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rwto.&Al rechars Inc. Page 2 Groundwater Monitoring Report Project No.425.2 October 19,2004 ' monitoring wells (MW-1, MW-2, MW-4, MW-5 and MW-8) out of the 13 monitoring wells and 3 domestic wells sampled during this even. 1 A summary of groundwater analytical findings includes: * TPH-G concentrations in MW-1 and MW-4 have increased in comparison with the ' previous two quarterly monitoring events. * TPH-G concentrations are elevated in MW-5 and the well has historically exhibited a trend of increasing concentrations. * TPH-G and BTEX concentrations have been detected in MW-8 in the last two monitoring events suggesting the plume has reached MW-8. * The concentration of TPH-G in MW-2 increased in comparison with the ' concentrations detected during the last two monitoring events. * Low levels of ethyl benzene and total xylenes were detected in MW-201, and TPH-G ' was detected during the July 2004 monitoring event. * Daring this monitoring event total xylenes and MtBE were detected in MW-106. * Samples were collected from three domestic wells during the July 2004 monitoring ' event. The domestic wells were non-detect above laboratory reporting limits suggesting contamination has not migrated to the monitored domestic wells. 1.0 GROUNDWATER MONITORING ' 1.1 Hydrology of Site 1.1.1 Zone Divisions To define the site more q accurately,the aquifer is divided into four zones (Zones A through D) defined by the screen intervals of the sixteen monitoring wells associated with the site. Zone ' divisions and well construction are summarized in Table 1 (change from Table A). From this report forward the aquifer will be divided into these four zones ' * Zone A includes monitoring wells screened between 5 and 22-feet bgs * Zone B includes monitoring wells screened between 32 and 35-feet bgs * Zone C includes monitoring wells screened between 45 to 49.5-feet bgs ' * Zone D is represented by MW-202 screened between 79 and 81.5-feet bgs 1.1.2 Horizontal Groundwater Gradients ' Zone A The average groundwater elevation is 73.14 feet above mean sea level (AMSL). This represents a decrease of 0.68 feet since the April 2004 monitoring event. The zone-specific ' groundwater gradient was 0.0015 ft/ft flowing NO3°E. A review of the groundwater gradients in Zone A show groundwater bearings varying from north to northeast with the slope ranging from 0.0010 to 0.0044 ft/ft.