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Mr. Himanshu Mehta, P.E. 26 February 2008 Page 2 of 11 I landfill includes Segment 1, Segment 2, and an Infill Area located between Segment 1 and Segment 2. Segment 1 is approximately 20 acres, unlined, and was initially closed in 1990 with a cover system that included 8- to 12 -in. thick compacted clay cap. Segment 2, which is approximately 38 acres in total footprint, has a 60 -mil thick high-density polyethylene (HDPE) geomembrane single liner. The Infill Area has: (i) a single composite liner comprised of a 60 - mil thick HDPE geomembrane placed on top of 2 -ft thick compacted clay liner over a 5 -acre area between Segment 1 and Segment 2; and (ii) a 60 -mil thick textured HDPE geomembrane single liner over the 7.5 acres of the eastern side slopes of the closed Segment 1 landfill. Leachate from the lined Segment 1 eastern side slopes, Segment 2, and Infill Area is collected through a combination of leachate collection system (LCS) drainage media and HDPE pipes, and conveyed to a pump station located at the northwest corner of Segment 2. The leachate is then transferred through a force main to the West Regional Wastewater Treatment Plant for treatment and disposal. In June 2005, the Florida Department of Environmental Protection (FDEP) issued the SWDD with an expansion permit, under Permit Modification No. S031-0128769-011, for the disposal of C&D debris over the south and west slopes of the closed Segment 1 landfill using 3 horizontal to 1 vertical (3H:1 V) side slope geometry. The westward top slopes of the C&D expansion would extend to elevation (El.) 129.5 ft National Geodetic Vertical Datum (NGVD) and grade to the east at a 5 percent slope. The Segment 2 and Infill Area were also permitted to have 3H:1 V waste slopes from El. 55 to El. 145 ft NGVD. In August 2006, FDEP issued the SWDD with an expansion permit for placement of C&D debris over the north slope of the closed Segment 1 landfill using 3H:1 V side slope geometry, extending the elevation to approximately 125 ft NGVD, under Permit Modification No. S031-0128769-013. Because of the significant decline in construction activity in the County, the C&D debris placement over the slopes of the previously - closed Segment 1 landfill, under the current FDEP Permits, is presently projected to reach final grades by March 2009. A modification of the current permit is required to facilitate construction of the Class I landfill vertical expansion described below. In order to improve aesthetics at the IRCL facility, the SWDD has voluntarily elected to place cover soil and sod over portions of the C&D debris that had reached final grades in a "close -as - you -go" manner. In April 2007, the SWDD authorized Geosyntec under Work Order No. 6 to design and permit the closure system for the C&D placement on Segment 1 slopes in order to meet the closure requirements of the solid waste regulations. In June 2006, FDEP issued the SWDD with a permit for the vertical expansion that includes the construction of a liner system over the top slopes of the previously -capped Segment 1 of the Class I landfill and raising the final elevation of the lined Class I landfill from the 145 ft NGVD to approximately 185 ft NGVD (Permit Modification No. 5031-0128769-012). This additional XL07232/JL80057_IRC PROPOSAL.doc engineers 1 c _, r Hsts 1 Innovators