eriss research summary 2012-2013

Supervising Scientist Division, 2013

Supervising Scientist Report 206

Preface

The Environmental Research Institute of the Supervising Scientist (eriss) is part of the Supervising Scientist Division (SSD) of the Australian Government’s Department of the Environment (DoE). eriss provides specialist technical advice to the Supervising Scientist on the protection of the environment and people of the Alligator Rivers Region (ARR) from the impact of uranium mining. Its major function is to conduct research into developing leading practice methodologies for monitoring and assessing the impact of uranium (U) mining on water and air (transport pathways) and soil, and on the bushfoods that are consumed by the local Indigenous people. This research spans the operational, decommissioning and post rehabilitation phases of mining.

eriss also applies its expertise to conducting research into the sustainable use and environmental protection of tropical rivers and their associated wetlands, and to undertaking a limited program of contract research on the impacts of mining elsewhere in the north Australian tropics.

The balance and strategic prioritisation of work within the uranium component of eriss’s project portfolio are defined by Key Knowledge Needs (KKNs) developed through consultation between the Alligator Rivers Region Technical Committee (see ARRTC membership and function in Appendix 2), the Supervising Scientist, Energy Resources of Australia Ltd (ERA) and other stakeholders. The KKNs are subject to ongoing review by ARRTC to ensure their currency in the context of any significant changes that may have occurred in U mining related activities and issues in the ARR.

Not all of the KKN research areas (Appendix 3) are able to be covered by eriss, since not all of the required disciplines are available within the Institute. To address these particular gaps, collaborative projects are conducted between eriss and researchers from other organisations, and consultants are commissioned by eriss and others to undertake specific pieces of work. For example, KKN projects related to detailed hydrogeology or tailings management on the Ranger lease are conducted and reported separately by consultants engaged by ERA. A more complete picture of the scope of research work that is conducted by all parties can be obtained by referring to the minutes that are produced for the meetings of ARRTC.

This report documents the monitoring and research projects undertaken by eriss over the 2012–13 financial year (1.7.12 to 30.6.13). The report is structured according to the five major topic areas in the KKN framework, noting that this year there are no papers for Nabarlek.

  1. Ranger – current operations
  2. Ranger – rehabilitation
  3. Jabiluka
  4. Nabarlek
  5. General Alligators Rivers Region

Of the 30 or active projects during 2012–13, the majority (>95%) were addressing issues associated with the current operational phase and/or proposed rehabilitation and post-rehabilitation phases of Ranger mine.

eriss continued its chemical and biological off-site monitoring programs for assessing impacts from the current operations at Ranger. Research associated with current operations continued its focus on water quality issues. Research on the toxicity of manganese to local freshwater species was completed, with the results being used to derive a site-specific trigger value (to protect at least 99% of species) for manganese of 75 mg/L. Also, an interim site-specific trigger value (to protect at least 99% of species) for ammonia, of 0.7 mg/L as total ammonia nitrogen, was derived based on the latest international scientific knowledge. Both trigger values are expected to be incorporated into the regulatory framework during 2013–14, while the ammonia value will also be updated in 2015 following the generation of toxicity data for local freshwater species.

Research related to rehabilitation at Ranger remains a key focus at eriss. The trial landform studies continued in 2012–13, with a focus on the processing and reporting of solutes data (up to 2011–12) and continued updating of hydrology and bedload yields. Bedload yields from the study plots continued to decline with time. Similarly, for the solutes, major ion and uranium concentrations have also declined over time. Other key rehabilitation-related research to be progressed include: (i) further refinement and testing of the landform evolution models that are being used to assess the stability of the rehabilitated landform over both short and long-term timeframes; (ii) continued development of water quality closure criteria for solutes and turbidity/suspended sediment in billabongs; (iii) at a broader spatial scale, mapping of vegetation and associated annual variation on the Magela floodplain (from 2010 onwards) using high resolution multispectral satellite data, to inform a baseline from which any landscape scale impacts of mine rehabilitation could be detected; and (iv) commencement of the Ranger rehabilitation and closure ecological risk assessment, in collaboration with ERA.

Jabiluka is in long-term care and maintenance and the current work of the Supervising Scientist is focused on maintaining a routine continuous monitoring program for flow and electrical conductivity downstream of the formerly disturbed area. In 2012–13, these data were acting as a baseline prior to the decommissioning and rehabilitation of the interim water management pond at the Jabiluka site during the 2013 dry season. Radiological monitoring and assessment continued at the El Sherana airstrip radiological containment in the South Alligator River Valley, with the primary purpose to assess the containment’s performance through time, including whether site radiological conditions are stable. Uranium Equities Ltd continues to pursue exploration activities on the Nabarlek lease. Environmental monitoring and assessment for this site is being conducted via Mining Management Plans submitted by the company to the Northern Territory Government.

The key non-uranium mining related external activity for 2012–13 was the involvement of several eriss staff in the current revision of the Australian and New Zealand Guidelines for Fresh and Marine Water Quality. Details of the involvement in the Water Quality Guidelines revision are provided in the Supervising Scientist 2012–13 Annual Report.

Three maps (following this Preface) provide the regional context for the locations that are referenced in the research papers. Map 1 shows Kakadu National Park and the locations of the Ranger mine, Jabiluka project area, the decommissioned Nabarlek mine, and the South Alligator River valley. A schematic of the Ranger minesite is provided for reference in Map 2. Map 3 shows the locations of billabongs and other waterbodies used for the aquatic ecosystem monitoring and atmospheric and research programs for assessing impacts from Ranger mine.

For additional information, readers are referred to the annual publications list (Appendix 1) that details all of the material published, and conference and workshop papers presented, by eriss staff in 2012–13.