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compared to similar landfills in the State of California, this alternative merits further evaluation. 4.1.2 Source Control This alternative involves controlling additional leachate generation. Since leachate is created when water comes into contact with the solid waste in the landfill, controlling leachate generation, in part, requires limiting the amount of water that infiltrates the landfill and subsequently contacts solid waste. Since the landfill has not yet received final cover, there is a distinct possibility for more leachate to be generated and hence this alternative warrants further evaluation. The most straightforward method of limiting water from infiltrating the Corral Hollow Sanitary Landfill is to install a low-permeability cap over the landfill. The County prepared and submitted a Corral Hollow Sanitary Landfill Final Closure Plan which was prepared November 1992 and revised it in February 1995. The County is planning to close the landfill in 1995 and complete the placement of final cover by October 1995. The Final Closure Plan has been approved by the California Integrated Waste Management Board(C B) and RWQCB. Final cover at the Corral Hollow Sanitary Landfill will be applied to approximately 43 acres, which is the area that has received refuse. The final cover will consist of a 2-foot foundation layer followed by a 1-foot clay layer and a 1-foot vegetative layer. Design drawings of the final cover are contained in Appendix B. Soils for the foundation and vegetative layers will be imported. The clay layer will consist of imported clay to meet the required permeability specifications of 1 x 10-6 centimeters per second. A construction quality assurance program will be implemented so that the final cover material will be tested, constructed, and maintained to comply with the Closure and Postclosure Regulations CCR Title 14, Chapter 3, Article 7.8, Section 17774, and Subtitle D. By the time the site stops accepting waste, the foundation layer of the final cover will have been placed. Therefore, approximately 138,746 cubic yards of soil is needed to cover 43 acres with 2 feet of soil (1-foot clay barrier layer and 1-foot vegetative layer). The final landfill cover will be constructed to a minimum of 3 percent grades. These slopes are designed to provide proper drainage, prevent high velocity overland flow, and prevent slopes reversal due to landfill settlement. Final landfill slopes will be vegetated with Bromme grass upon placement of the vegetative soil layer. The vegetation will help stabilize slopes and reduce erosion. The rooting depth of the grass will not exceed the thickness of the 1-foot vegetative cover layer so the clay SAC\N�PJ0093%M390031.9BG-9 :1 Rev. 4 0 � R /95 0939-003.19 4.-2