Territory Stories

Assessment of the Jabiluka Project : report of the Supervising Scientist to the World Heritage Committee

Details:

Title

Assessment of the Jabiluka Project : report of the Supervising Scientist to the World Heritage Committee

Creator

Johnston, A.; Prendergast, J. B.; Bridgewater, Peter

Collection

E-Publications; E-Books; PublicationNT; Supervising Scientist Report; 138

Date

1999

Location

Alligator Rivers Region

Table of contents

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.

Language

English

Subject

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

Publisher name

Environment Australia

Place of publication

Canberra (A.C.T.)

Series

Supervising Scientist Report; 138

Format

1 volume (various pagings) : illustrations, maps

File type

application/pdf

ISBN

642243417

Use

Copyright

Copyright owner

Environment Australia

License

https://www.legislation.gov.au/Details/C2019C00042

Parent handle

https://hdl.handle.net/10070/264982

Citation address

https://hdl.handle.net/10070/462402

Related items

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

Page content

10 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 at Ranger 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 10-9m/sec is desirable. Based upon the research carried out on Ranger tailings, it is concluded that 99% of uncemented tailings in the silos at Jabiluka would have a permeability of less than 10-9m/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 permeabilities which are 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. Predicted concentrations of solutes in the environment Modelling of the concentrations of solutes in the deep aquifer east of the tailings repositories in the direction of Swift Creek predicts that, after 200 years, sulphate concentrations should not exceed 20 mg/L even at distances as short as 100 m from the repositories. Uranium is not expected to move more than 50 m in 1000 years and for radium this distance is 15 m. The maximum distance moved by uranium under the most extreme (and very low probability) scenario considered in the Monte Carlo analysis is 300 m. Concentrations of uranium and radium at these distances will be negligible compared to naturally occurring concentrations. The transport of solutes to the west of the repositories is expected to be more rapid because of the higher permeability of the schists compared to that of the sandstone. Monte Carlo calculations indicate a probable migration distance of 500 m after 200 years for non-reactive solutes including sulphate, although greater distances are possible. The tailings derived solutes would be entering an area of already very poor quality water where natural sulphate concentrations are in the range 1500 7000 mg/L so that the impact of the migration of water from the tailings repository would be negligible. In addition, the floodplain is underlain by low permeability clays which act to limit any potential upflow of the groundwater into surface waters. The Monte Carlo calculations indicate that uranium is likely to travel up to 200 m in a westerly direction in about 1000 years at which point the concentration would be reduced to less than 1 mBq/L, a concentration that is significantly less than natural concentrations in the region. The calculations show that migration of uranium by up to 1200 m is


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