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• 7.2.4.3 ESTIMATED COST FOR WORST CASE RELEASE MITIGATION In accordance with 27 CCR, Section 20380(b), Forward will establish and maintain assurance of financial responsibility for initiating and completing corrective action for all known or reasonably foreseeable releases from the facility. Recognizing the limited thickness of the vadose zone and the ephemeral occurrence of surface water at the site, it is expected that the worst case release from the facility would be to groundwater. A corrective action program (CAP) has been implemented along the northern (downgradient) border of the existing Austin Landfill. Since groundwater flow from the existing Forward Landfill is northerly toward the existing Austin Road Landfill, should a release occur from the existing Forward Landfill•it would be largely contained by the Austin Road Landfill CAP. However, since northeasterly component of groundwater flow is sometimes identified in the area, it is possible that some part of a new release could migrate east of the proposed expanded Forward Landfill, and outside the current Austin Road Landfill CAP containment area. If this were to occur, it is likely that this would necessitate expansion of the • CAP. Such an expansion could include installation of additional groundwater extraction wells, installation of aquifer recharge systems, and installation of additional gas collection wells. Assuming that an area of impacts is identified along the northeast side of the Forward Landfill, and assuming that the area of impact is approximately half that of the impacts currently existing at the Austin Road Landfill, the additional CAP measures that could be required might include: installation of 2 additional groundwater extraction wells, installation of an aquifer recharge basin, and improvements to the gas extraction system. As shown in Table 20, it is estimated that the costs to implement these additional CAP measures at the Forward Landfill would be approximately $155,469. This cost estimate does not include costs for improvements to the gas extraction system as there are financial assurances for these costs included in the final closure costs (see Table 8 of Appendix L). This total is intended to provide a basis for compliance with 27 CCR, Chapter 6, Subchapter 2, Article 4 financial assurance requirements. This cost estimate takes into account typical well construction, earthworks, and appurtenant costs. • Forward Landfill JTD 7-9 L:\Allied\2000.193\Reports\td:Sec-7.0:05/24/02 BRYAN A.STIRRAT 6 ASSOCIATES