One-Dimensional Transient Analytical Solution for Gas Pressure in Municipal Solid Waste Landfills

Landfill gas (LFG) is generated in municipal solid waste (MSW) landfills because of the decomposition of degradable components. Gas pressure within the landfilled MSWs is of importance as cover or landfill stability may be affected by gas pressure. This paper presents a one-dimensional transient analytical solution for gas pressure profiles in a MSW layer. This solution considers the variation of the LFG generation rate with respect to depth and decay of the LFG generation rate with time. The authors used the specified outward gas flux bottom boundary condition to simulate horizontal LFG collection systems and basal leachate collection systems serving dually as LFG collection systems. The presented solution also gives the outward gas flux from the MSW layer surface, which may be used to assist in the prediction of air quality near landfills. An application of the presented solution shows that averaging the LFG generation rate throughout the MSW layer results in a remarkable overestimation of gas pressure.