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West Lake Landfill is an unlined mixed-waste landfill located in Bridgeton, Missouri, near St. Louis and the Mississippi River, whose contents have been shown to include radioactive waste; it is thus also an EPA Superfund cleanup site. In 1973, after having changed hands (and responsible oversight) several times, a portion of original stored radioactive material at a nearby storage facility—the material with lowest relative radioactivity, a leached barium sulfate residue originating from the Manhattan Project—was combined with topsoil to dilute the contaminated material. It was then illegally dumped at the West Lake site. Due to the discovery of the radioactive and other contaminants at the site, West Lake was proposed as a Superfund site in October 1989, and after undergoing an extensive feasibility study, it was officially listed as such a site in August 1990. The landfill is divided into multiple sectors, within which are two operable units (OU), OU-1 and OU-2. OU-1 contains radioactive material; OU-2 has been shown to as well. In addition to the radioactivity from the dumped barium sulfate cake, soil samples also indicate the presence of many more radioactive materials, including uranium, thorium, and elements resulting from their decay. OU-1 covers on the surface (based on soil depth of ) and subsurface, while OU-2 covers on the surface and subsurface. Recently, the West Lake landfill has drawn further scrutiny because of a nearby subsurface smoldering fire (in OU-2), and event located only away from OU-1. If the fire were to reach the OU-1 area of radioactive waste, radiation could be be released into the air. ==History== The West Lake Landfill site originated in 1939 as a limestone quarry operated by the Westlake Quarry Company.〔 Landfilling at the site began in the 1950s.〔(【引用サイトリンク】title=West Lake Landfill )〕 In 1973, B&K Construction Co., a company contracted by Cotter Corporation, dumped of leached barium sulfate and of soil at the landfill.〔〔 〔 The leached barium sulfate was a byproduct of Mallinckrodt Chemical Works’ uranium enrichment program as a part of the Manhattan Project and later nuclear weapon production.〔 The Nuclear Regulatory Commission discovered the disposal and investigated the site, publishing a report in 1977.〔(【引用サイトリンク】title=NPL Site Narrative for Westlake Landfill )〕 West Lake was proposed to be a Superfund site on October 28, 1989, and the EPA placed the landfill on the National Priorities List, designating it as a Superfund site on August 30, 1990. The EPA has listed four potentially responsible parties: the US Department of Energy; the Cotter Corporation; and Republic Services subsidiaries Bridgeton Landfill and Rock Road Industries.〔 EPA directed those parties to undertake investigations and evaluations consistent with CERCLA (Superfund) guidance.〔 After decades of investigation, including multiple studies, public meetings, and public comment periods, the EPA selected a final site cleanup plan.〔 In 2008, the EPA announced that they would contain the contaminated sites by placing a multilayered cover over of OU-1.〔 〔 The EPA plan also required institutional controls and monitoring of the site.〔 After receiving additional comments from environmental groups and the general public, the EPA asked the potentially responsible parties to commission a study of alternative cleanup options.〔〔〔 The resulting supplemental feasibility study was released in 2011.〔 In 2012, following consultation with the EPA National Remedy Review Board, the EPA asked the potentially responsible parties to gather more data and perform additional evaluations.〔 After conducting an aerial survey of the site and surrounding areas in 2013, the EPA reported that the radioactive waste remained contained within OU-1 and posed no safety risk to outlying areas. 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「West Lake Landfill」の詳細全文を読む スポンサード リンク
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