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available fire flows were assigned to the various land use areas as follows: 5000 gallons per <br />minute (gpm) for industrial areas, 3500 gpm for commercial, and 1500 gpm for residential. <br />x After completion of various analyses using the water model,it is concluded that the peak day <br />demand can be delivered through the existing Arden Hills system, and that the TCAAP area will <br />be in the same pressure zone as the existing Arden Hills high pressure zone (area north of I-694), <br />with a similar range of pressures. The need for the following key infrastructure components <br />have been confirmed: <br />o A network of 8-inch and 12-inch PVC water mains is needed in the development area. <br />o In order to meet the target 5000 gpm industrial fire flow for the recommended 3-hour <br />duration, a 1.5 million gallon water tower is needed. The height of the tower would be <br />similar to the existing north tower (these two towers will have the same top elevation). <br />o The existing pressure boosting station should be kept as is. A second pressure boosting <br />station should be added at the existing western 12-inch water main crossing of I-694 in <br />order to meet the target fire flow and, importantly, to provide redundancy in the water <br />supply crossing I-694 (otherwise a single crossing / booster station must be relied upon). <br />o The MnDOT facilities to the north of the Thumb parcel can be served from Arden Hills <br />These facilities are currently served by the City of Mounds View with a 10-inch water <br />main owned by the State. <br />o Interconnection with the Mounds View water system: This option appears technically <br />attractive given that there is already a 10-inch water main installed beneath I-35W to <br />the west edge of the Thumb parcel. Interconnection would include a normally-closed <br />gate valve, which would only be opened in the event of a water emergency (on either <br />side). This interconnection will also provide a key benefit to the anticipated early <br />Thumb Parcel development since, without this interconnection, any problem with the <br />primary water supply (a lone 12-inch water main extended from Arden Hills) would <br />completely cut off water supply to the Thumb parcel. It could also boost the available <br />fire flow in an emergency, which will be initially limited to 2200 gpm through the lone <br />12-inch water main, until Arden Hills completes the Spine Road water main into the <br />Thumb parcel. <br />x After review of the recommended infrastructure with the Arden Hills City Council, these <br />additional preliminary design tasks will be completed: <br />o Prepare a detailed cost estimate of the water system infrastructure including trunk <br />water main throughout the TCAAP development, any interconnections, the added <br />booster station, and the water tower. <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. <br />Sanitary Sewer System Design <br />The sanitary sewer system design has two major tasks - determining design flows and capacity and <br />designing a sanitary sewer system for the design development scenario. The TCAAP site will be served <br />by an existing trunk sanitary sewer line that was constructed in 1994 for the US Army. Ramsey County <br />acquired this facility and an existing connection and use agreement.