DATE: March 17,2019 (revised 4/3/2019)
I have no faith that anyone in Brazil has the technical competence to assess the stability of the 17 identified large at risk dams let alone figure out how to safely de risk them. ANM , the new mining agency, and Brazil ‘s mining law is a runaway train. They are not capable of solving any of the problems its own confused law has created over 40 years.
source: Marcos Pedlowski April 2,2019
The 4 Risk 3 Level dams are deemed at imminent risk of failure. Dam VI at Corregeo Do Feijao, immediately adjacent to the failed Dam1 initially survived the explosive loss of Dam1 but is now listed at level 1 which requires specific re evaluation of stability and correction of identified problems.
The Brumadinho story is the poster child for the unknowing and misunderstanding of Static liquefaction an important and overlooked factor in as many as 50% of of the worlds catastrophic failures Morgenstern said in his recent Melo lecture. Brumadinho and the 17 identified large at risk dams are a common story of what we neglected over the past 40 years of our mineral supply model . How can we .now overcome and correct for errors in dam design and construction when for 40 years we have just kept building past them and on them . At Brumadinho at the 17 troubled at risk dams waste problems came from companies creating a global presence through mergers & acquisitions that didn’t involve much strategic vetting of the wastes they are taking on or even the quality of the deposits they were acquiring.
In 2002, just as Vale acquired the 3 mines of which Dam 1 was a part, Davies, Martin & McRoberts wrote:
“Design practice in many mining regions has in fact discounted the possibility of the mechanisms and criteria for this failure mode, the possibility of its occurrence has often been overlooked in the search for other causes of failure.
The simplistic view is that by defining the friction angle and pore pressure of the sand, we can predict the strength of that sand, the drained strength. The exception these references allow for is sands during an earthquake when the sand may become ‘liquefied.’ Clays on the other hand are deemed to be cohesive and have an undrained strength. Those readers who have benefited from a more enlightened geotechnical education may not find this a credible proposition, but it is clear to the authors that even as we enter the 21st century, a range of educators, regulatory and quasi-governmental groups, and an alarming number of geotechnical consultants still have not un-learned their first series of lectures in soil mechanics based on textbooks expounding the views noted above. Until these simplistic models have been un-learned by all involved with the design, licensing, and construction of tailings impoundments, a major contributor to failures, i.e. inappropriate and incorrect designs based upon a lack of understanding of the tailings strength, will continue. ” (emphasis added)
Davies, McRoberts, Martin ( 2002)
In late summer 2018, just months before the Dam 1 failure, Dr. Morgenstern wrote:
“From a technical perspective, it is of interest to note that inadequate understanding of undrained failure mechanisms leading to static liquefaction with extreme consequences is a factor in about 50% of the cases. Inadequacies in site characterization, both geological and geotechnical, is a factor in about 40% of the cases. Regulatory practice, considered appropriate for its time and place, did not prevent these incidents. However, the most important finding is that the dominant cause of these failures arises from deficiencies in engineering practice associated with the spectrum of activities embraced by design,construction, quality control, quality assurance, and related matters. This is a very disconcerting finding.” Morgenstern, The Melo Lecture August 2018
It is in this dark crevasse of “unknowing” that Córrego do Feijão Dam I matured to the 5th largest failure ever in recorded history, based on what we have now as deaths, runout, and release.
Most of the underlying failure conditions at Brumadinho already existed when Vale acquired in 2001. Vale just followed suit with past practices for at least the next 5 years. An awareness of critical issues, especially the drainage issues and the eroded unstable beach conditions emerged post 2006 but there was no systematic commitment to the identified fixes and changes needed in operations. The TSF had a scheduled end of life of 2016 and in 2013 less than 800,000 in capacity remained and Vale was on the hunt for tailings capacity to meet its goal of doubling production by 2023 so Dam 1 just counted itself out of serious attention by not furthering that goal. No fixes were planned. They simply stopped depositions and were pursuing a re mining plan at Dam1 as a revenue generating “de commissioning” or even possible sale. They had obtained an expedited permit for the re mining just before failure.
My advocacy for a few years now has been for a competently staffed adequately mandated Tailings Board similar to how a Buildings Department works. It would have special authority in the event of an impaired dam , especially one at risk of failure by static liquefaction, to essentially take custody of the dam to insure immediate competent expert attention to its de risking and stability. The $1 bn it may have cost to solve the Brumadinho’s problems is far less costly to civil society than the $13 bn it is trying to grab now for clean up. According to an inquiry from Deutchebank on what are realistic costs ,Vale is seeking a total $1bn for all 5 dams it had been directed to de commission. These dams can’t be immediately de risked or decommissioned for anything like $200M each. The work at these 5 dams must be determined by experts and they must have what they need no matter what the cost.
All would agree, this is no way to govern mineral resources and no way to provide a sustainable supply of world minerals. It will be disastrous if Brazil allows the response to the impaired at risk dams to proceed under Vale’s control especially having grabbed $13bn for clean up on the one that already failed. I am advocating emergency authority to create a sort of “protective custody” and informed oversight and authority and funding to act as needed to properly de risk or de commission those 17 dams which failed their stability re certification. Brazil law already provides for absolute liability regardless of effect on stock holders and investors. It already has the mechanism to finance what needs to be done on those dams.
For more on the Brumadinho and static liquefaction follow the unfolding narrative at http://www.worldminetailingsfailures.org