Estimation of Landfill Settlement Using Different Models

Abstract

AbstractEstimation of settlement is a matter of prime importance for the maintenance of municipal solid waste (MSW) landfills. Settlement of MSW landfill used to take place for a long duration, and the total displacement can approach up to 30% of original landfill height. The main phases of settlement in MSW landfills are initial compression, primary compression, and long-term secondary compression. The mechanisms involved in the waste settlement are densification, placement of finer particles in the voids of larger size particles, physical–chemical change, and bio-chemical decomposition. The factors which affect the settlement values are initial density or void ratio of the solid waste, placement sequence, decomposable materials, leachate levels, and landfill operation methods. A large value of settlement after non-functioning of the landfill is undesirable from management angle as it can cause surface ponding, development of cracks in clay liners (such as compacted clay liners), and tear in the geomembrane layer. Therefore, understanding of total landfill settlement is necessary for landfill design and the future construction over it. Different prediction models are used to determine the displacement of a typical MSW landfill. These models are based on soil mechanics-based model, rheological model, empirical model, and biodegradation-induced settlement model. The model parameters are taken from data available in the published literature. Measured settlement data from each model is displayed as settlement-versus-time graph. In the study, it can be seen that the predicted settlement magnitude differs notably depending on the prediction model used and the selection of parametric values. Marques (2001) model was found out to predict the settlement more closely as it considers all the mechanisms involved in the settlement in good proportion.KeywordsLandfillsMunicipal solid wastesSettlementModelsPredictions