Tailings Contaminate Lake

[C&J]

The dam was built on unstable ground. One would expect that engineers be required to check that the ground they are building on is suitable for the purpose. And that the Ministry make sure, when the plans are submitted for approval, that engineers are doing that kind of checking.

I don't know what the current rules are, but if such checking of ground suitability is not a requirement then it ought to be. So if such a requirement is missing from current legislation, that would definitely suggest inadequate oversight on the part of the Government, and poor standards of practise on the part of the engineers. Both of which need to be rectified.

I agree, this is one of the areas that definitely came up as lacking. The investigation stated that there was not enough drilling in the failure area, or that the engineers did not understand how the material behaved.

However, that said, there was a lot more to the dam failure than just the fact that it was built on unsuitable ground. The independent investigation found other things that contributed to what happened, mainly the fact that the dam had been raised several times in an incorrect manner (the slope was too steep). I believe their wording was something to the effect that while the unstable ground "loaded the gun" it was the overly steep slope that "pulled the trigger".

That was the wording they used, but the slope used was approved by the government and the engineer of record. There was no mention that they were not following the approved design construction.

The investigation also found that there were other factors that, while not contributing to this particular failure, likely would have contributed to some sort of failure in the future had they continued unabated.

Right, due to not understanding the initial design requirements. Not due to construction or management practices.

The following quote is from an article in the Vancouver Sun that outlines what the investigative panel had to say on the subject (my bold):

The root cause was an undetected flaw under the section that breached. But overly steep slopes on the embankment, neglected beaches, inadequate safety margins, ad hoc planning, and the hefty volume of water behind the dam all contributed to making the failure much worse than it needed to be.

“The panel was disconcerted to find that, while the Mount Polley tailings dam failed because of an undetected weakness in the foundation, it could have failed by over-topping, which it almost did in May 2014. Or it could have failed by internal erosion, for which some evidence was discovered.

“Clearly, multiple failure modes were in progress, and they differed mainly in how far they had progressed down their respective failure pathways.”

Mount Polley was not a story of one flaw that went undetected for years with nothing to be done about it. Rather, it was characterized by a pattern of dubious behaviour, margins of safety that skirted the edge of the cliff, little thought of worst-case scenarios, all factors in a disaster waiting to happen.

If you'd like to read the entire article, here's the link:
http://www.vancouversun.com/opinion/col ... story.html

That Vancouver Sun article definitely embellished some of the findings. The dam didn't almost fail by overtopping or erosion, the previous cracking had nothing to do with this failure. There was no multiple failure modes occuring. It was mentioned multiple times that there was no warning of this failure occuring, there was no monitoring that could have been done to predict it. The margin of safety was not skirting the edge of the cliff.

If you'd like to view the actual investigative report presentation that article was written on, here's the link:
https://www.mountpolleyreviewpanel.ca/final-report

The investigative panel clearly made an effort not to assign blame to anyone, that is for the next investigations. I am sure they will find all parties to be responsible in some form. The thing to take away is that it could easily be found that management was following what they believed was proper practice, ie, not being deliberately negligent.

The thing that interests me most is why were there all the different engineering firms involved? Who was the push on the change?

[C&J]

That Vancouver Sun article definitely embellished some of the findings. The dam didn't almost fail by overtopping or erosion, the previous cracking had nothing to do with this failure. There was no multiple failure modes occuring. It was mentioned multiple times that there was no warning of this failure occuring, there was no monitoring that could have been done to predict it. The margin of safety was not skirting the edge of the cliff.

If you'd like to view the actual investigative report presentation that article was written on, here's the link:
https://www.mountpolleyreviewpanel.ca/final-report

The investigative panel clearly made an effort not to assign blame to anyone, that is for the next investigations. I am sure they will find all parties to be responsible in some form. The thing to take away is that it could easily be found that management was following what they believed was proper practice, ie, not being deliberately negligent.

The thing that interests me most is why were there all the different engineering firms involved? Who was the push on the change?

Quoting myself:

Just read through some more of the actual report, and it does appear some of the construction practices were quite questionable. These weren't touched on as much in the presentation.

It does mention the overtopping, but also states that it was not a cause of the failure, more an indication of the operation of the tailings facility, same with the marginal safety factors.

[Merry]

The evidence is not all in yet to determine whether or not what was actually happening was what had been approved. That is what the current two investigations are trying to determine. The mandate of the first investigation was only to determine what actually happened to that dam, not to assign blame. The following is a direct quote from it's Terms of Reference

The panel shall perform its duties without expressing any conclusions or recommendations regarding the potential civil or criminal liability of any person or organization

The investigation also found that there were other factors that, while not contributing to this particular failure, likely would have contributed to some sort of failure in the future had they continued unabated.

Not due to construction or management practices.

Not so, the following is another direct quote from the report (my bold)

The specifics of the failure were triggered by the construction of the downstream rockfill zone at a steep slope of 1.3 horizontal to 1.0 vertical. Had the downstream slope in recent years been flattened to 2.0 horizontal to 1.0 vertical, as proposed in the original design, failure would have been avoided. The slope was on the way to being flattened to meet its ultimate design criteria at the time of the incident.

The changes referred to in the last sentence were made following a directive from the Ministry, who had observed what was happening regarding the slope and ordered the correction. Unfortunately it was too little, too late.
The following quote is also taken from the report (my bold)

attention was turning to longer-term prospects for continued dam raising, and the outlook was not good.BGC made explicit the connection between the structural limitations of the dam and the ever-growing volumes of surplus water it was being called upon to contain.In a June 18, 2013 memorandum, it stated:
A continuous beach along the complete upstream length of the dam is the design requirement necessary for dam stability and needs to be achieved moving forward regardless of the final targeted crest elevation. The current water pond surplus does not allow for the development/maintenance of above-water beaches.
It elaborated on this topic a month later, on July 25, 2013:
An above-water tailings beach separating the till core from the reclaim water pond constitutes a fundamental design element of the dam. Without a wide above-water beach, the MPMC tailings dam is effectively being operated as a water-retaining dam, with the water pond effectively in direct contact with the till core, separated by only a narrow zone of tailings or waste rock.

As I stated in an earlier post, I know for a fact that as little as a week before the breach there was no "beach" on that dam and that the water level was virtually to the top. If that's not poor management, given all the previous warnings outlined in this report, then I don't know what is.

[erinmore3775]

You are absolutely correct, Merry! It is the textbook example of poor management not only at the onsite level but at the company executive level as well. It demonstrates a clear disregard of the engineer's recommendations, worker safety, and respect for the environment. Proper mitigation (buttressing and beaching) probably would have prevented the failure. However, cost considerations prevented these mitigations from being put in place.

[Smurf]

It is nice to have someone who knows what they are talking about and is also interested enough to stay on top of this for the benefit of us all. Thank you Merry.

[Merry]

Thanks Smurf.

Let's hope those investigating do a good job so that incidents such as this one never happen again in Canada.

[Merry]

Amazingly, it appears they're getting ready to reopen Polley despite the fact all the investigations are not yet complete. Even though it's supposed to only be a temporary opening, I still think it's foolish to start up again prior to having ALL the relevant information regarding the dam failure.

The same management team is in place now that was in place then so, until we know for sure that human incompetence (negligence?) on the part of one or more of that team did not have a role to play, I think it's extremely unwise to allow the mine to re-open. But money talks, and it's costing the company a small fortune every single day that mine is down. So what's a few potential lives lost, or fishing habitat destroyed, when millions are at stake?

Energy and Mines minister Bill Bennett said he’s hopeful to have good news Friday regarding the temporary reopening of Mount Polley Mine.

“We are in a position now whether to accept the company’s application to restart for formal review,” Bennett told the Tribune Thursday. “If the application is accepted it will be referred out immediately to the Cariboo Region Mine Review Committee. There will be a final decision made Friday.”

The final decision rests with a statutory decision maker, however, Bennett said his staff has told him the company’s restart plan is high quality and looks promising.

If accepted the committee will begin to review the application on March 30, coinciding with a 30-day public consultation period that will conclude on April 29.

“You can see that we’re trying to keep a very expeditious time line,” Bennett said, however, he warned even with intensive resources being applied by government, permits wouldn’t be granted until early June.

Bennett praised MLA Donna Barnett and Minister Coralee Oakes for their daily push to have the mine start up again.

Two reports on the Aug. 4, 2014 tailings impoundment breach are still pending, including one from the Chief Inspector of Mines and rgw Conservation Officer Service.

In the meantime, government is acting on the recommendations made by the Independent Investigation Panel in its report released in January.

“We can’t just do business as usual. Our obligation is to learn from what happened and to learn from the report,” Bennet said.

A reopening would be for more than six months but less than a year. Details will be shared if the application is accepted.
Mount Polley will host a community meeting in Likely on Wednesday, April 1, from 7 to 9 p.m.

http://www.wltribune.com/news/297722191.html

[Merry]

Here's the follow up to the news story I posted above:

The application for re-start of the Mount Polley Mine has been received and reviewed and will now be referred to the mine development review committee which will have its first meeting on Tuesday, March 31, a Ministry of Energy and Mines spokesperson confirmed Friday afternoon.

The first community meeting about the restart plan will be held in Likely on Wednesday, April 1, at the Likely Community Hall from 7 to 9 p.m.

Imperial Metals will host the meeting and ministry officials will attend.

The schedule for future community meetings is being worked out and details will be shared when available, the ministry said, adding the company's application documents will be posted online to the Ministry of Energy web site soon.

A 30-day public consultation period will occur through the month of April.

http://www.wltribune.com/news/297843341.html

[Merry]

Interesting article written by someone who recently visited the site of the spill:

On Easter Sunday, April 5, I traveled with a scientist and an engineer from Vancouver to Likely, BC, the site of the infamous Mount Polley tailings breach. The three of us shot photos, took samples and pulled each other out of tailings quicksand as we hiked seven treacherous kilometres from Quesnel Lake up the completely destroyed Hazeltine Creek to the site of the dam failure.

Eight months have passed since one of the worst mining disasters in Canadian history. Despite an ongoing RCMP investigation and a complete lack of clean-up, the BC Ministry of Energy, Mines and Natural Gas has agreed to review an application from Imperial Metals, the company responsible, to reopen the Mount Polley gold and copper mine as early as June.

The month-long review began on April 1, meaning that it will be completed before the results of the investigation have been released. That investigation, which led to a raid at Imperial Metals’ Vancouver office in February, could yield criminal charges.

Allowing a review to go forward before the investigation has been completed does raise a question. Do government and industry view disasters like the one at Mount Polley as an acceptable cost of doing business?

I spoke with Larry Chambers, a former employee of the mine who believes he was fired for raising safety concerns.
“When I worked at Mount Polley I phoned the ministry of mines and told them that the dam was pushed out. A lot of the employees working there knew the dam was going to give out,” said Chambers. “I told them they’ve gotta do something about this. It’s going to breach. It’s a disaster waiting to happen. It all fell on deaf ears.”

The disaster took place on unceded Secwepemc First Nations territory, home to Kanahus Manuel of the Secwepemc Women Warrior Society, a group opposed to all development that threatens water in their territory.

“The province has no jurisdiction to be making these decisions on our homeland,” Kanahus argued. “What happens here at Mount Polley and how government and industry deal with this disaster is going to set a precedent on how they deal with other disasters and spills in the future, whether from mining or pipelines. This is what they think about us. This is what they think about our water and our land.”

Secwepemc territory is also home to a vast stretch of the proposed Kinder Morgan tar sands pipeline, as well as the Ruddock Creek mine, proposed by Imperial Metals and currently undergoing an environmental assessment.

Given the extent of resource extraction proposed on contested lands, whatever happens next may well set the tone for the future of an industry that Canada dominates worldwide.

https://ricochet.media/en/396/photos-co ... eopen-mine

[Merry]

In view of the fact that the Province is considering allowing Mount Polley to resume operations, I think it's important that we get a refresher on the type of negligence that allowed the dam to burst, and to remember that all the same players are still managing that mine.

The following article was written in Feb, but it's contents are still very relevant today (maybe more so). The bold highlighting is mine.

The ill-fated tailings dam at Imperial Metals’ Mount Polley mine was an improvised work in progress, built higher every year to hold back the growing volumes of water behind it.

“For years, dam raising had managed to stay one step ahead of the rising water,” wrote a trio of engineering experts in a report on the dam breach released Friday. “But on May 24, 2014, the water caught up.”

The spur was a heavy run-off from an abnormally high winter snow pack, followed by torrential rains. With the rising waters in the tailings pond threatening to over-top the dam itself, the mine operator put out a call on the 25th to AMEC, its engineering firm of record.

After arriving on the scene the following day, geotechnical engineer Dmitri Ostritchenko found plenty of cause for concern: wet spots on the embankment, seepage here and there, and a pond almost level with the core of the dam.

Two days later he reported by email to the company’s senior geotechnical engineer, Andrew Witte, that the situation had not much improved. “At the end of the day, the freeboard level is basically zero,” wrote the on-site engineer, referring to the gap between the water level and the crest of the dam.

Despite some effort to reduce the amount of water behind the dam, tailings were still being added to the pond because the mine was continuing to operate. “Basically there has not been much (de-watering),” he wrote, “as they are still focused on making sure the mine can operate.”

This was too much for Witte. The safe operating standard was nine tenths of a metre of freeboard at bare minimum. Mining operations had to take a back seat until that was restored. He directed Ostritchenko to remind the company of its obligations.

“Under this type of scenario they are supposed to stop discharging tailings and focus on de-watering to get 0.9 metre of freeboard again,” wrote the senior engineer. “If they are not removing water, they are in direct contravention of (what the province) expects.

“That is a dangerous game to play and we need to make sure that our *bleep* is covered by telling them to pump water out of the tailings storage facility. We cannot support the ‘just keep operating in the danger zone attitude.’ Remember, if they lose the dam, the mine can’t operate anyways.”

They didn’t lose the dam — not then, anyway. That wouldn’t happen for another 10 weeks.

Instead, the rising water, the precarious state of the dam, and the urgings of the engineering firm galvanized the mine operator into action. The embankment was topped up, the water drained, and the situation stabilized by the end of May.

Still, it was a near-run thing. A near “over-topping failure” and “potential breach” of the dam, according to the report from the trio of experts.

They also highlighted factors that contributed to the near-miss. The climate model for the dam neglected to consider a worst-case weather scenario. “They did not account for specific wet year conditions.”

The amount of water stored in the tailings pond had increased 10-fold to 10 million cubic metres in just four years. Yet the company had only just obtained a permit for a treatment plant that would allow the release of three million cubic metres of water a year. “It is not clear to the panel why it took so long.”

Another area of concern was the failure to maintain a separating barrier of tailings — known as a “beach” — to prevent erosion of the earthen embankment from the rising water behind it.

Critically important because the structure was not designed as a water-retaining dam, though increasingly that is what it was doing. The report is replete with references to “chronic problems with maintaining the tailings beach.”

Key documents related to the concerns about the beach, and others connected to the near-over-topping of the embankment, were among the dozens excluded from the public record when the report was released Friday.

The exclusions were made at the request of the two continuing investigations into the dam failure, one by the provincial inspector of mines, the other by provincial conservation officers. Each may result in recommendations for charges.

Even with the exclusions, the engineering panel had plenty to say about the sorry state of affairs that preceded the dam failure last August.

The root cause was an undetected flaw under the section that breached. But overly steep slopes on the embankment, neglected beaches, inadequate safety margins, ad hoc planning, and the hefty volume of water behind the dam all contributed to making the failure much worse than it needed to be.

“The panel was disconcerted to find that, while the Mount Polley tailings dam failed because of an undetected weakness in the foundation, it could have failed by over-topping, which it almost did in May 2014. Or it could have failed by internal erosion, for which some evidence was discovered.

“Clearly, multiple failure modes were in progress, and they differed mainly in how far they had progressed down their respective failure pathways.”

Mount Polley was not a story of one flaw that went undetected for years with nothing to be done about it. Rather, it was characterized by a pattern of dubious behaviour, margins of safety that skirted the edge of the cliff, little thought of worst-case scenarios, all factors in a disaster waiting to happen.

http://www.vancouversun.com/opinion/col ... story.html

Please note the part I highlighted in red, because I personally know of at least one eye witness report that there was absolutely NO beach as little as one week to the day before that dam burst.

[maryjane48]

like i called it back few pages , sadly no one will be held to account and its on christies watch

[Merry]

Protests against efforts to reopen the British Columbia mine at the centre of an environmental disaster have been staged at the Toronto Stock Exchange, government offices and in at least two U.S. cities.

A national day of action by the B.C.-based Secwepemc Women Warriors Society was launched in protest over the potential reopening of the Mount Polley gold and copper mine in the province's Cariboo region.

Society spokeswoman Kanahus Manuel says the warriors have been monitoring the impacts at the mine disaster site and oppose attempts to re-start the Williams Lake-area operation.

The tailings pond at the Imperial Metals Corp. open-pit mine burst without warning last August, spilling 24 million cubic metres of silt and water into nearby lakes and rivers.

An independent, government-ordered report determined the spill was caused by a poorly designed dam that didn’t account for drainage and erosion failures associated with glacial till beneath the pond.

A public permit application process to reopen the mine is underway and a decision is expected in June.

http://www.castanet.net/edition/news-st ... htm#138762

[Merry]

Turns out the spill wasn't totally benign as the mine operators claim:

Months after a dam at Mount Polley mine collapsed, releasing more than 25 million cubic metres of tailings and water, a polluted plume of sediments continued to circulate through Quesnel Lake.

Now a study by researchers from two universities and the federal Department of Fisheries and Oceans is raising concerns about the long-term impact of that plume, which is still exposing fish, plants and insects to copper, selenium and other metals.

Ellen Petticrew, a University of Northern British Columbia geology professor, said a study that took place over the two months immediately after the spill found that although the sediment sank in the lake, it created a layer that could be stirred back to the surface by wind and wave action.

Long after the initial spill, the plume was observed at times pulsing out into the Quesnel River.

“Because of the shape of the lake, the long skinny arms oriented in an east-west direction, when a strong wind blows, it can pile up water at one end of the lake and generate what’s called a seiche, or rocking movement,” said Dr. Petticrew. “And if you think about your layer cake if you push down on one end then the cold water comes up at the other end and it rocks back and forth … [until] the cold turbid water with the mine particles in it gets pushed out and empties into Quesnel River.”
Dr. Petticrew said it’s not yet clear how the pollutants in the plume are affecting fish in the lake or river and it might take years of study to determine that.

She said sediment was stirred up last fall during a seasonal event known as lake turnover. Data haven’t been collected yet on this spring’s turnover.

“We know some of the sediment settled over winter. … We just don’t know how much of it will stay on the bottom and how much will get into the water column,” she said. “So the concern for the future is that these particles have higher copper levels than the ambient water column, and we’re concerned about the effect this can have on the biota and how well the lake can handle this load of contaminants. It’s a big lake; it’s a deep lake, but it’s a lot of material to be dumped into it.”

You can read the rest of the article here:
http://www.theglobeandmail.com/news/bri ... e24272988/

[Smurf]

Thanks for keeping us up on this. I for one don't follow it that close but am interested. It truly doesn't surprise me that there could be after effects from a huge spill like this. It will/would be interesting to know exactly what the delegation from Alaska will be told.

[Donald G]

To Merry ...

As I have said a number of times it is because of posts like yours that any number of people have been able to follow a rather complex situation and subsequent investigation. You have done a lot to keep the focus on what happened and what now? Castanet should be paying you the rate of a top investigative reporter, which is the role you are admirably performing.

Your efforts are greatly appreciated.