community consultative committee (ccc)data.centennialcoal.com.au/domino/centennialcoal/cc205... ·...

Glen Davis Road Capertee NSW 2846 Australia

T: 61 2 6359 2100 F: 61 2 6359 2132 E: [email protected] 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

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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:

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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:

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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

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Attachment 1 – Airly Mine Surface & Groundwater Overview

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


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


Surface water features


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


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)


Surface water monitoring network


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.


Groundwater features


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.


Existing groundwater users and monitoring bores


Existing groundwater users and monitoring bores

Airly Mine monitoring bores shown in light blue.

Not all monitoring bores and landholder bores shown.


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.


Groundwater monitoring

Groundwater

quality sampling

Continuous water pressure logging

with VWPs


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.


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.


Rainfall and streamflow data for Gap Creek


Rainfall and streamflow data for Genowlan Creek


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.



Surface water monitoring results – Airly Creek


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.



Hydrograph - ARP01

• VWP in current mining area.


Hydrograph – ARP04

• VWP in current mining area.



• Standpipe monitoring bore in Gap Creek alluvium. Cumulative rainfall

departure (CRD) shows rainfall trends.



• Standpipe monitoring bore in Gap Creek alluvium.



• Standpipe monitoring bore in Genowlan Creek alluvium.


Hydrograph – ARP15SP

• Standpipe monitoring bore in Narrabeen Sandstone.


Groundwater monitoring results – regional

groundwater

• Minimal variability in piezometric pressure in Shoalhaven and Devonian

strata underlying site boundary.

• No impacts from mining to date.



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.


Water balance model – existing water cycle


Water balance model – predictions for current

conditions


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.


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.


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.


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.


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