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The environmental threat of tailings dams

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The Olympic Dam mine in South Australia (Photo via Jessie Boylan, supplied)

BHP has applied to expand the Olympic Dam mine in SA, but with the recent failure of tailings dams, caution must be taken, writes Dave Sweeney.

AWAY FROM THE airbrushed corporate head offices, staged media events and slick communications products, the reality of the mining trade is pretty basic and very intrusive.

An orebody is identified, extracted, processed and removed and while the clothing might be high-visibility, many of the industry’s impacts tend to stay pretty low on the wider world’s radar.

Right now, the world’s biggest mining company, BHP, has formally applied to expand the massive Olympic Dam mine in northern South Australia.

This plan deserves serious attention and scrutiny for three key reasons: it involves the long-lived and multi-faceted threat of uranium, it proposes to use massive amounts of finite underground water and the company is in trouble globally over the management of mine wastes and residues currently stored in multiple leaking – and sometimes catastrophically failing – tailings dams.

BHP has recently commissioned a “tailings taskforce” to conduct a high-level review of the management of the company’s tailings dams or tailing storage facilities.

The move comes in the literal wake of the collapse of a tailings dam at the Samarco iron ore operation in Brazil in 2015 that saw 19 deaths along with widespread and continuing environmental damage.

The mine was a joint operation of BHP and Vale, a Brazilian mining multinational that is a major player in global iron and nickel production, promoting its mission as transforming natural resources into prosperity.

Or maybe not after an estimated 40 million cubic metres of toxic sludge from the collapsed dam poisoned the Doce River and utterly devasted the lives of the local Krenak people.

Nothing quite focuses the corporate mind as a high profile and high cost legal action and in May, BHP was served with a multi-party damages claim for over $7 billion on behalf of around 235,000 claimants.

The memory of Samarco and the dangers of large-scale tailings dam failure were tragically highlighted in January this year when another Vale tailings dam at the Brumadinho mine failed, resulting in terrible loss of life with a death toll of between two and three hundred people and massive environmental impact.

In this context, it is deeply disturbing that BHP recently confirmed that three of the tailings dams at Olympic Dam are in the “extreme risk” category.

This is the highest risk status according to what is often regarded as the best global industry benchmark – the Canadian Dam Association’s safety standards – and relates less to the likelihood of collapse and more to the severity of the resulting human and environmental impacts if a failure did happen.

In preparing to contest the new Olympic Dam expansion, environmental groups have commissioned a detailed analysis that clearly shows the tailings present a significant, near intractable, long-term risk to the environment.

However, there are serious concerns that BHP is seeking this major tailings expansion without a full Safety Risk Assessment — such an approach is inconsistent with modern environmental practice and community expectation.

Olympic Dam tailings contain around 80 per cent of the radioactivity associated with the original ore as well as around one-third of the uranium from the ore.

Since 1988, Olympic Dam has produced around 180 million tonnes (Mt) of radioactive tailings. These are intended to be left in extensive above-ground piles on-site forever.

BHP’s radioactive tailings at Olympic Dam are extensive and cover 960 ha or 9.6 km2, an area one-third larger than Melbourne’s CBD.

They have reached a height of 30 metres, roughly that of a ten-storey building, at the centre of tailings piles where water sprays are used to limit tailings dust release and potent radioactive radon gas is released to the atmosphere.

Critics of the planned expansion are calling for safety to be comprehensively and transparently assessed across all tailings at Olympic Dam, without any restrictions, exemptions or legal privileges to the company, before any decision on new storage facilities or more radioactive tailings production.

In the public interest, a full comprehensive tailings Safety Risk Assessment is required from BHP in the expansion Assessment Guidelines and this must be subject to public scrutiny in the EIS Assessment process.

Environment groups are demanding that the EIS Guidelines adopt the Federal Government’s Olympic Dam Approval Condition 32 Mine Closure (EPBC 2005/2270, Oct 2011) as a requirement on BHP for a full Comprehensive Safety Assessment, covering all radioactive tailings at Olympic Dam including that the tailings plan must:

‘...contain a comprehensive safety assessment to determine the long-term (from closure to in the order of 10,000 years) risk to the public and the environment from the tailings storage facility.’

In recognition that tailings risks are effectively perpetual, Condition 32 on Mine Closure requires environmental outcomes:

‘...that will be achieved indefinitely post mine closure.’

The SA Government’s Guidelines and the full comprehensive tailings Safety Risk Assessment must also incorporate the higher environmental standards set by the Federal Government in 1999 to regulate the Ranger Uranium Mine in Kakadu in the Northern Territory:

‘to ensure that:

  1. The tailings are physically isolated from the environment for at least 10,000 years;
  2. Any contaminants arising from the tailings will not result in any detrimental environmental impact for at least 10,000 years.’

There is an obligation for these Guidelines to mandate the application of the ‘high environmental standards’ set out in Object D of the Commonwealth-SA Assessment Bilateral Agreement.

BHP must demonstrate a plausible plan to isolate radioactive tailings mine waste from the environment for at least 10,000 years, in line with the Federal Government’s environmental requirements at the NT’s Ranger uranium mine.

And the South Australian and Federal Governments have a clear duty of care to make sure they do. After Brazil, no one in industry or government can ever say they didn’t know.

Dave Sweeney works on nuclear issues with the Australian Conservation Foundation and was a member of the Federal advisory panel on radioactive waste. You can follow him on Twitter @nukedavesweeney.

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