We employ a strong governance model based on the MAC (Mining Association of Canada) guidelines for TSFs. Our global tailings stewardship programme employs three types of audit – in-house at site level, in-house at corporate level, and a third, entirely independent audit – and these are aimed at providing a ‘triple check’ of our TSFs against our corporate standard and international guidelines (including ANCOLD, MAC and CDA).
Following the Feijão accident, our particular focus was on Serra Azul, where our TSF is the only one in our portfolio that uses an upstream ‘wet’ dam construction. The TSF had been dormant since 2012 and possesses significantly lower moisture content than that reported for the Feijão TSF. Applying early concerns from the Feijão TSF failure, we stress-tested the Serra Azul dam model safety factors. Consequently, we decided to err on the side of caution and evacuate the local community downstream of the dam, enabling us to carry out further testing and safely implement any mitigation measures.
This is a disruption to the community, for which we are sorry, but we are convinced that it has been the right thing to do and we are working hard to ensure we look after the needs of those affected. After moving households located within approximately 5km from the dam into hotels, we set up an emergency response plan to look after their livestock and business assets, and to ensure the children have continued access to education. By March 2019, a phased plan to rehouse the families has begun, following international best practice.
We are currently reviewing our approach to decommissioning the Serra Azul TSF to maximise safety.
Our tailings transition plan
Across all our TSFs, we have developed an approach to optimise their safety.
- No new wet tailings dams.
- Accelerate the use of non-wet disposal such as thickened paste tailings or dry stack tailings options where possible. We already employ this approach in Mexico and Brazil iron ore mines.
- Optimise the use of radar and satellite monitoring to heighten the sensitivity of remote monitoring and enable transparent access to this data.
These three principles are underpinned by our strong TSF governance system.