Modelling of contaminant transport in heterogeneous vertical barrier

Abstract

AbstractVertical barrier technique is an ideal candidate for site contamination control. In practical application, the characteristic of vertical cut‐off wall is heterogeneous with permeability decreases with depth due to the increasing geostatic stress. In this study, a numerical model was established considering the coupling effect of groundwater flow and contaminant transport considering depth dependent permeability. The results showed that a heterogeneous barrier with variable permeability can reduce the breakthrough time by 63.7% compared to a fixed permeability barrier. The contaminant concentration inside the wall was up to 10 times higher than outside. Shallow leakage occurs where the horizontal migration is dominated by advection. The distribution of pore‐water pressure in the system after the installation of high‐density polyethylene (HDPE) membranes significantly reduced the shallow convective effect by reducing up to 90% pore‐water pressure. Reinforcing the vertical barrier wall using HDPE membrane can effectively prevent the shallow leakage caused by the heterogeneity.