Vale concludes the decommissioning of the first of nine upstream damsNov, 27, 2019 Posted by Sylvia Schandert
Vale completed the decommissioning works of the first of the nine upstream dams announced on January 29. Located at the Águas Claras Mine in Nova Lima, 8B began its works on May 17. The goal is that in the next three years all are decommissioned or have the appropriate safety factors, without offering risk to communities and municipalities located below the structures and the environment.
In addition to 8B, the decommissioning project includes the Sul Superior dams (Barão de Cocais); Vargem Grande (Nova Lima); Fernandinho (Nova Lima); B3/B4 (Nova Lima); Group (Ouro Preto), and Forquilhas I, II, and III (Ouro Preto). In some structures downstream containment barriers are being built to enhance safety in the event of breakage. The decommissioning and containment works are budgeted at R$8.6bn.
The works to eliminate the dam characteristics carried out at 8B consisted of removing the elevation that was supported by sediments and constructing a central channel with stones to allow the natural flow of surface water. Before the work began, which generated a total of 160 direct jobs, all the surface water in the reservoir was removed by pumping. To form the rockfill in the central channel and where the bus was located, it was necessary to lay about 50,000 tons of stones.
According to Carlos Miana, Executive Manager of the Decommissioning Project, the main challenge faced in the work was the safe transportation of a large volume of stones to 8B (located inside the Águas Claras Mine) and lifting out the sediment removed from the dam. “From the stockyard to the dam, it’s almost 4 km from a narrow, curvy, steep downhill dirt road. Thanks to constant driver awareness and strict safety controls, we have been able to complete the works, even working day and night, without any accident,” informs Miana.
The dam area is also being revegetated, which will allow a faster reintegration into the environment. A vegetable blanket was applied in an area of 12,700 m2 and 1,000 seedlings of native species of Mata do Jambreiro were planted, a permanent protection reserve preserved by Vale where it was located at 8B. The structure had a Declaration of Stability Condition (DCE) and had no alert level, so workers could access the dam without any restrictions.
With the conclusion of the works, the processes of formalization of the decommissioning are being initiated with the state agencies and the National Mining Agency.
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