Effect of Liner Consolidation on Contaminant Transport Through a Landfill Bottom Liner System
In municipal solid waste landfills, a triple-layer composite liner consisting of a geomembrane liner (GML), a geosynthetic clay liner (GCL) and a compacted clay liner (CCL) is commonly used at the landfill bottom to isolate the leachates from surrounding environment. This paper presents a numerical investigation of the effect of liner consolidation on the transport of a volatile organic compound (VOC), benzene, through the GML/GCL/CCL composite liner system. The numerical simulations were performed using the model CST3. The performed numerical simulations considered the impact of consolidation on contaminant transport for a GML/GCL/CCL liner system. The simulation results indicate that, depending on conditions, consolidation of the GCL and CCL can have significant impact on the transport results of benzene, both during the consolidation process and long after the completion of consolidation. The traditional approach for the assessment of liner performance neglects consolidation of the liners and fails to consider the consolidation-induced transient advection and concurrent changes in material properties and, therefore, can lead to significantly different results.