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19 April 1999 AGE-NC Project No 95-0104 IPage 4of5 6 Indicated that the ground water flow direction was generally toward the northeast at a ' gradient of 0 002 ft/ft, or approximately 11 feet per mile, ground water monitoring data collected in the area VW-1, MW-3 and MW-5 inferred a southeast ground water flow direction at a gradient of 0 002 ft/ft, (Figure 3) Due to the low gradient at the site, slight ' variations in ground water measurements or changes of recharge/discharge of the local ground water could greatly modify ground water flow direction ' • Ground water elevation at the site increased an average 1 72 feet between the September 1998 and the January 1999 ground water monitoring events ' • Ground water was approximately 22 feet above the screen intervals at MW-2, MW-3 and MW4 Therefore these wells are"drowned"and yield samples more representative of deeper ground water than of shallow ground water ' • TPH-g was detected in water samples collected from wells MW-1, MW-5, MW-6 and VW-1 at concentrations ranging up to 4,300 micrograms per liter(4g11) • MTBE was confirmed from wells MW-1 and VW-1 utilizing EPA Method 8260 at concentrations as high as 1 6µgll, MTBE was not detected above laboratory reporting limits ' from any of the analyzed samples utilizing EPA Method 8020, TBA was detected from wells MW-1 and VW-1 at concentrations ranging as high as 6 9 µg/l No other fuel oxygenates were detected at concentrations above laboratory reporting limits from the analyzed samples • BTEX compounds were detected in ground water samples collected from wells MW-1,MW- 5, MW-6 and VW-1 at concentrations ranging as high as 520 µg/l (xylenes, VW-1) The greatest benzene concentration was detected from well MW-6 at a concentration of 20 µg/1 • From October 1998 to January 1999, an increase In dissolved petroleum hydrocarbon concentrations was observed from wells MW-1, MW-5 and MW-6, (Table 2) Conversely, a slight decrease was observed from well VW-I None of the increases or decreases appears to be related to a significant trend • The elevated concentrations of petroleum hydrocarbons detected in samples collected from well VW-1 indicate that this well is within or near the dissolved petroleum hydrocarbon "core area" of the plume (Figure 4) 5.0. RECOMMENDATIONS Based upon the results of this investigation, AGE recommends • Continued quarterly monitoring and sampling of selected ground water monitoring in April 1999, wells MW-3 and MW-4 should be sampled during the April 1999 sampling event to monitor deeper ground water downgradient to crossgradient of VW-1 The April quarterly ' Advanced GeoEnvironmental,Inc