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Brazil dam collapse triggers standards review

3140330 brazil dam

Brazil iron mine owner Vale is to raise safety standards after ordering an evacuation of people living downstream of a second tailings dam at its Córrego do Feijão Mine site after a tailings dam collapsed on Friday killing at least 58 people.

As reported by New Civil Engineer’s sister title Ground Engineering, rescuers have said that there is little hope of finding any of the other 305 people missing alive after Friday’s collapse, which Vale has said happened without warning.

No details have yet been released about the cause of the collapse near Brumadinho in Minas Gerais State but Vale has said that it will increase its standards in response to the disaster.

Vale chief executive Fabio Schvartsman said that the company has created a working group that in the next few days will present a plan to raise the safety standard of the company’s dams. The objective, according to him, is to improve on the most rigorous parameters that exist today in Brazil and in the world.

“I’m not a mining technician,” he told a press conference. “I followed the technicians’ advice and you see what happened. It didn’t work.

“It seems to me that there is only one solution: we have to go beyond any standard, national or international. We are going to create a safety mattress that is far superior to what we have today,” he said.

Schvartsman flew to the scene of the incident on Friday soon after the news broke. “It is Impossible to come here and not become emotional by the sadness of the situation and the superhuman efforts of all those assisting in this operation,” he said. “For our part, Vale is putting everything it has available, all equipment and human resources, without limits.”

On Saturday, a day after the breach, Schvartsman flew over the region and met with representatives of state and federal governments to evaluate the supporting measures of the rescue and the care of those affected and their families.

Nonetheless, Brumadinho mayor Avimar de Melo Barcelos said that the company had been “careless and incompetent” and said that the state and company were both at fault for poor oversight of the operation.

Over the weekend, ground engineering specialist Fugro reported that four of its employees at the site were unaccounted for. A fifth employee was rescued and was in a local hospital with minor injuries. Fugro said it was working with local authorities to get more information on the well-being of its colleagues and is providing full support to the families of the missing persons.

Landslide specialist David Petley, who is Sheffield University pro vice chancellor (research and innovation), described the scale of the collapse as “breathtaking”.

“This is clearly a complete collapse of the retaining structure, which was tall and steep, with most of the tailings having been mobilised into a high velocity flow,” he said.

Petley has reviewed analysis undertaken by Vale of its tailings dams in Brazil in 2016, which shows the company recognised the consequences of the dam collapse as high but classified the risk of this happening as low. The records show that the dam was 87m high and impounded almost 13M.m3 of mine waste.

Petley said that this collapse is indicative of a much larger global issue.

“The impacts of tailings dam collapses on people and the environment can be catastrophic, as this event illustrates,” said Petley. “As such it must be incumbent upon operators to ensure that collapses cannot and do not occur under any foreseeable circumstances. But we repeatedly experience tailings dam failures – recent examples include Cadia in Australia (2018), Mishor Rotem in Israel (2017), Henan Xiangjiang Wanji in China (2016), Samarco in Brazil (2015), Mount Polley in Canada (2014), Xichuan Minjiang in China (2011) and Kolontor in Hungary (2010), among many, many others.

“No other area of geotechnical engineering would tolerate a failure rate like this, and no other area of geotechnical area would be allowed to operate in the area of the risk / consequence matrix occupied by tailings dams. That this situation is allowed to continue is an absolute disgrace.”

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