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Happy Valley Water & Sewer Study <br />Technical Memorandum <br />Table 4: Sewer System Siting and Sizing Evaluation Criteria <br />Cgeggry <br />Pipe Material for new Sewer Mains <br />PVC <br />Minimum cover' <br />5 feet <br />Maximum distance between manholes' <br />.• <br />Minimum pipe size' <br />350 feet <br />8 -inch diameter <br />Maximum d /D' <br />0.75 <br />Minimum Slope' <br />8" 0.003 ft/ft <br />10" 0.0025 ft/ft <br />Minimum Velocity' <br />2 feet per second <br />Maximum Velocity' <br />10 feet per second <br />Mannin 's'n' for qravijX sewersz <br />0.013 <br />Pump-Station Criteria <br />Minimum force main pipe size 7777 <br />6" <br />Maximum Velocity3 <br />5 feet per second <br />Pump Configuration 1 du +1 standby <br />Pump Effcienc 3 70% <br />Hazen Williams'C' for new and existing force <br />mains3 100 <br />Residential ADWF4 <br />220 gpd per dwelling unit <br />equivalent <br />Golf Course ADWF4 <br />35,561 gpd <br />PWWF /ADWF Peaking Factors <br />3.2 <br />Footnotes: <br />I. Per 1984 Design Standards <br />2. Per 2007 Wastewater Master Plan <br />3. Typical values used for similar systems <br />4. Residential and Golf Course ADWF are based on calibrated values used in the 2007 Wastewater Collection <br />System Master Plan. The 1984 Design standards assume a flowrate of 320 gpd per Dwelling Unit and a peaking <br />factor of 2.0. <br />5. Peaking factor is based on the PW W F /ADWF ratio for the entire system repotted in'I'able 6.2 of the 2007 <br />Wastewater Collection System Master Plan. Note that this peaking factor is more conservative than the peaking <br />factor of 2.0 used in the 1984 Design Guidelines, but is not based on location specific int iltration and inflow <br />factors. A calibrated dynamic model may indicate a higher or lower peaking factor should be used. <br />4.2 Sewer System Evaluation Results <br />Proposed improvements to the sewer system are shown in Figure 6. <br />Gravity Sewers <br />A steady state model was developed to evaluate the capacity of existing and proposed gravity sewers. The <br />modeling software used for the study was InfoWorks CSTv` by Innovyze; although Info Works uses a fully - <br />dynamic hydraulic model engine, only fixed flow rates were evaluated. Per unit flowrates were based on <br />average dry weather flowrates (ADWF) and peaking factors summarized in Table 4. Flows generated by <br />November 2016 13 <br />