Repair and temporary dam at Mount Polley Mine near Williams Lake.

Mount Polley design, steep additions led to failure

Glacial layer in dam base not understood, plans to buttress slope put off until weight of water and tailings caused breach

The Mount Polley mine dam failed because of an overlooked glacial material layer in the foundation and a series of steep additions that eventually overcame it, an independent engineering review has concluded.

“Basically the weight of the dam was too much for the weak materials in the foundation to bear,” said U.S. consulting engineer Steven Vick, one of three experts called in to examine the failure that caused the dam to breach and fail in August 2014.

The report concludes that the concrete-like glacial till material in the base of the dam wasn’t understood in enough detail when the dam was designed and built in 1997. Later raising of the dam to hold more water and tailings weakened the base layer and led to the failure.

Vick said the additions to the dam were built at a steeper slope than the original dam, and plans to buttress the area were delayed until it was too late.

Energy and Mines Minister Bill Bennett said the report shows there were no warning signs, and no surface inspections could have detected the problem that was overlooked in the design and original construction.

Two more investigations of the mine failure are pending. Bennett said the Chief Inspector of Mines is likely to release his report by June, and the Conservation Officers’ Service will also report when its investigation is complete.

Bennett said the government is willing to see the Mount Polley mine reopen, but the other investigations must be complete first. The parent company Imperial Metals has applied to use an existing pit to store tailings and resume operations without using the original tailings pond again.

 

Just Posted

Okanagan-Shuswap Weather: Most long-weekend rain has already fallen

A mix of sun and cloud is expected for the last two days of the the Victoria Day weekend.

Update: Mother dead, youth in critical condition after carbon monoxide poisoning at Sandy Point Campground

The woman was found unresponsive insider her tent and the youth was taken via air ambulance to hospital

Penticton Indian Band councillor trying for federal seat

Joan Phillip acclaimed as NDP candidate for Central Okanagan-Similkameen-Nicola

Former Greyhound bus drivers gather in the Okanagan for one last hurrah

Bash kicks off Friday in Penticton and runs until Sunday

Some South Okanagan students are $1,000 richer

Million Dollar Bursary Program offers bursaries each year to Interior Savings’ young members

Weather holds up for Rutland May Days

60th annual May Day midway, market and entertainment saw hundreds of attendees

Raptors beat Bucks 118-112 in 2OT thriller

Leonard has 36 points as Toronto cuts Milwaukee’s series lead to 2-1

South Okanagan runners take top spots in Peach City RunFest

Both the top male and female half-marathon winners were from Penticton

Former Greyhound Canada employees gather in Okanagan to say a final farewell

“Greyhound may take our jobs but they will never take our friendships,” says former bus driver

Kelowna firefighters douse blaze in hedges

The cause of the fire on Renfrew Road is under investigation.

‘Teams that win are tight’: B.C. Lions search for chemistry at training camp

The Lions added more than 50 new faces over the off-season, from coaching staff to key players

Rescue crews suspend search for Okanagan kayaker missing for three days

71-year-old Zygmunt Janiewicz was reported missing Friday

Okanagan Springtime Regatta draws more than 50 sailboats

Sailors treated to windy, excellent long weekend conditions on Okanagan Lake in Kelowna

B.C. VIEWS: Reality of our plastic recycling routine exposed

Turns out dear old China wasn’t doing such a great job

Most Read