Double-liner system

FIG. 25-76 Schematic of an FML plus compacted-soil double-liner system for a landfill, (Drawing not to scale.) (U.S EFA, EFA/530/SW-S5-012 Washington, DC., 19S5 EiomEieerrmn, H M., Standard Handbook of Hazardous Waste Treatment and Disposal, AtcGiutu-H) //, 19SS. )... 

Regulatory requirements for hazardous waste landfill double-liner systems are given in 40 CFR 264.3 The minimum liner system design standard generally considered to meet these requirements includes, from top to bottom4 ... 

Clay liners, synthetic liners, or combinations of both are required in landfills. Figure 26.1 depicted the synthetic/composite double-liner system that appears in U.S. EPA s MTG. As explained... 

FIGURE 26.16 Profile of the MTG double-liner system. (Adapted from U.S. EPA, Requirements for Hazardous Waste Landfill Design, Construction, and Closure, EPA/625/4-89/022, U.S. Environmental Protection Agency, Cincinnati, OH, August 1989.)... 

Double-liner systems are more prone to defects in the structural details (anchorage, access ramps, collection standpipes, and penetrations) than single-liner systems. 

The amount of mass of each organic compound entering the aquifer via the double-liner system was calculated using these initial leachate concentrations. There was a continuous 12.2-meter head driving flie leachate through the liner. Leachate was predicted to... 

The minimum prescriptive (regulated) cross sections for liner systems for MSW and HSW disposal in the United States are shown in Fig. 10. As shown in Fig. 10a, the minimum requirements for MSW include a single composite liner overlain by an LCRS. Thus, an LDS and bottom liner are not required for MSW disposal in the United States. However, a double liner system consisting of an LDS sandwiched between a bottom composite liner system and a GML top liner is required in the case of HSW disposal (Fig. 10b). TheLDSandbottomlinerintheHSW requirements provide a level of redundancy in the containment that is required due to the particularly hazardous nature of HSW. 

Double-liner systems proposed by the United States Environmental Protection Agency guidelines. The leachate collection layer is also considered to function as the geomembrane protection layer, (a) The flexible membrane liner, FML/composite double liner, (b) FML/compacted soil double liner (after Mitchell, 1986). With the kind permission of the Geological Society. 

The landfill must have a double liner system that can prevent any migration of wastes out of the landfill to the adjacent soil, groundwater, or surface water. The liner system must include a leachate collection and removal system between the two liners. 

Modem hazardous-waste landfills typically have dual leachate collection systems, one located between the two impermeable liners required for the bottom and sides of the landfill, and another just above the top liner of the double-liner system. The upper leachate collection system is called the primary leachate collection system, and the bottom is called the secondary leachate collection system. Leachate is collected in perforated pipes that are embedded in granular drain material. 

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