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16 <br /> 3.3.3 Laboratory Analysis of Ground Water Samples <br /> All ground water samples collected for analysis were stored in a cooler chilled to 4° <br /> Celsius and shipped under strict chain of custody protocol to the analytical laboratory <br /> The samples were analyzed in Modesto, California by GeoAnalytical Laboratories, a <br /> Califorma State certified analytical laboratory for the following constituents <br /> ' • TPH - gasoline, Method 5030/LUFT <br /> detection limit 0 05 mg/L <br /> ' • Benzene, Toluene, Ethyl Benzene and Total Xylenes (BTEX), MTBE, EPA Method <br /> 602 <br /> 1 detection limits 0 3 gg/L BTE, 0 6 µg/L X, 1 0 µg/L MTBE <br /> ' 4.0 AQUIFER TESTING <br /> The work plan for the site called for pump or slug tests to be carried out at the site <br /> However, the San Joaquin County Environmental Health Division advised that a pump <br /> and treat groundwater remediation alternative was not to be considered for this site and <br /> that soil vapor extraction was to be evaluated Consequently, the resources which were <br /> originally specified for the aquifer test were diverted to soil vapor extraction testing <br /> 1 5.0 SOIL VAPOR EXTRACTION TESTING <br /> On June 19, 1996 AGS performed a soil vapor extraction test at the site Monitoring well <br /> ' MW-1 was selected as the point from which to apply a vacuum because of its proximity <br /> to the area most likely to be remediated using this methodology A regenerative blower <br /> with a rated capacity of approximately 110 cubic feet per minute was utilized to produce <br /> ' and maintain the vacuum at the well head The maximum vacuum rating for the blower <br /> is approximately 85 inches of water <br /> ' Monitoring wells MW-6, MW-7, and MW-8 were selected as observation wells to test for <br /> pressure changes over time Each observation well was fitted with a 2 inch cap that had a <br /> sample port at the top The caps were secured to the well casing to minimize vacuum loss <br /> that might affect readings <br /> II <br /> Readings were collected from each of the three observation wells and MW-1 to determine <br /> whether a vacuum gradient was being generated that could be measured at the <br /> American Geological Services, Inc. <br />'1 CA95DE-029 <br /> r <br /> 9 <br />