UNEP Tailings Dams report and residual risk assessment

UNEP Tailings Dams report and residual risk assessment discusses the joint UNEP-GRID Arendal assessment entitled “Mine Tailings Storage: Safety Is No Accident” from a risk assessment point of view.

The United Nations Environment Programme (UNEP) released the report in October 2017 in Geneva. The report urges States and the industry to “end deadly and damaging mining waste spills by enforcing a zero-failure objective”.

We believe that this objective requires some additional definitions and details. That is to make it truly helpful to society, industry and the environment.

Frequency and consequences of Tailings dams failures

The report comes in the wake of 40 mining waste failures over the last decade. Those include eight significant spills since 2014 alone. First of all, let’s note that 40 Tailings Dams failures in ten years is not big news. It is a sort of long term average the industry and society have seen for many decades (actually a century). It lead public to gradual higher awareness.

Those failures have reportedly killed at least 341 people, but possibly more than 1000 since 2008. Including the Samarco Fundao and Mount Polley, breaches damaged hundreds of kilometers of waterways. They affected drinking water sources and jeopardized the livelihoods of many communities around the world. Here, again, no big news, this has been going on for many decades as we have shown since 2012 with our papers.

The statements above do not condone the failures. It ensures no one thinks we have reached “the end of the world”, like sensationalist media like to convey. Dams’ failures have always been triggered by the compounded effects of numerous causes, including negligence, errors and omissions, and excessive human arrogance.

What has changed most is the public perception and awareness surrounding these events, an evolution occurring for other nefarious events types as well.

You can read our quantification of likelihood of failure of tailings dam due to the causes referenced below, their consequences, and the risks compared to societal tolerance.

• Oboni, C., Oboni F., Factual and Foreseeable Reliability of Tailings Dams and Nuclear Reactors -a Societal Acceptability Perspective, Tailings and Mine Waste 2013, Banff, AB , November 6 to 9, 2013
• F., Oboni, C., Oboni, J., Caldwell, Risk assessment of the long-term performance of closed tailings, Tailings and Mine Waste 2014, Keystone, Colorado, USA, October 5-8, 2014
• J., Caldwell, F., Oboni, C., Oboni, Tailings Facility Failures in 2014 and an Update on Failure Statistics, Tailings and Mine Waste 2015, Vancouver, Canada, October 25-28
• Oboni, F., Oboni, C., A systemic look at tailings dams failure process, Tailings and Mine Waste 2016, Keystone, Colorado, USA, October 2-5, 2016
• Oboni, F., Oboni, C., Screening Level Risk Assessment for a Portfolio of Tailings Dams, Fall issue of Canadian Dam Association (CDA, ACB) Bulletin, Vol. 28 No. 4 Fall 2017.

Indeed we stated since 2012 that the mining industry is really far from the zero-failure objective that the United Nations Environment Programe states as a goal. Meanwhile we showed that a highly regulated industry, such as the nuclear, has, astonishingly, similar long term rates of very significant accidents.

UNEP report recommendations

The UNEP-GRID Arendal report, “Mine Tailings Storage: Safety Is No Accident” lists a couple overarching recommendation as follow:

Recommendation 1

The approach to tailings storage facilities must place safety first by making environmental and human safety a priority in management actions and on-the-ground operations. Regulators, industry and communities should adopt a shared zero-failure objective to tailings storage facilities where “safety attributes should be evaluated separately from economic considerations, and cost should not be the determining factor” (Mount Polley expert panel, 2015, p. 125).

Recommendation 2

Establish a UN Environment stakeholder forum to facilitate international strengthening of tailings dam regulation.

UNEP Tailings Dams report and residual risk assessment

Then the UNEP report asks mining companies to make environmental and human safety a priority in management actions and on-the-ground operations by requiring:

• detailed and ongoing evaluations of potential failure modes,
• residual risks
• and perpetual costs of waste storage facilities.

This set of recommendations is something any engineer or miner claims they do! The truth is unless you work quantitatively and assess the control and mitigation quantitatively you will not not properly evaluate risks. That is generally not done! Thus they cannot properly evaluate the residual risk of a tailings dam system.

Common practice risk matrix assessment methodologies are simply lacking the required objectivity and definition.

And the proof is in the pudding. Unless risk assessor and designers seriously change their approaches, things will continue to go as today without notable improvements.

Furthermore placing safety first is a vague objective as long as it is not quantified. Hazardous industries, nuclear power clearly define their safety objectives.

That’s particularly true when looking at the world-wide portfolio of dams, at highly variable stages of life-cycle development. To be on the path of “zero-failure” we have to consider possible “congenital problems”. Among those, for example, insufficient depth of geotechnical investigations, insufficient factors of safety, etc.

Those problems will continue to affect the world-wide portfolio for decades unless significant mitigations are implemented. Only rational risk assessment and the clear definition of a safety/success criteria allow to prioritize those mitigations and increase societal safety. Mitigative funds have to be allotted rationally and sensibly, and, above all, sustainably, in order to correct the mid and long term situation.

Additionally, we note there is no definition of what a residual risk assessment should entail (Mackenzie Valley Review Boards, Report of Environmental Assessment and Reasons for Decision, Giant Mine Remediation Project, Appendix D, June, 2013) and perpetual cost of waste storage facilities cannot be evaluated using the classic (common practice) NPV because of very well known drawbacks. Here too, solutions exist.

How to perform a residual risk assessment?

The very basic requirements are:

• First you need a baseline risk assessment. It should detail and update evaluations of potential failure modes during the system (and not only the dam’s) life cycle. Defining the system is a fundamental step which requires lots of attention.
• You also need to understand the multidimensional consequences and the system’s failure/success criteria.
• As stated in the Mine Tailings Storage: Safety Is No Accident A Rapid Response Assessment you need to  “Clarify responsibility for tailings dam performance.” which is a multi-parameter optimization problem. Indeed, oftentimes tailings dam’s failure means different things to different stakeholders. e.g. engineer or regulators. We discussed this type of performance criteria mis-communication in our Solomon island example.
• Finally, you need to have a risk register that quantitatively integrates the data with mitigation leading to calculate the residual risk.

All of the above can be performed with ORE, as it is quantitative, scalable, convergent and proven by over twenty years of deployments world-wide on mining and other instries systems.

Who has to perform residual risk assessment?

Mine Tailings Storage: Safety Is No Accident A Rapid Response Assessment also identifies a common practice that has to stop. The developer or design-engineers self-risk assessment has to stop as it is fraught by conflict of interest.

Independent risk assessor has to become the new norm. The report identifies this requirement in distinct ways. For example by stating: “Establish independent waste review boards to conduct and publish independent technical reviews prior to, during construction or modification, and throughout the lifespan of tailings storage facilities.”

This of course must include an independent risk assessment at every step.

The report then adds:

• “Ensure any project assessment or expansion publishes all externalized costs, with an independent life-of-mine sustainability cost-benefit analysis.” Including, of course the risks.
• “Require detailed and ongoing evaluations of potential failure modes, residual risks and perpetual management costs of tailings storage facilities.” and
• “Reduce risk of dam failure by providing independent expert oversight” done by independent risk assessor to maintain good and unbiased oversight. This will “Ensure best practice in tailings management, monitoring and rehabilitation”.

How often should you perform a residual risk assessment?

Ideally every-time the conditions change. It can range from weather patterns to managerial changes. Of course any addition/alteration to the tailings dam and overall system design should trigger an update.

We have experienced is that oftentimes situations change quickly. Any form of traditional (risk matrix) risk assessment update is too slow and lacks definition to identify anomalies. Thus, our solution is to deploy a automatic “real time” risk monitoring. It uses a blend of traditional monitoring and space observation techniques.

The ORE risk register will then swiftly be updated depending on the weather changes, water levels, wet spots etc. We call this particular ORE application “real time” because, in theory, updates could occur in real time.

Practice and rate of movements, evolution, etc. dictate the optimum updates frequency.

Closing remarks

UNEP Tailings Dams report and residual risk assessment goals will become a really useful document. That is, provided we insert a number of limit conditions and some additional methodological specifications.

1. Definition of minimum safety with respect to life and environment, considering the “congenital problems” structures and systems may present.
2. A clear glossary.
3. Methodological specifications, particularly in relation to what society expects from a risk assessment.
4. Monitoring methodologies, etc.

Tagged with: Analysis, assessment, development, management, operational, Risk Assessment, sustainability, Tailings Dams, tolerance

Category: Consequences, Hazard, Mitigations, Optimum Risk Estimates, Probabilities, Probability Impact Graphs, Risk analysis, Risk management, Tolerance/Acceptability