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ARCO -4- April 14, 2011 <br /> Claim No. 15783 <br /> VII. COMMENTS AND JUSTIFICATION FOR RECOMMENDED ACTION <br /> A. Site Description: active retail gasoline station <br /> B. Site History: the extent of groundwater contamination is defined <br /> C. Groundwater Monitoring Summary: strong monitoring history <br /> D. Remediation Summary: ozone injection, delayed, pilot test approved <br /> E. Contaminant Exposure Pathway Evaluation: unknown <br /> F. Recommendation: <br /> In April 2008, the Fund recommends that the San Joaquin County LOP should <br /> direct the Responsible Party to assess remedial technologies to achieve Water <br /> Quality Objectives more rapidly. The Fund will review this site next year to track <br /> progress. <br /> UPDATED, April 2009, the San Joaquin County LOP has directed the <br /> Responsible Party to conduct ozone injection. The Fund concurs and will review <br /> this site next year to track progress. <br /> UPDATED, April 2010, the Fund recommends that the San Joaquin County LOP <br /> transfer regulatory responsibility of this site to the Regional Board for <br /> enforcement. The approved remediation should begin without delay. The Fund <br /> will review this site next year to track progress. <br /> UPDATED, April 2011, current groundwater trends suggest Water Quality <br /> Objectives will be achieved without active remediation. Monitoring well MW-1 <br /> screened in the source area has consistently had elevated.concentrations of <br /> residual fuel oxygenates in groundwater. However, after 10 years of monitoring, <br /> the groundwater plume is largely limited to the source area and groundwater <br /> concentrations are abating rapidly. The Fund recommends that the San Joaquin <br /> County LOP review this site for closure. <br /> -Zi2111' <br /> Kir Larson, P.G. Date Robert Trommer, C.H.G. Date <br /> Engineering Geologist Senior Engineering Geologist <br /> Technical Review Unit Chief, Technical Review Unit <br /> (916) 341-5663 (916) 341-5684 <br /> California En vironmental Protection Agency <br /> P.a Recycled Paper <br />