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closure. Since the FL is proposed to be closed in six stages, the basis of the closure cost estimate is the largest area requiring closure over the life of the landfill which, based on Table 1, is 187.6 acres. The active fill area will be maintained to an area equal to or less than this coverage area. As shown on Table 1, the maximum closure area will decrease over time. Therefore, the closure cost estimate can be reduced once Stage I is completed and again after Stage VII is completed. The cost estimate presented in Table 3 is a new closure cost estimate for this PCPCMP Amendment and serves as the basis to fund the closure account over the life of the landfill. The closure cost estimate reflects third -party costs in 2008 dollars. The closure features are grouped into categories for convenience in presenting the cost estimate. A brief description of the components included in each category is given below. 1.8.1 Final Cover Based on the proposed final grading contours, the approximate area which will require placement of final cover is 187.6 acres. The proposed final cover for the FL will consist of two different covers, one each for the lined and unlined portions of the landfill. For the lined portions of the landfill the final cover will consist of a minimum two -foot thick foundation layer (one foot assumed to be in-place) composed of random soil materials; a barrier layer consisting of a synthetic cover (i.e., a 40 -mil LLDPE geomembrane) overlain by with high density polyethylene (HDPE) geosynthetic drainage strips; and a two -foot vegetative layer of random soils. For the unlined portions of the landfill the final cover will consist of a minimum two -foot thick foundation layer (one foot assumed to be in-place) composed of random soil materials; a one foot thick low -permeability layers with a permeability of 1x10-6 cm/sec or less; and a two -foot vegetative layer of random soils. Engineered alternative cover systems may be proposed to address specific engineering requirements that arise in the course of preparing detailed designs for the individual closure stages. The cost of constructing the final cover includes site preparation, site grading, final cover placement and settlement monument installation. 1.8.2 Final Cover Construction Ouality Assurance Monitoring and Testing Costs for CQA include the final cover placement tests, inspections and reporting. 1.8.3 Drainage Control System Costs for the drainage control system include the construction, removal and replacement of inlet structures and down drains over a 187.6 -acre area. Construction of the permanent drainage control system for the current fill area is complete. As operations expand, the drainage control facilities for the upcoming fill area are installed concurrent with liner construction as part of normal landfill 8 SWT Engineering Forward Landfill - PCPCMP Amendment (Z:\PROJECTS\Allied Waste\Forward\JN81013 5 yr Review Plan\JTD Amd 3 PCPCMP Amd 3 Dec 08\PCPCMP Amend 3 121808.doc; Amendment No. 3: 12/18/08)