Lihir gold mine in Papua New Guinea is located on Lihir Island, which has deep offshore waters. During the Lihir project feasibility study, a detailed risk analysis and environmental impact assessment of all available options for waste storage and/or disposal was conducted.

These studies revealed that land disposal was unsuitable for social, environmental and economic reasons. They confirmed that the most suitable method of disposing tailings and waste rock was into the ocean, rather than conventional on-land storage dams.

As a result, tailing is now discharged through an underwater pipeline at a 125-metre water depth. The tailing continues to descend rapidly beyond the pipeline, eventually settling on the seabed at depths of between 900 metres and 2,000 metres.

Waste rock is disposed by barges in designated disposal zones that have depths in excess of 100 metres. These zones are located above steep submarine canyons, down which the rock descends. The waste rock mixes with the tailings and settles on the ocean floor.

The mine has a minimal impact on the quality of the island's water. In fact, both company and the PNG Government Office of Environment and Conservation (OEC) results continue to show that Lihir has maintained water quality standards better than standards set by the Government.

Lihir is in the process of setting up a collaborative programme with other mining companies to establish an industry code for deep sea tailings disposal - design, use and monitoring. A major focus of the code will be to provide technical information on where in the world DSTP is appropriate, how DSTP works and minimum requirements for feasibility studies, operations and on-going monitoring.

Alongside the code development programme the company is undertaking a research programme with independent scientific experts to address some of the issues in relation to DSTP impacts on the marine ecosystem.

More information

Department of Environment & Conservation:
Statement on environmental performance and compliance

Australian Institute of Marine Science:
Method to measure coral response to sediment stress

Deakin University are undertaking a research project on the tailings chemistry at Lihir. More