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.

Get local stories you won't find anywhere else right to your inbox.
Sign up here

Just Posted

A 17-year-old snowmobiler used his backcountry survival sense in preparation to spend the night on the mountain near 100 Mile House Saturday, Jan. 16, 2021 after getting lost. (South Cariboo Search and Rescue Facebook photo)
Teen praised for backcountry survival skills after getting lost in South Cariboo mountains

“This young man did everything right after things went wrong.”

Rotary Club of Williams Lake members, including president Mike Austin (second from left), cook up breakfasts during a Stampede breakfast this past summer. (Photo submitted)
ROTARY MONTH: Rotary Club of Williams Lake looking to get back to business

While COVID-19 made most of 2020 and the start of the new… Continue reading

Tribune columnist Jim Hilton captured this photo of the forest floor during a hike in the Helmken Falls area at Wells Gray Provinicial Park. (Jim Hilton photo)
FOREST INK: Forests and its connection to human health, part one

Urbanization and modern lifestyle have diminished possibilities for human contact with nature

Williams Lake physician Dr. Ivan Scrooby and medical graduate student Vionarica Gusti hold up the COSMIC Bubble Helmet. Both are part of the non-profit organization COSMIC Medical which has come together to develop devices for treating patients with COVID-19. (Monica Lamb-Yorski photo - Williams Lake Tribune)
Williams Lake physician part of COSMIC Medical group developing ‘bubble helmet’ for COVID-19

The helmet could support several patients at once, says the group

A scene from “Canada and the Gulf War: In their own words,” a video by The Memory Project, a program of Historica Canada, is shown in this undated illustration. THE CANADIAN PRESS/HO - Historica Canada
New video marks Canada’s contributions to first Gulf War on 30th anniversary

Veterans Affairs Canada says around 4,500 Canadian military personnel served during the war

Conservative Leader Erin O’Toole holds a press conference on Parliament Hill, in Ottawa on December 10, 2020. THE CANADIAN PRESS/Sean Kilpatrick
No place for ‘far right’ in Conservative Party, Erin O’Toole says

O’Toole condemned the Capitol attack as ‘horrifying’ and sought to distance himself and the Tories from Trumpism

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 passer by walks in High Park, in Toronto, Thursday, Jan. 14, 2021. This workweek will kick off with what’s fabled to be the most depressing day of the year, during one of the darkest eras in recent history. THE CANADIAN PRESS/Chris Young
‘Blue Monday’ getting you down? Exercise may be the cure, say experts

Many jurisdictions are tightening restrictions to curb soaring COVID-19 case counts

A health-care worker prepares a dose of the Pfizer-BioNTech COVID-19 vaccine at a UHN COVID-19 vaccine clinic in Toronto on Thursday, January 7, 2021. THE CANADIAN PRESS/Nathan Denette
COVID-19: Provinces work on revised plans as Pfizer-BioNTech shipments to slow down

Anita Anand said she understands and shares Canadians’ concerns about the drug company’s decision

Tourists take photographs outside the British Columbia Legislature in Victoria, B.C., on Friday August 26, 2011. A coalition of British Columbia tourism industry groups is urging the provincial government to not pursue plans to ban domestic travel to fight the spread of COVID-19. THE CANADIAN PRESS/Darryl Dyck
B.C. travel ban will harm struggling tourism sector, says industry coalition

B.C. government would have to show evidence a travel ban is necessary

(Phil McLachlan - Capital News)
‘Targeted’ shooting in Coquitlam leaves woman in hospital

The woman suffered non-life threatening injuries in what police believe to be a targeted shooting Saturday morning

JaHyung Lee, “Canada’s oldest senior” at 110 years old, received his first dose of the COVID-19 vaccine on Thursday, Jan. 14, 2021. He lives at Amenida Seniors Community in Newton. (Submitted photo: Amenida Seniors Community)
A unique-looking deer has been visiting a Nanoose Bay property with its mother. (Frieda Van der Ree photo)
A deer with 3 ears? Unique animal routinely visits B.C. property

Experts say interesting look may be result of an injury rather than an odd birth defect

Most Read