Tailings material in breached Brazilian dams significantly less than estimates

Staff writer ▼ | January 9, 2016

Samarco MineraÃ§Ã£o has provided further information on the recovery and response effort following the breach of its FundÃ£o tailings dam and SantarÃ©m water dam in Minas Gerais, Brazil.

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Samarco has reported findings from ongoing mapping of the Rio Doce. A study carried out in early December by ACQUA Consultoria has found fish, individuals and shoals, living in the river.

Using sonar techniques, the team studied a 670 kilometre stretch between the mouth of the Rio Doce and Risoleta Neves hydropower plant (Candonga dam).

They were able to detect fish living in areas affected by the turbidity plume as well as in unaffected tributaries of the Rio Doce. Further monitoring studies will be carried out to determine the identity of the species present.

Samarco confirmed in its 60-day update that satellite assessments showed the volume of tailings material released during the dam breach was approximately 32 million cubic metres. Approximately 85 percent of the released tailings were retained within 85 kilometres of the FundÃ£o dam.

The amount of tailings released is therefore significantly less than some initial estimates which were in excess of 50 million cubic metres.

Furthermore, Samarco has undertaken several activities to stabilise the released tailings and prevent more material from entering the Rio Doce system. These include the construction of dikes to contain tailings and revegetation along the Gualaxo and Doce rivers.

The native revegetation is intended to reduce the risk of erosion in heavy rainfall.

Dredging of the Candonga hydroelectric dam is planned which will also improve water quality.

Samarco reports that work to repair and reinforce the Selinha dike above the FundÃ£o dam in the Germano complex is complete. Samarco confirms it is continuing to reinforce the SantarÃ©m water dam which overflowed, but which retained some of the tailings from FundÃ£o.

Reports issued by the companies responsible for water supply in the affected municipalities along Rio Doce confirm the water treatment facilities along the Rio Doce are operational and capable of treating water for human consumption and industrial and agricultural use.

Work is also being performed by a number of organisations, including Samarco, SAAE, Copasa, water supply companies and local councils to control any ongoing impacts to hydroelectric power plants from turbidity and sediment accumulation. ■

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Tailings material in breached Brazilian dams significantly less than estimates

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