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' 24 August 2001 AGE-NC Project No 98-0448 ' Page 6 of 7 ' 4.4. DISCUSSION AND CONCLUSIONS The implications from the April 2001 ground water monitoring event are as follows • Ground water flow direction at the site was generally toward the south-southwest at a gradient of 0 015 ft/ft or less, due to the low gradient at the site, slight vanations in ground ' water measurements or changes of recharge/discharge of the local ground water could greatly modify the inferred ground water flow direction ' • The increase of ground water elevation of approximately 0 56 feet between January 2001 and April 2001 is probably due to seasonal fluctuation • The ground water elevation at the site was reasonably within the screened intervals of wells ' MW-1, MW-2, MW-3, MW-4A, MW-5, MW-6, MW-7 and MW-8 and should be representative of shallow ground water conditions,however well MW-4B is"drowned"with water approximately 25 feet over the screen and yields a sample more representative of ' deeper ground water conditions • Ground water elevation data collected on 23 April 2001 was inconclusive regarding potential • water mounding due to alar sparging at the site • The elevated concentrations of petroleum hydrocarbons detected in samples collected from ' wells MW-1,MW-2, MW-4A and MW-4B indicate that these wells are within the dissolved petroleum hydrocarbon "core area" of the plume (Figures 4) • Previous and current analytical results from ground water samples suggest that there is a minor MTBE, DIPE and TBA-impact to ground water in the areas of wells MW-3 and MW- 4 (Table 2) • Laboratory results of ground water samples collected from MW-4B (screened 45 to 50 feet bsg) suggest that the dissolved petroleum hydrocarbon plume extends to at least 50 feet bsg, and is at least 30 feet thick Based on SVE remediation data collected between 16 April 2001 (start-up) and 30 June 2001, AGE concludes • The volume of hydrocarbons extracted by the SVE system was calculated to be approximately 677 65 pounds, or approximately 108 4 gallons of petroleum hydrocarbons extracted (Appendix F) during the second quarter 2001 monitoring period • The average SVE inlet flow rate was 40 cubic feet per minute(cf n) at an average differential Ipressure of 0 55 inches of water (Table 5) Advanced GeoEnvironmental,Inc