Evaluation of the effectiveness of a cover with capillary barrier effect to control percolation into a waste disposal facility

Abstract

The goal of an instrumented experimental plot constructed on the Saint-Tite-des-Caps landfill site was to evaluate the field behaviour and performance of a cover with capillary barrier effect (CCBE) to control water percolation. The CCBE consists of a layer of deinking by-products (DBP) on top of a layer of sand overlying a gravel layer. The DBP layer acts as a seepage control layer to control the rate of seepage that can reach the top of the capillary barrier. Analysis of the field data shows that the seepage control layer consisting of DBP remained nearly saturated and controlled percolation to the desired level. In addition, for the first year of monitoring, the diversion length determined from field data was very similar to that estimated by the analytical solution that was used for the design of the experimental plot. Afterwards, the diversion length increased due to a decrease in the rate of seepage caused by settlement of the seepage control layer, which caused a decrease in its saturated hydraulic conductivity. At all times, the flows that reached the gravel layer at the toe of the experimental CCBE were, for all practical purposes, lower than the maximum seepage rates required by the most restrictive landfill regulations.