attachment i: spring gully development epbc referral eurombah … · 2020-08-02 · 2. roads,...

Spring Gully North-West and North-East Project – Referral Documentation REPORT

Attachment I: Spring Gully Development EPBC Referral Eurombah Creek Surface Water Impact Assessment – Spring Gully North-West and North East (KCB, 2017).

Re-evaluation of the CSG water management strategy has been recently undertaken to remove the reliance on the contingency release of treated CSG water to Eurombah Creek. As a result, the assessment of potential impacts to Eurombah Creek associated with the release of treated CSG water is no longer applicable.

Refer to the Spring Gully North-West and North-East Project – Preliminary Documentation for further details on the current proposed CSG water management strategy.

170207_WTF-SW-IA_final.docx

D09620A62

Klohn Crippen Berger LTD. • Level 5, 43 Peel St • South Brisbane QLD 4101 • Australia

+617.3004.0244 t • +617.3004.0299 f • www.klohn.com

February 7, 2017

Australia Pacific LNG

Level 3NT, 339 Coronation Drive

Milton

QLD, 4064

Annemarie Skelly

Environmental Advisor

Dear Ms. Skelly:

Spring Gully Development EPBC Referral

Eurombah Creek Surface Water Impact Assessment – Spring Gully North-West and North East

Klohn Crippen Berger Ltd. is pleased to provide Australia Pacific Liquefied Natural Gas (APLNG)

with this draft Eurombah Creek surface water impact assessment report for the Spring Gully

Development EPBC Referral for the Spring Gully North-West and North-East development areas.

Should you have any queries regarding this assessment, please do not hesitate to contact the

undersigned on +61 7 3004 0244 or [email protected].

Yours truly,

KLOHN CRIPPEN BERGER LTD.

Chris Strachotta, RPGeo

Senior Hydrogeologist

CS:KB:WD

Origin Energy Resources Ltd

NEDA and NWDA EPBC Referral

Eurombah Creek Surface Water Impact

Assessment

TABLE OF CONTENTS


Page ii

D09620A62 February 2017

1 INTRODUCTION .............................................................................................................. 1

1.1 The Project ...................................................................................................... 1

1.2 Regulatory Framework .................................................................................... 3

1.2.1 Significant impact guidelines 1.3: Coal seam gas and large coal mining

developments ................................................................................... 3

1.2.2 State Regulations .............................................................................. 5

1.2.3 Independent Expert Scientific Committee – Information Guidelines .. 7

1.3 Background Data ............................................................................................. 8

1.3.1 Authorised Activities ....................................................................... 13

2 PHYSICAL SETTING ....................................................................................................... 14

2.1 Regional Climate ............................................................................................ 14

2.2 Hydrology ...................................................................................................... 14

2.2.1 Regional Catchment ........................................................................ 14

2.2.2 Localised Drainage Network ............................................................ 17

2.2.3 Localised Drainage Water Quality .................................................... 18

2.2.4 State Approved Spring Gully WTF Releases...................................... 20

2.2.5 Eurombah Creek Third Party Users .................................................. 21

2.2.6 Watercourse Springs ....................................................................... 21

2.2.7 Eurombah Creek Downstream Aquatic Ecosystem .......................... 22

3 CSG WATER PRODUCTION AND WATER MANAGEMENT .............................................. 23

3.1 CSG Water Production ................................................................................... 23

3.2 Water Management Strategy......................................................................... 23

4 ANALYTICAL ASSESSMENT ............................................................................................ 25

4.1 Eurombah Creek Catchment Runoff Assessment ........................................... 25

4.1.1 Australian Water Balance Model – Eurombah Creek ....................... 26

4.1.2 AWBM Scenarios ............................................................................. 28

4.1.3 Model Results and Interpretation .................................................... 29

4.1.4 Model Assumptions and Limitations ................................................ 31

4.2 HEC-RAS Hydraulic Modelling ........................................................................ 32

4.2.1 Model Setup .................................................................................... 32



4.3 Catchment Water Balance / Water Quality Model ......................................... 35

4.3.1 Model Set-up .................................................................................. 35



5 IMPACT ASSESSMENT ................................................................................................... 43

5.1 Potential Project Impacts – Significant impact guidelines 1.3 ......................... 43




Assessment

TABLE OF CONTENTS (continued)


Page iii


5.1.1 Changes to Hydrological Characteristics .......................................... 43

5.1.2 Changes to Water Quality ................................................................ 46

5.2 Cumulative Impacts ....................................................................................... 50

5.2.1 Predicted Cumulative Flow and Levels – Eurombah Creek ............... 51

5.2.2 Predicted Cumulative Water Quality – Eurombah Creek .................. 51

6 CLOSING ....................................................................................................................... 53

REFERENCES ............................................................................................................................ 54

List of Tables

Table 1-1 Applicable Water Quality Objectives for the Project (derived from the Spring Gully

CWMP (APLNG, 2017)) ...................................................................................... 6

Table 1-2: IESC Specific Information Checklist ........................................................................... 9

Table 2-1: Monthly Climate Statistics for Roma Airport and Injune Post Office (BoM, 2016) ... 14

Table 2-2 Mean Surface Water Quality Concentrations ........................................................... 20

Table 2-3 Approved Spring Gully WTF Total Monthly Releases (ML) ....................................... 20

Table 2-4 Spring Gully WTF Release Water Quality Summary .................................................. 21

Table 4-1 AWBM Input Parameters ......................................................................................... 27

Table 4-2 Changes to Water Levels at Selected Locations ....................................................... 33

Table 4-3 Adopted Eurombah Creek Water Quality Concentrations ........................................ 35

Table 4-4 Water Quality Monitoring Locations Applicable to the Water Quality Model .......... 36

Table 4-5 Predicted Eurombah Creek Water Quality at Point 2,5 and 20 for the Various Climate

and WTF Scenarios and Applicable WQOs ....................................................... 37

Table 4-6: Summary of Comparison of Applicable Water Quality Parameters ......................... 41

Table 5-1 Summary of Potential Impacts Against Significant Impact Guidelines 1.3 (DoEE,

2013a) for Changes to Hydrological Characteristics ......................................... 44

Table 5-2 Summary of Potential Impacts Against Significant Impact Guidelines 1.3 (DoEE,

2013a) for Changes to Water Quality ............................................................... 48

List of Figures

Figure 1: Location Plan .............................................................................................................. 2

Figure 2: Eurombah Creek Catchment and Associated Sub-catchments .................................. 15

Figure 3: Geology underlying Eurombah Creek ....................................................................... 16

Figure 4: Eurombah Creek at Brookfield (#130376A) Flow Monitoring Records ...................... 17

Figure 5: Spring Gully WTF Release Location ........................................................................... 18

Figure 6: Eurombah Creek Surface Water Monitoring Points .................................................. 19

Figure 7 Watercourse Spring W59 Location ............................................................................ 22

Figure 8: Total Projected Water Extraction for the Project ...................................................... 23

Figure 9: Median (1898) and 1 in 20 Year, Wet Year (1917), Monthly Rainfall Distribution ..... 25




Assessment

TABLE OF CONTENTS (continued)


Page iv


Figure 10: Average Daily Flows – Recorded vs Modelled Flows ............................................... 27

Figure 11: Cumulative Flows - Recorded vs Modelled Flows.................................................... 28

Figure 12: WTF Weekly Releases for the Base Case, Project and Cumulative Scenarios ........... 29

Figure 13: Eurombah Creek Catchment Sub-catchment Inflow Locations ................................ 31

List of Appendices

Appendix I AWBM Predicted Sub-catchment Inflows

Appendix II HEC-RAS Predicted Model Results

Appendix III GoldSim Water Quality Model Results



Eurombah Creek Surface Water Impact Assessment


Page 1


1 INTRODUCTION

Klohn Crippen Berger Ltd (KCB) has been commissioned by Origin Energy Resources Limited

(OERL) to undertake a hydrological assessment for the proposed release of treated coal seam gas

(CSG) water from the Spring Gully Water Treatment Facility (WTF) into the Eurombah Creek

catchment. The treated water is produced as a result of treatment of CSG water from the

development of Petroleum Leases (PL) 414, 415, 416 and part of 418 known as the North-West

Development Area (NWDA); and, PL417 known as the North-East Development Area (NEDA). The

location of the NWDA and the NEDA, collectively known as the Project, is presented in Figure 1.

Approximately 10,250 ML of CSG water will be produced as a result of the Project and will be

managed in accordance with the existing Spring Gully Coal Seam Gas Water Management Plan

(APLNG, 2017). CSG water produced from the Project will be beneficially used (Project activities,

irrigation or aquifer injection) or released to the Eurombah Creek catchment following treatment.

The release of treated CSG water is required when the inherent variability of irrigation demand

means that a proportion of treated CSG water cannot be beneficially used. An annual average

release rate of 280 ML/year is proposed to be released from the Spring Gully WTF into Eastern

Gully, a tributary to Eurombah Creek, as a result of the Project.

The objective of this assessment is to assess the potential impact on surface water resources as a

result of the release of treated CSG water to the Eurombah Creek catchment (herein referred to

as the Study Area). An assessment of potential impacts to threatened ecological communities and

threatened species listed under the Environment Protection and Biodiversity Conservation Act

1999 (EPBC Act) as a result of the release of treated CSG water has been completed by Natural

Resource Assessments Pty Ltd (NRA). The assessment is conducted with reference to the

Department of the Environment and Energy (DoEE) Significant Impact Criteria provided in

‘Significant impact guidelines 1.3: Coal seam gas and large coal mining developments – impacts on

water resources’ (DoEE, 2013a).

The following terms are used in this report:

� Spring Gully NWDA and NEDA – The Project;

� Spring Gully NWDA – approximately 16,289 ha comprising PL 414, 415, 416 and the

northern portion of PL418;

� Spring Gully NEDA – approximately 23,135 ha encompassing PL417;

� Study area – Eurombah Creek catchment covering 3,050 km2, approximately 997 km2

upstream and 2,053 km2 downstream of release point; and,

� Approved Spring Gully Development area – the existing Spring Gully development located

on PLs 195, 200, 203, 204 and 268 (currently in application to replace PL203).

1.1 The Project

The Project will involve the progressive development of CSG infrastructure on Spring Gully NWDA

and NEDA (refer to Figure 1), and will include the following activities:





Page 2


Figure 1: Location Plan

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PL 195

PL 200

PL 200

PL 203

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PL 268

PL 417

PL 419

PL 418

PL 414

PL 415

PL 416

700,000 750,0007

,05

0,0

00

7,1

00

,00

07

,15

0,0

00

0 5 10 15 20 25

km

NOTES:1. Lease locations sourced from DNRM, 2015

2. Roads, Rivers, Towns, Railway: Geodata Topo 250K Series 3 Geoscience Australia

May 2009.

Town

Principal Road

Minor Road

River / Creek

North-West DevelopmentArea

North-East Development

Area

Approved Spring Gully

Development Area

Spring Gully DevelopmentArea

Petroleum Leases (DNRM)

PROJECTION1. Horizontal Datum: GDA942. Grid Zone: 553. Vertical Datum: Mean Sea Level4. Scale: 1:750,000

Spring Gully North-West

Development Area

Spring Gully North-East

Development Area





Page 3


� Drilling, installation, operation and maintenance of up to 114 production wells (mix of

vertical and horizontal wells depending upon the optimum method for CSG extraction),

targeting the Bandanna Formation of the southern Bowen Basin, over the estimated

30 year life of the development;

� Installation, operation and maintenance of gas and water gathering flowlines;

� Installation, operation and maintenance of associated supporting infrastructure

(e.g. temporary workforce accommodation, access roads, power and communication

systems, laydowns, stockpiles and storage areas); and,

� Decommissioning and rehabilitation of infrastructure and disturbed areas.

Locations of infrastructure may be refined as the detailed design process of the development

progresses.

The Project will not require development of gas compression facilities or water management and

treatment infrastructure. Gas and water from the Project will be directed to existing infrastructure

located within the Approved Spring Gully Development area. The use of existing gas processing

and water treatment facilities will minimise land disturbance and associated environmental

impacts within the Project area.

Subject to EPBC approval, production within the Spring Gully NWDA is planned to commence in

November 2017, on PL414, PL415 and PL416 and February 2018, for the proposed wells within

PL418. In the Spring Gully NEDA further production is planned to commence in November 2017

for two wells, with the remaining wells scheduled to commence operation in January 2019, which

will augment the already existing network across PL417.

1.2 Regulatory Framework

1.2.1 Significant impact guidelines 1.3: Coal seam gas and large coal mining developments

The Significant impact guidelines 1.3: Coal seam gas and large coal mining developments –

impacts on water resources (DoEE, 2013a) identify a ‘significant impact’ as an “impact which is

important, notable, or of consequence, having regard to its context or intensity”.

For a water resource a ‘significant impact’ may occur where, as a result of the action, one of the

following changes to the hydrological characteristics of a water resource are of a sufficient scale

or intensity to significantly reduce the current or future utility of the water resource for third

party users, including environmental and other public benefit outcomes:

a) changes in the water quality, including the timing of variations in water quality;

b) changes in the integrity of hydrological or hydrogeological connections, including

substantial structural damage (e.g. large scale subsidence); and,

c) changes in the area or extent of a water resource.

DoEE have identified the following aspects that may need to be considered when assessing the

above hydrological characteristics:





Page 4


� flow regimes (volume, timing, duration and frequency of surface water flows);

� recharge rates to groundwater;

� aquifer pressure or pressure relationships between aquifers;

� groundwater table and potentiometric surface levels;

� groundwater-surface water interactions;

� river-floodplain connectivity;

� inter-aquifer connectivity; and,

� coastal processes including changes to sediment movement or accretion, water circulation

patterns, permanent alterations in tidal patterns, or substantial changes to water flows or

water quality in estuaries.

The Significant impact guidelines 1.3, section 5.4, provide guidance on changes to water quality

which state that a significant impact on a water resource may occur where, as a result of the

action:

a) there is a risk that the ability to achieve relevant local or regional water quality objectives

would be materially compromised, and as a result the action:

� creates risks to human or animal health or to the condition of the natural environment

as a result of the change in water quality;

� substantially reduces the amount of water available for human consumptive uses or

for other uses, including environmental uses, which are dependent on water of the

appropriate quality;

� causes persistent organic chemicals, heavy metals, salt or other potentially harmful

substances to accumulate in the environment;

� seriously affects the habitat or lifecycle of a native species dependent on a water

resource; or,

� causes the establishment of an invasive species (or the spread of an existing invasive

species) that is harmful to the ecosystem function of the water resource;

b) there is a significant worsening of local water quality (where current local water quality is

superior to local or regional water quality objectives); or,

c) high quality water is released into an ecosystem which is adapted to a lower quality of

water.

Both changes to the hydrological characteristics and water quality as a result of the proposed

activities have been assessed as part of this assessment for the identification of potential impacts.





Page 5


1.2.2 State Regulations

1.2.2.1 Water Plan (Fitzroy Basin) 2011

The surface water resource of the Eurombah Creek catchment is managed under the Queensland

Water Resource Plan framework as part of the Water Plan (Fitzroy Basin) 2011 (DNRM, 2016). The

purpose of the plan is to:

1. define the availability of water in the plan area;

2. provide a framework for sustainably managing water and the taking of water;

3. identify priorities and mechanisms for dealing with future water requirements;

4. provide a framework for establishing water allocations;

5. provide a framework fort reversing, where practicable, degradation in natural ecosystems;

6. regulate the taking of overland flow water; and,

7. regulate the taking of groundwater.

Eurombah Creek occurs within the Upper Dawson sub-catchment of the Fitzroy Basin.

1.2.2.2 Fitzroy Basin Resource Operations Plan

The Fitzroy Basin Resource Operations Plan (ROP) (DNRM, 2015) provides the process to

implement the Water Plan (Fitzroy Basin) 2011 (DNRM, 2016). The key function of the ROP is to

provide the operating and environmental management rules and monitoring requirements to

resource operations licence holders.

Under the Fitzroy Basin ROP (DNRM, 2015), Eurombah Creek occurs within the Dawson Valley

Water Management Area. Within this management area Eurombah Creek is a tributary of the

Dawson O Zone, along the AMTD reach 428.0-453.5 (km); and, is described as “Eurombah Creek

Junction to Utopia Downs Gauging Station”. There are no resource operations licence holders in

the Dawson O Zone of the Dawson Valley Water Management Area.

1.2.2.3 Environmental Protection (Water) Policy 2009 – Dawson River Sub-basin

Environmental Values and Water Quality Objectives

The Environmental Protection (Water) Policy 2009 (EPP (Water)) is subordinate legislation under

the Environmental Protection Act 1994 and, of relevance to this investigation, provides a

framework for identifying environmental values (EVs) for Queensland waters, and deciding the

water quality objectives (WQOs) to protect or enhance those EVs. For the Project the Dawson

River Sub-Basin Environmental Values and Water Quality Objectives Basin No. 130 (part), including

all waters of the Dawson River Sub-basin except the Callide Creek Catchment September 2011

(Department of Environment and Heritage Protection (EHP), 2011) provides the applicable EVs

and WQOs.

Applicable EVs for the Study area, for waters of the Upper Dawson Southern Tributaries (which

includes Eurombah Creek), are as follows:





Page 6


� protection of aquatic ecosystems;

� suitability for farm supply / use;

� suitability for stock watering;

� suitability for primary contact recreation;

� suitability for secondary contact recreation;

� suitability for visual (no contact) recreation;

� suitability for drinking water supplies;

� suitability for industrial use; and,

� protection of cultural and spiritual values, including Traditional Owner values of water.

Australia Pacific LNG evaluated land use and EVs for the Eurombah Creek catchment for the EA

amendment application (December 2016), determining that there was no drinking water service

provider and irrigated cropping in the catchment and that the drinking water and irrigated

cropping EVs were not deemed applicable for the EA amendment application (APLNG 2016a,

2016b, Queensland Government approved Exclusion Decision (SRN00020) under the Water Supply

(Safety and Reliability) Act 2008 (Qld))). For consistency, drinking water and irrigated cropping

have not been considered further for this assessment. The closest drinking water service provider

to the release point lies on the Dawson River at Gyranda Weir, more than 200 km downstream of

the release point (APLNG 2017).

To protect each of the EVs listed above, DEHP (2011) has specified sub-regional water quality

guideline values or cited separate guideline documents that should be used to derive WQOs for

effective management. In the case of the aquatic ecosystem EV, these WQOs vary depending on

the condition (and associated management intent) of the waters in question. Waters of the

Project are considered to be ‘moderately disturbed’ and therefore the management intent (as

defined by EPP (Water)) is to ensure the biological integrity of an aquatic ecosystem that is

adversely affected by human activity to a relatively small but measurable degree.

In order to maintain the protection of the above EVs, which have the potential to be affected by

CSG water management, WQOs have been identified for the surface water of Eurombah Creek

downstream of the treated CSG water release point as part of the Spring Gully Coal Seam Gas

Water Management Plan (Spring Gully CWMP) (APLNG, 2017). These WQOs are considered to be

applicable to the Project and are provided in Table 1-1.

Table 1-1 Applicable Water Quality Objectives for the Project (derived from the Spring Gully

CWMP (APLNG, 2017))

Parameter Unit WQO

Physical and Chemical

Temperature oC 30

pH pH unit 6.5-8.5

Electrical conductivity (baseflow) µS/cm 370

Electrical conductivity (high flow) µS/cm 210

Dissolved oxygen % sat. 85-110

Turbidity NTU 50

Chlorophyll a µg/L 5





Page 7


Parameter Unit WQO

Total suspended solids mg/L 30

Nutrients

Total nitrogen µg/L 620

Ammonia (as N) µg/L 20

Nitrate (as N) µg/L 700

Filterable reactive phosphorus µg/L 20

Total phosphorus µg/L 70

Major Cations and Anions

*Calcium (minimum) mg/L 5

Sulfate mg/L 5

Metals and Metalloids

Aluminium µg/L 55

Antimony (III) µg/L 9

Arsenic (III) µg/L 24

Arsenic (IV) µg/L 13

Beryllium µg/L 13

Boron µg/L 370

Cadmium µg/L 0.2

Chromium (III) µg/L 3.3

Chromium (IV) µg/L 1.0

Cobalt µg/L 1.4

Copper µg/L 1.4

Gallium µg/L 18

Iron µg/L 300

Lanthanum µg/L 0.04

Lead µg/L 3.4

Manganese µg/L 1,900

Mercury (inorganic) µg/L 0.06

Molybdenum µg/L 34

Nickel µg/L 11

Selenium (total) µg/L 5

Silver µg/L 0.05

Tin (inorganic, SnIV) µg/L 3

Uranium µg/L 0.5

Vanadium µg/L 6

Zinc µg/L 8

* Calcium WQO is a minimum WQO (i.e. concentrations are not to decrease below 5 mg/L)

1.2.3 Independent Expert Scientific Committee – Information Guidelines

The Independent Expert Scientific Committee on Coal Seam Gas and Large Coal Mining

Development (the IESC) is a statutory body under the EPBC Act. The IESC’s key functions are to:

� provide scientific advice to the Commonwealth Environment Minister and relevant state

ministers in relation to coal seam gas (CSG) or large coal mining development proposals

that are likely to have a significant impact on water resources;

� provide scientific advice to the Commonwealth Environment Minister on bioregional

assessments;

� provide scientific advice to the Commonwealth Environment Minister on research

priorities and projects;





Page 8


� collect, analyse, interpret and disseminate scientific information about the impacts of CSG

and large coal mining activities on water resources; and,

� provide scientific advice on other matters in response to a request from the

Commonwealth or state ministers.

To allow the IESC to provide robust scientific advice to government regulators on water-related

impacts of CSG, an information guideline has been development outlining the information

considered necessary for the IESC to undertake the relevant assessment. Table 1-2 provides the

information checklist identified in the IESC Information Guidelines, and the relevant sections of

this report that addresses each checklist item.

1.3 Background Data

Data for this hydrological assessment was provided to KCB by APLNG and NRA. The following

information / data was provided:

� Previous investigations and documents relevant to this surface water assessment,

including:

� Assessment of Discharging Reverse Osmosis Permeate to Eurombah Creek (ECCO,

2007)

� Australia Pacific LNG Project EIS, Volume 5: Attachments, Attachment 22: Surface

Water and Watercourses – Gas Fields (APLNG, 2010)

� Spring Gully Coal Seam Gas Water Management Plan (Q-8200-15-MP-0001) (APLNG,

2017)

� Scientific Information for Land Owners (SILO) synthetic daily climate data for the

Eurombah Creek catchment area for the period January 1, 1889 to December 4, 2016

sourced from the Science Delivery Division of the Department of Science, Information

Technology and Innovation (DSITI);

� Eurombah Creek stream gauging records (i.e. creek levels, flow rates) from the

Department of Natural Resources and Mines (DNRM) stream gauging station Eurombah

Creek at Brookfield (# 130376A);

� Surface water monitoring data (water quality, anecdotal water level information),

including Spring Gully WTF release water quality;

� Spring Gully WTF release rate monitoring records;

� Proposed Spring Gully WTF annual release profile; and,

� 1 m resolution LiDAR data across the Eurombah Creek catchment / Project area.

Some additional background data to complete this assessment was sourced from the Department

of Natural Resources and Mines (DNRM) QSpatial website and Queensland Globe, with specific

reference to these datasets provided within the figure notes.





Page 9


Table 1-2: IESC Specific Information Checklist

Component Checklist Item Section addressed in this

Report

Description of the proposal

A regional overview of the proposed project area including a description of the geological basin, coal resource, surface water

catchments, groundwater systems, water-dependent assets, and past, current and reasonably foreseeable coal mining and CSG

developments.

Section 1 and 2

A description of the statutory context, including information on the proposal’s status within the regulatory assessment process and on

any water management policies or regulations applicable to the proposal. Section 1.2 and 1.3

A description of the proposal’s location, purpose, scale, duration, disturbance area, and the means by which it is likely to have a

significant impact on water resources and water-dependent assets. Section 2 and 3

A description of how impacted water resources are currently being regulated under state or Commonwealth law, including whether

there are any applicable standard conditions. Section 1.2 and 1.3

Surface Water

Context and

conceptualisation

A description of the hydrological regime of all watercourses, standing waters and springs across the site including:

� Geomorphology, including drainage patterns, sediment regime and floodplain features.

� Spatial, temporal and seasonal trends in streamflow and/or standing water levels.

� Spatial, temporal and seasonal trends in water quality data (such as turbidity, acidity, salinity, relevant organic chemicals,

metals and metalloids and radionuclides).

Current stressors on watercourses, including impacts from any currently approved projects.

Section 2 and 3

A description of the existing flood regime, including flood volume, depth, duration, extent and velocity for a range of annual

exceedance probabilities, and flood hydrographs and maps identifying peak flood extent, depth and velocity. Section 2 and 4

Assessments of the frequency, volume and direction of interactions between water resources, including surface water/ groundwater

connectivity and connectivity with sea water. Section 2.2

Analytical and

numerical

modelling

Conceptual models at an appropriate scale, including water quality, stores, flows and use of water by ecosystems. Section 2.2

Methods in accordance with the most recent publication of Australian Rainfall and Runoff. Section 4.1

A programme for review and update of the models as more data and information becomes available.

Not applicable as a result of

conservatism adopted in

modelling input parameters and

results from established

monitoring program

Description and justification of model assumptions and limitations, and calibration with appropriate surface water monitoring data. Section 4

An assessment of the risks and uncertainty inherent in the data used in the modelling, particularly with respect to predicted scenarios. Section 4





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Report

A detailed description of any methods and evidence (e.g. expert opinion, analogue sites) employed in addition to modelling.


conservatism adopted in

modelling input parameters and

existing monitoring program

that has established current

conditions in Eurombah Creek

Impacts to water

resources and

water-dependent

assets

Description of all potential impacts of the proposed project on surface waters, including a clear description of the impact to the

resource, the resultant impact to any water-dependent assets dependent on the resource, and the consequence or significance of the

impact, including:

� Impacts on streamflow under different flow conditions.

� Impacts associated with surface water diversions.

� Impacts to water quality, including consideration of mixing zones.

� Estimates of the quality, quantity and ecotoxicological effects of operational discharges of water (including saline water),

including potential emergency discharges, and the likely impacts on water resources and water-dependent assets.

Identification and consideration of landscape modifications, for example, subsidence, voids, onsite earthworks including disturbance

of acid-forming or sodic soils, roadway and pipeline networks through effects on surface water flow, surface water quality, erosion

and habitat fragmentation of water-dependent species and communities.

Section 5

Existing water quality guidelines and targets, environmental flow objectives and requirements for the surface water catchment(s)

within which the development proposal is based. Section 1.2 and 1.3

Identified processes to determine surface water quality and quantity triggers which incorporate seasonal variation but provide early

indication of potential impacts to assets. Section 2.2

Proposed mitigation actions for each trigger and identified significant impact.


trigger / significant impact not

being identified

Description and adequacy of proposed measures to prevent/minimise impacts on water resources and water-dependent assets. Not applicable as a result of

impacts not being identified

Description of the cumulative impact of the proposal on surface water resources and water-dependent assets when all developments

(past, present and/or reasonably foreseeable) are considered in combination. Section 5.2

An assessment of the risks of flooding, including channel form and stability, water level, depth, extent, velocity, shear stress and

stream power, and impacts to ecosystems, project infrastructure and the final project landform. Section 5

Data and

monitoring

Monitoring sites representative of the diversity of potentially affected water-dependent assets and the nature and scale of potential

impacts, and matched with suitable replicated control and reference sites (BACI design) to enable detection and monitoring of

potential impacts.

Section 2.2

Water quality monitoring complying with relevant National Water Quality Management Strategy (NWQMS) guidelines and relevant

legislated state protocols. Section 2.2





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Report

Specified data sources, including streamflow data, proximity to rainfall stations, data record duration and a description of data

methods, including whether missing data has been patched. Section 2, 3 and 4

A surface water monitoring programme collecting sufficient data to detect and identify the cause of any changes from established

baseline conditions, and assessing the effectiveness of mitigation and management measures. Section 2

The rationale for selected monitoring variables, duration, frequency and methods, including the use of satellite or aerial imagery to

identify and monitor large-scale impacts.

Not applicable as a result of a

monitoring program already

being established as part of

Approved Spring Gully

Development

Ongoing ecotoxicological monitoring, including direct toxicity assessment of discharges to surface waters where appropriate. See Aquatic Ecology report

(NRA, 2017)

Identification of dedicated sites to monitor hydrology, water quality, and channel and floodplain geomorphology throughout the life

of the development proposal and beyond. Section 2.2

Cumulative Impacts

Context and

conceptualisation

Cumulative impact analysis with sufficient geographic and time boundaries to include all potentially significant water-related impacts. Section 5.2

Cumulative impact analysis identifies all past, present, and reasonably foreseeable actions, including development proposals,

programs and policies that are likely to impact on the water resources of concern. Section 2.2 and 3

Impacts

An assessment of the condition of affected water resources which includes:

� Identification of all water resources likely to be cumulatively impacted by the proposed development.

� A description of the current condition and quality of water resources and information on condition trends.

� Identification of ecological characteristics, processes, conditions, trends and values of water resources.

� Adequate water and salt balances.

� Identification of potential thresholds for each water resource and its likely response to change and capacity to withstand

adverse impacts (e.g. altered water quality, drawdown).

Section 4 and 5.2





Page 12



Report

An assessment of cumulative impacts to water resources which considers:

� The full extent of potential impacts from the proposed development, including alternatives, and encompassing all linkages,

including both direct and indirect links, operating upstream, downstream, vertically and laterally.

� An assessment of impacts considered at all stages of the development, including exploration, operations and post closure /

decommissioning.

� An assessment of impacts, utilising appropriately robust, repeatable and transparent methods.

� Identification of the likely spatial magnitude and timeframe over which impacts will occur, and significance of cumulative

impacts.

� Identification of opportunities to work with others to avoid, minimise or mitigate potential cumulative impacts.

Section 4 and 5.2

Mitigation,

monitoring and

management

Identification of modifications or alternatives to avoid, minimise or mitigate potential cumulative impacts


potential cumulative impacts

not being identified

Identification of measures to detect and monitor cumulative impacts, pre and post development, and assess the success of mitigation

strategies


potential cumulative impacts

not being identified

Identification of cumulative impact environmental objectives Section 1.2 and 1.3

Appropriate reporting mechanisms


reporting mechanism already

established under the Approved

Spring Gully Development

Proposed adaptive management measures and management responses


reporting mechanism already

established under the Approved

Spring Gully Development





Page 13


1.3.1 Authorised Activities

Full-scale CSG production within the Approved Spring Gully Development area commenced in

2005, with current CSG activities, authorised by the Spring Gully Environmental Authority (EA)

EPPG00885313 issued by the Queensland Department of Environmental Heritage and Protection

(EHP).

The EA authorises the release of treated CSG water to a maximum of 10.2 ML/day and an annual

average of 700 ML/year into Eastern Gully, a tributary of Eurombah Creek. APLNG propose to

incorporate the CSG water produced from the Project within the feed water for the water

treatment facilities at Spring Gully WTF. The release of 700 ML/year of treated water is already

authorised for the Spring Gully WTF. Therefore, the State approved Spring Gully WTF release rate

will not be exceeded as a result of NWDA and NEDA development. The 700 ML/year Spring Gully

release rate will be assessed as the cumulative impact scenario for this surface water assessment.





Page 14


2 PHYSICAL SETTING

2.1 Regional Climate

The climate of the Surat Basin is generally sub-tropical with warm, wet summers and cooler, drier

winters. Monthly climate statistics were sourced from the BoM (2016) for Roma Airport

(temperature) and Injune Post Office (rainfall) gauging stations (Table 2-1).

Average annual rainfall for the Injune Post Office station is ~635 mm, with most rainfall falling

between November and March.

Table 2-1: Monthly Climate Statistics for Roma Airport and Injune Post Office (BoM, 2016)

Month

Roma Airport Station (43091) Injune Post Office Station (43015)

Mean max temperature (°C)

(1992 to 2016)

Mean min temperature (°C)

(1992 to 2016)

Mean rainfall (mm)

(1925 to 2016)

Jan 34.2 20.8 89.1

Feb 32.6 20.0 88.0

Mar 31.4 17.3 62.1

Apr 28.0 12.4 41.2

May 23.8 7.7 32.8

Jun 20.3 5.3 30.0

Jul 20.2 3.7 28.9

Aug 22.6 4.8 25.4

Sep 26.6 9.3 25.9

Oct 29.8 13.6 47.4

Nov 32.0 17.4 73.4

Dec 33.2 19.3 90.9

Annual 27.9 12.6 635.3

2.2 Hydrology

2.2.1 Regional Catchment

Eurombah Creek is a tributary of the Dawson River, which is a sub-catchment of the greater

Fitzroy Basin. Eurombah Creek commences between Roma and Injune at an elevation of

~620 mAHD. The catchment generally drains in an east north-easterly direction before discharging

into the Dawson River ~85 km downstream of the Spring Gully WTF.

The Eurombah Creek catchment covers an area of approximately 3,050 km2 and comprises 20

sub-broad sub-catchments (Figure 2). Surface water flow in the catchment is ephemeral, with

flows typically occurring during the wetter summer months from November to March.

The bedrock geology underlying Eurombah Creek comprises the Injune Creek Group of

sedimentary units and the Hutton Sandstone (Figure 3). Approximately 25 km downstream of the

Spring Gully WTF release location Quaternary alluvium deposits, associated with Eurombah Creek

and the downstream Dawson River, have been mapped. This alluvium is consistent to the

confluence with the Dawson River.





Page 15


Figure 2: Eurombah Creek Catchment and Associated Sub-catchments

DAWSON R IVER

Spring Gully WTF

EUR

OM

B AH

CRE E K

S1

S2

S3

S4

S5

S6

S8

S7

S9

S10

S12 S13

S11

S14

S17

S16

S18

S15

S19

S20

0 1020

30

40

50 60

70

80

675,0 00 700,0 00 725,0 00 750,0 00

7,0

75

,00

07

,10

0,0

00

7,1

25

,00

07

,15

0,0

00

0 5 10 15 20 25

km

Spring Gully Water Treatment F acility

Chainage Markers (10 km intervals)

River

Creek

Eurombah Creek Catchment

Eurombah Creek Sub-catchment

NOTES:

1. Lea se l oca tion s source d from D NR M, 2016

2. R oads , R ive rs, Towns, QLD D EM: Geodata Topo 25 0K Serie s 3 Geoscie nc e A ustra lia

M ay 2 009.

3. D ig ita l Ele vatio n Mode l (D EM) sourced from

D N RM - QSpa tia l, 2015

PROJECTION

1. Ho rizonta l Datum: G DA 94

2. G rid Zone: 55

3. Vert ica l Datum: Mean Sea Leve l

4. Scale: 1:600,000





Page 16


Figure 3: Geology underlying Eurombah Creek

The Injune Creek Group comprises the Westbourne Formation, the Springbok Sandstone, Walloon

Coal Measures, Eurombah Formation and Durabilla Formation. Of these units the Springbok

Sandstone is considered to be a main aquifer (OGIA, 2017), however, the aquifer shows a high

degree of variability. The Hutton Sandstone is also considered to be a main aquifer (OGIA, 2017).

Recharge to these aquifers predominantly occurs via direct rainfall infiltration, however, leakage

DAWSON RIVER

YU

LE

BA

TAR

OO

M

R

OA

D

RO

MA

TAR

OO

MR

OA

D

TAROOMINJUNE ROAD

WA

LL

UM

BI L

LA

NO

RT

HR

OA

D

CA

RN

AR

VO

NH

IGH

WA

Y

C

ARNAR

VON

DE

VE

LO

PM

EN

TA

LR

OAD

JKb

KudKud

Kud Kud

Ky

JoQa

JKb

T

Ky

Ky

Ky

Ky

QaKy

JKb

JKb

JKb

TmbJKb Ky

Ky Ky

JKb

Ky

Jo

Jo

Ji

JKb

Ji

Ji

JiJh

JKb

Qa

Jg

Jg

Jg

Jg

Ji

Ji

Ji

Ji

T

JKbJKb

JKb

Jg

Jg

Jiw

Re

Je

Rm

Jp

Jh

Je

JhJhJh

JhJh

Rm

Jp

Qa

Qa

Qa

Qa

JeJh

Ji

Je

Spring Gully WTF

EUROMBA

H

CREEK

675,000 700,000 725,000 750,0007,0

75

,00

07

,10

0,0

00

7,1

25

,00

07,1

50

,00

0

0 5 10 15 20 25

km

Spring Gully Water

Treatment Facility

River

Creek

Principal Road

Minor Road

Eurombah Creek

Catchment

NOTES:

1. Lease locations sourced from DNRM, 2016

2. Roads, Rivers, Towns, QLD DEM: Geodata Topo 250K

Series 3 Geoscience Australia May 2009.

3. Geology Map Surat Basin Rock Unit Surface and Surat

Basin Structure, DEEPI December 2011.

PROJECTION1. Horizontal Datum: GDA94

2. Grid Zone: 553. Vertical Datum: Mean Sea Level

4. Scale: 1:600,000

GEOLOGY

Fault

Anticline

Syncline

QUATERNARY

Qa-NSB

TERTIARY

T-NSB

Tmb-NSB

CRETACEOUS

Doncaster Member, Kud

Bungil Formation, Ky

JURASSIC - CRETACEOUS

Mooga Sandstone, JKb

JURASSIC

Orallo Formation, Jo

Gubberamunda Sandstone, Jg

Westbourne Formation, Jiw

MIDDLE JURASSIC - LATE JURASSIC

Injune Creek Group, Ji

MIDDLE JURASSIC

Hutton Sandstone, Jh

EARLY JURASSIC

Evergreen Formation, Je

Precipice Sandstone, Jp

MIDDLE TRIASSIC

Moolayember Formation, Rm

TRIASSIC

Clematis Group, Re





Page 17


from streams (e.g. Eurombah Creek) may also occur. Hydraulic connection between Eurombah

Creek and the unconsolidated sediments of the alluvium deposits are also anticipated.

Stream gauging of Eurombah Creek is undertaken by DNRM at the stream gauging station

Eurombah Creek at Brookfield (# 130376A) located ~58 km downstream of the Spring Gully WTF

release location. The stream gauge was commissioned in November 2011 to record rainfall, water

level in the creek and the creek flow rate. Monitored stream flow records from the gauging

station are provided in Figure 4, indicating the ephemeral nature of the system.

Figure 4: Eurombah Creek at Brookfield (#130376A) Flow Monitoring Records

2.2.2 Localised Drainage Network

Eurombah Creek is an ephemeral stream that is subject to infrequent flows. During periods of “no

flow” the creek is divided up into a series of waterholes. The main flow channel is incised into the

surrounding terrain, with bank heights of ~10 m in places. The channel bed is sandy, with limited

vegetation and has bedrock outcrops at certain locations. Channel banks are also sandy and rocky,

with most being steep, supported by vegetation growth.

The Spring Gully WTF releases into Eastern Gully, which flows into Eurombah Creek. The WTF

release location is approximately 1.1 km upstream of the confluence with Eurombah Creek (Figure

5). The Eurombah Creek catchment is approximately 3,050 km2, of which 997 km2 is upstream of

the confluence with Eastern Gully.

0

10

20

30

40

50

60

70

80

90

100

Ap

r-1

3

Jun

-13

Au

g-1

3

Oct

-13

De

c-1

3

Fe

b-1

4

Ap

r-1

4

Jun

-14

Au

g-1

4

Oct

-14

De

c-1

4

Fe

b-1

5

Ap

r-1

5

Jun

-15

Au

g-1

5

Oct

-15

De

c-1

5

Fe

b-1

6

Ap

r-1

6

Jun

-16

Au

g-1

6

Oct

-16

Me

an

Da

ily F

low

(m

3/s

)





Page 18


Figure 5: Spring Gully WTF Release Location

2.2.3 Localised Drainage Water Quality

Monitoring of surface water quality from the water courses within the vicinity of the Project area

has been undertaken as part of the EA requirements and receiving environment monitoring

program (REMP) for the Approved Spring Gully Development Area. The monitoring comprises of

locations upstream and downstream of the Spring Gully WTF release location; and, from adjacent

sub-catchments. Mean surface water quality concentrations from monitoring points located

within the vicinity of the Spring Gully WTF release location are presented in Table 2-2, while the

location of these monitoring points are provided in Figure 6. Water quality monitoring at these

Discharge Locat ion

Spring Gully WTF

E UROM B AH CRE E K

D

URHA M CRE E K

E AS TE R N GUL LY

706,0 00 708,0 00 710,0 007

,12

0,0

00

7,1

22

,00

07

,12

4,0

00

0 0.25 0.5 0.75 1

km

Spring Gully Water Treatment Facility

Discharge Location

Creek

Spring Gully Water Treatment Facility Area

NOTES:

1. Lease l oca tion s sourced from D NR M, 2 016

2. R oads , R ive rs, Towns, QLD D EM: Ge odata Topo 25 0K Series 3 Geo scie nce Austral ia

M ay 2 009 .

3. S pring Gu lly Ae ria l Im age pro vid ed by OE, 2013

PROJECTION

1. Horizon tal Da tum: G DA 94

2. G rid Zone: 55

3. Vert ica l Datum: Mean Sea Level

4. Scale: 1:35,000





Page 19


locations have been undertaken since August 2011. Therefore, Table 2-2 represents mean

parameter concentrations for current conditions, which includes the existing and approved Spring

Gully WTF releases into Eurombah Creek (section 2.2.4).

Figure 6: Eurombah Creek Surface Water Monitoring Points

SGR1

SGR2

SGR3

SGSW14

SGSW15

SGSW20

SGSW21

SGSW22

SGSW34

SG-CR110

SG-CR111

Discharge Location

Spring Gully WTF

E UROMBAH

CRE

EK

DU

RH

AMC R E E

K

EA S T ERN GULLY

706,0 00 708,0 00 710,0 00 712,0 00 714,0 00

7,1

18

,00

07

,12

0,0

00

7,1

22

,00

07

,12

4,0

00

7,1

26

,00

0

0 0.5 1 1.5 2

km

Water Quality Sampling Location

Discharge Location

Spring Gully Water Treatment Facility

Spring Gully Water Treatment FacilityArea

River / Creek

NOTES:

1. Lea se loca tion s sourced fr om DN R M, 2 016

2. R oads , R ive rs, To wn s, QLD DE M: Ge odata Topo 250K Serie s 3 Geo scie nce Au stral ia

M ay 2009 .

3. S pring Gu lly Ae ria l Im age pro vided by OE, 201 3

PROJECTION

1. Horizontal Datum: G DA 94

2. G rid Zone: 55


4. S cale: 1:6 0,0 00





Page 20


Table 2-2 Mean Surface Water Quality Concentrations

Quality

Characteristic Units SGSW14 SG-CR110* SGSW15 SG-CR111* SGR1 SGR2 SGR3 SGSW20 SGSW21 SGSW22 SGSW34

Sample Count

Lab - 78 - 76 - 20 42 48 68 73 74 74

Sample Count

Field - 22 6 21 6 9 14 14 19 19 21 22

pH - 7.38 7.70 7.58 7.75 7.77 7.69 7.56 7.39 7.40 8.12 7.66

Boron mg/L 0.04 0.03 0.03 0.17 0.29 0.28 0.24 0.13 0.16

Electrical

Conductivity µS/cm 335 349 347 345 738 489 475 400 339 674 425

Temperature °C 21.18 22.58 21.75 23.25 22.13 23.00 21.97 22.28 22.33

Calcium mg/L 34.74 34.00 38.71 25.40 16.20 19.75 24.18 24.22 30.68

Turbidity NTU 142.08 129.71 114.12 69.96 77.49 76.69 105.83 44.89 28.94

Dissolved

Oxygen mg/L 4.13 5.13 2.99 4.82 5.83 5.51 5.63 5.92 5.45

Chloride mg/L 70.90 54.37 105.07 152.84 117.93 86.97 88.64 113.75 102.98

Sodium mg/L 59.71 48.33 50.57 124.52 95.14 69.63 72.79 136.05 87.55

Sulphate mg/L 3.57 3.70 6.29 6.28 3.65 2.62 3.35 10.44 5.00

Alkalinity

(Total) mg/L 192.81 177.41 138.75 194.33 116.93 109.37 128.00 233.23 172.73

Sodium

Absorption

Ratio

- 0.87 0.91 1.69 3.01 4.14 4.08 3.54 12.33 4.35

* only in-situ monitoring completed

Parameters presented in Table 2-2 represent the parameters required for monitoring of the

Spring Gully WTF releases into Eurombah Creek as identified in Schedule B: Table 2 – Contaminant

Release Limits for Release Point of the Spring Gully EA (EPPG00885313).

2.2.4 State Approved Spring Gully WTF Releases

Release of treated CSG water from the Spring Gully WTF has been undertaken since 2007 as an

authorised activity under the Spring Gully EA (EPPG00885313 – see section 1.3.1). A summary of

the Spring Gully WTF releases from 2010 is provided in Table 2-3. Monitoring records indicate that

although a Spring Gully WTF release rate of 700 ML/year has been approved, this annual release

volume has not been reached since the commencement of the Spring Gully WTF releases.

Table 2-3 Approved Spring Gully WTF Total Monthly Releases (ML)

2010 2011 2012 2013 2014 2015 2016

January - 40.41 45.20 - 0.03 94.60 -

February - - 98.08 42.25 - 78.96 31.82

March - 41.00 33.93 39.35 17.68 132.06 5.46

April - 63.90 16.99 30.26 128.42 - -

May - 110.32 64.83 68.96 65.69 31.67 -

June - 96.55 98.40 70.56 25.29 12.07 -

July - 59.03 83.00 108.02 18.58 61.14 -

August - 49.00 83.51 36.78 15.42 16.78 -

September - 55.01 13.83 42.60 10.21 6.29 -

October - 55.47 6.72 37.04 - 12.68 -

November 6.73 13.74 11.25 - - 21.10

December 172.50 83.81 - - 85.20 3.80

Total 179.23 668.22 555.74 475.82 366.53 471.13 37.28 * Spring Gully WTF releases to Eurombah Creek commenced in 2007, however, records are only available from 2010.





Page 21


Monitoring of the existing Spring Gully WTF release water quality has been undertaken on a

periodic basis since December 2010. A summary of the water quality results for the parameters

identified in the Spring Gully EA under the contaminant release limits is provided in Table 2-4.

Table 2-4 Spring Gully WTF Release Water Quality Summary

Quality Characteristic Units Count Mean Release Concentration

pH - 551 7.52

Boron mg/L 165 0.45

Electrical Conductivity µS/cm 551 314

Temperature °C 537 21.5

Calcium mg/L 49 15.7

Turbidity NTU 71 0.65

Dissolved Oxygen mg/L 66 6.15

Chloride mg/L 150 74.5

Sodium mg/L 55 56.4

Sulphate as SO4 mg/L 1 0.38

Alkalinity (Total) as CaCO3 mg/L 150 50.9

Sodium Absorption Ratio - 141 4.9

For boron, this study has modelled the WTF release on the basis of a release quality of 1 mg/L,

compared to the actual mean release concentration of 0.45 mg/L. The value of 1 mg/L has been

adopted in the analysis to represent the release limit which is currently being discussed with the

State regulator, EHP, based on a direct toxicity assessment (DTA) for boron which demonstrates

that 1 mg/L is justified. Hence the modelling for boron is inherently conservative.

2.2.5 Eurombah Creek Third Party Users

A review of the Water Plan (Fitzroy Basin) 2011 (DNRM, 2016) and the Fitzroy Basin ROP (DNRM,

2015 indicates that there are no water allocation groups operating along Eurombah Creek; and,

no resource operations licence holders along Eurombah Creek. Therefore, and based on the

ephemeral nature of the creek, it is assumed that there are no third party surface water users

along Eurombah Creek.

2.2.6 Watercourse Springs

A watercourse spring (as defined in OGIA, 2016) is a section of watercourse where groundwater

enters the stream from an aquifer and can also be referred to as a baseflow-fed watercourse.

Within the Study area, one watercourse spring identified as W59 occurs, along Eurombah Creek.

This spring is located approximately 20 km downstream of the Spring Gully WTF release location

(Figure 7), and is sourced by the Upper Hutton Sandstone aquifer. This spring has been reported

to occur as a result of formation outcropping (OGIA, 2016).

Wetlands associated with watercourse springs do not qualify as an EPBC groundwater community

(Fensham et al. 2007, Fensham et al. 2010), and are therefore not considered further in this

assessment.





Page 22


Figure 7 Watercourse Spring W59 Location

2.2.7 Eurombah Creek Downstream Aquatic Ecosystem

Details of the aquatic ecosystem downstream of the Spring Gully WTF release location in

Eurombah Creek is provided in the aquatic ecology report completed by NRA (2016).

DAW SON R IV ER

Spring Gully WTF

EUR

OMBA

H

CRE E K

S1

S2

S3

S4

S5

S6

S8

S7

S9

S10

S12S13

S11 S14

S17

S16

S18

S15

S19

S20

W59

675,0 00 700,0 00 725,0 00 750,0 00

7,0

75

,00

07

,10

0,0

00

7,1

25

,00

07

,15

0,0

00

0 5 10 15 20 25

km

Spring Gully Water Treatment F acility

Watercourse Spring (UWIR, 2016)

River

Creek

Eurombah Creek Catchment

Eurombah Creek Sub-catchment

NOTES:


2. R oads , R ivers, Towns, QLD D EM: Geodata Topo 25 0K Serie s 3 Geoscie nc e A ustra lia

M ay 2 009.

3. D ig ita l Ele vatio n Mode l (D EM) sourced from

D N RM - QSpa tia l, 2015

PROJECTION

1. Ho rizonta l Datum: G DA 94

2. G rid Zone: 55

3. Vert ica l Datum: Mean Sea Leve l

4. Scale: 1:600,000





Page 23


3 CSG WATER PRODUCTION AND WATER MANAGEMENT

3.1 CSG Water Production

One-hundred and fourteen (114) CSG production wells are planned for the Project, comprising a

mix of vertical wells and horizontal wells, spread across the NWDA and NEDA. CSG water will only

be extracted from the vertical wells.

APLNG provided projected CSG water extraction rates based on type curves developed from a

stochastic reservoir simulation model. The combined total water extraction rate projected for the

NWDA and NEDA is presented in Figure 8.

Figure 8: Total Projected Water Extraction for the Project

3.2 Water Management Strategy

Approximately 10,250ML of CSG water will be produced over the life of the Project, with a peak in

March 2019. The CSG water will be transferred to the existing approved facilities on PL195 where

it will be stored and treated via reverse osmosis (RO) desalination, a technology that generates

two products, treated CSG water and brine. If the CSG water is an appropriate quality, it will be

beneficially used prior to treatment. The brine generated by the Project will be stored within the

existing approved ponds in PL195 and disposed of in accordance with the existing Spring Gully

Coal Seam Gas Water Management Plan (Spring Gully CWMP) (Q-8200-15-MP-0001) (APLNG,

2017). This management plan was developed for the Approved Spring Gully Development Area,

however, as the proposed Spring Gully WTF release (280 ML/year) for the Project will be captured

under the authorised Approved Spring Gully Development Area WTF release (700 ML/year) this

management plan will be applicable for the Project.

Specific to this assessment, the Spring Gully CWMP prioritises the distribution of treated water

across the Project area, with beneficial use activities receiving the highest priority for treated

water usage followed by contingency releases into Eurombah Creek. Beneficial uses for the

treated CSG water include:

0

200

400

600

800

1000

1200

2015 2020 2025 2030 2035 2040 2045 2050 2055 2060 2065

Pro

ject

ed

Wa

ter

Ext

ract

ion

(M

L/y

r)

Year





Page 24


� Project construction and operational activities;

� Irrigation in accordance with appropriate regulatory approvals (General Beneficial Use

Approval Irrigation of Associated Water (including coal seam gas water) (EHP, 2014);

� Stock watering; and,

� Aquifer injection into the Precipice Sandstone, in accordance with the Spring Gully EA.

Contingency releases of treated water in Eurombah Creek generally occur when the irrigation

demand decreases (e.g. during high rainfall events and cooler months) and a proportion of treated

water cannot be beneficially used. A summary of the proposed Eurombah Creek release profile for

the Project is provided in the following section.





Page 25


4 ANALYTICAL ASSESSMENT

4.1 Eurombah Creek Catchment Runoff Assessment

SILO climate data was sourced for the Eurombah Creek catchment from the climate database

hosted by the Science Delivery Division of the DSITI. The SILO data comprised synthetic daily

climate records from January 1, 1889 to December 4, 2016. These climate records were analysed

to identify rainfall scenarios to be applied to the Eurombah Creek catchment runoff assessment,

which comprised a median year rainfall distribution and a 1 in 20 year, wet year, rainfall

distribution.

The annual cumulative rainfall for a median year and a 1 in 20 year, wet year, were calculated

from the SILO rainfall records. Using the calculated annual cumulative rainfall, a comparison

against the annual rainfall from the SILO data set was undertaken to select the representative

median and 1 in 20 year, wet year, rainfall distribution for the analytical assessment. The daily

rainfall data sets for 1898 and 1917 were selected as the median and 1 in 20 year, wet year,

rainfall distributions respectively. The monthly rainfall distribution for the representative median

and 1 in 20 year, wet year, are presented in Figure 9. Both rainfall distributions indicate that the

majority of rainfall occurs between September and March, with a dry season between April and

August.

Figure 9: Median (1898) and 1 in 20 Year, Wet Year (1917), Monthly Rainfall Distribution

0

50

100

150

200

250

mm

/mo

nth

Median Monthly Rainfall Distribution 1 in 20 Year, Wet Year, Rainfall Distribution





Page 26


Two climate scenarios were selected for the assessment of potential impacts from the WTF

release on Eurombah Creek. These scenarios comprise the median and the 1 in 20 year, wet year

scenarios; and, were selected to assess potential WTF impacts on the Eurombah Creek flow under

“normal” conditions and high flow conditions, respectively. The median and 1 in 20 year, wet

year, rainfall scenarios were selected based on the assessment of the cumulative rainfall for a

statistically identified median year and 1 and 20 year, wet year, from the SILO data for the Project

area (Section 2.1). The selected cumulative rainfall for both rainfall scenarios were compared with

the SILO cumulative rainfall records (January 1, 1889 to December 4, 2016) to identify daily rainfall

records from the SILO dataset representative of a median year and 1 in 20 year, wet year. Daily

records for 1898 and 1917 were selected as the representative median and 1 in 20 year, wet year.

The median rainfall records indicate that 131 days of rain occur within the year, which includes

daily rainfall events as low as 0.1 mm. However, results from the AWBM (section 4.1.1) identify

that “wetting up” (i.e. saturation) of the upper soil profile is required within the Eurombah Creek

catchment before a rainfall event results in runoff within Eurombah Creek. Therefore, although

131 days of rain occur during the median year, not all of these days represent Eurombah Creek

flow. As a result, the median rainfall scenario is also considered to represent “dry” conditions for

the catchment.

Runoff from the various sub-catchments of the Eurombah Creek catchment was simulated using a

catchment water balance model developed based on the Australian Water Balance Model

(AWBM) (Boughton, 2004). Details of the AWBM developed for Eurombah Creek, and the model

results are provided in the following sections.

4.1.1 Australian Water Balance Model – Eurombah Creek

The AWBM was used as the primary module to estimate the rainfall-runoff relationship for the

Eurombah Creek catchment. The parameters in the AWBM were assessed using the Rainfall-

Runoff-Library (RRL) software program developed by the Water Cooperative Research Centre

(CRC) for Catchment Hydrology.

The inputs to the AWBM model are the observed or recorded rainfall, potential

evapotranspiration and concurrent stream flow data. The input data used for the Eurombah Creek

model was:

� SILO climate data, including daily potential evapotranspiration and rainfall; and,

� Flow data from the DNRM gauging station “Eurombah Creek at Brookfield” (#130376A).

Through the use of a series of parameters, the input rainfall and evapotranspiration data is

correlated with the streamflow data to estimate the runoff produced for the catchment. Table 4-1

shows the parameters adopted in the GoldSim AWBM module.





Page 27


Table 4-1 AWBM Input Parameters

AWBM Parameter Value

C1 32 mm

C2 93 mm

C3 150 mm

Base Flow Index (BFI) 0.95

Ks (Surface Flow Recession Factor) 0.10

Kb (Baseflow Recession Factor) 0.75

Figure 10 shows the comparison between the daily flows modelled within AWBM and the

recorded flows for the Eurombah Creek flow monitoring station at Brookfield (#130376A). Over

the comparison period (April 2013 to October 2016 – most complete set of consecutive

monitoring records from the monitoring station), the recorded total flow passing over the weir

was approximately 103,600 ML (40.8 mm depth of runoff across the catchment), based on the

mean daily flow records, which matched the modelled outputs as shown in Figure 11. Due to the

highly ephemeral natural of Eurombah Creek, and the high losses due to evaporation and seepage

within the creek upstream of the weir, the modelled and recorded daily flows were not able to be

matched as well as the cumulative flows. This may be a result of rainfall variability throughout the

catchment which is unable to be captured in the AWBM.

In addition, only 1 streamflow gauge was available for the catchment, at which point the

upstream catchment is 2,542 km2, which reduces the ability to correlate rainfall and streamflow. A

greater number of streamflow gauges would improve the rainfall-runoff relationship established.

Figure 10: Average Daily Flows – Recorded vs Modelled Flows





Page 28


Figure 11: Cumulative Flows - Recorded vs Modelled Flows

4.1.2 AWBM Scenarios

A number of WTF release, and associated rainfall conditions, scenarios have been simulated using

the Eurombah Creek catchment AWBM to assess flow rates from contributing sub-catchments.

Results from these simulations were used as inputs in the HEC-RAS model to assess flow velocities

and water levels in Eurombah Creek. The current condition, modelled as a 500 ML/year Spring

Gully WTF release, is the base case for the Project scenario comparisons and forms the underlying

conditions for the Eurombah Creek actual water quality and environmental data. These scenarios

comprise:

� Natural conditions – no existing Spring Gully WTF release

� Median year rainfall (repeated over a 5 year duration)

� 1 in 20 year, wet year, rainfall (repeated over a 5 year duration)

� Current conditions, base case for comparisons – 500 ML/year Spring Gully WTF release



� Project only scenarios – 280 ML/year Spring Gully WTF release



� Cumulative scenarios – 700 ML/year Spring Gully WTF release







Page 29


Figure 12: WTF Weekly Releases for the Base Case, Project and Cumulative Scenarios

4.1.3 Model Results and Interpretation

Predicted flows from each of the sub-catchments of the Eurombah Creek catchment for the

AWBM scenarios are provided in Appendix I.

Results from the above scenarios were used as inputs in the HEC-RAS model to assess flow

velocities and water levels in Eurombah Creek. The assessment of potential impacts on Eurombah

Creek from the Project only Spring Gully WTF release (280 ML/year) and the cumulative Spring

Gully WTF release (700 ML/year) was undertaken by comparing the results of these simulations

with the simulated current conditions (500 ML/year) for both median and 1 in 20 year, wet year,

rainfall conditions.

The location of the sub-catchment releases that have been simulated in the model are presented

in Figure 13.

Cumulative flow in Eurombah Creek increases downstream of the Spring Gully WTF towards the

confluence with the Dawson River due to the contribution of sub-catchment flows into Eurombah

Creek. The proposed Spring Gully WTF release contributes to flow in Eurombah Creek. The

proportion of this contribution, based on the mean Spring Gully WTF release and mean Eurombah

Creek flow (for comparative purposes) at model location Point 5 (model location immediately

downstream of the Spring Gully WTF confluence with Eurombah Creek) for the various model

scenarios are predicted to be:

0

20

40

60

80

100

120

140

160

1 8

15

22

29

36

43

50

57

64

71

78

85

92

99

10

6

11

3

12

0

12

7

13

4

14

1

14

8

15

5

16

2

16

9

17

6

18

3

19

0

19

7

20

4

21

1

21

8

22

5

23

2

23

9

24

6

25

3

26

0

ML/

we

ek

Weeks

280 ML/year WTF Release 500 ML/year WTF Release 700 ML/year WTF Release





Page 30


� Median rainfall

� Spring Gully WTF, 280 ML/year – 0.53%



� 1 in 20 year, wet year, rainfall




The results provided in Appendix I were used as sub-catchment inflow inputs into the HEC-RAS

model for the assessment of Eurombah Creek flow velocities and water levels for the various

modelled scenarios (refer to Section 4.2).





Page 31


Figure 13: Eurombah Creek Catchment Sub-catchment Inflow Locations

4.1.4 Model Assumptions and Limitations

The predicted catchment runoff is estimated based on the correlation of the AWBM results with

the Brookfield monitoring station (#130376A), therefore, losses from the system for catchment

runoff have been incorporated into the prediction. However, these losses have not been captured

for the Spring Gully WTF release as this is a direct flux to the system rather than a flux from

catchment runoff. As a result, the total Spring Gully WTF release, simulated in the predictive

simulation of the AWBM, will be present in Eurombah Creek for the entire simulated creek extent

(i.e. the Spring Gully WTF release would report to the downstream Dawson River), which is

DAWSONRIVER

Spring Gully WTF

EUROM

BAH

C REEK2

10

17 16

18

20

S1

S2

S3

S4

S5

S6

S8

S7

S9

S10

S12 S13

S11

S14

S17

S16

S18

S15

S19

S20

675,0 00 700,0 00 725,0 00 750,0 007

,07

5,0

00

7,1

00

,00

07

,12

5,0

00

7,1

50

,00

0

0 5 10 15 20 25

km

Spring Gully Water

Treatment F acility

Flow Model Input Nodes

River

Creek

Eurombah Creek

Catchment

Eurombah Creek Sub-

catchment

NOTES:


2. R oads , R ive rs, Towns, QLD D EM: Geodata Topo 25 0K Serie s 3 Geoscie nce Austral ia

M ay 2 009 .Flow Direction

PROJECTION

1. Horizon tal Datum: G DA94

2. G rid Zone: 55


4. S cale: 1:600,000

EURO MBAH CREEK

6 5

8

INS E T

INS E T

0 0.5 1

km





Page 32


considered to be a limitation of the model, resulting in conservative WTF release contributions to

the Eurombah Creek catchment.

Additionally, the AWBM model does not take into account accumulation of water in the

Eurombah Creek storage during low flow periods or WTF release only periods. Accumulation of

water in the creek storage would limit the extent of the low flow and WTF only flow scenarios in

Eurombah Creek, and dilute the resulting concentration of water quality parameters in the WTF

release. As this has not been captured in this assessment, the results are considered conservative.

4.2 HEC-RAS Hydraulic Modelling

A hydraulic model was used to estimate the changes in flow velocity and water surface elevation

that would occur at key locations in Eurombah Creek in response to the Spring Gully WTF releases.

4.2.1 Model Setup

The model selected for the study was the HEC-RAS model published by the U.S. Army Corps of

Engineers. The model was based on LiDAR data provided on a 1 m grid. A one-dimensional model

was created, extending approximately 55 km downstream of the Spring Gully WTF (based on

extent of the available LiDAR data), ending approximately 27 km upstream of the confluence with

Dawson River. The model also extends 2 km upstream of the Spring Gully WTF release location.

The model is based on 112 cross sections across an average spacing of approximately 500 m for

the extent of the model, which is considered to be adequate for the purposes of the current

study. Four road crossings are located within the model reach. The most downstream cross

section is a bridge for which specific geometric information is available. The channel at the bridge

crossing is approximately 3 m deep, suggesting that the bridge opening is likely quite high.

Therefore, the bridge was omitted from the model.

The Manning’s ‘n’ value (channel roughness) was estimated to be 0.040 based on ground

photographs in previous reports (EECO Pty Ltd. 2007; KCB 2009; NRA Environmental Consultants

2016) and aerial photography available through Google Earth. A guide to Manning’s n values

published by the USGS (1967) was used for reference.

The inflow inputs in the model was specified at several locations based on results from the AWBM

GoldSim model (Section 4.1.2). These locations are as follows:

� The upstream extent of the simulated reach (Point 2; model km 2.35)

� The location where release from the WTF / Eastern Gully would flow into Eurombah Creek

(Point 21; model km 0.00)

� Three locations to account for tributary inflows:

� Point 5; model km – 25.64







Page 33


HEC-RAS model scenarios comprised the scenarios completed for the Eurombah Creek AWBM and

summarised in Section 4.1.2. A summary of results from these model simulations is provided in

Section 4.2.2.


Results of the analysis, in terms of change in water level, are summarised in Table 4-2, with

detailed results provided in Appendix II. These results present the predicted change in water

levels at each modelled location in comparison to base case (current conditions – 500 ML/year

Spring Gully WTF release). Also presented in Table 4-2 is the predicted change in water level

between the base case (500 ML/year WTF release) and the rainfall scenarios with no WTF release

contributions.

Table 4-2 Changes to Water Levels at Selected Locations

Mean Water Level Change from Base Case

Scenario (500 ML./year WTF release) to: Rainfall Scenario

Change in Water Level (m) at Location No.*

21 5 8 10

Release of 280 ML/year (Project only) Median -0.003 -0.006 -0.006 -0.005

1 in 20 year, wet year -0.002 -0.004 -0.004 -0.004

Release of 700 ML/year (Cumulative) Median 0.002 0.004 0.004 0.004

1 in 20 year, wet year 0.001 0.003 0.003 0.003

Mean Water Level Change from No Release

Scenario to: Rainfall Scenario

Change in Water Level (m) at Location No.*

21 5 8 10

Release of 500 ML/year (base case) Median 0.012 0.018 0.017 0.019

1 in 20 year, wet year 0.007 0.012 0.012 0.013

* Change in water level was calculated during natural flow within Eurombah Creek. These calculations do not include

Spring Gully WTF release during “dry” Eurombah Creek conditions.

On average, the release of 280 ML/year from the Spring Gully WTF into Eurombah Creek would

result in a decrease in water levels, when compared to the base case scenario, by -0.2 cm

to -0.6 cm, while the release of 700 ML/year would raise levels, in comparison to the base case

scenario, by 0.1 cm to 0.4 cm. Changes in water levels are fairly consistent from one location on

Eurombah Creek to another, although there is some variability because of the specific hydraulic

conditions at each location.

Predicted mean water level changes as a result of the base case scenario (500 ML/year WTF

release), in comparison to rainfall scenarios with no WTF release contributions, range from 0.7 cm

to 1.9 cm. These changes are relatively consistent between the modelled locations along

Eurombah Creek.

The impact of the releases on creek flow velocities is characterised by averaging the predicted

maximum flow velocities over only those weeks when the release was greater than zero; and, the

combined WTF and natural creek maximum flow velocities is less than double the natural creek

flow velocities1. The number of weeks varies for each scenario, and therefore these numbers

1 Impacts of the WTF releases on creek flow velocities have been assessed based on proportional contribution of the

WTF to the creek flow velocities. Therefore, to avoid unrealistically over-estimating the flow velocity contribution

from the WTF, the flow velocities of the combined WTF and natural creek that are double the flow velocity of natural

creek flow have been omitted from the calculation / assessment.





Page 34


provide only a general indication of the actual effect of the releases. In comparison to the average

flow velocities predicted for the current conditions (500 ML/year Spring Gully WTF release), the

proportional change in the flow velocity relative to current conditions are:

� Project only scenario – 280 ML/year Spring Gully WTF release

� Median rainfall conditions – decrease of 0.008 m/s

� 1 in 20 year, wet year, conditions – decrease of 0.005 m/s

� Cumulative scenario – 700 ML/year Spring Gully WTF release

� Median rainfall conditions – increase of 0.006 m/s

� 1 in 20 year, wet year, conditions – increase of 0.004 m/s

The flow velocities predicted from the HEC-RAS simulations were assessed on a Hjulström Curve

(Boulton et. al., 2014) to assess the potential impact to the Eurombah Creek banks as a result of

changes in the flow velocities. The predicted average flow velocity for the current condition

scenario (500 ML/year WTF release) varies from 0.187 m/s, during median rainfall conditions, to

0.272 m/s during the 1 in 20 year, wet year, rainfall conditions. In comparison, the Project only

scenario varies from 0.179 m/s to 0.267 m/s; while the cumulative scenario varies from 0.193 m/s

to 0.276 m/s for the median and 1 in 20 year, wet year, rainfall conditions, respectively. These

flow velocities, when applied to creek systems comprising sand, silt and clay (similar to Eurombah

Creek) are below the critical erosion velocity for these particle sizes (i.e. ~0.4 m/s for sand,

~200 m/s for clay). Therefore, changes in the flow velocities as a result of the Project and

cumulative scenarios does not pose an erosion risk to the creek.


The following assumptions and limitations are applicable to the HEC-RAS modelling undertaken

for the Eurombah Creek assessment:

� Sub-catchment inflows used as inputs in the HEC-RAS model have been predicted based on

a number of conservative assumptions and limitations (as described in section 4.1.4).

These assumptions and limitations are applicable to the HEC-RAS model.

� The HEC-RAS model has been simulated under steady-state conditions, resulting in the

simultaneous application of sub-catchment inflow to Eurombah Creek. Therefore, a time-

lag in flow within Eurombah Creek has not been simulated and the predicted flow and

water levels are considered conservative.

� The HEC-RAS modelling platform simulates flow in a water course conservatively, with flow

retained between simulated reaches of the water course (i.e. no losses from the system).

Additionally, the modelling platform does not take into account storage accumulation

within the water course during periods of low flow or following prolonged dry periods.

� The use of LiDAR data (instead of surveyed cross sections) limits the accuracy of the model.

In particular:

� The LiDAR data likely underestimates the channel capacity because of water standing

in pools along the creek at the time the LiDAR was flown (if standing water was present

in the channel);





Page 35


� There appear to be many weirs or small dams across the creek that raise upstream

water levels locally and that will not be captured in the model; and,

� Culverts (if any) at the road crossings will not be captured in the model.

These factors would affect the absolute estimates of water level at any given location, but

are believed to have no perceptible effect on the estimates of the change in water level

due to the proposed release.

4.3 Catchment Water Balance / Water Quality Model

4.3.1 Model Set-up

Prediction of water quality along Eurombah Creek was conducted by coupling dissolved water

quality concentrations, based on historical monitoring records, with sub-catchment inflows

predicted in the AWBM GoldSim model (section 4.1). Water quality parameters adopted in the

GoldSim model are consistent with those defined in contaminant release limits for the release of

treated CSG water in the Spring Gully EA2. Temperature, turbidity and dissolved oxygen have been

excluded from these predictions because the GoldSim mass balance is unable to model these

parameters. Although these parameters are not simulated in the model, the REMP monitoring

data and WTF release monitoring data to date demonstrate that these parameters do not cause a

concern in Eurombah Creek when released, and the WTF water quality for the Project will not

change from the water quality of the current WTF release.

Receiving Environment Monitoring Program monitoring records were used to identify the input

water quality concentrations from the Eurombah Creek sub-catchments for the water quality

model, based on average concentrations of the monitoring records. These adopted water quality

concentrations are provided in Table 4-3. A summary of the water quality zones of the water

quality model, applicable model sub-catchments and applicable surface water monitoring points

are provided in Table 4-4. Water quality concentrations adopted for the Spring Gully WTF release

(Table 4-3) is based on the contaminant release limits for the release of treated CSG water in the

Spring Gully EA. The adoption of these Spring Gully WTF release concentrations is considered

conservative as actual water quality concentrations from the WTF release water quality

monitoring records are consistently below the concentration adopted in the model.

Table 4-3 Adopted Eurombah Creek Water Quality Concentrations

pH B (mg/L) EC (uS/cm) Ca (mg/L) Na (mg/L) SO4 (mg/L) Cl (mg/L)

Background* 7.73 0.035 348 34 54 3.64 63

Durham Creek (S4) 6.9 0.025 146 13 10 3 7

WTF Release 7.5 1.0 370 5 115 5 175

* Background concentrations apply to sub-catchment S1, S2, S3, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14, S15, S16, S17, S18, S19 and S20.

2 Schedule B: Table 2 – Contaminant Release Limits for Release Point (EA EPPG00885313).





Page 36


Table 4-4 Water Quality Monitoring Locations Applicable to the Water Quality Model

Water Quality Zone Model Sub-Catchment ID Applicable Monitoring Points

Background

S1, S2, S3, S5 (not including Eastern Gully

contribution), S6, S7, S8, S9, S10, S11, S12, S13, S14,

S15, S16, S17, S18, S19, S20

*SG-CR110, SG-CR111,

SGSW14, SGSW15

Durham Creek S4 Monitoring records from ECCO

(2007) report – Table 2 and 3 * pH and EC concentrations for background water quality zone based on in-situ monitoring from SG-CR110, SG-CR111, SGSW14, SGSW15.

Remaining background water quality parameters are based on laboratory testing results from SGSW14 and SGSW15.

Water quality prediction in the GoldSim model utilised a conservative mass balance approach

resulting in the conservation of mass in Eurombah Creek as each downstream sub-catchment

contributes runoff and load to the creek. Reactive processes associated with runoff mixing and

changing chemical characteristics; and / or, chemical attenuation processes (e.g. absorption etc)

have not been simulated in the model.

Additionally, as identified in Section 4.1.4, limitation of Eurombah Creek flow during low flow

periods as a result of storage accumulation within Eurombah Creek has not been simulated in the

AWBM. This results in the conservation of flow and load across the extent of the simulated

Eurombah Creek, which is simulated as discharging into the Dawson River. Monitoring by APLNG

and DNRM’s stream gauging, has shown that Eurombah Creek is ephemeral, with flows typically

occurring following larger rainfall events. Hence, release flows from the Spring Gully WTF do not

reach the Dawson River except in periods of natural flow when the release water is greatly diluted

by natural runoff contributions to the catchment.


A summary of the predicted water quality concentrations from location points Point 2 (upstream

catchment – pre-WTF contribution), Point 5 (first sub-catchment confluence downstream of WTF

release location) and Point 20 (downstream – confluence with the Dawson River) are provided in

Table 4-5 for the median and 1 in 20 year, wet year; and, 280 ML/year, 700 ML/year and

500 ML/year scenarios. Predicted water quality results for all location points in the model, for the

various scenarios, are provided in Appendix III.

Generally, the predicted water quality results indicate that natural catchment runoff dilutes the

chemical load contributed by the Spring Gully WTF release, with the exception of calcium, where

the WTF release concentration for calcium is lower than background catchment runoff.





Page 37


Table 4-5 Predicted Eurombah Creek Water Quality at Point 2,5 and 20 for the Various Climate and WTF Scenarios and Applicable WQOs

Point 2 Median + 500 ML/yr Median + 280 ML/yr Median + 700 ML/yr 1 in 20 yr, Wet ML/yr

+ 500ML/yr

1 in 20 yr, Wet ML/yr

+ 280ML/yr


+ 700ML/yr WQO

SO4

Minimum (mg/L) 2.022 2.022 2.022 2.022 2.022 2.022

5.000 Maximum (mg/L) 3.640 3.640 3.640 3.640 3.640 3.640

Average (mg/L) 3.578 3.578 3.578 3.578 3.578 3.578

Ca

Minimum (mg/L) 19.090 19.090 19.090 19.090 19.090 19.090

5.000* Maximum (mg/L) 34.370 34.370 34.370 34.370 34.370 34.370

Average (mg/L) 33.782 33.782 33.782 33.782 33.782 33.782

Na

Minimum (mg/L) 30.010 30.010 30.010 30.010 30.010 30.010

- Maximum (mg/L) 54.020 54.020 54.020 54.020 54.020 54.020

Average (mg/L) 53.097 53.097 53.097 53.097 53.097 53.097

Cl

Minimum (mg/L) 34.780 34.780 34.780 34.780 34.780 34.780

- Maximum (mg/L) 62.600 62.600 62.600 62.600 62.600 62.600

Average (mg/L) 61.530 61.530 61.530 61.530 61.530 61.530

pH

Minimum 7.730 7.730 7.730 7.730 7.730 7.730

6.5 - 8.5 Maximum 7.985 7.985 7.985 7.985 7.985 7.985

Average 7.740 7.740 7.740 7.740 7.740 7.740

B

Minimum (mg/L) 0.019 0.019 0.019 0.019 0.019 0.019

0.370 Maximum (mg/L) 0.035 0.035 0.035 0.035 0.035 0.035

Average (mg/L) 0.034 0.034 0.034 0.034 0.034 0.034

EC

Minimum (uS/cm) 193.134 193.134 193.134 193.134 193.134 193.134

210 (high flow),

370 (baseflow) Maximum (uS/cm) 347.761 347.761 347.761 347.761 347.761 347.761

Average (uS/cm) 341.814 341.814 341.814 341.814 341.814 341.814


+ 500ML/yr


+ 280ML/yr


+ 700ML/yr WQO

SO4

Minimum (mg/L) 2.404 2.404 2.404 2.404 2.404 2.404

5.000 Maximum (mg/L) 5.000 5.000 5.000 5.000 5.000 5.000

Average (mg/L) 4.488 4.474 4.494 4.042 4.023 4.051





Page 38


Ca

Minimum (mg/L) 5.000 5.000 5.000 5.000 5.000 5.000

5.000* Maximum (mg/L) 31.500 31.500 31.500 31.500 31.500 31.500

Average (mg/L) 13.646 13.890 13.539 20.870 21.205 20.715

Na

Minimum (mg/L) 31.050 31.050 31.050 31.050 31.050 31.050

- Maximum (mg/L) 115.000 115.000 115.000 115.000 115.000 115.000

Average (mg/L) 92.159 91.528 92.434 72.594 71.721 72.993

Cl

Minimum (mg/L) 35.370 35.370 35.370 35.370 35.370 35.370

- Maximum (mg/L) 175.000 175.000 175.000 175.000 175.000 175.000

Average (mg/L) 134.317 133.189 134.808 99.582 98.024 100.295

pH

Minimum 7.481 7.481 7.481 7.481 7.481 7.481

6.5 - 8.5 Maximum 7.566 7.566 7.566 7.566 7.566 7.566

Average 7.496 7.495 7.496 7.493 7.493 7.493

B

Minimum (mg/L) 0.023 0.023 0.023 0.023 0.023 0.023

0.370 Maximum (mg/L) 1.000 1.000 1.000 1.000 1.000 1.000

Average (mg/L) 0.675 0.666 0.679 0.400 0.387 0.406

EC

Minimum (uS/cm) 210.896 210.896 210.896 210.896 210.896 210.896

210 (high flow),


Average (uS/cm) 350.946 350.449 351.163 333.622 332.924 333.937


+ 500ML/yr


+ 280ML/yr


+ 700ML/yr WQO

SO4

Minimum (mg/L) 1.242 1.242 1.242 0.646 0.646 0.646

5.000 Maximum (mg/L) 5.000 5.000 5.000 5.000 5.000 5.000

Average (mg/L) 4.410 4.399 4.416 4.059 4.044 4.066

Ca

Minimum (mg/L) 5.000 5.000 5.000 5.000 5.000 5.000

5.000* Maximum (mg/L) 33.250 33.250 33.250 33.250 33.250 33.250

Average (mg/L) 14.849 15.078 14.746 22.731 23.017 22.588

Na

Minimum (mg/L) 18.430 18.430 18.430 9.585 9.585 9.585

- Maximum (mg/L) 115.000 115.000 115.000 115.000 115.000 115.000

Average (mg/L) 90.480 89.958 90.719 73.670 73.011 73.999





Page 39


Cl

Minimum (mg/L) 21.360 21.360 21.360 11.110 11.110 11.110

- Maximum (mg/L) 175.000 175.000 175.000 175.000 175.000 175.000

Average (mg/L) 130.995 130.046 131.426 100.131 98.938 100.730

pH

Minimum 7.500 7.500 7.500 7.500 7.500 7.500

6.5 - 8.5 Maximum 8.197 8.197 8.197 8.481 8.481 8.481

Average 7.558 7.559 7.558 7.582 7.583 7.581

B

Minimum (mg/L) 0.012 0.012 0.012 0.006 0.006 0.006

0.370 Maximum (mg/L) 1.000 1.000 1.000 1.000 1.000 1.000

Average (mg/L) 0.641 0.633 0.644 0.379 0.369 0.384

EC

Minimum (uS/cm) 118.642 118.642 118.642 61.701 61.701 61.701

210 (high flow),


Average (uS/cm) 351.219 350.918 351.353 344.623 344.241 344.813

* WQO for calcium is a minimum concentration (i.e. concentrations should be higher than 5 mg/L to be compliant)





Page 40


In comparison to the predicted water quality for base case conditions (500 ML/year WTF release)

the predicted water quality associated with the Project only scenario (280 ML/year WTF release)

shows reduced concentrations for each parameter, with the exception of calcium. The

proportional difference in water quality concentrations between the base case and the Project

only case is as follows for each parameter:

� Sulphate – -0.48% to -0.31%;

� Calcium – 1.61% to 1.79%

� Sodium – -1.20% to -0.69%;

� Chloride – -1.56% to -0.84%;

� pH – -0.003% to -0.002%;

� Boron – -3.12% to -1.34%; and,

� Electrical conductivity – -0.21% to -0.14%

The GoldSim model generally under predicts the instream water quality for parameters other than

for boron. Section 4.3.3 provides a discussion of the limitations of the model which lead to this

under prediction. In assessing the expected impact of the Project on water quality, the changes

between the base case and each Project case need to be considered relative to the REMP data

which proportions the modelling to actual observed results. For boron, as discussed in section

2.2.4, the over-prediction compared to the REMP data is due to the assumption of a 1 mg/L boron

concentration in the WTF release water quality compared to the actual average of 0.45 mg/L.

The applicable WQOs for the Project, derived from the Spring Gully CWMP (APLNG, 2017) and

summarised in Table 1-1, have been compared with the actual REMP data and the changes in the

applicable parameter concentrations predicted for the Project only scenarios (280 ML/year WTF

release) relative to the base case conditions (500 ML/year WTF release – median rainfall and 1 in

20 year, wet year, rainfall). The predicted changes in applicable parameter concentrations for the

base case conditions and Project only scenarios are compliant with the WQOs for the Project, with

the exception of boron for both median and 1 in 20 year, wet year, rainfall conditions.

The change in boron concentration from the base case (500 ML/year release) to the Project only

scenario (280 ML/year release) is modelled as -3.12% to -1.34%. Hence against an average REMP

water quality concentration of 0.20 mg/L for boron3, the WQO of 0.37 mg/L would not be

exceeded. However, using the assumed WTF release concentration of 1 mg/L for boron increases

the predicted average boron concentration to 0.39 – 0.68 mg/L (predicted at Point 5) which is

above the boron WQO of 0.37 mg/L. For this WTF release boron concentration of 1 mg/L to

provide a river quality below the WQO, an amendment of the site specifc limit for boron to 1 mg/L

is required.

3 Based on boron concentrations from REMP monitoring locations downstream of the WTF release location (i.e. SGR3,

SGSW20, SGSW21, SGSW22, SGSW34 – see Table 2-2)





Page 41


A DTA (Origin, 2014) was conducted in accordance with ANZECC/ARMCANZ (2000) Vol. 1

guidelines to specifically assess the impact of boron and this concluded that a level of 1 mg/L was

acceptable as the WQO. As a result, Origin are currently seeking an amendment to the Spring

Gully EA with EHP on this basis, and if approved will request to adopt a WTF release limit of

1 mg/L for boron.

A summary of comparison between the applicable WQO parameters, REMP actual concentrations

and predicted concentration change from the base case conditions to the Project only scenario is

provided in Table 4-6.

Table 4-6: Summary of Comparison of Applicable Water Quality Parameters

Parameter Applicable WQO

Concentration

REMP Actual

Concentration1

Predicted Change from

Base Case

SO4 (mg/L) 5 5.35 -0.48% to -0.31%

Ca (mg/L) 52 24.7 1.61% to 1.79%

Na (mg/L) - 91.5 -1.20% to -0.69%

Cl (mg/L) - 98.1 -1.56% to -0.84%

pH 6.5 – 8.5 7.64 -0.003% to -0.002%

B (mg/L) 0.37 0.20 -3.12% to -1.34%

EC (uS/cm) 370 (baseflow), 210 (high flow) 460 -0.21% to -0.14% 1 REMP actual concentration represents the average parameter concentration from monitoring locations downstream of the WTF release location. 2 WQO concentration for calcium is minimum concentration (i.e. the WQO is triggered when concentrations fall below 5 mg/L


The following assumptions and limitations are applicable to the water quality modelling

completed for the Eurombah Creek catchment:

� The assumptions and limitations associated with the AWBM module and associated results

are applicable to the water quality model as the flow / release rates would influence the

parameter concentrations. Key assumptions adopted in the AWBM module that influence

the water quality results include:

� Water conservation within the model – i.e. water losses from the catchment (e.g.

seepage, evapotranspiration) are not simulated in the model, which may result in the

under-prediction of parameter concentrations.

� Limitation of flow due to accumulation of water in the creek storages has not been

simulated in the model. All in simulated flow in Eurombah Creek progresses to the

downstream confluence with the Dawson River.

� Only dissolved concentrations have been considered. The model has not accounted for

sediment / suspended solid transport along the surface water system. Even though the

sediment / suspended solids have not been captured in the water quality model, it is

anticipated that the water filtration associated with the Spring Gully WTF will limit

sediment to be incorporate with the release to Eurombah Creek. Therefore, the predicted

dissolved water quality concentrations are anticipated to be representative of the

simulated total water quality concentrations.

� Water quality predictions are based on a conservative mass balance mechanism. Chemical

loads that contribute to the Eurombah Creek flow are maintained within the creek to the

confluence with the Dawson River. In reality, adsorption processes between Eurombah





Page 42


Creek water and the creek bed would result in the decrease in parameter concentration

downstream of the WTF release location. Additionally, flow losses (e.g. seepage,

evapotranspiration) and storage accumulation within Eurombah Creek, which have not

been captured in the water quality model, would limit the flow to the Dawson River,

except during periods of higher rainfall / runoff.

� Reactive processes that may result in precipitation (i.e. reduction in dissolved water quality

concentrations), dissolution (i.e. increase in dissolved water quality concentrations) or

attenuation processes (e.g. absorption) have not been simulated in the model. These

processes may result in the variation (increase or decrease) of the predicted parameter

concentrations. However, based on the REMP water quality monitoring records from

Eurombah Creek, these process likely result in the decrease water quality concentrations

(in comparison to the current conditions water quality concentration).

� The release water quality of the Spring Gully WTF is based on the contaminant release

limits defined in the Spring Gully EA (EPPG00885313), however, the WTF release water

quality to date have been below these concentrations.

� Evaporation and associated evapo-concentration mechanisms have not been built into the

water quality model. As a result, potential parameter concentration increases due to

evapo-concentration, which may occur during periods of “no flow” following a flow event

where accumulated ponded water in storage is evaporated over time, is not captured.





Page 43


5 IMPACT ASSESSMENT

The impact on Eurombah Creek as a result of the Spring Gully WTF release is assessed for the

Project only scenario (i.e. WTF release at 280 ML/year) and cumulative scenario (i.e. WTF release

at 700 ML/year) against the base case / current conditions scenario (i.e. WTF release at

500 ML/year). The WTF release for the cumulative scenario represents the approved Spring Gully

WTF release, authorised as an activity under the Spring Gully EA. The proposed Project only WTF

release will be incorporated within the approved 700 ML/year WTF release. No increases to the

approved Spring Gully WTF release rates or annual volume are required as a result of the Project.

5.1 Potential Project Impacts – Significant impact guidelines 1.3

Assessment of potential impacts on Eurombah Creek as a result of the Spring Gully WTF release

(280 ML/year) was undertaken using the guidance provided in the Significant impact guidelines

1.3: Coal seam gas and large coal mining developments – impacts on water resources (DoEE,

2013a).

The significant impact criteria associated with Matters of National Environmental Significance –

Significant impact guidelines 1.1 (DoEE, 2013b) will be addressed in the aquatic ecology

assessment report completed by NRA (2017). Specific to the hydrological system, the significant

impact criteria provided in Significant impact guidelines 1.3: Coal seam gas and large coal mining

developments – impacts on water resources (DoEE, 2013a) have been used to assess potential

impacts on the hydrological system as part of this assessment. The two key significant impact

criteria, from Significant impact guideline 1.3, relevant to this assessment are:

� Guidance on change to hydrological characteristics; and,

� Guidance on changes to water quality.

These significant impact criteria are discussed further, and addressed in the context of this

assessment, in the following sections.

5.1.1 Changes to Hydrological Characteristics

DoEE (2013a) identify that a significant impact as follows:

An action is likely to have a significant impact on a water resource if there is a real or not remote

chance of possibility that it will directly or indirectly result in a change to:

� the hydrology of a water resource,

� the water quality of a water resource,

that is of sufficient scale or intensity as to reduce the current or future utility of the water resource

for third party users, including environmental and other public benefit outcomes, or to create a

material risk of such reduction in utility occurring.

Assessment of changes to the hydrological characteristics of Eurombah Creek was completed by

developing a catchment water balance model (AWBM) to predict sub-catchment flows within the

Eurombah Creek catchment for two rainfall scenarios (median and 1 in 20 year, wet year) and the

Spring Gully WTF release monthly distribution for a 280 ML/year scenario, compared to current

conditions within Eurombah Creek (i.e. existing 500 ML/year WTF release). Predicted catchment





Page 44


inflows were used as inputs for a HEC-RAS model developed for Eurombah Creek to allow

assessment of flow velocities and water levels within the creek up to a distance of ~55 km

downstream of the Spring Gully WTF release location, for both rainfall scenarios. Results from the

modelling indicated that for the release of treated CSG water for the Project only that:

� WTF release volumes will be 220 ML less than the annual average for the base case WTF

release volume. This would result in reduced flows in Eurombah Creek compared with the

base case, with a reduction of 0.44% of the creek flow during median rainfall conditions

and 0.30% of the creek flow during the 1 in 20 year, wet year rainfall conditions.

� Average flow velocities within Eurombah Creek for the Project only scenario would

decrease by an average of 0.008 m/s at each modelled location under median conditions

and an average of 0.005 m/s at each modelled location under the 1 in 20 year, wet year

conditions in comparison to the Spring Gully WTF release for the current conditions.

� The average water level reduction in Eurombah Creek across each of the modelled

locations, as a result of the Project only Spring Gully WTF release scenario, in comparison

to the current conditions scenario, during the median and 1 in 20 year, wet year conditions

range from -0.6 cm to -0.3 cm and -0.4 cm to -0.2 cm, respectively.

Eurombah Creek, downstream of the Spring Gully WTF release location, is underlain by a

combination of Injune Creek Group and Hutton Sandstone outcrop; and, Quaternary alluvium

deposits approximately 25 km downstream of the WTF release location.

A minor decrease in Eurombah Creek water levels is predicted for the Project only scenario

(280 ML/year WTF release) in comparison to current conditions (500 ML/year WTF release),

ranging from -0.2 cm to -0.6 cm. In relation to W59 watercourse spring downstream of the Spring

Gully WTF release location, the decrease in the water level is not predicted to have any impact on

the W59 watercourse spring. This spring is sourced by the Upper Hutton Sandstone, and the

decrease in creek levels is not anticipated to affect the spring source.

The potential for significant impacts as a result of changes to the aspects identified in

Section 1.2.1 are summarised in Table 5-1.

Table 5-1 Summary of Potential Impacts Against Significant Impact Guidelines 1.3 (DoEE, 2013a)

for Changes to Hydrological Characteristics

Parameter Criteria Triggered Comments

Flow Regime No

Project only Spring Gully WTF release in Eurombah Creek has been conservatively predicted

to result in a 0.30% to 0.44% decrease in stream flow, a 0.005 m/s to 0.008 m/s decrease in

average flow velocities and a reduction in creek levels of up to 0.6 cm in comparison to the

current conditions Spring Gully WTF release (500 ML/year).

Therefore, the proposed development is unlikely to result in any significant impact to the

current surface water flow regime of Eurombah Creek; as the predicted flow rates, flow

velocities and creek levels have slightly decreased from current conditions. Additionally, as

flows within Eurombah Creek are intermittent and no downstream users of the water

resources have been identified, a significant impact to the flow regime as a result of the

Project WTF release is not predicted.





Page 45



Recharge rates

to groundwater No

Potential impacts to recharge rates to groundwater as a result of CSG development is

assessed in the Groundwater Assessment for NWDA and NEDA (KCB, 2016).

Spring Gully WTF releases into Eurombah Creek, which flows towards the east to the

Dawson River. Eurombah Creek flows over outcrop of the Injune Creek Group and Hutton

Sandstone, which are not hydrostratigraphic units associated / interconnected with

hydrostratigraphic units associated with the Project CSG development (Bandanna

Formation, Precipice Sandstone). The outcrop of the Precipice Sandstone is location ~36 km

north of the Spring Gully WTF release location. Seepage into the underlying Injune Creek

Group and Hutton Sandstone may occur, however, the predicted water level in Eurombah

Creek associated with the Spring Gully WTF release is slightly lower than the predicted

water level of the current conditions scenario (i.e. level decrease of up to 0.6 cm).

Considering the predicted decrease in water level of Eurombah Creek is within the range of

seasonal water level variability, it is anticipated that the Project only Spring Gully WTF

release is unlikely to result in a significant change to groundwater recharge rates.

Approximately 25 km downstream of the Spring Gully WTF release, Eurombah Creek flows

over Quaternary alluvium, which is mapped to the remainder of the creek extent to the

confluence with the Dawson River. A decrease in the water level of Eurombah Creek would

result in a decreased recharge rate to the Quaternary alluvium. However, the magnitude of

the predicted water level decrease is anticipated to be within the seasonal variability of

water levels within the creek, therefore, the Spring Gully WTF release for the Project is not

anticipated to significantly impact the hydrogeological system of the alluvium.

Based on the observed outcrop geology underlying Eurombah Creek and the anticipated

decrease in creek water levels as a result of the Project in comparison to current conditions,

no significant impacts / changes to recharge as a result of Spring Gully WTF release to

Eurombah Creek are anticipated.

Aquifer

pressure or

pressure

relationship

between

aquifers.

Groundwater

table and

potentiometric

surface levels

No










Based on the interpreted limited change in the groundwater table of the hydrostratigraphic

units underlying Eurombah Creek, no significant impacts to the hydrogeological system are

anticipated.





Page 46



Groundwater /

surface water

interactions

River /

floodplain

connectivity

No










Considering the predicted decrease in water level of Eurombah Creek is within the range of

seasonal water level variability, it is anticipated that the Project only Spring Gully WTF

release is unlikely to result in a significant change to the level of interaction between the

surface water and groundwater systems.

Approximately 25 km downstream of the Spring Gully WTF release Eurombah Creek flows

over Quaternary alluvium, which is mapped to the remainder of the creek extent to the

confluence with the Dawson River. Interaction between Eurombah Creek and the

Quaternary alluvium would occur during periods of flow within Eurombah Creek. A

decrease in the water level of Eurombah Creek would result in a reduction of interaction

between the creek and alluvium. The predicted decrease in the Eurombah Creek water

levels for the Project is up to 0.6 cm, in comparison to current conditions. However, the

magnitude of the predicted water level decrease is anticipated to be within the seasonal

variability of water levels within the creek, therefore, the river / floodplain connectivity is

unlikely to change as a result of the Spring Gully WTF release for the Project.

Potential impacts to groundwater and surface water interactions and river / floodplain

connectivity as a result of the Spring Gully WTF release for the Project are unlikely.

Inter-aquifer

connectivity No




hydrostratigraphic units associated with the NWDA and NEDA CSG development (Bandanna

Formation, Precipice Sandstone). Changes in the groundwater table of the Injune Creek

Group and/or Hutton Sandstone hydrostratigraphic units, as a result of the Spring Gully

WTF release, is unlikely due to the minimal predicted change in Eurombah Creek water

levels from the Project (i.e. decrease of up to 0.6 cm). Therefore, a significant impact as a

result of changes in inter-aquifer connectivity is not anticipated.

Coastal

processes No

The Project area is located in south central Queensland. Given the distance to the coast and

no potential impacts to surface water from the proposed development, changes to coastal

processes will not occur.

5.1.2 Changes to Water Quality

DoEE (2013a) have identified that significant impacts on a water resource may occur as a result of

an activity that may compromise the ability to achieve relevant local or regional water quality

objectives, a significant worsening of local water quality or high quality water is released into an

ecosystem which is adapted to a lower water quality. Potential impacts that may result from

comprised water quality objectives, as a result of an implemented activity, have been provided for

guidance in the Significant impact guidelines 1.3 (DoEE, 2013a) and are summarised in

Section 1.2.1.

Assessment of changes in water quality in Eurombah Creek as a result of the Spring Gully WTF

release for the Project was conducted using a mass balance water quality model. The AWBM

formed the basis for the water quality model, with water quality components built for each flux of

the AWBM allowing the contribution of a chemical load along Eurombah Creek from each in-

flowing sub-catchment and the Spring Gully WTF. Water quality inputs in the model were based





Page 47


on historical Eurombah Creek surface water monitoring records, while the Spring Gully WTF

release water quality was based on the contaminant release limits defined in the Spring Gully EA

(EPPG00885313), with the exception of temperature, turbidity and dissolved oxygen, which were

unable to be simulated in the GoldSim model due to the adopted mass balance approach.

However, although these parameters are not simulated in the model, the REMP monitoring data

and WTF release monitoring data to date demonstrate that these parameters do not cause a

concern in Eurombah Creek when released, and the WTF water quality for the Project will not

change from the water quality of the current WTF release.

Water quality concentrations for the parameters identified in the Spring Gully EA

(EPPG00885313), were predicted along Eurombah Creek for the median and 1 in 20 year, wet year

scenarios. Results from this modelling indicate:

� On average chemical loading from the Spring Gully WTF release during flow periods in

Eurombah Creek is diluted by the natural runoff from the Eurombah Creek catchment

resulting in downstream water quality concentrations lower than the contaminant release

limits (Spring Gully EA (EPPG00885313)), with greater dilution (i.e. lower concentrations)

predicted for the 1 in 20 year, wet year conditions in comparison to the median year

conditions. However, these water quality concentrations are higher than the water quality

from the catchment upstream of the Spring Gully WTF release location (i.e. background

water quality) due to the chemical load from the WTF release. In comparison to the

applicable WQOs for the Project (Table 1-1), the predicted water quality concentrations

would:

� be compliant for pH, EC, calcium and sulphate concentrations; and,

� exceed the current boron WQO concentration (0.37 mg/L). This exceedance is a due to

the adopted WTF release boron concentration (1 mg/L), which results in a predicted

average boron concentration ranging from 0.39 mg/L to 0.67 mg/L. An amendment to

the WTF release limit for boron to 1 mg/L has been prepared and submitted to the

State regulator (EHP), which has been justified in the amendment using DTA data.

In comparison to average current conditions water quality concentrations (500 ML/year

Spring Gully WTF release) from monitoring locations downstream of the Spring Gully WTF

release location, the predicted water quality concentrations from Point 5 (modelled

location immediately downstream of the WTF release location) would be:

� similar for pH;

� slightly lower for boron, sodium, sulphate, chloride and electrical conductivity; and,

� slightly higher for calcium.

� Spring Gully WTF release during “no flow” periods, under both climate scenarios, in the

Eurombah Creek catchment is predict to result in the transfer of the WTF chemical load to

the confluence of the Dawson River. However, this is a result of the conservatism

associated with the water balance / water quality model which retains the WTF release in

the system (i.e. no losses from the system). In reality, this is unlikely to occur as losses

associated with seepage, evaporation and storage accumulation would limit the extent of

the WTF release downstream flow.





Page 48


The potential impact to the downstream aquatic ecosystem associated with the W59 watercourse

spring in Eurombah Creek, as a result of changes in the Eurombah Creek water quality, is provided

in the aquatic ecology report completed by NRA (2016).

The potential for significant impacts to occur as a result of changes in the Eurombah Creek water

quality is summarised in Table 5-2 against the guidance aspects summarised in Section 1.2.1.

Table 5-2 Summary of Potential Impacts Against Significant Impact Guidelines 1.3 (DoEE, 2013a)

for Changes to Water Quality


Create risk to

human or

animal health

or to the

condition of the

environment

No

On average, the predicted water quality concentrations for the Project only scenario within

Eurombah Creek will be within the WQOs, with the exception of boron. The exceedance of

the boron WQO is a result of the adopted 1 mg/L WTF release concentration, which is based

on the contaminant release limits specific in the Spring Gully EA (EPPG00885313). A DTA

(Origin, 2014) was conducted in accordance with ANZECC/ARMCANZ (2000) guidelines to

specifically assess the impact of boron and this concluded that a level of 1 mg/L was

acceptable as the WQO. Origin are currently seeking an amendment to the Spring Gully EA

with EHP on this basis, and if approved will request to adopt a WTF release limit of 1 mg/L

for boron.

A comparison of predicted Project only (280 ML/year) concentrations to the base case

concentrations (500 ML/year WTF release) indicate that the predicted concentrations will

be similar to or lower than current conditions, with the exception of calcium, which will

have a higher predicted concentration.

During periods of “no flow” in the Eurombah Creek catchment Spring Gully WTF release

may also occur. The predicted water quality in Eurombah Creek resulting from this scenario,

not including potential dilution from water in storage within the creek, is equivalent to the

contaminant release limits specified in the Spring Gully EA (EPPG00885313), with the

exception of boron (as discussed above), which is the same as the adopted water quality of

the WTF release. These predicted concentrations are a conservative estimate as the

anticipated release water quality from the WTF will be lower than the concentrations

adopted in the water quality model (i.e. contaminant release limits (Spring Gully EA

(EPPG00885313)). The mean WTF release parameter concentrations (Table 2-4) indicate

that to date WTF release parameter concentrations have been below the EA limits.

Due to the ephemeral nature of Eurombah Creek, third-party use of water in Eurombah

Creek is not anticipated to occur and is not identified under the Water Plan (Fitzroy Basin)

2011 and Fitzroy Basin ROP. Therefore, any potential risk to human health as a result of the

Project WTF release is not anticipated.

Current water quality conditions in Eurombah Creek include contributions from the Spring

Gully WTF release (500 ML/year), which is greater than the predicted release rates for the

Project (280 ML/year). REMP surface water monitoring of Eurombah Creek (i.e. water

quality, hydrological characteristics) associated with the approved WTF have not identified

any risks to human health, animal health or the condition of the environment as a result of

5 years of releases from the WTF

Therefore, it is predicted that the Spring Gully WTF release for the Project will not result in a

significant impact to human or animal health, or to the condition of the environment.





Page 49



Substantially

reduce the

amount of

water available

for human

consumptive

uses or for

other uses,

including

environmental

uses which are

dependent on

water of the

appropriate

quality

No

The Spring Gully WTF release into Eurombah Creek for the Project is 220ML lower than the

annual average release rates from the Spring Gully WTF for the past 5 years. There would

be corresponding reduction to annual stream flows, flow velocities and in water levels

within Eurombah Creek in comparison to current conditions. However, although slight

decreases are predicted, the Project WTF release forms a proportion of the overall and

already approved Spring Gully WTF release (700 ML/year – cumulative scenario). As a

result, the Project will not substantially reduce the amount of water available for human

consumption and/or environmental uses.

Changes in water quality within Eurombah Creek as a result of the Spring Gully WTF release

are predicted to be minimal, with average chemical load contributions for the Project

predicted to be less than the predicted current conditions scenario (500 ML/year WTF

release) and similar to the downstream REMP monitoring records. The predicted

concentrations for the “no flow” period scenario are considered conservative as the

anticipated release water quality from the WTF will be lower than the concentrations

adopted in the water quality model (i.e. contaminant release limits (Spring Gully EA

(EPPG00885313))).

Therefore, as no changes to the amount of available water for human consumptive uses or

environmental uses are anticipated, a significant impact as a result of these changes are not

predicted.

Causes

persistent

organic

chemicals,

heavy metals,

salt or other

potentially

harmful

substances to

accumulate in

the

environment

No

Treatment of associated water from the NWDA and NEDA development will be conducted

at the existing Spring Gully WTF with treated water potentially being released into

Eurombah Creek as part of the water management strategy. The WTF release water quality

will be compliant with the contaminant release limits as defined in the Spring Gully EA

(EPPG00885313).

The REMP sediment data demonstrates that there has been no significant

accumulation of organic chemicals, heavy metals or salt for the base case

condition (500 ML/year WTF release). The Project case represents a reduction in

the release volume at the same concentration, and hence is not predicted to cause

accumulation in the environment.

Changes in water quality within Eurombah Creek as a result of the Spring Gully WTF release

are predicted to be minimal, with average chemical load contributions for the Project

predicted to be less than the predicted current conditions scenario (500 ML/year WTF

release) and similar to the downstream REMP monitoring records.

Evapo-concentration of the water quality within Eurombah Creek may occur during periods

of low flow and “no flow” within the creek, resulting in standing pools of water. Water

quality concentrations may increase as a result of evaporation. During periods of flow (both

natural and WTF release) dilution of the standing pools would result, flushing the diluted

water within the creek, mitigating the potential accumulation of chemical load in the

downstream environment.

The Spring Gully WTF release is unlikely to cause any harmful substances to accumulate in

the downstream environment.

Seriously

affects the

habitat or

lifecycle of a

native species

dependent on a

water resource

The assessment of potential significant impacts against this criterion is cover in the aquatic

ecology assessment completed by NRA (2017).





Page 50



Causes the

establishment

of an invasive

species (or the

spread of an

existing

invasive

species) that is

harmful to the

ecosystem

function of the

water resource

The assessment of potential significant impacts against this criterion is cover in the aquatic

ecology assessment completed by NRA (2017).

There is a

significant

worsening of

local water

quality (where

current local

water quality is

superior to

local or

regional water

quality

objectives)

No

Water quality concentrations within Eurombah Creek as a result of the Project only Spring

Gully WTF release scenario are predicted to be lower than the predicted water quality

concentration for the current conditions scenario (500 ML/year WTF release) with the

exception of calcium. In comparison to the REMP monitoring records, the predicted water

quality concentrations in Eurombah Creek, for applicable parameters are similar. The

predicted water quality concentrations associated with the Project only WTF release are

compliant with the concentration of the WQOs for applicable parameters, with the

exception of boron. The exceedance of the boron WQO is a result of the adopted 1 mg/L

WTF release concentration, which is based on the contaminant release limits specific in the

Spring Gully EA (EPPG00885313). A DTA (Origin, 2014) was conducted in accordance with

ANZECC/ARMCANZ (2000) guidelines to specifically assess the impact of boron and this

concluded that a level of 1 mg/L was acceptable as the WQO. Origin are currently seeking

an amendment to the Spring Gully EA with EHP on this basis, and if approved will request to

adopt a WTF release limit of 1 mg/L for boron.

High quality

water is

released into

an ecosystem

which is

adapted to a

lower quality of

water

No

The predicted water quality in Eurombah Creek as a result of the Spring Gully WTF release is

predicted to be similar to, or better than, the water quality of current conditions in

Eurombah Creek.

Current conditions in Eurombah Creek include the Spring Gully WTF release associated with

the Approved Spring Gully Development Area (500 ML/year). The water quality associated

with the Project WTF release is anticipated to be similar to the WTF release water quality

currently being undertaken. Therefore, significant impacts associated with high quality

water release into an adapted ecosystem is not anticipated.

5.2 Cumulative Impacts

Currently, the Spring Gully WTF release into Eurombah Creek, which is an authorised activity

associated with the Approved Spring Gully Development Area, is approved to release at a rate of

10.2 ML/day and 700 ML/year. The proposed Spring Gully WTF release into Eurombah Creek

associated with the NWDA and NEDA developments is based on a rate of 280 ML/year. APLNG

propose to incorporate the 280 ML/year WTF release from NWDA and NEDA within the already

approved 700 ML/year release rate, therefore, additional release into Eurombah Creek from the

WTF above the already approved 700 ML/year release rate will not be required.

Ongoing Spring Gully WTF release into Eurombah Creek will be limited to 10.2 ML/ day and

700 ML/year, including the contribution from the NWDA and NEDA developments. Therefore, the

prediction of flow rates, flow velocities, water levels and the water quality in Eurombah Creek as a

result of a WTF release rate of 700 ML/year is considered appropriate for the assessment of

cumulative impacts. The assessment of cumulative impacts for flows, levels and water quality in

Eurombah Creek is provided in the following sections.





Page 51


5.2.1 Predicted Cumulative Flow and Levels – Eurombah Creek

The 700 ML/year Spring Gully WTF release rate into Eurombah Creek was simulated in the

catchment water balance model (AWBM) and the HEC-RAS model to assess the contribution of

the WTF to changes in the creek flow rate, flow velocities and water levels. Two simulations based

on the median annual rainfall and the 1 in 20 year, wet year rainfall were undertaken for the

700 ML/year WTF release. Results from the modelling indicated:

� an increase in the Eurombah Creek flow is observed immediately downstream of the

Spring Gully WTF release location (Point 5) as a result of the cumulative WTF release,

contributing 0.37% of the creek flow during median rainfall conditions and 0.25% of the

creek flow during the 1 in 20 year, wet year rainfall conditions, in comparison to the

median and 1 in 20 year, wet year rainfall conditions, for the current Spring Gully WTF

release contributions (500 ML/year);

� average flow velocities within Eurombah Creek would increase by 0.006 m/s under median

conditions and 0.004 m/s under the 1 in 20 year, wet year, conditions as a result of the

Spring Gully WTF release in comparison to the median and 1 in 20 year, wet year, rainfall

conditions, for the current Spring Gully WTF release contributions (500 ML/year),

respectively; and,

� the average water level rise in Eurombah Creek as a result of the Spring Gully WTF release

during the median and 1 in 20 year, wet year conditions are both less than 0.5 cm in

comparison to the current conditions (500 ML/year Spring Gully WTF release).

The 700 ML/year WTF release rate represents 1.34% and 0.92% of the flows present in the river

during a median rainfall and1 in 20 year, wet year rainfall. This shows that the natural runoff of

the Eurombah Creek catchment governs the characteristics of flow within the creek, with minimal

contribution anticipated from the WTF release for both Project only and cumulative scenarios.

Although the cumulative scenario results in a slight increase in flow rate, flow velocity and water

level of Eurombah Creek compared with current conditions, this change is unlikely to significantly

impact the downstream receiving environment.

There are no other known releases into the Eurombah Creek from other CSG, mining or industrial

activities.

5.2.2 Predicted Cumulative Water Quality – Eurombah Creek

Assessment of the cumulative impacts on the Eurombah Creek water quality was conducted using

the AWBM, updated with the water quality components, based on the Spring Gully WTF release of

700 ML/year. Input water quality concentrations adopted for the Project only scenario are the

same for the cumulative scenario. Results from the modelling indicate:

� Chemical loading from the Spring Gully WTF release during flow events in Eurombah Creek

is diluted by the natural runoff resulting in downstream water quality concentrations lower

than the contaminant release limits (Spring Gully EA (EPPG00885313)), but slightly higher

than the Project only predicted concentrations. In comparison to the applicable WQOs for

the Project (Table 1-1), the predicted average water quality concentrations would:





Page 52


� be compliant for pH, EC, calcium and sulphate concentrations; and,

� exceed the current boron WQO concentration (0.37 mg/L). This exceedance is a due to

the adopted WTF release boron concentration (1 mg/L), which results in a predicted

average boron concentration ranging from 0.41 mg/L to 0.68 mg/L. A DTA (Origin,

2014) was conducted in accordance with ANZECC/ARMCANZ (2000) guidelines to

specifically assess the impact of boron and this concluded that a level of 1 mg/L was

acceptable as the WQO. Origin are currently seeking an amendment to the Spring Gully

EA with EHP on this basis, and if approved will request to adopt a WTF release limit of

1 mg/L for boron.





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6 CLOSING

KCB is pleased to provide this Eurombah Creek Surface Water Impact Assessment for the

proposed development of the Spring Gully NWDA and Spring Gully NEDA.

This report is an instrument of service of Klohn Crippen Berger Ltd. The report has been prepared

for the exclusive use of OERL (Client) for the specific application to the Spring Gully NWDA and

Spring Gully NEDA. The report's contents may not be relied upon by any other party without the

express written permission of Klohn Crippen Berger. In this report, Klohn Crippen Berger has

endeavoured to comply with generally-accepted professional practice common to the local area.

Klohn Crippen Berger makes no warranty, express or implied.

Yours truly,

KLOHN CRIPPEN BERGER LTD.

Chris Strachotta, RPGeo

Senior Hydrogeologist





Page 54


REFERENCES

Australian and New Zealand Environment and Conservation Council and Agriculture and Resource

Management Council of Australia and New Zealand, 2000. Australian and New Zealand

Guidelines for Fresh and Marine Water Quality. Vol. 1. The Guidelines. October 2000.

Australia Pacific LNG, 2017. Spring Gully Coal Seam Gas Water Management Plan (Q-8200-15-MP-

0001) (Revision 6). Report prepared by Australia Pacific LNG.

Australia Pacific LNG, 2016a. Technical Memorandum. Contaminant Release (boron) and

Eurombah Creek Surface Water Values. Prepared by Australia Pacific LNG, 8 November 2016.

Australia Pacific LNG, 2016b. Environmental Authority EPPG00885313 Amendment Application

Boron and Temperature (difference) Release Limits. Supporting Information Report for the

amendment of the Spring Gully release limits for Boron and temperature, 31 November 2016.

Australia Pacific LNG, 2015. Spring Gully Coal Seam Gas Water Management Plan (Q-8200-15-MP-

0001).

Australia Pacific LNG, 2010. Australia Pacific LNG Project EIS, Volume 5: Attachments, Attachment

22: Surface Water and Watercourses – Gas Fields.

Boughton,W. 2004. The Australian water balance model. Environmental Modelling and Software. Vol. 19. PP 943-956.

Boulton.A., Brock.M., Robson.B., Ryder.D., Chambers.J., and Davis.J., 2014. Australian Freshwater Ecology: Processes and Management, 2nd Edition. Wiley-Blackwell, May 2014.

Department of Environment and Heritage Protection (2015). Spring Gully Environmental Authority (Permit No. EPPG00885313).

Department of Environment and Heritage Protection (2014). General beneficial use approval – Associated water (including coal seam gas water).

Department of Environment and Heritage Protection (2011). Dawson River Sub-Basin Environmental Values and Water Quality Objectives Basin No. 130 (part), including all waters of the Dawson River Sub-basin except the Callide Creek Catchment September 2011

Department of Environment, Commonwealth of Australia (2013a). Significant impact guidelines 1.3: Coal seam gas and large mining developments – impact on water resources.

Department of Environment, Commonwealth of Australia (2013b). Matters of National Environmental Significance. Significant impact guidelines 1.1. Environmental Protection and Biodiversity Conservation Act 1999.

Department of Natural Resources and Mines (2015). Fitzroy Basin Resource Operations Plan.

EECO Pty Ltd. 2007. Spring Gully Coal Seam Gas Field: Assessment of Discharging Reverse Osmosis

Permeate to Eurombah Creek. A report to Origin Energy Limited. Report No. POEN05-R01.

Klohn Crippen Berger Ltd. 2009. Eurombah Creek Sampling Program: Spring Gully – Draft Interim

Report. A report to Origin Energy. KCB File No. M09620A01.

Natural Resources Assessment (2016). EPBC Act Report Proposed Spring Gully CSG Water Release to Eurombah Creek – Assessment of Potential Impact. Report prepared for Origin Energy Limited.

Origin Energy Resources Limited (2014). Condamine River – DTA of boron on treated CSG water. Report completed by Origin Energy Limited. January 2014.





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U.S. Geological Survey. 1967. Roughness Characteristics of Natural Channels. USGS Water Supply

Paper 1849. By H.H. Barnes.



APPENDIX I

AWBM Predicted Sub-catchment Inflow






APPENDIX II

HEC-RAS Predicted Model Results






APPENDIX III

GoldSim Water Quality Model Results

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