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Mr Michael Infurna / . Page 2 Prior to sampling, monitoring wells MW1 through MWS 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 8015, gasoline oxygenate additives, EDB and 1,2 DCA using EPA method 8260, and BTEX using EPA method 8020 Groundwater Analytical Results TPHg, TPHd, BTEX, gasoline oxygenates, EDB and 1,2 DCA were not detected in wells MW 1, MW2, MW4 and MW5 Benzene and toluene were not detected in well MW3 In well MW3, TPHg was detected at a concentration of 1,100 parts per billion (ppb) TPHd was detected at a concentration of 1,900 ppb Methyl tert butyl ether (MTBE) was detected at a concentration of 1,100 ppb Tert butyl alcohol (TBA) was detected at a concentration of 84 ppb, and tert-amyl methyl ether (TAME) was detected a concentration of 3 3 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 was 0 002 ft/ft Groundwater flowed in a northeasterly direction • Benzene and toluene were not detected in well MW3 Gasoline oxygenates, TPHg, TPHd, BTEX, EDB and 1,2 DCA concentrations were less than laboratory method detection limits (MDLs) in wells MW1, MW2, MW4 and MW5 • In well MW3, MTBE decreased slightly since the previous event Low levels of TBA were detected for the second time since sampling began, and TAME was detected for the first time at near non-detectable concentrations MTBE was not detected in any other site wells Conclusions The lateral and vertical limits of contammation have been defined Both the dissolved contaminant plume and residual soil contamination are localized in the vicinity of well MW3 and are of very limited extent Dissolved contaminants have never been detected in wells MW1, MW2 and MW5 nor have they been detected in well MW4 except for the anomalous MTBE 11GZA ESNVOL 11DATAIGROUNDZEIWOOLSEY CH nQMR1200311QM2003 doc