Tailings storage facilities risk management
BHP uses the ‘three lines model’ of risk governance and management to define roles of different teams across the organisation in managing risk. This sets clear accountabilities for risk management and provides appropriate ‘checks and balances’ to support us in protecting and growing value. Our approach to TSF failure risk management at our operated assets is aligned with our standard approach to risk management, assurance and continuous improvement.
Under this model, the first line is provided by our frontline staff, operational management and people in functional roles – anyone who makes decisions, deploys resources or contributes to an outcome is responsible for identifying and managing the associated risks. Our first line operational personnel and management own the TSF failure risks and implement controls designed to reduce the likelihood and potential impacts of a failure.
Our second line functions, primarily the Tailings Excellence team, Resource Centre of Excellence and the Risk team, are responsible for providing expertise, support, monitoring and challenge on risk-related matters including by defining mandatory minimum performance requirements for the management of TSF failure risks. The second line supports the first line and is responsible for verifying risk management activities by conducting reviews and other assurance activities to help identify opportunities to improve understanding and management of TSF failure risks.
The third line, our Internal Audit and Advisory team, is responsible for providing independent and objective assurance over the control environment (governance, risk management and internal controls) to the Board and our Executive Leadership Team. This may include, for example, auditing the effectiveness of mandatory minimum performance requirements and their application to TSF failure risks. Additional assurance may also be provided by external providers, such as our external auditor.
The outcomes and actions resulting from the activities at each line are required to be documented, monitored, actioned and communicated on a regular basis to the relevant asset personnel, Executive Leadership Team members and the Board’s committees through operational and governance processes. Our approach to TSF failure risk management at operated assets is multi-dimensional encompassing both management of controls and governance. The key elements of this are:
- maintenance of dam integrity
- operation, surveillance and maintenance
- emergency preparedness and response
- TSF governance and standards
- Group-level oversight and assurance
Maintenance of dam integrity
Where feasible, we will try to avoid implementing new conventional TSFs by using other options such as filtering or in-pit design. When we must use a TSF, a key dimension to maintaining dam integrity is dam selection and design. The basis of dam design is guided by performance and design criteria specified by the GISTM, the Australian National Committee on Large Dams (ANCOLD), 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 are 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 post 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.
Our mandatory minimum performance requirements for TSFs are designed to ensure data and records are maintained and accessible at all stages of the TSF lifecycle.
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:
- Monitoring systems – operating in real time or periodically
- Routine surveillance – undertaken by operators
- Dam inspections – more detailed inspections undertaken periodically by the Responsible Tailings Facility Engineer
- Dam Safety Inspections – annual inspections undertaken by the external Engineer of Record reviewing aspects across both TSF integrity and governance
- Dam Safety Reviews (DSRs) – conducted by an external third party as described below
- 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 DSRs
Dam Safety Reviews
DSRs are central to our approach to TSF integrity and continuous improvement. We undertake DSRs consistent with the guidance provided by the CDA in its 2016 Technical Bulletin Dam Safety Reviews. As per this guidance, review frequency is informed by the dam classification under CDA.
DSRs are detailed processes that involve 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 such as 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.
Emergency preparedness and response
The preceding steps of our approach seek to prevent TSF failure risk and this third key element is mitigation; through robust emergency preparedness and response we aim to minimise the potential impacts in the unlikely event that a TSF failure was to occur.
Our approach to emergency response planning for our TSFs is designed to be commensurate with the level of risk and includes:
- defined roles and responsibilities of response teams in the end-to-end process
- 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
- engaging with community stakeholders to maintain a shared state of readiness
Tailings storage facilities governance and standards
In addition to the above-mentioned elements and appropriate change management, effective governance of our TSFs also requires accountabilities to be clearly defined and appropriately qualified personnel appointed to key governance roles.
There are three key first-line roles which 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 Tailings Facility 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 TSF design, certifying TSF integrity and supporting the Dam Owner and the Responsible Tailings Facility Engineer on any other matters of a technical nature
In accordance with the GISTM, we have defined our Accountable Executive (AE) positions, who are direct reports of the BHP Chief Executive Officer and answerable to the BHP Board’s Sustainability Committee. The AE roles include an AE accountable for the Group-wide TSF governance framework, and AEs accountable for the safety of TSFs including avoiding or minimising the potential environmental and social impacts of a TSF failure, tailings management training and emergency preparedness and response. They will have regular communication with TSF operational and technical employees monitored through a combination of KRIs, tailings management training, and for emergency preparedness and response.
TSFs may also have Independent Tailings Review or Stewardship Boards to strengthen the control environment for TSF failure 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; they are in place (or are in the process of being established) for all our operated assets with ‘very high’ or ‘extreme’ consequence classified facilities. For the facilities where a board is not required, independent, senior technical reviewers will act in this capacity.
Additional detail on our approach to TSF standards and Group-level oversight and assurance is detailed above in our journey to date.
For more information on how our Board of Directors is committed to safe management of TSFs, emergency preparedness and response, recovery in the unlikely event of a failure, and transparency see our BHP TSF Policy Statement.
Reducing TSF failure and impacts
We evaluate all 72 operated TSFs in line with the Canadian Dam Association (CDA) Safety Guidelines to assess the potential failure consequence at each.