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' 01 September 2005 AGE-NC Project No 95-0173 ' Page 8 of 10 ' extracted by the SVE system was calculated to be approximately 266 pounds, or equivalent to a volume of approximately 42 gallons of gasoline Added to the estimated 2,093 gallons of hydrocarbons extracted from the SVE system since 11 April 2000 (start-up), the total volume of hydrocarbons extracted to date is estimated at 2,135 gallons (Table 7) A plot of the cumulative volume (gallons) of hydrocarbons extracted to date and SVE sample TPH-g concentrations are included with Appendix F The volume/mass calculations for extracted hydrocarbons are included ' with Appendix G 4.4. CONCLUSIONS The implications from the May 2005 ground water monitoring event are as follows ' Ground water flow direction was Inferred to be east-northeast, at an approximate hydraulic gradient of 0 003 ft/ft Due to the generally low gradient at the site, slight variations in groundwater measurements or changes of recharge/discharge of the local ground water could greatly modify ground water flow direction On average,ground water elevation at the site Increased approximately 4 67 feet between the 4`h Quarter 2004 and 2nd Quarter 2005 ground water monitoring events • Ground water at the site was significantly above the screened Intervals of wells AW-1 (A and ' B), AW-2 (A and B), and MW-13 (A-C), and slightly above the screened Intervals of wells MW-1 through MW-4 The ground water elevation appeared to be within or near the ' screened Intervals of all other wells at the site and should be representative of shallow ground water conditions • Ground water elevation data collected on 16 May 2005 Implies that ground water mounding did not occur at the site due to the on-going IAS activities • The elevated concentrations of petroleum hydrocarbons detected In samples collected from 1 well MW-4 (screened 30 feet to 50 feet) Indicates that this well is within the remaining dissolved petroleum hydrocarbon"core area" of the plume (Figure 4) • The rapid decrease in dissolved petroleum hydrocarbon concentrations at AW-1 1(A and B) y n i = i B L a4-_L_ tVed tO thLc air sp rCTY 11n�PtI�7ItiPC Swat wf-11C A W-1 R aria A1+V-L t1�dnu ts)camb- a�uiuu�cu �� ufc.oi�g:,ingµ�. �I.,...F,--=�w and AW-2B during July 2004 through May 2005 However,previous analytical groundwater data has Indicated this concentration reduction may later rebound • Generally, an overall apparent trend of decreasing dissolved petroleum hydrocarbon concentrations Is evident in water samples collected from wells MW-1 through MW-4, MW-6,AW-1 (A and B),and AW-2(A and B),the decreasing trend may be attributed to the air spargmg activities being performed at wells AW-1B and AW-2B (Table 3) ' Advanced CeoEnvironmental,Inc