QUESNEL, B.C. — A tailings pond that breached Monday, releasing a slurry of contaminated water and mine waste into several central British Columbia waterways, was growing at an unsustainable rate, an environmental consultant says.
Brian Olding, who operates Brian Olding and Associates Ltd., said Imperial Metals Corp. (TSX: III) had been working on fixing the problem. Olding said he was hired by the company as well as the Williams Lake and Soda Creek First Nations to review the company’s plans to treat and release water as part of the province’s effluent release permitting process.
“More water’s coming in over the year than they could deal with,” Olding said. “They just kept building the walls up higher and higher every year and it got to the point where that was untenable.”
He said the firm was seeking a permit to treat and release some of the water to keep the size of the pond in check in its Mount Polley Mine, an open pit gold and copper mine about 140 kilometres southeast of Quesnel.
The earthen dam at one end of the four-kilometre long pond breached early Monday morning, sending a 45-metre wide wall of water and mining debris into local creeks and lakes, and prompting drinking water bans on Quesnel Lake, Polley Lake, Hazeltine Creek, Cariboo Creek and the Quesnel River up to its intersection with the Fraser River.
Olding described the walls on the tailings pond as “very high.”
No analysis of the dam’s structural integrity was done as part of the review, he said.
“I requested a structural engineering company be involved, and that was nixed. They did not want to deal with that problem at that time.”
Nor was an analysis of groundwater underneath the dam conducted, said Olding.
B.C. Energy and Mines Minister Bill Bennett said he was told of an incident a few months ago where the water in the tailings pond got a little high.
“They’ve been monitoring it and reporting to the ministry every since then. Water levels were normal. In fact, they were lower than the level that were regulated, so we’re just not sure yet how this happened.”
On Tuesday, the Vancouver-based mining firm said the situation has stabilized.
In a news release, Imperial Metals said the cause of the breach is unknown and there was no indication of trouble before a section of the earthen dam crumbled before dawn on Monday.
“Our first priority is the health and safety of our employees and neighbours, and we are relieved no loss of life or injury have been reported. We are deeply concerned and are working to mitigate immediate effects and understand the cause,” the company said.
Bennett, who was travelling to the area on Tuesday, said government and company officials will get to the bottom of what happened and make sure it doesn’t happen again.
“We don’t know how bad, we don’t know the quality of the water that was in the tailings pond,” he said. “I am advised it was fairly high quality water and I hope that turns out to be the case.”
“We have to make sure the water the people are using is safe and we need to do some work to clean up whatever debris has come out of the dam,” Bennett added.
Olding said the tailings’ water is likely to contain metals such as selenium, cadmium and copper, among other contaminants. Although such materials occur naturally, they are considered toxic in higher concentrations.
Not only is the water potentially hazardous, so are the tailings sediments carried along with it, he said.
“You don’t know how far they’re going to travel until you check it out and you don’t know what’s in those sediments. If they dry out on the side, and grass starts to grow on them, and animals start to eat them, and Indians start killing moose, bear, whatever else eats there, then you’ve got a human contaminant issue.”
Imperial Metals shares plunged Tuesday, the first day of trading after a holiday weekend. The stock (TSX:III) was down nearly 40 per cent at mid-afternoon on the Toronto Stock Exchange, trading at $10.25, down $6.55 from the Friday close. Earlier, the shares fell as low as $9.06, the stock’s lowest intraday price in more than a year.