Date of Award

Winter 1994

Document Type


Degree Name

Doctor of Philosophy (PhD)


Civil & Environmental Engineering

Committee Director

A. Osman Akan

Committee Member

Joseph M. Marchello

Committee Member

Billie M. Reed


Numerous processes occur in landfills which lend themselves to modeling. Many of the processes are mutually interdependent. An unsteady numerical model is developed combining the major processes. The three-dimensional moisture transport equations and boundary conditions are solved using an implicit finite difference scheme. The boundaries are determined through a two-dimensional runoff model for the landfill surface and a one-dimensional leachate liner flow model at the bottom of the landfill. The runoff model accounts for evapotranspiration, runoff, infiltration, and leachate recirculation. Richard's equation is solved for saturated and unsaturated vertical flows and Darcy's Equation is solved for lateral flow between adjacent saturated landfill cells. Results of the moisture flow are used to solve contaminant production and transport equations. Contaminant production uses moisture flow and previous leaching history to generate source terms. The source terms and recirculated contaminants are used to implicitly solve contaminant transport equations which account for advection, diffusion, and dispersion of the contaminant. Landfill temperatures are predicted by solving an energy equation implicitly. Temperatures are combined with moisture content and gas production history to determine gas generation. The model is applied to three Wisconsin lysimeters and a Kentucky landfill to demonstrate the simulation of leachate and contaminant production and transport. Comparison to the HELP water balance model is also done for a Wisconsin lysimeter. The model is also applied to an existing landfill to demonstrate the gas generation portions of the model.