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it _ <br /> Mr Michael Infurna <br /> Page 2 <br /> i <br /> Prior to sampling, monitoring wells MW1 through MW5 were purged of a minimum of three well <br /> casing volumes During the purging process, temperature, pH and electrical conductivity <br /> parameters were measured <br /> Samples were collected after parameter stabilization, and appropriate water level recovery Purge <br /> water was contained in properly labeled DOT-approved 55-gallon drums The drums are currently <br /> being stored onsite Purge logs are included in Attachment A <br /> Groundwater samples were delivered under chain of custody protocol to Argon Laboratories (ELAP <br /> #2359) Analysis consisted of TPHg and TPHd using modified EPA method 8015B, gasoline <br /> oxygenate additives, ethylenedibromide (EDB) and 1,2-dichloroethane (1,2-DCA) using EPA <br /> method 8260B, and BTEX using EPA method 8021B <br /> Groundwater Analytical Results <br /> EDB and 1,2-DCA were not detected in any site wells BTEX, TPHg, TPHd and gasoline <br /> oxygenates were not detected in wells MW1, MW2, MW4 and MW5 <br /> In well MW3, TPHg was detected at a concentration of 1,900 parts per billion (ppb) Benzene was <br /> detected at a concentration of 0 8 ppb TPHd was detected at a concentration of 910 ppb Methyl- <br /> . tent-butyl ether (MTBE) was detected at a concentration of 870 ppb Analytical results are <br /> summarized in Table 2 Attachment B contains laboratory reports and chain of custody <br /> documentation Graphs of TPHg, TPHd and MTBE concentrations over time in MW3 are included <br /> in Attachment C <br /> Summary <br /> • Groundwater levels at the site rose since the previous round of sampling The average <br /> groundwater gradient across the site was 0 003 ft/ft Groundwater flowed predominantly in a <br /> northeasterly direction This is the sixth consecutive quarterly monitoring event in which <br /> flow was toward the northeast <br /> • EDB and 1,2 DCA were not detected above laboratory method detection limits (MDLs) in any <br /> site well Gasoline oxygenates, TPHg, BTEX, and TPHd concentrations were less than <br /> MDLs in wells MW1, MW2, MW4 and MW5 <br /> • Relative to the previous sampling event, the concentrations of TPHg, TPHd, & MTBE in well <br /> MW3 decreased by approximately 14%, 82% & 10% respectively <br /> Benzene was detected in MW3 for the first time since November 2002, however at a level <br /> below the MCL <br /> IIGZA_FSIVOL 11DATAIGROUNDZEIWOOLSEY CHIRQMR12OG412QM2004 doe <br />