Another Tailings Dam Bursts
Tragically, it’s happened again. Another tailings dam has failed at an iron mining operation in Brazil. This time it’s Vale’s Corrego do Feijão mine near Brumadinho. The death toll is staggering. Our hearts and prayers are with the families of the iron ore miners in Minas Gerais and all the people who suffered a loss.
From an engineering standpoint, this is totally unacceptable. The environmental impact this time is not as severe as the Samarco collapse near Mariana in 2015, when satellites tracked an orange plume through Brazil’s countryside until it eventually fouled the Atlantic Ocean, but it’s a major environmental calamity nonetheless.
Another difference between this event and other past tailings dam failures is that this one has been captured on video. And, it’s scary. The video basically shows a tailings tsunami erupting from the base of the dam and quickly wiping out the surface facilities at the mine, including a cantina where many miners were reportedly eating lunch. They had seconds to react. This video should be mandatory viewing for every mining engineer and geotechnical engineer, especially those building tailings dams. Earthen dams are designed to transmit liquid. When an earthen dam contains too much liquid, it runs the risk of failure by liquefaction. Investigators found liquefaction to be a part of the cause for the Samarco failure. Vale has had a little more than three years to get its house in order. With what has happened now, Vale will have a hard time convincing Brazilians it was taking dam safety seriously.
The blame game is in full swing. The media is reporting that independent inspectors from TÜV SÜD do Brasil had warned Vale that faulty water drainage and monitoring systems at the Feijão dam represented a serious risk. A report submitted prior to the incident, according to local media, said the inspectors could not properly assess the dam’s stability because they were unable to accurately monitor water levels and drainage, but they signed off on it anyway. TÜV SÜD do Brasil certified the dam as stable in September 2018. After the collapse, three Vale employees and two TÜV SÜD do Brasil engineers were arrested and later released.
Based in Munich, Germany, TÜV SÜD is an independent inspection/auditing firm and Europeans associate its symbol with quality work. In 2013, it purchased Bureau de Projetos e Consultoria Ltda., a Brazilian engineering firm that focused on environmental management services for the rehabilitation of industrial lands. Immediately after the incident, the management board and supervisory board for TÜV SÜD initiated extensive investigations, which are ongoing.
At the same time, Korn Ferry, an international consulting company, working with Vale’s Board of Directors has appointed former Minister of the Federal Supreme Court Dr. Ellen Gracie as chairperson of its Extraordinary Independent Consulting Committee for Investigation (CIAEA). Vale established the CIAEA to determine the causes and potential responsibilities for the Feijão breach. Separately, Vale announced it has retained counsel and that law firm has assembled four outside experts who will provide an assessment of the technical causes of the rupture.
Tragic events like these can bankrupt a mining company. Vale was the fourth largest mining company based on its market capitalization prior to this incident. For Brazil, all mining represents about 2% of its gross domestic product and iron ore revenues amount to about $2.3 billion annually. Vale is a large rural employer. The people of Brazil are already weighing the value of those jobs against its costs in lives and environmental damage. Only time will tell how this plays out.
Steve Fiscor, Publisher & Editor-in-Chief, E&MJ