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Ms. Mary Meays <br /> September 29, 1995 (9347-3011) <br /> 6. The remaining concentrations of dissolved- and adsorbed-phase petroleum hydrocarbons <br /> will be effectively addressed using GWO. The GWO system has increased the dissolved <br /> oxygen content of ground water, as shown on Table 4, and will continue to enhance the <br /> natural biodegredation of the remaining dissolved- and adsorbed-phase petroleum <br /> hydrocarbons. <br /> 7. Since the site is covered with asphalt and the shallow water-bearing zone is not currently <br /> used for domestic consumption, the soil and ground water conditions at the site do not <br /> pose an existing threat to public health. <br /> 8. The VES and ground water recovery systems can be more effectively used at another site. <br /> 9. The removal of the VES/ground water recovery system and continued operation of the <br /> GWO system is compatible with development of the property. <br /> 10. Wells MW-1, MW-2, MW-4, MW-5, and RW-1 are consistently below the respective <br /> method detection limits for all petroleum hydrocarbons, or contain only low <br /> concentrations. <br /> 11. TPH-G was only detected in the soil samples collected from confirmation soil borings <br /> CB9 and CB9 drilled in September 1992. Benzene was not detected above reported <br /> laboratory detection limits in any of the samples collected and analyzed from the nine <br /> additional borings. <br /> On the basis of the above information, Fugro and Shell request the following: <br /> ■ The concurrence of the SJCPHS/EHD to shut down the VES and ground water recovery <br /> system but continue with GWO system in wells MW-3, MW-4, and RW-2. <br /> ■ The concurrence of the SJCPHS/EHD to reduce the sampling frequency of the wells <br /> indicated in item 10 above to a semi-annual basis (ground water sampling of wells MW-3, <br /> MW-4, and RW-2 and dissolved oxygen measurements in all wells will be performed <br /> each quarter). Quarterly status and ground water reporting will continue. The results of <br /> the monitoring and sampling will be periodically evaluated to determine the effectiveness <br /> of the ongoing active and passive remediation. <br /> ■ The concurrence of the SJCPHS/EHD that the property is suitable for development, <br /> provided there is no hindrance to monitoring, sampling, or remediation. <br /> 93473011.ARP -6- <br />