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

Nine fires burning in West Kootenay

All fires considered to be lightning caused.

West Kootenay afternoon storms spark fires

Lots of thunder and lightning, and little rain, as system moves through region

PLACE NAMES: Rossland neighbourhoods, Part 2

Early Rossland’s misaligned townsite additions frustrated the city engineer

Webster students find missing man

Man reported missing from his Warfield home Wednesday night

Getting to know you better: Rossland kids spend day with nature

Third annual bio-blitz brings kids more environmental awareness

10 facts about Father’s Day

Did you know that the special day for dads was first celebrated in 1910?

B.C. university to offer mentorship program for former youth in care

Students using the provincial tuition waiver program will soon be able to form a community at KPU

You might not know these B.C. records are public

Hired a lawyer to file a civil claim? Those are published online

B.C. bus driver loses case to get job back after texting while driving full bus

An arbitator ruled that Tim Wesman’s phone usage was a “a reckless disregard for public safety”

Revamped B.C. Lions set to battle veteran Winnipeg Blue Bombers

The Lions’ first test of the season will be a big one

No business case for Trans Mountain expansion, says former environment minister

Cabinet is expected to announce its decision on the expansion of the Alberta-to-B.C. pipeline by Tuesday

LETTER: British Columbia’s forest industry crisis being made worse

Andrew Wilkinson warns of regulatory overload by John Horgan’s NDP

Convicted B.C. child abductor Randall Hopley back in custody 6 months after release

Correctional Services Canada could not provide further details due to privacy concerns

Bears have killed 17 people in B.C. since 1986

Number of bear complaints and bears killed rose sharply during same period

Most Read