08-22-2022 City Council Packet - Laserfiche WebLink

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REVIEW OF EXISTING SITES AND INFRASTRUCTURE The WSB team will visit the proposed water treatment plant site and review the existing as -built drawings, easements, and existing infrastructure in extensive detail. Potential contaminants and other barriers that may restrict or affect the layout of the plant at the site will be evaluated up front during this analysis. Other factors such as ease of chemical deliveries, access for maintenance trucks, security, stormwater retention, proximity to water and sanitary sewer utilities, and proximity to three phase-480 volt electrical power will be evaluated during the preliminary design phase. REVIEW OF TREATMENT TECHNOLOGIES AND TOURS OF EXISTING WATER TREATMENT FACILITIES Potential treatment methods and technologies to treat the city's existing and future wells will be studied in detail. The WSB team will analyze the treatment technologies identified in the feasibility study report and other technologies to make certain that the city receives the most current, advanced, and cost effective treatment technology available. If requested by the city, WSB will coordinate and attend additional tours of existing water treatment facilities that utilize each of the treatment methods being evaluated so that city staff have a clear understanding of the treatment technologies and options that are available for the Water Treatment Plant. The analysis will include, but not be limited to, initial construction costs, long term operational costs, flexibility of each system to treat additional elements as standards change, water chemistry changes or demand necessitates, the ability of each system to effectively and efficiently remove iron, manganese and other contaminants from the water supply, ease of operation of each system (manpower needed, availability of replacement parts and materials, etc.), the discharge of the waste product, and ability of the plant to expand or be modified in the future. This will be a comprehensive review and recommendation on the "best" plant to meet the current and future needs of the city. The city's existing wells produce high concentrations of manganese. The manganese concentrations range from 0.152 to 0.383 mg/L in the City's highest manganese producing well. The highest manganese concentrations are over seven times the recommended secondary standard (0.05 mg/L) for manganese. More importantly, all four of Wells 1, 3, 5, and 6 exceed MDH's recommended guidance level of 100 micrograms per liter of manganese for infants. The iron, manganese, and ammonia in the City's well water could be treated without chlorine and potassium permanganate with biological filtration. Biological filtration is commonly practiced in the United States and Europe and is endorsed by the Minnesota Department of Health (MDH) as an efficient and effective method for treating these (and other) contaminants. The benefits of biological filtration include higher filtration rates, longer filter runs (reduces backwash supply and wastewater volumes), savings in chemical costs, and reduction in disinfection byproducts. The design of a conventional gravity filtration process with detention and aeration can easily accommodate biological filtration. A Proposal for Design, Bidding, and Construction Administration for a Water Treatment Plant for City of Lino Lakes Project Understanding & Approach 7