TOTAL VOLUMES OF SUBSTANCE RELEASED
1985, 2004, 2014 >34 million m3
1962, 1980, 1994, 2008 >26 million m3
Mexico 1937 > 2 million m3
1995 > 4 million m3
2007, 2015, 2019
>74 million m3
1998 > 5 million m3
Hungary 2010 > 1 million m3
USSR 1981 > 3 million m3
1982, 1992, 2012 >120 million m3
South Africa 1994 > 0.6 million m3
Fit to Burst
The recent dam collapse in Brazil could just be the beginning of a series of disasters due to inadequate dam technology and monitoring
An upstream dam uses far less wall material and occupies less land than a downstream dam, but can be less stable particularly if seismic activity is a feature of the region.’
So wrote mining engineer Chandra Durve and then head of technology at Cornwall technical college, Dr Edward Ferrett, in October 1985 in an article for Geographical about tailings dams – the structures used to contain the waste product of mining operations. The dams, they noted, require constant monitoring using small instruments that measure water pressure: ‘It is this type of continuous monitoring that could provide early warnings of potential failures.’ As recent events in Brazil and around the world indicate, it seems these warnings, already well understood in the 1980s, have not been heeded by some large mining companies.
The most recent upstream tailings dam collapse took place on 25 January in the state of Minas Gerais in Brazil when the 280-foot-high structure owned by Vale SA, which towered over the small town of Brumadinho, collapsed, sending 11.7 million cubic metres of toxic mud downstream. The surge crashed into the Vale administration rooms where workers were eating lunch, overwhelmed trains and vehicles and submerged nearby homes. At the time of writing, an estimated 300 people have been killed and the waste is still on the move, contaminating rivers and water supplies in the area. The disaster follows a similar event in 2015, when another tailings dam in Minas Gerais owned by Samarco – a joint venture between Vale and BHP Billiton – collapsed, killing 19 people. Shortly before that, the Mount Polley tailings dam in Canada failed, sending eight million cubic metres of gold and copper waste into a pair of glacial lakes. According to the non-profit organisation World Mine Tailings Failures
6 • Geographical
Barnes & Noble
Find out more information on this title from the publisher.
Sign in with your Exact Editions account for full access.
Subscriptions are available for purchase in our shop.
Purchase multi-user, IP-authenticated access for your institution.
Register for digital access using your print subscription details.