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
87 preferable from the perspective of minimising environmental hazards on the surface because the sandstone is relatively low in the concentrations of hazardous chemicals. This material will require additional attention during the rehabilitation phase, but control of potential impacts on surface waters will be straightforward. The quality of groundwaters in the vicinity of the Jabiluka orebody, both to the west in Mine Valley and to the east towards Swift Creek, is high. Soluble salt concentrations are relatively low and radionuclide concentrations are very low. It is concluded that there is very little movement of radionuclides into the groundwater aquifer from the orebody. In contrast, the groundwater underlying the acid sulphate soils of the Magela floodplain is of high salinity, is acidic, and has high sulphate concentrations. The observed sulphate concentrations are up to one third of the concentration of sulphate expected in the Jabiluka tailings. Modelling of the dispersion of solutes in groundwater A two dimensional section finite element model was used to determine flow directions, head distributions and the range of velocities. A three dimensional numerical solute transport model was applied to determine the concentrations of solutes leached from the tailings paste material for use as the source concentrations in the analytical model. An analytical contaminant transport model was used to determine concentrations due to advection, dispersion in three co-ordinate directions and retardation. This model used as input the range of velocities and source concentrations determined from the first two models. This model was combined with Monte Carlo calculations to determine concentration profiles for a large number of different parameter values within selected ranges. Properties and constituents of tailings Although limited information is available on Jabiluka tailings because the mine is not operational, physical properties of tailings at Ranger have been studied extensively. Ore at Jabiluka and the Ranger Mine originate from the same geological formation and will be subject to the same milling process. Hence the tailings from the two mines are expected to have similar physical and chemical properties. Work undertaken as part of this review shows that achieving a tailings permeability of less than 10-9 m/sec is desirable. Based upon the research carried out on Ranger tailings, it is concluded that 99% of tailings in the silos at Jabiluka would have a permeability of less than 10-9 m/sec. Similar results are expected for tailings in the mine void but care will need to be exercised in placement of tailings in the mine void to avoid segregation and extensive residual voids. Research elsewhere on the effect of cementing the tailings paste indicates that the permeability of tailings will be reduced still further and may even reach a value which is lower than normal tailings by a factor of 1000. The addition of cement to the tailings will result in highly alkaline conditions which will reduce the availability of metals and radionuclides for dispersion from the tailings mass in groundwater. The conclusion of this review is that there is a very high probability of achieving a permeability in the cemented tailings that is less than 10-9 m/sec.