water ptfi tailingsPT-FI operates a controlled riverine tailings management system, which was implemented based on methods approved and permitted by the Indonesia government. Tailings are transported from the concentrating facility along with water and a small quantity of concentrating reagents. Reagents added as part of the concentrating process have been demonstrated to dissipate within a short distance of the concentrating facility.

The controlled riverine tailings management system at PT-FI uses an unnavigable river to transport the tailings from the concentrator in the Highlands along with natural sediments to a large engineered and managed deposition area in the Lowlands, called the Modified Ajkwa Deposition Area or ModADA. The river is not used for potable water, agriculture, fishing or other domestic or commercial uses. Levees have been constructed on both sides of the ModADA to laterally contain the depositional footprint of the tailings and natural sediment within the designated area. Quantities of finer tailings and other sediments deposit in the estuary and the sea to the south.

Independent, environmental management expert audits have reaffirmed that this system is the best site-specific management alternative, given the topographical, seismic and geotechnical, geological, climatological and environmental conditions of the area. It has been in service for more than 20 years and has performed reliably, safely, and in line with initial design plans. A large-scale conventional style tailings dam would not be safe, stable or effective.


 PT-FI maintains an extensive environmental management and monitoring program to assess the potential current and future environmental impacts from its controlled riverine tailings system. PT-FI to spends approximately $100 million annually to manage and monitor the controlled system.

A multi-disciplinary, multi-department team routinely measures surface and groundwater quality, air quality, and biological, hydrological, sediment, and meteorological characteristics of the entire operations area. PT-FI collects around 15,000 samples for analysis annually (based on a five-year average), using the results to develop the scientific information needed to make informed management decisions about system performance with a focus on eliminating, minimizing, or mitigating environmental impacts.

To support this effort, PT-FI established the Timika Environmental Laboratory or TEL in the mid-1990s, located within our operational area in the Lowlands town of Timika. The lab is certified to ISO 17025 quality standards by the Indonesian National Accreditation Committee and serves as the main analytical lab for sample analyses used in our monitoring programs. TEL is registered with the MoEF as a Referenced Environmental Laboratory.

Impacts of the tailings management system, including increases in sedimentation, were predicted in numerous studies and are consistent with the design and operation approved and permitted by the government of Indonesia. Monitoring results continue to indicate the environmental impacts of the tailings deposition are reversible at the end of the mine’s life, except for elevation changes. Large-scale demonstration reclamation projects show that several land use options will be possible after final closure of the deposition area.