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08 November 2000 AGE-NC Project No. 95-0142 Page 2 of 9 • On 9 and 10 February 1994, ground water monitoring wells MW-1,MW-2 and MW-3 were installed at the site. In November 1994, monitoring well MW-4 was installed at the site. • On 13 June 1995 three soil probe borings were established at the site. On the 14 and 15 June 1995 soil vapor samples were obtained from the site. Significant mass of hydrocarbons were detected in soil and vapor samples analyzed. • On 25 and 26 September 1995,four soil borings were drilled at the site,borings VE-1,VE-2, VE-3 and VE-4 were completed as dual-screened soil vapor extraction wells. • On 24 April 1997, soil boring MW-5 was advanced at the site. • On 22 May 1998, four soil probe borings (AS134 to AS137) were advanced at the site. Hydrocarbon impacted soil was encountered to a depth of 60 feet bsg. • On 04 November 1998, a deep ground water monitoring well, MW-6 was installed on-site. On 10, 11 and 12 of January 2000,two down gradient, deep ground water monitoring wells, MW-7 and MW-8, were installed on-site. Hydrocarbon impacted ground water was detected in well MW-6, installed in the former UST area. A total of 18 ground water monitoring events have occurred at the site. Soil and ground water on the site have been impacted with petroleum hydrocarbons. The horizontal extent and stability of the petroleum hydrocarbon-impacted soil and ground water has been documented. In Corrective Action Plan -November 1995, dated 15 November 1995 (CAP), AGE recommended implementation of soil vapor extraction in conjunction with in-situ air sparging for remediation of the petroleum hydrocarbon-impacted soil and ground water at the site. At the time the CAP was prepared,ground water extraction was generally not viewed as an effective and cost efficient method of ground water remediation, but has gained more favor recently, due to reduced treatment and disposal costs, as a method to address impacted ground water where air-sparging may not be controllable or effective. Since the approval of the CAP in December 1995, the local and regional ground water elevation has risen significantly and has maintained an elevation approximately 25 feet below surface grade (bsg). Also, the vertical extent of hydrocarbon-impacted soil and ground water has been more fully assessed since the CAP was developed. The mass of adsorbed hydrocarbons now known to be within the saturated zone is significant. Recent evaluation of soil and ground water below 50 feet bsg has documented significant concentrations of dissolved hydrocarbons that must be satisfactory mitigated to achieve site closure. At this time, adsorbed hydrocarbon concentrations are known to extend to 80 feet bsg, where low concentrations suggest that 80 feet bsg is close to the adsorbed plume margin. AGE believes that the sustained increase of ground water elevation will significantly decreased the potential effectiveness of the proposed SVE/IAS treatment system to address impacted soil and Advanced Geo Environmental,Inc.