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meet State nondegradation requirements in addition to City and other local ' <br />requirements. <br />E7. Storm water will be required to be pretreated prior to discharge to wetlands. ' <br />E8. A Storm Water Pollution Prevention Plan (SWPPP) in conformance with the <br />NPDES regulations will be needed for any development in the study area. t <br />Review of the SWPPP for each development will be required by the City. <br />F. Wastewater Mitigation Plan ' <br />F1. Under all three scenarios wastewater generated from the study area will be <br />conveyed north through existing 15-inch and 18-inch trunk sewer lines along <br />Twin Lakes Road and then west through the 24-inch trunk sanitary sewer to the ' <br />TH 169 Lift Station. <br />F2. .Under all three scenarios, the existing collection system, including the TH 169 ' <br />Lift Station, and the WWTF have existing available capacity to handle the <br />additional projected flows from the AUAR Study Area. However, under Scenario <br />3, 85% to over 90% of the capacity of sections of the existing trunk sewer system ' <br />along Twin Lakes Road from 179TH Avenue NW to 171 Avenue would be utilized <br />during estimated peak hour flow conditions. Also under Scenario 3, , <br />approximately 97% of the current pumping capacity of the TH 169 Lift Station <br />would be utilized during estimated peak hour flow conditions. <br />F3. Wastewater from the portion of the study area on the west side of TH 10 could ' <br />be conveyed north through a new sanitary sewer line constructed along the west <br />side of TH 10 and connected to the existing 15-inch sewer that crosses TH 10 ' <br />just north of 170Th Avenue. Under Scenarios No.1 and No. 2 a 10-inch diameter <br />gravity sewer line would have sufficient capacity to carry the. projected peak. <br />hour wastewater flows from the portion of the study area west of TH 10, plus ' <br />potential flow from future development south of the study area. Under Scenario <br />No. 3 a 15-inch gravity sewer line would be required. For Scenario No.1 a 10- <br />inch diameter sewer would be recommended to serve the area along the west <br />side of TH 10. For Scenarios No. 2 and No. 3 a 15-inch gravitysewer line is <br />recommended for carrying the projected flows from the portion of the study <br />area west of TH 10 to allow for potential future development south of the study ' <br />area. <br />F4. Wastewater from the portion of the study area between TH 10 and the <br />Burlington Northern Railroad could be conveyed north and connected to the <br />existing 15-inch sewer just south of 171~T Avenue that extends north to 173ra <br />Avenue. For all three scenarios, a 10-inch gravity sewer would be large enough <br />to convey the estimated peak hour flow from the portion of the study area <br />between TH 10 and the Burlington Northern Railroad. However, because the <br />current urban service area boundaries extend beyond the limits of the study <br />area, a 12-inch sanitary sewer is recommended to provide additional capacity <br />.for future development. <br />City of Elk River <br />Draft Alternative Urban Areawide Review <br />August 2011 <br />Page 12 of 94 , <br />