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Tailings storage facilities risk management

BHP uses the ‘three lines of defence’ model of risk governance and management to define the relationships and clarify the roles of different teams across the organisation in managing risk. Our approach to tailing storage facility (TSF) risk management at our operated assets is aligned with our standard approach to risk management, assurance and continuous improvement.

Our first line operations personnel own the risks and are required to implement controls designed to reduce the likelihood and impact of a TSF failure. Our second line functions, primarily the Tailings Taskforce, Technical Centre of Excellence and the Risk team, set the global standards that apply to our management of TSF risks. For example, our second line sets mandatory minimum performance requirements for the management of TSF failure risks and defines Key Risk Indicators (KRIs) to help monitor performance against our risk appetite. The second line supports the first line and verifies risk management activities, including by conducting reviews and other assurance activities to identify opportunities to improve understanding and management of TSF failure risks. Our Internal Audit and Advisory team then provides independent assurance as the third line, which may include auditing the effectiveness of the global standards and their application to TSF failure risks.

Dam Selection and Design

A key dimension to maintaining dam integrity is dam selection and design. The basis of dam design is guided by design criteria specified through the Australian National Committee on Large Dams (ANCOLD), Canadian Dam Association (CDA) or local regulation, taking account of dam classification. Quality assurance and quality control across all construction phases of dam lifts/expansions during operation, change management (identifying, assessing and mitigating the impacts of any changes on dam design and integrity), and subsequent construction is also critical to maintaining dam integrity.

Operation Surveillance and Maintenance

Central to our approach is the recognition that maintaining TSF integrity is an ongoing process of continuous assessment that needs to be maintained for the life (including into closure) of each TSF. Operation, surveillance, maintenance, effective monitoring and review practices must operate in line with TSF design requirements and be quality assured and controlled to ensure the TSF is functioning as intended.

Key roles

Effective governance of our TSFs requires all of the above elements – from change management to document management to appropriately qualified personnel with clear accountabilities – to be encompassed.

We have three key first line roles that we mandate across our operated assets:

  • Dam Owner – the single point of accountability for maintaining effective governance and integrity of the TSF throughout its life-cycle
  • Responsible Dam Engineer – a suitably qualified BHP individual accountable for maintaining overall engineering stewardship of the facility including planning, operation, surveillance and maintenance
  • Engineer of Record – an individual external to BHP who is a suitably qualified professional engineer retained by the Dam Owner for the purpose of maintaining dam design, certifying dam integrity and supporting the Dam Owner and the Responsible Dam Engineer on any other matters of a technical nature

As explained below, some TSFs also have independent Tailings Review or Stewardship Boards to strengthen the control environment for TSF risks. BHP assesses the dam classification, risk, and operational circumstances in determining whether to empanel a Tailings Review or Stewardship Board. Not all facilities will have a Tailings Review or Stewardship Board; we have them in place (or are in the process of establishing them) for all our operated assets with ‘very high’ or ‘extreme’ classified tailings facilities.

Surveillance

Given TSFs are dynamic structures, effective monitoring, surveillance and review is central to ongoing dam integrity and governance. These processes span six dimensions with the specific details commensurate with the significance of the facility:

    1. Monitoring systems: operating in real time or periodically
    2. Routine surveillance: undertaken by operators
    3. Dam inspections: more detailed inspections undertaken periodically by the Responsible Dam Engineer
    4. Dam Safety Inspections: annual inspections undertaken by the external Engineer of Record reviewing aspects across both dam integrity and governance
    5. Dam Safety Reviews: conducted by an external third party as described below
    6. Tailings Review or Stewardship Boards: a panel of qualified independent individuals established, commensurate with dam significance, under specific terms of reference to review aspects such as the current status of the dam; any proposed design changes and outcomes of any inspections or Dam Safety Reviews  

Dam Safety Reviews

Dam Safety Reviews are central to our approach to TSF integrity and continuous improvement. We undertake Dam Safety Reviews consistent with the guidance provided by the Canadian Dam Association (CDA) in its 2016 Technical Bulletin Dam Safety Reviews. As per this guidance, review frequency is informed by the dam classification under CDA.

Dam Safety Reviews are detailed processes that include a review of dam integrity and dam governance. They include a review of the dam break assessment and dam consequence classification. The review is led by an external Qualified Professional Engineer, who has the appropriate level of education, training and experience, with support and input from other technical specialists from fields that may include, for example, hydrology, geochemistry, seismicity, geotechnical and mechanical. At the conclusion of the review, the Qualified Professional Engineer is required to sign an assurance statement that includes a comment as to the integrity of the facility as a result of the review.

Emergency Preparedness and Response

The final key element in our approach to TSF risk management is emergency preparedness and response.

Our approach to emergency response planning for our TSFs is designed to be commensurate with risk and includes:

  • identifying and monitoring for conditions and thresholds that prompt preventive or remedial action
  • assessing and mapping the potential impacts from a hypothetical, significant failure including impacts to infrastructure, communities and environment, both within and outside the mine site, regardless of probability
  • establishing procedures to assist operations personnel responding to emergency conditions at the dam
  • testing and training in emergency preparedness ranging from desktop exercises to full-scale simulations. Desktop and field drills are scheduled at a frequency commensurate with the level of risk of the facility
  • engaging, testing and integrating our emergency response plans with external authorities, including conducting coordinated drills to ensure readiness and transparency

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