Alligator Rivers Region Technical Committee Meeting 29 5 ...environment.gov.au/.../files/summary-29th-meeting.docx · Web viewThe Chair (Dr Barry) welcomed members to the 29th meeting

Alligator Rivers Region Technical Committee Meeting 29 5 – 6 December 2012 Meeting Summary

Alligator Rivers Region Technical Committee

Meeting 29

5 – 6 December 2012

Meeting Summary

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ARRTC29 Meeting SummaryPage 3 of 21

Agenda

WEDNESDAY 5 DECEMBER 2012 (0900 -1700)

1 Preliminary Session (Chair)

1.1 Welcome and Introductions

1.2 Apologies and Observers

1.3 Correspondence

1.4 Conflict of Interest Declarations

1.5 Governance

1.5.1 Draft ARRTC Terms of Engagement

2 ARRTC28 Outcomes (Chair)

2.1 ARRTC28 – Meeting Summary

2.2 ARRTC28 - Actions

3 Stakeholder Reports

3.1 Uranium Equities Ltd - Nabarlek (Ms Taylor)

3.2 Environment NGOs (Dr Mudd)

3.3 Department of Mines and Energy (Mr Ball)

3.4 Northern Land Council (Dr Smith)

3.5 Parks Operations and Tourism Branch (South Alligator Valley) (Mr Issaverdis)

3.6 Supervising Scientist (including Monitoring) (Mr Hughes)

4 Science underpinning regulatory decisions (Mr Ball)

4.1 Regulatory applications/approvals

4.2 MTC Minutes

5 Research Reports

5.1 Supervising Scientist Division

5.1.1 eriss 2011-12 research outcomes (Dr van Dam)

5.2 Energy Resources of Australia Ltd

5.2.1 ERA operations and ITWC update (Dr Sinclair)

6. KKN research and revisions – joint status report (eriss)

6.1 Joint KKN status summary

6.2 KKN Technical Presentations

Independent Surface Water Review Working Group Update (Prof Barry Hart by phone - 1500-1530)

THURSDAY 6 DECEMBER 2012 (0900 - 1700)

6. KKN research and revisions - joint status report (cont.)

7 Other Business

7.1 SSD publications since ARRTC28

7.2 ERA publications since ARRTC28

7.3 ARRAC37 Meeting Summary

7.4 Chair meeting report

8 Next Meeting Attendance

Members

Dr Simon Barry

Independent Scientific Member and Chairperson

Dr Jenny Stauber

Independent Scientific Member

Prof Paul Boon


Ms Jane Coram


Prof David Mulligan


Prof Colin Woodroffe


Mr Andrew Johnston


Dr Gavin Mudd

Environment NGO stakeholder member

Dr Greg Sinclair

Energy Resources of Australia Ltd

Dr Howard Smith

Northern Land Council

Mr Russell Ball

NT Department of Mines and Energy

Mr Alan Hughes

Supervising Scientist

Apologies

Ms Melissa Taylor

Uranium Equities Limited

Ms Anna Morgan

Parks Australia Division

Mr Justin O’Brien

Permanent Observer - Gundjeihmi Aboriginal Corporation

Presenters/Observers

Mr Peter Waggitt


Ms Sally Strohmayr


Ms Lauren Cooper


Ms Shelly Iles


Dr Ping Lu


Dr Matt Kozak

Intera Pty Ltd

Dr. John Sigda

Intera Pty Ltd

Ms Sharon Paulka


Mr Nathaniel Toll


Ms Nicole Jacobsen


Mr Reid Miller


Ms Kyla Clark


Ms Linda Pugh


Professor Barry Hart

Chair, Independent Surface Water Working Group

Mr Adam Thompson

Northern Land Council

Jean-Pierre Issaverdis

Parks Australia Division

Dr Rick van Dam

Environmental Research Institute of the Supervising Scientist

Dr Che Doering


Dr Andreas Bollhöfer


Dr Chris Humphrey


Dr Amy George


Dr Renée Bartolo


Dr Mike Saynor


Dr Wayne Erskine


Dr Andrew Harford


Other SSD staff

Secretariat

Mr Scott Parker

Office of the Supervising Scientist

Ms Shannon Traut

Office of the Supervising Scientist

1 Preliminary Session1.1 Welcome and Introductions

The Chair (Dr Barry) welcomed members to the 29th meeting of the Alligator Rivers Region Technical Committee. Members were provided a facilities and safety briefing. Dr Barry thanked ERA for arranging the tour of Ranger mine prior to the meeting. He noted that all members had found the tour interesting and appreciated the opportunity to see first-hand the status of the various minesite developments. ARRTC noted the recent retirement of Dr David Jones as Director of eriss. Members commended Dr Jones for his outstanding contribution to the ongoing protection of the Alligator Rivers Region environment through his leadership of eriss’s world class scientific research program. It was agreed that the Chair would also note Dr Jones’ contribution in his report to the Minister following the meeting. Members also agreed to send a card to Dr Jones.

ARRTC29-1: 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.

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.

1.2 Apologies

Apologies from the following members were noted:

Ms Melissa Taylor

UEL

Ms Anna Morgan

Parks Australia

Mr Justin O’Brien

GAC (permanent observer)

1.3 Correspondence

The following correspondence was noted.

Outgoing - Letter to Minister Burke – ARRTC28 outcomes (17 February 2012)

Incoming - Letter from Minister Burke – ARRTC28 outcomes (15 March 2012)

1.4 Conflict of Interest Declarations

No 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. Ms Coram advised that as an employee of Geoscience Australia she is periodically requested to provide technical advice on groundwater issues at Ranger to a number of Australian Government departments. Dr Stauber advised 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.

1.5 Governance

Mr Parker advised that the draft Terms of Engagement document had not been tabled at this meeting as there are a number of remaining issues with the proposed structure and wording that need to be resolved. He noted further out-of-session consultation with members may be required in relation the clauses dealing with Intellectual Property and Non-disclosure. It was noted that not all current ARRTC members have signed non-disclosure agreements although ARRTC members are generally bound by decisions from previous meetings preventing the disclosure and/or unauthorised use of commercially sensitive information. Dr Sinclair requested that the Terms of Engagement be finalised and signed by members as soon as possible so that ERA can continue to provide ARRTC with the same level of technical and scientific information. It was asked if shares held by members’ partners, or in family trusts, could be considered a conflict of interest. Mr Parker advised he would seek further advice on this. Dr Barry advised he is generally comfortable with the approach being proposed with the Terms of Engagement but suggested that members raise any specific concerns with the Secretariat. ARRTC noted the Secretariat will circulate the draft Terms of Engagement out-of-session in early 2013.

ARRTC29-3: 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.

ARRTC29-4: Secretariat to circulate the final draft Terms of Engagement out-of-session in early 2013.

2 ARRTC28 Outcomes2.1 ARRTC28 - Summary Record

The ARRTC28 draft Meeting Summary was approved without amendment.

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2.2 ARRTC28 - actions Arising

Action/Outcome

Status

Previous

ARRTC27-4

ARRTC requested Ms Paulka to seek agreement from UEL to provide closure criteria and Hydrogeological review reports to Prof Mulligan and Gavin Mudd.

UEL to address

Carried over

ARRTC27-5

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

UEL to address

Carried over

ARRTC28

ARRTC28-1

ARRTC approved the ARRTC27 meeting summary as tabled with one minor amendment (p.20).

Complete

ARRTC28-2

ARRTC agreed that the meeting summary for this and future meetings should be more concise and should aim to capture the key discussion points and outcomes of the meeting without attributing individual members.

Complete

ARRTC28-3

ARRTC agreed the draft actions should be circulated to members within 4 weeks of each meeting, and the draft minutes circulated within 8 weeks.

Complete

ARRTC28-4

ARRTC requested that DoR provide the outcomes of ongoing work on the new Maximum Operating Level to members out-of-session.

Overtaken by current work on application for new MOL. ARRTC agreed to leave as action.

ARRTC28-5

ARRTC requested that DoR and ERA circulate their respective reports from the Bureau of Meteorology on Probable Maximum Precipitation.

Papers tabled. Completed.

ARRTC28-6

ARRTC requested that Parks Australia provide a copy of the O’Kanes Pty Ltd proposal (if possible) and further details on the groundwater monitoring program being put in place for the SAV rehabilitation project.

Addressed under Agenda Item 3.5

ARRTC28- 7

ARRTC requested that the Secretariat circulate the SSD report to ARRAC37 to members, and that SSD ARRAC reports be circulated with the draft ARRTC minutes for future meetings


ARRTC28-8

ARRTC noted the implications of current budget constraints in terms of the prioritisation and possible deferral of some SSD research activities for 2012-13.

Complete

ARRTC28-9

ARRTC commended SSD staff on the quality of their 2012-13 Research Report and technical presentations to this meeting.

Complete

ARRTC28-10

ARRTC commended ERA on the quality and depth of work being done on closure activities at Ranger and the high quality of information presented this meeting.

Complete

ARRTC28-11

ARRTC requested that SSD provide a presentation on ERICA and the ARPANSA approach on non-human biota to next meeting.

Addressed under Agenda Item 6

ARRTC28-12

ARRTC agreed there should be a new separate KKN addressing radiation impacts on non-human biota.

Complete

ARRTC28-13

ARRTC requested a presentation be provided to next meeting outlining the conceptual framework for closure at Ranger (covering the decommissioning, post-rehabilitation, and long-term post rehabilitation phases).

Addressed under Agenda Item 5.2.1

ARRTC28-14

Prof Boon to circulate to members an overview of the use of conceptual models in ecological rehabilitation.

Complete

ARRTC28-15

ARRTC agreed that the ERA proposed approach of using existing data is sound, but that further data should be collected so that the derived trigger values can be reviewed and refined in the future.

Complete

ARRTC28-16

ARRTC commended ERA on the quality of current groundwater modelling work and the good progress to date in implementing the Weaver report recommendations.

Complete

ARRTC28-17

ARRTC requested that Dr Smith provide a presentation to next meeting on the integration of Aboriginal Traditional Knowledge (and expectations) into the closure planning process.


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/teleconf.

Action delayed to Q1 2013. Addressed under Agenda Item 6

ARRTC28-19

ARRTC agreed to look at the feasibility of holding a one day workshop in Canberra in September 2012 to enable members to review and comment on the draft risk framework and revised KKNs.

Workshop not held – see ARRTC28-18 above

ARRTC28-20

ARRTC agreed that, consistent with the approach agreed last meeting, the draft revised KKNs would be reviewed at the November 2012 meeting on a by exception basis.

Addressed under Agenda Item 6

ARRTC28-21

ARRTC noted the Secretariat will finalise the draft ARRTC Terms of Appointment form and circulate out-of-session.

Complete

ARRTC28-22

ARRTC agreed that members would advise the Secretariat of their availability for the last two weeks of September and November 2012.

Complete

3 Stakeholder Reports3.1 NT Department of MINES and ENERGY (ms strohmayr)

Ms Strohmayr provided an update on DME regulatory activities during the reporting period. Key points are summarised below. There are currently six authorised exploration operations on a number of tenements in the Alligator Rivers Region, including: Uranium Equities Limited (Nabarlek, Headwaters), Cameco (Arnhem), UXA (Nabarlek North and Nabarlek W) and Alligator Energy (Tin Camp Creek). The following regulatory proposals and approvals for Ranger during the reporting period were noted.

Application to raise the Maximum Operating Level (MOL) on the Ranger Tailings Dam Stage VII – The TSF crest raise to RL 58m was completed in early November 2011. An application to increase the MOL to RL 57m (dry season) and RL 56.5m (wet season) was submitted. The Ranger Authorisation was varied on 24 September 2012 to incorporate the MOL of the TSF taking into account the Bureau of Meteorology’s estimates of Probable Maximum Precipitation (PMP). An independent expert review of the TSF design commissioned by SSD recommended that triaxial testing be conducted to confirm the assumed cohesion values in the design stability are representative of the materials used in construction.

Application to raise the MOL on the Ranger Tailings Dam Stage VIII RL60.5m (under review) – The lift of clay core of the TSF to RL60.5m was completed in November 2012. An application was submitted to raise the MOL to RL 59.25m (dry season) and RL 57.91m (wet season). When contingency pumping of 200ML/day from TSF to Pit 3 has been demonstrated by ERA, the wet season MOL will increase up to 58.71m RL. A TSF inspection was conducted by stakeholders on 14 November 2012 and the annual TSF inspection report was submitted on 27 November 2012. Triaxial test results were updated and submitted to MTC. The application is still under review and is subject to conditions being met by ERA (including status of GA 2011 report on TSF seepage model recommendations).

2012 Ranger exploration program – A proposal was submitted on 1 June 2012. ERA responded to MTC stakeholder comments and Exploration Management Plan was updated accordingly. Drill sites were inspected during Routine Periodic Inspections. The R3 Deeps exploration decline boxcut has been completed and infilling commenced in November 2012.

Application for construction of an earthen levee to the north of Pit#3 – An application was submitted in October 2012 to construct levee to mitigate the movement of surface water into pit#3 via cracks in the pit wall and the adjacent access road. The location of the levee borrow pit was changed to avoid an archaeological site prior to approval by MTC. Matting is being installed to minimise erosion and turbidity monitoring will be carried out up and downstream of the site. ARRTC noted there is expected to be some disturbance sediment generated by the construction of the proposed levee and also from the ongoing weathering of the rock used in its construction. ERA will monitor turbidity and pH downstream of the site (using grab sampling). SSD also operates continuous monitoring of turbidity upstream and downstream of the site. ERA advised that, consistent with the Independent Surface Water Working Group recommendations, it is currently upgrading its continuous monitoring network and this may include installation of continuous turbidity recording.

Key areas of interest to DME – It was noted the key research areas of interest to DME include the outcomes of the ISWWG review, the development of site-specific groundwater trigger values and closure criteria, and brine injection/disposal in Pit#3. ERA also advised weekly water quality reports are provided to stakeholders. ARRTC agreed it would be useful to see these reports and to have some level of feedback on the effectiveness of the levee and associated mitigation works going forward. ERA agreed to provide this information in its operational reports to future ARRTC meetings.

ARRTC29-5: ERA to include details on the effectiveness and associated water quality impacts associated with the levee in its operational reports to future ARRTC meetings.

Discussion - ARRTC noted ERA has provided information to the regulator and relevant stakeholders on the cause of the cracks in the pit wall and the proposed mitigation measures. ERA advised the significance of the cracks had been assessed using an internal formal risk assessment register. ERA also advised that ensuring the geotechnical stability of the pit wall is critical given the pit is now being backfilled. ARRTC noted that ERA will continue to provide stakeholders with periodic updates as required through the MTC and directly if necessary. Dr Mudd advised he thought the construction of a levee is an appropriate mitigation measure and that he had advised GAC that something of this nature would probably be required. He also acknowledged that such cracking is a common issue with open cut mining. ARRTC noted the key issues are (1) whether the identified risks are being appropriately and effectively mitigated and (2) whether there are any associated knowledge gaps requiring further investigation. ERA will continue to monitor the effectiveness of the levee during the forthcoming wet season. It was noted that if the deep sands underlying the levee prove to be an issue, ERA will likely install a cut-off trench. The cracks at the bottom of the pit wall are now less of an issue as the wall has unloaded and the key focus now is on surface inflow mechanisms. ERA was asked if any pore moisture measurements of the pit wall have been taken and agreed to provide further details on this at the next meeting.

ARRTC29-6: ERA to provide details on any measurements of pore moisture in the wall of Pit#3 to next meeting.

3.2 Northern Land Council (Dr Smith)

Dr Smith provided a presentation on how NLC is working with ERA, DME and other stakeholders to define appropriate closure criteria as part of a rehabilitation and post-closure plan. He noted it is important that Traditional Owners and their knowledge are effectively integrated into this process to assist with establishing stewardship arrangements for managing the land post mining. The Environment Requirements require (1) that mining operations at Ranger do not impact on the World Heritage values and attributes of Kakadu National Park (KNP) and (2) that the Ranger Project Area environment be rehabilitated to a level such that it can be incorporated into KNP post mining. He noted the Mirrar determine this to mean that any rehabilitation must consider cultural as well as environmental attributes. The process developed by NLC and ERA for integrating Traditional Ecological Knowledge with Western science to determine mutually acceptable closure criteria involves testing whether the proposed criterion is technically, culturally and economically viable. ARRTC noted that balancing belief structures and scientific data is always difficult, but a table of agreed closure criteria has been developed. Dr Smith advised that cultural landscaping was also undertaken using archival information, living memory and archaeological/anthropological reports to determine how the area was used by Mirrar prior to mining. This information was then used to inform a cultural risk assessment which identified five main categories (and more sub-categories) of risks to cultural activities. Seven pilot projects have been agreed as first steps towards re-establishing relationships (i.e. restoration of Magela Creek riparian zones, progressive rehabilitation of Land Application Areas; closure of Pit#1 and rehabilitation of Ranger access tracks; removal of the interim water management pond at Jabiluka; removal of bores in Mine Valley and rehabilitation of Djarr Djarr mining camp).

Discussion - It was asked if ARRTC has a role to play in assisting with building TO trust in relation to the formal science. Dr Smith noted ARRTC has a legitimate interest but not a direct role. The current focus is on establishing and strengthening the relationship between ERA and GAC, with NLC providing a supportive role. Dr Smith suggested Mirrar would not want to engage directly with ARRTC as NLC and GAC represent their interests. ARRTC agreed that cultural and scientific knowledge needs are equally important and that better integration of these needs to be based on trust and mutual understanding. There was some discussion regarding whether cultural knowledge should be included as part of ARRTC’s Key Knowledge Needs process. ARRTC agreed that cultural aspects should be addressed as part of the proposed KKN risk assessment methodology. Dr Smith noted that there are a number issues already addressed under the KKNs which have cultural implications (e.g. contaminants in bushfoods). It was noted that ARRAC plays an important role in providing a forum for stakeholders to share information and this should include cultural aspects. ERA noted that the ERs require the rehabilitation process to be undertaken in accordance with best practice which includes consideration of environmental, social and cultural values. It was noted that in practice this is can be extremely difficult and that is why it is important to focus on getting the relationships right and building trust to facilitate this. ARRTC noted that ERA has included cultural criteria in its Best Practicable Technology assessment criteria and is working to build relationships with TOs through the successful implementation of the pilot projects. It was agreed that the rehabilitation of Pit#1 provides a good opportunity to test how the process works. ARRTC agreed to track progress of the pilot projects and associated processes to see if the scientific outcomes are robust and workable. Dr Smith advised that, due to the culturally sensitive issues involved, the process is currently being managed via a small working group outside of the Closure Criteria Working Group. Once a document has been finalised, this will go to MTC and then presumably to ARRTC. Dr Mudd agreed that GAC engaging directly with ERA to ensure cultural issues are appropriately addressed as part of the rehabilitation process is a welcome and positive step forward. He also noted that the David Lawrence book “Kakadu – making of a national park” on the history of Kakadu provides a good historical insight into the issue.

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.

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.

3.3 Parks australia (Mr Issaverdis)

Mr Issaverdis provided an update on the status of rehabilitation works in the South Alligator Valley. Operational responsibility for the site has been transferred to Kakadu National Park. Contractors will be onsite in early December 2012 to remediate and mitigate the erosion gullies that formed in the south east corner of the containment facility during the next wet season. Revegetation (predominately with Acacia species) is progressing well across the whole facility and will aid in stabilising the site over future wet seasons. Mr Greg Balding has been engaged on a short term contract to supervise rehabilitation works and to prepare an ‘Acceptable Limits’ report for ARPANSA. ARPANSA issued a new Facility Licence to the Director of National Parks (DNP) in February 2012. An annual report was submitted to, and accepted by, ARPANSA in September 2012. As required under the new licence, a monitoring program has been developed in conjunction with SSD which covers containment performance, surficial radioactivity, groundwater and vegetation. SSD undertook gamma dose rate and radon flux density surveys at the site in September 2012 which showed that radioactivity is low and similar to typical background values elsewhere in the Alligator Rivers Region. SSD undertook an inspection of the site in June 2012 and made a number of recommendations including clearing around monitoring stations and remediating erosion gullies. All of these recommendations have, or are currently being addressed. It is expected that ongoing investment will be required over the next 4-5 years to conduct the required monitoring and cover the licence fees. Parks will continue to work with SSD to ensure the site is appropriately maintained.

Discussion - ARRTC noted that while the erosion gullies on the site are relatively large, they are not impacting the actual containment which is located below grade. It was asked if the site is subject to the requirement that tailings be isolated from the environment for 10,000 years as is the case at Ranger. Questions were also raised about the vegetation composition on the site and the possible effects of fire. Mr Issaverdis noted the vegetation on the site is Acacia dominated and while it is hoped that the site can be protected from fire for at least 5 years, it is expected a fire will go through the site at some stage. ARRTC noted this and other vegetation management issues are being addressed in the report being prepared by Mr Balding.

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.

3.4 Supervising Scientist Division (including monitoring) (MR HUGHES)

Mr Hughes provided a status report on SSD operations during the reporting period. He advised that Dr van Dam would provide information on SSD monitoring activities under the eriss research report later in the meeting. Mr Hughes noted that SSD had participated in the Independent Surface Water Working Group and that the review’s recommendations may have significant implications for the current regulatory framework and associated monitoring activities. ARRTC noted that resource constraints and staffing continue to be key challenges for SSD and that ultimately this may mean fewer staff undertaking more targeted activities. Mr Hughes noted the recent retirement of Dr Jones and advised that he was also planning to retire in 2013. ARRTC noted that SSD is having ongoing discussions with the Department on how to deal with staff departures and succession planning going forward.

3.5 Environmental Non-Government organsiations (Dr Mudd)

Dr Mudd provided a report on behalf of environmental NGOs. He acknowledged the significant work being undertaken by ERA at Ranger is addressing a range of complex and challenging issues. He noted that, while he doesn’t necessarily agree with further mining development at Ranger, ERA should be commended for its efforts to date in implementing the brine concentrator and other rehabilitation/closure related work. Dr Mudd advised that he had recently attended a community forum at Rum Jungle discussing uranium mining development and rehabilitation. The forum was hosted by NTDME and included representatives from a range of indigenous and environmental stakeholder groups. He stressed the importance of maintaining the current good relationships between government and stakeholders and noted the environment movement is very keen to see the Australian Government make the necessary investments to properly remediate legacy mine sites. Dr Mudd advised that the environment movement remains opposed to the proposed development of underground mining at Ranger 3 Deeps, and he will continue to provide feedback and technical advice to his stakeholders as required.

3.6 Uranium Equities Ltd (Nabarlek) (Ms TaylOr)

Apology - No report provided.

4 Science underpinning regulatory decisions (Mr Ball)

Mr Ball suggested there is significant overlap between this agenda item and agenda item 3.1. He noted that, as part of the regulatory process, the MTC rarely commissions independent scientific advice and relies mainly on the science provided in the various reports and proposals submitted by proponents, and expert advice from MTC members and internal NTDME scientific/technical staff. He noted that SSD commissions its own independent scientific and technical advice from time and this can be fed into the MTC process. He suggested there is a need to determine what actually constitutes “science” in the context of this agenda item. Dr Barry noted that this issue has been discussed at length at previous meetings and ARRTC has previously confirmed that part of its statutory role involves assessing whether regulatory decision making is based on the best available science. He suggested this standing agenda item is addressing this but queried if the current level of information provided by NTDME is adequate and appropriate. He agreed, however, that ARRTC does not have any direct role in the regulatory process. ARRTC noted that a more formal process had been used in the past to document scientific knowledge underpinning particular regulatory decisions. Mr Ball noted that, although ARRTC doesn’t have a direct role in the regulatory decision making process, the committee is still free to discuss and review the science related to various applications and decisions as required. Mr Ball indicated that NTDME would be happy to provide further information if ARRTC has specific concerns in relation to a particular regulatory matter and noted there is also scope for the MTC to seek specific advice from members out-of-session if required. ARRTC agreed that independent scientific members should be able to consider and, if warranted, comment on, the science on which particular regulatory decisions have been based. It was noted there is currently no requirement that ARRTC’s advice needs to be taken into account as part of the regulatory process.

It was suggested that members could highlight in their reports to each meeting those issues on which ARRTC comment is sought and the outcomes can be captured in the meeting summary. ARRTC agreed there is no need for a detailed compendium of science underpinning each regulatory decision and supported this approach. ARRTC also agreed the science generated and used to guide operational decision making by ERA on the mine site is of equal importance and interest.

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.

5 Research Activities5.1 Supervising Scientist Division5.1.1 SSD proposed 2012-13 research program (dr van Dam)

Dr van Dam provided a presentation on SSD proposed 2012-13 research program. Key points are summarised below.

Overview 2011-12 wet season - Overall, total rainfall for 2011-12 as measured at Jabiru Airport was just above average. Rainfall for December was almost double the average which resulted in some water quality issues in Magela and Gulungul Creeks. Cease-to-flow in Magela Creek was slightly later than usual (7 August 2012) due to the catchment being well recharged. Water quality generally improved in Magela Creek while there was some slight deterioration of water quality in Corridor Creek. ERA is looking at doing further analysis of water quality data to determine possible causes. Water quality in RP1 also improved during the period. There was no deterioration of water quality in Gulungul Creek although a number of EC spikes occurred (none exceeding 25 µS/cm) due to local flushing of groundwater. It was noted that, from 2010-11 onwards ERA has captured run-off from the TSF walls and prevented it reporting to Gulungul Creek, which may be a factor in the reduction of peak frequency observed.

Research priorities - ERA provided updated rehabilitation and closure timelines earlier this year and SSD took this into account in assessing and reprioritising the eriss research program, reflecting the increased focus on rehabilitation. Communication and cooperation between SSD and ERA staff on key projects continues to improve. The eriss work program is dominated by research projects in different stages of completion across a range of programs due to staffing and resourcing limitations. The research is addressing relevant KKNs and it is expected that ERA research projects are addressing most of the gaps.

Issues - In response to Departmental budget cuts in 2012-13 and 2013-14, savings are largely being made by reduced consultancies and not filling vacant positions. Unfortunately, the main Program affected by staff departure is the Physico-chemical Processes (PCP) Group. Internal review of the research program is planned for early 2013 to align staff resources and work priorities. It was noted that the ISWWG outcomes may have implications for SSD (e.g. bioaccumulation work) and will need to be considered in planning. In relation to the KKN revision process, ARRTC has already made some suggestions but will need to await outcomes of risk assessment workshop in early 2013. Advancement of Pit#1 rehabilitation may also have work planning implications for eriss.

Key activities in 2013 - Other key activities for eriss in 2013 include: repeating the billabong macroinvertebrate sampling program during recessional flow period; continuing the 4th year of data collection on the trial landform and determining future work requirements; conducting the 3rd and final sediment uranium toxicity field experiment; and internal implementation of duration based EC trigger framework (based on previous work on Mg Pulse) for Magela Creek.

Discussion - There was discussion regarding the future of the trial landform work and strong agreement that it should continue. It was noted that the erosion plots have been going for four years and while there has been good work on bedload (which has shown that bedload decreases significantly over time so there may not be a need to monitor annually), further work is required on analysis of the sediment and solute data. ARRTC noted that that decisions regarding future work on the trial landform will be made in the context of available resources. It was suggested one option may be to not monitor all of the plots and make greater use of remote sensing. It was noted however that a good understanding of what the data are showing is required before any work is ceased. It was noted that the current work is focused on defining the solute loads coming off the landform, so it would be useful have a hiatus to allow the four years of existing data to be properly reviewed rather than have a further year of monitoring data. It was suggested a higher degree research student could be engaged to do some of this work. ARRTC noted this and agreed that other potential areas for collaboration between the parties should be explored.

5.2 Energy Resources of Australia Ltd5.2.1 ERA - INTEGRATED TAILINGS WATER AND CLOSURE (ITWC) 2011 (Dr Sinclair)

Dr Sinclair advised that under current approvals ERA is required to complete the Ranger closure process by 2026. Consistent this timeframe, ERA is planning to manage process water over 4 discrete phases namely: (1) safe containment of process water in TSF and Pit#1/ TSF lift (complete), (2) reducing inventory using brine concentrator, cease mining in Pit#3, backfill and rehabilitation of Pit#1 (which is the current focus); and (3 and 4) use TSF as evaporation pond, lower process water inventories, manage brines, transfer tailings into Pit#3 and store salts until closure. It was noted this phased approach represents a major package of work involving a range of projects out to 2026. The PFS is expected to be completed by 2013 and a detailed closure plan and costing should be finalised by April 2013. ERA anticipates making a statement to the market in early 2013 regarding its obligations from the rights issue. A preferred “base case” Closure Strategy has been defined following a final Best Practicable Technology assessment undertaken with assistance from Dr Arthur Johnston and will be presented to MTC in December 2012. The Closure Criteria Working Group is continuing to make good progress and is working on how to integrate TO cultural knowledge into the process and an agreed definition of “detrimental impact”. Dr Sinclair noted the Ranger site is not going to be the same as it was pre mining but highlighted the need for appropriate closure criteria to inform engineering design decisions. ARRTC noted that ERA and SSD are continuing to work collaboratively on a range of rehabilitation/closure related projects.

Dr Sinclair advised it is critical to ensure that Pit#3 tailings and salt disposal options provide the best environmental outcome. He noted the current preferred option is to use thickened tailings and inject salt as liquid brine into Pit#3. Further studies are being done to improve knowledge and confidence in relation to this approach. Dr Sinclair outlined the current preferred closure strategy to finalise closure by 2026 which covers options for tailings transfer, brine management and pit backfilling, water management arrangements and controls required to reduce inflows into Pit#3 and limit seepage to Magela Creek. It was noted the proposed backfill plan for Pit#3 involved placing 30M t of low grade ore in the bottom of the pit over the next year (to Dec 2014) to be used as the brine repository, followed by 41M tonnes tailings from milling (14M tonnes 2014-16 ) and the TSF (27M t 2015-2020). After tailings have settled, remaining low grade rock will be added followed by approximately 62M tonnes of waste rock to the final landform over the period 2023-2025.

ERA has developed a holistic BPT framework and criteria which is being used to guide technical and engineering decision making and the whole closure strategy. The criteria also include TO cultural heritage components which will be further refined based on the outcomes of the pilot rehabilitation projects. Based on the BPT assessment, the “Milling to 2020 without extended water treatment” option was rated best. It was noted that final closure criteria and options for dealing with solutes coming off the rock capping still need to resolved. If solute issues can’t be successfully addressed using pit barriers, or other engineered structures, extended water treatment will be required. It was noted the principal pathway for dispersal of solutes from tailings is via the sand lens between the North-East corner of the Pit#3 and Magela Creek and a range of mitigation options are under consideration.

Dr Sinclair noted that the restoration of Djalkmarra Billabong is a key cultural objective for TOs, however, ERA currently believes that restoration is not a feasible option as modelling is showing this could be a massive solute trap. ARRTC noted that ERA will consult further with stakeholders and TOs on this issue. It was noted that ERA will accelerate rehabilitation of Pit#1 as it is a good test bed for Pit#3 rehabilitation. Dr Sinclair advised that current consolidation modelling indicates that the tailings in Pit#1 will settle at an average 5m above RL 0m. He noted that ERA is planning to submit an application to MTC in early 2013 for the higher level. Dr Sinclair suggested this may be something that ARRTC could comment on. It was noted future work includes completing modelling for full landform and investigate source definition, investigating measures for solute reduction within a BPT framework and reviewing the closure criteria.

Discussion –

There was discussion about the proposed seepage barrier between Pit#3 and Magela Creek. It was noted that the specific criteria required are still being considered but that if salts are an issue, options may include trenching in Pit around sands in the weathered zone to prevent shallow contaminated groundwater from entering Magela Creek. Dr Sinclair noted that release of solutes is predicted to occur during recessional flow periods so there is minimal dilution. He noted that a geo-fabric could also be placed over the tailings as well. It was noted that reactive solute transport is not expected to be an issue but if required the barrier could be customised to limit solutes of main concern. There was also discussion regarding the effects of the dolomite units in Pit#3. Dr Sinclair noted the dolomites are massive and in competent rock. He noted that placing acid in the bottom of the Pit will result in some activity but this should be neutralised fairly quickly. ERA is planning to use directional drilling to target the injection of brines within the rock backfill of the repository. It was suggested that existing preferential pathways could be an issue. Dr Sinclair noted the rock capping is expected to be the key issue in terms of solute signature.

Dr Sinclair was asked if data from water samples collected from the trial landform drainage have been analysed. He advised the data needs to be further analysed and reported but that the current data are based on flows from fresh rock dumps and therefore may be conservative. It was noted that sulfides associated with the low grade ore underlying the waste rock contributed to the neutral drainage observed. It was noted that ERA is significantly reliant on the brine concentrator working effectively. Dr Sinclair noted the brine concentrator is proven technology so there is a high degree of confidence that the treatment plant will work effectively. Scaling of the brine concentrator falling film tubes may present a maintenance/increased downtime risk which will be mitigated by the addition of anti scaling materials and/or gypsum seeding crystals. He advised any teething issues would be resolved when the plant is commissioned. He was asked if there is any possibility of mill production at Ranger being expanded to 4m tonnes per year. Dr Sinclair advised that increasing mill throughput had been considered as part of the Heap Leach Pre Feasibility Study but was not currently an option given the current mine life. There was some discussion about the status of the final landform and Dr Sinclair advised the final landform work is progressing well but discussions with TOs will continue and modelling results (e.g. gullies) also need to be factored into the final design.

ARRTC29-11: ERA to provide a presentation on Pit#1 rehabilitation status and proposed final landform to next meeting.

6.0 Joint KKN Review and Status Reporting (ERA/eriss)

Dr Humphrey provided an overview of the process used to develop the joint KKN status report for this meeting. It was noted that ARRTC’s comments from ARRTC28 have been taken into account. ARRTC noted that further revisions to the existing KKNs and the identification of new knowledge gaps would be informed by the outcomes of the rehabilitation/closure risk assessment workshop now proposed to be held early 2013. It was also noted the process to date had identified a number of themes and structural elements (e.g. the need to deal separately with aquatic/terrestrial ecosystems and radiological threats to human/other biota, and removal of offsite solute budgets from monitoring). Other issues included the need for water/sediment quality closure criteria to acknowledge different ecosystem types and derivation methods, possibly with different temporal phasing. Dr Humphrey outlined a matrix which he suggested could be used to reorganise the KKNs across the different temporal phases and ecosystem types and also inform the rehabilitation/closure risk assessment approach. ARRTC noted that the implications of underground mining also need to be factored into the KKN review process. ARRTC agreed that the proposed matrix approach and the existing conceptual contaminant pathways work should both be considered as part of the rehabilitation/closure risk assessment. SSD and ERA then jointly presented the current research and revision status for each of the KKNs. A number of technical presentations under a number of KKNs were also presented. Key points raised under each KKN are summarised below.

KKN 1.1.1 Surface water transport of radionuclides

ARRTC noted that research addressing this KKN is on track and agreed that separate KKNs are required for human health and aquatic biota, and that dietary aspects should be included.

KKN 1.1.2 atmospheric transport of radionuclides

ARRTC noted that research addressing this KKN is on track and agreed the KKN should be updated as additional information arises and new standards are developed (e.g. the change in radon risk coefficient (ICRP 115) and ICRP (XXX)).

Presentation: Radiation protection of the environment (non-human biota) - Dr Che Doering

Dr Doering provided a presentation covering the philosophy and recommendations of the International Commission on Radiological Protection (ICRP), the ICRP framework for environmental protection and other relevant international and national initiatives. ICRP is an independent non-government body established to provide guidance and recommendations on protection against risks associated with Ionising radiation. Recommendations by the IRCP in 1990 (IRCP60) assumed that protection of man would de facto provide protection for all biota. Following increased global community awareness of environmental issues and the development of multilateral conventions, many governments developed new legal frameworks for environmental protection. This led to reassessment of the technical basis of this recommendation noting that man doesn’t co-exist with other biota in all environments and the fact that different biota have different exposure characteristics. A revised recommendation (IRCP103) in 2007 proposed the use of reference plants and animals. Since then the IRCP Framework and further guidance on applying the framework to different exposure situations has been developed. The ICRP framework involves using reference animals and plants for relating radiation exposure to dose and derived consideration reference levels for relating dose to effect for four endpoints including early mortality, morbidity, reproductive success and genetic effects. It was noted that derived consideration reference levels for non-human biota are not legally enforceable but dose limits for radiation protection of humans are. Translating the ICRP framework into the environmental assessment context involves measuring or modelling radionuclide concentrations in environmental media (soil, water, sediment), use of transfer factors (concentration ratios) to determine radionuclide uptake by biota and use of dose conversion factors to determine internal and external doses rates to biota. Other elements of the assessment context include selection of representative organism (based on likelihood of exposure, sensitivity to radiation, importance to ecosystem structure/function and its ecological significance/status), developing a reference organism (based on geometry)and occupancy. Dr Doering advised that relevant international initiatives include the IAEA EMRAS II (2009-2012) (eriss is involved in working groups dealing with biota modelling and development of a wildlife transfer coefficient handbook); and the IAEA MODARIA (2012-2015) initiative (eriss involved in working groups dealing with analysis of radioecological data and biota modelling). Relevant national initiatives include the Review of methods and models for radiation protection of non-human biota and applicability to the Australian context (ARPANSA 2009-10), the Review of concentration ratios for non-human biota inhabiting Australian uranium mining environments (ARPANSA/DRET 2011-12) and the development of a safety guide for radiation protection of the environment (Radiation health Committee 2011-14). ARRTC noted that other work done under the Uranium Council included the collection of site specific data, the development of guidance for operators and a workshop on the use of the ERICA tool.

Discussion - Dr Doering was asked if different transfer factors are used to take account of the ingestion method and he advised that the method just looks at the average internal uptake and activity concentration in the whole of the organism. It was asked if the IRCP guideline on exposure had been derived from laboratory studies and Dr Doering advised that different methods had been used including expert judgement based on literature review. He noted that in relation to screening level, species level sensitivity analysis was done as part of the ERICA European work and a derived No effect level of 10 micro grays/hr looked at a 5% effect mark. It was noted that this is similar to the process used to develop guidelines for ecotoxicology.

KKN 1.2.1 ecological risks via the surface water pathway

ARRTC noted the current research needs under this KKN have been completed. The Contaminant Pathways Conceptual Models internal report is expected to be finalised by the end of the year and the surface water hydrodynamic model to assess far-site impacts from solutes and erosion products from proposed landform and tailings disposal options will be completed by ERA in early 2013. It was noted that outputs from this work feed into KKN 2.7.1.

Presentation - Recommendations from Independent Surface Water Working Group (Prof Barry Hart)

The Chair of the Independent Surface Water Working Group (ISWWG), Professor Barry Hart, presented the outcomes of the committee’s recent review. The ISWWG was established following on from the Ranger Groundwater review process. Prof Hart was appointed as independent Chair. The objective of the Working Group was to review surface water issues and practices at Ranger to address a range of concerns identified by GAC. Work was undertaken with GAC to identify a number of key issues of concern under four broad categories: surface water management and releases on and off site; existing monitoring practices; compliance framework and downstream monitoring; and integrity and reporting of data. The terms of reference for the review were approved in June 2012. Independent consultants were engaged to undertake work under each of the four categories. The consultant reports were reviewed by an independent science reviewer in October who wrote a consolidated report. A total of 60 recommendations were initially identified and following a 2 day workshop these were refined and consolidated to a final 15 recommendations. The review confirmed that the current water management and monitoring system at Ranger is of a very high standard. ERA is currently developing an action plan to address the recommendations.

Discussion - Prof Hart noted the use of an independent scientific reviewer had proved very helpful in ensuring the process was underpinned by a high degree of mutual trust. ARRTC commended Prof Hart and the members of the Working Group on their work. ARRTC also noted that some of recommendations could have implications for a number of the KKNs. ARRTC noted that the relevant stakeholders strongly support the recommendations and are committed to their implementation. It was noted that while ARRTC had not been directly involved in the work, a number of ARRTC stakeholder members were on the Working Group. ERA advised that while a number of the issues addressed had previously been raised with ARRTC, a number were low level issues between GAC and ERA, so it was decided to keep the process focused and to only report the outcomes of the work to ARRTC, ARRAC and the MTC. It was noted that the project had been completed much quicker than had been expected. ERA is currently looking at actions under each recommendation and will likely need to establish a number of sub-groups to work on this. It was asked if ARRTC members would have access to the final report and recommendations and ERA advised the report is still being worked on and would be provided to ARRTC when finalised. Prof Hart advised the final report and recommendations and the separate consultant reports would be published as 2 separate volumes. It was noted that the independent scientific members of ARRTC were welcome to provide any comments on the recommendations to ERA.

ARRTC29-12: ARRTC thanked Prof Hart for his presentation and commended the Working Group on its work.

ARRTC29-13: ERA/GAC to provide copy of the ISWWG report and recommendations to ARRTC members once it has been finalised.

KKn 1.2.2 land irrigation

ARRTC noted that research addressing this KKN was mostly on track and near completion. ARRTC agreed the KKN should be refocused to investigate the fate of the contaminants in the LAA’s and their potential impacts on groundwater and surface water quality, including potential off-site contributions to loads and their effects.

Presentation - Land Application Area Rehabilitation –TRIAL REHABILITATION (Dr Ping Lu)

Dr Lu noted this is a collaborative project between ERA, eriss and Safe Radiation Pty Ltd. There are 2 main exposure pathways: direct (gamma) irradiation and inhalation of dust. Dose contribution from the entire LAAs is quite low at 80 µSv yr-1, which is about 27% of the dose constraint (assuming RPA overall public dose constraint is 300 µSv/yr). Magela LAAs (A & B) contribute the majority of the dose (>72%). Dr Lu was asked why all pathways were added together and he explained the aim is to understand the dose from the whole site including impacted LAA and the landform covered by waste rock. Dr Lu was asked why the occupancy of 1400 hours was chosen and it was noted these figures were used as examples. It was suggested the annual dose figure for the dust inhalation pathway looked a little high and Dr Lu noted that most of the radioactivity in the LAAs is in the top 5cm. It was noted that software is being used to adjust the occupancy scenarios (which are highly conservative) in consultation with TOs. The trial in Magela LAA was designed to test the effectiveness of various rehabilitation methods and refine associated parameters. Four options were tested: (1) baseline (removal of pipes), (2) soil mixing, (3) soil removal and (4) soil removal and mixing. Pre and post remediation measures were taken on soil gamma radiation, soil radionuclides and chemistry analysis, radon exhalation and dust suspension using previously established dose factors. External gamma radiation dose rate was measured at different heights for adults and children sitting and standing. Results indicate that surface activity concentration in section 1 (without remediation) reading was around 100 which dropped to 10% of pre remediation levels in section 2. In section (scrapped) surface activity dropped to 10-18% of pre remediation level. Regarding dust suspension, results in section 4 based on modelling data dust radioactivity dropped to 19% of pre-remediation level. It was noted that the focus on dust was because in natural soil it is expected the activity is distributed but in the LAA most of the activity is in the top 5cm and the due to the activity in the top 2cm (the fraction of dust that would be resuspended), the dust numbers were so high. It was noted the numbers would be different for waste rock and the final dose would depend on how people access the land. A conservative occupancy scenario has been used based on different levels of activities and posture for adults and children/babies. It was noted that access to the site changes between wet and dry season. It was noted that radiation dose rate received through occupancy of the land application areas after different rehabilitation treatments through all pathways reduced between 45% (mixing or scrapping) and 75% (mixing and scrapping). The final product will provide annual effective radiation dose figures through 4 key exposure pathways. A computer based dose model has been developed and this information will guide optimisation of dose allocation and rehabilitation strategies. The computer model has been updated to include all of the different scenarios and rehabilitation options. Future activities include developing a rehabilitation plan for Magela LAA A and B in consultation with TOs and commencing rehabilitation in 2014 subject to MTC approval.

Discussion – It was asked how the top soil scraped for the construction of the levee would be disposed of and whether this posed any issues for the environment or workers. ERA advised the top soil will be disposed of in the borrow pit and that there are no risks posed to workers.

KKN 1.2.3 wetland filters

See KKN 253.

KKN 1.2.4 ecotoxicology

ARRTC noted that research addressing this KKN is mostly on track and revisions to the KKN would be based on the outcomes of the rehabilitation/closure risk assessment.

Presentation – maganese toxicity (Dr Andrew Harford)

Dr Harford advised that Mn has been listed as a lower-priority contaminant of concern for many years. More recently elevated levels of Mn in bores have been observed and limited toxicity testing in 2008 showed higher toxicity compared to literature especially for Hydra viridissima (IC10 = 60 µg L-1 Mn). Testing of brine concentrator distillate containing 130 - 230 µg L-1 Mn resulted in reduced Hydra growth rates. Also recently became aware of a draft environment quality statement for European Union of 62-123 µg L-1 Mn. To date work has been completed for 2 species: Lemna (Duckweed) IC10 = 2.4 mg L-1 and Chlorella (Alga) IC10 = 14 mg L-1. Preliminary toxicity estimates have been completed for 4 species: Hydra viridissima IC10 = 0.09 mg L-1; Moinodaphnia macleayi IC10 = 0.48 mg L-1; Amerianna cumingi IC10 = 0.60 mg L-1; and Mogurnda mogurnda IC10 = 74 mg L-1. A significant loss of Mn (~200-300 µg L-1) was observed in the Hydra test which was not seen in 2008. A Mn fate test was done which recovered 70-87% and an aqua regia extraction will be done to see if Mn is precipitating onto the test plates. It was noted that as a precipitate was observed, bacteria could be contributing to Mn oxidation or potentially something may be being released by the Hydra. It was also noted the same effect wasn’t observed in the Ngarradj water sample tested in 2008. It was suggested the effect could be light related. ERA noted that water would be directed to a retention pond prior to release and that the brine concentrator will have a chevron which will remove metals. It was noted that DOC is not a significant modifying factor for Mn. It was also noted that redox is a key determinant factor and that further laboratory work will be done.

Presentation - Toxicity of U to sediment biota – derivation of sediment guideline for U (dr Andrew Harford)

ARRTC noted the aim of this work is to derive a sediment quality guideline for uranium. Two pilot studies have been completed to date, however, the main experiment was postponed last season. Datasets, data analysis and main experiment design has been completed. For pilot study 2, macroinvertebrate counts for all U treatments and lab control have also been completed as has the microinvertebrate ecogenomics work. Bacteria have been re-sequenced but there was an issue with the first run which requires further investigation. Macroinvertebrate results show a significant difference in richness (ANOVA) and the microinvertebrate results indicate “NOEC” at 500 mg kg-1 (PERMANOVA), and that Uranium was a strong predictor of differences. It was noted that Total Organic Carbon was also a factor. The results show that effects are evident but need to determine how to use these community data to calculate a No Effect Concentration (NEC) and derive a Sediment Quality Guideline. Also looking at thresholds and investigating three recent methods: Non-Linear CAP (Millar et al 2005); Threshold Indicator Taxa ANalysis (TITAN; Baker and King 2010); and Gradient Forests (Ellis et al 2012). Key conclusions from this work are that a number of assemblage-based analysis methods are useful for deriving a NEC, species identification will add value to the results, and that an experimental design that maximises the number of concentrations is best for determining a NEC. The final experimental design will involve the agreed spiking method and more treatments, which will be deployed following rain and retrieved in April 2013. The results of this work will be reported in late 2013/early 2014.

KKN 1.2.5 mass balances and annual load limits

ARRTC noted that research addressing this KKN is mostly on track and revisions to the KKN would be based on the outcomes of the rehabilitation/closure risk assessment and updated to reflect current activities on the mine site.

Presentation - Gulungul Creek Mg loads (Dr Wayne Erskine)

Dr Erskine advised the results being presented are based on work by Dr Alana McKay. SSD maintains 3 gauging stations upstream, mid and downstream on Gulungul Creek. There are some missing data (Feb-Mar 2007) but this has been completed using Hydstra. Continuous monitoring data were collected between 2005-06 and 2011-12 by eriss (earlier data for G8210012 by NRETAS). Discharge has been calculated from heights using rating curves and there is a large dataset of lab EC, field EC and continuous EC. ARRTC noted this work arose from stakeholder concerns regarding level of mine derived solute loads in Gulungul Creek. Results of this work are similar to those reported by Chris LeGras for ERA. MgSO4 is a key indicator of mine derived waters and Mg and EC are strongly related. Mg loads were calculated by converting EC to Mg concentrations and multiplying by simultaneous discharge for each time increment and summed over total time period. Mg loads were compiled for upstream and downstream stations. Results show an average of 7.8 tonnes per annum of Mg, or 37 % of the mean annual difference of 21 tonnes per annum, is derived from the mine, while the rest is from diffuse sources. It was estimated that about 2-4 tonnes per annum were coming of the TSF wall. It was noted the lower difference between upstream and downstream during low flow years is due to the diffuse sources.

Discussion - It was asked why Mg rather than SO4 is used as a surrogate for EC and it was noted this was because Mg has higher toxicity than SO4. It was also asked if the EC results include contributions from other non-mine areas such as tributaries on the LHS bank. ARRTC noted that the Gulungul Creek results show that the mine derived contribution to Magela Creek is an order of magnitude greater. It was asked if EC can be affected by bicarbonate downstream and if this would change the relationship and it was noted that data are not available to investigate this currently. ARRTC noted that one of the recommendations from the ISWWG was to get reference from downstream station to improve knowledge of catchment as a whole. Dr Mudd noted that GAC also has concerns about the levels of uranium in Gulungul Creek and asked if there would be a much different methodology involved to determine this. It was noted that LeGras also measured uranium so may be possible to do a comparison, but there is probably less confidence in the uranium data.

KKN 1.3.1 Surface water, groundwater, chemical, biological, sediment and radiological monitoring

ARRTC noted research addressing this KKN is mostly on track. It was noted that this KKN informs a range of other KKNs and will be revised on the basis of the outcomes of the rehabilitation/closure risk assessment. ARRTC also noted that ERA is undertaking a range of on- and offsite monitoring while eriss is more focused on offsite monitoring, with a significant biological monitoring component. ARRTC also noted there are also potential implications for monitoring generally arising from the ISWWG recommendations.

Presentation – onsite/offsite water quality monitoring (ms iles)

Ms Iles advised the main point sources of mine water in Magela Creek are RP1 and Corridor Creek. Water quality in RP1 has significantly improved due to the interception trench and addition of permeate. Late season releases from RP1 can cause problems with EC due to low flows. Water quality in GTB-Corridor Creek system deteriorated during the dry season and macroinvertebrate studies also showed some changes. The season variation in EC in GTB has been increasing over recent years and was particularly pronounced in the 2010 dry season and more so in 2012. Mg levels have also increased while U levels have remained low with a few spikes since 2004. ERA is continuing to manage water quality onsite by diverting pond water through RP1 and CC wetland filters. ERA is also looking at how to improve water quality outcomes for GC2. It was previously though that the influence on the western channel at 009 was dominated by RP1, but work by Tilliard for the ISWWG found higher levels of EC coming from GTB than RP1 and has recommended that the five monitoring sites along the creek be used to better understand sources from the mine site. Grab sample data for Magela Creek show that EC has remained very low but it was noted that continuous monitoring provides a much better overview of changes in EC over time. A paper has been prepared proposing the move towards using continuous monitoring as part of the compliance framework. In Gulungul Creek, Mg levels upstream were higher than downstream and uranium levels remained under the Magela Creek focus limit. It was noted that the ISWWG recommended measuring unfiltered metals and Ms Iles advised this was due to issues with event based sampling and potential problems with samples being left in the field too long and the Australia WQ guidelines recommending that total metals be used. It was noted that SSD have a conversion between total versus filtered metals. It was also noted that stakeholders have previous raised concerns about the potential for metals to slowly accumulate on the floodplain and that measuring loads was important. Potential issues with this include difficulties in capturing the entire load for full season due to patchy datasets and interpreting the data. It was noted that the ISWWG recommended looking at this further.

Presentation – Atmospheric radioactivity monitoring at Ranger and Jabiluka (Dr Andreas Bollhöfer)

Dr Bollhöfer advised that eriss has three atmospheric monitoring stations (Jabiru, Jabiru East and Mudginberri), measuring radon decay product potential alpha energy and dust long lived alpha activity (LLAA) concentration, respectively, and now has similar continuous monitoring data record (2 years) to that for the surface water monitoring program. The monitoring results from Jabiru and Mudginberri radon station were presented. In 2012 the downtime of the stations was less than 20%. ARRTC noted that the mine related doses from radon decay products for the reporting period was 0.021 mSv at Jabiru and 0.003 at Mudginberri, and for LLAA, the mine related dose was less than 1 micro sievert at Jabiru and less than 0.1 micro sievert at Mudginberri. It was suggested the differences in SSD and ERA results may be due to ERA only measuring weekly and instrument failures during the wet season.

Presentation – Bioaccumulation of uranium and radium in freshwater mussels from Mudginberri and Sandy Billabongs (Dr Andreas Bollhöfer)

Dr Bollhöfer advised that SSD undertakes an annual collection and analysis of a bulk mussel sample from Mudginberri Billabong at the end of each dry season. Aged mussels from Mudginberri Billabong and Sandy Billabong are analysed every 3rd year and the results are compared to previous years. In 2011, SSD also looked at polonium in mussels. ARRTC noted that the Ra and 210Pb results for 2011 were within one standard deviation from previous collections which indicates there has been no change in U, Ra and 210Pb over this time. There is some variability across age classes but no trend. Mussels collected at end of wet season are generally in poorer condition and thus may have higher radionuclide activity concentrations. ARRTC noted the annual committed effective dose of 0.14 mSv based on assumption of 2kg of mussels being ingested by a 10 year old child was almost exclusively from natural background and was not mining related.

Presentation – Toxicity monitoring using freshwater snail reproduction (Dr chris Humphrey)

Dr Humphrey advised that monitoring results indicate that snail egg production is responsive to mine-associated elevated EC in Magela and Gulungul Creeks. Continuous monitoring data indicate there is a significant relationship between seasonal variability in mean upstream-downstream difference values in EC and corresponding variability in mean egg number, with egg production increasing with increased EC. There is also a significant interacting effect of water temperature and EC on snail egg counts with egg production increasing with increasing EC at lower water temperatures (27-29oC) and significantly reducing at higher water temperatures (>30oC). ARRTC noted that these relationships were not able to be replicated in the laboratory with only increasing egg production with increasing water temperature being observed. It was also noted that it is not clear at this stage whether these results are ecologically significant but SSD will continue to monitor.

KKN 2.1.1 defining the reference state and baseline data

ARRTC noted that a number of research projects addressing this KKN have been completed (e.g. pre-mining radiation conditions; soils data and literature as part of LAA assessment; Magela water quality triggers based on reference data) but a number of other projects have been delayed (e.g. groundwater baseline derivation; geomorphic characterisation of Gulungul catchment; landscape dynamic from aerial photographs). It was noted last meeting that this KKN overlaps with the analogue site and criteria development KKNs and ARRTC agreed this KKN should be revised based on the outcomes from the rehabilitation/closure risk assessment process.

KKN 2.2.1 Landform Design

ARRTC agreed that, due to Mr Lowry’s absence, the presentation on landform modelling should be deferred to next meeting. Ms Iles advised the latest version of final landform has been developed by ERA based on consultations with TOs and previous modelling results. The design takes account pre-mining drainage conditions and has Djalkmarra Billabong reinstated but not in same spot. The CAESAR model has been updated to take account of consolidation with and without surcharging and the model has been run across the whole of final landform. Work is proposed to incorporate sediment traps and rock armouring and also data from erosion and water quality monitoring and eco-hydrology work on the trial landform. SSD is also doing evolution modelling on trial landform and a LiDAR capture looking at erosion characteristics. A new framework will be developed for landform design which will incorporate a range of other factors including the various development scenarios, extreme rainfall and associated flooding events. There was considerable discussion about the current state of understanding of erosion, vegetation dynamics, surface and groundwater chemistry and hydrology derived from the trial landform and whether this is adequately representative of how the actual rehabilitated landform will perform. ARRTC noted the KKN will be re-sequenced with the other rehabilitation related KKNs and revised based on the outcomes from the risk assessment process.

Presentation - LiDAR capture for the Alligator Rivers Region (Dr renee Bartolo)

Dr Bartolo advised that SEWPaC and DCCEE commissioned a LiDAR data capture for the ARR floodplains which included Nabarlek catchment, Myra Camp and the East Alligator landslip area. SSD is keen to assess if LiDAR is the best method to use in ARR. LIDAR can provide information on canopy structure (height and cover) which can be used to assess ecosystem and landscape health post rehabilitation. It was noted that ERA has a matching dataset (which overlaps the SSD one) which is being used to model hydrodynamics for part of the Magela Creek catchment pertaining to Ranger. This modelling will now be extended to the whole catchment with the input of the LiDAR data. It was also noted the intensity image can be used as a substitute for aerial imagery and provides good contextual imagery. GA and the CRC-Spatial Information are currently doing work to validate data. The LiDAR derived DEM provides good information on water and vegetation types. SSD is currently working with NT Government to compare the precise point positioning approach using aerial photography to the LiDAR approach. LiDAR is also being used to generate canopy height and foliage models. ARRTC noted that future work will include using LiDAR data to develop hydrodynamic models and assessing sea level rise impacts as part of NERP/NAH, using DEM in the application of landscape evolution modelling to determine erosion and landslip potential within the catchment and the validation of the LiDAR dataset by the CRC for Spatial Information.

Presentation - soil erosion and Water quality on trial landform (Dr wayne erskine)

Dr Erskine advised his presentation is based on work by Dr Mike Saynor. The results for rainfall and bedload yield for the four plots on the trial landform were published in the 2011-12 SSD Annual Report. Results for plots 2 and 3 are still being calculated. Previous issues with probes have been resolved and results will be presented to next ARRTC. Data is now being collected at 30sec intervals. Results from plot 1 indicate that runoff was lower during the first year due to the presence of pore spaces in fresh rock but by year 3 pore space has been filled. A hydrological threshold exists where a rainfall event of greater than 29mm is required to fill surface storage and generate runoff. As ripping differed on other plots, further work being done to determine differences in runoff and looking at using laser scanning to determine pore space. The bedload results for all plots confirm previous evidence that bedload yield decreases significantly over time. The results also indicate that gravel increases over time while silt and clay decreases leading to surface armouring. Weathered material from Jabiru industrial area was mixed and run through plot 1. The absence of any instantaneous spikes provides confidence that the mica was the cause of background noise observed previously. It was noted that as waste rock mixed with weathered material is not a viable cap material there may be limited value in continuing with plots 3 and 4. ERA agreed and noted that there will be limited available laterite anyway. There was discussion about the implications of ceasing this work and whether further data are required. It was noted the key issue is the time required for data processing.

KKN 2.2.2 - Development and agreement of closure criteria from the landform perspective

ARRTC noted that research addressing this KKN is mostly on track and that closure themes and objectives and a post closure land use statement are being developed. ARRTC noted that the ERs require that “detrimental impact” be defined and SSD is developing a discussion paper on this. Working groups will be established for each closure theme. ARRTC noted that further revision of this KKN will be based on the outcomes of the rehabilitation/closure risk assessment as applied to the decommissioning, stabilisation and monitoring, and post closure phases.

KKN 2.2.3 - Water quality in seepage and runoff from the final landform

It was noted the some research addressing this KKN has been reported in presentations under previous groundwater related KKNs. ARRTC noted that elements of research have been delayed and other aspects have been addressed by Intera. It was noted that reworking of some stockpiles on site can make it difficult to get good water quality data but the 1c stockpiles are less dynamic than others and provide an opportunity to get good data. It was noted that the outcomes of research under this KKN should be able to be reported at next meeting. ARRTC also noted that the ISWWG report recommended that more continuous monitoring of solutes be undertaken to enable a solute mass balance to be developed for the release circuit. ERA advised that a number of further water quality studies are planned. ARRTC noted that further revision of this KKN would be based on the outcomes of the risk assessment.

KKN 2.2.4 - GEOMORPHIC BEHAVIOUR AND EVOLUTION OF THE LANDSCAPE

ARRTC noted that research addressing this KKN is on track and modelled results have been compared with actual data from plot 1 on the trial landform. Work on the CAESAR landform evolution modelling by Lowry et al is progressing well and results were presented at the 2012 Life of Mine conference. Prof Tom Coulthardt worked with SSDI on consolidation and evolution of the Pit#1 cap and the IR on this work is currently being reviewed. Further research looking at slack water deposits and paleofloods in the ARR is planned. SSDI may also be involved in developing hydrodynamic models. ARRTC noted this KKN will be revised on the basis of a logical framework to be developed for a range of rehabilitation and post closure related KKNs and the outcomes of the risk assessment. It was noted KKN currently doesn’t recognise the need for hydro-meteorological data for landform simulations.

KKN 2.2.5 - RADIOLOGICAL CHARACTERISTICS OF THE FINAL LANDFORM

ARRTC noted that research addressing this KKN is on track and the KKN remains valid. It was noted this KKN should be considered as part of the proposed FEPS process given the need to consider radiological exposure and dose model development. Further work is required to determine levels of radon and decay products generated by the final landform in air (inhalation pathways). ARRTC noted that the far field is very low and is expected to be lower once the minesite has been rehabilitated, although near field exposure to people accessing the minesite may be different.

Presentation - Radon exhalation from trial landform (Dr andreas Bollhöfer)

Dr Bollhöfer advised this three year project aims to predict long-term 222Rn exhalation flux from the rehabilitated landform and contribute to the development of closure criteria by investigating seasonal and long-term changes in radon (222Rn) exhalation for four different treatments, and dependency on season, cover type, weathering and compaction effects and developing vegetation. It was noted that Radon is part of the U decay series with a half life of approximately 4 days. Radon is generated in the soil and if injected into the soil pore space can be transported by diffusion following concentration gradient (Fick’s law) or by convection (Dacy’s Law) proportional to pressure difference. Radon is a noble gas and exhaled from the soil surface, radon decay products are isotopes of heavy metals so may attach to aerosol and lodge and further decay in lungs. Therefore measuring radon exhalation is the first step in calculating inhalation dose. Radon exhalation from the Trial Landform has been determined by collecting 222Rn using activated charcoal cups and measuring radon decay products using Nal γ-spectroscopy. In addition environmental gamma dose rates on the Trial Landform and 226Ra activity concentrations have been measured using HPGe γ-spectroscopy. The main conclusions from this work are that 222Rn activity flux density is higher during the dry season from waste rock and laterite mix compared to waste rock only and the wet season, and there is no difference due to vegetation. ARRTC noted that SSD will continue measurements to determine if seasonal variability establishes in waste rock only and a new joint SSD/ERA project is proposed to determine the radon diffusion length for waste rock using columns of variable heights filled with waste rock.

KKN 2.3.1 - Containment of tailings and other mine wastes

ARRTC noted that research addressing this KKN is on track. It was noted that no revisions are required but the KKN overlaps with KKN2.3.2 and KKN2.3.3 and there is a need to agree scenarios to model for 10,000 years.

KKN 2.3.2 - Geochemical characterisation of source terms

ARRTC noted that the geochemical modelling work being done by Intera for ERA is addressing this KKN. It was noted that Pit#1 provides best opportunity to test assumptions regarding in situ waste rock and water interaction. Future research will be refined based on outcomes from FEPS process. ARRTC noted this KKN overlaps with a number of other KKNs but no revisions are required at this stage.

KKN 2.3.3 - Aquifer characterisation and whole-of-site model

ARRTC noted that research addressing this KKN is on track. ERA advised that an extra 78 bores have been installed and 102 bores are being sampled annually with data being reported to MTC on quarterly basis. This is updating ERA’s whole-of-site conceptual understanding of groundwater contamination dynamics and feeds into systems assessment and FEPS process. ERA will continue to monitor the TSF and undertake further in situ hydraulic testing around Pit#3 and R3 Deeps. There was some discussion regarding the number of statutory monitoring bores on site and whether more are required. It was noted that the water management plan is a statutory document and that all bores (operational and statutory) are reported in the annual wet season report. There was also discussion about whether further in situ testing is required for the Magela Creek sands and characterisation of the TSF plume. ERA advised that a CBD characterisation study was done to determine density of tailings in the TSF and stratified pore water samples were used to get a foundation sample 1m depth below tailings mass. ERA advised that there are no plans to drill more deep bores through the tailings mass at this stage due to concerns that a pathway could be created. ARRTC noted that the work by Intera is addressing the issue of connection between the Pit#3 and Magela Creek. ARRTC noted that Pit#1 contains tailings from Pit#3 so will provide valuable information on groundwater aspects associated with Pit#3 rehabilitation. There was discussion about the possible cause of the high concentrations observed at the SW end of the TSF. It was noted that when the TSF was constructed there was fault in that location and there is probably a preferential pathway established. It was also noted, however, that monitoring bores down gradient indicate that the plume hasn’t migrated very far if it’s there. It was also noted that the TSF dam wall was constructed with a collection system that flows to the South interception trench so the elevated levels are probably due to toe drainage water. ARRTC noted this KKN probably could be split to place greater emphasis on the aquifer characterisation aspects.

KKN 2.3.4 - Hydrological/hydrogeochemical modelling

ARRTC noted research addressing this KKN is being undertaken by Intera on behalf of ERA.

Presentation –Pit 3 Solute Loading to Magela Creek (Intera, dr John Sigda)

ARRTC noted this is a collaborative project work with range of contributors including CSIRO, RioTinto and Intera. Dr Sigda advised the objectives of the project are to characterise groundwater flows and associated solute source strength and duration, assess transport of solutes from Pit#3 waste rock and tailings to Magela Creek, assess brine migration from Pit#3 closure and carry out a systems analysis of Pit#3 closure. Conceptual and numerical models of groundwater-surface water interactions near pits and a 3D groundwater flow model have been developed. Flow rate in Magela Creek is the key driving force influencing groundwater-creek stage dynamics and dilution over different temporal scales. Shallow sands between Pit#3 and Magela Creek are an important hydrogeological feature. Conceptual model shows that interactions between groundwater driving forces determine when groundwater can discharge into Magela Creek surface water (groundwater inflow can occur when there is no flow in creek) and that there are potential “fast paths” due to the unconsolidated Magela sands, the Djalkmarra fault and carbonates located between the two pits. It was decided to extend model domain to include both pits and include leaching from waste rock and tailings. Waste rock and tailings sources were characterised using tailings studies to estimate Mg concentrations and tailings pore water expression rates, concentration and duration. Waste rock leaching occurs predominately in the vadose zone where pyrite oxidation can increase the rate of Mg release. Findings from the waste rock source strength modelling included that the maximum Mg2+ concentration for 2s waste rock is an overestimate of waste rock Mg2+ leachate concentration, pyrite oxidation and Mg2+ release are not expected to be important in saturated waste rock and that pyrite oxidation/exhaustion rate is a function of residence time, sulphide content, and reactive mineral surface area. Solute loading to Magela Creek was simulated for a number of scenarios. Findings included that Mg will quickly migrate through shallow sand into Magela Creek sediments and surface water, that highest Mg concentrations in Magela Creek surface water are predicted to occur during end of the wet season and into the dry season when surface water levels regress faster than groundwater levels, and for given flow/transport conditions, creek loading is likely to be directly proportional to Mg concentration in waste rock leachate. The reactive solute modelling indicates that reactive constituents will not be significant attenuated. Results of the brine migration modelling indicate that this should not be a significant issue through there are a number of uncertainties associated with all of the modelling results. ARRTC noted next steps will include simulation of how Pit#3 closure designs could mitigate solute egress from the pit to Magela Creek by changing residence times or geochemical conditions, and further studies to reduce uncertainty about waste rock source behaviour.

Presentation – systems analysis of ranger closure process (Intera, dr Matt Kozak)

Dr Kozak noted that scenario approaches are a useful systems modelling technique for dealing with regulatory requirements involving long timeframes such as the Ranger 10,000 year tailings isolation requirement. Such long timeframes need to address changes in boundary conditions, geological processes uncertain events (e.g. extreme weather events). Modelling for very long time frames involves very long run times so probabilistic analyses can be useful. Scenario development can also be helpful to deal with operational uncertainty, habitual an

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Alligator Rivers Region Technical Committee Meeting 29 5 ...environment.gov.au/.../files/summary-29th-meeting.docx · Web viewThe Chair (Dr Barry) welcomed members to the 29th meeting