Storage Capacity and Slope Stability Analysis of Municipal Solid Waste Landfills

Landfill storage capacity and slope stability are among the most significant engineering concerns in municipal solid waste (MSW) landfill operation. Factors that affect the landfill storage capacity and slope stability are interrelated. Research on the effects of settlement on the landfill storage capacity and stability is insufficient. In this article, storage capacity and slope stability analysis of MSW landfills was conducted on a typical valley-type landfill. A practical approach was utilized to obtain the landfill settlement and storage capacity with the one-dimensional compression model that considered different MSW compression mechanisms and the compressibility property of MSW. The influences of settlement over time on the landfill storage capacity and stability were reflected by changing the landfill scheme and the MSW property including shear strength and bulk unit weight. The factor of safety of the deformed landfill slope was estimated by the limit-equilibrium method with consideration of varied bulk unit weight and shear strength indices for MSW with a high food waste content. The quantitative effects of operational practices, including MSW filling rate, final height of MSW body, designed front slope angle and main leachate level, on the landfill storage capacity and stability were investigated. The results showed that: (1) the main leachate level is of importance to the landfill storage capacity and stability; (2) reducing the filling rate of MSW has multiple advantages: the requirement to control the main leachate level thickness in the MSW body can be diminished, more waste can be filled, and the stability of landfills can be sustained; (3) although the landfill storage capacity can be effectively improved by increasing the height of the MSW body, at the same time, it becomes more important to control the main leachate level in the MSW body to sustain the landfill stability; and (4) reducing the slope angle will help weaken the requirement of the main leachate level to sustain the landfill stability, but not necessarily decrease the landfill expansion ratio. In addition, the landfill stability assessment should be associated with the construction stage, because the factor of safety varies with time due to the development of landfill settlement and the biodegradation process.