Mount Polley mine disaster

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Mount Polley mine disaster
Mount Polley Mine site.jpg
24 July 2014
Mount Polley Mine dam breach 2014.jpg
5 August 2014
USGS satellite photos of the Mount Polley Mine site before and after the dam breach
Date4 August 2014
LocationQuesnel Lake, British Columbia, Canada
Coordinates52°30′48″N 121°35′47″W / 52.513437°N 121.596309°W / 52.513437; -121.596309Coordinates: 52°30′48″N 121°35′47″W / 52.513437°N 121.596309°W / 52.513437; -121.596309
CauseFailure of tailings pond dam
FootageFootage: Youtube

The Mount Polley mine disaster is an environmental disaster in the Cariboo region of central British Columbia, Canada, that began 4 August 2014 with a breach of the Imperial Metals-owned Mount Polley copper and gold mine tailings pond, releasing its water and slurry with years worth of mining waste into Polley Lake. The spill flooded Polley Lake, its outflow Hazeltine Creek, and continued into nearby Quesnel Lake and Cariboo River. By 8 August the four-square-kilometre (1.5 sq mi) sized tailings pond had been emptied of the majority of supernatant (process water) that sits atop the settled solids (mining waste, or 'tailings'). Water tests showed elevated levels of selenium, arsenic and other metals similar to historical tests before the disaster. The cause of the dam break has been investigated with a final report published 31 January 2015. Imperial Metals had a history of operating the pond beyond capacity since at least 2011.

Dam breach[edit]

The Mount Polley open pit copper and gold mine disaster in the Cariboo region of British Columbia began in the early morning of 4 August 2014 with a partial breach of the tailings pond dam, releasing 10 million cubic metres (10 billion litres; 2.6 billion US gallons) of water and 4.5 million cubic metres (4.5 billion litres; 1.2 billion US gallons)[2] of slurry into Polley Lake.[3] Another source gives the quantity spilled as: 7.3 million cubic metres (7.3 billion litres; 1.9 billion US gallons) of tailings, 10.6 million cubic metres (10.6 billion litres; 2.8 billion US gallons) of water, and 6.5 million cubic metres (6.5 billion litres; 1.7 billion US gallons) of interstitial water.[4] The slurry of tailings and process water carried felled trees, mud and debris and "scoured away the banks" of Hazeltine Creek which flows out of Polley Lake and continued into the nearby Quesnel Lake. The spill caused Polley Lake to rise by 1.5 metres (4.9 ft).[5] Hazeltine Creek was transformed from a two-metre-wide (6.6 ft) stream to a 50-metre-across (160 ft) "wasteland"*[6] and Cariboo Creek was also affected.[2] As of 8 August 2014, a "slurry of toxic water and mud" continued to pour into Quesnel Lake.[6] By the end of the day the four-square-kilometre (1.5 sq mi) sized tailings pond was "virtually empty".[2][5] Mine safety experts and media articles have called the spill one of the biggest environmental disasters in modern Canadian history.[7][8] British Columbia’s government initially insisted the dam failure was not an environmental disaster but stated "We will have a much better idea 24 hours from now on the quality in Quesnel Lake," ,[9] a position clarified again by British Columbia’s Environment Minister, Mary Polak, in November 2014 after more sampling data became available.[10]

State of local emergency[edit]

On 6 August 2014 Cariboo Regional District declared a local state of emergency in several nearby communities, including Likely, British Columbia, partly because of concerns over the quality of drinking water, which affected 300 residents.[5] On August 9, water use restrictions were removed for residents of Likely and downstream from that community based on water quality testing by the British Columbia Government. However, the government continued the advisory for points upstream of Likely. On August 12, Interior Health further rescinded the ban on drinking water, narrowing the "Do Not Use" order to only the impact zone directly affected by the breach, which includes Polley Lake, Hazeltine Creek, and an area within 100 metres (330 ft) of the shoreline sediment deposit, where Hazeltine Creek runs into Quesnel Lake. This remaining advisory is expected to stay in place indefinitely. The government advised that boiling the water would not help in the "do not use" areas.[2][11][12] All five testing sites of the second water test run had zinc levels above chronic, or long-term, exposure limits for aquatic life.[11]

The government described the purpose of the state of local emergency was to provide "exceptional" powers in the interest of public safety, and an equitable distribution of potable water to the residents of Likely. All tourism businesses in the affected areas remained open. Because the affected water system is salmon-bearing, there was a temporary closure of part of the Chinook salmon fishery by Fisheries and Oceans Canada. Fishing along the Fraser River was not affected. Rainbow trout toxicity test results from water collected at Quesnel Lake near the mouth of Hazeltine Creek on August 5 and 6 showed water was not toxic to rainbow trout.[2][12]


Pollution Abatement Order[edit]

On August 6, two days after the breach, the British Columbia Ministry of Environment issued a Pollution Abatement Order to Mount Polley Mining Corporation. The company submitted an action plan for the Preliminary Environmental Impact Assessment, environmental monitoring, stopping the flow from the "Tailings Impoundment" breach, as required. The company was required and did report weekly on the implementation of action plan measures.[2]

Immediate control[edit]

In August MPMC submitted an interim erosion plan and a sediment control plan to mitigate ongoing erosion and sediment transport downstream, to control further flow from the tailings area, and to improve the quality of water flowing into Quesnel Lake.[13] In the beginning of September 2014, a berm to prevent further spread of tailings was nearing completion and laid off workers, about 40 of the mine’s approximately 300 workers demanded to reopen the mine. a spokesman at the Ministry of Mine said operations would require permits and approvals and could only go ahead after a rigorous review.[14]

Environmental monitoring and impacts[edit]

Effects of Mount Polley mine dam failure for the lead: the breach alone released 134 t of Pb to water : 92% of the total reported for all of Canada in 2014 from 1990 to 2004

According to an Imperial Metals summary filed with Environment Canada in 2013, "there was 326 tonnes of nickel, over 400 tonnes of arsenic, 177 tonnes of lead and 18,400 tonnes of copper and its compounds placed in the tailings pond [last year]".[5] At a community meeting on 5 August 2014, president of Imperial Metals, Brian Kynoch, claimed the water in the tailings pond was almost potable, "though the silt, the "ground-up rock" left over after extracting the metals" posed a problem.[5]

Water, sediment, and fish in Polley and Quesnel Lake are monitored by British Columbia government staff. Fish sampling revealed elevated levels of selenium that exceed guidelines for human consumption, as well as elevated levels of arsenic and copper not considered a threat to human health. These levels were similar to levels found in 2013 before the tailings breach and considered likely due to local geology.[15]

Sediment testing near the tailings spill revealed elevated concentrations of copper, iron, manganese, arsenic, silver, selenium and vanadium. The government said tests in May 2014, before the tailings release, had shown elevated levels of the same elements.[16]

The extent of the damage is predicted to "remain unknown for years or even decades", as toxicants slowly accumulate in the environment. It should be noted, however, that the geological nature of the tailings is such that the minerals present in the tailings will not readily dissolve into the waters affected, as the pH of the waters is not low enough to promote dissolution of the minerals and therefore would lessen their bio-availability.[9]

Engineering monitoring and inspection[edit]

In 2010, Mount Polley Mining Corporation's (MPMC) engineering firm reported a 10-metre (33 ft) crack in the earthen dam while working to raise it, and that piezometers were broken, which per MPMC were later fixed.[17]

In 2010, then-premier Gordon Campbell had cut funding for seven ministries responsible for resource management, which were reorganized into a "single team" approach. Inspections across the province decreased from twenty-two in 2009 to three in 2010, two in 2011, and none in 2012. Mount Polley was last inspected in 2013, but not 2011 or 2012. Bill Bennett, Minister of Energy and Mines, said "there is no evidence that the government’s missed inspections were related to the failure of the dam this year".[17] In 2018, the Association of Professional Engineers and Geoscientists of British Columbia charged the responsible engineers with negligence or unprofessional conduct.[18]

Investigation of root cause[edit]

On 18 August, the British Columbia government, with support of the Soda Creek Indian Band and Williams Lake Indian Band, ordered an independent engineering investigation into the pond breach and a third-party review of all 2014 dam safety inspections for every permitted mine's tailings pond in the province. The panel reviewing this breach was composed of Norbert Morgenstern, P.Eng., Dirk van Zyl, P.Eng., and Steven Vick. Their final report was published 31 January 2015.[13] The investigation covered many factors, including the question of whether the piezometers measuring the water pressure on the dam had been located correctly. The last readings, 2 August 2014, did not show any changes in the water pressure.[2] On 1 February 2015, the Globe and Mail reported that a principal finding of the panel determined that the tailings dam collapsed because of its construction on underlying earth containing a layer of glacial till, which had been unaccounted for by the company's original engineering contractor.[19]

Political responses[edit]

The University of Victoria Environmental Law Centre filed a complaint with B.C.’s privacy commissioner regarding the government not releasing environmental assessments and dam inspection reports about Mount Polley mine; after journalists found a dam inspection report from 2010 and environmental assessments from 1992 and 1997 in public libraries,[20] the B.C. government has withheld subsequent reports.[10] Indigenous political activists led by Kanahus Manuel set up blockades and held numerous community based protests against Imperial Metals following the disaster.[21]

The long-term water management plan for the Mount Polley mine site has been approved by an independent statutory-decision maker from the Ministry of Environment.

The long-term water management plan is expected to be fully in place by fall 2017 and will replace the short-term water management plan that has been in place since 30 November 2015.

Mount Polley Mining Corporation submitted its formal permit amendment application, which included the long-term water management plan and supporting Technical Assessment Report, in October 2016. The documents were subject to extensive public consultation, including First Nations and local communities. The application also underwent a full technical review from the Cariboo Mine Development Review Committee (CMDRC), which includes representatives from provincial and federal agencies, First Nations, local governments (City of Williams Lake and Cariboo Regional District), and the community of Likely.

U.S. concerns[edit]

Since the spill, Alaskan mine opponents, including environmentalists such as Trout Unlimited Alaska, aboriginal peoples, the fishing industry and politicians, point to several planned B.C. mining projects involving three major salmon-producing river systems that run downstream into Southeast Alaska. The large Red Chris gold and copper mine owned by Imperial Metals Corp is now in operation and located in the headwaters of the Iskut River, a major tributary of the Stikine River whose estuary is near Petersburg and Wrangell, Alaska.[10] The KSM project owned by Seabridge Gold Inc has been approved by B.C., awaits federal approval and is located near the Unuk River system supporting one of Southeast Alaska’s largest Chinook salmon population, and flows into Alaska, although its tailings facility would be located in the Nass River watershed emptying into the Pacific in B.C. A third mine is slated to reopen and expand in the Taku River near Juneau.[22]

Imperial Metals history[edit]

The controlling shareholder of Imperial Metals is billionaire N. Murray Edwards. He donated half a million dollars in campaign contributions to the B.C. Liberal party since 2005 and helped organize a $1-million fundraiser for B.C. Premier Christy Clark’s re-election.[23]

Imperial Metals & Power Ltd was incorporated in British Columbia in December 1959. Besides the Mount Polley open pit copper mine and gold mine, it owns the Red Chris copper/gold mine and has a 50% interest in the Huckleberry open pit copper mine and the Ruddock Creek zinc/lead project.[24]

See also[edit]



  1. ^ Jesse Allen and Adam Voiland (2014-08-15). "Dam breach at Mount Polley mine in British Columbia". NASA (Visible Earth). Retrieved 2014-09-11.
  2. ^ a b c d e f g "Mount Polley tailings pond situation update", Government of BC, Newsroom, 8 August 2014, retrieved 8 August 2014
  3. ^ Yaffe, Barbara (8 August 2014). "Alberta has reason to fret over B.C. tailings pond spill". Calgary Herald. Opinion. Retrieved 9 August 2014.
  4. ^ a b Wise Uranium, 2018. The Mount Polley tailings dam failure (Canada)
  5. ^ a b c d e CBC News (6 August 2014), "Mount Polley mine tailings spill: Imperial Metals could face $1M fine", CBC News, retrieved 8 August 2014
  6. ^ a b Birchwater, Sage (5 August 2014). "Likely residents fear the worst after Mount Polley Mine disaster". The Williams Lake Tribune. Black Press, Inc.
  7. ^ "Breach Of Tailings Pond Results In 'Largest Environmental Disaster In Modern Canadian History'". Australian Mine Safety Journal. 12 August 2014.
  8. ^ Peter Koven (16 August 2014). "Imperial Metals plans debenture issue in wake of dam breach". National Post, syndicated via Star-Phoenix.
  9. ^ a b Peter Moskowitz (13 August 2014). "Mount Polley mine spill: a hazard of Canada's industry-friendly attitude?". The Guardian. Guardian News and Media. Retrieved 26 November 2014.
  10. ^ a b c Joel Connelly (24 November 2014). "British Columbia mine breach 'a disaster' that will linger for years". Seattle pi. Hearst Seattle Media, LLC. Retrieved 23 December 2014. The scale of the initial disaster is tremendous: It is going to take a long time. This is the very, very beginnings of this,"
  11. ^ a b The Canadian Press (2014-08-09). "Water ban linked to Mount Polley mine tailings spill partially lifted". The Vancouver Sun. Retrieved 2014-08-10.
  12. ^ a b "Mt. Polley Mine incident". BC Government Newsroom. Retrieved 2014-08-16.
  13. ^ a b Imperial Metals. "Mount Polley Updates-Tailings Breach Information". Imperial Metals Corporation. Retrieved 2014-09-14.
  14. ^ Sunny Dhillon (7 September 2014). "Reopen Mount Polley mine, union says". The Globe and Mail. Retrieved 2014-09-14.
  15. ^ "Mount Polley spill: Testing finds elevated selenium in fish". CBC. 2014-08-22. Retrieved 2014-09-14.
  16. ^ Canadian Press (2014-08-29). "Mount Polley mine breach: Elevated levels of chemical elements near tailings pond". Vancouver Sun. Retrieved 2014-09-14.
  17. ^ a b Justine Hunter (14 October 2014). "B.C. didn't inspect Mount Polley mine in 2010, 2011". The Globe and Mail. The Globe and Mail Inc. Retrieved 23 December 2014.
  18. ^ CP (26 September 2018). "Three engineers to face disciplinary hearings in Mount Polley dam collapse". Vancouver Sun. Retrieved 27 September 2018.
  19. ^ "Globe and Mail, "Mount Polley Spill taints Alaska-B.C. mine relations"".
  20. ^ Gordon Hoekstra (October 8, 2014). "Victoria breaking the law by not releasing mine reports: UVic law centre". Vancouver Sun. Postmedia Network Inc. Retrieved 23 December 2014.
  21. ^ Kresnyak, Danny (April 29, 2015). "First Nation group launches protest to halt re-opening of Mount Polley mine". Vancouver Observer. Retrieved July 15, 2016.
  22. ^ James Keller (21 August 2014). "'Lack of confidence' in B.C. from Alaskan fishing industry since Mount Polley breach". Globe and Mail. The Canadian Press. Retrieved 23 December 2014.
  23. ^ Kelly Sinoski (12 August 2014). "Major Imperial Metals shareholder held private fundraiser for Clark's re-election bid". Vancouver Sun. Postmedia Network Inc. Retrieved 26 November 2014.
  24. ^ "Our Company", Imperial Metals, Imperial Metals Inc, 2013, retrieved 8 August 2014

External links[edit]