Tailings management involves addressing risks such as the potential consequences of a tailings storage facility failure to our workforce and communities, increased fresh water use in mine production due to water losses in tailings management, and groundwater impact due to seepage.
Following the failure of Samarco’s Fundão tailings dam on 5 November 2015 (see page 19 of the 2018 Sustainability Report), we have sought to enhance our tailings management governance and risk assessment processes.
Following that event, BHP completed Dam Risk Reviews for active, inactive and closed tailings storage facilities across our business. These reviews included a thorough evaluation of risks, and identified no significant deficiencies to the stability or management of our tailings storage facilities.
The risk reviews also highlighted new opportunities to improve the design, construction and operation of our facilities. In total, more than 400 actions were assigned to BHP Assets. These actions are 93 per cent complete, with the remaining actions considered low priority such as administrative actions and long-lead items regarding closure and climate change impacts. None of these actions is overdue.
Dam Safety Reviews were then completed across BHP following the guidelines recommended by the Canadian Dam Association (CDA) – widely regarded as the most rigorous in the industry.
Monitoring and alarm systems at all sites were reviewed, and supplemented where new opportunities to improve were identified. All significant tailings storage facilities have emergency response plans in place.
As part of our ongoing process of continuous improvement, external Dam Safety Inspections are conducted annually and risk-based Dam Safety Reviews every three to seven years, in line with CDA guidelines.
BHP’s tailings storage facilities are located at seven operated sites in Australia and Chile, with a further seven closed sites throughout North America, and four non-operated joint ventures in North America and South America.
We have a number of facility designs within our portfolio, and we have an assurance process in place that seeks to identify and manage the risks associated with each.
The design of a tailings storage facility is influenced by many factors including proximity to employees, communities, infrastructure and other sensitive areas, the geological conditions on which it is constructed, climatic and seismic factors and tailings deposition and characteristics.
In total, there are 115 tailings storage facilities across these sites (including non-operated joint ventures) of which 20 are active. In total, 47 of these storage facilities have been constructed using the upstream method, of which 13 are active.
Those 13 operational upstream tailings storage facilities are located at the following operated sites: one at Mt Whaleback (Western Australia), two at Olympic Dam (South Australia), two at Goonyella and one at Blackwater (Queensland), and seven at Nickel West (Western Australia).
We have 26 upstream facilities at our closed sites in North America, and a further eight inactive upstream facilities at our operated sites.
The number of tailings storage facilities is calculated based on the classification by the Responsible Dam Engineers at our sites. We keep this definition under review.
Improvements to the governance process for our dams include:
- a centralised function within our Resource Engineering Centre of Excellence;
- appointment of Dam Owners for all facilities and Responsible Dam Engineers for high-risk facilities and most other water dams. Responsible Dam Engineers are accountable for coordinating all tailings management activities and Dam Owners provide a single point of accountability for tailings management;
- appointment of external Engineers of Record for all facilities;
- development of internal governance procedures covering all activities related to the management of active, inactive or closed tailings storage facilities.
The establishment of independent Tailings Stewardship Boards to undertake reviews for active and many inactive and closed tailings dams including design, construction, operation and closure is underway to provide independent third party input. A trial of the stewardship program has been completed at our Olympic Dam asset in South Australia.
An important component of the program is providing site-specific training for Dam Owners, Responsible Dam Engineers and key operational personnel on a regular basis. We have also established an internal Tailings Working Group to share best practice across the business.
Our focus for FY2019 is on:
- finalising development of internal governance procedures;
- completing implementation of the stewardship program for active and some inactive and closed tailings storage facilities and high-risk water dams;
- working closely with universities and other organisations on advancing new monitoring and dewatering technologies.
Progress has been made in working with vendors on testing, development and application of advanced tailings dewatering methods.
BHP is operating tailings dewatering equipment at two of our Queensland Coal operations, and funded the trial of a tailings filter press at our Escondida asset in Chile to evaluate performance.