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Tailings

The tailings and waste rock (including overburden) that we produce represent our largest volume of waste. Managing these volumes produced in our mining operations presents significant environmental, safety and engineering challenges. In 2016, we produced approximately 204 million and 231 million metric tons of tailings and waste rock, respectively. The primary risks associated with managing waste rock stockpiles and tailings relate to structural stability, geochemistry, water quality and dust generation. Management of this waste is regulated in the jurisdictions where we operate, and our programs are designed to be in compliance with applicable national, state and local laws, permits and approved Environmental Impact Studies.

Freeport-McMoRan’s objective is to have zero catastrophic structural failures of tailings storage facilities (TSFs). We maintain an active and robust tailings management and stewardship program designed for continual improvement and assurance, currently operating 18 TSFs and managing 52 TSFs that are inactive or have been reclaimed. Our two newest TSFs – the Linga Tailings Dam at our Cerro Verde operation in Peru and the East-West Tailings Dam at our Morenci operation in Arizona are now fully operational. The Tailings Stewardship Program includes inspection and management processes associated with water dams and crush leach stockpiles.

At the operational level, qualified internal tailings-dedicated engineers and onsite leaders manage TSF stability. We employ qualified external Engineer(s) of Record (EoRs) for analyses, designs, inspections, and reviews for stability. We also follow established operations, maintenance and communication protocols. In this process, we regularly inspect and monitor phreatic level trends, deposition plans and adherence to good operational construction practices, water management controls, seepage management, decant systems and other stability components. In addition, we periodically review as-built conditions through field and laboratory geotechnical testing programs under the guidance of our EoRs.

Water balance management is incorporated with tailings management as a key driver of structural stability. Tailings engineers also coordinate with environmental experts on water quality management and closure planning associated with our TSFs. At TSFs located in arid regions, our tailings management program includes measures to reduce fugitive dust emissions from the surface of tailings impoundments and increase reclaimed water capture to reduce freshwater consumption. Our efforts to limit dust generation include the application of magnesium chloride, polymers, watering and wind fencing.

At the corporate level, we manage TSF stability through our Tailings Stewardship Program, which includes multiple levels of inspection and review. In the Americas, the Tailings Stewardship Team (TST), a multi-disciplinary group of internal and external experts, evaluates the design, operation and maintenance of TSFs to ensure that we are following and internally sharing good practices. The TST documents, prioritizes and tracks progress on recommended actions. The TST inspects all active and select inactive TSFs annually (including Cerro Verde in 2017). Inactive and closed TSFs are inspected on a site-specific schedule (every two, three, or four years). Our EoRs inspect our operating TSFs at least quarterly, and monthly in some cases. Our corporate tailings experts communicate frequently with all of our operations with TSFs and follow-up on recommended actions regularly. In 2016, our TST conducted annual field inspections at 17 active and 20 inactive TSFs. Sites have achieved 98 percent completion on TST recommended activities for TSFs (2004 to 2016).

Freeport-McMoRan has a critical controls management system in place. Focus areas progressing in 2017 include:

Governance systems

  • Formalized Terms of Reference for our internal and external engineers, and external engineering inspectors/reviewers
  • Formalized responsibility assignment for tailings operations and assurance
  • Strong internal accountability for resolving inspection/review recommendations
  • Technical support to site-based engineers from Corporate Technical Services’ Tailings & Water Group
  • Integrated life-cycle planning and management of tailings and water

Operations and surveillance systems

  • Monitoring and Action Plans with automated monitoring instrumentation
  • Training for engineers, superintendents, supervisors and operators
  • Standardized water and tailings accounting and reconciliation
  • TSF Emergency Action Plan integration with site-wide Crisis Management Plans

Operational critical control examples

  • Flood management requirements such as beach offset (freeboard)
  • Instrument thresholds compared to actual measurements for acceptable factors of safety for static drained, undrained and post-earthquake conditions
  • Mitigation measures, if needed, at any TSF may include enhanced drainage, buttress or increased water consumption

In the Americas, we also seek the advice of Technical Review Boards / External Tailings Review Boards (TRBs), composed of internationally recognized external experts retained by us, regarding our EoRs’ design and analysis, as well as our management of TSF stability. The TRBs provide a layer of assurance beyond our TST that our practices are in alignment with industry-leading TSF good practices. We utilize functioning Boards for all of our active TSFs in North America and South America and will be implementing Boards at certain inactive sites in the future.

The TSF failures at the Imperial Metals-owned Mount Polley Mine in British Columbia in 2014, and the Samarco Mineração S.A.-owned mine in Minas Gerais, Brazil, in 2015, were among the largest unplanned discharges of tailings in history, with significant loss of life, environmental and social impacts. We have studied the published investigation and technical panel reports related to these failures. Our TSFs have been reviewed by internal and external experts to confirm that processes and systems are well aligned with resulting recommendations.

We participated in the ICMM Tailings Working Group and support the ICMM Position statement on preventing catastrophic failure of tailings storage facilities published in December 2016. Freeport-McMoRan utilizes all elements of the Tailings Governance Framework: accountability, responsibility, and competency; planning and resourcing; risk management; change management; emergency preparedness and response; and review and assurance.

We continued to enhance our programs and documentation around TSF governance and management systems during 2016. We clarified essential functions and associated roles and responsibilities for TSF planning, operations, surveillance, oversight and improvements. This effort included drafting competency requirements for tailings engineers and managers.

Regarding our operations, surveillance, and critical controls systems, we have implemented a Key Performance Indicator Dashboard for internal communication between multiple levels of operations, engineering, and management as a minimum standard for all active operations’ surveillance activities. Example topics include beach width, freeboard, embankment material quality, and status of completing recommendations made by the site engineer, EoR, TST, and TRB.

During 2017, we are drafting an “umbrella” TSF Framework Management document that connects all of the associated programs and procedures together for more effective internal communications. We will also begin a pilot of mobile data entry and visualization platforms for inspections and operational data. Among other enhancements, we are also continuing to implement training tools and identifying opportunities for strengthening technical resources at our operations.

Our Tailings Stewardship Program, though our Water Stewardship Team (WST), inspects our higher-hazard water dams annually (relative to smaller or lower consequence dams) and oversees actions to address associated recommendations.

Our Tailings Stewardship Program, though our TST, also reviews and inspects our engineered crushed leach stockpiles annually, oversees actions to address recommendations, and provides site engineers tools similar to those developed for our TSFs.

We manage waste rock and overburden in stockpiles for possible future mineral recovery, reclamation or other projects. These stockpiles are regularly monitored and evaluated for structural stability in accordance with local seismic design criteria.



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