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0 <br />• <br /> detected traces of VOCs at five feet below the surface. At 10 feet <br /> below the surface and within native soil , the OVA detected 15 ppm of <br /> VOCs, and a moderately strong diesel odor was present. The OVA detected <br /> 39 ppm at 15 feet, 50 ppm at 20 feet, 0.5 ppm at 25 feet, and 22 ppm at <br /> 30 feet below the surface in borehole BHI . A diesel odor was present at <br /> each of those levels, although the odor at 30 feet was not a <br /> characteristic diesel odor. Due to the levels of contamination <br /> encountered, borehole BH1 was extended to 40 feet below the surface. No <br /> indication of soil contamination was detected in the field below the <br /> 30 foot level . Soil samples from 20, 30, and 40 feet below the surface <br /> in BH1 were selected for laboratory analyses. The borehole drilling <br /> logs are included as Appendix C. <br /> The six soil samples were analyzed for TPH by EPA Method 8015M using <br /> a gas chromatograph-flame ionization detector (GC-FID) and for BTEX by <br /> EPA Method 602 by Chemwest Analytical Laboratory, Inc. The chain of <br /> custody form and the laboratory analytical results are included as <br /> Appendix D and are summarized in Table 4-1 . The QA/QC Program for <br /> Chemwest Analytical Laboratory, Inc. , is included in Appendix E. <br /> Peripheral borehole samples B3-15 and B4-15 were found to contain <br /> low levels of BTEX while B5-15 was below the reporting limit (BRL) . The <br /> analyses for TPH detected levels of 110 mg/kg in sample B4-15 and 150 <br /> mg/kg in B5-15 while B3-15 was BRL. It is unusual that B3-15 contained <br /> 8. 11 mg/kg total BTEX while it contained no TPH as diesel fuel . <br /> Furthermore, the ratios of total BTEX to TPH as diesel fuel in all of <br /> the samples are unusually high for diesel fuel contamination. The <br /> laboratory representative reported that the analytical data from EPA <br /> Method 8020 indicates that a purgeable hydrocarbon mixture, either <br /> gasoline or a solvent, is present in the soil . Borehole sample B3-15 <br /> contains 68 mg/kg of the purgeable hydrocarbon mixture when it is <br /> quantified to gasoline. Hydrocarbon contamination in the soil samples <br /> from borehole BHI was found to be significantly higher. Sample B1-20 <br /> 9 <br />