Flow Characteristics of Landfill Leachate Collection Systems and Liners

Abstract

The hydraulics of drainage and seepage for a sloping landfill leachate collection system were investigated. A transient liquid balance equation was developed and solved numerically. A dimensionless form of the model was used to simulate leachate flow over and through a clay liner. It was found that the model is very sensitive to changes in the hydraulic conductivity of both the liner and the drainage layer, as well as to changes in the leachate input rate. The results of the numerical model were compared to results obtained from a quasi‐steady state model and an analytical solution. The assumptions made in simplified predictive models used in design practice are discussed and their influence is assessed. The model can be used to predict seepage and drainage rates, and head build‐up on landfill liner collection systems.