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15 September 2000 — `— AGE-NC Project No. 95-0185 Page 3 of 4.0. CONCLUSIONS Based on the data collected during this monitoring period, AGE concludes: • Ground water flow at the site was toward the southeast which is consistent with the previous monitoring events. The ground water elevation has decreased approximately 0.18 feet since the last sampling event in June 1999. The average hydraulic gradient was determined to be 0.001 feet/feet which is nearly flat (0.06 degrees). The flat hydraulic gradient suggests that ground water has a very slow flow rate. • The concentrations of"I'PH-d in all of the wells has either remained fairly stable or decreased since the last monitoring event in June 1999.In addition,TPH-g was stable in MW-I between the last two monitoring events. • 13TE&X concentrations dropped from trace concentrations in June 1999 to non-detectable levels during this sampling event. _ 0 MTBE was not detected in any of the ground water monitoring wells during this monitoring event. MTBE was last detected in monitoring wells MW-1, MW-2 and MW-3 in June 1996 and in monitoring well MW-4 in October 1997. 5.0. RECOMMENDATIONS Based upon the analytical data from previous and current monitoring events. AGE believes that the TPI 1-d and TPH-g plumes are either stable or declining. In addition, only trace concentrations of B'I'E&X and MTBE have been detected in the ground water samples in the past. Therefore, AGE recommends that one additional ground water monitoring well be installed in the down-gradient direction near the southeast corner ofthe property.Following the installation of the additionalground water monitoring well. AGF: recommends an additional year of quarterly monitoring. If the hydrocarbon plumes show no lateral migration in the down-gradient direction and the concentrations of hydrocarbons remain stable or decline,AGE;will request the PHS-EMD consider granting closure for this 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 on analytical results provided by an independent laboratory. Evaluations ofthe geologic/hydrogeologic conditions at the site for the purpose of this investigation are made from a limited number of available data points(i.e. ground water samples)and subsurface conditions may vary away from these data points. No other warranty,expressed or implied. is made as to the professional recommendations contained — in this report. Advanced(.col-'m ironmental.Inc.