Photograph by Adriano Machado, Reuters
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Members of a rescue team search for victims after a tailings dam owned by Brazilian mining company Vale SA collapsed in Brumadinho, Brazil, on January 28, 2019.

Photograph by Adriano Machado, Reuters

Brazil’s deadly dam disaster may have been preventable

Experts say the industry needs to adopt newer technology and receive stricter oversight.

Update: In a press statement on January 29, Vale announced the decommissioning of all the company's dams that use the upstream method (see below). The company has 10 dams of this type, all of them said to be already inactive. The cost of the change is estimated at R$ 5 billion ($1.3 billion U.S.) and decommissioning will occur over the next three years.

Only 1,177 days separate accidents of the Fundão ore reject dams in Mariana and the Córrego do Feijão mine in Brumadinho in the metropolitan region of Belo Horizonte, both in southeastern Brazil. In the first incident, in November 2015, the toxic sludge expelled by the structure killed 19 people, buried villages, left thousands of people homeless, and reached the sea. At the time it was considered one of the country's biggest socio-environmental disasters in the mining sector.

And then on January 25th, 2019, about 78 miles from Mariana, another tragedy struck in the state of Minas Gerais. The full impact of the Brumadinho accident is still being evaluated, but at least 65 people have been reported dead, victims of the tailings mud stored at Dam I of the Córrego do Feijão Mine, and about 280 were missing at the time of this writing.

The collapse of those two dams, operated respectively by the Samarco (joint-venture of BHP Billinton and Vale S.A) and Vale, could have been avoided, say environmental experts. Stricter licensing laws and state oversight and the adoption of more modern technology could transform the Brazilian mining sector, making such incidents less likely, experts told National Geographic Brasil.

Leonardo Ivo, director of the Association of Observers of the Environment of Minas Gerais, has been in Brumadinho over the last few days in the aftermath of the accident. "It is necessary to rethink this practice of storing mud," he says.

The anthropologist Andréa Zhouri, coordinator of the Environmental Issues Studies Group of the Federal University of Minas Gerais, says tragedies such as Brumadinho's are not "natural disasters," but "political-institutional failures." And the state’s recent efforts to simplify the environmental licensing process and the monitoring of dams is at least partly to blame. "In Brazil and Minas, it is the ore above everything and everyone," says the researcher.

The historical importance of mining to the state’s and country’s economy is undeniable, Zhouri notes, but she argues that economics have been placed too far ahead of human life and environmental issues. "The issue is not to criticize the ore itself, but the economic model of exporting mineral commodities that makes the country dependent while subjugating society and territories in a perverse and criminal way," she says. The researcher criticizes loosening legislations in favor of mining companies and the institutional practices that operationalize the regulations.

For the superintendent of the Association of Environmental Defense, Maria Dalce Ricas, Vale's confidence in the safety of the dam was so strong that the company's facilities were located nearby. The company’s buildings and employees were among the victims of the disaster. "These dams are time bombs that can explode at any moment," says the environmentalist. "A good part of these dams are inactive, but this one was also inactive and even so it collapsed."

Anatomy of a disaster

The immediate cause of the dam failure is still unknown. Tailings dams are structures that hold mining waste, which, for environmental reasons, must be properly stored. Vale declined a request for comment, referring instead to its press releases. There, the company reported that Dam I of Córrego do Feijão Mine was inactive and that the company was developing its decommissioning project. According to Vale’s statememts, the dam had a Stability Condition Declarations issued by TUV SUD do Brasil in June and September 2018.

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"It is worrying that the dam has been evaluated by competent institutions and external audits and found there was no risk of breaking," says Ivo.

Built in 1976 by Ferteco Mineração, the dam used the upstream method, which, although common, is the least safe, according to experts. This method was the same in the Fundão dam in Mariana. According to the G1 report, there are another 130 dams of this type in the country. Upstream upheaval is the process where the dam uses the tailings itself to lift the mud up in steps.

Zhouri says upstream dams should be banned from mining in Brazil. "This technique is outdated and obsolete, used only in developing countries. It is not safe for the population, but it is the cheapest," she says. "There are alternatives, such as dry containment, and Vale has this technology. The state must demand it."

"We learned very little from Mariana's tragedy. The rupture of the dam of Fundão should have been a huge alert," says Ricas. “Costs shouldn’t justify avoidance of technical measures that guarantee the safety of the population, of biodiversity, and of the environment."

The risk of further collapse may even be imminent: on Sunday morning, it was suspected that Dam IV, also in the Córrego do Feijão Mine, could break. The sirens in the region were activated by Vale and the community had to leave their homes. Throughout the day, however, Vale reported that the Civil Defense had lowered the level of criticality of the dam from two to one. People were able to return to their homes and firefighters resumed searches for the missing.

Evolving laws

After the tragedy in Mariana in November 2015, a popular initiative, coordinated by the Minas Gerais Public Ministry, obtained more than 56 thousand signatures and generated Bill 3695/2016, Sea of Mud Never More, filed in the Legislative Assembly of the state. The main objective was to create specific legislation on safety of mining tailings dams. Four points were considered essential for the legislation to bring changes to the industry. First, the prohibition of upstream upheaval. The second point requires taking out a surety bond before the start of the operations to help cover expenses in the event of an accident.

Third, the rule would oblige mines to consider the safer dry-tail treatment method; and, fourth, dams could not be built near public water supplies or within 10 kilometers of a population. Although the law had the support of the Public Ministry, Ibama and environmentalists, it was replaced by a more vague bill, PL 3676/2016, which does not contain the four points and would, according to Ivo, allow more weighing of economic criteria in the evaluation of the licenses. Neither bill has yet been approved.

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An aerial view of an area affected by a mudslide after the dam's collapse.

In addition, an environmental licensing law approved in Minas Gerais in 2017 allows, in some cases, three-phase licensing (prior licenses, installation, and operation licenses) to be approved simultaneously. Yet that can be too rushed, says Ivo, increasing the chance of accidents.

The state law that governs the safety regulations of dams in Minas Gerais, 15056/2004, says that in case of an environmental accident, the emergency measures are assumed by the company, either directly or in reimbursement to the state. At the federal level, Law No. 12334/2010, known as the National Dams Security Policy (PNSB), aims to ensure that dam safety standards are followed. Neither law, however, was able to avoid the tragedies in Mariana and Brumadinho.

For Zhouri, the Brazilian state needs to do more in regulating the mining industry. "Mining has to be subjected to society, not the other way around," she says.

Viable alternatives?

What, then, are the alternatives to ore tailings dams?

Ricas says the problem is complex and there are no simple solutions. However, she says it is not acceptable to store sludge above communities because of the risk of rupture. Other options include drainage cells, in which the material is disposed of in piles to dry; transforming waste into raw materials for construction; and dry crushing. Ricas says each technology would be applied to a particular type of tailings, depending on the ore, and that viability should be studied in each specific case.

Ivo believes that the technology of dry treatment should be adopted as soon as possible by mining companies in Brazil. "They prefer to take the risk of collapsing because of the economic aspect, but studies show that the technology of dry treatment would increase the cost by only 20 percent, which is plausible for a miner," he argues. According to Ivo, some companies already do the dry treatment of ore tailings, in cities like Ouro Preto and Nova Lima.

Ricas understands that it will be difficult for the government to monitor the hundreds of dams in the country and that even a stricter licensing process would not necessarily solve the issue. She believes the answer lies in technology. "A dam must always be the last option," she says.

This article was previously published by the Brazilian edition of National Geographic and has been translated.