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� A 19 November 2009 AGE-NC Project No. 02-0950 Page 11 of 13 • Since initiation of the ground water monitoring program, ground water elevations have ranged from approximately 6 to 12 feet below the NAVD and depths to ground water have ranged from approximately 14 to 20 feet btoc. Between December 2005 and May 2009, ground water flow direction at the site was inferred to be towards the southeast at low hydraulic gradients ranging between 0.002 ft/ft and 0.01 ft/ft.Ground water elevation figures depicting ground water flow directions and gradients from October 2003 to May 2009 are presented in Appendix E. • Prior to corrective action (i.e. excavation), the lateral extent of petroleum hydrocarbon- impacted soil appeared to extend from the core area of the plume (i.e. soil boring B2) approximately 33 feet towards the southwest, approximately 13 feet towards the north, approximately 19 feet towards the west and approximately 9 feet towards the east. The vertical extent of petroleum impacted soil appears to extend to approximately 36 feet bsg at B2 and MW-2.The pre-excavation lateral and vertical extent of impacted soil is depicted in Figures 6 through 9. • Prior to excavation,AGE estimates that 4,292 pounds(lbs),or 687 gallons of total petroleum hydrocarbon appeared to remain in soil at the site. The assumptions for the calculation of hydrocarbon mass remaining in soil is presented in Appendix H. • Approximately 521.22 tons (equivalent to approximately 417 cubic yards) of petroleum hydrocarbon-impacted soil was excavated and removed from the site in July 2007.Based on mass and volume calculations(Appendix I),AGE estimates that approximately 3,287 pounds (equivalent to 526 gallons) of petroleum hydrocarbons were removed from the site as part of corrective action measures. • Following corrective action,AGE estimates that soil impact at the site was reduced to 1005 pounds remaining beneath the site.Utilizing Figures 10 and 11,the lateral and vertical extent of petroleum hydrocarbon-impacted soil remaining at the site appears to be limited beneath the former excavation area at depths between 25 feet and 36 feet bsg.Laterally,TPH impact is evident at the sidewalls of the former excavation and appears to extend approximately 5 feet toward the north, east and west and 15 feet south of the former excavation limits. • Laboratory analysis of ground water samples historically detected TPH-g,TPH-d and BTEX from monitoring wells MW-2 and MW-7. Additionally, TAME was sporadically detected from wells MW-2 and MW-7, while 1,2-DCA was sporadically detected only from well MW-2. Ground water analytical data is summarized in Table 6. • Dissolved petroleum hydrocarbon compounds were generally not detected from ground water samples collected from wells MW-1 and MW-3 through MW-6, and should be considered non detect wells for all constituents of concern. Additionally, following the July 2007 corrective action at the site, dissolved TPH-d and BTEX concentrations also decreased at wells MW-2 and MW-7 to non detectable levels,while TPH-g concentrations declined to Advanced GeoEnvironmental,Inc.