Tailings Management. An Ongoing Journey.
A topic that has recently risen to the forefront for mining operators around the world. Questions are being raised by investors and society - they’re wondering:
How is the mining industry managing its business, and where do the risks really lie?
Industry’s management of tailings has evolved significantly since the 1960s, and there are many things being done right, many companies with great track records, great governance and management systems, and many very stable facilities. After all, we do have an enormous quantity of tailings that has and continues to be stored safely around the world.
On the flip side of great performance, we have continued to see an average of 2-2.5 failures per year over the past 25-30 years . And unfortunately, the consequences of these failures (including the loss of human life) have continued to increase – in fact, the last major failure essentially set a new record. No matter how we promote the benefits of mining, and all the positive things we are able to do through mining, this aspect remains a very stark black mark on our record.
Consider that the public expects failures to be a rarity for civil structures of a similar nature. Over the past 100 years, the failure rate of water storage or hydro dam infrastructure is only 0.01% , more than two orders of magnitude lower than tailings dam failure rates. It shouldn’t be a surprise that the public expects these same standards of safety from mining as they do for this civil infrastructure.
Now consider that the mining industry also upholds safety to very high standards and ambitions – aiming for zero fatalities, zero harm, zero failures. Why shouldn’t the same values apply to everything related to the management of our wastes? And how might we move forward to eliminate these failures?
Choices & Change
Most engineers will tell you that all technical and physical challenges can be overcome, if we simply consider different approaches to design and development. These approaches could include choosing better locations for containment infrastructure, and/or reducing the volume of tailings we produce in the first place. We can also utilize our greater understanding of tailings characteristics, and technologies with capabilities to ensure the gradation, density, moisture content, and rheology of tailings materials so that they are produced and placed in new, lower risk, ways. An example of this is creating drier tailings and applying compaction during placement as opposed to spigotted discharges. These decisions often primarily come down to cost – not technical feasibility. We have a choice.
On the human side and operations, change is a bit more difficult. Here, we begin dealing with behavioural and cultural change, mindset shifts regarding “how things should be done around here”.
PDCA – Improvements under Constant Review
Industry has been making improvements on several fronts, and over the past several years, the Environmental and Social Responsibility Society (ESRS) of CIM has supported this work by showcasing projects and operations through webinars and conference sessions and by hosting annual educational workshops. Areas covered in these sessions have included challenges and opportunities with respect to:
Tailings Management Systems. A lot of work has gone into the development of strong guiding management principles (i.e. MAC TSM), appropriate operating practices, and the means to observe and respond to various performance conditions. MAC’s guides offer great information on how tailings facilities should be managed, including having the appropriate personnel as responsible authorities over the facilities, the associated material and water balances, and overall performance.
Competencies. There has been a growing awareness and more frequent dialogue around the limited availability of personnel who have the appropriate knowledge and experience in tailings management to become the “next generation of experts” who will continue to grow and nurture more specialists to come. The experts that were once in the field are now reaching retirement age, and few younger employees have shown interest in tailings management. This is a gap that requires filling, and we’re very happy to see that UBC is initiating a Graduate Certificate in Global Mine Waste Management, expected to start in January 2020.
Governance & oversight. It has been recognized that having external, third party review panels helps to ensure that appropriate design rigour has been performed, by qualified people. This also helps to fill any gaps in knowledge and experience of the tailings team, as just noted in the last point. It also helps to ensure that accountable personnel have been assigned responsibility to monitor & react to performance at each and every site, and that they are in fact aware of how their infrastructure is performing.
Shifts in technical requirements. Constant change is one of the most critical aspects to consider, for the scale of the facilities we now manage. It used to be that a dam was designed for one small ore body and the processes that would be used for the life of the mine, and the tailings within, were well defined and dams were designed to contain these materials accordingly. Now, mine developments can extend decades, expand into new geologic deposits, mill ores from other sites, and even significantly alter their processes during the life of an operation. Considering that we’re still learning what it means to continuously build and manage large-scale structures with constantly changing requirements, this can introduce a lot of risk.
Personnel turnover & knowledge retention. Over the lifecycle of any single mine, there is high potential for turnover of the people and transfer of responsibilities with respect to tailings infrastructure and management systems. This is by far the greatest risk we face, and it can lead to several challenges, including lack of knowledge transfer, and the appearance of gaps in the historical record of development and/or changes in practices over time. It can also introduce misunderstandings regarding the levels of risk associated with various aspects of the system, such as underlying ground conditions, rates of seepage, past performance of deposition or changes in pressures.
Broadening our Focus
Going forward, shifts in design and practice to manage risk are still needed, particularly in the following areas:
Resilience. Engineers and management are reluctant to accept and apply strong resilience criteria that require multiple lines of defence against the consequence of failure. For example, if you have fine wet mobile tailings, a resilient defence would require you have both a robust embankment, and a downstream clearance, secondary containment, or other barriers to flow. Conversely, amend the tailings themselves to be inherently stable.
Systems thinking & Integration. When it comes to tailings management, too much activity is siloed or compartmentalized. Tailings are typically an “afterthought”, and there continues to be a reliance on the geotechnical engineering community to take on the full responsibility of safely containing our industry’s “trash”. Instead, there should be much more collaborative work and consideration at much earlier stages in design, to ensure safe storage of the residuals of mining. Just as we put so much time and effort into optimizing the recovery rates of precious ores, or improving the quality of water we need to discharge, we should similarly focus on engineering the residuals to ensure they are chemically inert and geotechnically stable.
Ownership of Liability. Recent incidents have highlighted the question of who is ultimately responsible for tailings management facilities. Technical experts are increasingly reluctant to accept liability for the ongoing performance of these facilities. This is disquieting as the one element that stands to suffer is the dam itself, but understandable, considering that these hired experts don’t typically have control over management decisions or changes in ownership, even when mine developments can extend decades, expand into new geologic deposits, mill ores from other sites, and even significantly alter their processes during the life of an operation. Going back to the point of systems thinking, there are many opportunities for collaborative optimizations through the value chain of extraction and processing, if we could agree we all need to take ownership of the performance of these materials. Everyone (technical, financial, legal, and insurance influencers) must work together to redefine how responsibility and liability is shared in order to reduce the risk profile. This will require persistent, informed and fair leadership by owners.
Better information management. With the regular extensions of mine lives, as well as the sale and acquisition of operations or mergers of companies, we’ve acknowledged that there is a high turnover of personnel involved with our tailings infrastructure and management systems. This can lead to several challenges, including lack of knowledge transfer and the appearance of gaps in the historical record. We need to do a much better job with managing and retaining data and information, as well as ensuring access to it.
Change & Conflict Management. Related to the last point, we do need to recognize that past records are often not available to the level of detail that might be desired or required to appropriately assess some risks when new changes are proposed. Differences of opinion can and do come about when new experts and designers come into the picture, leading to disagreements about how to proceed or alter practices and designs. Improved management of change is critical, no matter who is involved, including the assessment of risks associated with proposed technical changes, changing material characteristics, shifting containment requirements, altered designs, personnel & oversight shifts, training, and more.
Training in Risk Awareness. Each and every operator needs to understand the risks they manage every day. Increasing operators’ level of ownership in the work they are doing and their understanding of how their actions impact other parts of the system is critical to maintaining the safety of tailings facilities.
At the end of the day the root drivers of success in the management of tailings systems are leadership and unifying the diverse ecosystem of people involved with managing these complex systems. If such a culture exists, and everyone involved is well-informed of the integrated risks, of how each player contributes to managing those risks, and they each have the appropriate tools, training and support needed, the mining industry can improve its tailings failure track record.
Let us integrate waste management in the core parts of the mining business, strengthen our unified safety culture, and work towards zero failures in all functions of our business.
1. Azam, S., Li, Q. (2010). Tailings Dam Failures: A Review of the Last One Hundred Years. Waste GeoTechnics. Geotechnical News.
2. ICOLD (2001). Tailings Dams – Risk of dangerous occurrences, lessons learnt from practical experiences, Bulletin 121.
This article was first published as a summary in the CIM Magazine, September/October 2019 issue.
Karen Chovan is the Principal of Enviro Integration Strategies and Vice Chair of CIM Environmental and Social Responsibility Society. She has worked for 20 years in the mining sector, giving her insight into the challenges and opportunities for improvements that can be made in operations, projects, and corporate environments.