5.2. SR 08-08-2011 - Laserfiche WebLink

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west of TH 10. However, because the current urban service area boundaries extend beyond the limits of the study area, a 15-inch sanitary sewer is recommended to provide additional capacity for future development. Wastewater from the portion of the study area between TH 10 and the Burlington Northern Railroad could be conveyed north and connected to the existing 15-inch sewer that extends north to 173~d Avenue (Figure 18-2). A 10-inch gravity sewer would be large enough to convey the estimated peak hour flow of 0.53 MGD from the portion of the study area between TH 10 and the Burlington Northern Railroad However, because the current urban service area boundaries extend beyond the limits of the study area, a 15-inch sanitary sewer is recommended to provide additional capacity for future development. Under this scenario, the collection system, including the TH 169 Lift Station, and the WWTF have the available capacity to handle the additional flows from the AUAR Study Area. However, under peak hour flow conditions 85% to over 90% of the capacity of sections of the existing trunk sewer system along Twin Lakes Road, from 179th Avenue NW to 171St Avenue would be utilized. Also under estimated peak hour flow conditions approximately 97% of the current pumping capacity of the TH 169 Lift Station would be utilized. Wastewater Mitigation Plan The mitigation plan for wastewater collection and conveyance associated with development of the AUAR Study area are shown in Figures 18-1 and 18-2: Under all three scenarios wastewater generator from the study area will be conveyed north through existing 15-inch and 18-inch trunk sewer lines along Twin Lakes Road and then west through the 24-inch trunk sanitary sewer to the TH 169 Lift Station. • Under all three scenarios, the existing collection system, including the TH 169 Lift Station, and the WWTF have existing available capacity to handle the additional projected flows from the AUAR Study Area. However, under Scenario 3, 85% to over 90% of the capacity of sections of the existing trunk sewer system along Twin Lakes Road from 179th Avenue NW to 171St Avenue would be utilized during estimated peak hour flow conditions. Also under Scenario 3, approximately 97% of the current pumping capacity of the TH 169 Lift Station would be utilized during estimated peak hour flow conditions. Wastewater from the portion of the study area on the west side of TH 10 could be conveyed north through a new sanitary sewer line constructed along the west side of TH 10 and connected to the existing 15-inch sewer that crosses TH 10 just north of 170th Avenue. Under Scenarios No. 1 and No. 2 a 10-inch diameter gravity sewer line would have sufficient capacity to carry the projected peak hour wastewater flows from the portion of the study area west of TH 10, plus potential flow from future development south of the study area. Under Scenario City of Elk River Draft Alternative Urban Areawide Review July 2011 Page SO of 84