Supervising Scientist Division

Letter of transmittal

Supervising Scientist Annual Report 2004–2005

Supervising Scientist, Darwin, 2005
ISBN 0 642 24395 6
ISSN 0 158-4030

Letter of transmittal

Hon Greg Hunt MP
Parliamentary Secretary to the Minister for the Environment and Heritage
Parliament House

20 October 2005

Dear Parliamentary Secretary

In accordance with subsection 36(1) of the Environment Protection (Alligator Rivers Region) Act 1978 (the Act), I submit to you the twenty-seventh Annual Report of the Supervising Scientist on the operation of the Act during the period of 1 July 2004 to 30 June 2005.

Yours sincerely


Dr A Johnston PSM
Supervising Scientist


Subsection 36(1) of the Environment Protection (Alligator Rivers Region) Act 1978 requires the Supervising Scientist to provide an Annual Report to Parliament on the operation of the Act and on certain related matters. The Act requires the following information to be reported:

Supervising Scientist's overview

The Supervising Scientist is responsible for the supervision, monitoring and audit of uranium mines in the Alligator Rivers Region as well as research into the possible impact of uranium mining on the environment of the region.

Energy Resources of Australia (ERA) operates the only active uranium mine in the region, the Ranger mine, and currently operates the Jabiluka project on a care and maintenance basis. The Nabarlek mine was decommissioned in 1995 and the adequacy of the rehabilitation of this site is under ongoing assessment.

In my previous Annual Report, I provided extensive information on the potable water contamination incident and the radiation clearance incidents that took place at the Ranger mine during 2003 and 2004. The Supervising Scientist’s reports on these incidents were tabled in Parliament on 30 August 2004. Following consideration of issues raised in the reports and my recommendations, the Minister for Industry, Tourism and Resources, the Hon Ian Macfarlane MP, wrote to ERA requiring the company to comply, within a specified timeframe, with a series of conditions under the Atomic Energy Act 1953.

A series of independent audits of the Ranger mine were commissioned by the Department of Industry, Tourism and Resources to assess ERA’s compliance with the Minister’s conditions. Following receipt of the audit reports, Mr Macfarlane wrote to ERA on 30 March 2005 to advise it that he had concluded that the company had, with the exception of the implementation of workplace safety standard AS4801, complied with all of the Minister’s conditions. ERA is required to meet the AS4801 standard by 30 September 2005.

In addition to the specific conditions required by the Minister under the Atomic Energy Act, the Minister advised ERA that he expected the company to comply with all of the recommendations made in my reports. By 30 June 2005, most of my recommendations had been implemented by ERA. However, I have commissioned an additional independent audit of the Radiation Safety Practices at the Ranger mine. The purpose of this audit is to examine the steps that ERA has taken to upgrade its radiation management system and, as a result, to address concerns about the radiation protection culture at Ranger. This audit is scheduled to occur in July 2005.

Four reportable incidents occurred at Ranger mine during 2004-05. One involved contamination of the compressed air circuit with ammonium diuranate originating from the process plant. An on-site investigation by staff from the oss concluded that the contamination was limited in extent and had not posed a threat to either the environment or human health. The remaining incidents were minor.

An important development at Ranger during the year was the submission and approval of an application by ERA to construct a water treatment plant. This plant has been designed to treat both pond and process water prior to its discharge from site. Commissioning of the plant is expected during November 2005. This plant will be an integral part of the water management system at Ranger for the remaining years of production and well into the closure and rehabilitation phase of Ranger operations.

Another issue of significance that was addressed in 2004-05 was the minimisation of groundwater seepage from tailings in Pit 1. There is a region in the south-eastern wall of the pit where the permeability is relatively high and could, if not managed, give rise to seepage of contaminants from the tailings if approval is given for deposition of tailings above the currently approved maximum height. Such an approval is being sought by ERA as part of a strategy to store additional tailings in Pit 1 as an interim measure until Pit 3 is ready for tailings deposition. During the year, therefore, ERA commenced construction of a seepage barrier in the region of higher permeability. The barrier is being constructed of locally derived clay-rich material supported and protected by a layer of waste rock armour. Geotechnical and geochemical testing of the materials used for construction indicates that the integrity of the barrier will be maintained over the long term.

The Supervising Scientist’s independent environmental monitoring program at the Ranger mine continued throughout 2004-05. Compliance with the water quality limits and guidelines throughout the wet season downstream from Ranger provided reassurance that the aquatic environment has not suffered any deleterious effects from mining during the year and the results of the biological monitoring programme confirm this.

Magnesium sulfate is the dominant surface water contaminant associated with the Ranger mine. Although this common salt is generally considered to be of very low toxicity, aquatic surveys in waterbodies on the Ranger site in the mid-1990s showed correlations between changes in macroinvertebrate community structure and increasing magnesium sulfate. This finding prompted a full ecotoxicological investigation. The results have shown that, surprisingly, magnesium does induce an adverse response in a number of species at quite low concentrations. We have also found, however, that these responses are significantly ameliorated by the presence of calcium and that, since calcium is also present at enhanced concentrations in waters leaving Ranger, the effect of magnesium is substantially reduced. A risk assessment has been carried out using monitoring data collected over the past twenty years and we have been able to conclude that, although effects may be observed on water bodies on the Ranger site, the risk to aquatic animals and plants in the waters of Magela Creek downstream from Ranger over the life of the mine has been negligible.

It is a requirement that radiological conditions on the final landform at Ranger will lead to a minimum of restrictions on use of the area by people. It will, therefore, be necessary to design the landform in a manner that minimises exposure to radon, a radioactive gas associated with uranium. Radon exhalation from soils is influenced by a number of factors such as soil moisture, soil porosity and the concentration of radium in the soil. A recently completed study has investigated the dependence of radon exhalation on these factors at Ranger and well-defined relationships have been determined for radon exhalation from different ground surface types. The results will be of great value in the design of the final landform at the rehabilitated site.

The Supervising Scientist’s routine monitoring programme for the Jabiluka site was modified during 2004-05. Jabiluka entered a long-term care and maintenance phase in 2003 and the site now poses a very low risk to the environment. For this reason, the Supervising Scientist’s water chemistry monitoring program at Jabiluka was reduced to monthly sampling for the 2004-05 wet season and the biological monitoring programme ceased. This reduced programme, coupled with those of ERA and the Northern Territory Government, is adequate to check on the continued stability of conditions at the Jabiluka site. The full programme can be implemented again at any time in the future if development occurs at Jabiluka. The results obtained in the reduced programme demonstrated that the quality of water entering Kakadu National Park from the site continued to be very good.

Assessment of the adequacy of decommissioning and rehabilitation of the Nabarlek mine site continued throughout 2004-05. Negotiations are ongoing on revised revegetation objectives and it is anticipated that agreement will shortly be reached on measures that will need to be taken to improve the condition of the site. Further work was undertaken to characterise the radiologically anomalous area prior to work being carried out to rehabilitate the area.

Finally, I would like to advise that I have decided to retire from my position as Supervising Scientist in October 2005. I have had a very rewarding career with the Supervising Scientist’s organisation in its various forms over the years and this has been largely due to the people with whom I have been privileged to work, both internally in my division and my department and externally in industry, government and more generally in the community. Many thanks to all of you. To those who continue to be charged with the protection of the people and the environment of the Alligator Rivers Region, I wish you every success.

Dr Arthur Johnston PSM
Supervising Scientist