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I06 December 2000 AGE-NC Project No 95-0173 ' Page 6 of 7 Iextracted gasoline during these periods The mass of hydrocarbons extracted from the SVE system was calculated to be approximately 209 I gallons Added to the estimated 201 gallons of hydrocarbons extracted from 11 April to 29 June 2000 from the SVE system, the total mass of hydrocarbons extracted to date is approximately 410 gallons The mass calculations for extracted hydrocarbons are Included with Appendix E I 40 CONCLUSIONS IThe Implications from the September 2000 ground water monitoring event are as follows ' • Ground water flow direction for the area bound by wells MW-1 through MW-13, AW-lA and AW-2A was generally toward the northeast at a gradient of 0 003 ft/ft, due to the low gradient at the site, slight variations in ground water measurements or changes of recharge/discharge of the local ground water could greatly modify ground water flow direction • The decrease of ground water elevation of approximately 2 feet between May 2000 and September 2000 is probably due to seasonal fluctuation C Ground water elevation data collected on 29 September 2000 does not suggest ground water mounding is occurring due to the air sparging activities at the site • Wells MW-1,MW-2,MW-3 and MW-4 are approximately five feet"drowned", and may not yield samples fully representative of shallowest ground water conditions The ground water elevation appeared to be withing the screen intervals of wells MW-5 through MW-12 and should be representative of shallowest ground water conditions ' • The elevated concentrations of petroleum hydrocarbons detected in samples collected from wells MW-2, MW-3, MW-4, AW-1 and AW-2 indicate that these wells are within the ' dissolved petroleum hydrocarbon "core area" of the plume (Figure 4) • The highest dissolved petroleum hydrocarbons were detected in the area of wells AW-1, AW-2 and MW-3, with increasing depth, the dissolved plume apparently grades from higher conccr�trations to low cr concentrations • From May 2000 to September 2000, a moderate to substantial decrease in concentrations of ' dissolved TPH-g and BTEX were quantified in ground water samples collected from wells MW-1, MW-2 and MW-3 (Table 2) The TPH-g and BTEX decreases may be due to air sparging activities • Laboratory results of ground water samples suggest that there is a minor MTBE-impact to • ' Advanced GeoE nviro n mental,Inc I