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en viroso <br />• ® Ground water samples from Well MW-4 contained 1 0 ppb benzene All other <br /> wells sampled were ND for benzene A benzene concentration map is presented on <br /> Plate 2 <br /> Quarterly Sampling <br /> Wells MW-1 through MW-5, RW-1, RW-2, VEW-1, VEW-3, and VEW-4 were sampled <br /> and analyzed for Total Purgeable Petroleum Hydrocarbons quantitated as gasoline (TPPH) <br /> according to EPA Method 8015 (Modified), and benzene, toluene, ethylbenzene, and <br /> xylenes (BTEX) and methyl-tertiary-butyl-ether (MTBE) according to EPA Method 8020 <br /> Ground water samples from Wells MW-5 and VEW-3 were also analyzed for MTBE <br /> according to EPA Method 8260 Additionally, a duplicate sample and an equipment blank <br /> were prepared and analyzed for quality control purposes <br /> Field monitoring data and chemical analytical data are summarized in Table 1 Blaine's <br /> Quarterly Ground Water Monitoring Report is presented in Appendix A <br /> Remediation System Operation <br /> The current soil vapor extraction system which utilizes activated carbon for airstream <br /> abatement was re-activated on April 18, 1996 and operated until August 21, 1996 when it <br /> was shut down with approval from the SJCPHS in a letter dated August 14, 1996 Table 2 <br /> presents operational and analytical data for the operation of the current soil vapor extraction <br /> system Plate 3 presents plots of cumulative hydrocarbon mass removed and hydrocarbon <br /> removal rate for the current soil vapor extraction system As shown on Plate 3, <br />• hydrocarbon removal rates have become asymptotic Vapor extraction system analytical <br /> reports for the third quarter of 1996 are presented in Appendix B <br /> Response to SJCPHS ]Letter Dated August 14, 1996 <br /> The letter requested that the presence of MTBE be confirmed by EPA Method 8260 <br /> analysis This analysis was performed on samples collected from Wells MW-5 and VEW- <br /> 3 Results of this analysis were 50 ppb for Well MW-5 and 4 ppb for Well VEW 3 <br /> Shell was also requested to collect ground water samples from the four soil vapor <br /> extraction wells this quarter Samples were collected from three of the four wells, the <br /> fourth well was dry Analysis was ND for TPPH and BTEX compounds <br /> For your information, the attached Table 3 presents well screen interval data for the site <br /> (Logs for Wells MW-4 and MW-5, and VEW 1 -4 were not available in Enviros files ) <br /> Enviros will contact SJCPHS after submittal of this report to discuss the planned submittal <br /> of a request for closure during November 1996 <br /> 96369 2 <br />