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

PRICK! sees increase in patients

The rainbow friendly service offers STI and HIV screening monthly

First Things First evoking the power of song and play

Environmental group educating through entertainment

Super blood wolf moon fills Okanagan skies, to photographers’ delight

Photographers had a rare chance Sunday to capture a rare lunar eclipse

Creator of trans webcomic series Assigned Male coming to Penticton

Stop is part of French-Canadian author Sophie Labelle’s Serious Trans Vibes Tour

UPDATE: B.C. legislature managers accused of excessive travel, personal expense claims

Clerk Craig James, security chief Gary Lenz call allegations ‘completely false’

China demands US drop Huawei extradition request with Canada

China detained two Canadians on Dec. 10 in an apparent attempt to pressure Canada to release Meng

9 brains, 3 hearts: Some wild facts about octopuses

Things to know about the giant Pacific octopus, which is naturally found in the waters of the U.S. West coast, the Aleutian Islands and Japan

Hollywood announces 2019 Oscar nominations

Netflix has scored its first best picture nomination, something the streaming giant has dearly sought

B.C. man fined $10,000 after leaving moose to suffer before death

Surrey man was convicted last week on three Wildlife Act charges

Man charged in 7-Eleven fire in Shuswap granted bail

Accused facing arson charges released with 23 conditions including a 7 p.m. curfew

Signs commemorating Japanese interment in the Shuswap planned

Information on each of the five internment camps in the area will be provided at camp locations

‘Blue Monday’ isn’t real, but depression can be

CMHA encourages people to prioritize their mental health

Most Read