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SOURCE: Reuters
DATE: June 9, 2021
SNIP: Vale SA’s decomissioned Xingu dam is at “imminent risk of collapsing,” according to a statement on Wednesday by the Regional Labor Department for the southeastern Brazilian state of Minas Gerais.

The Xingu tailings, or mining waste, dam in the town of Mariana, already devastated by a 2015 dam rupture which killed 19 people, had its risk level elevated last October by Brazil’s National Mining Agency. Although the Xingu dam stopped receiving mining waste in 1998, Vale still employs workers there to monitor its stability ahead of a planned decommissioning procedure.

Labor auditors responsible for mandating the closure and evacuation of the surrounding area said a potential collapse at Xingu could happen via a process known as liquefaction, in which water weakens the solid materials composing a dam.

Liquefaction was previously pinpointed as a key cause of the 2019 collapse of Vale’s dam at Brumadinho, which killed 270 people.

The Regional Labor Department said in the statement on Wednesday that the area was closed after a request for documents on April 27 and an inspection on May 20. The company will have to take various technical measures to get permission to reopen the area.

“Documents presented by Vale show the Xingu dam is not stable (…), presenting a significant risk of collapse”, the surveillance group said. “The situation is extreme and puts workers at risk.”

Engineers and technicians told the auditors that the tailings at Xingu had not been properly drained and had been deposited in the dam in an uncontrolled manner.