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

Northwest couples compete at His and Hers golf tournament in Prince Rupert

Kitimat and Smithers couples take home the hardware

100 years since the surrender of Simon Gunanoot

The famed Gitsxan hunter was a fugitive for 13 years

Smithers celebrates National Indigenous Peoples Day

The day included dancing, singing, a moose call contest and a soapberry ice cream tutorial.

UNBC researcher leads study on cannabis-impaired driving

Dr. Russ Callaghan hypothesizes increased motor vehicle collision injuries among young people

Bestselling Indigenous author enlightens Smithers audience on the Indian Act

Bob Joseph is the author of 21 Things You May Not Know About the Indian Act

Video shows fireworks shot at swan in Alberta

Alberta Fish and Wildlife is investigating the incident in Grande Prairie

‘Text neck’ causing bone spurs to grow from millennials’ skulls, researchers say

Technology use from early childhood causing abnormal bone growths in 41 per cent of young adults

B.C. teen killed by fallen tree on field trip remembered as hero

13-year-old Tai Caverhill was the first to spot the tree falling and warned his friends

Surrey RCMP raises Pride flag amid din of protesters

There were about 30 protesters on either side, and 20 Mounties doing crowd control

Should B.C. get rid of Daylight Saving Time?

The province wants to know, as state governments down south make the move

Air Canada reviewing how crew left sleeping passenger on parked plane

In a Facebook post, the woman said she woke up ‘all alone’ on a ‘cold dark’ aircraft

Canadians crash out of Women’s World Cup in 0-1 loss to Sweden

Canada missed a chance to tie the game on a penalty shot

Four-year-old boy assaulted at B.C. soccer game

It happened at a weekend tournament in Ashcroft

Two bear cubs saved near Revelstoke after mother hit by car

Conservation officers trapped the cubs and transported them to a wildlife sanctuary

Most Read