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

83 tailings, and other procedures constituting the tailings treatment, are the subject of a current research program being undertaken by the mining company. The final fully developed tailings management procedure will be approved only after the Supervising Scientist is satisfied as to its efficacy. The primary solutes of environmental concern in the tailings at Jabiluka are magnesium, sulphate, manganese, uranium, and radium. Some of the properties of these elements, which are needed to predict downstream concentrations are listed below in table 6.3.1. It is well known that the availability of metals in solution is a function of pH, with metal solubility generally decreasing with increases in pH. The addition of cement to the tailings paste will increase the pH, and a pH of up to 10 could be expected in Jabiluka cemented tailings. Also, it could be expected that the addition of cement to the tailings will bind some of the solutes to the cured tailings matrix. Cincilla et al (1997) suggest that the geochemistry of tailings paste can be readily modified to improve its environmental behavior. Further discussion of these aspects is given in the Jabiluka PER and in a report by Waite et al (1998). In addition, further investigations will be carried out as part of the ERA research program alluded to above. The values of tailings solute concentrations in table 6.3.1 have been used in examples given in section 6.3.4 because they are conservative. Table 6.3.1 Model parameters for important solutes in the Jabiluka tailings Solute Concentration in Tailings* Retardation Factor, Rf Distribution Coefficient, Kd Uranium 15Bq/L 20 1 Radium 15Bq/L 100 5 Magnesium 5,000mg/L 1 0 Sulphate 20,000mg/L 1 0 Manganese 500mg/L 30 1.5 * Concentrations have been estimated using data for the geologically similar Ranger tailings In table 6.3.1, Kd is the distribution co-efficient (see Eq (1) in Kalf & Dudgeon 1999) which describes the amount of the solute which will be retarded through absorption, precipitation/dissolution and complex ion-exchange reactions in the aquifer. The value of Kd is linearly related to the retardation factor, Rf, of the solute used in the model. 6.3.4 Predicted downstream concentrations of tailings derived solutes The groundwater modelling indicated that the upward component of groundwater flow is weak in both the groundwater movement to the east towards Swift Creek and to the west towards the Magela floodplain. The flow was found to be predominantly horizontal, implying that only a small fraction of the groundwater in the deeper aquifer would be accessible to surface waters. All of the calculated groundwater concentrations discussed below refer to concentrations in the deep aquifer. Surface aquifer concentrations arising from the tailings repositories will be much lower. Regular annual flushing of the surface aquifer in the Wet season will ensure that there is a high degree of additional dilution and no build-up of contaminants in this zone. Sources of the modelled solutes were the tailings silos for groundwater flows to the east, and the tailings deposited in the mined out stopes for flow to the west (see fig 6.3.3). As a test, Monte Carlo calculations were run initially by Kalf and Dudgeon (1999) for 255, 500 and 1000 random selections of the values of the variables. When little difference was found


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