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
82 Richards, pers comm). Although Richards et al (1990) suggest that the data illustrated in figure 6.3.4 are the most representative of their measurements on Ranger tailings, they also measured higher values of permeability, particularly in areas where significant segregation had occurred. This indicates that care will be needed in the management and placement of tailings into the repositories at Jabiluka. Richards et al (1990) derived the following equation to represent the relationship between tailings permeability, k (m/s), and effective stress, h (KPa): 1114.27 102.1)72.10/()100.3( += xhxk (6.1) This equation has been plotted in figure 6.3.4. In the modelling work undertaken by Kalf and Dudgeon (1999) a tailings permeability of less than 10-4 m/day (approximately 10-9 m/sec) is recommended. The effective stress that would be required to achieve a permeability of 10-9 m/s can be calculated from Eq. 6.1, as 14 kPa. If approximate values are assumed for the tailings density of 2, and the density of water assumed to be 1, then 14 kPa of overburden stress can be achieved through a tailings overburden depth of approximately 1.4 m. For a 135 m deep silo at Jabiluka, 99% of uncemented tailings placed in a silo would have a permeability less than 10-9 m/s, and the mean tailings permeability in the 135 m high silo would be much less than 10-9 m/s (fig 6.3.4). The addition of 4% cement to the tailings can lower its permeability by a further three orders of magnitude. In addition to the effect of adding cement, the reduction in water content that will be achieved through dewatering the tailings (dewatering will be undertaken before cement additions) will improve the cohesiveness of the tailings and reduce the possibility of segregation, which can increase the permeability. Figure 6.3.4 Permeability (m/s) as a function of effective stress (kPa) for tailings from the Ranger Mine located 22 km from Jabiluka The considerations above indicate that a cemented tailings permeability of well below 10-9 m/s should be readily achieved at Jabiluka. The final percentage of cement to be added to the 1.E-11 1.E-10 1.E-09 1.E-08 10 100 1000 Effective stress (kPa) P er m ea b ili ty k ( m /s ) Sample 2 Sample 2 fitted line Sample 5 Sample 5 fitted line Sample 4 Sample 4 fitted line Equation 6.1
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