CONTROLLED RIVERINE TAILINGS MANAGEMENT
In 2018, PTFI produced approximately 63 million metric tons of tailings, which were managed using a controlled riverine tailings management system approved and permitted by the Government of Indonesia. PTFI’s controlled riverine tailings management system is implemented based on methods approved and permitted by the Government of Indonesia. The site-specific system, chosen after extensive evaluations of over a dozen alternatives, uses an unnavigable river to transport tailings out of the highlands (from approximately 3,000 meters elevation) to an engineered deposition area in the lowlands referred to as the ModADA. The river is not used for potable water, agriculture, fishing or other domestic or commercial uses, nor was it used for these purposes before operations began. Levees have been and continue to be constructed to laterally contain the footprint of the tailings and natural sediment within the ModADA while quantities of finer tailings and other sediments deposit in the estuary and the sea. Independent environmental management expert audits have reaffirmed the controlled riverine tailings management system is the best site-specific management alternative considering the topographical, seismic and geotechnical, geological, climatological and environmental conditions of the project area. If any conventional tailings system had been selected and implemented, it likely would have structurally failed by now.
In December 2018, Indonesia’s Ministry of Environment and Forestry (MOEF) issued a revised environmental permit to PTFI to address many of the operational activities that it alleged were inconsistent with earlier studies. The remaining sanctions are being resolved through adoption of revised practices and, in a few situations, PTFI has agreed with the MOEF on an appropriate multi-year work plan. PTFI and the MOEF also established a new framework for continuous improvement in environmental practices in PTFI’s operations, including initiatives that PTFI will pursue to increase tailings retention and to evaluate large scale beneficial uses of tailings within Indonesia.
The MOEF issued a new decree that incorporates various initiatives and studies to be completed by PTFI during 2019 targeting continuous improvement in a manner that would not impose new technical risks or significant long-term costs to PTFI’s operations. The new framework enables PTFI to maintain compliance with site-specific standards and provides for ongoing monitoring by the MOEF.
Data from biological sampling continue to demonstrate that the estuaries downstream of the tailings deposition area are functioning ecosystems, based on both the number of species and the number of specimens collected of nektonic, or free-swimming, organisms such as fish and shrimp. Large-scale demonstration reclamation projects show that several land-use options are possible after final closure of the deposition area.
In addition to internal and external audits and assessments, PTFI uses the ModADA Management Board (MMB) for oversight of the tailings system. The MMB is a multi-disciplinary expert panel that meets on site to assess system performance and risks associated with the ModADA and coastal zone area. The MMB focuses on the structural integrity of the levees and the geochemical stability of the deposition area, as well as associated stakeholder engagement. The MMB provides recommendations to PTFI leadership and engineering teams on priority activities and tracks progress on detailed recommendations. When mining is completed, this area can be reclaimed with natural vegetation or used for agriculture, forestry, grazing of livestock and aquaculture among other options, depending on stakeholder ambitions.
For more information on this topic, including our extensive biological monitoring system and beneficial use of tailings opportunities, please see the Controlled Riverine Tailings Management at PTFI summary document.