Agenda - Planning Commission - 05/01/2003

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38 restored to a Type 1, wet prairie wetland. A 0.77-acre riparian buffer will be incorporated along the wetland transition zone in this area. Drainage Area 7 will include a 2.30-acre stormwater detention pond. This pond will include a shallow bench that will support a fringe of emergent vegetation. Since this- pond will provide pretreatment of stormwater that will benefit the wetland immediately downstream of it (within Drainage Area 8), it is proposed for public value wetland credits. Drainage Area 8 includes 1.35 acres of wetland and 1.35 acres of PVC buffer with a meandering channel flowing though it. Portions of the basin will be designed to establish Type 1, wet meadow/wet prairie wetland hydrology. The basin will be established with respect to groundwater levels and a low weir will be installed in fl'ant of the outlet such that infiltration will be maintained, but water will be retained at a frequency to facilitate saturation of soils. Finer soils could be mixed in to promote Type 1 vegetation. Within Drainage Area lO, and along the north boundary of the RTC site, is a 3.79 acre wetland, where 2.23 acres of this wetland is within the RTC site and is denoted as "Wetland D". This wetland is a iow quality reed canary grass monotype with a few small areas of mixed emergent marsh vegetation. A total of 3.79 acres of wetland restoration and buffer PVC is proposed for this wetland. The primary objective of this restoration would be to remove the non-native reed canary grass and reestablish a diverse, wetland community of wet meadow and mixed emergent marsh. Since portions of this 3.79-acre wetland occur on private property, landowner cooperation would be necessary to successfully restore this wetland. The 3.79 acres of proposed restoration includes both wetland restoration and establishment of buffers. Drainage Area 18 will include a 3.5-acre stormwater pond that will function much the same as the stormwater pond proposed for Drainage Area 7. The concept design described for Area 7 generally applies to Area 18. The wetland system in Drainage Area 19 will function in a way similar to Drainage Area 8; that is, it will include a narrow, meandering, perennial stream with a wet meadow/wet prairie fringe. The design concept described for Drainage Area 8 describes this wetland. A total of 1.3 acres of wettand and 1.3 acres of buffer are proposed for Drainage Area 19. Drainage Area 24: This drainage area encompasses a linear area between the Railroad ROW and the RTC. This entire strip ofland encompasses some 10.8-acres of land. A total of 2.7-acres, or 1/4 of Area 24, is proposed as new wetland credit. A central, meandering drainage-way of Type 3 wetland is proposed. The edges of this wetland will be bordered with Type 1 and 2 wetland meadow. Drainage Area 26: Development of this combined wetland/infiltration system is conditioned on approval by Anoka County. This system would receive flows from Drainage Area 25 and would include a wetland treatment/stormwater pond (26a). From this initial pond, flows would outlet into an infiltration pond/wetland system (26b). A I I I i I I I I I I I I I I I I I I I