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

Oversize load collides with Highway 1 overpass in Chilliwack

Traffic disrupted eastbound around Lickman Road over pass Monday morning

Harrison workers back on the job

Union calls new agreement ‘a good compromise’

Campfire ban coming into effect across West Coast

The Coastal Fire Centre says bans will begin on Wednesday

Heat warning issued for Metro Vancouver

Inland areas expect to hit at least 26 degrees for daytime highs

Trudeau asks transport minister to tackle Greyhound’s western pullout

Prime Minister Justin Trudeau says he’s asked Transport Minister Marc Garneau to find solutions in Greyhound Canada’s absence.

Hub for mental health and addictions treatment opens at B.C. hospital

St. Paul’s Hospital HUB is an acute medical unit that includes 10 patient beds

Glow Langley returns bigger and brighter this Christmas

Organizers will also introduce Harvest Glow — a celebration of autumn

Restaurant Brands International to review policy over poaching employees

One of Canada’s largest fast-food company to review ‘no-poach’ franchise agreements

Calgary family’s vacation ends in tragedy on Texas highway

Three people died and four others were injured in the crash

Union construction cost competitive, B.C. Building Trades say

Non-union firms can bid on infrastructure, but employees have to join international unions

Trudeau to shuffle cabinet ahead of Liberals’ team for 2019

Trudeau could lighten the work loads of cabinet ministers who currently oversee more than one portfolio

Car calls 911 on possible impaired B.C. driver

A luxury car automatically calls Princeton police to scene of crash involving alcohol

BC Games marks 40 years in 2018

Cowichan Games a milestone for BC Games Society

Most Read