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Acid mine drainage is preventable if mining companies take their responsibilities seriouslyFormer United States President George Bush Jr. used the alleged existence of Saddam Hussein’s weapons of mass destruction (WMD) as a pretext to invade Iraq, bringing untold devastation to that country. When it turned out that the WMD did not exist, the revelation destroyed his legacy. Today, millions of South Africans living in the Witwatersrand basin literally are sitting on top of a scourge that constitutes a clear and present danger to their lives; a scourge that stems directly from the source of South Africa’s wealth. Now it is time to declare war on acid mine drainage (AMD).
AMD occurs when polluted water flows from old mining areas, containing high concentrations of heavy metals. Both rainwater and groundwater may be contaminated.
Rainwater that flows through mine tailings reacts with the substances in the crushed rock and becomes acidic. Groundwater that flows through underground mine shafts and other mining holes similarly is contaminated.
Then, in a dangerous gradual process called decanting, old mine shafts fill up with rainwater and groundwater; past a certain level, huge volumes of acid mine water flow into other water sources, including unpolluted groundwater, streams, rivers and borehole water.
On the Witwatersrand, the largest gold and uranium mining basin in the world, the problem has been building up for over 100 years. The more than 120 mines that have operated there collectively have removed 43 500 tonnes of gold, with 73 000 tonnes of uranium extracted between 1953 and 1995. Apart from fuelling the dynamo that drove the South African economy, this mammoth activity also generated some 400 square kilometres of mine tailings dams and six billion tonnes of pyrite (iron sulphide) – a substance that makes acid mine water on exposure to air and water.
The Witwatersrand Mining Basin covers some 1 600km2, consisting of the Far East Basin, Central Rand Basin, West Rand Basin, Far Western Basin, KOSH (Klerksdoorp, Orkney, Stilfontein and Hartebeestfontein) and the Free State gold mines. This is the area into which water affected by AMD has been flowing naturally for years – ultimately flowing into the Vaal and Limpopo rivers.
The problem already has assumed crisis proportions. A statement by the Department of Water and Environmental Affairs last year announced: “Various studies predict that AMD will entirely decant into the central basin within three and a half years. This situation not only represents a potential environmental catastrophe, but also threatens the structural integrity of the Johannesburg city centre.”
In the words of clinical toxicologist Carin Smit: “The extreme variations in pH, along with the high toxic metal content, along with the high volume of sulphates in the water (upward of 2 500ppm) makes for a river of death, which will affect vegetation, aquatic life, bird life, animal life (especially in the Krugersdorp Game Reserve, as it is hardest and first hit!); and downstream it will affect farmers and low-income communities, who rely on the water for everyday living.” (http://carinsmit.co.za)
AMD is preventable if mining companies take their responsibilities seriously and manage mine tailings and old mines properly.
Unfortunately, the South African mining sector has not always acted as an exemplary citizen in this regard. In recent years particularly, dwindling profits have led some marginal mines to cut costs aggressively, in some cases leading to scandals related to fatal mining accidents. With such a cavalier attitude toward human life, their regard for the environment can only be scant.
So the mess has to be cleaned up before the Witwatersrand implodes, with a nasty, schlupping sound, into the cavity from which its wealth was extracted. Of course, the decontamination process is extremely difficult and expensive, so the Department of Water and Environmental Affairs has stepped into the fray with the announcement of a R6.9-million subsidy to assist mines in dealing with this problem.
“The department and the mines are in partnership to take on this inherited liability, caused by 120 years of gold mining in the area.
“We have made these funds available over the next three months and are prepared to engage in further investment to aid the mines with the AMD problem,” said Minister of Water and Environmental Affairs Bujelwa Sonjica at a press conference. The subsidy will be used to enhance the water treatment plants of Rand Uranium and Mintails’ and help the mines to decontaminate partially, with calcium carbonate and calcium hydroxide, any AMD that overflows before it has a chance to enter local water systems.
As Rand Uranium chief executive officer John Munro told Mining Weekly Online, record levels of rain in recent months have exacerbated the problem, stating that Rand Uranium has been pumping and treating 13 million litres of water a day. The subsidy would facilitate the treatment of another 2.5 million litres of water daily.
The subsidy also would enable Mintails, another local mining company, to deal with some five million litres of water a day. In addition, Munro mentioned that two dosing plants had been built to form a “last-resort buffer”.
Obviously, this is a stop-gap measures. Is the government serious about the problem? One cannot help but notice the disparity between the sum allocated to deal with this impending catastrophe and the subsidy earmarked for President Jacob Zuma’s family. Will the mining sector do the right thing, even if it means closing down mines?
As Minister Sonjica noted, “We are sitting on a ticking time bomb, as it is predicted that AMD will also decant in the central and eastern basins of Johannesburg, as soon as next year and at three times the magnitude.
“The department is in conversation with the mines, and other role-players to decide on a sustainable, long-term solution to the problem, before it is too late.”
