Five BHP tailings dams pose 'extreme risk': Update

Adds types of mines in second paragraph

UK-Australian mining firm BHP's has classified five of its tailing dams as posing an "extreme risk" to surrounding communities in the event of a collapse, while a further 16 are said to pose a "very high risk".

The dams were ranked according to the Canadian Dam Association (CDA) Consequence Classification ratings. Of those posing an extreme risk, one is in the US and four are in Australia. A pair are inactive, but the tailings dams at the Whaleback iron ore mine in Western Australia and Olympic Dam copper-uranium mine in South Australia remain active.

The facilities ranked very high risk are located in Australia, Chile, Canada and the US, five of which are in Arizona. Facilities at two non-operated joint ventures — Antamina in Peru and Samarco-Germano in Brazil — were also rated an extreme risk.

BHP commissioned the risk assessment after two high-profile collapses at Brazilian tailings dams resulted in the deaths of hundreds of people and severely disrupted iron ore mining operations, causing global supply concerns.

In November 2015, Fundao tailings facility at the Samarco complex — a joint venture between BHP and Brazil's

Vale — ruptured, killing 19 people and causing one of Brazil's worst environmental disasters. Last month, Samarco announced plans to restart operations at the mines.

Vale became the subject of further controversy in Brazil in January when the Brumadinho dam collapsed at the Corrego do Feijao iron ore mine, killing hundreds of people and devastating the surrounding environment.