Abstract

Climate Change Risk Assessments (CCRAs) are becoming an important part of future mine planning for both operating and closed mines. Although the level of detail varies for a CCRA, the overall objective of a CCRA is to identify the change in risk associated with identified infrastructure based on the changing climate variables. Climate change variables considered in the CCRA are selected based on the infrastructure assessed and may include (but are not limited to) annual precipitation, short-duration storms, snow pack, frequency of specific storm types, and temperature. The change in risk is assessed based on the sensitivity of the infrastructure to the selected changing climate variable and the defined potential consequences.  

This presentation explores lessons learned from CCRAs and shares the importance of selecting appropriate climate variables for each infrastructure type. The presentation focuses specifically on flood routing risks to mine infrastructure in general, with a particular focus on tailings management infrastructure.  

Based on experience in participating in CCRAs as well as facilitating risk assessments, KCB has found that the changing risk ratings for tailings infrastructure are often too conservative. This is due to inappropriate selection of the climate change variables for tailings infrastructure, lack of understanding of site-specific flood routing and climate characteristics, and a lack of understanding of the sensitivity of the tailings infrastructure to the climate change variable. Tailings infrastructure is often designed for extreme events (e.g., greater than 1 in 1000 years) that are not often considered in a CCRA, and lower return period storms (e.g., 1 in 100 years) are not critical or sensitive events for tailings infrastructure. The uncertainty regarding climate change effects on extreme storms further complicates the assessment. Finally, the level of effort (e.g., qualitative assessment compared to quantitative assessment) may not be fit for purpose for some infrastructure. This paper will demonstrate how these circumstances can result in an overly conservative ‘false alarm’ for some tailings infrastructure that is designed to handle extreme events and will discuss some considerations to help reduce these 'false alarms'.