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4 l <br /> Fourth Quarter 2000 Monitoring and Sampling Report 2 <br /> 7-Eleven,Inc,Store#14117,2725 Country Club Boulevard, Stockton,CA January 15,2001 <br /> Monitoring Well Sampling and Analytical Results <br /> Before sampling, at least four well-casing volumes of water was removed from each well The <br /> groundwater samples were collected using disposable bailers Groundwater samples were placed In 40- <br /> milliliter glass vials, which were acidified with hydrochloric acid to preserve the samples The samples <br /> were then sealed using Teflon septum caps, labeled with the fob Identification number, the sample <br /> number, date, time, and type of laboratory analysis required The samples were stored on ice and <br /> transported with a chain-of-custody record to a state-certified laboratory for analysts The groundwater <br /> samples were analyzed for BTEX, MTBE and TPH-G using Environmental Protection Agency (EPA) <br /> methods 8021 B/modified 8015, and for oxygenates MTBE, TBA, DIPE, ETBE, and TAME using EPA <br /> method 8260B <br /> The analytical results for groundwater samples are summarized in Table 1 Dissolved benzene, MTBE <br /> and TPH-G concentrations ranged up to 360 micrograms per liter (pg/L), 9,800 pg/L and 4,700 pg/L, <br /> respectively Highest MTBE levels were reported in well MW-2 located in the underground storage tank <br /> pit (UST) area, whereas highest benzene concentrations were detected In well MW-3 located <br /> downgradient from the pump Island The laboratory analytical reports for the groundwater samples are <br /> Included in Attachment 4 Dissolved oxygen data taken from the monitoring wells indicate generally <br /> anaerobic conditions, with dissolved oxygen levels of about 0 5 milligrams per liter (mg/L) (Table 1) <br /> i <br /> There are no known public water supply wells located within one mile downgradient or crossgradlent from <br /> the site <br /> Purge Water Transportation and Disposal <br /> All purge water generated during this quarterly monitoring and sampling event was stored in 55-gallon <br /> Department of Transportation (DOT)-approved drums pending characterization and proper disposal <br /> Waste disposal documentation will be forwarded once received <br /> 14117040 RPT <br />