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28 January 1993 <br />(GeoAudit CV43F1-1.35) <br />Page 4 of 5 <br />FINDINGS <br />The generalized stratigraphic sequence in the boring consisted of <br />alternating layers of sandy silt, silty sand and silt/clay <br />mixtures. The depth to groundwater in the well, as measured on 8 <br />January 1993, was 91.90 feet. <br />Organic vapors were detected only in soil sample 33-90, at 13 parts <br />per million (see attached boring logs). No hydrocarbon odor was <br />noticed in the water sample. <br />Four soil samples from MW-2 were analyzed. No hydrocarbon <br />contamination was detected in any of the four soil samples. Total_ <br />lead was detected in three of the four soil samples at levels <br />ranging from 5.5 ppm to 8.5 ppm. Table 2 summarizes the laboratory <br />results. The laboratory report and chain of custody for the soil <br />samples are included in appendix A. <br />The water sample from MW-2 was analyzed according to EPA method <br />8015, and total petroleum hydrocarbons in the gasoline range (TPH- <br />g) were detected at a concentration of 83 Ag/L (ppb). Analysis <br />according to method 8020 detected benzene at a concentration of 1.0 <br />ppb, but no toluene, ethylbenzene or xylenes were detected. <br />However, an unknown hydrocarbon with a boiling point intermediate <br />between that of benzene and toluene was detected in the sample (see <br />chromatogram of the 8020 analysis). The hydrocarbon was suspected <br />to be a halogenated solvent. Therefore, the sample was analyzed for <br />halogenated volatile organic compounds (HVOC's) by EPA 601. Eight <br />of the 28 target analytes were detected in the water sample. These <br />individual constituents included 1,1-Dichloroethene (120 ppb), 1,1,1-Trichloroethane (16 ppb) and Trichloroethene (36 ppb). The <br />sum of these concentrations exceeds the 83 ppb TPH-g that were <br />detected in method 8015, which indicates that all of the TPH-g can <br />be accounted for by the concentrations of HVOC's. As reported by <br />WEST laboratories in the accompanying letter, the TPH is not <br />typical gasoline, and is probably the halogenated hydrocarbons. The <br />laboratory reports and chains of custody are included in Appendix <br />B. <br />CONCLUSION AND RECOMMENDATIONS <br />No contamination was detected in soil samples collected from the <br />monitoring well drilled during this phase of investigation. There <br />is no evidence of vadose zone contamination in the vicinity of the <br />boring, indicating that MW-2 is located beyond the margin of the <br />soil contamination plume.