Agenda - Parks and Recreation Commission - 04/10/2014

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SECTION 2 SANITARY SEWER FLOW PROJECTIONS A. PURPOSE Sanitary sewer flow projections form the basis of planning for future sanitary sewer infrastructure needs. The City of Ramsey is located in the northwest corner of Anoka County and is experiencing tremendous growth which is requiring expansion of the sanitary sewer facilities necessary to convey and treat sanitary sewer flow. In order to project future sanitary sewer flows, average daily flows for residential, commercial and industrial users must be evaluated and projected. In addition, maximum day to average day peaking factors must be determined in order to project the peak flows for infrastructure sizing. This section will provide an analysis of land use trends based on comprehensive plan projections, population growth trends, historical usage, allocation of sanitary sewer demands to residential, commercial and residential user categories, and projection of future average to peak sanitary sewer demands. B. DESIGN CRITERIA The 1974 City of Ramsey Comprehensive Sewer Plan used a per capita design flow of 100 gallons per capita per day. Sewer studies since 1978, including the 1991 Comprehensive Sewer Plan used a per capita design flow of 75 gallons per capita per day, which was supported by actual sewer flows experienced by the City and other similar metropolitan communities. This study recommends the continued use of 75 gallons per capita per day. Sanitary sewer flow varies over a 24-hour period with peak flows generally in the morning and evenings. Therefore, in order to size sanitary sewer facilities, the variation between average and peak flows is estimated. Typically flow variation between average and peak flows are between 2.5 for major trunk facilities and 4.0 for local lateral lines. Flow variation factors City of Ramsey Page 2-1 Comprehensive Sanitary Sewer Plan - 2004 Prepared by Bolton & Menk, Inc.