Evaluation of performance of double composite landfill liner

Performance of landfill liners is evaluated with respect to leakage rate and mass flux. The composite liners considered in this study include a single geosynthetic clay liner (GCL), the Subtitle D liner system, the Wisconsin NR500 liner system, and the recently utilized double composite liner system, which consists of a geomembrane (GM) - GCL - GM - compacted clay layer (CCL). The leakage rate through circular and long defects in the GM of the landfill liners was analyzed using analytical equations and numerical models. For the mass flux criterion, the analyses of contaminant transport through defects in the GM component of liner systems and diffusion of volatile organic compounds through intact landfill liners were conducted using numerical models. The comparison shows that the double composite liner systems are superior to the other kinds of liner systems according to the performance-based evaluation.