BHP Billiton says waste from dam burst less than initially thought

BHP Billiton said on Friday that the amount of mining waste spilled as a result of the dam burst at its Samarco joint venture iron ore mine in Brazil last November was a lot less than previously thought.

Samarco estimated that the volume of tailings material released during the dam breach was around 32m cubic metres, with approximately 85% of the released tailings retained within 85km of the Fundao dam.

The number is significantly lower than some of the initial estimates which were in excess of 50m cubic metres.

In addition, Samarco has undertaken a number of measures to stabilise the released tailings and prevent more material from entering the Rio Doce system, including the construction of dikes to contain tailings and revegetation along the Gualaxo and Doce rivers.

Dredging of the Candonga hydroelectric dam is planned in order to improve water quality.

At 0837 GMT, BHP shares up 1.8% to 684.30p.