The safest tailings dam is the one that is not built. And if built, without perpetual oversight, the failure of a tailings dam is inevitable.
These stark remarks were made in the recent publication of Safety First: Guidelines for Responsible Mine Tailings Management which was written by Earthworks, MiningWatch Canada and the London Mining Network, amongst others.
The report goes on to add that at present industry standards and governmental regulations “do not go far enough” to adequately protect communities and ecosystems from tailings failures. Indeed, the design, construction, operation and closure of tailings facilities still require significant changes to protect people and the environment.
“Operating companies must commit to making safety the primary consideration in tailings facilities and dam design, construction, operation, closure and post-closure,” the authors state, adding that “the primacy of safety must be independently verified” and that a culture of safety and responsibility “must be upheld at the highest level within a corporation”.
To understand how and why failures occur, the authors of this report stress that “we must understand the scope of the issue”.
“A global inventory of the thousands of active and abandoned tailings disposal facilities does not exist, nor is there a complete registry of tailings dam failures,” according to the report. “Compiling and sharing this information, publicly and transparently, is essential. An independent international agency, such as a United Nations endorsed agency, in collaboration with civil society, states, and operating companies, must drive the process to collect information on tailings dams and tailings dam failures worldwide, and share it with the public to reduce the risks associated with these sites and promote the protection of human health and the environment.”
Driving risk
Independent assessment and transparency have been called for in relation to tailings management worldwide. Although the Global Industry Standard on Tailings Management (GISTM) was recently introduced, critics say it was almost entirely written by the mining industry and claim it is a document that is highly favourable to their interests.
In 2020, the Global Tailings Review, a process co-convened by the trade industry association the International Council on Mining and Metals (ICMM), the UN Environment Programme, and Principles for Responsible Investment, released the GISTM. MiningWatch Canada says that although it came well short of the recommendations in the afore mentioned publication Safety First, “it was an important first attempt at international tailings dam regulation”.
ICMM members have committed to implementing the GISTM at all mines within five years, but it is unclear what progress has been made, and tailings failures continue. Since November 2021, there have been at least ten failures, leaks or overflows.
“Effective tailings management is impossible without civil society oversight as well as that of the role of independent professionals,” said Hassen Lorgat of the Benchmarks Foundation in South Africa and convenor of the South African Tailings Working Group. “This means that the laws and practices of corporations must change. This is urgent especially in the time of the climate crisis.”
Dr Steven Emerman is an internationally recognised geologist specialising in groundwater and mining, who has evaluated numerous proposed and existing tailings storage facilities around the world. He gives the example of the Copper Mountain Tailings Management Facility in British Columbia, Canada. Emerman claims that the mine will not release its dam safety reviews which were “extremely critical about the stability of that tailings dam”, and neither will the BC government.
Emerman, who has testified on tailings dams before the US House Subcommittee, European Parliament and the UN National Assembly, and is also Chair of the Body of Knowledge Subcommittee of the US Society on Dams, said that according to the GISTM the report should be released and made available to the public.
“I’ll just emphasise that tailings dams in BC are among tallest in the world,” Emerman says. “Proposals to raise the height of East Dam at Copper Mountain to almost 260m would make it the second tallest tailings dam in the world. The West Dam at the same facility would be the third tallest.”
The concern here is that the height of a tailings dam is one of the many drivers of risk that can lead to failure. Others include high seismicity, high precipitation, closed facilities or those under care or maintenance, the volume of tailings stored, plus upstream construction methods.
Upstream construction is considered as a less desirable form of dam construction from a safety standpoint. Although the dams are inexpensive as they use minimum amounts of construction material, as they are built on top of uncompacted tailings, upstream dams are known to have higher rates of stability issues and are susceptible to failure by liquefaction.
The tailings dams that failed at Mount Polley in Canada, plus Samarco and Corrego de Feijao mines in Brazil were all upstream dams. The Mount Polley dam was converted into an upstream dam in violation of permits. Upstream dams are now prohibited in Brazil, Chile, Ecuador and Peru.
Emerman went on to explain why a closed status of a tailings facility can also be a driver of risk. Such a facility is only safely closed when deposition of tailings has ceased, and all closure activities have been completed so the facility requires only routine monitoring, inspection and maintenance in perpetuity, or until there are no credible failure modes. However, for closure, system failure is considered to be “basically inevitable”. Over time there are simply too many things that could go wrong. Just recently a closed tailings dam collapsed in Jagersfontein in South Africa on 11 September 2022. It is reported that three people were killed, 40 injured, homes were swept away and at least 20 were damaged. The mine was closed more than ten years ago.
“Tragedies like these show how communities bear the brunt of irresponsible mine waste management. South Africa has the largest number of upstream tailings dams worldwide, a construction method that is considered unsafe and has actually been banned in some countries. Mining companies must not be allowed to simply walk away from unstable tailings dams,” Hassen Lorgat said. “This means that governments must ensure the laws and practices of corporations change to protect communities and ecosystems.”
Emerman goes on to say that the key questions to ask about closed tailings facilities include:
- Is there a realistic plan to monitor, inspect and maintain the tailings storage facility in perpetuity?
- Does the facility still have credible failure modes?
British Columbia
Back in British Columbia pressure is growing to address the risks posed by tailings dams across the province. The waste created by an accelerating mining boom is not only seen as a threat to communities and watersheds in the region, but the increase in extreme weather events brought on by climate change has intensified this threat.
Severe flooding is one of the main causes of tailings dam failure at mine sites around the world. According to MiningWatch Canada, British Columbians find themselves on the front lines of climate change, facing more extreme weather. In 2021, the province experienced ‘atmospheric rivers’ that caused severe flooding, loss of homes and infrastructure, and billions of dollars of damage.
“Extreme rainfall driven by climate change adds stress to the structures holding mine tailings. Even tailings facilities designed for today’s most extreme weather events may not be able to withstand future extremes under the influence of climate change, or multiple events such as heat domes, atmospheric rivers, and recurring flooding,” the organisation states.
Following the Mount Polley tailings disaster in BC during 2014, the Mount Polley Independent Expert Engineering Investigation and Review Panel found that to get on a path to zero failures, the province needed to reduce its tailings facility inventory by half and use best available technology for the remaining facilities.
However, as the years rolled by, there was concern that the province had not yet produced a clear strategy to reduce active tailings dams to prevent further disaster. This led the BC Mining Law Reform Network and SkeenaWild Conservation Trust to create a database of mines with tailings storage facilities (TSF) across the province.
The database comprises 86 mine sites that currently, or are proposed to, contain at least one TSF, and this was used to create a publicly available, interactive online British Columbia Mine Tailings Map. A report authored by Dr Steven Emerman also evaluated the database and the risks of a tailings dam failure (based on assessing the combination of the probability and consequence of failure).
“The purpose of the map was to establish the landscape of current and future TSFs across BC,” says Adrienne Berchtold, Ecologist and Mining Impacts Researcher at SkeenaWild Conservation Trust. “We wanted to provide that information publicly and easily regarding TSF location and risk factors. We also wanted to assess trends in BC tailings storage and determine whether the associated risks are changing.”
Described as being full of lots of different functionalities and information, it is hoped that the map “will be a useful tool for people to take their own lessons from”.
For each site on the map, details on the following key risk indicators are provided:
- Operational status – Sites that are closed and under care and maintenance may not receive adequate oversight to prevent tailings dam failures. Proposed sites show the emerging tailings landscape in BC, and the risks associated with it.
- Number of tailings dams – Every tailings dam on a site carries its own risk of failure, so more dams convey increased risk.
- Tallest tailings dam height – Taller tailings dams tend to have greater failure consequences and, in some circumstances, have increased probability of failure. However, the failed Mount Polley Dam was only ~40m tall.
- Highest dam failure consequence rating assigned to any tailings dam on site. Dam failure consequence ratings are assigned on the basis of potential loss of life and potential environmental, cultural, and economic impacts in the event of a failure.
- Upstream dam present indicates whether upstream dam construction has been used to build any tailings dam on site.
- Current tailings storage volume – Larger stored volumes of tailings tend to result in greater failure consequences.
- Design storage capacity for the largest (greatest volume) tailings storage facility.
“What we have learned from this map,” Berchtold says, “is that there is accumulative risk arising through all of these facilities across the province.”
Expert analysis
Dr Steven Emerman’s analysis of the database looks at the risks of failure at the 172 dams holding back mine processing waste in BC. He found that the height and volume of tailings storage facilities across the province have been increasing exponentially over time. The total volume of tailings currently being stored at BC mines is estimated to be 2.5 billion cubic metres and, with the addition of 11 proposed new mines, this is expected to increase by 75%. Operating TSFs are on average nearly twice as high as closed facilities or those under care and maintenance status, with proposed facilities on average again twice as high as operating facilities. Operating facilities hold on average five times more tailings than facilities in closed and care and maintenance status, while proposed facilities would hold on average three times more than operating facilities.
With such an increase in height and volume, there has been a corresponding increase in the potential severity of consequences of tailings dam failures, including the potential for loss of human life. Fifty eight percent of BC’s existing mine sites with TSFs are officially rated as likely to have high, very high, or extreme consequences in the event of a tailings dam failure. At only 19% of mine sites with TSFs would dam failure not result in a loss of life. Indeed, the death toll following a failure at many of the highest risk dams could be in the hundreds and could irreparably destroy salmon habitat, commercial farms, and vital infrastructure.
The analysis also found that one in four mine sites with tailings dams use upstream dam construction methods which has twice as many stability issues than downstream constructed ones. When looking at high, very high and extreme consequences of dam failure categories that include loss of life, 63.2% of sites have upstream dams.
“What’s most disturbing,” Emerman says, “is if we look at the consequence categories in this progression from closed, operated to proposed. For closed facilities 46% are in the categories high, very high and extreme, operating 83% and proposed 100%. In fact, for all proposed facilities the consequence categories are either very high or extreme. That means there is no proposed facility where there would be fewer than ten fatalities in the event of failure.”
Furthermore, British Columbia is already at high risk for some of the primary drivers of tailings dam failures globally —earthquakes and high precipitation, which cause flooding. Climate change will compound flooding risks with more frequent and severe rainstorms.
Recommendations
To ensure the safety of tailings dams in BC and reduce the risk to communities and the environment, key recommendations from this research include:
- Committing to a plan to reclaim or otherwise seek safe closure of tailings storage facilities in BC – This includes developing a strategy to reduce BC’s active tailings storage facilities by half, as recommended by the Mount Polley Independent Engineering Investigation Review Panel.
- Clarifying treatment of tailings storage facilities in ‘care and maintenance’ and provide clear guidance for management of facilities in this status.
- Align with international best practices and implement a ban on upstream tailings dam construction methods.
- Reverse the trend of more severe consequence ratings at new tailings storage facilities – Reducing the consequences of failure at all new tailings facilities or, alternatively, denying permitting for those that cannot be more safely designed and/or located, puts safety as a top priority.
- Factoring in seismic and climate change risks at all tailings facilities, especially when evaluating proposed mines – BC should update its guidelines to require that all tailings dams be built to withstand the most extreme flooding and earthquake events, and that future climate risks be factored into TSF environmental assessment and regulatory oversight.
- Pursuing strategies to reduce the volume of tailings, especially at new mines.
- Improving accessibility and transparency of information on risk factors for all tailings facilities.
“The Mount Polley mine disaster was a wake-up call to BC’s mining companies and the province. This map and report show that the risks to the environment and communities from tailings dams are still high and growing,” says Jamie Kneen, Co-lead of MiningWatch Canada and Co-Chair of BC Mining Law Reform. “More action is needed to follow through and get BC on a path to zero failures—from cutting the inventory in half, to phasing out certain mine dam construction methods. The government needs to act now to improve safety standards as mining continues to expand in the province.”
Summary of recommendations from Safety First: Guidelines for Responsible Mine Tailings Management (2022)
- Make safety the guiding principle in design, construction, operation and closure of tailings facilities.
- Ban new tailings facilities in locations that would not allow for timely assisted evacuation of inhabited areas in the event of dam failure.
- Ban upstream dams at new mines and close existing upstream dams.
- Design dams to avoid any potential loss of life, which must be considered an extreme event.
- Mandate the use of best available technology for tailings facilities, including the use of filtered tailings, and implement rigorous controls for safety, including after mine closure.
- Demonstrate understanding of local conditions and tailings characteristics with robust monitoring systems.
- Develop appropriate emergency preparedness/response plans.
- Ensure the independence of reviewers to promote safety and transparency.
- Address financial risks, including proper financial assurance and insurance.
- Attempt to eliminate all credible failure modes to have safer facility closures.
- Establish grievance procedures, whistleblower protection, and community-based safety oversight for potentially affected communities.
- Obtain consent from potentially affected communities and guarantee the right to say ‘no’ to proposed or expanded tailings facilities.
- Make information regarding mine safety publicly available in relevant languages.
- Offer affected communities access to independent technical experts.
- Require corporate boards of directors assume full responsibility for the risks (including financial risks) and the consequences of tailings facility failures.
The Safety First report and recommendations were endorsed by 157 scientists, community groups, Indigenous peoples, and civil society groups. It was based on consultation with over 200 stakeholders and experts across five continents.
REFERENCES:
Morrill, J., Chambers, D., Emerman, S., Harkinson, R., Kneen, J., Lapointe, U., Maest, A., Milanez, B., Personius, P., Sampat, P., and Turgeon, R. (2022), Safety First: Guidelines for Responsible Mine Tailings Management, Earthworks, MiningWatch Canada and London Mining Network. Report available at earthworks.org/safety-first and miningwatch.ca/safety-first
Webinar: Mapping B.C.’s Mine Tailings Threat (September 21, 2022) https://www.youtube.com/watch?v=kUfd_MOBua0
The webinar was co-hosted by BC Mining Law Reform and POLISWaterProject, as part of POLIS' ongoing Creating a Blue Dialogue webinar series. Panellists: Adrienne Berchtold Ecologist and Mining Impacts Researcher, SkeenaWild Conservation Trust; Dr. Steven H. Emerman Owner, Malach Consulting; Dr. Ellen Petticrew Research Chair, Quesnel River Research Centre; Moderated by: Nikki Skuce Director, Northern Confluence Initiative and Co-Chair, BC Mining Law Reform.
https://miningwatch.ca/news/2022/5/30/mining-industry-standard-failing-make-waste-dams-safe
Emerman, Steven, The Risk of Tailings Dam Failure in British Columbia: An Analysis of the British Columbia Existing and Future Tailings Storage Database, July 2022. https://reformbcmining.ca/wp-content/uploads/2022/06/BC_TSF_Database_Analysis_ Emerman_Revised2.pdf
Explore the British Columbia Mine Tailings Map at https://reformbcmining.ca/tailings-map/
