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24 June 2005 AGE-NC Project No. 97-0290 Page 6 of 7 and significantly declined in this area since remediation at the site began.The BTEX plume appears to be stable and declining,with the core of the plume limited to the northern portion of the site. • Concentrations of TPH-g and benzene in well MW-2 have exhibited decreasing trends over the past two years, as depicted in Appendix F. • TPH-g was not detected in five of the seven soil vapor samples collected during the five- month rebound testing period;TPH-g was detected only in the December 2004 and January 2005 samples,at concentrations of 450µg/1 and 400 gg/l.Assuming that low concentrations (<50 µg/1)of TPH-g were still present in the non-detect soil vapor samples,a conservative estimate of 127 lbs of TPH-g were extracted from the subsurface, using the uppermost detection limit of 50 µg/1 to determine the amount of TPH-g extracted during sampling intervals in which TPH-g was not detected. 5.0. RECOMMENDATIONS Based on the findings of the environmental activities recounted in this report,AGE recommends: • Operation of the SVE system should cease due to the lack of regular detections of significant petroleum-hydrocarbon concentrations in SVE samples.Although the operation of the IAS system, in conjunction with the SVE system, may result in further reduction of the low concentrations of hydrocarbons in ground water at the core of the plume and directly down- gradient of the former UST, the hydrocarbon concentrations have approached asymptotic decline and will not quickly respond to the IAS operation.Therefore,operation of the on-site remediation should cease and a future ground water monitoring event of the core area well should be conducted to test for any rebound in hydrocarbon concentrations. • Based on the declining concentrations of dissolved hydrocarbons in ground water and low dissolved hydrocarbon concentrations remaining in the core of the contaminant plume,AGE recommends preparation of a closure report for the site. 6.0. LIMITATIONS Our professional services were performed using that degree of care and skill ordinarily exercised by environmental consultants practicing in this or similar localities. The findings were based upon analytical results provided by an independent laboratory.Evaluation of the subsurface conditions at the site for the purpose of this investigation was made from review of a limited number of available data points (i.e. soil-vapor and ground water samples) and subsurface conditions may vary away Advanced GeoEnvironmentat,Inc.