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Third Quarter 2001 Monitoring and Sampling Report 2 <br /> 7-Eleven Inc Store#14117 2725 Country Club Boulevard,Stockton CA October 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 were <br /> then sealed using Teflon septum caps, labeled with the fob Identification number,the sample number,date, <br /> time, and type of laboratory analysis required The samples were stored on Ice and transported with a <br /> chain-of-custody record to a state-certified laboratory for analysis The groundwater samples were <br /> analyzed for BTEX, MTBE and TPH-G using Environmental Protection Agency(EPA) methods <br /> 8021 B/modified 8015, and for oxygenates MTBE,TBA, DIPS, ETBE, and TAME using EPA method 8260B <br /> ' The analytical results for groundwater samples are summarized in Table 1 Dissolved benzene,TPH-G, <br /> and MTBE concentrations ranged up to 650 micrograms per liter (pg/L), 5,100 gg/L and 36,000 gg/L, <br /> respectively Highest MTBE levels were reported In well MW-2 located In the underground storage tank pat <br /> (UST) area,whereas highest benzene concentrations were detected In well MW-4 located crossgradient <br /> next to the UST area The laboratory analytical reports for the groundwater samples are included in <br /> Attachment 4 Dissolved oxygen data taken from the monitoring wells indicate generally anaerobic <br /> conditions,with dissolved oxygen levels at or near 1 milligrams per liter (mg/L) (Table 1) <br /> There are no known public water supply wells located within one mile downgradient or crossgradient 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 /> 1 <br /> 1 <br /> 14117012 RPT <br /> ti <br />