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i ' 02 October 2000 AGE-NC Project No 97-0301 Page 4 of 5 at wells MW-1,MW-2,MW-3 and MW-4,therefore,ground water samples collected in June 2000 may not be fully representative of shallow ground water conditions- • Ground water elevations decreased at the site an average 101 feet from March 2000 to June ' 2000 • From December 1999 to March 2000, a substantial decrease in concentrations of dissolved ' TPH-g, TPH-d, benzene, toluene and ethylbenzene were quantified in the ground water sample collected from well MW-1 (Table 2), conversely, an substantial increase in concentrations were quantified from March 2000 to June 2000, thus returning concentration II ' levels near those encountered during the first monitoring event • The core of the dissolved petroleum hydrocarbon plume appears to be located in the area of ' MW-1,analysis of ground water samples collected from MW-1 suggest the core of the plume is impacted by TPH-g, TPH-d, TPH-k, BTEX, TBA, 1,2-DCA and EDB • The lateral extent of the dissolved petroleum hydrocarbon plume is not known toward the ' southeast, northeast, cast and west of the current area bound by wells MW-1,MW-2,MW-3 and MW-4 '• • The elevated petroleum hydrocarbon concentrations detected in water samples collected from well MW-1 (screened between 30 and 50 feet bsg) suggest that this well may be screened within or near the dissolved petroleum hydrocarbon"source area" of the plume ' The vertical extent of petroleum hydrocarbon-impacted soil is not fully defined at the site • Fuel oxygenated compounds do not appear to have significantly impacted ground water on ' the subject site 5.0. RECOMMENDATIONS ' Based upon data collected during June 2000, AGE recommends • Continued quarterly ground water monitoring The next quarterly monitoring and sampling event is tentatively scheduled for September 2000 • Continued utilization of wells MW-1, MW-2, MW-3 and MW-4 for characterization of ' ground water conditions at the site • A search for all potential ground water receptors within a 2,000-foot radius of the site ' Installation of at least three additional ground water monitoring wells to assess the lateral extent of petroleum-impacted ground water, two wells should be installed southeast and northeast of the former UST area to delineate the up-gradient and cross-gradient petroleum Advanced GeoEnvironmental,Inc