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SECTION 5 Containment System The central portion of the WMU FU-04 containment system consists of a liner and LCRS on the base of the unit and a side slope liner and LCRS on the southern excavation slope. The northern slope in the central portion of the cell incorporates an interface liner to separate Class III wastes in the former Austin Road Landfill from the overlying Class II wastes to be placed in WMU FU-04. An interface liner will be placed over the southern WMU ART-03 refuse slope in the northwestern portion of the cell. The interface liner also overlies a relatively flat area between the toe of the WMU ART-03 southern refuse slope and the crest of the southern slope of the former Austin Road landfill. This relatively flat area provides a transition zone between the WMU ART-03 and WMU FU-03 liner and LCRS. The existing WMU ART-03 southern termination berm will be removed in the transition zone. The clay liner in WMU ART-03 will be transitioned to a 60-mil HDPE geomembrane and extended to meet the WMU FU-03 geomembrane liner. The WMU ART-03 gravel layer will be extended to connect to the geocomposite drainage net at the top of the WMU FU-03 northern slope. Leachate from WMU ART-03 can then flow directly into WMU FU-03. Because the transition zone is relatively flat and is underlain by refuse in the former Austin Road Landfill, a geogrid is incorporated in the transition zone to support the overlying liners and LCRS systems. Finally,the northeastern portion of WMU FU-04 is located on the top deck of the former Austin Road Landfill. The interim final cover serves as the base liner for this portion of the cell. A LCRS will be placed over the interim final cover. Leachate will drain to header pipes located along the southern termination berm. Once WMU FU-04 is constructed and approved for disposal, the header pipes will route leachate to the base of the central portion of WMU FU-04. Only Class III wastes will be placed in the northeastern portion of WMU FU-04. The base liner system for the central portion of WMU FU-04 consists of the following, from bottom to top: • Prepared subgrade; • Minimum 2-foot thick compacted clay liner with a maximum field hydraulic conductivity of 1 x 10-7 cm/sec; • 60-mil, double-sided textured HDPE geomembrane liner; • Cushion geotextile; • One-foot thick blanket gravel and pipe network drainage layer with a minimum hydraulic conductivity of 0.1 cm/sec; • Nonwoven geotextile filter fabric; • One-foot thick protective operations layer The side slope and interface liner system consists of, from bottom to top: FU-04 REPORT.DOC 5-1