Previous work at UCT to characterise coal processing wastes for ARD potential was challenged by inadequate characterisation techniques and insufficient evaluation tools. This project aims to optimise the toolbox for characterising the environmental risks associated with coal waste using mineralogical, elemental, geochemical ARD and metal risk assessment. The static ARD tests will be enhanced and validated by an extended boil Net Acid Generation protocol. Sulphur speciation methods will be compared and evaluated. The spontaneous combustion potential of coal waste of various sources and origin will be evaluated. In addition, the long-term environmental risk of metals and salts mobilised under sequential chemical extraction and ARD leaching will be scored and ranked. The characterisation will be done at laboratory scale on a number of fine to coarse coal wastes from different coalfields and operations in South Africa. The optimised characterisation toolbox will provide reliable data for the assessment of human health and environmental risks potential posed by coal processing wastes. Furthermore the data will be useful in the justification and implementation of environmental impact mitigation measures and also in providing a basis for value recovery of these wastes.