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44.0 <br /> 4.2 Laboratory Results <br /> Three of the five soil samples were analyzed for total petroleum <br /> hydrocarbons (TPH as gasoline and diesel) , purgeable aromatics <br /> (BTE&X) and total lead in accordance with EPA methods 8015 <br /> modified, 8020 and 7421, respectively. TPH as gasoline, TPH as <br /> diesel, and BTE&X were not detected in any of the soil samples. TPH <br /> as motor oil was detected in the 30 foot sample. <br /> The detection of hydrocarbons with a molecular weight higher than <br /> diesel appeared to be anomalous, particularly in light of the fact <br /> that no hydrocarbons were detected in any other sample. Laboratory <br /> error was suspected, and the sample was re-analyzed on July 9, 1993 <br /> at GeoAudit' s request. No hydrocarbons were detected in the re- <br /> analysis. <br /> Total lead was detected in samples B1-20, B1-25 and B1-30 at levels <br /> of 8 . 5 mg/kg, 6. 8 mg/kg and 6. 4 mg/kg respectively. These <br /> concentrations are characteristic of background levels in San <br /> Joaquin County. No other constituents were detected in any other <br /> soil samples. The analytical results are summarized in Table 1. The <br /> laboratory report and chain of custody are attached in Appendix A. <br /> 5. 0 CONCLUSIONS & RECOMMENDATIONS <br /> The boring was installed near the location of the highest <br /> contamination reported at the time of the tank removal. If <br /> contamination were present, it should have been detected in the <br /> boring. Analytical results for the soil samples collected during <br /> this investigation indicate that the soil contamination associated <br /> with the former underground storage tank has not migrated <br /> vertically. <br /> The second analysis of sample B1-30 did not detect motor oil. <br /> GeoAudit believes that the motor oil originally detected in sample <br /> B1-30 was due to laboratory error. <br /> Contamination originally present beneath the UST's has dissipated, <br /> perhaps through natural degradation processes. Since no <br /> contamination was detected during this investigation, GeoAudit <br /> recommends that this site be approved for closure. <br /> 6. 0 LIMITATIONS <br /> Our professional services were performed using that degree of care <br /> and skill ordinarily exercised by environmental consultants <br /> practicing in this or similar localities. The findings were mainly <br /> based on analytical results provided by an independent laboratory. <br /> No other warranty, expressed or implied, is made as to the <br /> professional recommendations contained in this report. <br /> 3 <br />