Tailings Storage Facilities Management
Tailings dams are dynamic structures and maintaining dam integrity requires consideration of a range of factors including appropriate engineering design, quality construction, ongoing operating discipline and effective governance processes. As a result, BHP’s approach to dam risk management at our operated dams is integrated into our standard approach to risk management, assurance and continuous improvement, with particular focus on four key areas:
- Maintenance of dam integrity;
- Governance of dam facilities;
- Monitoring, surveillance and review; and
- Emergency preparedness and response.
Supporting this approach to dam risk management at our operations are Group-level, company-wide processes of technical support and oversight.
Maintenance of dam integrity
Central to our approach is the recognition that maintaining dam integrity is an ongoing process of continuous assessment that needs to be maintained for the life (including into closure) of a tailings facility. As a result, we have identified five key dimensions to maintaining dam integrity:
- Design: the basis of dam design is guided by design criteria specified through ANCOLD, CDA and local regulation, taking account of dam classification;
- Construction: quality assurance and quality control across all construction phases (from initial construction to dam lifts / expansions during operation);
- Operations and maintenance: operating and maintaining the dam in accordance with its design requirements;
- Change management: identifying, assessing and mitigating the impacts of any changes on dam design and integrity; and
- Monitoring, surveillance and review: ensuring the dam is functioning as intended.
Governance of dam facilities
Effective governance encompasses a range of aspects from change management to document management to appropriately qualified personnel with clear accountabilities.
We have three key roles that we mandate across our operated assets
- Dam Owner – the single point of accountability for maintaining effective governance and integrity of the Tailing Storage Facility 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; and
- Engineer of Record - an independent, 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.
Note: 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 Tailings Review or Stewardship Boards, which are either in place or in the process of being established for BHP-operated Assets with Very High and Extreme classified tailings facilities.
Monitoring, surveillance and review
Given tailings dams 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 Dam Engineer;
- Dam Safety inspections: annual inspections undertaken by the external Engineer of Record reviewing aspects across both dam integrity and governance;
- Dam Safety Reviews: conducted by an external third party as set out below; and
- 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 dam integrity and continuous improvement. We undertake Dam Safety Reviews consistent with the guidance provided by the Canadian Dam Association in their 2016 Technical Bulletin Dam Safety Reviews. As per this guidance, review frequency is informed by the dam classification.
Dam Safety Reviews are detailed processes that include a thorough 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 which 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 dam risk management is emergency preparedness and response. Our approach to emergency response planning for our tailings facilities 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 infrastructure, communities and environment, both on and offsite, regardless of probability;
- Establishing procedures to assist operations personnel responding to emergency conditions at the dam; and
- Testing and training in emergency preparedness ranging from desktop exercises to full-scale simulations. Desk top and field drills are scheduled at a frequency commensurate with the level of risk of the facility.
BHP has established a Tailings Taskforce, which is accountable for the continued improvement and assurance for BHP’s operated tailings storage facilities, progressing our technology efforts and leading ongoing participation in the setting of new international tailings management standards.
Working with industry
BHP welcomes a common, international and independent body to oversee integrity of construction and operation of all tailings storage facilities across the industry. We also support calls for greater transparency in tailings management disclosure and will work with the industry to make sure the disclosure is consistently applied and informs better tailings dam stewardship.
BHP has 67 operated tailings facilities across our operated sites.
Thirteen operated facilities are active, 12 of which are in Australia and one in Chile.
At our non-operated joint ventures there are nine facilities.
Note: The number of tailings facilities is calculated based on the definition agreed by the International Council on Mining and Metals Tailings Advisory Group in response to the Church of England information request, which differs to the definition applied to our February disclosure. We keep this definition under review. The reduction in number of facilities in this disclosure compared to the February disclosure is primarily due to the aggregation of individual dams into (integrated) facilities. The majority of these changes are associated with the North American Closed Sites.
Tailings Facilities Disclosure
In April 2019, the Church of England Pensions Board and the Council on Ethics Swedish National Pension Funds wrote to approximately 700 mining firms to request specific disclosures of their tailings facilities.
BHP is committed to improving the transparency of information about tailings facilities, and is working with the ICMM and other relevant organisations to pursue improvements in global tailings management practices.
As part of this commitment, we have responded to the Church of England Pensions Board and the Council on Ethics Swedish National Pensions Funds’ request.
Read BHP’s full response here.
For more information also refer to our ESG briefing on tailings dams here.