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' 07 November 2005 <br /> • AGE-NC Project No 98-0448 <br /> Page 7 of 9 <br /> 1 <br /> of hydrocarbons extracted to date is estimated at 315 27 gallons The mass/volume calculations for <br /> extracted hydrocarbons are included with Appendix F <br />' 5.0. DISCUSSION AND CONCLUSIONS <br />' The implications from the September 2005 ground water monitoring events are as follows <br /> • The September 2005 ground water elevations at the site ranged approximately between 9 42 <br />' feet (MW-7) and 11 81 feet (MW-4B) below MSL The ground water elevation at the site <br /> were slightly above the screen intervals at wells MW-1, MW-2, MW-3 and were within the <br /> screened intervals of wells MW-4A and MW-6, and should be representative of shallow <br />' ground water conditions, however well MW-4B is"drowned"with water approximately 25 <br /> feet over the screen and yields a sample more representative of deeper ground water <br /> conditions (Table 2) <br /> r • Ground water elevation data collected on 29 September 2005 did not suggest that ground <br /> water mounding was occurring due to air spargmg at the site (Figure 3) <br /> • • Ground water flow direction at the site was toward the south-southwest, the ground water <br /> gradient was estimated to be approximately 0 010 ft/ft (Figure 3) <br />' • Only minor concentrations of xylenes were detected in the sample collected from well MW-2 <br /> (Figure 4), no other petroleum hydrocarbons were detected from wells MW-1 through MW- <br /> 6 <br />' • Between the June 2005 and September 2005 monitoring events, decreasing TPH-g <br /> concentrations were reported from samples collected at well MW-2 (from 500 µg/1 to <br />' ND<50 gg/l), benzene levels were not detected from MW-2 for the 9`h consecutive <br /> monitoring event, toluene and ethylbenzene were not detected this quarter and total xylenes <br /> levels continue to decrease from MW-2 samples The trend of decreasing concentrations may <br />' be attributed to the air sparge activities being performed at wells AW-4,AW-5 and MW-4B <br /> (Table 3) <br />' Based on SVE/IAS remediation data collected between 08 June 2005 and 07 September 2005,AGE <br /> concludes - <br /> • The volume of hydrocarbons extracted by the SVE system was calculated to be <br /> approximately 17 pounds during the second quarter 2005, or equivalent to an approximate <br /> volume of 2 72 gallons of gasoline extracted (Appendix F) or approximately one percent <br /> (10%) of the total hydrocarbons removed <br /> Advanced GeoEnvironmental,Inc <br />