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
34 4 Prediction and impact of severe weather events 4.1 Introduction The previous chapter of this report addressed hydrological modelling issues under current climatic conditions. It included, however, an assessment of severe weather events in the sense of severe annual rainfall events that would only be expected to occur once in 10,000 years. The submission of Wasson et al to the Mission of the World Heritage Committee (Wasson et al 1998) addressed a number of other types of severe weather events such as: evidence in the historical record of very severe weather events, the appropriateness of estimates of Probable Maximum Precipitation events (PMP), and the effect of climate change on the design of water management systems. These issues are addressed in this chapter. 4.2 Evidence on past severe weather events in the region In their submission to the Mission of the World Heritage Committee, Wasson et al (1998) presented evidence that, in the past, climatic conditions in the region have been very different to current conditions. They refer to the work of Wasson et al (1992) in which it was shown that a transition from a much drier climate took place somewhere between 1900 and 1400 years before present. They also refer to the work of Nott (1996) which demonstrated that river discharges in Waterfall Creek in the south of Kakadu National Park were about five times larger than current discharges between 8000 and 4000 years before present. On the basis of this evidence, Wasson et al (1998) conclude that the design of bunds, and all other structures to contain tailings, water and other wastes, at both Jabiluka and Ranger, is based on principles that are grossly inadequate. We simply do not know if the design structures can withstand the major rainfall events of the future, so the integrity of Kakadu NP cannot be guaranteed with any probability. The Supervising Scientist does not dispute the evidence cited by Wasson et al (1998) from the work of Nott (1996) and Wasson et al (1992) that the climate of the region has been significantly different from the present climate during the past 10,000 years nor the conclusion that similar differences in climate may occur during the next 10,000 years. What is disputed, however, is the application of this scientific evidence to the management of water and tailings at Jabiluka. The criticisms of Wasson et al (1998) are all premised on the assumed need to design and build tailings and water retention dams that will be structurally stable for 10,000 years and will totally contain all water that might accumulate over this period. This assumption is totally incorrect and reflects a lack of understanding of the accepted proposal for milling at Jabiluka by the authors of the submission. The storage of tailings or contaminated water on the land surface over a period of 10,000 years is not an issue. The project approved by the Minister for the Environment required all tailings to be returned underground to the mine void and to additional stopes or silos specially excavated to contain the tailings. There will, therefore, be no need to contain tailings in surface repositories for any period longer than the mine life, approximately 30 years. Wasson et al (1998) also propose that if the water retention ponds become seriously contaminated, then they too will need to be stable for 10,000 years. This is not the case.