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Drainage Area 24: This drainage area encompasses a linear area between the Railroad <br />ROW and the RTC. This entire strip of land encompasses some 10.8-acres of land. A <br />total of 2.7-acres, or 1/4 of Area 24, is proposed as new wetland credit. A central, <br />meandering drainage-way of Type 3 wetland is proposed. The edges of this wetland will <br />be bordered with Type 1 and 2 wetland meadow. <br /> <br />Drainage Area 26: Development of this combined wetland/infiltration system is <br />conditioned on approval by Anoka County. This system would receive flows from <br />Drainage Area 25 and would include a wetland treatment/stormwater pond (26a). From <br />this initial pond, flows would outlet into an infiltration pond/wetland system (2~b). A <br />landscape theme that incorporates a mixture of dry prairie, oak savanna, and wet prairie <br />with an ephemeral water-way could serve as the cornerstone for this area and provide a <br />valuable link between RTC and Mississippi West Regional Park. <br /> <br />Off-Site g/etland Mitigation <br />Two additional areas have been identified for off-site wetland mitigation in the event on- <br />site mitigation is not feasible. These sites are illustrated in Figure 12.5. <br /> <br />Site #1 would be within the Mississippi Regional Park when development of the park- <br />proceeds. Although a specific location cannot be identified at this time, the City, WMO <br />and County would work together to select and develop a site that would hold the best <br />potential for successful wetland establishment. Figure 12.6 illustrates the Anoka County <br />Park Department's concept for how the Park will be desig-ned. Several locations could be <br />possible sites for incorporation of"new" wetland. To accomplish thi~ actl3n in 'the <br />future, RTC LLC would need to escrow an amount of funds sufficient to construct the <br />additional wetland acreage not provided for on-site. <br /> <br />Site #2 is located along the south - southeast side of Lake Itasca on land already owned <br />by the City of Ramsey. This area currently contains some excellent quality shrub swamp, <br />wet prairie and emergent marsh along the shores of Lake Itasca. A suitable site could be <br />located where wetland does not currently exist, but where adequate hydrology is <br />available. There are also several areas of reed canary-dominated wetland that could be <br />improved for public value credit though re-establisl-mqent of native wetland CommunSties. <br />Any wetland improvements in this area could be desig'ned to also improve Btanding's <br />turtle habitat. <br /> <br />The following are proposed to mitigate impacts associated with the stormwater outfall to <br />the Mississippi River: <br /> <br />Redzice Frequency of Stormwater Discha~Te, Lower Magnitztde of Peatc Flow Rates: The <br />RTC project incorporates a variety of strategies to lower increases in stormwater rate and <br />volume. While all stormwater conveyance features are desig'ned to accommodate the <br />100-year runoff event without taking infiltration into consideration, on-site retention and <br />infiltration can be incorporated at multiple scales into the RTC dur/ng the detailed design <br />phase for smaller storm retention. Peak flow rates for the 100-year, 24-hour runoff and <br />100-year, I O-day snowmelt events are 25.1 cfs and 25.3 cfs respectively. <br /> <br />240 <br /> <br /> <br />