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L . <br /> The soil vapor study will consist of collecting soil gas samples from approximately <br /> 8 to 10 locations. The proposed soil gas sampling locations are shown on Figure 3. <br /> Actual sampling locations may be moved due to access restrictions, presence of utilities, <br /> and/or sample results. At each sampling location, soil gas samples will be collected at <br /> depths of 15, 30, and 45 feet bgs. The three sampling depths were selected to provide <br /> data that may eventually be used for the preliminary design of a-soil remediation system, <br /> if further remediation is deemed necessary. <br /> A direct-push hydraulic or percussion drive-"point sampling system will be <br /> employed to collect the soil vapor samples. At the prescribed interval, the drive rods will <br /> be slightly retracted to expose the slotted portion of the expendable drive-point. Tubing; <br /> lowered down the drive train as they are being advanced, will be evacuated prior to <br /> collecting the gas sample. The collected gas sample will be analyzed for BTEX using <br />• EPA Method 8020, and for TPH:using EPA Method 8015 modified. <br /> Upon completion of gas sampling, the drive train will be used to backfill-the hole <br /> with bentonite chips while the drive train is retracted from the hole. All equipment will <br /> 4 be decontaminated prior to use at the site and between each sampling location. <br /> Decontamination will consist of spraying the equipment with hot water'(steam cleaning). <br /> Water generated during decontamination will be contained within labeled 55-gallon <br /> drums. <br /> San Joaquin County files will be examined- to assess the presence of production j <br /> and other wells within 2,000 feet of the site. <br /> i <br /> A level survey will be conducted to establish an accurate top-o€-casing reference <br /> elevation for MW-4. The elevation of MW-4 will be tied into wells MW-1 and MW-2. <br /> The results of this investigation will be presented in a summary report showing the I' <br /> a <br /> distribution of aromatics and TPH in the vadose zone of the site. i <br /> - I <br /> R4182OA-1222950-5 <br /> soilvap.pin 5 <br /> j: <br />