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T <br /> 1. H. KLEINFELDER &ASSOCIATES <br /> to the same specifications. Plate 3 illustrates the location of the <br /> extraction and air inlet piezometers in relation to the tank excavation �? <br /> area. <br /> The wells were completed with 4-inch inside diameter, flush-threaded, <br /> schedule 40 PVC pipe. Teflon tape was used to seal all joints to reduce <br /> the potential for air leakage. Well screen sections were perforated with <br /> r <br /> 0.020-inch factory-cut slots. The screened section was set from <br /> approximately 10 to 25 feet below the # <br /> ground surface, above the ground <br /> water table; the perforated section was set above the ground water table. ; <br />' If. <br /> 3.2 PROCESS PLOW DIAGRAM <br /> The process flow diagram for the system is shown on Plate 5. A two-stage <br /> Wet seal-type vacuum pump (NASH Engineering Co., Model #467-00704-0) was ! <br /> used for extracting hydrocarbon-saturated air within the soil pores. The j <br /> performance characteristics of the vacuumum a <br /> p p re shown on Plate 6. The <br /> Pump requires 15 gallons per minute (gpm) of water flow for its liquid <br /> seal, which was continually recirculated through a vented reservoir. The <br /> suction side of the pump is connected to the vapor extraction well via a l <br /> 4-inch PVC ball valve, used for regulating the air flow. A 2-inch PVC <br /> bypass line and ball control valve have a dual purpose, namely, <br /> regulating the air flow and acting as a particulate trap. The ball <br /> control valve is used for better operational control and flexibility <br /> during startup and shutdown. The discharge side of the pump is connected I ` <br /> to a surge tank to reduce mist entrainment. The exhaust from the pump is 1 <br /> discharged to the atmosphere through a 10-foot long PVC tube. <br /> i <br /> Holes, 1/4-inch in diameter, were installed at the pump inlet and outlet, ; <br /> and approximately 16 inches above the ground surface in the standpipes on <br /> the vapor extraction well and AIPs (as shown on Plate 4). These sampling <br /> ports were used to insert an anemometer (to measure the linear velocity in <br /> the pipe), take field organic vapor and Drager tube readings, and collect <br /> air samples for chemical analysis. # <br /> I <br /> I <br /> 41-87-137 7 <br />