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Project Michael Infurna No. 232• <br /> September 16, 1996 <br /> Page 2 <br /> Vapor Extraction Pilot Study <br /> To address County Health's concern for performing vapor extraction at deeper depths, well <br /> VEW-113 well be screened from 25 feet bgs to a foot above the existing ground water elevation <br /> (see Work Plan, Figure 10). <br /> In response to County Health's question regarding the impact of the concrete UST pad around <br /> existing well MW-1 and proposed well VEW-1B on vapor extraction performance, this wi 1 be <br /> evaluated during the pilot study. Based on our experience at similar sites, the additional cover <br /> provided by the concrete pad will actually help to increase the radius of influence around <br /> VEW-lA and to a lessor extent around VEW-113. <br /> Remedial Alternatives Evaluation <br /> Please keep in mind that the Work Plan is not a Feasibility Study nor a Corrective ActionIan <br /> (CAP). Once the vapor extraction pilot study has been completed, the information necessary <br /> to evaluate this option as a possible remedial measure will be available. At that time, an <br /> evaluation (Feasibility Study) of at least two remedial alternatives will be prepared and <br /> submitted to County Health. <br /> Ground Water Remediation <br /> If necessary, Montgomery Ward will remediate ground water contamination that it caused, <br /> i.e., assuming that the contaminants are at concentrations that require remediation. However, <br /> currently available information indicates that releases from a former Unocal service statin at <br /> 5606 Pacific Avenue have and continues to impact ground water beneath the Montgomery <br /> Ward site. Therefore, it is Montgomery Ward's opinion that any ground water remediation <br /> efforts, should they be necessary, must be addressed jointly by Montgomery Ward and <br /> Unocal. It makes no sense for Montgomery Ward to initiate ground water remediation a orts <br /> if ground water remediation at the former Unocal site is not occurring. <br /> County Health has indicated that it may not approve a CAP which does not have <br /> recommendations for ground water remediation. It is our opinion that cleanup of the site in <br /> phases, e.g., soil first then ground water, is an acceptable remedial strategy. This strateD,,y is <br /> further supported by the current trend that the State Water Resources Control Board is <br /> pursuing of relaxing soil and ground water cleanup levels. <br /> Reporting <br /> Soil contamination data will be reported in parts per million and ground water data will be <br /> reported in parts per billion. All future cross-sections will depict vertical depths in feet below <br /> ground surface instead of feet below mean sea level. <br /> ENVIRONM AL AUDIT INC.® <br />