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Chevron <br /> t_ Chevron <br /> Chevron Products Company <br /> November 20, 1998 6001 Bollinger Canyon Road <br /> Buildino L <br /> San Ramon,CA 94583 <br /> P.O.Box 6004 <br /> Mr.Ron Rowe San Ramon,CA 94583-0904 <br /> San Joaquin County Public.Health Services Marketing—Sales West <br /> Environmental Health Division Phone 5k0 842-9500 <br /> 304 E. Weber Ave.,Third Floor ATS <br /> Stockton,CA 95202 <br /> Re: Former Chevron Station_#97-6258,2409 E.Main St Stockton CA <br /> Dear Mr.Rowe: . <br /> I would like to acknowledge receipt of your correspondence dated November 2, 1998;sent by facsimile, . <br /> approving Secor's October 28, 1998 work plan for the,subject site. Thank you for your quick reply. The <br /> work plan was approved with the following conditions:.at least two of the three proposed borings must be <br /> continuously cored and logged; sample analyses must include MtBE, TAME,DIPE,and ETBE;and <br /> hydrogeologic cross sections must be provided. <br /> Chevron requests that the three conditions for work plan.approval be removed.The imposed conditions <br /> represent extensive and costly efforts that are not warranted given what is currently known about the site. <br /> The gasoline UST's were removed and all fueling operationsceased in 1976. This was approximately three <br /> years before the earliest reported use of MtBE(and other ether compounds)in gasoline.There have been no <br /> detections of MtBE at the subject site.or uncategorized compounds reported by the laboratory.The <br /> contaminant of concern has been described as-weathered'gasoline by the laboratory and the absence.of <br /> benzene in all samples confirms this. The site-specific data suggests a release of gasoline occurred prior to <br /> 1976.The release appears to be limited to the southeast portion of the former UST complex and.the extent . <br /> in soil has been defined laterally and vertically. Groundwater impacted ted by weathered gasoline was detected <br /> at 58 feet logs. <br /> Chevron agrees that the extent of the weathered gasoline plume ingroundwaterneeds to be further defined. <br /> However,the inferred age of the gasoline release and the expected absence of ether Compounds and other <br /> oxygenates makes it unnecessary to analyze for them.The fate and transport characteristics of a weathered <br /> gasoline plume without oxygenates are:well understood and a limited migration distance can be assumed. <br /> As such;the role of preferential migration pathways becomes less significant asdoes the need to.investigate <br /> them through continuous coring and cross section mapping. Chevron proposes that the work plan be <br /> immediately implemented without the three conditions.If MtBE'is detected(and confirmed)during the <br /> normal course of the investigation,Chevron will analyze groundwater for the other three ether compounds <br /> and consider the need for further,more extensive investigation during a separate phase of investigation. <br /> With your concurrence,Chevron and Secor will proceed immediately with the proposed investigation.If <br /> you have any questions or comments,please contact in directly at(925)842-8695. <br /> R nyded <br /> ReoyclaUe <br />