Part One: BC Mine Dam Failure Shows Why Pebble is a Disaster in Waiting

Written by: Zach Cockrum

The level of devastation from breach of the Mount Polley gold and copper mine tailings pond is staggering.
Photo courtesy of Cariboo Regional District Emergency Operations Centre

[Editor’s note: This is the first in a three-part series running on the Trout Unlimited blog. Coming next, why the Mount Polley disaster could repeated in the transboundary region of British Columbia and Southeast Alaska.]

One of the most frequent claims of promoters of the proposed Pebble Mine at the headwaters of Bristol Bay, Alaska, is that modern technology means the failures of “tailings ponds” is highly unlikely.  However, just this week, an earthen dam at the Mt. Polley Copper mine in British Columbia, Canada, failed, releasing an estimated 1.3 billion gallons of contaminated tailings into the Fraser River watershed, known for its abundance of sockeye salmon.  What we’ve seen this week is exactly why TU is supporting the Environmental Protection Agency (EPA) effort to limit mining activities in Bristol Bay.

When open-pit copper mines are created, the percentage of the deposit which contains the actual mineral is very low. In order to extract valuable minerals, chemicals are applied to large volumes of crushed rock.  The result is far more toxic “tailings”, than extracted minerals.  In the case of Pebble Mine, extraction could generate more than 10 billion tons of waste rock that would be contained by a 740-foot tall tailings dam similar to the one that failed at Mt. Polley.  While Mt. Polley’s tailings amounted to 20,000 tons per day, Pebble’s are estimated to be 200,000 tons per day.

When the EPA assessed the potential impacts of large scale mining in the area, the Pebble Limited Partnership, which owns the claim to the Pebble deposit, hired an engineering firm to critique the EPA’s findings.  The consultants said [PDF], “Modern dam design technologies are based on proven scientific/engineering principles and there is no basis for asserting that they will not stand the test of time.”

There’s just one problem: the consulting firm PLP hired, Knight Piesold Limited, engineered the tailing dam at Mt. Polley.  Worse yet, PLP also hired them to design their tailings dam at the Pebble deposit.  You read that right.  The same company that PLP hired to criticize the EPA’s assessment, who argued there is no reason to believe these dams will fail, engineered a dam that failed, and is on the hook for building a similar structure at the headwaters of one of the best salmon fisheries in the world.  

The impact in the Fraser watershed has been disastrous.  Waters are off limits to swimming, and drinking. Dr. Peter Ross of the Vancouver Aquarium says the failure means, “sudden, lethal injury to fish and their feed”.  Over the long run, sediment loads will bury salmon spawning sites, and deposit toxic chemicals into the streambed.  That’s a serious problem for the estimated 1.5 million sockeye salmon which return to waters near the mine every year.  You can see a short video of the damage below:

The unfortunate events in British Columbia demonstrate exactly what TU has been saying for years – the Pebble Mine is the wrong mine in the wrong place.  An average of 40 million salmon return to the Bristol Bay every year to spawn.  A similar failure at Pebble could threaten these fish, and the 14,000 jobs and $1.5 billion in economic activity generated by commercial salmon fishing in the region.  Please add your voice today to stand up for these fish, and support the EPA’s effort to protect Bristol Bay.

4 thoughts on “Part One: BC Mine Dam Failure Shows Why Pebble is a Disaster in Waiting”

  1. Pingback: Part II: BC Mine Disaster Proves Need for More Review of New Mines | Orvis News
  2. Pingback: Part Three: Mount Polley Disaster Can Repeat Itself If We Don't Learn Its Lessons | Orvis News
  3. Pingback: Video: Xboundary, from Salmon Beyond Borders | Orvis News
  4. Thank you for this page I’m putting it in a letter to the editor in our fight against Pebble. Thank you for all the links too. Here’s a rough draft of my letter, if you have any suggestions I’m interested. Hope you will leave this on youtube so people in Alaska can view it. Love that you partner with Xbountary from Salmon Beyound

    The more research I do the more fearful I am about the Pebble mine and BC’s Transboundary border mines. I’m just hopeful that we can take to heart what our Canadian neighbors are also going through from the Mount Polly disaster.
    Please watch this short documentary Xbountary on YouTube. The toxic slurry that you see in this flim surged into Quesnel Lake, one of Canada’s deepest lakes. This slurry still lays at the bottom of this lake and Polly Lake too. Because the BC government and Imperial Metals were afraid they would make a bigger mess by trying to clean it up they left it there. This alone ought to be enough scientific proof as to the scale of irreversible damages these breaches can cause.
    Since that decision was made by them, an underground and underwater discharge pipeline was ran to Quesnel Lake from Mt. Polly’s tailing dam. Concerned Citizens of Quesnel Lake organized out of fear about if the mines waste waters were even being treated before being discharged into their lake, which is also a part of the Fraser River Watershed. Here’s their website In May of 2019 the Mount Polly Mine closed again citing financial concerns with market prices for their metals.
    The history of Imperial Metals and BC’s environmental policies are extremely shoddy at best in protecting those around them. Just one year after the breach in 2015 Mount Polly mine resumed operations. In this same year, Imperial Metals was also allowed to open and operate another larger open pit mine named Red Chris mine. This one sets at the headwaters of Alaska’s transbountary borders in the Stikine watershed. I’m assuming they used the some engineering firm for their tailing dam design at this mine.
    When you watch Xbountary, from Salmon Beyond Borders be sure to click on Mount Polly mine disaster for a story that left me wondering why in the world they would even think about hiring this firm? Orvis News: BC mine dam failure shows why Pebble is a disaster in waiting. Written by: Zach Cockrum August 11, 2014. After you read the story go back to second paragraph and click on 20,000 tons. Skytruth: Satellite detects massive spill at Canadian gold mine. Written by: David Manthos. The film at the end of this article gives you a bird’s eye view over half an hour long, of this toxic slurry flowing into the Quesnel Lake.
    Governor Dunleavy you should be asking President Trump to help protect our borders from transbountary mines in the southeast not encouraging more mines especially in the headwaters of Bristol Bay. These mines are dirty, toxic and irreversibly destructive and the tailings are there forever cooking up a witches brew, weather there in dam impoundment or a lake.
    It’s a very delicate balance when it comes to our salmon and open pit mining in and around their habitat. It’s not worth putting a renewable resource at risk for one that is not and for one that will forever change the landscape of our mountains and the purity and flow of its streams?

    Vicki Duggin


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