Minas Gerais sets out tailings dam decommissioning rules

Southeast Brazil’s Minas Gerais state is tightening regulations on tailings dams in an effort to avoid further tragedies like the two that have affected the state in recent years. 

The state published a decree setting out obligations for companies to classify dams according to risk, along with decommissioning of existing structures and emergency works, among other issues.

"This classification is important so that the state system for the environment and water resources (Sisema) can establish inspection and monitoring priorities, focusing on those dams that represent greater potential for environmental and social damage," the state government said in a release. 

Minas Gerais was the scene of the two worst mining tragedies in Brazil's history, caused by the collapse of tailings dams, one in Mariana in 2015 and the second in 2019 in Brumadinho.

Due to decades of intense mining, mainly for iron ore, companies operating in Minas Gerais need to dig deeper and deeper to extract good quality ore, creating large mountains of tailings. 

Those tailings dams must be decommissioned by February 2022. 

"The closure of the structures must be accompanied by the removal of the associated infrastructure and, for this, some rules need to be followed. These include eliminating or reducing the entry of surface and groundwater into the reservoir and adopting measures to ensure the long-term physical, chemical and biological stability of the structures that remain in place," the government said.

"In addition, there should be monitoring for the period necessary to verify the effectiveness of the decommissioning."