Gas Pressure Model for Layered Municipal Solid Waste Landfills

Abstract

A mathematical model for calculating gas pressure profiles in layered landfill systems is presented. Solutions to scenarios considering a zero-pressure top boundary condition and a zero gas flux or fixed gas pressure bottom boundary condition are presented. Two cases, specified gas pressure and specified inward gas flux, are addressed for scenarios involving horizontal gas collection systems. A series of application examples demonstrate how the proposed model can be used to investigate the influences of (1) variation of gas generation rate with respect to depth and time, (2) soil covers, (3) horizontal collection layers, and (4) geomembrane and geosynthetic clay liner covers on gas pressure distribution in landfills. The proposed model provides a useful tool to landfill engineers in designing landfill gas management systems and in particular when selecting and specifying gas collection system spacing and pumps.