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COMPREHENSIVE SEWER PLAN <br />Sanitary Sewer Design Criteria <br />September 15, 2020 <br />:3.0 SANITARY SEWER DESIGN CRITERIA <br />3.1 LAND USE <br />The 2040 land use identified in Mounds View's 2018 Comprehensive Plan update (see Appendix F) is the <br />land use that served as the basis for the development of the sanitary sewer flow projections and analysis <br />of the trunk system. Using the future land use plan, the area of each land use was determined for each <br />sewer subdistrict. Detailed descriptions of the various land uses are found in the City of Mounds View <br />Comprehensive Plan. Areas of each land use by sewer subdistrict are presented in Appendix A. <br />3.2 ESTIMATED AVERAGE WASTEWATER FLOWS <br />Municipal wastewater is made up of a mixture of domestic wastewater, commercial and industrial wastes, <br />groundwater infiltration, and surface water inflows. With proper design and construction, groundwater <br />infiltration and surface water inflows, or infiltration/inflow (1/1), can be minimized. The flows due to 1/1 are <br />accounted for in the analysis and design of the trunk sewer system. The anticipated average wastewater <br />flows from the various sewer subdistricts were determined by applying unit flow rates to each of the land <br />use categories. The "system design" unit flow rates are presented in Table 3-1. The average wastewater <br />flows for each sewer subdistrict are presented in Appendix B. <br />For all land uses, unit rates/acre were used to generate average flow projections. The units per acre <br />assumptions and population densities for the residential land uses were based on information from the <br />City Planning staff. The estimated flows are in accordance with standard engineering practice in <br />accordance with our experience in Mounds View as well as other communities in the Twin Cities area and <br />are generally considered conservative. <br />Table 3-1 — System Design Wastewater Unit Flow Rates <br />hk FLand Use Tlyw� <br />Single Family Residential <br />Gal/Acre/Day <br />616 <br />Multi -Family Residential <br />1,232 <br />Mobile Home <br />660 <br />Mixed Use <br />1,200 <br />Commercial <br />1,200 <br />Industrial <br />1,200 <br />Public <br />800 <br />Parks/Open Space <br />0 <br />3.3 PEAK FLOW FACTORS <br />The sanitary sewer system must be capable of handling the anticipated peak wastewater flow rate <br />including any 1/I. The design peak flow rate is expressed as a variable ratio to the average flow rate. <br />B <br />,\1938\active\193804167\reports\2018 csp\submitted to city 9-8-2020\moundsviewcsp_formcesreview_09152020_updateddraft.docx 3.5 <br />