Canadian Mining Disasters and Their Lasting Impacts

By: Laurel Broens

Laurel Broens

Contributing Historian

Laurel is a graduate of the Master of Library and Information Studies program from the University of Alberta and holds a BA in Economics and a BA in Religious Studies from the University of Calgary. She has worked in the information management field for over a decade in a career spanning public and academic libraries and government and legal records management. Laurel is a proud member of the Alberta Union of Provincial Employees (AUPE) and is the current chair of AUPE Local 002, Chapter 002 which represents more than 4700 Government of Alberta administrative and program services workers in the Edmonton area. In her spare time, Laurel runs the popular labour history Twitter account @labour_girl.

Industrial mining has been conducted on the land now called Canada since the late 1700s and is one of the country’s primary industries to this day.[i] The economic and resource benefits of mining have come with a number of costs, including the forced removal of Indigenous Peoples from their traditional territories; exploitative working conditions that have led to death, illness, and injury; and environmental destruction.[ii] In this article, we will explore three of many instances where Canadian mining projects have led to disaster: the 1914 Hillcrest Mine explosion in Alberta, which to this day remains Canada’s deadliest mining disaster; the 1992 Giant Mine bombing in the Northwest Territories, which occurred in the midst of a brutal lockout; and the 2014 Mount Polley tailings pond collapse in British Columbia, which caused widespread environmental destruction that lingers to this day.

Hillcrest Mine Explosion (Alberta, 1914)

On the morning of June 19, 1914, 235 men entered the Hillcrest Mine on the Alberta side of the Crowsnest Pass for what likely seemed like a routine workday. They could not have known that 189 of them would not make the trek home later that evening, becoming victims of what is recognized as Canada’s deadliest mining disaster.

Pump house and number 2 mine entrance at Hillcrest coal mine, Crowsnest Pass, 1914. Image courtesy of the University of Calgary & Glenbow Archives.

The Hillcrest Mine was discovered in 1900 by American prospector Charles Plummer Hill, who began developing the mine in 1905. Four years later, Hill sold the mine to a group of developers while remaining on the board of directors. By 1914, Hillcrest employed 377 men earning an average of $125 a month.[iii] Most of the workers lived in the nearby town of Hillcrest, whose population had swelled to nearly 1,000 since the mine opened.

Because of seasonally low demand for coal, the mine was closed June 17 and 18, 1914, though routine inspections were still conducted on schedule. When it reopened on June 19, 228 men entered the mine to begin their shift at 7 a.m., with seven more men joining them two hours later.[iv] At approximately 9:40 a.m., the mine was rocked by an explosion so powerful it destroyed a thick concrete wall above ground[v] and stopped a large electric fan positioned at mine opening No. 1 to draw gases from the mine. A quick-thinking electrician raced to restart the fan, which very likely saved the lives of some of the men, who later escaped from underground. Meanwhile, seeing that the entrance No. 1 was nearly fully blocked by fallen rocks, the remaining men on the surface scrambled to clear debris around entrance No. 2.[vi]

Ignoring the risk of asphyxiation, the earliest rescue group entered the mine unprotected. However, by 10 a.m. assistance had arrived from nearby Blairmore, bringing with them oxygen masks for the rescuers.[vii] By noon, the final survivors had been freed from the mine, and 189 men were still unaccounted for. It took nearly a week to finish recovering their bodies. One man, Sidney Bainbridge, was never found. Many of the men left behind large families; 400 children were made fatherless.[viii]

Circuit Court Judge Arthur A. Carpenter was soon appointed to head the official commission of inquiry investigating the cause of the disaster. The commission began on July 2. Before concluding, the commission heard from numerous witnesses, including Hillcrest Collieries chief engineer William Hutchison, employees who witnessed the disaster, and mine inspection experts.[ix] In the meantime, samples of coal dust from the mine were sent to a US Department of the Interior station in Denver, Colorado, for testing, which eventually determined that the dust was highly explosive.[x] Carpenter released his final report on October 20, concluding “that the disaster was caused by an explosion of gas, the origin and seat of which is unascertainable, this explosion being augmented by the ignition of dust throughout the mine.”[xi]

While operations at Hillcrest resumed shortly after the disaster with few safety updates, Alberta’s mining legislation was updated to include provisions for better regulation of coal dust, and the province increased its investment in mining education and training in rescue work. Through a combination of workers’ compensation and federal, provincial, and private donations, each widow was awarded $20 a month, paid out to a total of $1,800 (approximately $46,000 in 2023 dollars).[xii] In 1926, a second deadly blast roared through the mine, killing two men. Hillcrest continued operations until December 1, 1949, when it was shut down for the last time and its entrances were sealed.[xiii]

Giant Mine Bombing (Northwest Territories, 1992)

Disaster site: Giant mine, set against Yellowknife’s skyline. Image courtesy of the Toronto Public Library & Toronto Star Archives.

The Giant gold mine, located to the north of Yellowknife, Northwest Territories, began production in 1948.[xiv] In 1990, faced with financing problems, Giant Yellowknife Mines Limited sold a number of Canadian properties, including Giant Mine, to Royal Oak Mines for $33 million. Royal Oak quickly began implementing a number of cost-cutting measures, including eliminating positions and replacing management and senior staff.[xv] At the time, the mine employed more than 200 unionized workers who were represented by Local 4 of the Canadian Association of Smelter and Allied Workers (CASAW).[xvi]

By 1992, the mine had become unprofitable, and the relationship between the union and management had grown extremely tense. In April 1992, the CASAW bargaining committee reached a tentative agreement that would freeze wages with an option to renegotiate after three years if the price of gold increased. The contract also reduced worker benefits, removed weekend premium pay, and decreased the frequency of safety inspections. Insulted by the offer, the union voted to reject the agreement.[xvii] On May 22, the day before the workers planned to begin a strike, management locked them out with the intention of bringing in replacement workers.[xviii] A number of union members also crossed the picket lines and continued working throughout the lockout.[xix]

On strike: Striking miners Romeo Berube, 55, left, and Roger Warren, 49, wait in the picket line shack at Gate C, the main entrance at the Giant mine, January 1993. Image courtesy of the Toronto Public Library & Toronto Star Archives.

The lockout was violent from the start, with workers throwing rocks, starting fires, and sabotaging power delivery to the mine. These actions prompted the mine owners to replace their security guards with Pinkerton, an American firm with a reputation for strikebreaking, in an effort to intimidate the workers.[xx] On June 14, a riot broke out when a group of striking workers stormed the mine, damaging property and injuring guards. Throughout the following months, a group of strikers, calling themselves the “Cambodian Cowboys,” broke into the mine on several occasions, stealing and setting off explosives and spray-painting threats in the tunnels.[xxi]

On the morning of September 18, 1992, an explosion shook the mine, instantly killing nine men riding a rail car. Six of the men were CASAW members who had crossed the picket line, while the other three were replacement workers. The RCMP quickly determined that a bomb had been deliberately set near the rail tracks and opened a murder investigation.

Holding On: Carol Riggs, left, is locked in despair with her daughter Lynda over the death of her son Shane in a blast deliberately set in a Yellowknife mine, January 1993. Image courtesy of the Toronto Public Library & Toronto Star Archives.

Following a 13-month investigation, the RCMP zeroed in on 49-year-old Roger Warren as their prime suspect. The night before the bombing, Warren – who owned a pair of boots that matched footprints found at the scene – had been on picket duty. During a police interview in October 1993, Warren confessed to setting the bomb, expressing his disgust for “scabs.”[xxii] During his 1994 trial, Warren attempted to take back his confession but was nevertheless convicted of nine counts of second-degree murder. In 2003, he re-confessed and admitted to acting alone. Warren was granted full parole in 2016 after 20 years in prison and died three years later.[xxiii]

In the meantime, the Canada Labour Relations Board held a hearing and found that Royal Oak had committed three bad-faith bargaining violations, the most serious of which was the firing of 49 workers throughout the strike.[xxiv] In November 1993, the board ordered an end to the lockout[xxv] and forced Royal Oak to resubmit the original tentative agreement. This time, the union members voted overwhelmingly to accept it.[xxvi]

After more than 50 years in operation, Giant Mine closed for good in 2004. Following its closure, an environmental assessment found that the site was contaminated with more than 237,000 tonnes of toxic arsenic trioxide dust.[xxvii] In 2014, it was determined that it was too dangerous to remove the arsenic, and plans were made to bury and freeze it in underground chambers. The Yellowknives Dene First Nation community was vocal throughout the remediation process with their concerns about the condition of the mine site and the proposal to store the arsenic underground. However, little has changed since then, and today the mine remains one of the most contaminated sites in Canada.[xxviii]

Monument to miners who died on the job – Yellowknife, NWT. Photo credit: Sandy Campbell. Image courtesy of the University of Alberta.

Mount Polley Tailings Pond Collapse (British Columbia, 2014)

While modern technology and improved safety standards have reduced the danger of mining work itself, the environmental impacts of mining have created their own disasters. One of the most devastating incidents occurred on August 4, 2014, when a tailings dam failure at Mount Polley mine in British Columbia released more than 24 million cubic metres of contaminated wastewater, known as tailings, into Quesnel Lake, Hazeltine Creek, and other bodies of water that local residents relied upon for drinking.[xxix] According to Environment Canada, the Mount Polley waste contained arsenic, lead, and other heavy metals.[xxx]

A still photo taken from video provided by the Cariboo Regional District of a helicopter overflight of the stricken area. Image courtesy of CBC.

Two days after the dam failure, the Government of British Columbia declared a local state of emergency after issuing a water ban for the Quesnel and Cariboo river systems. The government also ordered the Mount Polley Mining Corp., owned by Imperial Metals, to prevent further release of contaminants and to provide environmental impact assessments and cleanup plans.[xxxi] The BC Ministry of Environment had repeatedly warned Imperial Metals that the level of wastewater in its tailings pond was too high, as recently as May 2014.[xxxii]

In July 2016, the province announced updates to BC’s mining code designed to prevent similar environmental disasters. The changes included more stringent design standards for tailings storage and an added requirement in mine permit applications to outline mitigation plans for the risks associated with tailings facilities and dams.[xxxiii] In June 2022, BC’s chief auditor of mines found that while these changes had generally improved mine waste management, they were inconsistently enforced at tailings facilities that were no longer operating.[xxxiv]

Eight years after the breach, in 2022, three engineers were disciplined by the provincial regulatory and licensing body, Engineers and Geoscientists British Columbia. Former engineers Todd Martin and Stephen Rice were fined a combined $225,500 for unprofessional conduct inconsistent with appropriate engineering practices, and junior engineer Laura Fidel was temporarily suspended and ordered to undergo additional training. Engineers and Geoscientists BC also took action by updating professional practice guidelines, clarifying duties, and holding professional development seminars.[xxxv]

An independent report found that the tailings dam had been built on a sloped glacial lake, which weakened its foundation. The design did not adequately take drainage and erosion into account. However, no charges were ever filed against Imperial Metals in what is now known to be the largest mining spill in Canadian history.[xxxvi] While most of the contamination quickly settled at the bottom of the lakes and waterways, small particles are still detectable today.[xxxvii]

[i] John Sandlos and Arn Keeling, “Mining”, The Canadian Encyclopedia (2015).

[ii] John Sandlos and Arn Keeling, Mining Country: A History of Canada’s Mines and Miners, pg.8.

[iii] Frank Anderson, Canada’s Worst Mine Disaster, pg.5–6.

[iv] Steve Hanon, The Devil’s Breath: The Story of the Hillcrest Mine Disaster of 1914, pg.106–109.

[v]Canada’s Deadliest Mining Disaster“,

[vi] Anderson, pg.15–17.

[vii] Ibid., pg.23.

[viii] Ibid., pg.39–41.

[ix] Hanon, pg.196–219.

[x] Ibid., pg.247.

[xi] Ibid., pg.252.

[xii] Ibid., pg.260–263.

[xiii] Anderson, 44.

[xiv] Ryan Silke, “The Operational History of Mines in the Northwest Territories, Canada”, Yellowknife Historical Society, pg.246.

[xv] Ibid., pg.266.

[xvi] Richard Foot, “Giant Mine Murders”, The Canadian Encyclopedia.

[xvii] Sandlos and Arn, Mining Country, pg.181.

[xviii] Emily Blake, “Gold, Arsenic and Murder: A Look at the Complex History of N.W.T.’s Giant Mine”, Toronto Star.

[xix] Silke, “The Operational History of Mines in the Northwest Territories, Canada”, pg.267.

[xx] Foot, “Giant Mine Murders”, The Canadian Encyclopedia.

[xxi] Blake, “Gold, Arsenic and Murder”, Toronto Star.

[xxii] Foot, “Giant Mine Murders”, The Canadian Encyclopedia.

[xxiii] Rachel Zelniker, “A City Divided”, CBC.

[xxiv] Ibid.

[xxv] Blake, “Gold, Arsenic and Murder”, Toronto Star.

[xxvi] Silke, “The Operational History of Mines in the Northwest Territories, Canada”, pg.267.

[xxvii] Charlotte Morritt-Jacobs, “Clean-Up of Notorious Giant Mine in Yellowknife Pegged at $1B, to Take Longer Than Expected”, APTN National News.

[xxviii] Sandlos and Arn, Mining Country, pg.208–209.

[xxix]Mount Polley Mine Tailing Dam Breach”, Government of British Columbia.

[xxx] Yvette Brend, “7 Years Later, 2 Engineers Face Discipline for Actions That Led to Mt. Polley Mine Disaster”, CBC.

[xxxi] Dene Williams and Kirk Moore, “Mount Polley Mine Tailings Spill: Imperial Metals Could Face $1M Fine”, CBC.

[xxxii] Jenni Sheppard, “Mount Polley Mine Tailings Pond Breach Followed Years of Government Warnings”, CBC.

[xxxiii] Dirk Meissner, “B.C. Mining Code Strengthened to Prevent Disasters Like Mount Polley”, CBC.

[xxxiv] Canadian Press Staff, “Regulator Fines Engineers 8 Years after Mount Polley Disaster in B.C.”, CTV News Vancouver.

[xxxv] Ibid.

[xxxvi] Dirk Meissner, “Mount Polley Mine Disaster 5 Years Later; Emotions, Accountability Unresolved”, CBC.

[xxxvii] Lee, “Mount Polley Mine Tailings Present in Quesnel Lake Water Eight Years after Big Spill”, The University of British Columbia.


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