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' Mr Michael Infurna Page 2 • Samples were collected after parameter stabilization, and appropriate water level recovery Purge water was contained in properly labeled DOT-approved 55-gallon drums The drums are currently being stored onsite Purge logs are included in Attachment A Groundwater samples were delivered under chain of custody protocol to Argon Laboratories (ELAP #2359) Analysis consisted of TPHg and TPHd using modified EPA Method 8015M, gasoline oxygenate additives, ethylenedibromide (EDB) and 1,2-dichloroethane (1,2-DCA) using EPA Method 826013, and BTEX using EPA Method 8021B Groundwater Analytical Results EDB and 1,2-DCA were not detected in any site well BTEX, TPHg, TPHd and gasoline oxygenates were not detected in wells MW1, MW2, MW4 and MW5 In well MW3, BTEX compounds were not present, but TPHg was detected at a concentration of 550 parts per billion (ppb) TPHd was detected at a concentration of 710 ppb Methyl-tent-butyl ether (MTBE) was detected at a concentration of 1,700 ppb Analytical results are summarized in Table 2 Attachment B contains laboratory reports and chain of custody documentation Graphs of TPHg, TPHd and MTBE concentrations over time in MW3 are included in Attachment C Summary • O Groundwater levels at the site fell since the previous round of sampling The average groundwater gradient across the site was 0 005 ft/ft Groundwater flowed predominantly in a northeasterly direction o EDB and 1,2-DCA were not present above laboratory method detection limits (MDLs) in any site well Gasoline oxygenates, TPHg, BTEX, and TPHd concentrations were less than MDLs in wells MW1, MW2, MW4 and MW5 • In monitoring well MW3, the concentrations of TPHg, TPHd, and MTBE were similar to the previous event Conclusions Dissolved contaminants in groundwater at the site consist primarily of TPHd and MTBE BTEX compounds are absent or present only at trace levels The contaminant plume is localized in the immediate vicinity of well MW3, and is of very limited extent Although concentrations spikes occur from time to time, the cumulative data indicate that the plume is not migrating, and dissolved contaminant concentrations are stable to decreasing • G 1GROUNDZEIWOOLSEY CH-nQMR1200513QM2005 doe