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
6 The combined effect of adopting the recommendations of this review on each of the above topics rather than the model used by ERA is that the pond volume required to achieve a given exceedence probability will increase by about 10%. Use of pond evaporation rather than enhanced evaporation in the ventilation system The use of pond evaporation rather than enhanced evaporation in the ventilation system would lead to a reduction in the required storage capacity of about 30% because the full evaporative capacity would be available from the commencement of operations rather than achieving its maximum effect only after 10 years of operation. It is recommended that ERA, in its detailed design of the Jabiluka water management system, uses increased pond evaporation rather then enhanced evaporation in the ventilation system. In making this recommendation, it is recognised that some enhanced evaporation in the ventilation system as a result of dust suppression procedures is inevitable. This will need to be modelled carefully by ERA to achieve the optimum water management system. Partitioning the water retention pond into three or four compartments with connecting spill-ways and a water pumping system is one way in which control of evaporative losses could be achieved. Evaporative losses in dry spells could be minimised by pumping all remaining water into one of the compartments and could be maximised in wetter periods by using the full evaporative capacity of all of the compartments. It is recommended that ERA consider this approach in the detailed design of the water management system at Jabiluka. Effect of climate change on the required storage capacity The minimum predicted temperature increase is the extreme scenario for water balance modelling since this would minimise evaporation and hence maximise the required storage volume. The minimum predicted increase of 0.35C over the next 30 years is insufficient to have any significant impact on evaporation. There is no need, therefore, to adjust the hydrological model to take the effect of temperature change into account. The maximum predicted change in annual rainfall from global warming over the next 30 years is 1%. There is, therefore, no need to repeat the simulation of the water management system to take this effect into account. The effect of climate change will be negligible. The effect of the predicted increase in storm intensity due to global warming has been assessed using the results of a sensitivity analysis. The results indicate that this increase in storm intensity would not have any significant impact on the required storage capacity of the water management system at Jabiluka. Risk assessment of the ERA proposal A risk assessment has been carried out for the water management system proposed by ERA for the Jabiluka mine. In this context, it is important to note that tailings will not be stored at the surface. The principle hazard that needs to be assessed is the possible impact on people and on downstream ecosystems arising from the unplanned discharge of water that has been in contact with uranium ore. In conducting the risk assessment, estimates have been made of the concentraions of solutes in runoff from the ore stockpile. All of these concentrations are considered to be maximum expected values and some are likely to be significant over-estimates.