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1-8 and/or equipment that will be allowed within the staged (partial) closure areas will be for post-closure monitoring and maintenance. 1.7 Post Closure End Use The post closure end use for the FL, which includes all staged closure areas, is non-irrigated open space. As the staged closure areas are completed, native vegetation will be planted which will provide erosion control. 1.8 Closure Cost Estimate In order to establish the basis for the proper level of funding for a landfill to be closed in increments over its active life, a closure sequence or staging plan must be prepared. T#-, +In order to meet 27 CCR requirements, the cost estimate must be based on the maximum extent or area of the landfill that would ever require 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„e.—an updated 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 20082013 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. The back-up data/documentation in support of the closure cost estimate is included in Attachment 3. 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 fer the lined and unlined PE)FtOORS of the landfill. For the lined peFtiens of the landfill the final eever will consist of a minimurn two feet thick foundatien laye-r (one foot assumed to be in plaGe) composed of randem sail materials; a barrieF laye-r hrane) overlain by with high E9�}S a-ssynthetic �a— L��—g2Amei�r�rm-rc�v overlain density polyethyleRe (HDPE) geesynthetie drainage strips; and a two feet veget-ative layeF of Fandern seals. Fer the unlined peFteORS of the landfill the final eever will GeRSiSt ef a minimum twe feet thiek foundation layer (one feet assumed to be On plaee) coMpesed of FandGM materials; a ene feet thiek lew permeability layers with a permeability of 1x4:0 6 GFFI/seG eF less; and a twe feet vegetative layer ef randem seffils. Engineered alternative GeveF syste � a g detaileddesignsfor the individual closure stages Based on the final cover design evaluation (GLA, 2005), it was determined that a four-foot thick monolithic (ET) alternative final cover section composed of on-site soils will satisfy the regulatory requirements for an Forward Landfill SWT Engineering PCPCMP Amendment No.4-May 2013 z:\projects\allied waste\forward\five year permit rvw 2013\itd-5 yr pr 2013\appendices\app a-pcpcmp 2013\text\pcpcmp amend 2013.doc