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Upstream Dam De-characterization Program in Brazil

Vale's priority is the safety of people and communities downstream of its operations, as well as the safety of all its structures. In this sense, one of the company's main initiatives is the Upstream Dam De-characterization Program, which covers all of our 30 dams, dikes and drained piles in Brazil with upstream heightening method.

Under the upstream heightening method, the body of the geotechnical structure is built from the thick tailings deposited in the reservoir, by successive stratification and in the opposite direction to the flow of water (upstream). This is the same construction method used on the collapsed dam in Brumadinho.

What is de-characterization?

The term ‘‘de-characterization’’ means to functionally reintegrate the structure and its contents into the environment, so that the structure no longer serves its primary purpose of acting as a tailings containment. Brazilian legislation requires that the de-characterization of all upstream dams take place on a specific schedule, based on projects agreed with the authorities.

The de-characterization of an upstream structure is a complex process, with specific challenges for each structure that, if left untreated, can affect the conditions of geotechnical stability and increase the risk of the works. Therefore, de-characterization requires time, intensive care with safety and customized solutions. The de-characterization projects include detailed engineering studies for each structure included in the program, with reinforcement works when applicable.

For the B3/B4, Forquilha III and Sul Superior dams, structures in critical safety conditions, Vale built downstream containment structures (ECJ) with the purpose of retaining tailings in case of rupture of the structure during the de-characterization works. ECJ projects are subject to review and eventual approval by the authorities. In addition, the ECJ for Forquilha III was designed considering a hypothetical scenario of simultaneous failure of the Forquilha I, Forquilha II, Forquilha III and Forquilha IV dams. ECJ projects are subject to the review and eventual approval by the competent authorities.

To reduce human exposure to risks, Vale has been carrying out works to de-characterize the B3/B4 and Sul Superior dams with remotely controlled equipment. Finally, it is important to note that all of the company's dams undergo routine field inspections and are permanently monitored by Vale's Geotechnical Monitoring Center (CMG), including those that are part of the De-characterization Program.

Program evolution

Among the 30 structures contemplated, 7 had works completed by 2021. The dams that were de-characterized and reintegrated into the environment are:

8B (2019);
Dique Rio do Peixe (2020);
Dique 2 - Kalunga dam (2020);
Dique 3 - Kalunga dam (2020);
Pondes de Rejeitos - Igarapé Bahia dam (2020);
Fernandinho (2021);
Dique 5 - Pontal dam (2021).

The company expects to complete its Upstream Dam De-characterization Program in Brazil by 2035, according to the synthetic schedule below.

Schedule of the Upstream Dams Decharacterization Program in Brazil

1 For Diques 2, 3 and 4, the ECJ construction works are scheduled to start in 2022, with completion expected in 2023.
2 For the Vargem Grande dam, reinforcement works were completed.
3 For Sul Superior dam, preparatory activities began in 2020, while de-characterization activities await authority release to proceed.
Elimination of Upstream Dams per Year (unit)
1 Studies on the Dike 1A and Dique 1B structures led to a review of the solution adopted, with the assessment of new alternatives for de-characterization. Thus, the estimated deadline for completion of works was revised from 2023 to 2024.
2 The Grupo dam, at emergency level 2, needs complementary studies on impacts for the start of preliminary activities, in addition to greater care in the execution of the instrument maintenance plan. These conditions led to the postponement of the deadline for the end of the de-characterization, from 2024 to 2025.
3 The estimated completion date for the ED Vale das Cobras structure was revised from 2025 to 2027, in order to carry out additional drilling, extending the deadline for completing the engineering project. In the case of the ED Monjolo structure, the postponement of completion from 2025 to 2026 was due to the need for additional verification of information present in the As Is and De-characterization projects, for greater uniformity in the assumptions.

Vale emphasizes that the deadlines proposed above are based on the best information and techniques available at the time. They can be adjusted based on a relevant fact or condition that appears, in particular, related to the safety of the de-characterization process.

Resources for the de-characterization of upstream dams

Vale's Upstream Dam De-characterization Program has provisions recorded, as regularly disclosed in the Company's Financial Statements. As of December 31, 2021, Vale recorded:

  • An increase of US$ 1.7 billion in provisions, based on updated estimates for the overall cost of projects, which considered new engineering and geotechnical solutions, new risk management concepts, the use of remotely operated equipment and improvement of containment plans for certain dams.
  • A provision balance for the Program of US$ 3.523 billion reais, which excludes disbursements, exchange rate adjustments and present value accumulated in US$ 1.443 billion since 2019.

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