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N , Mr Michael Infurna Page 2 • 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 Iabeled 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 using EPA method 8260, and BTEX using EPA method 8020 Groundwater Analytical Results BTEX, EDB and 1,2 DCA were not detected in any site wells TPHg, TPHd and gasoline oxygenates were not detected in wells MW1, MW2, MW4 and MW5 In well MW3, TPHg was detected at a concentration of 1,200 parts per billion (ppb) TPHd was detected at a concentration of 320 ppb Methyl tert butyl ether (MTBE) was detected at a concentration of 770 ppb and tent butyl alcohol (TBA) was detected at a concentration of 33 ppb Tert-amyl methyl ether (TAME) was not detected in well MW3 during this event 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 rose since the previous round of sampling The average groundwater gradient across the site was 0 002 ft/ft Groundwater flowed in a northeasterly direction • BTEX compounds, EDB and 1,2 DCA were not detected above laboratory method detection limits (MDLs) in any site well Gasoline oxygenates, TPHg, TPHd, and BTEX concentrations were less than MDLs in wells MW1, MW2, MW4 and MW5 • Compared to the previous sampling event, the concentrations of TPHd and MTBE in well MW3 were substantially lower while the level of TPHg was slightly higher Low levels of TBA were detected in MW3 for the third time since sampling began TAME was not detected in MW3 during this event Conclusions Both the dissolved contaminant plume and residual soil contamination are localized in the vicinity of well MW3, and are of very limited extent Only well MW3 has ever contained dissolved contaminants and no evidence of plume migration has been found Analytical data indicate stable to decreasing dissolved contaminant concentrations in this well (Attachment C) IIGZA_FS\VOL_11DATAIGROUNDZEIWOOLSEY CHTIQMR1200312QM2003 doc I