Performance of landfill low-permeability liners for minimizing groundwater contamination

Abstract

Low-permeability liners are required at the base of municipal solid waste (MSW) landfills to minimize leachate leakage and contaminant migration into groundwater. This paper uses a two-dimensional coupled groundwater flow and contaminant transport model to examine the performance of three types of low-permeability liners specified by the current Chinese landfill standard: (1) a compacted clay liner (CCL), (2) a geomembrane (GMB) overlying a CCL, and (3) a GMB overlying a geosynthetic clay liner (GCL) on a CCL. The model simulates leachate leaking and contaminant migrating over the entire base of the landfill for the CCL and through the holed GMB wrinkles for the GMB composite liners. The performance of each type of low-permeability liners was evaluated and compared in terms of leakage rate and peak impact of chloride on the aquifer. Based on liner cases and conditions examined in this paper, the results show that the three types of low-permeability liners are not equivalent for minimizing the leakage rate and chloride impact on the aquifer. The GMB + GCL + CCL performs the best among the three low-permeability liners, and is effective for limiting the peak chloride impact on the aquifer below the acceptable level in drinking water.