Williams Lake Mayor Walt Cobb and Cariboo Regional District Chair Al Richmond listen to the findings of the independent panel that investigated the Mount Polley Mine breach. 'I'm glad the report is out

Williams Lake Mayor Walt Cobb and Cariboo Regional District Chair Al Richmond listen to the findings of the independent panel that investigated the Mount Polley Mine breach. 'I'm glad the report is out

Mount Polley Mine tailings impoundment was on the brink of failure

Mount Polley Mine's tailings impoundment was a mechanism on the brink of failure, experts said.

Mount Polley Mine’s tailings impoundment was a mechanism on the brink of failure, according to the findings of the independent investigation panel.

“The design did not take into account the complexity of the sub-glacial and pre-glacial geological environment associated with the perimeter embankment foundation,” panel chair Dr. Norbert Morgensten said as the panel released its report on the Aug. 4 breach during a press conference in Victoria Friday.

“The weight of the dam was too much for the weak materials in the foundation to bear,” panel member Steven Virk said.

The weaker area determined as glaciolacustrine (GLU) was in a small localized area where the breach occurred.

It went undetected because the original drilling and subsurface investigations were not designed to detect those kinds of small features.

The design didn’t appreciate how important they were to the stability of the structure and particularly the change of behaviour that occurred as the dam was heightened and reached a certain elevation, Virk said.

Not taking into account the glacial environment characterization could be likened to a creating a loaded gun, Morgenstern said.

“But if constructing unknowingly on this upper GLU deposit constituted loading the gun, building with the steep 1.3 metre to one metre steep slope pulled the trigger,” he added.

The investigation found no evidence of failure due to human intervention, overtopping, or piping and/or cracking resulting in internal erosion.

It also indicated that the water accumulation within the TSF was not a cause of failure, however Virk said because of the 10 million cubic metres of water that was present more tailings were released once the breach occurred.

“What we often see in these kinds of failures is a mud flow and tailings come out in a liquefied state. That didn’t happen here. The tailings came out by erosion.”

Cariboo-area politicians who gathered at the Pioneer Complex Friday to hear the report reacted afterwards with a mix of relief and uncertainty.

“We can hopefully put some closure to the issue,” Cariboo Chilcotin MLA Donna Barnett said. “August 4 was a devastating day, and something none of us wants to see again.”

Barnett said the expertise of the panel and the explanation that was given in laymen’s terms and the depth of the investigation was very well done.

Cariboo Regional District Chair Al Richmond said it is very fortunate no one was hurt or killed.

“We have the opportunity to hope they implement the changes the mining minister is saying the panel has recommended and move forward with the importance of the mine in the area to see if at all possible it can begin again,” Richmond said. “We certainly know now that the use of that tailings storage facility is some time off.”

Richmond said the report’s recommendations will benefit the Cariboo because additional work will have to be done on tailings storage facilities.

“I am glad they have set some tight timelines on that,” he said. “”We have to make them safer and rebuild public confidence in mining.”

Agreeing it was good that the CRD film of the breach unfolding proved helpful to the investigators, Richmond was quick to credit the CRD emergency response team who worked with the RCMP and provincial government and made a decision to get in the air to see what was happening that day.

“It was team thing of everyone pulling together,” Richmond said.

For Mayor Walt Cobb the report delivered good and bad news.

“The good news is that nobody really did anything wrong, it’s one of those things that happened, but the bad news is we still have uncertainty and don’t know when we’re going to be able to get the mine open,” Cobb said. “Hopefully they will get the startup permit in place and be able to use the Springer Pit for putting the tailings in right now.”

On Saturday the mine’s owner said it agreed with the panel’s findings.

“The  independent panel’s conclusion that the perimeter embankment of the Tailings Storage Facility (TSF) failed because a glacio-lacustrine layer lying approximately eight metres below the base of the dam in the area of the breach was not as strong as had been assumed in original design of the TSF,” Imperial Metals said in a statement. “Had the GLU beneath the TSF been as strong as assumed by design criteria, the “sudden and unanticipated” failure would not have occurred.”

 

Both the Williams Lake and Soda Creek Indian Bands received a report from the panel prior to its release to the public.

 

A joint statement from the bands is expected, WLIB economic development officer Kirk Dressler said.

Just Posted

Williams Lake courthouse. (Monica Lamb-Yorski photo - Williams Lake Tribune)
Preliminary inquiry gets underway May 17 into 2018 murder north of Williams Lake

Wyatt Lee Boffa, Daine Victor Stump are charged with first degree murder

Talia McKay of Williams Lake is a burn survivor who remains grateful for the support she received from the Burn Fund (Monica Lamb-Yorski photo - Williams Lake Tribune)
’You have to allow yourself the grace to heal’: B.C. burn survivor reflects on her recovery

Learning how to stand straight and walk again was a feat said Williams Lake resident Talia McKay

As a former reporter and editor at the Tribune, Diana French carries on sharing her ideas through her weekly column. (Photo submitted)
FRENCH CONNECTION: Worth taking another look at hemp for paper production

Ninety years after being deemed illegal, few are afraid of marijauna

Ranch Musings columnist David Zirnhelt. (File photo)
RANCH MUSINGS: Milking cows and strangers on the premises

Cows in a milking barn may get upset if a stranger comes

Lake City Secondary School Grade 12 students Haroop Sandhu, from left, Amrit Binning and Cleary Manning are members of the school’s horticulture club. (Monica Lamb-Yorski photo - Williams Lake Tribune)
LCSS horticulture club a growing success

Aspiring gardeners at a Williams Lake secondary school are earning scholarship dollars… Continue reading

Daily confirmed COVID-19 cases reported to B.C. public health, seven-day rolling average in white, to May 12, 2021. (B.C. Centre for Disease Control)
B.C. preparing ‘Restart 2.0’ from COVID-19 as June approaches

Daily infections fall below 500 Friday, down to 387 in hospital

Cannabis bought in British Columbia (Ashley Wadhwani/Black Press Media)
Is it time to start thinking about greener ways to package cannabis?

Packaging suppliers are still figuring eco-friendly and affordable packaging options that fit the mandates of Cannabis Regulations

A vial of AstraZeneca vaccine is seen at a mass COVID-19 vaccination clinic in Calgary, Alta., Thursday, April 22, 2021. Dr. Ben Chan remembers hearing the preliminary reports back in March of blood clots appearing in a handful of European recipients of the Oxford-AstraZeneca COVID-19 vaccine. THE CANADIAN PRESS/Jeff McIntosh
Science on COVID, VITT constantly changing: A look at how doctors keep up

While VITT can represent challenges as a novel disorder, blood clots themselves are not new

Poached trees that were taken recently on Vancouver Island in the Mount Prevost area near Cowichan, B.C. are shown on Sunday, May 10, 2021. Big trees, small trees, dead trees, softwoods and hardwoods have all become valuable targets of tree poachers in British Columbia as timber prices hit record levels. THE CANADIAN PRESS/Jen Osborne.
Tree poaching from public forests increasing in B.C. as lumber hits record prices

Prices for B.C. softwood lumber reached $1,600 for 1,000 board feet compared with about $300 a year ago

The warm weather means time for a camping trip, or at least an excursion into nature. How much do you know about camps and camping-related facts? (John Arendt - Summerland Review)
QUIZ: Are you ready to go camping?

How many camp and camping-related questions can you answer?

On Friday, May 14 at Meadow Gardens Golf Club in Pitt Meadows, Michael Caan joined a very elite club of golfers who have shot under 60 (Instagram)
Crowds at English Bay were blasted with a large beam of light from an RCMP Air-1 helicopter on Friday, May 14. THE CANADIAN PRESS/Marc Grandmaison
Police enlist RCMP helicopter to disperse thousands crowded on Vancouver beach

On Friday night, police were witness to ‘several thousand people staying well into the evening’

People shop in Chinatown in Vancouver on Friday, February 5, 2021. THE CANADIAN PRESS/Jonathan Hayward
Vancouver community leaders call for action following 717% rise in anti-Asian hate crimes

‘The alarming rise of anti-Asian hate in Canada and south of the border shows Asians have not been fully accepted in North America,’ says Carol Lee

Sinikka Gay Elliott was reported missing on Salt Spring Island on Wednesday, May 12. (Courtesty Salt Spring RCMP)
Body of UBC professor found on Salt Spring Island, no foul play suspected

Sinikka Elliott taught sociology at the university

Most Read