Risk Assesment for DAM Decharacterization

The decharacterization of dams consists of a process that eliminates the dam's function of retaining tailings and water. The decharacterization of structures built upstream (on tailings or sediments) became a legal requirement, following the occurrence of accidents involving these systems, which resulted in severe impacts on people and the environment. It is, therefore, a complex and comprehensive process, whose main focus is to preserve the safety of people and communities located downstream of its operations, as well as facilities and the environment.

This case involves the application of qualitative methodologies (Preliminary Risk Analysis – APR and Bow Tie Analysis) to support the assessment of risks associated with the decharacterization of 10 dams, dikes and pilings, located in Brazil, drained using an upstream raising method. The existing controls to mitigate each mapped risk were assessed in terms of criticality, and their functionality and effectiveness were verified. Additionally, as a result of the analysis and diagnosis carried out, actions were proposed and the implementation of new controls was recommended, in order to ensure that the decharacterization process is carried out safely, meeting applicable standards and requirements, and best practices at the level worldwide.