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
21 3 Hydrological modelling 3.1 Introduction A number of questions were raised by Wasson et al (1998) on the validity of the assumptions and analytical methods used by the proponent in the design of the Total Containment Zone (TCZ) at Jabiluka. The issues raised relate to: The methods used to derive the annual rainfall that is not likely, on average, to be exceeded more than once in 10,000 years (the 1:10,000 AEP annual rainfall), The methods used to estimate evaporation in the water retention pond, and The calculation of the quantity of water that will be evaporated in the exit stream of the mine ventilation system. Various aspects of these issues were raised in the Supervising Scientists submissions on the Jabiluka EIS and the PER. They were, however, raised in the context of issues that would need to be addressed at the detailed design stage of the project if the approval for mining were to be granted. The important issues at the EIS/PER stage are: (i) the acceptance of a design criterion, that the water retention system should capture and retain all water that could accumulate in a year where the annual rainfall is that which is not likely, on average, to be exceeded more than once in 10,000 years, and (ii) that adequate evidence is presented that this design is achievable. The Supervising Scientist reached the conclusion that such a design is achievable and that outstanding detailed technical issues could be resolved by the Supervising Authorities and the Supervising Scientist in the normal process of assessment and authorisation if approval for the project was given. This approach was endorsed by Environment Australia in its assessment of the EIS and PER. The above hydrological issues are addressed in this chapter to determine the basic parameters required for design of the water management system under current climatic conditions. Issues related to possible climate change are addressed in chapter 4 and design issues per se are addressed in chapter 5. 3.2 Determination of 1 in 10,000 year annual rainfall The design criterion adopted by ERA in the Draft EIS (ERA 1996) for the retention pond in the Total Containment Zone (TCZ) at Jabiluka was that it should be capable of retaining the runoff from the TCZ in a 1:10,000 AEP rainfall year as well as including a residual volume of water retained from previous years (ERA 1996, page 468). Thus the estimate used for the 1:10,000 AEP rainfall was considered an important issue for the success of the total containment strategy. 3.2.1 Choice of data sets The first issue that needs to be addressed in estimating the 1:10,000 AEP annual rainfall is the choice of data set(s) to be used in the analysis. Data are available for Jabiru airport, 18 km south of Jabiluka, for the period from 1971 until 1998, a relatively short data set, and for Oenpelli, about 25 km north east of Jabiluka, from 1911 until 1998. (For locations, see fig 2.1.) The records for all other meteorological data sites within 100 km are relatively short. Extensive data sets (of the order of 100 years) are available for Darwin, Katherine, Pine Creek and a number of other sites but they are all more than 200 km distant from Jabiluka.