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

Restorative justice key for North Okanagan society

National Restorative Justice Week begins Sunday

Hall call for Vernon’s Ken Holland

Four-time Stanley Cup-winning GM of Detroit Red Wings to be inducted into BC Sports Hall of Fame

Vernon on track to record same number of overdose deaths as last year

128 people died of overdoses in September across the province

Vernon rallies around family battling throat cancer news

The Thomas family is one of the many that are financially vulnerable to unexpected personal crises.

Your weekday weather update

Flurries and more rain anticipated for the Okanagan - Shuswap

Protesters confront Environment Minister in B.C.

Protesters wanting more for killer whales confront Catherine McKenna

Humans reshaping evolutionary history of species around the globe: paper

University of British Columbia researcher had the paper published in the Proceedings of the Royal Society

Toronto ‘carding’ activist Desmond Cole stopped by police in Vancouver

Cole says his experience reveals what daily life is like for black and Indigenous residents

Commercial trucks banned from left lane of Coquihalla

B.C.’s Ministry of Transportation has introduced a new program that hopes to prevent accidents and closures on the Coquihalla Highway.

Okanagan pickleball pair win bronze at nationals

Vernon and Kelowna players reach podium in California

B.C. firefighters rescue horse stuck in mud

‘It happens more often than you’d think,’ says deputy chief

Couple allegedly caught staking out Okanagan home

The man and woman were seen in a black Suzuki Tracker with a white back

Silver Star nordic trails open Friday

Great early season conditions at North Okanagan resort and at Sovereign Lake Nordic Centre

Most Read