A Consequence-Based Tailings Dam Safety Framework

Despite the development of tailings dam safety standards, guidelines, bulletins, risk assessment tools and management tools, tailings dam failures with high consequence have occurred at a similar rate over the last ten years as they did before. At the time of writing this paper (January 2019) another tailings dam failed in Brazil resulting in a large number of fatalities. The authors of this paper concluded that the main underlying reasons for recent failures of large tailings dams is a systematic failure to recognize the potential geotechnical hazards, their consequences and trigger mechanisms together with failure to act when the risk is recognised. The individual prescriptive measures currently applied during some stages of tailings projects to control the risk, such as scaling the design loads based on the consequence, are not considered sufficient to overcome the systematic deficiency. Instead, a holistic dam safety management system overarching all phases of tailings dam projects from planning to closure is required, including the management of the facilities. The authors suggest the widely used and understood consequence-based principles should be extended to cover the entire life span of tailings dams, including the dam safety management system. This approach is an extension of the tailings dam safety frameworks presented in MAC (2017) and Morgenstern (2018) and may provide the minimum requirements for all relevant aspects of the tailings dam safety framework. The suggested approach would respect the risks posed by the tailings dam while taking into account the economic aspects of the project. The approach should considered by the ICOLD Technical Committee for Tailings Dams and Waste Lagoons and the International Council on Mining and Metals.

Herza, J., M. Ashley, J. Thorp and A. Small. 2019. “A Consequence-Based Tailings Dam Safety Framework,” in Proceedings of the 87th Annual Meeting of International Commission on Large Dams (ICOLD), 9-14 June 2019. Ottawa, ON: Canadian Dam Association.