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1 ' 12 May 2005 . AGE-NC Project No 96-0229 ' Page 5 of 6 ' 4.0. SUMMARY AND CONCLUSIONS The implications from the findings of the December 2004 ground water monitoring event are • Generally,depth to ground water at the site varied between 33 feet and 36 feet below the tops of the well casings, ground water elevations ranged between 19 72 feet (MW-3) and 23 29 ' feet(MW-12) below mean sea level (Table 2) • First Zone ground water flow direction at the site inferred a net ground water flow towards ' the northeast at a hydraulic gradient of approximately 0 004 ft/ft (Figure 4), • Second Zone ground water flow direction at the site inferred a net ground water flow direction towards the east at hydraulic gradients of approximately 0 007 ft/ft (Figure 5) I • Due to the low hydraulic gradient at the site, slight variations in ground water recharge/discharge could greatly modify the inferred ground water flow direction • The most intense TPH-g-impacted ground water was reported in the area of First Water Zone wells MW-2 and MW-6 at concentrations as high as 81,000 pg/1, the First Water Zone TPH-g plume appears to have migrated at least 425 feet towards the northeast (downgradient) in the areas of wells MW-18 and MW-19 (Figure 6) • The most intense MTBE-impacted ground water was reported in the area of First Water Zone well MW-9(screened 20-40 ft)at a concentration of 1,100µg/1,the First Water Zone MTBE plume appears to have migrated at least 490 feet towards the northeast (downgradient) beyond the areas of wells MW-10 and MW-18 (Figure 7) A significant increase in MTBE ' concentrations has been evident from well MW-9 for three consecutive quarterly monitoring events ' • Significant concentrations of 1,2-DCA were detected in the samples collected from wells MW-1 and MW-2 and downgradient at well MW-17A, indicating 1,2-DCA may have laterally migrated 315 feet towards the northeast to the area of MW-17A (screened 62-67 feet), however, the vertical extent appears to be defined onsite by the adjacent multi-level well MW-13 (A-D)and offsite to the northeast by multi-level well MW-17 (B-C) 5.0. RECOMMENDATIONS IBased upon data collected during December 2004, AGE recommends • Continued utilization of wells MW-I through MW-19 for quarterly groundwater monitoring and sampling,the first quarter 2005 ground water monitoring event was performed on 04-05 April 2005 and a report of findings is pending The second quarter 2005 ground water Advanced GeoEnvironmental,Inc I