Safety of Dams

Repair and development

Safety of Dams


Safety of Dams

For information about the safety of our dams, check out the following content and watch the videos with explanations of Marcelo Klein, Vale´s director of Recovery and Development.

Dams levels

See Vale’s actions according to the safety level of the dams.

Level 1

When an anomaly is detected that results in the maximum conservation status score or any other situation with potential compromise of safety of the structure, which requires special (daily) inspections.

Level 2

When the result of actions adopted in the anomaly referred to on level 1 is classified as “not controlled” or “not extinct”, requiring new especial inspections and interventions.

Level 3

Imminent rupture situation or already occurring.

Why has the safety classification of dams been raised from Level 2 to Level 3?

What is Vale doing to ensure that dams classified at Level 3 do not breach?

According to Brazil's National Mining Agency (ANM, Agência Nacional de Mineração), the Level 3 indicates that the structure is breaching or the breach is imminent. Is that right?

Evacuation Trainings and Sirens

The siren activation is part of the Emergency Action Plan for Mining Dams (PAEBM). When level 2 of a dam is declared, the siren is activated and has the specific function of alerting the need for evacuation from the Self-Rescue Zone (ZAS). And at level 3, the siren has the function of alerting that a rupture is imminent or is occurring. It is worth mentioning that at emergency level 1, despite the sirens not being triggered, the entire dam security team is already aware and working so that the situation does not evolve.

Are the cities being informed about the evacuation trainings? Is there any prior preparation? Does everyone have to participate?

A listing is made of all the people who are in the Secondary Safety Zone. Then, informative folders are distributed to invite these people for training lectures that take place one day before or in the morning of the day for evacuation training. Lectures are available at several sessions. It is an adequate moment to share information. These evacuation trainings take place in the middle of the afternoon. We always encourage the participation by the greatest possible number of people so that it is representative..

Why are so many evacuation trainings being provided? What happens during the evacuation training?

Areas with dams classified at a high level from 2 to 3 must participate in the evacuation trainings. They are important so that the population knows the procedures in case of an eventual breach. During evacuation training, residents are informed about the procedures, which are basically moving from their homes to the meeting point, where they will be safe and assisted.

The schedule for preparatory meetings and evacuation trainings has been disclosed in the news section about dams on our website

Click here to see the latest news

Technological investment in tailing dam monitoring

  • Video monitoring devices for 24/7 coverage
  • Piezometers measuring water level at different points in the dams
  • Acquisition of new piezometers and inclinometers
  • Geophones measure dam’s response to seismic activity
  • Radars ensure fast response and millimetric precision
  • Satellite and drone imagery to support conservation states and ground displacement

Geotechnical Monitoring Center

  • Data gathering from various structures
  • 24 specialists, on shift rotation, are responsible for monitoring the data 24 hours per day, 7 days per week, to ensure safe and quick decision making
  • The Geotechnical Monitoring Center started operations in February 2019, and will be expanded throughout all of Vale’s iron ore geotechnical structures

Information about the Zones

Which area must be evacuated? Why people did not evacuate the Secondary Safety Zone?

Only the Self-Rescue Zone must be evacuated because it takes up to 30 minutes for the flooding to reach this area. Residents of the Secondary Safety Zone must participate in the evacuation trainings only. There is enough time for people to follow the procedures and ensure their own safety.

What happens to the employees who live in the Self-Rescue Zone and the Secondary Safety Zones? Shall they follow the same procedures?

The procedures are the same for each and every citizen. There is no distinction between employees and non-employees. The Self-Rescue Zone, classified at Level 2, must be evacuated, and people of the Secondary Safety Zones must participate in the evacuation trainings as planned.

Self-Rescue Zone

The Self-Rescue Zone (ZAS, Zona de Autossalvamento) is the region up to 10km or 30 minutes from the dam breach point. People are responsible for their own rescue. They must get out of the flooding area and go to a safe zone on her own.

Secondary Safety Zone

The Secondary Safety Zone (ZSS, Zona de Segurança Secundária) is the region beyond 10km or 30 minutes from the dam breach point. If the dam breaches, there is enough time for the trained people to act for their own rescue and go to the meeting points for assistance. The meeting points are informed during the trainings conducted by the Civil Defense.

Learn more about the Safety Indicator

The Factor of Safety for dams is evaluated by means of complex calculation. Geotechnical algorithms take several factors into account to determine this safety.

Has there been any change to this indicator? Since when?

There was no real physical change in the condition of Vale dams. With regard to safety factors, the requirement level is higher. Some dams are classified at the minimum tolerance level to ensure the safest and most conservative assessment condition.

Oque é mancha de inundação?

What is the flooding area?

It is the picture of a region estimating effects after a dam breach. It presents the amount of material contained in the dam through mathematical templates, possible method for draining the material, and extent of the breach. It is calculated considering safety factors so that, in case of a breach, the real flooding area is smaller than the theoretical flooding area.