State of Practice for Tailings Management Workshop at CIM 2015 Montreal, Mount Polley Failure

State of Practice for Tailings Management Workshop at CIM 2015 Montreal, Mount Polley Failure

State of Practice for Tailings Management Workshop at CIM 2015 Montreal, Mount Polley Failure summarizes part of the conversations and presentations which took place, as Riskope interprets them.

Tailings Pond

The Tailings Management Workshop started with a Panel, Ministry, Legal and CIM, CAD positions’ review, in particular with respect to the tailings dam accident occurred on Aug. 4th, 2014, at Mount Polley, B.C., Canada.
Incidentally, we reported immediately after the accident in this blog, giving “world-wide” rates of MAJOR failures we had developed in a paper published in 2012.

Mount Polley causes of failure

The causes of failure (simplified to the extreme for the sake of this post) were a shear failure of the dam foundation compounded to high water levels in the impoundment.
Geotechnical investigations missed a weak layer and misunderstood the potential for strength loss of that layer under un-drained conditions.
Failure was rapid and without precursors leaving the alert by a deformation monitoring system useless, should there had been one.

The Panel was given the mandate to define a path to zero failures, obviously a “political statement” more than a technical one, as we have already discussed in various prior blogposts here, here and here.

Given the “unalterable wording” of the mandate the Panel had to carefully formulate their conclusions.

Questions

However, during the discussion several questions came up dealing with:

• The little space given to management in the panel conclusions—due to time and scope limitation, following the replies given.
• How to prevent investigations to “miss” critical geotechnical/geological features? Factors of safety to be too aggressively selected? This will remain the responsibility of the proponents/owners following the replies given. CDA is responding to the Mount Polley failure by strengthening a number of statements and definitions (also on factor of safety, a point we have raised in a recent paper, when looking to the long term fate of dams. They recognize however that flexibility has to remain and that “one definition fits all” does not work.

• How to stop misrepresenting reality to the public. The question was bearing on the wording of the mandate itself. “Path to zero failure” is certainly giving to the public the illusion that the goal is reachable, whereas it is not. No industry in this world has ever reached such a goal. Very regulated industries, like commercial aviation are carefully formulating finite goals recognizing this.

  • FAA for example has the following goal. Reduce the commercial air carrier fatalities per 100 million persons on board by 24 percent over 9-year period (2010-2018). No more than 6.2 in 2018. NB: that’s 6.2*10^-8, a value at least two orders of magnitude below the credibility threshold (10^-5 to 10^-6) many industries accept.

  • A reply stated that there is a hiatus between “risk management” and “safety” approaches. The reason was that Safety Management strives for “zero fatalities”. In a private discussion afterwards I stressed the fact that the “zero fatalities” is certainly a honorable goal. It is however a simplification of a complex reality which works well as a slogan. It keeps key personnel accountable and alert, but is certainly not a scientifically acceptable statement.

• We heard again participants using the term risk as synonymous to a number of other technical words, we at Riskope stress again the need for a proper glossary that specialists should use to avoid misunderstandings.

• There was a specific request for clarity on defining tolerance to risk and enhancing understanding of complex consequences. It is obvious that this question cannot find a reply as long as common practice PIGs risk matrix and other fallacious methodologies will be used in the mining (and other) industries, as pointed out in one of our 2012 paper.

At Riskope we have devoted our efforts to these themes in the last decades. Specific replies, methods exist. Contact us.

Tagged with: CIM 2015, Mount Polley Failure, path to zero failures, State of Practice, Tailings Management

Category: Consequences, Mitigations, Risk analysis, Risk management, Tolerance/Acceptability

One response to “State of Practice for Tailings Management Workshop at CIM 2015 Montreal, Mount Polley Failure”

1. Alistair Kent says:

   May 20, 2015 at 9:03 pm

   Thanks for this brief summary of the CIM workshop. Familiar issues re-occur. I hope that there will be further more extensive reporting on the CIM – perhaps a CIM article by yourselves and other like Rick Siwick and Harvey McLeod.
   Best regards

   Reply