Tailings dam management not just ‘engineering challenge’ ERM says

The tailings dam disaster at Brumadinho in Brazil. Photo by Diego Baravelli/Wikimedia Commons.

Sustainability consulting firm ERM says the mining industry needs to do more to prevent tailings dam disasters and notes that a further possible 19 incidents with tailings facilities could occur over the next decade.

In a report released last month, ERM reviewed the dam failure incident reports of 11 major dam failures over the last 12 years and concluded that “basic organizational and human factors, such as budgeting, operational leadership, safety and risk culture, and competence, played a significant role in each.”

Citing statistics from the World Mine Tailings Failures study released in 2019, ERM noted that historically there have been between two and five major failures and 35 minor failures annually.

“Minimizing the risk of tailings dam failures is one of the greatest challenges facing the sector,” ERM stated in its report. “Despite the billions of dollars being invested and the recent launch of a global industry standard on tailings management, there is a concern that the industry is destined to do ‘too little too late’ to prevent further catastrophic incidents.”

While the technical and engineering causes of tailings dam disasters have been covered extensively and include three major factors – slope instability, overtopping and foundation stability – ERM stated, “unfortunately the organizational and human or ‘adaptive’ causes have not been so well researched and yet these have been just as significant in contributing to catastrophic failures.”

“An over-reliance on engineering standards and considerations has led to a focus on the low likelihood of tailings dam failures – yet they continue to occur,” ERM noted.

A worker surveys the damage at the Brumadinho dam disaster in Brazil. Photo by Diego Baravelli/Wikimedia Commons.

One problem is that decision-makers “often rely on layers of controls that are reviewed by peers, subject matter experts and independent boards,” ERM found, but “do not dig deeply enough into how the controls are being implemented and how well they are understood by the workers managing the dam.”

“Indeed in almost all cases when a third party review is conducted of a tailings storage facility (TSF) considering the management of controls (e.g. training, deviation reporting, corrective action tracking, communication, and governance processes), significant breakdowns emerge quite readily. Any control strategy cannot be devoid of the human factor.”

ERM noted that based on disclosed information on about 600 TSFs around the world, there are more than 1.3 million people living downstream and within 20 km of the waste storage dams. Of those, 57% live downstream of TSFs built using “upstream” construction methods. According to ERM, the upstream model “is considered to be the lowest initial cost for a raised tailings embankment due to the minimal amount of initial fill material required,” noting that about half of these upstream models are operational and another 25% are described as ‘inactive’ but haven’t been closed down or rehabilitated.

“Our analysis has considered the location and topography of these TSFs as well as the plausible flow trajectories,” ERM said. “Using satellite imagery, we have estimated that more than 70,000 sq. km of land, (an area the size of Scotland) is at risk of impact from these tailings facilities should they fail.”

ERM also found that those people of greatest risk are living downstream of TSFs associated with copper mining operations.

In an interview, Louise Pearce, ERM’s global managing mining and metals lead, said the report followed up data published by The Investor Mining & Tailings Safety Initiative, which is led by the Church of England Pension Board and Sweden’s AP Funds Council of Ethics. In April 2019, the Initiative requested dam-by-dam disclosure information from mining companies after 270 people were killed in the Vale tailings dam disaster at Brumadinho in Brazil.

The request was issued to over 600 companies and was backed by 100 investors with nearly US$13 trillion in assets under management. Most major mining companies, Pearce said, have committed to implementing the standard and ERM sees this as a great step.

“Our paper highlights the need to pay more attention to the human factors associated with managing dams safely and the importance of considering the downstream consequences, with much greater rigor,” Pearce said. “When implementing the global standards, mining companies need to place an early emphasis on the community and the human aspects equally with engineering design consideration.”

“Are you talking to the communities? Do they really know how much time they have to react if something goes wrong?”


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