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Stantec CENTERVILLE SURFACE WATER MANAGEMENT PLAN WATER RESOURCE MANAGEMENT PLAN September 2012 Rice Creek Watershed District identifies the intercommunity flows from Centerville to Lino Lakes, via Clearwater Creek (Anoka - Washington Judicial Ditch 3) as: • 2 -year, 24 -hour rainfall peak flow: 195 cfs • 10 -year, 24 -hour rainfall peak flow: 303 cfs • 100 -year, 24 -hour rainfall peak flow: 422 cfs • 100 -year, 10 -day snowmelt peak flow: 413 cfs Because of the large storage volume available in the two lakes, peak flows entering from the City will be greatly attenuated prior to discharge from Peltier Lake. As stated earlier in this chapter, the City requires that peak flow rates from the 2 -, 10 -, and 100 -year storm events be maintained at or below existing conditions. The RCWD rules require the infiltration and /or retention of the runoff volume generated by the 2.8 -inch storm event (for new development) or 0.8 -inch storm event (for redevelopment). The combination of all of these factors leads to a net reduction below existing conditions for discharge leaving the City and entering Lino Lakes. 6.8 EROSION AND SEDIMENT CONTROL Recognizing that erosion and sediment control can best be administered on a local level, the Centerville City Council discussed methods and policies that can be implemented to control erosion from new construction sites. In the past, this responsibility was delegated almost fully to the Rice Creek Watershed District. However, due to the number of construction projects the RCWD administers during a given construction season, it is difficult for the watershed district to inspect these projects. The erosion and sediment control criteria for new developments that resulted from these discussions with the City have been consolidated into an Erosion and Sediment Control Policy for New Developments. The policy adopts the procedures and recommendations of the Minnesota Pollution Control Agency's Protecting Water Quality in Urban Areas: Best Management Practices for Minnesota. City Code Chapter 157 addressing Erosion Control is provided in the appendix. NPDES permitting requires that the MPCA should be notified of all grading activities affecting 1 acre or more. The City ensures MPCA notification through developer agreements as projects of this scale arise. The RCWD has encouraged the City to participate in the District's Water Quality BMP Cost - Share Program. This is a dedicated cost -share grant program to assist property owners with the implementation of Best Management Practices (BMPs) aimed at improving the quality of surface waters within the District. Installing a rain garden, stabilizing erosion problems along shorelines, restoring degraded wetlands, installation of agricultural BMPs, and installing pervious pavers are some of the practices that may be eligible for this program. For selected projects, the RCWD may provide funding up to 50% of total project costs up to a maximum of $5,000. One Team. Infinite Solutions. 6.17 36