ABSTRACT As Early As 1987, the US Environmental Protection
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Registration Number: 2006/217972/23 NPO NUMBER: 062986-NPO ABSTRACT 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 ecosystems1.” Gold tailings dams from the Witwatersrand Basin usually contain elevated amounts of heavy metals and radionuclides. With slimes dams in the goldfields of the Witwatersrand Basin 2 covering an area of about 400 km and containing some 430 000 tons of U3O8, and 6 billion tons of iron pyrite tailings, they constitute an environmental problem of extraordinary spatial dimensions. Due to inadequate design, poor management and neglect, these tailings dams have 1 CSIR. Briefing Note August 2009. Acid Mine Drainage in South Africa. Dr. Pat Manders. Director, Natural Resources and the Environment. European Environmental Bureau (EEB). 2000. The environmental performance of the mining industry and the action necessary to strengthen European legislation in the wake of the Tisza-Danube pollution. EEB Document no 2000/016. 32 p 1 been subject to varying degrees of water and wind erosion. Effects range from water pollution, the result of acid mine drainage, and air pollution in the form of airborne dust from unrehabilitated or partially rehabilitated and reprocessed tailings dams. As a result of acid mine drainage (AMD), from point discharges and seepage uranium is released into the groundwater and fluvial systems. (Figure 1) Figure 1 2 West Wits Pit Figure 2 Recent public domain official and scientific studies indicate that there is active leaching of uranium from the tailings, transport of soluble uranium species through water systems, with subsequent deposition of insoluble uranium species in sediments of fluvial systems. Sequential extractions showed that these radionuclides are distributed in multiple phases within the sediments and that they may be remobilised by environmentally plausible chemical processes2. The Witwatersrand is densely populated. The subpopulation groups particularly at risk, are the indigent residents of informal settlements. Pollution related to the Witwatersrand gold mining industry poses a number of serious risks to surrounding communities. The major primary pathways by which contamination can enter the environment from a mine site are the airborne pathway, where radon gas and windblown dust disperse outwards from the mine sites, the waterborne pathway either via ground or surface water or due to direct access, or by living in settlements directly adjacent to mines or in some cases, living in settlements on the contaminated footprints of abandoned mines. 2 Coetzee et al. 2002. Council for Geoscience. 3 A recent study of radiological risk has identified significant risks to the public in the Wonderfonteinspruit Catchment (West and Far West Rand goldfields) due to irrigation, stock watering and other pathways3. Together with uranium, a number of other metals present in the gold ores are found in the waste streams and may pose a threat to public health. At the time of writing little information is available regarding the health risk to humans due to radionuclides, particularly at low levels. At the time of writing, there has been no public domain epidemiological or toxicological studies commissioned to determine or assess the chronic effects such as mutagenicity, teratogenicity and estrogenicity upon affected communities. The most important lesson learnt from the studies in the Wonderfonteinspruit is that no short- cuts exist which would allow certain pathways to be ignored in a study of radioactive contamination within these mining areas4. INTRODUCTION The Witwatersrand5 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 low-grade uranium6. 120 Years of gold mining activity within the gold mining areas of the West Rand and Far West Rand (Wonderfonteinspruit Catchment Area – Figure 1) and the non-internalisation of negative externalities, have resulted in "…the mean values for the Wonderfonteinspruit samples … to exceed not only natural background concentrations, but also levels of regulatory concern for cobalt, zinc, arsenic, cadmium and uranium, with uranium and cadmium exhibiting the highest risk coefficients.” 3 National Nuclear Regulator. 2007. 4 Draft Regional Closure Strategies for the Witwatersrand Goldfields. Department of Minerals and Energy. 2008. 5 *The Witwatersrand Mining Basin is composed of the Far East Basin, Central Rand Basin, Western Basin, Far Western Basin, KOSH and the Free State gold mines. 6 “A Remote-Sensing and GIS-Based Integrated Approach for Risk Based Prioritization of Gold Tailings Facilities – Witwatersrand, South Africa” by H. Coetzee. Mine Closure 2008, Johannesburg. 4 The Wonderfonteinspruit valley is densely populated because of its agricultural value and presence of gold mines. The majority of the inhabitants live in informal settlements, using contaminated ground- and stream water for personal hygiene and drinking. With above-average infection rates of HIV/AIDS and chronic and acute malnutrition, this subpopulation is particularly vulnerable to additional stress of the immune system by contaminants such as uranium. RADIOACTIVE HAZARDS Uranium is generally associated with the gold ores of the Witwatersrand. Uranium and its radiogenic progeny are therefore found in many of the residues and wastes produced in the mining and processing of gold7. Uranium is identified as the principal contaminant of concern within the gold mining areas of the West Rand and Far West Rand (Wonderfonteinspruit Catchment Area). (Figure 3) Uranium is emitted by a single industry namely the gold mining industry. Uranium is radioactive and chemically toxic with an extremely long half-life. It has been shown that the risk posed by uranium, an important by-product of gold mining in the West Rand and Far West Rand and an identified hazardous component of the wastes and effluents from gold mining activities, occurs due to both radiotoxicity and chemical toxicity with, in some cases, the chemical toxicity dominating over the radiotoxicity8. 7 “Radiometric Surveying in the Vicinity of Witwatersrand Gold Mines” by H. Coetzee. 2008. 8 “South Africa’s Challenges Pertaining to Mine Closure – The Concept of Regional Mining and Closure Strategies” by D.M. van Tonder et al; “Establishing a Framework for Intervention and Remediation of Radioactive Contamination from Gold Mining – Learning from the Past” by J.F. Ellis. 2008. 5 •Tailings Dams contain 100 000 tons of U •50 Tons of U discharged annually •Seepage/Percolation: 24 tons U (1 000 to 1 million higher than the background U concentrations) Technolgically Enhanced Naturally Occurring Radioactive Material •Point Discharges: 12 tons of U •Stormwater: 10 tons of U •Sinkholes: Secondary Sources of U contamination Figure 3: West and Far West Rand Goldfield The documents that hold the history of the Wonderfonteinspruit would exceed 5m if stacked. The bibliography of relevant literature that has been compiled would, if printed, extend to nearly 120 pages. In this submission copious reference will be made to the following official public domain Reports: An Assessment of Sources, Pathways, Mechanisms and Risks of Current and Potential Future Pollution of Water and Sediments in Gold-Mining Areas of the Wonderfonteinspruit Catchment - Report to the Water Research Commission. Compiled by Henk Coetzee, Council for Geosience - WRC Report No 1214/1/06 ; ISBN No 1- 77005-419-7 – March 2006. Contamination of wetlands by Witwatersrand gold mines – processes and the economic potential of gold in wetlands - Henk Coetzee, Jaco Venter & Gabriel Ntsume - Council for Geoscience Report No. 2005-0106 6 A comprehensive radiological risk assessment performed by German physicists on behalf the National Nuclear Regulator, the radiological risks to the public was published in the Report, entitled: Radiological Impacts of the Mining Activities to the Public in the Wonderfonteinspruit Catchment Area. The impacts of mining in the West Rand and Far West Rand on the surface and ground water system, in particular impacts related to uranium, with elevated levels of radioactivity are well documented. It was found that tailings dams within the Wonderfonteinspruit Catchment Area contain 100 000 tons of U. Groundwater pollution arise as a result of the poorly designed and managed tailings dams, which allow leachate to seep into the underlying aquifers and due to the lateral migration of water from the shallow portions of flooded mine voids into the surrounding aquifers. An important local groundwater issue has arisen in the Far West Rand, where mine tailings dams were established in sinkhole prone areas, with the stated aim of encouraging drainage of the tailings, and where tailings were used as a fill material after the development of sinkholes in the dolomite which covers large parts of the area. In both of these cases, uraniferous tailings can have a severe impact on water quality were deliberately introduced into a major aquifer9. It was found that: 50 Tons of U are discharged