BHP has revealed that four of the dams it has built in Australia to store mining waste carry the highest possible risk classification under global standards, meaning any collapse of them would be catastrophic.
On Friday the miner told investors 32 of its 67 ‘tailing’ dams around the world that hold sometimes dangerous mining by-products were ‘high risk’ or worse under Canadian Dam Association dam safety classifications.
The classifications do not measure the stability of the dams or likelihood of them bursting, but rather estimate the hypothetical loss of life and damage to surrounding areas if a worst case scenario failure occurred with no controls in place.
Extreme risk, the worst of CDA’s classifications, means the potential loss of life exceeded 100 people and there would be major environmental, cultural, infrastructure and economic damage.
Australia is home to four of BHP’s five extreme risk dams. One at its Mt Whaleback iron ore mine in WA and three at its Olympic Dam mine in South Australia.
It also has two ‘very high’ risk dams at its Goonyella Riverside coal operation in Queensland and Nickel West nickel operation in Leinster, 300km north of Kalgoorlie.
The risk from the company’s Australian dams was to its employees and it is understood the company has taken it seriously enough to relocate employee offices at its Mt Whaleback mine.
Three extreme risk dams in joint ventures not operated by BHP were also identified in South America.
BHP’s extreme risk dams are all built using the upstream method, where dam walls are raised sequentially from the crest. It is the same method used in Vale’s Brumadinho dam in Brazil, which collapsed in January and killed more than 200 people. The disaster prompted the country to ban the method.
BHP was a joint venture partner with Vale at the Samarco mine in Brazil when a dam collapsed in 2015, killing 19 people and devastating the environment.
The taskforce was established in April and is headed by BHP’s former copper division health and safety boss Matthew Currie.
Mr Currie told investors Brumadinho strengthened its resolve to collaborate to eliminate tailings risk from our sector.
“The taskforce will be accountable for further enhancing our focus on tailings including the continued improvement and assurance for BHP’s global tailings storage facilities, progressing our technology efforts and leading ongoing participation in the setting of new international tailings management standards,” he said.
The taskforce is in the process of recruiting team members and working out a timeframe for action.
The company has conducted two reviews of its dams since 2016 and found “no immediate dam integrity concerns”, but it is taking precautions.
At BHP’s Pilbara iron ore mines it has temporarily relocated employees from offices currently in the ‘inundation zone’ while it looks at building a barrier to protect them.
A similar barrier is being engineered at Olympic Dam and emergency drills have been run to test the effectiveness of emergency evacuation and response.
A BHP spokeswoman said its Mount Whaleback mine in the Pilbara, the home of one of its extreme classified dams, had extensive controls in place.
“The structural integrity of the tailings dam wall at Whaleback was independently verified and found to meet international safety standards at the last comprehensive dam inspection in October 2018,” she said.
Earlier this year the International Council on Mining and Metals, an industry trade group including BHP, announced it would set new standards for tailings dam design and maintenance by the end of the year.
Originally published by Sydney Morning Herald.
- Speak to our team for a free demo of our Tailings Monitoring solution
- See how our solutions help manage industry stakeholder engagement and operator and regulator compliance requirements here
Don’t miss another update!