Alligator Rivers Region Technical Committee
Meeting 38
16 – 17 May 2017
Record of meeting
Darwin, NT
This document is a summary record of the scientific information presented to, and the discussion and actions arising from, the 38thmeeting of the Alligator Rivers Region Technical Committee. ARRTC meeting summaries are used to inform planning and prioritisation of scientific research activities.
ARRTCDr Simon Barry / Chair, Independent Scientific Member
Ms Jane Coram / Independent Scientific Member
Prof Paul Boon / Independent Scientific Member
Dr Jenny Stauber / Independent Scientific Member
Assoc Prof Gavin Mudd / Environment NGO stakeholder member
Mr Adam Thompson / Northern Land Council
Ms Sharon Paulka / Energy Resources of Australia
Mr Matthew Whitfort / Supervising Scientist
Apologies
Mr Andrew Johnston / Independent Scientific Member
Prof David Mulligan / Independent Scientific Member
Presenters and observers
Dr Geoff Pickup / Consultant
Mr Chris Malcolm / Gundjeihmi Aboriginal Corporation
Dr Howard Smith / Northern Land Council
Dr Ian Hollingsworth / Horizon Environmental Soil and Survey Evaluation forGundjeihmi Aboriginal Corporation (Presenter)
Michelle Iles / Energy Resources of Australia Limited
Ben McTavish / Energy Resources of Australia Limited (Presenter)
Dr Ping Lu / Energy Resources of Australia Limited (Presenter)
Andy McLellan / Energy Resources of Australia Limited
Toby McGrath / Water Solutions for Energy Resources of Australia Limited (Presenter)
Graeme Esslemont / Energy Resources of Australia Limited
Peter Anderson / Energy Resources of Australia Limited
Sally Strohmayr / Department of Primary Industry and Resources
Pete Cotsell / Parks Australia Division
Sally-Ann Atkins / Parks Australia Division (Presenter)
Mr Keith Tayler / Supervising Scientist Branch (Presenter)
Dr Rick van Dam / Supervising Scientist Branch (Presenter)
Dr Chris Humphrey / Supervising Scientist Branch (Presenter)
Mr Peter Baker / Supervising Scientist Branch (Presenter)
Dr Renee Bartolo / Supervising Scientist Branch (Presenter)
Mr John Lowry / Supervising Scientist Branch (Presenter)
Dr Mike Saynor / Supervising Scientist Branch (Presenter)
Ms Berlinda Bowler / Supervising Scientist Branch
Ms Kate Dixon / Supervising Scientist Branch
Dr Andrew Harford / Supervising Scientist Branch
Dr Che Doering / Supervising Scientist Branch
Ms Kate Turner / Supervising Scientist Branch
Mr Mike Welch / Supervising Scientist Branch
Mr John Miller / Supervising Scientist Branch
Ms Lisa Chandler / Supervising Scientist Branch
ACRONYMS
ARPANSAAustralian Radiation Protection and Nuclear Safety Agency
ARRTCAlligator Rivers Region Technical Committee, the Committee
CCLAACorridor Creek Land Application Area
ECElectrical conductivity (of water)
ERAEnergy Resources of Australia Limited
ERISSEnvironmental Research Institute of the Supervising Scientist
ERMEnvironmental Resources Management Australia Pty Limited
GACGundjeihmi Aboriginal Corporation
GCT2Gulungul Creek Tributary 2
KKNsKey Knowledge Needs
OWSOffice of Water Science, Department of the Environment and Energy
RMCPRanger Mine Closure Plan
SSBSupervising Scientist Branch, Department of the Environment and Energy
TSFTailings Storage Facility, Ranger uranium mine
1Welcome and opening session
The meeting commenced at 9.07 am.
The Chair, Dr Simon Barry, welcomed members and observers to the meeting.
1.1Acknowledgement of Country
The Chair acknowledged and paid respect to the Larrakia people, the traditional owners, past and present, onwhose country this meeting took place.
1.2Disclosure of conflicts of interests
Dr Stauber noted CSIRO’s ongoing assistance with SSB’s uranium sediment toxicity project.
Dr Mudd noted he continues undertaking consultancy work for GAC.
1.3Attendance and apologies
As recorded above. The resignation of Professor David Mulligan from the Committee was acknowledged.
1.4 Observers
As recorded above.
1.5Correspondence
ARRTC noted the status of correspondence (incoming or outgoing) to 16 May 2016.
1.6Governance
SSB provided an update on committee governance arrangements. ARRTC was advised that formal appointments are expected to be finalised in August 2017, and members notified at that time.
1.7Publications
Publications for the Supervising Scientist Branch and ERAfor the period 1 July 2016to 31 March 2017 are at AttachmentE of the ARRTC Report and in the ERA report respectively.
2ARRTC 37 Outcomes
2.1ARRTC 37 – Summary record
ARRTC endorsed the minutes, with verification of astatement to be checked by Mr Andrew Johnston.
2.2ARRTC 37 – Actions arising
Actions noted as complete were removed. Outstanding actions were updated.
3Research
3.1Energy Resources of Australia Limited –Ms Sharon Paulka, ERA
Associated presentation: 3.1 ERA operations and closure update
Associated paper:3.1 Report to the Alligator Rivers Region Technical Committee meeting # 38Environmental studies and closure
ERA advised that Mr Tim Eckersley, former General Manager Operations, had moved to Rio Tinto, effective January 2017.Ms Lesley Bryce has been formally appointed as General Manager Operations and will commence on 5 June 2017.
Operations
An update on work health and safety performance was provided, with improved performance noted following implementation of enhanced procedures.
An update on environmental performance since January 2017 was provided. Five minor incidents had occurred and will be reported onat the next Routine Periodic Inspection.
An update was provided on rainfall and TSF levels, water management (pond and process water bodies), operational performance, and the 2016 outcomes for the three near-term strategic priorities.
Closure
An update on progressive rehabilitation was provided, including amount spent on rehabilitation and water management to date, status of the feasibility study for the Ranger rehabilitation program in 2017, and progress made on Pit 1 capping, dredging, brine concentrator and brine injection.
An updated schedule of Ranger closure was presented which shows major closure and rehabilitation activities and milestones underway and proposed up to 2026. ERA also provided the timeline for their technical studies up to March 2018 (contained in the ERA report).
ERA noted the Ranger Mine Closure Plan will be made available to the public, most likely in quarter 1, 2018 and updated annually.
The ARRTC commended ERA for its intentions to make the Closure Plan publicly available.
An update onand aerial photographs of the progressive rehabilitation of Jabiluka was provided.
Pit 3 tailings deposition strategy
ERA described the change to its approach for the Pit 3 tailings deposition strategy from subaerial (from top/side of pit) to sub-aqueous, following advice from a tailings consolidation consultant. The change in method included a full risk assessment. SSB advised it was seeking its own independent expert advice on potential longer-term impacts:and was of the view that the change in strategy may have to include review ofclosureschedule timeframes and water movement. Solute transport and landform subsidence were noted by SSB as the two potential environmental issues of most concern.
ARRTC acknowledged the change in strategy was significant, and requested a presentation on the consolidation work, potential operational challenges including delay to the rehabilitation schedule, and risks associated with having such a large pit full of water requiring rapid consolidation and backfill.
ACTION 38-1:ERA to present at ARRTC 39 (December 2017) an update on the change to the Pit 3 tailings deposition strategy and consolidation work generally,and SSB to present on the results of SSB’s independent review of the potential longer-term operational and environmental risks of the strategy change.
3.2SSB overview and ERISS proposed 2017-18 research and monitoring program – Mr Keith Tayler and DrRick van Dam, SSB
Associated presentation: 3.2 Supervising Scientist Branch update
Associated presentation: 3.2 SSB 2016-17 update and ERISS 2017-18 research and monitoring program
Associated paper:3.2 Supervising Scientist Branch proposed 2017-18 research program
Branch update
SSB provided an update on the status of its review of ERA’s Ranger Mine Closure Plan, the development of the Supervising Scientist’s Rehabilitation Standards, the Branch’s staffing profile, and the Departmental restructure which will result in the Branch joining a newly formed Reef, Heritage and Marine Division.
SSB advised it had developed a 10 year plan: a forward work program for the next 10 years. The Plan arose from the screening level ecological risk assessment from which the KKN’s were derived and endorsed by ARRTC in 2016. The Plan maps out the Branch’s research, monitoring, and supervision activities and projects to 2026, each scheduled, costed, and aligned with ERA rehabilitation activities. The Plan, which will be published in the near future, provides a clear program of work and the ability to report directly against it.
Research and monitoring program
SSB provided a summary of the 2016-17 wet season water quality results and research progress, and the 2017-18 planning process and proposed work program.
Regarding water quality, monitoring has shownan overall trend of improved water quality over the past eight wet seasons. A number of EC spikes were noted in Gulugul Creek in February 2017, but these were not severe enough to triggerexceedance actions. It is thought the spikes were related to the release of water into the Gulungul Creek Tributary 2 (GCT2).
Regarding the 2016-17 research program, significant progress has been made across the following teams:
- Water and Sediment Quality Team:the completion of the multiple lines of evidence assessment formagnesium water quality Rehabilitation Standard, the Magela Creek sand bed sub-surface water quality and ecological pilot study, the development of the freshwater mussel chronic toxicity test, and advice obtained forthe Rehabilitation Standard for sulfate.
- Revegetation and Landform Team: attainment of Beyond Visual Line of Sight qualifications for drone operations, the modelling of effects of riplines on a rehabilitation surface project now in the write-up phase, and refinements to CAESAR-LisFlood modelling.
- Environmental Radioactivity Team: attainment of the first measurement of 231Pa in mussel flesh, the measurement of226Ra and metals in mussel shells to establish tissue-to-whole organism conversion factors for biota dose modelling, and refinement of radon dispersion modelling of final landform.
The proposed 2017-18work program, aligned with SSB 10 year plan, is focussed on KKNs, and is made up of54 research projects (29 of which are new) and eight monitoring projects (Figure 1). Recognising the need for continual improvement, a component of the proposed 2017-18 work program will be dedicated to undertaking development, review and refinement of monitoring and research methods.
Figure 1. SSB 2017-18 research projects, by theme.
SSB thanked ARRTC for its feedback on the Supervising Scientist Branch Report. The SSB has provided responses to the feedback.
3.3 Specific presentations
3.3.1 Over-arching
Rehabilitation ecological risk assessment update (Renee Bartolo, SSB)
Associated paper: 3.3.1 Project scope, methods and timelines for Cumulative Ecological Risk Assessment (CERA) for the rehabilitation and closure of Ranger uranium mine (Bayliss, 2017)
Associated presentation: 3.3.1 Rehabilitation ecological risk assessment – project update
At its 37th meeting (November 2016) ARRTC requested SSB:
- Screen the moderate andlow risks identified in the Ecological Risk Assessment, and identify (i) where those moderate andlow risks are covered by the KKNs (based on the critical and high risks) and (ii) reference relevant existing KKNs; and
- Present on the method to be used for the cumulative ecological risk assessment (CERA).
Screening
From the 69 moderate and low risks identified in the Ecological Risk Assessment, a total of 12 risks overall (two in the decommissioning phase, 10 in the post-decommissioning phase) were identified as having no corresponding KKN. Themanagement of these 12 risks was discussed. The remaining 57 riskshave now been mapped against a corresponding KKN.
CERA method
This project is a collaboration between ERISS, CSIRO (Peter Bayliss) and consultant Dave Walden.
The scope of the first phase of the CERA is tomodel on-site risks associated with landform development/stabilisation and revegetation, and the interaction between the two (refer associated paper by Bayliss, 2017). The project aims are to: determine the most appropriate method for undertaking a CERA; to identify and catalogue datasets that will be used in the risk assessment; develop an agreed conceptual model and supporting narrative to undertake a risk assessment; undertake qualitative modelling on the conceptual models developed through the rehabilitation and closure ecological risk assessments to date; and complete a CERA for the on-site risks (landform, revegetation, and contaminants and sediments).SSB presented the conceptual model of on-sight risks, and the framework for the CERA (Figure 2). The second phase of the CERA (in 2018) will model off-site risks and in particular, in relation to surface water and groundwater interactions. The ‘whole of site’ surface water model, tentatively due for completion by ERA by the end of the year, is critical for the second phase.
With respect to timing for phase 1, a qualitative modelling workshop is scheduled for August 2017. Complete quantitative risk analysis, modelling and assessments is expected to be complete by November 2017, and the draft risk assessment report expected by December 2017.
Figure 2. Framework for the cumulative ecological risk assessment.
Based on AS/NZS ISO 31000:2009 risk management principles and guidelines,
ISO IEC 31010:2009 risk management risk assessment techniques, and the
US EPA Guidelines for Ecological Risk Assessment.
3.3.2 Waterand Sediment
Magela Creek sand bed water quality and ecology studies (Chris Humphrey, SSB)
Associated presentation: 3.3.2 Magela Creek sand bed water quality and ecology studies.
Project title: Assessing the ecological risks of mine water contaminants in the dry season, subsurface waters of Magela Creek sand channel. ARRTC 38 report, page 135-137.
Project publications to date: Chandler L, Tomlinson M & Humphrey C 2017. Water quality and biota in the subsurface sands of Magela Creek - report of a pilot study. Internal Report. Supervising Scientist Branch, Darwin. In review.
Dr Humphrey provided an update on the progress ofthis project,last presented atARRTC 36 (August 2016). The design of this current study, commencing in July 2017, is being informed by the 2016 pilot study which examined water quality (including current mine water contamination) and biota of subsurface saturated sands of Magela Creek. The results of the pilot study were presented, and are reported in Chandler et al 2017 (in review). The forward work plan includes monthly collection of biota and water chemistry samples, investigations into habitat variables (such as subsurface flow rates and hydraulic conductivity) and genomics and morphological analysis of biota samples.
ARRTC commended the techniques and approach taken by the project, supported the project’s forward work program in its current form, and endorsed the project.
3.3.3 Groundwater
Corridor Creek Land Application Area (CCLAA) to Gulungul Creek upper tributary groundwater plume delineation (Ben McTavish, ERA)
Associated presentation: 3.3.3 CCLAA to GulungulCreek upper tributary groundwater study.
Associated report:3.1 Report to the Alligator Rivers Region Technical Committee meeting # 38Environmental studies and closure, section 1.4, pages 9-11.
Associated report: Ranger Annual Groundwater Report 2015/16. Environmental Resources Management Australia Pty Limited, December 2016.
The aim of this investigation was to assess the potential causes of elevated EC spikes measured in surface water from Gulungul Creek upper tributary, and the potential relationship between irrigation activities at the CCLAA, where concentrations of sulfate and several other ions in groundwater exceed adopted background values.Potential interactions between groundwater and surface water between the south-western portion of the CCLAA and surrounding catchmentsare being assessed. The findings were presented to ARRTC, and are reported on in the Ranger Annual Groundwater Report 2015/16 (ERM, 2016). The assessment indicates that due to the cessation of irrigation in the southern portion of the CCLAA, hydraulic loading in this area has declined thus reducing the potential for migration of contaminants of potential concern from this area (ERM, 2016).
A conceptual hydrological model for the CCLAA and Gulungul Creek upper tributary area based on the source-pathway-receptor framework, is being developed. Mitigation measures were presented and include limiting irrigation rates in the south-west corner of the CCLAA and continued groundwater monitoring.
ACTION 38-2: ERA to present at ARRTC 41 (November 2018) an update on the CCLAA to Gulungul Creek upper tributary groundwater plume delineation.
ACTION 38-3: SSB to present at ARRTC 39 (November 2017) an update on Gulungul Creek water quality investigations.
Gulungul Creek tributary 2 interception system update (Ben McTavish, ERA)
Associated presentation: 3.3.3 GCT2 interception system update.
Associated paper:3.1 Report to the Alligator Rivers Region Technical Committee meeting # 38Environmental studies and closure, section 2.2.1, pages 22-24.
Associated report: Ranger Annual Groundwater Report 2015/16. Environmental Resources Management Australia Pty Limited, December 2016.
The GCT2 interception systemconsists of a seepage interception trench, a cut-off wall, seven shallow dewatering bores along the GCT2 alignment, and the periodic capture and pumping of GCT2 surface flow. The system was installed over 2014-15, and is designed to reduce further migration of impacted groundwater from the TSF into the GCT2alignment, remove impacted groundwater already present down gradient of the TSF west wall sump, and reduce discharge of impacted shallow groundwater into the GCT2 channel.
To date, the interception system has been very effective at drawing out salt, and hence reducing EC in associated monitoring bores, since dewatering commenced in January 2016.
ARRTC was interested to know about the chemical characteristics of the intercepted waters, as this would provide useful insights to form an understanding of the chemical composition of groundwater moving through and beyond the rehabilitated site and how representative they are considered to be of the post-closure groundwater.
ERA presented the review of system performance completed by ERM between January and October 2016. Nine megalitres of groundwater and 22 tons of salt were removed from the GCT2 channel. Next steps are to continue to monitor the systems performance, and review recommendations made by ERM to improve the operation and optimisation of the system.
ERA contend the GCT2 area hydrology is different to that expected post-closure, so believe the two are not readily comparable. As identified in the Ranger conceptual model, post-closure hydrology is expected to be less head-driven with longer solute transport timelines. Currently, the tailings dam embankments provide significantly greater storage of waste rock leachate, and this in turn, significantly increases driving head.