Supervising Scientist Annual Report 2009-2010

2010

Supervising Scientist, 2010
ISSN 0 158-4030
ISBN-13: 978-1-921069-13-0

Supervising Scientist's overview

The Supervising Scientist plays an important role in the protection of the environment of the Alligator Rivers Region of the Northern Territory through the supervision, monitoring and audit of uranium mines in the Region, as well as research into the possible impact of uranium mining on the environment of the Region.

Ranger is currently the only operational uranium mine in the Region, and is owned and operated by Energy Resources of Australia Ltd (ERA). Production commenced at Ranger in August 1981, and current plans will see mining of the Ranger 3 deposit cease in 2012 with milling of stockpiled ore expected to continue through until 2020. Recent proposals by ERA to include a heap leach facility at Ranger have not affected the current mining and milling operations timetable but could potentially increase production over the same period.

As the time of mine closure and rehabilitation draws closer, the work of the Supervising Scientist includes a focus on these themes as well as on current operational issues. Staff have been engaged with stakeholders in discussions and research activities associated with rehabilitation and closure.

Staff of the Division remain active in ongoing supervision, inspection and audit, radiological, biological and chemical monitoring, and research activities in relation to both present and past uranium mining activities in the Region. Significant work has continued in developing improvements to the Supervising Scientist's surface water monitoring program. This program is relevant to both the operational and rehabilitation phases of mining.

At Ranger mine the 2009-10 wet season was around average with rainfall of 1596 mm. During the year there were no reported incidents that resulted in any environmental impact off the immediate minesite. The extensive monitoring and research programs of the Supervising Scientist Division confirm that the environment has remained protected through the period.

Over the past year ERA achieved a small reduction in the process water volumes stored on site by reducing additions to the process water systems through measures including reducing the area of surface runoff catchment reporting to it. However, delays in commissioning of the process water treatment facility and deferred implementation of a proposed enhanced evaporation program mean that the process water inventory at the mine remains a focus.

Monitoring programs by ERA, the NT Department of Resources and SSD continue to indicate that there is no evidence of seepage from the base of the Ranger tailings storage facility (TSF) impacting on Kakadu National Park. ERA has installed additional monitoring bores around the TSF at the request of stakeholders, including SSD.

The SSD surface water quality monitoring program continues to be improved with refinements to the operation of continuous monitoring of pH, electrical conductivity (EC) and turbidity in Magela and Gulungul Creeks upstream and downstream of Ranger mine. Continuous monitoring results indicate that water quality variations, both natural and mine-related, can occur on a time base measured in hours rather than days. This method of monitoring has therefore proven to be superior to the statutory weekly grab sampling technique that is currently employed.

The SSD monitoring stations have also been equipped with autosamplers that collect water samples triggered by in-stream events such as increases in EC or turbidity exceeding defined threshold levels. This has enhanced the capability of the monitoring program by allowing collection of samples outside of normal working hours or when conditions in the creeks are unsafe for manual grab sampling.

During April 2010 there were occasions where EC spikes in Magela Creek triggered the SSD autosampler at the downstream monitoring station. Subsequent analysis of the samples confirmed that the cause was elevated levels of magnesium sulfate in the water and that these events did not contain significantly elevated levels of uranium or radium. It was concluded that the anomalous EC readings were mine-related, having resulted from elevated salt levels in Retention Pond 1.

The principal biologically-based toxicity monitoring approach for 2009-10 was in situ monitoring using fresh water snails, with test organisms deployed in containers floating in the creek water. This program was extended from Magela Creek to include Gulungul Creek during the 2009-10 wet season.

Determination of radionuclide levels in mussels from Mudginberri Billabong has been a continuing element of the SSD monitoring program downstream of Ranger. Results for 2009-10 are similar to previous years and it is concluded that the consistently low levels of uranium and radium in mussels collected downstream of Ranger pose no risk to human or ecological health.

Ecotoxicology research programs in progress include determination of responses for a variety of organisms to pulse event durations for a range of magnesium concentrations. Previous work has confirmed a strong correlation between magnesium and EC in Magela Creek. Use of EC as a surrogate for magnesium has the obvious advantage of being suitable for direct measurement rather than relying on sampling and analysis at a remote laboratory.

An eight hectare trial landform was constructed by ERA during late 2008 and early 2009 adjacent to the north-western wall of the tailings storage facility at Ranger mine. SSD is involved in erosion studies on the trial landform to assist in longer term modelling of the performance of ultimate landform created during rehabilitation of the site.

The Jabiluka project remains in long-term care and maintenance, and the next stage of the project is a matter for discussion between ERA and the area's traditional owners.

The Nabarlek mine in western Arnhem Land was decommissioned in 1995 and the rehabilitation of this site remains under ongoing assessment. During the year Uranium Equities Limited undertook exploration and rehabilitation activities at Nabarlek. SSD participated in stakeholder inspections and audits of these activities and there were no significant environmental issues identified. Detailed research outcomes of the Environmental Research Institute of the Supervising Scientist (eriss) are published in journal and conference papers and in the Supervising Scientist and Internal Report series. Highlights of this work are described in this annual report.

In May 2006, the Australian Government announced funding to undertake rehabilitation of former uranium mining sites in the South Alligator River Valley in the southern part of Kakadu National Park. Most of the work associated with this project has now been completed. SSD continues to provide advice and assistance to the Director of National Parks as the rehabilitation works are completed and post works monitoring progresses.

The Alligator Rivers Region Technical Committee (ARRTC) continues to play a vital role in assessing the science used in making judgements about the protection of the environment from the impacts of uranium mining. Dr Gavin Mudd was appointed to ARRTC as a technical member representing environmental non-government organisations. Dr Carl Grant and Professor Peter Johnston resigned as independent members during 2009-10 and replacement members were appointed in early 2010-11. The new members are Professor David Mulligan and Mr Andrew Johnston. Their areas of expertise are in plant ecology and rehabilitation and in radiation protection respectively.

During the reporting period, SSD provided advice to the Approvals and Wildlife Division of the department on referrals submitted in accordance with the EPBC Act for proposed new and expanding uranium mines, including the following projects:

  • Olympic Dam Expansion, SA
  • Ranger Mine Heap Leach proposal, NT
  • Beverley North Project, SA
  • Yeelirrie WA

Funds were provided in the 2009-10 Federal Budget for a four-year program to progress and implement environmental maintenance activities, conduct appropriate environmental monitoring programs and develop contemporary site rehabilitation strategies at Rum Jungle under a national partnership agreement between the Northern Territory and the Australian Government. The Rum Jungle Technical Working Group (RJTWG) comprises representatives from the NT Department of Resources, NT Department of Natural Resources, Environment, the Arts and Sport, Australian Government Department of Resources, Energy and Tourism, the Northern Land Council and SSD. SSD has contributed to the work of the RJTWG during the reporting period.

Finally, I would like to offer my personal thanks to all the staff of the Supervising Scientist Division for their continued enthusiasm and efforts during the year. The commitment and professionalism of the Division's staff remain vital factors in the Division being able to fulfil its role in environmental protection.

(signed)

Alan Hughes
Supervising Scientist

See also