Modelling Percolation Through Bentonite-Sand Monolithic Landfill Covers Under Climatic Variability: Influence of Cracks and Barrier Composition

Abstract

Bentonite sand mixtures are frequently used as landfill cover systems owing to their low hydraulic conductivity and self-healing properties. These typical barriers play a crucial role in minimizing the percolation of rainwater in municipal solid wastes. However, under the effect of varying climatic conditions, especially in arid regions, desiccation cracks may be induced in these barriers, increasing the percolation of rainwater through these barriers and causing a severe disruption in environmental conditions. It is, therefore, of primary importance to investigate the effectiveness of various bentonite sand compositions as a landfill barrier under such conditions. In the present study, an effort has been made to determine the effectiveness of three different bentonite sand mixtures as a landfill cover under a given precipitation condition. A numerical model of a one-dimensional monolithic landfill cover system was developed to determine the effectiveness of these mixtures. The percolation behavior through these covers was studied with and without cracks under the given precipitation condition. The results indicate that a higher bentonite content shows lower percolation under intact and cracked conditions compared to other monolithic covers. The proposed model provides a framework to assess percolation through landfill covers under cracked conditions, thus helping to improve the effectiveness of engineered containment systems.