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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 ontainment. Recently approved laws and regulations require us to decharacterize all of our upstream structures 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 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 further review and eventual approval by the authorities.

Vale's decharacterization plan

Our decharacterization plan for Vale's upstream structures was updated in 2021 and now comprises 30 geotechnical structures, with 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. An initial study for its decharacterization is underway and the respective schedule will be announced in due course.

Vale completed the decharacterization works of 6 out of the 30 upstream structures to date. Between 2019 and 2020, it completed the decharacterization of Dique Rio do Peixe¹, II Kalunga and III Kalunga dikes, and 8B and Pondes de Rejeitos dams². In 2020, it also completed the construction of two downstream containment structures (ECJ), one for the Sul Superior dam and the other for B3/B4 dam. 

In 2021, Vale completed the decharacterization of Fernandinho dam and finalized the ECJ that serves Forquilhas I, II, III, IV and Grupo dams. For the second half of the year, the decharacterization of the 5 Pontal dike and the reinforcement of the 4 Pontal dyke are planned.

Vale's plan also includes the construction of another three ECJs for certain dams and dikes, to retain tailings in case of dam break, protecting the downstream area during the decharacterization works. The three ECJs are scheduled for completion in 2023, with a detailed timeline to be defined.

¹ Pending  the evaluation process from the National Mining Agency (ANM) and the State Environmental Foundation (FEAM).
² Pending assessment by ANM.
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 2023
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.

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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