5.2.3 Waste and tailings

The most significant output materials of Gold Fields’ operations are tailings, waste rock, chemical waste and hydrocarbon waste, all of which are responsibly managed. Gold mining requires large volumes of blasting agents, hydrochloric acid, lime, cyanide, cement and caustic soda (sodium hydroxide), all of which it uses on an ongoing basis. Of these, cyanide represents the most potentially hazardous substance. All Gold Fields’ operations, except Cerro Corona, are fully compliant with the requirements of the International Cyanide Management Code (ICMC). Cerro Corona produces ore concentrate and does not require ICMC certification. ICMC certification also extends to Gold Fields’ transport providers.

All Gold Fields’ operations have tailings management plans in place, including closure and post-closure management plans. All TSFs and associated pipeline and pumping infrastructure are subject to ISO 14001 certification, external tailings audits, as well as regular inspection and formal annual reporting. TSFs are also subject to Group-wide inspection by independent experts at least once every three years – or more frequently where required by local circumstances or regulations.

Gold Fields’ last Group-wide TSF audit was conducted in 2014, which included all 15 operational and 10 dormant TSFs, by an independent, expert consultancy and found that all facilities were wellmanaged and were either already aligned with global good practice, or have plans in place for alignment. The audit found that the Gold Fields TSFs were within the top quartile of industry leading practice in terms of design, operation, and management.

In response to the recent high profile tailings dam failures at Mount Polley (4 August 2014) and Samarco (5 November 2015), which have resulted in increased scrutiny of the industry’s tailings management practices, the ICMM initiated a global review of TSF standards and critical control processes across its member companies. Gold Fields CEO Nick Holland is acting as the CEO sponsor for the review and Gold Fields also chairs the member company working-group. Gold Fields is committed to implementing any additional measures to improve TSF management that may emanate from the review.

To date Gold Fields has applied the following measures at its operations to minimise the risks posed by TSFs to the environment, which include:

  • Pollution containment facilities to capture run-off water from the TSF surfaces, together with solution trenches to capture shallow groundwater seepage
  • Recycling systems to allow the reuse of tailings water in metallurgical processes
  • Monitoring of groundwater plume quality and migration (where applicable) and, where pollution is detected, installing measures to contain plumes
  • Planting vegetation, installing netting and applying chemical suppressants on slope faces to control dust and erosion

More broadly, Gold Fields is taking proactive steps to anticipate constraints relating to the development of future TSFs and the replacement of existing ones. Production activities are dependent on a mine having sufficient TSF capacity. Securing new TSF capacity can involve lengthy permitting processes with local environmental agencies – and can also require negotiations with local communities.

Group mining waste
(million tonnes)
Group mining waste

In 2015, the Group took the following steps to ensure that its operations continued to enjoy a sustainable TSF pipeline to support future production:

  • In Australia, our St Ives mine received final environmental approval from the regulator for the proposed Leviathan in-pit tailings facility, which is expected to realise around A$50 million (US$37 million) in savings for tailings facility construction and closure liabilities over the life-of-mine. In addition, operational cost reductions are estimated to total up to A$5 million (US$3.7 million) a year. Construction started in Q1 2016
  • In 2014, Gold Fields concluded lengthy negotiations with the EPA over the development of future TSFs at Tarkwa. This resulted in Gold Fields securing formal, written permission to raise two of the existing TSFs at Tarkwa (TSF1 and TSF2). During 2015, the wall raise at TSF1 was completed, while construction at TSF2 is nearing completion. These extensions will provide the mine with adequate tailings capacity for the next two years. TSF3 has been earmarked for closure in 2017. These three
  • Planting vegetation, installing netting and applying chemical suppressants on slope faces to control dust and erosion TSFs currently provide the mine with capacity for tailings storage of 13.5 million tonnes per annum
  • To cater for its longer-term production profile Tarkwa has been in talks with the EPA about two new TSFs – TSF5 and TSF6. In late 2015 the mine received verbal go-ahead for site clearing and preparation of TSF5. This work commenced in January 2016, while the environmental review and approval processes are ongoing. TSF 6 is in pre-feasibility stage
  • During 2015, Damang completed the wall raising at the East TSF, which will provide adequate capacity until 2017. A decision to commission the new Far East TSF will depend on the current investigation into the mine’s longer-term operational future.
  • At Cerro Corona the Las Tomas spring was relocated to allow for the expansion of the TSF after the relevant approvals were received. An audit by the regulator in August 2015 found that the relocation had been carried out in line with the approvals requirements

Meanwhile, both underground and open-pit operations produce substantial volumes of waste rock. This is kept in managed waste rock dumps, which are subject to comprehensive rehabilitation through the application of cover material, usually topsoil and vegetation, once they are no longer in use.

South Deep commenced the removal of the old South Shaft waste rock dump in early 2015. While tailings output was stable, there was an increase in waste rock across the Group largely due to increased stripping at the Invincible, Neptune and A5 open pits at St Ives.