Six dams at Vale’s Manitoba Operations tailings management area in Thompson are being analyzed to ensure that they are stable
The dams are downstream dams, built on compacted soil in the direction of water flow. A presentation on the Vale website posted June 8 says that the dams are in the high hazard category, which means that if they fail, there is a possibility that as many as 100 deaths could result, along with a significant loss of environmental and social values as well as very high economic losses affecting important infrastructure. The presentation says that the Thompson tailings dams have, at some point in their history, failed to be certified as stable or experienced notable stability concerns identified by an independent engineer.
“Based on internal and external investigations, 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),” says the document in reference to the Thompson tailings dams.
The Thompson tailings dam has been in operations since 1971 and most recently underwent an independent expert review in September 2018. The dam is overseen by both in-house engineering specialists and external engineering support and a formal analysis of the impact of a catastrophic failure was most recently completed in 2017.
Information about Vale’s dams in Canada and elsewhere was provided in response to a series of questions about dam safety posed by the Church of England Pensions Board, a large institutional investor and a group of large Swedish investors as a result of the January Brumadinho dam collapse in Brazil that killed about 270 people, the Wall Street Journal reports.
Churchill-Keewatinook Aski NDP MP Niki Ashton, who represents Thompson in the House of Commons, told the Journal that she wasn’t made aware of the issues with the tailings dam.
“Vale needs to be forthcoming to the public when it comes to the potential dangers associated to their operations," Ashton told the newspaper through a spokesman.
“I've called on the government to urgently deal with the situation,” Ashton said June 14 on Twitter. “Vale needs to be accountable and ensure the protection of the people and the ecosystem surrounding their operations.”
A Vale spokesperson told the Wall Street Journal that the company always complies with relevant legislation and keeps authorities informed about the situations at its dams at all times, having invested about $220 million in dams since 2016.