Instability phenomenon at municipal solid waste landfills in Vietnam: Case study at Cam Ly landfill, Da Lat City, Lam Dong Province

In Vietnam, poor management of municipal solid waste (MSW), combined with changes in its physical and mechanical properties over time, increases the risk of instability in landfills. The instability poses significant environmental pollution risks and adversely affects infrastructure, production activities, and livelihoods of people living near these landfills. This study focuses on the Cam Ly MSW landfill in Da Lat City, Lam Dong Province, Vietnam, where the geotechnical properties of MSW and soil layers were determined through both in situ and laboratory tests. The findings showed that MSW typically has low resistivity values ( 30 Ωm), suggesting that geophysical survey is a useful tool for determining the thickness and distribution of MSW, providing valuable data for assessing landfill stability and post-closure planning. The instability type and causes at Cam Ly were analyzed using the Limit Equilibrium Method (LEM) through Geoslope/W software and the Finite Element Method (FEM) through Plaxis 2D software. The type of landfill instability identified is of the slip surface within the waste pile. The main causes of instability at the landfill were steep terrain, inadequate compaction of the MSW, and saturation due to prolonged heavy rain. Research on MSW landfill instability is essential for improving landfill management, reducing environmental impact, and safeguarding nearby communities.