Application of Variably Saturated Flow Theory to Clay Cover Liners

Abstract

The movement of precipitation through the upper layers of a waste landfill may be described by a variably saturated flow model based on Darcy's equation. Such a model predicts moisture transport through clay liners for a specified site design and climatology. Example simulations are presented to highlight the difference between this approach and more prevalent moisture routing techniques. The model was used to simulate water movement through the clay barriers covering test cells at an existing research site. The simulated leakage was significantly less than that observed, suggesting that flow through macropores and other discontinuities may be dominant. A sensitivity analysis of model parameters indicates that liner thickness and saturated permeability are most critical to the leakage solution, while refuse properties have a more limited impact, especially prior to saturation of the liner.