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Progress of the de-characterization plan for upstream structures

Vale reiterates that its priority is the safety of people and communities downstream of its operations, as well as the safety of all its structures. One of the main initiatives to reduce the company's risk level is the decharacterization of all of our 30 upstream geotechnical structures in Brazil, including dams, dikes and drained piles.

An upstream structure is a geotechnical structure built using the upstream raising method, in which the body of the structure is built from the thick tailings deposited in the reservoir, by successive stratification and in the opposite direction to the water flow (upstream). This is the same method of construction as the Brumadinho dam.

What is decharacterization?

The term ‘‘decharacterization’’ means functionally reintegrating the structure and its contents into the environment, so that the structure no longer serves its primary purpose of acting as a tailings containment. Recently approved laws and regulations require us to decharacterize all of our upstream structures occurs on a specified timetable, based on projects agreed with authorities.

The decharacterization of an upstream structure is a complex process and may take a long time to be concluded with the necessary safety precautions. The works related to the decharacterization process presents individual challenges that requires specific solutions as it may influence the geotechnical stability conditions and increase the risk of such structures.

Vale is conducting detailed engineering studies for each structure to be decharacterized and the improvement of stability may be required, through reinforcement works or building downstream containment structures (ECJ or back-up dam) to safely initiate the decharacterization. The back-up dams have the purpose of retaining tailings in the event of a dam failure. All these projects are subject to  review and eventual approval by the authorities.

Vale's decharacterization plan

The decharacterization plan for Vale's upstream structures was updated in 2021 and comprises 30 geotechnical structures, after the inclusion of Area IX dam, at Fábrica Mine, in Ouro Preto, MG, which had its construction method reassessed and changed to the upstream method, in light of new information and parameters identified with the execution of its “As-Is” project. 

 The latest update shows that Vale has already eliminated 7 upstream structures in the country. The dams that have been decharacterized and reintegrated into the environment are the 8B, Fernandinho, Rio do Peixe dike and the 5 dike of the Pontal dam, in Minas Gerais; and the 2 and 3 dikes of the Kalunga dam and the Pondes de Rejeitos dam of the Igarapé Bahia, in Pará. This means that these structures have lost their upstream characteristics and no longer have the purpose of acting as a tailings containment.

All the company's dams are continuously monitored by a series of instruments and by the Geotechnical Monitoring Center (CMG).

1- Early works started in July 2020
2- Spillway works started.
3- Decharacterization awaiting assessment by regulatory bodies
4- Beginning of the works of the preliminary stage of decharacterization
5- A second back-up dam is expected, with completion by 2025
6- Area IX was included in the portfolio after reclassification as an upstream dam, based on updated studies. Conceptual project under development.
7- ED means Drained Pile.
8- Early works started in 2021.

Resources for the decharacterization of upstream dams

In 2020, a total of US$ 293 million was disbursed with the decharacterization of upstream dams. As of December 31, 2020, a provision of US$ 2.289 billion was recognized in Vale's balance sheet for the decharacterization of upstream structures.

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