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GeoHydrologic Consultants, Inc. was approximately 87,646 pounds. This amount is limited to the average concentration of hydrocarbons in the borings used to calculate the original mass; therefore the true original mass is most likely higher. Soil hydrocarbon concentrations have significantly decreased based upon a total of 191,127 pounds of hydrocarbons being remediated by the vapor treatment system from system start-up on April 26,2001 through November 26, 2007. Based upon the original mass of hydrocarbons (87,646 pounds - March 1999),and the mass of hydrocarbon removed by the soil vapor system (191,127 pounds),the remediation of the vadose zone hydrocarbons has had substantial success and appears to be approaching asymptotic concentrations. In the fourth quarter 2007, the highest concentration of TPHg, benzene and MTBE in groundwater were found in MW-11 (11,100 µg/L, 3,760 µg/L, and 305 gg/L, respectively); alcohols and oxygenate results indicated none of these compounds(except MTBE)were detected above the laboratory detection limit, with the exception of TBA in well MW-I 1 at 155 µg/L. The concentrations of TPHg, benzene, and MTBE in groundwater for the Fourth Quarter 2007 are shown in Figures 3,4, and 5 in Appendix A, respectively. 3.0 WELL ABANDONMENT, UST REMOVAL, WELL REINSTALLATION AND SOIL SAMPLING ACTIVITIES In December 2007, GHC performed oversight of Tafoya and Associates of Chino, California for the scope of work of vapor and groundwater well abandonment;cutting and plugging the portions of conveyance piping connecting the abandoned wells; UST, dispenser, and fuel removal;soil sampling beneath USTs,dispensers, and fuel lines and from soil stockpiles; installation of new vapor and groundwater wells as a replacement for the abandoned wells;and restoration of the conveyance piping for the new extraction wells network. 3.1 Well Abandonment- Piping Removal Existing wells MW-11/VW-3, VW-2-SNW-2-13, and MW-12, which were installed within the UST pit, and the related conveyance piping from MW-3, VW4, and MW- 10/VW-1 in the proximity of the excavation areas(Figure 2)were disconnected, severed and removed by Tafoya. The existing lines inside of the proposed excavation area were cut back and capped to prevent any damage and plugging of the conveyance lines. As explained later in this report,these lines (except VW-2-SNW-2-D which was not reinstalled)were plumbed and reconnected to the re-installed wells after the USTs were removed and the excavation was backfilled and compacted. 3.2 Well Abandonment Well destruction permits were obtained prior to conducting well abandonment activities. A copy of the signed off well destruction permits are included in Appendix G. Mr. TOC 172 UST Removal Report Final Page 7