5.2. SR 08-08-2011 - Laserfiche WebLink

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As with Scenario 1, wastewater generated from the study area will be conveyed north through existing 15-inch and 18-inch trunk sewer lines along Twin Lakes Road to 179th Avenue NW and then west through the 24-inch trunk sanitary sewer to the TH 169 Lift Station. 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 (Figure 18-2). An 8-inch sewer would be large enough to convey the estimated peak hour flow of 0.40 MGD wastewater generated from this area 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 0.403 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 12-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. Scenario 3 The land use for this scenario is similar to Scenario 2 with the exception that a higher density for residential units is used (20 units per acre rather than 8 units per acre) and the building square footage for job area, destination retail, temporary destination retail, and service/commercial are higher than for Scenario 2. For Scenario 3, an average daily wastewater flow of 200 gpd/unit will be used for high density residential and 1,400 gpd/acre will be used for destination retail and service/commercial development. An average daily wastewater flow of 1,000 gpd/acre will be used for job area and transit center. As with Scenario 2, no wastewater flow is projected for temporary destination retail and open space. A peaking factor of 3.6 was used to determine the peak hour flow from the overall AUAR area under this scenario. Based on these wastewater generation rates, the estimated average day wastewater flow projected for the portion of the study area west of TH 10 under Scenario 3 would be 0.227 MGD and the estimated peak hour flow would be 0.82 MGD. The portion of the study area between TH 10 and the Burlington Northern Railroad would generate the same estimated average day wastewater flow projected for City of Elk River Draft Alternative Urban Areawide Review July 2011 Page 48 of 84