The OK Tedi mine has been a three stage process: the mining and processing of the gold enriched cap from 1984 to 1986, the extraction of both gold and copper from the copper rich base from 1986 to 1988 and the extraction of largely copper (with small quantities of gold and silver) from 1988 to the present.OK Tedi is an open pit operation where up to 80,000 tonnes of ore and 152,000 tonnes of overburden are mined each day. The mining lease was granted in 1981 for 21 years with the right of renewal for a further 21 years. A small volume of tailings was retained in the Interim Tailings Scheme near the mill in the early years of operations. Since then, and with approval from the State, tailings have been discharged directly into the Ok Tedi and Fly River systems. An alternative tailings treatment was not feasible because of the unstable terrain, geological formations and very high rainfall of the region. Ok Tedi Mining Limited (OTML), the current operators of the mine, is planning for an orderly closure of the mine in 2013. However OTML is in the process of undertaking a feasibility study to extend the mine life by another 7 years until 2020 by a combination of underground and an open pit mining.