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RESULTS OF LABORATORY ANALYSES <br /> Water samples collected from each well were analyzed for TPHg, TPHd, and BTEX using <br /> modified EPA methods 8015/8020 These results and cumulative results of laboratory analyses <br /> are summarized in Table 1 The Chain of Custody Record and laboratory analytical reports are <br /> included in Appendix B <br /> Results of this quarter's laboratory analyses of water samples from wells MW-1, MW-2, MW-3, <br /> 1 MW-4, MW-5 and MW-6 indicate the following <br /> • Concentrations of BTEX, TPHg, and TPHd were nondetectable in all wells <br /> 1 <br /> CONCLUSIONS <br /> Based on the results of this quarterly monitoring and previous work performed at the site, <br /> SMTH concludes that the TPHg, TPHd, and BTEX concentrations in groundwater have <br /> remained nondetectable, consistent with the last monitoring episode in December 1994. <br /> Since monitoring was reinitiated in December 1992 the concentrations of TPHd, TPHg, and <br /> BTEX have steadily decreased to nondetectable levels and no longer appear to be impacted by <br /> petroleum hydrocarbons in soil beneath the site. This is a result of the continued operation of <br /> the soil vapor extraction system which began operating in July 1993 The vapor extraction <br /> system has removed over 3,700 pounds of a total estimated 3,900 pounds of petroleum <br /> hydrocarbons from soil beneath the site (RESNA, March 1993) The system is currently <br /> extracting less than three pounds per day of TPHg and BTEX and has been effective in removing <br /> ' almost 95% of petroleum hydrocarbons from soil beneath the site (Table 3). <br /> RECOMMENDATIONS <br /> Based upon the findings and conclusions of this and previous groundwater monitoring episodes, <br /> SMTH recommends that soil confirmation borings be advanced and soil samples be collected for <br /> laboratory analysis. <br /> ' SCHEDULE <br /> A work plan for advancing confirmation soil bonngs will be submitted to SJCPHS in May The <br /> 1 field work will be performed and a closure report will be prepared Upon case closure by <br /> SJCPHS, groundwater monitoring will be discontinued, the appropriate well destruction permits <br /> will be obtained, and the wells will be abandoned. <br /> 54W561QUARTLY11QMR1995 FNL 3 <br /> 1 <br />