Alligator Rivers Region Technical Committee...

Alligator Rivers Region Technical CommitteeMeeting 30

21 – 22 May 2013

Meeting Summary

Alligator Rivers Region Technical Committee - Meeting 30Agenda

Tuesday, 21 May 2013 (0900 -1700)1. Preliminary Session (Chair)

1.1 Welcome and Introductions1.2 Apologies and Observers1.3 Correspondence1.4 Conflict of Interest Declarations1.5 Governance

2. ARRTC29 Outcomes (Chair)

2.1 ARRTC29 - Summary Record2.2 ARRTC29 - Actions Arising

3. Stakeholder Reports3.1 Uranium Equities Ltd - Nabarlek (Ms Taylor)3.2 Environment NGOs (Dr Mudd)3.3 Department of Mines and Energy (Mr Ball)

- Regulatory decisions and related science3.4 Northern Land Council (Mr Thompson)3.5 Supervising Scientist (including Monitoring) (Mr McAllister)3.6 Parks Australia (South Alligator Valley) (Ms Morgan)

4 Research Reports4.1 Supervising Scientist Division

4.1.1 Proposed eriss 2013-14 research program (Dr van Dam)4.1.2 SSD publications since ARRTC29

4.2 Energy Resources of Australia Ltd4.2.1 ERA operations/ ITWC update (Dr Sinclair)4.2.2 ERA publications since ARRTC29

Wednesday, 22 May 2013 (0900 - 1700)

5. Strategic Overview (ERA/eriss)

5.1 Status of research informing closure criteria5.2 Initial assessment of the geomorphic stability of the conceptual rehabilitated Ranger landform5.3 Status of Pit#1 rehabilitation and final landform5.4 Rehabilitation-Closure Risk Assessment Outcomes5.5 KKN revision status 5.6 ARRTC Summary Discussion

6. Other Business

7. Next Meeting

ARRTC29 Meeting Summary of 21

AttendanceMembersDr Simon Barry Independent Scientific Member and ChairpersonProf Paul Boon Independent Scientific MemberProf David Mulligan Independent Scientific MemberProf Colin Woodroffe Independent Scientific MemberMr Andrew Johnston Independent Scientific MemberDr Gavin Mudd Environment NGO stakeholder memberDr Greg Sinclair Energy Resources of Australia Ltd Mr Adam Thompson Northern Land CouncilMr Russell Ball NT Department of Mines and Energy (Day 2 only)Mr Richard McAllister A/g Supervising ScientistMr Stuart Paul Parks Australia DivisionApologiesDr Jenny Stauber Independent Scientific MemberMs Jane Coram Independent Scientific MemberMs Melissa Taylor Uranium Equities Limited Ms Anna Morgan Parks Australia DivisionMr Justin O’Brien Permanent Observer - Gundjeihmi Aboriginal CorporationPresenters/ObserversMr Peter Waggitt NT Department of Mines and Energy Ms Sally Strohmayr NT Department of Mines and EnergyMs Shelly Iles Energy Resources of Australia Ltd Ms Sharon Paulka Energy Resources of Australia Ltd Dr Ping Lu Energy Resources of Australia Ltd Dr Graeme Esslemont Energy Resources of Australia LtdMr Thomas Marshall Energy Resources of Australia LtdDr Rick van Dam Environmental Research Institute of the Supervising ScientistDr Che Doering Environmental Research Institute of the Supervising ScientistDr Andreas Bollhöfer Environmental Research Institute of the Supervising ScientistDr Chris Humphrey Environmental Research Institute of the Supervising ScientistDr Amy George Environmental Research Institute of the Supervising ScientistDr Renée Bartolo Environmental Research Institute of the Supervising ScientistDr Mike Saynor Environmental Research Institute of the Supervising ScientistDr Wayne Erskine Environmental Research Institute of the Supervising ScientistDr Andrew Harford Environmental Research Institute of the Supervising ScientistMs Kate Turner Environmental Research Institute of the Supervising ScientistMr John Lowry Environmental Research Institute of the Supervising ScientistSECRETARIATMr Scott Parker Office of the Supervising Scientist Ms Shannon Traut Office of the Supervising Scientist


1 Preliminary Session1.1 WELCOME AND INTRODUCTIONSThe Chair (Dr Barry) welcomed members to the 30thth meeting of the Alligator Rivers Region Technical Committee (ARRTC). Mr Parker provided members with a facilities and safety briefing. Dr Barry noted Mr Hughes is on long term leave pending his retirement and Mr McAllister is currently acting Supervising Scientist until September this year. ARRTC acknowledged Mr Hughes’ significant contribution to the protection of the Alligator Rivers Region environment as Supervising Scientist and in previous roles with the NT Government. Dr Barry noted that Dr Stauber has fallen ill and may not be able to attend the meeting. ARRTC noted that the meeting agenda structure has been revised in line with the changes agreed last meeting.

ARRTC30-1: ARRTC acknowledged Mr Hughes’ significant contribution to the protection of the Alligator Rivers Region through his work as Supervising Scientist and in previous roles within the NT Government.

1.2 APOLOGIESApologies from the following members were noted:

Dr Jenny Stauber Independent Scientific Member (sick)Ms Jane Coram Independent Scientific MemberMs Melissa Taylor Uranium Equities LimitedMs Anna Morgan Parks AustraliaMr Justin O’Brien GAC (permanent observer)

1.3 CORRESPONDENCEThe following correspondence was noted.

Outgoing - Letter to Minister Burke – ARRTC29 outcomes (30 April 2013)Incoming - Ministerial response pending

1.4 CONFLICT OF INTEREST DECLARATIONSNo conflicts of interest were declared. Dr Barry advised that he is currently contractually engaged to provide technical services as part of the review of the National Water Quality Guidelines being managed by eriss. He also noted that CSIRO is currently engaged by Energy Resources of Australia Ltd on a range of technical and rehabilitation related projects, and is working collaboratively with eriss on a sediment toxicity project. Dr Mudd advised that he is contractually engaged by Gundjeihmi Aboriginal Corporation to provide scientific and technical advice on a range of water and rehabilitation related issues. Prof Mulligan noted that QU CMLR will be assisting SSD in undertaking a number of Unmanned Aerial Vehicle (UAV) demonstration flights in June 2013.

1.5 GOVERNANCEMr Parker advised that the draft Terms of Engagement document provided in the meeting papers has been revised based on advice from DSEWPaC Legal and comments from a number of members including Energy Resources of Australia Ltd and Geoscience Australia. Mr Parker noted that a number of members have already advised they have no concerns with signing the document once finalised. It was noted the draft document will be finalised once comments have been received from CSIRO. ARRTC agreed that the draft Terms of Engagement should be finalised as soon as possible out-of-session to minimise any potential impacts on the Committee’s work going forward. It was also noted that, in addition to the Terms of Engagement, it is currently proposed that observers at ARRTC meetings will be required to sign deeds of non-disclosure to further ensure confidential information provided at ARRTC meetings is appropriately protected. It was noted that Commonwealth and NT government officials are already subject to non-disclosure obligations under their respective codes of conduct. ARRTC noted that all information from ERA provided to this and future ARRTC meetings is deemed to be confidential and cannot be disclosed to any third party or used for any other purpose than what it was provided for, without express written permission from ERA. It was also noted that other industry members should clearly mark (or otherwise identify to the ARRTC Secretariat) all confidential information provided to ARRTC. It was also noted that industry members will absent themselves from presentations from other industry members as per the protocol agreed at ARRTC29.

ARRTC30-2: ARRTC agreed that the draft ARRTC Terms of Engagement should be finalised out-of-session as soon as possible.

Mr Parker advised that he had sought advice from his legal area regarding the question raised at ARRTC29 regarding whether shares in uranium companies operating in the Alligator Rivers Region held by a member, their partner or in a family trust would constitute a conflict of interest. He advised the general view is that, in addition to complying with the relevant clauses in the Environment Protection (Alligator Rivers Region) Act 1978 pertaining to disclosure of members’ pecuniary interests, members should obtain their own legal advice regarding the implications of such share holdings given their particular circumstances.

2 ARRTC29 Outcomes2.1 ARRTC29 - SUMMARY RECORDThe ARRTC29 draft Meeting Summary was approved without amendment.


2.2 ARRTC29 – ACTIONS/OUTCOMESAction/Outcome Status

Carried over ARRTC27-4 ARRTC requested Ms Paulka to seek agreement from UEL to provide closure criteria and Hydrogeological review reports to Prof Mulligan, Dr Mudd and Mr

Johnston.ARRTC Secretariat to follow up with UEL. Noted these issues are covered in UEL’s meeting report.

ARRTC27-5 ARRTC agreed that UEL be invited to submit a proposal to amend the (Nabarlek) KKN and that ARRTC then consider based on the evidence that has been provided to support this.

ARRTC Secretariat to follow up with UEL. Items in red were added at ARRTC30

ARRTC28-18 ARRTC agreed that ERA and SSD should undertake further work as part of the proposed risk assessment process to draft a risk based framework for prioritising the KKNs associated with the decommissioning and rehabilitation phases at the Ranger mine. ARRTC agreed members will be involved where possible in person by or email.

ARRTC agreed this action is complete.

ARRTC29ARRTC29-1 ARRTC commended Dr David Jones on his outstanding contribution to improving the level and quality of scientific understanding of the impacts of uranium

mining on the environment of the Alligator Rivers Region.Completed

ARRTC29-2 ARRTC agreed the Chair would formally record ARRTC’s recognition of Dr Jones’ contribution in his letter to the Minister following the meeting. CompletedARRTC29-3 Mr Parker to provide clarification as to whether shares held by partners of ARRTC members or in family trusts of which the member is a beneficiary, constitute

a potential conflict of interest.Completed

ARRTC29-4 Secretariat to circulate the final draft Terms of Engagement out-of-session in early 2013. CompletedARRTC29-5 ERA to include details on the effectiveness and associated water quality impacts associated with the levee in its operational reports to future ARRTC

meetingsAddressed this meeting - Completed

ARRTC29-6 ERA to provide details on any measurements of pore moisture in the wall of Pit#3 to next meeting. Dr Sinclair advised that monitoring shows there has been no further movement in the Pit#3 wall

ARRTC29-7 ARRTC commended Dr Smith and ERA on their excellent work to date in developing approaches for integrating traditional indigenous knowledge into the rehabilitation and closure planning processes for Ranger.

Completed

ARRTC29-8 Dr Smith to provide ARRTC members with copies of his other papers on approaches for integrating traditional indigenous knowledge into the rehabilitation and closure planning processes.

Completed

ARRTC29-9 Parks Australia to provide further details on the groundwater and vegetation monitoring programs for the El Sherana containment including any relevant reports and data to next meeting.

Addressed this meeting - Completed

ARRTC29-10 ARRTC agreed that members will clearly identify in their reports and presentation to each meeting those scientific issues relating to operational or regulatory decision making on which they seek ARRTC’s views.

Completed

ARRTC29-11 ERA to provide a presentation on Pit#1 rehabilitation status and proposed final landform to next meeting. Addressed this meeting - CompletedARRTC29-12 ARRTC thanked Prof Hart for his presentation and commended the Working Group on its work. CompletedARRTC29-13 ERA/GAC to provide copy of the ISWWG report and recommendations to ARRTC members once it has been finalised. CompletedARRTC29-14 ARRTC thanked Dr Sigda and Dr Kozak for their presentations and commended Interra on the quality of the work undertaken to date. CompletedARRTC29-15 ARRTC noted Dr Toll is leaving ERA and thanked him for his valuable contribution to the work of the Committee. CompletedARRTC29-16 ARRTC noted the proposed research scope developed by Dr George and Ms Valdron-Clark and requested that a more detailed project proposal be provided to

next ARRTC meeting.Addressed this meeting - Completed

ARRTC29-17 ARRTC agreed that further work under KKN 3.1.2 be placed on hold pending the outcomes of the risk assessment in 2013. CompletedARRTC29-18 ARRTC commended ERA and SSD on their cooperative working arrangements to date and the high quality of their reports and presentations. CompletedARRTC29-19 ARRTC agreed that, prior to each meeting, the Secretariat will circulate a table listing the KKNs under which presentations will be provided, and that members

will highlight any other KKNs on which they would also like presentations.Completed

ARRTC29-20 ERA to provide further information on the status of research informing the development of closure criteria for Ranger to next meeting. Addressed this meeting - CompletedARRTC29-21 ARRTC noted that resource constraints will continue to be an issue for SSD and that ongoing prioritisation of research effort will be required. CompletedARRTC29-22 ARRTC agreed to establish a new standing agenda item named “Strategic Overview” under which the status of work under each KKN against agreed

milestones will be reported.Completed

ARRTC29-23 ERA to provide members with details of the proposed approach for the KKN risk assessment workshop (including dates) out of session. CompletedARRTC29-24 ARRTC agreed that independent scientific members are able to contacted out-of-session if required and to explore opportunities for making better use of

individual members’ scientific expertise.Completed

ARRTC29-25 ARRTC agreed the next meeting should be held in last week of May 2013 to allow time for the outcomes from the KKN risk assessment process to be considered.

Completed

ARRTC30-3: ARRTC agreed the Secretariat will follow up actions ARRTC27-4 and ARRTC27-5 (as amended) with Ms Taylor out-of-session.


3 Stakeholder Reports3.1 URANIUM EQUITIES LTD (NABARLEK) (MS TAYLOR)Ms Taylor was unable to attend the meeting but tabled an update report on behalf of UEL. Key points are summarised below.Exploration - UEL remains committed to the region and has signed an agreement with Cameco to acquire 100% of the West Arnhem JV (exploration areas immediately surrounding the Nabarlek ML). Exploration in 2012 was suspended due to the ongoing negotiations with Cameco and 2013 exploration programs were curtailed due to the current financial climate.Rehabilitation of Legacy Areas - Wet Season Program 2012-13 - UEL undertook two weed spraying campaigns during the 2012-13 wet season and planted 2,750 tubestock in February 2013 in the sewage, old camp, waste rock dump and plant run-off areas.Closure Criteria Development - Draft Closure Criteria – UEL closure obligations are outlined in section 5 of the Nabarlek Rehabilitation and Closure Plan and relate to infrastructure (to be removed as agreed), the Radiological Anomalous Area (contamination to be removed to a pre-mining background dose rate of 1.7µG/h), surface and groundwater (surface water currently acceptable and groundwater being reviewed as part of the hydrogeological review) and revegetation and weeds (criteria to be agreed by stakeholders)Infrastructure/RAA – The Nabarlek Plant Infrastructure Rehabilitation Plan and Nabarlek RAA Rehabilitation Plan were submitted to NTDME in 2012 and comments were received from NTDME and SSD. UEL is unable to proceed with planning work at this stage due to market conditions.Groundwater - A groundwater data review was conducted early in 2011 to collate all historic collected groundwater data into a single database. A Hydrogeological Assessment, Monitoring Data Review and Risk Assessment was undertaken in 2012 to develop and document a robust understanding of the groundwater system at the Nabarlek site. NT DME has approved the report and noted that further work will be required to establish closure criteria.

Revegetation Closure Criteria – UEL proposed approach involves adapting eriss monitoring program (2003-04) to suit criteria and stakeholder requirements and developing closure criteria in consultation with Traditional Land Owners. The fundamental criterion for measuring success of rehabilitation is confirmation by TOs that rehabilitation blends in with the surrounding vegetation. Measureable values will be set for each milestone and for final closure. These will link to agreed milestones for bond reductions. The current plan is suspended due to capital market conditions.

3.2 ENVIRONMENTAL NON-GOVERNMENT ORGANSIATIONS (DR MUDD)Dr Mudd provided a report on behalf of environmental NGOs. Dr Mudd advised he had attended a public forum held prior to ARRTC which had been organised by the Environment Centre NT. He noted a range of uranium related issues were discussed at the forum including the Ranger 3 Deeps proposal and associated environmental approval process. Dr Mudd advised that the environment movement remains opposed to uranium mining and will continue to monitor the developments at Ranger.

3.3 NT DEPARTMENT OF MINES AND ENERGY (MS STROHMAYR)Ms Strohmayr provided an update on NTDME regulatory activities during the reporting period. Key points are summarised below. There are currently six uranium mining and exploration tenements authorised under the NT Mining Management Act in the Alligator Rivers Region and surrounding areas. Uranium Equities Limited has two projects: Nabarlek and West Arnhem JV (in process of being authorised). The Headwaters project was closed out in February 2013. Cameco Australia Pty Ltd only has the Arnhem project. UXA has two projects: Nabarlek North and Nabarlek West. Alligator Energy has one project at Tin Camp Creek.Ms Strohmayr advised there were no significant approvals during the reporting period. Three applications were received from ERA including for the extension of the Ranger 3 Deeps exploration decline, ventilation shaft and bulk sample (April 2013); the Pit#1 closure stage 2 preload placement (10 May 2013) and the Ranger 2013 surface exploration program (18 May 2013). All of these applications are currently under review by the MTC. Ms Strohmayr advised that the Ranger 3 Deeps proposal was deemed to be a controlled action under the EPBC Act on 13 March 2013 and will be subject to a full EIS. She noted that the proposal is unable to be assessed under the Commonwealth-NT bilateral agreement as components of the project are located on Commonwealth lands where the agreement does not apply. The project is therefore being assessed by the NT and Commonwealth Governments. NTDME has provided comments on the draft EIS guidelines and a workshop for stakeholders is scheduled for early June 2013.Ms Strohmayr advised that an inspection of the earthen levee constructed between Magela Creek and the mine access road at Ranger in April confirmed that there has been minimal erosion and native vegetation is establishing at the site. In addition, continuous water quality monitoring has not detected any significant increase in turbidity downstream of the levee (and was in fact higher upstream). Ms Strohmayr advised that, following MTC approval, water was siphoned from the interim water management pond at Jabiluka into Swift Creek, subject to minimum flow requirements. A total of 60ML (40ML remaining) was released with no detectable impact on Swift Creek. ARRTC noted the key research issues of interest to NTDME include an updated tailings consolidation model and solute transport model for Pit#1 to assist in determining a final permanent tailings level; finalisation of closure criteria for Pit#1 to remove it as a process water catchment; brine injection and disposal in Pit#3; and development of scientific and cultural rehabilitation criteria for Jabiluka and Djarr Djarr.Discussion - Dr Mudd asked how it was determined there was no impact on Swift Creek from the disposal of water from the pond. Ms Strohmayr advised that this was based on monitoring upstream and downstream of the release point. Dr van Dam


advised that EC, U, Mg and pH data were reported and pH was the key variable of concern. Mr McAllister advised that the water in the pond is essentially rainwater but there had been issues previously with algae in the water. Dr Sinclair advised that ERA had commenced flood irrigation of the remaining water (about 34ML remaining) and will keep stakeholders advised on progress. Dr Mudd asked if the final approved level of tailings in Pit#1 is still RL 0. Dr Sinclair advised this wasn’t the case and Mr McAllister noted it had always been stated that this would be an interim level. Dr Mudd advised that there was always an expectation that Pit#1 would return to RL 0. Dr Barry asked if the science is being applied to determine what he final RL will be. Dr Mudd advised that based on a previous meeting with GAC it had been agreed that the level may temporarily exceed RL 0 but would always come down to RL 0 so there is no tailings left in the weathered zone. Dr Sinclair advised that ERA will comply with the ERs. Dr Barry noted that ARRTC remains concerned to ensure that regulatory decision making continues to be based on the best available science.

3.4 NORTHERN LAND COUNCIL (MR THOMPSON)Mr Thompson advised NLC has nil to report apart from noting recent staffing changes in the NLC Mining Group following Dr Smith’s resignation.

3.5 SUPERVISING SCIENTIST DIVISION (INCLUDING MONITORING) (MR MCALLISTER)Mr McAllister provided the SSD operations update and noted that Dr van Dam would address monitoring issues later this meeting. He advised that SSD is continuing to operate in an increasingly resource constrained environment. The Department is currently undertaking a voluntary redundancy process which will see a permanent reduction of 116 positions, including 4 from SSD. It was noted this will mainly impact on the division’s business support area but there will be minor flow-on impacts on the eriss scientific research program which Dr van Dam would address later in the meeting. Mr McAllister noted that eriss would not be able to be protected from any further reductions in resources.Discussion - Dr Mudd noted there are real concerns that further reductions in resourcing could start to impact on SSD’s capacity to perform its statutory functions. Dr Barry noted it was within ARRTC’s role to raise concerns if there is evidence that such resource constraints are actually preventing work addressing the Key Knowledge Needs from continuing but it is equally important that SSD continue to effectively prioritise available resources. Mr McAllister noted that ARRTC obviously has no role in SSD operational decision making but he is always interested in getting ARRTC’s views on what are the highest research priorities going forward. Dr van Dam noted that his presentation later this meeting would highlight how the current resourcing is impacting on SSD scientific programs. Mr McAllister noted that forced redundancies were not currently being considered but could not be ruled out in the future. Dr Mudd asked if SSD is able to access grant and other external funding sources. Mr McAllister advised SSD may be able to look at further collaboration with universities. Dr Barry noted a key advantage of being core funded and not having to rely on external funding is that the focus remains on the science and not where the funding is coming from. ARRTC agreed to discuss this matter further later in the meeting.

3.3 PARKS AUSTRALIA (MR PAUL)Mr Paul provided an update report on the South Alligator Valley remediation project on behalf of Parks Australia. Key points are summarised below. It was noted that ARPANSA issued the DNP with a revised facility licence on 5 April 2013 which requires an annual report to be submitted to ARPANSA until the licence is cancelled or surrendered. As required under the licence, an environmental monitoring plan has been developing in partnership with SSD covering assessment of containment performance, surficial radioactivity, ground water quality and vegetation monitoring.Remediation works - Erosion gullies that formed in the south east corner of the containment facility during the 2011-12 wet season were filled in and stabilised in late December 2012. The 2012-13 wet season produced significantly lower than average rainfall, and minimal erosion has been detected at the site. Further erosion prevention work is scheduled for late May/early June 2013, including rock armouring the south east corner. Revegetation is progressing well across the facility area predominantly with Acacia species. O’Kanes visited the site in May 2013 to conduct erosion assessment, vegetation survey, cover permeability assessment and collect in situ data from data loggers. Parks is currently awaiting a report and data on the performance of the containment cover.Surface radioactivity - Parks engaged SSD to undertake an assessment of potential doses and make recommendations on dose constraints for workers and the public based on various exposure scenarios and exposure pathways. The report produced considers the radiological characteristics measured at the site between 2007 and 2012. Based on the current radiological characteristics of the containment, the results indicate that for the identified exposure scenarios, the expected maximum dose is less than 10 microsieverts (μSv) per year. Considering the containment poses a very low risk to both the public and workers, and that annual monitoring by SSD will continue for the foreseeable future, the DNP has proposed to ARPANSA a maximum dose constraint level of 30 μSv. It is anticipated that as more data becomes available, this figure will be refined and revised downwards.Groundwater monitoring - Trevlyn Radiation and Environment has been engaged to undertake groundwater monitoring at the site. Pre-wet season monitoring of bores was undertaken in November 2012. While most results fell within recommended guidelines, elevated Manganese (Mn) levels were detected at ESMB11. Further ground water sampling was conducted in May 2013 and if Mn levels remain high, further investigation into the cause will be undertaken.Inspections - SSD inspected the facility in January 2013 and recommended that a controlled burn be done to reduce potential for a high intensity fire leaving the containment cover prone to erosion. The fire break around the facility has also been mown and controlled burning carried out around the site. An unplanned burn outside the containment in April 2013 was contained by the


fire break. SSD also recommended a more permanent solution for the erosion gullies on the south east corner, which will be addressed when the containment slopes are rock armoured in June 2013.Discussion - Prof Woodroffe asked what type of erosion control will used on the site and Mr Paul advised that both jute netting and rock armouring were being considered. Mr McAllister noted that south-eastern section posed the greatest erosion risk due to the friable nature of the cover material. Prof Woodroffe suggested it was important that a record be kept of the rehabilitation of the site to provide a future reference source. Mr McAllister noted that ARPANSA will also be doing inspections of the site. Mr Paul noted that Parks will provide ARPANSA a report on the environmental monitoring plan for the site. Mr McAllister noted SSD has some concerns in relation to the dense stand of Acacias currently on the site. Professor Mulligan asked who is undertaking the vegetation monitoring on the site and Mr Paul advised this was being done by consultants. Dr Mudd commended Parks on the level of reporting that has provided to ARRTC on the El Sherana rehabilitation project and asked if there is a plan for monitoring the other rehabilitated mine sites in the South Alligator Valley. Mr McAllister noted a key issue for Parks is the requirement that rehabilitation works in the SAV be completed by 2015. Mr Waggitt noted there is no timeframe on associated monitoring activities. Mr McAllister advised that SSD has raised with Parks the need for further consultation with TOs with a view to obtaining sign off for the sites from a scientific perspective. Mr Waggitt advised he was not aware of the need for any further work and believed that both Phase A and B had been undertaken to satisfaction of TOs. Dr Mudd suggested there would be value in collating the monitoring data and associated documentation on the works undertaken, perhaps after the Gunlom Agreement. It was suggested this could be done prior to further consultation with TOs. Dr Mudd suggested this wouldn’t have to be a large detailed report but rather a collation of existing information. Mr Waggitt noted a document prepared by Mike Faucet in 2004-05 provides a comprehensive history of the sites in the SAV. Mr McAllister noted that this could be followed up in discussions with Parks. Dr Barry asked if there was any role for ARRTC in prioritising the science. Dr Mudd suggested the key science related to groundwater monitoring, erosion mitigation, revegetation and other rehabilitation issues that have had to be addressed would be relevant, especially in relation to measures that have been successful. Prof Woodroffe noted that the erosion issues at El Sherana could be of relevance to the rehabilitation planning and modelling for Ranger, in particular the fact that gullies have developed on the site in such a short time frame. Mr McAllister noted the issues at El Sherana are at a relatively small scale and would be of more interest to ARPANSA who monitor the site. Prof Mulligan also expressed concern in relation to the dominance of Acacias on the site and the risks this poses to rehabilitation success due to the increased fire risk. Mr Paul noted the Acacias are short lived species so it is likely other species will also establish over time. Prof Mulligan suggested it was important that the site continued to be monitored and subject to active fire management through controlled burns, noting that pre burn data are particularly important. Mr Johnston suggested the proposed dose constraint of 30 microsieverts seems very small. Dr Bollhoefer noted the dose constraint number had been proposed by Parks following receipt of the SSD report. He noted that SSD had determined the maximum dose that might be received based on how much time Park workers would spend on the site or the scenario of tourists inadvertently camping for 4 nights, and used radon emanation data gamma dose. He noted the rates were no different to the surrounding area. SSD modelled radon concentration in the air and determined the maximum dose anyone would receive was 10 microsieverts then Parks had agreed upon the more conservation figure of 30 microsieverts. ARRTC noted the dose is very conservative. He agreed the figure is very low but is set at realistic level as it is a very small site. Mr Johnston advised he understood the technical basis for the figure but remained surprised how low the dose is. Dr Mudd noted the figure was essentially a management limit and agreed with Dr Bollhoefer regarding the assumptions on which the dose was based. ARRTC noted that if people camped on the site long term, the exposure would be much higher.

ARRTC30-4: ARRTC agreed that all available, relevant, current and historical information related to the South Alligator Valley rehabilitation activities, including monitoring data and historical documentation, should be collated into a single reference document.

4 Research Reports4.1 SUPERVISING SCIENTIST DIVISION - PROPOSED 2013-14 RESEARCH PROGRAM (DR VAN DAM)Dr van Dam provided a presentation on the proposed eriss research program for 2013-14. Key points are summarised below.2012-13 wet season – the 2012-13 wet season was generally poor with below average rainfall – approximately 25% of the total rainfall occurred during a late season event in April. Due to the lower than average rainfall, discharges from the mine were minimal with little effect observable on the water quality in the creeks. Magela Creek - there was close tracking between the upstream and downstream sites with discharge and EC peaking during the rainfall event in April. ERA was discharging pond water from RP1 up until March. ERA was also releasing treated pond water permeate via Corridor Creek which was ceased following the detection of a small peak in EC in Magela Creek in May (as the permeate entering the upper catchment pushed water out through the lower catchment when the creek had very little flow). Turbidity at the upstream and downstream sites also tracked closely and peaked during the April event.Gulungul Creek - Compared to Magela Creek, the EC data for Gulungul Creek were much noisier. There was close tracking between the upstream and downstream sites up until the event in April where levels both upstream and downstream decreased due to dilution before recovering with the downstream site slightly higher due to mine site runoff. Turbidity at the upstream and downstream sites also tracked closely and peaked during the April event. Overall water quality was good. Discussion - Dr Mudd asked if Mg levels had tracked EC levels and Dr van Dam confirmed this. Prof Woodroffe asked why the upstream and downstream EC levels remained apart for so long and Dr Sinclair advised this was due to run off and drainage of solutes coming off weathering of the waste rock.


2013-14 Work planning context – key knowledge timelines

Dr van Dam advised that eriss planning this year was based around the following key knowledge timelines: Pit#1 backfill and initial cap - Billabong water quality (solutes) closure criteria by June 2013. Dr Humphrey’s group is looking

at developing water quality guidelines associated with Pit#1 closure but this could be pushed back to September. Rehabilitation/closure risk assessment - Conceptual models required by June 2013. Important that momentum continue in

collaboration with ERA. Water treatment - Brine concentrator distillate toxicity by August 2013 and water quality trigger values for Mn and NH 3 by

August 2013 Remediation of Land Application Areas - Radiation dose assessments for human and non-human biota by Q4 2013. There are

also some related radiological and vegetation issues. Pit#3 tailings deposition - Multiple deliverables for SSD by Q3 2014 including water quality issues.Eriss resource constraints

Dr van Dam noted the implications for the eriss research program from ongoing funding pressures have been mentioned at previous meetings. The key affected program areas of eriss impacted by the constrained funding environment are PCP (staff losses) and SSDI (program refocusing). As the consultancy budget is also reduced, there is less scope to contract external assistance. As part of the Departmental voluntary redundancy program, SSD will lose four positions including 1 from eriss. SSD management is aiming to minimise impacts on the eriss science program, however, there is likely to be some impact going forward. Work programs have been aligned with available resources but further fine tuning may be required. Dr van Dam noted that geomorphology continues to be a high priority area given the key risks associated with sediments coming off the mine site especially during the rehabilitation phase. Given this, staff and functions have been transferred from SSDI to PCP, including the landform evolution modelling work by John Lowry. To reflect these changes, PCP has also been renamed Hydrologic, Geomorphic and Chemical Processes (HGCP) and SSDI renamed Revegetation and Landscape Ecology (RLE). Dr van Dam noted the key expertise gaps for eriss continue to be environmental chemistry, surface water - groundwater interactions and quantitative risk modelling.Discussion - Dr Mudd asked what quantitative risk modelling means in this context. Dr van Dam noted this refers to parameterising the conceptual models to develop a better understanding of the level of inherent risk associated with the various pathways. Prof Woodroffe asked if the change in name for SSDI reflected a shift in focus away from using LiDAR and remote sensing. Dr van Dam advised that most of the remote sensing work is related to methods for monitoring rehabilitation but there will continue to be overlap with the work by HGCP given the multidisciplinary nature of projects.PROPOSED 2013-14 RESEARCH PROGRAM Dr van Dam noted that the total number of projects proposed for 2013-14 were down by about 10% compared to last year although HGPC has an increased number of projects reflecting the landform evolution work. It was also noted that the number of projects addressing closure and rehabilitation related knowledge needs have increased. Dr van Dam provided further details on a number of key proposed projects.KKN1.2.4 ECOTOXICOLOGYToxicity of uranium to sediment biota – Proposed activities under this continuing project include analysis and interpretation of the 2012-13 field experiment and derivation of a sediment quality trigger value. It was noted that, as this work is about 6 months behind the Pit#1 closure timeframe, an interim criterion may be required. It was also noted this work may be applicable to the operational phase.Toxicity of ammonia to freshwater species – This new project will look at the toxicity of the low level of residual ammonia in brine concentrator distillate (operational phase) and the much higher level of ammonia in tailings seepage (post mining phase). The importance of pH in this context was also noted. Given this work is about 12 months behind, an interim criterion may be required. It was noted an interim criterion could be developed using the ANZECC (2000) guidelines, tailored to the relevant pH and temperature.Discussion - Dr Sinclair asked if this work would be able to be finalised by the end of 2013-14. He noted ERA will need to release distillate before then so an interim criterion will be required. Mr McAllister noted that the ammonia specific toxicity work was separate to the distillate whole effluent toxicity work which should be completed by August 2013. Dr van Dam confirmed that the distillate whole effluent toxicity work would definitely be completed when required by ERA.KKN1.2.5 – MASS BALANCES AND ANNUAL LOAD LIMITSSolute budgets for Magela and Gulungul Creeks – This continuing work is focused on updating the solute budgets (including updating the EC v Mg relationships and temporal and spatial characteristics of major solute inputs) for Magela and Gulungul Creeks and quantifying errors associated with solute load estimates. It was noted that ARRTC has previously highlighted the importance of this work.KKN2.1.1 – DEFINING THE REFERENCE STATE AND BASELINE DATA Pre-mining landscape change analysis using historical aerial photography – This new project involves pre-mining landscape change analysis using aerial photos to look at vegetation changes over time and use this to inform landscape/vegetation closure criteria. It was noted that the potentially confounding effects of other non-mining disturbance factors (e.g. fire; buffalos) will also need to be considered. Discussion - Dr Mudd noted the eradication of buffalo occurred in the early 1980s. Dr van Dam noted the potential issues associated with developing closure criteria for the current landscape on a previous landscape impacted by buffalos. Dr Barry asked how useful the historical land use is in terms of developing a baseline. Dr van Dam advised this stems from the ERs that


mention comparison with surrounding values and there are issues associated with having a substrate on the final landform which is significantly different to the original pre-mining condition. Dr Sinclair noted ERA is concerned about the same issues. Prof Woodroffe noted that spatial sciences can be useful for monitoring creek bank erosion and deriving other geomorphic information. Dr van Dam noted that when the photos were selected, key features to be compared were identified. Prof Boon asked why the years 1978, 1979 and 1980 were selected and Dr Humphrey advised that image availability was a key determining factor. Dr Whiteside added that the availability of colour and infrared images from those years provides more useful information for vegetation change analysis and, importantly, the selected images are from the period immediately prior to commencement of mining. Dr van Dam noted the work will also look at inter and intra decadal variability.KKN2.2.1 – LANDFORM DESIGNErosion and chemistry studies on trial landform – It was noted that rainfall, height, discharge, turbidity, sediment, EC and selected chemistry data have been collected from the trial landform for the past four wet seasons (09-10 to 12-13) and data processing/analysis has been hampered by staff shortages. It is now proposed to cease data collection from plots 3 and 4 (waste rock/laterite mix) and increase staff resources to accelerate data processing during 2013-14.Discussion - Prof Mulligan asked when and how the issue with mica was resolved and Dr Erskine advised the relationship between turbidity and suspended sediment had been resolved using a 9 point moving average statistical relationship between turbidity and suspended sediment. Prof Mulligan asked what will happen to plots 3 and 4 and Dr Erskine advised he was unsure but there are proposals to try alternative work using flumes rather than plots on steeper slopes and using this extra data to calibrate the CAESAR model. He also advised that historical eriss data from work using different sized plots and rainfall simulation had recently been obtained from Steve Riley. Prof Mulligan asked if this was on waste rock and Dr Erskine advised the work had been done using waste rock from Pit#1 which has different geochemistry to Pit#3 (U more available). Dr Saynor advised that some data from historical work at Tin Camp Creek were also obtained. ARRTC agreed such historical data will be very valuable. Dr Barry queried if there isn’t sufficient laterite available to use a laterite/waste rock treatment for the final rehabilitated landform, can plots 3 and 4 be used for other studies. Dr van Dam noted ERA may have plans for the area. Dr Sinclair confirmed that laterite will not be used in the final landform surface but may be used to form the impermeable layer on Pit#3 to stop upward seepage should this be an issue. Dr Lu noted that ERA is dealing with a “novel ecosystem” (waste rock only substrates) that doesn’t currently exist in the natural environment so current work is focused on determining the types and environmental requirements of the vegetation for the final landform. He noted that the density of vegetation in this modified environment could be lower but this needs to be demonstrated. ERA is collaborating with CDU and CSIRO on this research and ERA expects to be able to provide a presentation on this work to ARRTC by the end of year. Existing physiological studies on plant water stress at the end of the dry season is continuing. Dr Lu agreed there is insufficient laterite for the final landform but he has seen plants growing better in the laterite mixed plots, although weeds remain a major issue. ERA is looking at compaction of a sub-surface layer to reduce hydraulic conductivity, which may improve soil water holding capacity and vegetation success on waste rock only substrates. Dr Sinclair noted ERA has also reduced workforce so there is a need to be more targeted in this area.2.2.5 RADIOLOGICAL CHARACTERISTICS OF THE FINAL LANDFORMRadon exhalation from the Ranger trial landform – This continuing work involves measuring radon exhalation, and its temporal variability, from the trial landform, to predict long-term radon exhalation flux for the rehabilitated landform and inform closure criteria. Inhalation of radon decay products is likely to be a significant contributor to dose on the rehabilitated landform. This work is related to the collaborative project with ERA using radon exhalation columns to determine the effect of capping depth on radon flux. Discussion - Dr Mudd asked about the linkages between this and work by Dr Lu looking at effects of soil moisture. Dr Bollhoefer noted that there is limited time available to look at the data but this is planned. Prof Boon noted that plants also act as conduits for many gases and asked if this is the case for radon. Dr Mudd noted that the radon gas emanates from the radium in the soil but, as it’s a non-reactive gas, it would probably go straight through the plant. Dr Bollhoefer noted there may be a small amount of transmission via plants but this wasn’t a major pathway. Dr Mudd noted plants can also affect radon through changes in partial pressures. Dr Lu noted that, in 20-30 years after some trees have died, the root systems can provide preferential pathways as can termites. Prof Boon noted up to 90% of methane transport is via plants.KKN 2.5.1 – CLOSURE CRITERIA FOR ECOSYSTEMSRefinement of billabong water quality closure criteria – It was noted this continuing project builds on the 2012 – 13 billabong water quality project to develop closure criteria. The project will further assess responses over a gradient of water quality, and continue to track effects in Georgetown Billabong where biological impacts were previously observed (or assess recovery if water quality improves) and then refine the closure criteria if required. KKN2.5.3 – ESTABLISHMENT AND SUSTAINABILITY OF ECOSYSTEMS ON MINE LANDFORMAquatic ecosystem establishment knowledge assessment – This continuing collaborative project with ERA on developing approaches for the restoration/remediation of near–site waterbodies was discussed at last ARRTC. The future direction of this work depends on decisions by ERA regarding the presence/type of waterbodies to be incorporated in the final landform design. Current work is focused on collating existing literature on aquatic ecosystems and identifying knowledge gaps to guide future research requirements. Also using risk assessment outputs.Discussion - Dr Humphrey asked if the current timeline was suitable and Dr Sinclair agreed. Ms Iles advised that ERA should be in position to make a decision on whether Djalkmarra Billabong will be restored or not. Dr Sinclair advised that ERA will need to go back to GAC on this but hopefully a decision should be possible by mid-year. He noted that it was likely that some form of sentinel wetland would be required around the final landform but these may not be permanent. Dr van Dam noted that such


wetlands could be used for passive treatment of surface runoff during the vegetation establishment phase. It was noted the wetlands would also capture sediment and low levels of metals. KKN2.5.4 – RADIATION EXPOSURE PATHWAYS ASSOCIATED WITH ECOSYSTEM RE-ESTABLISHMENT

Radionuclide uptake in traditional aboriginal foods – It was noted that eriss has collected many data on radionuclides and metals in biota and bushfoods typically to calculate uptake/concentration factors. The focus of data collation and analysis to date has been on radionuclides (including development of the BRUCE database) so now looking to analyse the metal data to better understand metal accumulation, enable human health assessments and address the ISWWG recommendation 6 regarding bushtucker monitoring. Work on mussels will continue.KKN2.6.1 – MONITORING OF THE REHABILITATED LANDFORM Demonstrating the utility of unmanned aerial vehicles for monitoring rehabilitation success of the Ranger mine site – It was noted that unmanned aerial vehicles provide flexible and cost effective means of monitoring the long term success of the rehabilitated landform using very high resolution imagery. It is proposed to undertake a number of UAV demonstration flights in June in collaboration with UQ CMLR to test the viability of this technology, followed by data analysis and interpretation. Discussion - Dr Barry noted the rationale for SSD investigating the applicability of UAVs for monitoring purposes. He advised that, based on previous experience, it is really important that SSD is fully cognisant of the state of the art in this field as the technology is evolving rapidly. Dr Whiteside agreed that technology in this field is developing rapidly and there are now prototype vehicles that can carry a payload of 4 band sensor and a $40,000 hyper spectral camera. Prof Woodroffe suggested that LiDAR should also be considered as well. Dr Erskine noted that if SSD does acquire the technology then HGCP would also look at suitable applications.KKN2.7.1 ECOLOGICAL RISK ASSESSMENTS OF THE REHABILITATION AND POST-REHABILITATION PHASESRanger rehabilitation/closure risk assessment: Phase 2 – Risk analysis – This new project will identify key knowledge gaps and inform the KKN revision process.DELAYED/SUSPENDED PROJECTS Dr van Dam listed the key projects that have been delayed or suspended due to budget and staffing constraints. He noted that a number of corporate projects have also been delayed.

ARRTC30-5: ARRTC commended SSD on the high quality of papers and presentations provided to this meeting and endorsed the proposed eriss 2013-14 research program.

4.2 ENERGY RESOURCES OF AUSTRALIA LTD - OPERATIONS AND INTEGRATED TAILINGS WATER AND CLOSURE REPORT (DR SINCLAIR)Dr Sinclair provided presentation covering ERA operations and closure/rehabilitation related activities. Key points raised are summarised below.Safety and People - ERA achieved a YTD All Injury Frequency Rate (AIFR) of 0.50. One recordable injury occurred in 2013 and the employee has made a full recovery and returned to full duties. ERA was awarded the Australian Road Safety Founder’s Award for Outstanding Achievement in late 2012 in relation to road safety initiatives at the Australian Road Safety Awards. ERA continues to be a major employer in the West Arnhem region. About 16% of the current workforce is indigenous and about 20% female. ERA is continuing its education partnership with the West Arnhem College. Financial – As of 31 December 2012, ERA had $465 million in cash, achieved a total of $75 million savings related to its 2011 Business Review programme and is on track to save $150 million by end of 2014. ERA has a continued focus on cost reductions going forward but all projects remain on schedule and budget.Reserves and Resources - Base case reserves and resources as at 31 December 2012 will take ERA through to 2016, augmented by approximately 70 M t of low grade material. ERA can reduce cut-off grade at the mill so is drawing some of this material forward to get to 2020. ERA is now at the point where the current resource base needs to be replenished and this was the reason for the Ranger 3 Deeps development. ERA’s intention is to replace low grade resources with high grade ore. Exploration – Exploration drilling has been underway at Ranger 18, Ranger 19 and Ranger 48 since July 2012. During 2013, ERA plans to target Ranger 19 and Ranger 48 focusing on deep targets. Other exploration activity will continue at Ranger 3 Deeps. Dr Mudd asked about the prospectively at Ranger 4 and Dr Sinclair noted there is some enrichment in the laterite at this site. Operations – The backfill of Pit#3 is progressing well and tailings/brine disposal is expected to commence in 2015. Stockpiles continue to be reduced resulting significant aesthetic changes at the Ranger site which should be important to TOs. It was noted that 10 M t (out of total 30 M t) of waste rock has been placed in Pit#3 with a higher rate of backfill than expected. The Ranger plant is running well and cost optimisation is continuing especially regarding acid usage. The plant will be fed with low grade material from the stockpile (similar to 2012 H1) during H2. It is forecasted that 2013 production will be between 2,700 to 3,300 tonnes U3O8.Water management – The 2012-13 wet season rainfall to date has been approximately 80 per cent of the long term average. Water management arrangements at site have been enhanced and ERA has capacity to manage extreme weather events. The Independent Surface Water Working Group review was completed in late 2012. Dr Sinclair noted the scientific input provided by eriss to the work of the Committee was very valuable. The review confirmed that water management at Ranger is of world class standard and there is no evidence of mining related impacts on the downstream environment. The Working Group’s 15 recommendations will be progressed through the MTC. Dr Sinclair noted the final report had been accepted and endorsed by GAC and ERA, and that report addresses all of the concerns initially raised by GAC. The brine concentrator project is on schedule


and work is currently focused on energising the power station and other components. It is expected the facility will be commissioned by Q3 2013; the commissioning phase will include acceptance testing and ecotoxicology analysis. Once operational, the facility will produce up to 1.83 billion litres of clean water per year.Progressive rehabilitation – The current Integrated Tailings Water and Closure Pre-feasibility study is looking at the best options for solving tailings and water disposal and mitigating associated impacts, and is expected to be completed by Q2 2013. Rehabilitation work over the period 2013-15 is approximately 25% of the total rehabilitation task for the site. Effective preparation of Pit#3 is critical for the successful rehabilitation of the TSF. Current rehabilitation provision (as at 31 December 2012) is $782 M (real/undiscounted) or about $640 M on a net present cost basis (excluding the 220 M for the brine concentrator).Mining agreement – A suite of agreements between ERA, TOs, NLC and the Commonwealth Government developed under the Aboriginal Land Rights (Northern Territory) Act 1976 (Cth) were executed on 24 January 2013. The new Mining Agreement provides a structured approach for ongoing collaboration between GAC and ERA. A Relationship Committee has been established to ensure effective information sharing and review processes with TOs. ERA will also assist GAC in implementing a Sustainability Trust which will deliver a range of social initiatives in the local region. Dr Sinclair noted the new agreement addresses 30 years of legacy stakeholder issues.Exploration decline and Ranger 3 Deeps (Phase 1) – The construction of the exploration decline is continuing. Backfill of the boxcut and local rehabilitation has been completed and involves a relatively small foot print. The target ore body is estimated at 34000 t resources and is a structurally complex deposit. The exploration decline will be about 2.4 km long and involve approximately 54000m of drilling over the next 18 months. As at 20 May 2013, the face position of the decline was 802 metres from the surface. Data from high resolution drilling will be used to design the cross cut and the decline is expected to be completed by March 2014.Ranger 3 Deeps exploration decline (Phase 2) – Phase 2 of the project would involve extending the decline to a maximum length of 3000m to enable a 155m cross cut to be made so that a 10000 t sample of representative mineralised ore can be taken and used to evaluate the radiological sorter pilot plant. A vent rise would also be constructed to provide the high level of ventilation required for radiation management purposes. The results of drilling are expected by the end of 2014. Radiometric ore sorter – The use of radiological sorting is ERA’s preferred option for beneficiating the higher carbonate ore. It is planned to recommission the existing radiological sorter which was constructed in 2007 for separating low grade ore from barren carbonate rock using scintillometers and air injection. The mineralogy of ore from Ranger 3 Deeps is similar to ore from Pit#3. Removal of carbonate rock from the milling process will result in lower acid requirements and other environmental benefits.Ranger 3 Deeps EPBC referral – The proposal was referred under Commonwealth and NT Government legislation. The proposal was deemed to be a controlled action under the EPBC Act and also determined to require an Environment Impact Statement level assessment by the NT. A meeting is proposed for June 2013 to discuss draft assessment guidelines. These will also be subject to public comment process. Dr Sinclair advised the key milestones anticipated for the Ranger 3 Deeps project include commencement of exploration drilling in June 2013, exploration and resources drilling completed by mid-2014, regulatory and ministerial approval by late 2014 and, subject to this, underground production commencing in late 2015.ITWC and Closure Estimate Overview - It was noted that the Ranger ERs are set out in the section 41 Authority. It is anticipated that tailings transfer from the mill and the TSF to Pit#3 will commence in 2015 and the Pit#1 rehabilitation process should be completed by this point. Further work is required to reduce the number/size of process water catchments onsite. It is also anticipated that by 2021, LAA rehabilitation will be underway, the mill area will be deconstructed, contaminated material from the TSF will be transferred to Pit#3 and wicks installed to begin drying period, and the brine concentrator and power station will still be operating. By 2024, work on rehabilitating RP1 and RP6 and the stockpiles will have commenced and the backfill of Pit#3 will be continuing. There may be a final landform retention pond to deal with runoff and MFRO units may be required depending on water quality. Final closure is anticipated in 2025-26, by which time the backfill of Pit#3 and rehabilitation of the brine concentrators will be complete and revegetation of various areas ongoing. It was noted the TSF will be decontaminated and the wall will be pushed in to form part of the final elevated landform.Discussion - Dr van Dam asked what period of monitoring may be required post-closure and Dr Sinclair noted ERA is planning on monitoring for 10 years. Mr Johnston noted a 10 year monitoring period highlights the need to ensure the science informing the process is right. Dr Mudd asked how the ERA annual rehabilitation plan and bond is configured. Dr Sinclair advised the bond comprises both cash and a bank guarantee. However, the life of mine closure cost is paid out of cash flow so it is critical that the mining process continue. Dr Humphrey asked if there is any advance in whole-of-site understanding regarding the solute transport modelling and Dr Sinclair advised that Intera is currently working on the whole of site model for solute release which should enable cumulative loads into Magela to be assessed. Solute models for Pits 1 and 3 will be delivered in Q4 2013 with the whole of site model in 2014. He added that meetings will be held to discuss the models with stakeholders. Dr Humphrey asked if ERA would use preferential milling if underground mining is approved. Dr Sinclair advised the ERA plans to blend high and lower grade ore so the Ranger 3 deeps mine wouldn’t impact on the current closure timeframe. Dr Humphrey asked if the quality of the waste rock used in rehabilitation will change and Dr Sinclair said the rehabilitated landform will still be covered by ones rock. Dr Mudd noted there appears to be an inconsistency with previous ERA statements regarding the amount of ore to be mined. Dr Humphrey asked how efficient the laterite interface will be in reducing any exchange. Dr Sinclair advised that the Interra modelling indicates that as the tailings are surcharged there will still be some process water signature - a low volume but with high concentration – in the seepage on recessional flow of Magela. Dr Sinclair advised that ERA is currently evaluating possible mitigation options which may include a cut off wall around Pit#3 or installing a liner or other barrier on top of the tailings to stop solutes coming over. Dr Sinclair noted that ERA was currently using an older consolidation model which assumes the tailings are


sitting higher than they will be. ARRTC noted the importance of the Pit#1 rehabilitation to the overall rehabilitation of the mine site. It was noted that there will be whole of site assessment completed, not just separate Pit solute models. Dr van Dam asked if the model will include the effects of mitigation options and Dr Sinclair confirmed this. Dr Sinclair also noted there is a confluence of a number of parallel research streams that will be collated later in 2013. It was noted that cultural inputs around closure criteria will also need to be considered in this process.

ARRTC30-6: ARRTC commended ERA staff on the high quality of their scientific work and presentations to this meeting.

5.0 Strategic Overview (ERA/eriss)Dr Barry noted this new agenda item was agreed at last meeting in response to concerns that ARRTC members also be allocated sufficient time at meetings to discuss the overall direction, focus and timing of research addressing the Key Knowledge Needs and other strategic matters. Mr Parker advised that, as the KKN revision process was yet to be finalised pending the outcomes from the closure/rehabilitation risk assessment, a number of presentations previously requested by ARRTC would be provided this meeting instead. He noted, however, members would still have the opportunity at the end of the meeting to have a summary discussion. He noted that for future meetings, this agenda item will address matters nominated by members prior to the meeting using the process agreed at ARRTC29.

5.1 STATUS OF RESEARCH INFORMING CLOSURE CRITERIAMs Paulka provided a presentation on the status of research informing the development of closure criteria for Ranger mine. Key points raised are summarised below. Ms Paulka advised that the Closure Criteria Working Group (CCWG) has formed a number Technical Working Groups (TWG) to progress research and develop closure criteria for the agreed themes of Landform, Radiation, Water and Sediment, Flora and Fauna and Soils. It was noted that these TWG may also establish sub groups to address specific issues. Dr Mudd asked how soil and sediment are being dealt with and Ms Paulka advised that the sediment theme related to aquatic environments and the soils theme relates to terrestrial environments. It was noted that sediment transported off-site as suspended sediment would be covered under the broad sediment theme. The CCWG is currently working on the proposed scope of work and associated deliverables. ARRTC noted that any delay in developing closure criteria may delay internal approvals and progress towards the closure deadline of 2026. Ms Paulka noted the key tasks included identifying and documenting baseline reference datasets, developing individual closure parameters under each theme and methods for setting associated parameter thresholds (taking account of temporal and spatial aspects), identifying associated research need and data gaps followed by derivation of parameter threshold values and predicted trajectories. It was noted that monitoring methods for measuring compliance will also need to be developed as well as contingencies to deal with deviations from predicted trajectories. Ms Paulka advised that the closure projects reported to ARRTC29 have been prioritised based on current closure approval milestones and mapped against the relevant closure criteria. This information will be provided to the TWGs for updating. Ms Paulka then outlined the key priority closure projects.Discussion - Prof Woodroffe noted the Pit#1 landform is referred to as being final and asked if the current landform will be recontoured as part of the final landform. Ms Paulka advised that there may be a need for recontouring to address erosion and noted the current Pit#1 consolidation model is significantly different to previous versions. Prof Woodroffe asked what scope is there to modify the Pit#1 landform if it is proposed to be designed and constructed by 2015. Dr Sinclair advised that monitoring will continue and ERA is currently not planning to do the bulk backfill until the end of 2014, so the consolidation modelling will continue to be refined. Prof Woodroffe asked if components (e.g. the geotextile) would be revisited if needed. Dr Sinclair advised the landform will follow the contour of the tailings so predicting where sediment will be will require the data from the preload to feed into backfill design. Ms Paulka noted there will be a delay before the final landform is done and handed over for revegetation. Dr Sinclair advised the timing currently looked workable. Prof Mulligan asked if the final Pit#1 landform would essentially be a shedding landform and Dr Sinclair noted the landform would be designed to enhance recharge but will need to also take account of erosion potential. It was noted the final Pit#1 will likely be convex in profile. Prof Woodroffe noted that the characteristics of the rock used will also feed into the surface topography. He noted the modelling was technically interesting but the key issue is ensuring the final landform design is right. Dr Sinclair noted the landform design is an iterative process requiring significant data and the key design aim is to ensure the final landform does not allow standing water. He acknowledged this is different to previous TO expectations. Dr Mudd noted that 20 years ago when the option of having a rehabilitated Djalkmarra Billabong was raised, it was always expected that there would be solutes coming from the landform. He acknowledged however that expectations need to be balanced with technical feasibility. Dr van Dam advised that modelling by Lowry et al on Pit#1 indicates that the Pit#1 final landform should not be considered in isolation from the surrounding landform. Dr Sinclair noted that Pit#1 is essentially being used as a rehabilitation pilot and agreed it should be considered holistically. Prof Woodroffe suggested that, notwithstanding the good work being done, the actual proposed final landform for Pit#1 is still not fully developed at this stage. Prof Boon asked if closure criteria will be developed for fauna and Ms Paulka advised that this was not proposed at this stage. Dr Humphrey noted closure criteria would be developed for terrestrial flora. Ms Paulka advised that the current thinking is that if the habitat is established on the final landform then the fauna will follow. Dr George asked if there is any scope to expand this approach beyond terrestrial into aquatic biota. Ms Paulka advised these issues would be considered by the relevant TWGs. Prof Boon noted that recent work from North America looking at time required for modified/impacted environments to recover indicates that wetlands may require from 20 to 50 years and that reestablishment of nutrient cycling can take up to 100s of years. He suggested there may therefore be issues with signing off on the basis of having a structural ecosystem in place which is actually dysfunctional. Ms Paulka noted this is why a trajectory approach supported by monitoring is proposed. Dr Sinclair noted


that Traditional Knowledge would also be an important input to the process. Dr Humphrey suggested that there may be other relevant learnings that could assist in accelerating the ecosystem establishment process. Dr Barry noted that the ecosystems on the final landform are always going to be highly modified so the trajectories will be, to some extent, towards agreed modified state endpoints. It was also agreed that the trajectories need to be based on a sound conceptual understanding of the ecological issues associated with restoring modified ecosystems. Ms Paulka agreed it is important that the agreed objectives are realistic and achievable. Dr Barry agreed and suggested the whole process needs to be science based. Prof Mulligan agreed it is important to set early realistic rather than aspirational endpoints that will never be reached. He noted that mining changes everything in the landscape so the post-mining environment will never be like it was pre-mining and expectations of relevant stakeholders should be based on this. Dr Sinclair agreed and suggested the issue of restoration of billabongs is an example of this. Dr Mudd noted, however, there is a legally enforceable requirement in relation to Ranger that the site be restored to a state such that it could be incorporated into Kakadu National Park. He noted that this is what the TOs are reasonably expecting. Dr Sinclair advised that the process of ecosystem establishment on the final landform post mining will take many years and this is why a trajectory approach is proposed. Dr Barry noted that regardless of the relevant legal obligations on parties and associated expectations, ARRTC’s focus is on ensuring the science informing decision making is the best available.Dr Humphrey asked about the possible implications of not having any surface expression of water from the final landform. Dr Sinclair advised the key requirement is that the tailings source term and potential solute pathways are contained. Prof Boon noted there is a difference between “restoration” and “rehabilitation” and the latter should be used in this case. Dr Sinclair advised that key task is to rehabilitate the site to the standard set out in ERs. Dr George asked how TO cultural values will be addressed through the process and Ms Paulka advised this will be addressed by the cultural TWG that has already been formed and currently working on progressive rehabilitation projects. She advised that ERA is working through a single point of contact with TOs. Dr van Dam noted the increasing convergence between the closure criteria working group process and the current risk assessment process. Prof Mulligan noted that compromise may be required if the relevant members of the CCWG are not able to agree. Ms Paulka noted the current definition of “detrimental impact” needs to be resolved between the various stakeholders. Prof Woodroffe noted the whole process appears to be very focused on the mine site and asked to what extent the broader landscape, including the Magela Floodplain downstream, is being considered and if this is also being modelled. Ms Paulka noted that this spatial scale is being considered as part of closure rehabilitation risk assessment process. Prof Boon asked why a trajectory approach is proposed given this is very deterministic. Dr van Dam suggested perhaps a set of preferred trajectories should be identified. Ms Paulka noted that there are obviously various different pathways to each of the end points. Prof Mulligan asked how trajectories would deal with possible disturbances along the way (e.g. fire). Prof Boon noted there is evidence in the literature that even changes to a single species can have ecosystem wide implications.

5.2 INITIAL ASSESSMENT OF THE GEOMORPHIC STABILITY OF THE CONCEPTUAL REHABILITATED RANGER LANDFORMMr Lowry provided a presentation on the status of landform evolution modelling for Ranger. Key points raised are summarised below. Mr Lowry noted that rehabilitation/closure is a key focus of the SSD 2013-14 research program. He noted a priority requirement is the assessment of the geomorphic stability of the proposed rehabilitated landform to address Key Knowledge Needs 2.2.1 (Landform design) and 2.2.4 (Geomorphic behaviour and evolution of the final landform), and inform landform design and development of closure criteria. Mr Lowry advised that the CAESAR landscape evolution model has been combined with the Lisflood hydrodynamic flow model and is being used to simulate runoff, erosion and deposition for different scenarios. For this work, differential consolidation rates are also being modelled. The model uses discrete rainfall and run-off data and can also model the impact of extreme rainfall events (e.g. Cyclone Monica rainfall data). The model is able to provide graphical outputs. The current work uses a catchment-based approach in two phases: (1) application of the model to Pit#1 (including Corridor Creek) and (2) assessment of remaining areas of landform. Primary inputs for the model include a Digital Elevation Model, LiDAR and conceptualised landform from ERA, rainfall data from Jabiru Airport and particle size data from the TLF (waste rock only). Other parameters used include differential consolidation and vegetation (grass cover). Multiple scenarios are applied to catchments on the landform including with/without vegetation (all catchments); with/without surcharge (Corridor Creek and Djalkmarra) - with/without consolidation. The model assumes that the entire landform is composed of waste rock, including areas that are currently, and will remain as, woodlands and riparian zones. The rainfall data for the 45 year simulation included a greater than 1 in 100 event, but the 1000 year dataset did not include this event, due to the time required for processing if looped multiple times. All scenarios have been modelled for 45 years and 1000 years. Dr Mudd asked if the particle size of waste rock can be altered to simulate effects of weathering and Mr Lowry advised the model can be stopped to change particle size and restarted. Mr Lowry noted the landform design requires further work and outlined the key conclusions based on the results for the draft landform assessed. For Corridor Creek, none of the scenarios predicted gullies with a depth of greater than 5 metres over a time period of 1000 years however a 4-metre deep gully is predicted to form on the side of the landform over a period of 1000 years under vegetated consolidated conditions. Djalkmarra Creek will re-establish itself in Djalkmarra catchment, within a period of 45 years. Gullies up to 12 metres deep are predicted under vegetated conditions over a period of 1000 years. A 7-metre deep by 300-metre wide channel belt/incised floodplain is predicted to form in the area currently occupied by Pit#3 in the catchment over a period of 1000 years under unvegetated conditions. Coonjimba Creek will re-establish itself in Coonjimba catchment and gullies up to 12 metres deep are predicted to form in both the upper and lower reaches of the catchment under vegetated conditions. A channel belt 300 metres wide by 11 metres deep is predicted to form in the lower reaches of the catchment under unvegetated conditions over 1000 years. Gulungul Creek is likely to experience net infilling of existing drainage lines under both vegetated and unvegetated scenarios within 45 years.


Mr Lowry advised the future work on the project will include using a high resolution DEM, further modelling looking at effects of reducing the size and slopes of the catchments and redirecting runoff into adjacent catchments, increasing elevations of key features to prevent formation of sinks and applying a staged surcharge approach. Other changes will include identifying and incorporating different surface treatments appropriate for specific functional elements (e.g. rock-armoured drainage collection channels, erosion control structures, sediment traps) of the final landform. Mr Lowry noted the longer term viability (decadal time scale) of such structures is questionable as they are likely to need maintenance and the focus should be on hill slope and catchment geomorphology rather than hard engineering. More work is also required on modelling the impact of development of vegetation communities (and impact of fire on those communities), improving the rainfall data used in modelling (e.g. using weather generator and analysis of paleoflood records to develop model scenarios), developing ability to predict suspended sediment concentrations and extending simulations out to period of 10,000 years and integration of model outputs with the SIBERIA packageDiscussion - Prof Mulligan asked what type of vegetation cover is being used in the model. Mr Lowry advised that 100 percent mature grass community is currently being used but there is a need to look at the effects of mature more complex ecosystems and also fire. Mr Johnston asked what triggers the gullying process and is this just a function of the model or based on geology at site. Mr Lowry advised the establishment of gullies is a function of particle size of the initial surface and rainfall intensity and that gullying usually starts after 3 and 4 years of heavy rainfall. Mr Johnston asked why gullies form in particular locations and Mr Lowry advised the model takes account of slope. Prof Boon asked if the changes in creek morphology predicted by the model would be expected to occur in these systems over 1000 years naturally. Dr Erskine suggested this is probably the case and noted that previous work by Prof Woodroffe at Kalpalga and work by Nacy shows there is a Holocene cap on most of the creeks in the region. Prof Woodroffe indicated he is surprised that the model is predicting that level of change over 1000 years given there has been very little change in the surrounding landscape over millions of years. Prof Boon noted the model is highlighting changes in micro scale heterogeneity. Dr Erskine suggested it is not an issue of the effect of vegetation on the landform but rather the effects of riparian vegetation which will change the way the creeks are modelled. Dr Mudd asked how different transpiration rates and the water budget is dealt with in model (e.g. fraction between runoff, recharge etc). Mr Lowry advised this was still being looked at. Dr Erskine advised that for some outputs the water balance has been modified. Prof Woodroffe noted the vegetation in the model is still a relatively gross cell parameter. Mr Lowry advised that each cell has two parameters for vegetation (maturity and erosive stress). Dr van Dam asked if it would be useful to have a baseline model so the outputs of modelled scenarios could be compared back to a baseline. Prof Woodroffe noted it was unclear where Pit#1 is in the catchment and asked what cell size is being used. Mr Lowry advised a 10m by 10m cell size (based on a resampled 1m DEM) was being used due to the computation intensity involved. Prof Woodroffe queried the presence of parallel drainage lines in the model where these are usually expected to be dendritic. Mr Thompson asked if, in addition to the looped Jabiru rainfall data, extreme rainfall events would be included in the model. Mr Lowry noted it was planned to include such events (e.g. cyclones) in the model in the future. Dr Mudd suggested that some trend in frequency of extreme events would also be useful. Mr Lowry advised that an artificial rainfall data generator could be used. Ms Iles noted that this issue had been raised in the FEPS workshop and that Interra is also addressing the frequency of extreme events in their models Dr Barry suggested there should be some alignment of this parameter between models as well. Mr Lowry advised that after 45 years an extreme event still has impact on sediment loads so it would be reasonable to expect that a number of major extreme events in quick succession could lead to massive amount of material being exported out. Professor Mulligan noted that effects of extreme events on vegetation could also be simulated as timing of rainfall is important, given a saturated landform will perform differently to a dry landform. He suggested also that the effects of vegetation on the water balance should be looked at. It was suggested that the proportion of rainfall loss due to evaporation prior to reaching the ground is also important and should be deleted from rainfall data in model. Dr Erskine noted there is a paper in Nature which indicates that soil production per unit rainfall energy decreases during the wet season due to grass growth so sediment production in December can be orders of magnitude higher than in March.Prof Woodroffe commended Mr Lowry for his high quality presentation. He noted that the detailed creek network in the model is totally a function of the DEM being used. As flow direction modelling shows where channels will develop based on different DEMs, there is an opportunity to use a series of DEMs to look at different scenarios. Mr Lowry advised this was being considered. Dr Humphrey queried why the Djalkmarra Billabong would not be reformed given every significant creek line on the western side of Magela Creek has a billabong. Dr Sinclair advised that this is not going to happen and further alignment between the modelling and landform design process is required. Dr van Dam noted the conceptual landform used in the model is based on the conceptual landform provided by ERA. Dr Mudd asked about the boundary conditions used in the model and whether it assumes that water doesn’t travel past this point into Magela Creek. Prof Boon cited the axiom that all models are wrong but some are useful and asked how wrong the current model could be. Mr Lowry advised the model outputs align well with the results of field studies on the trial landform so at present there is a high level of confidence in the model outputs. It was noted the cell size used in studies on the trial landform was 30 square metres versus the 10m cell size used for the landform evolution model. Dr Erskine noted that CASEAR is very time intensive so there are issues with using it to develop various scenarios. It was suggested that current computer processing power should be increased to address this.

ARRTC30-7: ARRTC thanked Mr Lowry and Ms Paulka for their high quality presentations.

5.3 STATUS OF PIT#1 REHABILITATION AND FINAL LANDFORMDr Sinclair provided a presentation on the status of Pit#1 rehabilitation and the final landform. Key points raised are summarised below. Dr Sinclair noted that Pit#1 rehabilitation process provides a good learning opportunity for Pit#3 rehabilitation and will provide invaluable data to confirm consolidation models which feed into future assessments of seepage impacts. The activities of the closure WG have been aligned with this timing. Closure of Pit#1 will be undertaken using a phased approach comprising wick


installation (7500 wicks; completed 2012), preload placement and monitoring (Q3/Q4 2013), Pit#1 backfill (Q4 2014 – Q2 2016) and rehabilitation and revegetation (2016-17). An MTC technical workshop on Pit#1 closure was held in early May 2013 and ERA submitted a notification on 17 May for the Pit#1 preload phase and is currently awaiting MTC comments. The Pit#1 preload placement will involve installation of a woven geotextile fabric covered by 1 m of Run of Mine (ROM) rock fill and a 1.5m layer of select ROM rock. Dr Sinclair noted the aim is to convert Pit#1 into a pond water catchment before starting the transfer of tailings and process water to Pit#3. Currently the mine fleet is fully occupied backfilling Pit#3 but will then be assigned to Pit#1. Vertical concrete dewatering sumps will be installed along with a range of instrumentation including settlement plates, piezometers and standpipes. It was noted that existing wicks have activated due to weight consolidation and tailings strength has increased to support placement of preload materials. CSIRO seepage modelling is being updated based on 2012 monitoring results and the revised tailings consolidation model. The CSIRO solute transport model also considers kinetics and digenesis. Current modelling indicates a bi-modal pathway of solute transport with sulfate being transported by slow moving groundwater and reaching the discharge boundary beyond 100 years. It was noted that predicted solute concentrations are being updated in line with the consolidation model. Dr Sinclair stressed the key issue is controlling the upwards solute flux. The t imeframe for the backfill of Pit#1 is considered achievable from a science and technical perspective and indigenous staff members are being trained in revegetation techniques and a seed contract being negotiated.Discussion - Dr George asked what contributed to the rate of consolidation being underestimated. Dr Sinclair advised contributing factors included the initial assumed volumes used were incorrect, some early surveys didn’t take account of the effect of small under bed drains and some of the prisms used for previous surveys had moved, affecting volumetric calculations. He noted that once the wicks were installed it became evident that the actual level of consolidation was significantly higher than originally assumed. Prof Woodroffe asked if the topography of the geotextile fabric will change due to compaction. Dr Sinclair confirmed this and noted that the shape and contour of the surface will be modified as required. He noted the model now shows a much faster rate of consolidation and that the tail drops off quickly so the expressed process water can be treated through the brine concentrator. Dr Mudd noted that the model assumes that Magela Creek is the boundary and asked how it is known this is a no-flow boundary. Dr Sinclair advised the Interra model has the full boundary conditions and these models will need to be integrated with the Interra work. Dr Sinclair advised the seepage barrier is up to RL 15 and any cover will be designed to maximise recharge. Prof Mulligan noted the critical issue is how much rainfall will be required to maintain this recharge. It was noted that a recharge rate of 5% of rainfall was the target, based on the current modelling results. Prof Woodroffe noted that this approach is different to other cases where the design aim has been to maximise surface water runoff and avoid standing water. He asked whether the infiltration rate or volume of infiltration were most important. Prof Mulligan noted that previous experience in designing covers to exclude water infiltration has met with limited success. He also noted it is unclear how 5% rainfall infiltration rate could be designed for. Dr Sinclair noted that infiltration was desirable in this case as it results in a less dense fresher water lens in the transport zone. ARRTC noted the key driver of solute discharge from Pit#1 is the tailings consolidation.

5.4 REHABILITATION-CLOSURE RISK ASSESSMENT OUTCOMESMs Iles provided a presentation on the outcomes from the Ranger closure ecological risk assessment workshop. Key points raised are summarised below. Ms Iles noted this work is addressing KKN 2.7.1 Ecological risk assessments of the rehabilitation and post rehabilitation phases and is also linked to the closure criteria working group process. She also noted the workshop was the first (problem formulation) phase of a multi-phase risk assessment approach. It was noted that the results of the workshop and associated follow up work are being published by CSIRO. Extreme events and climate change were considered and addressed as stressors. The project is a collaborative effort between SSD, CSIRO and ERA and had input from all key stakeholders. Ms Iles noted a number of different approaches were considered including USEPA and ISO31000:2009. It was decided to go with the ISO: 31000 approach as it lends itself much better to working with stakeholders and working with qualitative data. As part of the stakeholder engagement process, meetings were held with TOs on country and a one day workshop was held with NLC and GAC. This included consideration of work by Dr Howard Smith on integration of cultural knowledge into closure planning. Dr Smith was also part of the project planning team. A 2 day workshop was held at SSD and was attended by representatives from ERA, SSD, NTDME, GAC, NLC and Parks. Prof Mulligan also attended as an ARRTC representative. Ms Iles advised the aims of the workshop were to identify endpoints, sources, stressors and values for each temporal phase and develop associated conceptual/causal models. Three spatial scales (mine site, Ranger Project Area and Magela Creek catchment, KNP and ARR) and three temporal scales (decommissioning, stabilisation and monitoring, and long term post –closure monitoring) were used. The identified values, end points, stressor, sources pathways were then put into Netica. Following the workshop further work was undertaken to revise, standardise and refine the workshop outputs and conceptual models and these were to be provided to the relevant workshop theme groups for review. A draft risk matrix was developed based on the values and assessment endpoints with each cell representing a conceptual risk model. Ms Iles advised future work on the project included finalisation of the problem formulation phase by Q3 2013 followed by the risk analysis phase. This phase will involve working with CSIRO to develop a formal plan for the risk analysis (including screening for priority), formalising the Bayesian network structure for each of the models (or alternative tool), populating the models with information (e.g. data, expert judgement, literature information) and commencing prioritised analyses and sensitivity assessments. It was noted that CSIRO may be engaged to assist with some or all of these tasks. Ms Iles advised the Bayesian network approach was preferred as it allows for non-quantitative aspects to be included along with personal views/expert opinion. Data, where available, will be used to replace expert opinion where possible. The outputs of this work will continue to inform the current KKN revision process. Discussion - Dr Mudd asked if extreme dry events and dry spells are being included in the process and Dr Bartolo advised probably not as dryness only affects vegetation. Dr Mudd challenged this assumption and noted dryness can also affect erosion and a range of other factors. Prof Woodroffe recommended that climate variability and climate change should also be in the


same scenario. It was noted that the process is an ecological assessment so water, soils and sediments are included under terrestrial values. Dr Mudd noted the cultural sub model includes risks to access and traversability of final landform which is a significant TO concern. Prof Mulligan stated he had attended the workshop representing ARRTC and was interested to note the significant work being done by the closure working group. He advised he had found the exercise worthwhile and thought the involvement of the NLC/GAC was critical. Prof Mulligan asked if the values within the surrounding KNP are being considered in terms of end points. He noted that based on his experience, access to expert judgement is critical if using Netica and Bayesian network approaches. Dr van Dam noted that the process has been delayed due to existing workload of staff involved but there is now a clear path forward. Ms Iles noted that KNP is considered for endpoints though there is an issue with identifying values as these are not always clear from the ERs and are open to interpretation. Prof Boon noted that, based on his previous experience with Bayesian networks, they were useful but problems always arise when it comes to ascribing probabilities. Dr Barry indicated he thought the work to date was a good start and asked if all of the conceptual models have been completed. He expressed some concern about trying to take everything to the Bayesian framework and agreed with Prof Boon that there can be problems with assigning probabilities across the networks and this can be very complicated to do well. Dr Barry asked if there are any pathways at this stage that all stakeholders agree are very low risk and can be removed from the framework up front. Ms Iles noted this will be derived from the screening process along with what resolution is required. Dr Barry noted that some issues will be obvious knowledge gaps so there is a need to decide what level of resources should be applied, and to what level risks have to be assessed.

ARRTC30-8: ARRTC noted the proposed approach and timeframe for the Ranger closure risk assessment project and requested that a status report (including the results from the screening phase) be provided to next meeting.

5.5 KKN REVISION STATUS Dr van Dam provided a presentation on the status of the KKN revision process. Key points raised are summarised below. Dr van Dam noted that ARRTC has previously agreed that the revision of the KKNs should be informed by the outputs of the rehabilitation/closure risk assessment process. He noted an example table matrix had been presented to ARRTC29 which proposed an approach for structuring the revised KKNs based on the agreed spatial and temporal scales. Dr van Dam noted the conceptual modelling/problem formulation phase of the risk assessment workshop (as outlined in the draft risk assessment matrix presented this meeting) would appear to support this proposed approach, although clearly this will need to be further refined as part of the process. For example, the relationship between the relevant conceptual risk models and identified knowledge gaps and the actual structure and content of the KKNs requires further consideration. The proposed risk analyses will inform the revision of the KKNs, as key risks and uncertainties are identified, quantified and prioritised. Dr van Dam suggested that the assessment endpoints are the key elements and provide a logical set of primary headings for structuring the KKNs and the temporal phase could be used as the secondary headings. A number of example KKN structures were presented and discussed. It was agreed it may be useful to map the existing KKNs to the proposed framework once this has been developed. ARRTC noted that SSD and ERA staff will continue to work on the KKN revision and will report progress to ARRTC at the next meeting later this year.Discussion - Dr Barry asked how the risk models in the cells relate to the risk assessment workshop outputs. Dr van Dam advised that the risk models will be based on pathways identified in the workshop and that some cells may be the same as other cells. Dr Sinclair asked if the assessment endpoints are weighted at this stage, noting that some may be more important than others. Dr van Dam advised this would be addressed as part of the planned screening process. Dr Barry asked what each model would produce and Dr van Dam advised each model would represent the risks and uncertainties associated with the relevant stressors and pathways for that spatial and temporal combination. Mr Johnston asked if the models will change depending on the temporal phase involved. Dr van Dam noted it is intended that there will be separate models for the different temporal phases and these will be linked to the knowledge gaps that will need to be addressed to reduce the uncertainties. Dr Sinclair asked if the process would include high impact/low probability events as well. Ms Iles noted that one of the screening tools will be the FEPS outputs which already address these types of events. Dr Barry noted it will also depend on the weightings applied to the various elements in the risk models. Dr Sinclair noted it is important that the risk assessment not be too complicated or have too much emphasis on the lower impact events that pose no risk to the environment. Dr Mudd noted that different stakeholders will likely have differing views on what is an acceptable or low impact. Dr Humphrey noted it is important that the KKN revision process not pre-empt the outcomes from the closure risk assessment outcomes. Dr Mudd asked if there is a deadline by when the KKN revision needs to be finalised. Dr Barry noted there is no deadline but it would be good to have the work finalised as soon as possible. Dr Humphrey suggested the work could be done in stages starting with a mapping of the old KKNs. Dr van Dam noted a key concern with the current KKNs is that many are not worded as research questions. Prof Mulligan suggested that SSD and ERA should be able to identify what the key risks are, and then scope the KKNs and associated research questions accordingly. Dr van Dam noted the process is a formalisation of current understandings so there is a need to be confident that the models cover everything. Prof Mulligan asked if ARRTC members would have the opportunity to assess the models and Dr van Dam noted there may be elements where specific advice from ARRTC members is required. Prof Mulligan asked which external technical experts will be involved in the Bayesian assessment. Dr Barry noted the clear linkages between the risk assessment and the KKN revision process and that this is what ARRTC requested. Prof Boon noted that expert input should be sought where knowledge gaps become clear in relation to ascribing probabilities. Dr van Dam noted that in many cases SSD and ERA have the knowledge to ascribe the numbers but it will come down to the screening process which will identify key areas of risk.

ARRTC30-9: ARRTC noted the current risk based approach proposed for the revision of the Key Knowledge Needs and


requested that a status report be provided to next meeting.

5.6 ARRTC SUMMARY DISCUSSIONDr Barry noted the purpose of this agenda item is to provide ARRTC members with the opportunity to discuss strategic science issues and raise any issues not already covered or on which they would like further information. Dr Sinclair advised that ERA highly values the benefit it derives from ARRTC members’ expertise and advice. He asked if ARRTC believes the current level of information provided by ERA and SSD is sufficient. Prof Woodroffe advised that he found the erosion presentations very interesting but doesn’t believe he has the necessary level of scientific expertise to be an independent advisor on erosion issues. He indicated he would be more confident if there was an independent evaluation of the work to date on the progression of Pit#1 into Pit#3 and the final landform modelling. He noted this presents a significant research opportunity as not many other people would be looking at these issues, especially the requirement for isolating tailings for 10000 years. He suggested the whole process would be significantly strengthened if there were independent suitably qualified consultants who could advise. He noted that the people who have developed the models are probably not the most appropriate people to get as independent reviewers. Prof Woodroffe suggested that CSIRO or GA may have someone suitable but given the timeframes this would need to be done fairly quickly. He noted that sending out manuscripts is one way of getting independent review but, in his view, a more direct process is required. Dr van Dam sought clarification on whether Prof Woodroffe was suggesting the need for independent expert assessment of the validity of the models and the work to date or just the work plan. He noted the work is at a key stage and obviously time critical. Dr van Dam advised that SSD would need to initiate this internally. Dr Mudd suggested also looking at other areas where similar issues have been faced (e.g. Appalachian mountains). Professor Mulligan agreed the questions about the landform erosion work are valid and noted the current model is built on a geomorphic model not an erosion model. He suggested there are number of erosion models that could be looked at as well including those developed by the Australian Coal Association in the early Bowen Basin days. Dr van Dam noted that it was always assumed that CAESAR and SIBERIA would be run side by side. He also noted that current issues may in part be due to the lack of available computer processing capacity on the current system. Professor Mulligan noted the other impediment appears to be the communications issues experienced between ERA and SSD. Dr Sinclair noted that, from a design view, the problem is ERA needs to run hundreds of iterations of models but CAESAR can only be run a few times over the same time period. This poses issues in terms of the landform design process and this is why the decoupling occurred. He noted a simplified SIBERIA model might also be useful for eriss. Prof Woodroffe noted that ArcHydro may also be of use. Prof Mulligan noted this needs to be addressed given the modelling results currently indicating a 10m deep gully on top of Pit#3. Dr Sinclair noted that ERA will base its design on whatever is required to avoid this. Ms Iles suggested the communications will also be enhanced by having the relevant people also involved in the closure working groups.

ARRTC30-10: ARRTC agreed that Prof Mulligan would provide suggestions on various suitable modelling packages that could be used by ERA to undertake high run landform evolution modelling for Ranger.ARRTC30-11: ARRTC agreed that the current Landform Evolution Modelling approaches should be independently reviewed.

Dr Mudd noted that most groundwater models being developed by ERA are centred on the mine site and are confined by close boundary conditions. He asked why ERA isn’t looking further away from the mine site at a regional scale, especially the deeper groundwater which is the longer term pathway. Dr Mudd agreed that modelling fractured rock at depth is complex but suggested that this issue should also be addressed. Dr Sinclair advised that ERA could provide an update on its groundwater modelling activities and associated boundary conditions at next meeting.

ARRTC30-12: ARRTC requested Dr Sinclair to provide an update on ERA groundwater modelling activities (including associated boundary conditions) to next meeting.

Dr van Dam noted that Interra looked at brine seepage in deep aquifers as part of its modelling and Dr Sinclair advised this has predicted negligible additional solute transport down Magela Creek. Dr Mudd suggested a better understanding of groundwater at a regional scale is required and that having boundary conditions so close to the mine doesn’t mean seepage will actually stop at the boundary condition, especially in deeper groundwater systems. Dr Sinclair noted the solute plume is at maximum depth of 50m whereas the total depth of Pit#3 is 230m. He noted that the dolomite goes below the contact zone. Dr Mudd noted that dolomites do have some solution pathways. Dr Sinclair advised that ERA is mainly interested in fault zones. Prof Boon asked what has been the consequence of the ISWWG report in terms of ERA practices. Dr Sinclair noted this work was initiated by GAC based on their specific concerns. The scope of the study was quite wide so GAC had arranged for the process to be subject to independent expert review. Dr Sinclair advised the report has been well received by stakeholders. He noted that Prof Taylor hadn’t been to Ranger previously so it really was an independent process. Dr Sinclair noted the report has had a similar effect to that of the previous Weaver report on groundwater at Ranger. Both processes identified issues and knowledge gaps, provided recommendations for addressing these and were well received by stakeholders. Dr Sinclair noted that such independent review processes are very beneficial. He noted the main difference between the two processes is that the ISWWG process arose out of deep seated concerns and mistrust. Mr Thompson indicated he supports the need for an independent review of the landform erosion modelling work. Prof Boon agreed noting that so much hinges on getting this right. Dr Mudd noted that lessons were also learnt from modelling at Nabarlek and asked if the results of this work have been compared to the current model outputs. Dr Erskine noted the original model used at Nabarlek was RUSL which was relatively crude; SIBERIA was used later. Dr Barry asked, in terms of the trajectories proposed for vegetation on the final landform, what information is required to understand what the final vegetation structure will look like, given it is clearly not going to be the same as pre-mining. Dr Humphrey noted there is a need to look at differences between structure and function in ecosystems on final landform trajectories. Dr Barry noted it is important that the science underpinning the closure criteria and trajectories be clearly communicated and agreed by


stakeholders. Dr Sinclair agreed it is important that the science is clear and agreed prior to communicating this to TOs, however he stressed it is equally important to be clear about what is achievable in engineering terms.

ARRTC30-13: ARRTC requested that ERA provide a presentation on the status (and scientific basis for) the proposed vegetation related closure trajectories for Ranger to next meeting.

It was noted that the final landform will be an engineered structure which places conditions on the types of vegetation that can be supported. Prof Mulligan noted that, as part of rehabilitation works at Weipa, an engineered solution had been implemented which involved replacing the mined bauxite layer with additional top soil in order to lower the water table so that a preferred tree species could be sustained to meet TO stakeholder requirements. Dr Humphrey noted that previous work on analogue landforms at Ranger didn’t identify any major impediments for vegetation re-establishment. Dr Lu noted the substrates on the final landform will be different to that existing in nature. He noted the longest trial was for 17 years and species composition was very restricted and certainly not the full spectrum of species observed in non-mined areas. Dr Lu noted that vegetation can generally exist in locations outside of their niche but they will eventually die out. It was noted that the final landform will be significantly different to the trial landform with a range of substrates, slopes, drainage, moisture levels, aspects etc. Dr Lu stated that he was confident that ERA will be able to establish a functional ecosystem on the final landform using a mosaic of different species and densities of local native plant species. Prof Mulligan asked if there will be some areas on the final landform which won’t be covered with hard waste rock. Dr Sinclair confirmed that some areas will be ripped only. Prof Boon noted there is a 2 dimensional tension between deterministic and stochastic outcomes in terms of the final landform. While there is also some apparent tension with differences between realised niche and fundamental niche of the vegetation, this probably isn’t as deterministic as modelling water flows. Dr Humphrey noted there are weak relationships between vegetation and environmental parameters. Dr Sinclair noted that, in terms of trajectories for closure, the stochastic forces will win at the end of the day. Prof Mulligan noted that using a substrate that’s highly weathered will mean that fines are going to move. This is fine for established vegetation as it is building pore space but this can also affect seed viability. He noted the other issue over time is organic matter build up and the fire risk associated with this. Dr Lu advised that ERA has done some experimental work looking the effects of fire and the proposed revegetation strategy involves introducing fire after about 5 years, or when trees trunk diameters are above 5 cm. He noted that ERA was considering the possibility of conducting an early wet season burn on the laterite side of the trial landform and he offered to present these results to the next meeting if the burn does go ahead. Dr Humphrey also noted that he would trust in the initial approach developed by Dr Paul Reddell (which has been further developed by ERA based on results from studies on the Trial Landform) and the expert views of others who have experience in revegetation in the tropics.

ARRTC30-14: ARRTC requested that ERA provide a presentation on the status (and scientific basis for) the current revegetation strategy for Ranger to next meeting.

ARRTC30-15: ARRTC requested that a presentation on the status of knowledge and planning for the development of all closure trajectories be provided to next meeting.

Dr Sinclair noted that he is still concerned about comparing erosion rates on the final landform to undisturbed areas in Kakadu National Park. Dr van Dam agreed there has to be some reconciliation between what is stated in the ERs and what is technically achievable for the site. Dr Mudd noted the ERs actually refer to “similar” not “comparable”. Dr Sinclair noted the term “comparable” has been used in a number of previous presentations to ARRTC. Dr Humphrey asked if the ERs can be changed. ARRTC was informed that they have been changed in the past. Dr Sinclair noted that further work needs to be done on the implications of erosion on the environmental values that need to be protected.

ARRTC30-16: ARRTC requested that ERA and SSD provide a presentation on the status of erosion modelling for Ranger to next meeting.

ARRTC30-17: ARRTC requested that Dr Lu provide a presentation on the results from his eco-hydrology research at Ranger to next meeting.

It was noted that the relationship between the revegetation strategy and the proposed vegetation closure trajectory requires further work and the current data are only 3-4 years old (although there are some historical data available on tree size and composition). Dr Barry suggested there is still scope to access a wider set of knowledge held by others who have undertaken similar revegetation activities in northern Australia. It was noted these issues will be considered by the vegetation closure sub-group. Prof Woodroffe highlighted the importance of ARRTC being updated each meeting on progress towards closure.

6 Other BusinessDr Sinclair advised that the immediate priorities for ERA include the ecotoxicology work on the brine concentrator permeate and the finalisation of the Pit#1 closure criteria (scientific criteria). He advised that the current Ranger 3 Deeps proposal is for a 5 M t mine but ERA will continue exploration drilling until 2014 and any additional ore discovered would be subject to a separate referral. Dr Barry noted issues for report to the Minister include the status of the closure/rehabilitation risk assessment and KKN revision processes, Mr Hughes’ retirement, the status of major mine site developments at Ranger (including Pit#1 closure and the brine concentrator) and the timetable for closure criteria development. It was agreed that the letter should also include the potential implications of further resource constraints on SSD’s capacity to undertake high priority scientific research activities.


7 Next MeetingARRTC30-18: ARRTC agreed the next meeting (ARRTC31) would be held on a date to be agreed in the second half of November 2013, and may be preceded by a tour of Ranger mine (subject to confirmation by ERA).

The meeting closed at 4.00 pm. Scott Parker ARRTC Secretary22 May 2013


Action/Outcome ResponsibilityCarried over ARRTC27-4 ARRTC requested Ms Paulka to seek agreement from UEL to provide closure criteria and Hydrogeological review reports to Prof Mulligan, Dr Mudd and Mr

Johnston.ARRTC Secretariat to follow up with UEL. Noted that UEL report to meeting addresses some of this.

ARRTC27-5 ARRTC agreed that UEL be invited to submit a proposal to amend the (Nabarlek) KKN and that ARRTC then consider based on the evidence that has been provided to support this.

ARRTC Secretariat to follow up with UEL.

ARRTC30ARRTC30-1 ARRTC acknowledged Mr Hughes’ significant contribution to the protection of the Alligator Rivers Region through his work as Supervising Scientist and in

previous roles within the NT Government.ARRTC

ARRTC30-2 ARRTC agreed that the draft ARRTC Terms of Engagement should be finalised out-of-session as soon as possible. SecretariatARRTC30-3 ARRTC agreed the Secretariat will follow up actions ARRTC27-4 and ARRTC27-5 (as amended) with Ms Taylor out-of-session. SecretariatARRTC30-4 ARRTC agreed that all available, relevant, current and historical information related to the South Alligator Valley rehabilitation activities, including monitoring

data and historical documentation, should be collated into a single reference document.Parks Australia; SSD

ARRTC30-5 ARRTC commended SSD on the high quality of papers and presentations provided to this meeting and endorsed the proposed eriss 2013-14 research program.

ARRTC - complete

ARRTC30-6 ARRTC commended ERA staff on the high quality of their scientific work and presentations to this meeting. ARRTC - completeARRTC30-7 ARRTC thanked Mr Lowry and Ms Paulka for their high quality presentations. ARRTC - completeARRTC30-8 ARRTC noted the proposed approach and timeframe for the Ranger closure risk assessment project and requested that a status report (including the results

from the screening phase) be provided to next meeting.ERA; SSD

ARRTC30-9 ARRTC noted the current risk based approach proposed for the revision of the Key Knowledge Needs and requested that a status report be provided to next meeting

ERA; SSD

ARRTC30-10 ARRTC agreed that Prof Mulligan would provide suggestions on various suitable modelling packages that could be used by ERA to undertake high run landform evolution modelling for Ranger.

Prof Mulligan

ARRTC30-11 ARRTC requested Dr Sinclair to provide an update on ERA groundwater modelling activities (including associated boundary conditions) to next meeting Dr SinclairARRTC30-12 ARRTC requested that ERA provide a presentation on the status (and scientific basis for) the proposed vegetation related closure trajectories for Ranger to

next meeting.ERA

ARRTC30-13 ARRTC requested that ERA provide a presentation on the status (and scientific basis for) the current revegetation strategy for Ranger to next meeting ERAARRTC30-14 ARRTC requested that a presentation on the status of knowledge and planning for the development of closure trajectories be provided to next meeting. This can be combined with ARRTC30-12.ARRTC30-15 ARRTC requested that ERA and SSD provide a presentation on the status of erosion modelling for the Ranger to next meeting. ERA; SSDARRTC30-16 ARRTC requested that Dr Lu provide a presentation on the results from his eco-hydrology research at Ranger to next meeting. Dr LuARRTC30-17 ARRTC agreed the next meeting (ARRTC31) would be held on a date to be agreed in the second half of November 2013, and may be preceded by a tour of

Ranger mine (subject to confirmation by ERA).Secretariat (advice from ERA)


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