ENVIRONMENTAL-IMPACT ASSESSMENT OF TAILINGS DISPERSAL FROM A URANIUM-MINE USING TOXICITY TESTING PROTOCOLS

Toxicity testing is a means of establishing the environmental risk of a uranium tailings release. It is valuable in designing tailings conta inment structures because it assists in setting acceptable levels of r isk for the design. This paper presents details of toxicity tests of t he tailings from Ranger Uranium Mine, Northern Territory Australia. Th e results suggest that the non-radiological toxicity of the tailings i s low. The environmental risk of a tailings release is more likely to be related to the physical impacts of the tailings, including infillin g of billabongs and changes in the sedimentology of riparian ecosystem s rather than their biogeochemical impact. Two major results were: (1) water from treatment with washed tailing fines were not toxic to Hydr a viridissima, and (2) mixtures of washed tailings fines and natural f loodplain sediment (overlying water or elutriates) were not toxic to H ydra viridissima or Moinodaphnia macleayi.