De-Characterization of Dams

Repair and development

De-Characterization of Dams

De-characterization is the process for a dam to be reincorporated into the relief and the environment.

When the structure is de-characterized, it does not serve its primary purpose of retaining tailings, ensuring zero risk for the environment and the surrounding communities.

Watch the video about the decharacterization of 8B dam in Nova Lima.

Planning

Vale has nine upstream dams under the process of de-characterization.

Learn about each phase of this process:

Place your mouse pointer over the illustrations to learn more

Click on the illustrations to learn more

Phase 1

Improvement of the Factor of Safety

In this phase, the company pumps surface water and builds peripheral channels to lower the level of material inside the structure. The pumping process of some dams involves drilling and operation of deep wells.

Phase 2

Enhanced Safety

In this phase, the dam slope is reinforced to stabilize the structure and prevent any collapse during treatment and construction works.

Phase 3

Removal of Material and Revegetation

After reinforcement works, tailings are partially or totally removed from the dam, according to the structure. The following phase is the treatment and revegetation of slopes and surrounding region with native species to reintegrate the area into the local environment.

Phase 4

Monitoring and Control

The last part of the process involves monitoring and controlling the environmental recovery of the area after de-characterization is complete. This phase also includes monitoring of physicochemical parameters and the biological stability of the region.

Schedule

Vale is making progress with the de-characterization of upstream dams.
Check below the calendar of planned actions.

Dam location

The nine dams under de-characterization process are located in Minas Gerais. Check out their location below.

Barão de Cocais - MG

Sul Superior Dam

+ see details

Nova Lima - MG

8B Dam

+ see details

B3/B4 Dam

+ see details

Fernandinho Dam

+ see details

Vargem Grande Dam

+ see details

Ouro Preto - MG

Forquilha I Dam

+ see details

Forquilha II Dam

+ see details

Forquilha III Dam

+ see details

Grupo Dam

+ see details

FAQ

What is the difference between de-characterization and decommissioning?

De-characterization refers to the treatment of a structure when it does not serve its primary purpose of retaining tailings anymore. After the works are complete, the remaining structure is fully stable and is reincorporated into the relief and the environment.

Decommissioning is the phase of the life cycle of the structure that begins upon the confirmation that such dam is no longer required in the operational context of the project and, therefore, can be deactivated or de-characterized.

How will the tailings from these upstream dams be handled after de-characterization?

The mineral goods from the nine dams under de-characterization process will not be used. The tailings will be disposed in depleted mines as well as in tailings and waste rock piles.

Can these construction works affect the stability of the structures?

The construction works do not add risk to the dams. Vale has been adopting all measures required to increase safety and mitigate the risks from interventions related to the de-characterization process. In the case of construction works intended to reinforce the dams set to emergency Level 3, for example, the company is considering some alternatives, such as the use of unmanned equipment (tractors, excavators, trucks, among others) operated remotely, in addition to helicopter and cargo cable car to access hazardous areas. The goal is to keep people away from the areas of risk.

Not all tailings will be removed from the structures. Still, is it possible to state that the structures have been de-characterized and are safe for those who live or work in these locations?

It is important to emphasize that the purpose of the de-characterization project is to fully de-characterize the dam from its purpose of retaining tailings. That is, at the end of the works, the structures are fully stable and reincorporated into the relief and the environment. In some cases, there will be residual tailings that will not affect the stability of the soil in which the dam was built.

Has Vale de-characterized any upstream dam before?

Vale started the de-characterization of its iron ore tailings dams in 2014, which also involved the implementation of a second ETD construction method. Since then, nine structures have been de-characterized – five upstream dams (Serraria dike, 7 Pontal dike, 1A Conceição dike, 1B Conceição dike, and 6 Pontal dike) and four built by the ETD method (02 Alto da Serra basin, 03 Alto da Serra basin, 04 Alto da Serra Fe basin, and 06 Pé de Serra basin).

Check out other information about Vale's dams:

Emergency containment

Vale is carrying out containment works in the dams currently set to emergency Level 3 in order to reduce possible impacts.

Read more +

Dam Safety

Learn some specific terms and Vale's initiatives to increase safety in the surroundings of its operations.

Click here +

Glossary

Check out some technical and specific terms about dams for a better understanding.

See here +

Dams

Learn more about this topic and Vale´s structures

Click here +