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

Still barriers to abortion access on Vancouver Island

Experts say transportation, support, doctors can be barriers to accessing abortion

Victoria Police host Faith-Based Safety Forum in light of recent religious attacks

More than 35 faith-based leaders voice concerns, air questions

Kelowna toddler suffers cracked skull after fall from balcony

Neighbour who found the two-year-old boy said he has a bump the size of a golf ball on his head

Greater Victoria wanted list for the week of May 21

Greater Victoria Crime Stoppers is seeking the public’s help in locating the… Continue reading

POLL: Were you satisfied with the Game of Thrones series finale?

Millions gathered in front of their televisions Sunday night to watch the… Continue reading

RCMP probe if teen was intentionally hit with ski pole by mystery skier on B.C. mountain

The incident happened on March 20 on Grouse Mountain. Police are urging witnesses to come forward

Support growing for orphaned Okanagan child after father dies in highway crash

Family thanks emergency crews for assistance in traumatic incident

Pipeline protester chimes in on Justin Trudeau’s B.C. fundraising speech

The government purchased the Trans Mountain pipeline and expansion project for $4.5 billion

Baby boom seniors putting pressure on B.C. long-term care: report

B.C. leads Canada in growth of dementia, dependence on care

UPDATED: B.C. man says he’ll take People’s Party lawsuit as far as he can

Federal judge shut down Satinder Dhillon’s ‘nonsensical’ motion to bar use of PPC name in byelection

Canada stripping citizenship from Chinese man over alleged marriage fraud

The move comes amid severely strained relations between Ottawa and Beijing

Most Read