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

The end of an Echo

Invermere Valley Echo shuts down operations in Columbia Valley

Creating a new narrative for Canal Flats

Economic development consultant hired, lists vision for next 90 days

UPDATE: Crews battle as wildfires rage in B.C. Interior

Crews brace for another day on B.C. firelines as no let up is likely

VIDEO: B.C. wildfires by the numbers

Wildfires continue to engulf regions of B.C.’s forests and communities.

VIDEO: More than 180 wildfires burning across B.C.

Firefighters from other provinces called in to assist

DTSS Grad March 2017

DTSS Grad March 2017

59 cats seized in Chase

59 neglected and injured cats were seized from a property in Chase

Soundgarden singer Chris Cornell dead at age 52

The singer/songwriter passed away early Thursday morning in Detroit

Paying tribute to a primeval passage

Uninterrupted celebrates the Adams River sockeye run in an extraordinary way.

UPDATE: Pemberton Music Festival cancelled, no automatic refunds

In the past, the music festival located in Pemberton drew large crowds last year of 180,000 fans

Medical wait times cost B.C. patients $2,300 each

New Fraser Institute report places B.C. at second worst in costs associated with long wait times

UPDATE: 22 killed at Ariana Grande concert

Witnesses reported hearing two loud bangs coming from near the arena’s bars at about 10:35 p.m.

One in three Canadian high school students have rode with drinking drivers, study reveals

Nearly one in five rode with a driver who’d been smoking pot

Top court to hear federal government’s appeal on residential school records

A lower court judge ruled to destroy the stories after 15 years unless consent is given to preserve

Most Read