The catastrophic failure of the Vale tailings dam in Brazil, the second in three years, is a test for worldwide mining industry. Such tailing dams are some of the largest structures in the world with failure rates one hundred times greater than for water retention dams and the risks of failure are growing in time.
Such dams are meant to last for ever, so the initial design, the maintenance, the regulatory and inspection regimes are critical, even many decades after a mine has closed. If lessons are to be learned from Brumadinho, it is that regulation matters and that the regulators must not end up being ‘captured’ by those they seek to regulate.
In Peru the regulatory authority is OSINERGMIN which comes under the Ministry of Energy and Mines (MINEM) which is, in turn, the entity responsible for accelerating the development of mining.
The Vale dam that failed used the ‘upstream’ construction method which is known to be the least reliable of three tailing dam construction methods and is particularly suspect in earthquake zones. In Minas Gerais state legislature, there had been failed attempts to forbid this construction method. It should, however, be noted that Peru, Chile and others have for a long time banned the use of the ‘upstream’ method.
The UN and others have called for an impartial investigation into the collapse in Brazil, since it raises serious questions as to the stability of tailings dams elsewhere.