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RECEIVEb <br /> STi��{TUS MAY 18 2015 <br /> ENVIRONMENTAL,INC. 3330 Cameron Park Drive, Ste 550 <br /> ENVIRONMENTAL HEALTH Cameron Park, California 95682 <br /> REf4MiTlSERVICES (530)676-6004-Fax:(530)676-6005 <br /> May 12, 2015 <br /> Project No. 2129-1140-01 <br /> Mr. Gabriel Gonzalez <br /> San Joaquin County <br /> Environmental Health Department <br /> 1868 East Hazelton Avenue <br /> Stockton, California 95205 <br /> Re: Supplemental Information to Support Environmental Case Closure, Knowles <br /> Property, 7835 Thornton Road (formerly 1140 West Hammer Lane), Stockton, <br /> California <br /> Dear Mr. Gonzalez: <br /> Stratus Environmental, Inc. (Stratus) has prepared this document on behalf of the <br /> Knowles Family Trust, for the Knowles Property located at 7835 Thornton Road <br /> (formerly 1140 West Hammer Lane), Stockton, California. San Joaquin County <br /> Environmental Health Department (SJCEHD) currently regulates an environmental case <br /> at the subject property, resulting from a release of motor vehicle fuel from a former fuel <br /> storage and delivery system. In 1990, a relatively large excavation was performed in <br /> order to remove petroleum hydrocarbon mass in soil from the site. Between September <br /> 2012 and April 2015, a groundwater remediation project, using ozone injection <br /> technology, was used at the site. <br /> In a letter dated April 9, 2015, SJCEHD indicated their intention of managing the site's <br /> environmental case to closure, and directed that groundwater remedial efforts be <br /> discontinued. However, prior to proceeding to closure, the agency requested that an <br /> estimate of the contaminant mass removed during the 1990 excavation work be provided. <br /> The April 2015 letter also requested an estimation of the time needed for remaining fuel <br /> contaminant concentrations in groundwater to attenuate towards water quality goals <br /> (WQGs). Stratus has prepared this document in order to provide this information <br /> requested by SJCEHD. <br /> CONTAMINANT MASS REMOVAL BY EXCAVATION <br /> In a December 2010 Feasibility Study/Corrective Action Plan (FS/CAP), the company <br /> that prepared the report on behalf of the site (Ground Zero Analysis, Inc.) indicated that <br /> approximately 3,000 cubic yards of soil was excavated in 1990. The material was <br /> stockpiled on site, aerated, tested to verify the absence of petroleum hydrocarbons after <br /> KAKnowles-Hammer Lane\Reports\knowles-hammer-supplemental-closure-info.doc <br />