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02 August 2000 <br /> AGE-NC Project No 95-0121 <br />' Page 6 of 7 <br /> 5.0. DISCUSSION AND CONCLUSIONS <br /> The implications from the findings of the April 2000 ground water monitoring event are <br />' • Ground water flow direction at the site was inferred to be toward the northeast at a gradient <br /> of 0 004 ft/ft or less, due to the low gradient at the site, slight variations in ground water <br />' measurements or changes of recharge/discharge of the local ground water could greatly <br /> modify ground water flow direction <br /> • The increase of ground water elevation of approximately 2 11 feet between January 2000 and <br />' April 2000 was probably due to seasonal fluctuation <br /> • Ground water elevation data collected on 19 April 2000 does not suggest ground water <br />' mounding is occurring due to the air sparging activities at the site <br /> • The ground water elevation at the site is approximately ten to nineteen feet above the screen <br /> intervals at wells MW-1 through MW-7 (drowned wells), and may not yield samples fully <br /> t representative of shallowest ground water conditions <br /> • From January to April 2000, a moderate to substantial decrease in dissolved petroleum ` <br />' hydrocarbon concentrations was quantified in samples collected from wells MW-1, MW-2 <br /> and MW-3 (Table 2), the reported decreases may be due to air sparging activities <br />' • The elevated concentrations of petroleum hydrocarbons detected in samples collected from <br /> wells MW-1,MW-2, MW-3, MW-4 and MW-7 indicate that these wells are within or near <br /> the dissolved petroleum hydrocarbon "core area" of the plume (Figure 4) <br /> Based on SVE remediation data collected between 01 April 2000 and 30 June 2000,AGE concludes <br />' • The mass of hydrocarbons extracted from the inlet of the SVE system was calculated to be <br /> approximately 57 58 pounds of petroleum hydrocarbons (Appendix F) dunng the second <br />' quarter 2000 monitoring period <br /> • Since initiation of the SVE system, the total mass of petroleum hydrocarbons extracted is <br /> estimated to be approximately 92 91 pounds (Appendix F) <br /> • The average SVE inlet flow rate was equal to 44 cubic feet per minute (cfm) at an average <br /> differential pressures of 0 65 inches of water(Table 5) <br /> ' • No general concentration trends were evident in the PID field measurements or results of <br /> laboratory analysis of soil-gas vapor samples over the monitoring period <br /> 1 <br /> ' Advanced GeoEnvironmental,Inc <br /> 1 <br />