By Sage Birchwater —
It’s been eight months since the August 4 breach of Mount Polley Mine’s tailings storage facility (TSF) spilled 25 million cubic metres of mining effluent and scour material into the pristine waters of Quesnel Lake.
The volume of the spill was so significant that it caused the level of the 266-square-kilometre (103-square-mile) Quesnel Lake to rise seven centimetres overnight.
The short- and long-term environmental impact of having this much toxic material dumped into one of the deepest and purest fjord lakes in the world has not yet been determined. Safe to say, this watershed has been changed forever.
At the end of January, 2015, an independent panel of mining engineers commissioned by the provincial government to assess the physical reasons for the spill, determined that a weakness in the foundation of the dam played a significant role in the breach. The panel said a layer of glacial silt or glaciolacustrine (GLU) beneath the TSF, made the impoundment unstable. It also found that outside slopes of the TSF dam were too narrow and steep, and that if the embankment had been widened by adding more rock buttressing to the perimeter, the breach would not have occurred.
Still to be determined are the human causes for the dam failure.
Both Premier Christy Clark and Energy and Mines Minister Bill Bennett have vowed they will leave no stone unturned to get to the bottom of why the breach occurred.
It’s not clear how thoroughly the government will investigate its own role in the disaster.
Was there adequate government oversight? Had mine inspections become lax? Had government cutbacks inhibited the ability of regulators to perform their duties?
Equally concerning are questions around the management of Mount Polley Mine. Did the company put profits ahead of careful mining practices? Was the company deaf to warnings by employees and its professional experts? Will anyone be held accountable for the dam failure?
Jacinda Mack, mining co-ordinator for the Northern Secwepemc Tribal Council (NStQ), says it will take a long time for the government and the mining industry to regain the public trust.
“The Mount Polley Mine disaster wasn’t only a dam breach, it was a breach of trust as well,” she says.
Mack acknowledges that the mining company has worked tirelessly to repair the damage since the spill, but there is still a long, uphill battle ahead. With the spring freshet just around the corner, the challenge to reduce the amount of effluent flowing into Quesnel Lake will be difficult.
She says experts hired by the NStQ are working with experts hired by Mount Polley Mine to give a balanced approach to the cleanup.
“We’re working with the mine to make sure they get the job done,” says Mack. “We’ve got our experts saying, how about this, or have you thought about that. Engineer to engineer, specialists of fish habitat talking shop to each other. We are coming up with the best solution together.”
Another important partner in the disaster mitigation is the Quesnel River Research Centre (QRRC), located just downstream from Likely on the Quesnel River.
Sam Albers, who manages the Centre for the University of Northern BC, says it was fortunate the QRRC had equipment on site when the breach occurred on August 4.
“We were able to take water samples and tailings debris samples immediately,” he says. “We observed the level of Quesnel Lake rise seven centimetres after the breach, once the lake sloshed back and forth for 12 to 14 hours.”
With so much going on, Albers said it was a challenge to think coherently.
“Then we realized we were never going to get those early days back if we didn’t start gathering data immediately,” he says.
One of the tasks of the QRRC was to track the behaviour of the sediment plume trapped beneath a layer of cold water known as a thermocline, 30 metres below the surface. They watched the plume spread eastward up the lake as far as the junction with the North Arm. Then in December as the surface temperature of the lake dropped, the sediment trapped beneath the thermocline was flushed out into Quesnel River.
Albers says the QRRC is tracking many unknowns, such as to what extent the breach will impact the food web. So far, he says, there are more questions than answers.
“How resilient is Quesnel Lake to this mine breach disturbance?” he says. “How much can the lake take a kick? Food web analysis is not simple. How do particle size and metal concentrations interact with zooplankton? How leachable are these materials?”
Albers says the work being done by the QRRC is tiny compared to the gargantuan rehabilitation effort of Mount Polley Mine, but it’s important none the less.
“We’re putting together grants to attract folks who will ask the questions that are not conventional,” he says. “We’ve got students exploring uncharted territory.”
Sage Birchwater moved to the Cariboo-Chilcotin in 1973. He spends his time freelancing, authoring books, and with Caterina, hanging out with their dog and cat, gardening, and being part of the rich cultural life that is the Cariboo Chilcotin Coast.