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19 November 2009 AGE-NC Project No. 02-0950 Page 8 of 13 approximately 6 feet bsg. The clean overburden from the surface to 6 feet bsg was field screened (visual,odor and texture)and measured with an organic vapor meter(OVM)equipped with a photo- ionization detector((PID: Thermo Environmental 580, 10.0 eV,calibrated to isobutylene)and then stockpiled separately from any petroleum hydrocarbon-impacted soil. The petroleum-impacted soil encountered thereafter was excavated and immediately placed in trucks and transported to Forward Landfill in Manteca, California for disposal. Based on manifest records,approximately 521.22 tons(equivalent to approximately 417 cubic yards) of petroleum hydrocarbon-impacted soil was excavated and removed from the site. Revisiting the previously reported mass and volume calculations,AGE estimates that approximately 3,287 pounds (equivalent to 526 gallons) of petroleum hydrocarbons were removed from the site during the soil excavation procedures. The mass and volume calculations are presented in Appendix I. Analytical results of excavation soil samples are presented in Table 2; Figure 3 illustrates the approximate location and lateral extent of the excavation. A report of findings (Soil Excavation and Disposal Report, dated 26 September 2007)was prepared by AGE and submitted to the EHD and RWQCB. Between 10 and 13 July, and 16 July 2007, the excavation was backfilled by L&B with pea gravel to approximately 6 feet bsg, clean native soil removed and stockpiled from the excavation was backfilled to approximately 2 feet bsg and with road base material to surface grade. The volume of clean overburden returned to the excavation as backfill was approximately 89 cubic yards. The excavation area was compacted in 1-foot lifts from approximately 5 feet bsg to the surface by L&B utilizing a Bomag BW-177PDH-3 single-drum compactor. 5.0. ASSESSMENT OF HYDROCARBON-IMPACTED SOIL Between October 2002 and March 2008, six soil borings (B1 through B6), one cone penetrometer test boring (CPT-1) and seven ground water monitoring wells (MW-1 through MW-7) were installed/advanced at the site as part of an ongoing subsurface petroleum hydrocarbon investigation. Additionally, two soil borings (Alta EM B5 and Alta EM B6) were advanced off-site towards the north by Alta EM Inc. to depths of 23 feet bsg for collection of soil and grab water samples Analytical results of soil samples are summarized in Table 1. To date, a total of forty three (43) soil samples (including those from the UST removal activities) were collected at depths ranging between 9 and 50 feet bsg and submitted for laboratory analysis of petroleum hydrocarbon constituents. Based on the above laboratory results, TPH-g, TPH-d and BTEX were detected in a total of 10 soil samples. The most significant TPH-g and TPH-d soil impact was encountered from boring B2-15 feet at concentrations of 22,000 mg/kg and 7,500 mg/kg, respectively. Additionally, the greatest BTEX concentrations were encountered from B2-15 at 1.1 mg/kg benzene, 460 mg/kg toluene, 320 mg/kg ethylbenzene and 1,830 mg/kg xylenes. Advanced GeoEnvironmental,Inc.