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groundwater in the west-central and northwest portion of the site. The on-site USTs are the <br /> likely source of gasoline and diesel compounds detected in the southern portion of the site. <br /> Diesel compounds did not exceed ESLs, although gasoline constituents were present in <br /> excess of ESLs and at sufficient concentrations such that free product may be present in <br /> groundwater in the southern portion of the site. Semi-volatile organic compounds were <br /> also present in groundwater samples collected from all locations at concentrations <br /> exceeding ESLs, although the source for these compounds has not been determined at this <br /> time. Certain metals were detected at concentrations that exceed ESLs in groundwater at <br /> four(4) sample locations; one (1) in the northwest corner and three (3)in the southern <br /> portion of the site. Based on these findings,ROKEN recommended removal of the USTs <br /> and development of a workplan to further characterize the nature and extent of soil and <br /> groundwater contamination at the site. <br /> Based on the results of these investigations and in anticipation of applicable regulatory <br /> requirements including requirements for the potential residential_site development, ROKEN <br /> prepared this Draft Workplan for UST Removal and interim remedial action,and also presents <br /> recommendations for additional remedial investigation. <br /> 5.0 UNDERGROUND STORAGE TANK REMOVAL <br /> At least four(4)underground storage tanks have been identified in the southwest corner of the <br /> site. One or more of these USTs has released petroleum product which has significantly <br /> impacted on-site soil and groundwater. The soil and/or groundwater impacts may extend off-site <br /> as well. Petroleum products, metals, and other contaminates have been detected in other areas of <br /> the site. Petroleum products detected in groundwater in the west-central and northwest portion <br /> of the site may be the results of an up-gradient, off-site release presumably at Quik-N-Save, <br /> which is currently under investigation by the SJCEHD. Removal of these USTs and surrounding <br /> contaminated soil, and discussion of further remedial investigation to determine the nature and <br /> extent of environmental conditions throughout the site is the subject of this workplan. <br /> The environmental conditions at the site have not been fully characterized. Additional <br /> investigation will be necessary to determine the nature and extent of contamination. However, <br /> based on existing information the interim remedial action focused on the USTs should <br /> significantly improve the site conditions and provide economic benefit for additional remedial <br /> action, if required. Interim remedial action can be accomplished by UST removal, soil <br /> excavation, limited free-product removal, disposal of soil and groundwater and periodic <br /> groundwater monitoring. <br /> 5.1 PROJECT PLANNING <br /> ROKEN will facilitate the necessary regulatory notifications and submittal of an unauthorized <br /> release report. A workplan based on this draft will be submitted as part of the UST removal <br /> permit requirements. Prior to conducting UST removal and soil excavation activities the <br /> following activities will be conducted: <br /> Conduct a pre-project site visit with the Contractor to inspect site conditions and plan work <br /> 5 <br />