Leachate Collection in Landfills: Steady Case

Abstract

This paper analyzes the performance of landfill leachate collection systems with low‐permeability soil liners under steady‐state conditions. Algebraic equations and graphs are presented for predicting the average and maximum saturated depth on the liner, the location of the maximum saturated depth, and the leakage rate. These equations and graphs are developed from numerical solutions of the governing differential equation. Some surprisingly simple relationships are shown to be applicable over much of the practical range. In general, saturated depth over the liner is sensitive to four parameters: the liner slope, the drainage length or drain spacing, the saturated hydraulic conductivity of the drain layer, and the difference between the impingement rate on the liner and the liner's hydraulic conductivity. Under normal conditions, leakage rate is sensitive only to the hydraulic conductivity of the liner. Within the practical range, liner thickness has little effect on either saturated depth or leakage rate.