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r <br /> Mr Michael Infurna <br /> Page 2 <br /> Samples were collected after parameter stabilization, and appropriate water level recovery Purge <br /> water was contained in properly labeled DOT-approved 55-gallon drums The drums are currently <br /> being stored onsite Purge logs are included in Attachment A <br /> Groundwater samples were delivered under chain of custody protocol to Argon Laboratories (ELAP <br /> #2359) Analysis consisted of TPHg and TPHd using modified EPA method 801513, gasoline <br /> oxygenate additives, ethylenedibromide (EDB) and 1,2-dichloroethane (1,2-DCA) using EPA <br /> method 826013, and BTEX using EPA method 8021 B <br /> Groundwater Analytical Results <br /> EDB and 1,2-DCA were not detected in any site well BTEX, TPHg, TPHd and gasoline <br /> oxygenates were not detected in wells MW1, MW2, MW4 and MW5 <br /> In well MW3, TPHg was detected at a concentration of 1,100 parts per billion (ppb) TPHd was <br /> detected at a concentration of 280 ppb Methyl-tent-butyl ether (MTBE) was detected at a <br /> concentration of 1,600 ppb No BTEX compounds were detected Analytical results are <br /> summarized in Table 2 Attachment B contains laboratory reports and chain of custody <br /> documentation Graphs of TPHg, TPHd and MTBE concentrations over time in MW3 are included <br /> in Attachment C <br /> • Summary <br /> o Groundwater levels at the site fell since the previous round of sampling The average <br /> groundwater gradient across the site was 0 007 ft/ft Groundwater flowed predominantly in a <br /> northeasterly direction This is the seventh consecutive quarterly monitoring event in which <br /> flow was toward the northeast <br /> EDB and 1,2 DCA were not detected above laboratory method detection limits (MDLs) in any <br /> site well Gasoline oxygenates, TPHg, BTEX, and TPHd concentrations were less than <br /> MDLs in wells MW1, MW2, MW4 and MW5 <br /> • Relative to the previous sampling event, the concentrations of TPHg and TPHd in well MW3 <br /> decreased by approximately 42% and 69% respectively, however, the concentration of MTBE <br /> in well MW3 rose by 84% <br /> Conclusions <br /> The contaminant plume is localized in the immediate vicinity of well MW3, and is of very limited <br /> extent Although concentrations spikes can occur from time to time, the cumulative data indicate that <br /> the plume is not migrating, and dissolved contaminant concentrations are stable to decreasing <br /> The next round of groundwater sampling is scheduled for November 2004 EHD will be provided <br /> with 48 hours notice prior to conducting fieldwork <br /> 11GZA_FSIVOL IWATAIGROUNDZEIWOOLSEY CHnQMR000413QM2004 doc <br />