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The TVA Kingston Fossil Plant coal fly ash slurry spill occurred just before 1 a.m. on Monday December 22, 2008, when an ash dike ruptured at an solid waste containment area at the Tennessee Valley Authority's Kingston Fossil Plant in Roane County, Tennessee, USA. of coal fly ash slurry was released. The coal-fired power plant, located across the Clinch River from the city of Kingston, uses ponds to dewater the fly ash, a byproduct of coal combustion, which is then stored in wet form in dredge cells. The slurry (a mixture of fly ash and water) traveled across the Emory River and its Swan Pond embayment, on to the opposite shore, covering up to of the surrounding land, damaging homes and flowing up and down stream in nearby waterways such as the Emory River and Clinch River (tributaries of the Tennessee River). It was the largest fly ash release in United States history. ==Details== The Tennessee Valley Authority (TVA) and Environmental Protection Agency (EPA) initially estimated that the spill released 1.7 million cubic yards (1.3 million m³) of sludge, which is gray in color. After an aerial survey, the official estimate was more than tripled to 5.4 million cubic yards (4 million m³) on December 25, 2008.〔 The spill covered surrounding land with up to six feet (1.8 m) of sludge. The EPA first estimated that the spill would take four to six weeks to clean up; however, Chandra Taylor, the staff attorney for the Southern Environmental Law Center, said the cleanup could take months and possibly years. As of June 2009, six months following the spill, only 3% of the spill had been cleaned and is now estimated to cost between $675 and $975 million to clean, according to the TVA. The unlined aboveground ash fill, which was situated above the ash pond and above the Emory River winter level, above sea level, contained a watery slurry of fly ash generated by the burning of finely ground coal at the steam power plant.〔(【引用サイトリンク】title=Fly Ash definition )〕 Fly ash is the fine particulate pollutants produced by the combustion of coal, which are collected rather than allowing them to escape into the atmosphere, then mixed with water so they can be pumped into the retaining pond.〔 〕 Once the particulate matter settles out, it is dredged to drying cells.〔 The dredge cell was surrounded by tall earthen walls, which had twice developed leaks since 2002. Although the land surrounding the power plant is largely rural rather than residential, the spill caused a mudflow wave〔 〕 of water and ash that covered 12 homes,〔 pushing one entirely off its foundation, rendering three uninhabitable,〔 and caused some damage to 42 residential properties. It also washed out a road,〔 ruptured a major gas line,〔 obstructed a rail line, downed trees, broke a water main,〔 〕 and destroyed power lines. Though 22 residences were evacuated,〔 nobody was reported to be injured or in need of hospitalization. It was the largest coal-related slurry spill in United States history, more than three times the size of the Martin County sludge spill of 2000, which spilled of liquid coal waste.〔 The of sludge were enough to fill 1,660 Olympic-size swimming pools,〔 and the volume released was about 101 times larger than the 1989 Exxon Valdez oil spill (1.1 billion/10.9 million=100.9). On December 23, 2008, a TVA spokesman, Gil Francis Jr., stated that, at the time of the spill, the area contained about 2.6 million cubic yards (2.2 million m³) of ash, and that two-thirds of that had been released,〔 which would later be found to cover an area of .〔 ''The New York Times'' noted that the amount spilled is larger than the amount stated to have been in the pond before the spill, a discrepancy the TVA was unable to explain.〔 The containment area affected was one of three; the other two stayed intact, while only the retaining wall for the solid waste containment area was affected. The spill killed a "tremendous" number of fish, according to the Chattanooga Times Free Press. Although residents feared water contamination, early tests of water six miles (10 km) upstream of the ash flow showed that the public water supply met drinking water standards.〔 A test of river water near the spill showed elevated levels of lead and thallium, and "barely detectable" levels of mercury and arsenic.〔 On January 1, 2009 the first independent test results, conducted at the Environmental Toxicology and Chemistry laboratories at Appalachian State University, showed significantly elevated levels of toxic metals (including arsenic, copper, barium, cadmium, chromium, lead, mercury, nickel, and thallium) in samples of slurry and river water. The Kingston Fossil Plant received a total of of rain between December 1 and December 22, plus on November 29 and 30.〔(【引用サイトリンク】title=Valley Precipitation )〕 This rain combined with temperatures were identified by TVA as factors that contributed to the failure of the earthen embankment. An October 2008 inspection report had identified a "minor leak" in the faulty wall, but the report was not finalized. Local residents said that the spill was not a unique occurrence; the 1960s-era pond had been observed leaking, and being repaired, nearly every year since 2001.〔 A TVA news release confirmed that there had been two prior cases of seepage, in 2003 and 2006. 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「Kingston Fossil Plant coal fly ash slurry spill」の詳細全文を読む スポンサード リンク
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