Contaminant Transport through a Compacted Clay Liner with the Consideration of Consolidation Effects

This paper presents the results of a numerical study pertaining to the significance of consolidation of a compacted clay liner (CCL) on contaminant transport through the CCL serving as the barrier component in a solid waste impoundment bottom liner system. Numerical simulations were conducted using the validated CST2 model, which accounts for one-dimensional coupled large strain consolidation and contaminant transport in saturated porous media. Simulation results indicate that CCL consolidation can play a significant role on contaminant transport through the CCL during the entire 40-year evaluation period. Analyses based on traditional advective-dispersive transport neglect the transient advective transport and changes in CCL properties caused by consolidation process and, therefore, can lead to significantly different results. For the simulations with initial CCL thickness of 0.5, 1, and 1.5 m, consolidation is shown to decrease the steady-state contaminant mass flux by 59%, 67%, and 71%, respectively, and thus ignoring consolidation would produce conservative transport result for single CCL.