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I15 December 2003 <br /> AGE-NC Protect No 95-0173 _ <br /> IPage 8 of 9 <br /> I decreasing concentrations may be attributed to the air sparge activities being performed at <br /> wells AW-1 through AW-7(Figures 4 and 5) <br /> • A substantial increase in dissolved hydrocarbons was observed from well AW-2B, the <br /> increase in hydrocarbon concentrations may also be attributed to IAS activities being <br /> conducted from AW-1B with lateral movement of dissolved petroleum hydrocarbons at <br /> deeper depths <br /> • Previous and current laboratory results of ground water samples suggest that there is a minor <br /> MTBE- and 1,2-DCA-impact to ground water in the areas of wells MW-2 through MW-5, <br /> MW-11 and AW-2A (Tables 3 and 4) <br /> Based on SVE remediation data collected between 23 June 2003 and 09 September 2003, AGE <br /> concludes <br /> I The average SVE inlet vapor concentration was approximately 798 µg/l, the average SVE <br /> inlet flow rate was approximately 101 cubic feet per minute (Table 6) <br /> • The volume of hydrocarbons extracted by the SVE system was calculated to be <br /> approximately 91 gallons of petroleum hydrocarbons (Appendix F) during the June, July, <br /> August and September 2003 monitoring periods (Table 7) <br /> • Since initiation of the SVE system,the total volume of petroleum hydrocarbons extracted is <br /> estimated to be approximately 1,698 gallons (Table 7) <br /> I • A spike in the PID field measurements was evident(09 September 2003)that coincided with <br /> the reconfiguration of the SVE well network from VW-1 through VW-7 to VW-1 through <br /> VW-4 SVE Wells VW-5 through VW-7 were closed at the well-heads due to only trace <br /> I levels of petroleum hydrocarbons observed at these wells from PID field measurements <br /> (Table 6) <br /> 6.0. RECOMMENDATIONS <br /> Based upon third quarter 2003 data collected from the site, AGE recommends <br /> • Continued quarterly ground water monitoring and sampling ofwells MW-1 through MW-13, <br /> AW-lA, AW-1B, AW-2A and AW-2B, ground water sampling results will be used to <br /> monitor progress of the SVE and IAS remediation system <br /> • Continued operation of the on-site SVE and IA.S remediation system, however, to optimize <br /> . the effective radius of influence in the `core' area of the plume, AGE recommends only <br /> extraction from SVE wells VW-1 and VW-2 and sparging pressure to wells AW-I (A and <br /> IAdvanced GeoEnvirantnental,Inc <br /> I <br />