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E! F Mr Michaellnfurna Page 2 i Prior to sampling, monitoring wells MW1 through MW5 were purged a minimum of three well casing volumes During the purging process, temperature, pH and electrical conductivity parameters were measured 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 801513, gasoline oxygenate additives using EPA method 826013, and BTEX using EPA method 8021 B Groundwater Analytical Results EDB and 1,2 DCA were not detected in any site wells BTEX, TPHg, TPHd and gasoline oxygenates were not detected in wells MWI, MW2, MW4 and MW5 In well MW3, TPHg was detected at a concentration of 2,200 parts per billion (ppb) Xylenes were detected at concentrations of 5 1 ppb TPHd was detected at a concentration of 5,100 ppb Methyl- tert-butyl ether (MTBE) was detected at a concentration of 970 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 • Groundwater levels at the site rose since the previous round of sampling The average groundwater gradient across the site was 0 003 ft/ft Groundwater flowed predominantly in a northeasterly direction This is the fifth consecutive quarterly monitoring event in which flow was toward the northeast • EDB and 1,2 DCA were not detected above laboratory method detection limits (MDLs) in any site well Gasoline oxygenates, TPHg, BTEX, and TPHd concentrations were less than MDLs in wells MWI, MW2, MW4 and MW5 • Relative to the previous sampling event, the concentration of TPHd in well MW3 decreased approximately 60% The level of TPHg increased substantially and MTBE increased only slightly Conclusions The contaminant plume is localized in the immediate vicinity of well MW3, and is of very limited extent Although concentrations spikes can occur from time to time, the cumulative data indicate that the plume is not migrating, and dissolved contaminant concentrations are stable to decreasing \\GZA_FSIVOL LIDATAIGROUNDZEIWOOLSEY CHTIQMR12004F1QM2004 doc