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Technical Report <br /> Mashpee,MA <br /> AIRVAC Estimate#2005-120 <br /> FLOES <br /> Determining wastewater flow rates is a fundamental step in the conceptual design <br /> of a Vacuum collection system. Reliable data for existing and projected flow rates <br /> affect the hydraulic characteristics and sizing of the vacuum collection system <br /> components. Flow rates from residential,commercial,industrial,institutional,and <br /> recreational areas must be established before the collection system can be <br /> accurately designed. <br /> Extraneous flow into the collection system from infiltration and inflow is not <br /> included in the flow rates. BY its very nature a vacuum sewer System is tight <br /> leaving no chance of infiltration or inflow, unless a break occurs. A break or smaii <br /> leak would be detected by an increase in vacuum Pump run time and would be <br /> isolated and repaired. <br /> Flow rates have been determined by 110 gallons per capita, 4.0 persons per <br /> service connection, and a peak factor of 2.5. In order to properly size a vacuum <br /> station and collection system peak flow rates have been used. Flow rates are <br /> shown in Table 2. <br /> Table 2—Flow rate <br /> Vacuum system Connections Average daily <br /> flow <br /> w(g Peak flow(gpm) <br /> 325 <br /> 143,000 <br /> 248 <br /> #2 <br /> 9 1-1. - I ' - 25 407,000 707 <br /> #3 <br /> 1,010 <br /> #4 575' 253,000 <br /> #5 439 <br /> 630 277,200 <br /> Total 481 <br /> 1,524,600 2,64.1 7 11-1.11 <br /> Vacuum <br /> AIRVAC VALVE PIT PACKAGES AND BUFFER TANKS <br /> AIRVAC valve pit packagesto the vacuum collection system. A <br /> valve pit package includes a sump, valve pit and a 3"AIRVAC interface valve. A <br /> buffer tank is a standard concrete manhole with a sump(s)formed on the bottom <br /> and one or more AIRVAC valves mounted to the wall. <br /> A valve Pit Package is used to connect customers with a peak flow less than 3.0 <br /> 913m, typically residential and small commercial users, to the vacuum collection <br /> system. A traditional gravity line carries wastewater from the customer to a <br /> fiberglass sump usually located in the right-of-way. Connected to the top of each <br /> sump is a fiberglass valve Pit. Housed inside the valve pit is a 3"AIRVAC interface <br /> valve. The valve pit is separated from the sump by an airtight connection. When <br /> ten gallons of sewage collects in the sump,the interface valve opens and allowing <br /> the system(16"-20"Hg)to empty the sump. <br /> 1:WiwacEsfimatesk2OO51051201CADf2005-120.d. 2 <br />