Area affected by rains in MG has 3 of the dams with the highest risk of collapse in the country


The rains that have hit Minas Gerais in recent weeks and have already caused the death of at least 24 people are affecting the region where the three dams with the greatest risk of collapse in Brazil are located and reopen the “wound” left by the collapse of dams in Mariana. , in 2015, and Brumadinho, in 2019.

The dams are: Forquilha III, Sul Superior and B3/B4, all operated by Vale and close to cities that together have an estimated population of 255,000 people.

According to the National Mining Agency (ANM), these are the only dams in Brazil in a level 3 emergency situation, when the rupture is imminent or in progress. Since the start of the new rainy season, no incidents have been recorded in them.

Specialists interviewed by BBC News Brasil say that the rains increase the risk of problems in dams such as mining tailings. According to them, the risk in Minas Gerais is even greater due to the high concentration of these structures and their proximity to urban centers.

When contacted, Vale said it had built containments close to the structures to prevent the advance of sediments in the event of a rupture.

Amid increased rains, family members of victims of the Brumadinho dam collapse report apprehension and fear that scenes like 2019 could be repeated.

“There are helicopters flying over our heads and all this reminds us of that war scenario when the dam broke and killed my sister. Other relatives of victims comment on how much this reopened our wounds”, said Josiane Melo, who lost her sister in the Brumadinho tragedy.

The state of Minas Gerais has been hit by heavy rains since the beginning of the year. According to the National Institute of Meteorology (Inmet), in Belo Horizonte alone, precipitation accumulated 241.7 mm in 72 hours – between the 8th and 10th, well above the historical average for the month, which is 329 mm.

According to the state Civil Defense, 341 municipalities are in an emergency situation as a result of the storms. In addition to the dead, the rains left 3,900 people homeless and another 24,600 homeless.

The death toll does not include the 10 victims of the fall of a stone block on a speedboat in Capitol Hill on Saturday (8), because the case is still under investigation.

Companies like Vale, CSN, Usiminas, Samarco and Vallourec had to stop some of their operations.

Vale has paralyzed activities in two production areas. According to the company, the measure was taken to ensure the safety of its employees. It also paralyzed the circulation of trains on the Vitória a Minas Railroad (EFVM).

Mineração Usiminas interrupted its activities in the region of Itatiaiuçu (MG).

The company also informed that it activated level 1 of the Emergency Action Plan for Mining Dams (PAEBM) for its Central Dam, deactivated since 2014. This level predicts an initial state of alert, but would not mean that the structure is compromised.

On Saturday, the dam of a Vallourec dam overflowed and flooded a stretch of the BR-040, which connects Minas Gerais to Rio de Janeiro. The stretch was closed, but has since been released.

The incident caused the ANM to increase the emergency level of the dam to level 3, but the measure was reversed the next day and it is now at level 2. It is in the midst of this scenario that fears turn to the dams considered most susceptible to failure.


The three dams most at risk in Brazil are located in municipalities that, due to the rains, are in an emergency situation, according to the Civil Defense of Minas Gerais: Ouro Preto, Nova Lima and Barão de Cocais.

According to the ANM, however, the dams are not in an emergency situation due to the rains this year. They have been at this alert level since March 2019, after the dam at the Córrego do Feijão mine in Brumadinho collapsed.

According to the agency, emergency level 3 is granted when technicians verify that the structure of a dam is in a situation of imminent failure (it can happen at any time) or when it is already breaking.

In March 2019, when Vale raised the emergency level of Forquilha III and B3/B4, the company said that the measure was taken in a “preventive” way because they had safety factors below what the federal government standards determined.

The three structures are upstream dams of the same type as the one that collapsed in Brumadinho.

According to the ANM, they have a high potential for damage, which means that their disruption could cause significant damage to the communities located around them.

They are part of the company’s de-characterization plan, a term used by the industry to indicate the deactivation of a dam, works to make it totally stable and its reincorporation into the environment.

In a note sent by Vale, the company says that it has built structures to protect communities near the dams.

“All the company’s dams in this situation already have their respective containments completed, being able to retain the tailings if necessary. This is the case of the Sul Superior dam, at the Gongo Soco mine, in Barão de Cocais (MG); of B3/ B4, at the Mar Azul mine, in Nova Lima (MG); and from the Forquilha III dam, at the Fábrica mine, in Itabirito (MG)”, reads an excerpt from the note sent by the company.

Intensify monitoring

Professor at the Department of Civil Engineering at the University of Viçosa Eduardo Antônio Gomes Marques says that the intensity of the rains recorded in recent days increases the risk of incidents in dams.

“The rains do increase the possibility of incidents. This happens especially in Minas Gerais because we have a very large number of dams close to cities”, he explains.

Marques says that the risk of failure, however, affects both dams that are at emergency level three and those that are at lower levels.

He says it is important to intensify the monitoring of structures affected by the rain. According to him, one of the biggest concerns today is the behavior of the natural walls of dams.

Due to the rain, he says, the soil is very saturated and this could lead to a fall of ravines inside the reservoirs, which would increase the pressure on the dams leading to their overflow or, in extreme cases, to their rupture.

“We see that the dams are being monitored, but one possibility is that the rain makes the slopes fall, which would put pressure on the dams. This is dangerous because the structures are very close to cities and the time for evacuation is short”, he says. .

Regarding the three that are at the maximum emergency level, Marques confirms that the containment works have already been carried out and that, if they have been correctly dimensioned and executed, a possible rupture would have reduced impacts on the local population.

“The containment works were completed and a rupture would not bring as many risks as before. But this estimate considers that all the works were done and dimensioned correctly. If this did not happen, it is difficult to know the impacts”, he said.

The professor of dam safety at the Federal University of Itajubá (Unifei) Carlos Barreira Martinez says that it is necessary to keep monitoring of dams at emergency level 3 and intensify attention to other structures that, due to the rain, may pose risks.

He also points out a new element that, according to him, should be considered in the safety calculation for dams: the occurrence of extreme weather phenomena. According to him, climate change is altering the rainfall cycle and this can have an impact on dams.

“These structures are made considering a rainfall regime that did not foresee these extreme events that are so recurrent. What we are seeing is a series of very intense rains in a short time and in very specific regions. This can bring impacts that need to be scaled”, stated.

In a note, the ANM informed that it intensified inspections of dams in Minas Gerais in January due to the rains. According to the agency, more than 20 inspections have already been carried out in the state this month.

“The ANM teams are in the field, intensifying the inspection of the structures, in order to guide companies to mitigate any anomalies that are happening or will happen”, says an excerpt from the note. The report sought out the Fire Department and Civil Defense of Minas Gerais, but they did not respond.

Open wound

The increase in rains in Minas Gerais in recent days brought back bad memories for Josiane Melo, a resident of Brumadinho. Three years ago, she lost her sister when Vale’s dam at the Córrego do Feijão mine failed. Civil engineer Eliane Melo worked for an outsourced company in the area affected by the rupture.

“The rain left many people stranded, mud entering people’s homes. There are helicopters flying over our heads and all this reminds us of that war scenario when the dam broke and killed my sister. Other victims’ relatives comment on the how much it reopened our wounds,” he said.

Josiane says that the news about the possibility of the rupture of other structures is putting the population on alert. This is because, as in 2019, the companies responsible for the dams have stated that the structures are safe.

“It’s the same thing that happened in 2019. Everyone said that the Mariana and Brumadinho dams were safe until they broke. People are worried. Everyone is wondering: will it happen again?” he said.

The report sought the Fire Department and Civil Defense of Minas Gerais, but did not get a response.


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