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Technical Report <br /> Mashpee,MA <br /> AIRUAC Estimate#2005-120 <br /> For residential areas, a single valve pit package can serve up to four properties; <br /> however,there are limited opportunities where this arrangement is possible. The <br /> most common arrangement is a single valve pit package serving two properties. <br /> To account for connections that cannot share a valve pit we typically add an <br /> additional 10%valve pits. A summary of valve pit package is shown in Table 3. <br /> Table 3—Valve it ackages and buffer tanks <br /> Vacuum system Connections Valve pit package <br /> #1 I 325 _ 179 <br /> #2 I 925 509 <br /> #3 ( 1,010 - 556 <br /> 575 316 <br /> #4 �. 347 <br /> #5 630 <br /> Total 3,465 <br /> 1,906 <br /> VACUUM SEWERS <br /> Each AIRvAc 3"interface valve is connected to the vacuum collection system by a <br /> 3" service lateral (crossover connection). Differential air pressure (7-10 psi) <br /> propels the sewage into the vacuum collection system. Turbulence disintegrates <br /> the solids and mixes them with the air and liquid to form aerobic foam, which <br /> scours the pipeline,preventing blockage. <br /> The 3° crossover connects to a branch or main line. Unlike gravity sewers that <br /> must be laid with enough slope to create a scoring velocity,the vacuum lines are <br /> only slightly sloped (0.2%) toward the vacuum station since vacuum provides <br /> adequate velocity. <br /> The vacuum mains are installed with a sawtooth profile to minimize burial depth. <br /> When the vacuum line exceeds the minimal cover by a foot or more,inserting two <br /> 45-degree fittings and a short section of pipe creates a lift back to minimum cover. <br /> Division valves are installed in the branch or main lines to allow portions of the <br /> piping system to be isolated for troubleshooting and maintenance, <br /> r <br /> i <br /> i I:WiwacEstimates\2005\05120\CAD\2005-120.dm 3 <br /> 4 <br /> i <br /> 4 <br />