Brazilian prosecutors freeze over $219m of Vale’s assets

People located at and near Brumadinho, the town where the breach occurred, are now facing the dangers associated with having toxic elements in the Parapoeba river, which flows into Sao Francisco, a river that provides drinking water to communities in five of Brazil's 26 states.

Minas Gerais' government said on Thursday that initial tests of the Paraopeba River indicated the water of such body “poses risks to human and animal health,” and called locals to refrain from using the river’s water, whatever the purpose.

Additionally, the city of Mangaratiba, in Rio de Janeiro, has temporarily closed Vale's Ilha Guaíba (TIG) iron ore terminal. According to CBN radio, the company was also fined 20 million reais (about $5.5 million) for failing to submit environmental licenses.

The global community has been left with several unanswered questions, particularly about the causes of the dam breach and why Vale didn’t do anything earlier to prevent it. Reuters reported the iron ore producer had identified concerns around its tailings dams in 2009, but did not implement several steps that could have avoided or lessened the amount of damage.

In the last 24 hours, UN experts and most news outlets have pointed their finger at the kind of dam chosen by Vale. The Brumadinho facility, which dates from the 1970s, was built using the “upstream construction” method. This is a design that has long been banned in earthquake-prone mining countries such as Chile and Peru because tailings are used to gradually build the embankment walls, making a dam susceptible to damage and cracks.

While Brazil is not as earthquake-prone a nation as its western neighbours, it’s been shown that even small seismic activity can affect tailings dams such as the one near Brumadinho.

Lindsay Newland, executive director of World Mine Tailings Failures, an online database that aims at exposing the cause of those kind of disasters and to teach how to prevent them, argues there was no way Vale could have adopted a different technology to build its dams.

“The nature of the ore being produced at most of its mines was not amenable to dry stack, filter or thickening,” she said in an emailed statement. “That is a problem throughout Brazil and throughout the world's portfolio of 18,000 Tailing Storage Facilities (TSF),” she said.

Legislators, such as Minas Gerais’ own Joao Vitor Xavier have tried to pass legislation banning upstream dams. In July, his measure was defeated without mining companies bothering to join the debate, he told Bloomberg.

Newland says banning upstream dams is not the answer to failure prevention. “It is meaningless to advocate (prohibition of upstream) as a risk reduction. There are as many as 12,000 existing such dams structures all over the world that are full of fines, which is the root cause for unstable conditions,” he said.

Dirk van Zyl, a professor of mining engineering at the University of British Columbia and EduMine author, says that while dry-stack tailings are more stable, they can be as much as ten times more expensive.

“There are a lot of calculations people can use for the cost of a failure,” he said. “You not only have the real cash cost to the company, but you also open the whole discussion of what a human life is worth?” he noted.