Brasília municipal solid waste landfill: a case study on flow and slope stability

Abstract

For geotechnical and environmental reasons, landfills are positioned above the regional water table and thus are formed in unsaturated conditions. This condition can be different if the drainage system and the rain regime of the site are such that they create a level of internal liquid in the landfill. During January and February 2019, excessive movements occurred in the slopes of the Brasília sanitary landfill. A geotechnical investigation indicated that the raised leachate level caused by the clogging of the drainage system contributed to the landfilled waste movements. The limit equilibrium analysis was used to predict the relationship between leachate level and slope stability. In order to understand the process that led to the rupture, flow and stability analysis by limit equilibrium were performed. The parameters associated with flow, water retention capacity, and shear strength were obtained based on literature evaluations. In addition, data from tests were used, which allowed to define more accurately the distribution of pore pressures of liquid that led to the failure. This study allowed to define the cause of failure and also to establish the role of the drainage system in maintaining the stability of the landfill. The studies indicated that although the gain of shear strength of landfill due to the unsaturated condition is negligible, the process of flow in unsaturated medium, associated with climatic aspects, are fundamental for a medium- and long-term analysis.

Reliability of Municipal Solid Waste Landfills within the Eurocode Framework

“…In the studies reviewed in the literature, the stability of MSW landfill slopes is commonly assessed using the FS, and reliability is evaluated using β. Stability analyses are predominantly conducted using the limit equilibrium method (e.g., the Bishop method), while reliability assessments are performed using simulation-based reliability methods (e.g., the Monte Carlo method) [12][13][14][15][16][17][18].…”

“…Furthermore, they assessed the reliability index using the Monte Carlo method. Juca et al [17] investigated the stability of the Brasilia sanitary landfill slopes using limit equilibrium methods, assuming rotational failure within the waste mass. They also employed the FS as a measure of stability.…”