Responsibly managing waste from mining operations is essential, as is being transparent with our stakeholders about our tailings storage facilities (TSFs) and how we manage them. We engage with stakeholders throughout the lifecycle of our TSFs, from design to closure.
How we manage tailings
We work through technical committees and joint venture relationships to support leading practice in tailings management.
Our facilities are regulated, permitted and have been managed for many years to comply with local laws, regulations, permits, licences and other requirements. Tailings management has been included in the Group risk register since 2010, and our Group safety standard in place for tailings and water storage facilities has been in place since 2015. Our internal assurance processes verify that our managed TSFs operate in accordance with this standard, which we updated in 2020.
Our operational TSFs have emergency response plans – tested through training exercises in collaboration with stakeholders such as local emergency services – and follow strict business resilience and communications protocols.
There have been no external wall failures at our TSFs for more than 20 years.
In May 2021, we updated previously disclosed information on each of our TSFs. All facilities were assigned a consequence classification in accordance with the regulatory or industry body that oversees tailings in each region or jurisdiction. Additional technical data from updated downstream impact assessments, required under the GISTM and Rio Tinto’s internal standard for tailings and water storage facilities, resulted in a modification to hazard classifications of some facilities. Consequence classifications are not ratings of the condition of a facility or the likelihood of failure; instead, they rate the potential consequence if they were to fail.
Since the launch of GISTM in August 2020, we have continued work on our implementation plan. We completed a gap analysis against our internal tailings management, environment, and communities and social performance standards and developed improvement plans to close identified gaps. While COVID-19 pandemic restrictions delayed a few items, we plan to complete all outstanding actions as quickly as possible, while adhering to restrictions in each jurisdiction. We are on track to have all TSFs with a potential consequence rated “extreme” or “very high” in conformance with GISTM by August 2023, with all remaining facilities in conformance by August 2025.
We played an active role in the ICMM tailings working group in 2021, which focused on the development of the GISTM conformance protocol as well as a tailings good practice guide designed to help support industry-wide adoption.
In 2021, we also:
- Appointed Accountable Executives for tailings and established the Tailings Management Committee, which provides governance of tailings management practices across the Group to ensure we meet the GISTM and the relevant requirements of the Rio Tinto standard
- Updated our tailings disclosure information and released our updated D5 standard for the management of tailings and water storage facilities on our website in May 2021
- Published our tailings policy on our website in August 2021
- Published our Group-wide controls for tailings management in our centralised risk management system so that no matter where in the world our people are, controls relating to tailings can be consistently applied and verified
- Continued to support the Future Tails partnership, a collaboration between Rio Tinto, BHP and the University of Western Australia (UWA), launched the first micro-credentials, and enrolled the first cohort of more than 90 students for the Graduate Certificate in Tailings Management at UWA
What are tailings and how are they made?
Tailings are residues created as part of mining, refining, smelting and water treatment processes. These processes are never 100% efficient, nor is it possible to reclaim all reusable and expended processing chemicals. Tailings are discharged – normally as slurry – to a storage facility, where water is subsequently recovered and recycled back into the operation.
Tailings are mainly discharged in two ways. The first is to use below water approaches. The second is to use above water/above ground approaches. Tailings can be modified in other ways, such as:
Dewatering to a wet or dry cake that cannot be transported via a pipeline.
Includes dewatering until the tailings do not segregate.
Dewatering to form a high solids content slurry.
Tailings storage construction methods
Tailings storage is one of the biggest design decisions in the development of a mine. There are many factors which need to be considered in selecting the optimum site and construction method. Site conditions such as topography, rainfall, seismic activity, mineral characteristics and proximity to people dictate appropriate tailings sites, technology and storage solutions. The aim is to safely contain the tailings under any and all circumstances.
As a result, each tailings storage facility is unique. Depending on the environment and the chemical characteristics of the tailings the tailings impoundment may be lined, using a variety of lining systems which are designed to prevent impacts to surface and groundwater systems. As the tailings slurry is collected in the impoundment, the water separates from the heavier sand and silt particles and is collected at the surface. The tailings pond water is then recycled back into the operation for reuse and the tailings may be reclaimed so as to minimise the impact on the environment.
The construction method is important to ensure safe operation of a facility. Tailings storage facilities follow one of three wall construction designs, or hybrids of these. We also store tailings within some of our completed mining pits or in excavated or underground storage, which generally will not require the construction of the following dam wall options.
Upstream designs start with a free draining starter wall as the foundation. The tailings are then discharged into the dam, which then harden to form the foundation for the next level of wall. Ensuring water is properly removed and recycled is a crucial element of maintaining the structural integrity of the wall. These are suitable for facilities in areas of low rainfall, low seismic activity and relatively flat terrain.
Downstream designs start with an impervious starter wall unlike the upstream design that has a free draining starter wall. The tailings are then discharged into the dam and as the embankment is raised, the new wall is constructed and supported on top of the downstream slope of the previous section. This shifts the centreline of the top of the dam. The downstream design was developed for areas with seismic activity and high rainfall or water collection. A number of our facilities use the downstream construction method with a single embankment.
The centreline method is a hybrid of upstream and downstream designs. When the wall level is raised it is built on top of both the tailings and the existing wall. In contrast to the downstream design, the centreline remains the same throughout the subsequent raises.
Modified centreline construction is a centreline dam that is slightly raised using upstream construction. When the wall level is raised it is built on top of both the tailings and the existing wall, but slopes slightly upstream.
We take into consideration the specific conditions on each site before deciding on the appropriate tailings sites, technology and storage solutions.
An integrated approach to managing tailings facility risk
We have a structured approach to managing tailings facility risks, underpinned by our safety standard. There are three levels of governance and assurance that we apply to all facilities:
- First level of assurance takes place at the asset itself with the main tenets being effective facility design, comprehensive operational controls and regular reviews.
- Second level is assurance to the Rio Tinto Standard through periodic Business Conformance Audits and Technical Reviews. Business Conformance Audits are audits of a business or operation to assess conformance to our Health, Safety, Environment and Communities (HSEC) performance standards and Management System according to procedures and protocols established by HSEC.
- Third level of assurance is independent of site management and normally conducted by third parties. Our Internal Audit team works with external auditors to provide confidence that the systems for risk management, internal control and governance are adequate and effective.
All our managed facilities, whether active or inactive, have an external engineer of record or design engineer.
Group safety standard in place since 2015
We aim to protect the health and safety of people, the surrounding environment and conserve water in the best way we can, everywhere we operate. While all of our sites comply with laws, regulations, permits, licenses and regulatory requirements, in 2015, we went further by introducing a Group standard for all tailings and water storage facilities. This ensures all of our managed facilities operate in accordance with one standard.. In 2016, we joined the ICMM’s Tailings Working Committee, which conducted a tailings management review of its member companies. Our work helped inform the ICMM Position Statement, published in 2016, including the six elements of Tailings Storage Facility governance.
In 2020, we updated our Group standard and reviewed all our relevant standards to ensure they are well aligned with the new global industry standard on tailings management (GISTM).
Our Group standard is consistent with these six key elements:
Accountabilities, responsibilities and associated competencies are defined to support appropriate identification and management of TSF risks.
Risks associated with potential changes are assessed, controlled and communicated to avoid inadvertently compromising TSF integrity.
Processes are in place to recognise and respond to impending failure of TSFs and mitigate the potential impacts arising from a potentially catastrophic failure.
The financial and human resources needed to support continued TSF management and governance are maintained throughout a facility’s life cycle.
Internal and external review and assurance processes are in place so that controls for TSF risks can be comprehensively assessed and continually improved.
Risk management associated with TSFs includes risk identification, an appropriate control regime and the verification of control performance.
Exploring future opportunities
Recent enhancements to our tailings management approach
Since 2010, we have classified tailings management as a risk in the Group Risk Register. Rio Tinto has been part of the ICMM working committee since 2016.
We launched our Group safety standard for tailings in 2015; since then, we have made the following improvements to it:
- Mandated detailed control requirements to help consistently implement the Group standard
- Established the Surface Mining Centre of Excellence to provide technical expertise, ownership of the technical content of the Group standard and a second line of assurance by undertaking technical risk reviews for sites
- Appointed Nominated Managers and Qualified Site Representatives for tailings storage facilities, and high-risk water dams
- Nominated Managers are accountable for their site’s conformance to our standard for the management of tailings and water storage facilities
- Qualified Site Representatives are accountable for the day-to-day operations and monitoring of tailings facilities
- Responsible Dam Engineers provide technical support to the Nominated Manager to manage tailings and water storage facility risks
- Developed training modules on leading practices for safe tailings management for our tailings facility operators. Training is mandatory for the Nominated Roles
- Continue to ensure that all designs and major studies for operational tailings storage facilities are reviewed by our Surface Mining Centre of Excellence Tailings team as well as by an independent third party
- Updated our safety standard and procedure to ensure we continued to learn from and embed any tailings audit outcomes and include industry-leading practices
- Launched the Future Tails partnership with BHP and University of Western Australia in 2020 which includes training programmes to build talent and capability; publications that summarise state-of-the-art tailings analysis, design, operation and management; and research collaborations with industry to drive further innovation
Tailings management at our non-managed sites
All managed Rio Tinto joint ventures apply the Group Standard and Procedure. For our non-managed operational sites with tailings facilities, we actively participate in technical committees in an advisory capacity with our joint venture partners. Each of the technical committees has a Tailings Steering Committee, or equivalent, to support the effective management of tailings.