Developing a plan for Closure Surveillance and Long-Term Stewardship

January 7, 2026

Responsible closure of a tailings or mine waste facility requires transparent and justifiable decision making based on sound science and engineering practices. This paper explores concepts for responsible closure design and stewardship using a risk-informed approach. The authors discuss how surveillance and stewardship requirements can change at closure by considering questions such as: how many instruments are required for adequate post-closure performance monitoring, how do the requirements for inspections and independent review change, what can we do as part of closure design to reduce the surveillance requirements, or how do we future proof the closure designs of structures against the evolving state of engineering practice? This paper aims to link knowledge-base components of site characterization, design basis, operational history, and performance monitoring, with consideration of potential failure modes, controls, and verification activities, to the requirements for responsible closure stewardship. An effective closure surveillance and stewardship strategy (including independent review and assurance mechanisms) should be tailored to address the unique challenges and requirements of a site as it transitions from operations to closure. Surveillance requirements can and will change over the long-term; for example, instruments that may have been vital for verifying dam performance during operations, may no longer be required or may be very different to verify the performance of closure design controls. It is also important to consider how often such instrumentation will need to be replaced. The authors also explore the differences between sites with long-term site activities, such as water treatment where staff are present, and those without, which have minimal on-site human presence. The paper outlines elements for responsible decision making to support the long-term safety and sustainability of tailings and mine waste facilities.

Willms, D., Witte, A. 2025 "Developing a Plan for Closure Surveillance and Long-Term Stewardship,” in Proceedings of the Tailings and Mine Waste 2025 Conference, 2-5 November 2025, Banff, Alberta: University of Alberta Geotechnical Centre (UAlbertaGC) (CGS and CPA)