14 September 2020
The safety of our people and the communities in which we operate always comes first and managing our material safety risks is key. The failure of a tailings storage facility (TSF) is one of the most material risks at our operations.
We evaluate all 70 operated TSFs in line with the Canadian Dam Association (CDA) Safety Guidelines to assess the potential failure consequence at each. This includes our active facilities, closed facilities and acquired legacy facilities that BHP operates.
Under our Risk Framework, we estimate the potential impacts of our TSF failure risks by assuming the hypothetical, most significant failure of each TSF without regard to probability and assuming that all risk controls are ineffective. Once assessed, our focus is on preventing or reducing the likelihood of a TSF failure, as well as aiming to eliminate the potential impacts to people and the environment in the event of a failure. As part of this, we identify opportunities to improve controls that have been designed to prevent or reduce the likelihood of a TSF failure occurring. We also identify opportunities to improve mitigating controls; including actions that could be taken to reduce the potential impacts of a TSF failure should one occur.
Two examples of our work to reduce the risk of safety impacts to our people and nearby communities include the construction of a barrier at Newman Operations in Western Australia and, within our legacy assets, the work towards relocation of tailings from the Miami Avenue Tailings Project in Miami, Arizona.
Both projects significantly reduce the potential impact risk to people by removing the hazard, reducing its likelihood or removing people from the potential area of impact if there is a TSF failure event. The Miami Avenue Tailings Project will eventually eliminate the risk of a TSF failure at this facility.
Newman Operations Barrier
At Newman Operations (formerly Mount Whaleback) in the Pilbara region of Western Australia, operations have relied upon a TSF since the mid-1980s. The facility contains about 17,500,000 m3 of tailings. Early last year, we began a program of work to improve safety and reduce the potential impacts of a TSF failure at the operation. The most significant part of this program was the construction of a barrier between the TSF and the main processing hub.
The work was completed in two stages: the first phase reduced the facility’s CDA classification from ‘Extreme’ to ‘Very High’ (June 2019), and the second phase reduced the CDA classification further to ‘High’ (June 2020). A continued program of work around improvement of TSF stewardship remains a priority to us and is designed to support further improvements to tailings safety management at the facility.
Relocating tailings in Miami, Arizona
The Miami Avenue Tailings Project involves the relocation of legacy tailings from historic underground copper mining activities. Located in Miami, Arizona, BHP’s Miami Unit mine was acquired by BHP in the mid-1990s and the Miami Ave TSF has been inactive for over 90 years. This facility contains about 360,000 m3 of tailings, deposited between 1920 and 1921. While stable for many years, this facility has a CDA rating of ‘Extreme’ due to its proximity to the former copper boom town of Miami.
Our Risk Framework requires us to review risks and controls periodically. In January 2019, we reassessed the risk of a TSF failure at Miami Avenue and decided to eliminate the risk by relocating the tailings to a nearby depression on the interior of the mine site. This in turn will remove the risk of safety impacts to people in the potential impact zone. Logistics planning was completed in FY2020 and tailings relocation commenced soon after.
The removal of the tailings is expected to be completed at the end of 2020, eliminating the TSF failure risk from this facility. BHP has worked closely with the local community and external stakeholders to ensure a safe and transparent removals process.