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River Islands Development at Lathrop November 2020 <br /> Final Phase 2 Sewer Technical Report Rev 1 #6520 <br /> 3. Sewer Generation Rates <br /> 3.1 Sewer Generation Rates <br /> Per the City Standards, all sewers lines should be designed to carry the PWWF from all areas tributary to <br /> them. The design flows (PWWF)at any point should be the ADWF multiplied by the peaking factor per City <br /> Detail S-1 (see Appendix D). Sewer should also be designed for both size and depth to accommodate <br /> developments in upstream tributary areas that would logically be served by them. <br /> 3.1.1 Sewer Generation Rates—Average Dry Weather Flow <br /> Section 5-4.2 in the City Standards, lists the land use sewer flow factors to be used to estimate the ADWF. <br /> These generation factors have recently been revised, based upon review of actual flow data from more <br /> than a thousand homes, measured at the interim pump station. Table 3-1 below summarizes the land use <br /> sewer flow factors to compute the ADWF in accordance with Section 5-4.2. <br /> Table 3-1: Land Use Sewer Flow Factors <br /> Land Use Land Use Sewer Flow Factor <br /> Low Density Residential 200 GPD/du <br /> Medium Density Residential 180 GPD/du <br /> High Density Residential 170 GPD/du <br /> Commercial 590 GPD/ac <br /> Industrial 355 GPD/ac <br /> Parks 55 GPD/ac <br /> Schools/ Institutional 245 GPD/ac <br /> NOTE 1 —Land Use Sewer Flow Factors in Table 3-1 are from the City's Design and Construction Standards. <br /> NOTE 2—Gallons per Day(GPD) <br /> To compute the ADWF,the assigned land use for each lot/parcel should be multiplied by its applicable land <br /> use sewer flow factors as shown in the equation below. <br /> Average Dry Weather Flows (gpd) <br /> = Parcel's Land Use Factor x Land Use Wastewater Flow Factor <br /> Table 3-2 lists the computed ADWF for each land use type within River Islands in accordance with the <br /> City's Standards. <br /> Table 3-2: Phase I and II Average Dry Weather Flows <br /> Land Use <br /> Phase I & II Sewer Flow Average Dry <br /> Total Number Factor Weather Flow <br /> Land Use of DU/Acres (GPD/du or ac) (GPD) <br /> Low Density Residential (DUs) 7,191 200 1,438,200 <br /> Medium Density Residential (DUs) 3,636 180 654,480 <br /> High Density Residential (DUs) 4,183 170 711,110 <br /> Commercial (acres) 258.4 590 152,438 <br /> Industrial (acres) 0.0 355 0 <br /> Parks (acres) 341.8 55 18,798 <br /> Schools/ Institutional acres 162.0 245 39,692 <br /> Total 3,014,719 <br /> 12 <br />