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

T.W. Paterson column: McLean brothers’ murderous rampage ended quietly

“Shoot! you son of a ——-, shoot! I’m not afraid of an ounce of lead.”

49ers regroup to hold off Lakehill

6-2 victory not one of Cowichan’s best, says coach

Climate strike draws huge crowd in Duncan

Millions strike for climate worldwide

PHOTOS: Young protesters in B.C. and beyond demand climate change action

Many demonstaers were kids and teens who skipped school to take part

Walmart to quit selling e-cigarettes amid vaping backlash

U.S.’s largest retailer points to ‘growing’ complications in federal, state and local regulations

Former B.C. lifeguard gets house arrest for possession of child porn

Cees Vanderniet of Grand Forks will serve six months of house arrest, then two years’ probation

Crown alleges resentment of ex-wife drove Oak Bay father to kill his daughters

Patrick Weir alleged in his closing arguments that Andrew Berry is responsible for the deaths of his daughters

How to react to Trudeau’s racist photos? With humility, B.C. prof says

‘We are now treating racism as a crime that you cannot recover from’

‘I’d do it again,’ says B.C. man who swam naked, drunk in Toronto shark tank

David Weaver, of Nelson, was drunk when he went to Ripley’s Aquarium in Toronto on Oct. 12 2018

Victoria man spots online photo of his totem pole 11 years after it was stolen

Mark Trueman restored the pole himself before it was stolen off of his property in Duncan

VIDEO: Fire destroys Williams Lake strip club targeted by past arson attempts

Diamonds and Dust Entertainment Lounge destroyed by fire, as well as New World Tea and Coffee House

Trudeau seeks meeting with Singh to apologize for blackface, brownface photos

‘I will be apologizing to him personally as a racialized Canadian,’ Trudeau said Friday

Most Read