MISSION 19 of 2011
Name of Mission: Acid Mine Drainage Documentary
Date of Mission: 22 August 2011
Aircraft used: Cessna
Pilot: Philip Wakely
Beneficiary: Mariette Liefferink
Beneficiary’s report By Mariette Liefferink
I was approached by a group of film students who have been awarded a bursary/sponsorship to document the Acid Mine Drainage impacts, risks and hazards. As early as 1987, the US Environmental Protection Agency recognised that “…..problems related to mining waste may be rated as second only to global warming and stratospheric ozone depletion in terms of ecological risk. The release to the environment of mining waste can result in profound, generally irreversible destruction of ecosystems.” If this is indeed so then the Witwatersrand gold mining area of South Africa is at serious risk.
The potential volume of AMD for the Witwatersrand Goldfield alone amounts to an estimated 350ML/day (1ML = 1000m3). This represents 10% of the potable water supplied daily by Rand Water to municipal authorities for urban distribution in Gauteng province and surrounding areas, at a cost of R3000/ML. The gold mining industry in South Africa (principally the Witwatersrand Goldfield) is in decline, but the post-closure decant of AMD is an enormous threat, and this could become worse if remedial activities are delayed or not implemented.The Witwatersrand has been mined for more than a century. It is the world’s largest gold and uranium mining basin with the extraction, from more than 120 mines, of 43 500 tons of gold in one century and 73 000 tons of uranium between 1953 and 1995. The basin covers an area of 1600 km2, and led to a legacy of some 400 km2 of mine tailings dams and 6 billion tons of pyrite tailings containing 430 000 tons of low-grade uranium.
Waste from gold mines constitutes the largest single source of waste and pollution in South Africa and there is wide acceptance that Acid Mine Drainage (AMD) is responsible for the most costly environmental and socio-economic impacts. As at 1997, South Africa produced an estimated 468 million tons of mineral waste per annum (DWAF, 2001). Gold mining waste was estimated to account for 221 million tons or 47 % of all mineral waste produced in South Africa, making it the largest, single source of waste and pollution (DWAF, 2001). There are more than 270 tailings dams in the Witwatersrand Basin, covering approximately 400 km2 in surface area (AngloGold Ashanti, 2004). These dams are mostly unlined and many are not vegetated, providing a source of extensive dust, as well as soil and water (surface and groundwater) pollution (AngloGold Ashanti, 2004).Production of AMD may continue for many years after mines are closed and tailings dams decommissioned. AMD is not only associated with surface and groundwater pollution, degradation of soil quality, for harming aquatic sediments and fauna, and for allowing heavy metals to seep into the environment but long-term exposure to AMD polluted drinking water may lead to increased rates of cancer, decreased cognitive function and appearance of skin lesions. Heavy metals in drinking water could compromise the neural development of the fetus which can result in mental retardation.
An airborne radiometric survey of the Witwatersrand goldfields was done for the Department of Water Affairs by the Council of Geoscience. Interpretation of the data show many of the residential areas
within the central business district of Johannesburg, and densely populated residential areas within the West and Far West Rand, and the East Rand fall within areas of high risk of radioactivity contamination.