page_title: Tailings dam
section_title: Environmental damage
hierarchical_section_title: Tailings dam / Concerns / Environmental damage
caption_attribution_description: O rompimento da barragem de rejeitos da mineradora Samarco, cujos donos são a Vale a anglo-australiana BHP, causou uma enxurrada de lama que inundou várias casas no distrito de Bento Rodrigues, em Mariana, na Região Central de Minas Gerais. Inicialmente, a mineradora havia afirmado que duas barragens haviam se rompido, de Fundão e Santarém. No dia 16 de novembro, a Samarco confirmou que apenas a barragem de Fundão se rompeu. Local: Distrito de Bento Rodrigues, Município de Mariana, Minas Gerais. Foto: Rogério Alves/TV Senado
context_page_description: A tailings dam is typically an earth-fill embankment dam used to store byproducts of mining operations after separating the ore from the gangue. Tailings can be liquid, solid, or a slurry of fine particles, and are usually highly toxic and potentially radioactive. Solid tailings are often used as part of the structure itself.
  Tailings dams rank among the largest engineered structures on earth. The Syncrude Mildred Lake Tailings Dyke in Alberta, Canada, is an embankment dam about 18 kilometres long and from 40 to 88 metres high. It is the largest dam structure on earth by volume, and as of 2001 it was believed to be the largest earth structure in the world by volume of fill.
  There are key differences between tailings dams and the more familiar hydroelectric dams. Tailings dams are designed for permanent containment, meant to "remain there forever". Copper, gold, uranium and other mining operations produce varied kinds of waste, much of it toxic, which pose varied challenges for long-term containment.
  An estimated 3,500 active tailings impoundments stand around the world, although there is no complete inventory, and the total number is disputed.
context_section_description: The mining and processing byproducts collected in tailings dams are not part of the aerobic ecological systems, and are unstable. They may damage the environment by releasing toxic metals (arsenic and mercury among others), by acid drainage (usually by microbial action on sulfide ores), or by damaging aquatic wildlife that rely on clear water.
  Tailings dam failures involving significant ecological damage include:
  the Brumadinho dam disaster, Brazil, January 25, 2019, where as many as 252 people are unaccounted for, and at least 134 are dead. The disaster released 12 million cubic meters of iron waste leading to the Paraopeba River.
  the Bento Rodrigues dam disaster, Brazil, November 5, 2015, considered the worst environmental disaster in Brazil's history, killed 19 people when an iron ore containment dam failed and released 60 million cubic meters of iron waste.
  the Mount Polley mine disaster, British Columbia, August 4, 2014, which released 10 million cubic metres of water and 4.5 million cubic metres of metals-laden tailings.
  the Ok Tedi environmental disaster in New Guinea, which destroyed the fishery of the Ok Tedi River, continuously from 1984 through 2013
  the Sotkamo metals mine, Finland, 4 November 2012, released "hundreds of thousands of cubic metres" of waste water which raised concentrations of uranium, nickel, and zinc in nearby Snow River, each to at least 10 times the harmful level.
  the Ajka alumina plant accident, Hungary, October 4, 2010, which released one million cubic metres of red mud, a waste product of aluminum refining, flooding the village of Kolontár and killing the Marcal River.
  the Baia Mare cyanide spill, Romania, January 30, 2000, called the worst environmental disaster in Europe since the Chernobyl disaster
  The Doñana disaster, southern Spain, 25 April 1998, which released 4-5 million cubic metres of acidic tailings containing heavy metals.
  the Church Rock uranium mill spill in New Mexico, July 16, 1979, the largest release of radioactive waste in U.S. history 
  three uranium tailings dams near the town of Ak-Tüz, present-day Kyrgyzstan, collapsed in a December 1964 earthquake, releasing 60% of their radioactive volume (600,000 cubic metres (21,000,000 cu ft)) into the Kichi-Kemin River and its agricultural valley
  an incident on April 7, 1961 released 700,000 cubic metres (25,000,000 cu ft) of uranium mine tailings from operations of the Soviet-era Wismut organization into the Zwickauer Mulde River in the village of Oberrothenbach
  the Mailuu-Suu tailings dam failure also in Soviet-era Kyrgyzstan on April 16, 1958 caused the uncontrolled release of 600,000 cubic metres (21,000,000 cu ft) of the radioactive uranium-mine tailings in to spill downstream into a portion of the densely populated Ferghana Valley
  Tailings ponds can also be a source of acid drainage, leading to the need for permanent monitoring and treatment of water passing through the tailings dam. For instance in 1994 the operators of the Olympic Dam mine, Western Mining Corporation, admitted that their uranium tailings containment had released of up to 5 million m3 of contaminated water into the subsoil. The cost of mine cleanup has typically been 10 times that of mining industry estimates when acid drainage was involved.
caption: Bento Rodrigues dam disaster, 2015
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