Vale opens the books on Sudbury tailings dams following collapse in Brazil

Vale says it is currently doing work to stabilize some of its tailings dams in Sudbury, but stresses that there is no risk to the public.

The company this month released a report on the state of its dams around the world that it says was asked for by a large group of investors represented by the Church of England, following the collapse of a Vale dam in Brazil in January that killed 270 people. 

The report includes dozens of dams that Vale manages in the Sudbury basin to hold mining waste, some dating back to 1929.

Eight of them, in what's referred to as the M and P tailings areas near Copper Cliff, are listed as having some stability problems.

"Routine monitoring and inspection over the years has revealed some soft, silty layers in some areas of the shell of six of these dams," reads a statement from Vale, which declined an interview with CBC.

"Importantly, this does not indicate any imminent threat of dam failure nor any imminent threat to public safety. We have been addressing this issue through a program of continuous upgrades and capital spending to fortify and buttress the dams to address the issue responsibly and appropriately, with the oversight of the Tailings Review Board."

These dams were built in 1945 and 1960 and Vale says they haven't been receiving tailings from the Sudbury mining operations for the past 30 years.

The report says that if these dams failed, the risk would be "extreme." 

Aside from four tailings areas in Copper Cliff referred to as R1, R2, R3 and R4 built in the 1980s, most of Vale's tailings in the Sudbury area are inactive

"The integrity of tailings facilities across the entire mining industry is under greater scrutiny than ever to ensure public safety," Vale says in its statement.

"Ensuring the safe operation and maintenance of our facilities here in Sudbury continues to be our highest priority."