Agenda - Council Work Session - 09/13/2022

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Pilot Study Report Water Treatment Plant Prepared for the City of Ramsey, Minnesota 1.2 2 2.1 Introduction Background SEH was contracted by the City of Ramsey to conduct a centralized water treatment plant feasibility study. As part of the study, SEH conducted a pilot study to consider options for the removal of iron and manganese from their water supply. The water quality in Ramsey is high in both iron and manganese with levels exceeding the United States Environmental Protection Agency (US EPA) secondary standards of 0.3 mg/L and 0.05 mg/L respectively. Along with the manganese secondary standard, Ramsey's average manganese levels exceed Minnesota Department of Health's (MDH's) Health Based Value (HBV) of 0.1 mg/L for bottle-fed infants less than one year of age. Objectives The objectives of the study were to evaluate the effectiveness of various treatment methods for removing iron and manganese, and then to select treatment methods for the design of a Water Treatment Plant for the City of Ramsey. The study included the following objectives: • Evaluate the effectiveness of chlorine and permanganate for the removal of iron and manganese; • Establish filter run lengths; • Evaluate filter loading rates; • Select the filter media type that provides the best removal of iron and manganese, and; • Evaluate the use of aeration and detention as part of the treatment process. Existing Facilities Wells The City of Ramsey has eight wells all located in the southern part of town north of U.S. Highway 10. The City's original two wells, Wells No. 1 and 2, are located in the southeast part of town, while the other wells are all located in the southwest part of town. The wells are capable of producing approximately 11 million gallons per day, although the treatment plant would be located within the southwest well field and thus would not be fed by Wells No. 1 or 2, making the potential treatment capacity 9.5 million gallons per day. Page 1 RAMSY 154354