Semi-analytical solution for two-dimensional contaminant transport through composite liner with strip defects

The composite liner system, which consists of geomembrane (GM) and geosynthetics clay liner (GCL), is usually used to prevent the toxic landfill leachate from migrating into the environment. However, it is difficult to evaluate the barrier capacity of the liner system, especially in the case of strip defects and two-dimensional (2-D) scale. In view of this, a 2-D model is developed to discuss the contaminant transport through flawed composite liner, and the semi-analytical solution is produced with the combination of integral transforms. The soil contaminant concentration profiles generated by this new model are shown in good agreement with the results by lab experiments and numerical simulations, which implies that the current solution can serve as an efficient and easy-to-use estimation tool by replicating numerical results with universality. A case study based on diffusion coefficient, defect rate and modeling sizes was conducted to illustrate the concentration and flux profiles under the spatiotemporal domains. Results show that the contaminant migration in landfill is mainly affected by defect rate, which can shorten the migration time by 2-3 orders of magnitude when ranging from 0 to 1. However, GCL can reduce the pollution level caused by GM failure, and concentration of SL bottom can be reduced by 23.8 times with the GCL thickness ratio increases from 0 to 0.1 at T =0.1.