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<br />I <br />'- <br />I <br />1 <br />I <br />I <br />I <br />I <br />I <br />. <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />r <br /> <br />I <br /> <br />Appendix J: Pond Design Standards <br /> <br />Water auality Treatment <br />Subd. 1. Development that is not tributary to an existing regional treatment pond is required to <br />employ best management practices to treat storm water discharge. <br /> <br />Pond Construction <br /> <br />Subd. 1. Above Normal Water Elevation <br /> <br />The following criteria will be followed for pond construction above the normal water elevation. For <br />pond construction below the normal water elevation, refer to Pond Restoration and Nutrient Trapping <br />Pond Design Standards on the following pages. This area of the pond will more than likely be the <br />pond area flooded during a storm up to a 100- year duration. <br /> <br />. Maximum 3 Horizontal to 1 Vertical (3H: I V) side slopes. <br />. Proper access for maintenance, operations, and inspection. <br />. Emergency overflow above the lOO-year design storm high water elevation. <br /> <br />Subd. 2. Nutrient Trapping Pond Design <br />Newly constructed detention basins shall provide additional storage volume below the outlet to allow <br />for reasonable accumulation of sediment. Where sedimentation is considered to be a continuous <br />problem, access to the area to allow for sediment removal is required. <br /> <br />General Criteria <br />The following general criteria should be used when designing the sediment pond: <br /> <br />. For basins intended to have permanent water levels, a minimum of 4 feet of standing water (dead <br />storage depth). <br /> <br />Maximize the separation between inlet points and outlets to prevent short-circuiting of storm <br />flows. <br /> <br />. A 10:1 slope for the first 10 feet from shore, then 3:1 maximum slope. <br /> <br />. Proper access for maintenance, operations, and inspection. <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 fall in the 65-70 percent range. Storm water treatment can be provided via a single <br />pond which meets the design and treatment criteria or an onsite network of interconnected ponds. If <br />an onsite pond network is used, the overall pollutant removal efficiency for the network must meet <br />the criteria. <br />