Two‐Dimensional Leachate Estimation through Landfills

Abstract

A numerical model is developed to compute the time variation of leachate flow in landfills. The two‐dimensional moisture‐transport equation, along with the boundary conditions, is solved using an implicit finite difference scheme in a vertical plane. The time‐varying boundary conditions include computation for runoff, evapotranspiration, and infiltration in an unsteady state condition. The leachate accretion is obtained from the time history of moisture content. The downward leachate accretion helps develop the leachate mound at the bottom of the landfill. Solution of the saturated leachate flow equation with respect to the bottom of the landfill establishes lateral flows toward the perimeter or collection system at the landfill. Also, vertical flow through the bottom clay layer is computed using Darcy's law. The model is applied to a landfill section in New York to demonstrate the simulation of runoff, moisture content, recharge, as well as lateral and vertical flows for the field conditions in a landfill.