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1. Detention basins must be designed to provide an outlet structure to control the <br />1 -year or 2 -year, and 100 -year frequency events to pre -project peak runoff sites. <br />An emergency overflow spillway must be identified that provides for the safe <br />conveyance of larger flows. <br />2. Permanent sedimentation and water quality ponds are required and must be <br />designed to provide water quality features consistent with the National Urban <br />Runoff Program (NURP criteria) and District wet pond criteria. This includes: <br />a) A permanent wet pool with dead storage of at least equal to the runoff from <br />a 2.5 rainfall over the area tributary to the pond, <br />b) An outlet structure capable of preventing migration of floating debris and <br />oils for at least the one-year storm; and, <br />c) Access for future maintenance. <br />3. All new residential, commercial, industrial and other habitable or non -habitable <br />structures must be constructed so that the lowest floor elevations are a minimum <br />of two feet above the critical event 100 -year high water elevation and are one - <br />foot above the overflow elevation of nearby waterbodies. <br />4. Development resulting in the creation of impervious surfaces must explicitly <br />address the use of Best Management Practices (BMPs) to: <br />a) Limit the loss of pervious area; and, <br />b) Infiltrate runoff which does occur from impervious areas to the extent <br />feasible. <br />5. Incorporate practices into the design which are capable of infiltrating the <br />impervious surface runoff from the Minneapolis -St. Paul median storm (0.34 <br />inches) in 72 hours. <br />B. PROPOSED RCWD STORMWATER RULES <br />RCWD is proposing new rules that would modify the existing rules discussed above. <br />These proposed rules would apply to three types of project types: <br />Northwestern College Master Plan 10 13529.000 <br />Stormwater Management Study <br />