I am just copying some comments I recently made on the Mt Polley failure:
The causes of the Mt Polley failure were numerous, encompassing the entire lifecycle of the facility (site selection, design, construction, operation and maintenance). Jack Caldwell’s blog has lots of good info. There are numerous defenses to prevent failures: robust design, quality construction, 3rd party auditing, government oversight, emergency procedures, trained/competent staff, accident reporting, up-to-date operating manual, spillways, etc. When all these little mistakes aligned into the perfect storm failure occurs. It would have only taken one party doing a better job to prevent this – even including the local First Nations tribal band. They could have better judged the risks of impounding water in a net precipitation area within an earthen embankment designed for tailings – perhaps the engineer could not communicate the risk science in a relevant, understandable manner. I suspect much will come to light as to the failure of that decision-making during 2009-11 when the mine expanded, applied for discharge rights, and was denied. The time bomb kept ticking when there was an overtopping accident last year, yet no executive-level flags were raised. Much of this was foreseeable. I hope we can learn and improve. I think we will. Stats show we have improved. But dams and risks are growing bigger and the uncertainties of climate and the future increases severity of failure.
Risk = probability x consequence.
Tolerability and acceptability is a critical discussion, and poorly lacking in the public realm. Thanks for the comments Roy, Chris, Harvey, Franco and others. I agree with Roy we must separate risks imposed on society with those we personally subject ourselves to, and impose lower tolerance criteria for tailings dams. There will always be a grey area within ALARP (as low as reasonably possible) and I suspect 95% of failures occur within there, so it’s appropriate to demand a higher standard once again, at all previously mentioned places (management, operation, regulatory,etc). Failures and their severity will increase over time – in centuries or millenia all mine wastes fail and will pollute the environment, adversely affecting lives of future generations. Our contemporary management theories discount closure costs to almost nil, and don’t consider costs in the really long term, so these failures will continue to tarnish our industry and cause unduly harm. We should approach tailings with a longer view of future uncertainties, our best guess failure rate, and the predicted consequences.
Thank god this failure did not kill anyone or cause grossly unjustified harm to the local community. It’s very sad and troubling nonetheless.
My concern is how to make mine waste facilities more transparent. Cannot UAVs and satellites monitor operations quickly and cheaply? Isn’t the internet and mobile devices easy methods to share design/construction/operation data? Can’t we discuss mining risk tolerability in social media more to refine our boundaries? I think transparency and disclosure is a key first step to more robust risk management and accountability. And perhaps less discounting, and more dry stacked tailings too!