8.3 SR 02-06-2023 - Laserfiche WebLink

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Table 4.10 — Preliminary Northwest Lift Station Design�'� Ultimate Initial Firm Ultimate Firm No. Min. Wet Forcemain Peak Pumping Pumping Pumps Forcemain Name Well Diameter Hourly Flow Capacity Capacity (Initial/ Depth (ft) Quantity (inch) (gpm) (gpm) (gpm) Ultimate) Regional 3,300 750 4,000 2 or 3/4 30 2 12 & 16 NW-LS-1 155 200 200 2/2 26 1 6 NW-LS-2 366 425 425 2/2 25 1 6 (1) 2040 firm pumping design capacities and forcemain diameters shall be revised during each lift station's design phase based on tinal development densities. Wastewater pumped by the northwest Regional Lift Station will be sent directly to the City's WWTP which will require the facility to update its receiving structure. This lift station will need at least a single 12-inch forcemain to operate at the recommended initial firm pumping capacity of 750 gpm. Similar to the existing TH 169 Lift Station, the proposed northwest Regional Lift Station can be constructed with enough space to install future pumps. Initially, only two to three pumps will be needed and individual pumping capacities can be increased or new pumps can be added in the future as development progresses. Although parallel forcemains are strongly recommended with long runs of forcemains like this one, the proposed parallel 16- inch forcemain will not be needed until approximately the 2050-2060 timeframe. Therefore, the City could choose not to install the 16-inch forcemain until later. However, for the purpose of budgetary planning, the cost estimate for the northwest study areas includes the construction of the 16-inch forcemain at this time. A proposed layout for both forcemains along the railroad corridor is shown in Figure A22 in Appendix A. A high-level ultimate sanitary sewer layout for the northwest areas beyond 2040 is shown in Figure A23 in Appendix A. Feasibility Report Northeast & Northwest Urban Service Area Expansion Study City of Elk River, MN WSB Project No. 020010-000 Page 21