Tailings Dam Failures

According to a news report from Hetq, a news source from Armenia, there has been toxic tailings discharge from the Akhtala Mining Enrichment Combine tailings dam. The tailings are flowing freely into the nearby Akhtala River at least since mid-September. The author of the news article says that she visited the tailings dam twice in the past 2 months, and that on her 2nd visit, "the toxic sludge was flowing into the river at the same rate as during our first visit".

Take a look at the photograph in the article. What do you think about the location and slope of the tailings dam? What do you think may be the cause of this failure?

Here is a short piece from 2011 that I recently found.  Just another of those dreary articles on the terrible state of tailngs facilities in China.  My question: with the political system they have, is it possible for them to mine safely, net alone dispose of their waste safely?

Last year's Zijin tailings dam disaster in China was one of the most serious of its kind  - and appropriately recognised as such on MAC. See: Zijin Mining fined $1.4m for July gold mine spill

But it was far from being the only one.

Indeed, according to a recent government report, at the end of 2009 China had 12,523 tailings ponds, of which no less than 2,098 (16.8 percent) exhibited various safety problems.

It's only just over two years since the worst reported mine tailings dam disaster in history killed at least 277 people in Shanxi province.

Now, a Chinese tailings pond expert is calling on the government to "learn from foreign countries how to set up insurance systems for mining companies".

Then, "if a mining company goes bankrupt, the insurance company would provide coverage for potential pollution problems that could occur and result in liabilities and expenses for the mine owner".

Of course - to stand any chance of being effective - such a scheme should be mandatory. In any case it is intended to operate only after a potentially catastrophic event.

At least the posting of a stipulated financial bond by mining companies, designed to cover the "worst possible scenario", acts as a some deterrent to embarking on a calamitous project in the first place.

As global demand for rare earths appears to rise, so pressure is being applied on China to release supplies of these metallic elements, considered essential for computers and so-called "clean energy" technologies.  

Meanwhile - and whether or not it is designed to justify a squeeze on supplies  - the Chinese government is finally trying to impose environmental rules on its many rare earths' operations.

Tailings, and other mined wastes, from these operations are among the most hazardous dumped around the country.

Do you agree with the following list of things that the the International Finance Corporation (IFC) (2007), management of mine tailings and waste dumps include the following actions, and these are recommendations for what should appear in an EIA on the topics?  I find too much emphasis on seismicity---maybe all the IFC money goes to South America.  For the rest, I find this but a list of platitudes.  Let us have u opinions on the matter.

• Design, operation, and maintenance of structures according to internationally recognized standards based on a risk assessment strategy. Appropriate independent review should be undertaken at design and construction stages with ongoing monitoring of both the physical structure and water quality, during operation and decommissioning.
• Where structures are located in areas with a risk of high seismic loadings, the independent review should include a check on the maximum design earthquake assumptions and the stability of the structure to ensure that during seismic events there will be no uncontrolled release of tailings.
• Design of tailings storage and waste rock facilities should take into account the specific risks and hazards associated with geotechnical stability or hydraulic failure and the associated risks to downstream economic assets, ecosystems and human health and safety. Environmental considerations should thus also consider emergency preparedness and response planning and containment/mitigation measures in case of catastrophic release of tailings or supernatant waters.
• Any diversion drains, ditches and stream channels to divert water from surrounding catchment areas away from the tailings and waste rock structures should be built to the flood event recurrence interval standards. Usually, these diversions are designed for 100‐year runoff event but could vary by country.
• Design specifications should take into consideration the probable maximum flood event and the required freeboard to safely contain it (depending on site specific risks) across the planned life of the tailings dam, including its decommissioned phase.
• Where potential liquefaction risks exist, including risks associated with seismic behavior, the design specification should take into consideration the maximum design earthquake.
• On‐land disposal should be in a system that can isolate acid‐generating material from oxidation or percolating water, such as a tailings impoundment with dam and subsequent dewatering and capping. On‐land disposal alternatives should be designed, constructed and operated according to internationally recognized geotechnical safety standards.
• In addition, tailings impoundments and waste rock dumps should be constructed in a manner that minimizes the release of contaminants by including liners if seepage would result in groundwater or surface water contamination.
• Waste facilities should have adequate monitoring and seepage collection systems to detect and collect any contaminants released in the immediate vicinity.  This should include:
  • Consideration of seepage management and related stability analysis in design and operation of tailings storage facilities. This is likely to require a piezometer based monitoring system for seepage water levels within the structure wall and downstream of it, which should be maintained throughout its life cycle.
  • Consideration of zero discharge tailings facilities and completion of a full water balance and risk assessment for the mine process circuit including storage reservoirs and tailings dams.
  • Consideration of use of natural or synthetic liners to minimize risks.
  • Consideration of thickening or formation of paste to be backfilled into pits or underground workings during mine progression.
  • Utilization at decommissioned leach pads of a combination of surface management systems, seepage collection and active or passive treatment systems to ensure that post-closure water quality is maintained.

Mines and tailings dams should not fail.  But they do, regularly.  In spite of the application of ideas, intelligence, and aptitude.  One of the reasons for these failures, I suspect, is an inadquate assessment of the envorinmental impacts of the mine and its wase disposal facilities before implementation.  So my contentious thought for the day and for discussion:  why not a thorough review before mining as part of the enviornmental impact assessment.

To get you going, here is somehting I published elsewhere. 

The Environmental Law Alliance Worldwide  has a publication all prospective miners and mine investors should read.  The publication is free to download.  I have, and recommend you do so too.  The document is Guidebook for Evaluating Mining Project EIAs.  It is available in English, Spanish, and French.

Here is how they describe it:

Most countries require an environmental impact assessment (EIA) before giving the green light to a mining project. EIA processes provide a valuable opportunity for citizens to participate in decisions about mines. The problem is, project proponents often submit long, complex EIA documents that are incomprehensible to lay people.   We hope this Guidebook for Evaluating Mining Project EIAs will help grassroots advocates and communities understand mining EIAs, identify flaws in mining project plans, convince decision-makers to reject ill-conceived mining projects, and explore ways that proposed mining projects could be made socially and environmentally acceptable.   The Guidebook was produced in 2010 by a team of experts at the Environmental Law Alliance Worldwide (ELAW), including ELAW Board Chair Dr. Glenn Miller, Director of the Graduate Program in Environmental Sciences and Health at the University of Nevada at Reno.   ELAW has helped partners around the world evaluate dozens of EIAs for proposed mining projects. The Guidebook consolidates what we have learned and points to many critical resources for communities seeking to make their voices heard about proposed mining projects.

The group publishing this document, ELAW,  is headquartered in Oregon.  Their website is at this link.  Their blog is at this link.   They are a group of lawyers who take on environmental issues world-wide.

They appear to be active in mining too. Do not get too angry about all this.  They are probably innocent enough.  And their publication on evaluating mining EIAs is good stuff.  It starts out with a brief summary of mining; proceeds to a description of the impacts that mining may have; describes the EIA process; tells you how to review a mining EIA; and concludes by telling you how to be an effective participant in the EIA process.

For the most part the text and figures are good, the tone even, the perspective fair, and the advice sound.  If you are charged with preparing or reviewing a mining EIA or equivalent you could well benefit from reading this document.  Let me know how you succeed.

At this link is a pdf of a great PowerPoint presentation by Mike Gowan of Golder Associates.  He presents many photos of tailings facility failures.  One picture that I have never seen before is of a slimes dam that apparently flowed into underground mine workings.  I seem to recall that happened in Zambia many years ago.  If you know of htis incident please let us know more.  Apparently 120 people died, so it was pretty spectacular. 

I have elsewhere blogged about this presentation, so to make it easy for you here is my blog posting.  Enjoy.

Mike Gowan of Golder Associates in Australia has enabled me to post at this link a PowerPoint presentation of a talk he gave earlier this month in South Africa.  At the link is the PowerPoint in pdf format.  It is a big file and may take time to download, but persist, for the wait is worth the reward once you go through the presentation.

Mike was born and brought up on the Witwatersrand, and has lived and worked tailings ever since.  This presentation is at once intensely personal and of international significance.  Here for the first time, that I am aware of, is a great collection of photos and figures showing early mining and slimes dam practice in South Africa.  Here are pictures I have not seen before of the failure of slimes dams.  Here are snippets of stories of George Donaldson who pioneered tailings practice in South Africa.  (I got on the wrong side of him early in my career so have never written about him.)  Mike resuscitates his contributions.

The presentation consists of nearly 140 slides, so it is inevitable that Mike would take us on a world-wide, whirl-wind tours of the tailings facilities he is now working on.  Rock dam starter dikes subtended by upstream tailings in China.   Dealing with high rainfall in the Solomon Islands.   Compacted cyclone underflow in Chile. Diamonds in Botswana.   Concrete-face waste rock dams in Peru.  HDPE covers to limit evaporation in Oman.

Here are pictures and thoughts about filtered tailings, thickened tailings, paste for backfill, dust, commingling, and nearly all the multiple aspects of the science, engineering, and art of tailings management.  Mike is master of them all.

This is an extra-ordinary collection of photos and technical details.  Make sure you leave yourself time to pour over and savor the details.

The Observational Method as originally expounded by Ralph B Peck is often offered as a way to avoid failure of geotechncial works including tailngs dams.  Although seldom used in practice, it remains a viable approach.

Recently I had cause to write about groundwater impact analysis as it relates to mining.  I said they should use the Observatinal Method.  The groundwater engineers said "no way." 

I pointed out that their approach of distinguishing between deterministic and probabilistic modelling is just another way of doing the Observational Method. 

Consider: they define a few deterministic situations, a likely case scenario, and extreme upper bound case, and a very bad worst case.  They analyze all three and then go about monitoring in the field to see which one is correct. 

Sometimes they undertake probabilistic analyse to quantify the chance of their various scenarios coming to be.  But this is just a more sophisticated way of defining liekly and extreme conditions, which is the heart of the Observatinal Method. 

What do you think? 

On the 31st floor floor of a Vancouver downtown hotel this afternoon, we attended an open house arranged by Paterson and Cooke.  They presented the opening of their newVancouver office.  And caused me to think a radical thought that I write about here, namely are we entering the era of the end of paste tailings?

So radial an idea deserves explanation.  But first a summary of the Paterson and Cooke open-house.

Robert Cooke described the company objectives and projects.  They are indeed specialists in tailing transport: from South Africa, to Snap Lake, to Chile, and now a pipeline up to 137 km long in the North African desert. 

Then a dissertation by Yarek Koziura on rheology, that new term to describe the relationship between the rate at which you move tailings and the force required to move them.  Like peanut butter, tailings do not just flow; you need to apply force to get them moving; and the faster you apply the force the more likely they are to move.  The pipeline guys have always known this, but we geotechnical engineers are only now beginning to understand the implications of rheology in tailings deposition and cell design.  (Soon on EduMine there will be a course I have just finished writing on tailings and in that course I expand on the application of rheological principles to tailings practice)

Then to a good presentation by Rob Brown which was on a project.  I confess that I snoozed through the presentation and cannot report on it.  Contact Rob at Paterson and Cooke for details.  I picked up that it was a worthwhile project with many innovations. 

But back to my contentious statement that formed as I snoozed.  In fall last year, I went to a distant mine where the thickener had failed to thicken and the mine was closed.  Andy Robertson at the November 2011 Tailings and Mine Waste Conference said that paste tailings were one of the poorly performing dragons of tailings. At the same conference, Mike Davis of AMEC noted the irony that there are thickened/paste tailings conferences while filter-pressed, dry-stack tailings did not have its own conference, yet was a better and increasing way to deal with tailings.  On Monday I lunched with the environmental officer of a big mining company; I was told they are now reluctant to contemplate a new mine at which they cannot use filter-pressed, dry-stack tailings. 

And after the Patterson and Cooke presentations I was told they are moving to enter that field too.

Then I returned to the office to a call with friends in Australia.  They told me that there is a project in their desert to thicken the tailings and then polymer amend them just before deposition.  I did not catch all the details but is seems that thickening alone does not achieve the water use and quality objectives the project demands.  It is obvious to me they should go filter-pressing. 

I recognize there are cost considerations.  But if you cannot afford to get rid of the tailings properly, maybe you should not mine. 

Thus I plead for a discussion of this idea: are we at a turning point in tailings management? Are the old certainties fading? Are new realities about to make themselves dominant?  Comment below, for I cannot believe anybody will agree with me.

Last year I posted the following on my blog.  The questions I posed are stil valid and unanswered.  Maybe you can help.

Jump back to the proceedings of the 1979 Uranium Mill Tailings Management conference for the story of a tailings impoundment that was mis-managed and which, in consequence, failed.

Here is the way the paper by John Nelson and Joseph Kane describe the causes of failure (I edit some of the gauche prose the authors thrust on us.):

On July 16, 1979 the Church Rock Tailings Dam failed.  The embankment was about 35-ft high and was constructed on a relatively deep deposit of clayey, silty sand.  Certain soils were collapsible and laboratory testing indicated collapse in excess of ten percent upon wetting.  The impoundment was not lined, and seepage into the foundation soils could readily occur.  Along the southern half of the embankment, approximately three feet of settlement had been observed since the beginning of operation in 1977.  As a result of the large settlement, differential movement of the embankment would be expected.  BOth longitudinal and transverse cracks had been observed in the embankment prior to the failure, and were attributed to the differential movement occurring in the embankment. 

In order to protect against internal erosion of the embankment in the cracks, it had been recommended that a sand beach be maintained against the face of the embankment.  The purpose of this sand beach was to act as a source of sand that could then be carried into any cracks that  might develop.  The idea was that passage of sand into cracks would prevent internal piping.  The fact that sand was carried into the cracks was confirmed by observation after the failures of sand in the cracks on the walls of the breach.

Just prior to the failure, freeboard at the embankment had been decreased as a result of pond filling–the freeboard had been reduced to the point where tailings solution was in direct contact with the embankment and the sand beach had not been maintained. In that configuration, the sand beach because it was below the tailings fluid, was ineffective and the cracks within the embankment probably filled with tailings solution.  The owner’s consultants propose as a probable cause of failure that internal erosion of the embankment occurred under the action of the fluid in the cracks. 

Slope instability was ruled out on the basis of a few simple 1979 style stability analyses. 

Thus we have an instance of poor design, over-optimisitic assumptions, lousy impoundment management, and failure.  These days one cannot but wonder how they could stand b and see the embankment move, deform, crack, and not stop operation.  No doubt some unnamed consultant told them the risk was small as long as the kept a sand beach above water.  Which of course they did not do.  

What was the outcome of this failure?  If you know more, please comment.

Here is a note of tailings failure.  Please conside and comment.  I cannot determine when this was first posted on hte web.

The Joint Review Panel studying the Jackpine Mine Expansion Project must require Shell Canada to provide better information on the risks and environmental consequences of a failure of the dams supposed to prevent toxic tar sands tailings from spilling into the Athabasca River, says Sierra Club Prairie.
 
“Catastrophic spills like BP Deep Horizon and Fukushima happened even though the public was told that they never would" said Chelsea Flook, Interim Director of Sierra Club Prairie.  “Shell has clearly failed to meet some base requirements fundamental to adequate environmental, treaty and human rights protection in the area,”
 
“The Joint Review Panel cannot allow proponents to evade their responsibility to conduct quantitative, public risk assessments of tailing dam failures any longer” said Stephen Hazell, advisor to Sierra Club Prairie. “The risks of a catastrophic tailing dam failure destroying the Athabasca can only increase as more tailing dams are built in the tar sands, and as global climate change increases risks of extreme precipitation events resulting in flash floods in the Athabasca River Basin.”
 
Jim Kuiper, a mining engineer who reviewed the draft Environmental Impact Statement for Sierra Club Prairie, reported that “the EIS fails to contain or discuss any type of risk analysis for the tailings impoundment including consideration of worst-case scenarios. This is surprising given that difficult tailings facility foundations conditions have been noted at similar sites in the area, and similarly in terms of volume of engineered fill, oil sands tailings facilities are amongst the largest earth structures in the world . . .The EIS for the Jackpine Mine Expansion Project proposal must include analysis of potential failures modes that could lead to catastrophic or otherwise significant impacts.”
 
Sierra Club Prairie’s submission stated, “Development is occurring at such as fast pace that each new EIS cannot fully consider cumulative effects; projects are being announced and approved faster than the cumulative impacts can be evaluated in impact statements.” The Joint Review Panel needs more information on how a catastrophic tailing dam breach would impact the constitutional and treaty rights of downstream First Nations.
 
Sierra Club Prairie’s submission on the adequacy of the Shell’s environmental impact statement is available on the Canadian Environmental Assessment Agency public registry at www.ceaa-acee.gc.ca.
-xx-
 
For More Information Please Contact:
Chelsea Flook, Interim Director, Sierra Club Prairie chelseaf@sierraclub.ca (780)722-1226

Stephen Hazell, Ecovision Law Stephen@ecovisionlaw.ca (613)422-1107

There is nothing about the failure of tailings dams in the document I review below.  This is surprising.  Maybe they just choose nto to tell it all.  Nevertheless, if you take a look at the kind of clients the mining insurance industry is seeking, you will get an idea of what you have to do to avoid becoming a failure and insurance payout statistic next year. 

For a fascinating review of an aspect of mining not generally read or talked about, download a copy of the Spring 2012 Willis Mining Market Review.  It has ninety-two pages of information and great photos on risks and insurance against risks in the mining industry.  

We tend to read the news that is made bland or sensational by journalists.  Seldom do we get insight, as we do in this review of the aftermath of the tornado, flood, earthquake, or kidnapping.  In summary, the experts on both sides gather and try to get the insurance companies to pay. And to gather from this review they pay a lot, something like $95 B in mining claims in 2011.  

Which is why some insurers are dropping mining clients. The insurers prefer to service companies that have:

a) A clear understanding and ability to mitigate the effects of Contingent Business Interruption (CBI) exposures. This involves understanding the chain of customers and suppliers at multiple levels and mitigating the potential impact of losses to them by maintaining critical stocks and by identifying  alternative suppliers.   Bottlenecks in the supply and production chains will likely be subject to more penal terms and conditions by underwriters. With equipment suppliers reporting healthy order books, lead-in times to replace damaged or lost equipment are likely to lengthen further.

 b) A pro-active approach to minimizing the effect of weather-related events to their operations. Assets with large product and ore stockpiles are most likely to be looked upon favorably by (re)insurers, as will those with designated ‘sacrificial pits’ to allow for continued operations. In open-pit mining, the ability to exploit seams from higher benches immediately after wet weather, thereby allowing the lower part of the pit to become a sump, has been reported to be very successful in minimizing periods of force majeure.

c) Sound risk engineering and innovative risk avoidance measures form an integral and core part of their business. On a number of occasions in 2011, and in the face of potential loss incidents, various insured’s showed commendable alacrity in ensuring the continuity of their operations, and great attention was given to business continuity plans. With commodity prices remaining both high and volatile, this attitude will be of particular importance to excess of loss underwriters.

The review has much in a similar vein.  The more interesting human part is the story of kidnappings of mining people.  A terrible story to tell.  The worst country-for-mining-kidnapping list goes thus:  Nigeria, Pakistan, Mexico, Afghanistan, Venezuela, India, Phillipines,Iraq, Honduras, Colombia, Brazil, Guatemala, Turkey, Kenya, Malaysia, Yemen, Argentina, Nepal, Sudan, and China. 

Don’t get too nervous; ninety-seven percent of mining kidnappings last year were in Nigeria.  So you are relatively safe in most other places. Incidentally, the review notes that ten percent of kidnappings resulted in the death of the person kidnapped. 

The review notes that there were over 10,000 kidnappings of the general populace in Mexico in 2010.  I am not vacationing there!

And so on.  This is a fascinating and well-produced e-document.  Down-load it and tell us what you think.