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Design Flows and Capacities <br />x A sewer demand analysis was performed using the TCAAP Mater Plan – Option B and the Design <br />Development Scenario noted above. The average daily demand is 0.70 million gallons per day <br />(mgd). <br />x A downstream capacity analysis was performed for the existing trunk sanitary sewer conveying <br />discharge from the site to the Metropolitan Council Environmental Services (MCES) Lift Station <br />35 in Mounds View and the existing system has adequate capacity to serve the TCAAP Site. <br />Adequate capacities for the MCES lift station and interceptor system to serve the site have been <br />confirmed. <br />x The existing trunk sanitary sewer was visually inspected and determined to be acceptable. <br />x Meetings and coordination have occurred with Metropolitan Council Environmental Services <br />(MCES) to confirm lift station and interceptor capacity and to establish a feasible and acceptable <br />method for measuring flows discharging from the site. <br />x Once the existing trunk sanitary sewer reaches a flow of 0.5 mgd, the trunk sanitary sewer <br />would be eligible to classified as an MCES interceptor, which would be owned and maintained <br />by MCES. <br />Preliminary Sanitary System Design <br />x A sanitary sewer system has been developed to serve the entire TCAAP site. The pipe sizes range <br />from 8-inch to 18-inch. <br />x An inverted siphon will not function properly for the proposed site and construction phasing and <br />therefore a lift station will be required to serve the TCAAP site south of County Road H. <br />x The lift station will be designed to accommodate a wide range of flow rates as the site is <br />developed. A variable frequency drive (VFD) motor will be used to adjust pumping power. <br />x The TCAAP Thumb Parcel can be served with gravity sewer and can be developed in advance of <br />installing a lift station. <br />x The gravity sewer for the TCAAP Thumb will be at the depth required to serve the MnDOT <br />facilities to the north. A 4” PVC force main extending from the sanitary sewer manhole to the <br />north property line is recommended to provide service to the MnDOT facilities in the future. <br />x After the sanitary sewer system is finalized, these additional preliminary design tasks will be <br />completed: <br />o Prepare a detailed cost estimate of the sanitary sewer system infrastructure <br />o Prepare a MN Statutes Chapter 429 Feasibility Report <br />o Prepare a maintenance needs spreadsheet (man-hours and equipment) <br />o Evaluate if special construction and/or maintenance issues exist in any TCAAP areas due <br />to the presence of groundwater contamination and if so, provide recommendations and <br />estimated additional construction/maintenance costs.