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03 September 2004 <br /> AGE-NC Project Na 98-0448 <br />' Page 12 of 13 <br /> • The July 2004 concentrations of petroleum hydrocarbons detected in the samples collected <br />' from wells MW-2 and MW-4A Indicate that these wells are within the dissolved petroleum <br /> hydrocarbon "core area" of the plume (Figures 7 and 8) <br />' • At the conclusion of the recent ground water rebound response test, a significant Increase <br /> (spike)of dissolved concentrations of TPH-g, ethylbenzene and xylenes were reported from w <br /> wells MW-2, MW-4A and MW-4B, however, a significant decrease was reported from all <br /> Ithree wells during the July 2004 ground water monitoring event The significant decreases <br /> may be attributed to the recent Implementation of wells VW-6 and AW-5 into the <br />' remediation system <br /> Based on SVE/IAS remediation data collected between 28 January 2004 and 22 June 2004, AGE <br />' concludes <br /> • The volume of hydrocarbons extracted by the SVE system was calculated to be <br /> approximately 108 pounds, or equivalent to an approximate volume of 17 25 gallons of <br /> gasoline extracted (Table 4, Appendix 1) <br /> • The average SVE Inlet flow rate was estimated to be 37 cubic feet per minute (cfm), at an <br /> average differential pressure of 0 58 Inches of water (Table 3) <br /> • Since Initiation of the SVE system(April 2001),the total volume ofpetroleum hydrocarbons <br /> extracted is estimated to be approximately 270 gallons (Table 4) <br /> • A significant spike in the June 2004 SVE influent air samples can be attributed to the <br /> addition of wells VW-6 and AW-5 to the remediation system, the spike was likely caused <br /> by air spargmg activities mechanically stripping adsorbed soil contamination beneath the <br /> ground water table (saturated zone) <br /> 6.0. RECOMMENDATIONS <br /> Based upon the results of this investigation, AGE recommends <br /> • Continued quarterly ground water monitoring and sampling of wells MW-1, MW-2, <br /> MW-4A, MW-4B and MW-6, ground water sampling results will be used to monitor <br />' progress of the SVE and IAS remediation system <br /> • Continued operation of the on-site SVE and IAS remediation system, remediation progress <br />' will be re-evaluated on a quarterly basis Based on the current data, AGE anticipates <br /> operation of the on-site SVE and 1AS remediation system at least through the 2004 calendar <br /> year z <br /> IAdvanced GeoEnvironmental,Inc <br />