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Work Plan for Environmental Investigation June 21, 1989 <br /> Waterfront Redevelopment, Stockton, California AGS 39048-1W <br /> lowered through the hollow center of the probe rod to collect a <br /> sample. After allowing sufficient time for collection, the <br /> sample assembly is withdrawn from the probe rod. The sample vial <br /> is removed from the sampling assembly, and a gas sample is <br /> withdrawn with a syringe and injected into the Photovac 10S70 <br /> portable gas chromatograph. This procedure can be repeated at <br /> multiple depth points at each sampling location. <br /> Sampling locations are placed in an appropriate grid pattern on <br /> the surface with spacings that allow data to be reasonably <br /> interpreted. Alternatively, locations are selected based on <br /> available information relating to plume migration. Initial <br /> samples are generally collected at the perimeter of the property; <br /> subsequent locations are chosen based on the results of earlier <br /> sample analysis. Analytical results are evaluated at the time of <br /> collection with computer assistance to allow field interpretation <br /> and decisions for locating subsequent sampling points. This <br /> real-time analytical procedure significantly improves the <br /> efficiency and cost-effectiveness of the investigation. An <br /> automatic level is used to survey probe-hole locations relative <br /> to an arbitrary survey station and other facilities or features <br /> at the site. The probe holes will be backfilled with neat cement <br /> to within a few inches of the ground surface and then topped off <br /> 10 <br /> Applied GeoSystems <br />