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
7 The risk assessment included a contingency situation in which the accumulated runoff from the catchment of the water storage pond at Jabiluka exceeds the capacity of the pond and the excess water from the Total Containment Zone is diverted and allowed to flow freely to Swift Creek. Also assessed is the risk to the environment associated with structural failure of the water storage pond arising from overtopping of the pond, static failure of the constructed embankment, or the occurrence of a severe earthquake. Risks associated with exceeding the available water storage capacity Estimates have been made of radiation exposure of members of the public resulting from an exceptional Wet season in which the storage capacity of the water retention pond is exceeded and the excess water is discharged to Swift Creek. The probability that any member of the public would receive a radiation dose of 20 Sv on one occasion during the 30 year life of the mine would be less than 1 in 10,000. The annual dose limit recommended by the International Commission on Radiological Protection for members of the public is 1000 Sv per annum. The conclusion is, therefore, that the water management system proposed by ERA for Jabiluka is one that poses an insignificant radiological risk to people living in the vicinity of the mine and consuming traditional foods obtained from the waterbodies downstream from the mine. Estimates have also been made of probable effects on aquatic animals resulting from an exceptional Wet season in which the storage capacity of the water retention pond is exceeded and the excess water is discharged to Swift Creek. The assessment included both radiological and chemical exposure. The conclusion reached is that, under normal circumstances, no effect on aquatic animals living in Swift Creek downstream from the Jabiluka mine would be expected to occur even when the volume of excess water discharged is that with an exceedence probability of 1 in 50,000 over the life of the mine. If the discharge results from an extreme rainfall event with an exceedence probability much greater than 1 in 100 at the end of a Wet season in which the rainfall has an exceedence probability of greater than 1 in 1000, some adverse effects may occur in invertebrates, but adverse effects on fish would not be expected. Any adverse effects on invertebrates would be very short-lived. Risks associated with overtopping the water storage pond The probability of the pond overtopping in the absence of contingency measures has been estimated to be 5 in 10,000. It was assummed that overtopping would lead to complete structural failure of the pond embankment. The estimated radiation exposure of members of the public arising from such an event is about 150 Sv. Thus, even for this catastrophic event, the expected dose received by members of the public would not be greater than 15% of the annual limit recommended by the International Commission on Radiological Protection. The uranium concentration in Swift Creek following overtopping of the retention pond and subsequent total failure of the dam walls would be expected to give rise to adverse effects on some aquatic invertebrates in the Creek but adverse effects on fish would not be expected. There is a risk of about 5 in 10,000 that, following overtopping of the water retention pond, an area that is about 1% of the Magela floodplain would experience some adverse effects on aquatic animals. Fish and many other species would not be affected. Between about 2 km2 and 20 km2, adverse effects may persist but beyond 20km2 no effects should be observed. In addition, any effects will be transitory and the system would fully recover following flushing by the natural waters of the Magela Creek.
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