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Mr MichaelInfiuna <br /> Page 2 <br /> • <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 8015B, gasoline <br /> oxygenate additives, ethylenedibromide (EDB) and 1,2-dichloroethane (1,2-DCA) using EPA <br /> method 8260B, 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 500 parts per billion (ppb) TPHd was <br /> detected at a concentration of 1,100 ppb Xylenes were detected at a concentration of 1 8 ppb <br /> Methyl-tent-butyl ether (MTBE) was detected at a concentration of 1,700 ppb 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 rose since the previous round of sampling The average <br /> groundwater gradient across the site was 0 003 ft/ft Groundwater flowed predominantly in a <br /> northeasterly direction <br /> • EDB and 1,2-DCA were not present above laboratory method detection limits (MDLs) in any <br /> site well Gasoline oxygenates, TPHg, BTEX, and TPHd concentrations were less than MDLs <br /> in wells MW1, MW2, MW4 and MW5 <br /> • Relative to the previous sampling event, the concentrations of TPHg, TPHd, xylenes and <br /> MTBE in well MW3 increased Benzene, toluene and ethylbenzene were not detected in well <br /> MW3 <br /> Conclusions <br /> Dissolved contaminants in groundwater at the site consist primarily of TPHd and MTBE BTEX <br /> compounds are absent or present only at trace levels The contaminant plume 1s localized in the <br /> immediate vicinity of well MW3, and is of very limited extent Although concentrations spikes occur <br /> from time to time, the cumulative data indicate that the plume is not migrating, and dissolved <br /> contaminant concentrations are stable to decreasing <br /> G 1GROUNDZEIWOOLSEY CH nQMR1200512QM2005 doc <br />