Australian mines are environmental time bombs, say researchers
Mining companies and governments have been increasingly aware that an environmental time bomb is ticking away at hundreds of mine sites around Australia through acid mine drainage, according to the Commonwealth Scientific and Industrial Research Organisation (CSIRO) - Australia's largest scientific research organisation.
Acid mine drainage is caused by oxidation of sulfidic mining waste after ore is removed. CSIRO Minesite Environment Research leader, Dr Graham Taylor, says while old and abandoned mines are the biggest problem, with taxpayers footing the clean-up bill, potential contamination from active mines is a large environmental liability for the mining industry.
Dr Taylor says the mining industry is recognising, through duty of care obligations and community expectations, the value of a proactive role in avoiding contamination and is taking steps to do just that.
“According to a recent survey we estimate that for the Australian industry as a whole, the cost of managing potential acid generating wastes at operating mine sites is AU$60 million a year. That may seem like a lot of money, but it is cheaper than trying to clean up environmental damage after it has occurred,” says Dr Taylor.
For example, the cost of remediating abandoned sites releasing acid drainage – $100,000 per hectare – is 150 per cent higher than the average cost at active mine sites.
Dr Taylor, who heads CSIRO’s Minesite Environmental Research unit, says there are many examples throughout Australia of mine sites – both active and abandoned – which have not been adequately managed environmentally and which have caused varying degrees of contamination.
“These usually cost mining companies, and in some cases governments, more money to fix than they would have if the companies had put in place adequate management plans. . . .It’s only in the past 20 years that the potentially catastrophic effects of acid mine drainage have become known to miners, regulators and the public.
“One of the things we’re concerned about is that the industry’s most commonly used method of managing potential environmental damage, which is to simply cover the sulfidic waste and revegetate, may not be effective in the long term.”
Australia has a number of abandoned mines where acid drainage caused and, in many cases, still causes major contamination problems – Brukunga in South Australia, Captains Flat in New South Wales, Mt. Lyell in Tasmania, Mt. Morgan in Queensland and Rum Jungle in the Northern Territory, among others.
Despite general agreement on the potential environmental damage from acid mine drainage at Australian mines, the extent of the problem has not previously been accurately quantified. But now, a national survey supported by the mining industry has indicated there are 54 mine sites in Australia managing significant amounts of acid generating wastes and 62 sites are managing potential acid generating wastes.
The CSIRO Minesite Rehabilitation team of some 20 scientists and technicians is developing innovative techniques and cost-effective strategies for the industry and regulatory authorities to return land disturbed by mining to agreed community land use. It also evaluates the effectiveness of predictive techniques.
Dr Taylor says some of Minesite’s techniques may have possible applications overseas which could improve global mining rehabilitation as well as generate earnings for Australia.
More information: Dr Graham Taylor (08) 8303 8437 Leader, Minesite Environmental Research, CSIRO Land and Water
Ms Margaret Bryant CSIRO Land and Water 0417 247 241 (mob) (08) 9330 3101
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