Modeling Lateral Gas Transport in Soil Adjacent to Old Landfill

Abstract

Lateral migration of landfill gases in soils surrounding old (closed) municipal landfills can lead to explosion hazards and damage to vegetation. Landfill gas production and migration is controlled by microbial activity and soil physical properties such as gas (air) permeability, gas diffusivity, and atmospheric pressure variations. Gas diffusivity and air permeability were measured on undisturbed samples collected at an agricultural field adjacent to an old Danish municipal landfill. Empirical expressions for predicting gas diffusivity and air permeability from soil-water content were fitted to the data. An empirical expression for calculating methane oxidation rate as a function of soil temperature was developed using site-specific measurements of methane oxidation rate. The transport and degradation parameter expressions were incorporated into a numerical model for simulating landfill gas transport, using soil-water content, temperature, and soil organic matter content as measured input parameters (functions of time and soil depth). Previous measurements of landfill gas (CO