWD. This includes requiring and verifying that all projects impacting wetlands meet the requirements of the Minnesota WCA. The Board of Water and Soil Resources serves as both a state administrator of the programs associated with the WCA, as well as providing technical assistance to LGUs administering the WCA. Water resources management is complex and establishing broad, durable boundaries around responsibilities is challenging. We intend to continue to collaborate with our Watershed District partners to identify issues, define leading and supporting roles and responsibilities, and make progress toward our shared interest in water resources stewardship. The City and Watershed Districts have consistently demonstrated a willingness to advance policies and projects in a collaborative spirit and the portfolio of past performance informs future partnerships. Further, the City and Watershed Districts share an interest in regulatory streamlining to minimize the burden on regulated parties and will work collaboratively when a project presents particular complexities. 3.5.1.2 Data and Information The MCWD and NMCWD collect and maintain numerous regional data collections and models that are made available for use by the City of Edina. Below is a list of data and models available from one or both of the watershed districts and a brief description of how the City has or will utilize these resources. Hydrology and hydraulics (H&H) model – provides information on regional flood elevations and hydraulics. The City has used the NMCWD Atlas 14 H&H model to evaluate impacts from proposed drainage modifications and as a base for the Atlas 14 model updates in support of the 2018 WRMP and subsequent annual model updates completed to support this iteration of the WRMP. The City used the MCWD H&H model for estimating Atlas 14 tailwater conditions in Minnehaha Creek for the City’s Atlas 14 model updates in support of the 2018 WRMP and subsequent annual model updates conducted to support this iteration of the WRMP (see Appendix A – Attachment B). Atlas 14 Flood Elevations– provide information on base flood elevations for development and redevelopment. The City relies on the NMCWD and MCWD to provide 1-percent-annual-chance flood elevations for Regional Flood Areas throughout the city (see Section 4.1). While the MCWD has not yet published Atlas 14 flood elevations for Minnehaha Creek, the City of Edina looks forward to utilizing these values when available to consistently provide flood risk reduction based on Atlas 14 precipitation frequency estimates citywide. MCWD Functional Assessment of Wetlands (FAW) – provides data on wetland functions and values, establishes management classifications based on quality and sensitivity, and identifies restoration opportunities for wetlands within the Minnehaha Creek watershed (Hennepin Conservation District, 2003). The City incorporated the results of the FAW into its 2011 and 2018 WRMP (see Section 2.2.7.2). Stream Assessments – provide data on biological and physical condition of streams. The NMCWD collects benthic macroinvertebrate and fish samples annually from the North Fork of Nine Mile Creek near Metro Boulevard in Edina and conducts periodic physical condition assessments. This information has been used to identify changes in stream water quality that may be caused by nonpoint source pollution City of Edina 2022 Water Resources Management Plan 3-31 and provide a more complete understanding of overall stream health. Specifically, the data was used to complete the Nine Mile Creek biological stressor identification study (MPCA, 2010) and design the Edina Streambank Restoration project constructed by NMCWD from 2017-2019. The MCWD has conducted limited periodic biological monitoring of Minnehaha Creek (e.g., Zebra Mussel monitoring, fishery survey) and project-specific physical condition assessments within Edina. Hydrologic and Water Quality Data Reports – provide data on water quality, water quantity, and ecological integrity conditions and trends for District resources. The NMCWD and MCWD collect and analyze hydrologic (stream flows, lake levels) and water quality data at numerous locations within Edina, including Minnehaha Creek (downstream of the Browndale Dam), North Fork of Nine Mile Creek (at Metro Boulevard), and numerous lakes. This information is used by the City to track water quality conditions and trends and identify the need for additional lake and watershed management. Educational Resources – provide education and outreach information regarding water resources best management practices. The City has utilized the information and trainings offered by the MCWD and NMCWD to support and bolster their education program. 3.5.1.3 Land Use Planning Opportunities The MCWD Watershed Management Plan (2018) and NMCWD Water Management Plan (2017) both highlight the desire to more closely integrate land use planning and water resource management to capitalize on opportunities to improve water resources as development and redevelopment occurs. Given that land use planning lies primarily with the cities, achievement of this goal will require close coordination and partnership between the Watershed Districts and cities. Coordination Plan To achieve the level of coordination and communication required to successfully capitalize on opportunities to improve water resources as part of land use planning, the City will strive to conduct the following activities: • Participate in an annual meeting to review water resource plan implementation, to be coordinated by the WDs. Parties will discuss how the WDs can receive notice of and consult on land use, infrastructure, park and recreation, and capital improvement planning efforts. • Transmit the annual NPDES MS4 report to WDs (mutual transmittal, if applicable) • Notify the WDs of the following: o Updates to road and infrastructure implementation programs. The City annually produces a map of anticipated road reconstruction and road maintenance projects for the next five years. o Updates to park and recreation plans. o Institution and completion of small area plans and other focused development or redevelopment actions. o Significant alterations within the City MS4 system (to maintain currency of the WD watershed-wide hydrology and hydraulics model). o Updates to the City’s Wellhead Protection Plan and associated programs. City of Edina 2022 Water Resources Management Plan 3-32 o Updates to the Capital Improvement Plan. • Partnership or coordination as to public communications and education. The WDs are asked to complete the following activities: • District notice to the City regarding watershed management plan amendments and annual capital improvement program updates. To capture CIP and budget planning, the annual meeting should occur early in the second quarter. The annual meeting will involve the City’s Community Development Director, Economic Development Manager, Engineering Director, Engineering Services Manager, and Water Resources Manager. The City welcomes and will accommodate requests from the WDs for additional meetings and communications that spur from the annual meeting. For elements the City and WDs identify for coordination, specific communication plans and schedules will be made. The Water Resources Manager will facilitate communication among appropriate parties based on the scope of the item. Conversations around water resources planning occur continuously throughout the year and are guided by this plan. It is common for various stakeholders across the community (public agencies, non-profit organizations, resident groups, city departments, and private entities) to be involved in work that has prominent or nuanced water resources implications. Some of the challenges of coordinating water resources planning include the number of stakeholders involved, balancing funding priorities, community attitudes, and the fact that plans and projects are often owned by others (and may have different schedules, values, and service targets). Due to the dynamic nature of various concurrent activities and planning efforts, maps of anticipated road reconstruction, potential park improvements, capital infrastructure investment/reinvestment, priority water resources issues, and private development are not provided here, but will be prepared ahead of each annual meeting. Spatial analysis tools allow for these pieces of information to be integrated annually, efficiently incorporating the best available information. The City and WDs have a history of partnership. The past successes have largely been the result of strong working relationships that promote regular conversations. The City is eager to continue and expand cooperative work in the following areas: • CIP and budget planning: The City’s process for this is described in more detail in Section 3.5.3. Internal review begins in second quarter, drafts are available for comment in third quarter, and City Council takes action in December of each year. • Private development and redevelopment: It’s common for large projects to go through a sketch plan review with City Council. The City will share known upcoming projects at the annual meeting. As WD staff develop relationships with the community and economic development staff at the City, they can regularly and informally check in with the City to stay abreast of private development and redevelopment activity. The City will facilitate a coordination meeting with private developers and the WDs at the request of the WDs. For projects that do not go through a sketch plan review, the City will inform permit applicants of the potential need for a WD permit City of Edina 2022 Water Resources Management Plan 3-33 and, when one is required, will not issue a City permit until the WD permit application has been made. • Public development and redevelopment: Described in more detail in Section 3.5.1.4. Because of our strong working relationship with the WDs, the City is continually seeking opportunities for coordination. This occurs through informal conversations as opportunities arise. Any future efforts including small area plans or other planning activity will be shared at the annual meeting. • Operation and maintenance: The City will inform the WDs of illicit discharges in a timely manner and share a summary of the illicit discharge detection and elimination program at each annual meeting. Additionally, the City will share its MS4 inspection results at each annual meeting. • Regulatory enforcement: As described in Section 3.5.1.1. • Education and engagement: As described in Section 3.5.1.2, the City will share its education and engagement calendar at each annual meeting. The City asks the WDs to continue to cross- promote and partner on events. In 2014, the City and Minnehaha Creek Watershed District initiated a Memorandum of Understanding (MOU) to describe the common goal of clean water among the agencies and outline spheres of collaboration in a number of areas including public education and outreach, development oversight, integrated capital improvements, and planning coordination. A copy of the MOU is available in the City’s Water Resources Library. More recently, conversations between the City and MCWD have focused increasingly on the common goal of reducing and managing flood risk. The MCWD is working to develop a two-dimensional hydraulic and hydrologic model, for which the City and the MCWD are partnering on a pilot model build, to better understand risks at a watershed scale and work cooperatively with communities to manage them. The MCWD has expressed a desire to work with the City to evaluate the cumulative downstream effects of the projects and policies in the City’s Flood Risk Reduction Strategy. While many of the proposed changes, such as floodplain fill to elevate homes out of the floodplain or pipe upsizing to reduce structure flooding, can be modeled to show no increase in flood stage on an individual project basis, the cumulative effect across multiple projects is not well understood. The City is committed to working cooperatively with the MCWD to understand and prevent or minimize downstream impacts that may result from the City’s flood risk reduction efforts, including: • Coordination on a project-specific basis to evaluate options to manage flood risk • Advising MCWD in its development of a two-dimensional model to inform flood risk management policies • Exploring opportunities to partner with MCWD on regional flood storage projects • Updating the MOU between the City and MCWD to reflect this intent City of Edina 2022 Water Resources Management Plan 3-34 3.5.1.4 Implementation Partnership Opportunities The City will work closely with the NMCWD and MCWD to identify and implement water resource protection or improvement partnership projects. While some opportunities may be associated with development and redevelopment, other opportunities will be focused on land owned by the City. Figure 3-3 shows the city-owned parcels throughout the city. A recent example includes cooperative efforts with MCWD to address clean water, drainage issues, and civic engagement in Arden Park and cooperative efforts with NMCWD to construct a stormwater filtration BMP in Rosland Park and stormwater retrofit in Lynmar Basin. Anticipated future opportunities for water resource management or improvement partnerships associated with City-owned parks and property redevelopment include: Minnehaha Creek Watershed • Weber Park: Flooding issues (and clean water co-benefits opportunity), civic engagement • Grandview Green: Stormwater management, regional planning, permitting, civic engagement • Exploration of possible regional flood storage opportunities: Meadowbrook Golf Course, Pamela Park, existing pump stations at Melody Lake and near Interlachen golf course, and others Nine Mile Creek Watershed • Pentagon Park: Flooding issues (and clean water co-benefits opportunity), rule administration planning, civic engagement • Lake Cornelia: Clean water and flooding issues, civic engagement • Lake Edina: Clean water and flooding issues, civic engagement • Arrowhead Lake and Indianhead Lake: Clean water and flooding issues, civic engagement • Mirror Lake: Clean water and flooding issues, civic engagement This WRMP lays out a framework for working toward incremental improvement in water resource issues through the Flood Risk Reduction Strategy and Clean Water Strategy. Through Plan implementation, the City will continue to coordinate with the Minnehaha Creek Watershed District and the Nine Mile Creek Watershed District to involve the applicable watershed district in the development of programs, projects, and management strategies for each of the City’s focus areas. 3.5.2 Development Review Process and Land Use Planning The City utilizes its Development Review process to address stormwater management and ensure water resource protection within the City. Engineering staff review development and redevelopment proposals to ensure that the stormwater management policies and performance standards detailed in Section 4.0 of this plan are met. Engineering staff also consult the City’s Wellhead Protection Plan to ensure that development and redevelopment proposals are in line with the protective measures established for the City’s sensitive groundwater resources. Staff from the City’s planning department review development and redevelopment proposals with the guidance of the City's long-range Comprehensive Plan and Zoning Ordinance. In addition to incorporating the policies and design standards of this WRMP, the Edina Comprehensive Plan (City of City of Edina 2022 Water Resources Management Plan 3-35 Edina, 2018) includes policies, principles, and guidelines that integrate water resources protection and management with land use planning. Among these include the City’s land use policy to “grow and develop sustainably to protect the natural environment, promote energy efficiency, conserve natural resources, and minimize the impacts of buildings on the environment” and to “maintain the current open space and wetlands acreage and seek to expand it whenever possible”. The Comprehensive Plan encourages reductions in impervious surfaces and associated stormwater runoff from redevelopment sites and parking lot design that promotes stormwater infiltration, and also encourages protection and improvement of urban forests, which provides stormwater management benefits, among others. Additionally, the Edina Comprehensive Plan includes procedures for planning, programming, and implementing transportation infrastructure, sewer and water infrastructure, and park, recreation, and natural area management. These plans coincide with the timing of the local comprehensive planning timeline and support the Transportation, Water Resources, and Parks & Trails elements of the comprehensive plan. The City’s zoning ordinance is used by staff in the planning department to guide development and redevelopment within the city. The zoning ordinance establishes required setbacks from naturally occurring lakes, ponds, and streams. In some cases, the buffer requirements of the watershed districts may be more stringent, upon which the watershed district requirements supersede. The City’s zoning ordinance also addresses development within the floodplain districts of the city. Small Area Plans outline a long-range vision for land use and development in a very specific area of the City based on input from residents and business representatives. A list of completed and upcoming Small Area Plans is available on the City’s website: www.EdinaMN.gov/657/Small-Area-Plans. The City of Edina is basically fully developed; thus, land alteration activities are primarily of a redevelopment nature. As the city redevelops, the City utilizes the policies of the Edina Comprehensive Plan, the zoning ordinance, and this WRMP to encourage low-impact site design. The City also relies on implementation of the rules and regulations of the NMCWD and MCWD. 3.5.3 Prioritization Prioritization of projects occurs within the City’s Capital Improvement Program and budget and is determined by the City Council with guidance from City Staff and the Water Resources Management Plan policies and implementation activities. Top priority projects will be those that: • Have measurable, long-term improvements to water quality, especially for waterbodies that are on the 303(d) Federal List of Impaired Waters or have data suggesting that the resource is not meeting clean water goals. • Measurably reduce risks of flooding for principal structures. • Combine clean water and flood resiliency benefits. City of Edina 2022 Water Resources Management Plan 3-36 • Solve drainage problems and reduce risk or consequence of flood, while maintaining or improving water quality. • Provide the most service for the least cost. The City’s Capital Improvement Program (CIP) is a five-year plan for capital improvements that is updated annually. The CIP process includes analyzing projects contributing to public health and welfare, projects helping to maintain and improve the efficiency of the existing systems, and projects that define a future need within the community. The City implemented a two-year budget cycle process which takes an alternating year approach to the operating budget and CIP processes. While both the operating budget and CIP are reviewed every year, the majority of the planning, focus and effort will alternate between the two. During even-numbered years, the City’s focus will be on the CIP. Extra efforts are dedicated to reviewing the projects in the CIP and prioritizing them based on information available at the time. The operating budget is reviewed but only updated if necessary. During odd-numbered years, the City’s focus will be on the operating budget. Extra efforts are dedicated to resident engagement processes and a two-year operating budget. The CIP is reviewed but only updated if necessary. During 2022, the City will develop the 2023-2028 CIP, with opportunities for public review and comment. City Council formally adopts a CIP near the end of every even-numbered year. A copy of the most current Capital Improvement Plan is available on the City’s website at http://www.edinamn.gov/273/Finance. 3.5.4 Resources The resources available to implement the Water Resources Management Plan include: • City staff and equipment. • Partnerships that leverage technical assistance, funding, and accomplish multiple overlapping goals. • Coordination of project planning and implementation across City departments and with private development and redevelopment. • Investments in stormwater management by others, driven by regulatory demand. 3.5.5 Financial Considerations Implementation of the proposed regulatory controls, programs and improvements that are identified in the plan will have a financial impact on the City. To establish how significant this impact will be, a review of the means and ability of the City to fund these controls, programs, and improvements is necessary. Table 3.5 lists potential sources of revenue for implementation of the water resources management efforts outlined in this plan. City of Edina 2022 Water Resources Management Plan 3-37 Table 3.4 Potential Funding Sources for Plan Implementation Description of Funding Sources Revenue Generated 1. Revenue generated by City’s Stormwater Utility. $5,400,000/yr (budgeted for 2022) 2. Special assessments for local improvements made under the authority granted by Minnesota Statutes Chapter 429. Variable depending on activities undertaken 3. Revenue generated by the Watershed Management Special Tax Districts provided for under Minnesota Statutes Chapter 473.882. Variable depending on activities undertaken 4. For projects being completed by or in cooperation with NMCWD and MCWD, project funds could be obtained from watershed district levies associated with their administrative funds, construction funds, preliminary funds, repair and maintenance funds or survey and data acquisition funds, as provided for in Minnesota Statutes Chapter 103D.905. Variable depending on activities undertaken 5. Grant monies that may be secured from various local, regional, County, State, or Federal agencies. This would include MnDOT, MPCA, Metropolitan Council, the MnDNR, and others. Variable depending on activities undertaken 6. Other Sources: These may be other sources of funding for stormwater activities such as tax increment financing, state aid, etc. The City will continue to explore additional revenue sources as they become available. Variable 7. Tax abatement. 3.5.6 Utility funding The stormwater utility fund was created to manage storm water runoff quality in concert with the local watershed. City projects often include repair and maintenance of stormwater infrastructure assets. Single family residential properties pay a fixed quarterly fee. Commercial property owners are charged based on the amount of impervious surface that does not allow rainwater to be absorbed into the ground. Over time, capital and programmatic costs for water resources management have increased to meet the demand for flood risk reduction and clean water services. To date, the stormwater utility has been able to keep up with improvements mandated by the state; however, complying with the minimum standard hasn’t enabled the City to reach clean water goals and sets out a timeline for accomplishing the goals that is far from reach. In order to see measurable improvements in flood risk management, drainage, and clean water services, the City will need to begin to plan financially for significant improvements to the system, beyond the minimum standard for annual operations and maintenance. As the City and watershed districts continue to evaluate and develop plans City of Edina 2022 Water Resources Management Plan 3-38 for polluted waterways, there will be pressure to generate more revenue to fund stormwater management systems. 3.5.7 Coordinated Policy Issues Solving flooding, drainage, and clean water issues in the City will require a variety of tools, practices, and partners. Various agencies are involved with flooding and clean water services or constrain or are affected by the provision of these services. Coordinating policies among various stakeholders including watershed districts, MPCA, DNR, city departments, and others will make delivery of these services more achievable. Some ongoing coordinated policy issues that have been identified include: • A need to understand the pace of progress and the investment needed to solve flooding, drainage, and clean water issues. Statewide there have been small moves in solving these problems. Technical obstacles (such as which practices are the most efficient, how to implement them, assurances that they are working as intended), as well as political obstacles (such as how much the city or other agencies are willing to invest and on what timeline) remains to be determined. • Alignment of the watershed district’s monitoring programs to include in-lake and BMP level monitoring necessary to confirm designed outcomes, set goals for pollution reduction, and prioritize future implementation. • A need to plan surface water outcomes in public infrastructure topics. Elevating the focus of flooding, drainage, and clean water issues in improvement projects as well as regular operation and maintenance. This should be driven by a defined service level. • Development of a program for inspection and maintenance of private stormwater BMPs. The City will engage with the watershed districts to determine if a cooperative framework where the City inspects private stormwater BMPS and the watershed districts enforce their maintenance agreements is feasible. • Aging infrastructure and deferred maintenance trends represent liability that stresses existing budgets. While much of the vast network of catch basins, ponds, outlets, and other stormwater infrastructure on both the public and private side are made of durable materials and have long design lives, they do require maintenance and will require reinvestment to continue to provide service. • Land use policies are connected to local flood risk. Increasing impervious cover and an already overtaxed public system make it difficult to keep up with local flood issues. • Flooding, drainage, and clean water services often compete for resources. The public demand for each service varies greatly. Without defined service levels, resources are often allocated to solve drainage issues or small flood issues while larger flood issues and clean water issues remain City of Edina 2022 Water Resources Management Plan 3-39 unresolved. An example of this is the public demand for pumping of lakes and ponds to manage water levels. Defining the levels of each service is necessary to make progress toward goals. • A need to build an understanding of flooding, drainage, and clean water issues among city departments to better incorporate water resources planning into city operations (parks, neighborhood roadway reconstruction, planning, economic development, permitting and development review). The City of Edina will continue to work with its decision-makers and partners to resolve these issues and/or conflicts, where possible. However, many of these remaining issues are challenging problems that may take significant time and effort to address. 3.6 Plan Update and Amendment Procedure It is the intention of the City to have this WRMP reviewed and approved by the NMCWD and MCWD. Once approved, no significant changes to this plan can be made without the approval of the proposed revisions by the watershed districts within the City that are affected by the change. Significant changes to the local plan shall be made known to the following parties: • City Manager, Director of Public Works, and City Engineer • Affected Watershed District within the City • Metropolitan Council • City Council Following notification of the above parties, they shall have 60 days to comment on the proposed revisions. Failure to respond within 60 days constitutes approval. Upon receipt of approvals from the affected watershed districts within the City, any proposed amendments will be considered approved. Minor changes to the Plan shall be defined as changes that do not modify the goals, policies, or commitments expressly defined in this plan by the City. Adjustment to subwatershed boundaries will be considered minor changes provided that the change will have no significant impact on the rate or quality in which stormwater runoff is discharged from the City boundaries. Minor changes to this plan can be made by the staff at the City without outside review. This WRMP will guide the City of Edina’s activities through 2028 or until superseded by adoption and approval of a subsequent WRMP. Amendments to the WRMP will be completed in accordance with MCWD and NMCWD watershed plans, consistent with 8410.0160. _______________________________________________ 1 To be determined City of Edina 2022 Water Resource Management Plan 3-40 Table 3.5 Water Resources Implementation Program Project Name / Location Description Proposed Improvement Cost Estimate ($) Proposed Year Funding Source Plan Amendments This Water Resources Management Plan may need to be amended periodically. This plan will be amended as required. As Required As Required SW Utility Plan Update/Revision This Water Resources Management Plan will expire in 2028 and will need to be updated/revised to be consistent with WMO plans and policies and state and federal rules. This Plan will be updated to maintain compliance with state and federal rules and WMO policies. 100,000 2027-2029 SW Utility Interactive GIS water resources web mapping tools Annual updates and maintenance activities for interactive GIS web mapping tool, as needed. Web mapping tool will have continued functionality and reflect most up-to-date information available. 2,000 Annual SW Utility City-wide education and resident involvement Create and implement City’s Education Plan including educational and outreach tasks. Maintain level of activity to involve and educate residents with various water related issues. 10,000/yr Annual SW Utility Illicit discharge detection and elimination Continue implementation of the Illicit discharge detection and elimination program. Inventory, mapping, inspection, enforcement and education. City Staff Annual SW Utility Construction site stormwater runoff control Maintain construction site stormwater runoff control program. Plan review, inspection, enforcement and education. City Staff Annual SW Utility Street Sweeping Pollution prevention through regular street sweeping. Strategic street sweeping in target areas and at optimal times to minimize pollution to surface waters. City Staff (3000 hours annually) Annual SW Utility Storm Infrastructure Asset Inventory Manage inventory of stormwater infrastructure assets. Actively manage database. Continue to incorporate private infrastructure and stormwater BMPs into inventory. Share stormwater network on interactive map. City Staff Ongoing SW Utility _______________________________________________ 1 To be determined City of Edina 2022 Water Resource Management Plan 3-41 Table 3.5 Water Resources Implementation Program Project Name / Location Description Proposed Improvement Cost Estimate ($) Proposed Year Funding Source Stormwater infrastructure asset inspections Inspection of stormwater infrastructure assets, public and private. Inspection and education. 60,000/yr Annual SW Utility Storm Infrastructure Asset Operations and Maintenance Operate and maintain stormwater infrastructure assets. Operations, maintenance, renewal, and replacement of stormwater infrastructure assets. City Staff (1400 hours annually) Annual SW Utility City facility operations and maintenance Manage city facilities to prevent pollution Regularly inspect facilities and adjust practices to prevent pollution City Staff Annual SW Utility Updates to Hydrologic and Hydraulic Modeling Annual updates to City’s stormwater management system modeling to reflect infrastructure improvements. Current, up-to-date modeling results. 28,000/year Annual SW Utility Impaired Waters Tracking and Review Monitor impaired waters list and respond with review and implementation. The City will remain informed and responsive to impaired waters issues. City Staff Ongoing SW Utility Flooding and drainage improvements Opportunistic flooding and drainage improvements to be addressed in street reconstruction projects, development / redevelopment, and other capital projects. 200,000/yr plus opportunistic Capital Improvement Projects Ongoing SW Utility Implementation of Stormwater Management Ordinance Adopt and implement a stormwater management ordinance reflecting the policies and design standards detailed in this plan. To be determined. Related to Flood Risk Reduction Strategy and Clean Water Strategy outcomes. City Staff TBD1 SW Utility _______________________________________________ 1 To be determined City of Edina 2022 Water Resource Management Plan 3-42 Table 3.5 Water Resources Implementation Program Project Name / Location Description Proposed Improvement Cost Estimate ($) Proposed Year Funding Source Wellhead Protection Plan Implement wellhead protection plan and provide plan updates to MCWD and NMCWD. Effectively manage and reduce where possible the number of potential contamination sources, namely private wells, through outreach and development review. City Staff Ongoing SW Utility Water Reuse Potential Investigate water reuse potential as opportunities arise. To be determined. City Staff Ongoing SW Utility Infiltration and Inflow reduction Reduce the amount of infiltration and inflow to the sanitary sewer system. Reduce the amount of infiltration and inflow to the sanitary sewer system. 600,000/year Ongoing SW Utility Implementation of Nine Mile Creek Chloride TMDL Implement the requirements of the Nine Mile Creek Chloride TMDL. BMPs per the Nine Mile Creek Watershed Chloride TMDL Report, to be incorporated into Clean Water Strategy. City Staff Ongoing SW Utility/ NMCWD/ Grant Funding Implementation of recommendations from the Lower Minnesota River WRAPS and NMCWD UAAs Partner with the NMCWD to implement the recommended remedial measures to improve the water quality of Lake Cornelia, Lake Edina, Nine Mile Creek. To be determined and addressed in Clean Water Strategy. TBD1 2018-2028 SW Utility/ NMCWD/ Grant Funding Participation in the NMCWD Mirror Lake Use Attainability Analysis (UAA) update and implement recommendations Partner with the NMCWD to update UAA and implement recommended remedial measures to improve the water quality of Mirror Lake. To be determined. TBD1 Ongoing SW Utility/ NMCWD/ Grant Funding Participation in the NMCWD Arrowhead and Indianhead Lakes Use Attainability Analysis (UAA) update and implement recommendations Partner with the NMCWD to update UAA and implement recommended remedial measures to improve the water quality of Arrowhead and Indianhead Lakes. To be determined. TBD1 Ongoing SW Utility/ NMCWD/ Grant Funding _______________________________________________ 1 To be determined City of Edina 2022 Water Resource Management Plan 3-43 Table 3.5 Water Resources Implementation Program Project Name / Location Description Proposed Improvement Cost Estimate ($) Proposed Year Funding Source Engineering Standards Development Continue to develop and implement stormwater management design standards. Consider ordinance changes as needed. City Staff 2018-2023 SW Utility Lake and Pond Management – aquatic vegetation Implement lake and pond management policy to manage requests for aquatic vegetation destruction. Algae treatments. Curlyleaf pondweed control. Special assessed aquatic vegetation management services. 45,000/yr Annual SW Utility and special assessments Clean Water Strategy Develop a water quality implementation program which outlines a plan for working toward meeting water quality goals. A tool to gain feedback from City Council and set the pace, location, and ultimate goal for clean water. Strategy to be reviewed annually. Identifies water quality CIP and regular housekeeping practices, quantifies pollution removal, provides cost estimates. Determine pollutant load reduction necessary for nondegradation of water bodies. Coordinated with street reconstruction projects, redevelopment, park improvements, and other opportunity areas. Incorporates various TMDLs/WRAPS/UAAs/WRMP items and various BMPs. Has annual or biannual reporting to quantify movement toward goal – can also be used for annual SWPPP and MS4 reporting. 200,000 2022-2023 SW Utility/Grant Funding Stormwater pond evaluation Accessory to Clean Water Strategy. Review of stormwater ponds to determine pollutant removal and develop maintenance schedule. 10,000 2022 SW Utility Critical Facility Flood Risk Review Assess flood exposure for critical facilities and evacuation routes Desktop GIS exercise to identify critical facilities, flood exposure tolerances, and potential impacts TBD 2023 SW Utility _______________________________________________ 1 To be determined City of Edina 2022 Water Resource Management Plan 3-44 Table 3.5 Water Resources Implementation Program Project Name / Location Description Proposed Improvement Cost Estimate ($) Proposed Year Funding Source Flood response preparedness planning Blue sky planning with leadership, emergency responders, planning, and engineering to provide efficient and effective emergency services during and after a flood hazard Development of a substantial damage plan consistent with FEMA regulations and in line with Climate Action Plan item W 4-1. Annual training with key departments and stakeholders 80,000 2023-2024 SW Utility City of Edina 2022 Water Resources Management Plan 45 Table 3.6 Potential Implementation Activities (including Capital Improvements) ID1 WRMP Section2 Project Name/Location Proposed Improvement Nine Mile Creek—North S1 5.3.1.1 Maloney Avenue and Tyler Court (ML_35 and ML_19) Upgrade the downstream 18” pipe to a larger pipe. Create an upstream pipe restriction to limit inflow and use upstream storage. S2 5.3.1.2 Between Leslee Lane and Kaymar Drive (MD_22) Upgrade the outlet pipes to larger pipes. Lower, or at least maintain, the surface overflow to Jeffrey Lane. S3 5.3.1.3 Parkwood Road and Schaefer Road (MD_28, MD_29, and MD_35) Underground storage combined with infiltration (B soils) under Parkwood Road. Lower, or at least maintain, the surface overflows between homes. S4 5.3.1.4 Schaefer Road and View Lane (MD_38) Install a pipe to the east to Bredesen Park. S5 5.3.1.5 Nine Mile Village Townhomes (MD_49) Construct a berm on the west side of Villa Lane. Redirect overflow from Bredesen Park slightly to the south. S6 5.3.1.6 Hawkes Lake and Upstream Surrounding Area (HL_1, HL_11c, HL_11w, HL_49, and HL_12) Increase the capacity of the pumped outlet and the downstream gravity drain. Add storage in the city-owned parcel in MD_15. R1 5.2.1 Colonial Church Parking Lot and Colonial Way (CO_3, CO_4, and CO_10) N/A; to be studied. R2 5.2.1 Nine Mile Creek, Malibu Drive (NMN_60) N/A; to be studied. R3 5.2.1 Blake Road South and South Knoll Drive (MD_24 and MD_25) N/A; to be studied. R4 5.2.1 Nine Mile Creek, south of Londonderry Drive, west of Walnut Drive (EdCrk3) N/A; to be studied. R5 5.2.1 Nine Mile Creek, northwest of Vernon Avenue South and View Lane (EdCrk5) N/A; to be studied. R6 5.2.1 Olinger Boulevard and Sun Road (MD_15) N/A; to be studied. Appendix C Hawkes Drive (HL_2) Construction of overflow swale between homes. Appendix C 5711 and 5717 Grove St (HL_18) Upgrade to larger pipes. Appendix C 5516 and 5520 Dundee Rd (HL_25) Perform detailed field survey. Additional pumping capacity may be required at lift station. Appendix C Fountain Woods Apartments (NMN_90 and NMN_23) Privately owned drainage system. Notify owners of flood potential. City of Edina 2022 Water Resources Management Plan 46 ID1 WRMP Section2 Project Name/Location Proposed Improvement Nine Mile Creek—Central S7 6.3.1.1 Antrim Road and Chapel Drive (NMC_41) Survey homes to confirm flooding problem. Individual flood-proofing. Lower, or at least maintain, the surface overflow between homes. S8 6.3.1.2 Ridgeview Drive (NMC_106 and NMC_107) Survey homes to confirm flooding problem. Install a gravity system, with a backflow preventer, to Nine Mile Creek on the other side of the railroad tracks. Install a pipe to connect to existing storm sewer at Tifton Drive and Ridgeview Drive. S9 6.3.1.3 West 66th Street and Naomi Drive (NMC_71, NMC_74, and NMC_103) Pumped outlet to Normandale Park, with additional storage added in the park, or a gravity system to Nine Mile Creek. Could connect to Nine Mile Creek through NMC_106 if that proposed improvement is constructed. R7 6.2.1 Cherokee Trail (IP_2 and IP_4) N/A; to be studied. R8 6.2.1 Nine Mile Creek, north of the West 70th Street crossing (NMC_1) N/A; to be studied. R9 6.2.1 Valley View Road and Hillside Road (NMC_84, NMC_86, and NMC_120) Street Reconstruction Project for Edina in 2017. R10 6.2.1 TH 62 at Nine Mile Creek crossing (NMC_104) N/A; to be studied. R11 6.2.1 TH 62 at Tracy Avenue (NMC_28, NMC_94, NMC_93, NMC_92, and NMC_87) N/A; to be studied. Appendix C 6005 and 6009 Crescent Dr (manhole 457) Construction of a positive overflow channel. Appendix C Cherokee Trail and Gleason Backyard Depression Area (IP_4) Work with homeowners to evaluate construction of a low level outlet from landlocked depression. Appendix C 5339 West 64th Street (NMC_80) Upgrade to larger pipes at Ridgeview Drive and Valley Lane. Appendix C Valley View Road and Hillside Road (NMC_86 and NMC_120) Upgrade to larger pipe. Lake Cornelia/Lake Edina/Adam’s Hill D1 2022 WRMP Appendix A: 4.3.1.1 2 Southdale Road Neighborhood (LE_34, LE_36, and LE_43) Raise West 68th Street at the intersection with Valley View Road, increase storm sewer capacity to South Cornelia Lake, and/or add underground storage at Cornelia School Park and increase storm sewer capacity. City of Edina 2022 Water Resources Management Plan 47 ID1 WRMP Section2 Project Name/Location Proposed Improvement D2 2022 WRMP Appendix A: 4.3.1.2 2 Southwest Corner of TH 62 and TH 100 (NC_7, NC_8, NC_13, NC_11, NC_12, NC_14, NC_15, NC_16, and NC_20)2 Add targeted storm sewer inlets to maximum capacity without surcharding and/or add underground storage under steets in the upstream part of the neighborhood. R12 7.2.1 Garrison Lane and St. Johns Avenue, northeast (NC_5 and NC_49) N/A; to be studied. R13 7.2.1 Garrison Lane and St. Johns Avenue, southeast (NC_2) N/A; to be studied. R14 7.2.1 South Cornelia, east side (SC_1) N/A; to be studied. R15 7.2.1 Lake Edina (LE_1, LE_10, and LE_7) N/A; to be studied. R16 7.2.1 Heatherton Trail (LE_29) N/A; to be studied. R17 7.2.1 York Avenue South, north of Parklawn Avenue (AHR_15) N/A; to be studied. R18 7.2.1 6124 Wilryan Avenue (NC_46 and NC_45) N/A; to be studied. R19 7.2.1 Hazelton Road and Lynmar Lane (LE_19, LE_24, and LE_21) N/A; to be studied. R20 7.2.1 Dunberry Lane and Oaklawn Avenue (LE_31 and LE_28) N/A; to be studied. Appendix C Swimming Pool Pond (NC_3)/North Lake Cornelia (NC_62) Upgrade pipe and outlet structure. Appendix C Hibiscus Avenue (LE_53, LE_7, and LE_10) Construct positive overflow swale. Appendix C 6312, 6316, 6321, 6329 Tingdale Ave (NC_11) No recommendation at this time. Further analysis required. Appendix C St. Johns/Ashcroft and West 64th Street (NC_40 and NC_26) Installation of additional pipe to drain TH 62 median ditch and prevent upstream flooding. Appendix C Barrie Road and Heritage Drive (NC_86, NC_97, and NC_99_ No recommendation at this time. Reevaluation of TH 62 system will be required. Appendix C York Avenue and West 64th Street (NC_88) Increase pump capacity. Adjust pump on/off elevations. Appendix C TH 62 at France Avenue (NC_132) No recommendation at this time. Reevaluation of TH 62 system will be required. Appendix C Parnell Avenue and Valley View Road (NC_135) No recommendation at this time. Further analysis required. Nine Mile Creek—South S10 8.3.1.1 West 70th Street and West Shore Drive (NMS_38) Increase pipe capacity under West 70th Street. Regrade/lower the surface overflow along West City of Edina 2022 Water Resources Management Plan 48 ID1 WRMP Section2 Project Name/Location Proposed Improvement 70th Street to the west. Add storage in Arnesan Park (LE_54) and install connecting pipe. S11 8.3.1.2 Centennial Lakes (CL_1) Flood proof individual low entries. A floodwall (~3 feet) around the lake at the southern end. R21 8.2.1 City of Edina Building, Metro Boulevard (NMS_51) N/A; to be studied. R22 8.2.1 West 73rd Street, west of TH 100 (NMS_28, NMS_53, NMS_3, NMS_57, NMS_30, NMS_62, NMS_27, NMS_56, NMS_58, and NMS_65) N/A; to be studied. R23 8.2.1 Parklawn Avenue (NMS_77, NMS_70, and NMS_93) N/A; to be studied. R24 8.2.1 Oaklawn Avenue and Gilford Drive (NMS_94 and LE_13) N/A; to be studied. R25 8.2.1 France Avenue South and West 72nd Street (CL_58, CL_56, and CL_57) N/A; to be studied. Appendix C 7001 and 7025 France Avenue (CL_51) No recommendation at this time. Nine Mile South Fork S12 9.3.1.1 McCauley Trail West (AH_6) Increase pump and pipe capacity to Aarowhead Lake. Raise the control elevation upstream in AH_3 to store water upstream. Create additional connected storage in AH_9 and/or AH_13. S13 9.3.1.2 Sally Lane and Valley View Road (NMSB_52, NMSB_69, and NMSB_77) Increase the size of the culvert under Valley View Road. Work with the NMCWD to store water upstream west of TH 169. R26 9.2.1 Between Gleason Road and Mark Terrace Circle (NMSB_27) N/A; to be studied. R27 9.2.1 7122 Tupa Drive, 7117 Gleason Road, and 7116 Gleason Road (NMSB_13 and NMSB_30) N/A; to be studied. Appendix C 6309 Post Lane (AH_31) Construction of two control structures to restrict flow through the existing storm sewer system. Appendix C Braemar Golf Course (NMSB_62) No recommendation at this time. Further analysis required. Appendix C 7009 and 7013 Sally Lane Backyard Depression Area (NMSB_70) None. Analyzed in STS-406. City of Edina 2022 Water Resources Management Plan 49 ID1 WRMP Section2 Project Name/Location Proposed Improvement Southwest Ponds S14 10.3.1.1 Gleason Road and Bonnie Brae Drive (SWP_24) Survey homes to confirm flooding problem. Individual flood-proofing of potentially impacted homes. Create additional storage in the city-owned parcels south of Bonnie Brae Drive. R28 10.2.1 Kemrich Drive and Shannon Drive (SWP_53 and SWP_66) N/A; to be studied. R29 10.2.1 Dewey Hill Road, west of Cahill Road (SWP_21, SWP_48, SWP_5, SWP_34, SWP_35, SWP_15, SWP_14, and SWP_4) N/A; to be studied. Appendix C 7411 Coventry Way (SWP_14) Installation of flap gate. Appendix C 7317 Cahill Road (SWP_46) No recommendation at this time. Further analysis required. Appendix C 7709 Stonewood Court (NM494_4) Upgrade to larger pipes. Northeast Minnehaha Creek D3 2022 WRMP Appendix A: 9.3.1.1 2 Halifax Avenue South (MHN_84, MHN_3, MHN_56, MHN_89, MHN_55, MHN_61, MHN_62, MHN_63, MHN_87, MHN_88, MHN_90, and MHN_2) and Indianola Avenue (MHN_4, MHN_5, MHN_42, and MHN_72) Regrade portions of Indianola Avenue, add underground strorage below church parking lot in southeast of neighborhood, and add storm sewer inlets and increase storm sewer capacity. D4 2022 WRMP Appendix A: 9.3.1.2 2 Weber Park (MS_26, MS_25, MS_41, MS_32, MS_44, MS_24, MS_15, MS_53, MS_2, MS_38, MS_40, MS_54, MS_31, MS_33, MS_39a, and MS_39b)2 Project to address flooding issues started in 2022. S15 12.3.1.1 Indianola Avenue South of West 50th Street (MHN_72) Underground storage and infiltration (A soils) with sufficient inlet capacity. Enlarge downstream pipes to Minnehaha Creek, while not creating downstream impacts. S16 12.3.1.4 Edinbrook Lane and Westbrook Lane (MHN_79) Reroute flow from MHN_78. Improve, and possibly lower, the surface overflow to the north. Purchase the homes to create storage and infiltration (B soils). S17 12.3.1.5 North of Morningside Road between Lynn Avenue and Crocker Avenue (MS_22) Survey homes to confirm flooding problem. Add an inlet in the backyard area and connect to existing storm sewer under Crocker Avenue or Lynn Avenue. City of Edina 2022 Water Resources Management Plan 50 ID1 WRMP Section2 Project Name/Location Proposed Improvement S18 12.3.1.6 Branson Street between West 44th Street and Morningside Road (MS_3, MS_48, and MS_7) Add inlets and connecting pipes in the backyard depression areas. Increase pipe sizes under Morningside Road. Add storage in MS_7. Add underground storage under Branson Street and Oakdale Avenue. R30 12.2.1 West 50th Street and Arden Avenue (MHN_6, MHN_7, MHN_72, MHN_53, and MHN_54) N/A; to be studied. R31 12.2.1 Country Club Road and Casco Avenue (MHN_16) N/A; to be studied. R32 12.2.1 Minnehaha Creek, southeast of Wooddale Avenue and West 50th Street (MHC_3 and MHN_27) N/A; to be studied. R33 12.2.1 Minnehaha Creek, southwest of TH 100 and West 44th Street (MHC_1) N/A; to be studied. R34 12.2.1 Minnehaha Creek, southeast of TH 100 and West 44th Street (MHC_2) N/A; to be studied. R35 12.2.1 Scott Terrace and West 42nd Street (MS_52) May be addressed with the Weber Park proposed improvements. R36 12.2.1 Townes Road and West 48th Street (White Oaks) White Oaks Area, studied in 2013-2014, STS-406. R37 12.2.1 TH 100 near Harvey Lake (H100_20 and H100_22) N/A; to be studied. R38 12.2.1 Bridge Street and Moorland Avenue and Edina Boulevard (MHN_25, MHN_52, MHN_51, MHN_19, MHN_24, MHN_23, and MHN_22) N/A; to be studied. Appendix C 4000 West 42nd Street and 4100, 4104, and 4108 France Ave (MS_40) Implement recommendations of the 2006 Weber Park Pond Feasibility Study. Appendix C 4308 France Ave (MS_17) Work with homeowners to evaluate installation of gravity system to drain backyard depression area. Appendix C Arden Avenue (MHN_14) No recommendations at this time. Southeast Minnehaha Creek D5 2022 WRMP Appendix A: 10.3.1.2 2 Concord and West 58th Street (MHS_59, MHS_26, MHS_58, MHS_42, MHS_53, and MHS_17) Add storm sewer capacity aong West 58th Street, add surface storage at South View School, add underground street storage in the East Golf Terrace neighborhood and the Wooddale Church parking lot, and raise the overflow through private property on Woodland Road West. City of Edina 2022 Water Resources Management Plan 51 ID1 WRMP Section2 Project Name/Location Proposed Improvement S19 13.3.1.1 Tower Street (MHS_75, MHS_86, and MHS_76), between Fairfax Avenue and Wooddale Avenue (MHS_16), and North of 56th Street (MHS_83) Add inlets in these areas and increase downstream capacity to Minnehaha Creek. .Add parallel pipe network from West 56th Street and Wooddale Avenue to West 56th Street and Kellogg Avenue. Underground storage and infiltration under side streets. R39 13.2.1 Minnehaha Creek, north of Pamela Park (MHC_4, MHS_8, and MHS_9) N/A; to be studied. R40 13.2.1 Woodcrest Drive and Backyard Pond (MHC_4, MHS_10, MHS_12, and MHS_41) N/A; to be studied. R41 13.2.1 South end of Pamela Park, West 62nd Street (LP_26, LP_17, and LP_22) N/A; to be studied. R42 13.2.1 East side of Pamela Park, Halifax Avenue South (LP_14, LP_10, LP_9, and LP_7) N/A; to be studied. R43 13.2.1 West 61st Street, between Xerxes Avenue South and York Avenue South (MPLS_130) N/A; to be studied. Appendix C 6213 Ewing Ave (LP_15) Upgrade to larger pipes. Appendix C 3600 West Fuller Street (MHS_4) Installation of a catch basin in backyard depression and storm sewer along Beard Avenue. Appendix C 5605, 5609, 5613, 5617, 5621, 5625, and 5629 South Beard Avenue (MHS_79) Upgrade to larger pipes. Install catch basin in alley. Appendix C 5837, 5833, 5829, and 5825 South Chowen Ave (LP_24) Installation of a catch basin in backyard depression area. Appendix C Chowen Avenue and West 60th Street (LP_27) Perform detailed survey/verification of storm sewer to verify pipe sizes, inverts, and low point of entry. Appendix C 5912, 5916, 5920, 5924, 5928 Ashcroft Avenue and 5925 Concord Avenue (MHS_51) Pumped or gravity outlet of 3 cfs capacity. Appendix C 5840 and 5836 Ashcroft Avenue (MHS_89) Work with homeowners to evaluate installation of catch basin from backyard depression. Appendix C 5609 and 5605 Dalrymple Road (MHS_24), and 5610 and 5612 St. Andrews Avenue (MHS_66) Construct surface overflow swale (1) or upgrade to larger pipes (2). Appendix C 5701 Dale Avenue (ML_12) Upgrade to larger pipes. Appendix C 5213 and 5217 Richwood Drive (ML_7) Perform detailed field survey of wetland storage. Further analysis required. City of Edina 2022 Water Resources Management Plan 52 ID1 WRMP Section2 Project Name/Location Proposed Improvement Northwest Minnehaha Creek S20 14.3.1.1 Blake Road South and Spruce Road (HO_4) Increase downstream pipe capacity: (1) increase pipe connecting HO_8 and HO_19, or (2) add additional outlet to the Interlachen Golf Course from the wet pond (HO_8) or from the existing storm sewer under Spruce Road. Add depressions/storage in the golf course to offset additional water. R44 14.2.1 Annaway Drive and Interlachen Country Club (EI_3, EI_25, EI_25a, and EI_34) N/A; to be studied. R45 14.2.1 Annaway Drive, Merilane Avenue, and Mait Lane (EI_1, EI_2, EI_4, and EI_5) N/A; to be studied. Appendix C Interlachen Landlocked Area Construct/raise embankment between landlocked wetland and Meadowbrook Golf Course. Develop management plan for pumped outlet. (1) In the ID column: D = detailed analysis conducted for flood-prone area (pink) In the ID column, S = screening level analysis conducted for flood-prone area (yellow) In the ID column, R = registered flood-prone area: identified as a flood-prone area but not studied further for this WRMP (blue) (2) Study areas updated as part of this WRMP update are included in Appnedix A to this WRMP; study areas not updated as part of this WRMP amendment reference sections of the 2018 WRMP. North B ranchNineMileCreek SouthBranc h N i ne Mile C r eekMud Lake Lake Cornelia Lake Edina Mirror Lake Arrowhead Lake Indianhead Lake Highlands Lake Melody Lake Lake Pamela Harvey Lake Hawkes Lake Centennial Lakes M in ne h a h a C r ee k£¤169 100 62 100 456717 456731 4567158 456731 Braemar Park (Courtney Fields) Bredesen Park Rosland Park Pamela Park Lewis Park Highlands Park Walnut Ridge Park T. Lea Todd Park Open Space 1 Heights Park Garden Park Heights Park Lincoln Drive Floodplain Van Valkenburg Park Fred Richards Golf Course Arden Park Krahl Hill Creek Valley School Park Lake Edina Park Normandale Park Weber Field Park Arneson Acres Park Countryside Park Weber Woods Centennial Lakes Park Open Space 2 Open Space 3 Centennial Lakes Park Alden Park Utley Park Open Space 2 Moore Property Pamela Park York Park Yorktown Park Centennial Lakes Park Cornelia School Park Wooddale Park Strachauer Park Garden Park Open Space 5 Fox Meadow Park Kojetin Park Edinborough Park Arden Park Garden Park McGuire Park Fox Meadow Park Birchcrest Park Sherwood Park Garden Park Addition Melody Lake Park Chowen Park Open Space 2 Centennial Lakes Park St. John's Park Tingdale Park York Park Browndale Park York Park Frank Tupa Park Grandview Square Open Space 6 MinneapolisMinneapolis HopkinsHopkins Eden PrairieEden Prairie RichfieldRichfield MinnetonkaMinnetonka BloomingtonBloomington Saint Louis ParkSaint Louis Park Barr Footer: ArcGIS 10.6, 2018-05-22 11:14 File: I:\Client\Edina\Projects\CRWMP_Update_2017\Maps\Reports\Figures_CityReviewDraft\Fig_15_1_City_Owned_Property.mxd User: smsCITY-OWNED PROPERTYWater ResourcesManagement PlanCity of Edina, Minnesota FIGURE 3.4 0 3,000 Feet !;N City-Owned Property Park/Recreational Area Streets and Highways Creek/Stream Lake/Pond City of Edina Boundary Imagery Source: MnGeo, 2016 City of Edina 2022 Water Resources Management Plan 4-1 4.0 Policies for Water Resources Management The following sections outline the policies for the three core services provided through the water resources program: flood risk and stormwater runoff management, clean water services, and natural resources restoration and protection. 4.1 Flood Risk and Stormwater Runoff Management The City adopts the following general flood risk and stormwater runoff management policies (Sections 4.1.1 through 4.1.5 provide specific policies and standards): 1. The primary goal for the City’s flood risk reduction effort is to improve public safety and reduce the exposure of private principal structures to flooding a. We improve public safety by reducing the potential hazards people may encounter associated with floods. b. We reduce principal structure exposure by keeping infrastructure systems well- maintained, retrofitting for new capacity, or rebuilding for new capacity when infrastructure is replaced at the end of its lifecycle. c. We regulate development and redevelopment to ensure the actions proposed at the time of development considers flood risk and does not adversely impact others. 2. The development of new infrastructure and programs should include consideration to reduce flood risk for principal structures. 3. The City adopts No Adverse Impact (NAI) principles to promote responsible development measures for private development and public design standards. 4. The City will maintain a map with flood exposure information and make it available to the public. We will incorporate changes to reflect our best understanding of the hydraulics, hydrology, stormwater infrastructure and natural conveyance systems, topography, and land use and development. A floodplain is any land area susceptible to being inundated by floodwaters from any source. More specifically, the Minnesota Floodplain Management Act of 1969 defines the floodplain as that area adjoining a watercourse which is subject to inundation by a flood of 1-percent-annual-chance. City of Edina 2022 Water Resources Management Plan 4-2 5. The City will engage the community in decision- making and encourage active participation in addressing water resources problems. 6. The City will determine the applicable 1-percent- annual-chance flood elevation(s) by using the best information available at the time. For regional flood areas, the applicable 1-percent-annual-chance flood elevation will be based on FEMA’s effective Flood Insurance Rate Map (FIRM) and Flood Insurance Study (FIS), flood management elevations adopted by the respective watershed district, or hydrologic and hydraulic model(s) developed by the respective watershed district, whichever is higher. For local flood areas, the applicable 1-percent-annual-chance flood elevation will be based on the City’s 2022 WRMP or subsequent XPSWMM model updates. The applicable 1-percent-annual-chance flood elevations are subject to change due to periodic model updates that incorporate additional or more accurate information and may differ from the flood elevations identified in this plan. 7. The local 1-percent-annual-chance flood elevation will be based on a 24-hour duration precipitation event unless an event of another duration is determined to result in a higher flood elevation. The 1-percent-annual-chance, 10-day snowmelt event will be used for landlocked basins. 8. The rules and requirements of the Nine Mile Creek Watershed District and Minnehaha Creek Watershed District are applicable and can be found on the respective watershed district website. 9. Requests for city-coordinated pumping to lower water levels during wet periods will be evaluated A basin is considered landlocked if it doesn’t have an outlet in the 10- percent-annual-chance event. If it outlets in the 10-percent-annual- chance event it is not considered landlocked. Landlocked basins may be subject to prolonged higher- than-normal water levels during periods of high precipitation For a regional flood area, the applicable 1-percent-annual-chance flood elevation (also called the Special Flood Hazard Area) is based on the higher of FEMA’s effective Flood Insurance Rate Map (FIRM) and Flood Insurance Study (FIS), flood management elevations adopted by the respective watershed district, or hydrologic and hydraulic model(s) developed by the respective watershed district. Regional tailwater refers to the local flood area which is controlled by the regional flood area. A local flood area is the area below the modeled 1-percent-annual- chance flood elevation for areas outside of the regional flood area. These areas are described in detail in Appendix A of this plan. Generally, regional flood conditions tend to persist longer than local flood conditions. City of Edina 2022 Water Resources Management Plan 4-3 based on the health, safety, and welfare of residents. Pumping will only be considered when flooding threatens principal structures. (Resolution No. 2021- 22: City’s Policy of Prioritizing Flooding Issues, adopted by City Council on February 17, 2021.) 4.1.1 Minimum Principal Structure Elevations To prevent flooding of principal (to include both residential and non-residential commercial industrial or institutional) structures, the City will implement the following standards in addition to the Floodplain Overlay Districts ordinance (City Code Chapter 36, Article 10). 1. New principal structures, additions, and other permanent fixtures including heating and air conditioning ventilation systems must have a lowest floor elevation at least two feet above the applicable 1-percent-annual-chance flood elevation if one or more of the following conditions exist: a. The structure is partially or wholly within the subwatershed of a regional flood area; b. The structure is partially or wholly within the subwatershed of a local flood area subject to regional tailwater effects (the regional tailwater elevation shall apply); c. The City Engineer determines the structure to be at significant risk due to seepage. 2. New principal structures that are not subject to Section 4.1.1 (1) and are partially or wholly within the subwatershed of a ponding basin must have a lowest floor elevation at least two feet above the ponding basin outlet elevation and must satisfy applicable watershed district requirements (see Section 4.1.1 (5)). 3. New principal structures, additions, and other permanent fixtures including heating and air conditioning that are partially or wholly within the subwatershed of a landlocked basin must have a lowest floor elevation that is at least two feet above the water level resulting from two concurrent Ponding basin describes an area used for long term or extended flood storage, for example detention basins/ponds, retention basins/ponds, infiltration basins, natural waterbodies, or other areas that provide flood storage either by design or naturally. Temporary storage area describes an area used for short term, temporary flood storage, for example infiltration assets, backyard depression areas, streets, parking lots, or other areas that provide temporary short term flood storage either by design or naturally. Stormwater conveyances may be natural systems or engineered facilities with temporary flow or baseflow. Flow path is temporary and may be planned or unplanned overland flow. Lowest floor elevation is the floor elevation of the lowest enclosed area (including basement or crawl space). Lowest opening elevation is the lowest opening of a structure, for example garage door, windowsill, top of window well elevation, or walkout elevation. City of Edina 2022 Water Resources Management Plan 4-4 1 or 10-percent-annual chance, 24-hour rainfall events or two feet above the 1 or 10-percent- annual chance 10-day snowmelt, whichever is higher. In either case, the starting elevation of the basin/waterbody prior to the runoff event should be established by one of the following: a. Existing Ordinary High Water Level established by the MnDNR; b. Ordinary High Water Level established by a licensed surveyor in accordance with the MnDNR’s ‘Guidelines for Ordinary High Water Level (OHWL) Determinations’ c. Annual water balance calculation approved by the City; d. Local observation well records, as approved by the City; or e. Mottled soil. Note: The landlocked basin 1-percent-annual-chance and/or 10-percent-annual-chance flood elevation may be lowered by creating new storage, excavating an overflow swale, limiting flows into the basin, or installing an outlet pipe at an overflow point. 4. New principal structures, additions, and other permanent fixtures including heating and air conditioning ventilation systems must have a lowest opening elevation at least two feet above the applicable 1 percent-annual-chance flood elevation if one or more of the following conditions exist: a. The structure is partially or wholly within the subwatershed of a local flood area; b. The structure is partially or wholly within the subwatershed of a local flood area subject to regional tailwater effects (the local flood area elevation shall apply); c. The structure is partially or wholly within the subwatershed of a temporary storage area, an emergency overflow, flow path, or stormwater conveyance; the 1-percent-annual- chance flood elevation of the temporary storage area, emergency overflow, flow path, or stormwater conveyance at the point where the temporary storage area, emergency overflow, flow path, or stormwater conveyance is closest to the structure applies. 5. Principal structure modifications that require a watershed district permit must conform to their minimum elevation standards. 6. Site-specific Standards for Principal Structure Elevations: The basis for the site-specific standard is to allow an alternative path for risk reduction that doesn’t require 2 feet of freeboard (but not less than zero feet of freeboard) as required in Section 4.1.1 and/or below grade parking garages design standards as required in Section 4.1.3. This may include strategies that reduce flood vulnerability instead of or in addition to reducing flood exposure. The outcome should still be overall reduction in risk. Elevation standards for the lowest floor elevation or lowest opening elevation reduce flood exposure by providing two feet of City of Edina 2022 Water Resources Management Plan 4-5 freeboard between the structure and the floodplain. Site-specific standards for lowest floor elevation or lowest opening elevation less than the two feet of freeboard required by Section 4.1.1 and/or lesser below-grade parking garages design standards as required by Section 4.1.3 may be allowed given all the following conditions are met: a. The project is not partially or wholly within the subwatershed of a regional flood area. b. The project is not partially or wholly within the subwatershed of a local flood area subject to significant regional tailwater effects. c. The project results in a net reduction in vulnerability from existing conditions. For example, additional construction methods and precautions are proposed that reduce the potential for flood damage to the structure. d. The project owner demonstrates that meeting the lowest floor elevation or lowest opening elevation requirements as described in Section 4.1.1 presents practical difficulties for complying. e. The project does not adversely impact the flood exposure of others. f. The project design is approved by the City Engineer. g. The project design meets the applicable rules of the respective watershed district. 4.1.2 Structure Setbacks 1. All principal and accessory structures shall maintain setbacks described in City Code Sec. 36-1268. 2. The Minnesota Department of Natural Resources (MnDNR) determines OHWLs. In the absence of a MnDNR defined OHWL, the following elevations shall be used in reference to setbacks; a. The city-established outlet elevation for the lake, pond, or wetland. b. The elevation delineating the highest water level that has been maintained for a sufficient period to leave evidence upon the landscape, commonly the point where the natural vegetation changes from predominantly aquatic to predominantly terrestrial, as established by a professional land surveyor. c. The top of the bank of the channel for Minnehaha Creek and Nine Mile Creek. OHWL and outlet elevation can be access through the City’s interactive web maps,. OHWL are listed in Table 2.4. City of Edina 2022 Water Resources Management Plan 4-6 4.1.3 Below-Grade Garages and Parking To prevent flooding of below-grade garages and parking facilities, the City will implement the following design standards: 1. Construction of below-grade parking garages in residential structures within local flood and regional flood areas is prohibited. 2. Construction of below-grade parking garages in mixed-use and non-residential structures within local flood and regional flood areas is permitted, provided the structure (including the parking garage) is flood proofed to two feet above the applicable 1-percent-annual-chance flood elevation in accordance with the following design standards: a. Together with associated utility and sanitary facilities, the structure must be designed so that below two feet above the 1-percent-annual- chance flood elevation the structure is watertight with walls substantially impermeable to the passage of water and with structural components having the capability of resisting hydrostatic and hydrodynamic loads and effects of buoyancy. b. A Floodproofing Certificate and Inspection and Maintenance Plan must be provided by a registered professional engineer or architect. c. A floodproofing design that entails human intervention, such as the installation of flood gates or flood shields, will require a Flood Emergency Operation Plan. 4.1.4 Stormwater Infrastructure Design Standards Stormwater infrastructure provides drainage, flood risk management, management of pollution, and protection of natural resources. The City adopts the following design standards for all new stormwater infrastructure assets: 1. All ponding basins, temporary storage areas, and basin outlet pipes should be designed to collectively detain and/or convey the flows from the critical 1- percent-annual-chance, 24-hour rainfall or 10-day snowmelt event in landlocked basins. Ponding For further guidance including requirements and certification of below-grade parking garages, review the following; •FEMA’s Technical Bulletin 6- 93, “Below-Grade Parking Requirements for Buildings Located in Special Flood Hazard Areas” •FEMA’s Technical Bulletin 3- 93, “Non-Residential Floodproofing – Requirements and Certification”. FEMA establishes minimum floodplain management requirements and both allows and encourages local agencies to adopt higher standards to increase flood resiliency, especially when local agencies have access to information or knowledge of conditions that require higher standards than the minimum criteria. City of Edina 2022 Water Resources Management Plan 4-7 basins should be designed to contain the flows from the 1-percent-annual-chance storm without overtopping. 2. The City will place a high priority on safely storing and conveying water for the critical storm as stormwater assets are added, upgraded, renewed, or replaced. 3. The City will require new stormwater conveyance systems to provide a 10-percent-annual-chance (10-year) level of service. Existing stormwater conveyance systems that currently do not provide a 10-percent-annual-chance level of service will be modified, as opportunities arise and as feasible. 4. Where practical and physically possible, regional ponding basins and temporary storage areas, as opposed to individual onsite ponding basins and temporary storage areas, are preferred to reduce flooding, to control discharge rates, and to provide necessary storage volumes. 5. All ponding basins and temporary storage areas should have planned, stabilized emergency overflow conveyance paths or structures to minimize impacts resulting from extreme storms or plugged outlet conditions. 6. Each ponding basin and temporary storage area should have an access point for maintenance purposes. 7. The City will allow outlets from landlocked basins only when such outlets are at or above the 1- percent-annual-chance floodplain, are consistent with state and federal regulations, and the downstream principal structure, riparian, and habitat impacts of such outlets have been analyzed and no detrimental impacts result. An exception to this policy is the City will allow an outlet below the 1-percent-annual-chance floodplain elevation in situations where public safety is threatened and/or inundation of principal structures would be likely if the outlet is at a higher elevation. 4.2 Clean Water Services The streams, ponds, lakes, and wetlands in the City of Edina are an important community resource. These resources supply aesthetic and recreational benefits, in addition to providing wildlife habitat and refuge. The City recognizes the need to assure adequate water quality in the water bodies within the city and will take steps to protect and improve these resources. The City of Edina will manage the City’s water resources so that the beneficial uses of lakes, streams, ponds, and wetlands remain available to the community. Such beneficial uses may include aesthetic appreciation, wildlife habitat protection, nature observation, and recreational activities. The City adopts the following general policies addressing clean water services: 1. The City will review, permit, and enforce standards for construction activities to prevent pollution. The City has an inventory of public and private stormwater infrastructure assets which can be found online via the City’s interactive web maps, City of Edina 2022 Water Resources Management Plan 4-8 a. The City will implement stormwater management requirements for single and double dwelling units as described in City Code, chapter 10 and for site plans associated with commercial, multifamily, and multiuse as described in City Code, chapter 36. b. The City requires erosion and sediment controls and submittal of erosion and sediment control plans for proposed construction activities. c. The City will direct that entities proposing construction projects that disturb more than 1 acre of land will need to apply for coverage under the MPCA’s General NPDES Construction Stormwater Permit. 2. The City will work to heighten community awareness of water quality management through education and training to reduce pollution sources including, but not limited to, chloride. 3. The City will engage the community in decision-making and encourage active participation in addressing water resources problems. 4. The City will manage its natural systems so that the beneficial uses of streams, natural wetlands, natural ponds, and lakes remain available to the community. 5. The City will conduct targeted street sweeping and encourage other forms of upstream pollutant reduction in areas closer to the source of such pollutants. 6. The City will encourage use of regional stormwater infrastructure, as opposed to individual on-site stormwater infrastructure, to reduce flooding, control discharge rates, and provide for water quality management. 7. The rules and requirements of the Nine Mile Creek Watershed District and Minnehaha Creek Watershed District are applicable and can be found on the respective watershed district website. The City will work with the MPCA, Nine Mile Creek Watershed District, and Minnehaha Creek Watershed District to implement the recommendations and/or requirements of existing or future WRAPS and TMDL(s) throughout the city. 8. The City will work with Nine Mile Creek Watershed District, Minnehaha Creek Watershed District, and lake associations to study the health of waterbodies and plan activities for protecting and improving waterbodies. 9. The City will waive permit fees for collaborative projects with the Minnehaha Creek Watershed District, Nine Mile Creek Watershed District, and other cities where the project purpose aligns align with clean water or flood risk reduction goals and the watershed district is paying 50% or more of the costs of the project. 10. The City will target improvements to address pollutant loading from watershed sources, and partner with watershed districts and lake associations to address internal phosphorus loads. City of Edina 2022 Water Resources Management Plan 4-9 11. The City will promote and protect a diverse, native population of aquatic vegetation that contributes to a balanced ecosystem through partnerships with watershed districts and lake associations. 12. The City will conduct management of invasive aquatic species where the management strategy has a measurable clean water benefit. 13. The City will encourage the use of low-impact site design for development and redevelopment within the city. 14. The City will, where feasible, apply low-impact site design principles for City-sponsored improvement projects. 4.3 Wetlands The City of Edina’s goal is to achieve no net loss of wetlands, including acreage, functions, and values. Though it may be tempting to modify wetlands to make them resemble their state during periods of drought (when most of the City was developed) (see Section 3.3), wetlands have adapted to natural cycles of wet and drought and they should not be prevented from experiencing continued adaptation in the future. These are important factors in natural wetland hydrology that maintain the functions and values that wetlands provide. Where practical, opportunities to improve the functions, values, biological diversity, and acreage of existing wetlands should be sought. The City adopts the following policies relating to natural wetlands within the city: 1. The City discourages wetland alteration. Unavoidable wetland alterations must be mitigated in conformance with the Wetland Conservation Act (WCA) requirements and the requirements of the Nine Mile Creek Watershed District or Minnehaha Creek Watershed District, and must be guided by the following principles, in descending order: avoid the impact, minimize the impact, rectify the impact, reduce or eliminate the impact over time, and compensate for the impact. 2. The Nine Mile Creek Watershed District and the Minnehaha Creek Watershed District are the local government units (LGU) responsible for administering the Wetland Conservation Act in the City of Edina. The City will work in conjunction with the Nine Mile Creek Watershed District and the Minnehaha Creek Watershed District on issues pertaining to wetland alterations within the city boundary. 3. The City will support watershed districts and other agencies in their efforts to maintain and periodically update wetland inventory data and management classifications. 4. The City will incorporate wetland data into its inventory as wetland delineations are performed either as part of a comprehensive inventory or as the result of standalone projects. City of Edina 2022 Water Resources Management Plan 4-10 5. The City will partner with watershed districts to restore previously existing wetlands and enhance existing wetlands. 6. The City will involve the appropriate regulatory agencies (e.g., MPCA, U.S. Army Corps of Engineers, and the MnDNR) in the planning of any proposed water quality or flood control facilities identified in this plan that may be located within a wetland. 7. The City will provide buffer zones of native vegetation, where feasible, around ponds and wetlands to provide habitat. The City will work with the Nine Mile Creek Watershed District and Minnehaha Creek Watershed District to educate the public regarding wetland protection and the importance of creating and maintaining vegetative buffers. Land use and property ownership may limit the ability to provide buffer zones. 8. Constructed stormwater ponds will be managed as stormwater assets, not naturally occurring wetlands. 4.4 Natural Resources Restoration and Protection The City’s goals are to protect and enhance fish and wildlife habitat, soils and native landscapes. To accomplish this objective, the City adopts the following policies: 1. Cooperate with other units of government to complete habitat and recreation corridor connections (trails and greenways). 2. Maintain, enhance, or provide new habitat as part of wetland modification, stormwater facility construction, Parks redevelopment, or other appropriate projects. 3. Encourage alternative landscape designs that increase beneficial habitat, wildlife and clean water ; promote infiltration and vegetative water use, decrease detrimental wildlife uses (such as beaver dams, goose overabundance), protect water control facilities, stabilize soils with deep roots near the shoreline, stabilize soils for water quality or recreational opportunity ,and minimize irrigation demand and chemical control. 4.5 Groundwater The City’s goal is to protect the quality and quantity of groundwater resources. The City adopts the following groundwater policies: 1. The City will encourage groundwater recharge and protect recharge areas from potential sources of contamination. The City will provide increased greenspace, native vegetation, and pond “dead” storage wherever possible and appropriate to allow for the infiltration of stormwater runoff and promote groundwater recharge. City of Edina 2022 Water Resources Management Plan 4-11 2.The City will encourage use of grassed waterways to maximize infiltration where not detrimental to groundwater supplies. 3.The City will implement groundwater quality and quantity protection measures outlined in the City’s Wellhead Protection Plan, Part II (2013) or the next generation of this plan.. 4.The City will address unused unsealed private wells through the permitting process. 5.The City will review and adopt as necessary a water sustainability ordinance that is protective of groundwater quality and quantity. 6.The City will investigate, and implement where feasible, water reuse projects. 7.The City will promote awareness of groundwater resource issues through public education and information programs. 4.6 Appeal Process Appeals in which it is alleged that there is an error in any order, requirement, decision, or determination made by an administrative officer in interpretation or enforcement shall be pursued consistent with City Code chapter 36. The Planning Commission shall serve as the board of appeals and adjustments. 4.7 Water Resources Management Agreements Water resource management-related agreements that the City has entered with other organizations can be found online through the “Edina Docs” Water Resources Library: http://edinadocs.edinamn.gov/ •City of Bloomington: for the area of the Border Basin •City of Eden Prairie: for the area along Washington Avenue •City of Richfield: for the outlet from Adam’s Hill Pond •City of Hopkins: for the area east of Blake Road and along TH 169 •City of St Louis Park: for Meadowbrook Golf Course and Morningside area •Minnehaha Creek Watershed District: for Arden Park, Pamela Park Water Quality Improvements, and the 2014 Memorandum of Understanding outlining spheres of collaboration •Nine Mile Creek Watershed District: for the establishment of a framework for collaborative pursuit of water resource improvement projects (2019), Edina/Nine Mile Creek Streambank Stabilization project (2015, 2019), Pentagon Park assessment and planning (in cooperation with the City of Bloomington), Rosland Park BMP Project (2020), 2019-2020 alum treatment, and Lynmar Basin Stormwater Retrofit Project (2022). City of Edina 2022 Water Resources Management Plan 5.0 References Association of State Floodplain Managers (ASFPM). 2016 conference. Critical Facilities Assessment for Southeastern Connecticut: Strategies for Flood Resilience. Barr Engineering Company, 1999a. Glen Lake Use Attainability Analysis. Barr Engineering Company, 1999b. Round Lake Use Attainability Analysis. Barr Engineering Company, 2001. Bloomington Use Attainability Analysis. Prepared for Nine Mile Creek Watershed District. Barr Engineering Company, 2004. Draft Mirror Lake Use Attainability Analysis. Barr Engineering Company, 2006. Draft Lake Cornelia Use Attainability Analysis. Barr Engineering Company, 2016. City of Edina Imperviousness Assumptions for Stormwater Modeling. Prepared for City of Edina. City of Edina, 2009. Edina Comprehensive Plan. Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe, 1979. Classification of Wetlands and Deepwater Habitats of the United States. U.S. Fish and Wildlife Service, FWS/OBS-79/31. Federal Emergency Management Agency (FEMA), 2016. Flood Insurance Study for Hennepin County, MN All Jurisdictions. Hennepin Conservation District, 2003. Functional Assessment of Wetlands, Minnehaha Creek Watershed District. International Panel on Climate Change (IPCC). 2014. Assessment Report 5 (AR5). International Panel on Climate Change (IPCC). 2022. Assessment Report 6 (AR6). Minnehaha Creek Watershed District, 2007. Minnehaha Creek Watershed District Comprehensive Water Resources Management Plan. Minnehaha Creek Watershed District, 2018. Minnehaha Creek Watershed District Watershed Management Plan. Minnesota Department of Natural Resources, 1999. Minnesota Routine Assessment Method for Evaluating Wetland Functions (MnRAM). Minnesota Pollution Control Agency (MPCA), 2000. Protecting Water Quality in Urban Areas, March 2000. Minnesota Pollution Control Agency (MPCA), 2005. Minnesota Stormwater Manual. Minnesota Pollution Control Agency (MPCA), 2010. Nine Mile Creek Biological Stressor Identification. Prepared by Barr Engineering Company. City of Edina 2022 Water Resources Management Plan Minnesota Pollution Control Agency (MPCA), 2013. Minnehaha Creek E. coli Bacteria Total Maximum Daily Load. Prepared by Tetra Tech, Inc. Minnesota Pollution Control Agency (MPCA), 2015. South Metro Mississippi River Total Suspended Solids Total Maximum Daily Load Study. Prepared by MPCA and LimnoTech. Minnesota Pollution Control Agency (MPCA), 2016. Twin Cities Metropolitan Area Chloride Total Maximum Daily Load Study. Prepared by MPCA and LimnoTech. Minnesota Pollution Control Agency (MPCA), February 2020. Lower Minnesota River Watershed Total Maximum Daily Load Study Part II—Northern Watersheds: Riley-Purgatory-Bluff Creek and Nine Mile Creek Watersheds. Prepared by MPCA and Barr Engineering Co. Minnesota Pollution Control Agency (MPCA), April 2021. Lake Pepin and Mississippi River Eutrophication Total Maximum Daily Load Study. Prepared by MPCA and LimnoTech. Mitsch, W.J. and J.G. Gosselink, 2000. Wetlands. Nine Mile Creek Watershed District, 2017. Nine Mile Creek Watershed District Water Management Plan. Nine Mile Creek Watershed District, July 2019. Lake Cornelia and Lake Edina Water Quality Study - Use Attainability Analyses for Lake Cornelia (updated from 2010) and Lake Edina (first version). Prepared by Barr Engineering Co. Nine Mile Creek Watershed District, June 2020. Lake Cornelia and Lake Edina Water Quality Improvement Project – Feasibility Study/Preliminary Engineering Report. Prepared by Barr Engineering Co. National Oceanic and Atmospheric Administration, 2013. Atlas 14 Volume 8 - Precipitation-Frequency Atlas of the United States, Midwestern States. Schwab, G.O., D. Fangmeier, W. Elliot, and R. Frevert, 1993. Soil and Water Conservation Engineering. Shaw, S.P., and C.G. Fredine, 1959. Wetlands of the United States: Their Extent and Their Value to Waterfowl and Other Wildlife. U.S. Fish and Wildlife Service. Circular 39. Stack LJ, Simpson MH, Gruber J, Moore TL, Yetka L, Eberhart L, Gulliver J, Smith J, Mamayek T, Anderson M, Rhoades J. 2014. Long-term climate information and forecasts supporting stakeholder-driven adaptation decisions for urban water resources: Response to climate change and population growth. Final project report: Sectoral Applications Research Program FY2011, Climate Program Office, National Oceanic and Atmospheric Administration State of Minnesota, Stormwater Advisory Group, 1997. Stormwater and Wetlands: Planning and Evaluation Guidelines for Addressing Potential Impacts of Urban Stormwater and Snow Melt Runoff on Wetlands. June 1997. U.S. Army Corps of Engineers. Wetlands Delineation Manual. 1987. U.S. Department of Commerce, Weather Bureau, 1961. “Technical Paper No. 40. Rainfall Frequency Atlas of the United States.” U.S. Environmental Protection Agency, 1988. Stormwater Management Model, Version 4: User’s Manual. City of Edina 2022 Water Resources Management Plan Appendices Appendix A Modeling Methods and Hydrologic and Hydraulic Analysis of Drainage Areas: A1. Methodology for Modeling A2. Nine Mile Creek North A3. Nine Mile Creek Central A4. Lake Cornelia/Lake Edina/Adam’s Hill A5. Nine Mile Creek South A6. Nine Mile South Fork A7. Southwest Ponds (Dewey Hill Road Area) A8. TH 169 North A9. Northeast Minnehaha Creek A10. Southeast Minnehaha Creek A11. Northwest Minnehaha Creek Appendix A Attachment A City of Edina Imperviousness Assumptions for Stormwater Modeling Appendix A Attachment B Summary of Nine Mile Creek and Minnehaha Creek Modeling Approach Appendix B Legacy Flood Risk Reduction Project Recommendations Appendix C List of Pond Improvement Recommendations City of Edina 2022 Water Resources Management Plan Appendix A Modeling Methods and Hydrologic and Hydraulic Analysis of Drainage Areas A1. Methodology for Modeling A2. Nine Mile Creek North A3. Nine Mile Creek Central A4. Lake Cornelia/Lake Edina/Adam’s Hill A5. Nine Mile Creek South A6. Nine Mile South Fork A7. Southwest Ponds (Dewey Hill Road Area) A8. TH 169 North A9. Northeast Minnehaha Creek A10. Southeast Minnehaha Creek A11. Northwest Minnehaha Creek Attachment A – City of Edina Imperviousness Assumptions for Stormwater Modeling Attachment B – Summary of Nine Mile Creek and Minnehaha Creek Modeling Approach City of Edina 2022 Water Resources Management Plan Appendix B Legacy Flood Risk Reduction Potential Projects Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-1 2011 CWRMP Plan Section Title 2011 CWRMP Text 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. Status notes from 2018 WRMP Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-2 2011 CWRMP Plan Section Title 2011 CWRMP Text 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. Status notes from 2018 WRMP Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-3 2011 CWRMP Plan Section Title 2011 CWRMP Text Status notes from 2018 WRMP 5.3.1.4 505, 509, & 513 Tyler Court (ML_19) An inundation area is located east of the homes along Tyler Court, south of Maloney Avenue and west of Arthur Street. Stormwater runoff from a drainage area of approximately 29 acres discharges into this dry basin. A 24-inch storm sewer system drains this area. The 24-inch system flows south and west to Arthur Street, then south to the intersection of Arthur Street and Waterman Avenue. At this intersection, the pipe flowing east toward Mirror Lakes is reduced to an 18-inch pipe. Due to the restricted pipe capacity at Arthur Street and Waterman Avenue, flow in the system draining the dry basin reverses during intense rainfall events such as the 100-year frequency event, and the basin is inundated. During the 100-year frequency storm event, the dry basin reaches a flood elevation of 936.6 MSL. This flood elevation is considerably higher than the low house elevations at 505, 509, and 513 Tyler Court, surveyed at 932.9 MSL, 933.1 MSL, and 934.07 MSL, respectively. To alleviate a portion of the flooding problem, it is recommended that the 18-inch pipe flowing east from the Arthur Street and Waterman Avenue intersection be upgraded to a larger pipe. By upgrading to a 24-inch pipe, runoff from Waterman Avenue and Arthur Street will not back up into the dry pond and the 100-year frequency flood elevation of the pond would decrease to 934.7 MSL. To further alleviate the flooding problem, it will be necessary to perform a more detailed analysis on the system that drains the backyard inundation area. No studies or improvements completed to date. Included as a current flood protection project in Section 5.3.1.1. 5.3.1.5 6009 Leslee Lane (MD_22) A backyard depression area exists between the properties on the south side of Leslee Lane and north side of Kaymar Drive. The depression area collects stormwater from a drainage area of approximately 6.4 acres. A 15-inch storm sewer system extends southward into the backyard depression area from Leslie Lane, collecting stormwater from the low area, and continues to the west toward Jeffrey Lane. This system eventually connects with the Blake Road system at the intersection of Blake Road and Kaymar Drive. During the 100-year frequency storm event, flow is restricted in the 15-inch system and water pools in the backyard depression area behind 6009 Leslee Lane. The predicted 100-year frequency flood elevation in this area is 916.7 MSL. Based on the 2-foot topographic data, it appears that this flood elevation will impact the structure at 6009 Leslee Lane. To alleviate the backyard flooding and prevent property damage at 6009 Leslie Lane, it is recommended that the 15-inch pipe draining the backyard depression and the downstream 18-inch pipe be upgraded to 24-inch diameter pipes. This would result in a predicted 100-year frequency flood elevation of 915.8 in the backyard depression area. There have not been any studies or improvement projects completed for this area. Included as a current flood protection project in Section 5.3.1.2. Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-4 2011 CWRMP Plan Section Title 2011 CWRMP Text 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. Status notes from 2018 WRMP Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-5 2011 CWRMP Plan Section Title 2011 CWRMP Text 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. Status notes from 2018 WRMP Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-6 2011 CWRMP Plan Section Title 2011 CWRMP Text 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. Status notes from 2018 WRMP Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-7 2011 CWRMP Plan Section Title 2011 CWRMP Text 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. Status notes from 2018 WRMP Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-8 2011 CWRMP Plan Section Title 2011 CWRMP Text 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. Status notes from 2018 WRMP Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-9 2011 CWRMP Plan Section Title 2011 CWRMP Text 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. Status notes from 2018 WRMP Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-10 2011 CWRMP Plan Section Title 2011 CWRMP Text 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. Status notes from 2018 WRMP Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-11 2011 CWRMP Plan Section Title 2011 CWRMP Text 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. Status notes from 2018 WRMP Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-12 2011 CWRMP Plan Section Title 2011 CWRMP Text 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. Status notes from 2018 WRMP Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-13 2011 CWRMP Plan Section Title 2011 CWRMP Text 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. Status notes from 2018 WRMP Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-14 2011 CWRMP Plan Section Title 2011 CWRMP Text 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. Status notes from 2018 WRMP Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-15 2011 CWRMP Plan Section Title 2011 CWRMP Text 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. Status notes from 2018 WRMP Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-16 2011 CWRMP Plan Section Title 2011 CWRMP Text 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. Status notes from 2018 WRMP Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-17 2011 CWRMP Plan Section Title 2011 CWRMP Text 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. Status notes from 2018 WRMP Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-18 2011 CWRMP Plan Section Title 2011 CWRMP Text 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. Status notes from 2018 WRMP Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-19 2011 CWRMP Plan Section Title 2011 CWRMP Text 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. Status notes from 2018 WRMP Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-20 2011 CWRMP Plan Section Title 2011 CWRMP Text 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. Status notes from 2018 WRMP Barr Engineering Co. 2018 Comprehensive Water Resources Management Plan: City of Edina C-21 2011 CWRMP Plan Section Title 2011 CWRMP Text 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. Status notes from 2018 WRMP City of Edina 2022 Water Resources Management Plan Appendix C List of Potential Pond Improvements 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.