SUSTAINABILITY Tailings management

Tailings management

As at end-2022, our 11 operations (including our two non-managed JVs: Asanko in Ghana and Far Southeast in the Philippines) have 38 TSFs, of which 12 are active. Of the active TSFs, we have two in-pit TSFs – at Agnew and St Ives – six downstream/centre-line TSFs and four upstream TSFs. In addition, two TSFs are under construction – a new upstream-raised TSF at Granny Smith and a new filtered stack at Salares Norte. Our 2030 ESG target is to reduce the number of upstream-raised TSFs to three. To this end, we started converting two upstream-raised TSFs to downstreamraised TSFs at Tarkwa.

Our Australian and South African mines are in relatively dry regions and have limited stored supernatant water. The Tarkwa, Damang and Asanko TSFs in Ghana are designed to cope with exceptionally high seasonal rainfalls. We implemented critical controls and performance objectives to ensure TSF embankments remain stable over the life of the facilities. We appointed independent review boards at Tarkwa and Cerro Corona because their TSFs have “extreme” or “very high” Global Industry Standard on Tailings Management (GISTM) consequence category ratings. Our technical teams continue to work with Galiano Gold, which manages Asanko, to maintain the sound operational performance of its lined and downstream-raised TSFs. Salares Norte’s TSF will be a filtered stack dam and will be commissioned in H1 2024, soon after the mine starts operating.

The Far Southeast (FSE) TSF in the Philippines is well managed, with no visible signs of instability. The facility has freeboard available to contain up to a one-in-500-year flood event. However, the TSF is in a region prone to high seismic activity and typhoons. Gold Fields and Lepanto Consolidated Mining commissioned external consultants for a more reliable understanding of the risk profile and to develop potential risk control concepts to improve the facility’s risk profile. Gold Fields is currently reviewing its interest in FSE.

A detailed profile of Gold Fields’ TSFs can be found on our website at www.goldfields. com/environment-tsf.php

Global Industry Standard on Tailings Management

Gold Fields and other ICMM members committed to conform all TSFs with “extreme” or “very high” consequence category ratings with the GISTM by August 2023, based on internal selfassessments. All our other tailings facilities that are not in a state of safe closure will conform with the GISTM by August 2025. We have appointed Accountable Executives and Responsible Tailings Facility Engineers as required by the GISTM.

We completed internal self-assessments against the ICMM Conformance Protocols for Tarkwa and Cerro Corona, our two priority sites. A final assessment is due in June 2023. ERM, a third-party consultancy, will verify the internal self-assessment outcomes after August 2023. As an important part of our GISTM work, we engage with communities close to TSFs on emergency preparedness, among others.

The Global Tailings Management Institute

In January 2023, on the fourth anniversary of the Brumadinho Tailings dam disaster (which resulted in the deaths of 270 people), the United Nations Environment Programme and investors representing the Principles for Responsible Investment announced the formation of the Global Tailings Management Institute (GTMI). The GTMI aims to drive and implement mining industry safety standards related to TSFs. A multi-stakeholder advisory panel (which included the ICMM) developed the standards. Gold Fields was one of two mining companies representing the ICMM on the panel.

Once operational, the GTMI will be central to the independent auditing the GISTM requires companies to undergo.

TSF governance and technical work

Independent parties conduct external audits on our active TSFs every three years. We also commission third parties to review operational and legal aspects and sustainable development at the TSFs every three years. The most recent round of audits was carried out in Q1 2023 and findings are due later in 2023. The audits were a gap analysis to assess whether sites conform to the newly released Gold Fields TSF Standard (finalised in Q4 2022). The standard covers 10 topic areas with a detailed monitoring and surveillance requirements section.

We retain an Engineer of Record (EoR) and independent technical reviewers for all active Gold Fields-managed sites. A qualified external engineer fills the EoR role, supported by their consulting engineering company. 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 Board maintains a high level of oversight of the Group’s TSFs by reviewing quarterly TSF management reports and overseeing external and independent monitoring verification. We continue to further improve TSFs’ operational safety – including, where practical, considering filtered tailings (currently being installed at Salares Norte), commingling, improved water management and in-pit tailings disposal. The ICMM considers these initiatives in its work to improve critical TSF controls and reduce tailings water content.

Gold Fields has 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
  • Setting minimum requirements for tailings surveillance
  • Ensuring cross-discipline interaction for every TSF design or modification
Industry collaboration

Gold Fields actively engages with the industry on this subject. We have engaged in the following projects and initiatives:

  • AMIRA P1217 research project, which investigates tailings instrumentation and monitoring technologies
  • GeoStable Consortium, which was formed with our peers to investigate the commingling of tailings and waste rock
  • ICMM Tailings Management Working Group, which works with members to adopt a more proactive approach to tailings management