Supervising Scientist Annual Report 2012-2013


ISSN: 0 158-4030
ISBN-13: 978-1-921069-22-2

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, as well as through the conduct of 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, with milling of stockpiled ore expected to continue through until 2020. Mining in Pit 3 ceased in December 2012 and the pit is currently in the process of being backfilled. A proposal to develop the Ranger 3 Deeps underground operation was referred under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) in January 2013. A decision was made in March 2013 that the proposal would be assessed at the EIS level. The proposal is not expected to impact on the closure of operations at Ranger. Mining and Milling are currently required to cease by 2021 with closure of Ranger by 2026.

During the year there were no reported incidents that resulted in any environmental impact to the surrounding environment. The extensive monitoring and research programs of the Supervising Scientist Division (SSD) confirm that the environment has remained protected through the period.

The 2012–13 wet season was one of the driest on record. This has significantly reduced water inventories on site and enabled a number of key projects to progress ahead of schedule. Following completion of mining in Pit 3 in early December 2012 progress has been made on the backfill of the pit in preparation for the transfer of tailings from the tailings storage facility (TSF) into Pit 3. Works will also commence in Q3 2013 on the close out of Pit 1 with the potential to remove Pit 1 from the process water catchment. This combined with the commissioning of a Brine Concentrator process water treatment plant in Q3/Q4 of 2013 will result in further reductions in process water inventory over the next few years.

As in previous years, the management of the TSF remains a focus. Capacity increases over the past few years combined with a contingency pumping system, a lower than average wet season, and the imminent commissioning of the Brine Concentrator process water treatment plant, have resulted in increased capacity to manage process water within the TSF over the coming 2013/14 wet season.

Monitoring programs by ERA, the Northern Territory Department of Resources and SSD continue to indicate that there is no evidence of seepage from the base of the Ranger tailings storage facility impacting on Kakadu National Park. ERA installed additional monitoring bores around the tailings storage facility during 2011 at the request of stakeholders, including SSD. Monitoring of these bores continued throughout 2012/13.

As reported previously, in 2011–12 ERA undertook pilot scale testing of its preferred brine concentrator technology for the treatment of process water. The positive conclusions from this test, including the findings from an ecotoxicological assessment conducted by the SSD, lead to the approval from ERA’s Board to install this technology on site. Construction of the brine concentrator is now complete and at the time of writing ERA are undertaking commissioning of the plant with a view to seeking approval from the Supervising Scientist for release of the treated water.

Works continue on the construction of an exploration decline into the Ranger 3 Deeps (R3D). To date approximately 1.6 km of decline and portal works have been completed. Exploratory drilling has commenced into the ore body with early results confirming the R3D resource. As discussed above, an EIS is currently in production for the development of the R3D ore body and is expected to be released to the public early 2014.

The 2012–13 wet season represents the third season for which continuous monitoring of pH, electrical conductivity (EC) and turbidity in Magela and Gulungul Creeks upstream and downstream of the Ranger mine has been the primary early warning monitoring method employed by the SSD. The monitoring stations are equipped with autosamplers that collect water samples triggered by in-stream events such as increases in EC or turbidity exceeding defined threshold levels. The SSD’s surface water monitoring results, together with explanatory notes, were posted weekly on the internet throughout the wet season. Overall, the water qualities measured in Magela and Gulungul Creeks for the 2012–13 wet season were comparable with previous wet seasons, with the results indicating that the aquatic environment in the creek has remained protected from mining activities.

In situ toxicity monitoring using fresh water snails in Magela and Gulungul Creeks upstream and downstream of the mine, with test organisms deployed in containers immersed in the creek water, is a biological-based method that complements the finding from the continuous monitoring. The measured responses of the snails during the 2012–13 wet season, combined with the results from monitoring of fish and macroinvertebrates conducted in the recessional flow period towards the end of the wet season, continue to confirm that the downstream aquatic environment remains protected from the effects of the mining of uranium at Ranger.

As noted in previous years, work is continuing on further enhancing interpretation of the results from the Supervising Scientist’s surface water monitoring program. Work to establish a quantitative relationship between the trigger value for Mg and exposure durations, was finalised during 2012 to a point such that an applicable trigger value can be derived for any given pulse duration and magnitude detected by the continuous water quality monitoring system. This work has been published in peer-reviewed international journals, and been presented to the Minesite Technical Committee with a view to instituting it as part of the regulatory regime for compliance in Magela Creek in the near future. This represents world’s leading practice in applying ecotoxicological derived limits to continuous monitoring data.

Determination of radionuclide levels in mussels from Mudginberri Billabong has been a continuing element of the SSD assurance monitoring program downstream of Ranger. The results from the most recent sampling and analysis conducted in October 2012 show that the levels of uranium and radium in mussels collected downstream of Ranger continue to pose no risk to human or ecological health.

The Jabiluka project remains in long-term care and maintenance. Agreement was reached during 2012 between ERA and traditional owners on rehabilitation of the remaining infrastructure on site. Dewatering of the Interim Water Management Pond (IWMP) commenced at the end of the 2012/13 wet season with a view to its removal during the 2013 dry season. Works are currently now underway to remove the pond and revegetate the site. SSD will increase its monitoring of the site over the next 2 wet seasons in response to the ground disturbance of the remedial activities.

The Nabarlek mine in western Arnhem Land was decommissioned in 1995 and the rehabilitation of this site remains under ongoing assessment. During the 2012 Uranium Equities Limited undertook limited exploration and rehabilitation activities at Nabarlek. No activities are planned for 2013. SSD participated in stakeholder inspections and audits of these activities and there were no significant environmental issues identified.

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. This project has now been completed. SSD continues to provide advice and assistance to the Director of National Parks on aspects relating to ongoing monitoring of the work.

The Alligator Rivers Region Technical Committee (ARRTC) continues to play a vital role in assessing the key knowledge required, and the robustness of the science used, to make judgements about the protection of the environment from the impacts of uranium mining. During the year ARRTC focused on the current ERA Closure Risk Assessment Project with a view of informing the revision of the Key Knowledge Needs. This work is ongoing and will evolve as Ranger approaches closure, informing both closure criteria and key gaps in knowledge.

Detailed outcomes from the Environmental Research Institute of the Supervising Scientist (eriss) research program 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.

During the reporting period, SSD provided advice to the Environment Assessment and Compliance Division of the Department on referrals submitted in accordance with the EPBC Act for proposed new and expanding uranium mines.

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 Governments. The Rum Jungle Technical Working Group comprises representatives from the Northern Territory Department of Resources, Northern Territory Department of Natural Resources, Environment, the Arts and Sport, Australian Government Department of Resources, Energy and Tourism, the Northern Land Council and SSD. SSD contributed to the work of the Rum Jungle Technical Working Group during the reporting period, including the selection of preferred rehabilitation strategies that have now formed part of a further submission for funding over the next 3 years.

In closing I offer my personal thanks to all the staff of the Supervising Scientist Division for their continued enthusiasm and efforts during the year. It is through the commitment and professionalism of the Division’s staff that the Division able to fulfil its role in ensuring environmental protection to such a highly respected level. In particular I would like to highlight the efforts of those staff who have departed after many years of service, including Joan Mount and Caroline Camilleri who have provided over 20 years of service to SSD, and Ann Webb who has been the mainstay in the preparation and publication of this report over many years. I would also like to recognise the significant contribution of both Dr David Jones who retired as the Director of eriss towards the end of 2012, and Mr Alan Hughes who is on long term leave and will retire from the position as Supervising Scientist early 2014. Alan leaves us as the second longest serving Supervising Scientist.


Richard McAllister
Acting Supervising Scientist

See also