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• WORK PLAN FOR CONSTRUCTION O: VAPOR RECOVERY SYSTEM WELL CONSTRUCTION Using Hogate Drilling Cots Mobile D-40L drilling rig, 10 inch hollow stem augers will be drilled through the excavation back fill and into the native soil to the 40 foot depth. A WEGE geologist will screen the cuttings and samples using a HNU PID and select samples for preservation and delivery for analysis to Chemtech Laboratories. Samples will be obtained from every five foot interval of native soil drilled at the base of the borings. Once the boring is completed the inner rod assembly will be removed from the augers and "steam cleaned" 2 inch PVC casing will be installed through the augers. The casing will be SCM 40 F480 PVC pipe, with machine slotted 0.020 inch screen. The casing will be in 10 foot threaded joints. The interval from the base of the boring (40' depth) to the 30 foot depth will have the icreen, the remaining casing to the surface will be blank. After placing the casing through the augers to the base of the excavation, #2/12 monterey sand will be used for the sand pack of the annular space of the boring. The sand will be slowly poured through the augers, as the augers are removed five feet at a time; this will insure a proper sand pack fill. The sand pack will be brought up to the fifteen foot depth and the remaining augers will then be removed. A neat cement with 5% bentonite will then be poured into the annular space of the boring to provide the sanitary seal for the well. The cement will be brought up to the one foot depth and then allowed to cure, prior to any activity concerning the well. MANIFOLDING THE VAPOR WELLS TO THE TREATMENT AREA Once the cement seal has cured in the vapor extraction wells, the wells will be manifolded to the treatment area using SCH 40 PVC pipe. The well head will be fitted with a 2 inch PVC T that will have a water-vapor tight cap. A sample port and a ball valve will be placed off of the T prior to the 2 inch manifold pipe for obtaining vacuum and temperature readings, adjusting the influence for that well and obtaining samples from the well, see Figure 7C. The 2 inch PVC pipe will connect together from the wells prior to the intake of the blower (1 horse Rotron Blower) . At the intake (vacuum side) of the blower a sample port will be installed for obtaining vacuum and temperature readings and also samples. The exhaust of the blower will be piped into 4 85 gallon activated charcoal tub scrubs placed in series. Another sample port will be placed on the exhaust of the activated charcoal drums, see Figure 7B. i `°