25 March 2019
Sul Superior: another Vale tailings dam at risk of imminent collapse in Brazil
The Brazilian mining company Vale warned over the weekend that its Sul Superior tailings dam, at the Gongo Soco mine near to Barão de Cocais, in the southeastern Brazilian state of Minas Gerais, is at risk of imminent collapse. This dam had been the focus of concern over the last two months, with evacuations from the path of a potential tailings flow starting on 8th February 2019. However, on Friday Vale raised the alert level to 3, the highest classification. The Guardian reports that, according to Brazil’s mining and energy secretary, level three means that “a rupture is imminent or already happening”. It also carries a quote from Lt Col Flavio Godinho, a member of the state civil defence department, that “any activity at the dam could trigger a rupture”.
Back in February, portaldasgerais.com.br posted this image of the Sul Superior dam:-
Indications are that this dam is in the order of 85 metres high, containing a volume of tailings in the range of 3 to 6 million cubic metres. Fortunately, this is somewhat less than was the case at Brumadinho, but is still sufficient to cause enormous environmental damage.
This appears to be the site on Google Earth – the location is -19.972, -43.598:-
There is a very interesting paper available online from the Colombia Water Center (NB PDF), which proposes a hazard assessment methodology for tailings dams, and uses a selection of large facilities in Minas Gerais as an example. Interestingly, the Sul Superior Dam generated a hazard assessment that is 17th out of a list of 28 facilities.It appears that the Brumadinho dam, which is sometimes technically known as Barragem I, ranked 7th on the list.