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26 October 2000 • AGE-NC Project No 96-0229 Page 3 of 5 ' approximately 11 feet per mile and directed radially towards the northeast The ground water surface elevation at the site is approximately 4 to 5 feet above the slotted screen intervals in wells MW-3 and MW-4 and approximately 22 to 24 feet above the slotted screen intervals in wells MW-1 and MW- IOB 3 2 LABORATORY RESULTS OF GROUND WATER SAMPLES A total of eleven ground water samples were submitted to a DHS-certified laboratory TPH-g was detected in water samples collected from wells MW-1, MW-2, MW-3, MW-4, MW-6, and MW-7 at concentrations ranging between 59 micrograms per liter (µg/1) and 55,000 µg/1 IBTEX compounds were detected in ground water samples collected from wells MW-1, MW-2, MW-3, MW-6 and MW-7 at concentrations as high as 6,400 µg/1 (xylene, MW-3) The greatest benzene concentration was observed at MW-1 at a concentration of 4,000µg/1 MTBE was detected utilizingEPA Method 8020 m ground water samples collected from 1� p � . wells MW-1, MW-7, and MW-8 at concentrations as high as 440µg/1 MTBE was detected utilizing EPA Method 8260 in samples collected from wells MW-1, MW-6, MW-7 and MW-8 at concentrations as high as 260 µg/1 No other fuel oxygenated additives were detected above laboratory reporting limits from the analyzed samples Analytical results of the ground water samples are summarized in Table 2 The laboratory reports I (Castle Analytical Laboratories Reference No 3167) and chain-of-custody forms are presented 1n Appendix B 4.0 SUMMARY AND CONCLUSIONS IThe implications from the findings of the August 2000 investigation are • Ground water monitoring data collected in the area of wells MW-1 through MW-10 indicated Ia ground water flow direction generally toward the northeast at a gradient of 0 002 ft/ft This appears to be the prevailing flow direction for the area Due to the low hydraulic gradient at the site, slight vanations in ground water measurements or changes of recharge/discharge of the local ground water could greatly modify ground water flow direction • Monitoring wells MW-1 and MW-14B are "drowned", and yield samples representative of deeper ground water conditions Deeper ground water in the area of MW-1 (48 to 53 feet • bsg) is Impacted, but is not impacted in the down-gradient area of MW-10B (50 to 55 feet bsg) IAdvanced GeoE nviron mental,Inc I