Modelled environmental risk-values for low cost housing developments on rehabilitated gold-tailings dams : scientific paper

In view of the current socio economic situation in South Africa, there is a nationwide need for low cost housing, which typically requires low cost land. One such option is land which is situated close to mines or on sites of previously existing mining activities (rehabilitated tailings areas) (NNR, 2002:4). Mining companies need to determine whether rehabilitated areas are contaminated, as well as the degree of contamination. This is necessary in order to adhere to South African legislation (Mineral and Petroleum Resources Development Act (Act 28 of 2002)), which states that tailings areas must be rehabilitated to either their natural state or to a land use which conforms to the principle of sustainable development. Before a rehabilitated tailings dam arising from mining operations is assigned to a new land use, it is important that potential impacts on human health be determined, particularly impacts arising from residual radioactive material. When houses are built in areas with high radium concentrations, levels of radon gas are an important consideration, as a link has been established between radon and lung cancer in humans (EPA, 2003). The use of the Residual Radioactive Material Guidelines (RESRAD) modelling programme to determine the environmental risk values for rehabilitated gold-tailings dams was explored. RESRAD is a relatively conservative model for determining radiation dose, radon levels and risk values at a contaminated site. It was found that the dose rate received by children was higher than that of adults, due to the higher metabolic rate of children. In addition, poor quality building standards of low cost houses may further increase the dose and risk to inhabitants, thus alternative land uses may be more appropriate, where radon mitigation measures could be better controlled.