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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 Wetland 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/ti 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 designed. Several locations could be <br />possible sites for incorporation of "new" wetland. To accomplish this action 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-establishment of native wetland communities. <br />Any wetland improvements in this area could be designed to also improve Blanding'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 />Reduce Frequency of Stormwater Discharge, Lower Magnitude of Peak 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 designed 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 during the. detailed design <br />phase for smaller storm retention. Peak flow rates for the 100-year, 24-hour runoff and <br />100-year, 1 O-day snowmelt events are 25.1 cfs and 25.3 cfs respectively. <br /> <br />Oversize Culvert and Reduced Slope at Outfall: The last section of culvert will be <br />enlarged from 21-inches to 36-inches and include an apron and rip-rap to lower velocities <br />and dissipate the energy at the discharge point. This will minimize the potential for scour <br />and erosion. <br /> <br />Directional Boring to Install Culvert: If possible, the culvert will be placed within the <br />river bank by directional boring rather than an open cut. This will reduce the need to <br />remove shoreline vegetation and will minimize the area of disturbance. Erosion control <br />measures will be implemented where soil is disturbed. All disturbed areas will be <br /> <br />D-7- <br /> <br /> <br />