SUSTAINABILITY Tailing and waste management

Tailings and waste management

At the end of 2021, our 11 operations (including our three JV sites: Asanko in Ghana, Gruyere in Australia and Far Southeast in the Philippines) contained 37 TSFs, of which 13 TSFs were active and one was under construction. Of the active TSFs, we have two in-pit TSFs – at Agnew and St Ives – six downstream/centre-line TSFs and five upstream TSFs. In line with our ESG-related commitments, we aim to reduce the number of upstream-raised TSFs from five to three by 2030.

Our mines in Australia and South Africa are located in relatively dry regions, with limited amounts of supernatant water stored in the facilities. In Ghana, the Tarkwa, Damang and Asanko TSFs are designed to cope with exceptionally high seasonal rainfalls. We implemented critical controls and performance objectives to ensure TSF embankments remain stable throughout the wet and dry seasons and over the life of the facilities. We also appointed independent review boards at Tarkwa and Cerro Corona. Our technical teams continue to work with Galiano Gold, who manages Asanko, to maintain the good operational performance of the lined and downstream-raised TSF. The Salares Norte TSF, a filtered dry-stack dam, will be commissioned in H1 2023.

In the Philippines, the FSE TSF is well managed with no visible signs of instability. In addition, the facility has freeboard available to contain up to a 1:500 year flood event. However, the TSF is located in a region prone to high seismic activity and frequent typhoons. As a result, Gold Fields and Lepanto Consolidated Mining commissioned external consultants to develop a more reliable understanding of the current risk profile and potential risk control concepts that could further improve the facility's risk profile. These studies are now complete, and an independent summary report was produced that presents a clear and concise record of the study components' findings.

Global Industry Standard on Tailings Management

After the Brumadinho tailings tragedy in January 2019, ICMM members, the UN Environment Programme and the UN Principles for Responsible Investment established an independent panel of experts to develop a new international standard relating to TSFs. As a result of this process, the GISTM was launched on 5 August 2020 as the first global standard on tailings management applicable to existing and future TSFs. The GISTM strengthens current mining industry practices by integrating social, environmental, local economic and technical considerations. The standard covers the entire TSF lifecycle – from project conception to post-closure.

Gold Fields and other ICMM members have committed that all TSFs with "extreme" or "very high" consequence category ratings will comply with the GISTM by August 2023. All other tailings facilities we operate that are not in a state of safe closure will comply with the GISTM by August 2025. Soon after the launch, we commenced a detailed site-specific gap analysis of each Gold Fields-managed TSF against the new standard to identify gaps and confirm our conformance roadmap. This work is complete, and we are in the process of closing all gaps identified. Further to this, we also appointed new Gold Fields' GISTM-specific roles, being the Accountable Executives (AEs) and Responsible Tailings Facility Engineers (RTFEs).

Internal self-assessments against the ICMM Conformance Protocols for our two priority sites (Tarkwa and Cerro Corona) are planned for H1 2022, which will be carried out with the relevant TSF Engineers of Record (EoRs). In addition, we are also considering external verification of conformance for Q1 2023, prior to the ICMM conformance deadlines.

Tailings storage facility governance and technical work

All Gold Fields' active TSFs are subject to an independent, external audit every three years. Furthermore, a comprehensive third-party review covering operational, legal aspects and sustainable development is carried out at the TSFs in three-yearly intervals. The next round of audits is due in Q1 2023. This review is also used to check the operations' ongoing compliance against the Group TSF Management Guideline and applicable design guidelines.

Facilities with an "extreme" consequence category rating must have this third-party operational review carried out annually. Gold Fields is in the process of transitioning its TSF Management Guideline to a standard to incorporate the requirements of the GISTM and the lessons learned from a variety of TSF-related incidents over the past few years. This draft standard was also benchmarked against other guidelines and standards developed by our industry peers.

We retain an EoR for all of our active Gold Fields-managed sites. The role of the EoR is filled by a suitably qualified external engineer, supported by the consulting engineering company they work for. EoRs are responsible for reviewing and approving all engineering and design data, associated operating and monitoring procedures, as-built drawings and facility inspections to confirm physical integrity, safety and ancillary structures' performance.

The Gold Fields Board continued to employ a high level of oversight of the Group's TSFs by maintaining quarterly TSF management board reporting, progressive implementation of real-time environmental and geotechnical monitoring instruments and increased external and independent monitoring verification. In addition, we continue with our programme to further improve the operational safety of the TSFs – including, where practical, consideration of filtered and dry-stacked tailings (currently being installed at Salares Norte), co-disposal, improved water management and in-pit tailings disposal. These initiatives are also the subject of work at the ICMM to improve critical TSF controls and reduce tailings water content.

Gold Fields has progressively implemented several technical improvements at its TSFs, including:

  • Considering leading practice assessments of static and seismic liquefaction
  • Installing real-time information monitoring and database storage systems
  • Minimum requirements for tailings surveillance
  • Cross-discipline interaction for every TSF design or modification

Process plant tailings waste and waste rock, or mineralised waste, are two of the most significant by-products of mines. By responsibly managing these waste streams, we can minimise their impact on the environment and our host communities.

In terms of general waste, we have an internal target to limit general or non-hazardous waste generated for disposal at landfill sites to 2015 levels, which totalled 11.2kt. In 2021, we generated 1.2kt in hazardous waste, and 10.2kt in non-hazardous waste for disposal, thus achieving our annual target. Gold Fields recycled 63% of all non-mineralised waste generated in 2021, compared with 60% in 2020. Wastes such as plastic, scrap metal, oils and hydrocarbons are recycled off-site by specialist recyclers.

Group mining waste Tailing dam

Tailings dam at our Damang mine, Ghana