Mineral and metal mines in B.C. will need to do a better job of managing their tailings ponds under new regulations being implemented by the B.C. government following a Mount Polley mine disaster investigation.
But given that it took six years for Imperial Metals (TSX:III) to get a permit from the Ministry of Environment to relieve pressure on its tailings pond with a release of water, mining companies might be wondering if the B.C. government is also prepared to do a better job in helping them manage water levels.
On August 4, 2014, a tailings pond dam for the Mount Polley copper-gold mine burst, releasing 21 million cubic metres of water and slurry into local waters near Likely, B.C.
Following a 16-month investigation, the Chief Inspector of Mines issued a report December 17 that concluded Imperial Metals would not be held liable because the disaster was largely the result of a design flaw that could not have been anticipated. But the report wasn’t a full exoneration. It took the company to task for failing to follow best practices.
The report generally agrees with an earlier investigation by engineering experts who concluded that a weak foundation of glacial material that gave way under the weight of the dam caused its collapse.
Although water pressure didn’t cause the dam to collapse, it exacerbated the problem by flooding local waters with more water and slurry than might otherwise have been released.
The Chief Inspector of Mines criticized Imperial Metals for its dam and water management practices, pointing to “insufficient beaches and too much supernatant water” as contributing factors.
“We determined that while the mine did not contravene any existing regulatory requirements, its management and operational practices failed in a number of areas such as water management and misplaced confidence in the TSF (tailings storage facility) design,” Chief Inspector of Mines Al Hoffman said in a press release.
Hoffman’s report notes “inadequate water management” as one of the problems with Imperial’s mine management practices.
That prompted Imperial Metals to fire back with revelations that it had been asking the B.C. government for permission to ease the pressure on the dam through a controlled release of water since 2006. That’s when the company says it first applied for a water discharge permit. But it took six years for the Ministry of Environment to issue a permit, and even then, it was “completely inadequate” for the amount of water the company needed to release, according to Steve Robertson, Imperial Metals’ vice-president of corporate affairs.
“There were too many restrictions on how much water could be discharged to the environment,” Robertson said. “We effectively ended up only being able to discharge a small fraction of the water that we wanted to.”
The company applied for an amendment to the permit it received in 2012 to increase the volume of water it could release. In July 2014, it finally received the permit it had been seeking – just one month before the dam broke.
Despite having the permit in hand, the company was unable to release any water until it had built a new water treatment plant, which would have taken several months.
Neither the Ministry of Environment nor the Chief Inspector of Mines have explained why it took several years for Imperial Metals’ water discharge permit application to be approved. Neither responded to requests for interviews.
The Environment Ministry’s reluctance to issue a water discharge permit might be understandable if the water stored behind the dam was highly toxic.But the chemistry of the ore mined at Mount Polley is such that its tailings are relatively clean, with low amounts of sulphide and high amounts of acid-consuming elements and minerals that limit the formation of acids.
That explains why, shortly after the dam’s collapse, water testing indicated that the water released was near drinking-water quality.
“We already have excellent water quality,” Robertson said. “And for it to take that long …”
As a result of the Mount Polley investigation, the Chief Inspector of Mines will require all mines that have tailings ponds to designate a dam safety manager, as well as someone to oversee the dam’s water management. They will also have to have independent technical review boards.
Conspicuously absent from the recommendations, however, is any requirement on the part of the government to issue water discharge permits in a timely fashion.
If six years is a normal timeline for a routine water discharge permit to be issued, it shouldn’t be, Robertson said.
“If there’s anything to learn out of this – and there’s lessons for everybody to learn out of this – I think one of the lessons that the government has is that mine sites need to be able to manage their water.”
