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

Greater Victoria enjoys sunny first day of spring

Summer-like temperatures of 21 degrees hit Wednesday for first day of spring

Discovery Island wolf continues to thrive

The wolf, known as ‘Takaya’, has lived on the island for seven years

Victoria police search for missing man, his vehicle and travel trailer

Last seen on March 17 driving white Honda Ridgeline bearing B.C. licence plate CG 4316

Bitter Saturna land-use dispute highlights legal grey areas

Unhappy Tsawout accuse leadership of cultural destruction

Saanich forwards student-targeted development to public hearing

Proposed development advertises itself to individuals who want a car-free lifestyle

VIDEO: Can you believe it? This B.C. hill pulls cars backwards up a slope

Sir Isaac Newton had clearly never been to this Vernon anomaly when he discovered gravity

POLL: When do you think the next major earthquake will hit Vancouver Island?

According to seismologists, Vancouver Island is overdue for a magnitude 7 earthquake.… Continue reading

European, Canadian regulators to do own review of Boeing jet

Air Canada plans to remove the Boeing 737 Max from its schedule at least through July 1

Prime minister defends Liberal budget measures as sales effort gets underway

Conservatives under Andrew Scheer say it’s a spree funded by borrowing against the future

Mayor meets with B.C. health minister on homeless taxi transfers

Two homeless people were discharged from Surrey Memorial and sent to a Chilliwack shelter

B.C. lottery winner being sued by co-workers

They claim he owes them $200,000 each, in a lawsuit filed in B.C. Supreme Court in Vancouver

Teacher reprimanded for conduct towards special needs student

Alan Stephen Berry told vice principal he did not have time to use positive strategies

Volunteer green team joins forces to restore local habitats

Partnerships with schools educate and facilitate remediations

Having phone within sight while driving does not violate law: B.C. judge

The mere presence of a cell phone within sight of a driver is not enough for a conviction, judge says

Most Read