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' 24 December 2001 • AGE-NC Project No 95-0130 Page 4 of 5 ' • Ground water flow direction was inferred to be towards the northeast at a gradient of 0 007 ft/ft in the area bound by wells MW-1 through VW-3 • Ground water at the site is approximately 15 to 25 feet above(drowned) the screen intervals of wells MW-1, MW-2, MW-3, MW-4 and MW-5 (i e screened below ground water elevation), and may not yield samples fully representative of shallowest ground water ' conditions, wells VW-1C, VW-2A and VW-3A are approximately five to ten feet "drowned" The ground water elevation appeared to be withing the screen Interval of well VW-1B and should be representative of shallowest ground water conditions ' • The decrease of ground water elevation of approximately 1 07 feet between the February 2001 and the May 2001 monitoring events is likely part of the seasonal ground water fluctuation ' • The only detection of dissolved TBA was in the sample collected from off-site crossgradient well MW-5 at a concentration of 35 µg/1 and from well MW-3 located at the northeast fringe ' of the Top Filling Station property at 95 /,tg/l • The reported concentrations of MTBE have generally decreased slightly compared to ground '• water samples analyzed during the February 2001 and May 2001 monitoring events However, reported concentrations of MTBE have not demonstrated an increasing or decreasing trend during the ground water monitoring program • The elevated concentrations of petroleum hydrocarbons detected in samples collected from wells VW-1, VW-2 and VW-3 indicate that these wells are within or near the dissolved petroleum hydrocarbon "core area"of the plume (Figures 4 and 5) r • The lateral extent of the dissolved petroleum hydrocarbon plume is not known toward the northwest, north, northeast and east of the area bound by wells MW-1 through VW-3, the vertical extent is not known in any area (Figures 4 and 5) • The greatest concentrations of dissolved TPH-g and BTEX were detected in samples collected from wells VW-1, VW-2 and VW-3 located near the northern-mast former UST pit which is consistent with previous monitoring event results The greatest concentration of dissolved MTBE was detected in the sample collected from. well VW-3 (Figure 4) located near the southern-most former UST pit (Figure 5) which suggests possibly at least two separate releases 50 RECOMMENDATIONS IBased upon the results of the third quarter 2001 investigation, AGE recommends Advanced GeoEnvironmental,Inc