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PUBLIC HEALTH SERN,*10ES <br /> Pp U l ly <br /> �. .o <br /> SAN JOAQUIN COUNTY 2, . <br /> ENVIRONMENTAL HEALTH DIVISION :< <br /> Ernest M. Fujimoto, M. D., M.P.H., Acting Health Officer <br /> 304 E. Weber Ave., Third Floor • P. O. Box 388 • Stockton, CA 95201-0388 .'1 P <br /> 209/468-3420 <br /> BRETT HUNTER <br /> OCT 4 `lq06 <br /> ENVIRONMENTAL ENGINEERWW <br /> CHEVRON USA <br /> P 0 BOX 5004 <br /> SAN RAMON CA 94583-0804 <br /> RE: Lincoln Village Chevron Station #9-4275 SITE CODE: 1952 <br /> 2905 West Benjamin Holt <br /> Stockton CA 95207 <br /> San Joaquin County Public Health Services, Environmental Health Division (PHS/EHD) has <br /> considered your October 3, 1996 telephone request for a re-evaluation of your site based <br /> on recent "regulatory" changes. PHS/EHD has the following comments for your <br /> consideration. <br /> PHS/EHD has worked with you to maintain compliance and to avoid enforcement actions <br /> which have been warranted. The most recent PHS/EHD directive letter dated July 10, <br /> 1996 put forth the minimum requirements to avoid scheduling an administrative hearing <br /> and referenced historic compliance problems. In response, your correspondence dated July <br /> 17, 1996, included various compliance dates which Chevron established. You indicated <br /> that drilling would begin by October 4, 1996 and that interim remediation would begin by <br /> November 29, 1996. In the recent telephone request you indicated that you were thinking <br /> about doing some drilling/construction beginning November 4, 1996, but that you did not <br /> plan on implementing any remedial action for some time. <br /> This site has not undergone any remedial action besides intrinsic bioremediation which has <br /> not evidenced a reasonable reduction rate to decrease the contamination load to <br /> groundwater. Extremely contaminated soil remains in place with benzene concentrations <br /> up to 11 ppm and TPH-gas up to 2,600 ppm at 15 feet below ground surface (bgs) as <br /> evidenced during the drilling and sampling of S62 on June 20, 1994. The highest <br /> concentrations observed at approximately 14 feet bgs during the January 6, 1989 tank <br /> removals were 31 ppm benzene and 3,600 ppm TPH-gas. It must be noted that SB2 was <br /> located approximately 25 feet from the former tank pit, indicating that the existing soil <br /> contamination represents a significant source of petroleum hydrocarbon contamination to <br /> groundwater. <br /> Groundwater contamination concentrations have altered slightly most likely due to the <br /> construction of the monitoring wells and the fluctuating depth of the groundwater table <br /> (19.76 to 11 .60 feet bgs). The most recent quarterly report which PHS/EHD received, <br /> included the results for groundwater samples collected on July 24, 1996 that evidenced <br /> concentrations of benzene up to 2,300 ppb and TPH-gas up to 30,000 ppb. According to <br /> the City of Stockton, the municipal well #10 located within the groundwater contamination <br /> plume is classified as active and useable. ' <br /> A Division of San Joaquin County Health Care Services <br />