Mount Polley mine disaster followed years of permit delays — report

Mining company had warned of “geotechnical instability” from a buildup of water behind tailings pond dam, FOI documents show. (Image from archives)

In 2004, Imperial Metals Corp. (TSX:III) notified B.C.’s Ministry of Water, Land and Air Protection that it would be applying for a water discharge permit in anticipation of restarting its Mount Polley copper mine near Likely, B.C.

The company said it would need to release water from a tailings pond, which would grow in volume once mining resumed operations.

Ten years later, it was still waiting for permission to discharge water when, on August 4, 2014, one of the tailings pond embankments gave way – solving the water surplus problem in a most dramatic way.

Documents show that Luke Moger, the company’s project engineer, warned in 2013 that “water in the TSF [tailings storage facility] will reach point of geotechnical instability in two to three years if not addressed.”

The Mount Polley incident became one of B.C.’s worst mining disasters, spilling more than 20 million cubic metres of water and slurry into Hazeltine Creek, Polley Lake and Quesnel Lake.

Documents obtained by Business in Vancouver through a freedom of information (FOI) request confirm that the company had warned a slow-moving government that “geotechnical instability” could result if pressure on the tailings pond dam was not relieved through a discharge of water, although it appears no one predicted such a catastrophic failure.

The documents also suggest the ministry – now the Ministry of Environment – did not appear to consider the matter all that urgent.

While an expert technical panel investigating the disaster concluded that water pressure did not trigger the dam’s failure, it did exacerbate the damage due to the sheer volume of tailings water and slurry that flowed into fish-bearing streams and lakes.

In a separate investigation, Chief Inspector of Mines Al Hoffman concluded in December 2015 that, while Imperial Metals did not contravene any regulations, the company had “failed to operate using best available practices.” He cited “inadequate water management” as one of the problems.

Imperial Metals fired back by pointing out it had applied for a water discharge permit in 2006. When it finally got one in 2012, it was so restrictive that it allowed for only about one-10th of the water that needed to be discharged. The company applied for an amendment and had been given the green light to start a pilot water treatment project in December 2013, but was still waiting for a new discharge permit to be issued when the dam collapsed.

So why did it take so long for the government to approve a water discharge permit?

When provincial officials were either unable or unwilling to answer that question, Business in Vancouver filed a freedom of information request in January 2016, asking for documentation that might provide an answer.

It took the government a year to respond to the request with the release of 3,500 pages of documentation. The documents reveal nothing particularly problematic with the application. If they reveal anything, it’s that the wheels of bureaucracy turn particularly slowly when it comes to getting anything related to a mine approved in B.C.

The Mount Polley mine, idle since 2001, was restarted in 2005, and in 2006 the company began seeking a water discharge permit, although it did not formally apply for one until 2009.

Since the water would need to be treated before it could be released into fish-bearing waters, the company began looking at treatment options. The company decided on a two-phase plan. Until it could get a longer-range treatment plan in place, it decided to go with a stopgap measure to deal with an urgent water volume problem. It settled on reverse osmosis (RO) treatment.

“It is something that we were considering to get us over the hump of needing to get water off of the property, but would give us time to develop a better, long-term solution,” Steve Robertson, Imperial Metals vice-president of corporate affairs, told Business in Vancouver.

Minutes from a November 2013 liaison committee meeting show that Luke Moger, the company’s project engineer, warned that “water in the TSF [tailings storage facility] will reach point of geotechnical instability in two to three years if not addressed.”

Before the mine’s restart in 2005, there was 1.5 million cubic metres of water in the tailings pond. It had grown to 7.6 million cubic metres by May 2013, and the company was forced to raise the dam’s embankments to prevent overtopping.

Above-average runoff and rainfall pushed it to nine million cubic metres, and, in May 2014, the dam came close to being overtopped by water, after a heavy rainfall.

Email exchanges suggest Ministry of Energy and Mines staff were aware of the concerns. But Environment Ministry staff seemed more concerned about water quality than quantity.

In a response to the company’s plan to use reverse osmosis as a stopgap measure for treating water before discharging it, one ministry staffer questioned the plan: “Holy cow! RO? What has precipitated this decision and why are they in such a rush? This is a super-expensive technology with lots of issues with brines.”

Environment Minister Mary Polak could not be reached for comment, but the ministry makes no apologies for taking its time.

“In the interest of public health and safety, ministry staff must ensure a permit application is not rushed through without gathering the appropriate expertise to make an informed decision,” ministry spokesman David Karn said in an email.

After the dam burst, the reverse osmosis treatment was no longer needed. The company has since repaired the tailings pond, the mine is back in operation, and it has opted for a different water treatment system.

But the company still needs a water discharge permit, and it’s still waiting to get one. 

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