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p d1 a, <br /> r t <br /> PUBLIC HEALTH SERVICES <br /> SAN JOAQUIN COUNTY <br /> ENVIRONMENTAL HEALTH DIVISION rA ` <br /> Karen Furst, M.D , M,PH , Health Officer c P <br /> 304 East Weber Avenue, Third Floor • Stockton, CA 95202 <br /> 209/468-3420 <br /> PAUL SUPPLE <br /> NOV 2 1 204€ <br /> ARCO PRODUCTS COMPANY <br /> P O BOX 6549 <br /> MORAGA CA 95470 <br /> RE ARCO Station #4932 SITE CODE 1136 <br /> 16 E Harding Way <br /> Stockton CA 95204 <br /> San Joaquin County Public Health Services, Environmental Health Division (PHS/EHD) <br /> has reviewed the "Site Assessment Report"dated November 6, 2000 that was submitted <br /> by SECOR International Incorporated (SECOR) on behalf of the above referenced site <br /> and has the following comments <br /> The report details investigative site work that took place on August 21-22, 2000, when <br /> three groundwater monitoring wells, one soil vapor extraction (SVE) well, and one <br /> SVElmonitoring well were installed on site As described in the report, subsequent <br /> development and sampling of the wells took place on September 5, 2000 <br /> Results of the investigation indicate that both soil and groundwater have been <br /> significantly impacted by petroleum hydrocarbons and fuel oxygenate additives, and that <br /> the vertical and lateral extent of the impact has not been defined The highest <br /> concentrations of soil contamination appear in the area of the northern dispenser island, <br /> where analytical results from boring MW-4 had 4,190 mg/kg total petroleum <br /> hydrocarbons as gas (TPHg), 15 6 mglkg benzene and 68A mg/kg methyl tertiary butyl <br /> ether (MtBE) Water samples were collected from all five wells on site Analytical <br /> results showed contaminant impacts to each well, at quantities up to 166,000 µg14 TPHg, <br /> 10,500 pg/l benzene, 43,644 µg/l toluene, 5,230 pgfl ethylbenzene, 25,400 ugll xylene, <br /> 708,000 µg/l MtBE, 427 µg/l tertiary amyl methyl ether, 26,100 pgll tertiary butyl alcohol <br /> and 23 8 pg/I dichloroethane <br /> Routine quarterly groundwater monitoring must be initiated at this site, and must <br /> continue until directed othearwise from PHS/EHD PHS/EHD has not approved the use of <br /> a no-purge method of groundwater sampling at this site Both The California State <br /> Water Resources Control Board, as referenced in the Leaking Underground Fuel Tank <br /> (LUFT) Field Manual, and the United States Environmental Protection Agency (EPA) <br /> recommend that monitoring wells are purged until a minimum of three well volumes are <br /> removed, or until measured parameters of pH, temperature and conductivity of the <br /> discharged water stabilize to +/- 10% over two successive well volumes The next <br /> groundwater monitoring should be scheduled for early December 2000 <br /> A Division of San Joaquin CountN Hi-alth Care Services <br />