Brazil’s Samarco mining firm has pledged to pay at least $260 million in reparations for the environmental damage caused by the bursting of two dams two weeks ago.
Signing a “preliminary commitment”, Samarco has sought to guarantee payment for preventative mitigation, repair or compensation measures in agreement with the state prosecution service.
BHP Billiton managing director Andrew Mackenzie made a public apology for the joint venture operation's dam bursting, which killed at least six people and left 22 missing.
“Everyone at BHP Billiton has been deeply affected by the terrible incident at the Samarco mineral operation in Minas Gerais in Brazil. We remain filled with sadness and concern for the community there. I travelled to the region last week with Jimmy Wilson, the president of Iron Ore,” Mackenzie said.
“The devastation that we witnessed around the site and in the community was quite heartbreaking. It was important for us to go there to learn more about the situation and best to understand how BHP Billiton can help both now and over the longer term.”
Scientists say the sediment, which may contain chemicals used by the mine to reduce iron ore impurities, could alter the course of streams as they harden, reduce oxygen levels in the water and diminish the fertility of riverbanks and farmland where floodwater passed.
Researchers are testing the river water and results should be published over the coming weeks, giving a better idea of the contents of the mining waste.
One cause for concern is that compounds known as ether amines could have been used at the mine to separate silica from the iron ore, in order to produce a better quality product.
The Rio Doce valley in Minas Gerais has a long history of mining. But the state is also the country’s foremost producer of coffee and milk. South of the disaster, mineral spas are a leading tourist attraction. In recent years, the area has been plagued by both flooding and drought, which are both exacerbated by the mine-related damming.
Mackenzie said BHP was committed to the Samarco investment for the long term but acknowledged the ability to continue mining was not certain.
The company was in the process of raising the dam wall, which authorities said was cheaper than replacing it. The state is investigating whether the reservoir was too full when the beach occurred.
According to mining industry research and scientific literature published in recent years, the compounds are commonly used at Brazilian mines, including Samarco's.