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The Ok Tedi environmental disaster caused severe harm to the environment along of the Ok Tedi River and the Fly River in the Western Province of Papua New Guinea between about 1984 and 2013. The lives of 50,000 people have been disrupted. One of the worst environmental disasters caused by humans, it is a consequence of the discharge of about two billion tons of untreated mining waste into the Ok Tedi from the Ok Tedi Mine, an open pit mine in the Western Province of Papua New Guinea. This mining pollution, due to the collapse of the Ok Tedi tailings dam system in 1984 and the lack of a proper waste retention facility, was the subject of class action litigation, naming Ok Tedi Mining Limited and BHP Billiton and brought by local landowners. Villagers downstream from Ok Tedi in the Fly River system in the Middle Fly District and the southern and central areas of the North Fly District, in particular, believe that the effect on their livelihood from this disaster far outweighs the benefits they have received from the mine's presence in their area. ==Environmental impact== In 1999, BHP reported that 90 million tons of mine waste was annually discharged into the river for more than ten years and destroyed downstream villages, agriculture and fisheries. Mine wastes were deposited along of the Ok Tedi and the Fly River below its confluence with the Ok Tedi, and over an area of . BHP's CEO, Paul Anderson, said that the Ok Tedi Mine was "not compatible with our environmental values and the company should never have become involved." , mine operators continued to discharge 80 million tons of tailings, overburden and mine-induced erosion into the river system each year. About of forest has died or is under stress. As many as may eventually be harmed, an area equal to the U.S. state of Rhode Island or the Danish island of Funen. Following heavy rainfall, mine tailings are swept into the surrounding rain forest, swamps and creeks, and have left behind 30 square kilometers of dead forest. Thick gray sludge from the mine is visible throughout the Fly River system, although its effects downriver are not as severe. Chemicals from the tailings killed or contaminated fish, although they are still eaten by the people of the surrounding villages. However, fish counts decrease closer to the mine. The massive amount of mine-derived waste dumped into the river exceeded its carrying capacity. This dumping resulted in the river bed being raised 10 m, causing a relatively deep and slow river to become shallower and develop rapids, thereby disrupting indigenous transportation routes. Flooding, caused by the raised riverbed, left a thick layer of contaminated mud on the flood plain among plantations of taro, bananas and sago palm that are the staples of the local diet. About 1300 square kilometers were damaged in this way. The concentration of copper in the water is about 30 times above the standard level, but it is below the World Health Organisation (WHO) standards. The original plans included an Environmental Impact Statement that required a tailings dam be built. This would allow heavy metals and solid particles to settle, before releasing the clean ‘high-water’ into the river system where remaining contaminants would be diluted. In 1984 an earthquake caused the half built dam to collapse. The company continued operations without the dam, initially because BHP argued that it would be too expensive to rebuild it. Subsequently, the PNG government decided a dam wasn’t necessary, in the wake of the closure of the Panguna mine. Most of Papua New Guinea's land is held under a system of native title, with ownership divided amongst many small clans, while the central government retains control over how resources that lie under the ground are used. There are no waste retention facilities on the premises. This allowed all ore processing residues, waste rock and overburden to be discharged into the Ok Tedi River. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Ok Tedi environmental disaster」の詳細全文を読む スポンサード リンク
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