PT Freeport Indonesia operates a copper-gold mine located in the remote highlands of Papua, Indonesia, about 3500 km east of Jakarta. Currently, the district produces about 240 000 tonnes per day (tpd) of which about 45 000 tpd come from the DOZ Block Cave and the rest is mined from the Grasberg Open Pit. Over the next ten years, ore production from large block caves in the area is expected to reach about 200 000 tpd, replacing a large part of the production from the Grasberg Pit._x000D_
Block cave mining alters the hydrological characteristics of the area being mined and when the cave expresses itself at the surface in the form of subsidence, it increases the entrapment area for surface water. Operating a large block cave mine in a region with an average annual rainfall of 5500 mm in steep mountainous terrain and complex geological and hydrological features presents a challenging scenario for dewatering or depressurisation of the area. The high rainfall infiltration and entrapment in stacked mines operating within an essentially single orebody, coupled with the presence of fine-grained and clayey material within the draw points of the block cave, creates mud rushes or wet muck spills, which can endanger the personnel and interrupt production._x000D_
This paper outlines the problems caused by high water inflow into the DOZ Block Cave and the efforts undertaken to ensure the safety of the miners and continued achievement of desired production rates from underground mining in the district._x000D_
FORMAL CITATION:Syaifullah, T, Widijanto, E and Srikant, A, 2006._x000D_
Water issues in DOZ block cave mine, PT Freeport Indonesia, in Proceedings Water in Mining 2006, pp 361-368 (The Australasian Institute of Mining and Metallurgy: Melbourne).