Tailings Dams ‘Have Not Breached,’ … Except When They Have

By August 16, 2014Hot Topic

Several other incidents offer insights into BC spill.

By Maura Forrest,

Originally published 8/15/14, on TheTyee.ca
[excerpts] Here are some of the facts:

A barrier breaks at a mine site, causing millions of litres of water to gush from a tailings pond into nearby waterways.

The mining company and the provincial government assure the public that the water poses no health risks, while local First Nations call for independent reviews.

It turns out the dam was not subject to regular inspections prior to the breach.

The incident is called “the largest spill of its kind in Canadian history.”

A government official is quoted as saying he is “surprised this could happen.”

Sound familiar?

Except it’s not the story of the recent Mount Polley disaster in British Columbia. It’s the story of another mining spill that occurred at the Obed coal mine in Alberta less than a year ago.

On Oct. 31, 2013, 670,000 cubic metres of water and 37,000 cubic metres of sediment poured out of a containment pond at the Obed mine, roughly 300 kilometres west of Edmonton. The spill devastated two small creeks and sent a murky sediment plume floating down the Athabasca River.

[excerpt] Tailings dams ‘have not breached’: minister

During a press conference with Bennett on Tuesday, Dr. Trevor Corneil of the Interior Health Authority lifted another part of the water ban that has been in place since the tailings dam broke on Aug. 4.

Water from Quesnel River and Quesnel Lake is now safe to use, except for the area surrounding a “visible plume” of sediment that remains near the mouth of Hazeltine Creek. Corneil also said that all fish in Quesnel Lake, Quesnel River, and the Fraser River are safe for consumption.

During the conference, Bennett stressed that the Mount Polley spill is one-of-a-kind.

“Tailings dams at operating mines in Canada have not breached,” he said, adding that a few closed mines in Canada have had tailings pond spills.

But one mining expert said that’s not the case.

Pierre Gratton, president of the Mining Association of Canada, points to the Sullivan Mine in Kimberley, B.C. In 1948, a tailings dam broke at that mine, releasing 1.1 million cubic metres of effluent. A similar incident occurred at the same mine over 40 years later, in 1991, but the tailings flowed into a secondary dam that contained them before they spilled into the environment. The Sullivan Mine was active until 2001.

“We can’t say [tailings spills] never happen,” Gratton said. “They do happen. But they’re rare. We haven’t had a failure of this kind in many, many years.”

Others argue that Bennett’s statement is merely an exercise in semantics.


A history of spills

In 2011, a series of incidents at the Lac Bloom mine in Quebec released over 50 million litres of tailings water that affected 15 downstream lakes.

In 2008, 11 million litres were released from the old Opemiska copper mine near Chapais, Quebec.

In 2004, a tailings dam collapsed during reclamation of a mine in B.C., spilling up to 8,000 cubic metres of water and sediment into Pinchi Lake.

In 1998, a tailings dam collapsed at the Canadian-owned Los Frailes mine in Aznalcóllar, Spain, releasing up to five million cubic metres of toxic water and sludge, and covering thousands of hectares of farmland in slurry.

In 1996, a Canadian-owned copper mine in the Philippines released 1.6 million cubic metresof tailings through an old drainage tunnel, forcing 1,200 residents to leave their homes.

And in 1995, a Canadian-owned gold mine in Guyana spilled 4.2 million cubic metres of cyanide slurry into the Essequibo River.

The three high-profile international spills prompted the Mining Association of Canada to launch its Towards Sustainable Mining certification program in 2004. Mining companies that are members of the association are ranked according to six indicators. The most important is tailings management.

“With tailings, a failure is unacceptable,” said Gratton, adding that industry “wanted to do something about that.”

Gratton said many companies have improved their tailings management practices in the last decade. Progress reports are publicly available on the organization’s website.

At the time of the Mount Polley spill, Imperial Metals was in the process of obtaining the certification, but had not yet undergone an external evaluation.


Leave a Reply