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

RCMP officer reaching out to youth about intimate partner violence

Chilliwack officer and friends of Maple Batalia team up to encourage bystanders to speak up

Harrison approves budget, considers future of business tax rates

Residents and businesses will see a 2.37 per cent tax increase for 2019

Chilliwack-Kent MLA unimpressed with ‘classic NDP high-tax-and-spend budget’

Laurie Throness said there was nothing in Tuesday’s presentation for Chilliwack

ACES grows the love of gardening with annual seed exchange

The event will be returning to Harrison Mills Community Hall on March 1

Murder charge formally dropped against woman accused in downtown Chilliwack killing

Stay of proceedings ordered for Victoria Purcell; Kirkland Russell to be sentenced for manslaughter

VIDEO: Wheelchairs teach Agassiz students acceptance through sport

Teacher Donna Gallamore brought wheelchairs to the Kent Elementary for learning and fun

UPDATE: Woman, off-duty cop in critical condition after stabbing outside B.C. elementary school

The officer was interceding in an alleged assault when he and the woman were stabbed

5 to start your day

Two people are in critical condition after stabbing, searchers recover body of missing snowshoer and more

‘A little baloney’ in PM’s claim about solicitor-client privilege on SNC-Lavalin

The Conservatives and NDP want Trudeau to waive that privilege so Wilson-Raybould can offer her side of the story

Proposed edible pot rules are wasteful, would leave products tasteless: critics

When Canada legalized weed last fall, it only allowed fresh or dried bud, oil, plants and seeds

Samsung folding phone is different – but also almost $2,000

But most analysts see a limited market for foldable-screen phones

Alcohol policies fizzle for Canadian governments as harms overflow: reports

About 80 per cent of Canadians drink, and most enjoy a drink or two

Ontario man accused of killing 11-year-old daughter dies in hospital, police say

Roopesh Rajkumar had been hospitalized with what police described as a self-inflicted gunshot wound

Most Read