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, i • A S S O C I A T E S I N C . GROUNDWATER FLOW DIRECTION Water level measurements were collected from monitoring wells MW1, MW2, and MW3 on October 9, 2003. Water elevations ranged from —29.26 to —29.33, representing an average decrease in water table elevation of approximately 4.08 feet since July 2003. The water level data were used to develop the groundwater elevation contour map (Figure 3). Assuming that horizontal isotropic conditions prevail, groundwater in the uppermost aquifer beneath the site flowed towards the northeast. The average hydraulic gradient on October 9, 2003 was calculated to be 0.0011 or approximately 5.8 ft/mile. A summary of groundwater monitoring data is presented in Table 1. SAMPLING ACTIVITIES On October 9, 2003, ATC personnel collected groundwater samples from monitoring wells MW1, MW2, and MW3. The locations of the monitoring wells are shown on Figure 2. Prior to collection of groundwater samples, the depth to water, pH, electrical conductivity, and temperature were measured in the monitoring wells and recorded. A minimum volume of three well casings was purged from each well prior to sampling. The wells were allowed to recover and samples were collected from each well using a disposable bailer. The groundwater matrix samples collected from each well were submitted to State-certified Argon Laboratories (FLAP Cert. No. 2359) for chemical analysis of TPHg utilizing EPA method 8015 modified, and BTEX and oxygenate fuel additives including MTBE utilizing EPA method 802113/8260B. Groundwater well purge and sample logs are contained in Attachment 1. ANALYTICAL RESULTS The groundwater analytical results measured at monitoring wells MW 1, MW2, and MW3 showed detectable concentrations of TPHg, BTEX, MTBE, TBA, and 1,2-DCA. The Maximum Contaminant Level (MCL) for benzene, 1 pg/L, was exceeded at monitoring well MW2 which had detected a concentration of 5.6 µg/L. The MCL for MTBE, 13 pg/L, was exceeded at wells MW1, MW2, and MW3, which had detected concentrations of 18 µg/L, 75 pg/L, and 76 ug/L, respectively. The MCL for 1,2-DCA, 0.5 gg/L, was exceeded at monitoring wells MWl, MW2 and MW3, which had detected concentrations of 26 µg1L, 44 gg/L, and 42 pg/L, respectively. An Action Level for TBA, 12 gg/L, was exceeded at well MW2 that had detected a concentration of 38 gg/L. CONCLUSIONS Groundwater flow direction and gradient is consistent with previous sampling events. Water table elevations have decreased since the July 2003 monitoring event. Groundwater analytical results show a slight increase in concentrations, though most remained within historical parameters as set by previous groundwater analytical results. s:lenvironmental1224931Repmu\4QR-03.doc 3