Agenda - Planning Commission - 06/05/2003

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Subtotal 1.58 2.30 1.35 3.79 3.50 1.30 3.40 11.90 19.12 Grand Total I 26.37 *PVC- Public Value Credits Drainage Area 6 includes three existing wetlands (Wetland B, C and E). Wetland B is a created wetland that includes a narrow buffer within a conservation easement. The existing drainageway will be left intact, while 0.81 acres of the cropped wetlana will be 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 o.f 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 front 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 10, an&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 low 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, me.a. ndering, 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 wetland and 1.3 acres of buffer are proposed for Drainage Area 19. 239