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wag <br /> EAWMI[fi Nianal Operauaes <br /> EA Engineering.Science,and TechnolagY 41 Lalayene Circle <br /> Lafayette,CA 94549 <br /> Telephone:416-283-7077 <br /> Fax:416-283-3894 <br /> r 30 October 1990 <br /> Lisa Backlund <br /> Chevron U.S.A.Inc. <br /> P.O.Box 5004 <br /> 2410 Camino Ramon <br /> San Ramon,California 94583-0804 <br /> RE: Site Code 1138 <br /> Groundwater/Soil Remediation,at Former <br /> Chevron Station <br /> 45 East Harding Way, <br /> Dear Ms.Backlund: <br /> Please review this nty <br /> explanation to the letter dated encedpsite clean I andtember 1990minvestigadonSan naddressed <br /> Public Health Services,regarding the above-referenced groundwater <br /> oundwater table <br /> to Chevron Veli n El Dorado Street that islheavily trafficked.arid because the grents to install easerna <br /> monitoring re pared a work plan that differs <br /> has been steadily declining since the wells were installed,EA p PJanuary 1989. The work t <br /> from the work plan submitted to San Joaquin Public <br /> to install Health <br /> deeper omtori 9 wells on the <br /> plan authored in March 1990 includes a propund to have <br /> 1 <br /> site and-two wells off the site if a fram abovater e EA recommends beneath <br /> ds that the work plan,if it <br /> been impacted by petroleum hydrocarbons <br /> meets your approval,be submitted to Public Health Services of San Joaquin County for app <br /> wel <br /> s were <br /> The work plan proposes further investigation ttom cand groundwater <br /> becausg them usee all less <br /> monitoring or <br /> dry or contained only residual water in the P surnmary report on groundwater <br /> extraction wells. As you can see in tali attached <br /> ewdent dry betty n March and July 1989,except st <br /> monitoring(up to September 1990), <br /> MW2,which was sampled until March 1990. MW2 has since(June 1990)gone dry' <br /> recent gauging on 18 September 1990 found all monitoring wells to be roved in <br /> Meanwhile,a soil remediation system has been in-- 'led according to a work plan din wells <br /> the Spring of 1990. The system <br /> assoiloriginally <br /> extractionosud hwelas ls(se Fiimodguree 3 ed of the quarterly re- <br /> M�y3,MW4,MWS,and M groundwater monitoring wells MW3-6 have been <br /> port). The five vapor extraction wells and at <br /> plumbed to the system,and extraction/treatural t as supply and electricalment have whichhich willbehooked- <br /> last parts of the system,a high pressure g <br /> up to the system during the week of 22 October. System start-up is planned for the week o <br /> 29 October 1990. <br /> flans to remediate groundwater cannot bs downoto seced ondary grounder until water levels er waters is assessed. If <br /> and migration of petroleum hydrocarbon <br /> EA:s March 1990 work plan is implemented and groundwater is found is contain ons will be <br /> -__..—.-.hydrocarbons,a.work plan adequate to cover encountered hy�g <br /> P ,-..-- proposed oundwatcr-monitoring wells are described <br /> - -- -------- ----------- <br /> developed. Locations and construction o p P - --- ---- - <br /> in the work plan. A copy of the work plan is attached to facilitate your review and comman- <br /> i <br /> t <br />