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age <br /> 1. H. KLEINFELDER & ASSOCIATES <br /> The operational procedures for the vapor extraction system are described <br /> in the following steps: <br /> k'� I <br /> o The waterline ball valve is opened and the discharge from the <br /> surge tank is monitored to make sure that a 15 gpm water flowrate <br /> is maintained through the vacuum pump. <br /> i� <br /> o Before startupof <br /> the vacuum pump, baseline ghotoionization EI <br /> detector (PTD) readings are taken at the sampling ports. j <br /> o The main control valve and the ball valve in the 2--inch bypass <br /> line are left fully open and the electrical connection to the <br /> pump is switched on. Once the air flow has stabilized (indicated <br /> by a steady reading on the pressure gauge installed on the <br /> �I <br /> suction side of vacuum pump) the bypass line is closed very <br /> r ; <br /> slowly, which creates a vacuum in the soil. Stabilization <br /> r <br /> typically takes two to three minutes. The vacuum is verified by I r <br /> the pressure gauge on the vapor e.-traction well. <br /> o During the pilot-plant study, operational parameters were ! ;, <br /> measured at each sampling port to evaluate the effectiveness of <br /> the vapor extraction system: These parameters included <br /> hydrocarbon concentration, air flow rate, and static pressure. HP, <br /> 3.3 SAMPLING AND ANALYSTS j <br /> f; <br /> f , <br /> The vapor extraction system was carefully evaluated through daily <br /> monitoring of the field parameters, including hydrocarbon concentrations <br /> in the exhaust gas using a photoionization detector. Also, periodically <br /> exhaust gas samples were collected in carbon tubes and analyzed by <br /> standard EPA procedures (Mathews at al., 1982; Holdren at al., 1986). A <br /> I ; <br /> special vapor sampling train was developed for this purpose (Plate 6). I <br /> 4 <br /> one end of a 1/4-inch Teflon tube was connected to the discharge end of j <br /> .I <br /> -- -= -- ------ <br /> ----the- vacuum---pump while--the_ather-_end-was_connected-to_activacad_-carbon--_-. <br /> beds, typically two or three connected in series. The gasoline - <br /> I; ; <br /> contaminated air was adsorbed onto Che carbon bed and clean air was then. <br /> 41-87-137 8 <br /> i. <br />