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1 <br /> <br />CITY COUNCIL <br />WORK SESSION STAFF REPORT <br />ITEM NO. 5 <br /> <br />STAFF ORIGINATOR: Michael Grochala, Community Development Director <br /> <br />WORK SESSION DATE: February 5, 2024 <br /> <br />TOPIC: Water Treatment Plant Capacity Analysis <br /> <br />______________________________________________________________________________ <br />BACKGROUND <br /> <br />The City authorized the preparation of plans and specification for the Water Treatment Plant in <br />August of 2022. The plant uses a gravity filtration process that is capable of operating either <br />conventionally or biologically. Biological filters, where a microbial population is promoted in <br />the filters to perform iron, manganese, and ammonia removal, can often be operated at higher <br />loading rate, thereby increasing the WTP capacity. This increase is only feasible under <br />biological filtration. <br /> <br />The plant is being designed to conventionally treat a volume of 6,000 gallons per minute (gpm) <br />based on our 2040 forecasted demand. The City’s Comprehensive Water Plan anticipates an <br />ultimate treatment need of 10,000 gpm. This additional treatment is planned to be provided by <br />a 2nd WTP and well field in the north side of Lino Lakes. <br /> <br />To minimize long term infrastructure costs staff requested WSB to complete a capacity analysis <br />to determine what would be needed to maximize potential for biological treatment at the <br />proposed plant. Based on the review the biological WTP capacity could potentially increase <br />from 6,000 to 10,000 gpm with no change to filters. However, this would require oversizing of <br />other components of the plant and distribution system to accommodate the higher flow rate. <br /> <br />While the projected post 2040 demand is well into the future, it is a sizable increase, and likely <br />to change, oversizing of certain components within the plant would add future flexibility and <br />redundancy to the plant’s operations. Elimination of a future water treatment plant would <br />result in substantial savings in future infrastructure costs. A high level estimate provided by <br />WSB identified a potential cost savings of $25 million. <br /> <br />After additional discussion with WSB, staff is recommending the addition of a fourth high <br />service pump, expanded aerators and larger electrical service at the time of construction. This <br />would improve operation and maintenance of the plant initially while providing future capacity. <br />50