On Tuesday I was in yet another of those asinine arguments about what constitutes “perpetual” in mining and mine closure. I had heard all the arguments, smart and cynical, more than thirty years ago when we debated them on the UMTRA Project. But the pusillanimous arguments continue, for everyone has an opinion and wants to be heard.
“The BC and Canadian governments will always be here,” is the first profound statement. “They will always be around to provide institutional control of the closed mine. You need not examine how the closed mine will perform in the absence of responsible surveillance and maintenance.” There is always a cock-eyed optimist in the crowd!
“Unless, of course, they have mined out the oil sands, and everybody is starving and they have cut all the timber and have decaying houses. Then they will not give a damn about your silly closed mine that relies on the government to keep it in shape and prevent its failure.” There is always a cynic in the crowd!
What does “perpetual” mean in the context of mine closure?
Maybe it means what the dictionary says it means, namely forever.
But how long is forever? The lawyer instinct is strong in us all regardless of how much we deprecate lawyers.
Maybe forever is as long as the universe has existed. Say 14 to 15 billion years. Or maybe it is only as long as there has been mining. They were mining at Bomvu Ridge in Swaziland 43,000 years ago.
Or maybe it is as long as the Holocene; that geological age that begun about ten thousand years ago with the retreat of the last glaciers.
“No. It is only as long as the Bible says the earth has existed. God created the earth only about 6,800 years ago. So why try to out-time God?”
My Spanish friends say perpetual is 2,000 years. That was when they begun mining in Spain to provide the needs of the Roman Empire.
Not so, say the Greeks. “Athens flourished long before that on the output of the Laurentian silver mines. They never closed them. Just build a decaying temple to some goddess and nobody will care to go see the damage wrought by 2,800-year old mines.”
Today I got a paper from Mark Logsdon–email me if you want the paper–I will refer you to Mark for a copy of the paper. He notes these examples of old mining:
- Example 1: There is a record of sulfide mining in the Iberian Pyrite Belt that extends at least 4,500 years. Massive-sulfide copper deposits of the Eastern Mediterranean were major sources of copper in the Homeric Bronze Age, and they continue to be reactive today
- Example 2: In erosional scars exposed in Quartz-Sericite-Pyrite altered volcanic and intrusive rocks in the Red River Valley, northern New Mexico, the radiometric dating of jarosite and alunite formed by oxidation of pyrite in these scars indicates that pyrite has been reacting in situ for periods of 30,000 to 1.5 million years, yet such altered rocks still retain much of their original pyrite. Calculated depletion times for waste rock there range from ca. 1,500 a to more than 100,000 a, based on plausible alternative models for the hydrodynamics of the waste-rock piles.
Mark then summarizes current thinking on the UMTRA standard of longevity/perpetuality, namely “1,000 years to the extent reasonable, and at any rate for 200 years. “ He writes:
There is no industry standard for such a long-term performance of closed mine facilities, nor are there established regulatory criteria for rock piles. The only geotechnical systems for which there has been extensive analysis of long-term periods of performance is for the mining and milling residues controlled under the Uranium Mill Tailings Radiation Control Act (UMTRCA) of 1978 (P.L. 95-604). The regulatory standard requires that control of tailings “shall be effective for up to 1,000 years to the extent reasonably achievable and, in any case, for at least 200 years” (EPA, 1983). The UMTRCA time frames were established to consider periods over which climatological and geomorphic processes could reasonably be predicted, given current knowledge of earth science and engineering. In a review of the technical basis for the regulations, the National Research Council, the contracting-review arm of the U.S. National Academy of Sciences, concluded that the 200-year period was consistent with our knowledge of the longevity of engineered systems, but that estimates looking forward 1,000 years must be thought of as qualitative and inherently uncertain.
The Academy has recently returned to this topic in an updated review of the performance of engineered barriers for waste management (NRC, 2007). The general conclusion of the NRC is that up to 20 years of field observations indicate that engineered waste-containment systems designed, constructed and maintained appropriately meet or exceed their intended performance. However, NRC notes that the demonstrated period of performance for such systems remains only a few decades, and that longer–term monitoring will be needed to show that performance over hundreds of years can be achieved reliably across the range of waste-management alternatives currently in service. A key finding of the recent study is that on-going maintenance is required (Mitchell, 2008).
Industry-standard practice by mining companies and their technical advisors considers that engineered covers, such as a stable, very low erosion slope with a low-net infiltration, sustainable re-vegetated cap can be established. Given the exploration, development and operation history of the mine and an expected construction and reclamation activity on the order of 50 years, there will be nearly 100 years of geologic and hydrogeologic data available for most modern mines. It seems entirely reasonable to project that time period forward and to establish a goal of 200 years performance for the engineered closure system at modern mines, in keeping with the rational of the National Academy.
Only outsiders used the acronym UMTRCA. It is the obvious one, but you use UMTRA Project if you are an insider.
To me this is all nonsense. I an my engineers designed and oversaw the construction of those cells. They will last a thousand years. If you doubt me just go see how the Cahokia Mounds have performed over a thousand years. Or see the Myan Mound at my Guatemalan site. Great stuff for idle and unemployed consultants to blather about. But guys, it has all been researched and said. You are perpetually repeating the obvious.
Now I know many hate the UMTRA formula of 1,000 years to the extent reasonable and at any rate for 200 years. Andy Robertson can expound for hours on why it is wrong, muddle-headed, and absolutely inapplicable in Canada.
Even Mark cannot bring himself to accept and validate it. Instead he take refuge in this wordy restatement of the same idea:
Consideration of these periods, the scientific basis for understanding closure risk, and established engineering practice leads us to suggest that a reasonable, total planning period for management of mine wastes should be in the range of 200 years, and it probably should include a semi-quantitative assessment of whether or not major changes in performance are likely to occur between approximately 500 and 1,000 years. Plans should include (1) identification of risks to surface and ground water in terms of adverse impacts to beneficial uses, (2) presentation of a case that mine-waste structures would be stable with respect to erosion by flooding or deep-seated shear failures, and (3) presentation of a case that reactive wastes as disposed for those periods will remain physically stable.
There we go again: risk assessment is the magic wand!
Of course, on UMTRA we did not do risk assessments. They became fashionable long after we had closed 24 sites. Now we can “explain” away almost every decision on the basis of a spurious risk assessment. If you do not believe me, talk to Franco Oboni and his son Cesar Oboni at Riskope.
The consultants and operators in the oil sands industry have recently provided us with another definition of perpetual. They conclude that before you can de-list an oil sand tailings facility you must prove that is will respond to long-term geomorphic forces in the same way as the natural landscape around the closed and e-listed facility.
Now that is innovative and superbly bold: make the closed facility just like the hills & valleys, just like the wetland & rivers, just like the local arboreal forests of northern Alberta. An amazing concept. I would have thought this would come from a regulator. But is comes from the consultants and operators of the oil sand mines. So we must presume they honestly believe they can do it, and achieve this immeasurably ambitious goal, and can close their mines so that an alien in an arriving spaceship could not tell the difference between nature and man-made.
Their naivety is stunning. Not the aliens! But the humans!
OK. I concede that it is easy to blog on this topic. I concede that it is impossible to get an answer. I concede that the reality is that every closed mine will need institutional controls which implies the presence of government. I concede that it is good to believe that government, as we now know, it will be there. And to close mines on the basis that the government will be able and willing to do whatever is necessary in the long term. Look at Giant Mine and Faro—perpetual make-work projects by any definition.
But in my heart, I cannot believe that governments will always be there and willing to undertake surveillance and maintenance of inadequately closed mines. Maybe I have read & thought too much of history to believe that what is now will always be.
Thus I must conclude that the simple, professional thing to do is close mines to be stable for 1,000 years to the extent reasonable and at any rate for 200 years. I know it can be done; I have done it.
The rest is repetition, avoidance, dodging, and persiflage.
PS. As an alternative, attend the seminar Cold Cover Practice 2014. Its alternative title is Seminar on Cold Regions: Cover System and Mine Closure. I may go. I will not present. There will be many other experts there who will prove the points of this blog posting. You can be sure they will deny what I write. Maybe they can persuade you to an alternative perspective. It could be fun.
PPS. Or just read this excellent report on solutions to the issues.