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DRA <br />F <br />T <br /> <br /> <br /> <br /> <br />P18-0078, P18-0080, P18-0081, PUD-130, and Tract 8569 PC-2026-09, April 22, 2026 <br /> <br />20 of 36 <br /> <br />connections to the City’s sewer network. Public sanitary sewer system shall be <br />designed to satisfy the following minimum standards: <br /> <br />a. Minimum Manning Coefficient (n) within the pipe = 0.013 <br /> <br />b. Minimum flow velocity = 2 feet per second at least once per day <br />c. Maximum flow velocity = 10 feet per second <br /> <br />d. Maximum depth of flow to pipe diameter (d/D) = 0.75 for dry weather flow <br />conditions <br /> <br />e. Minimum pipe sizes: <br />i. Laterals = 4 inches diameter <br />ii. Main = 8 inches diameter <br />iii. Force main = 6 inches diameter <br /> <br />f. Minimum slope per table: <br />Pipe size in diameter Minimum slope <br />4 inches 0.02 (lateral) <br />8 inches 0.005 (lateral) <br />8 inches 0.003 <br />10 inches 0.0025 <br />12 inches 0.0020 <br />15 inches or larger 0.0015 <br /> <br />g. Maximum manhole spacing = 350 feet <br /> <br />h. Minimum curvature for curved sewer mains: 200 feet or not less than <br />recommended by pipe manufacturer <br /> <br />i. Minimum pipe cover = 5 feet <br /> <br />j. Peaking factor shall be Peak Wet Weather Flow divided by Average Dry Weather <br /> <br />k. flow (PF = PWWF/ADWF). Referring to the City’s Wastewater Master Plan from <br />August 2007, PF shall be the average of the three events shown on Table 4.5 <br />“Inflow and Infiltration Analysis” for each subbasin. The Basin I.D. is from Figure <br />ES-3. Minimum allowable PF = 2.0. <br /> <br />l. Backflow prevention devices must be installed if the lowest plumbing fixture if the <br />building is lower than the downstream cleanout overflow device or manhole to