Assessment of the Jabiluka Project : report of the Supervising Scientist to the World Heritage Committee
Johnston, A.; Prendergast, J. B.; Bridgewater, Peter
E-Publications; E-Books; PublicationNT; Supervising Scientist Report; 138
Alligator Rivers Region
Main report--Appendix 2 of the Main Report. Submission to the Mission of the World Heritage Committee by some Australian Scientists ... --Attachment A. Johnston A. and Needham S. 1999. Protection of the environment near the Ranger uranium mine--Attachment B. Bureau of Meteorology 1999. Hydrometeorological analysis relevant to Jabiluka--Attachment C. Jones, R.N., Hennessy, K.J. and Abbs, D.J. 1999. Climate change analysis relevant to Jabiluka--Attachment D. Chiew, F and Wang, Q.J. 1999. Hydrological anaysis relevant to surface water storage at Jabiluka--Attachment E. Kalf, F. and Dudgeon, C. 1999. Analysis of long term groundwater dispersal of contaminants from proposed Jabiluka mine tailings repositories--Appendix 2 of Attachment E. Simulation of leaching on non-reactive and radionuclide contaminants from proposed Jabiluka silo banks.
Uranium mill tailings - Environmental aspects - Northern Territory - Alligator Rivers Region; Environmental impact analysis - Northern Territory - Jabiluka; Uranium mines and mining - Environmental aspects - Northern Territory - Jabiluka; Jabiluka - Environmental aspects
Supervising Scientist Report; 138
1 volume (various pagings) : illustrations, maps
https://hdl.handle.net/10070/462403; https://hdl.handle.net/10070/462400; https://hdl.handle.net/10070/462405; https://hdl.handle.net/10070/462406; https://hdl.handle.net/10070/462408; https://hdl.handle.net/10070/462409; https://hdl.handle.net/10070/462411
60 runoff coefficients for the stockpile and the whole catchment have been assumed to be 1.0 and 0.4 respectively although towards the end of a Wet season with an exceedence probability of greater than 1:1,000 the runoff coefficient for the whole catchment would also probably be approaching 1.0. The areas of the catchments have been taken as 40 km2 for Swift Creek and 2500 m2 for the ore stockpile as specified in the PER. These figures yield a dilution factor of about 6400. As indicated in section 5.3.1, the principal constituents of runoff that need to be considered are magnesium, sulphate and uranium. A number of studies of the toxicity of uranium to local native species of Kakadu National Park have been carried out by the Supervising Scientist and by ERA. These measurements were conducted following an extensive program of research by the Supervising Scientist in which 19 different local native species of aquatic animals and plants were investigated (Holdway et al 1988a) to establish their suitability for incorporation in an ecotoxicological testing program. The species eventually adopted in the program were chosen on the basis of their suitability with respect to rearing and captive husbandry and also with respect to the sensitivity of their response to exposure to waters in the retention ponds at the Ranger mine. Results for the toxicity of uranium to aquatic animals of the region are given in Holdway et al (1988b), Bywater et al (1991) and Holdway (1992). The lowest concentration of uranium at which any adverse effect was observed (the LOEC) was 190 g/L and the highest concentration at which no effect was observed (the NOEC) was 160 g/L. These results were obtained for the Cnidarian Hydra viridissima using population growth over six days as the test endpoint. Other work by the Supervising Scientist (Lewis 1992) indicated that the sensitivity of freshwater snails to waters in the retention ponds at Ranger, in which uranium is the most significant constituent, is comparable with that of Hydra. The regular application of ecotoxicological data is in determining the dilution required to render safe the discharge of an effluent into a stream. In such cases, the approach usually adopted is to apply a safety factor to the geometric mean of the lowest NOEC and the corresponding LOEC to take into account within-species variability, between-species variability and statistical effects (ie Type I vs Type II errors). This approach has been adopted by, and continues to be recommended by, the Supervising Scientist in the application of Best Practicable Technology to the management of water at the Ranger mine (Johnston 1991). The reason for the approach is that, in recommending a safe dilution for an actual release of effluent, the species used in the laboratory are being considered as surrogates for the whole ecosystem and caution needs to be applied to ensure that other aquatic animals will be protected. The same approach is recommended for risk assessments (van Leeuwen & Hermens 1995, USEPA 1998) to determine the concentration below which no effects on aquatic ecosystems will be expected. Using the data given above for hydra, the safe concentration for uranium is 18 g/L. In the current assessment, this concentration will be used to indicate the concentration below which no effects are expected. In addition, the lowest observed LOEC in tests carried out on local native species, 190 g/L, will be used to indicate the concentration above which adverse effects would be expected to occur. For concentrations intermediate between the safe concentration and the effects concentration, it is considered that adverse effects may occur in some species, particularly invertebrates. In this context, it should also be noted that the estimate used for the concentration of uranium in runoff from the ore stockpile (see section 5.3.1) is considered to be a worst case scenario and is about a factor of 10 higher than the estimate made by ERA in the PER based upon
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