Rupture of Thompson's tailing dams could kill nearly 100 people, Vale reveals

A mining giantreeling froma deadly damcollapse in Brazil says it is investigating one of its dams in Thompson, Man., over fearsa rupture could kill as many as100 people.

Vale revealedone of the six active mine dams in the northern Manitoba city recorded a "very high" hazard rating, as determined by the Canadian Dam Association, which means a collapse could result in up to 100 deaths, significant loss of environmental and cultural values and "very high economic losses" affecting important infrastructure.

The mining company disclosed the safety ofits damoperations worldwide, after facing pressurefrom the Church of England Pensions Board and a group ofSwedish investorsin the wake of a January dam failure at Brumadinho, Brazil, that killed 270 people.

Vale employees and contract safety inspectors knewof dangerous conditions at the Braziliandam for months, the Wall Street Journal has reported.

'People on the ground' ignored: MP

"Based on internal and externalinvestigations, known zones in the dam foundation are under further analysis and we are undertaking additional assessment and precautions while the investigation is ongoing with the oversight of the TRB [Tailings Review Board]," Vale said in its report.

The company'srecords statethe Thompson tailing dams have, at some point, failed to be confirmed as stable, or experienced notable stability concerns, as citedbyan independent engineer.

Tailing dams are physical structures that store the remnants of mining operations.

The company's disclosure first came to the attention of local MP Niki Ashton when it was reported by the Wall Street Journal.

"Vale told its shareholders of this, but not people on the ground," she told the House of Commons on Monday, after writing to federal Environment Minister Catherine McKennaand Natural Resources Minister Amarjeet Sohito askthe Liberal government to intervene against a company she alleges is disregarding safety.

Sohi said he would follow up with the area MP.

Vale said it publicly disclosed its findings on its website afew days ago.

The company said a review in the last few weeksfound onecontainment damdid not meet the standard of the Canadian Dams Association, but Valeis reviewing the analysisby an independent engineering consultant since the findingdoes not correspond with the dam's actual performance.

"In reality, all phreatic surfaces those below the water table are reporting normally. There are no increases in pore pressure, no displacements or movement in the dam whatsoever," Vale spokespersonAngie Robson said in a statement.

She said the dam is continuing to perform well.

"Thereis no imminent threat of dam failure.This is an issue that was surfaced through effective monitoring and inspection and is being addressed responsibly and appropriately. In other words, the system is working," she continued.

Safety our highest priority: Vale

"The integrity of tailings facilities across the entire mining industry is under greater scrutiny than ever. Ensuring the safe operation and maintenance of our facilities, including in Thompson, is our highest priority."

It added that a discussion ontailings management comes up whenVale's community liaison committee in Thompson meets.

The Thompson tailings dam has been in operation since 1971 andwas lastevaluated by anindependent expert in Sept. 2018, Vale said. The company said it last conducted an analysis in 2017 of the downstream impact on communities, ecosystems and critical infrastructure in the event of a catastrophic failure.

Vale has been trimming its operations in Thompson afterit closed a nickelmine in 2017 and shuttered itssmelting and refiningfacilities a year later.

The mining company employedabout 1,450 full-time employees in early 2017, but thetotal has since dropped to about 850.