HOME   WISE Uranium Project   >   Tailings Dam Safety   >   Issues   >

The Brumadinho tailings dam failure (Minas Gerais, Brazil)

(last updated 17 Feb 2019 22:00 UTC)

Contents:


The dam failure and its impacts

At 12:28 PM on Friday, January 25, 2019, tailings dam No. 1 of Vale's Córrego do Feijão iron ore mine near Brumadinho, Região Metropolitana de Belo Horizonte, Minas Gerais, Brazil, suddenly failed, releasing almost its complete holdings of 12 million cubic metres of tailings in a big burst.

Travelling at up to 120 km/h, the tailings wave first touched the foot of adjacent Dam No.6, then hit the mine's loading station, its administrative area (including a cafeteria where many workers had lunch at the time), and two smaller sediment retention basins (B4 and B4A).
The slurry wave then traveled approx. 7 km downhill until reaching Rio Paraopeba, thereby destroying a bridge of the mine's railway branch, and spreading to parts of the local community Vila Ferteco, near the town of Brumadinho.
The slurry wave killed 169 people, and 141 are reported missing.

The slurry was then carried further downstream by Rio Paraopeba, thereby killing all life in the river and inhibiting production of drinking water in settlements along the river. It is expected to arrive at the dam of the Retiro Baixo hydroelectric plant approx. 300 km downstream within two weeks.

At 5:30 AM on Sunday, January 27, 2019, residents of Brumadinho were evacuated, as it was feared that Dam No.6 could fail, as well, since dam monitoring instruments detected an increase in water levels. Around 15:00, it was determined that the risk had decreased and residents were allowed to return to their homes.

 

The causes of the dam failure

At the time being, the cause of the dam failure is unknown. Unless more information becomes available, all discussion on the causes of the failure remains speculative.

According to Vale, the dam was built in 1976 by Ferteco Mineração (acquired by Vale on April 27, 2001), using the upstream method. The dam was 86 meters high with a crest length of 720 meters. The disposed tailings occupied an area of 249,500 m2 and the disposed volume was 11.7 million m3.

The dam last received tailings in July 2016 and was "deactivated" thereafter. There apparently was no ponding water on top of the tailings except for a small section.

For reasons so far unknown, the slope of the dam appears to have gone through a sudden massive rotational failure that extended across the full width and height of the dam.

There are no reports of any external events that are typically known to trigger such failures, such as earthquakes or heavy rainfall.

It is known that dam slopes with marginal safety factors may fail upon slight vibrations, such as caused from trucks passing nearby.
In this case, the trigger might have been the drilling of a monitoring well that was ongoing in the middle of the slope as it collapsed.
If this drilling activity actually triggered the dam failure, then the safety factor of the slope must have been on the brink. It is unclear how this can have gone unnoticed, given that, according to Vale, the dam had 94 piezometers (instruments for measuring the pressure of a liquid) and 41 water level indicators to monitor its integrity.

Information surfacing bit by bit in early February 2019 appears to confirm that the factor of safety of the dam was inacceptably low and that there were serious deficienies with monitoring of the dam stability:

Given the information that surfaced so far, it becomes obvious that the company was very well aware of the low factor of safety and the various circumstances increasing the liquefaction hazard. But why did they not take appropriate action to reduce the hazard? The company rather maintains: "There is no known report, audit or study with any mention of an imminent risk of collapse at Dam 1 in the Córrego do Feijão mine in Brumadinho," and: "To the contrary, the dam had all its certificates of safety and stability attested to by local and foreign specialists."

 

The aftermath of the dam failure

Minas Gerais Government gives companies 3 years to eliminate 50 upstream dams: On Wednesday (Jan. 30), the Environment Secretariat of Minas Gerais determined that the dams built in the state by the upstream damping method - the same used in the dams responsible for the Brumadinho and Mariana tragedies - are decharacterized. Although it is quite common and cheap, it is considered less safe by experts because of the risk of accidents.
In a resolution published in the Official Gazette, the agency determines that the companies responsible will have 360 days to present the technology to be adopted and the work plan with a schedule. From there, they will have two years to implement this new technology. By the determination, the structures must cease to possess characteristics of dam, that is, to stop retaining rejects, being destined to another purpose.
Still according to the Secretariat, there are currently 50 dams upstream in the state, in addition to the one that broke in Brumadinho. Among them, 27 are in operation, and 22 are paralyzed. (Globo Jan. 31, 2019)
> View: Environment Secretariat release Jan. 31, 2019
> View: Resolução conjunta SEMAD/FEAM nº 2.765 , de 30 de janeiro de 2019

Minas Gerais cancels licenses to operate tailings dams at two other Vale mines in wake of disaster: The Brazilian state of Minas Gerais canceled Vale SA's license to operate a dam at one of its largest mines, the company said on Wednesday (Feb. 6), following the collapse of another dam in the state that killed an estimated 300 people.
The state canceled Vale's license for Laranjeiras dam. It had been used in the operation of the Brucutu mine, which had already been suspended by a court order, freezing nearly 9 percent of the company's output.
Minas Gerais also canceled Vale's license to operate its Jangada mine, which has been paralyzed since the dam close to the Córrego do Feijão mine burst in the state, killing at least 150 people. Another 182 people are still missing from what is possibly Brazil's most deadly mining disaster.
The cut in output from Brucutu forced Vale to declare force majeure in iron ore and pellets contracts on Tuesday (Feb. 5). (Reuters Feb. 6, 2019)

Brazil set to ban upstream tailings dams after collapse kills hundreds: Brazil's mining agency plans to ban upstream tailings dams used for storing mining waste, a director at the National Mining Agency (ANM) said on Thursday (Feb. 7), after such a dam burst last month, likely killing at least 300 people. Eduardo Leão, a director at ANM, said the agency aims to issue an ordinance on Friday (Feb. 8) requiring that such dams be taken down or converted into other types of dams.
Brazil has 88 upstream tailings dams, according to Leão. It was not immediately clear what kind of deadline the dam operators would face to take down or convert the dams. (Reuters Feb. 7, 2019)

Federal Public Prosecutor's Office calls for emergency measures to prevent failure of tailings dam at former Poços de Caldas uranium mine (Brazil):
> See here

Minas Gerais Public Prosecutor's Office tries to suspend deployment of large tailings dam of Vale near condominiums in Itabirito: The Minas Gerais Public Prosecutor's Office (MPMG) is trying to stop the implementation of Vale's Maravilhas III ore tailings dam with a capacity of 108.86 million cubic meters in Itabirito, in the Central Region of Minas Gerais.
The petition, which was filed at the 1st Public Treasury Court of Belo Horizonte, requests, as a matter of urgency, the revocation of an earlier court decision, which allowed for the implementation of the enterprise. The risk is that if this reservoir is broken, two residential condominiums and at least four rural properties could be hit by mining tailings. According to preliminary information, the dam would have a waste storage capacity nine times larger than the Brumadinho dam. (Jornal Estado de Minas Feb. 7, 2019)
> View MPMG release Feb. 7, 2019

Bill to toughen mining rules back to deal in Minas Gerais Assembly: After being rejected last year, a proposal to siege and tighten the rules in the mining sector is back in the Legislative Assembly of Minas Gerais (ALMG) . [...] The expectation is that it will be voted shortly in the Public Administration Commission, where it was presented on Monday (Feb. 4).
The project, which has as its mouthpiece in the Assembly the deputy João Vítor Xavier , was built in partnership with the Public Prosecution and civil society. The text is a regulatory framework for dam safety in Minas Gerais.
"We want an effective regulatory framework. Economic issues can not continue to overlap with human and social issues," said promoter Andressa Lanchotti, coordinator of the Operational Support Center of the Environmental Defense Prosecutor's Office and coordinator of the task force that manages the disaster of Mariana.
The joint proposal touches on points such as the use of better technologies, the existence of people in the self-rescue zone and also provides for an environmental bond. It is a matter of forcing the miners to reserve money or have insurance-guarantee to, in case of disaster, to deal with socio-environmental issues and reparation to the victims. "Samarco and Vale are two giants of the sector, but what if a tragedy occurs with a company without capital or in abandoned mine?", warns the developer.
Deputy João Vítor recalled that the substitution was made on the basis of a technical note from the MP, of 18 pages, pointing out the weaknesses of the PL currently underway in the Assembly. (Jornal Estado de Minas, Feb. 7, 2019)

Three towns evacuated for failure risk of tailings dam at Vale's Gongo Soco mine in Barão de Cocais, Minas Gerais: The National Mining Agency has ordered the withdrawal of about 500 people from the communities of Socorro, Tabuleiro and Piteiras, all in Barão de Cocais, in the Central Region of Minas Gerais, because of the Southern Superior Dam of Vale's Gongo Soco mine. The residents were evacuated at dawn on Friday (Feb. 8), around 1am.
According to the miner, Warm Consulting denied the Stability Condition Statement of the structure. From there, the company began to perform level 1 of the Emergency Plan of Mining Dams. Sirens were triggered and people started to leave their homes. (Globo Feb. 8, 2019)
> View: Vale release Feb. 8, 2019

Town evacuated for failure risk of tailings dam at ArcelorMittal's Serra Azul mine in Itatiaiuçu, Minas Gerais: Residents of the town of Pinheiros, in Itatiaiuçu, Metropolitan Region of Belo Horizonte, were removed from their homes at dawn this Friday (Feb. 8). Altogether, about 50 families were evacuated from their homes.
According to the city's Military Police, the request for support of the withdrawal came from the Civil Defense, which warned of the risk of breaking the dam. The village is 1.5 kilometers from the dam. The families were taken to hotels in the city of Itaúna, in the Central-West Region of the state. The dam belongs to the mining company ArcelorMittal . Wanted, the company has not yet returned to the story. (Globo Feb. 8, 2019)
> View: ArcelorMittal release Feb. 8, 2019

Eight other tailings dams at risk of failure: At least eight ore tailings dams in Minas Gerais are also at a severe risk of disruption. In a public civil action signed on February 1 in a secretive, now broken, case, the Public Prosecutor's Office asked Vale to urgently comply with measures that would reduce the possibility of new tragedies such as Brumadinho, where dam 1 of the Córrego do Feijão Mine was broken, leaving, so far, 165 people dead and 155 missing. According to the document, Vale has already known about these risks since October 2018.
The MP action was filed on February 1, five days after the Brumadinho disaster, based on the mining company's own inspection documents - issued in October 2018. The eight dams mentioned are located in the cities of Barão de Cocais (Dam Laranjeiras) , Nova Lima (Capitão do Mato Dam, Barrage Dam B and Dam Taquaras), Ouro Preto (Dam Fork I, II and III) and another in Brumadinho, within the Córrego do Feijão mine complex (Menezes II Dam). (Jornal Estado de Minas Feb. 12, 2019)

Two more tailings dams at risk of failure: The number of dams at risk of severe disruption in Minas Gerais increased to 10. According to a lawsuit filed by the State Attorney General's Office (MPMG), the Sul Superior dams (Mina Gongo Soco) in Barão de Cocais (Central Region) and Vargem Grande in Nova Lima (Grande BH) are also in threat. On Tuesday (Feb. 12), the agency had already released a document containing eight other dams at risk. (Jornal Estado de Minas Feb. 13, 2019)

NGOs create information platform on social and environmental impacts of Córrego do Feijão dam failure: With the creation of a Civil Society Crisis Office, civil society organizations will monitor the situation of those affected by the rupture of the Vale dam in Brumadinho.
Composed of environmental NGOs and human rights activists, the office will monitor actions related to the rupture of Vale's tailings dam at the Córrego do Feijão Mine, request the punishment of those responsible and defend victims' rights, support and propose measures to prevent new disasters and tragedies and to give visibility to the impacts of mining on communities.
Other issues addressed will be the role of the company and the various actors after the tragedy and the perspective on water security in Belo Horizonte and the Metropolitan Region and the future regarding the possibility of new disasters related to the rupture of mining tailings dams.
The main instrument of the cabinet will be a digital platform that is already available. (Globo Feb. 14, 2019)
> View: Gabinete de Crise Sociedade Civil

Town evacuated for risk of tailings dam failure at Vale's Mar Azul mine in Nova Lima, Minas Gerais: The Minas Gerais Fire Department has now informed that it will evacuate a risk area of the B3/B4 dam at Vale's Mina de Mar Azul mine in the municipality of Nova Lima (MG). Between 170 and 200 people will have to be removed from the site, which covers about 49 buildings, between homes and commercial establishments.
At the request, Vale reported that it activated Level 2 of the Emergency Action Plan for Mining Dams (PAEBM) for the B3/B4 dam at the Mar Azul mine, in Nova Lima, MG, on Saturday (Feb. 16). According to the company, the measure was taken "for safety". According to the company, the measure is "preventive." "The decision is a preventive measure and takes place after reviewing the data of analysis reports of specialized companies hired to advise Vale. It should be noted that the structure is inactive and this initiative has a preventive nature," said the company in a note sent by its press office.
According to the Fire Department, the audit refused to certify security of the structure, which motivated the preventive evacuation. B3/B4 have about 3 million cubic meters of tailings. That is, it was built with the same type of structure as Dam I of the Córrego do Feijão mine, which broke at the end of January, in a tragedy that goes to have more than 300 dead. (Estadão Feb. 16, 2019)
> View: Vale release Feb. 16, 2019

 


Resources

Maps:

 

Views:

 

News + Infos:

Company

Government

Academic

Environmental NGOs

Newspapers

 

Literature

 

HOME   WISE Uranium Project   >   Tailings Dam Safety   >   Issues   >