Analytical Model for Contaminant Transport in Composite Liners Considering the Longevity of Barrier Components

The pollution from landfills due to the leakage of leachate is an important source of groundwater contamination. The service life of geomembrane and high-permeability leachate collection system, which play a crucial role in the long-term effectiveness of landfill liner systems, can be greatly shortened due to the complex environmental conditions of landfills. The one-dimensional analytical model of contaminant transport in geomembrane and compacted clay composite liners considering the service life of geomembrane and leachate collection system is presented. Influences of the service life of geomembrane on contaminants transport are described by changing boundary conditions. Effects of the service life of leachate collection system are achieved by the fluctuated leachate head. An investigation into the influence of geomembrane and leachate collection system service life on the breakthrough of the composite liner is presented. An empirical formula for the prediction of breakthrough time considering the service life of geomembrane and leachate collection system is proposed, which may provide the reference for the preliminary design of composite liners. The proposed solution can capture the field observed data well. Both the total flux and concentration are underestimated by about three orders of magnitude and 47.5%, respectively, compared to the model that doesn’t consider the service life of geomembrane.