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Glen Davis Road Capertee NSW 2846 Australia
T: 61 2 6359 2100 F: 61 2 6359 2132 E: info@centennialcoal.com.au W: www.centennialcoal.com.au
Centennial Airly Pty Limited ABN 84 078 693 722
Community Consultative Committee (CCC)
Minutes of the Airly Mine CCC Water Workshop held at the
Administration Office on 23rd
October 2018 at 10:00am
Attendance: Gerard Martin - Chairperson
Sam Price – Environment & Community Coordinator, Airly Mine Lisa Menke – NSW National Parks & Wildlife Service Alex Mateer – Capertee Valley Landcare Group. Esme Martens – Community Representative James Marshall – GM Stakeholder Engagement, Centennial Coal
Lachlan Hammersley – Manager Water Engineering, Centennial Coal Stuart Gray – Technical Director – Hydrogeology, GHD
Invited Community Representatives and Local Landholders:
Neil Franklin
Baron Gray
Derek Larsen
Floyd Larsen
Lisanne Spackman
Wendy Williams
1. Meeting Open: The Chair opened the meeting at 10:02am
2. Apologies:
Dr Haydn Washington – Hon. Secretary, Colo Committee
Dennis Wallace – Mine Manager, Airly Mine
Page 2 of 6
Clr Wayne McAndrew – Lithgow City Council
David King – Technical Services Manager, Airly Mine
3. Declarations of Interest:
All members completed and signed declarations of pecuniary interest forms. - Esme Martens declared that she owns land within the Inglenook
Project area. - Gerard Martin declared that he is paid by Centennial Coal to fulfill the
role as the independent Chair of the Airly CCC.
4. Confirmation of Previous Minutes:
N/A – Water Workshop/Focus Session
5. Business Arising from the Previous Meeting:
At the previous meeting on 24th July 2018, members requested an interactive workshop to better understand Airly’s water management system and water monitoring program. - The request has been actioned by this CCC Water Workshop/Focus Session
held at Airly Mine on 23rd October 2018.
6. Correspondence:
Correspondence In:
N/A - Water Workshop/Focus Session
Correspondence Out:
N/A - Water Workshop/Focus Session
7. Company Reports and Overview of Activities:
Stuart Gray (Hydrogeological Expert – GHD) and Sam Price (Environmental Scientist – Airly Mine) provided a comprehensive overview of Airly Mine’s background surface and groundwater systems. The presentation also included an in depth explanation of Airly’s water management system and water monitoring network, including performance results to-date (see attachment 1).
Key Points Include:
Page 3 of 6
Overview of surface water features at Airly Mine and the surface monitoring program;
Overview of the groundwater features at Airly Mine and the groundwater monitoring program;
Summary of monitoring results to date and demonstrated that there has been no exceedances of the predictions made within the EIS;
Overview of the water balance and groundwater model; Nil water discharge and full compliance with water monitoring to-date for
2018; Site tour of Airly Mine’s pit top infrastructure area and water management
areas, Airly Creek Riparian Project Area, and groundwater monitoring bore ARP11 located in Airly Gap.
8. General Business:
The workshop was held in an interactive casual setting with questions and responses
taking place throughout the presentation. There was general discussion about Airly
Mines influence on ground water throughout the presentation. Key concerns include
(but not limited to):
Concerns around fracturing and connectivity between upper and lower
aquifer.
Airly will provide additional clarification on fracture zones and the
potential interaction between Airly operations on the upper and lower
aquifer.
Flow monitoring of Airly Creek downstream of operations.
Airly Creek is well outside the zone of influence of the Airly mine
workings, as such, flow monitoring on Airly Creek is not required.
Airly monitors flow in Village Spring, Gap and Genowlan Creeks as
well as discharge volume from all Licenced Discharge Points onsite.
Airly monitors water quality in Airly Creek in comparison to a
background representative site that’s not influenced by Airly
operations.
Flow monitors have not been installed to date on Airly Creek because
they are unnecessary and the actual installation of a 15-20m concrete
weir will cause adverse environmental impacts on the Airly Creek
Riparian Zone.
EC levels in Airly Creek were a concern.
Airly provided an explanation in relation to the elevated background
salt of the upper Airly Creek catchment as a result of the outcropping
Shoalhaven Marine Sediments. The elevated EC readings in Airly
Creek are a result of natural outcropped background geology and not
from Airly Mine operations.
The following actions arose from the meeting:
Page 4 of 6
1. Liaise with Capertee Valley community (via Mr Derek Larsen) to identify and
establish downstream groundwater monitoring to assist understand
interaction of Airly Mine with ground water resource (lower aquifer).
2. To provide further clarification relating to the potential interaction of the Airly
mine workings with Lower Devonian Strata (including influence of fracture
zones).
9. Date of Next Meeting:
Date of the CCC Workshop and topic will be decided by the CCC Members during the
next CCC meeting.
With there being no further business the meeting closed at 2:05pm.
Attachments:
1. Airly Mine Surface & Groundwater Overview
Page 5 of 6
Attachment 1 – Airly Mine Surface & Groundwater Overview
Page 6 of 6
Airly Mine Surface water and groundwater
overview Dr Stuart Gray | Technical Director - Hydrogeology
Airly Mine Surface and groundwater overview
Presentation overview
• Overview of surface water features at Airly Mine and the surface water
monitoring program
• Overview of groundwater features at Airly Mine and the groundwater
monitoring program
• Summary of monitoring results to date and comparison to EIS predictions
• Overview of the water balance model and groundwater model
Airly Mine Surface and groundwater overview
Monitoring and compliance framework
Baseline monitoring and modelling
EIS predictions
Operational phase monitoring
Compare results to EIS predictions
If non-compliance, conduct investigation and mitigate if required
Airly Mine Surface and groundwater overview
Surface water features
Airly Mine Surface and groundwater overview
Surface water impacts – EIS predictions
• Maximum predicted mine water discharge to Airly Creek is 76 ML/year,
although discharges will be minimised through management controls. Low
risk of changing water quality in Airly Creek.
• Maximum predicted flow reduction in watercourses above mining area up to
3% due to baseflow reduction.
• Negligible change to geomorphology based on subsidence predictions.
• No observable change to surface water quality above mining area due to
mining
Airly Mine Surface and groundwater overview
Surface water monitoring program
Surface water monitoring is undertaken in accordance with the Airly Mine
Water Management Plan (WMP), updated July 2018.
The surface water monitoring program consists of:
• Continuous flow gauging on Gap Creek and Genowlan Creek.
• Monthly water quality sampling (when water is present) at Airly Creek, Gap
Creek, Genowlan Creek and The Grotto.
• Monthly water quality sampling of storages at the Surface Facilities Area.
• Water quality sampling at LDP001, LDP002 and LDP003 on discharge and
gauging at LDP001. Note there has been no discharges from LDP001 since
April 2012 and no discharges from LDP002. LDP003 discharges are
infrequent (5 since 2013)
Airly Mine Surface and groundwater overview
Surface water monitoring network
Airly Mine Surface and groundwater overview
Stream health monitoring program
Stream health monitoring is undertaken in accordance with the WMP.
The stream health monitoring program consists of:
• Watercourse stability monitoring every two years.
• Biannual aquatic ecology monitoring on Airly Creek, Torbane Creek, Dog
Trap Creek, Gap Creek and Genowlan Creek.
Airly Mine Surface and groundwater overview
Groundwater features
Airly Mine Surface and groundwater overview
Groundwater impacts – EIS predictions
• Peak groundwater inflow into mine workings of 184 ML/year.
• Drawdown in alluvium and Permian strata predicted using the groundwater
model.
• No groundwater drawdown beyond the approved development consent
boundary
• Groundwater level recovery up to 60 years.
• No observable change to groundwater quality or beneficial use of
groundwater.
Airly Mine Surface and groundwater overview
Existing groundwater users and monitoring bores
Airly Mine Surface and groundwater overview
Existing groundwater users and monitoring bores
Airly Mine monitoring bores shown in light blue.
Not all monitoring bores and landholder bores shown.
Airly Mine Surface and groundwater overview
Groundwater monitoring program
Groundwater monitoring is undertaken in accordance with the WMP.
The groundwater monitoring network consists of:
• 10 standpipe groundwater monitoring bores.
• 27 vibrating wire piezometers (VWPs) at 9 locations.
• Monitoring of seepage from old shale workings at Village Spring.
• Sampling of groundwater quality at Airly Mine’s production bore and Nioka
bore (private landholder bore).
• Annual stygofauna sampling at 5 standpipes.
Airly Mine Surface and groundwater overview
Groundwater monitoring
Groundwater
quality sampling
Continuous water pressure logging
with VWPs
Airly Mine Surface and groundwater overview
Groundwater monitoring frequency
• Groundwater levels and pressures are recorded continuously at standpipes
(every 1 to 6 hours) and VWPs (every 12 hours) and downloaded monthly.
• Flow gauge continuously records flow at Village Spring.
• Monthly groundwater quality sampling at standpipes, Village Spring and Airly
Mine’s production bore.
• Quarterly groundwater quality sampling at Nioka.
Airly Mine Surface and groundwater overview
Surface water monitoring results – Gap and
Genowlan Creek
• Flow occurs in Genowlan and Gap Creek following significant rainfall events.
• Minimal flows recorded at flow gauges at Genowlan and Gap Creek during
2017 and 2018 attributable to below average rainfall.
• Water quality is fresh and slightly acidic. No change in water quality over
time.
• Aquatic ecology sites on Gap and Genowlan Creeks have been found to be
in better condition than other sites.
• All results to date consistent with EIS predictions.
Airly Mine Surface and groundwater overview
Rainfall and streamflow data for Gap Creek
Airly Mine Surface and groundwater overview
Rainfall and streamflow data for Genowlan Creek
Airly Mine Surface and groundwater overview
Surface water monitoring results – Airly Creek
• Water quality at monitoring sites in Airly Creek is brackish and generally
slightly alkaline.
• Water quality in Airly Creek is related to the natural geology of the
catchment. Surface water in Airly Creek is magnesium/calcium sulfate type
water and the same water type as the underlying Shoalhaven Group aquifer.
• All results to date consistent with EIS predictions.
Airly Mine Surface and groundwater overview
Surface water monitoring results – Airly Creek
Airly Mine Surface and groundwater overview
Groundwater monitoring results – local
groundwater
• Piezometric pressure is generally low/negative with minimal variability. Due
to the natural groundwater seepage along the slopes of Mount Airly and
Genowlan Mountain.
• Observable impacts of mining limited to Lithgow Seam and Marrangaroo
Formation at ARP04. Otherwise, groundwater levels are mainly influenced
by rainfall conditions.
• Groundwater inflow into the underground workings has been negligible to
date.
• No stygofauna detected to date.
• All results to date consistent with EIS predictions.
Airly Mine Surface and groundwater overview
Hydrograph - ARP01
• VWP in current mining area.
Airly Mine Surface and groundwater overview
Hydrograph – ARP04
• VWP in current mining area.
Airly Mine Surface and groundwater overview
Hydrograph – ARP05
• Standpipe monitoring bore in Gap Creek alluvium. Cumulative rainfall
departure (CRD) shows rainfall trends.
Airly Mine Surface and groundwater overview
Hydrograph – ARP11
• Standpipe monitoring bore in Gap Creek alluvium.
Airly Mine Surface and groundwater overview
Hydrograph – ARP09
• Standpipe monitoring bore in Genowlan Creek alluvium.
Airly Mine Surface and groundwater overview
Hydrograph – ARP12
• Standpipe monitoring bore in Genowlan Creek alluvium.
Airly Mine Surface and groundwater overview
Hydrograph – ARP15SP
• Standpipe monitoring bore in Narrabeen Sandstone.
Airly Mine Surface and groundwater overview
Groundwater monitoring results – regional
groundwater
• Minimal variability in piezometric pressure in Shoalhaven and Devonian
strata underlying site boundary.
• No impacts from mining to date.
• All results to date consistent with EIS predictions.
Airly Mine Surface and groundwater overview
Hydrograph – ARP13
Airly Mine Surface and groundwater overview
Hydrograph – ARP15
Airly Mine Surface and groundwater overview
Water balance
• Water balance model was developed for the Airly Mine Extension Project to
account for all water transfers to, from and within the surface facilities site.
• Computer software is used to predict future water demands and discharges
based on a range of possible future rainfall scenarios.
• Updated annually.
Airly Mine Surface and groundwater overview
Water balance model – existing water cycle
Airly Mine Surface and groundwater overview
Water balance model – predictions for current
conditions
Airly Mine Surface and groundwater overview
Groundwater modelling
• A three dimensional numerical hydrogeological model was developed for the
Airly Mine Extension Project.
• The model has since been updated and recalibrated using additional
monitoring data collected since 2014.
• The model has been utilised to predict potential impacts due to mining.
• Independent third party reviews of the model undertaken in 2014 and 2018
and found the model to be fit for purpose.
Airly Mine Surface and groundwater overview
Reporting
• Surface water and groundwater monitoring results are compared to trigger
values in the WMP and EIS predictions and reported annually.
• Water balance model updated and reported annually.
• The hydrogeological model may be recalibrated if monitoring data indicates
impacts that are different to those predicted by the modelling.
Airly Mine Surface and groundwater overview
Summary – surface water
• Surface watercourses at Airly Mine are ephemeral with flow observed
following significant rainfall events.
• Comprehensive surface water monitoring program including flow, water
quality, watercourse stability and aquatic ecology.
• All observations to date are consistent with EIS predictions.
• Site water balance predicts minimal discharges to Airly Creek. Discharges
are avoided through management controls such as maintaining sufficient
freeboard in dams.
• External water supplies are being considered since groundwater inflows into
the mine are less than expected.
Airly Mine Surface and groundwater overview
Summary – groundwater
• Minimal connection between local groundwater sources above the mine
workings and regional groundwater sources that supply landholders.
• Comprehensive groundwater monitoring program throughout the local and
regional groundwater sources.
• Observations to date are consistent with EIS predictions.
• Based on the peer reviewed groundwater model, no groundwater drawdown
is predicted beyond the site boundary and no impacts to landholder bores
are predicted.
Airly Mine Surface and groundwater overview
www.ghd.com
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