The largest quantity of waste generated at our mining operations is tailings, which is finely ground natural rock residue and water from the processing of mineralized ore.

Tailings at all of our operations worldwide are managed by the best site-specific technology achievable. At the majority of locations this involves impounding the tailings within engineered and monitored dams, known as Tailings Storage Facilities (TSFs). Company-wide, we manage 72 TSFs, 15 of which are active and 57 of which are inactive or have been fully reclaimed.

North and South America

In North and South America, through our Tailings Stewardship Program, we pursue the application of best practices in the operation and monitoring of TSFs to ensure regulatory compliance and proper closure. The Stewardship team is comprised of company management, technical experts and operators along with technical expert consultants. The team conducts detailed field and data audits of each operation’s active TSFs at least every two years to identify any areas of concern, to ensure compliance and to make recommendations for improvements.

TSFs are regulated under governmental authority and regulations that vary by locality and site-specific conditions of each operation. The company is also developing and implementing state-of-the-art conservation techniques for improving water reclamation from TSFs. This is being done by reducing evaporative losses and improving recovery of water discharged to the TSFs from processing, effectively reducing the overall water consumption by our operations. By reducing fresh water requirements for ore processing, we are increasing sustainability of water resources for our operations and the surrounding communities.

Reclamation of tailings dams and impoundments is an ongoing process at existing operations that have filled impoundments. All proposed TSFs fully include closure and reclamation in their designs. Reclamation of TSFs can include grading surfaces to have mild slopes and capping the tops to control dust, erosion and water quality, and to provide geotechnical stability. Long-term water quality programs are established and monitored to meet closure requirements.

Indonesia

An exception to the use of TSFs is our operation in Papua, where site-specific topography, seismic activity and annual rainfall in excess of 30 feet require alternative management of tailings. Since the beginning of operations at PT Freeport Indonesia in the early 1970s, a highland river originating in the mill area has been designated for the transport of tailings and naturally occurring river sediment to the lowlands. Located there is a tailings management area in the lowlands and coastal zone, engineered and managed for the deposition and control of tailings between two levees. The tailings deposition system is operated under PT Freeport Indonesia’s comprehensive tailings management plan, approved by the Government of Indonesia during the 1997 AMDAL process (environmental and social impact study). Independent environmental audits since that time continue to confirm that this is the only feasible option given site-specific conditions.

The large size of the containment area (230 square kilometers), which is open at the lower end of the levees to allow the large amounts of rainfall to exit the area, presents more potential for exposure to tailings than at facilities with enclosed TSFs. Consequently, as part of the Government of Indonesia AMDAL process, we also submitted in 2002 to the Government of Indonesia a more detailed Environmental Risk Assessment of the tailings management system. This assessment found that the identified environmental impacts of PT Freeport Indonesia’s tailings management system were consistent with those predicted in the original AMDAL: mainly that tailings are not toxic to people, terrestrial or aquatic flora and fauna, and that the effects of sedimentation in the estuaries are reversible after tailings deposition ceases. Nevertheless, this aspect of the operation is one of the major focal points of the extensive Environmental Management System, as well as a major topic of dialogue by critics of the operation. PT Freeport Indonesia continues to work with various national and international experts to ensure that its tailings management represents best practice, considering the applicable geotechnical, geochemical, topographical, climatological, seismic and hydrological conditions.

Hundreds of thousands of mangroves have been planted as part of an assisted mangrove colonization program in the Ajkwa Estuary, one aspect of the tailings management program for the Grasberg operation in Papua, Indonesia.

 

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