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c� <br /> hydrocarbons observed ( predominantly higher-chain <br /> . hydrocarbons in the gas/diesel range) suggested the possible <br /> presence of diesel fuel or degraded gasoline in very low <br /> levels. <br /> Specific samples were re-analyzed by a second certified <br /> r� laboratory ( Sequoia Analytical ) to provide a qualitative <br /> check on the inztidl laboratory results . Although the <br /> original samples had exceeded their maximum holding time, <br /> 4� analysis would indicate the presence or absence of STEX and <br /> :'PH. Samples were continuously refrigerated from the time <br /> of collection and strict chain-of-custody procedures were <br /> F followed to minimize losses of contaminant constituents <br /> pursuant to Water4ork' s Soil Sampling Protocol (Appendix 8 ) . <br /> Confirmation sampleas were analyzed for TPH as diesel as well <br /> as HTEX and TPH as gasoline even though the contaminant is <br /> more likely degraded gasoline than diesel fuel. Considering <br /> that the Ldnks had oeen removed several years ago, absence <br /> of lower-chain gas.:)l-ne hydrocarbons due to biodegradation. <br /> 4 and iolatilizatzon ,could oe expec-�ed. Confirmation samples <br /> were consistent .ith the initial results. A summary of <br /> % oonfirmation analysis results is presented in Table 2 . <br /> Copies of laboratory data sheets are provided in appendix C. <br /> The original rationale for conducting this investigation 4as <br /> concern over the organic lead fraction of total lead <br /> F � concentrations remaining in soils after the tank was <br /> removed. Analysis of the soil• samples for organic lead indicate non-detectable concentrations of organic lead in <br /> E ` all samples analyzed. <br /> 0 CONCLUSIONS AND RECOMMENDATIONS <br /> 1 Contamination Source/Points of Discharge <br /> Laboratory analyses and field observations indicate the most <br /> likely source of contamination was overspillage and/or <br /> pining leaks. Best available information indicates that tho <br /> pumping system utilized a single pump 4ith drain-back piping <br /> 22or all three products. This could have resulted in la.mited <br /> product residence time in the piping system thereby <br /> minimizing product los- from any piping leaks. The non- <br /> commercial nature of th, former tanks resulted in relatively <br /> few tank fills over the life of the tank, as apposed to a <br /> high-volume commercial gas station, which minimized <br /> opportunities for overspill. Based on the operational <br /> na.stary and the low concentrations of contaminants detected <br /> in soils, the volume discharged was probably relatively <br /> small. <br /> 7 <br /> ,tet <br />