Ok Tedi is a major open-pit copper-gold mine in the southern highlands near the western border of Papua New Guinea with Indonesian Papua. The pit is near oval-shaped and has a narrow north-south trending drainage slot at its southern end, is 3000m by 2000m in area at crest perimeter and 750m deep. By 2013, pit depth will be 900 m. About 150,000t to 200,000t of rock is mined daily; half this tonnage is ore. A 60m deep mini open-pit was mined during 2009–2010 within the southern slot to recover ore outside the current pit mining limit. Slope instabilities have existed on both sides of the slot for several years. Structurally controlled, raveling-sliding and toppling failures are active on the east and west slopes, respectively. Cumulative ground displacements in excess of 25m and 12m have been monitored on the two slopes since 2005. Trends and key factors influencing displacements and the strategy used to safely mine the mini-pit through the landslides are described in this paper.
Ok Tedi is a major open-pit copper-gold mine in the southern highlands of Papua New Guinea (PNG) within 15 km of the country's rugged western border with Indonesian Papua (Irian Jaya). Mining commenced in 1982 and the current pit will be fully mined by 2013. It may be possible to extend mine life by slope cutback and underground operations. Crest of the highest slope is near RL 2100 m. Although located in the tropics, daily temperatures are typically 12 to 20 deg Celsius. Adverse weather conditions persist. Clouds shroud the pit. Annual rainfall is 9 to 11m. PNG is a seismically active region but earthquake magnitudes are moderate (typically Richter 4 to 6) and those magnitudes likely to impact pit stability are infrequent (1 to 2 per year).