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

Revelstoke’s draft budget would mean a 4.9 per cent property tax increase

Revelstoke city council will present their draft budget for public feedback in… Continue reading

Revelstoke’s Project Prom continues with new volunteer

Amber Hart has taken over the project from her mom

Expect delays on Highway 1 west of Golden due to vehicle fire

Expect delays while driving Highway 1 between Golden and Revelstoke. Drive BC… Continue reading

Source of Turtle Creek contamination identified

Revelstoke Mountain Resort made the repairs immediately

B.C. students win Great Waters Challenge video contest

Video, mural and song about saving the salmon claims the top prize

Eight cases of measles confirmed in Vancouver outbreak

Coastal Health official say the cases stem from the French-language Ecole Jules Verne Secondary

Ontario police field complaints over Amber Alert for missing girl, 11, found dead

Some said the Amber Alert issued late Thursday for Riya Rajkumar disrupted their sleep

Former B.C. premier Gordon Campbell accused of sexual touching

Accuser went to police, interviewed by Britian’s Daily Telegraph

B.C. couple attacked with acid, slashed with knife in Vietnam

Warning, graphic images: Man has burns on 80 per cent of his body, slashed with knife

Northern B.C. First Nation clan says ancient tools found at pipeline work site

Archeologists from the Smithsonian Institute estimate one of the stones found dates back up to 3500 years

Drive BC warning slippery conditions for Okanagan main highways

The region is forecasted to see flurries and snow for the first half of the weekend

Man and woman shot in targeted incident in Kamloops

The shooting happened yesterday afternoon

Names keep adding to vaccine petition started by B.C. mom

Maple Ridge mom started campaign to make vaccination a condition of attending school

Most Read