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i Mr Michael Infurna Page 2 Prior to sampling, monitoring wells MWl through MW5 were purged of a minimum of three well casing volumes During the purging process, the physical parameters of temperature, pH and electrical conductivity were measured Samples were collected after the physical parameters had stabilized and water levels had recovered to appropriate levels 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 i Groundwater samples were delivered under chain of custody protocol to Argon Laboratories (ELAP #2359) for the analysis of TPHg and TPHd using modified EPA method 8015, gasoline oxygenate additives, EDB and 1,2 DCA using EPA method 8260, and BTEX using EPA method 8020 i Groundwater Analytical Results TPHg, TPHd, BTEX, EDB and 1,2 DCA were not detected above their respective method detection limits (MDLs) in wells MW1, MW2, MW4 and MW5 In well MW3, benzene was detected at a concentration of 3 6 parts per billion (ppb), TPHg was detected at a concentration of 980 ppb, and TPHd was detected at a concentration of 1,800 ppb Methyl tent butyl ether (MTBE) was the only gasoline oxygenate additive detected at site MTBE was detected in wells MW3 and MW4 at concentrations of 1,200 ppb and 19 ppb, respectively 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 fell since the previous round of sampling During this event an apparent groundwater depression was observed in the center of the site Groundwater flowed towards well MW3 with an average gradient of 0 005 ft/ft Flow direction at the site has historically been inconsistent • TPHg, TPHd, and BTEX concentrations continue to be less than laboratory MDLs in wells MW1, MW2, MW4 and MW5 Benzene was detected in well MW3 after being at non- detectable levels during the three previous sampling events • The MTBE concentration in well MW3 increased somewhat since the previous event but was still within the low end of the historical concentration range for this well Low levels of MTBE were detected in well MW4 for the first time Conclusions Groundwater flow direction remains variable at the site The apparent groundwater depression observed in the middle of the site near well MW3 might possibly be the result of an inaccurate water level measurement I1G7A—Fs\sYsoi\Data\GROUNDZEIWOOLSEY CHTIQMR1200214QM2002 doc