Fiona caused wall failure at N.S. gold mine's open pit
No one was injured and no material impacted the surrounding environment, company says
Part of the wall surrounding the open pit at Nova Scotia's only operating gold mine collapsed during post-tropical storm Fiona last month.
St Barbara, the Australian company that owns the Touquoy gold mine in Moose River, N.S., noted the wall failure in its most recent quarterly report released Tuesday.
Material from the wall located above a production area slid into the pit due to "sustained and unprecedented rain and accompanying weather conditions," the company said in a statement Wednesday morning.
Despite the failure, the quarterly report said, "as a result of advanced site storm preparations, pleasingly there was no major damage to infrastructure nor any environmental breaches resulting from the storm."
Approximately 40,000 tonnes of material fell, about double the amount of material that's usually removed from the pit each day.
No one was injured.
The material was caught by catchment berms, and none of it reached the surrounding environment, the statement said.
The company's geotechnical and environment teams investigated and developed a plan for the safe return of workers. The company said in the quarterly report the rehabilitation work would take three weeks to complete.
A spokesperson for the provincial Environment Department said in a statement the department is aware of the incident and has been in touch with the company.
"The disturbance from the storm was located within the limits of the approved pit area, and we want to assure Nova Scotians that there were no impacts to the surrounding environment," the statement said.
Fiona also knocked out power to the mine from Sept. 24 to Oct. 5.
Company wants to store tailings in pit
Atlantic Gold, the subsidiary of St Barbara that operates the mine, has applied to the province's Environment Department for permission to store tailings — the material that remains after ore has been processed for gold — in the open pit.
The company's original application for that change was met with a request from the environment minister for more information. Atlantic Gold is still in the process of completing the additional work.
If the pit wall ever failed when tailings were stored there, the consequences could be dire, depending on how significant the breach was.
Karen McKendry, wilderness outreach co-ordinator with the Ecology Action Centre, said tailings can contain "a cocktail of proprietary chemicals."
While effluent from the mine's tailings facility is regulated and tested for certain chemicals and minerals, McKendry said a significant tailings containment failure could result in the release of higher levels of toxins and cause local flooding.
"I've never seen a catastrophic failure model for that dam because the company isn't required to make one and the government has never asked for one."
McKendry also said the mine was designed about 15 years ago, and she's concerned the company's modelling for climate change is no longer appropriate.
"If this [the open pit wall failure], which happened during an unprecedented but now going-to-be-the-norm storm is any indication, I don't know that their infrastructure is up to the task of the kinds of storms we're going to experience."
