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11 <br /> C <br /> Mr. Martinez Page 2 February 23 , 1989 <br /> SOIL GAS INVESTIGATION <br /> On February 14 , 1989, Mr. Calvin D. Pratt of GHH Engineering <br /> and two representatives of Tracer Research Corporation <br /> conducted a soil gas investigation at the site to determine <br /> whether hydrocarbons from the former tank farm were <br /> detectable in the soil . The work was completed in accordance <br /> with the proposal submitted to the CVRWQCB on February 3 , <br /> 1989. <br /> The soil gas investigation involved looking for vapors in <br /> shallow soil gas by pumping a small amount of soil gas out of <br /> the ground through a hollow probe driven into the ground, and <br /> analyzing the gas for the presence of volatile contaminants. <br /> The presence of contaminants in the soil gas usually means <br /> that there is contamination from the observed compound in the <br /> soil below the probe. Once in the soil gas, volatile organic <br /> compounds diffuse horizontally and vertically through the <br /> soil to the ground surface where they dissipate into the <br /> atmosphere. <br /> A total of 12 locations were sampled (SG1 thru SG12) . The <br /> soil gas samples were analyzed for Benzene, Toluene, and <br /> Xylene (BTX) , and Total Hydrocarbons (TH) . Sampling was <br /> conducted in a grid pattern in the areas of suspected <br /> contamination. Sampling locations and selected analytical <br /> results are shown on Figure 2. Soil gas samples were <br /> collected at 5 and 10 feet below the ground surface. If <br /> probe refusal or saturated soil was encountered, the sample <br /> r was collected above the refusal or saturation depth. <br /> The QA/QC analytical results from the February 14 soil gas <br /> investigation are summarized in Table 1, and the verification <br /> of the field results is contained in Appendix B. <br /> L - <br /> L <br />