Miami Ave Tailings removal

Reducing TSF failure risks and impacts

Enhancing protection for our people, communities and the environment

As an industry, we constantly seek to challenge safety standards to protect our people, the environment and the communities where we operate. The management of tailings is no exception. Our aspiration is zero harm from tailings and we continue to work with others and share progress to make this a reality.

We evaluate all of our 72 operated tailings storage facilities (TSF) in line with the Canadian Dam Association (CDA) Safety Guidelines to assess the consequences of potential failure at each. This includes active facilities, inactive or closed facilities and acquired legacy facilities at our operated assets.

Under our Risk Framework, the potential impacts of our TSF failure risks are estimated by assuming the hypothetical, most significant failure of each TSF, without regard to probability, and also assuming that all risk controls are ineffective. Once assessed, our focus is on preventing or reducing the likelihood of a TSF failure and aiming to eliminate the potential impacts to people, communities and the environment in the unlikely event a failure was to occur.

Two projects that demonstrate our ongoing work to significantly reduce the risk of TSF failure and any potential impacts are:

  • the construction of a waste rock buttress at our Nickel West Leinster operation in Western Australia
  • the relocation of tailings at the Miami Avenue TSF at our legacy asset in Arizona, United States

Both projects significantly reduce the potential impacts by reducing the likelihood of the risk, removing people from the potential area of impact if there is a TSF failure event or by removing the hazard altogether.

Reclassification of Nickel West Leinster TSF 2/3, Western Australia

The TSF 2/3 at our Leinster Nickel West site in Western Australia has been in operation since 1992. Since 2017, waste rock buttresses have been constructed along the perimeter embankments to improve safety, with additional buttressing completed in FY2021. This has reduced the risk of failure and resulted in a reclassification of the TSF from ‘very high’ down to a ‘significant’ classification under the CDA guidelines.

Relocating tailings in Miami, Arizona, United States

The Miami Avenue Tailings project involved the relocation of approximately 0.3 Mm3 of legacy tailings that were deposited from historic copper mining activities between 1920–21. Although the facility had remained inactive since that time and was stable for many years, it carried a CDA classification of ‘extreme’ due to the potential for seismically induced runout to impact the nearby community of Miami.

Our Risk Framework requires review of risks and controls periodically, including those relating to legacy tailings, and is designed to ensure our management of risk is dynamic and responsive to changes in internal and external environments. In January 2019, we reassessed the risk of a seismically induced runout failure at the site and identified further actions that could be taken to reduce the risk associated with the facility. As a result, the tailings were relocated to a nearby depression in the interior of the mine site. To facilitate a safe and transparent removals process, we worked closely with the local community and external stakeholders and, with relocation completed in FY2021, the TSF failure risk associated with those tailings has been eliminated. As a result, the site classification has decreased from ‘extreme’ to ‘low’.