A risk assessment tool for tailings storage facilities

Abstract

The recent occurrence of several major failures of tailings storage facilities (TSF) has caused the mining industry to focus on significantly improving the engineering and management (design, construction, operation and monitoring) of these structures to reduce their environmental impact. This effort is led by the Mining Association of Canada, which mandates the application of risk assessment in tailings management. Due to the very complex nature of TSF, such as phased design and construction, continuous operation, and evolving guidelines and practices over many years, the application of traditional risk assessment tools has limitations. A risk assessment tool specifically developed for TSF management is presented. This tool is based on the work of Silva et al. from 2008 that relates the annual probability of failure to the factor of safety and the level of engineering. This relationship was modified to reflect current practice. The annual probability of failure was then combined with a consequence rating to produce a rational and quantifiable evaluation of risk. The risk assessment tool provides detailed information on the level of practice of a structure, the corresponding annual probability of failure as well as the associated risk. Validation of the tool included application to a recent well-documented failure.