The misfortune of Brumadinho triggered horror worldwide. At noon on 25 January, a section of a dam about 89 meters high collapsed in the Brazilian village. The resulting mudslide rolled over neighboring settlements and buried more than 300 people among themselves. So far, 186 bodies have been recovered. More than a hundred more people still missing are most likely dead as well.

The devastating avalanche was possibly preventable. According to documents of the public prosecutor of Brumadinho, which are available to the SPIEGEL, those responsible had been aware for about 15 months about security problems at the hill of rubble, mines and sludge. "Our evidence shows that this was not an accident," says William Garcia Pinto Coelho, the state prosecutor.

For the German TÜV Süd this could become a huge problem. Because the Prüfverein, who likes to act as a model of German thoroughness, was responsible for minimizing the risk of a mudslide. From the point of view of prosecutor Coelho, TÜV Süd did not live up to this responsibility.

From the minutes of a testimony it appears that the German examiners were involved in many questionable decisions in the period before the dam accident. And internal mails prove that a Munich-based TÜV manager was also involved.

Prosecutor Coelho's documents raise questions: Why is TÜV Süd so lenient when it comes to security? Why did he not intervene more consistently despite new problems in Brumadinho? And above all, what about the more than two dozen other dams in Brazil where TÜV Süd should also avert the danger of a mudslide?



Prosecutor Coelho makes serious allegations. The TÜV Süd and the mining company Vale, for whose iron ore mine Córrego do Feijão the catastrophic dam had been built, would have taken the "risk of dam failure," he told the SPIEGEL. And thus also "the death of hundreds of people".

The company Vale rejects this. There have been no indications of the disaster, writes the company, which has now millions of victims of the victims, the place Brumadinho and the misfortune affected companies paid.

Among other things, Coelho bases his allegations on the testimony of Makoto N. As of February 2017, the 62-year-old engineer worked for TÜV Süd's team, which assessed the safety risks of 25 dams for Vale, including the risks of the now partially collapsed dam B1 the iron ore mine Córrego do Feijão.

N. was the man who had signed many of the controversial safety reports of TÜV Süd for Vales dam, reports the "Wall Street Journal". He probably cooperates with the prosecutor to reduce his own possible sentence.

According to Ns testimony, which is the SPIEGEL, there have been several abnormalities in the past 15 months.

The controversial security value

In November 2017 N. took part in a technical meeting in Belo Horizonte. On this, he says, there had been a lecture by experts from the Brazilian company Potamos - a then partner of the TÜV Süd, which was later dropped by Vale, because he had demanded from the perspective of the mining company to high safety requirements.

The Potamos experts complained that it fell below a central, strictly observed minimum value, which describes the risk of soil liquefaction. The value should actually be at least 1.3, the scientists said. Dam B1 has only a value of 1.06. Earlier measurements were inaccurate.

Soil liquefaction is considered a horror scenario in the construction industry. Simply put, this happens when too much water penetrates into the earth and particles of soil are pushed so far apart that they barely adhere to one another. Solid soil becomes liquid and slips.

According to the Brazilian Environmental Agency, everything indicates that such soil liquefaction ultimately triggered the dam failure of Brumadinho. As early as 2015, liquefaction had caused the rupture of a nearby Vale-operated dam, the biggest environmental disaster in Brazil to date.

At the expert meeting in Belo Horizonte, the criticism of the low safety value of dam B1 caused some discomfort. A scientist who heard the lecture demanded a quick improvement of the measurements, says N. Otherwise, as the man should have said, "all high dams are damned for soil liquefaction".

After the expert meeting, TÜV Süd submitted a concept for improving measurements to Vale, says witness N. However, Vale refused. Instead, had been discussed at the request of Vale South urging Vale, whether one can not lower the minimum value of 1.3.

In a TÜV-Süd-Gutachten of September 2018, the minimum value of dam B1 to be observed is only given as 1.05. The value of the dam is slightly above, it says in the paper. The dam is therefore in "stable condition".

Why the value was so low despite the scandal at the expert conference is not known. Neither Vale nor TÜV Süd commented on this. Prosecutor Coelho accuses the German auditors, they had "adjusted the numbers so that they could issue the declaration of stability."

TÜV Süd did not respond to these or other allegations by the Brumadinho prosecutor. The testing association merely stated that it was currently investigating "internal processes and possible causes of the dam failure" and that external experts had also come to the house for this. If TÜV Süd employees prove errors, they will "draw conclusions".

According to the prosecution's documents, not only Brazilian employees are likely to be affected by the investigations.

The German middleman

On May 13, 2018, witness N. expressed massive doubts about the safety of the later catastrophic dam.

Everything points to the fact that dam B1 will "fail" an upcoming review in June, wrote N. in an email to five TÜV Süd colleagues. "Therefore, strictly speaking, we can not sign the Stability Declaration, which results in the immediate closure of all activities at the Córrego do Feijão Mine."

That would have been a disaster for Vale. According to the Wall Street Journal, the mine made more than $ 1 million in sales every year over the past year.

photo gallery

14 pictures

Dam failure: devastating mudslide in Brazil

Colleague Ns suggested that the problem be discussed with a Munich-based TÜV manager named M. He is said to have been privy to the events in Brumadinho.

The German had come to Brazil once a month, says witness N. He was a kind of "CEO for technical and administrative decisions" for her. Prosecutor Coelho also believes that M. "knew the security problems at the dam."

On June 12, the TÜV Süd Damm B1, despite N's concerns as safe. Why, does not emerge from the documents of the prosecutor. Even if M. and N. were in contact before the questionable decision is unclear. TÜV Süd did not comment on request.

Lucrative deals

Prosecutor Coelho suspects that the Germans were so lenient in their dealings with Vale because they did not want to jeopardize future business with the mining giant.

There is a risk that Vale will use a pending agreement "as extortion," wrote a Brazilian TÜV South employee on 14 May in an email to colleagues. The agreement, which Vale signed a few weeks later, includes new orders for TÜV Süd in the amount of around 2.4 million euros. Specifically, it's about services for 18 more Vale dams.

Note for informants

If you have any further information on possible mistakes that may have led to the dam failure in Brumadinho, please contact the authors Claus Hecking and Stefan Schultz. Your information and all personal information are covered by the protection of informants and will be treated confidentially.

At the TÜV Süd, they obviously hoped for even more business. On May 15, 2018, a Brazilian TÜV South employee wrote that the previous partner company Potamos would have shown "fear and indecision" in terms of security against Vale.

Vale no longer wants to work with Potamos, the mails say, "and that can be an opportunity for us". The business with the prevention of liquefaction of dams still offers "room for big growth".

The drilling error

At the B1 dam soon more things went wrong. In June 2018, so-called horizontal drilling started at the dam. This should drain water and thus reduce the risk of liquefaction.

TÜV Süd had proposed this internationally recognized concept to Vale in December 2017. Vale had preferred to a council of Potamos, support dam B1 and so reduce the risk of slipping, says N. The latter solution would have been "two to three times more expensive" than the measure proposed by TÜV Süd.

The holes at the dam were subject to complications. The commissioned company drilled, according to N. with too high water pressure, which would have formed fine cracks in the soil. The work was then stopped. N. emphasizes that poorly executed wells can cause soil liquefaction, especially if several holes are affected.

Opinion of Vale

However, Vale said that the drilling error apparently did not have much after-effects. He had occurred only in a borehole. Concretely, more earth had come out of this than would have been normal for the diameter of the hole. The hole was then immediately sealed.

Two gauges registered a jerky rise in water levels of around three meters at the same time, Vale says. After a few hours, the water level has returned to normal.

The holes were apparently then suspended. At the end of June, TÜV Süd had presented Vale with an alternative procedure for continuing the drilling, according to the prosecutors' papers. But Vale had rejected this.

The questionable report

On September 26, 2018, the TÜV Süd Damm B1 once again attested to the physical and hydraulic safety, despite the drilling rig and the aborted measures to increase the stability of the dam.

The explosive report is 256 pages long and bears the title "Geotechnisches Risikomanagement". Witness Makato N. signed the convolute - despite his previously expressed concerns.

SPIEGEL was able to see a German version of the stability certificate written in Portuguese. Whether it deviates from the Portuguese original, was not verifiable, since it comes from TÜV Süd, who has in Germany according to information from the environment of the company no own expertise on the safety of earth dams.

"I declare that I have carried out the regular safety inspection", it says in the report, and "certify the stability" of the dam.

On a scale from A to E, TÜV Süd certified the dam the grade B. It is the second worst rating, but according to TÜV Süd, it is still sufficient to continue operating the dam. Risk category "low", it says in the report.

The fact that dam 1 was quite flawed was documented by the Brazilian TÜV inspectors. Drainage channels are silted, it says in the report. The water drainage wall was cracked. In addition, the Brazilian TÜV Süd employees reported "termite and ant hills", wild growth on a slope and a leaky water pipeline. Nevertheless, the "Brazilian minimum requirements in the area of ​​security" are fulfilled.

To increase the safety of the system, the experts recommended avoiding vibrations and detonations in the immediate vicinity. Also, no heavy equipment should be used in the area of ​​the dam. The "vegetable soil surfaces" should be pruned and keep the water level low. For this purpose, the installation of additional measuring instruments to control the water pressure was recommended.

Vale later claimed that 8 of the 17 improvements to the dam required by TÜV Süd in its report had been implemented by the day of the disaster.

Witness N., on the other hand, criticizes the "slowness" with which improvements to the dam had been implemented. Above all, Vale had promised to support the dam, as once demanded by Potamos. But this plan was not implemented.

Strange measurement data

On January 11, gauges in Damm B suddenly showed data that again indicated a jerky rise in water levels.

The measurement intervals were then increased, writes TÜV Süd employee Marcelo P. in the mail change. First, there were daily measurements, from 21 January then "every five minutes". Who made this, is not clear.


Torn bridge in Brumadinho

The data may indicate that the dam had "signs of collapse" even days before the disaster, P. continues. If the population could have been warned about the deadly mudslide.

Vale refers to an external report from the beginning of February. It states that there was apparently a configuration error in 4 out of the 46 meters installed at the dam. Further checks would have shown that the water level in the dam had remained stable contrary to the strange measured data.

On 22 and 23 January, engineers from Vale and TÜV Süd also inspected the dam, Vale continues. Again, no security problems have been discovered.

An explanation why just before the mudslide strange measurement errors occurred, but Vale has not.