Globally there are thought to be up to 18,000 “tailings” dams – but no one knows for sure.
The homepage of the website World Mine Tailings Failures shows in full-screen-terror the video footage of the dam bursting at Vale’s Córrego do Feijão mine near the city of Brumadinho, killing a confirmed 165 people with over 150 more presumed dead.
A previously tranquil hillside collapses. Employees and families eating in a canteen are wiped out by a deadly wave of toxic iron ore sludge.
The tragedy is compounded by the data backstory on the same page; depressingly familiar historical numbers. The problem has been worsening over the decades since ICOLD/UNEP began collecting statistics prompted by an increasing frequency of high-consequence tailings failure events post-1990.
But just how big is the problem of mine tailings?
In the same region of Minas Gerais as Brumadinho, Vale alone has built 105 of these huge pits to hold mining waste. Globally there are thought to be up to 18,000 “tailings” dams – but no one knows for sure.
And therein lies a big part of the problem. What we are observing is not an issue specific to Vale or Brazil, but a systemic issue for the whole industry. There’s little transparency on how companies are managing social and environmental risks, particularly at a site-specific level, and no comprehensive public or government database of where these tailings dams are – let alone whether they’re at risk of failing.
Even the International Council on Mining and Metals (ICMM) – which brings together 27 mining and metals companies and over 30 national and regional associations – doesn’t have such a database for its member firms.
It’s not that so-called “upstream” dams – as in the Samarco and Brumadinho disasters – should be banned outright.
Geotechnical spokespeople from organisations such as the Australian National Committee on Large Dams (ANCOLD) maintain that they have the lowest initial cost and are the most popular in low-risk seismic areas and can be stable if properly designed within existing guidelines. Plus, how do you ban something that already exists to such a huge scale? Hazard classifications around tailings dams already exist and are fairly consistent (in principle at least) across the globe. But Lindsay Newland Bowker, Executive Director at World Mine Tailings Failures, says large gaps in practice arise not from evil or malpractice, but uncertainties that are inherent to the mining industry: “Once a mine has a permit and is in production, there’s nothing to stop it increasing capacity if the price turns favourable for the commodity. They’ll rush to produce more and grab deposition space for tailings.” Consequently, dams are often built up over time to hold more and more tailings. Such was the case in Brumadinho where the dam
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