Feasibility of Monolithic Covers for MSW Fills in Humid Climate

This paper presents the results of a study on the utilization of monolithic covers of local soils for municipal solid waste (MSW) fills in the State of São Paulo, Brazil, by means of simulations with a numerical code using unsaturated soil parameters and local climate data. Two sites were studied - Campinas and Ilha Solteira - located in regions with high demand for MSW disposal sites. A lateritic clay and a lateritic clayey sand were selected due to their availability in the regions. Water retention curves for compacted specimens of the two soils were obtained by the filter paper method and fitted to the van Genuchten model, as required by the employed code, Visual Hydrus. The influence of compaction water content on cover performance was investigated by determining water retention curves at four compaction water contents for the lateritic clay and two compaction water contents for the lateritic clayey sand. Real precipitation and evaporation data for one year were used. Simulated monocover thickness were 1 m and 4 m. Results showed that, for both sites, 1-m-thick covers meet the requirement of maximum annual percolation rate of 30 mm/year, when the soil is compacted at the optimum or wet of optimum water content. There is, therefore, the possibility of using monocovers with performance comparable to prescriptive compacted soil covers for the studied conditions.