Two of most important functions of a landfill cover are to minimize the infiltration of water and to control the emission of landfill gas. Compacted clay liner (CCL), geosynthetic clay liner (GCL), and geomembrane (GM) are the three major types of hydraulic barrier materials used in the bottom lining systems as well as cover systems of landfills. However, it is well recognized that clay liners crack upon desiccation. The cracked liner may enhance the capacity to conduct fluid, which not only increase the infiltration of the downward moving water but also the emission of upward moving gas. Laboratory air permeability tests were conducted to quantify the rate of air passing through desiccated clay liner specimens. In addition, the equilibrium water content of clay liners in the field condition is also studied. The results show that desiccated clay liners may allow considerable amount of landfill gas to pass through. In addition, the air permeability of desiccated GCLs are much higher than that of desiccated CCLs. Accordingly, it is suggested that geomembranes should be used to contain landfill gas for landfills located in areas where landfill gas emission are to be controlled effectively.
Menu