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<br />. <br /> <br />The minimum building elevation shall be the greatest of either 2 feet above the level resulting from <br />two concurrent 100-year, single event rainfall events or 2 feet above the 100-year lO-day snowmelt. <br />In either case, the starting elevation of the pond/waterbody prior to the runoff event shall be <br />established by one of the following: <br /> <br />1. Existing Ordinary High Water level established by the MDNR <br />2. Annual water balance calculation approved by the LRRWMO; <br />3. Local observation well records, as approved by the LRRWMO; or <br />4. Mottled soil. <br /> <br />Pond Construction <br />Above Normal Water Elevation <br />The following criteria will be followed for pond construction above the normal water elevation. This <br />area of the pond will more than likely be the pond area flooded during a storm up to a IOO-year <br />duration. <br /> <br />. Maximum side slopes above the normal water level of 3 horizontal to I vertical. <br />. Proper allowan~e for access and maintenance easements. <br />. Emergency overflow above the 100-year design storm high water elevation. <br />. Erosion control per erosion control standard. <br />. Restoration per restoration standard. <br /> <br />All disturbed or constructed wetland areas will be restored using City-approved mitigated vegetation <br />which is consistent with surrounding vegetation. All other areas will be seeded immediately after <br />pond construction with a mixture containing fast germinating seed mixture and permanent grasses. <br />Areas may be sodded instead of seeded. <br /> <br />Live storage volume shall be sized to prevent flooding of existing structures, maintain the flow rates <br />approved by the member cities, and handle all future development proposed in the watershed. In <br />areas identified as critical to maintain wildlife habitat, the bounce of the pond shall be limited to <br />protect the habitat. <br /> <br />Size <br /> <br />Nation-wide Urban Runoff Program (NURP) ponds will be designed with standing water or dead <br />storage for pollutant removal. The total phosphorus removal efficiency for each pond or pond <br />network must provide at least 60 percent average annual range and at least 90 percent annual removal <br />efficiency of total suspended solids. Stormwater treatment can be provided via a single pond which <br />meets the design and treatment criteria or an on-site network of interconnected ponds. If an on-site <br />pond network is used, the overall pollutant removal efficiency for the network must meet the criteria. <br /> <br />Water Management Plan <br />P:\Mpls\23 MN\02\2302047\WorkFiles\3rd Gen WMP\LRRWMO_3rd Gen WMP _July 2009_Draft.doc <br /> <br />81 <br />