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

Fires on Highway 1, CN mainline keep Ashcroft firefighters busy

Two vehicle fires and a rail fire sparked within an 11-day span

Reports on seniors’ needs, downtown show way forward for Cache Creek

‘I hope they won’t gather dust’ says Cache Creek mayor

Counselling support available for those impacted by wildfires

New, confidential, free service in region designed for families or individuals

Local News Briefs: Come out and rock

Join Rawkn’ Art Camp participants as they show off their accomplishments, and stay for a concert

Do you know these women?

Identity of two subjects of portraits by Ashcroft artist being sought

Fashion Fridays: How to dress and feel powerful

Kim XO, helps to keep you looking good on Fashion Fridays on the Black Press Media Network

‘Easy Rider’ star Peter Fonda dies at 79

Actor and writer was nominated for an Oscar for co-writing the 1969 psychedelic road trip movie

Bob Lenarduzzi out as Vancouver Whitecaps president

MLS team is at the bottom of the Western Conference standings

B.C. daycare operator denies negligence in death of ‘Baby Mac’

Infant died in early 2017 after biting an electrical cord, according to a lawsuit filed by his mom

BC SPCA reopens animal cruelty investigation at Abbotsford pig farm

Additional alleged footage released from Excelsior Hog Farm sparks new investigation

Donor upset no one noticed B.C. school’s sculpture had been missing for a year

Agassiz’s Fraser River Lodge owner baffled how theft went undetected

Purple fentanyl among items seized in B.C. drug bust

Youth being recruited as drivers for more-established drug dealers, police say

Fatal overdoses in B.C. drop 30% during first half of year

A total of 538 people have died between January and June, BC Coroners Service reports

VIDEO: B.C. RCMP officer’s stunt at motorcycle festival prompts internal investigation

The officer was part of a stunt event at the Squamish Motorcycle Festival

Most Read