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5-2 <br />0 5.2.2 Liner and LCRS Components <br />The liner and LCRS system for the Forward Landfill are described in Section 4.1.1. A base <br />liner and slope liner system are presented below for the future Forward Landfill. There is no <br />liner/LCRS system underlying the northern portion (i.e., the Austin Road Unit) of the landfill <br />and portions of the eastern area of the landfill (i.e., Forward Unit). An intermediate liner <br />system is required over the existing refuse fill to separate Class III from Class II waste. <br />5.2.2.1 Base Liner System <br />The base liner system design included in this JTD is based on compliance with the current <br />WDRs for the existing facilities and in accordance with 27 CCR, Section 20330 <br />requirements for a Class II liner system applicable to the Forward Landfill. A Liner <br />Performance Demonstration for a Single Composite Liner (GLA, 2002) was submitted to and <br />approved by the RWQCB for final determination of the existing base liner design. A copy of <br />the demonstration is included as Appendix G. The current composite base liner components <br />for the Forward Landfill consist of (from bottom to top) (see Details 1 and 4 on Drawing 5): <br />♦ Prepared subgrade; <br />♦ A 24 -inch thick low -permeability soil (minimum permeability of 1 x 10-7 cm/sec);' <br />♦ A 60 -mil HDPE liner (textured); <br />is ♦ A 12-ounce/square yard cushion geotextile (which can be omitted provided the LCRS <br />is sub -angular to rounded); <br />♦ A 12 -inch LCRS gravel layer; <br />♦ An 8-ounce/square yard separator geotextile; and <br />♦ A 12 -inch thick protective cover soil layer. <br />The LCRS includes leachate collection swales and LCRS pipes that collect leachate from the <br />LCRS gravel layer. Spacing of LCRS lateral pipes and headers was determined by HELP2 <br />leachate generation modeling performed by GLA (see Appendix H). Leachate is collected <br />from the landfill base LCRS and pumped to one of the on-site lined leachate ponds (i.e., <br />evaporation impoundments). These ponds are discussed in Section 7.1.1. <br />5.2.2.2 Slope Liner System <br />The composite slope liner system consists of (from bottom to top) (see Details 2 and 4 on <br />Drawing 5): <br />♦ Prepared subgrade; <br />1 A GCL may be used as part of a double composite liner in sump areas. <br />Forward Landfill SWT Engineering <br />Joint Technical Document - April 2014 <br />z:\projects\allied waste\forward\five year permit rvw 2013\jtd-5 yr pr 2013\text\sec 5_final.doc <br />