NT Mining Operations Pty Ltd Union Reefs North ... - NT EPA

1 NT Mining Operations Pty Ltd Union Reefs North Underground Mine Draft Environmental Impact Statement

NT Mining Operations Pty Ltd Union Reefs North Underground Mine

Draft Environmental Impact StatementPart 1

i NT Mining Operations Pty Ltd Union Reefs North Underground Mine Draft Environmental Impact Statement

TABLE OF CONTENTS

1 Executive Summary ............................................................................................................................................... 1

1.1 Context ......................................................................................................................................................... 1

1.2 Site History .................................................................................................................................................... 2

1.3 Project Description ....................................................................................................................................... 2

1.4 Alternatives ................................................................................................................................................... 5

1.5 Mine Water Management ............................................................................................................................ 5

1.6 Mine Closure ................................................................................................................................................. 6

1.7 Existing Environment .................................................................................................................................... 6

1.8 Risk Assessment ............................................................................................................................................ 7

1.9 Terrestrial Flora and Fauna ........................................................................................................................... 8

1.10 Hydrological Processes ............................................................................................................................... 13

1.11 Inland Water Environmental Quality .......................................................................................................... 15

1.12 Aquatic Ecosystems .................................................................................................................................... 17

2 Acronyms .............................................................................................................................................................20

3 Introduction .........................................................................................................................................................23

3.1 Overview ..................................................................................................................................................... 23

3.2 The Proponent ............................................................................................................................................ 23

3.3 Project Location .......................................................................................................................................... 23

3.4 Environmental and Social Performance ..................................................................................................... 28

3.4.1 Social Responsibility and Community Benefit .................................................................................... 29

4 Proposal Description ............................................................................................................................................30

4.1 Summary Information ................................................................................................................................. 34

4.2 Existing Authorisations ............................................................................................................................... 35

4.3 Site History .................................................................................................................................................. 38

4.4 Proposal Context......................................................................................................................................... 38

4.5 Mine Schedule ............................................................................................................................................ 39

4.6 URPA Existing Infrastructure ....................................................................................................................... 39

4.6.1 Hazardous Substances ........................................................................................................................ 40

4.6.2 Energy ................................................................................................................................................. 40

4.6.3 Run Of Mine (ROM) Pad ..................................................................................................................... 40

4.6.4 Processing Plant ................................................................................................................................. 41

4.7 Operational Water Infrastructure ............................................................................................................... 44

4.7.1 Mine Water Dams .............................................................................................................................. 47

4.7.2 Tailings Storage Facility ...................................................................................................................... 48

4.8 New Infrastructure ..................................................................................................................................... 49

4.8.1 Explosives Magazine ........................................................................................................................... 49

4.9 Mine Development ..................................................................................................................................... 50

ii NT Mining Operations Pty Ltd Union Reefs North Underground Mine Draft Environmental Impact Statement

4.10 Mine Production ......................................................................................................................................... 50

4.10.1 Blasting ............................................................................................................................................... 53

4.10.2 Material Characterisation ................................................................................................................... 53

4.10.3 Processing ........................................................................................................................................... 54

4.10.4 Equipment and Vehicles ..................................................................................................................... 55

4.10.5 Workforce ........................................................................................................................................... 55

4.11 Alternatives ................................................................................................................................................. 55

5 Approvals and Regulatory Framework .................................................................................................................60

5.1 Overview ..................................................................................................................................................... 60

5.1.1 Commonwealth Legislation ................................................................................................................ 60

5.1.2 Northern Territory Legislation ............................................................................................................ 61

5.1.3 Policies and Guidelines ....................................................................................................................... 64

5.1.4 KLG Policies......................................................................................................................................... 65

5.1.5 Australian Standards .......................................................................................................................... 66

5.1.6 Non-Statutory Obligations.................................................................................................................. 66

6 Stakeholder Engagement and Community ...........................................................................................................67

6.1 Consultation ................................................................................................................................................ 67

7 Existing Environment ...........................................................................................................................................71

7.1 Bioregional Description............................................................................................................................... 71

7.2 Climate ........................................................................................................................................................ 73

7.2.1 Rainfall and Evaporation .................................................................................................................... 73

7.3 Geology ....................................................................................................................................................... 75

7.4 Hydrogeology .............................................................................................................................................. 77

7.5 Hydrology .................................................................................................................................................... 78

7.5.1 Flooding .............................................................................................................................................. 78

7.5.2 Water Quality ..................................................................................................................................... 82

7.6 Land Systems and Vegetation ..................................................................................................................... 83

7.7 Fauna .......................................................................................................................................................... 87

7.7.1 Results ................................................................................................................................................ 87

7.8 Introduced Species ..................................................................................................................................... 89

8 Mine Water Management ....................................................................................................................................90

8.1 Operational Water Balance ........................................................................................................................ 90

8.1.1 Direct Rainfall, Catchment Runoff and Evaporation .......................................................................... 91

8.1.2 Raw Water from Dam C ...................................................................................................................... 91

8.1.3 Groundwater Ingress .......................................................................................................................... 91

8.1.4 Retained in Tailings ............................................................................................................................ 91

8.1.5 Seepage In and Out of Crosscourse Pit .............................................................................................. 91

8.1.6 Discharge under WDL and Change in Storage .................................................................................... 92

8.1.7 Sensitivity to Rainfall Conditions ........................................................................................................ 93

iii NT Mining Operations Pty Ltd Union Reefs North Underground Mine Draft Environmental Impact Statement

8.2 Flood Assessment ....................................................................................................................................... 93

8.2.1 Prospect Pit ........................................................................................................................................ 94

8.2.2 Crosscourse Pit ................................................................................................................................... 95

8.3 Water Security ............................................................................................................................................ 95

8.4 Post Closure ................................................................................................................................................ 95

8.4.1 Prospect Pit ........................................................................................................................................ 95

8.4.2 Crosscourse Pit ................................................................................................................................... 96

8.5 Waste Discharge License ............................................................................................................................ 97

8.5.1 Discharge Location ............................................................................................................................. 98

8.5.2 Preliminary Site Specific Trigger Values ........................................................................................... 100

8.5.3 Water Treatment .............................................................................................................................. 101

8.5.4 Discharge Regime ............................................................................................................................. 104

9 Mine Closure ...................................................................................................................................................... 105

9.1 Closure Domains ....................................................................................................................................... 105

9.1.1 Union Reefs North Underground Mine Closure Domain.................................................................. 108

9.1.2 Haul Road Closure Domain ............................................................................................................... 113

9.1.3 Prospect South Pit Closure Domain .................................................................................................. 116

9.1.4 Prospect North Pit Closure Domain.................................................................................................. 119

9.1.5 Dam A and Dam C Closure Domain .................................................................................................. 122

9.1.6 Dam B Closure Domain ..................................................................................................................... 125

9.1.7 Crosscourse Pit Closure Domain ....................................................................................................... 127

9.1.8 Processing Operations Closure Domain ........................................................................................... 130

9.2 Summary of Disturbance Areas and Required Rehabilitation Soil/Growth Medium ............................... 134

9.3 Decommissioning and Rehabilitation ....................................................................................................... 135

9.4 Closure Objectives .................................................................................................................................... 136

9.5 Potential Risks to Successful Closure, Decommissioning and Rehabilitation ........................................... 136

10 Risk Assessment ................................................................................................................................................. 138

10.1 Risk Assessment Methodology ................................................................................................................. 138

10.1.1 Risk Assessment Workshop .............................................................................................................. 139

10.1.2 Context Establishment ..................................................................................................................... 140

10.1.3 Risk Identification ............................................................................................................................. 140

10.1.4 Risk Analysis and Evaluation ............................................................................................................. 140

10.1.5 Risk Treatment ................................................................................................................................. 141

10.1.6 Risk Register ..................................................................................................................................... 141

10.2 Discussion of Key Outcomes ..................................................................................................................... 142

10.2.1 Risk Assessment Results ................................................................................................................... 142

11 Terrestrial Flora and Fauna ................................................................................................................................ 157

11.1 Overview ................................................................................................................................................... 157

11.2 Environmental Values ............................................................................................................................... 157

iv NT Mining Operations Pty Ltd Union Reefs North Underground Mine Draft Environmental Impact Statement

11.2.1 Ecology and conservation Status of the Ghost Bat .......................................................................... 157

11.2.2 Geographic Extent of the Regional Population ................................................................................ 158

11.2.3 Characteristics of Known and Likely Natural and Artificial Roosts in the Proposal Area ................. 158

11.3 Potential Impacts and Risks ...................................................................................................................... 164

11.3.1 Risk Assessment Summary ............................................................................................................... 164

11.3.2 Noise and Vibration .......................................................................................................................... 165

11.3.3 Temporary Exclusion to Roosts and Alternative Roosts ................................................................... 165

11.3.4 Disturbance to Roosts ...................................................................................................................... 168

11.3.5 Commonwealth Matters of National Environmental Significance (MNES) ...................................... 170

11.4 Mitigation and Management Mitigation Strategy .................................................................................... 171

11.5 Monitoring and Reporting ........................................................................................................................ 174

11.5.1 Monitoring ........................................................................................................................................ 174

11.6 Statement of Residual Impact .................................................................................................................. 176

12 Hydrological Processes ....................................................................................................................................... 177

12.1 Overview ................................................................................................................................................... 177




12.3.2 Groundwater Drawdown ................................................................................................................. 185

12.3.3 McKinlay River .................................................................................................................................. 186

12.3.4 Pine Creek Borefield ......................................................................................................................... 190

12.3.5 Pine Creek and Copperfield Creek Catchments ................................................................................ 190

12.3.6 Crosscourse Pit ................................................................................................................................. 190

12.3.7 Other Pits .......................................................................................................................................... 190

12.3.8 Dams and Ponds ............................................................................................................................... 190

12.3.9 Stakeholders ..................................................................................................................................... 190

12.4 Mitigation and Management .................................................................................................................... 190

12.4.1 Further Modelling............................................................................................................................. 191



12.6.1 McKinlay River and other Ponds and dam ....................................................................................... 193

13 Inland Water Environmental Quality .................................................................................................................. 194

13.1 Overview ................................................................................................................................................... 194


13.2.1 Permanent Water Bodies ................................................................................................................. 198

13.2.2 Baseline Surface Water Quality ........................................................................................................ 198

13.2.3 Surface Water Monitoring Data ....................................................................................................... 200

13.2.4 Groundwater Monitoring Data......................................................................................................... 201


v NT Mining Operations Pty Ltd Union Reefs North Underground Mine Draft Environmental Impact Statement


13.3.2 Impact Assessment ........................................................................................................................... 203




14 Aquatic Ecosystems ............................................................................................................................................ 210

14.1 Overview ................................................................................................................................................... 210


14.2.1 Groundwater Dependent Ecosystems .............................................................................................. 211

14.2.2 Aquatic Ecosystem Characterisation ................................................................................................ 215



14.3.2 Changes to Hydrological Processes .................................................................................................. 217

14.3.3 Changes to Water Quality ................................................................................................................ 220



14.5.1 Additional Characterisation of the Fauna Community ..................................................................... 220

14.5.2 Identify Reference Locations ............................................................................................................ 221


15 References ......................................................................................................................................................... 222

TABLES

Table 1-1 Indicative Project Schedule .......................................................................................................................... 1

Table 1-2 Key project components .............................................................................................................................. 2

Table 1-3 key environmental factors ........................................................................................................................... 7

Table 1-4 URPA adit locations ...................................................................................................................................... 9

Table 1-5 Ghost Bat Potential Impacts and Mitigation Measures ............................................................................. 10

Table 1-6 POTENTIAL impacts associated with mine dewatering .............................................................................. 14

Table 1-7 reduction in groundwater availability the McKinlay river .......................................................................... 18

Table 3-1 NT Mining Operations Contact ................................................................................................................... 23

Table 4-1 Project Key Components ............................................................................................................................ 34

Table 4-2 Summary of Authorised NTMO Operations in the Pine Creek Region ....................................................... 35

Table 4-3 Indicative Project Schedule ........................................................................................................................ 39

Table 4-4 Crosscourse Pit Freeboard May 2019 ........................................................................................................ 44

Table 4-5 Site Water Management ............................................................................................................................ 45

Table 4-6 URPA Explosives Bunker Storage ............................................................................................................... 49

Table 4-7 URPA Processing Tonnes and Ounces (Sourced from URPA and CHPA) .................................................... 53

Table 5-1 Commonwealth Legislation ........................................................................................................................ 60

vi NT Mining Operations Pty Ltd Union Reefs North Underground Mine Draft Environmental Impact Statement

Table 5-2 Northern Territory Legislation ................................................................................................................... 61

Table 6-1 Stakeholder Consultation ........................................................................................................................... 68

Table 7-1 Flood Frequency Analysis (FFA) Expected Probability Flows for the URPA ................................................ 78

Table 7-2 Land Unit Description – Land Unit of the Urpa (From Napier & Steen, 2002) ........................................... 83

Table 7-3 URPA Identified Declared Weeds 2013 to 2019 ......................................................................................... 89

Table 7-4 URPA Identified Pest Species 2013 to 2018 ............................................................................................... 89

Table 8-1 Site Water Balance – Mine Operations ...................................................................................................... 90

Table 8-2 Site Water Balance – Mine Operations – Wet Conditions ......................................................................... 93

Table 8-3 Prospect Pit Portal Flooding Risk Assessment ............................................................................................ 94

Table 8-4 72 Hrs Crosscourse Pit Flooding Risk Assessment ...................................................................................... 95

Table 8-5 Proposed Receiving Environment SSTVs for URSW08 ............................................................................. 100

Table 8-6 Preliminary Testwork Pre-Treatment and Treatment Water Quality Results – Crosscourse Pit 2019 .... 103

Table 8-7 Proposed Monitoring Analytes for Active Discharge ............................................................................... 104

Table 9-1 Closure Domain Classification and Nominal Duration ............................................................................. 105

Table 9-2 Union Reefs North Underground Mine .................................................................................................... 108

Table 9-3 Haul Road ................................................................................................................................................. 113

Table 9-4 Prospect South Pit .................................................................................................................................... 116

Table 9-5 Prospect North Pit .................................................................................................................................... 119

Table 9-6 Dam A and Dam C .................................................................................................................................... 122

Table 9-7 Dam B ....................................................................................................................................................... 125

Table 9-8 Crosscourse Pit ......................................................................................................................................... 127

Table 9-9 Processing Operations .............................................................................................................................. 130

Table 9-10 Disturbance Areas and Required Rehabilitation Soil/Growth Medium ................................................... 134

Table 9-11 Unplanned Mine Closure Scenarios and Mitigation Measures ................................................................ 135

Table 9-12 Mine Closure Risks ................................................................................................................................... 136

Table 10-1 Workshop Attendees ............................................................................................................................... 139

Table 10-2 Union Reefs North Underground Mine Project – Likelihood Descriptors ................................................ 141

Table 10-3 Union Reefs North Underground Mine Project – Risk Matrix .................................................................. 141

Table 10-4 Union Reefs North Underground Mine Project – Risk Criteria................................................................. 142

Table 10-5 Union Reefs North Underground Mine Project – Certainty Descriptors .................................................. 142

Table 10-6 Summary of Residual Risk Ratings............................................................................................................ 143

Table 10-7 Union Reefs Underground Mine – Environmental Risk Assessment ........................................................ 145

Table 11-1 Adits within the URPA Potentially Providing Roosting Habitat ................................................................ 161

Table 11-2 Risk Assessment – Terrestrial Flora and Fauna ........................................................................................ 164

Table 11-3 MNES Significant Impact Criteria ............................................................................................................. 170

Table 11-4 Mitigation and Management Actions ...................................................................................................... 172

Table 12-1 Qualitative Risk - Hydrological Processes ................................................................................................. 185

Table 12-2 Summary of Potential Impacts and Relative Risks ................................................................................... 185

Table 13-1 URPA Water Quality Guideline Values ..................................................................................................... 196

vii NT Mining Operations Pty Ltd Union Reefs North Underground Mine Draft Environmental Impact Statement

Table 13-2 Risk Assessment – Inland Water Environmental Quality ......................................................................... 202

Table 13-3 Operational Stage Conceptual Site Model ............................................................................................... 204

Table 13-4 Conceptual Site Model Post Closure ........................................................................................................ 205

Table 14-1 Summary Statistics for Remote Camera Trapping Undertaken September 2019 .................................... 215

Table 14-2 Risk Assessment – Aquatic Ecosystems .................................................................................................... 216

Table 14-3 Reduction in Groundwater Availability in Each Mining Phase (Appendix H) ........................................... 217

Table 15-1 Eis Study Team ............................................................................................................................................. 1

Table 15-2 Spatial Coordinates of Union Reefs Project Area Footprint and Site Technical Studies .............................. 1

Table 15-3 Project Commitments .................................................................................................................................. 1

FIGURES

Figure 1-1 Residual Risk Rating (After additional control measures) ............................................................................ 8

Figure 3-1 Regional Location ....................................................................................................................................... 25

Figure 3-2 Land Tenure ............................................................................................................................................... 26

Figure 3-3 Mineral Titles.............................................................................................................................................. 27

Figure 4-1 URPA Mineralised Zones ............................................................................................................................ 31

Figure 4-2 URPA Layout ............................................................................................................................................... 32

Figure 4-3 Prospect Pit Proposed Layout .................................................................................................................... 33

Figure 4-4 NTMO other Mineral Titles Granted .......................................................................................................... 37

Figure 4-5 URPA ROM Pad........................................................................................................................................... 41

Figure 4-6 Union Reefs Free Milling Process Flowsheet Schematic ............................................................................ 43

Figure 4-7 Crosscourse Pit Cross Section and Tailings Deposition Schematic ............................................................. 45

Figure 4-8 Site Water Management Schematic .......................................................................................................... 46

Figure 4-9 Crosscourse Tailing Volume 3D Model ....................................................................................................... 48

Figure 4-10 URPA Explosives Bunker Area .................................................................................................................... 49

Figure 4-11 Temporary Waste Rock Stockpile Adjacent to the Portal Entrance at CHPA ............................................. 51

Figure 4-12 Underground Mine Schematic (Brown = Decline, Red = Ventilation, Blue = Level Access and Lode Cross

Cuts, Yellow = Ore Drives) .......................................................................................................................... 52

Figure 4-13 Indicative Diagram – Modified Avoca Stoping ........................................................................................... 52

Figure 4-14 Lady Alice Alternative Portal Location ....................................................................................................... 57

Figure 4-15 Lady Alice Pit Western Wall ....................................................................................................................... 58

Figure 4-16 Lady Alice Pit Eastern Wall ......................................................................................................................... 58

Figure 4-17 Box Cut to the East of Prospect Pit............................................................................................................. 59

Figure 7-1 Bioregional Context .................................................................................................................................... 72

Figure 7-2 URPA Monthly Rainfall 2013 to 2019 ......................................................................................................... 74

Figure 7-3 URPA Site Rainfall 2012 to 2019................................................................................................................. 74

Figure 7-4 URPA Evapotranspiration Data .................................................................................................................. 75

Figure 7-5 Pine Creek Orogen Stratigraphic Column (Hollis, 2012) ............................................................................. 76

viii NT Mining Operations Pty Ltd Union Reefs North Underground Mine Draft Environmental Impact Statement

Figure 7-6 URPA Local Geology ................................................................................................................................... 77

Figure 7-7 Regional Hydrology .................................................................................................................................... 79

Figure 7-8 Site Hydrology and Water Monitoring Locations ....................................................................................... 80

Figure 7-9 McKinlay River Declared Beneficial Use Area ............................................................................................ 81

Figure 7-10 Land Units................................................................................................................................................... 85

Figure 7-11 Vegetation .................................................................................................................................................. 86

Figure 8-1 Crosscourse Pit Groundwater Flux ............................................................................................................. 92

Figure 8-2 Prospect Pit Rainfall Annual Exceedance Probability (AEP) ....................................................................... 94

Figure 8-3 Prospect Pit Water Level 2018 to 2019 ...................................................................................................... 96

Figure 8-4 Crosscourse Pit Post Closure Water Balance ............................................................................................. 97

Figure 8-5 Proposed Discharge Location ..................................................................................................................... 99

Figure 8-6 Preliminary Water Treatment Circuit (Sample B) ..................................................................................... 102

Figure 9-1 URPA Closure Layout ................................................................................................................................ 106

Figure 9-2 Prospect Pit Proposed Closure Layout ..................................................................................................... 107

Figure 10-1 Risk Management Process (AS/NZS ISO 31000:2009) .............................................................................. 139

Figure 10-2 Initial Risk Rating (After Planned Control Measures) ............................................................................... 143

Figure 10-3 Residual Risk Rating (After Additional Control Measures) ....................................................................... 144

Figure 11-1 Pine Creek Region Ghost Bat Records ...................................................................................................... 160

Figure 11-2 Local Union Reef Project Area Ghost Bat Records ................................................................................... 163

Figure 12-1 Regional Groundwater Study Area ........................................................................................................... 179

Figure 12-2 Conceptual Hydrogeological Model Sketch Cross Section (after Turner, 1990) ...................................... 180

Figure 12-3 Conceptual Hydrogeological Model Sketch Long Section ........................................................................ 181

Figure 12-4 Conceptual Site Groundwater Flows with Crosscourse Pit Outflow Under Current Conditions (metres

AHD) ......................................................................................................................................................... 182

Figure 12-5 Conceptual Site Groundwater Flows with Crosscourse Pit Outflow Under High Pit Lake Conditions

(metres AHD) ............................................................................................................................................ 183

Figure 12-6 Surface Water Drainage ........................................................................................................................... 184

Figure 12-7 Peak Drawdown at End of Mining (mAHD) .............................................................................................. 188

Figure 12-8 Peak Extent of Drawdown One Year after Mining ................................................................................... 189

Figure 12-9 Proposed Groundwater Monitoring Locations ........................................................................................ 192

Figure 13-1 Water Monitoring Locations .................................................................................................................... 195

Figure 13-2 URPA surface Water Monitoring Schematic ............................................................................................ 199

Figure 13-3 Crosscourse Pit Post Closure Water Balance ........................................................................................... 207

Figure 14-1 Aquatic Ecosystem Sites Visited and Assessed in Detail .......................................................................... 212

Figure 14-2 Groundwater Dependent Ecosystems ..................................................................................................... 214

ix NT Mining Operations Pty Ltd Union Reefs North Underground Mine Draft Environmental Impact Statement

APPENDICES

Appendix A – Terms Of Reference for Preparation of an Environmental Impact Statement; Union Reefs North

Underground Mine

Appendix B – Cross Reference to TOR

Appendix C – EIS Authors

Appendix D – Spatial Coordinates of Project Footprint and Site Technical Studies

Appendix E – Commitments

Appendix F – Geochemical Characterisation of Waste Rock and Ore

Appendix G – Ghost Bat Technical Report

Appendix H – Groundwater Study

Appendix I – Geochemical Water Quality Modelling

Appendix J – Upper McKinlay River Groundwater Dependent Ecosystem Characterisation


1 EXECUTIVE SUMMARY Northern Territory Mining Operations Pty Ltd (NTMO) propose to develop the Union Reefs North Underground Mine

(the project) at the Union Reefs Project Area (URPA), a highly modified brownfield mine site that has historically been

subject to gold mining.

This Environmental Impact Statement is submitted to the Northern Territory (NT) Environment Protection Authority

(EPA) for assessment under the Northern Territory Environmental Assessment Act (EA Act). The Proposal (the project)

is a ‘controlled action’ under the Commonwealth Environment Protection Biodiversity Conservation Act (EPBC Act),

and will be assessed in accordance with the bilateral agreement between the Australian Government and the

Northern Territory Government. The controlling provisions are listed threatened species (Sections 18 and 18A).

1.1 Context

NTMO is a 100% owned by Kirkland Lake Gold (KLG), which is an Australian and Canadian gold mining and exploration

company. The NTMO operations are centred between the Township of Adelaide River to the north and Pine Creek to

the south. The URPA is located approximately 20 km northwest of the township of Pine Creek and 175 km southeast

of Darwin. Authorised activities at the URPA include ore processing and tailings storage. The Cosmo Howley Project

Area (CHPA), approximately 40 km to the south of the URPA, is an authorised mining and rehabilitation area, with ore

supplied to the Union Reefs processing plant at URPA. At each of its mineral leases, KLG operates in accordance with

the World Gold Council’s Responsible Gold Mining Principles.

The Company has spent approximately $36 M over the past ten years on products and services provided by local

companies based in Katherine, Pine Creek and Adelaide River; and over $300 M when including Palmerston and

Darwin businesses. In 2019, KLG will have invested around $150 M into its NT Operations.

The strategy over the next 5 years is to feed ROM ore to the URPA processing plant at a rate of over 2 million tonnes

per annum (tpa), from underground mines at the Cosmo Howley Project Area (CHPA), URPA and Pine Creek Project

Area (PCPA) to produce over 200,000 ounces of gold per year. This would the NT Operations a significant contributor

to the Northern Territory economy. Given the required level of exploration and growth development necessary to

achieve this plan, the Union Reefs North Underground Mine is critical to help fund this development program. It has

the potential to deliver over $10 M in Northern Territory royalties to the government each year (based on today’s gold

price of over $2,100/ounce of gold).

KLG currently employs around 400 people, and 60% of this workforce live locally. In the NTMO leadership team it is

over 80% locally based. This project will add an additional 50 - 80 jobs specifically for the underground mining

operation at URPA. As other operations begin at, for example, Pine Creek, these numbers will increase further.

An indicative schedule for the project is presented in Table 1-1.

TABLE 1-1 INDICATIVE PROJECT SCHEDULE

Time (Indicative) (2 to 3 Months) 2020 to 2022 2022 to 2023 2023 to 2028

Phase Mine development Mine operations Mine closure Post closure

Activities Construction activities

Mining and processing activities

Closure and rehabilitation activities

Monitoring activities


1.2 Site History

The Union Reefs area is an important historical gold mining centre that was once serviced by a train line (now

abandoned) that ran through the western sector of MLN1109. Gold was first discovered at Union Reefs in 1873. Some

2,300 small pits, shafts, adits and open cuts were developed to exploit the high-grade, lode style mineralisation that

were worked by Chinese tributers.

The period between 1994 and 2003 represents the most significant mining and processing period at the URPA. During

this period a total of around 20 million tonnes of ore was mined at an average grade of around 1.5 grams per tonne

(g/t) for a production total of just below 950,000 ounces.. Most of this material (around 90%) was mined from the

Crosscourse pit.

During the 1994 to 2003 operational period, 11 open pits were mined and two waste rock dumps (WRDs) constructed.

Processing tailings were deposited into the Old Tailings dam and Union North pit and Crosscourse pits (from 2002).

1.3 Project Description

The underground mine will be accessed via a portal (entry) and decline developed from within the existing Prospect

pit. Prospect pit is divided into two sections, north and south which each have a pit lake. Prospect north and south

pit(s) will be completely dewatered prior to portal construction, with only a small dewatering sump remaining during

the operational phase of the project. The underground mine will be accessed via a portal and decline developed from

within the existing Prospect north pit. Prospect pit (south) will be used to store waste rock that will then be returned

underground and used as backfill during mining operations. This is the same model for waste rock management as

used at the Cosmo Deeps mine. Ore will be trucked directly to the existing Run of Mine (ROM) pad, and then fed into

the existing processing plant crusher using the existing infrastructure and equipment. Tailings will be deposited in the

existing Crosscourse pit Tailings Storage Facility.

Key project components are summaries in Table 1-2.

TABLE 1-2 KEY PROJECT COMPONENTS

Element Proposed

Production Estimates

Mining rate 92,000 tonnes/annum

Ore 280,000 tonnes (t)

Waste rock 291,000 t of which 241,000 t will be returned underground

Tailings solids 276,000 t

Production 39,232 gold ounces

Underground Mine

Portal location Eastern wall of the existing Prospect pit located at 177.5 metres Australian Height Datum (mAHD).

Mine depth 220 m below ground surface.

Portal bench Existing non-mineralised, oxide stockpile within the Prospect pit will provide approximately 7,000 to 12,000 t of material to construct/upgrade portal bench in Prospect pit prior to mine development.

Mining method The planned underground mining method is a combination of up-hole benching and Avoca stopping, in a three-lift, bottom-up sequence. This method requires the decline


Element Proposed

to be advanced at least three levels in depth prior to ore production commencing. The Cosmo underground development has been mined in this same way.

Materials handling

Ore will be trucked directly from the portal to the existing Run Of Mine (ROM) pad, and then fed into the processing plant crusher using the existing infrastructure and equipment.

Waste rock will be stored in the Prospect south pit, prior to progressive reuse underground to backfill the stopes, i.e. stopes will be backfilled with waste rock and cement rock fill.

Existing Infrastructure

Tailings Storage Facility (TSF)

The use of Crosscourse pit for tailings deposition is consistent with the current authorisation # 0539-03. The Crosscourse pit was mined from 1993 to 2002 when more than 80 Million tonnes (Mt) of material was removed to a depth of 265 m. The pit has been utilised as the TSF since August 2002.

Crosscourse pit currently holds 10,190 ML tailings and 12,605 ML water. Processing operations in 2021 to 2023 will contribute approximately 1,600 ML tailings and 2,400 ML water to Crosscourse pit

Processing plant

The URPA processing plant is located approximately 1 km from the proposed Prospect underground mine and operates under Authorisation # 0539-03.

The processing plant recovers gold by gravity concentration and Carbon In Leach (CIL) technology. It has a maximum capacity of 2 Million tonnes per annum (Mtpa) and can be operated efficiently at a lower throughput rate with the use of only one of the ball mill circuits.

Since the URPA processing plant was commissioned in 1993, it has operated for 23 out of 27 years. A total 30.3 Mt of ore has been processed at an average grade of 1.7 g/t, producing more than 1.5 million oz of gold.

The mill has performed well, with no significant issues noted. It is still in good condition and suitable for future production.

Hazardous materials storage

Existing (Authorisation # 0539-03)

Haul road Existing haul road to ROM pad will require road extension of approximately 400 m into Prospect pit.

Power Existing power lines and substation will be extended to create additional capacity 9 to 12 Megawatt (MW).

Site clearing The URPA currently contains disturbed area of 495 hectare (ha) with 354 ha rehabilitated/revegetated. Site clearing for the project will be approximately 1 ha.

Mining maintenance The existing fuel bay, wash-down area and minor repairs workshop will be used for refuelling, and repairs on mining machinery.

Existing URPA laydown and landfill areas.

Mining administration The existing URPA administration area

Water dams

This project will utilise water from Crosscourse pit and from Dam C. Existing water storage in Prospect pit will be pumped to Crosscourse pit prior to project construction.


Element Proposed

Water

Dewatering during mine development

100 MegaLitres (ML) dewatered from Prospect pit(s) to Crosscourse pit over a period of 2-3 weeks

Water use during mine operation

The underground mine is expected to use around 1.5 to 2 L/s for underground drilling and dust suppression, equivalent to 47 to 63 ML/year. This water will be sourced from Dam C and pumped underground via two 30,000 L water tanks installed adjacent to the Prospect pit.

Underground wastewater and groundwater ingress (7 to 18 L/s) will also be pumped into Prospect North pit. Prospect North pit water storage will be dewatered regularly into Crosscourse pit. Prospect North pit water level will be maintained in a dewatered state to avoid flooding risk of the portal.

Dam C

Dam C is used as a raw water source and will provide supplementary water for the processing plant. Dam C will also provide water for use in the underground mining operation.

Dam C is situated in the northeast of the URPA. It receives surface rainfall and catchment runoff from the hilly ridges to the east of the dam. The total catchment area of Dam C is 173 ha.

Dam B

Dam B acts as a sediment trap and settling pond for overflow runoff from URPA fuel bay and wash-down areas.

Any overflow from Dam B flows into sediment trap 3 (located between Dam B and the McKinlay River). Water quality in this area is monitored.

Other Infrastructure

Explosive and detonator storage

40 t and 25 kg respectively

Blasting for development and production will be required for the underground mine. Development blasting relates to the excavation of material required to gain access to the orebody and to provide space for underground infrastructure. Generally, this material is waste rock although there is some development ore recovered.

Production blasting is manipulated electronically and designed to optimise fragmentation and minimise dilution of the ore.

Diesel consumption 720,000 L/year

Annual greenhouse gas emissions

9,639 Carbon Dioxide Equivalence (t-CO2-e)

Workforce

Construction 12 staff

Operations 80 staff


1.4 Alternatives

The Union Reefs North Underground Mine has been designed to target the Prospect claim deposit. Given the location

of Ghost bat roosting habitat (adits) within Prospect Pit, NTMO did consider other alternatives including:

Establishing the portal location within the Lady Alice Pit, or

Establishing a box cut operation to the east of the proposed decline location.

Both of these alternative locations were tested and then abandoned for geotechnical, economic, safety and/or other

reasons that are described in more detail in the draft EIS.

1.5 Mine Water Management

A site water balance has been prepared for the operational and post closure phase of the project. The site water

balance considers all inflows and outflows of the water management features, and is based on real data including the

proposed water production rate from dewatering, process water requirements, and average annual rainfall from the

historical record. The URPA processing tonnes for 2020 to 2024, including processing tonnes from the CHPA, have

been included in this site water balance. The Underground Mine will contribute processing tonnes in 2021 to 2023.

The direct rainfall, catchment runoff and evaporation have been estimated based on the catchment area of Prospect

pit North and South (15.7 ha), catchment area and surface area of Crosscourse pit (173 ha and 27 ha respectively) and

the annual rainfall and evaporation depths. The net balance of direct rainfall, catchment runoff and evaporation is

estimated to be 455 ML on average, indicating that the site is hydrologically in water excess.

Operational requirements of underground operations and some components of the processing plant require a water

with a relatively high quality that is not available from the existing water storage in Crosscourse pit. This water will be

sourced from Dam C, which has a relatively large catchment and is expected to readily supply the required water

demand up to 299 ML/year.

The underground workings are expected to intercept groundwater at a rate of 18 L/s (i.e. the extreme high case

predicted by AQ2, 2018) that will be required to be dewatered to Prospect pit and from there pumped to Crosscourse

pit for the safe operation of the mine

The net groundwater flux into or out of Crosscourse pit depends on the water level elevation in the pit. The

relationship was estimated using a groundwater model. Since the completion of mining in Crosscourse pit, it has so far

been a groundwater sink, with inflows estimated to be 85 ML/year in early 2019. However if the water level in

Crosscourse pit rises, the pit has the potential to become a groundwater source. Crosscourse pit is anticipated to shift

from being a net groundwater sink to a net groundwater source is at a water level between 173-176 m AHD.

This balance is a fundamental property of the climate, hydrogeology and geometry of Crosscourse pit and

independent of existing and proposed operations. As is typical for open cut pits in tropical Northern Territory, the net

surface balance is expected to reach equilibrium with groundwater seepage out at about 186 m AHD, just below the

surface water spill level of 189 mAHD. In an above average rainfall year, the net surface water balance is well in excess

of the maximum groundwater seepage outflow rate. Overall, this indicates that in the long term and without water

management, Crosscourse pit is expected to fill and remain near to the spill level.

The timing of the increase in water levels will, to some extent, be hastened by aspects of the project including:

Dewatering of Prospect pit and subsequent dewatering of the underground workings.

Displacement of water by deposition of tailings in Crosscourse pit.


Without additional water management actions, the effect of this water excess would be increasing water surface

elevations in Crosscourse pit, resulting in:

Reduction in the available water storage capacity in Crosscourse pit to contain extreme floods.

Groundwater seepage from Crosscourse pit that is expected to report to downstream water management

features and watercourses, including the McKinley River.

The potential impacts will be mitigated by a range of measures, including extraction (recycle to the processing plant)

and treatment and discharge of water from Crosscourse pit under a Waste Discharge Licence (WDL).

1.6 Mine Closure

The Underground Mine project is proposed within the larger URPA. Details for the broader mine closure of the URPA

are contained in the URPA Mine Closure Plan (2015). The draft EIS commits to updating an integrated URPA Mine

Closure Plan.

The URPA is a highly modified, brownfields mining area that consists of numerous mine features or Closure Domains

unrelated to this draft EIS. Approximately 495 ha at URPA has been disturbed historically, of which 355 ha has been

rehabilitated/revegetated.

Mine features (Closure Domains) that are specifically and primarily associated with the underground mine include:

Primary: Mine features primarily associated with the underground mine (closure aspects addressed in this

EIS) – e.g. the underground mine

Secondary: Active and ongoing URPA mine features that interact with the project, but both pre-date and to

operate beyond the period of the project (discussed in this EIS but closure aspects addressed in the broader

URPA Mine Closure Plan) – e.g. the haul road, Prospect pit, Crosscourse pit, Dam C, and the Processing plant.

Tertiary: URPA mine features that do not interact with the project (not discussed in this EIS but closure

aspects addressed in the broader URPA Mine Closure Plan).

1.7 Existing Environment

URPA lies within the Pine Creek bioregion, which is characterised by the highly mineralised Pine Creek geosyncline.

The local geology of the URPA is dominated by the northwest striking Pine Creek Shear Zone. This zone is a 300 m

wide corridor of folded and sheared metasediments that largely comprises the Burrell Creek Formation and

structurally generated inliers of the Mount Bonnie Formation. The aquifer system is an elongated north-south

trending fractured and weathered rock system associated with the Union Reefs shear zone. It is around 300 to 500 m

wide and extends over many km to the north and south (Hall, 2018).

Land tenure in the Pine Creek bioregion comprises 41% aboriginal freehold land, 26% pastoral land. Approximately

42% of the bioregion comprises National Parks or other protected areas (Baker et al, 2005).

The landscape is described as stony foothills and is dominated by tall open forests dominated typically by Darwin

Woollybutt Eucalptus miniata and Darwin Stringybark Eucalyptus tetradonta (Baker et al, 2005). The URPA lies within

the Brock’s Creek Ridge land system, mapped by Christian & Stewart, 1946. This system occurs extensively in the

Katherine to Darwin Region, covering about 4,000 km2. It comprises sharp north-south running ridges and hills with

small, alluvial flats. It is described as elevated backbone country (Christian & Stewart (1946) and is characterised by

relatively steep slopes, active erosion and skeletal gravelly sandy loam soils. Flooding during the wet season is

confined to the narrow flats. Alluvial flats contain heavier soils that contain higher levels of clay and silt than soils on

erosional landscapes.

The URPA is situated in the upper reaches of the McKinlay River Catchment Area, at an elevation of 230 mAHD. It is

located on pastoral land that has carried cattle at low stocking rates, due to the steep slopes and skeletal soils. Given

the highly modified soils and vegetation resulting from decades of mining activity, the habitat within the URPA is, on

the whole, sub-optimal for breeding and foraging for fauna species.


The climate is broadly classified as tropical monsoonal. It is characterised by seasonal shifting of the prevailing winds

and two distinct seasons, the dry and wet season, with two subsidiary, transitional periods between them. Most

rainfall occurs in the wet season, January and February are the wettest months. Rainfall intensities are high, which is

typical for areas located in the tropical north of Australia. The average annual rainfall for Pine Creek is 1,141 mm.

Evapotranspiration is at an average of 5.68 mm per day.

Stream flows are highly variable and extremely responsive to rainfall, particularly in the upper reaches of the

catchment. Streamflow usually commences in late November (start/stop flows), reaches peak levels between

February and March and generally ceases flow during April to May.

The URPA is located within the upper Mary River Catchment, an area of approximately 5,600 Km2 south of the Arnhem

Highway including the Pine Creek and south-western Kakadu regions. The upper catchment is characterised by hilly

terrain before levelling out where the McKinlay and Mary River systems form extensive alluvial plains further north

(Napier & Steen, 2002).

The headwaters of the McKinlay River flow northwards along the western edge of the URPA lease and then into the

Mary River some 85 km downstream. The Mary River flows year round, but many of its catchment tributaries,

including the McKinlay River, are ephemeral i.e. flowing only during the wet season.

The two main McKinlay River sub-catchments that drain from the URPA include Esmeralda Creek to the south and

Wellington Creek to the north (Figure 7 8). A Beneficial Use Declaration to maintain the health of aquatic ecosystems

(Category 4 – Environment) has been set for the upper McKinlay River to the west of the URPA.

1.8 Risk Assessment

The NT EPA identified four key environmental factors that may be significantly impacted by the project. The

environmental risk assessment identified 31 risk events, which had the potential to impacts on key environmental

factors. These are identified in Table 1-3.

TABLE 1-3 KEY ENVIRONMENTAL FACTORS

Theme Environmental

Factor Objective

No of risk

events

identified

Land Terrestrial

flora and fauna

Protect the Northern Territory's flora and fauna so that biological diversity and ecological integrity are maintained.

15

Water Hydrological processes

Maintain the hydrological regimes of groundwater and surface water so that environmental values are protected.

2

Inland water environmental quality

Maintain the quality of groundwater and surface water so that environmental values including ecological health, land uses, and the welfare and amenity of people are protected.

12

Aquatic ecosystems

Protect the aquatic ecosystems to maintain the biological diversity of flora and fauna and the ecological functions they perform.

2

No risks were assessed to be Extreme at either the initial or residual risk stage. Of the 31 risks, 10 were ultimately

rated as Medium, and 21 as Low. Five potential events were given an initial risk rating of High, and each of these

reduced to Medium with additional controls. These potential events included four related to potential impacts on

Ghost bats (terrestrial flora and fauna), and one event relating to inland water environmental quality.


Five potential events were given an initial risk rating of Medium, and retained a Medium risk rating even with the

inclusion of additional controls. These included the effects on groundwater availability at the McKinlay River

associated with groundwater drawdown during mining (hydrological processes). The remaining risks were rated as

Medium, and then reduced to Low, with the application of additional controls; or were rated as Low in the initial risk

assessment stage.

The residual risks are presented in Figure 1-1.

FIGURE 1-1 RESIDUAL RISK RATING (AFTER ADDITIONAL CONTROL MEASURES)

1.9 Terrestrial Flora and Fauna

The Terms of Reference for the Preparation of an Environmental Impact Statement (TOR) provide a series of

information requirements specifically related to the distribution and ecology and conservation of the Ghost bat

(Macroderma gigas) at the URPA and in the wider region.

The Ghost bat is currently listed as ‘Vulnerable’ under the Commonwealth EPBC Act 1999 and ‘Near Threatened’

under the Territory Parks and Wildlife Conservation Act.

Existing data estimates a regional Ghost bat population centred on Pine Creek and including Spring Hill to the north

and Claravale Station to the south at between 570 and 1,132 individuals. This potentially represents 8.1 % to 12.5 % of

the national (global) Ghost bat population. The Union Reefs local population potentially represents 2.6 % of the upper

estimated regional Ghost bat population, and 0.3 % of the upper estimated national (global) Ghost bat population.

The Ghost bat has a history of decline across its broad Australian distribution. In the past 50 years there is evidence of

declines in natural roost caves, and the loss of several roost sites due to mining activity in Queensland and the

Northern Territory, including within the Pine Creek region. Losses of roost sites in the past decade were an important

consideration in the listing of the Ghost bat as Vulnerable under the EPBC Act 1999.

Adits in the URPA have been occupied at least since their discovery in October 1987, with periods where disturbance

and mining resulted in declines in their numbers, and shifts to alternative roost locations. A colony utilising the

Kohinoor adit in Pine Creek have been present since its discovery in the late 1950s, a period of approximately 60 years

of constant occupancy. The longevity of other regional roosts is not well known, however these sites are likely to have

been occupied by Ghost bats over extended periods.

The continued occupation of sites within the URPA and Pine Creek region, across periods of anthropogenic

disturbance, is indicative of the high level of importance of these roosts in the landscape. The high level of sensitivity

of ghost bats to disturbance suggests that if alternative suitable sites were available, stronghold roosts at Pine Creek

and Union Reefs would very likely be abandoned, with individuals moving to less disturbed sites. Adits in the URPA are

described in Table 1-4.


TABLE 1-4 URPA ADIT LOCATIONS

Adit Name (Adit Location)

Est Depth (m)

Entrance Width x

Height (m)

Ghost Bat No.

Min - Max

Comments on Ghost Bat Use and Habitat Suitability

Union North adit (Union North pit)

62 1 x 1.5 20 - 30

Internal structures unknown—will be further inspected during Phase 1 of the project.

Used by 20 to 30 Ghost bats as a diurnal roost on a regular basis across the wet and dry season.

Bats tend to move to the OK adit periodically during the wet season and use the Union North adit in the dry season.

OK adit (Prospect pit)

18 1.5 x 1.2 20 - 30

Internal structure determined using pipe inspection camera and internal investigation by KLG staff.

The end of the southern drive is used by 20 to 30 Ghost bats as a diurnal roost during the wet season. These bats switch to the Union North Adit in the dry season.

Prospect adit (Prospect pit)

8 0.4 x 0.4 1 - 1

Short remnant of a formerly larger adit, with only a small opening allowing access for bats. Thought to have been exposed by rock fall during 2018.

Used only by individual bats as a nocturnal feeding site and occasionally as a diurnal roost in 2019.

Lady Alice adit (East of Union

North pit) 30 0.4 x 0.2 0 - 0

Ghost bats not detected in the internal structure. The entrance has been blocked except for a narrow opening. The internal structure remains open and intersects a shaft that exits to the surface approximately 30 m to the east.

Re‐opening and modifying the structure is Action 4 in the Action Plan (Armstrong et al. 2019b).

The activities throughout mine development and operation, which could directly impact the URPA Ghost bat colony

include the following:

Noise from site setup and construction of new surface infrastructure required to support the proposed

underground mine operation.

Noise from mining operations including drilling and underground blasting.

Vibration from mining operations including drilling and underground blasting.

Damage to roost sites including internal blockages and collapse.

Temporary (two years) closure of the OK adit and Prospect adit during mine development and operations.

Introduction or increase in people to an area.

The overall strategy to manage and mitigate potential impacts to the ghost bat colony is contained in an action plan

that is outlined below.


TABLE 1-5 GHOST BAT POTENTIAL IMPACTS AND MITIGATION MEASURES

Action Timing* Threat Factor and Effectiveness

Action 1 - OK Adit Exclusion

Exclude the Ghost bat from the OK adit based on a planned methodology and timing. [Avoidance and mitigation/ minimisation].

Phase 2 Threat Factor: Habitat loss.

Effectiveness: Closure of the adit will be fully effective for diverting Ghost bat usage of the OK adit to the Union North adit and other alternatives. This avoids the significant impacts of ongoing daytime disturbances at the OK adit including vibration and noise causing day time exodus.

Baseline monitoring has established that Ghost bats already regularly use the Union North adit, and there is evidence they move in and out of URPA.

Action 2 - Survey of Internal Adit Structures

Characterise the internal dimensions of the OK adit and Union North adit, and the position of Ghost bat roost areas within. [Research to support minimisation].

Phase 1 Threat Factor: Disturbance to roost sites, breeding sites.

Effectiveness: The Union North adit and Lady Alice adit will be surveyed at night by trained and experienced personnel with appropriate equipment. The aim is to determine depth and extent, stability, the presence of crosscuts/stopes/shafts/etc. and the position of guano piles indicating roost position.

Action 3 - Construct Artificial Habitats

Create several artificial roosting habitats in the URPA, for both contingencies and additional capacity, and evaluate their success. [Both mitigation/ minimisation and offset].


Effectiveness: The creation of artificial habitat for the Ghost bat in Australia, as well as species such as the orange diamond-faced bat, is experimental, and therefore the effectiveness is still unknown.

The design is to provide several alternative horizontal tunnel habitats, not only to replace the OK adit, but to provide further capacity via multiple new roosting options within the URPA. The design will include:

Dimensions likely to provide conditions suitable for Ghost

bat roosting based on extensive experience of other roost

sites.

Confirmation of the suitability of the microclimate that will

form within through modelling with computational fluid

dynamics.

Action 4 - Re-open Lady Alice Adit

Re-open and rehabilitate the Lady Alice adit so that it is suitable for Ghost bat occupancy. [Mitigation/ minimisation and offset].


Effectiveness: The Ghost bat, and other cave-dwelling bat species readily move into underground mines following the cessation of mining, though over what timescale is unknown. Lady Alice adit will be opened and modified (block an open shaft that intersects the adit midway) to ensure that it retains a suitable warm, humid microclimate. This modification is anticipated to attract bats to roost within when access to the OK adit is removed.

The species has already been recorded near the entrance, current data indicates it has a similar depth to the OK adit, and the entrance portal is only around 150 m from that of the Union North adit. Combined with management that prevents casual visitation by people, there is confidence that it could become an alternative to the OK adit relatively quickly.



Action 5 - Manage Union North Adit

Manage the Union North adit during the period of mining to exclude visitation from mining personnel. [Mitigation/ minimisation].


Effectiveness: Managing the Union North adit is a core part of the strategy to manage the colony of Ghost bats in the Union Reefs area during the proposed mining period, given that this adit will be the colony’s closest known suitable diurnal roost. Managing Union North adit, Lady Alice adit and new artificial roosts will be a priority. Measures would include protecting roosts from disturbance and educating staff regarding access and disturbance in the vicinity of Ghost bat roosts and maintaining structural integrity and accessibility.

Action 6 - Manage Pine Creek and Spring Hill Ghost bat sites

Implement management measures at the Koohinoor adit, Pine Creek, to protect the Ghost bat roost. [Mitigation/ minimisation].

Phase 3 Threat factor: Disturbance to roost sites, breeding sites.

Effectiveness: The Kohinoor adit is currently protected from human intrusion by a low stock fence without barbed wire. If ownership of the Spring Hill mine changes to KLG in the future, protection measures will be improved. Measures would include discouraging casual entry by the public, such as signage, diverting attention away from the site and public education.

Action 7 - Monitoring Program

Continued monitoring of Ghost bat presence, activity levels and colony size at Union North adit, potentially Lady Alice adit, new artificial roost habitats, and other key regional sites (Pine Creek; Spring Hill; any newly discovered caves of significance surrounding the URPA). [Mitigation/ minimisation].

Phase 1

Phase 2

Phase 3

Phase 4

Threat Factor: Disturbance to roost sites, breeding sites.

Effectiveness: Continued monitoring by specialist ecologists to build on the surveys conducted since August 2018. Monitoring will collect information on bat presence and usage levels which is critical information on understanding Ghost bat colony size. Methods will include:

New video recording technology (e.g. thermal tracking software) able to make multiple scheduled recordings over

consecutive nights to collect.

Analysis of acoustic datasets.

Conducted by experienced analysts with advanced recording and analytical systems.

In the event of a collapse affecting the entrance portal, material blocking the entrance of the Union North adit will be removed. Subsequently, and if safe for human entry, the effect on Ghost bats will be evaluated by inspecting the interior for individuals that may have perished. These will be reported to DENR, and any carcasses submitted to the MAGNT.

Action 8 – Facilitate Post-Mining Occupation of Mine Workings by Ghost Bats

Provide a portion of the new mine for Ghost bat occupancy once mining has been completed and evaluate its success. [Rehabilitation or offset].


Effectiveness: Ghost bats and other cave-dwelling species of bat in northern Australia are well known for their tendency to occupy underground mine workings after mining activity has finished. As indicated by the current use of adits within the URPAs.

At project completion, the new underground structures will be deeper and more complex than existing adits, and potentially provide suitably warm and humid microclimates. Part of such a structure will be made available to Ghost bats following the cessation of mining. This will provide long term potential for Ghost bat numbers to build up to eventually become more important for the regional population than the Kohinoor adit.



This strategy has a very high potential to become one of the most effective and significant actions.

Action 9 - Cave and Mine Roost Survey

Conduct field surveys for Ghost bat diurnal roosts in natural caves in the hills surrounding the URPA. [Research to support minimisation].


Effectiveness: Confirmation of occupied natural caves in the surrounding hills will give reassurance that there are alternative roost sites very close to sites that might be subject to mining-related disturbance.

The methods for non-invasive discovery and monitoring of Ghost bats are effective if applied correctly. Methods described for Action 7 will be used. These methods do not present a disturbance to Ghost bats that might roost within a structure, especially if investigators do not enter and attempt to minimise noise when deploying equipment.

Action 10 - Genetic Study

Investigate the connectedness of Ghost bat colonies in the region using an advanced genetic method based on genome-scale DNA sequencing. [Research to support minimisation].


Effectiveness: An analysis of physical and genetic connectedness among colonies in other parts of the region, will be carried out. Ghost bats will be lured into harp and mist net traps (positioned close to, but not adjacent to roost sites) by acoustic playbacks, where fresh DNA will be collected from trapped individuals via ethically approved methods. These samples will be combined with those available from previous studies and analysed using a genome scale, DNA sequencing process called ‘DArTseq’. This will provide information for the movement and genetic similarity of individuals among colonies within the region.

Action 11 - Support Ghost Bat Research

Provide support for further academic research. This would include coordinating the development of a Recovery Plan, which is required under the EPBC Act 1999, but has not yet been developed. [Research to support overall management].

Phase 3

Threat Factor: Relevant to most threat factors listed in Threatened Species Scientific Committee (2016).

Effectiveness: There is still little understood about the timing of their breeding cycles in different populations, their acoustic ecology and the importance of water bodies for hydration with questions still remaining about the meaning of call types and interpretation in the context of environmental impact assessments.

Providing funding for a postdoctoral research program will add significant knowledge to the public sphere to assess threats and manage future impacts to Ghost bats populations.

*Timing includes:

Phase 1: Before new underground mine construction.

Phase 2: Exclusion phase, immediately prior to site works in the Prospect pit.

Phase 3: During mining.

Phase 4: After mining has been completed.


The assessment is based on historic data, surveys conducted in 2018 and 2019 and a risk assessment of potential

impacts. There remains a residual risk of unknown, unpredictable or irreversible impacts.

Closure of the OK adit is a mitigation measure designed to ‘avoid’ ongoing impact on the colony (associated with day

time exodus of the adit), through reducing the proximity of Ghost bats to planned mining operations such as

underground blasting. If the project is to proceed, there is no possible scenario where an avoidance or no impact

pathway could be implemented without temporary closure of this adit.

The proposed mitigation and management measures have reduced residual risk by increasing the possible number of

roost sites within the URPA (modification of the Lady Alice adit; building several artificial roost structures), and

extending proactive management to regional colonies that are predicted to be within the nightly flight range of Ghost

bats in the URPA (Pine Creek, possibly Spring Hill).

For this reason it is considered very unlikely that the closure of the OK adit would lead to the total loss of the URPA

colony, estimated at up to 30 individuals. However, in the event that this was to occur, the region would have lost less

than three per cent of the known regional population (at least 1,100 individuals), and less than 0.3 per cent of the

global population (less than 10,000). This total colony loss is unlikely to occur considering the mitigation and

management strategies detailed in Section 11.4, but remains possible in the following events:

Union North adit collapse while the colony is roosting (causing direct mortality).

Disturbance at Union North adit (mining activity or human disturbance) causing day time exodus leading to

mortality.

The residual risk of this occurring is Medium, and the likelihood is rare.

The primary Ghost bat management objective is to maintain the availability, protection and suitability of underground

roost structures in the URPA, to allow Ghost bats to occupy the area permanently as well as to facilitate movement

and dispersal of the regional population between Pine Creek and Spring Hill. These actions, in addition to opening new

adits within the URPA during and post mining and improving the quality of Pine Creek roosting sites, are expected to

provide a net benefit to the regional population by increasing the quantity and quality of diurnal roosting habitat

available to Ghost bats in the long term.

Additionally, it is worth noting that the historical mines in the Union Reefs area and in the region are greater than 100

years old, and over time natural collapse and infill is likely to exclude ghost bats from these sites, and potentially kill

large numbers of bats if they are trapped by sudden collapses (Appendix G). Should mining stop, the monitoring and

maintenance of historic adits would cease or become less frequent, and these sites would eventually become

unsuitable as roost sites.

There are currently no external (i.e. non‐mining, government) programs designed to monitor or protect historical

mine workings in the Northern Territory. Investment in mining is very likely to bring a net improvement in the

situation of Ghost bats in the Union Reefs area, and the region generally.

1.10 Hydrological Processes

The primary ground and surface water environmental values are discharge via seepage and surface flow to the

McKinlay River and its riparian and aquatic ecosystems. Groundwater also has value for extraction, notably at Pine

Creek borefield and the nearest third-party independent bore, being RN036105 (licenced to Territory Iron).

Hydrological connectivity is assumed between groundwater aquifers and existing pits, ponds and dams. This is

because historical workings have mined below the water table and existing pits, dams and ponds are highly likely to be

unlined and are in direct hydrological connection with the underlying/intersecting fractured rock aquifer.

Dewatering the Prospect pits and underground mine results in groundwater drawdown, and therefore, a potential

change to groundwater availability, i.e. at the McKinlay River. Drawdowns and groundwater availability are also linked

to surface water management and in this case, the management of the Crosscourse pit.


Scenario 1 – Crosscourse pit is maintained at its current low head water level (173 mAHD ) during the project

i.e. dewatering to Crosscourse pit and water treatment and discharge under a WDL.

Scenario 2 – Crosscourse pit water level is not managed during mine dewatering during construction and

mine operation, and therefore dewatering to Crosscourse pit results in water level increase to high head level

188 mAHD.

The largest groundwater drawdown is likely to occur if water levels in the Crosscourse pit are managed at

approximately current conditions (Figure 12 4). The modelled impact on the groundwater flow regime of dewatering

of the Prospect pit and underground mine has been demonstrated numerically under these conditions. Likewise, the

largest potential for drawdown impact on water levels within other water bodies, including pit lakes, is if the

Crosscourse pit is managed at approximately current conditions, rather than unmanaged at high levels.

In contrast, the largest potential for groundwater contamination is when Crosscourse pit is left unmanaged and

allowed to fill to high pit lake conditions. Under high pit lake conditions, impact from drawdown is masked by the

surface water inputs to the groundwater regime.

Table 1-6 describes the potential impacts associated with mine dewatering under different conditions.

TABLE 1-6 POTENTIAL IMPACTS ASSOCIATED WITH MINE DEWATERING

Potential Impact Crosscourse Pit Lake

Levels

Relative

Risk of Impact

Groundwater available for discharging to the McKinlay River and its

riparian ecosystem. Scenario 1 Higher


riparian ecosystem. Scenario 2 Lower

Drawdown impact on water levels within other water bodies

including pit lakes, and subsequent water quality changes. Scenario 1 Higher


including pit lakes, and subsequent water quality changes. Scenario 2 Lower

Groundwater available for nearest bore RN036105 (Territory Iron). Scenario 1 Higher

Groundwater available for nearest bore RN036105 (Territory Iron). Scenario 2 Lower

Groundwater available for Pine Creek. Scenario 1 Negligible


Outward flow of water of poor quality leaving Crosscourse pit as

groundwater. Scenario 1 Lower


groundwater. Scenario 2 Higher

The groundwater modelling demonstrated that:

There would be no change to the available groundwater or groundwater levels at the Pine Creek Borefield,

Pine Creek and Copperfield Creek Catchments associated with the proposed underground mining.

The groundwater level at the closest potential groundwater user, Territory Iron bore (RN036105), is peaks at

0.08 m.


Over the whole of the McKinlay River catchment the modelling demonstrates the underground mining is

likely to result in a maximum of a 3% change in groundwater available for both discharge to ephemeral pools

and available for riparian evapotranspiration. This decreases to less than 1% change in six years after mining

and is likely to approach 0% after a decade.

o The majority (approximately 60%) of this loss of groundwater availability occurs along the two short

sections closest to the underground mining. The maximum percentage change in this groundwater

availability along these sections is 17% and 12% respectively. These changes decrease to less than

4% and 2% respectively in six years after mining and as is likely to approach 0% after a decade.

The post underground mining groundwater regime in the McKinlay River is highly likely to mimic the pre-

underground mining groundwater regime.

The post underground mining groundwater regime at the ponds and dams is highly likely to mimic the pre-


A Water Management Plan will be produced prior to mining. The monitoring program will track:

The extent of the depressurisation zone and its effect during dewatering of the Prospect pits and

underground mine.

The extent of groundwater drawdown, on surface and groundwater flows as well as on other water bodies

within and adjacent to the proposal, from dewatering the Prospect pits and underground mine.

Any impact on beneficial uses of groundwater (notably the McKinlay River as a whole, the McKinlay River at

key sites, the Pine Creek borefield and the closest neighbouring groundwater bore (RN036105).

In the unlikely event groundwater drawdown mitigation is considered necessary, the large clean water stores on site

(i.e. Dams A and C) could be considered as temporary mitigation for:

Rapid deliberate flooding of the underground mine.

One off, out of season flush discharge to the McKinlay River (pending water quality results).

Target irrigation along the McKinlay River

As a substitute for groundwater extraction at neighbouring bores.

It is recognised that all of these would require significant multidisciplinary consideration and regulatory approval.

Management of the Crosscourse pit water levels is considered a likely mitigation measure for the management of

potential groundwater contamination. Management of pit water levels could be achieved by managing:

Tailings inputs

Mine water re-use

Treatment and discharge

It is recognised that discharge will require significant multidisciplinary consideration and regulatory approval, i.e. a

Waste Discharge Licence (WDL).

1.11 Inland Water Environmental Quality

The environmental objective for inland water environmental quality is to maintain the quality of groundwater and

surface water so that environmental values including ecological health, land uses and the welfare and amenity of

people are protected.

The McKinlay River catchment ecosystem condition determined from local reference data indicates that surface water

is of slight to moderate disturbance. Modification of water quality is due to the long history of anthropogenic activities

at URPA, alongside the typical tropical ecosystem characteristics, such as the wet-dry climate. The ANZECC &

ARMCANZ (2000) Guidelines set varying levels of ecosystem protection derived from local reference data. Guideline

values are used by NTMO as an early warning mechanism to provide insight into potential adverse water quality

changes. They are used to trigger surface water management actions if water quality sampling indicates on-going

values outside of the guideline values and/or the long-term site data range.


NTMO has adopted the 95% ecosystem protection values for environmental protection at surface water monitoring

point URSW08, i.e. downstream at the end of the mixing zone. This is with the exception of aluminium and zinc, which

have derived site specific trigger values (SSTVs) using ANZECC & ARMCANZ (2000) guidelines being the 80th percentile

of the historic dataset. This is due to the local mineralisation, and therefore naturally elevated concentrations of both

species. Livestock drinking water guidelines (SWG) are also considered given the downstream declared beneficial use.

The water quality monitoring program conducted by NTMO at the URPA includes sampling locations on the McKinlay

River, a control upstream from the site (URSW09) and one which serves as a compliance point downstream from the

site (URSW08). Comparison of results from analysis of water sampled at these two sites allows assessment of the

impact of the URPA on the quality of water in the McKinlay River downstream of the site over the past ten wet

seasons, i.e. 2010 to 2019.

Long term site data indicates:

elevated downstream concentrations of sulphate, calcium and magnesium, i.e. historic mining structures are

a source of NMD, but EC within guideline values indicating the impact is small

Al, As, Mn and Zn were detected in most samples across the nine seasons of water quality monitoring, but

‘no significant difference’ in the concentrations of these metals/metalloids in upstream and downstream

samples

Crosscourse pit contains the poorest quality water at URPA, with EC significantly above EC guideline value,

and concentrations of metals/metalloids (As, Co, Cu, and Zn) exceeding guideline value many times during

ten years of testing, suggesting these metals are effectively solubilised during processing of ore and remain in

soluble form following deposition into the pit, but WAD cyanide concentrations non-detectable in nearly all

samples despite significant concentrations in the tailings discharge to the pit, indicating that cyanide is short-

lived

Groundwater does not appear to be migrating to any significant extent into the nearby McKinlay River based

on concentrations of cobalt in water sampled from the nearby downstream surface water sample point,

which have been very low when high concentrations have been measured in adjacent groundwater

monitoring locations.

Potential impacts on surface and groundwater quality as a result of the project may arise as a result of the following

sources, features and/or processes:

Acid Rock Drainage (ARD) resulting from the oxidation of sulphidic materials exposed to oxygen. This may

arise from:

o Pit water level fluctuation in water storage areas exposing pit walls

o Seepage from waste rock dumps or stockpiles and/or tailings containing sulphidic mineralisation

o Underground mining

o Sulphidic materials used to construct infrastructure in Prospect pit such as ramps, roads and

platforms

Saline, metalliferous drainage and/or neutral drainage may also be produced by the materials described

above, without producing sulphidic acidity, but rather, latent acidity.

Existing surface water features such as pit lakes, water storage dams which may have dissolved substances

above guideline values, or have the potential to exceed guidelines from evaporative concentration, change in

water level or as a result of the disposal of mine products sub-aqueously.

This draft EIS presents a qualitative impact assessment based on the current understanding of consequent seepage

to/from each of the water storage areas on site and changes in water levels as a result of dewatering the Prospect

pits. This understanding is based on topographic elevation of the water storages, and groundwater extraction

modelling.

The impact from underground mine dewatering reaches its maximum in Dam A and B, Crosscourse pit and other

minor pits and dams, at or just after, mine closure. During mining, Dam B will potential contribute 0.9 L/s (change in

RL of 5 m) to the groundwater, but it will take >4 years for the seepage to reach the River, by which time seepage will


be dispersed and solutes adsorbed onto sediments through which it flows, and diluted as it reaches the shallow

alluvium via groundwater.

Any additional seepage from Crosscourse pit (i.e. up to 3.5 L/s during mining) will be towards the underground mine,

which will act as a sink. Groundwater ingress to the underground mine will then be pumped back to Crosscourse pit.

As the water level recovers in Dams A, B and C and Lady Alice pit, the water in these pits and consequently any

seepage via groundwater might impact the downgradient environment and surface water. The full extent of this will

be addressed by predictive geochemical modelling to be reported in the Supplementary EIS once the geochemistry

data has been assessed from known oxidation profiles and more geochemical information is available.

Following completion of mining, groundwater levels will be allowed to recover in the backfilled, underground mine

void and in Prospect pits. The walls of the underground mine and backfilled waste rock, exposed to air, allows

oxidation of sulphidic materials. This is a potential source of contamination for groundwater depending on the lag

time of the sulphides (to be determined in test work to be reported in the Supplementary report).

In the scenario where Crosscourse pit is also, post mining, allowed to fill its groundwater equilibrium 188 mAHD, i.e.

with no intended water discharge from the pit during operations; predicted groundwater flow will be from

Crosscourse pit to all other pits and dams on site, and McKinlay River, via the shallow aquifer. In the period six years

post mining, groundwater outflow from Crosscourse pit would peak at 17 L/s within first two years and stabilise at

around 13 L/s five years after post mining. In this case Crosscourse pit would contribute to additional contamination in

all pits through mass transport. Groundwater would become contaminated and would contribute to contamination

downgradient in the McKinley River. In the wet season when maximum flow in the McKinlay River occurs,

groundwater flow will be less than 1% of river flow but in the dry season groundwater flow will be significantly higher.

The qualitative assessment of inland water quality sources, pathways and sinks presented in this indicate that there is

a relatively low level of risk to surface water and groundwater quality in the mining, closure and post closure phases of

the project, provided the water level in Crosscourse pit is managed. The quantitative extent of impact is predicted to

be low, as reported in these preliminary findings, but will be reported in detail following the delivery of the predictive

geochemical modelling in a Supplementary EIS.

1.12 Aquatic Ecosystems

The McKinlay River represents the lowest natural point in the landscape, and so groundwater is close to the surface,

creating permanent surface and/or sub-surface water in incised areas of the river channel. Groundwater discharge

(including subsurface flow) plays an important role in the aquatic ecosystems of the upper McKinlay River by allowing

for the persistence of (some) permanent pools throughout the dry season, and vigorous riparian vegetation. The

permanent pools provide food, water and cooling for terrestrial fauna, and nesting habitat for birds and reptiles in the

riparian zone.

The continuity and vigour of riparian vegetation also plays an important role in a number of aspects of these aquatic

ecosystems. Increased shading decreases water temperature and reduces evaporation potential during the dry

season. Additionally, roots, fallen branches and detritus provide structural habitat for aquatic fauna from many

trophic levels. Finally, riparian vegetation is integral in maintaining bank stability, reducing erosion of stream banks

and subsequent deposition of fine sediments in the stream bed, and reducing interstitial spaces (pore spaces between

coarse substrate types, such as gravel, pebbles and cobbles) considered highly important for the diversity of

macroinvertebrate communities. Therefore, riparian vegetation and surface water should be viewed as co-dependent,

and the impairment of one community is very likely to result in the impairment of the other.

Drawdown from mine dewatering will result in reduction in groundwater available for aquatic ecosystems and riparian

vegetation. The impact of the modelled drawdown will be far less in both magnitude and duration than previous

mining operations i.e. complete dewatering of the Crosscourse pit, however there is expected to be a decrease in

availability of groundwater flow to discharge to the McKinlay River for groundwater dependent surface water

ecosystems and riparian vegetation.

The results of modelling show that the greatest impacts related to groundwater availability will likely occur after

mining has ceased, and although overall changes to the availability of groundwater to the McKinlay River is low (i.e.


3%), the quantum of change varies spatially along different sections of the River, and is likely to be greatest in local

sections closest to underground mining. These changes are described below. Table 1-7 includes reference to four

pools of water identified as containing permanent surface water (i.e. GDEs) during 2019 field survey and aquatic

ecosystem characterisation along the upper McKinlay River.

TABLE 1-7 REDUCTION IN GROUNDWATER AVAILABILITY THE MCKINLAY RIVER

Local Section of

McKinlay River

GDEs

Present

Mine Development

(2020 to 2021)

Mine Operation

(2021 to 2023)

Recovery

(2023 to 2028)

Post-Mining

(2028 onwards)

Upstream from

URPA

Riparian

vegetation 0% 0% 0 - 0.05% 0.05 - 0%

Upstream from

URPA

Billabong 0 - 0.2% 0.2 - 0.95% 0.99 - 0.2% 0.2 - 0%

Adjacent to

URPA

Riparian

vegetation 0 - 4% 4-12% 12 - 1% 1 - 0%

Adjacent

MRWET08

Riparian

vegetation

0 - 3% 3 - 15% 17 - 3% 3 - 0%

Downstream of

URRPA

Riparian

vegetation 0 - 0.1% 0.1 - 1.7% 2.1 - 1.2% 1.2 - 0%

Downstream

of URPA

Site MRWET12

site MRWET13

Riparian

vegetation

0% 0% 0% 0%

The aquatic community present within permanent pools on the upper McKinlay River is likely to be made up of taxa

tolerant of conditions encountered in the late dry season, conditions associated with a reduction in surface water

volume such as lower dissolved oxygen, concentration of salts and increased temperature. Should any pool experience

reduction in surface water volume as a result of lowered groundwater availability, stress on those taxa is not likely to

be beyond natural processes that occur in the environment.

A reduction in surface water volume also results in reductions in available habitat, space and substrate, the results of

which are likely to alter the assemblage of taxa within isolated pools. Again, this is not atypical of ephemeral pools,

whose aquatic communities experience these conditions annually, i.e. inter-annual variations in rainfall, water

availability and macroinvertebrate community composition. Antecedent wet season conditions are likely to be the

prominent driver of aquatic community assemblages. It is therefore more likely that annual variation in wet season

rainfall will have a greater influence on the aquatic ecology of permanent pools than a small loss in surface water

recharge during the dry season from groundwater.

Although there is likely to be some reduction in surface water availability from groundwater migration and availability

downstream of the URPA as a result of project dewatering, it is not likely to be the cause of drying of any permanent

pool mapped in the upper McKinlay River. Two identified pools downstream of the URPA are likely to be important

refugial habitat during the dry season, and provide unique habitat compared with other permanent pools. Their

persistence through the dry season due to groundwater availability and antecedent wet season rainfall may naturally

fluctuate, but a short-term reduction in available water is not likely to result in a long-term impact to the aquatic

community or riparian vegetation health at these pools.


In each section of the river, losses in groundwater availability are low, yet their cumulative impact on subsurface flow

along the upper McKinlay River may impact on permanent surface water immediately downstream of the mining lease

boundary. Losses are not considered likely to result in the drying of these pools, but may reduce their volume,

especially towards the end of the dry season when evaporation is high. In years of low rainfall, isolated permanent

pools are especially important as they provide refuge for aquatic flora and fauna that propagate the river during the

wet season. As rainfall varies annually, it is difficult to predict if these conditions will occur during the life of the

project. The risk has been set at Medium, given the cumulative impact and a low rainfall scenario.

Ongoing monitoring of groundwater and surface water levels will be crucial in setting (and responding to) adaptive

management strategies, if required, to maintain the aquatic ecosystems of perennial surface water in the upper

McKinlay River during the project and at, and beyond, closure.

The relatively short term duration of the project, and the apparent resilience of the aquatic ecosystems and riparian

vegetation community of the upper McKinlay River indicates there is little probability of residual impacts beyond the

recovery (post-closure) phase of the project.

Low magnitude, short-term changes to habitat availability, water availability and connectivity within the upper

McKinlay River as a result of operational dewatering and subsequent changes in groundwater discharge are expected.

The taxa present in permanent pools are adapted to such conditions. This is especially true for intermittent headwater

streams, where antecedent wet season conditions can have a greater impact on taxa present in permanent pools in

the dry season.

The project is not expected to result in any significant changes to the assemblages of aquatic biota in the upper

McKinlay River. Ongoing monitoring of the receiving environment, as described above, will be the most effective tool

in the management of potential aquatic ecosystem impacts.

20

NT Mining Operations Pty Ltd Union Reefs North Underground Mine Draft Environmental Impact Statement

2 ACRONYMS

Acronym Description

AAPA Aboriginal Areas Protection Authority

AEP Annual Exceedance Probability

ANZECC Australian and New Zealand Environmental and Conservation Council

ARMCANZ Agriculture and Resource Management Council of Australia and New Zealand

AusRivAS Australian Rivers Assessment System

BoM Bureau of Meteorology

BUD Beneficial Use Declaration

CGAO Crocodile Gold Australian Operations

CHPA Cosmo Howley Project Area

CIL Carbon In Leach

CO2-e Carbon dioxide equivalence

CRF Cemented Rock Fill

DENR Department of Environment and Natural Resources

DLRM Department of Land Resource Management

DPIR Department of Primary Industry and Resources

DTA Direct Toxicity Assessment

EC Electrical Conductivity

EIS Environmental Impact Statement

EOM End of Mine

EPA Environmental Protection Authority

EPBC Act Environment Protection and Biodiversity Conservation Act 1999

ESCP Erosion and Sediment Control Plan

ESR Environment and Social Responsibility

ESRMS Environmental and Social Responsibility Management System

FFA Flood frequency analysis

GL Gigalitres

g/t grams per tonne

GBS GBS Gold Australia Pty Ltd

GDE Groundwater Dependent Ecosystem

21


Acronym Description

GHG Greenhouse Gas

GV Guideline Values

GW Groundwater

GWA Genesee Wyoming Australia

ha hectare

KLG Kirkland Lake Gold

km km

kV kilovolt

kW kilowatt

L/s Litres per second

LOM Life of Mine

MCA Minerals Council of Australia

mAHD metres with respect to Australian Height Datum

MCP Mine Closure Plan

ML MegaLitres

MLN Mineral Lease Number

mm Millimeters

MMP Mining Management Plan

MNES Matters of National Environmental Significance

Mt Million tonnes

Mtpa Million tonnes per annum

NEPM National Environmental Protection Measure

NGER National Greenhouse Energy Reporting

NLC Northern Land Council

NMD Neutral Mine Drainage

NOI Notice Of Intent

NR Natural Resource

NRM Natural Resource Management

NT Northern Territory

NTGS Northern Territory Geological Survey

NTMO Northern Territory Mining Operations Pty Ltd

22


Acronym Description

oz ounces

PCO Pine Creek Orogen

PCPA Pine Creek Project Area

PEHR Public and Environmental Health Regulations

PSA Pressure Swing Absorption

PWC Power and Water Corporation

RL Reduced Level

ROM Run Of Mine

SG Specific Gravity

SSTVs Site Specific Trigger Values

SW Surface Water

SWG Livestock Drinking Water Guidelines

TDS Total Dissolved Solids

tpa tonnes per annum

TPWC Act Territory Parks and Wildlife Conservation Act

TSF Tailings Storage Facility

URCP Union Reefs Crosscourse Pit

URPA Union Reefs Project Area

WA Western Australia

WDL Waste Discharge Licence

WoNS Weeds of National Significance

WRD Waste Rock Dump

WRF Waste Rock Fill

23


3 INTRODUCTION

3.1 Overview

Northern Territory Mining Operations Pty Ltd (NTMO) propose to develop the Union Reefs North underground mine

(the project). In April 2019, NTMO submitted a notice of intent for the Proposal to the NT EPA for consideration under

the Environmental Assessment Act 1982. The Proposal is for a new mining activity on a highly modified brownfield

mine site that has historically been subject to gold mining.

This Environmental Impact Statement (draft EIS) is submitted to the Northern Territory (NT) Environment Protection

Authority (EPA) for assessment under the Northern Territory Environmental Assessment Act (EA Act). The Proposal

(the project) is a ‘controlled action’ under the Commonwealth Environment Protection Biodiversity Conservation Act

(EPBC Act), and will be assessed in accordance with the bilateral agreement between the Australian Government and

the Northern Territory Government. The controlling provisions are listed threatened species (Sections 18 and 18A).

This draft EIS has been prepared in accordance with the Terms of Reference (TOR) for the preparation of an

Environmental Impact Statement; Union Reefs North Underground Mine (Appendix A). A cross-reference document

comparing the TOR against the content of this draft EIS has been provided in Appendix B, for ease of reference.

3.2 The Proponent

The project proponent is NTMO (ACN 136 525 990), which is 100% owned by Kirkland Lake Gold (KLG). KLG is an

Australian and Canadian gold mining and exploration company trading on the Australian, New York and the Toronto

Stock Exchanges. The company is a mid-tier gold producer and a signatory to the Responsible Gold Mining Principles

set out by the World Gold Council. KLG has a target production in 2019 of over 950,000 ounces (oz) from mines in

Canada and Australia. Key NTMO project staff and company details are provided in Table 3-1.

TABLE 3-1 NT MINING OPERATIONS CONTACT

Name Mr Mark Edwards Ms Sally Horsnell

Title Project Director, NT Operations Environmental Manager

Email [email protected] [email protected]

Address 2/14 Shepherd Street, Darwin NT 0800

Postal PO Box 469, Darwin NT 0800

Phone 08 8982 4444

Fax 08 8982 4400

ABN 65 36 525 990

NTMO has engaged suitably qualified, independent consultants to prepare specialist technical studies as well as the

draft EIS report. The names, qualifications and experience of key persons involved in the preparation of the draft EIS

are provided in Appendix C, along with their technical scope.

3.3 Project Location

The spatial coordinates of the project footprint and site technical studies are included in Appendix D.

Geographically, the NTMO operations are centred between the Townships of Adelaide River to the north and Pine

Creek to the south. The Union Reefs Project Area (URPA) is located approximately 20 km north of the township of Pine

Creek and 175 km southeast of Darwin (220 km by road). The URPA is shown in a regional context in Figure 3-1.

24


The URPA is accessed from the Stuart Highway along a restricted 8 km mine access road, Ping Que Road. The URPA

tenements and Ping Que Road occupy land on Mary River West Station (Pastoral Lease 815, Figure 3-2) and are

located in a region of historical mining and pastoral land use (cattle grazing). Figure 3-2 indicates land tenure and

locations adjacent to the URPA.

The URPA consists of ten mineral titles (Figure 3-3) which are all held by KLG (noting that Newmarket Gold NT

Holdings Pty Ltd is a subsidiary of KLG). NTMO has been appointed as the nominated operator of the URPA on behalf

of KLG.

This draft EIS outlines the proposed activities within Mineral Lease Number 1109 (MLN1109, Figure 3-3). The spatial

coordinates of the proposal footprint and site technical studies have been included in Appendix D.

The Darwin to Adelaide Railway easement operated by Genesee Wyoming Australia (GWA) passes through the

western side of MLN1109 and a 66 kV transmission line (No. 219085) runs along the same route. Gas pipeline (No.

203267) also runs through MLN1109 and the Commonwealth holds the lease for the Telstra microwave repeater

tower (No. 8105) located on the lease (Figure 3-3).

30 September 2019GCS GDA 1994

!

!

!

!

!

!

!

!

!

!

BATCHELOR

PINE CREEK

ADELAIDE RIVER

DARWINPALMERSTON

DALY RIVER

MANDORAH

HUMPTY DOO

HAYES CREEKEMERALD SPRINGS

132°0'0"E

132°0'0"E

131°30'0"E

131°30'0"E

131°0'0"E

131°0'0"E12

°30'0"

S

12°30

'0"S

13°0'

0"S

13°0'

0"S

13°30

'0"S

13°30

'0"S

14°0'

0"S

14°0'

0"S

Union Reefs Project AreaRegional Location

0 25 50Kilometres

¯

Document Path: F:\Y Drive Data Backup\GIS\Projects\Union Reefs\2019 EIS\URPA Regional Location.mxd

LegendConservation AreaUnion Reefs Project Area Figure 3-1

22 November 2019GCS GDA 1994

#

#

#

# #

!

MARY RIVER WEST

JINDARE BONROOK

MARY RIVER EAST

BAN BAN SPRINGS

PINE CREEK

KYBROOK BONBROOK

ESMERALDA

SETAY VALLEY

FRANCES CREEK

0 2.5 5Kilometres

¯

Document Path: F:\Y Drive Data Backup\GIS\Projects\Union Reefs\2019 EIS\URPA Properties.mxd

Legend! Towns# Localities

RailwayHighways

RoadsGas PipelineMajor WatercourseMajor Waterbody

URPAPastoral Leases Freehold

Union Reefs Project Area Land Tenure

Figure 3-2

30 September 2019GCS GDA 1994

_̂

_̂

_̂

_̂

!

MLN1109

ML27999

MA402

ML31122

MA400MA401

MLN833

MA398

MA399

MLN856

131°50'0"E

131°50'0"E

131°45'0"E

131°45'0"E13

°40'0"

S

13°40

'0"S

13°45

'0"S

13°45

'0"S

0 2.5 5

Kilometres

¯

Document Path: F:\Y Drive Data Backup\GIS\Projects\Union Reefs\2019 EIS\URPA Utilities.mxd

Union Reefs Project Area Mineral Titles

Legend_̂ Telstra Towers

PowerlinesGas Pipeline

HighwaysRoadsRailway Figure 3-3

28


3.4 Environmental and Social Performance

NTMO operates another authorised mining operations at the Cosmo Howley Project Area (CHPA), approximately 40

km to the south of the URPA. NTMO are actively mining and rehabilitating at the CHPA, with ore supplied to the Union

Reefs processing plant.

At each of its mineral leases, NTMO is committed to compliance with statutory and other requirements, developing an

effective Environment and Social Responsibility Management System (ESRMS), continuous improvement and

minimising environmental and social impacts. The KLG policies, to which NTMO adheres, outline these commitments

and are available on the KLG website www.klgold.com/about-us/policies/

KLG has also recently signed up to the World Gold Council’s Responsible Gold Mining Principles, a new framework that

sets out clear expectations for consumers, investors and the downstream gold supply chain as to what constitutes

responsible gold mining. More details can be found at https://www.gold.org/about-gold/gold-supply/responsible-

gold/responsible-gold-mining-principles

NTMO identifies and tracks statutory and other requirements applicable to its activities, and a list of the key

legislation is provided in Section 5. KLG policies are described in Section 5.1.4. The KLG Management Team are

responsible for ensuring that all site employees and contractors:

Comply with all laws, conditions of any permits, licenses and authorisations or any NTMO standards,

management plans and procedures applicable to their activities.

Work safely, protecting people, environment and community.

Identify hazards and/or risks associated with their work and implement appropriate controls.

Report and rectify observed unsafe acts, incidents or hazards.

NTMO has demonstrated an ongoing commitment to the rehabilitation of the Cosmo-Howley mine site with a

significant amount of work completed on establishing flexible water pumping infrastructure to allow water to be

treated and discharged when conditions are appropriate. Discharge is carried out under the terms set out within a 5

year waste discharge license (WDL). This WDL is aligned to an adaptive management strategy which has been

approved by DENR. It has thus been possible for NTMO to reduce water inventories at Cosmo-Howley from around

8.5 GigaLitres (GL) to less than 6.5 GL today. With this reduction in inventory, water has been completely removed

from the Chinese 2 historical open pit for it to be refilled with waste rock from site. This project is currently underway

with the completion expected prior to the onset of the 2019/2020 wet season.

This backfill project will be used to guide future pit backfilling programs for the CHPA, with a final plan to significantly

reduce the amount of waste rock stored on surface and to also reduce the amount of possible water storage on site.

Other activities on site include the establishment of a successful water interception trench near the Howley Waste

Rock Dump (WRD), which has allowed the company to intercept and then treat some of the most contaminated water

that previously left site without control.

NTMO has recently entered into a Memorandum of Understanding with Charles Darwin University that allocates

funding over three years to a post-doctoral research program for Ghost bat conservation. Ghost bats often reside in

disused mine workings (called adits) because the adits provide the ideal temperature and humidity conditions that

Ghost bats require to roost. Yet those same habitat opportunities provided by mining activity may sometimes become

a key threatening process, i.e. roost disturbance, mine collapse and mine reworking. There is a lot that is unknown

about regional roost interconnectivity, and the behaviour of Ghost bats when a former roost becomes unsuitable or

unavailable. Dr Nicola Hanrahan will be sponsored by Charles Darwin University, under the Memorandum of

Understanding, to study the Ghost bats of the Pine Creek region (see also Chapter 11).

The commitments made in this draft EIS in relation to managing potential environmental and social impacts of the

project are listed in Appendix E.

http://www.klgold.com/about-us/policies/

https://www.gold.org/about-gold/gold-supply/responsible-gold/responsible-gold-mining-principles

https://www.gold.org/about-gold/gold-supply/responsible-gold/responsible-gold-mining-principles

29


3.4.1 SOCIAL RESPONSIBILITY AND COMMUNITY BENEFIT

NTMO is currently active in the local and regional community, providing sponsorships to many local events and

activities:

the Fred Pass Rural Show

The Northern Australia Emergency Response Competition – both sponsorship and the use of the

underground mine for the competition

The Top End Gran Fondo social bike ride

the Douglas Daly Camp Draft

Darwin Mining Club’s golf day, which raises money for CareFlight

NTMO has spent approximately $36 M over the past ten years on products and services provided by local companies

based in Katherine, Pine Creek and Adelaide River; and over $300 M when including Palmerston and Darwin

businesses. These local companies provide laboratory services, transport and logistics, construction, mechanical and

repair services and energy supply. KLG prides itself on working closely with local business for the benefit of the local

community.

KLG is also active in hiring local employee’s wherever possible. While it is not always practical to hire locally, especially

with technical or experienced roles, KLG currently employs around 400 people, and 60% of this work force live locally.

In the NTMO leadership team this ratio is over 80% locally based. Of the 400 employees, more than 270 are directly

employed by KLG and the other 130 are contractors. This project will add an additional 50 - 80 jobs specifically for the

mining operation. As the new operations begin in places like Pine Creek, these numbers will increase further.

Of those roles that are not locally based these include:

Experienced equipment operators e.g. Jumbo operators:

o KLG has long term plans to train operators on our own equipment, resulting in a lift in key operating

skills available in Darwin.

Roles requiring technical skills/experienced/knowledge:

o Geology

o Mine Engineering

o Metallurgy

In 2019, KLG will have invested around $150 M in the NT Operations, with a decision to maintain restart of the

processing plant being made either late in 2019 or early 2020. The strategy is to fill the Union Reefs plant with

material mined from Cosmo, Union Reefs and Pine Creek in coming few years, making the NT Operations a significant

contributor to the Northern Territory economy, with a plan to produce over 200,000 ounces of gold per year from

these operations. This project is a key part of this longer term strategy which has the potential to deliver over $10 M

in Northern Territory royalties to the government each year (based on today’s gold price of over $2,100/ounce of

gold).

In November 2019, KLG showcased its operations with an official reopening of the Union Reefs processing plant. The

event hosted the Speaker of the House, the Hon Kezia Purick, the Minister for Primary Industry and Resources, the

Hon Paul Kirby, the Opposition Leader, Mr Gary Higgins, the independent MLA for Nelson, Mr Gerry Wood and the

Mayor of the Victoria Daly Regional Council, Mr Brian Pedwell. The event also included various stakeholders from the

project area including the Mary River West Station Manager, representatives from the NLC, and other dignitaries from

Pine Creek and Adelaide River.

The company has also contributed, and will continue to contribute, payroll tax and royalties to the NT Government. It

is estimated that the URPA project will contribute royalty payments in the order of $1.6 M to $2.1 M, and $0.5 M in

payroll tax over the two year mine life.

30


4 PROPOSAL DESCRIPTION The site layout and mine plan for the proposed underground mine is based on the location of gold deposits at the

URPA which follow the Pine Creek shear zone and are located on two small sub parallel northwest, mineralised trends

(see Figure 4-1). The eastern trend is known as the ‘Lady Alice line’ and the western trend is the ‘Union Line’.

NTMO is planning to develop and advance the Union Reefs North Underground Mine (the project) to target the

Prospect claim deposit mineralisation. Mine development will be completed along the Union line and extend into the

Lady Alice line. Figure 4-1 illustrates the mineralised zones and pit and portal location. The underground development

will also be used as an exploration point to test mineralisation deeper in the Union trend, as well as new

mineralisation on the Lady Alice trend.

Both of these mineralised trends have previously been mined via the Union North, Prospect, Lady Alice, Crosscourse

and Millars open pits. The Crosscourse Open pit is located where the two mineralised trends are in close enough

proximity to link, forming a zone of wider and higher grade mineralisation (see Figure 4-1). Crosscourse pit was the

deepest and most productive open pit in the URPA.

The current URPA site layout and infrastructure are provided in Figure 4-2.

The underground mine will be accessed via a portal (entry) and decline developed from within the existing Prospect

pit. The underground mine will target both the Union and Lady Alice mineralisation trends.

Prospect pit is divided into two sections, north and south which each have a pit lake. Prospect north and south pit(s)

will be completely dewatered prior to portal construction, with only a small dewatering sump remaining during the

operational phase of the project. The underground mine will be accessed via a portal and decline developed from

within the existing Prospect north pit (Figure 4-3). Prospect pit (south) will be used to store waste rock that will then

be returned underground and used as backfill during mining operations. This is the same model for waste rock

management as used at the Cosmo Deeps mine by NTMO. Ore will be trucked directly to the existing Run of Mine

(ROM) pad, and then fed into the existing processing plant crusher using the existing infrastructure and equipment.

Tailings will be deposited in the existing Crosscourse pit Tailings Storage Facility (TSF).

The 2017 NTMO NI 43-101 Ore Reserve statement indicates a probable mineral reserve of 39,200 ounces of gold from

the Prospect claim deposit with an estimated Life of Mine (LOM) of two years. Additional drilling from within the

underground mine will further define the extent of the mineralisation, and aims to grow the reportable mineral

reserve, to extend the currently proposed LOM.

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Figure 4-3

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4.1 Summary Information

A summary of the key components of the proposal description is provided in Table 4-1.

TABLE 4-1 PROJECT KEY COMPONENTS

Element Proposed

Project Life

Construction period Two to three months, including pit dewatering

Operational period Two years with potential extension, i.e. there is a plan to construct an exploration platform in the Union Reefs North Underground Mine for exploration drilling.

Production Estimates

Mining rate 92,000 tonnes/annum

Ore 280,000 tonnes (t) ROM ore

Waste rock 291,000 t, of which approximately 241,000 t will be returned underground

Tailings solids 276,000 t

Production 39,232 gold ounces

Underground Mine

Portal location Eastern wall of the existing Prospect pit located at 177.5 metres Australian Height Datum (mAHD).

Mine depth 220 m below ground surface.

Mining method

The planned underground mining method is a combination of up-hole benching and Avoca stopping, in a three-lift, bottom-up sequence. This method requires the decline to be advanced at least three levels in depth prior to ore production commencing. The Cosmo underground development has been developed in this same way.

Materials handling

Ore will be trucked directly from the portal to the existing Run Of Mine (ROM) pad, and then fed into the processing plant crusher using the existing infrastructure and equipment.

Waste rock will be stored in the Prospect South pit, prior to progressive reuse underground to backfill the stopes, i.e. stopes will be backfilled with waste rock and cement rock fill.

Existing Authorised Infrastructure

Tailings Storage Facility (TSF)

Existing TSF is Crosscourse pit.

Crosscourse pit currently holds 10,190 ML tailings and 12,605 ML water.

Processing operations in 2021 to 2023 will contribute approximately 1,600 ML tailings and 2,400 ML water to Crosscourse pit.

Processing plant Existing, authorised

Hazardous materials storage Existing, authorised

Haul road Existing haul road to ROM pad will require road extension of approximately 400 m into Prospect pit.

35


Element Proposed

Power Existing power lines and substation will be extended to create additional capacity 9 to 12 Megawatt (MW).

Site clearing The URPA currently contains disturbed area of 495 hectare (ha) with 354 ha rehabilitated/revegetated. Site clearing for the project will be approximately 1 ha.

Water dams This project will utilise water from Crosscourse pit and from Dam C. Existing water storage in Prospect pit will be pumped to Crosscourse pit prior to project construction.

Water

Dewatering during mine development 100 MegaLitres (ML)

Water use during mine operation 290 to 315 ML/year recycle from Crosscourse pit, and from Dam C

Other Infrastructure

Explosive and detonator storage 40 t and 25 kg respectively

Diesel consumption 720,000 L/year

Annual greenhouse gas emissions 9,639 Carbon Dioxide Equivalence (t-CO2-e)

Workforce

Construction 12 staff

Operations 80 staff

4.2 Existing Authorisations

NTMO mineral titles in the Northern Territory (NT) comprise an area greater than 2,000 square km (km) located

around 200 km south of Darwin (see Figure 4-4). Currently authorised mining operations (excluding exploration

activities) at CHPA and URPA, both of which are operated by NTMO, are summarised in Table 4-2.

TABLE 4-2 SUMMARY OF AUTHORISED NTMO OPERATIONS IN THE PINE CREEK REGION

Site Activities Approved Action

Cosmo Howley Project Area (CHPA)

Authorisation

#0546-03

Underground mining

Ore produced from underground operations is transported to the Cosmo Deeps Run Of Mine (ROM) pad and then hauled to the Union Reefs Processing Plant. The haul road extends from the Cosmo Deeps underground mine ROM Pad directly to the Stuart Highway. Underground ore haulage operations are 24 hours per day, seven days per week.

Mine remediation and rehabilitation

Chinese 2 pit remediation and rehabilitation including pit rehabilitation earthworks and environmental management and monitoring program. Chinese 2 pit is an open cut pit of 3.7 ha mined during the 1990s. The design involves dewatering and backfilling the pit with waste rock. Backfill will be placed in Chinese 2 pit by a technique of layering and compaction of Potential Acid Forming (PAF) and Non-Acid Forming (NAF) material. An engineered cap, using screened NAF material, will be placed over the final NAF layer to prevent further oxidisation of the PAF material and to minimise impact on the surrounding groundwater.

36


Site Activities Approved Action

Union Reefs Project Area (URPA)

Authorisation

# 0539-03

Ore processing

Mined ore from the CHPA is transported and stockpiled on the URPA Run Of Mine (ROM) prior to being fed into the processing plant.

The URPA Processing Plant was placed in care and maintenance in June 2017 and restarted in October 2019.

Tailings storage

Tailings generated from the URPA processing plant are deposited into the Crosscourse pit, which has been legally utilised as the site Tailings Storage Facility (TSF) since August 2002.

The tailings are piped and discharged from a single point on the western perimeter into the Crosscourse pit TSF. Tailings discharge rates are up to 300 t/hour during normal processing conditions. Water for the processing plant is reclaimed from the Crosscourse TSF, and supplemented by raw water from Dam C where processing activities (i.e. elution) require a higher quality water.

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4.3 Site History

The Union Reefs area is an important historical gold mining centre that was once serviced by a train line (now

abandoned) that ran through the western sector of MLN1109. Gold was first discovered at Union Reefs in 1873. Some

2,300 small pits, shafts, adits and open cuts were developed to exploit the high-grade, lode style mineralisation that

were worked by Chinese tributers. The first phase of mining at Union Reefs ceased in 1914, and subsequent attempts

to reopen mines in 1922 and 1934 were not successful.

Between 1963 and 1988 extensive geological mapping and exploration drilling programs were undertaken by various

organisations across the URPA. Togar Pty Ltd undertook mining and processing of alluvial ore at the site from 1987

until 1992. In 1993, the Shell Company of Australia (SCOA) prepared an Environmental Impact Statement (EIS) to mine

and process ore from the Crosscourse and Union North pits (Figure 4-2). The period between 1994 and 2003

represents the most significant mining and processing activities at the URPA, undertaken first by SCOA then by Acacia

Resources and later AngloGold from 2000 to 2003. During this period a total of around 20 million tonnes of ROM ore

was mined at an average grade of around 1.5 grams per tonne (g/t) for a production total of just below

950,000 ounces mined. The majority of this material (around 90%) was mined from the Crosscourse pit.

During the 1994 to 2003 operational period, 11 open pits were mined and two waste rock dumps (WRDs) constructed.

Processing tailings were deposited into the Old Tailings Dam (surface tailings facility) and Union North pit and

Crosscourse pits (from 2002). All of these domains are included in the URPA layout in Figure 4-2. Following the

cessation of mining in 2003, the site was rehabilitated and the URPA processing plant placed into care and

maintenance. NTMO has completed significant site water monitoring of the URPA, and demonstrated that the site is

in good condition (see Chapter 13).

GBS Gold Australia Pty Ltd (GBS) officially re-opened the URPA in November 2006 for the processing of low-grade

stockpiles and ore from remote operations. They operated the mine until they went into receivership in 2008. During

that period they processed around 2.8 Million tonnes of ore at an average grade of around 2.0 g/t from mines at

Howley, North Point, Brocks Creek and Fountain Head.

In 2009, Crocodile Gold International (CGI) purchased the Australian gold mining assets of GBS and in December 2009

commenced remote mining and URPA processing operations via its subsidiary Crocodile Gold Australian Operations

(CGAO). From 2011, ore sourced from the Cosmo Underground Mine (Figure 4-4), and other satellite surface deposits

and processed at the URPA. In July 2015, CGAO merged with Newmarket Gold Inc. In November 2016, Newmarket

Gold Inc. merged with KLG. Since Crocodile Gold purchased the assets from GBS in 2009, 7.9 Mt of ore at an average

grade of 2.1 g/t has been milled at Union Reefs.

Since the URPA processing plant was commissioned in 1993, it has operated for 23 out of 27 years. A total 30.3 Mt of

ore has been processed at an average grade of 1.7 g/t. This has produced more than 1.5 million oz of gold. The mill

has performed well, with no significant environmental issues noted since it commenced operations. It is still in good

condition and suitable for future production. The material to be processed from the underground mine (the project)

represents less than 1% of total production since 1993.

NTMO has not operated the processing plant since mining activities at the Cosmo Howley Project Area (CHPA, Figure

4-4) were temporarily suspended in June 2017. The URPA processing plant has remained in care and maintenance,

maintained by NTMO staff, until the resumption of production in October 2019. The mill restart is currently testing

process material mined from the Cosmo Deeps mine including material from the Cosmo and Lantern deposits.

4.4 Proposal Context

NTMO are actively working through a detailed five year Life of Mine (LOM) plan for its Northern Territory operations.

This plan uses the Union Reefs processing plant as the central hub for mines at the Cosmo Howley Project Area

(CHPA), URPA and Pine Creek Project Area (PCPA) in the future (see Figure 4-4). The challenge for NTMO is to provide

enough ore to the processing plant to run it cost efficiently. The Union Reefs North Underground Mine is an important

part of this strategy, in that it will contribute a suitable amount of ore to the processing plant.

39


NTMO is currently completing a significant amount of exploration work including:

At the Cosmo/Lantern deposit at CHPA, where there are three underground rigs drilling to extend the mine

life.

In the URPA, where a surface rig has been active in the southern area, and the plan in the next few years is to

construct an underground mine close to the Millars pit, south of the Crosscourse open pit.

In the PCPA where a surface rig is drilling to test for another potential underground mine around the Gandy’s

deposit in the north.

There is also a plan to construct an exploration platform in the Union Reefs North Underground Mine for exploration

drilling, to test if the ore extends below the current Mineral Reserves can be converted into JORC-compliant Inferred

Resources. This will require another underground diamond rig to commence drilling around six months after the mine

commences operations.

The LOM plan for the Northern Territory operations is based on mining from these three project areas to feed ROM

ore to the Union Reefs processing plant at a rate of over 2 million tonnes per annum (tpa). Given the required level of

exploration and growth development necessary to achieve this plan, the Union Reefs North Underground Mine is

critical to help fund this development program. There is not currently sufficient ore supply from the Cosmo/Lantern

mine to profitably operate in the Northern Territory as a stand-alone operation, and fund additional exploration and

development work and rehabilitation at the same time. Bringing mines like the Union Reefs North Underground Mine

on line will allow NTMO to operate profitably and cover the costs of the required exploration work. This new mine is

therefore an important pillar in the plans for future growth and sustainable development for NTMO in the Northern

Territory.

The plan notes that there is potential for the Union Reefs North Underground mine to continue well into the future

and be supported by ore from Union Reefs South, Cosmo/Lantern and Pine Creek for the next five to ten years

pending exploration success and permitting.

4.5 Mine Schedule

An indicative schedule for the project is presented in Table 4-3.

TABLE 4-3 INDICATIVE PROJECT SCHEDULE

Time (Indicative) (2 to 3 Months) 2020 to 2022 2022 to 2023 2023 to 2028

Phase Mine development Mine operations Mine closure Post closure

Activities Construction

activities Mining and

processing activities

Closure and rehabilitation

activities Monitoring activities

4.6 URPA Existing Infrastructure

The URPA is a highly modified brownfields mining area. Approximately 495 ha has been disturbed historically, of which

355 ha has been rehabilitated/revegetated. Existing infrastructure and facilities at the URPA is depicted in Figure 4-2.

Underground mine development will utilise the following existing URPA infrastructure:

The URPA administration area.

Existing haul road leading to the ROM Pad (will connect to upgraded haul road connection to portal, Figure

4-3).

Existing URPA laydown and landfill areas.

Existing energy infrastructure (will connect to new power infrastructure).

The fuel bay, wash-down area and truck workshop will be used for refuelling, and repairs on mining

machinery.

Existing non-mineralised, oxide stockpile within the Prospect pit will provide approximately 7,000 to 12,000 t

of material to construct/upgrade portal bench in Prospect pit north prior to mine development.

40


4.6.1 HAZARDOUS SUBSTANCES Diesel requirements for the underground mine will be around 60,000 L/month or 720,000 L/year. Diesel will be stored

at the existing fuel bay (Figure 4-3), which has a 45,000 L aboveground storage tank, and deliveries are expected every

one to two weeks. This storage facility is included in the URPA Hazardous Substances Manifest and Plan submitted to

NT Worksafe in accordance with the guide, Manifest Requirements for Hazardous Chemicals.

NTMO has an existing Safety Management System (SMS) that requires the safe storage and management of hazardous

substances in accordance with applicable legislation, Australian Standards and Codes of Practice. The NTMO

Environmental and Social Responsibility Management System (ESRMS) also includes a Hazardous Substances

Management Plan to guide the safe and responsible use and control of all hazardous materials handled at NTMO sites

and to ensure that spills are appropriately managed.

4.6.2 ENERGY The 310 MegaWatt (MW) Channel Island Power Station is the main source of electricity for the Darwin to Katherine

Interconnected System, which is linked by a 132 kV transmission line. This system is then connected to the Pine Creek

Power Station (26.6 MW) which is independently owned and operated by Energy Development Limited. A 66 kV line

connects the URPA to the Pine Creek system.

To supply electricity for its operations, NTMO has established agreements with the Power and Water Corporation, and

Jacana Energy.

Electricity requirements for the underground operation is estimated at between 750,000 to 1,000,000 kilowatt hours

(kWh) per month or around 9 -12 MW/year. An additional internal power line will be installed to distribute power to

the underground mine from the existing substation located at the processing / workshop / office complex.

4.6.3 RUN OF MINE (ROM) PAD The existing ROM Pad (Figure 4-2) encompasses an area of approximately 5 ha, and is located directly to the north of

the processing plant, adjacent to the western side of the Crosscourse pit. The ROM Pad has been roller compacted to

minimise erosion issues. Run off water reports to Crosscourse pit with a flow gradient of approximately one percent.

An entry access ramp and traffic controls have been constructed on the ROM pad for safe traffic management (Figure

4-5).

During mine operations, the ROM Pad will receive ore from the Prospect decline and from the CHPA. Blended ore will

be fed into the mill, with approximately one week supply of ore stockpiled on the ROM as contingency mill feed.

41


FIGURE 4-5 URPA ROM PAD

4.6.4 PROCESSING PLANT The URPA processing plant is located approximately 1 km from the proposed Prospect underground mine. The plant

will treat blended ore from the Cosmo Underground Mine and Union Reefs North underground mine. The URPA

processing plant recovers gold by gravity concentration and Carbon In Leach (CIL) technology. It has a maximum

capacity of 2 Million tonnes per annum (Mtpa) and can be operated efficiently at a lower throughput rate with the use

of only one of the ball mill circuits.

Water for the processing plant is reclaimed from the Crosscourse pit, and supplemented by raw water from Dam C i.e.

some processing activities (e.g. elution) require a higher quality water.

The processing flow sheet is illustrated in Figure 4-6 below and described in the following sections. The processing

method will be consistent with previously authorised activities (see Table 4-2 above).

Crushing

Mined ore is transported and stockpiled on the ROM prior to being fed by a front-end loader into the three stage

crushing circuit. The crushing circuit has a primary jaw crusher operating in open circuit and secondary and tertiary

cone crushers operating in closed circuit with a double deck banana screen.

Crushing circuit product, at a nominal size of 12 mm is conveyed to the grinding circuit via the Ore Bin. The Ore Bin has

a capacity of 2,500 t and provides a buffer of approximately seven to eight hours between the crushing and grinding

circuits. Ore is fed via a slot feeder at a variable rate and is conveyed to the grinding circuit.

Grinding

Water is added to crushed ore entering the grinding circuit, consisting of two ANI single stage rubber lined ball mills in

parallel configuration. Each ball mill operates in a closed circuit with a nest of Warman cyclones for sizing classification

of the ground ore. The coarse underflow fraction reports back to the ball mill for further grinding whilst the fine

overflow fraction (75 to 106 µm) gravitates to a single high rate leach feed thickener for density control before being

pumped to the first of two leach tanks.

42


Gravity Gold Circuit

The grinding circuit is also equipped with four Knelson gravity concentrators (two per mill) to extract coarse gold. A

small percentage the cyclone underflow slurry is transferred to the Knelson concentrators. The Knelson concentrators

separate the higher Specific Gravity (SG) gold particles from non-gold bearing ore particles centrifugally. Knelson

concentrator tailings report back to the mill discharge stream whilst the concentrated coarse gold is sent into the

Acacia Reactor for further processing.

Leaching and Absorption

Leach feed slurry is pumped into two leach tanks where cyanide is added to put the gold into solution before the

material gravitates into the CIL circuit. High purity oxygen is added into the leach tanks from the Pressure Swing

Absorption (PSA) plant on site. The CIL circuit, comprising of seven leach/adsorption tanks is gravity fed through open

launders.

All seven tanks are aerated and fitted with hollow shaft mechanical agitators. Barren slurry exits from the last CIL tank

and gravitates to the residue treatment circuit. Activated carbon is pumped counter current to the process slurry to

recover gold from solution, achieving the highest gold on carbon loading in CIL tank one. Loaded carbon is pumped to

the elution circuit.

In excess of approximately 90% of all gold is recovered from the ore by the time slurry reaches the final adsorption

tank. The remaining barren slurry is pumped to the Crosscourse pit Tailings Storage Facility (TSF) for final disposal with

reclaimed water being sent to the process water circuit for re-use.

Elution and Gold Recovery

The elution facility recovers adsorbed gold off the loaded carbon into a concentrated gold solution. The gravity

concentrate produced by the Knelson concentrators is transferred into the Acacia Reactor where cyanide solution is

recirculated through the concentrate to produce high gold concentration solution.

The concentrated gold solutions are transferred to the electrowinning cells where the recovered gold is electroplated

onto steel wool cathodes. Periodically, the stainless steel wool is removed from the holding cells and the electroplated

gold is pressure washed into a collection tub.

The electro-won gold and the gravity won gold are calcined in an electric oven and smelted separately in a gas-fired

furnace into doré bullion. Bars are stamped for identification and dispatched via a security service.

Carbon Regeneration

A vertical gas fired carbon reactivation kiln is used to reactivate the carbon after elution. Carbon from the elution

column enters a pre-drier to remove excess of moisture and then fed into eight stainless steel tubes passing through a

combustion chamber. The carbon is exposed to 650 °C to volatilise organic contaminants. Regenerated carbon is

returned to the absorption tanks for reuse.

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FIGURE 4-6 UNION REEFS FREE MILLING PROCESS FLOWSHEET SCHEMATIC

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4.7 Operational Water Infrastructure

A number of the process and mine water dams constructed by previous operators at the URPA will be utilised to

support the project.

The processing plant water circulation process includes reclaim from the Crosscourse TSF, supplemented by raw water

from Dam C, i.e. some processing activities (i.e. elution) require a higher quality water and this is sourced from Dam C.

Prospect pit (North and South) will be completely dewatered prior to portal construction, with only a small dewatering

sump remaining during the operation of the project. Approximately 100 ML of water will be pumped into Crosscourse

pit via a 350 mm diameter pipeline using a 90 kW submersible floating pump.

All waste rock from underground mining will be temporarily stockpiled in Prospect South pit. A small water storage

pond (sump) will be constructed to collect runoff from Prospect South pit, to be pumped into the main water storage

pond in Prospect North pit.

The underground mine is expected to use around 1.5 to 2 L/s for underground drilling and dust suppression,

equivalent to 47 to 63 ML/year. This water will be sourced from Dam C and pumped underground via two 30,000 L

water tanks installed adjacent to the Prospect pit. Underground wastewater and groundwater ingress (7 to 18 L/s, see

Section 8) will also be pumped into Prospect North pit.

Prospect North pit water storage will be dewatered regularly into Crosscourse pit. Prospect North pit water level will

be maintained in a dewatered state to avoid flooding risk of the portal. A flood risk assessment has been completed

and is summarised in Section 8.2.

Tailings from the processing plant will be deposited in Crosscourse pit. The potential impacts of the project on water

volumes in Crosscourse pit are discussed in Section 8.1.6.

The tailings level in Crosscourse pit currently is 123 mAHD (1,123 m RL) and water level is approximately 172 -

173 mAHD. Crosscourse pit capacity in May 2019 is indicated Table 4-4 and Figure 4-8.

TABLE 4-4 CROSSCOURSE PIT FREEBOARD MAY 2019

Total Capacity (ML)

Tails Deposition (ML)

Current Water Volume Above Tails (ML)

Freeboard Capacity (ML)

Freeboard in Metres

29,282 10,190 12,605 6,487 15 m to overflow

45


FIGURE 4-7 CROSSCOURSE PIT CROSS SECTION AND TAILINGS DEPOSITION SCHEMATIC

The water management circuit for the project is summarised in Table 4-5 and Figure 4-8.

Additional information about site water management is detailed in Section 8.

TABLE 4-5 SITE WATER MANAGEMENT

Facility Type Inflows Discharges

Crosscourse pit Pit, tailings storage, recycled water.

Rainfall, groundwater ingress, tailings deposition.

Recycled for use in processing plant, discharge, and groundwater seepage when water level greater than 172-173 mAHD.

(Proposed WDL to discharge treated water to McKinlay River in 2020/2021 wet season).

Prospect pit

Access and dewatering sump for underground mine production.

Rainfall, runoff catchment, pumped water from underground operations and groundwater ingress.

Discharge to Crosscourse pit.

Underground mine

Underground mine.

Pumped Dam C water for mine operations and groundwater ingress.

Discharge to Crosscourse pit.

Dam C Raw water supply dam.

Rainfall, runoff catchment.

Supplementary process water supply, underground mine water supply.

Discharges into Dam A via a constructed drainage line (in above average wet seasons).

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4.7.1 MINE WATER DAMS There are a number of process and mine water dams constructed by previous operators at the URPA (see Figure 4-2,

and represented schematically in Figure 4-8), some of which support the existing authorised NTMO processing

operations and will be used by the underground mine project in a manner that is consistent with existing

authorisations.

Dam C

Dam C is used as a raw water source and will provide supplementary water for the URPA processing plant. Dam C will

also provide water for use in the underground mining operation.

Dam C (previously referred to as Union Reefs upper Water Dam) is situated in the northeast of the URPA. It receives

surface rainfall and catchment runoff from the hilly ridges to the east of the dam, and runoff and seepage from the

east WRD to the south. The total catchment area of Dam C is 173 ha.

Discharge volumes (overflow) from Dam C to Dam A are reflective of seasonal rainfall volumes i.e. passive flow.

Dam B

Dam B acts as a sediment trap and settling pond for overflow runoff from URPA fuel bay and wash-down areas, as well

as surface water runoff and seepage from the southern end of the west WRD.

Any overflow from Dam B flows into sediment trap 3 (located between Dam B and the McKinlay River). Water quality

in this area is monitored at the monitoring point URST3 (Figure 4-8).

Plant Spill Pond

The Plant Spill Pond captures runoff from the processing plant and is the water source for dust suppression around

the processing plant and ROM areas and for the wash-down water/wash-bay.

The Plant Spill Pond is a contingency sump for any chemical or processing spills in the processing area.

Other URPA Surface Water Infrastructure

The following surface water infrastructure, constructed by previous operators and managed by NTMO, will not be

utilised during the underground mining project.

Dam A

Dam A is an historical open pit situated within the northern part of the URPA. The dam receives rainfall and catchment

runoff from the ridges to its eastern and western sides and overtops annually via a spillway to Wellington Creek, with

the water quality monitored at monitoring point URSW01 (Figure 4-8). In previous years, Dam A received overtopping

water from Dam C via a connected drainage line.

Decant Pond

The Decant Pond is located in the south of the URPA. The decant pond receives runoff from the surface of what is

called the Old TSF, via a designed spillway at the south-eastern corner, and from subterranean flow-in from the decant

tower system, which is located in the southern wall of the Old TSF.

Passive discharge from the decant pond occurs during the wet season via a spillway running from the northwest

corner of the decant pond to the McKinlay River, upstream of the McKinlay River Weir Wetlands. This discharge was

monitored and regulated under a previous Waste Discharge Licence (WDL).

Sediment and Wetland Filters

The URPA site rehabilitation included the construction of several sediment traps (sediment trap 3, sediment trap 4A

and sediment trap 5B) to reduce total suspended materials, and wetland filters to assist with attenuation of metals, in

the water.

The majority of surface water runoff and seepage from the west WRD is directed to sediment trap 4A prior to

discharge into a tributary of the McKinlay River. A small portion of surface water runoff sheds to the north entering

Wellington Creek; this is monitored at URSW01.

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McKinlay River Weir Wetlands

Previous operators dammed a portion of the McKinlay River to create an additional area to capture freshwater during

the wet season. Freshwater is no longer sourced from here, and the operation seeks to recycle most of its process

water. The pipeline and pumping infrastructure have been removed, but the area remains a haven for wildlife. Water

discharging from the decant pond spillway enters the McKinlay River upstream of this wetland.

Smaller Open Cut Pits and Facilities

The remaining smaller pits and dams are not within NTMO current disturbance footprint and have maintained

consistent water levels without pumping since 2009. For these reasons, they are not included in the current surface

water monitoring schedule. Spot sampling has taken place in a number of these pits historically, however has been

deemed unsafe due to unstable pit walls.

These include Lady Alice, Prospect, Ping Que South, Union South, Big Tree, Temple, Millars, Union North (tailings

storage), Union North South, Union North southern extension and Union Dam.

Recent monitoring of Prospect pit water levels (2018 to 2019) indicate water level fluctuates between 1,174 Reduced

Level (RL) to 1,179 RL annually.

4.7.2 TAILINGS STORAGE FACILITY Tailings generated from the URPA Processing Plant are deposited into the Crosscourse pit (see Figure 4-8). The use of

Crosscourse pit for tailings deposition is consistent with the current authorisations (Table 4-2).

The Crosscourse pit was mined from 1993 to 2002 when more than 80 Million tonnes (Mt) of material was removed to

a depth of 265 m. The pit has been utilised as the TSF since August 2002. The original tailings deposition method used

from 2002 to 2005 is unclear, but since 2005 tails have been piped and discharged from a single point on the western

perimeter into the Crosscourse pit TSF. Tailings discharge rates are up to 300 tonnes/hour during normal processing

conditions. Current tailings and water volumes are indicated in Figure 4-9.

Pipelines are routinely inspected during tailings discharge to proactively manage pipeline repairs and prevent

potential pipeline failures. If a significant pipe failure did occur, tailings would report to, and be contained, by the

Crosscourse pit or Plant Spill Pond. A water balance for Crosscourse pit during mining operations and post closure is

presented in Section 8. Additional information relating to Crosscourse pit is included in Section 4.7, Operational Water

Infrastructure, and in Section 8, Mine Water Management.

FIGURE 4-9 CROSSCOURSE TAILING VOLUME 3D MODEL

49


4.8 New Infrastructure

Some new surface infrastructure is required to support the proposed underground mine operation. This will be

constructed in previously disturbed areas, but will require the clearing of approximately 1 ha of rehabilitated area (i.e.

clearing of regrowth vegetation). New or upgraded infrastructure (Figure 4-3) includes:

The surface mine ventilation system (0.01 ha) will be installed at surface during mine development.

The haul road (0.2 ha) connecting Prospect Pit ramp to the existing haul road.

Explosives magazine (0.5 ha).

An infrastructure area (0.01 ha) comprising substation, communications hut and two 30,000 L water tanks

with pumps to supply water to the underground operation.

4.8.1 EXPLOSIVES MAGAZINE The project will require the use and storage and use of explosives (Table 4-6). An historical URPA explosives bunker

area will be cleared (Figure 4-10) and fenced prior to installation of an explosives magazine. This facility will be

managed in accordance with the Dangerous Goods Act, which sets out the requirements and allowances for licensing,

packaging, storage, transportation and use of explosives.

The historic URPA explosives bunker area will be upgraded, including:

Road works and clearing regrowth vegetation at the magazine site.

Repaint and install insulation and lining in existing explosives magazine.

Install fencing and signage.

TABLE 4-6 URPA EXPLOSIVES BUNKER STORAGE

Storage Type Substance UN No Class Volume

Tank Diesel 1202 Combustible Liquid 3 45,000 L

Magazine Detonators 0360 1.1 B 5,000 detonators

Magazine Explosives Various 1.1 to 1.6 20 t

FIGURE 4-10 URPA EXPLOSIVES BUNKER AREA

50


4.9 Mine Development

The Union Reefs North Underground Mine will be accessed via a portal and decline developed from within the eastern

wall of the existing Prospect pit (Figure 4-3). The underground portal will be located at 177.5 mAHD. The existing

water level is at 175 mAHD.

Project construction works will be undertaken over a two to three month period and will include the following:

Upgrade existing ramp into Prospect pit.

Utilise existing waste material from within Prospect pit to sheet ramp and construct bench.

Build up bench for access to pit wall at portal location – to prepare and stabilise pit walls for a distance 6 m

high x 15 m wide in preparation for portal access.

Level portal bench area for air compressor, substation, generator set, pumps and tanks, and services for air

and water.

Extend South bench for dewatering access.

Extend North bench and bund for dewatering access.

Install pump and pump line into southern and northern pits.

Prospect north and South pit(s) will be completely dewatered over a period of two to three weeks, with only a small

dewatering sump remaining. Approximately 100 ML water will be pumped into Crosscourse pit via 350 mm diameter

pipeline using a 90 kW submersible floating pumps. There will be no water treatment prior to discharge into

Crosscourse pit.

A new haul road section will be constructed (Figure 4-3) between the Prospect pit ramp and existing ROM pad.

4.10 Mine Production

The underground mine plan includes the development of the orebody to around 220 m below ground surface. This is

similar to the depth of the Crosscourse pit.

Ore will be trucked directly from the portal to the existing Run of Mine (ROM) pad, and then fed into the processing

plant crusher using the existing infrastructure and equipment in place.

Waste rock (291,000 t total) will be placed on the surface in Prospect pit south, and progressively reused to backfill

the stopes from the level above i.e. with waste rock and cement rock fill. This is the same model for waste rock

management as in the CHPA (see Figure 4-11).

51


FIGURE 4-11 TEMPORARY WASTE ROCK STOCKPILE ADJACENT TO THE PORTAL ENTRANCE AT CHPA

The planned underground mining method is a combination of up-hole benching and Avoca stopping, in a three-lift,

bottom-up sequence (see Figure 4-12). This method requires the decline to be advanced at least three levels (i.e.

depth) prior to ore production commencing.

Up-hole benching relies on a combination of Waste Rock Fill (WRF) and Cemented Rock Fill (CRF). Sill pillars will

separate individual stoping blocks. As each block is mined up to a sill pillar, redevelopment below CRF is required for

placement of backfill in a sequence of three lifts commencing bottom up for each block (Figure 4-13). The Cosmo

underground development is mined the same way.

Fresh air will enter the mine via the portal and Fresh Air Rise (FAR) while the return air will be drawn up the Return Air

Rise (RAR) system by a fan with a capacity of 150 m3/s. All FARs and RARs will be 4 m diameter while the escape way

will be a series of 2 m diameter rise running from the surface to the lower levels of the mine (see red vertical shafts in

Figure 4-12).

The underground mining production cycle includes the following:

Develop access to the mineralisation via development of the mine decline (i.e. brown in Figure 4-12).

Develop the level access and lode cross cuts (blue in Figure 4-12).

Develop the ore access drives (yellow in Figure 4-12). Ore drives 3 m wide x 5 m high will be developed to

allow for production drill machinery with full electronic boom movement, loaders, installation of ground

support and ventilation ducting.

Establish a slot rise through to the level above. The slot rise is a vertical opening between two ore drives.

Drill long holes for loading of explosive and blasting or rock. Holes are drilled in a fan pattern (blast ring) at

regular intervals along the ore drive. Blast rings usually comprise between three to seven holes. These holes

are then packed with explosive. Blasting impact on the ore (and the noise and vibration impact) is managed

by blast hole design and timing.

Sill pillars are planned to separate individual stoping blocks. As each stoping block is mined up to a sill pillar,

concrete rock fill is required for placement of backfill.

Pick up the ore with a loader and move it to a stockpile for trucking to the surface. Conventional and tele-

remote boggers are used to bog ore (i.e. mucking) until the stope is clean.

Backfill the stope from level above with waste rock and cement rock fill.

Continue retreating to the central access.

52


FIGURE 4-12 UNDERGROUND MINE SCHEMATIC (BROWN = DECLINE, RED = VENTILATION, BLUE = LEVEL ACCESS

AND LODE CROSS CUTS, YELLOW = ORE DRIVES)

FIGURE 4-13 INDICATIVE DIAGRAM – MODIFIED AVOCA STOPING

The current, planned LOM processing tonnes for 2019 to 2023, including from the CHPA, are provided in Table 4-7.

Mining rates will be limited to around 500 t/day of ore from the underground mine. The projected mine production

rate of 17, 000 tonnes per month can be achieved with 60% stope tonnes and 40% development tonnes. This equates

to four operating stopes at a rate of 3,000 t/month and 220 metres/month of ore development.

Approximately 291,000 tonnes of waste rock will be stored within Prospect pit of which approximately 50,000 tonnes

will remain in situ as surface infrastructure i.e. access ramps within the pit, and 241,000 tonnes will be temporarily

stockpiled and progressively returned underground as backfill.

53


TABLE 4-7 URPA PROCESSING TONNES AND OUNCES (SOURCED FROM URPA AND CHPA)

Month Processing Tonnes from

Cosmo Howley Project Area (t)

Processing Tonnes from Underground Mine (t)

Total Processing Tonnage (t)

End December 2019 100,000 100,000

End December 2020 750,000 35,000 785,000

End December 2021 600,000 140,000 740,000

End December 2022 600,000 105,000 705,000

End December 2023 600,000 600,000

4.10.1 BLASTING Blasting for development and production will be required for the underground mine. Blasting times are limited to shift

changes or other times when personnel can be safely removed from the blast area. Underground blasts are smaller

than open pit blasts, requiring much smaller volumes of explosive material. Underground blasting also has lower levels

of vibration, and other potential surface impacts such as dust, airblast and flyrock are eliminated.

Development blasting relates to the excavation of material required to gain access to the orebody and to provide

space for underground infrastructure i.e. pumps, electrical systems etc. Generally, this material is waste rock although

there is some development ore recovered.

Development blasting occurs during the development of the portal, decline and drives required for drilling, ore

extraction and ventilation requirements. The scheduling and progress of development blasting is critical to mine

planning as it provides access to mining production areas. Development blasting will involve approximately one firing

every 12 hours with the blast spread over eight seconds. The maximum charge fired at any point in time will not

exceed 35 kilograms (kg) to minimise vibration.

Production blasting is manipulated electronically and designed to optimise fragmentation and minimise dilution of the

ore. Production blasting will only be required later in the mine life to extract ore from the stopes. Production blasting

will involve one firing every 24 hours with the blast spread over half a second. The maximum charge fired at any point

in time will not exceed 40 kg to minimise vibration.

The project will have the capacity to alter the magnitude, duration, timing and schedule of blasting to minimise

impacts on Ghost bats (see Chapter 11).

4.10.2 MATERIAL CHARACTERISATION Mining operations will expose either waste rock or ore (temporarily in most cases) to the atmosphere where there is

the potential for oxidation of sulphidic material, if present, with subsequent generation of acid and metalliferous

drainage (AMD, also known as Acid Rock Drainage or ARD) or Neutral Mine Drainage (NMD). Waste material includes

rock removed during decline development, and pit wall rock exposed following pit dewatering. Ore material includes

ore mined for processing and process wastes (tailings) and residual ore remaining in stopes following removal of the

ore. Generation of AMD (or ARD) and/or NMD has the potential to impact water quality in water storages at URPA and

in nearby waterways.

Waste rock will be placed in-pit in Prospect pit south, and then progressively returned underground to backfill stopes.

Approximately 291,000 t of waste rock will be stored within Prospect South pit of which approximately 50,000 t will

remain in situ as in-pit surface infrastructure (access to waste dump for reclamation of waste backfill) and 241,000 t

will be temporarily stockpiled and progressively returned underground as backfill. A small water storage pond (sump)

will be constructed to collect runoff from Prospect South pit, to be pumped into the main water storage pond in

Prospect North pit.

Material used to construct the portal ramp and bench area will be oxidised rock sourced from the pit (Section 4.9) and

will remain in place after mining ceases. The further 50,000 t of waste rock used for portal development which will

also remain in-pit post-mining, will be “first cut” rock from the decline development. This material will be sourced

54


from the oxidised profile. Geochemical testing of oxide material indicates that it is non-acid forming. Therefore, portal

development waste which will remain permanently in-pit is not expected to adversely change groundwater quality

through the generation of acid from oxidising sulphides.

The Prospect deposit at Union Reefs occurs within the Burrell Creek Formation, with the host rock primarily

comprising greywacke interbedded with shale. The gold mineralisation occurs within a variety of quartz-carbonate-

sulphide vein settings. Sulphides (pyrite, pyrrhotite, marcasite, sphalerite and galena) are often associated with the

gold mineralisation.

Appendix F provides a summary of previous geochemical test work conducted by EGi at the URPA, a detailed outline

of the test program currently being conducted, and preliminary results from the current testwork.

Static and kinetic testwork on material from the URPA by EGi (1993 to 2011, Appendix F) indicates that the risk for the

deposits at Union Reefs may be arsenic and metal (e.g. zinc and lead) leaching, rather than ARD, due to the elevated

arsenic in waste rock and ore, relatively low sulphur (S) in the samples tested, and moderate acid neutralising capacity

in fresh waste rock. Preliminary results from recent geochemical testwork indicate that the majority of materials to be

extracted from the Union Reefs North Underground Mine development will be NAF with low Arsenic (As). Arsenic

appears to be elevated primarily proximal to quartz veining, as is the sulphur distribution, supporting the observation

that elevated arsenic zones correspond to elevated sulphur zones. This is often the case whereby arsenopyrite is an

accessory gangue sulphide in quartz-gold mineral assemblages.

The current geochemical characterisation program involves a combination of standard and specialised testing carried

out on samples representing waste rock, low grade ore, and ore. All samples are being analysed for pH and electrical

conductivity (EC) on water extracts, Acid Neutralising Capacity (ANC), Net Acid Producing Potential (NAPP) and single

addition Net Acid Generation (NAG) on solid samples. Following completion of the preliminary geochemical tests, a

selected sub-set will be subjected to static specialised testing to help resolve any uncertainties in classification and

provide more information on geochemical characteristics. Specialised tests will include more detailed sulphur

speciation, kinetic NAG, Acid Buffering Characteristic Curves (ABCC), sequential NAG, and multi-element testing of

water extracts and NAG liquors. This testing will better define total acid generating capacities, relative re-activities of

sulphides and neutralising components, and ARD and NMD chemistries. A particular focus of the specialised

geochemical testing will be to understand the metal/metalloid leaching properties of the both the development waste

and ore samples.

These results will provide input data for the geochemical water quality prediction modelling to be carried out as a part

of additional work being conducted for the current EIS. The results of this work will be reported separately.

4.10.3 PROCESSING Processing is described in some detail in Section 4.6.4. Tailings slurry is pumped to the Crosscourse pit TSF. The

underground mine will contribute 276,000 t of tailings solids to Crosscourse pit. Process water is recycled back from

the Crosscourse pit.

Tailings water composition was recorded during mining of Crosscourse pit (Australian Tailings Consultants, 2003) as

typically slightly alkaline (pH range of 7.5 to 8.5) with Total Dissolved Solids (TDS) in range of 200 to 400 mg/L. Sodium,

Calcium and Magnesium cations are equally represented and the dominate anion is Sulphate. Electrical conductivity

(EC) was reported as less than 500 μs/cm. Elevated Arsenic, Cadmium, Antimony, Lead, Sliver, Sulphur, Tungsten and

Zinc have been recorded in tailings.

55


4.10.4 EQUIPMENT AND VEHICLES Ore will be hauled via the decline and the haul truck route directly to the existing ROM stockpile adjacent to the

processing plant. It is estimated that there will be 12 haul truck loads per day to the surface during the first ten

months and then 27 truckloads per day as ore production increases. It is expected that the required minimum

equipment will include:

1 x electric/hydraulic two boom jumbo

1 x electric/hydraulic production jumbo

1 x 14 t loaders

2 x 42 t diesel haul trucks

1 x agitator truck (as required)

1 x grader (as required)

2 x integrated tool carriers

Other miscellaneous equipment (i.e. light vehicles, site bus)

It is expected that a single site bus will be required to transport site staff to/from the existing Pine Creek

accommodation village at each shift change.

4.10.5 WORKFORCE Workforce numbers will ramp up from decline development to mine production. It is anticipated that over the decline

development period (i.e. the first three months) 16 to 20 employees will be required. As production and stopes come

on line, the mine production workforce will reach approximately 80 people working dayshift/nightshift on a two

weeks on/two weeks off roster.

4.11 Alternatives

The Union Reefs North Underground Mine has been designed to target the Prospect claim deposit. Given the location

of adits within Prospect pit, NTMO did consider an alternative portal location within the Lady Alice pit (Figure 4-14).

The Lady Alice pit portal would be located at the 158 mAHD, i.e. lower in the weathering profile and is potentially

more geotechnically stable, however this could only be confirmed once water is removed from the Lady Alice pit. The

lower portal depth also means that there is potentially less decline development required to access the ore.

The Lady Alice pit currently contains 308 ML water storage and this water would be required to be transferred prior to

mine development. The initial water transfer of 308 ML would be directly into the Crosscourse pit. Lowering the water

level in the Lady Alice pit would be a priority to undertake further technical assessment to confirm the alternative

portal location prior to the commencement of development.

While the Lady Alice pit decline location remains a viable alternative, it is not the preferred location given:

The larger volume of water to be transferred from this pit (300 ML compared to 100 ML in the Prospect pit).

The geotechnical condition of the walls cannot be fully assessed to confirm the portal design requirements

until the water is removed.

Waste rock from a Lady Alice portal would still need to be temporarily stored in the Prospect pit for later

reuse as underground backfill. Lady Alice pit does not have adequate space to store this material. There

would be a requirement to cut and fill a new access ramp into the Lady Alice pit for the surface transfer of

ore and waste rock. The Prospect pit (South) is around 500 m from the Lady Alice pit and the alternative

portal location would result in an increase in surface vehicle movements for the transfer of waste rock into,

and later out of, the Prospect pit.

56


The potential portal locations at Lady Alice are problematic due to:

o Access heading south would mean the decline starts within the mineralised zone and therefore

would sterilise potential future ore, i.e. this ore zone isn’t yet fully understood. Several new

mineralised zones have been defined in the overall Lady Alice mineralised zone through new drilling.

These are discontinuous but potentially economic, and more drilling is required to fully understand

the location of these zones. It is better to drill this material from underground where the base of the

pit could be targeted, this is geometrically hard to drill from surface due to the low angles of drilling

required, and the Company does not want to have a decline in this area before they know where the

ore is located.

o Access into the western wall would put the portal into potential unstable geotechnical conditions

(Figure 4-15) i.e. the western walls of pit at Union Reefs have had a history of failures, including a

significant western wall failure that occurred in Crosscourse pit in 2000. This historic information is

well documented in the closure reports for Open Pit Mining completed by AngloGold in 2004. It is

noted in the closure report that “The presence of joint sets and sub-horizontal shears can be a

geotechnical problem, particularly below water level. The less competent shale bands tend to

absorb water and disintegrate, allowing freedom of movement for a sliding or toppling failure. This

has been a common occurrence at URGM along the west walls of numerous pits. This highlights that

an underground mine portal needs to be located in the east, north or south walls of the open pits for

safety reason.

o The north and east walls are challenged by topography i.e. the surrounding ground surface is

significantly lower than the pit wall ramp on the western wall (Figure 4-16).

o A decline located in either the eastern or northern walls would head in the opposite direction to the

ore zones.

NTMO also considered a box cut operation (Figure 4-17) i.e. open cut to the east of the proposed decline location in

Prospect pit, however such an operation would require significantly more ground disturbance than establishing the

decline within an existing pit, given it would need to cut into oxide material higher up in the mining sequence.

Prospect pit provides access to the processing plant using already established haul routes and infrastructure. If the

decline was located at either a box cut site, or Lady Alice pit, then significant additional ground disturbance would be

required.

Also, in using box-cut from surface to access an underground mine, there is a higher risk of flooding during a

significant weather event. Locating the portal within an existing pit means that significant rainfall events can be

captured in the pit to prevent water inrush. Whereas the box cut would need to be mined to a depth where fresh rock

is available, and this would require a significant excavation, which would act as a water trap for significant rainfall

events.

The location for a box-cut, away from the adits, would require a significant distance of mining which would make the

mine uneconomic to build. It is estimated that the additional development costs would be in the order of $2.8 M on

top of the current mine plan, including costs associated with mining and ground support for the box cut, additional

underground development and additional haul road development. These additional development costs are not

sustainable.

!

!!

!

!

Alternative Box Cut

Magazine

Workshop/ Office

Fuel Bay

RoM Pad

Haul

Truck

s Rou

te

801000

801000

801500

801500

802000

802000

8482

000

8482

000

8482

500

8482

500

8483

000

8483

000

8483

500

8483

500

!(

!(PINE CREEK

ADELAIDE RIVER

Date:11 November 2019

Projection:GDA 1994 MGA Zone 52

Union Reefs Project Area Lady Alice Alternative

Portal Location

Document Path: G:\GIS\Environmental\Projects\Contractors\URPA EIS 2019\A2 Lady Alice Alternative Portal.mxd

Legend! Adits! Alternative Portal (Lady Alice)

Alternative Haul RouteLady Alice Mineralisation

¯0 100 200

Metres

Figure 4-14

58


FIGURE 4-15 LADY ALICE PIT WESTERN WALL

FIGURE 4-16 LADY ALICE PIT EASTERN WALL

59


FIGURE 4-17 BOX CUT TO THE EAST OF PROSPECT PIT

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5 APPROVALS AND REGULATORY FRAMEWORK

5.1 Overview

KLG is committed to compliance with statutory requirements, industry standards, guidelines and codes of practice and

has developed an effective Environment and Social Responsibility Management System (ESRMS). The strategic focus

of the ESRMS is to continually minimise environmental and social impacts. The policies that inform the ESRMS are

detailed in Section 3.4.

KLG identifies and tracks statutory and other requirements applicable to its activities, and the NTMO management

team are responsible for ensuring that all site employees and contractors:

Comply with all laws, conditions of any permits, licences and authorisations or any NTMO standards,

management plans and procedures applicable to their activities.

Work safely, protecting people, environment and community.

Identify any hazards or risks associated with their work and implement appropriate controls.

Report and rectify any observed acts, incidents or hazards that could negatively affect people, environment

and community.

5.1.1 COMMONWEALTH LEGISLATION A number of pieces of legislation under the Commonwealth Government are relevant to the project. These, along with

associated approvals and the context in which they apply to the project are detailed in Table 5-1 below.

TABLE 5-1 COMMONWEALTH LEGISLATION

Legislation Licensing and Approvals Context

Aboriginal Land Rights (Northern Territory) Act 1976

N/A

An Act to regulate exploration and mining on Aboriginal land and set out the processes to be followed when negotiating with Traditional Owners for access to, and leases over, Aboriginal land.

The Land Rights Act also mandates the protection of sacred sites irrespective of whether the site is located on Aboriginal land.

URPA is within the administrative boundary of the Northern Land Council (NLC) but is not located on Aboriginal land.

Environment Protection and Biodiversity Conservation Act 1999

Formal referral and assessment of the project given the proposed impact on Macroderma gigas (Ghost bat) habitat (temporary adit closure) – Listed as vulnerable under the EPBC Act.

An Act relating to the protection of the environment and the conservation of biodiversity, threatened species and related purposes.

The project has been declared a controlled action under the EPBC Act, with regard to listed, threatened species (Appendix G, Chapter 11) and will be assessed under the bilateral agreement between the Northern territory and Australian Government.

National Environment Protection Council Act 1994

NTMO annual reporting for the URPA is in accordance with the requirements and NEPM thresholds outlined in the Act.

The Act has powers to make National Environment Protection Measures (NEPMs) and sets national standards for air, water and noise quality as well as waste and contamination.

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Legislation Licensing and Approvals Context

National Greenhouse and Energy Reporting Act 2007

NTMO annual reporting for the URPA is in accordance with the requirements of the National Greenhouse and Energy Report Scheme.

Corporations must register and report if they emit Greenhouse Gases (GHG), produce or consume energy at or above specified quantities in a given financial year.

GHG emissions and energy consumption are detailed in mine management planning for the site and is reported separately under the National Greenhouse Energy Reporting (NGERS) framework.

Native Title Act 1993

N/A

The Act applies to native title in relation to land or waters, objectives relevant to the URPA are to provide for the protection of native title.

Mary River West Station, including the URPA is subject to a Native title claim.

5.1.2 NORTHERN TERRITORY LEGISLATION The Northern Territory Government has jurisdiction over environmental and other legislation relating to the siting,

construction and operation of the Union Reefs Underground Mine Project. A number of pieces of legislation are

relevant to the project. These, along with associated approvals and the context in which they apply to the project are

detailed in Table 5-2 below.

TABLE 5-2 NORTHERN TERRITORY LEGISLATION

Legislation License, Approval or Permit Context

Bushfires Management Act 2016

In the event controlled burning is required, NTMO will seek a permit through Bushfires NT.

The URPA is situated outside the emergency response area, and fire management is required to prevent impacts on property, industry and environment.

Control of Roads Act 1953

NA No roads will be opened or closed as a result of construction or operations for the project.

Dangerous Goods Act 1998

A licence to possess, store and/or sell explosives will be required for the URPA Explosives Magazine.

Individual Shotfirers will be licenced in accordance with the Act.

The storage and transport of explosives requires an approval to be obtained from Worksafe NT.

Electricity Reform Act 2000

Certificate of compliance. The Electricity Reform Act regulates the electricity supply industry and provides for the establishment of safety and technical standards for electrical installations.

Agreements with Power and Water Corporation (PWC) and Jacana Energy have been established.

Energy Pipelines Act 1981

NA Provides for the construction, operation, maintenance and end of life activities of pipelines for conveyance of energy-producing hydro-carbons and related purposes. Gas pipeline (No. 203267) also runs through MLN1109.

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Environmental Assessment Act 1982

Approval by Minster of Environment and Natural Resources.

In June 2019, NTMO submitted a Notice Of Intent (NOI) to the Northern Territory Environmental Protection Agency (NT EPA) for consideration under the Act. It was decided that the project required assessment under the Act. Subsequently, this draft EIS is submitted to the NT EPA for assessment in accordance with relevant legislation and the requirements of the Act and the associated Act Administrative Procedures.

This Act is yet to be superseded by the Environmental Protection Act 2019.

Heritage Act 2011 Work approval. Provides a system for the identification, assessment, protection and conservation of the Northern Territory’s natural and cultural heritage.

There are several sites on the NT Heritage Register within URPA and these are detailed in the existing URPA Archaeological and Heritage Register.

Mineral Royalty Act 1982

N/A The Mineral Royalty Act 1982 imposes royalties on minerals recovered in the Northern Territory and will apply to the project.

Mineral Titles Act 2010

MLN1109 granted on 16 December 1993 and expires on 31 December 2034.

Department of Primary Industry and Resources (DPIR) oversees the approval and regulation of mining activities under the Act. NTMO will abide by any specific conditions or requirements described in the grant documents of tenements under the Act.

Mining Management Act 2001

See Section 4.2 that summarises existing authorisations.

The Act and the Mining Management Regulations regulate mining activities and the management of mining sites. The legislation is administered by the DPIR and is the primary regulatory instrument for NT mining projects. URPA Mine Management Plan (MMP) authorisation required as pursuant to the Act.

A URPA MMP Amendment will be submitted to the DPIR to incorporate the Union Reefs North Underground Mine.

Northern Territory Aboriginal Sacred Sites Act 1989

AAPA Certificate C2009/267 for the URPA was granted on 8 October 2009.

The Aboriginal Areas Protection Authority (AAPA) have issued Aboriginal sacred site clearances for URPA. There are no currently registered or recorded sites in the project area.

Public and Environmental Health Act 2011

NA Approvals for onsite waste water management systems at URPA are already in place under the Act and Public and Environmental Health Regulations (PEHR).

Soil Conservation and Land Utilisation Act 1969

NA This Act provides for the prevention of soil erosion, and for the conservation of soil, and requires an Erosion and Sediment Control Plan (ESCP) to be prepared for development projects.

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Territory Parks and Wildlife Conservation Act 1976

Pursuant to Section 56, Permit to take or interfere with threatened wildlife.

The Territory Parks and Wildlife Conservation Act 1978 (TPWC Act) protects Northern Territory parks and reserves, animals and plants (including wildlife and protected wildlife).

Permits will be sought for proposed Ghost bat management strategy actions.

Transport of Dangerous Goods by Road and Rail (National Uniform Legislation) Act 2010

Pursuant to Part 8, Section 3 of the Act all approvals specified by the Authority will be sought.

This legislation applies to the project as dangerous goods will be handled and transported during construction and operation of the project. The appropriate licences will be acquired and the legislation adhered to.

Waste Management and Pollution Control Act 1998

Pursuant to Schedule 2 of the Act, Environmental Protection Approvals and/or Licences.

Required for construction and operation of facilities that store listed wastes, encouraging effective and responsible waste management and reduction and response to pollution.

General and hazardous wastes will be removed from site by a licensed contractor. Pursuant to Section 14 of the Act appropriate pollution incident notification procedures will be put in place.

A Waste Discharge Licence (WDL) is required for URPA passive discharge.

Water Act 1992 Nil required. The Act provides for the allocation, use, control, protection, management and administration of water resources. Mining is no longer exempt from the Water Act and Proponents may be required to seek a licence to extract surface or groundwater under the water Act.

Under the Water Act beneficial uses or values have been set for major aquifers and river catchments. These values are then used to set water quality target. There is a Beneficial Use Declaration (BUD) for the McKinlay River adjacent to the project area. The beneficial use is aquatic ecosystem protection. As outlined in the URPA MMP, NTMO has an existing, ongoing water quality monitoring program.

Weeds Management Act 2001

N/A Occupiers of land (including mine sites) have an obligation to ensure listed weeds are not introduced or spread.

Weed management, including Weeds of National Significance (WoNS) is addressed in the URPA MMP and adheres to the NT Government NT Weed Risk Management System.

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5.1.3 POLICIES AND GUIDELINES

Northern Territory Environmental Protection Authority Assessment Guidelines

The NT EPA issues assessment guidelines to assist proponents in understanding and complying with the information

requirements for the environmental impact assessment process.

The guidelines relevant to the project are:

General Guidance for Proponents preparing an Environmental Impact Statement

Guidelines for the Preparation of an Economic and Social Impact Assessment, 2013

Guideline for the Preparation of an Environmental Management Plan, 2015

Environmental Assessment Guidelines on Acid and Metalliferous Drainage, 2013

Guidelines on Conceptual Site Models, 2013

Guidelines for Assessment of Impacts on Terrestrial Biodiversity, 2013

Guidelines for Consultants Reporting on Environmental Issues

Guidelines on Environmental Offsets and Associated Approval Conditions, 2013

This draft EIS and all the appendices have been prepared in accordance with the relevant guidelines.

Mine Closure Guidelines

Guidelines for Preparing Mine Closure Plans (Western Australia Department of Mines and Petroleum, 2015)

Guidelines on Mine Closure and Completion and Mine Rehabilitation published in November 2006. NTMO

understands that these documents have been withdrawn and are being updated. In the absence of NT

guidelines, the Western Australia ‘Guidelines for Preparing Mine Closure Plans, May 2015’ are used. The

content and scope of the Mine Closure Plan follows the requirements of the WA guidelines.

Integrated Mine Closure – Good Practice Guide (ICMM, 2019).

Tailings Management Guidelines

Tailings Management – Leading Practice Sustainable Development Program for the Mining Industry

(Department of Foreign Affairs and Trade 2016).

Other Guidelines

Other guidelines that may be applicable to the project include:

Department of Sustainability, Environment, Water, Population and Communities Survey Guidelines.

Department of the Environment, Significant Impact Guidelines.

The Australian and New Zealand Environment Conservation Council (ANZECC), Guidelines for fresh and

marine water quality Australian National Committee on Large Dams Incorporated.

Mineral Council of Australia’s 2014 Water Accounting Framework for the Minerals Industry.

Northern Territory Department of Health 2014 Environmental Health Fact Sheet 700 Requirements for Mining

and Construction Projects.

The Department of Land Resource Management (DLRM) Guidelines and Field Methodology for Vegetation

Survey and Mapping.

Department of Health Guidelines for Preventing Mosquito Breeding Sites Associated with Mining Sites.

Preventing Acid and Metalliferous Drainage, Leading Practice Sustainable Development Program for the

Mining Industry (DITR 2016).

The Global Acid Rock Drainage Guide (INAP 2011).

Department of Foreign Affairs and Trade, 2009, Airborne Contaminants, Noise and Vibration – Leading

Practice Sustainable Development Program for the Mining Industry.

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5.1.4 KLG POLICIES

KLG believe that strong governance improves corporate performance to the benefit of all stakeholders. They

continually review and improve our practices to achieve higher standards of corporate governance. Their corporate

polices with respect to health, safety, environment, sustainable development and community development issues, as

well as in managing any risks related to these issues, can be viewed at https://klgold.com/about-

us/default.aspx#policies

Environmental Policy

KLG is committed to the integration and promotion of sustainability into all facets of our Company by implementing

responsible environmental practices throughout every level of our business. KLG recognises that effective

environmental management is critical to a successful future. To promote our commitment to Environmental

Management, KLG endeavours to:

Meet or exceed applicable laws and regulations, and licenses.

Develop and maintain a comprehensive and effective Environmental Management System.

Integrate environmental, social, cultural and economic considerations.

Foster mutually beneficial environmental partnerships with our communities.

Conduct business in a manner that minimises potential environmental impacts.

Instil a behaviour of environmental performance responsibility.

Seek continuous improvement in the management and use of resources in environmentally sustainable

exploration, mining, processing, waste management and rehabilitation.

Communicate openly and honestly with respect to the Company’s performance in a timely manner.

Maintain appropriate and effective communication with stakeholders.

Provide for the reclamation and rehabilitation of areas affected by our operations.

To fulfil our commitment to the environment, we will aim to continually improve our environmental performance by

regularly:

Reviewing objectives and targets.

Evaluating our environmental risks and taking steps to mitigate them.

Measuring and reporting performance transparently against objectives and targets.

Communicating this policy to our employees, contractors, suppliers and visitors while also making it available

to the public.

Workplace Health and Safety Policy

KLG is committed to providing a safe working environment for all of our employees, contractors, suppliers and

stakeholders.

KLG strives to provide a zero-harm working environment through the development of our integrated health and safety

management system based on continuous improvement. As part of our commitment, KLG will:

Never compromise on any of our safety values.

Meet or exceed all applicable laws and regulations, and NTMO company standards.

Work together with our employees in the development and implementation of standards.

Integrate health and safety into all aspects of our operational decisions and activities.

Establish relevant and measurable indicators to determine organisational performance.

Promote healthy lifestyles through appropriate awareness and training, fitness for work standards and

occupational health programs and benefits.

Communicate openly and honestly with respect to the Company’s performance in a timely manner.

Maintain high expectation of our employees, contractors and suppliers to work in a safe manner.

To fulfil our commitment to health and safety, we will aim to continually improve our performance by regularly:


https://klgold.com/about-us/default.aspx#policies

https://klgold.com/about-us/default.aspx#policies

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Engaging with our employees and stakeholders to improve and implement our integrated health and safety

management system.

Identifying and managing health and safety impacts, risks and opportunities.



to the public.

Social Responsibility Policy

KLG is committed to making a positive impact by creating meaningful opportunities for our employees and local

suppliers, and by facilitating lasting improvements in the communities in which we operate.

KLG believes that Social Responsibility is essential to operational and financial success and is committed to developing

relationships based on open and honest communication with our stakeholders. To further our commitment to Social

Responsibility, NTMO endeavours to:

Meet or exceed all applicable laws, regulations, and NTMO company standards.

Acknowledge cultural and other human rights and ensure all levels of the workforce understand and respect

such rights.

Integrate social responsibility into our decisions and activities.

Act ethically and respectfully regarding Indigenous rights, cultural beliefs and aspirations.

Understand, encourage and promote cross-cultural awareness.

Engage our stakeholders regarding their values in connection with the development, operation and closure of

mineral projects.

Communicate openly and honestly with respect to the company’s performance in a timely manner.

Maintain ongoing dialogues based on transparency, respect and good faith.

To fulfil our commitment to social responsibility, we will aim to continually improve our performance by regularly:


Engaging with our employees and stakeholders to find improvements that benefit both local economic

development and our shareholders.

Identifying and managing significant social impacts, risks and opportunities.



to the public.

5.1.5 AUSTRALIAN STANDARDS The Australian Standards (AS) that are applicable to the project include:

AS/NZS 4801:2001 Occupational health and safety management systems – Specification with guidance for

use.

AS/NZS ISO 31000:2009 Risk Management.

AS/NZS ISO 31000:2009 Risk Management – Principles and guidelines.

5.1.6 NON-STATUTORY OBLIGATIONS KLG endeavours to work closely with all project stakeholders to satisfy common interests and operates with the

guidance of the non-statutory organisations including the following:

KLG is a Member of the World Gold Council.

KLG is a member company of the Minerals Council of Australia (MCA), and as part of this membership is

committed to the principles of “Enduring Value – the Australian Minerals Industry Framework for Sustainable

Development”; and annual reporting of water usage using the MCA Water Accounting Framework.

NLC.

Fire and Emergency Response Groups.

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6 STAKEHOLDER ENGAGEMENT AND COMMUNITY NTMO is committed to focusing on sustainable development and working with employees, their families, and its local

communities to improve quality of life in a way that is good for both local economic development and shareholders.

The planned mining operations at the URPA will provide additional opportunities for NTMO to support local

employees, businesses, contractors and community groups.

The NTMO operations have brought increased employment and business to Darwin and surrounding regional towns

through a demand for goods and services. Since 2009, NTMO (and the previous CGAO) has spent more than

$300 million (M) with NT businesses including more than $30 M in the Pine Creek region. This year alone the company

has spent $150 M in project development works.

NTMO employs a range of permanent and casual employees, as well as contractors and specialist consultants. The

workforce requirements include managers, supervisors, operators, miners, geologists, engineers, surveyors,

environmental scientists, safety advisors, maintainers, electricians and various contractors. Most staff are based at the

Cosmo Howley Project Area (CHPA) offices and commute to the URPA when required. NTMO also has an

accommodation camp at Pine Creek (for URPA staff) and an office in Darwin for some support services staff (i.e.

Finance and Human Resources).

The majority of NTMO Employees and Contractors are accommodated at the Cosmo Village Camp and Pine Creek

Camp, however some local personnel opt to reside in private residences within the region and commute to site. The

Cosmo Village consists of 296 rooms, a pool, gym, recreational areas, wet mess, a fully catered dry mess and barbeque

facilities. Personnel such as specialist consultants or contractors may also be accommodated at commercial businesses

in Darwin or regional locations.

Employing locally, when the local workforce has the required skills or has the ability to acquire the required skills, is an

objective of the NTMO Consultation and Socio-Economic Management Plan. The current workforce is 60% NT local

and 20% female. In order to increase local capacity, NTMO have dedicated training personnel to upskill local

employees to meet the needs of the operation and have an apprenticeship programme for fitters and boilermakers.

NTMO is also working to make available opportunities for indigenous employment and has partnered with two local

indigenous employment agencies e.g. on the Chinese 2 backfill project at CHPA.

Undergraduate environmental scientists including those from the Charles Darwin University are employed during

semester breaks to assist with environmental management programmes over all NTMO project areas. In some cases,

undergraduate students have remained employed with NTMO whist completing studies and moved into graduate

environmental positions.

NTMO currently has around 400 employees and contractors supporting its operations. It is anticipated that with the

recommencement of CHPA mining production and URPA processing and mining operations, there will be more than

480 personnel.

6.1 Consultation

Consultation with NTMO stakeholders regarding site activities is important at all operational stages from exploration

to mining to mine closure. The NTMO Management Team are focused on developing relationships and maintaining

regular communication with our stakeholders to ensure ongoing support for our operations.

Open communication with relevant government departments is ongoing through meetings, site inspections, approval

applications, formal reports and written communications. Key government agencies include the DPIR, Department of

Environment and Natural Resources (DENR), NT EPA, NT WorkSafe and Bushfires NT.

The NTMO management team maintains regular communications with community leaders and local pastoralists; and

continues to develop these relationships, through both formal meetings and informal discussions. Members of

NTMO’s team participate in many local community groups, such as sporting club committees and local environmental

teams, as well as holding positions on committees like the Minerals Council of Australia NT Branch.

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Staff from NTMO, and the broader NTMO group, are also active with presentations to local Northern Territory based

annual technical conferences. This includes the Annual Geoscience Exploration Seminar (AGES) conference held by the

Northern Territory Geological Survey (NTGS) in Alice Springs, and the Mining the Territory conference in Darwin.

NTMO maintains a Consultation and Communication Log and Complaints Register for all of its operations. Any

complaints received are documented and fully investigated with communication made with the complainant (as

required) to outline actions taken or gain further understanding of the nature of the complaint. A review of the

complaints register and historical MMPs indicates that no formal complaints have been received since records began

in 2009, regarding activities at the URPA.

To date consultation regarding the commencement of underground mining activities outlined within this draft EIS has

primarily been through meetings, site visits and discussions with Government and community stakeholders (Table

6-1).

TABLE 6-1 STAKEHOLDER CONSULTATION

Date Organisation

/ Stakeholders

Key Issues Raised Format of

Consultation

Follow Up / How Issues will be Addressed

Further Work Required

September Mary River West Station Manager -Martin Gschwenter

Showed the location of the Underground project. Discussed Ghost bat habitats in adits. Looked at suitable option sites for stockyards and water sources for stock. Showed active exploration drilling areas.

Site visit face to face and tour around UR site.

Discuss areas suitable for stock yards and perimeter fencing. Bore monitoring, bore to be used for stock watering.

Provide bore water quality results.

13-Sep Jawoyn Liaison committee

Regional Liaison Committee meeting and discussed project.

Liaison Committee face to face meeting around the Esmeralda agreement but used as a platform to keep TO's up to date on company activities.

Additional meetings to be held. Interested to be involved with the Ghost bat regional research project and jobs.

Ongoing liaison with Jawoyn Liaison committee to keep informed on project and Ghost bat regional research project.

Discussions from Jul to Nov 2019

Victoria Daly Regional Council - Jocelyn Moir (Council Service Manager, Pine Creek)

Ghost bat regional research studies, Reopening of Pine Creek camp to service Union Reefs Mill and project. Water use issues at camp and social inclusion into township.

Phone call discussions and face to face meeting at Council office.

Water management at Pine Creek. Policy for no hi viz after work hours around the township.

Ongoing liaison with Victoria Daly Regional Council regarding Pine Creek camp, water management and social performance.

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Date Organisation

/ Stakeholders


Consultation



9-Oct Minerals Council Australia - NT Division

EIS, NT Operational plan update.

Conversation with MCA-NT Executive Director.

Request for further updates on progress of EIS under new act.

Ongoing liaison as required.

29-Oct PNX Metals - JV Partners on other projects

EIS work underway. Conversation with James Fox (CEO).

Nothing. Ongoing liaison as required.

24-Oct DPIR EIS and MMP for project.

Meeting with Andria Handley.

Process for MMP with respect to current MMP.

Additional meeting to be organised at a later date.

13-Nov Local MLA - Gary Higgins

Provided overview of UR project and key issues.

Face to face communication on new project whilst at the UR mill re-opening.

No follow-up. Provided date for EIS submission.


13-Nov Minister for Mines, Paul Kirby

Provided overview of UR project and key issues.

UR Mill reopening and site visits to the UR Project area and discuss key issues to be addressed in EIS.

No follow-up. Provided date for EIS submission.


Aug and Nov 2019

Charles Darwin University

Development of MoU with regard to the Post-Doctoral Ghost bat research and other, support for undergraduates and post graduate support projects with CDU.

Various Face to Face conversations at CDU and KLG office Darwin, Sam Banks.

Development of MoU and to develop research programme with the University.

Ongoing liaison to work with research programme, undergraduate and post grade projects.

25 Oct 2019

DIPL Transport

EIS development for underground mine and Public road network impacts.

Meeting between NTMO and the Department (Mike Tait and Kushan Gunarathne).

NA

TBC NT Worksafe

TBC Power and Water

TBC APA

TBC Bushfires NT

TBC Telstra

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Date Organisation

/ Stakeholders


Consultation



TBC Coomalie Shire

TBC Adelaide River community

TBC NT Pastoral Board

TBC Genesee Wyoming Australia

TBC Police and Emergency Services

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7 EXISTING ENVIRONMENT The sections below provide a brief description of the environmental context in which the project is located. More

detailed information relating to specific environmental factors is located in:

Chapter 11: Terrestrial Flora and Fauna

Chapter 12: Hydrological Processes

Chapter 13: Inland Water Environmental Quality

Chapter 14: Aquatic Ecosystems

7.1 Bioregional Description

URPA lies within the Pine Creek bioregion (Figure 7-1), which is characterised by the highly mineralised Pine Creek

geosyncline comprising Archaean granite and gneiss overlain by Palaeoprotozoic sediments (Baker et al, 2005). The

landscape is described as stony foothills and is dominated by tall open forests dominated typically by Darwin

Woollybutt Eucalptus miniata and Darwin Stringybark Eucalyptus tetradonta (Baker et al, 2005).

The Pine Creek bioregion is 28,456 km2; being around 2.12% of the NT land mass. Land tenure comprises 41%

aboriginal freehold land, 26% pastoral land. Approximately 42% of the bioregion comprises National Parks or other

protected areas (Baker et al, 2005).

URPA is situated in the upper reaches of the McKinlay River Catchment Area, at an elevation of 230 mAHD. The

project area is located on pastoral land that has carried cattle at low stocking rates, due to the steep slopes and

skeletal soils. The area has been mined since the 1870s (see Section 4.3). Refer to Figure 7-1 for the bioregions

applicable to the project area.

!(

!(PINE CREEK

ADELAIDE RIVER


4

Union Reefs Project Area

PINE CREEKCU

LLEN

RIVE

R

MARY RIVER

HARRIET CREEK

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STRA

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NELLIE CREEK

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WAND

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EEK

NELLIE CREEK

STUART HIGHWAY

KAKADU HIGHWAY

Union Reefs Project Area Bioregional Context

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0 6 12

Kilometres

LegendMLN1109National Parks

Bio RegionDaly BasinPine Creek

Figure 7-1

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7.2 Climate

The climate of the Darwin-Katherine region is broadly classified as tropical monsoonal. It is characterised by seasonal

shifting of the prevailing winds and two distinct seasons, the dry and wet season, with two subsidiary, transitional

periods between them.

The dry season occurs from May to September and is characterised by prevailing south-easterly winds. The transition

period from dry to wet season occurs in October and November and is characterised by high humidity and variable

winds. The wet season occurs from December to March with dominant northwest to westerly winds. The second

transition period, from wet to dry season, occurs in April and has variable winds, with dominant easterlies.

7.2.1 RAINFALL AND EVAPORATION Most rainfall occurs in the wet season, and rainfall averages decrease with distance from the coast. The average

annual rainfall between Douglas Daly-Pine Creek is 1,274 mm, compared to 970 mm for Katherine. Rainfall intensities

are high, which is typical for areas located in the tropical north of Australia. Long term, regional rainfall data is

available from the Bureau of Meteorology (BoM) weather station in Pine Creek, located approximately 12 km

southeast from the URPA. Summary rainfall data over 117 years (BoM, 2019) includes:

The mean annual rainfall for Pine Creek is 1,141 mm.

January and February are the wettest months, with mean rainfalls of 279 mm and 248 mm, respectively.

The highest mean monthly rainfall recorded was 762.6 mm in January 1894 (BoM, 2019).

NTMO monitors rainfall at the URPA (Figure 7-2). Weekly measurements are taken from a rain gauge located at the

site office. For the 12 month period, July 2018 to June 2019, a total of 871.6 mm rainfall was recorded on site. Figure

7-3 provides monthly total rainfall monitored via the URPA rain gauge. It indicates significant variability between

monthly totals, which generally dictate the upper catchment stream and river flows.

Evapotranspiration (Figure 7-4) is at an average of 5.68 mm per day. Total evapotranspiration for the 12 month period

July 2018 to June 2019 was 2,431 mm. Evaporation rate of large water bodies is approximately 60 to 70% of this

evapotranspiration rate.

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FIGURE 7-2 URPA MONTHLY RAINFALL 2013 TO 2019

FIGURE 7-3 URPA SITE RAINFALL 2012 TO 2019

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FIGURE 7-4 URPA EVAPOTRANSPIRATION DATA

7.3 Geology

NTMO operations, including the URPA, fall within the Archaean to Paleoproterozoic Pine Creek Orogen (PCO), one of

the major mineral provinces of Australia. The PCO is a deformed and metamorphosed sedimentary basin up to 14 km

thickness covering an area of approximately 66,000 km2 and extending from the Katherine area in the south to Darwin

in the north (Needham et al. 1988; Ahmad & Munson 2013). It hosts significant mineral resources, as well as

substantial base metals.

Gold mineralisation within the PCO is preferentially developed within strata of the South Alligator Group and lower

parts of the Finniss River Group along anticlines, strike-slip shear zones and duplex thrusts located in proximity to the

Cullen Granite Batholith. Of particular stratigraphic importance are the Wildman Siltstone, the Koolpin Formation,

Gerowie Tuff, Mount Bonnie Formation and the Burrell Creek Formation (Figure 7-5).

The local geology of the URPA is shown in Figure 7-6, and is dominated by the northwest striking Pine Creek Shear

Zone. This zone is a 300 m wide corridor of folded and sheared metasediments that largely comprises the Burrell

Creek Formation and structurally generated inliers of the Mount Bonnie Formation.

The URPA gold deposits follow the Pine Creek Shear Zone and are located on two smaller sub-parallel northwest

mineralisation trends within tightly folded inter-bedded metamorphosed greywackes and shales of the Burrell Creek

Formation. The eastern trend is known as the ‘Lady Alice Line’ and the western trend is the ‘Union Line’ (Figure 2 1).

Mineralisation is associated with quartz-sulphide veining, compromising 1 mm to 2 m thick lode-style veins in sheared

pelites, stockwork veins in greywacke and sheeted vein systems in thinly interbedded pelites and psammites.

The Lady Alice Line mineralisation occurs in a sub vertical shears on the western limb of the large Lady Alice anticline,

and is parallel to the axial plane. Deposits include Millars, Ping Que, Lady Alice and Lady Alice North. The Union Line is

a steeply east dipping shear on which the Union South, Union Central, Prospect and Union North deposits are located.

The previously mined Crosscourse Deposit is the largest known deposit within the Union Reefs area and occurs where

the two trends are proximal to each other.

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FIGURE 7-5 PINE CREEK OROGEN STRATIGRAPHIC COLUMN (HOLLIS, 2012)

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FIGURE 7-6 URPA LOCAL GEOLOGY

7.4 Hydrogeology

The complex lithology and structure in the region results in a similarly complex hydrogeological environment, in which

aquifer characteristics are expected to show significant variation according to lithology, tectonic history, weathering

and recharge conditions.

At the URPA the aquifer system is an elongated north-south trending fractured and weathered rock system associated

with the Union Reefs shear zone. It is around 300 to 500 m wide and extends over many km to the north and south

(Hall, 2018).

Within the main aquifer system, there are two aquifers:

A deep aquifer comprising fresh but fractured and mineralised rock. Within the deep aquifer there will be

further enhanced permeability associated with the main lode systems (Union Line and Lady Alice Line). The

deep aquifer will extend to the base of mineralisation, but permeability will decrease with depth as a result of

geostatic load and reduced mineralisation.

A shallow aquifer associated with weathered (partially to lightly weathered) basement rock. The

mapped/logged depth of weathering (and therefore the base of the shallow aquifer) is around 40 m below

surface. Permeability will be associated with relic fractures/mineralisation and residual rock and will be

comparatively more evenly distributed than in the deep aquifer.

The main aquifer system is bounded to the east and west by low permeability, weakly fractured, fresh and weathered

basement rocks. These would be more appropriately termed aquitards or aquicludes. (AQ2, 2018). The groundwater

present within the project site and in the surrounding study area is described in more detail in Chapter 12 and

Appendix H.

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Groundwater is of a Ca-Mg-Na-HCO3-SO4 type that is reflective of the geochemistry of the bedrock and presence of

sulphide mineralisation. Historically, the groundwater pH has ranged between 6.6 and 7.9, which is within the normal

range for groundwater (6.5 to 8.5). Groundwater quality is discussed in more detail in Chapter 13 and Appendix I.

7.5 Hydrology

The URPA is located within the upper Mary River Catchment (Figure 7-7), an area of approximately 5,600 Km2 south of

the Arnhem Highway including the Pine Creek and south-western Kakadu regions. The upper catchment is

characterised by hilly terrain before levelling out where the McKinlay and Mary River systems form extensive alluvial

plains further north (Napier & Steen, 2002).

The headwaters of the McKinlay River flow northwards along the western edge of the URPA lease and then into the

Mary River some 85 km downstream. The Mary River flows year round, but many of its catchment tributaries,

including the McKinlay River, are ephemeral i.e. flowing only during the wet season.

The two main McKinlay River sub-catchments that drain from the URPA include Esmeralda Creek to the south and

Wellington Creek to the north (Figure 7-8).

Beneficial uses under the Water Act 1992 describe how a water resource benefits the community. Throughout the NT,

beneficial uses or values have been set for major aquifers and river catchments. A Beneficial Use Declaration (BUD) to

maintain the health of aquatic ecosystems (Category 4 – Environment) has been set for the upper McKinlay River

(between lines 8478800 and 8490000) to the west of MLN1109 (Figure 7-9). This declaration was gazetted on 11

March 1998.

Aquatic ecosystem values associated with the project area are discussed in more detail in Chapter 14 and Appendix J.

7.5.1 FLOODING Stream flows are highly variable and extremely responsive to rainfall, particularly in the upper reaches of the

catchment. Streamflow usually commences in late November (start/stop flows), reaches peak levels between

February and March and generally ceases flow during April to May.

A flood gauge on the McKinlay River at Burrundie (G8180069), approximately 30 km downstream of URPA, collected

53 years of data, prior to being decommissioned in 2010 (AECOM, 2018). Base case flood modelling of the URPA was

conducted by AECOM, 2018 with inputs from the Burrundie guage. The expected probability flows are summarised in

Table 7-1 below.

The base-case flood model results demonstrate that for the events up to the one in 2,000 AEP, backwater from the

McKinlay River does not overtop any mine pits or inundate site infrastructure.

TABLE 7-1 FLOOD FREQUENCY ANALYSIS (FFA) EXPECTED PROBABILITY FLOWS FOR THE URPA

AEP (1 in Y) FFA Flow (m3/s)

50 714

100 768

500 855

1,000 880

2,000 900

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Figure 7-8

Figure 7-9

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7.5.2 WATER QUALITY

Water quality monitoring at URPA has been undertaken between 2010 and 2019, including at two key sampling

locations on the McKinlay River (Figure 7-8), one which serves as a control upstream from the site (URSW09) and one

which serves as a compliance point downstream from the site (URSW08). Analysis of the long term data (refer

Appendix I for more information) indicates the following:

There is ‘no significant difference’ in upstream and downstream pH values (Appendix I).

There is ‘no significant difference’ in upstream and downstream dissolved oxygen concentration (Appendix I).

Downstream water quality measurements indicate Neutral Mine Drainage (NMD) impacts on the McKinlay

River, with sulphate, calcium and magnesium concentrations constantly higher in downstream samples but

Electrical Conductivity (EC) within the guideline values, thereby indicating little downstream impact.

Many metals were non-detectable in most samples.

Al, As, Mn and Zn were detected in most samples but no significant difference in the concentrations of these

metals/metalloids in upstream and downstream samples was identified, as were changes in average

concentrations; indicating that natural attenuation processes are occurring.

When downstream concentrations of Al and Zn did exceed GV, generally upstream samples also gave

elevated concentrations suggesting the origin of these metals is upstream of the URPA (i.e. potentially

naturally occurring due to the regional mineralisation).

These findings apply across the whole monitoring period 2010-2019, and are not just based on recent observations.

NTMO have been monitoring water quality (see Figure 7-8) within and surrounding the URPA as a requirement of WDL

138-03 which expired on 1 December 2016. Conclusions from the monitoring and license report prepared by GHD

(2017) and submitted in October 2017 are as follows:

The long term water quality results in the McKinlay River downstream of the Union Reefs Project Area show

that water quality at the downstream sites is similar to that at the upstream site, URSW09, and also to sites

URSW01 and URSW03 which have potential to be impacted by Union Reef infrastructure.

Based on the water quality data recorded at URSW08, the contribution of URPA to water quality is not

sufficient to cause adverse impacts to the McKinlay River ecosystem downstream of the site. When trigger

values were exceeded at URSW08, the upstream concentrations at URSW09 were often also elevated.

However, inputs from the Decant Pond and the East WRD do appear to contribute to the elevated

concentrations at URSW08 during and soon after rain events. These contributions are minimal and water

quality rapidly returns to below trigger values at URSW08 due to catchment/natural geochemical attenuation

processes.

Sediment monitoring shows metal concentrations were generally low, and concentrations of aluminium, iron

and manganese concentrations were higher at control sites. Only the lead and zinc concentrations suggested

potential impacts from URPA discharges, although these concentrations were lower than the relevant

historical medians for the impact sites. There has been no evidence of any adverse impact on sediment

quality on the URPA resulting from the passive discharges of mine affected water from the site.

Water quality is discussed in more detail in Chapter 13 and Appendix I. Water quality monitoring sites are presented in

Figure 7-8.

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7.6 Land Systems and Vegetation

The URPA lies within the Brock’s Creek Ridge land system, mapped by Christian & Stewart (1946). This system occurs

extensively in the Katherine to Darwin Region, covering about 4,000 km2. It comprises sharp north-south running

ridges and hills with small, alluvial flats.

The land system is described as elevated backbone country (Christian & Stewart, 1946) and is characterised by

relatively steep slopes, active erosion and skeletal gravelly sandy loam soils. Flooding during the wet season is

confined to the narrow flats. Alluvial flats contain heavier soils that contain higher levels of clay and silt than soils on

erosional landscapes.

The land units within this land system that occur in the URPA have been described in Table 7-2 and Figure 7-10.

Vegetation mapping is presented in Figure 7-11.

TABLE 7-2 LAND UNIT DESCRIPTION – LAND UNIT OF THE URPA (FROM NAPIER & STEEN, 2002)

Land Unit

Summary Landform Dominant Soil

Vegetation Comments

5a Corymbia dichromophloia mid high open woodland over shallow red and brown gravelly soils on rocky strike ridges.

Slopes up to 35%.

Surface gravel >50%.

Red and Brown Kandosols.

Corymbia dichromophloia mid high open woodland with annual Sorghum sp. grassland understorey.

Extensive unit in the survey area.

Baker land system.

Eucalyptus miniata communities are more frequent in the lower and mid survey area.

5b Eucalyptus phoenicea tall woodland over moderately deep red gravelly soils on steep granite hills. Mid high to tall open woodland and woodland.

Slopes 20-50%.


Red Kandosols.

Eucalyptus phoenicea tall woodland with Sorghum intrans grassland understorey.

Mid high open woodland to tall woodland.

Cully land system (Lynch and Wilson, 1998).

Important habitat for restricted mammals and bird species.

May contain plant species of considerable conservation interest.

Large granite boulders.

6a Eucalyptus tectifica or Corymbia dichromophloia mid high open woodland over shallow brown gravelly soils on undulating rises and occasional plains.

Slopes up to 15%.


Brown Kandosols.

Eucalyptus tectifica mid high open woodland with Sorghum intrans or

Themeda triandra grassland understorey.

Extensive areas in the upper survey area.

Bend land system

10b Variable tall woodland on ephemeral drainage lines and creeks.

Nil slopes.

Nil surface gravel.

Kandosolic Redoxic Hydrosols.

Corymbia polycarpa mid high open woodland with Aristida macroclada grassland understorey.

Melaleuca viridiflora, Lophostemon

Stream channels, drainage depressions and levees of minor creek systems.

Important habitat for wildlife.

Drainage lines are always an erosion risk

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Land Unit

Summary Landform Dominant Soil

Vegetation Comments

grandiflorus, Eucalyptus bigalerita.

Melaleuca viridiflora Barringtonia acutangula, Acacia holosericea.

and vulnerable to disturbance by development, stock, feral animals, fire and exotic plant species.

10c Grassland or Corymbia polycarpa tall sparse open woodland on seasonally inundated drainage depressions and alluvial flats.

Slopes up to 2%.

Surface gravel nil.

Kandosolic Redoxic Hydrosols.

Mixed species closed grassland.

Broad drainage depressions associated with stream channels.

!(

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ADELAIDE RIVER


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STUART HIGHWAY

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Figure 7-10

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LegendML_GrantedRiparian Closed GrasslandGrasslandMid High Open WoodlandMid High Sparse Open WoodlandTall Open WoodlandTall Woodland

Figure 7-11

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7.7 Fauna

More than 40% of the land within the Pine Creek bioregion is protected within parks and reserves (Baker et al. 2005).

The fauna found within the URPA, including four listed, threatened species, are well represented throughout the

greater Bioregion (DENR, 2019).

Given the highly modified soils and vegetation resulting from decades of mining activity, the habitat within the URPA

is, on the whole, sub-optimal for breeding and foraging for these threatened species. The proposed activities at the

URPA include limited habitat modification (i.e. the only impacted habitat is Ghost bat adits), and individuals persisting

within the project area are unlikely to be negatively impacted. The Ghost bat is the only listed threatened species that

has the potential to be significantly impacted by the project.

A desktop assessment of terrestrial fauna was conducted encompassing a 10 km buffer around the URPA (MLN1109).

Reports from the following databases were generated (accessed 13 September 2019):

The Commonwealth Department of the Environment and Energy’s Protected Matters Search Tool (PMST) to

identify Matters of National Environmental Significance (MNES) potentially occurring in the Study area.

The DENR Fauna Atlas database to identify actual records of all fauna species known to occur.

NT NRM custom area report.

7.7.1 RESULTS The DENR Fauna Atlas lists 327 native species within 10 km of the URPA, this includes 207 birds, 38 mammals, 65

reptiles and 17 amphibians. Most of these species are well represented within the greater Pine Creek Bioregion (Baker

et al. 2005; EcoLogical, 2014; EcOz, 2014 and GHD, 2014), given the wide range of habitat types and large percentage

of protected area. A survey of vertebrate fauna, fish and aquatic micro-invertebrates was also conducted as part of

the 1993 EIS for URPA. The survey found that no species was limited to MLN1109 and this was expected, given that

the habitats at the URPA are widespread in the Top End (NSR, 1993).

Of the 327 native species found within 10 km of the URPA, 19 are federally (EPBC) listed threatened species, and they

or their habitat are known to occur or could potentially occur within 10 km of the URPA. This includes nine mammals,

five birds and one reptile, as follows:

Antechinus bellus (Fawn Antechinus)

Conilurus penicillatus (Brush-tailed Rabbit-rat)

Dasyurus hallucatus (Northern Quoll)

Hipposideros inornatus (Arnhem Leaf-nosed Bat)

Macroderma gigas (Ghost Bat)

Mesembriomys gouldii gouldii (Black-footed Tree-rat)

Petrogale concinna canescens (Nabarlek)

Phascogale pirata (Northern Brush-tailed Phascogale)

Saccolaimus saccolaimus nudicluniatus (Bare-rumped Sheath-tailed Bat)

Erythrura gouldiae (Gouldian Finch)

Geophaps smithii (Partridge Pigeon, eastern subspecies)

Erythrotriorchis radiatus (Red Goshawk)

Falcunculus frontatus whitei (Crested Shrike-tit [Northern])

Tyto novaehollandiae kimberli (Masked Owl [Northern])

Acanthophis hawkei (Plains Death Adder)

In addition to the federally listed species, only three species listed under the TPWC Act were identified. This includes a

bird, mammal and a reptile:

Falco hypoleucos (Grey Falcon)

Varanus mertensi (Mertens’ Water Monitor)

Rattus tunneyi (Pale Field-rat)

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Several other listed threatened species were identified within the databases but were excluded from these results,

including:

Three migratory, marine birds and one species of aquatic fauna (Pristis pristis, Freshwater Sawfish) have been

excluded due to the absence of suitable habitat within the UPRA.

Other species have been excluded due to sighting records being over 30 years old, i.e. the soils and

vegetation across much of the URPA have undergone continual disturbance from 1987 to 1992 and most

significantly from 1994 to 2003 (further detailed in Section 4.3), rendering the habitat of little value and/or

unsuitable for those species that may once have occurred on the URPA prior to mining activities.

The URPA fauna register indicates that of the 18 threatened species listed above, only four have been confirmed to

occur within URPA between 2011 and 2019. These are listed below and discussed in more detail in the following

sections:

Erythrura gouldiae (Gouldian finch) listed as endangered (EPBC Act) and vulnerable (TPWC Act) – sighted

2011.

Varanus mertensi (Mertens’ water monitor) listed as vulnerable (TPWC Act) – sighted 2012 and 2018.

Geophaps smithi smithi (Partridge pigeon, eastern subspecies) listed as vulnerable (EPBC Act and TPWC Act) –

sighted 2017 and 2018.

Macroderma gigas (Ghost bat) listed as vulnerable (EPBC Act) and near threatened (TPWC Act) – sighted

1993, 2018 and 2019.

Gouldian Finch

This species is now restricted to isolated areas in Northern Territory and the Kimberly. It is not uncommon at a

regional scale surrounding Pine Creek and Nitmiluk, with the largest known NT population in the Yinberrie Hills

(approximately 60 km south east of the URPA) (DENR, 2019).

The habitat within the URPA is highly disturbed, with regenerated areas lacking mature eucalypts, and grassland areas

in poor condition due to the absence of fire. These conditions are thought to be sub-optimal for Gouldian finch habitat

requirements, in terms of both breeding and foraging. The few, infrequent sightings within the URPA are thought to

be of individuals moving through the area to surrounding land and not part of a resident population.

Merten’s Water Monitor

This species is listed as Vulnerable in the Northern Territory. It has a widespread range, occupying coastal and inland

waters across the far North of Australia, although individuals are rarely seen far from water sources (DENR, 2019). The

areas of suitable Merten’s Water Monitor habitat include the McKinlay River adjacent to the the URPA, and water

storage dams and pits within the project area.

Partridge Pigeon (Eastern Subspecies)

This species has been declining in populations across the Top End of the NT and Kimberley, with several notable

populations within the Pine Creek Bioregion (DENR, 2019). It is a granivorous species, foraging in lowland eucalypt

open forests and woodlands on grass seed and Acacia spp. and other woody plants (Higgins & Davies, 1996).

Populations have been seen to greatly reduce in areas surrounding cleared land and widespread fire of high intensity

(Woinarski, 2004). It is thought that there are only small areas of low-value Partridge Pigeon habitat remaining on the

URPA.

Ghost Bat

The Ghost bat has a history of decline across its broad Australian distribution, and the loss of roost sites in the past

decade has been important consideration in the listing of the Ghost bat as Vulnerable. Ghost bats have established

colonies of significant size in historical mine workings, including adits, some of which are in the vicinity of ore bodies

with remaining economic potential. These artificial roosts can provide critical maternity sites, routine roost sites, and

dispersal stop‐over roosts for bats. Issues arise when a mining proposal requires reworking of old deposits where

historical adits are present, or where easy human access to an adit results in high levels of disturbance.

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Once distributed throughout most of the continent, the Ghost bat now exists as a fragmented group of geographically

isolated populations across northern Australia, in the Pilbara and Kimberley regions of Western Australia, the Top End

of the Northern Territory, and in Queensland. There are thought to be less than 10,000 individuals (Appendix G). A

detailed assessment of the potential impacts of the project on the distribution and ecology of the Ghost bats is

provided in Chapter 11 and Appendix G.

7.8 Introduced Species

Weed and feral animal records in the URPA have been documented below. The URPA Mine Management Plan

contains management measures to control weeds and feral animal species in the URPA.

TABLE 7-3 URPA IDENTIFIED DECLARED WEEDS 2013 TO 2019

Common Name Scientific Name WM Act Declaration Weeds of National

Significance (WoNS)

Flannel Weed Sida cordifolia Class B/C No

Gamba Grass Andropogon gayanus Class B/C Yes

Hyptis Hyptis suaveolens Class B/C No

Mission Grass Cenchrus sp Class B/C No

Mossman River Grass Cenchrus echinatus Class B/C No

Rubber Bush Calotropis procera Class B/C No

Sicklepod Senna obtusifolia Class B/C No

Spinyhead Sida Sida acuta Class B/C No

TABLE 7-4 URPA IDENTIFIED PEST SPECIES 2013 TO 2018

Common Name Scientific Name

Buffalo Babalus bubalis

Cane Toad Bufo marinus

Cat Felis catus

Dog Canis lupus familiaris

Donkey Equus asinus

Horse Equus caballus


NT Mining Operations Pty Ltd Union Reefs North Underground Mine

Draft Environmental Impact StatementPart 2

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8 MINE WATER MANAGEMENT

8.1 Operational Water Balance

The following site water balance for the operational phase of the project (i.e. year ending April 2021 – April 2023) has

been developed as part of the site water management planning. The site water balance considers all inflows and

outflows of the water management features identified in Section 4.7. The operational water balance is based on real

data including the proposed water production rate from dewatering, process water requirements, and average annual

rainfall from the historical record described in Section 7.2. The average annual water balance is summarised in Table

8-1, with discrete components described below.

The URPA processing tonnes (Table 4-7 in Chapter 4) for 2020 to 2024, including processing tonnes from the CHPA

have been included in this site water balance. The URPA Underground Mine will contribute processing tonnes in 2021

to 2023.

TABLE 8-1 SITE WATER BALANCE – MINE OPERATIONS

Year ending April 2020





Inputs

Rainfall (mm/year) 1,380 1,380 1,380 1,380 1,380

Mining rate (Mt/year) 0 0.092 0.092 0.092 0

Production rate (Mt/year) 0.1 0.785 0.74 0.705 0.6

Inflows (ML/year)

Catchment runoff – Prospect pit 113 113 113 113 113

Direct rainfall and catchment runoff – Crosscourse pit 941 941 941 941 941

Raw water from Dam C for processing plant 32 251 236 225 192

Raw water from Dam C for underground operations 0 63 63 63 0

Groundwater ingress to underground workings 0 79 221 221 0

Seepage to Crosscourse pit 36 62 62 62 62

Total Inflows 1,122 1,509 1,636 1,625 1,308

Outflows (ML/year)

Evaporation from Crosscourse pit 599 599 599 599 599

Retained in tailings 32 251 236 225 192

Seepage from Crosscourse pit 8 0 0 0 0

Discharge under WDL 0 2,037 1,342 1,287 931

Total Outflows 639 2,887 2,177 2,111 1,722

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Change in Storage (ML/year)

Change in water inventory 483 -1,378 -541 -486 -414

Crosscourse Pit Storage Balance

Change in tailings volume (ML) 69 541 541 486 414

Change in water volume (ML) 483 -1,378 -541 -486 -414

Change in Crosscourse pit freeboard volume (ML) -552 837 0 0 0

8.1.1 DIRECT RAINFALL, CATCHMENT RUNOFF AND EVAPORATION The direct rainfall, catchment runoff and evaporation have been estimated based on the catchment area of Prospect

pit North and South (15.7 ha), catchment area and surface area of Crosscourse pit (173 ha and 27 ha respectively) and

the annual rainfall and evaporation depths described in Section 7.2. The net balance of direct rainfall, catchment

runoff and evaporation is estimated to be 455 ML on average, indicating that the site is hydrologically in water excess.

8.1.2 RAW WATER FROM DAM C Operational requirements of underground operations and some components of the processing plant require a water

with a relatively high quality that is not available from the existing water storage in Crosscourse pit. This water will be

sourced from Dam C, which has a relatively large catchment and is expected to readily supply the required water

demand up to 299 ML/year. Water for processing operations will be recycled from Crosscourse pit wherever possible.

8.1.3 GROUNDWATER INGRESS The underground workings are expected to intercept groundwater at a rate of 18 L/s (i.e. the extreme high case

predicted by AQ2, 2018 appended to Appendix H), that will be required to be dewatered to Prospect pit and from

there pumped to Crosscourse pit for the safe operation of the mine. Groundwater ingress is included in the site water

balance in Table 8-1.

8.1.4 RETAINED IN TAILINGS Some water in tailings slurry sub aqueously deposited in Crosscourse pit will remain entrained in the tailings, with the

remainder released through consolidation and available for recycling to the processing plant. The water retained in

tailings is effectively lost from the water balance, so it is accounted for as an outflow, rather than change in storage.

However, it still accounted for in available water storage capacity in Crosscourse pit as the change in the volume of

tailings, along with the volume of the tailings solids themselves.

8.1.5 SEEPAGE IN AND OUT OF CROSSCOURSE PIT The net groundwater flux into or out of Crosscourse pit depends on the water level elevation in the pit. The

relationship was estimated using a groundwater model (refer Appendix H) and is summarised in Figure 8-1.

Since the completion of mining in Crosscourse pit, it has so far been a groundwater sink, with inflows estimated to be

85 ML/year in early 2019, however if the water level in Crosscourse pit rises, the pit has the potential to become a

groundwater source. Figure 8-1 shows that Crosscourse pit is anticipated to shift from being a net groundwater sink to

a net groundwater source is at a water level between 173-176 m AHD.

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FIGURE 8-1 CROSSCOURSE PIT GROUNDWATER FLUX

Figure 8-1 also shows the net surface water balance (direct rainfall and catchment runoff less evaporation) of

Crosscourse pit. This balance is a fundamental property of the climate, hydrogeology and geometry of Crosscourse pit

and independent of existing and proposed operations. As is typical for open cut pits in tropical Northern Territory,

Figure 8-1 shows that the net surface balance is expected to reach equilibrium with groundwater seepage out at

about 186 m AHD, just below the surface water spill level of 189 mAHD. In an above average rainfall year, the net

surface water balance is well in excess of the maximum groundwater seepage outflow rate. Overall, this indicates that

in the long term, Crosscourse pit is expected to fill and remain near to the spill level. The post closure water balance of

Crosscourse pit is considered further in Section 7.4.2.

8.1.6 DISCHARGE UNDER WDL AND CHANGE IN STORAGE

As discussed in Section 8.1.5, the groundwater and water balance modelling indicates that the long term equilibrium

water level in Crosscourse pit is close to the spill level; however, the timing of the increase in water levels is hastened

by aspects of the project including:

Dewatering of Prospect pit and subsequent dewatering of the underground workings.

Displacement of water by deposition of tailings in Crosscourse pit.

Without additional water management actions, the effect of this water excess would be increasing water surface

elevations in Crosscourse pit, resulting in:

Reduction in the available water storage capacity in Crosscourse pit to contain extreme floods.

Groundwater seepage from Crosscourse pit that is expected to report to downstream water management

features and watercourses, including the McKinley River.

The potential impacts will be mitigated by a range of measures, including extraction (recycle to the processing plant)

and treatment and discharge of water from Crosscourse pit under a Waste Discharge Licence (WDL). NTMO will apply

for a WDL.

0

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Water level elevation (m AHD)

Seepage from Crosscourse pit Seepage to Crosscourse pitNet surface water balance Wet year net surface water balanceSpill level Current water level

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The estimated average annual volumes expected to be discharged to maintain the water level in Crosscourse pit at

about current levels are included in Table 8-1. The approval of the WDL is not anticipated until late 2020, and

therefore no discharges are expected in the first year of the project, with an accordingly higher discharge volume in

the second year to realise target water levels to minimise potential seepage rates and impacts.

Over the life of the project, a total of about 6 GL of water would need to be managed during the operation of the

project in order to maintain water levels at current levels, and therefore, minimise seepage from Crosscourse pit.

A framework for the development of a waste discharge licence has been presented in Section 8.5.

8.1.7 SENSITIVITY TO RAINFALL CONDITIONS The operational water balance shown in Table 8-1 is based on average rainfall conditions. An additional scenario was

considered, sampling the wettest consecutive five years in the historical rainfall record (refer to Section 7.2). Higher

rainfall is expected to result in proportional higher direct rainfall and catchment runoff, while other flows remain

similar.

Changes to the key results sensitive to rainfall conditions in Table 8-1 are summarised in Table 8-2.

TABLE 8-2 SITE WATER BALANCE – MINE OPERATIONS – WET CONDITIONS

2019 2020 2021 2022 2023

Inputs

Rainfall (mm/year) 1,552 1,629 1,601 1,788 1,846

Inflows (ML/year)

Catchment runoff – Prospect pit 127 133 131 146 151

Direct rainfall and catchment runoff – Crosscourse pit 1,058 1,111 1,092 1,219 1,259

Results (ML/year)

Discharge under WDL 0 2,358 1,511 1,598 1,287

Table 8-2 shows that the total volume of water required to be managed to minimize seepage from Crosscourse pit

may vary up to about 7 GL (approximately 17% higher when compared to average conditions) over the life of the

project.

8.2 Flood Assessment

Although the water balance indicates that the water management system is capable of dealing with typical rainfall

characterised by the historical rainfall conditions, rare or extreme rainfall events have the potential to result in

discharges from the pit and inrush into the portal. The assessment of rare to extreme rainfall was undertaken based

on the design rainfall published by the Bureau of Meteorology (2019).

The primary mechanism that may result in the rare to extreme design rainfall at the site is a cyclone. The likelihood of

a cyclone passing over the URPA is low due to its southerly location, but associated winds and rainfall may affect the

site. Cyclones occur most frequently in the wet season months, particularly from January to March.

Figure 8-2 summarises the design rainfall depths for the site. For assessment of pit inrush, a design duration of 72 hours

has been adopted.

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FIGURE 8-2 PROSPECT PIT RAINFALL ANNUAL EXCEEDANCE PROBABILITY (AEP)

8.2.1 PROSPECT PIT The portal in Prospect pit will be located at 177.5 mAHD and the water level in Prospect North pit water storage will

be maintained below 168.5 mAHD, providing a freeboard volume of 60 ML. In order to further reduce the risk of

inrush, a pump and pipeline capable of transferring up 150 L/s to Crosscourse pit is proposed.

Table 8-3 below describes the flood risk assessment for Prospect pit. The assessment considers the continued

dewatering of the underground workings of groundwater inflow up to 18 L/s and water recycled from underground

operations of up to 12 L/s.

TABLE 8-3 PROSPECT PIT PORTAL FLOODING RISK ASSESSMENT

Annual Exceedance Probability

Total Rainfall (mm)

Total Catchment

(ha)

Total Surface Inflow (ML)

Peak Inrush Flow Rate

(L/S)

Total Underground Dewatering

(ML)

Total Inflow (ML)

1 in 100

72 hours 425 15.74 32.5 2,566 7.78 40

1 in 500

72 hours 555 15.74 52.47 3,558 7.78 60

1 in 1,000

72 hours 617 15.74 61.98 4,004 7.78 70

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Table 8-3 shows that Prospect pit is able to withstand a 1 in 1,000 AEP rainfall event over a 72 hour period, with a

150 L/s pump installed, without overflowing into the portal. In the unlikely event that the pump was not operational,

there is a risk of overflow if Prospect pit for rainfall events with a design frequency rarer than 1 in `100 AEP.

8.2.2 CROSSCOURSE PIT A similar assessment was undertaken for Crosscourse pit, considering the cumulative inflows from Prospect pit, as

summarised in Table 8-4.

TABLE 8-4 72 HRS CROSSCOURSE PIT FLOODING RISK ASSESSMENT

Annual Exceedance Probability

Total Rainfall (mm)

Total Catchment

(ha)

Total Surface Inflow (ML)

Peak Inrush Flow Rate

(L/S)

Receive from Prospect Pit

(ML)

Total Inflow (ML)

1 in 100

72 hours 425 77.86 297.7 14,315 40.28 338

1 in 500

72 hours 555 77.86 398.66 18,915 60.25 459

1 in 1,000

72 hours 617 77.86 446.1 21,073 69.76 516

Table 8-4 shows that cumulative inrush volume for Crosscourse pit for extreme rainfall events is up to 516 ML. This

volume is small compared to the some 6,000 ML freeboard currently in and expected to be maintained in Crosscourse

pit, assuming water is treated and discharged under license.

Overall, the risk of flooding of the underground portal or overtopping of Crosscourse pit, during the operational phase

of the project is considered low.

8.3 Water Security

As discussed in Section 4.7.1, Dam C has a relatively large catchment of about 200 ha. Runoff from this catchment is

expected to be in the order of 1,500 ML/year which is expected to readily supply the required water demand up to

299 ML/year (refer to Section 8.1.2).

Overall, the project has adequate water security.

8.4 Post Closure

8.4.1 PROSPECT PIT Most waste rock stockpiled in Prospect South pit will be backfilled into underground stopes. All pumps and facilities

will be decommissioned and Prospect pit will be reinstated to the original state.

Prospect pit overflow level is 193 mAHD. Prospect pit has never had a recorded overtopping and recent monitoring

indicates water level fluctuates between 174 to 179 m AHD annually (Figure 8-3). A bunded wall will be constructed at

the perimeter of the Prospect pit. This will reduce the current catchment from 15.7 ha to approximately 8.5 ha. The

pit will be recharged by groundwater ingress, and runoff during the first wet season post mining, and eventually reach

the groundwater aquifer level. The pit water level will continue fluctuating between 170 to 180 mAHD subject to

different wet season rainfall and following its historical legacy trend. The bund will be maintained at mine closure as

an abandonment bund for safety and security.

96

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FIGURE 8-3 PROSPECT PIT WATER LEVEL 2018 TO 2019

Overall, the long term post closure water level in Prospect pit is expected to reflect the water in Crosscourse pit and

remain well below the spill level. The long term post closure behaviour of Prospect pit is independent of the operation

of the project.

8.4.2 CROSSCOURSE PIT

As discussed in Section 8.1.5, the net groundwater flux into, or out of, Crosscourse pit depends on the water level

elevation in the pit. The relationship was estimated using a groundwater model (refer Appendix H) and is summarised

in Figure 8-4.

1165

1170

1175

1180

1185

1190

1195

RL

Timeline

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FIGURE 8-4 CROSSCOURSE PIT POST CLOSURE WATER BALANCE

Figure 8-4 also shows the net surface water balance (direct rainfall and catchment runoff less evaporation) of

Crosscourse pit long term post closure. This balance is a fundamental property of the climate, hydrogeology and

geometry of Crosscourse pit and independent of existing and proposed operations. As is typical for open cut pits in

tropical Northern Territory, Figure 8-4 shows that the net surface balance is expected to reach equilibrium with

groundwater seepage out at about 186 m AHD, just below the surface water spill level. In an above average rainfall

year, the net surface water balance is well in excess of the maximum groundwater seepage rate.

Overall, this indicates that post closure, Crosscourse pit is expected to fill with water, with water levels remaining at or

above about 185 m AHD. The pit will act as groundwater source and regularly spill via the surface overflow point. The

long term post closure behaviour of Crosscourse pit is independent of the operation of the project.

8.5 Waste Discharge License

NTMO intends to apply for a Waste Discharge License (WDL) under the Water Act to discharge treated water from

Crosscourse pit in order to manage water levels. Section 12.3.2 in Chapter 12, Hydrological Processes describes the

potential impacts and risks if Crosscourse pit is left unmanaged through operations, and allowed to fill to spill levels.

The WDL will stipulate the water quality and other discharge requirements.

WDL application requirements include (but are not limited to) the following:

Waste discharge license justification – see Section 12.3.2, Figure 12-4 and Figure 12-5 in this EIS.

Water treatment specifications and predicted water quality.

Discharge specifications – proposed discharge location along with details of the proposed mixing zone. This

will include the requirements for quantity, quality and dilution requirements (supported by ecotoxicity

assessment).

Discharge flow rates and volumes based on modelled receiving environment flow rates for wet season

scenarios.

0

100

200

300

400

500

600

700

800

165 170 175 180 185 190

Wate

r flux

(ML/d

ay)



98

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Proposed discharge duration.

Discharge monitoring regime including the required reporting schedule along with the timeframe for

receiving environment guidelines or trigger values.

Monitoring plan to assess any potential impacts associated with the waste discharge including the required

types, locations and frequency of monitoring to assess potential impacts on the receiving environment based

on a weight of evidence (multiple lines of evidence) approach.

8.5.1 DISCHARGE LOCATION It is proposed to undertake in-pipe water treatment in two stages and pump water to the McKinlay River at URSW04

via a staging pond (Dam B). The proposed discharge location at URSW04 (Figure 8-5) has been determined as the most

appropriate based on the following criteria:

Proximity to staging pond (i.e. Dam B).

Site accessibility (incl. during the wet season) for installation of discharge equipment and monitoring.

Opportunity for automated siphon discharge to replace active pumping from Dam B (reducing energy

consumption).

Appropriate length for the mixing zone prior to compliance point monitoring at URSW08 (Figure 8-5).

!(

!(PINE CREEK

ADELAIDE RIVER


&<

&<

&<

&<

&<&<

&<

&<

&<

&<

&<

&<

&<

&<`

``

McKinlay River

Wellington Creek

MRWET13MRWET12

MRWET08

URRD

URCP

DAMB

DAMA

URST3

URPSP

URSW10

URSW08

URSW04

URSW01

URST4A

Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/AirbusDS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo,and the GIS User Community

Union Reefs Project Area Proposed Discharge Location

¯


Legend` GDE Sites

&< Surface Water Monitoring Dam B Overflow Path

0 1 2Kilometres

Figure 8-5

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8.5.2 PRELIMINARY SITE SPECIFIC TRIGGER VALUES

Preliminary Site Specific Trigger Values (SSTVs) are presented in Table 8-5 and have been based on previous Waste

Discharge Licence SSTVs for the project site that were developed from more than five years (at least 12 data points as

suggested in the ANZECC 2000 guidelines) of upstream data at site URSW09 and compared with the 95% species

protection ANZECC 2000. Where the background concentrations are consistently higher than ANZECC (2000) values,

the suggested SSTV is selected from the 80th percentile of the background level data set. Conversely, where the

ANZECC 95% Species Protection value is higher than the 80th percentile of the background level data set, the ANZECC

(2000) 95% Species Protection value is the recommended SSTV.

Note that the proposed SSTV for EC of 700 to 1000 µs/cm is based on site data that indicates EC within the water

stream is generally related to sulphate concentrations rather than toxicants such as heavy metals.

TABLE 8-5 PROPOSED RECEIVING ENVIRONMENT SSTVS FOR URSW08

Analyte 80th Percentile

URSW09 ANZECC 95% TVs SSTV

URSW08

pH 7.0 8.0 6.0-8.0

pH (20th %ile) 6.2 6.0 6.0

EC (µS/cm) 56 250 700 – 1,000

DO (%) 117 120 120

DO (20th %ile) 40 90 40

Turbidity (NTU) 14 15 15

TSS (mg/L) 30 20 30

Dissolved Metals (µg/L)

Aluminium 120 55 120

Arsenic (III)* - 24 24

Arsenic (V)* - 13 13

Cadmium 1 0.2 1

Chromium 2.6 1.0 2.6

Cobalt <1 1.4 1.4

Copper 4.4 1.4 4.4

Iron 270 300 300

Lead <1 3.4 3.4

Manganese 37 1,900 1,900

Nickel <1 11 11

Selenium (total)** <1 11 11

Zinc 30 31 31

* Historical results are only total arsenic therefore until such time as reliable results are available for background levels the default GVs will determine the SSTVs. ** No dissolved value available for selenium.

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8.5.3 WATER TREATMENT NTMO treats water at different sites across its lease areas to manage contaminant levels prior to discharge to the

receiving environment. Usually pH modification of mine affected water is achieved using caustic soda (NaOH),

limestone (CaCO3) or lime (CaO).

Concentrations of As, Co, Zn and Cu are elevated in water sampled from the Crosscourse pit in comparison to other

monitoring sites including URSW09, which is an upstream baseline surface water monitoring location (see also Section

13.2.3).

Preliminary treatment studies of the water in Crosscourse pit indicates that caustic treatment alone will not

successfully reduce concentrations of contaminants such as arsenic to concentrations suitable for discharge to the

environment during high flow events, but additional treatment with FeCl2 has led to a reduction in arsenic levels

(Table 8-6).

Additional sampling and treatment studies will be required over the next six months to confirm the most appropriate

water treatment regime. This test work will be undertaken to include process water from the recent resumption of

processing operations at the URPA, so that currently recirculated process water and tailings discharge into

Crosscourse pit is captured in the testwork.

The preliminary Crosscourse pit water treatment circuit is illustrated in Figure 8-6.

A32345678

A

B

D

E

F

A

B

C

D

E

F

2345678 A1

A

SCALE:

SHEET: OF

REV.:DOCUMENT NAME:

1 1

NTS

A

Preliminary Water Treatment Circuit

CONTRACTOR DOC No.:PROJECT:


A Issued for informationn(IFI) Sam Y.31/10/2019 Trevor E.

Inflow

outflow

Underflow

RecycleFerric

Tank

Hydrocyclone

Caustic Dosing

To Crosscourse Pit

Inflow

outflow

Hydrocyclone

Inflow

outflow

Hydrocyclone

Inflow

outflow

Hydrocyclone

Inflow

outflow

Hydrocyclone

To DamB To DamB To DamB To DamB To DamB

Fecl2 Dosing

LegendUntreated WaterTreated WaterFerric Ion RecycleResidue WasteCaustic Dosing

UnderflowUnderflowUnderflowUnderflow

Figure 8-6

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TABLE 8-6 PRELIMINARY TESTWORK PRE-TREATMENT AND TREATMENT WATER QUALITY RESULTS – CROSSCOURSE PIT 2019

FL

S EC

(uS/

cm)

FLS

pH

Alu

min

um

Dis

solv

ed

(µ

g/L)

Ars

en

ic

Dis

solv

ed

(μ

g/L)

Cad

miu

m

Dis

solv

ed

(µ

g/L)

Ch

rom

ium

Dis

solv

ed

(μ

g/L)

Co

bal

t D

isso

lve

d

(μg/

L)

Co

pp

er

Dis

solv

ed

(μg/

L)

Fre

e C

yan

ide

(m

g/L)

Iro

n D

isso

lve

d

(µg/

L)

Lead

Dis

solv

ed

(µg/

L)

Man

gan

ese

Dis

solv

ed

(µ

g/L)

Nic

kel D

isso

lve

d

(µg/

L)

Sulp

hat

e (

mg/

L)

WA

D

Cya

nid

e (

mg/

L)

Zin

c- D

isso

lved

(µg

/L)

Crosscourse pit water 2015 to 2017

2,756 7.86 100 860 0.2 <1 310 15 0.014 21 <1 21 7 1,100 0.024 15

Crosscourse pit water 2017 to 2019

2,527 7.64 20 910 0.5 <1 160 2 0.004 <10 <1 39 5 1,200 0.007 52

URCP ST1

(Caustic) 2,692 8.2 80 600 <0.1 <1 110 1 <10 <1 12 2 1,200 4

URCP Trial Sample A CCft

2,829 6.62 20 8 0.2 <1 120 3 61 <1 190 7 1,300 53

URCP Trial Sample B CCft

2,730 6.96 <10 14 0.2 <1 110 <1 24 <1 140 5 1,300 5

Aquatic 95% protection

250- 6-8- - - 0.2- - 13 - 0.007- - 3.4- 1,900- 11- - -0.007 (total)

8-

104


8.5.4 DISCHARGE REGIME

Discharge is proposed to be managed via a dilution algorithm that will be based on monitoring of Electrical

Conductivity (EC). NTMO has found EC to be the most effective, real time marker species for discharge management.

Telemetry stations to measure EC, pH and flow will be installed (Figure 8-5):

At URSW 11 upstream control

At URSW 04 discharge point

At URSW 08 downstream compliance point

Proposed discharge water volumes will be based on discharge water quality, river flows and ecotoxicology.

Ecotoxicology assessment will be undertaken prior to discharge to characterise the acute toxicity of the discharge

water which will assist in the calibration of the discharge coefficient.

The proposed ecotoxicity assessment combines Direct Toxicity Assessment (DTA) with screening bioassays designed to

assess the potential toxicity of McKinlay River water downstream of the discharge point during discharge of treated

water from Dam B. Additionally the program will include a full dilution DTA test with two sensitive species and chronic

assessment of toxicity for the active discharge sources of treated mine water at Dam B.

Preliminary surface water and sediment monitoring analytes for active discharge are presented in Table 8-7.

TABLE 8-7 PROPOSED MONITORING ANALYTES FOR ACTIVE DISCHARGE

Type Analytes

Surface Water

Field measurements Flow, water level, pH, electrical conductivity, dissolved oxygen, temperature

Dissolved metals (0.45 µm) µg/L

Aluminum, arsenic (III and V), cadmium, chromium, cobalt, copper, iron, lead, manganese, nickel, selenium, zinc

Environmental indicators mg/L

Turbidity, total suspended solids, total dissolved solids, hardness, carbonate, bicarbonate, alkalinity, calcium, magnesium, potassium, sodium, chloride, sulphate, WAD and Free Cyanide

Sediment

Metals: 1 M HCl acid digest; Total metals

Al, As (III and V), Cd, Co, Cu, Fe, Mn, Ni, Se, Zn

Ions Total sulphur, sulphate, sulphide, Calcium, Magnesium, CN species

105


9 MINE CLOSURE The Underground Mine project is proposed within the larger URPA. This chapter is intended to provide input specific

to the mine closure for the project only. Details for the broader mine closure of the URPA are contained in the URPA

Mine Closure Plan. The URPA is a highly modified, brownfields mining area that consists of numerous mine features or

Closure Domains (see also Sections 4.6 and 4.7) unrelated to this draft EIS. Approximately 495 ha at URPA has been

disturbed historically, of which 355 ha has been rehabilitated/revegetated. This chapter addresses mine features

(Closure Domains) that are specifically and primarily associated with the underground mine (this draft EIS). Closure

Domains are therefore discussed using the following classifications:

Primary: Mine features primarily associated with the underground mine (closure aspects addressed in this

EIS).

Secondary: Active and ongoing URPA mine features that interact with the project, but both pre-date and to

operate beyond the period of the project (discussed in this EIS but closure aspects addressed in the broader

URPA Mine Closure Plan).

Tertiary: URPA mine features that do not interact with the project (not discussed in this EIS but closure

aspects addressed in the broader URPA Mine Closure Plan).

The draft EIS commits to updating an integrated URPA Mine Closure Plan, including the following aspects related

specifically to the Union Reefs Underground Mine (i.e. this project).

9.1 Closure Domains

Closure Domains are summarised in Table 9-1, detailed in Table 9-2 to Table 9-9 and presented in Figure 9-1 and

Figure 9-2.

TABLE 9-1 CLOSURE DOMAIN CLASSIFICATION AND NOMINAL DURATION

Closure Domain Closure

Classification Nominal Closure

Start Year Nominal Closure

End Year Nominal Closure Duration (Years)

Reference

Union Reefs North Underground Mine

Primary 2022 2023 1 Table 9-2

Haul road Secondary 2022# 2023# 1 Table 9-3

Prospect South pit Secondary 2022# 2023# 1 Table 9-4

Prospect North pit Secondary 2022# 2023# 1 Table 9-5

Crosscourse pit Secondary N/A N/A N/A Table 9-8

Dam A and Dam C Secondary N/A N/A N/A Table 9-6

Dam B Secondary N/A N/A N/A Table 9-7

Processing operations Secondary N/A N/A N/A Table 9-9

# Closure years only relate to aspects associated with the underground mine / the project.

Closure tasks by Closure Domain (where applicable to this EIS) are outlined in the sections below.


!

! !

!

McKinlay River

Dam C

Dam A

Decant Pond Dam

Dam BFuel Bay

Truck Workshop

LandfillLaydown Area

Processing/Office/Workshop Complex

Orica Compound

Storage Area

Crosscourse Pit

Union North Pit

Prospect Pit

Millars Pit

Lady Alice Pit

Big Tree PitUnion South Pit

Temple Pit

Ping Que Pit

ROM

Old Tailings Dam

Union Dam

0 0.5 1

Kilometres

¯

Document Path: G:\GIS\Environmental\Projects\Contractors\URPA EIS 2019\URPA Infrastructure.mxd

Legend! Ghost Bat Adits

Gas PipelineDamInfrastructure

PitROMTailings Dam (Closed)Waste Rock DumpPonds

Union Reefs Project Area Closure Layout

Figure 9-1

!(

!(PINE CREEK

ADELAIDE RIVER


·h

Prospect Pit North

Prospect Pit South

Magazine

Workshop Office

Fuel Bay

Exhaust Fan

RaiseTanks/ Power/ Compressor

RoM Pad

New Haul Road

Exist

ing Ha

ul Ro

ad

Portal

Union Reefs Project Area Prospect Pit Proposed

Layout

0 100 200

Metres

¯

Document Path: G:\GIS\Environmental\Projects\Contractors\URPA EIS 2019\URPA Prospect Infrastructure.mxd

Figure 9-2

108


9.1.1 UNION REEFS NORTH UNDERGROUND MINE CLOSURE DOMAIN TABLE 9-2 UNION REEFS NORTH UNDERGROUND MINE

Union Reefs North Underground Mine – Closure Task Register

Description of Domain or Feature

The Underground Mine area is within a brownfields area of the URPA. The mining area consists of exploration drilling disturbance and the portal is located within the Prospect pit.

At the End Of Mine (EOM) the elements that will require closure consideration are:

The portal

The portal ramp

Temporary waste rock piles

Temporary water management sumps

The network of underground workings including the decline, horizontal drives, vertical development, stopes

Tanks/power/compressor/raise area

Vertical development headworks

Surface exploration drillholes and pads

Location URPA

Tenements Mineral Lease Number 1109 (MLN1109)

Authorisations Not yet authorised.

Status Not yet developed.

Current disturbance

Exploration drilling.

URPA brownfields mining area.

URPA Processing facility and supporting infrastructure.

Previous Historical Mining.

Previous Pastoral Lease and Cattle Grazing.

Life of asset disturbance

2 years (LOM)

Estimated closure start date

2022

Estimated closure end date

2023

Closure works duration

1 year

Land-Use Information

Post-mining land use

Natural habitat compatible with pastoral use.

109



Rehabilitated landform objective

Reinstate natural (unmanaged) ecosystem(s) similar to the pre-mining state that does not preclude pastoral use or inhibit surrounding pastoral use.

Rehabilitation will achieve a stable and functioning landform that is consistent with the surrounding landscapes and other environmental values and will remove potential for long term, post closure impacts on downstream water quality, beneficial uses and environmental values.

Post-mining landform design

Flat area rehabilitation with gently sloping drainage.

Closure completion criteria and performance indicators

Certification that no contamination remains in place that would prevent the closure objectives being met.

Certification that adequate controls are in place to inhibit public access.

Certification that adequate vegetation has been reinstated to meet the closure objectives.

Closure Work Tasks

Activity Closure Work Tasks Approx. Timing and Duration

Development Rehabilitate, deep rip and seed exploration/disturbed areas not required for access to vertical development headworks.

2020 during construction

Decommission Cease mining.

Remove all mining mobile plant from underground.

Remove all chemicals and fuel from underground (if any).

Remove temporary surface waste rock piles to underground as required.

De-sludge temporary water management sumps.

Cease pumping underground inflows.

Remove air supply and management infrastructure from surface.

Remove water supply and management infrastructure from surface.

Remove tanks/power/compressor/raise area infrastructure.

Allow the network of underground workings including the decline, horizontal drives, vertical development and stopes to flood.

Monitor groundwater level rebounds.

Construct final portal geometry that precludes public access but allows groundwater outflow/inflow. Look to brick up face using standard mining approach.

Alter portal ramp geometry to final landform if required

2022 to 2023 1 year

110



Remove vertical development headworks including exhaust fans.

Construct concrete slab or similar to preclude public access from vertical development

Bund the Prospect pits to prevent accidental access to the pit area.

Rehabilitate, deep rip and seed access to vertical development.

Monitor rebounded mine water quality at outflow or in Prospect pit.

Demolish / remove from site

Vertical development headworks and exhaust fans.

Air supply and management infrastructure.

Water supply and management infrastructure.

Tanks/power/compressor/raise area infrastructure.

2022 to 2023 1 year

Site landform and drainage reconstruction

Reshape/re-contour area to generally radially drainage and to remove any erosion prone features.

Retain locally occurring tree species where possible.

Remove any exotic plant species as required.

Establish bunding around mine to ensure public access is restricted.

Deep rip all haul roads not required by the post-closure land user.

2022 to 2023 1 year

Rehabilitation and re-vegetation

Spread available topsoil at >100 mm where required and rip on contour.

Seed with local pioneer species and mulch with any available vegetation detritus.

Create fauna habitats (e.g. using rocks and available vegetation detritus).

2022 to 2023 1 year

Security and signage

The underground mine will have no access for public access post-closure.

No security fencing or signage is required.

Stock fencing put in place around the pit bund to keep cattle off the bund surface, particularly during the early growth years immediately post-closure. Fencing will be maintained by post-closure landowner/pastoralist if required to be maintained in the long term.

Not applicable

Schedule of Work for Research, Investigation and Trials Tasks

Aspect Research, Investigations and/or Trial Schedule

Rehabilitation materials characterisation

Undertake further materials characterisation test work on available rehabilitation cover materials to confirm

Ongoing

111



understanding of results Document and review learnings from existing URPA rehabilitation.

Portals Research requirements for final portal geometry that would allow Ghost bat access but preclude public access.

Ongoing

Completion criteria

Using monitoring results, research, investigation and trials, develop criteria that are specific to the Closure Domains.

Ongoing

Performance indicators

Develop specific, quantitative performance indicators for the measurement of success that are based on research and monitoring outcomes.

Ongoing

Landform and rehabilitation design

Continue with progressive rehabilitation and/or rehabilitation trials and subsequent flora and/ or fauna performance monitoring to inform closure design.

Ongoing

Seeding Conduct ongoing trials and investigations that will inform the success of seeding.

Ongoing

Schedule of Work for Progressive Rehabilitation

Aspect Progressive Rehabilitation Works Schedule

Disturbed areas As discussed above. As discussed above.

Pit bunds As discussed above. As discussed above.

Availability and Management of Closure Material Sources

Requirement Resource Volume/Area

Earthworks area Area requiring landforming and contouring based on surface area of disturbed areas.

See Table 9-10

Other areas requiring minor earthworks/landscaping (i.e. exterior haul roads).

See Table 9-10

Topsoil Spread to areas as required at >100 mm. Topsoil stockpiled adjacent to pits.

See Table 9-10

Spread topsoil to other areas. See Table 9-10

Seeding Seed areas disturbed and topsoiled. Purchase local pioneer species seed from local supplier (or establish local supply).

See Table 9-10

Key Tasks for Unexpected (Early) Closure and/or Temporary Closure

Scenario Key Tasks Schedule

Early closure Anywhere where the early closure has resulted in a partially completed landforms, further earthworks will be required to meet the final design specifications.

This includes any non-competent material left exposed at the time of closure which will need to be covered in

At early closure

112



competent rock to the minimum thickness required by the design specifications.

Remove and/or process any remaining ore stockpiles. At early closure

Temporary closure

Put in place additional bunding and/or fencing to prevent public access to unsafe areas.

On announcement of temporary closure.

Develop underground and pit water management in the care and maintenance plans.


Establish weed management plan. During the period of temporary closure.

Information Gaps

Aspect Information Gap/Uncertainty Schedule


Determine the optimum landform profile for maximum stability and vegetation establishment success.

Ongoing

Performance Monitoring and Maintenance Schedule

Aspect Performance Monitoring and Maintenance Task Schedule

Post-closure monitoring

Implement agreed post-closure monitoring program. 2022 to 2028

Post-closure maintenance

Undertake regular inspections as per monitoring requirements to assess the need for maintenance activities.

Annually

Implement post-closure maintenance activities as required.

As required to relinquishment

113


9.1.2 HAUL ROAD CLOSURE DOMAIN TABLE 9-3 HAUL ROAD

Haul Road – Closure Task Register


The existing haul road leading to the ROM Pad will connect to the upgraded haul road connection to the Prospect pit North portal.

At the End Of Mine (EOM) the elements that will require closure consideration are:

The haul road no-longer remaining in use as part of the URPA activities.

The haul road remaining in use as part of the URPA activities.

Location URPA


Authorisations Existing haul road is part of the URPA activities, Authorisation #0539-03

New haul road not yet authorised.

Status New haul road not yet developed.

Current disturbance

Existing tracks and old Prospect Pit haul road.


2 years (LOM)


2022


2023


1 year


Post-mining land use

Natural habitat compatible with pastoral use.


Reinstate natural (unmanaged) ecosystem(s) similar to the pre-mining state that does not preclude pastoral use or inhibit surrounding pastoral use.

Rehabilitation will achieve a stable and functioning landform that is consistent with the surrounding landscapes and other environmental values and will remove potential for long term, post closure impacts on downstream water quality, beneficial uses and environmental values.


Flat area rehabilitation with gently sloping drainage.


Certification that no contamination remains in place that would prevent the closure objectives being met.

Certification that adequate topsoil is in place.

114




Closure Work Tasks


Development Stockpile soil. 2020 during construction.

Decommission Rehabilitate haul road no-longer remaining in use as part of the URPA activities.

Maintain the haul road remaining in use as part of the URPA activities.

2022 to 2023 1 year

Demolish Not applicable Not applicable

Clean-up and dispose

Not applicable Not applicable


Reshape/re-contour area to generally radially drainage and to remove any erosion prone features.

Retain locally occurring tree species where possible.

Remove any exotic plant species as required.

Deep rip all haul roads not required by the post-closure land user.

2022 to 2023 1 year


Spread available topsoil at >100 mm where required and rip on contour.

Seed with local pioneer species and mulch with any available vegetation detritus.

Create fauna habitats (e.g. using rocks and available vegetation detritus).

2022 to 2023 1 year

Security and signage

The haul road area will be safe for public access post-closure.

No security fencing or signage is required.

Stock fencing put in place around the pit bund to keep cattle off the bund surface, particularly during the early growth years immediately post-closure. Fencing will be maintained by post-closure landowner/pastoralist if required to be maintained in the long term.

Not applicable




Undertake further detailed materials characterisation for available rehabilitation cover materials. Document and use learnings from existing URPA rehabilitation.

Ongoing

115



Completion criteria

Using monitoring results, research, investigation and trials, develop criteria that are specific to the closure domains.

Ongoing


Develop specific, quantitative performance indicators for the measurement of success.

Ongoing


Continue with progressive rehabilitation and/or rehabilitation trials and subsequent vegetation performance monitoring to inform closure design.

Ongoing

Seeding Conduct ongoing trials and investigations that will inform the success of seeding.

Ongoing



Not applicable. Not applicable. Not applicable.



Earthworks area Area requiring landforming and contouring based on surface area of haul road.

See Table 9-10

Other areas requiring minor earthworks/landscaping (i.e. soil stockpile areas).

See Table 9-10

Topsoil Spread to areas as required at >100 mm. Topsoil stockpiled adjacent to haul road.

See Table 9-10

Spread topsoil to other disturbed areas. See Table 9-10

Seeding Seed areas disturbed and topsoiled. Purchase local pioneer species seed from local supplier (or establish local supply).

See Table 9-10



Early closure Anywhere where the early closure has resulted in a partially completed haul road, further earthworks will be required to meet the final design specifications.

At early closure

Remove and spread soil stockpiles. At early closure

Temporary closure



Develop care and maintenance plans. On announcement of temporary closure.

Establish weed management plan. During the period of temporary closure.

Information Gaps

116





Determine the optimum landform profile and cover design for maximum stability and vegetation establishment success.

Ongoing




Implement agreed post-closure monitoring program. Relinquishment



Annually

Implement post-closure maintenance activities as required. As required to relinquishment

9.1.3 PROSPECT SOUTH PIT CLOSURE DOMAIN TABLE 9-4 PROSPECT SOUTH PIT

Prospect South Pit – Closure Task Register


The Prospect South pit is a partially flooded open pit within the URPA. Existing non-mineralised, oxide stockpile

within the Prospect pit will provide approximately 7,000 to 12,000 t of material to construct/upgrade the portal bench in Prospect North pit prior to mine development. The Prospect South pit will be the location of a temporary waste rock dump which will be built up to approximately the decant/connection to the Prospect North pit and portal level. The Prospect South pit will be dewatered prior to waste rock placement. Most waste rock in the Prospect South pit will be returned underground during mining. Conditions within Prospect South pit are highly likely to approximate pre-underground mining conditions as a partially flooded open pit and this domain will be managed within the broader URPA Mine Closure Plan.

At the End Of Mine (EOM) the elements that will mine require closure consideration are:

The open pit

Location URPA


Authorisations The Prospect South pit is part of the URPA activities.

Using the Prospect South as a temporary waste rock facility is not yet authorised.

Status The Prospect South pit has been mined.

Current disturbance Prospect South Pit.


2 years (LOM)


2022

117




2023


1 year


Post-mining land use Not applicable. Managed within the broader URPA Mine Closure Plan.


Not applicable. Managed within the broader URPA Mine Closure Plan.




Certification that no contamination remains in place that would prevent the closure objectives being met (e.g. pit water quality).



Closure Work Tasks


Development Not applicable. Not applicable.

Decommission Remove any remaining temporary surface waste rock piles underground.



Allow the open pit to flood.



Monitor rebounded mine water quality.

2022 to 2023 1 year


Clean-up and dispose Not applicable Not applicable



Not applicable



Not applicable

Security and signage No security fencing or signage is required. Not applicable

118



Stock fencing put in place around the pit bund to keep cattle off the bund surface and from accessing pit water, particularly during the early growth years immediately post-closure. Fencing will be maintained by post-closure landowner/pastoralist if required to be maintained in the long term.





Not applicable

Completion criteria Not applicable. Managed within the broader URPA Mine Closure Plan.

Not applicable



Not applicable



Not applicable

Seeding Not applicable. Managed within the broader URPA Mine Closure Plan.

Not applicable



Not applicable Not applicable. Managed within the URPA Mine Closure Plan.

Not applicable



Earthworks area Not applicable. Managed within the broader URPA Mine Closure Plan.

Not applicable

Topsoil Not applicable. Managed within the broader URPA Mine Closure Plan.

Not applicable


Not applicable



Early closure Anywhere where the early closure temporary waste rock storage, further earthworks will be required to return the waste rock underground.

At early closure

Temporary closure Return temporary waste rock underground.



119



Temporary closure Develop care and maintenance plans.

Establish weed management plan.

During the period of temporary closure.

Information Gaps




Not Applicable





Relinquishment



Annually



9.1.4 PROSPECT NORTH PIT CLOSURE DOMAIN TABLE 9-5 PROSPECT NORTH PIT

Prospect North Pit – Closure Task Register


The Prospect North pit is a partially flooded open pit within the URPA. Existing non-mineralised, oxide stockpile

within the Prospect pit will provide approximately 7,000 to 12,000 t of material to construct/upgrade the portal bench in Prospect North pit prior to mine development. The remainder of the Prospect North pit will be utilised as a temporary water management sump. The Prospect North pit will be dewatered prior to waste rock placement. Conditions within Prospect North pit are highly likely to approximate pre-underground mining conditions as a partially flooded open pit and this domain will be managed within the broader URPA Mine Closure Plan.


The open pit

The portal ramp

The portal

Location URPA


Authorisations The Prospect North pit is part of the URPA activities. Using the Prospect North pit for the portal and portal ramp is not yet authorised.

Status The Prospect North pit has been mined.

Current disturbance Prospect North pit

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2 years (LOM)


2022


2023


1 year








Certification that no contamination remains in place that would prevent the closure objectives being met (e.g. pit water quality).



Closure Work Tasks



Decommission Remove any remaining temporary surface waste rock piles underground.

Alter portal ramp geometry to final landform if required.



Allow the open pit to flood.



Monitor rebounded mine water quality.

2022 to 2023 1 year



121





Not applicable



Not applicable

Security and signage No security fencing or signage is required.

Stock fencing put in place around the pit bund to keep cattle off the bund surface and from accessing pit water, particularly during the early growth years immediately post-closure. Fencing will be maintained by post-closure landowner/pastoralist if required to be maintained in the long term.

Not applicable





Not applicable


Not applicable



Not applicable



Not applicable


Not applicable



Not applicable Not applicable. Managed within the broader URPA Mine Closure Plan.

Not applicable




Not applicable


Not applicable


Not applicable


122




Early closure Anywhere where the early closure temporary waste rock storage, further earthworks will be required to return the waste rock underground.

At early closure

Temporary closure Return temporary waste rock underground.



Temporary closure Develop care and maintenance plans.

Establish weed management plan.


Information Gaps



Not applicable. Managed within the URPA Mine Closure Plan.

Not applicable





Not applicable



Not applicable


Not applicable

9.1.5 DAM A AND DAM C CLOSURE DOMAIN TABLE 9-6 DAM A AND DAM C

Dam A and Dam C – Closure Task Register


Dam A and Dam C are up-gradient water supply features for the URPA. Both dams have the potential to be water supply sources for the project. Dam A and Dam C will remain active beyond the project and will be managed within the broader URPA Mine Closure Plan.

At the end of mine (EOM) the elements that will mine require closure consideration are:

Dam A

Dam C

Location URPA


Authorisations Dam A and Dam C have been water supply sources at the URPA since the 1990s. Authorised under Authorisation # 0539-03.

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Status Dam A and Dam C are the current water supply sources at the URPA.

Current disturbance Dam A and Dam C are the current water supply sources at the URPA.


Beyond 2 years (LOM)















Closure Work Tasks


Development Not applicable. Managed within the broader URPA Mine Closure Plan.

Not applicable.

Decommission Not applicable. Managed within the broader URPA Mine Closure Plan.

Not applicable.

Demolish Not applicable. Managed within the broader URPA Mine Closure Plan.

Not applicable

Clean-up and dispose Not applicable. Managed within the broader URPA Mine Closure Plan.

Not applicable



Not applicable



Not applicable

Security and signage Not applicable. Managed within the broader URPA Mine Closure Plan.

Not applicable

124







Not applicable


Not applicable



Not applicable



Not applicable


Not applicable




Not applicable




Not applicable


Not applicable


Not applicable



Early closure Not applicable. Managed within the broader URPA Mine Closure Plan.

Not applicable

Temporary closure Not applicable. Managed within the broader URPA Mine Closure Plan.

Not applicable

Information Gaps




Not applicable


125






Not applicable



Not applicable

9.1.6 DAM B CLOSURE DOMAIN TABLE 9-7 DAM B

Dam B – Closure Task Register


Dam B is a down-gradient water features for the URPA. Dam B has the potential to be a water quality management features for the project. Dam B will remain active beyond the project and will be managed within the broader URPA Mine Closure Plan.


Dam B

Location URPA


Authorisations The use of Dam B as a water quality management feature is not yet authorised.

Status Dam B has been used as a water storage at the URPA since the 1990s.

Current disturbance Dam B has been used as a water storage at the URPA since the 1990s.

Life of asset disturbance Beyond 2 years (LOM)


Not applicable.


Not applicable.

Closure works duration Not applicable.









Closure Work Tasks

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Decommission Water quality testing to ensure Dam B has not been adversely impacted by the project.

2022 1 Year





Not applicable



Not applicable


Not applicable




Undertake further detailed materials characterisation for available rehabilitation cover materials. Document and use learnings from existing URPA rehabilitation.

Ongoing

Completion criteria Using monitoring results, research, investigation and trials, develop criteria that are specific to the closure domains.

Ongoing

Performance indicators Develop specific, quantitative performance indicators for the measurement of success that are based on research and monitoring outcomes.

Ongoing


Continue with progressive rehabilitation and/or rehabilitation trials and subsequent vegetation performance monitoring to inform closure design.

Ongoing

Seeding Not applicable. Not applicable.



Not applicable Not applicable Not applicable




Not applicable


Not applicable

127



Seeding Not applicable. Managed within the URPA Mine Closure Plan.

Not applicable




At early closure





Information Gaps



Determine the optimum landform profile and cover design for maximum stability and vegetation establishment success.

Ongoing



Post-closure monitoring Implement agreed post-closure monitoring program. Relinquishment



Annually

Implement post-closure maintenance activities as required.


9.1.7 CROSSCOURSE PIT CLOSURE DOMAIN TABLE 9-8 CROSSCOURSE PIT

Crosscourse Pit – Closure Task Register


The Crosscourse pit is a partially flooded open pit within the URPA which has been utilised for tailings disposal since 2002. The Crosscourse pit is planned to be utilised for tailings disposal by both the project and other projects within the URPA. The Crosscourse pit will remain active beyond the project and will be managed within the URPA Mine Closure Plan.


The open pit

Location URPA


Authorisations The use of Crosscourse pit as a tailings storage facility is an authorised activity at the URPA. Authorisation # 0539-03

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Status The Crosscourse pit is the current tailings storage facility at URPA.

Current disturbance The Crosscourse pit is the current tailings storage facility at URPA.










Post-mining land use Not applicable. Managed within the URPA Mine Closure Plan.







Closure Work Tasks



Decommission Not applicable. Not applicable.





Not applicable



Not applicable


Not applicable



129





Not applicable


Not applicable



Not applicable



Not applicable


Not applicable




Not applicable




Not applicable


Not applicable


Not applicable




Not applicable


Not applicable

Information Gaps




Not applicable



130





Not applicable



Not applicable

9.1.8 PROCESSING OPERATIONS CLOSURE DOMAIN TABLE 9-9 PROCESSING OPERATIONS

Processing Operations – Closure Task Register


The project will utilise processing operations that already exist at the URPA. After the project these authorised processing operations will remain active and be managed within the broader URPA Mine Closure Plan. The existing processing plant (mill) will be used for processing. The existing ROM will be used as the ROM for the project. The existing fuel bay, wash-down area and minor repairs workshop will be used for refueling, and repairs. The existing magazine will be used as a magazine for the project. The existing administration area, energy infrastructure, laydown and landfill areas will be utilised for the project.


The existing URPA processing plant (mill area)

The existing ROM area

The existing URPA administration area

The existing URPA laydown and landfill areas

The existing energy infrastructure

The existing fuel bay, wash-down area and minor repairs workshop

In this chapter, these are collectively referred to as the processing operations.

Location URPA


Authorisations The use of the processing operations at URPA is already authorised. Authorisation # 0539-03

Status Processing operations at the URPA have been active intermittently since the 1990s.

Current disturbance Processing operations at the URPA have been at the current disturbance scale since the 1990s.









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Closure Work Tasks


Development Not applicable. Managed within the broader URPA Mine Closure Plan.

Not applicable.

Decommission Not applicable. Managed within the broader URPA Mine Closure Plan.

Not applicable.

Demolish Not applicable. Managed within the broader URPA Mine Closure Plan.

Not applicable

Clean-up and dispose Not applicable. Managed within the broader URPA Mine Closure Plan.

Not applicable



Not applicable



Not applicable


Not applicable





Not applicable.


Not applicable.



Not applicable.



Not applicable.

132




Not applicable.



Not applicable Not applicable Not applicable




Not applicable


Not applicable


Not applicable



Early closure Notify workers, contractors and the appropriate local and government authorities.

Assign a person to authorise site access and project management of care and maintenance activities.

Process all material at the ROM or on stockpiles.

Construct fences/barriers as required to restrict access to processing areas.

Remove all petroleum, chemicals and explosive products, run down stocks or return to suppliers.

Drain all tanks and pipelines.

Shutdown mechanical, hydraulic, and electrical systems and make sure they are effectively isolated.

Remove mobile equipment, and as required salvage and sell machinery/infrastructure.

Seal, secure and lock buildings or remove/demolish demountable buildings.

At early closure

Temporary closure Notify workers, contractors and the appropriate local and government authorities.

Assign a person to authorise site access and project management of care and maintenance activities.

Process all material at the ROM or on stockpiles.

Construct fences/barriers as required to restrict access to processing areas.


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Establish a program for road maintenance to ensure access is maintained.

Continue regular inspections.

Ensure any required water management infrastructure remains operational.

Establish a schedule and continue required environmental monitoring and management activities.

Assign an appropriately qualified person to review and report all monitoring data collected.

Review and update the broader URPA Mine Closure Plan.

Information Gaps


Not applicable. Not applicable. Managed within the broader URPA Mine Closure Plan.

Not applicable





Not applicable



Not applicable

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9.2 Summary of Disturbance Areas and Required Rehabilitation Soil/Growth Medium

A summary of the above disturbance areas and closure volumes (required soil/growth medium) are presented in Table 9-10.

TABLE 9-10 DISTURBANCE AREAS AND REQUIRED REHABILITATION SOIL/GROWTH MEDIUM

Primary Areas Length

(m) Length

(km) Width

(m)

Actual Designated Area (Ha)

Actual Designated Area (m2)

Soil Resource m3 (Lower Limit

100 mm)

Soil Resource m3

(Upper Limit 1,000 mm)

Minimum Required

Rehabilitation Soil m3 (at 100 mm)

Exploration and vertical development areas#

675 0.7 360 10.1 101,213 10,121 101,213 10,121

Haul roads to be closed 400 0.4 15 0.6 6,000 600 6000 600

# Not all of exploration and vertical development area between the haul road, Prospect pits, Lady Alice pit and Crosscourse pit are disturbed. To be calculated based on

actual disturbed areas.

Breakdown of Secondary Areas Length

(m) Length

(km) Width

(m)

Actual Designated Area (Ha)

Actual Designated Area (m2)

Soil Resource m3 (Lower Limit

100 mm)

Soil Resource m3 (Upper Limit 1,000 mm)

Minimum Required

Rehabilitation Soil m3 (at 100 mm)

Not Applicable. N/A N/A N/A N/A N/A N/A N/A N/A

Total of Primary Soils Required TBC TBC TBC TBC TBC TBC TBC TBC

TBC - To be calculated based on actual disturbed areas.

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9.3 Decommissioning and Rehabilitation

NTMO will redevelop the broader URPA Mine Closure Plan (MCP) 2015 in accordance with the Western Australian

Guidelines for Preparing Mine Closure Plans (Western Australia Department of Mines and Petroleum, 2015).

Additionally, KLG is a signatory to the Responsible Gold Mining Principles set out by the World Gold Council, including

the following mine closure objective:

We will plan for the social and environmental aspects of mine closure in consultation with authorities, our

workforce, affected communities and other relevant stakeholders. We will make financial and technical

provision to ensure planned closure and post-closure commitments are realised, including the rehabilitation

of land, beneficial future land use, preservation of water sources and prevention of acid rock drainage and

metal leaching.

The structure and information in the URPA MCP 2015 will need to be reconfigured and reassessed to meet new

guideline requirements, and the revised URPA MCP is likely to be substantially different to previously submitted

versions. NTMO will work with the DPIR to agree on a realistic submission date for the redeveloped URPA MCP.

This draft EIS is focused on the recommencement of active mining operations at the URPA, and it is considered that

the risk of any unplanned closure of operations is low. However, the scenarios under which unplanned closure may

occur and the corresponding NTMO mitigation measures are outlined in Table 9-11.

TABLE 9-11 UNPLANNED MINE CLOSURE SCENARIOS AND MITIGATION MEASURES

Unplanned Closure Scenario Mitigation Measures

Significant Gold Price Drop Operations suspended and placed into care and maintenance until economic mining and processing could resume.

Development of a robust Business Case.

Operational approval by President/CEO and Board.

Annual budgets with actual and forecast expenditure.

Extensive management and operation expertise.

Major Infrastructure Failure or Incident Operations suspended until the infrastructure failure or incident is addressed, and mining and processing can resume.

Routine maintenance and inspections of infrastructure.

Risk assessments and management plans.

Emergency Response Team and Plans.

Established company insurance policies.

Instructed to Close by a Government Agency Operations suspended until any non-conformance with regulatory requirements is addressed and mining and processing can resume.

Approved Mining and Risk Management Plans.

Routine reporting of monitoring and performance.

Regular consultation to provide updates on activities, clarify expectations and management of risks.

Owner Financial Bankruptcy Operations suspended and placed into care and maintenance until assets sold by administrators.

Strong financial position with quarterly public reporting.

NI 43-101 compliant indicated gold resources.

Mid-tier gold producer with a solid base of quality assets.

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The URPA has identified NI 43-101 compliant indicated gold resources and has an established processing plant, which

are highly valued assets for mining operations. Based on this and in the event of any unplanned closure, the site would

be placed into care and maintenance and mining and/or mineral processing operations would resume in the

foreseeable future.

If no foreseeable plan for future operations is possible, then the broader, updated URPA Mine Closure Plan would be

implemented. This would dramatically increase the cost of re-opening operations in the future, but would reduce the

on-going closure liabilities.

9.4 Closure Objectives

The key closure objective specifically associated with the Union Reefs North Underground Mine is long term public

safety. The objective is to inhibit public access to underground workings. Public access will be prevented by the

construction of an abandonment bund around the Prospect pit and sealing of the portal and ventilation shafts, prior

to allowing groundwater in the pit to naturally rebound post cessation of dewatering.

Mine closure planning will also include specific approaches to protect and/or creating Ghost bat roosts and maintain

habitat stability on advice from Ghost bat consultant experts (see Chapter 11, Terrestrial Flora and Fauna).

The objective for groundwater is the recovery of groundwater levels to their pre mining levels (see Chapter 12,

Hydrological Processes). Groundwater will naturally recharge in the backfilled underground workings so that

Potentially Acid Forming (PAF) material is maintained in an anoxic subaqueous environment, long term. Groundwater

monitoring down gradient of the underground mine void will help detect any potentially contaminated seepage and

provide early warning for unexpected changes (see also Chapter 13, Inland Water Environmental Quality).

All other surface infrastructure associated with the underground mine will be decommissioned and removed with the

affected areas rehabilitated.

9.5 Potential Risks to Successful Closure, Decommissioning and Rehabilitation

Key mine closure risks are identified in Table 9-12, with the proposed mitigation measures considered as Proponent

commitments to further inform the broader URPA Mine Closure Plan.

TABLE 9-12 MINE CLOSURE RISKS

Hazard / Event – End of Life

Consequence Mitigation Measures

Poor management of waste materials during mining operations leads to closure plans being unachievable or costly.

Delays to effective rehabilitation including seepage resulting in non-sustainable ecosystems and groundwater effects.

Delays associated with cost overruns could be a period of years.

Impacts to receiving environment associated with delays.

Conceptual closure plan developed for the project prior to start-up.

Increase level of detail in closure designs during operations (detailed design level throughout mining operations).

Prepare decommissioning and rehabilitation plan.

Annual review of concept plans with updated estimates of disturbance with associated rehabilitation estimates.

Regular monitoring of identified key environmental aspects of operation that are potentially most problematic during operation and at closure i.e. temporary surface waste rock storage, seepage of mine affected water to the groundwater and associated pit lake levels.

137


Hazard / Event – End of Life

Consequence Mitigation Measures

Underground mining allows for progressive backfill and review.

Employ closure project manager.

Undertake inspections and monitoring.

Performance monitoring of progressive rehabilitation and correction of designs/execution if required.

Closure designs not developed in detail to enable appropriate closure execution, including ineffective implementation of design, poor rehabilitation execution or design failure, resulting in significantly higher closure cost above closure provisioning.

Insufficient closure cost provision resulting in inability to execute closure plan. Delays or inability to achieve effective rehabilitation by project proponent. Delays in achieving rehabilitation criterion and could be a period of years, with un-remediated project site potentially acting as source of ongoing environmental hazard.

Reporting of spills.

Contaminated sites register.

Contaminated sites report.

Contaminated sites rehabilitation designs.

Closure plan operator is responsible for site until demonstrated that able to meet agreed closure objectives and criteria.

Undertake further sampling/monitoring to accurately define level and extent of any contamination during operations.

Unexpected early closure of the project, due to delays or falling commodity prices.

Delays to effective rehabilitation by project proponent, including through erosion or seepage resulting in non-sustainable ecosystems and groundwater effects. Potentially exacerbated by closure designs not yet developed in detail at time of early closure.

Strategic long term investment in Northern territory tenements.

Concept closure plan prior to mine start up.

Commit to developing/refining closure designs through operations.

In-pit waste storage progressively returned underground during mining operations, therefore limited impact should the project enter early closure.

Bonds held by NT Government requires 110% of estimated closure cost reviewed and provided annually.

Unable to reach agreement with stakeholders on closure objectives.

Mine closure objectives unable to be implemented, delays to effective rehabilitation.

Stakeholder relationship is ongoing at URPA.

NTMO is a signatory to World Gold Council Responsible Gold Mining Principles including principles associate with stakeholder engagement.

NTMO has other interests in the region and is committed to working closely with stakeholders for long term benefit of the company and the community.

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10 RISK ASSESSMENT Risk assessment provides a framework for identifying components of the project with the potential for greater

environmental risk, and highlights areas of focus for environmental impact assessment and project specific control

measures, in order to minimise the likelihood and consequence of these identified potential impacts.

This chapter describes the risk assessment methodology, outlines the key outcomes and rankings, and summarises the

findings of the risk assessment.

The impact pathways have provided a basis for evaluation and justification of the proposed controls or management

measures to modify the risk.

10.1 Risk Assessment Methodology

The risk assessment process has been undertaken using a systematic approach consistent with AS/NZS ISO

31000:2009 Risk management – Principles and guidelines, which is schematically presented in Figure 10-1.

The early steps in the process involved establishing the context. Key considerations were setting the boundaries and

the scope of the risk assessment, including an initial project description (Chapter 4, Chapter 8) which formed the basis

for the impact and risk assessment.

After the context was established, technical specialists systematically identified potential cause-and-effect ‘pathways’

associated with the project, determining the links between project activities and the potential to impact on a given

environmental or social value or issue either directly, indirectly and/or via cumulative impact.

Once a preliminary risk register was completed by each technical specialist, a risk workshop was held to discuss the

full range of risks. This workshop allowed technical specialists from key areas to discuss interrelated risks.

A risk workshop, facilitated independently of the technical specialists and the NTMO team, was conducted over a full

day on 23 August 2019 and was attended by a cross-section of internal stakeholders and technical specialists (See

Table 10-1).

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FIGURE 10-1 RISK MANAGEMENT PROCESS (AS/NZS ISO 31000:2009)

10.1.1 RISK ASSESSMENT WORKSHOP A hazard identification and risk assessment workshop was conducted over a whole day on 11 August and 19

November 2019. The purpose of the workshop was to review the identified hazards associated with the proposed

project, identify any additional hazards and assess the risks associated with all identified hazards.

The workshop was facilitated by GHD and included a cross section of project personnel. A list of attendees is provided

in Table 10-1.

TABLE 10-1 WORKSHOP ATTENDEES

Name Title Company

Nicole Conroy Technical Director - Environment GHD

James Hill Environmental Scientist GHD

Lee Evans Technical Director - Hydrogeology GHD

Paul Barden Zoologist Ecological Management Services

Tara Steele Aquatic Ecologist Aquatic Ecology Services

Russell Schuman Principal Environmental Chemist EGI

David Faulkner Senior Geochemist EGI

Justin Moore Environmental Officer NTMO

140


Name Title Company

Sally Horsnell Environment and Community Manager NTMO

Emer McGowan Environmental Officer (Zoology) NTMO

Samantha Cseh Graduate Environmental Officer NTMO

Sam Yang Senior Environmental Officer (Hydrology) NTMO

Mark Shanhun Safety Coordinator NTMO

Allan Sinclair Safety Advisor NTMO

Sam Nethery Mine Manager - Underground Operations NTMO

Stephen Halam Project Lead - Union Reefs North Underground Mine NTMO

10.1.2 CONTEXT ESTABLISHMENT The scope of the risk assessment included construction and operation, closure and post-closure project stages on both

a local and regional scale. An initial project description was used as a basis for the risk assessments. The project

description provided details of the project footprint, project infrastructure requirements as well as construction and

operational activities and processes. The project description also established the base level of planned controls that

are inherent in the project design.

10.1.3 RISK IDENTIFICATION

To determine risks, it is necessary to identify and describe cause and effect pathways for the project (i.e.

source → pathway → receptor). Impact pathways identify the activity or event associated with the project, and give

consideration to assets, values and uses. This was done systematically for each discipline area to determine links

between project activities and their potential consequences. The list of identified risks was developed using

knowledge of the specific activities proposed for each component of the project, the local environmental context and

understanding of the potential environmental or social impacts.

10.1.4 RISK ANALYSIS AND EVALUATION Risk ratings were established for each pathway by technical specialists assigning a level of consequence in accordance

with consequence criteria for the project (Table 10-2) and a level of likelihood in accordance with likelihood

descriptors (Table 10-3).

Consequence criteria range on a scale of magnitude from ‘minor’ to ‘catastrophic’. Magnitude was considered as a

function of the size of the impact, the spatial area affected and expected recovery time. These were influenced by the

requirements of relevant legislation and guidelines.

The initial risk rating considered the likelihood (Table 10-2) and consequence of the risk event with planned controls in

place. These controls are consistent with the project description, regulatory requirements and management measures

for projects of this nature.

Risks were assessed considering the maximum credible consequence level. Combining the assessed level of likelihood

and consequence provides guidance on the risk rating (Table 10-3).The risk was then assessed against relevant criteria

as shown in Table 10-4 to determine if additional management and mitigation actions are required, or if the risk is at a

tolerable level.

In addition to the risk ratings, the assessment applied a certainty level to each overall risk rating based on the

information and data available, as listed in Table 10-5. The certainty assessment incorporated consideration of the

effectiveness of the planned controls to manage the risk and was used to assist in determining if further actions

should be focused on in order to manage risks (i.e. a confidence rating).

141


10.1.5 RISK TREATMENT Where practicable, and as required, additional control measures were developed to further reduce the risk.

The risk was then reassessed with planned and additional (as required) controls in place to confirm the effect of the

additional control measures. This second rating is known as the residual risk rating.

The controls are actions to be implemented in the delivery of the project through the construction, operation,

decommissioning, closure and post-closure phases.

10.1.6 RISK REGISTER A risk register was established to document the findings of the risk assessment process. The risk register contains

details of impact pathways, their consequences, planned controls inherent in the project description, an initial risk

assessment, additional controls and the residual risk rating.

TABLE 10-2 UNION REEFS NORTH UNDERGROUND MINE PROJECT – LIKELIHOOD DESCRIPTORS

Descriptor Explanation

Almost Certain

The event is expected to occur in most circumstances.

This event could occur at least once during a project of this nature.

91 to 100% chance of occurring during the project.

Likely

The event will probably occur in most circumstances.

This event could occur up to once during a project of this nature.


Possible

The event could occur but not expected.

This event could occur up to once every 10 projects of this nature.


Unlikely

The event could occur but is improbable.

This event could occur up to once every 10-100 projects of this nature.


Rare

The event may occur only in exceptional circumstances.

This event is not expected to occur except under exceptional circumstances (up to once

every 100 projects of this nature).

Less than 1% chance of occurring during the project.

TABLE 10-3 UNION REEFS NORTH UNDERGROUND MINE PROJECT – RISK MATRIX

Likelihood Consequence Level

Minor Medium Serious Major Catastrophic

Almost Certain Medium High High Extreme Extreme

Likely Medium Medium High High Extreme

Possible Low Medium Medium High High

Unlikely Low Low Medium Medium High

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Rare Low Low Low Medium Medium

TABLE 10-4 UNION REEFS NORTH UNDERGROUND MINE PROJECT – RISK CRITERIA

Risk Criteria

Extreme Intolerable – Risk reduction is mandatory wherever practicable. Residual risk can only be

accepted if endorsed by senior management.

High Intolerable or tolerable if managed to as low as reasonably practicable – Senior management

accountability.

Medium Intolerable or tolerable if managed to as low as reasonably practicable – Management

responsibility.

Low Tolerable – Maintain systematic controls and monitor.

TABLE 10-5 UNION REEFS NORTH UNDERGROUND MINE PROJECT – CERTAINTY DESCRIPTORS

Certainty Descriptors

High Level Risk ranking is based on testing, modelling or simulation, use of prototype or experiments.

Analysis is based on verified models and/or data. Assessment is based on an historical basis.

Medium Level Risk ranking is based on similar conditions being observed previously and/or qualitative

analysis.

Low Level Risk ranking is based on subjective opinion or relevant past experience.

10.2 Discussion of Key Outcomes

10.2.1 RISK ASSESSMENT RESULTS The environmental risk assessment identified 31 risk events, which had potential impacts on environmental receptors.

These included potential impacts on the following environmental factors:

Terrestrial flora and fauna – 15

Hydrological processes – 2

Inland water environmental quality – 12

Aquatic ecosystems – 2

All these events were assessed through the environmental risk assessment process. No risks were assessed to be

Extreme at either the initial or residual risk stage. A summary of the risk register is presented in Table 10-6. The full

risk register is presented in Table 10-7.

Of the 31 risks, 10 were ultimately rated as Medium, and 21 as Low (Table 10-6).

Five potential events were given an initial risk rating of High, and each of these reduced to Medium with additional

controls. These potential events included four related to potential impacts on Ghost bats, and one event relating to

inland water environmental quality.

Five potential events were given an initial risk rating of Medium, and retained a Medium risk rating even with the

inclusion of additional controls. These included the effects on groundwater availability at the McKinlay River

143


associated with groundwater drawdown during mining. The remaining risks were rated as Medium, and then reduced

to Low, with the application of additional controls; or were rated as Low in the initial risk assessment stage.

The project risk profile at the initial and residual risk stages is depicted in Figure 10-2 and Figure 10-3.

TABLE 10-6 SUMMARY OF RESIDUAL RISK RATINGS

Environmental Factor Risk Rating Initial Risks Residual Risks

Terrestrial Flora and Fauna

High 4 -

Medium 2 6

Low 9 9

Hydrological Processes

High - -

Medium - -

Low 2 2

Inland Water Environmental Quality

High 1 -

Medium 4 2

Low 7 10

Aquatic Ecosystem

High - -

Medium 2 2

Low - -

Total 31 31

FIGURE 10-2 INITIAL RISK RATING (AFTER PLANNED CONTROL MEASURES)

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FIGURE 10-3 RESIDUAL RISK RATING (AFTER ADDITIONAL CONTROL MEASURES)


TABLE 10-7 UNION REEFS UNDERGROUND MINE – ENVIRONMENTAL RISK ASSESSMENT

Ref. Impact Pathway Planned Controls to Manage Risk

(As per Project Description, and elements of Standards /

Codes of Practice)

Initial Risk Additional Controls Recommended to

Reduce Risk

Residual Risk Comment Applicable Technical

Report / EIS chapter

Potential Event (How the Project

interacts with assets, values, uses and

location. Include clear description of the

cause)

Environmental Factor /

Receptor

Description of Consequences

(Clearly understand what is the final impact. Describe whether it is construction,

operation or decommissioning)

Co

nse

qu

en

ce

Likelih

oo

d

Risk R

ating

Leve

l of C

ertain

ty

Co

nse

qu

en

ce

Likelih

oo

d

Risk R

ating

Leve

l of C

ertain

ty

1 Vibration emissions from mining activities result in disturbance of /or damage to roost site for individual bats or a small population of bats in OK and Prospect adits.

Terrestrial flora and fauna

If bats exit into daylight in response to the disturbance, they will be exposed to predation by raptorial birds, and exposure to unfavourable outside ambient conditions. If bats respond by not returning to the site after dusk exodus, they will be restricted to the Union North adit, or else they will need to travel further in one night to reach an alternative site, which may or may not contain a suitable roosting microclimate. I.e. bats would need to move again until they find a suitable roost and female bats in particular will need to travel further during the night to reach an optimal site for e.g. breeding and raising young during the wet season.

It is proposed to close OK and Prospect adits (i.e. exclude the Ghost bats based on carefully planned protocol, )Action 1 in the Action Plan; Armstrong et al. 2019b) prior to construction of the portal and mine operation exclusion of bats from these adits will occur in a period when bats have shifted their attention to the Union North adit, and when there is no activity of Ghost bats at the OK and prospect adits (based on seasonal patterns observed to date) to avoid significant disruption if females are giving birth and raising young.

Ma

jor

Likely

Hig

h

Med

ium

Level

Characterise the internal dimensions of OK adit and Union North adit (Action 2). Create artificial habitats (contingency roosts) for the Ghost bats in the Union Reefs project area, for both contingencies and redundancy (Action 3). Re‐open and rehabilitate the Lady Alice adit so that it is suitable for Ghost bat occupancy (Action 4). Manage the Union North adit during the period of mining to avoid direct impact from mining personnel (Action 5). Conduct a programme of continuous monitoring of Ghost bat presence, activity levels and colony size at all known (Union North adit) and potential (Lady Alice adit, artificial roost habitats newly created) roosts within the project area, (Action 7).

Ma

jor

Un

likely

Med

ium

Med

ium

Level

The OK adit and Prospect adit are likely to experience significant levels of vibration - 29.6 mm/sec and 54.6 mm/sec for the OK adit (minimum distance between estimated position of roost site and blast point 33 m) and 15.7 mm/sec and 28.9 mm/sec for the Prospect adit (minimum distance between estimated position of roost site and blast point 51 m). The Union North adit (1.2 and 2.3 mm/sec), appear to be well away from areas where relatively high vibrations are expected. Work conducted by Rio Tinto at Koodaideri in the Pilbara adjacent to a colony of the Pilbara diamond‐faced bat (R. aurantia) suggested that vibration levels below 10 mm/sec is sufficient not to cause a significant disturbance to this species (Appendix G).

Appendix G Chapter 11.3.2

2 Temporary closure of OK adit during mine development and mine operations.


Habitat loss- temporary removal of one of two Ghost bat diurnal roost sites in the Union Reefs area and possible breeding site. This also represents a loss of redundancy in the event that one remaining roost becomes unsuitable or is disturbed.

As an anticipated contingency action, redundancy of roosting opportunity will be created within the Union Reefs project area through the provision of several artificial roost habitats and the modification of the Lady Alice adit to be more suitable for the Ghost bat (Actions 3 and 4 in the Action Plan; Armstrong et al. 2019b). Concurrent novel and collaborative management of stronghold sites at Pine Creek

Med

ium

Alm

ost C

ertain

Hig

h

Med

ium

Level

Undertake Field surveys for Ghost bat diurnal roosts in caves in the hills surrounding the Union Reefs project area (Action 9). Undertake a genetic study to determine whether the colony in the Union reefs project area is connected to those at Pine Creek and Spring Hill (Action 10). Given fluctuations in colony size

Med

ium

Po

ssible

Med

ium

Med

ium

Level

Individual: Alternative optimal roosts include: Union North adit, as well as the Kohinoor adit at Pine Creek, Spring Hill stopes (to be confirmed by genetic analysis), plus a modified Lady Alice adit and several artificial roosts with the Union reefs area (assuming the modelled microclimates are suitable). Colony: The colony appears to change in size because of



and Spring Hill will also increase the security of alternative roost sites further afield in the region (Action 6). The security of the colony using Union North adit will be maintained through education of personnel and restricting access (Action 5). Closure of the OK adit will be timed to avoid the presence of breeding individuals in the OK adit, particularly those with young (Action 1). Conduct a programme of continuous monitoring of Ghost bat presence, activity levels and colony size at all known (Union North adit) and potential (Lady Alice adit, newly created artificial roost habitats) roosts within the project area (Action 7).

observed in the Union Reefs project area since August 2018, it is expected that genetic markers will confirm the connectedness of regional colonies - and therefore that Pine Creek and Spring Hill are alternative roost sites. The colonies at Pine Creek and Spring Hill are both within 15 km from the Union Reefs adits, and Ghost bats are likely to be able to fly this distance in a single night. Conduct a programme of continuous monitoring of Ghost bat presence, activity levels and colony size at all known (Union North adit) and potential (Lady Alice adit, newly created artificial roost habitats) roosts within the project area (Action 7). Working with PC Gold on Ghost bat monitoring at Spring Hill.

the movement of individuals in and out of the project area, colony size has been counted at between 11 and c. 30 individuals throughout monitoring since October 2018). The temporary blockage of a relatively shallow roost (the OK adit) is predicted to be insignificant given access to known and predicted alternatives of greater depth. Regional Population: Given the indirect evidence that Ghost bats can readily move in and out of the Union Reefs project area to sites known and possibly unknown, the impact of the closure of the OK adit is unlikely to be significant for the regional population. If the Union North adit can be maintained as a protected roost site, and if other planned additional sites are indeed provided, then the Union Reefs area will likely remain an important stepping‐stone between Pine Creek, Spring Hill and any other sites used by Ghost bats in the region.

3 Vibration emissions from mining activities result in disturbance of individual bats or a small population of bats in Union north adit and other modelled locations.


If bats exit into daylight in response to the disturbance, they will be exposed to predation by raptorial birds, and exposure to unfavourable outside ambient conditions. If bats respond by not returning to the site after dusk exodus, they will be restricted to the Union North adit, or else they will need to travel further in one night to reach an alternative site, which may or may not contain a suitable roosting microclimate.

Numerical modelling undertaken to quantify magnitude of vibration emissions at sites relevant to the Ghost bat at URPA (GHD 2019, in Appendix G). Conduct a programme of continuous monitoring of Ghost bat presence, activity levels and colony size at all known (Union North adit) and potential (Lady Alice adit, newly created artificial roost habitats) roosts within the project area (Action 7).

Med

ium

Un

likely

Low

High

Level

The project has the capacity to adjust blasting pattern / timing / sequence / duration if the blasting is having an impact.

Med

ium

Un

likely

Low

High

Level

Union North adit (1.2 and 2.3 mm/sec), appear to be well away from areas where relatively high vibrations are expected.


4 Ground borne noise emissions from mining activities result in disturbance of


If bats exit into daylight in response to the disturbance, they will be exposed to predation by

None required. Min

or

Un

likely

Low

High

Level

None required. Min

or

Un

likely

Low

High

Level

Noise levels produced by blasting are not expected to present a significant effect to the Ghost bat.



individual bats or the colony of bats in the URPA.

raptorial birds, and exposure to unfavourable outside ambient conditions. If bats respond by not returning to the site after dusk exodus, they will be restricted to the Union North adit, or else they will need to travel further in one night to reach an alternative site, which may or may not contain a suitable roosting microclimate.

The blasting will take place underground, so noise will be ground‐borne, i.e. re‐radiated from the ground into the airspace of a tunnel. Levels were modelled to be relatively low (75 dBA at OK adit; 62 dBA at Union North), roughly equivalent to human conversation.

5 Union North adit is flooded during the wet season.


The Union North adit becomes a sub-optimal roost, which might cause bats to aggregate in fewer roost sites, and which might also limit breeding activity (birthing, raising young) of females.

Prior to mine development, the interior structure of the Union North adit will be inspected to determine depth and extent, stability, the presence of crosscuts / stopes / shafts / etc., and the position of guano piles indicating Ghost bat roost position (Action 2), if it is considered safe for entry by experienced investigator. This will provide information on the extent of likely flooding. Water will be pumped out of Union North adit if monitoring detects that pumping is required to keep the adit in use by Ghost bats.

Ma

jor

Po

ssible

Hig

h

Low

Level

Create artificial habitats (contingency roosts) for the Ghost bats in the Union Reefs project area, for both contingencies and redundancy (Action 3). Re‐open and rehabilitate the Lady Alice adit so that it is suitable for Ghost bat occupancy (Action 4). Manage the Union North adit during the period of mining to avoid direct impact from mining personnel (Action 5). Conduct a programme of continuous monitoring of Ghost bat presence, activity levels and colony size at all known (Union North adit) and potential (Lady Alice adit, newly created artificial roost habitats) roosts within the project area (Action 7).

Ma

jor

Un

likely

Med

ium

Med

ium

Level


6 Damage to the structure of Union North adit - entrance blockage or internal collapse associated with mining or not.


Loss of an entire colony if the collapse/blockage occurs during the day. Loss of the roost site, further limiting the roost options of Ghost bats in the region.

Prior to mine development, the interior structure of the Union North adit will be inspected to determine depth and extent, stability, the presence of crosscuts / stopes / shafts / etc., and the position of guano piles indicating Ghost bat roost position (Action 2), if it is considered safe for entry by experienced investigator. The Union North adit will be inspected during regular visits (as part of regular monitoring; Action 7) and in the event of a

Ma

jor

Un

likely

Med

ium

Low

Level

Create artificial habitats (contingency roosts) for the Ghost bats in the Union Reefs project area, for both contingencies and redundancy (Action 3). Re‐open and rehabilitate the Lady Alice adit so that it is suitable for Ghost bat occupancy (Action 4). Manage the Union North adit during the period of mining to avoid direct impact from mining

Ma

jor

Ra

re

Med

ium

Low

Level

The likelihood of collapse of the structure cannot be predicted with any certainty without survey of internal stability.

Appendix G Chapter 11.3.4, 11.6


collapse affecting the entrance portal, any blockage to the entrance of the Union North adit will be removed.

personnel (Action 5). Conduct a programme of continuous monitoring of Ghost bat presence, activity levels and colony size at all known (Union North adit) and potential (Lady Alice adit, newly created artificial roost habitats) roosts within the project area (Action 7). Action 5 will also be implemented at Spring Hill, if future circumstances allow.

7 Malevolent actions at a roost that cause disturbance and/or mortality of bats, in particular Kohinoor adit at Pine Creek that is easily accessible to the public.


Deaths of any proportion of a colony, but most likely at Pine Creek, and/or relocation of some or all of the colony in response, possibly to suboptimal sites temporarily.

Implement novel and collaborative management measures at the Koohinoor adit at Pine Creek to protect the Ghost Bat roost, as outlined in Action 6 of the Action Plan (Armstrong et al. 2019b). In the Union North project area, the Union North adit will be managed during the period of mining to exclude visitation from mining personnel (details in Action 5). Community awareness of Ghost bats at pine creek increases due to Company education program (Action 6).

Ma

jor

Po

ssible

Hig

h

Med

ium

Level

Action 5 will also be implemented at Spring Hill, if future circumstances allow.

Ma

jor

Ra

re

Med

ium

Low

Level Appendix G

Chapter 11.3.4, 11.6

8 Collapse or blockage of historical adit from random deterioration (Pine Creek, Spring Hill).


Loss of an entire colony if the collapse/blockage occurs during the day. Loss of the roost site, further limiting the roost options of Ghost bats in the region.

No mitigation is possible without disturbing the colony. Regular monitoring will be conducted to detect if this occurs (Action 7). With increased scrutiny of these sites during monitoring and other examinations, observations that suggest the potential for collapse or blockage may allow a mitigation to be implemented if issues are discovered.

Ma

jor

Ra

re

Med

ium

Low

Level

Ma

jor

Ra

re

Med

ium

Low

Level

This potential risk is not directly related to the project but is relevant given OK adit will be temporarily removed from regional roost opportunity.


9 A disturbance to a roost site, including OK adit, at a critical part of the breeding cycle that causes an interruption to breeding activity and


The total reproductive output of the regional population could fall by up to 10% for two years as a worst case if bats remain at Union Reefs, but are prevented from breeding

Closure of the OK adit will be timed to avoid the presence of breeding individuals in the OK adit, particularly those with young (Action 1 in the Action Plan; Armstrong et al. 2019b). In addition, manage the Union

Seriou

s

Ra

re

Low

Med

ium

Level

Min

or

Un

likely

Low

Low

Level



lowered reproductive output.

because of interruptions. This assumes the 30 animals at Union Reefs are all female, all produce one young, and all young perish. This scenario that seems very unlikely, so the risk has been calculated accordingly.

North adit during the period of mining to exclude visitation from mining personnel (Action 5).

10 Coincident, uncoordinated and non-prioritised research resulting in unnecessarily elevated levels of disturbance through duplication of effort.


Compounded disturbance, removal of alternatives to a disturbed roost site.

Support for a postdoctoral research position will be provided (as part of Action 11 in the Action Plan; Armstrong et al. 2019b) to coordinate efforts of industry in the region (as detailed in the Action Plan) and additional independent research. Publication of communications material so that community awareness is increased and publication of research to increase knowledge Mining operators’ forum to discuss regulatory and operational matters.

Min

or

Un

likely

Low

Low

Level

Min

or

Un

likely

Low

Low

Level


11 Field surveys in the hills surrounding Union Reefs reveal no alternative natural roosts.


Bats will need to travel further in one night to reach an alternative site, or roost temporarily in a suboptimal site until they reach a more suitable site.

As an anticipated contingency action, redundancy of roosting opportunity will be created through the provision of several artificial roost habitats and the modification of the Lady Alice adit to be more suitable for the Ghost bat (Actions 3 and 4 in the Action Plan; Armstrong et al. 2019b). These actions will be implemented well before the closure of OK adit.

Min

or

Po

ssible

Low

Low

Level

Action 10 - knowledge generation around connectedness of colonies using genetic markers.

Min

or

Po

ssible

Low

Med

ium

Level

Appendix G Chapter 11.3

12 Bats disperse to suboptimal roosts, rather than Union North adit or larger stronghold roosts, after the OK adit is closed.


Some individuals may be forced to occupy a suboptimal roost until they can reach another, better site.

As an anticipated contingency action, redundancy of roosting opportunity will be created through the provision of several artificial roost habitats and the modification of the Lady Alice adit to be more suitable for the Ghost bat (Actions 3 and 4 in the Action Plan; Armstrong et al. 2019b).

Min

or

Po

ssible

Low

Low

Level

Action 10 - knowledge generation around connectedness of colonies using genetic markers.

Min

or

Po

ssible

Low

Low

Level

While ghost bats prefer warm, humid roosts, individuals have often been seen in cooler and drier roosts (e.g. K.N. Armstrong unpublished observations in the Pilbara), so a temporary stop-over in such conditions is unlikely to be fatal for most or all individuals.


13 Dewatering for the mine reduces levels of groundwater that keep roosts humid for Ghost bats.


The roost will dry out and become unsuitable for use.

As part of Action 2 (outlined in the Action Plan; Armstrong et al. 2019b), temperature and relative humidity data loggers will be installed in these two

Min

or

Po

ssible

Low

Low

Level

Min

or

Po

ssible

Low

Low

Level

The effect of dewatering in the Prospect pit is not expected to extend to the Union North pit, and thus the amount of groundwater



mines, if entry to investigators is considered to be safe. Mitigative actions such as the manual introduction of water could be implemented if data loggers show the roost to be drying out - as part of adaptive management response.

available to the Union North adit and Lady Alice adit to keep microclimates humid is unlikely to change.

14 Young bats in the later stages of development perish after being abandoned in roosts by adults moving out of the Union Reefs area in response to a disturbance or closure of the OK adit.


The young bats would likely perish and a years’ worth of breeding lost (including females that will contribute to breeding in the future) - note: Cannot estimate how many young will perish because do not know how many females there are in existing colony. This is deemed unlikely because closure of the OK adit will be timed to avoid this.

Closure of the OK adit will be timed to avoid the presence of breeding individuals in the OK adit, particularly those with young (Action 1 in the Action Plan; Armstrong et al. 2019b). Serio

us

Ra

re

Low

Med

ium

Level

Min

or

Po

ssible

Low

Low

Level


15 Waste-water in open pit mine voids contains pollutants that might reduce rates of survival in Ghost bats.


Flooded mine voids have been present in the Union Reefs project area for many years, Ghost bats are unlikely to come into direct contact with water in mine voids because they are not known to drink free water from pools (water comes from their prey).

No mitigative action is required. The post-doctoral research will look at importance of water bodies for hydration.

Min

or

Ra

re

Low

Low

Level

Min

or

Ra

re

Low

Low

Level


16 Drawdown from mine dewatering will result in reduction in groundwater available for other users.

Hydrological processes

Drawdown propagates southwards and impacts groundwater availability for the Pine Creek township (PWC bores).

Comparative assessments to previous dewatering. Groundwater modelling, monitoring against modelling results, potential for mitigation via substitute water supply if required. Water Management Plan.

Seriou

s

Ra

re

Low

High

Level

Additional groundwater monitoring locations and relatively high frequency monitoring, providing additional time for mitigation and management of risk. Additional modelling to be completed to increase the level of certainty around this assessment.

Seriou

s

Ra

re

Low

High

Level

Numerical analysis indicates groundwater levels and availability at Pine Creek will not be affected. Additional monitoring points between risk receptor to confirm.

Appendix H Chapter 12.3.2, 12.6


Hydrological processes

Drawdown propagates and impacts groundwater availability for adjacent stations (closest stock and domestic bores) and other miners (Territory Iron rail siding bore).

Comparative assessments to previous dewatering. Groundwater modelling, monitoring against modelling results. Water Management Plan (WMP).

Med

ium

Un

likely

Low

Med

ium

Level

Additional groundwater monitoring locations and relatively high frequency monitoring, providing additional time for mitigation and management of risk.

Med

ium

Ra

re

Low

High

Level

Numerical analysis indicates groundwater levels and availability at neighbouring bores are unlikely to be affected. Additional monitoring points between risk receptor will reduce likelihood and consequence.

Appendix H Chapter 12.3.2, 12.6



Aquatic ecosystems

Drawdown in the aquifer delivers less water available for discharging to the McKinlay River (and baseflows in the Mary River catchment area) and impacts refuge water quality and longevity (and therefore available habitat, space and substrate).

Comparative assessments to previous dewatering. Groundwater modelling, monitoring against modelling results. Water Management Plan (WMP). Serio

us

Po

ssible

Med

ium

Med

ium

Level

Additional groundwater monitoring locations, relatively high frequency groundwater level monitoring and assessment. GDE and SW monitoring throughout project, as per WMP. Additional modelling to be completed to increase the level of certainty around this assessment. Potential for (short term) mitigation via specific planned substitute water releases if required.

Seriou

s

Un

likely

Med

ium

High

Level

Numerical analysis indicates groundwater levels will not be affected along McKinlay River. Groundwater availability may be reduced temporarily. If there is a dry wet season, the impact is greater.

Appendix J Chapter 14.3.2, 14.6


Aquatic ecosystems

Drawdown impacts groundwater availability for terrestrial fauna and flora (GDEs).

Comparative assessments to previous dewatering. Groundwater modelling, monitoring against modelling results. Water Management Plan (WMP). Field survey.

Seriou

s

Po

ssible

Med

ium

Med

ium

Level

Additional terrestrial flora and fauna surveys throughout project to confirm lack of presence of additional GDEs.

Seriou

s

Un

likely

Med

ium

High

Level Numerical analysis indicates groundwater levels in general will not significantly affected in any additional areas likely to contain GDEs.

Appendix J Chapter 14.3.2, 14.6

20 Contaminated seepage during surface storage of underground mine waste rock (241,000 t temporarily stockpiled).


Acidic pH, salinity and/or metals/metalloids affecting groundwater and/or surface water flowing into the mine or into surface water within Prospect pit. May also affect capacity to discharge water from Crosscourse pit if seepage from waste material contributes significantly to a decline in water quality as a result of capture and pumping to Crosscourse.

Undertake AMD test work to confirm level of risk - Static testing ahead of mining to develop waste rock segregation criteria and management options. Use geochemical data as an input into model to help predict likely water quality during and post operations. Implement AMD management plan inc. segregation of high As/PAF wastes during surface storage, and ensure this material is used during backfill for closure and only NAF low As material left at surface. Waste storage to minimise oxidation and reduce acid leachate. Seepage will be captured and pumped constantly into in Crosscourse pit- captured seeps pumped into Prospect North pit (short term) and then pumped to Crosscourse pit.

Seriou

s

Ra

re

Low

Med

ium

Level

Given the small volume (≈130,000 m3) of waste, increasing pump capacity could be applied in the unlikely event that poor quality seepage occurs to prevent infiltration during the wet season.

Seriou

s

Ra

re

Low

Med

ium

Level

While no kinetic geochemical test work has been done, static test work indicates that most (≈90%) of the material to be stored is NAF with very low levels of leachable metals/metalloids. Kinetic test work conducted by EGi on other sites with similar geology in the Pine Creek region suggests co-disposal (encapsulation) of PAF material with NAF, results in substantial attenuation of metals (Cu, Fe, Pb, Zn) and metalloids (As) leached from PAF materials and mitigates against poor quality drainage.

Appendix F Chapter 13.3

21 Contaminated seepage from permanent surface storage (i.e. in-pit


Acidic pH, salinity and/or metals/metalloids causing ongoing damage to ecosystems, groundwater

Undertake AMD test work to develop waste rock segregation criteria and management options.

Seriou

s

Un

likely

Med

ium

Med

ium

Level

Recontour permanent portal development post operation and store sub-

Seriou

s

Ra

re

Low

Med

ium

Level

Material used to construct the portal ramp and bench area will be oxidised rock sourced from the pit. The

Appendix F Chapter 13.3


storage in Prospect pit) of underground mine waste rock (50,000 t) and waste rock sourced from the Prospect North pit used in the portal development.

and/or surface water during operations and post closure.

Use only NAF material with low metal/metalloid leaching for construction of the portal bench.

aqueously to minimise reactivity.

further 50,000 t of waste rock used for portal development which will also remain in pit post-mining will be “first cut” rock from the decline development. This material will be sourced from the oxidised profile. Geochemical testing of oxide material indicates that it is non-acid forming. Therefore, portal development waste which will remain permanently in pit is not expected to adversely change groundwater quality.

22 Contaminated seepage/runoff from oxidation of sulphidic rocks in the walls of Prospect pit exposed to the atmosphere following dewatering and/or, change in groundwater quality as a result of dissolution of oxidation products after groundwater rebound following closure.


Acidic leachate may open up new oxygen pathways in pit walls and add to the load of contaminants in pit water pumped to Crosscourse pit. This can potentially adversely affect water quality in Crosscourse pit during operation and, with potential impact on surrounding groundwater and surface water bodies connected to Crosscourse. Decline in pit water quality post closure could adversely impact down gradient aquatic ecosystems.

Collect water samples and monitor during the operation to understand the level of contamination from the runoff of the walls in the Prospect pit. If it is understood to be a problem, an engineering solution should be applied to prevent seepage to groundwater. Serio

us

Un

likely

Med

ium

Low

Level

Pump out accumulating runoff in prospect pit quickly to reduce volume infiltrating. During operation Seepage will be captured and pumped constantly into in Crosscourse pit - At closure flood back to pre - mining levels.

Seriou

s

Ra

re

Low

Low

Level During operation any runoff that collects in the Prospect pit will be pumped to Crosscourse pit. Water quality will be assessed during operation and measures can be put in place once this is known. Water quality monitoring conducted over a last 10 years demonstrates relatively good water quality in the smaller pit lakes at URPA including Prospect North. Since these pit walls will have been exposed during the original mining operations, it appears this has not resulted in poor water quality following refill of the pit. This suggests it is unlikely that the proposed project will produce poor water quality in Prospect North pit post closure as a result of exposure of the pit walls to the atmosphere during mining.

Appendix I Chapter 13.3

23 Crosscourse pit is left unmanaged (no management of water level) and allowed to fill to high pit lake conditions.


Crosscourse pit becomes source - outward seepage leaving crosscourse pit and contaminating groundwater and downstream aquatic ecosystems in the McKinlay River. i.e. Acidic pH, salinity and/or metals causing ongoing damage to ecosystems,

Maintain the water level in the Crosscourse pit such that it remains a sink, i.e. manage the volume of water coming into and out of the pit via water recycle to process plant and via treatment and discharge under licence in the wet season to reduce the water level. This will maintain the balance and

Ma

jor

Po

ssible

Hig

h

Low

Level

Maintain Crosscourse as a groundwater sink by keeping the water level below the water table either by discharging or other engineering approach, e.g. enhanced evaporation by use of mechanical sprays. Additional groundwater

Ma

jor

Un

likely

Med

ium

Low

Level



shallow groundwater and surface water

minimise the risk of seepage.

monitoring locations and relatively high frequency monitoring, providing additional data for mitigation and management of risk. GDE and SW monitoring throughout project, as per WMP. Additional modelling to be completed to increase the level of certainty around this assessment. If for some reason it still becomes a source, apply an engineering solution such as management of Dam B water to prevent groundwater seepage down gradient.

24 Contaminated seepage from Crosscourse pit migrating to the underground development during operations.


This could result in the accumulation of water with elevated levels of dissolves species such as Zn and As. In the Crosscourse pit.

Water seeping from the base of the pit to underground operation will be captured by pumping from the underground operation. The water will be recirculated back to Crosscourse Pit.

Med

ium

Po

ssible

Med

ium

Low

Level

Water treatment under waste water discharge licence lowers water level in Crosscourse pit Monitoring water quality both in the underground and the Crosscourse Pit.

Med

ium

Un

likely

Low

Low

Level

The water will be recirculated during the operations. It is possible that it will be of poorer quality than current Crosscourse Pit water, however, given the small volume of water in Prospect pit compared to the total volume in Crosscourse pit, it is expected to have minor impact.


25 Contaminated seepage from underground development and backfilled waste rock and/or pit walls at closure infiltrating groundwater.


Acidic pH, salinity and/or metals causing ongoing damage to ecosystems, groundwater and/or surface water at closure.

Sampling and monitoring of water quality during mining operation to understand the level of contamination as backfilling takes place. Develop mitigation measures as required during operation in planning for closure.

Ma

jor

Un

likely

Med

ium

Low

Level

Groundwater quality monitoring during operation and development of options for mixing of backfill with suitable neutralising material (e.g. lime) to prevent acid leaching of metals. Manage Crosscourse pit water level.

Ma

jor

Ra

re

Med

ium

Low

Level

If mixing with acid neutralising material does not produce required results in accordance with the ANZECC (2000) guidelines, then water treatment may be required as potential management strategy.


26 AMD from ROM pad leading to contaminated seepage run-off.


Damage to associated surface water and aquatic ecosystems in the McKinlay River.

ROM pad has been recontoured and drains to Crosscourse pit rather than to Dam B.

Med

ium

Un

likely

Low

High

Level

Bund ROM pad, capture run-off and pump to Crosscourse pit. M

ediu

m

Ra

re

Low

High

Level

Long-term water quality monitoring including an extensive period of Plant operation (2011-2017), demonstrates that, while some impacted water drained from the ROM pad to Dam B and Sediment Trap



3, there is no evidence of elevated metal/metalloids in McKinlay River downstream from the passive discharge point indicating effective attenuation through dilution, adsorption, and precipitation.

27 Failure of pumps to redirect accumulating water in Prospect resulting in infiltration to groundwater.


If the water is of poor quality this may have potential to impact receptors down-gradient.

Ensure that spare pumps and generator are available for emergency backup of pumping. Pump capacity for 1000 year ARI back up pumps will be available on site

Min

or

Po

ssible

Low

Med

ium

Level

Accumulation of water will be a slow process, therefore the risk of pumps failing is lower.

Min

or

Un

likely

Low

Med

ium

Level

This control needs to be included in the Water management plan.

Water Management Plan Chapter 13.3

28 Poor management of waste materials during operations leads to closure plans being unachievable or costly.


Delays to effective rehabilitation including seepage resulting in contaminated ecosystems and groundwater effects. Delays associated with cost overruns could be a period of years. Impacts to receiving environment associated with these delays.

• Conceptual closure plan at start-up. • Increase level of detail in closure designs during operations • Prepare decommissioning and rehabilitation plan. • Annual review of concept plans with updated estimates of disturbance with associated rehabilitation estimates. • Regular monitoring of identified key environmental aspects of operation that are potentially most problematic during operation and at closure i.e. temporary surface waste rock storage, seepage of mine affected water to the groundwater and associated pit lake levels. • Underground mining allows for progressive backfill and review. • Employ closure project manager. • Undertake inspections and monitoring. • Performance monitoring of progressive rehabilitation and correction of designs/execution if required. working in conjunction with centre for mine rehabilitation at UQ to understand latest technology and rehabilitation methods

Seriou

s

Ra

re

Low

High

Level

Seriou

s

Ra

re

Low

High

Level KLG understands costs and consequences of poor planning and intends to avoid poor planning.

Chapter 9.5, 13.3


29 Closure designs not developed in detail to enable appropriate closure execution, including ineffective implementation of design, poor rehabilitation execution or design failure, resulting in significantly higher closure cost above closure provisioning.


Insufficient closure cost provision resulting in inability to execute closure plan. Delays or inability to achieve effective rehabilitation by project proponent. Delays in achieving rehabilitation criterion and could be a period of years, with un-remediated project site potentially acting as source of ongoing environmental hazard.

• Reporting of spills. • Contaminated sites register. • Contaminated sites report. • Contaminated sites rehabilitation designs. • Closure plan operator is responsible for site until demonstrated that able to meet agreed closure objectives and criteria. • Undertake further sampling/monitoring to accurately define level and extent of any ground contamination during operations.

Seriou

s

Ra

re

Low

High

Level

Seriou

s

Ra

re

Low

High

Level

Chapter 9.5, 13.3

30 Unexpected early closure of the project, due to delays or falling commodity prices or another unexpected issue.


Delays to effective rehabilitation by project proponent, including through erosion or seepage resulting in contaminated ecosystems and groundwater and / or surface water effects. Potentially exacerbated by closure designs not yet developed in detail at time of early closure.

• Strategic long term investment in Northern Territory tenements. • Concept closure plan at mine start up. • Commit to developing/refining closure designs through operations. • In-pit waste storage progressively returned underground during mining operations, therefore limited impact should the project enter early closure. • Bonds held by NT Government requires 110% of estimated closure cost reviewed and provided annually. Sale of the asset includes maintenance obligations moving to new owner

Seriou

s

Ra

re

Low

High

Level

Seriou

s

Ra

re

Low

High

Level

Chapter 9.5, 13.3

31 Unable to reach agreement with stakeholders on closure objectives.


Mine closure objectives unable to be implemented, delays to effective rehabilitation.

• Stakeholder relationship is ongoing at URPA. • NTMO is a signatory to World Gold Council Responsible Gold Mining Principles including principles associate with stakeholder engagement. • NTMO has other interests in the region and is committed to working closely with stakeholders for long term benefit of the company and the community.

Seriou

s

Ra

re

Low

High

Level

Seriou

s

Ra

re

Low

High

Level

Chapter 9.5, 13.3


NTMO will engage with stakeholders during the early closure planning and implementation

157


11 TERRESTRIAL FLORA AND FAUNA

11.1 Overview

This chapter addresses the potential impacts of the project on the Ghost bat (Macroderma gigas), as required for

the TOR. The Ghost bat is currently listed as ‘Vulnerable’ under the Commonwealth EPBC Act 1999 and ‘Near

Threatened’ under the Territory Parks and Wildlife Conservation Act.

Section 2.2.1 of the EIS TOR provide the following environmental objective:

To protect the NT’s flora and fauna so that biological diversity and ecological integrity are maintained.

The TOR provide a series of information requests specifically related to the distribution and ecology of the Ghost

bat at the URPA and in the wider region (Appendix A).

A detailed technical report is provided in Appendix G, including a detailed description of the desktop (including

reference sources) and field survey components of this assessment. This chapter summarises the technical report

including baseline data on the presence, activity levels and colony size of Ghost bats in the URPA in 2018 and

2019, including two consecutive breeding seasons, and provides an assessment of potential impacts of the

current underground mining project for the URPA.

An Action Plan for the Management of Ghost Bats in the URPA (Appendix 2 of Appendix G) informs the mitigation

measures outlined in this chapter. The overall objective of the Action Plan is to enact measures that will protect

Ghost bats from the potential impacts of project-related mining activity, anticipate and provide for

contingencies, and contribute to knowledge and conservation of the Ghost bat at the local, regional and national

scale. In addition, the overall vision of NTMO is to be recognised as a national leader in efforts to manage,

conserve and support research on the threatened Ghost bat.

11.2 Environmental Values

11.2.1 ECOLOGY AND CONSERVATION STATUS OF THE GHOST BAT

The Ghost bat has a history of decline across its broad Australian distribution. In the past 50 years there is

evidence of declines in natural roost caves, and the loss of several roost sites due to mining activity in

Queensland and the Northern Territory, including within the Pine Creek region. Losses of roost sites in the past

decade were an important consideration in the listing of the Ghost bat as Vulnerable under the EPBC Act 1999.

Ghost bats are one of the few carnivorous species of bat, with their diet consisting of small mammals (including

other bats), birds, reptiles, frogs and large insects, varying regionally and depending on seasonal availability.

Ghost bats forage either by ambushing passing prey in the air or on the ground. Most prey is taken to a feeding

perch in trees, rock overhangs, or cave entrances to be consumed. These ‘nocturnal refuges’ tend to be more

numerous than diurnal (daytime) roost sites.

Types of roosts utlilised by Ghost bats include the following:

Diurnal/daytime roost: An underground structure where Ghost bats remain during daylight hours, and

sometimes during the night. Diurnal roosts host reproductive activity and provide the specific micro

climactic conditions required by Ghost bats to thrive and survive.

Nocturnal refuge/feeding site: A site where bats may hang to rest periodically during the night, and

where they may consume captured prey. They will not utilise these roosts during daylight hours due to

being exposed to day time ambient climactic conditions.

Studies in the Northern Territory have shown that foraging areas were an average of 1.9 kilometres (km) from

roosts and 62 hectares in size. However, wing morphology suggests they are capable of a much greater nightly

range and have been recorded foraging at least 10 km from suitable roost sites.

Ghost bats emerge from the diurnal roost shortly after sunset, moving directly to an area where they forage for

approximately two hours. This is generally followed by a period of inactivity until the early morning when feeding

158


activity begins again, prior to returning to the roost before sunrise. They move between different foraging areas

but will also revisit foraging areas on consecutive nights.

Ghost bats roost in deep limestone or sandstone caves, shallow sandstone caves with domed ceilings or in

historical mine sites i.e. disused mine adits. The types of subterranean structures that provide diurnal roosts and

support the larger colonies of Ghost bats and act as breeding sites are generally deep, with warm, humid

microclimates. These sites are less common in the landscape than simple shallow caves and rock overhangs that

have microclimates closer to external ambient conditions. This means that roosting opportunities are limited at

critical times of the year. Given the absence of landscape and geological features supporting natural cave

systems within the URPA, sites supporting Ghost bat colonies are restricted to historical mine workings. These

artificial roosts can provide critical maternity sites, routine diurnal roost sites and dispersal stop-over roosts.

Culverts, out-buildings and other artificial structures are also used as short-term day roosts.

Females give birth to a single young and occasionally twins. Birth occurs over the period of a month commencing

in August in the NT. Young can be shifted to other warm caves as summer progresses. Juvenile bats commence

flying at seven weeks, with all young capable of flight by the end of January.

A distinctive trait of the Ghost bat is site fidelity of females, which results in stable breeding colonies. This

tendency of females to stay at the site of their birth, results in a low likelihood of short-term female

recolonisation should they be dispersed or extirpated from a breeding site.

11.2.2 GEOGRAPHIC EXTENT OF THE REGIONAL POPULATION

The Ghost bat exists as a fragmented group of geographically and genetically isolated populations across

northern Australia, with less than 10,000 individuals in existence. Ghost bat distribution ranges from the Pilbara

and Kimberley regions of Western Australia, through the Top End and Gulf Fall country of the Northern Territory,

to parts of northern Queensland. Important Northern Territory Ghost bat populations occur within the Pine

Creek, Katherine, southern Kakadu and Litchfield regions, centred on both natural and artificial roosts.

Existing data estimates a regional Ghost bat population, centred on Pine Creek and including Spring Hill to the

north and Claravale Station to the south, at between 570 and 1,132 individuals. Uncertainties in this data relate

to locations that have not been inspected recently and the potential for undocumented roosts. However, a large

proportion of this regional population estimate was generated from sites where there is recent count data,

including Kohinoor adit, Spring Hill, Union Reefs and Claravale Station.

The Pine Creek regional Ghost bat population potentially comprises 8.1 % to 12.5 % of the national Ghost bat

population, based on recent count data and the total Ghost bat population estimate for the IUCN Red List. Based

on these population figures, the Union Reefs population potentially represents 2.6 % of the upper estimated

regional Ghost bat population and 0.3 per cent of the upper estimated national (global) Ghost bat population.

The Pine Creek regional population is geographically isolated, and while it is possible to estimate its proportion of

the global population, its importance in terms of genetic diversity relative to the global population is unknown.

Further to this, the connectedness of the local URPA colony with the Pine Creek regional population is also

unknown, and its importance in terms of genetic diversity and viability is a clear gap in current Ghost bat

literature and understanding.

11.2.3 CHARACTERISTICS OF KNOWN AND LIKELY NATURAL AND ARTIFICIAL ROOSTS IN

THE PROPOSAL AREA

Historical Records

Early gold mining in the Pine Creek area commenced in 1870 and continued until 1915, creating a number of

artificial roosts within the URPA. Recent (post-1990) open cut mining resulted in the development of several

large open-cut pits and tailings deposition areas which are known to have removed a number of historical

workings, including several of those occupied by Ghost bats prior to the 1990s.

159


There are four records of Ghost bats within 10 km of the URPA dating from between 1987 and 1995 in the

Northern Territory Fauna Atlas (DENR 2019). The closest observations, although imprecise, are around 1.8 and

2.2 km south-east of URPA. Ghost bats were first detected on the URPA in 1987 and 1988, when biologists from

the Northern Territory Conservation Commission surveyed roost sites in the Union Reefs and Lady Alice adits.

Following this, exploration activities in the 1990s included adits being blocked to exclude the bats.

Adits in the URPA have been occupied at least since their discovery in October 1987, with periods where

disturbance and mining resulted in declines in their numbers, and shifts to alternative roost locations. A colony

utilising the Kohinoor adit in Pine Creek have been present since its discovery in the late 1950s, a period of

approximately 60 years of constant occupancy. The longevity of other regional roosts is not well known, however

these sites are likely to have been occupied by Ghost bats over extended periods.

The continued occupation of sites within the URPA and Pine Creek region, across periods of anthropogenic

disturbance, is indicative of the high level of importance of these roosts in the landscape. The high level of

sensitivity of ghost bats to disturbance (Appendix G) suggests that if alternative suitable sites were available,

stronghold roosts at Pine Creek and Union Reefs would very likely be abandoned, with individuals moving to less

disturbed sites.

Figure 11-1 illustrates the location of Ghost bat records in the Pine Creek region.

Figure 11-1 Pine Creek Region

Ghost Bat Records Mapping data source: GEOScience

Australia/ALA/NT Fauna Atlas 2019

Datum: Map Grid of Australia 94

Zone 52/GDA94 UTM

Original mapping layer data

Copyright EMS Pty Ltd 2019

[email protected]

Client: KLG

Project: UR Ghost Bat EIS Date: 20 Sept 2019

Author: PB

Map Area

Legend

� Ghost Bat NT Fauna Atlas Post-2000

• Ghost Bat NT Fauna Atlas Pre-2000

♦ Union Reefs GB Records 2018 - 2019

c, Ghost Bat Records ALA

roads

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161


Current Records

In 2018, a survey of old mine workings in the immediate vicinity of the URPA was conducted by Armstrong and

Barden (Appendix G), with additional monitoring in 2019 conducted by Barden and Hanrahan. This survey

involved detailed examinations of known and previously documented historic mine locations. Figure 11-2

describes the location of URPA Ghost bat survey records.

The survey identified three adits, one shaft and two parts of a mostly-filled stope, all potential roosts with the

potential to extend further than was visible from the entrance (Figure 11-2). These are characterised in Table

11-1 below.

TABLE 11-1 ADITS WITHIN THE URPA POTENTIALLY PROVIDING ROOSTING HABITAT

Adit Name

(Adit Location)

Est Depth

from

Entrance (m)

Entrance

Width x

Height (m)

Ghost Bat

Number

Min - Max

Comments on Ghost Bat Use

and Habitat Suitability

Union North adit

(Union North pit) 62 1 x 1.5 20 - 30

Internal structures unknown—will be further

inspected during Phase 1 of the project.

Used by 20 to 30 Ghost bats as a diurnal roost

on a regular basis across the wet and dry

season.

Bats tend to move to the OK adit periodically

during the wet season and use the Union

North adit in the dry season.

OK adit

(Prospect pit) 18 1.5 x 1.2 20 - 30

Internal structure determined using pipe

inspection camera and internal investigation

by KLG staff.

The end of the southern drive is used by 20 to

30 Ghost bats as a diurnal roost during the

wet season. These bats switch to the Union

North Adit in the dry season.

Prospect adit

(Prospect pit) 8 0.4 x 0.4 1 - 1

Short remnant of a formerly larger adit, with

only a small opening allowing access for bats.

Thought to have been exposed by rock fall

during 2018.

Used only by individual bats as a nocturnal

feeding site and occasionally as a diurnal

roost in 2019.

Lady Alice adit

(East of Union

North pit)

30 0.4 x 0.2 0 - 0

Ghost bats not detected in the internal

structure. The entrance has been blocked

except for a narrow opening. The internal

structure remains open and intersects a shaft

that exits to the surface approximately 30 m

to the east.

Re‐opening and modifying the structure is

Action 4 in the Action Plan (Armstrong et al.

2019b).

162


The Union North adit, OK adit and Prospect adit were confirmed as being occupied by Ghost bats. These adits

exist as open portals in the side walls of mine pits and are the remnants of larger structures that were mostly

removed during excavation of the pits. Since the discovery of Ghost bats at these sites in mid-2018, they have

been subjected to monitoring using permanent 24-hour acoustic recorders and periodic fly-out counts using

thermal/infrared cameras. This monitoring effort is ongoing and encompasses the majority of two Ghost bat

breeding seasons.

The data collected to date has identified a colony of approximately 20 to 30 individuals that use both the OK adit

and Union North adit as diurnal roost sites. Roosting has been detected in the Union North adit for most of the

dry season, as well as brief visits during August to November. Roosting has been detected in the OK adit most

commonly throughout the wet season as well as brief visits during July and October.

Prospect adit, discovered in the Prospect pit and thought to have been exposed during a recent rock fall, was

found to be used as a nocturnal feeding site/nocturnal refuge and occasional day-time/diurnal roost for what is

likely to be only individual Ghost bats.

The Lady Alice adit is currently almost completely blocked by fallen debris and rubble and Ghost bats have not

been detected using this site, however this location has been identified as a potential site that could be re-

opened to create additional Ghost bat roost habitat within the project area at a later date (refer Section 11.4).

The internal microclimate of this Lady Alice adit is likely to be suitable for this species, as orange diamond-faced

bats have been observed roosting at this location and are known to have similar habitat requirements.

A full description of the survey, monitoring program and roost characteristics are provided in Chapter 3 of

Appendix G.

Seasonal and Transitory use of Roosts

Monitoring indicates that Ghost bats switch between adits within the URPA as well roosting outside the URPA

periodically. There are currently no observations that support a clear explanation for the patterns of movement

of Ghost bats between the adits.

Monitoring indicates that the OK adit is used as a diurnal roost by Ghost bats predominantly throughout the wet

season. Its shallow depth is sufficient to maintain a suitable warm and humid roosting microclimate during the

warmer months. Despite this, the adit is still used as a nocturnal and diurnal refuge during the dry season.

The Union North adit is much deeper than the OK adit and is used as a diurnal roost by Ghost bats. The

continued presence of orange diamond-faced bats (Rhinonicteris aurantia) across the wet and dry season at the

Union North adit suggests that microclimate conditions in this adit would also be suitable for the Ghost bat

across the range of seasonal conditions.

The Prospect adit, by comparison, has a much lower level of activity than the other two locations. This site

appears to be used occasionally as a diurnal roost for a small number of individuals and as a nocturnal refuge and

feeding perch at other times. The Prospect adit is not thought to provide valuable diurnal/day time roosting

habitat due to its small entrance and shallow depth making it unsuitable to Ghost bat climactic requirements.

There was less than 10 calls per night at both Union North and OK adits combined from March to May 2019,

suggesting the URPA colony of an estimated 20 to 30 individuals utilised a diurnal roost outside of the URPA

during this time and returned from July 2019. This provides indirect evidence that the Ghost bats are moving in

and out of the URPA. Two major roosts adjacent to Union Reefs are around 10 km north (Spring Hill) and 13 km

south (Kohinoor, Pine Creek) (see Figure 11-2) and are potentially within the nightly Ghost bat foraging range.

There are likely to be numerous transitory roosts in the intervening area, including shallow mine workings,

culverts and small cave features in boulder piles and plateau margins. These transitory roosts may allow the

movement of individuals among the major known colonies (Figure 11-2).

Figure 11-2Union Reefs Project

Area AditsMapping data source: GEOScience

Australia/ALA/NT Fauna Atlas 2019

Datum: Map Grid of Australia 94 Zone

52/GDA94 UTM

Original mapping layer data Copyright

EMS Pty Ltd 2019

[email protected]

Client: KLG

Project: UR Ghost Bat EIS

Date: 20 Sept 2019

Author: PB

Legend

o Ghost Bat Records NT Fauna Atlas

• Adit (Historical)

0 Proposed Porta I

• Heritage Mining Sites (Checked)

roads

f--+-+ railways

Mineral Titles Granted

D Union Reefs Operations

N

0 500 1000 1500 m

t ECOLOGICAL MANAGEMENT SERVTCES

1 0000.0

8485 00.000

84840 0.000

• 8482000. 000

8481000.000

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164


11.3 Potential Impacts and Risks

The activities throughout mine development and operation, which could directly impact the URPA Ghost bat

colony include the following:

Noise from site setup and construction of new surface infrastructure required to support the proposed

underground mine operation.

Noise from mining operations including drilling and underground blasting.

Vibration from mining operations including drilling and underground blasting.

Damage to roost sites including internal blockages and collapse.

Temporary (estimated two years) closure of the OK adit and Prospect adit during mine development and

operations.

Introduction or increase in people to an area.

Changes to existing water resources such as dewatering of groundwater or pollutants from wastewater.

11.3.1 RISK ASSESSMENT SUMMARY An assessment of the risk associated with the project is detailed in Chapter 10. Of the 15 potential events

identified that have the potential to impact on the Ghost bats, there were no residual risk ratings of high, six

rated at medium and the remaining nine events rated as having low residual risk. A summary of the risk

assessment results is provided in Table 12-1.

TABLE 11-2 RISK ASSESSMENT – TERRESTRIAL FLORA AND FAUNA

Potential Event Residual

Risk Level

Vibration emissions from mining activities result in disturbance of /or damage to roost sites for

individual bats or a small population of bats in OK and Prospect adits. Medium

Temporary closure of OK adit during mine development and mine operations. Medium

Union North adit is flooded during the wet season. Medium

Damage to the structure of Union North adit - entrance blockage or internal collapse associated

with mining or not. Medium

Malevolent actions at a roost that cause disturbance and/or mortality of bats, in particular

Kohinoor adit at Pine Creek that is easily accessible to the public. Medium

Collapse or blockage of historical adit from random deterioration (Pine Creek, Spring Hill). Medium

A disturbance to a roost site, including OK adit, at a critical part of the breeding cycle that causes

an interruption to breeding activity and lowered reproductive output. Low

Coincident, uncoordinated and non-prioritised research resulting in unnecessarily elevated levels

of disturbance through duplication of effort. Low

Vibration emissions from mining activities result in disturbance of individual bats or a small

population of bats in Union north adit and other modelled locations. Low

Ground borne noise emissions from mining activities result in disturbance of individual bats or

the colony of bats in the URPA. Low

Field surveys in the hills surrounding Union Reefs reveal no alternative natural roosts. Low

Bats disperse to suboptimal roosts, rather than Union North adit or larger stronghold roosts,

after the OK adit is closed. Low

Dewatering for the mine reduces levels of groundwater that keep roosts humid for Ghost bats. Low

Young bats in the later stages of development perish after being abandoned in roosts by adults

moving out of the Union Reefs area in response to a disturbance or closure of the OK adit. Low

Waste-water in open pit mine voids contains pollutants that might reduce rates of survival in

Ghost bats. Low

165


Events listed above found to have residual risk ratings of medium or higher are discussed in detail in Section 11.3.

11.3.2 NOISE AND VIBRATION

A noise and vibration assessment (refer to Appendix 1 of Appendix G) estimated the potential noise impact

resulting from the project and the magnitude of vibration surrounding blast points planned in the underground

mine below the Prospect pit. The impact to seven locations where the Ghost bat had been recorded in the URPA

were considered in this assessment (Appendix G).

Vibration

Previous studies have suggested that vibration levels within 10 mm/sec does not cause a significant disturbance

to this species (Appendix G). The magnitude of vibrations from blasting was estimated at:

29.6 millimetres per second (mm/sec) and 54.6 mm/sec for the OK adit (minimum distance 33 metres)

15.7 mm/sec and 28.9 mm/sec for the Prospect adit (minimum distance 51 metres).

The remaining locations (outside 51 meters) all had values between 0.1 and 2.5 mm/sec. These results

demonstrate that:

The OK adit and Prospect adit are likely to experience relatively significant levels of vibration during the

many planned blasts. The potential impact from disturbance through significant levels of vibration could

be have similar consequences to the exodus response resulting from the loss of a roost, as described in

Section 11.3.3.

Potential high vibration levels in the OK adit and Prospect adit provide justification for a plan to exclude

Ghost bats from these adits during mine operations

The other locations, in particular the Union North adit appear to be outside the high vibration area, and

were modelled to receive low levels of vibration at 1.2 and 2.3 mm/sec.

Noise

Noise levels produced by blasting are not expected to present a significant negative effect on the Ghost bat. This

is because the blasting will take place underground, so noise will be ground-borne, i.e. re-radiated from the

ground into the airspace of a tunnel. Levels were modelled to be low (75 dBZ at OK adit; 62 dBZ at Union North),

roughly equivalent to human conversation at 1 to 2 metres.

Noise will also be at the lower frequency limit of hearing of the species, if they will detect it all, with the majority

of noise energy between 1 Hz to 50 Hz. There is limited empirical assessment of a disturbance threshold for bats

relating to blasting, however current opinion notes that noise levels from blasting are of significantly shorter

duration than drilling, which might take 12 hours or more. Whether bats become habituated to short, relatively

minor, low frequency noises associated with periodic underground blasts is unknown, but studies in the Pilbara

have shown that longer duration sounds from nearby drilling did not cause daytime roost exodus in bats

(Appendix G).

11.3.3 TEMPORARY EXCLUSION TO ROOSTS AND ALTERNATIVE ROOSTS

Temporary Exclusion to Roosts

The Ghost bat has a physiological requirement for roosts with warm, humid microclimates. Only a small

proportion of caves in the Australian landscape typically provide these conditions. Temporary closure of

approximately two years is proposed during underground mine operations. This includes the closure of OK adit,

which is considered to provide seasonally optimal microclimate conditions, and the Prospect adit which is a

recently occurring adit found to be used as a nocturnal feeding site and occasional diurnal roost by only

individual Ghost bats.

The temporary closures will have the following consequences:

Temporary removal of one of two main Ghost bat diurnal roost sites in the URPA (i.e. OK adit) and loss

of additional capacity in the event that Union North roost becomes unsuitable or is disturbed.

166


Temporary removal of a refuge adit (i.e. Prospect adit), which appears to be a relatively shallow

structure (18 metres maximum tunnel depth, with one shorter crosscut), and which are more common

than deeper structures.

Any exodus response due to the proposed exclusion from the OK adit might or might not provide an impetus for

the movement of individuals, with predicted connections to unknown natural cave sites in the surrounding hills,

and the major colonies located up to 15 km away at both Pine Creek and Spring Hill. This could produce one of

two scenarios:

1 Ghost bats relocating to either a known roost with an optimal or acceptable microclimate (given

seasonal changes); or

2 Ghost bats relocating to a ‘random’ cave that is too shallow to provide a suitable microclimate. In the

latter case, bats would need to move again until they find a suitable roost.

The closure will be timed for when Ghost bats are congregated in the Union North adit (most likely the months of

June, August, October, November), or when numbers have previously been observed to be low in the OK adit

(March to August). Consideration will also be given to avoid significant disruption during months of high mating

activity and when females are giving birth and raising young, which is thought to be in May/June and from

August to January respectively.

Based on the observations derived from the 2018 to 2019 monitoring program within the URPA, the most likely

scenario following the closure of OK adit is that most individual bats will remain in the Union North adit. It is

predicted that some will move elsewhere, either into natural caves surrounding the project area if they exist, or

into the larger colonies at Pine Creek and Spring Hill. Two assumptions have been created to arrive at this

scenario:

1 At least one natural cave in the hills surrounding the Union Reefs project area provides a suitable

microclimate for Ghost bat roosting, and at times relevant to the closure of the OK adit.

2 There are regular movements within the region, amongst the Pine Creek, Spring Hill and Union Reefs

colonies and surrounding caves.

Ongoing monitoring will provide a validation for the above scenarios. Additional understanding of Ghost bat

movement and interaction will be provided by proactive management solutions, including:

Field surveys for Ghost bat diurnal roosts in caves in the hills surrounding the Union Reefs project area.

A genetic study that will provide evidence on the extent of interconnectivity of individuals between Pine

Creek, Spring Hill and URPA colonies.

In addition, further capacity in the form of new artificial habitats will be established in other areas of the URPA,

sited away from mining-related activity, and designed via computational thermal modelling to provide a suitable

microclimate for roosting. The design phase of this artificial roost project component commenced in October

2019 (refer Section 11.4).

The worst case scenario is where bats excluded from using the OK adit respond by moving to shallow natural

overhangs, mining infrastructure or trees, where they would be exposed to predators, further mining-related

disturbance, and/or profoundly unsuitable environmental conditions for survival. This worst case scenario is

considered less likely than the scenario in which the colony remains in the URPA at the Union North adit, given

the timeline selected for the exclusion and the addition of other mitigation measures outlined in Section 11.4.

The impact of the proposed temporary closure of the OK adit is therefore considered to be insignificant at the

level of individual, colony and population for the following reasons:

Individual: Each Ghost bat is unlikely to find itself without an alternative optimal roost, and females

with young will not be reliant on the OK adit, at the time the entrance closure is undertaken. This is

relevant in both the short and long term. Alternative optimal roosts include: Union North adit, as well as

the Kohinoor adit at Pine Creek, Spring Hill stopes (to be confirmed by genetic analysis), plus a modified

Lady Alice adit and several artificial roosts with the URPA (assuming the modelled microclimates are

suitable).

167


Colony: The colony currently has more than one roosting option in the URPA (as described for

individuals), and the colony appears to change in size because of the movement of individuals in and out

of the project area (e.g. there were typically less than 10 calls per night at both adits combined in March

to May 2019; colony size has been counted at up to 30 individuals throughout monitoring since October

2018; Appendix G). The temporary blockage of a relatively shallow roost (the OK adit) is predicted to be

insignificant given access to known and predicted alternatives of greater depth.

Regional Population: Given the indirect evidence that Ghost bats can readily move in and out of the

URPA to sites known and possibly unknown, the impact of the closure of the OK adit is unlikely to be

significant for the regional population. If the Union North adit can be maintained as a protected roost

site, and if other planned additional sites are indeed provided, then the URPA will likely remain an

important stepping-stone between Pine Creek, Spring Hill and any other sites used by Ghost bats in the

region.

Alternate Roost Sites

Alternative roost sites and measures that will be carried out to improve their suitability during the temporary

closure of OK adit could include:

Union North Adit

Lady Alice Adit

Kohinoor Adit, Pine Creek

Spring Hill

Union North Adit

This site appears to be optimal for roosting based on monitoring of activity levels since October 2018. The site is

available as a roost all year round and is occupied during the period when Ghost bat young are being born

(relatively high activity in July to August 2019) and during development in the weeks afterwards (activity in

October to November 2018).

The numbers of other cave-roosting bats in the Union North adit (orange diamond-faced bat [Rhinonicteris

aurantia]; common sheath-tailed bat [Taphozous georgianus]; Finlayson’s cave bat [Vespadelus finlaysoni]) are

likely to be greater than in the OK adit, based on compiled activity data of R.aurantia and the greater depth and

larger area available in the Union North adit.

While only superficial inspections of the interior have been carried out to date, the Union North adit appears

structurally stable. There is some evidence that the rear of the adit is subject to some level of flooding during

heavy rain, however, there is no indication that this adit will become less suitable as a Ghost bat roost. The effect

of dewatering of the Prospect pit is not expected to extend to the Union North pit, and thus the amount of

groundwater available to keep the microclimates humid into the Union North adit and Lady Alice adit is unlikely

to change. An inspection of the interior of the adit (Action 2, Section 11.4) will provide information on the extent

of likely flooding. If modelling detects that water incursion would result in sub-optimal roost humidity conditions,

and if monitoring detects that Ghost bats are discontinuing use of the adit, the potential for pumping water out

of the adit will be investigated.

Lady Alice Adit

This small adit around 150 metres east of the Union North entrance portal (see Figure 11-2) appears to be a

straight horizontal tunnel of unknown length, but probably around 30 metres. The entrance portal is partially

obstructed by earth, with the aperture only accessible to species such as the orange diamond-faced bat,

recorded in 2018. There is also a shaft entrance further up the slope that connects to the horizontal adit. Ghost

bat calls were recorded at the entrance of the adit well after dusk, indicating nocturnal visitation, but the

structure is currently unsuitable for roosting Ghost bats.

To increase suitability as an alternative diurnal roost, it is proposed to remove some of the material obstructing

the entrance to allow Ghost bat entry, and seal the shaft entrance to increase the humidity inside. Given that

Ghost bats are already aware of the Lady Alice adit, and vibration and noise modelling predicts a similar level of

minimal disturbance as with the Union North adit, this could provide a good alternative to the OK adit. It will be

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included in any long-term monitoring effort. Any augmentation of the Lady Alice adit is likely to maintain

accessibility to other bat species.

Kohinoor Adit, Pine Creek

This site supports a large colony of Ghost bats, and has done so for many years despite continued disturbance in

the local area, including mining exploration, road construction, vehicle movements and frequent intrusion by

people. The high importance of this site to the regional population may be due to the lack of other roost sites

nearby that provide suitable habitat quality, rather than their tolerance of disturbance. Colonies at Union Reefs

and Spring Hill might be a response to previous disturbances at Pine Creek.

The Kohinoor adit has the capacity to support up to, and possibly exceeding, 1,500 individual Ghost bats. In the

context of up to 30 individuals from Union Reefs relocating themselves to Pine Creek, this would represent less

than 4 % of the current maximum estimated colony size of 800 individuals based on recent counts.

Measures to manage the Kohinoor adit in future could include managing human disturbance of the site and

promoting community and traditional owner involvement in conservation and management of the site (See

Action 6, Section 11.4).

Spring Hill

A study in 2017 by Northern Resource Consultants (2018) recorded 96 Ghost bats emerging from ‘stope 13’, and

a total of seven individuals from two other stopes, giving a total colony size of approximately 100 individuals.

However, evidence of tampering prior to the survey was found, suspected to have caused the relocation of Ghost

bats to other stopes. Further details on whether these could support Ghost bats in the future is unavailable.

If the location of the main structure containing Ghost bats at Spring Hill does not coincide with plans for further

mining, and management at that site is appropriate for their long term persistence, then Spring Hill might remain

an important site for the Ghost bats. This could include those individuals that might relocate from other sites

such as within the URPA and Pine Creek.

11.3.4 DISTURBANCE TO ROOSTS

Damage to Roost Sites – Internal Blockages and Collapse

Damage to the structure of an adit used by the Ghost bat could occur through internal collapse or entrance

blockage from natural deterioration or instability caused by mine operations. This could result in direct mortality

of bats being trapped or crushed, or indirect mortality though the loss of a roost or the decline in roost value,

which is especially detrimental during key seasons, when other roosts are not suitable.

Damage to the Union North adit is the most relevant to consider, because this site will likely constitute the

preferred alternative diurnal roost for the URPA colony following the closure of the OK adit. The risk of such

damage occurring is unknown because the internal structure has not yet been surveyed. However, from an

inspection of the entrance, the adit appears stable, and the pit walls above the entrance portal do not show signs

of instability that indicate the possibility of a minor ‘landslide’ that would cover it.

Any exodus response to mining-related activity at the Union North adit has the potential to produce one of two

scenarios:

Ghost bats relocating to either a known roost with an optimal or acceptable microclimate (given

seasonal changes); or

Ghost bats relocating to a ‘random’ cave that is too shallow to provide a suitable microclimate. In the

latter case, bats would need to move again until they find a suitable roost.

Mortality of individual Ghost bats from mining activities is considered low due to the low likelihood for self-

relocation to a suboptimal roost, and for the following reasons:

The proposed exclusion of the Ghost bat colony from the OK adit will be undertaken in the least invasive

way possible. A key tactic is to stage the exclusion of bats from the OK adit in a time period when bats

have shifted their occupancy to the Union North adit, and when there is no roosting activity at the OK

adit.

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The close proximity of the Union North adit means that at least one alternative roost is nearby if

individuals are searching for a diurnal roost close to dawn.

The risk of exodus and relocation from the Union North adit due to elevated noise and vibration levels

from blasting is considered unlikely (refer Section 11.3.2).

The two largest colonies at Pine Creek and Spring Hill are both within 15 km from the Union Reefs adits,

and the URPA colony is likely to be able to fly this distance in a single night. This suggests that the URPA

colony could relocate away from the URPA should the alternative adits be unsuitable.

Mitigation measures and monitoring of bat activity (refer Section 11.4) will be implemented to minimise

the risk of elevated mortality from relocation to suboptimal roosts.

Disturbance from People

The proposed additional and expanded mining operations in close proximity to roost sites may introduce human

activity to an area not previously affected by inadvertent or malevolent human activity. The addition of new

infrastructure, such as roads, can cause an increase in future human activity, continuing post closure.

Ghost bats are especially vulnerable when occupying a diurnal roost. When disturbed by day time entry of

people, their response is typically to exit the roost and fly into daylight where they are exposed to predatory

birds and unsuitable ambient conditions. A significant increase in the likelihood of mortality is expected in such a

case. Other impacts caused by human disturbance to diurnal roosts include:

Cause night-time relocation to an alternate roost site, an issue when there are few suitable nearby

roosts.

Disrupt breeding activity and reduce fecundity.

Existing disturbance from people is suspected to occur at Spring Hill and Pine Creek. This is a potential new risk at

the URPA, particularly through uncoordinated and non-prioritised research (refer Section 11.5). This could result

in unnecessarily elevated levels of disturbance to adits through duplication of effort.

Changes to the Humidity of Roosts

The project involves dewatering of Prospect pit, which could result in localised changes to the existing

groundwater and flooding regime within the URPA, and within adits utilised by Ghost bats. The types of

subterranean structures that support the larger colonies of Ghost bats and act as breeding sites are generally

deep, with warm, humid microclimates and changes to these conditions, through the removal of groundwater,

could reduce the suitability of roosts.

While only superficial inspections of the interior of adits within the URPA have been carried out to date, there is

evidence that the rear of the Union North adit is subject to some level of flooding during heavy rain. The effect of

dewatering to the Prospect pit is not expected to extend to the Union North pit, and thus the amount of

groundwater available to the Union North adit and Lady Alice adit to keep microclimates humid is considered

unlikely to change. An inspection of the interior of the Union North adit will confirm this, and provide further

information on the extent of flooding.

If changes to the water regime are found to result in suboptimal roost conditions, and if monitoring detects

Ghost bats are no longer utilising the adit, then the potential for pumping water out of the adit will be

investigated. This would investigate the benefits of reducing water ingress verses potential disturbance caused

by the process (refer Section 11.4). Conversely, temperature and relative humidity dataloggers will be installed in

Union North adit and Lady Alice adit, if possible. If the dataloggers show the roost to be drying out, actions such

as the manual introduction of water could be implemented, to maintain optimal humidity levels.

Pollution from waste water in mine voids are considered to be a low risk. This is due to the existing presence of

flooding from historical mine workings in the URPA and that Ghost bats are unlikely to come into direct contact

with water in mine voids because they are not known to drink free water from pools.

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11.3.5 COMMONWEALTH MATTERS OF NATIONAL ENVIRONMENTAL SIGNIFICANCE

(MNES)

An action is likely to have a significant impact on a vulnerable species if there is a likelihood or possibility of a

series of consequences, as set out in the Commonwealth Matters of National Environmental Significance (MNES)

Significant impact guidelines 1.1 (Commonwealth of Australia, 2013). These EBPC Act 1999 significant impact

criteria are summarised in Table 11-3 in relation to the project. A full description of project outcomes is provided

in Chapter 7 of Appendix G.

TABLE 11-3 MNES SIGNIFICANT IMPACT CRITERIA

Significant Impact Criteria Project Outcomes

Actions that may lead to a

long-term decrease in the size

of an important population of

a species.

The project requires temporary closure of two seasonal (wet season) roosts

(OK adit and Prospect) during operations to mitigate impacts from noise and

vibration, including potential adit collapse. These measures are not expected

to result in the long term decrease in the numbers of Ghost bats at the URPA

for the following reasons:

The project does not include loss of significant areas of foraging

habitat for Ghost bats in the local area (estimated clearing for the

project is 1 ha of regrowth vegetation).

There are alternative roosts in close proximity within the URPA, as

well as outside the URPA within nightly flying distance.

The Prospect adit is only used as a nocturnal feeding site and

occasional day-time roost for a small number of Ghost bats. The

implementation of the eleven Actions outlined in Table 11-4.

Actions that may reduce the

Area Of Occupancy of an

important population.

The proposal will not alter the Ghost bat area of occupancy, as there is no

requirement to exclude the bats from the Union North adit (located 650 m

north of Prospect adit) and would only require the temporary exclusion from

two wet season seasonal roosts as a measure to minimise day time

disturbance at these locations from mining activities.

Additionally the area of occupancy will be increased with the use of

mitigations measures including reopening lady Alice adit, and developing

additional artificial roosts prior to the mine development

Actions that may fragment an

existing population into two

or more populations.

The proposal does not require the removal of the local population or all roost

sites in the URPA. It is therefore unlikely to have a fragmentary effect on the

existing population in the local or regional area. The whole population of 20-

30 individuals could alternatively roost at the Union North adit.

Actions that may adversely

affect habitat critical to the

survival of a species.

The two roosts proposed for temporary closure (OK adit and Prospect adit)

are mainly used as wet season diurnal roosts. These sites cannot be

considered necessary to the survival of Ghost bats in the URPA, as there is an

alternative roost nearby that is used on a regular basis (Union North adit).

Also, offsets will be provided through opening and renovating an alternative

dry season roost (Lady Alice adit) and by providing new artificial roosts.

Actions that may disrupt the

breeding cycle of an

important population.

If breeding is occurring at the site, it is more likely to be associated with the

deeper Union North adit. Larger colonies with breeding activity tend to be in

deep caves or adits with relatively warm and humid microclimates.

Monitoring suggests that visitation of Union North adit during the season

when females are likely to be giving birth and raising young is higher than in

the OK adit.

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Significant Impact Criteria Project Outcomes

Actions that may modify,

destroy, remove or isolate or

decrease the availability or

quality of habitat to the

extent that the species is

likely to decline.

The temporary closure of OK adit, a seasonally-used roost is to avoid impacts

to the Ghost bat (including increased possibility of mortality from day time

exodus due to underground mining activities). The closure of Prospect adit,

an occasional nocturnal refuge for a small number of individuals, is unlikely

to impact these individuals as there are numerous alternative nocturnal

refuges in close proximity. These closures will be offset through opening and

renovating an alternative dry season roost (Lady Alice adit) and by providing

new artificial roosts.

Actions that may result in

invasive species that are

harmful to a vulnerable

species becoming established

in the vulnerable species’

habitat.

The project will not lead to the introduction or establishment of invasive

species in the habitat of the Ghost bat.

Actions that may introduce

disease that may cause the

species to decline.

The project and associated actions are unlikely to involve introduction of

diseases.

Actions that may interfere

substantially with the

recovery of the species.

None of the project activities are expected to interfere substantially with the

recovery of the Ghost bat.

11.4 Mitigation and Management Mitigation Strategy

The strategy for managing and mitigating potential impacts to the Ghost bat colony in the URPA is summarised

below and described in full in the Ghost bat action plan provided in Appendix G. The overall strategy involves:

1 Minimising the effect of the construction and operation of the project, by providing new opportunities

for roosting through additional capacity within the project area.

2 Supporting predictions and assumptions around Ghost bat distribution and movements on an URPA and

regional scale through long term monitoring of known roost sites and the identification of unknown

roost sites.

11 actions are proposed, which are expected to deliver a net improvement to the security of the Ghost bat

population in the region. Chapter 5 of Appendix G provides further detail on the consequences, risks, costs and

benefits, short, medium and long-term advantages and disadvantages of the mitigation measures proposed. The

eleven Actions are presented in Table 11-4, which outlines the effectiveness and threat factor of each action,

with reference to the project phase in which it is conducted. Project phases are as follows:

Phase 1: Before new underground mine construction.

Phase 2: Exclusion phase, immediately prior to site works in the Prospect pit.

Phase 3: During mining.

Phase 4: After mining has been completed.

An alternative to these actions would include the physical relocation of bats from the OK adit. This would require

capture and handling and potentially tagging of Ghost bats or regular intrusions into a roost, which could result

in greater disturbance to a colony and invasive procedures to an individual bat. Therefore, all actions proposed

are considered minimally invasive and provide the information necessary to confirm predictions about how

Ghost bats move in the region.

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TABLE 11-4 MITIGATION AND MANAGEMENT ACTIONS

Action Timing Threat Factor and Effectiveness

Action 1 - OK Adit

Exclusion

Exclude the Ghost bat

from the OK adit based on

a planned methodology

and timing. [Avoidance

and mitigation/

minimisation].


Effectiveness: Closure of the adit will be fully effective for diverting

Ghost bat usage of the OK adit to the Union North adit and other

alternatives. This avoids the significant impacts of ongoing daytime

disturbances at the OK adit including vibration and noise causing day

time exodus.

Baseline monitoring has established that Ghost bats already regularly

use the Union North adit, and there is evidence they move in and out

of URPA.

Action 2 - Survey of

Internal Adit Structures

Characterise the internal

dimensions of the OK adit

and Union North adit, and

the position of Ghost bat

roost areas within.

[Research to support

minimisation].


Effectiveness: The Union North adit and Lady Alice adit will be

surveyed at night by trained and experienced personnel with

appropriate equipment. The aim is to determine depth and extent,

stability, the presence of crosscuts/stopes/shafts/etc. and the position

of guano piles indicating roost position.

Action 3 - Construct

Artificial Habitats

Create several artificial

roosting habitats in the

URPA, for both

contingencies and

additional capacity, and

evaluate their success.

[Both mitigation/

minimisation and offset].


Effectiveness: The creation of artificial habitat for the Ghost bat in

Australia, as well as species such as the orange diamond-faced bat, is

experimental, and therefore the effectiveness is still unknown.

The design is to provide several alternative horizontal tunnel habitats,

not only to replace the OK adit, but to provide further capacity via

multiple new roosting options within the URPA. The design will

include:

1 Dimensions likely to provide conditions suitable for Ghost bat

roosting based on extensive experience of other roost sites.

2 Confirmation of the suitability of the microclimate that will

form within through modelling with computational fluid

dynamics.

Action 4 - Re-open Lady

Alice Adit

Re-open and rehabilitate

the Lady Alice adit so that

it is suitable for Ghost bat

occupancy. [Mitigation/

minimisation and offset].


Effectiveness: The Ghost bat, and other cave-dwelling bat species

readily move into underground mines following the cessation of

mining, though over what timescale is unknown. Lady Alice adit will

be opened and modified (block an open shaft that intersects the adit

midway) to ensure that it retains a suitable warm, humid

microclimate. This modification is anticipated to attract bats to roost

within when access to the OK adit is removed.

The species has already been recorded near the entrance, current

data indicates it has a similar depth to the OK adit, and the entrance

portal is only around 150 m from that of the Union North adit.

Combined with management that prevents casual visitation by

people, there is confidence that it could become an alternative to the

OK adit relatively quickly.

Action 5 - Manage Union

North Adit


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Manage the Union North

adit during the period of

mining to exclude

visitation from mining

personnel. [Mitigation/

minimisation].

Effectiveness: Managing the Union North adit is a core part of the

strategy to manage the colony of Ghost bats in the Union Reefs area

during the proposed mining period, given that this adit will be the

colony’s closest known suitable diurnal roost. Managing Union North

adit, Lady Alice adit and new artificial roosts will be a priority.

Measures would include protecting roosts from disturbance and

educating staff regarding access and disturbance in the vicinity of

Ghost bat roosts and maintaining structural integrity and accessibility.

Action 6 - Manage Pine

Creek and Spring Hill

Ghost bat sites

Implement management

measures at the

Koohinoor adit, Pine

Creek, to protect the

Ghost bat roost.

[Mitigation/

minimisation].


Effectiveness: The Kohinoor adit is currently protected from human

intrusion by a low stock fence without barbed wire. If ownership of

the Spring Hill mine changes to KLG in the future, protection measures

will be improved. Measures would include discouraging casual entry

by the public, such as signage, diverting attention away from the site

and public education.

Action 7 - Monitoring

Program

Continued monitoring of

Ghost bat presence,

activity levels and colony

size at Union North adit,

potentially Lady Alice adit,

new artificial roost

habitats, and other key

regional sites (Pine Creek;

Spring Hill; any newly

discovered caves of

significance surrounding

the URPA). [Mitigation/

minimisation].

Phase 1

Phase 2

Phase 3

Phase 4

Threat Factor: Disturbance to roost sites, breeding sites.

Effectiveness: Continued monitoring by specialist ecologists to build

on the surveys conducted since August 2018. Monitoring will collect

information on bat presence and usage levels which is critical

information on understanding Ghost bat colony size. Methods will

include:

New video recording technology (e.g. thermal tracking

software) able to make multiple scheduled recordings over

consecutive nights to collect.

Analysis of acoustic datasets.

Conducted by experienced analysts with advanced recording

and analytical systems.

In the event of a collapse affecting the entrance portal, material

blocking the entrance of the Union North adit will be removed.

Subsequently, and if safe for human entry, the effect on Ghost bats

will be evaluated by inspecting the interior for individuals that may

have perished. These will be reported to DENR, and any carcasses

submitted to the MAGNT.

Action 8 – Facilitate Post-

Mining Occupation of

Mine Workings by Ghost

Bats

Provide a portion of the

new mine for Ghost bat

occupancy once mining

has been completed and

evaluate its success.

[Rehabilitation or offset].


Effectiveness: Ghost bats and other cave-dwelling species of bat in

northern Australia are well known for their tendency to occupy

underground mine workings after mining activity has finished. As

indicated by the current use of adits within the URPAs.

At project completion, the new underground structures will be deeper

and more complex than existing adits, and potentially provide suitably

warm and humid microclimates. Part of such a structure will be made

available to Ghost bats following the cessation of mining. This will

provide long term potential for Ghost bat numbers to build up to

eventually become more important for the regional population than

the Kohinoor adit.

This strategy has a very high potential to become one of the most

effective and significant actions.

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Action 9 - Cave and Mine

Roost Survey

Conduct field surveys for

Ghost bat diurnal roosts in

natural caves in the hills

surrounding the URPA.


minimisation].


Effectiveness: Confirmation of occupied natural caves in the

surrounding hills will give reassurance that there are alternative roost

sites very close to sites that might be subject to mining-related

disturbance.

The methods for non-invasive discovery and monitoring of Ghost bats

are effective if applied correctly. Methods described for Action 7 will

be used. These methods do not present a disturbance to Ghost bats

that might roost within a structure, especially if investigators do not

enter and attempt to minimise noise when deploying equipment.

Action 10 - Genetic Study

Investigate the

connectedness of Ghost

bat colonies in the region

using an advanced genetic

method based on

genome-scale DNA

sequencing. [Research to

support minimisation].


Effectiveness: An analysis of physical and genetic connectedness

among colonies in other parts of the region, will be carried out. Ghost

bats will be lured into harp and mist net traps (positioned close to, but

not adjacent to roost sites) by acoustic playbacks, where fresh DNA

will be collected from trapped individuals via ethically approved

methods. These samples will be combined with those available from

previous studies and analysed using a genome scale, DNA sequencing

process called ‘DArTseq’. This will provide information for the

movement and genetic similarity of individuals among colonies within

the region.

Action 11 - Support Ghost

Bat Research

Provide support for

further academic

research. This would

include coordinating the

development of a

Recovery Plan, which is

required under the EPBC

Act 1999, but has not yet

been developed.


overall management].

Phase 3

Threat Factor: Relevant to most threat factors listed in Threatened Species Scientific Committee (2016).

Effectiveness: There is still little understood about the timing of their breeding cycles in different populations, their acoustic ecology and the importance of water bodies for hydration with questions still remaining about the meaning of call types and interpretation in the context of environmental impact assessments.

Providing funding for a postdoctoral research program will add significant knowledge to the public sphere to assess threats and manage future impacts to Ghost bats populations.

11.5 Monitoring and Reporting

11.5.1 MONITORING

Monitoring within the URPA

A monitoring program has been outlined in the actions listed in Table 11-4. The duration of this program will be

matched to the duration of mining in the Prospect pit, plus six months. Monitoring will be coordinated to

minimise unnecessarily elevated levels of disturbance to adits through duplication of effort. A full description of

the monitoring strategy and frequency of recording and reporting is provided in Chapter 6 of Appendix G.

The monitoring program will be focussed mainly at the Union North adit before, during and after the OK adit

entrance exclusion. Concurrent monitoring will be conducted at the two known largest regional colonies (Pine

Creek and Spring Hill) and any natural cave sites functioning as a significant diurnal roost discovered in areas

around the URPA to provide context in terms of any regional population scale effects.

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Monitoring at the OK adit will be continuous up until the exclusion (sealing of the entrance). Monitoring will

occur at the blocked entrance of the OK adit every night for one week after sealing of the entrance.

Ghost bat presence, overall activity and colony size will be assessed through both acoustic and video recordings,

both of which will not present a disturbance to the colony. Activity levels provide information on both presence

of the target species and the relative usage of a roost site. Other species of obligate cave-dwelling bats present

will also be represented in the recordings by their echolocation calls, and their presence/absence will also be

reported.

The best indicator of usage comes from counts of colony size. Autonomous thermal video recorder systems will

be deployed at adit entrances to capture at least the first three hours after sunset when most or all of the Ghost

bat colony emerging for nightly foraging. Ghost bats can be distinguished from other species of bat by their large

size even in thermal recordings.

Monitoring of Regional Sites

The Pine Creek and Spring Hill colonies will also be monitored using acoustic and thermal video recorders,

though on a less regular basis. Monitoring will be carried out for a total of two consecutive nights per fortnight,

for the duration of the program.

The monitoring program at regional sites will provide information on surrounding colonies, to determine

whether activities outside the URPA might be having an effect on how many Ghost bats are detected within the

project area.

Contingency Monitoring

Two sets of separate, independent factors might cause periods of Ghost bat absence at the Union North adit.

These are:

Natural factors (e.g. unforced movement throughout the landscape due to weather events or other

factors).

Mining-related activities (e.g. disturbance from human activity, noise and vibrations or changes to adit

climactic conditions).

Being certain about which of the two has caused a period of absence is simply not possible, unless there is clear

evidence of a major disturbance of the site, or a major change in the form of the underground tunnel structure

(including major flooding). Baseline monitoring based on long‐term acoustic recordings has so far documented

periods of at least 23 days of the absence of Ghost bat calls at Union North adit. Therefore, defining a trigger that

is robust to false positives but sensitive to possible negative effects on Ghost bats is a challenge. The following

structure is suggested:

Trigger Type 1: In the months that have had the highest documented activity of the Ghost bat (October,

January, February), an absence of any calls over more than seven days is to be considered a trigger [will

lead to Action Type 1].

Trigger Type 2: In any other month, an absence of more than 30 days is to be considered a trigger.

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11.6 Statement of Residual Impact

The assessment is based on historic data, surveys conducted in 2018 and 2019 and a risk assessment of potential

impacts. There remains a residual risk of unknown, unpredictable or irreversible impacts.

Closure of the OK adit is a mitigation measure designed to ‘avoid’ ongoing impact on the colony (associated with

day time exodus of the adit), through reducing the proximity of Ghost bats to planned mining operations such as

underground blasting. If the project is to proceed, there is no possible scenario where an avoidance or no impact

pathway could be implemented without temporary closure of this adit.

The proposed mitigation and management measures have reduced residual risk by increasing the possible

number of roost sites within the URPA (modification of the Lady Alice adit; building several artificial roost

structures), and extending proactive management to regional colonies that are predicted to be within the nightly

flight range of Ghost bats in the URPA (Pine Creek, possibly Spring Hill).

For this reason it is considered very unlikely that the closure of the OK adit would lead to the total loss of the

URPA colony, estimated at up to 30 individuals. However, in the event that this was to occur, the region would

have lost less than three per cent of the known regional population (at least 1,100 individuals), and less than 0.3

per cent of the global population (less than 10,000). This total colony loss is unlikely to occur considering the

mitigation and management strategies detailed in Section 11.4, but remains possible in the following events:

Union North adit collapse while the colony is roosting (causing direct mortality).

Disturbance at Union North adit (mining activity or human disturbance) causing day time exodus leading

to mortality.

The residual risk of this occurring is Medium, and the likelihood is rare.

The primary Ghost bat management objective is to maintain the availability, protection and suitability of

underground roost structures in the URPA, to allow Ghost bats to occupy the area permanently as well as to

facilitate movement and dispersal of the regional population between Pine Creek and Spring Hill. These actions,

in addition to opening new adits within the URPA during and post mining and improving the quality of Pine Creek

roosting sites, are expected to provide a net benefit to the regional population by increasing the quantity and

quality of diurnal roosting habitat available to Ghost bats in the long term.

Additionally, it is worth considering that the historical mines in the Union Reefs area and in the region are

greater than 100 years old, and over time natural collapse and infill is likely to exclude ghost bats from these

sites, and potentially kill large numbers of bats if they are trapped by sudden collapses (Appendix G). Should

mining stop, the monitoring and maintenance of historic adits would cease or become less frequent, and these

sites would eventually become unsuitable as roost sites.

There are currently no external (i.e. non‐mining, government) programs designed to monitor or protect historical

mine workings in the Northern Territory. Investment in mining is very likely to bring a net improvement in the

situation of Ghost bats in the Union Reefs area, and the region generally.

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12 HYDROLOGICAL PROCESSES

12.1 Overview

This chapter describes the hydrological and hydrogeological environments at the URPA and surrounds, and

quantifies impacts of the project on the fluvial environment. This chapter, along with Appendix H, seeks to

address the hydrological processes section of the NT EPA (2019) Terms of Reference for the project.

The environmental objectives, as they relate to ground and surface water are to:

Maintain the hydrological regimes of ground and surface water so that environmental values are

protected.

Maintain the quality of ground and surface water so that environmental values including ecological

health, land uses, and the welfare and amenity of people are protected. Note that water quality is

discussed in Chapter 13.

Protect aquatic ecosystems to maintain environmental water requirements and the biological diversity

of flora and fauna and the ecological functions they perform. Note that aquatic ecosystems are

discussed in Chapter 14.

Specifically, Section 2.2.2 of the draft EIS TOR provides ground and surface water information requirements for

assessment. This chapter addresses and describes the potential direct and indirect impacts of the project on

ground and surface water resources. Mitigation measures that will be implemented to minimise impacts are

documented.

A supporting groundwater study is provided as Appendix H (GHD, 2019), including detailed groundwater

modelling.

Other supporting information includes:

Section 4.7 – mine water dams and other water infrastructure

Section 7.5 – existing hydrological environment

Section 8.1 to 8.3 inclusive – operational water balance, flood assessment and water security.

A preliminary geochemical assessment (Appendix F).

Geochemical water quality modelling (Appendix I).


The primary ground and surface water environmental values are discharge via seepage and surface flow to the

McKinlay River and its riparian and aquatic ecosystems (see also Chapter 14, for a detailed characterisation of

aquatic ecosystems). Groundwater also has value for extraction, notably at Pine Creek borefield and the nearest

third-party independent bore, being RN036105 (licenced to Territory Iron).

The groundwater study (Appendix H) characterises the current hydrogeological and hydrological regimes of the

URPA and receiving waterways, with maps and/or schematic diagrams of flow directions and long term

monitoring data used to describe the following:

Groundwater aquifers (Figure 19, Figure 20, Figure 21, Figure 22, and Figure 23 of Appendix H) and

hydrological properties (Table 4, Table 5 and Table 8 of Appendix H).

Depth to aquifers (Table 2 and Table 3 of Appendix H), including temporal variation (Table 2, Table 3 and

Appendix B of Appendix H).

Groundwater contours (Figure 25 of Appendix H) and flow direction (i.e. Figure 18 and Figure 25 of

Appendix H), volumes (Table 12 of Appendix H) and yields (Table 4 of Appendix H).

Hydrological connectivity is assumed between groundwater aquifers and existing pits, ponds and dams

(Section 2.3 of Appendix H). This is because historical workings have mined below the water table and

existing pits, dams and ponds are highly likely to be unlined and are in direct hydrological connection

with the underlying/intersecting fractured rock aquifer.

178


Hydrological connectivity is assumed between the Pine Creek bore field (town water supply) and the

Union Reefs area and zone of influence (Figure 29, Figure 30 and Figure 31 of Appendix H), however due

to the distances involved, material properties and different catchments, there is unlikely to be any

interaction (Appendix E of Appendix H).

Surface connections via likely discharge locations, notably the McKinlay River and specifically at

MRWET12 and MRWET13 (Figure 3 of Appendix H) or recharge zones, notably existing open pits (Table 1

and Figure 10 of Appendix H).

Beneficial uses (Section 2.1 and Appendix A), specifically groundwater extraction, notably at Pine Creek

borefield and nearest bore RN036105 (Figure 15 of Appendix H).

The regional groundwater study area is mostly bounded by no flow granite boundaries (Figure 12-1). Regional

conceptual hydrogeological models are presented as Figure 12-2 and Figure 12-3. The groundwater system is

within a fractured rock aquifer with relatively low yields. Despite these relatively low yields, the Pine Creek town

water supply has demonstrated the capability of the aquifer to act as a groundwater supply.

Local head dependent flow conditions are presented under current conditions (Figure 12-4) and for comparison,

under a “High Pit Lake Scenario” which is considered an unlikely outcome of the project (Figure 12-5). Surface

water drainage is presented in Figure 12-6.

D isc

harge

B oundary

No Flow Boundary

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LEGEND

0 1 2 3 40.5

KilometersMap Projection: Transverse Mercator

Horizontal Datum: GDA 1994Grid: GDA 1994 MGA Zone 52 o

© 2019. Whilst every care has been taken to prepare this map, GHD (and DATA CUSTODIAN) make no representations or warranties about its accuracy, reliability, completeness or suitability for any particular purpose and cannot accept liability and responsibility of any kind (whether in contract, tort or otherwise) for any expenses, losses, damages and/or costs (including indirect or consequential damage) which are or may be incurred by any party as a result of the map being inaccurate, incomplete or unsuitable in any way and for any reason.

Figure 12-1

Job NumberRevision A

12512776

24 Sep 2019Kirkland Lake GoldUnion Reef EIS

Regional Groundwater Study Area Date

Data source: Data Custodian, Data Set Name/Title, Version/Date. Created by:fjohnson

2 Salamanca Square, Hobart Tasmania 7000 Australia T 61 3 6210 0600 E [email protected] W www.ghd.com

@ A31:122,000

Discharge

No flow

Granite no flow


FIGURE 12-2 CONCEPTUAL HYDROGEOLOGICAL MODEL SKETCH CROSS SECTION (AFTER TURNER, 1990)


FIGURE 12-3 CONCEPTUAL HYDROGEOLOGICAL MODEL SKETCH LONG SECTION

182

182


FIGURE 12-4 CONCEPTUAL SITE GROUNDWATER FLOWS WITH CROSSCOURSE PIT OUTFLOW UNDER CURRENT

CONDITIONS (METRES AHD)

183

183


FIGURE 12-5 CONCEPTUAL SITE GROUNDWATER FLOWS WITH CROSSCOURSE PIT OUTFLOW UNDER HIGH PIT

LAKE CONDITIONS (METRES AHD)

!(

!(

Union Reefs

Pine Creek

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Kirkland Lake GoldUnion Reef EIS

Figure 12-6


12512776

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Surface Water DrainageDate



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McKinlay River

Creeks

Model Boundary

McKinlay River

Esmerelda Creek

Wellington Creek

Pine Creek

185

185



12.3.1 RISK ASSESSMENT SUMMARY An assessment of the risk associated with the potential project impacts has been completed as discussed in Chapter

10: Risk Assessment. Of the two hazards identified for hydrological processes both were rated as low. A summary of

the risk assessment results is provided in Table 12-1.

TABLE 12-1 QUALITATIVE RISK - HYDROLOGICAL PROCESSES


Risk Level

Drawdown from mine dewatering will result in reduction in groundwater available for other users

(Pine Creek Township). Low


(adjacent landholders). Low

12.3.2 GROUNDWATER DRAWDOWN Dewatering the Prospect pits results in groundwater drawdown, and therefore, a potential change to groundwater

availability, i.e. at the McKinlay River. Drawdowns and groundwater availability are also linked to surface water

management and in this case, the management of the Crosscourse pit.

Scenario 1 – Crosscourse pit is maintained at its current low head water level (173 mAHD ) during the project

i.e. dewatering to Crosscourse pit and water treatment and discharge under a WDL.

Scenario 2 – Crosscourse pit water level is not managed during mine dewatering during construction and

mine operation, and therefore dewatering to Crosscourse pit results in water level increase to high head level

188 mAHD.

The largest groundwater drawdown is likely to occur if water levels in the Crosscourse pit are managed at

approximately current conditions (Figure 12-4). The modelled impact on the groundwater flow regime of dewatering

of the Prospect pit and underground mine has been demonstrated numerically under these conditions in Appendix H.

Likewise, the largest potential for drawdown impact on water levels within other water bodies, including pit lakes, is if

the Crosscourse pit is managed at approximately current conditions, rather than unmanaged at high levels.

In contrast, the largest potential for groundwater contamination is when Crosscourse pit is left unmanaged and

allowed to fill to high pit lake conditions (Figure 12-5). Under high pit lake conditions, impact from drawdown is

masked by the surface water inputs to the groundwater regime.

Table 12-2 describes the potential impacts associated with mine dewatering under different conditions.

TABLE 12-2 SUMMARY OF POTENTIAL IMPACTS AND RELATIVE RISKS


Levels

Relative

Risk of Impact


riparian ecosystem. Scenario 1 Higher


riparian ecosystem. Scenario 2 Lower


including pit lakes, and subsequent water quality changes. Scenario 1 Higher


including pit lakes, and subsequent water quality changes. Scenario 2 Lower

186

186



Levels

Relative

Risk of Impact

Groundwater available for nearest bore RN036105 (Territory Iron). Scenario 1 Higher

Groundwater available for nearest bore RN036105 (Territory Iron). Scenario 2 Lower




groundwater. Scenario 1 Lower


groundwater. Scenario 2 Higher

Regardless of the management approach of the Crosscourse pit lake level, drawdown and groundwater availability

impacts from dewatering of the Prospect pits and underground mine are highly likely to be smaller in magnitude and

duration than the 25 year dewatering and drawdown during recovery associated stress of the Crosscourse pit (and

other pits).

The groundwater study report (Appendix H) identifies potential impacts and risks to hydrological processes from the

proposal that relate to the effects of mine dewatering. For each potential impact identified below, this groundwater

study has provided evidence to quantify the expected impact as well as associated risks including:

Providing the current status of groundwater processes (Section 1 of Appendix H) and how the proposal may

alter the hydrological regime of the Proposal area (Figure 26, Figure 27 and Figure 28 of Appendix H),

surrounding pit lakes, ponds and dams (Table 13 and Sections 4.3.4, 4.3.5 and 4.3.6 of Appendix H) and

receiving waters, including groundwater extraction for stock watering and base flows in the Mary River

catchment area (Section 4.3.3 of Appendix H).

Discussing the potential for impact on Pine Creek bore field (Section 4.3.1 of Appendix H).

Verifying there will be no impact on Pine Creek town water supply (Section 4.3.1 and Appendix E as well as

Figure 29, Figure 30, and Figure 31 of Appendix H).

Quantifying the groundwater drawdown during operations and post-mining/closure (Figure 29, Figure 30,

and Figure 31 of Appendix H), indicating the peak drawdown and predictions of post-closure recovery of

groundwater levels, prediction of the time required for full recovery (Section 4 and Appendix E of Appendix

H), and predicted groundwater level contours at four regular intervals (Activate Layers on Figure 26, Figure 27

and Figure 28 of Appendix H) from the time of peak drawdown until the time of full recovery (Activate Layers

on Figure 29, Figure 30, and Figure 31 of Appendix H).

12.3.3 MCKINLAY RIVER Over the whole of the McKinlay River catchment the modelling demonstrates the underground mining is likely to

result in a maximum of a 3% change in groundwater available for both discharge to ephemeral pools and available for

riparian evapotranspiration. This decreases to less than 1% change in six years after mining and is likely to approach

0% after a decade. The model is designed such that this figure incorporates the impact on the downstream Mary River

catchment area including groundwater available for extraction for stock watering and base flows.

When examining local sections of the McKinlay River, the majority (approximately 60%) of this loss of groundwater

availability occurs along the two short sections closest to the underground mining from URSW10 to URSW04 and from

URSW04 to URSW03 (Figure 7-10). The maximum percentage change in this groundwater availability along these

sections is 17% and 12% respectively. These changes decrease to less than 4% and 2% respectively in six years after

mining and as is likely to approach 0% after a decade.

187

187


Whilst the key locations for aquatic ecosystems MRWET12 and MRWET13 (see also Chapter 14, Aquatic Ecosystems)

are down gradient of URSW10, these flows from URSW10 to URSW04 are the most applicable to inflow for them,

rather than the longer section from URSW08 to URSW10. Flows between URSW03 to URSW09 (Figure 7-8) are most

applicable to MRBILL01 (see also Chapter 14). The maximum percentage change in this groundwater availability along

this section is 1%. The post underground mining groundwater regime in the McKinlay River is highly likely to mimic the

pre-underground mining groundwater regime.

Peak modelled drawdowns are best represented by:

The end of mining in terms of magnitude (Figure 12-7).

The second year following mining in terms of extent (Figure 12-8).

The high pit lake scenario of 188 mAHD has been modelled to examine the impact of extreme rain events and

unmanaged water levels and these groundwater levels are plotted in Appendix E of Appendix H.

Appendix E of Appendix H also demonstrates that the majority of the modelled recovery occurs in the first six years

and complete recover is within ten years.

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Figure 12-7


12512776

06 Sep 2019Date



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GroundwaterDrawdown (m)

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5

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85

90

95

100

105

110

115

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130

135

140

145

150

155

160

165

175

McKinlay River

Model Boundary

Mine Pits, Ponds and Dams

MRWET12; MRWET13

URSW01; URSW03; URSW04; URSW05; URSW08; URSW09; URSW10

Pine Creek

51

551

55

15

51

55

1 111

11


Peak Drawdown at End of Mining (MAHD) (KLG_UR_50)

This PDF has interactive layers, please click on the icon at the top left for alternate groundwater level results

The default layer displayed is modelled drawdown at the end of Year 2 of underground mining

URSW01

URSW03

URSW04

URSW05URSW09

URSW10

URSW08

MRWET12MRWET13

@A

@A

@A

@A@A

@A

@A

@A

@A@A

@A

@A RN008106

RN008301

RN025784

RN022592RN022846

RN022727

RN022890RN021660

RN021668RN021667RN021666

RN008663

@A Pine Creek Pumping Bores

!<

!<!<

!<

!<

!<

!<

URDB6

URDB7URDB9URMB25

URMB26

RN036105

RN022577

!< Key Monitoring Bores

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LEGEND

0 1 2 3 40.5




Figure 12-8


12512776

06 Sep 2019Date



@ A31:120,000

GroundwaterDrawdown (m)

1

5

10

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25

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35

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45

50

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85

90

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McKinlay River

Model Boundary


MRWET12; MRWET13

URSW01; URSW03; URSW04; URSW05; URSW08; URSW09; URSW10

Pine Creek

51

551

55

15

51

55

1 111

11


Peak Extent of Drawdown One Year After Mining (KLG_UR_50)

This PDF has interactive layers, please click on the icon at the top left for alternate groundwater level

results The default layer displayed is modelled drawdown after 2 years after underground mining finishing

URSW01

URSW03

URSW04

URSW05URSW09

URSW10

URSW08

MRWET12MRWET13

@A

@A

@A

@A@A

@A

@A

@A

@A@A

@A

@A RN008106

RN008301

RN025784

RN022592RN022846

RN022727

RN022890RN021660

RN021668RN021667RN021666

RN008663

@A Pine Creek Pumping Bores

!<

!<!<

!<

!<

!<

!<

URDB6

URDB7URDB9URMB25

URMB26

RN036105

RN022577

!< Key Monitoring Bores

190

190


12.3.4 PINE CREEK BOREFIELD

The modelling demonstrates that there is no change to the available groundwater or groundwater levels at the Pine

Creek Borefield associated with the proposed underground mining.

12.3.5 PINE CREEK AND COPPERFIELD CREEK CATCHMENTS The modelling demonstrates that there is no change to the available groundwater or groundwater levels in the Pine

Creek and Copperfield Creek catchments associated with the proposed underground mining.

12.3.6 CROSSCOURSE PIT The modelled Crosscourse pit contributes up to an additional 3.6 L/s (Figure D-20 of Appendix H) to the rockmass due

to the underdrainage to the proposed underground mine. This approaches 0 L/s six years after mining. The post

underground mining groundwater regime at Crosscourse pit is highly likely to mimic the pre-underground mining

groundwater regime.

12.3.7 OTHER PITS The modelled other pits also contribute a combined additional maximum of 2.1 L/s (Figure D-21, Figure D-22, Figure D-

23 and Figure D-24 of Appendix H). These all approach 0 L/s within six years after mining. The post underground

mining groundwater regime at the other pits is highly likely to mimic the pre-underground mining groundwater

regime. The exception to this is the Prospect pit itself which will be dewatered and infilled to above water table during

mining. How the Prospect pit behaves in the post-mining regime depends on how closely it is returned to its pre-

underground mining condition.

12.3.8 DAMS AND PONDS The modelled dams and ponds also contribute a combined additional maximum of 3.5 L/s (Figure D-17, Figure D-18,

Figure D-19, Figure D-25 and Figure D-26 of Appendix H). The majority of this (approximately 60%) comes from Dam C,

which is the closest, largest, and highest of theses mine features, in the landscape. All approach 0 L/s within six years

after mining. The post underground mining groundwater regime at the ponds and dams is highly likely to mimic the

pre-underground mining groundwater regime.

12.3.9 STAKEHOLDERS The closest potential groundwater user is considered to be the currently unused Territory Iron bore (RN036105),

which was used for dust suppression at the rail siding and haul road adjacent to the URPA mine. The modelled

underground mine drawdown impacts groundwater level at this bore peaking at 0.08 m. This minor change should not

measurably impact groundwater availability to this bore. No other stock or domestic groundwater bores have been

identified within the zone of groundwater drawdown.

12.4 Mitigation and Management

Management of the Crosscourse pit water levels is considered a likely mitigation measure for the management of

potential groundwater contamination. Management of pit water levels could be achieved by managing:

Tailings inputs

Mine water re-use

Treatment and discharge

It is recognised that discharge will require significant multidisciplinary consideration and regulatory approval, i.e. a

Waste Discharge Licence (WDL).

A Water Management Plan will be produced prior to mining. The below monitoring program (Section 12.5) is

considered adequate to track:

The extent of the depressurisation zone and its effect during dewatering of the Prospect pits and

underground mine.

191

191


The extent of groundwater drawdown, on surface and groundwater flows as well as on other water bodies

within and adjacent to the proposal, from dewatering the Prospect pits and underground mine.

Any impact on beneficial uses of groundwater (notably the McKinlay River as a whole, the McKinlay River at

MRBILL01, MRWET12 and MRWET13, the Pine Creek borefield and the closest neighbouring groundwater

bore (RN036105).

In the unlikely event groundwater drawdown mitigation is considered necessary, the large clean water stores on site

(i.e. Dams A and C) could be considered as temporary mitigation for:

Rapid deliberate flooding of the underground mine.

One off, out of season flush discharge to the McKinlay River (pending water quality results).

Target irrigation along the McKinlay River (i.e. at MRBILL01, MRWET12 and MRWET13).

As a substitute for groundwater extraction at neighbouring bores.

It is recognised that all of these would require significant multidisciplinary consideration and regulatory approval.

12.4.1 FURTHER MODELLING The current groundwater modelling (Appendix H) is considered adequate to demonstrate the scale of the impact of

dewatering of the Prospect pit and underground mine at URPA on the site water balance. This is in-part due to the

previous works undertaken, notably AQ2 (2018) and the application of what, from an EIS perspective, are considered

the most conservative scenarios. To confirm these and the aforementioned assumptions, models for all hydraulic

conductivity scenarios within the AQ2 (2018) will be recalibrated for recharge, and run as transient models. These will

be presented in a Supplementary report.

Ongoing groundwater flow modelling is planned to occur with inputs from ongoing monitoring and reporting (Section

12.5).


In addition to monitoring existing surface and ground water sites, NTMO commits to drilling and monitoring additional

groundwater monitoring bores. A nominal program of 11 shallow bore locations is provided as Figure 12-9, and at

least some of these bores will include an adjacent bore drilled into the deeper aquifer. In addition, water levels at

MRBILL01, MRWET12 and MRWET13 will be monitored (for more information about these sites refer to Chapter 14,

Aquatic Ecosystems).

Automated telemetry loggers will be fitted to all new bores, and water level readings recorded hourly. Given the short

duration of the underground mine, data analysis of these levels and reporting on them will occur at:

Commencement of mining

3 months into mining

6 months into mining

1 year into mining

2 years into mining

1 year post mining

5 years post mining

This monitoring will include the water levels of all pits and the flow rates of all water pumped on site. Where results

exceed anticipated rates, groundwater drawdown or visible evidence of impact is observed, the groundwater

modelling will be re-assessed.

All surface water and groundwater monitoring locations will be sampled on a quarterly basis during mining, with this

frequency reviewed at the end of mining. Surface and groundwater quality monitoring will be reported on an annual

basis as part of the requirements of the mining authorisation, with this frequency reviewed at the end of mining.

In addition, all water monitoring data would be appended to annual updates to the Water Management Plan.

!<!<!<!<!<!<

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!<

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!<

!<

!<

!<

!<

!<

!< !<

!<

!<

!<

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URDB1URDB2

URDB3URDB4

URDB6

URDB7

URDB9

URMB25

URMB26

RN036105

MRWET13MRWET12

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0 0.2 0.4 0.6 0.80.1




Figure 12-9


12512776

24 Sep 2019Kirkland Lake GoldUnion Reef EIS

Proposed Groundwater Monitoring LocationsDate



@ A31:21,993

Model Boundary


!< Existing Monitoring Locations

!< Proposed Surface Water Monitoring Point

!< Proposed Groundwater Monitoring Point

!<MRBILL 01 !<

193

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12.6.1 MCKINLAY RIVER AND OTHER PONDS AND DAM The modelling demonstrates that there is not likely to be any measurable change in groundwater levels along the

McKinlay River as the river already forms the low point in the landscape. The modelling demonstrates the likely scale

of the impact on groundwater available for both discharge to the creek bed and available for riparian

evapotranspiration.

Over the whole of the McKinlay River catchment, the modelling demonstrates the underground mining is likely to

result in a maximum of a 3% change in this groundwater availability (refer Figure D-4 of Appendix H). This decreases to

less than 1% change in six years after mining, and is likely to approach 0% after a decade.

The post underground mining groundwater regime in the McKinlay River is highly likely to mimic the pre-underground

mining groundwater regime.

The post underground mining groundwater regime at the ponds and dams is highly likely to mimic the pre-


194

194


13 INLAND WATER ENVIRONMENTAL QUALITY

13.1 Overview

The environmental objective for inland water environmental quality is to maintain the quality of groundwater and

surface water so that environmental values including ecological health, land uses and the welfare and amenity of

people are protected.

This chapter describes the baseline water quality of surface water and groundwater in the headwaters of the McKinlay

River, and the water quality of pits and water storage areas (dams) associated with the URPA. The baseline provides a

measure against which potential changes in water quality as a result of the project can be identified. All baseline data

is reported in the context of ANZG (2018) guidelines. This chapter also, briefly, describes the beneficial uses and users

of these waters and the location of permanent water bodies.

Conceptual site models have been used to identify flow directions and potential qualitative changes in water quality

during mining and post mining including drainage from surface waste rock storage, passive and active water discharge

from pits and dams, seepage via groundwater and water movement across all water bodies.

Predictive water quality modelling using the Goldsim platform is proposed to link mine features that are influenced by

the project activities and to make predictions about potential impacts to water quality reporting to locations where

there may be risks to inland water quality.

The information contained in this chapter is drawn from the Geochemical Water Quality Modelling report (Appendix I)

and Geochemical Waste Characterisation of Waste Rock and Ore (Appendix F).


The key local drainage feature downstream of the URPA is the McKinlay River and its tributaries. The hydrology of the

catchment is documented in Section 7.5. The drainage lines surrounding the URPA include Wellington Creek, flowing

into McKinlay River to the north and Esmerelda Creek, flowing into the McKinlay River to the south (Figure 12-6).

Adjacent to the URPA (8478800 to 8490000 mN) the McKinlay River has a declared beneficial use for aquatic

ecosystem protection. The surface water use changes to livestock drinking water approximately 4 km downstream of

monitoring point URSW08, with Pastoral Stations being the main downstream users. In addition, the whole of the

Mary River catchment has a declared surface water beneficial use for environmental, riparian and cultural uses, and a

declared ground water beneficial use for environmental, riparian and agricultural uses. Water Quality Guideline Values

Water quality Guideline Values (GV) have been developed for the URPA (Table 13-1) based on the ANZECC Australian

and New Zealand Guidelines for Fresh and Marine Water Quality 2000 (ANZECC & ARMCANZ, 2000) and sampling

results from McKinlay River upstream reference site URSW09 (Table 13-1).

!(

!(PINE CREEK

ADELAIDE RIVER


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Esmeralda Creek

McKinlay River

Wellington Creek

URST4A

URRD

URDP

URCP

DAMC

DAMB

DAMA

URSW11

URSW03

URSW10

URSW09

URSW08

URSW05

URSW04

URST5B

Prospect Pit N

STUART HIGHWAY Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/AirbusDS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo,and the GIS User Community

Union Reefs Project Area McKinlay River Water Monitoring Locations

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0 1 2

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Figure 13-1

196

196


The McKinlay River catchment ecosystem condition determined from local reference data indicates that surface water

is of slight to moderate disturbance. Modification of water quality is due to the long history of anthropogenic activities

at URPA and typical tropical ecosystem characteristics, such as the wet-dry climate. The ANZECC & ARMCANZ (2000)

Guidelines set varying GV levels of ecosystem protection derived from local reference data.

Based on the above considerations, NTMO has therefore adopted the 95% ecosystem protection GV for

environmental protection at surface water monitoring point URSW08 (Figure 13-1), i.e. the end of the mixing zone.

This is with the exception of aluminium and zinc, which have derived site specific trigger values (SSTVs) using ANZECC

& ARMCANZ (2000) guidelines being the 80th percentile of the historic dataset. This is due to the local mineralisation,

and therefore naturally elevated concentrations of both species in the upstream control samples (URSW09). Livestock

drinking water guidelines (SWG) are also considered given the downstream declared beneficial use.

NTMO has adopted the 95% ecosystem protection GV and SWG (where applicable) at all other surface water creek

monitoring locations (URSW sites) and the 80% ecosystem protection GV and SWG at all other surface monitoring

sites, i.e. at water ponds and dams. This provides a good understanding of the site water quality, seasonal variations

and enables an assessment of potential environmental impacts in the event of discharge.

There are no current GV for groundwater ecosystem protection, however ANZECC & ARMCANZ (2000) provides values

for stock drinking and agricultural irrigation – both of which have been identified as beneficial uses of groundwater. It

is also appropriate to consider the connectivity between groundwater and surface water ecosystems and so

groundwater data is compared to the 80% ecosystem protection GVs and SWG (where applicable, i.e. where mine

dams mix with groundwater).

The URPA GV (Table 13-1) are used as an early warning mechanism to provide insight into potential adverse water

quality changes. The GV are used to trigger surface water management actions if water quality sampling indicates on-

going values outside of the GV and/or the long-term site data range.

TABLE 13-1 URPA WATER QUALITY GUIDELINE VALUES

Parameter Unit

Applicable Guideline Values

URSW08 95%

(i.e. SSTVs)

URSW

Monitoring Sites

(natural

streams)

95%

All Other Surface

and

Groundwater

(anthropogenic

water bodies

and

groundwater)

80%

All

SWG

pH 6.0 - 8.0 6.0 - 8.0 6.0 - 8.0 4.0 - 9.0

Electrical

Conductivity (EC)

μS/cm 20 - 250 20 - 250 20 - 250 5,970

Dissolved Oxygen

(DO)

%

Saturation

40 - 120 (1) 90 - 120 90 - 120 -

Turbidity NTU 2 - 15 2 - 15 2 - 15 -

Total Suspended

Solids (TSS)

mg/L 30 (1) - - -

Dissolved Aluminium

(Al)

μg/L 150 (2)(3) 55 (3) 150 (3) -

Total Aluminium (Al) μg/L - - - 5,000

197

197


Parameter Unit

Applicable Guideline Values

URSW08 95%

(i.e. SSTVs)

URSW

Monitoring Sites

(natural

streams)

95%

All Other Surface

and

Groundwater

(anthropogenic

water bodies

and

groundwater)

80%

All

SWG

Dissolved Arsenic

(As)

μg/L 13 13 140 -

Total Arsenic (As) μg/L - - - 500

Dissolved Cadmium

(Cd)

μg/L 1(1)(4) 0.2 (4) 0.8 (4) -

Total Cadmium (Cd) μg/L - - - 10

Dissolved Cobalt (Co) μg/L 2.5 (6) 2.5 (6) 13 (5) -

Total Cobalt (Co) μg/L - - - 1,000

Dissolved Copper

(Cu)

μg/L 4.4 (1)(4) 1.4 (4) 2.5 (4) -

Total Copper (Cu) μg/L - - - 1,000

Dissolved Iron (Fe) μg/L 300 (7) 300 (7) 300 (7) -

Dissolved Manganese

(Mn)

μg/L 1,900 1,900 3,600 -

Dissolved Nickel (Ni) μg/L 11 (4) 11 (4) 17 (4) -

Total Nickel (Ni) μg/L - - - 1,000 (cattle)

Dissolved Zinc (Zn) μg/L 31 (2)(4) 8 (4) 31 (4) -

Total Zinc (Zn) μg/L - - - 20,000

Sulphate (SO4) mg/L - - - 1,000

Calcium (Ca) mg/L - - - 1,000

Cyanide (CN) mg/L 7 7 18 -

Notes:

1. 80th percentile of URSW09 for GV as per ANZECC & ARMCANZ (2000). Dataset from 2010 to 2019.

2. 80% GV based on mineralisation and natural elevated levels.

3. GV should not be applied to samples with pH less than 6.5.

4. GV to be hardness modified.

5. Canadian 80% GV as recommended by NT EPA.

6. Canadian 95% GV as adopted by ANZECC & ARMCANZ (2000).

7. Low reliability GV ANZECC & ARMCANZ (2000). (Chapter 8.3.7).

198

198


13.2.1 PERMANENT WATER BODIES

No springs are known within the study area. Groundwater discharge is not adequate to produce springs or provide dry

season baseflow capable of producing surface water flow (Appendix H).

Immediately downstream (within 250 m and 750 m respectively) of URSW10, two permanent water locations have

been identified (MRWET12 and MRWET13, Appendix J) and these will remain a focus for assessment of aquatic

ecosystem impacts throughout mining.

13.2.2 BASELINE SURFACE WATER QUALITY The water quality monitoring program conducted by NTMO at the URPA includes sampling locations on the McKinlay

River (Figure 13-2), a control upstream from the site (URSW09) and one which serves as a compliance point

downstream from the site (URSW08). Comparison of results from analysis of water sampled at these two sites allows

assessment of the impact of the URPA on the quality of water in the McKinlay River downstream of the site over the

past ten wet seasons, i.e. 2010 to 2019.

A32345678

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DAM A

CC

DAM C

WEST WRD

EAST WRD

SEDIMENT TRAP 4A

FUEL BAY AND HAULAGE WASHDOWN

MILL

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C

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DAM B

OLD TAILING STORAGE SEDIMENT TRAP 5B

DUSTSUPPRESSION

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URSW04

URST4A

URSW10URSW01

URSW08 (COMPLIANCE)

URST3

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MCKINLAY RIVER WEIR WETLANDS

WELLINGTON CREEK

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DECANT POND

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PLANT SPILL POND

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URRD

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(CAPPED )

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DAM

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PIT

TAILING STORAGE FACILITY

DIVERSION CHANNEL

TAILING DISCHARGE

PROSPECT PIT

C

LADY ALICE PIT

C

UNION NORTH PIT

C

URPSP

Underground Production Usage

Crosscourse Water Treatment

ROM

Figure 13-2


13.2.3 SURFACE WATER MONITORING DATA The surface water monitoring data analysis is detailed in Appendix I and is summarised here. It shows:

There is ‘no significant difference’ in upstream and downstream pH in the McKinlay River, with circum-

neutral pH at both sites during nine seasons of monitoring.

There is ‘no significant difference’ in upstream and downstream dissolved oxygen concentration.

Elevated downstream concentrations of sulphate, calcium and magnesium have been measured consistently

in downstream samples since 2010, however during nine seasons of monitoring, Electrical Conductivity (EC)

has been within the Guideline Values (GV), demonstrating that the impact has been slight.

(Limited) monitoring data collected before processing of sulphidic ore from the nearby Cosmo mine in 2011

and after processing was discontinued (2017) indicates EC, sulphate, calcium and magnesium concentrations

were similar to those measured during the period in which sulphidic ore was processed, while tailings were

deposited sub-aqueously in Crosscourse pit. This suggests the NMD from URPA is not originating from

Crosscourse pit as a result of tailings deposition.

Many metals (Cd, Co, Cr, Cu, Mo, Ni, Pb, Se) were non-detectable in the vast majority of samples.

Al, As, Mn and Zn were detected in most samples across the nine seasons of water quality monitoring,

however there appears to be no significant difference in the concentrations of these metals/metalloids in

upstream and downstream samples, and no change in average concentrations during the nine seasons of

monitoring.

Concentrations of As and Mn have been below GV for all samples and Al and Zn concentrations were below

GV for the majority of samples. When downstream concentrations of Al and Zn did exceed GV, generally

upstream samples also gave elevated concentrations suggesting the origin of these metals is upstream of the

URPA.

Sources of NMD

Water sampled from Sediment Trap 5B (ST5B) and Sediment Trap 4A (ST4A) and from the TSF decant pond (URDP)

have significantly higher EC, and concentrations of sulphate, calcium and magnesium than other sampling points

downstream of the mine area. These sampling points include seepage water from the east and west Waste Rock

Dumps (WRD), and the old tailings storage facility (Figure 13-2) which indicates that these historic mining structures

are a significant source of NMD at the URPA.

Attenuation of Metals

Concentrations of Cd, Ni and Zn and, to a lesser extent, Co are elevated in water sampled from ST5B and Dam C

suggesting these metals are originating from the East WRD. Concentrations in Dam B and Sediment Trap 3 (ST3) are

significantly lower, suggesting that the West WRD is a lesser source of these metals (Figure 13-2).

Concentrations of As are elevated in water collected from URDP, indicating the old TSF is a source of this metalloid

(Figure 13-2). However, all of these metals/metalloids are routinely measured at background concentrations

downstream of the site in the McKinlay River, demonstrating effective attenuation of the concentration of these

elements.

Crosscourse Pit Water Quality

Analysis of Crosscourse pit water quality since 2010 has demonstrated that this pit contains the poorest quality water

at URPA. The sampling period spans 2011 to 2017, i.e. including when CHPA ore was processed at the URPA. This

allows comparison between periods during tailings deposition (2017 and earlier) and the two years after tailings

deposition ceased. The results show:

The pH has generally been within GV.

The EC has been significantly above GV.

WAD cyanide concentrations have been non-detectable in nearly all samples despite significant

concentrations in the tailings discharge to the pit, indicating that cyanide is short-lived.


Concentrations of As, Co and Cu (data not shown) are high in water sampled from the Crosscourse pit in

comparison to other monitoring sites.

The concentrations of metals/metalloids (As, Co, Cu, and Zn) have exceeded GV many times during ten years

of testing which suggests these metals are effectively solubilised during processing of ore and remain in

soluble form following deposition into the pit. Since processing was discontinued in 2017, there has been

very little change in the chemistry of the pit water, with the concentrations of most metals and metalloids

remaining approximately constant. The concentrations of both Co and Cu however, appear to have decreased

since processing stopped.

The concentration of As appears to have stabilised at around 1,000 g/L since 2014 after decreasing from

around 4,000 g/L in 2011. This has occurred despite the very variable concentrations (≈1,000 to 6,000 g/L)

of As in the discharged tailings. The controlling factors for As concentrations in the pit water are not clear.

EC and concentrations of sulphate and calcium are significantly elevated in the Crosscourse pit. This reflects

tailings deposition where high sulphate concentrations likely result from oxidation of sulphidic ore and

elevated calcium from lime addition for pH adjustment during processing. The low concentrations of

magnesium suggests that this water body is not a significant contributor to the NMD found in McKinlay River

water downstream of the URPA.

Other Pit Water Quality

Analysis of water from the smaller pits at the URPA which include Lady Alice, Prospect and Union Reefs North pits has

been limited and has only been conducted regularly since March 2018. The results of water quality analysis in these

pits during the past 18 months show:

Water in these smaller pits is generally of better or comparable quality to other water bodies at URPA, and

there has been little variation in water quality in these pits across the testing period, and between samples

collected during wet and dry seasons. The pH has been circum-neutral during the sampling period and salinity

has been relatively low (EC = 250 to 300 S/cm). Sulphate concentrations in water from these pits is relatively

low, generally less than 100 mg/L, with concentrations in Prospect pit North water slightly higher (100 to

150 mg/L).

Water in these smaller pits is of considerably better quality than water in Crosscourse pit with much lower

salinity and metal/metalloid concentrations. Metals generally have not been detected in water from these

pits with the exception of As, Cd, Cu, Mn, Ni and Zn. Concentrations of As and Zn are elevated in all pit

waters, but below the GV with the exception of As in Lady Alice pit and Zn in the Prospect South pit. These

results suggest that water quality may reflect relatively benign interaction with the pit walls, with the

exception of dissolution of As in Lady Alice pit and Zn in Prospect South pit.

13.2.4 GROUNDWATER MONITORING DATA The water quality monitoring program conducted by NTMO at the URPA also includes groundwater monitoring data

collected at six monitoring bores (Figure 13-1) since 2012. Groundwater monitoring bores URDB1 to URDB6 are

located between the decant pond which collects seepage from the old TSF and the McKinlay River. The results of

water quality monitoring in these bores show:

The pH of groundwater sampled from these bores was circum-neutral (6 to 7) during the eight years of

monitoring.

Groundwater below the old TSF has elevated salinity (EC 1,000 to 2,000 S/cm).

Metal concentrations in groundwater below the old TSF are generally low with the exception of Zn in one of

the monitoring bores (URDB4), cobalt in all of the monitoring bores, and slightly elevated Mn in most of the

monitoring bores.

The high concentrations of Co in groundwater below the old TSF is not reflected in the TSF decant water. However,

tailings water from more recent processing at UR contained elevated concentrations of Co. It is reasonable to assume

that the tailings deposited in the old TSF from earlier processing operations would also have contained high

concentrations of cobalt and the tailings in the old TSF are the source of Co in groundwater near the TSF. However, it

seems that this groundwater is not migrating to any significant extent into the nearby McKinlay River as


concentrations of cobalt in surface water sampled from the nearby downstream sample point (URSW03) have been

very low (Figure 13-2) across the same period of time in which high concentrations have been measured in adjacent

groundwater.

There are also two groundwater monitoring bores, URMB25 and URMB26, located to the north of Crosscourse pit and

between the East WRD and Crosscourse pit respectively. There are a further two monitoring bores, URDB7 to the

north of Lady Alice pit and URDB9 to the north of Union North pit (Figure 13-1). Monitoring of these groundwaters

have been conducted since 2010 with the exception of URDB7 which has analysis results since 2012 and URMB26 with

results since 2015. These show:

Groundwater pH values have been circum-neutral.

Groundwater salinity is low to moderate (EC 200 to 700 S/cm).

Concentrations of metals in groundwater sampled from these bores are generally low with the following

exceptions:

o Concentrations of Zn in groundwater sampled from bore URMB25 have generally been elevated

during the past ten years.

o Concentrations of As and Zn in groundwater sampled from bore URDB9 have been variable and

elevated during the past ten years.

o Concentrations of Co in groundwater sampled from bore URDB9 have been somewhat elevated

during the past ten years, but concentrations have gradually decreased and are currently

considerably lower than were measured ten years ago.

Groundwater does not appear to be migrating to any significant extent into the nearby McKinlay River based on

concentrations of cobalt in water sampled from the nearby downstream surface water sample point (URSW03), which

have been very low across the same period of time in which high concentrations have been measured in adjacent

groundwater monitoring locations.


13.3.1 RISK ASSESSMENT SUMMARY An assessment of the risks associated with potential project impacts has been completed and discussed in Chapter 10:

Risk Assessment.

There was 17 identified hazard associated with inland water environmental quality for the project, two were rated

medium and 15 were rated low as presented in Table 14-2.

TABLE 13-2 RISK ASSESSMENT – INLAND WATER ENVIRONMENTAL QUALITY

Potential Event Residual Risk

Level

Contaminated seepage during surface storage of underground mine waste rock (temporarily

stockpiled). Low

Contaminated seepage from permanent surface storage (i.e. in-pit storage in Prospect pit) of

underground mine waste rock (50,000 t) and waste rock sourced from the Prospect North pit

used in the portal development.

Low

Contaminated seepage/runoff from oxidation of sulphidic rocks in the walls of Prospect pit

exposed to the atmosphere following dewatering; and/or

Change in groundwater quality as a result of dissolution of oxidation products after

groundwater rebound following closure.

Low


Potential Event Residual Risk

Level

Crosscourse pit is left unmanaged (no management of water level) and allowed to fill to high pit

lake conditions. Medium

Contaminated seepage from Crosscourse pit migrating to the underground development during

operations. Low

Contaminated seepage from underground development and backfilled waste rock and/or pit

walls at closure infiltrating groundwater. Medium

AMD from ROM pad leading to contaminated seepage run-off. Low

Failure of pumps to redirect accumulating water in Prospect resulting in infiltration to

groundwater. Low

Poor management of waste materials during operations leads to closure plans being

unachievable or costly. Low

Closure designs not developed in detail to enable appropriate closure execution, including

ineffective implementation of design, poor rehabilitation execution or design failure, resulting

in significantly higher closure cost above closure provisioning.

Low

Unexpected early closure of the project, due to delays or falling commodity prices or another

unexpected issue. Low

Unable to reach agreement with stakeholders on closure objectives. Low

Potential impacts on surface and groundwater quality may arise as a result of the following sources, features and/or

processes:

Acid Rock Drainage (ARD) resulting from the oxidation of sulphidic materials exposed to oxygen. This may

arise from:

o Water level fluctuation in water storage areas exposing pit walls

o Waste rock dumps or stockpiles and/or tailings containing sulphidic mineralisation

o Underground works

o Sulphidic materials used to construct infrastructure such as ramps, roads and platforms

Saline, metalliferous drainage and/or neutral drainage may also be produced by the materials described

above, without producing sulphidic acidity, but rather, latent acidity.

Existing surface water features such as pit lakes, water storage dams which may have dissolved substances

above guideline values, or have the potential to exceed guidelines from evaporative concentration, change in

water level or as a result of the disposal of mine products sub-aqueously.

13.3.2 IMPACT ASSESSMENT In order to undertake impact assessment against the identified risks above, a number of tools were used. The

groundwater model (Appendix H, GHD 2019) was used to understand current (or baseline) seepage to/from each of

the water storage areas on site (Figure 12-4). Based on the topographic elevation of the water storages and water

levels in those storages, changes in water as a result of dewatering the Prospect pits levels in Crosscourse pit and the

Satellite pits was assessed by GHD (Appendix H). This information was cross checked with the seepage rates obtained

from the water balance model for model validation purposes (Section 8.1).

The conceptual assessments described below were used to demonstrate qualitatively, the potential level of impact

from proposed mining activities during operations and post closure.


Geochemical modelling will be undertaken (to be included in a Supplementary report) that will address quantitatively,

the level of water quality impact, once the full suite of geochemistry test work has been completed. This test work is

described in Section 4.10.2 in this draft EIS. The geochemical modelling results will also be reported in a

supplementary report to this draft EIS.

This water quality model assumes that the water level in the Crosscourse pit rises above the equilibrium groundwater

level during the first year of operation due to mine dewatering, and remains at 173 m AHD during Year 2, i.e. with

intended discharge.

Construction and Operational Stage Conceptual Site Model

During mining, the sources, pathways and sinks have been represented in Table 13-3 below. The conceptual site

model is based on change in flow for each of the water storage areas and the McKinley River, as predicted by the

groundwater model (Appendix H) and validated with the mine water balance.

The impact from underground mine dewatering reaches its maximum in Dam A and B, Crosscourse pit and other

minor pits and dams, at or just after, mine closure. The impacts are described, qualitatively, in Table 13-3.

TABLE 13-3 OPERATIONAL STAGE CONCEPTUAL SITE MODEL

Site Feature Current Status Change During Operation

(from Appendix H) Impact on Groundwater Chemistry

McKinlay River

Sink

Receives groundwater contribution.

From 2 to 17% (depending on location – an average of 3%) less groundwater available to the river compared to pre-mining flow in various river sections (refer to Appendix H for detailed volumes).

None

Dam A Mainly groundwater sink

Up to 0.2 L/s additional seepage to groundwater.

Negligible

Dam B Mainly source of seepage to groundwater.

Increased seepage up to 0.9 L/s, change in RL of 5.1 m.

The change in water level comprises both loss and gain as explained in Appendix H.

Seepage from Dam B reports to the McKinlay River.

Assuming hydraulic conductivity of 0.3 m/d, gradient between the River and Dam B of 0.01 and porosity of 0.01, it will take >4 years for the seepage to reach the River, by which time seepage will be dispersed and solutes adsorbed onto sediments through which it flows, and diluted as it reaches the shallow alluvium via groundwater.

Dam C Source – seepage to groundwater.

Increased seepage up to 2 L/s and 0.8 m decrease in RL.

Seepage will be to groundwater with potential flow towards Dam A.

None, water quality generally good with minor exceedance.

Prospect pit Sink – receives groundwater contribution.

Completely dewatered exposing rock to oxidation.

None, water will be circulated into Crosscourse pit.

Underground mine

Sink – receives groundwater.

Groundwater ingress. None, water will be recirculated back to Crosscourse pit.


Site Feature Current Status Change During Operation

(from Appendix H) Impact on Groundwater Chemistry

Crosscourse pit

Sink

Source – some seepage to groundwater.

Increased seepage up to 3.5 L/s to groundwater, reporting to the underground mine.

Seepage of water from Crosscourse pit, but the underground mine will act as a sink and water then recirculated back into the Crosscourse pit.

Lady Alice pit Sink for up gradient storage.

Increased seepage up to 0.7 L/s.

Elevated As in the pit water will report to the Union North pit which also has existing, elevated As. Some minor, additional concentration likely to enter groundwater system from the pit.

Other pits

Sink for up gradient storage.

Source – seepage to groundwater.

Union north and Union South pit 0.3 and 0.4 L/s additional seepage, other pits negligible change.

Union North pit and Union South pit has elevated As and Fe – contributes to concentration of contaminants entering groundwater system, however seepage to groundwater is minor.

Union Reef dam


Increased seepage up to 0.1 L/s.

Negligible

Decant seepage


No change None

Post Closure Conceptual Site Model, under Scenario 1

Following completion of mining, groundwater levels will be allowed to recover in the backfilled, underground mine

void, Prospect pits and Crosscourse pit.

Under scenario 1, Crosscourse pit is maintained at its current low head water level (173 mAHD) during the project and

post closure i.e. dewatering to Crosscourse pit and water treatment and discharge under a WDL.

The groundwater modelling (Appendix H) predicts recovery of water levels to their equilibrium condition (Figure 12-4

in Chapter 10) after six years post closure. The sources, pathways and sinks have been identified and are described in

Table 13-4.

TABLE 13-4 CONCEPTUAL SITE MODEL POST CLOSURE

Description Status Change Post-Operation Impact on Groundwater Chemistry

McKinlay River

downgradient

from the mining

operation

Sink

Recovery of groundwater

levels in section of the

river impacted by mining

operation.

Sections down-gradient from Crosscourse pit

may receive groundwater contribution with

additional contaminant load.

Dam A Source

Reduction in seepage to

pre-mining levels, 0.5 m

change (both increase

and decrease) in RL as a

result of underground

operations likely to reach

maximum after closure.

0.5 m change in elevation is expected to result in

minor additional change in chemistry due to

contact with exposed walls. PAF material in the

pit walls may result in an increase in metal

concentration.


Description Status Change Post-Operation Impact on Groundwater Chemistry

Dam B and C

Source –

seepage to

groundwater.


pre-mining levels over

time.

It is expected that dam walls are not acid

generating and are constructed of compacted

soil. Dam B is likely to be a potential source of

seepage of contaminated water generated via

through flow from Crosscourse pit, towards the

River.

Underground

mine Sink

Groundwater inflow – will

recover to pre-mining

levels in Prospect pit

within six years.

The walls of the underground mine and backfilled waste rock, exposed to air, allows oxidation of sulphidic materials. This is a potential source of contamination for groundwater system depending on the lag time of the sulphides (to be determined in test work to be reported in the

Supplementary report).

Crosscourse pit

Sink for up

gradient

storage.

Source –

seepage to

groundwater.


pre-mining levels over

time.

Continued seepage, similar water quality

expected as before mining.

Lady Alice pit Sink Reduction in seepage to

pre-mining levels.

There will be a positive change in RL of water of

4.5 m following recovery and additional

geochemical loading may occur. Given the

significant water volume already in the pit, and

historical refill of the pit, it is expected that if

solutes are dissolved from pit walls, they will be

significantly diluted.

Other pits Source Reduction in seepage to

pre-mining levels. Negligible change in water quality.

Union Reef dam Source Reduction in seepage to

pre-mining levels. None.

Decant seepage Source No change. None.


Post Closure Conceptual Site Model, under Scenario 2

Under scenario 2 Crosscourse pit water level is not managed during mining and therefore dewatering to Crosscourse

pit results in water level increase to high head level 188 mAHD at, or soon after, mine closure. The pit lake water level

reaches equilibrium at about this level (refer Figure 13-3).

FIGURE 13-3 CROSSCOURSE PIT POST CLOSURE WATER BALANCE

This conceptual model scenario assumes water contributing to the Crosscourse pit during operations, as well as

extreme and repeated seasonal rainfalls, with no intended water discharge from the pit during operations. This results

in the predicted water level in this pit varying from the current level to a maximum 188 m AHD; approximately 1 m

below the spill level, and some 15 m above the treat and discharge level.

The groundwater level results of this scenario have been modelled (Appendix H) and the results indicate that, at this

level, predicted groundwater flow will be from Crosscourse pit to all other pits and dams on site, and McKinlay River,

via the shallow aquifer (Figure 12-5). In the period six years post mining, groundwater outflow from Crosscourse pit

would peak at 17 L/s within first two years and stabilise at around 13 L/s five years after post mining (Appendix H).

These conditions will prevail until the water level in the Crosscourse pit reduces to about 173 mAHD.

In this case Crosscourse pit would contribute to additional contamination in all pits through mass transport.

Groundwater would become contaminated and would contribute to contamination downgradient in the McKinley

River.

Assuming a groundwater gradient between the Crosscourse pit and the river of 0.04, a hydraulic conductivity of

0.3 m/d and a porosity of 0.2, the linear groundwater velocity is estimated to be 900 m/d, i.e. a continuous and quick

discharge of water from the Crosscourse pit to the River (Appendix I). In the wet season when maximum flow in the

0

100

200

300

400

500

600

700

800

165 170 175 180 185 190

Wate

r flux

(ML/d

ay)




McKinlay River occurs, groundwater flow will be less than 1% of river flow i.e. 0.013 m3/s groundwater flow versus 550

m3/s river flow (AECOM 2018). In the dry season groundwater flow will be significantly higher.

The resulting geochemistry of the shallow groundwater and McKinlay River will depend on the adsorption of metals

onto sediments and change in pH and redox conditions along the flow path.

This scenario has been assessed only in the context that water levels in Crosscourse pit will be managed i.e. the water

level in Crosscourse pit will be maintained such that it remains a sink. With this control in place the risk has been

assessed as High i.e. major regional impact, possible likelihood. This risk has been reduced to Medium with the

implementation of engineering controls to reduce water levels if the water discharge option is not entirely successful,

i.e. the company has the capacity to move water around if required.


The management of potentially contaminated water from the underground mine and from the temporary waste rock

dump in Prospect pit South will be by storage in Crosscourse pit during mine development and operation. Seepage

from Crosscourse pit will be monitored downgradient of the pit via a series of monitoring bores along the

groundwater flowpath towards the River (see Figure 12-9).

The disposal of waste rock into the underground void will be managed such that PAF material is maintained saturated

long term. This will begin at mine closure when mine dewatering is stopped and as the groundwater level starts

recovering, with some potential for sulphide oxidation from void and backfill material, commensurate with lag times,

until these materials are completely inundated. The backfilled underground void will remain saturated. Management

will therefore focus on maintaining saturation in the backfilled void. Groundwater monitoring down gradient of the

void will help detect any potential contamination and provide early warning for any unexpected changes.

Changes in pit water level will not require management if the pit walls are not acid generating. However, in the event

that acid generating material is exposed, the water level will be managed such that the water level will be kept stable

during operations. This would be achieved by disposing water into the pit where high water level fluctuations are

expected. It is not expected that water in Lady Alice pit will become contaminated as the pit walls were exposed in the

past and the water level has recovered while the water quality in the pit has remained of good quality.

Potential seepage will be monitored by specifically targeted monitoring bores located downgradient of the e.g. Lady

Alice pit and Dam B.

Monitoring bores will be installed downgradient of the Dam B and Crosscourse pit to monitor the changes in water

chemistry over time.

Water quality monitoring will be undertaken quarterly for major ions, field parameters and heavy metals (As, Cu, Ni,

Pb, Zn, Fe). The sampling frequency will be quarterly during the two years of operation reducing to yearly during post-

mining period. Water quality data will be:

Compared to ANZG (2018) guidelines for the slightly disturbed ecosystems.

Compared to long terms site specific guidelines that need to be developed.

Reviewed annually by a qualified hydrogeochemist, and if no statistically significant changes are observed

after two years, the monitoring frequency can be reduced.

As the water level recovers in Dams A, B and C and Lady Alice pit, the water in these pits and consequently any

seepage via groundwater might impact the downgradient environment and surface water.

The full extent of this will be addressed by predictive geochemical modelling to be reported in the Supplementary EIS

once the geochemistry data has been assessed from known oxidation profiles and more geochemical information is

available.



Should the water level in the Crosscourse pit reach 188 mAHD this would result in seepage to all water storage dams

and 13 L/s outflow via groundwater reporting ultimately to the McKinlay River. To manage this, a system of

interceptions would be needed to prevent the poor-quality water entering the shallow alluvium or river water. To

avoid this, it is required to keep the water level in Crosscourse pit at current level i.e. 173 - 175 mAHD.

Monitoring of groundwater quality in the vicinity and downgradient of the Crosscourse pit will continue at existing

bores, and new bores will be established between the pit and the river. The groundwater monitoring results will be

statistically reviewed and monitoring will be adjusted depending on the findings of the analysis. Should the monitoring

and assessment find any adversely impacted groundwater and exceedance of guideline values, the sampling will be

repeated and the reason for change will be investigated. Engineering mitigation will be investigated (to be

implemented at Dam B) if heavy metal concentration is recorded above ANZECC & ARMCANZ 2000 guidelines in

downgradient bores.


The qualitative assessment of inland water quality sources, pathways and sinks presented in this report found that

there is a relatively low level of risk to surface water and groundwater quality in the mining, closure and post closure

phases of the project, provided the water level in Crosscourse pit is managed. The quantitative extent of impact is

predicted to be low, as reported in these preliminary findings, but will be reported in detail following the delivery of

the predictive geochemical modelling in a Supplementary EIS.


14 AQUATIC ECOSYSTEMS

14.1 Overview

This chapter addresses the potential impacts of the proposal on aquatic ecosystems, as required for the TOR. It

characterises the aquatic ecosystems present within the upper McKinlay River and its tributaries, and describes the

distribution and abundance of these systems in the context of the existing Union Reefs Project Area (URPA). It also

draws on the predicted changes in hydrological processes (Chapter 12) and water quality (Chapter 13) to assess the

potential impacts of the proposal on the aquatic ecosystems.

Section 2.2.4 of the EIS TOR provided the following environmental objective in relation to aquatic ecosystems:

‘[To] protect aquatic ecosystems to maintain environmental water requirements and the biological diversity

of flora and fauna and the ecological functions they perform.’

This chapter describes the potential direct and indirect impacts of the project on aquatic ecosystems, including direct

impacts on groundwater availability to aquatic ecosystems, and the quality of groundwater dependent aquatic

ecosystems and riparian vegetation during and post mining. Mitigation measures that will be implemented in order to

minimise the impact of project construction and operation are discussed.

This chapter also considers the cumulative effects of extraction of groundwater during operation, and impacts beyond

closure as required in the TOR for the project.

An aquatic ecosystems report is provided in Appendix J, including descriptions of the desktop and field survey

components of the assessment.


At its closest point, the McKinlay River is located less than 1 km from the proposed underground mine. The two main

sub-catchments that drain the project area include Esmeralda Creek to the south and Wellington Creek to the north.

These flow into the McKinley River, which flows along the western edge of the URPA lease.

The upper McKinlay River catchment is highly modified as a result of historic gold mining over 140 years, and

particularly due to recent mining activity over the past 40 years. The River flows intermittently, flowing through the

wet season and receding to isolated pools in the early dry season. Flows are highly variable and extremely responsive

to rainfall, reaching peak levels of overland flow in February and March. Surface flow may continue into the early dry

season, but does not contribute significantly to the permanent water present through the dry season. Water is

available in the late dry season only where groundwater discharges to the bed, bank, pools and riparian zone, i.e. at

the lowest points in the landscape. These permanent pools of water and the associated riverine flora serve as refuge

habitats through to the end of the dry season (Appendix J).

A Beneficial Use Declaration (BUD) to maintain the health of aquatic ecosystems has been set for a section of the

McKinlay River that flows to the west of MLN1109 (between lines 8478800 and 8490000). The surface water beneficial

use objective changes to livestock drinking water approximately 4 km downstream of URPA surface water monitoring

point URSW08, with Pastoral Stations being the main downstream users. Two wet season, passive discharge points lie

within the McKinlay River BUD:

The former TSF Decant Pond passively discharges via a spillway into the McKinley River.

Dam C, which receives seepage from the East Waste Dump, passively discharges via a weir and spillway into

Dam A and then Dam A discharges into Wellington Creek.

Two man-made features have altered the hydrology of the upper McKinlay River, a weir constructed for historical

mining, and a road and rail crossing downstream of the weir, where the McKinlay River turns west. Water

infrastructure at URPA is further detailed in Section 4.7.


Aquatic ecosystem monitoring undertaken at sites on the McKinlay River and its tributaries since 2009 (Appendix J)

indicates that:

In most years, in the early dry season, base flow (i.e. surface flow) is still present at the majority of sites.

The macroinvertebrate and fish community is ecologically adapted to intermittent flow conditions, and is

pollution tolerant (e.g. tolerant of low dissolved oxygen and concentrated dissolved salts).

There is often higher diversity and better macroinvertebrate metric results downstream of the URPA than

upstream, given the more permanent water bodies present.

The upstream macroinvertebrate community is somewhat different to that downstream, which aligns with

the difference in the upstream sites which are located in the headwaters of the catchment, where water

availability is lower.

The alluvial flats, incised channels and riparian vegetation of the upper McKinlay River are important areas of

biodiversity i.e. significant numbers of terrestrial and aquatic species have been observed. The magnitude and

longevity of flow appears to be a key ecological driver of the river (Appendix J).

The ecology of remnant, dry season pools in the upper McKinlay River is not broadly understood, nor is the extent to

which the groundwater influences dry season ecology in the river. Aquatic Ecology Services was engaged by NTMO to

conduct a dry season field survey along the McKinlay River in late August 2019 in order to map and characterise the

aquatic ecosystems, with particular reference to remnant, dry season pools (i.e. refugial pools).

14.2.1 GROUNDWATER DEPENDENT ECOSYSTEMS The 2018/2019 wet season was poor across large areas of the Northern Territory, including the URPA. Compared with

the previous year, only half of the rainfall was recorded in the 2018/2019 wet season. It is expected that, during a

below-average year of rainfall, groundwater recharge and subsequent base flow would be reduced in the McKinlay

River. The lower than average wet season rainfall presented a unique opportunity to understand the role that

groundwater plays in maintaining surface water in the upper McKinlay River through the dry season.

A total of 38 sites were recorded during the field survey conducted along the upper McKinlay River in August 2019,

which included 16 wet sites, 19 dry sites, two billabongs and one weir. Of the 16 wet sites, there were a large number

where very little surface water remained, which indicated that these sites would likely not hold water by the end of

the dry season.

Fourteen sites were assessed in detail (Figure 14-1) including larger pools that were likely to hold water for the

entirety of the dry season, and a number of sites with little or no water, that are expected to contain water for a

significant portion of the dry season after an average wet season. Site photos and site descriptions for all sites

surveyed can be found in Appendix J. Sites downstream appeared to be in better condition than those upstream or

adjacent to URPA, mainly due to:

Greater diversity in substrate types, including cobbles.

Lower erosion and deposition of fine materials.

More diverse range of habitat types available.

Less water infrastructure (such as weirs and culverts).

GDE Sites

Billabong

Dry

Weir

Wet

ML1109

Ponds

Pits

Dams


Upper McKinlay River Groundwater Dependent Ecosystem Characterisation: Sites visited and assessed in detail

Figure 14-1


Upon review, the Australian GDE Atlas did not predict any potential GDEs in the upper McKinlay River, however,

permanent surface water is likely due to groundwater intersection of the river bed and/or resulting from groundwater

discharge was observed during the 2019 field survey. The pools were sparsely distributed across the upper McKinlay

River.

Three areas were identified as containing permanent surface water (Appendix J, Figure 14-2):

A billabong (MRBILL01) to the south-east of the project has historically held water through the dry season

when other surface waters have contracted. A weir (MRWEIR) is constructed on the McKinlay River adjacent

to the billabong which also holds water for the majority of the dry season, but does reduce significantly in

volume in years where wet season rainfall is below average. The billabong and weir are located between

surface water monitoring points URSW03 and URSW09.

A pool (MRWET08) is located west and down-gradient of the western waste rock dump. It is unclear if the

pool is a naturally occurring feature or the result of road and rail infrastructure built directly downstream and

seepage from the North-west waste rock dump (WRD). In any case, the pool is well established and provides

dry season refuge for terrestrial and aquatic fauna, and has an intact riparian zone. Water quality in the pool

is poor compared with other permanent surface water, but instream habitat quality is good. The aquatic

ecosystem in the pool is assumed to be somewhat impaired by water quality. The site is located between

surface water monitoring points URSW03 and URSW04.

Two pools (MRWET12 and MRWET13) are located downstream of the URPA. The pools are lined by

continuous riparian vegetation, and are considered to have very good quality instream habitat. Water quality

in the pools did not suggest any impairment to aquatic fauna. These two pools are important features in the

landscape as they represent both good quality habitat and water quality. The cover of dense Pandanus

groves in these locations also represent a unique aquatic habitat type not found at other permanent pools.

The pools are located between surface water monitoring points URSW10 and URSW08.

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14.2.2 AQUATIC ECOSYSTEM CHARACTERISATION

Fauna and Macroinvertebrates

Saltwater and freshwater crocodiles were observed in permanent pools, including juvenile freshwater crocodiles

indicating that nesting is likely to be occurring. Mertens Water Monitors were not observed.

Remote cameras were left in place for ten days at five sites. Summary statistics are presented below in Table 14-1,

and a full list of species recorded at each site can be found in Appendix J. A single species listed as threatened was

recorded upstream of URPA (Partridge Pigeon, MRWET01). Saltwater Crocodiles (EPBC Migratory) were observed at

two sites, and although seen during surveys, no Freshwater Crocodiles were captured on any camera. The lowest

number of species were recorded downstream of URPA at MRWET12, and the highest was upstream of URPA at

MRWET01. Feral pigs, donkeys and buffalo were observed, and evidence of hard-hoofed animals accessing permanent

water along the entirety of the area surveyed was recorded.

TABLE 14-1 SUMMARY STATISTICS FOR REMOTE CAMERA TRAPPING UNDERTAKEN SEPTEMBER 2019

Summary Statistic Camera 1 Camera 2 Camera 3 Camera 4 Camera 5

Total Species Count 23 18 18 10 19

Native 18 15 16 8 19

Exotic 5 3 2 2 0

NT listed 1 0 0 0 0

EPBC threatened 1 0 0 0 0

EPBC migratory 0 1 1 0 0

Macroinvertebrate and fish sampling was not undertaken during survey. Due to the likely presence of estuarine

crocodiles, these methods of sampling are difficult to undertake safely in the late dry season, when fauna is

concentrated in isolated pools. Although fish and macroinvertebrates were not sampled, both fauna communities

were observed at the larger permanent pools.

In lieu of macroinvertebrate data, a review of macroinvertebrate data collected in the early dry season 2011 to 2019

was conducted (Appendix J), to assist with characterisation of the aquatic ecosystems of the upper McKinlay River.

Although this data is not temporally representative of the community present during the late dry season, it provides

an indication of what taxa may remain in isolated pools through the dry season, and helps to understand the health of

the aquatic ecosystems of the river.

Macroinvertebrates show high inter-annual variability in community composition, regardless of their position relative

to the URPA. This is a typical feature of intermittent streams where habitat availability is considered to be the

influential factor in community composition. The in-situ quality of habitat was found to be high, with a range of

microhabitats and substrate types available, especially downstream of the URPA.

Riparian Vegetation

Riparian vegetation was found to be growing vigorously and without dieback, despite the below average rainfall for

the region in 2018/19, and suspected reductions in groundwater availability in the 2019 dry season. The riparian zone

was highly concentrated at the edges of the River, signifying its reliance on wet season flows along with saturation of

the capillary fringe through groundwater discharge, along with hydraulic lift by deep roots accessing the shallow

aquifer.

Riparian vegetation did show changes in its composition based on location in the catchment. Upstream of the URPA,

very few Paperbark trees were found, and the majority of larger trees were Swamp Box (Lophostemon grandiflorus)

and Freshwater Mangrove (Barringtonia acutangula). Very few Pandanus (Pandanus spiralis) were found upstream,


only being located where surface water or damp earth was found. The substrate within the creek throughout this area

was more consolidated, with a low proportion of coarse material such as sand and pebbles compared with sites

downstream.

Adjacent to URPA there was a significant increase in available alluvial material (namely coarse to fine sand) and a

distinct change in the vegetation of the riparian zone. Adjacent and downstream of URPA, the dominant vegetation

type is Paperbark. The construction of a weir adjacent to the URPA during the late 1980s has allowed for a greater

amount of available surface water, including flooding of the surrounding area upstream of the weir. This flooding has

created alluvial deposition and the development of a dense paperbark swamp forest, which is at least 50 m wide on

either side of the channel. Trees are smaller but very dense in their growth pattern. Further downstream, paperbarks

continue to dominate the vegetation, but the riparian zone is much narrower, and individual trees were generally

larger.

Typically, all areas that contained surface water, moist substrate or subsurface water coincided with the growth of

Pandanus, with the exception of the swamp forest adjacent to the weir, which is a monoculture of Paperbark trees.

The McKinlay River represents the lowest natural point in the landscape, and so groundwater is close to the surface,

creating permanent surface and/or sub-surface water in incised areas of the river channel. Groundwater discharge

(including subsurface flow) plays an important role in the aquatic ecosystems of the upper McKinlay River by allowing

for the persistence of permanent pools throughout the dry season, and vigorous riparian vegetation. The permanent

pools provide food, water and cooling for terrestrial fauna, and nesting habitat for birds and reptiles in the riparian

zone.

The continuity and vigour of riparian vegetation also plays an important role in a number of aspects of these aquatic

ecosystems. Increased shading decreases water temperature and reduces evaporation potential during the dry

season. Additionally, roots, fallen branches and detritus provide structural habitat for aquatic fauna from many

trophic levels. Finally, riparian vegetation is integral in maintaining bank stability, reducing erosion of stream banks

and subsequent deposition of fine sediments in the stream bed, and reducing interstitial spaces (pore spaces between

coarse substrate types, such as gravel, pebbles and cobbles) considered highly important for the diversity of

macroinvertebrate communities. Therefore, riparian vegetation and surface water should be viewed as co-dependent,

and the impairment of one community is very likely to result in the impairment of the other.


14.3.1 RISK ASSESSMENT SUMMARY An assessment of the risks associated with potential project impacts has been completed and discussed in Chapter 10:

Risk Assessment.

There were two identified hazard associated with the aquatic ecosystem for the project, both rated as having a

medium risk as presented in Table 14-2. These potential events are discussed below.

TABLE 14-2 RISK ASSESSMENT – AQUATIC ECOSYSTEMS


Risk Level


(aquatic ecosystems). Medium


(groundwater dependent ecosystems incl. riparian vegetation). Medium


14.3.2 CHANGES TO HYDROLOGICAL PROCESSES

Groundwater modelling undertaken by GHD (Appendix H) has shown a localised area of drawdown surrounding the

underground mine. The impact of the modelled drawdown will be far less in both magnitude and duration than

previous mining operations i.e. complete dewatering of the Crosscourse pit, however there is expected to be a

decrease in availability of groundwater flow to discharge to the McKinlay River for groundwater dependent surface

water ecosystems and riparian vegetation.

Discharge of groundwater to the McKinlay River maintains the vigour of riparian vegetation, and standing water level

of isolated permanent pools in the dry season. The magnitude of change in groundwater discharge is an important

factor in assessing the potential impact to these ecosystems. The results of modelling by GHD (Appendix H) show that:

The greatest impacts related to groundwater availability will likely occur after mining has ceased; and

Although overall changes to the availability of groundwater to the McKinlay River is low (i.e. 3%), the

quantum of change varies spatially along different sections of the River, and is likely to be greatest in local

sections closest to underground mining.

Approximate percentage changes in availability of groundwater are presented below in Table 14-3. Values are

approximated, based on graphs presented by GHD (Appendix H). The impact of these changes on GDEs is discussed

below.

TABLE 14-3 REDUCTION IN GROUNDWATER AVAILABILITY IN EACH MINING PHASE (APPENDIX H)

Local Section of

McKinlay River

(Figure 14-1)

GDEs

Present

Mine Development

(2020 to 2021)

Mine Operation

(2021 to 2023)

Recovery

(2023 to 2028)

Post-Mining

(2028 onwards)

Upstream

Above URSW09

Riparian

vegetation 0% 0% 0 - 0.05% 0.05 - 0%

Upstream

URSW03 -

URSW09

Billabong 0 - 0.2% 0.2 - 0.95% 0.99 - 0.2% 0.2 - 0%

Adjacent

URSW04 -

URSW03

Riparian

vegetation 0 - 4% 4-12% 12 - 1% 1 - 0%

Adjacent

URSW04 -

URSW10

MRWET08

Riparian

vegetation

0 - 3% 3 - 15% 17 - 3% 3 - 0%

Downstream

URSW08

Riparian

vegetation 0 - 0.1% 0.1 - 1.7% 2.1 - 1.2% 1.2 - 0%

Downstream

Below URSW08

MRWET12

MRWET13

Riparian

vegetation

0% 0% 0% 0%

Upstream of the project

Groundwater modelling indicates little change in availability of groundwater upstream of the project (Appendix H).

Areas including the weir and billabong (URSW03 to URSW09, Figure 14-2) and the headwaters of the McKinlay River

(above URSW09) show maximum groundwater availability losses of <1% and <0.1% respectively. These changes are

not expected to have an impact on riparian vegetation health upstream of URSW03, or on the water level within the

billabong.


Adjacent Areas

Downstream of the weir (URSW03 to URSW04, Figure 14-2) comprises permanent pool MRWET08. Groundwater

modelling has predicted a reduction in groundwater availability which begins during mine development and increases

steadily, peaking at 12% loss at the cessation of mining, then declining gradually over the recovery period, returning to

pre-mining levels by the end of 2027. This change in groundwater availability is not expected to significantly impact on

surface water availability at MRWET08. Riparian vegetation located upstream of MRWET08 may be impacted by

changes to groundwater availability, but this is not expected to result in long-term impact, i.e. previous dewatering of

Crosscourse pit is likely to have had a greater impact on groundwater availability for riparian vegetation, and although

that impact has not been measured, the presence of large trees in that area now indicates that trees have survived

dry seasons with limited access to subsurface moisture. This indicates the resilience of the riparian vegetation despite

some level of groundwater dependency.

The section between URSW04 and URSW10 contained a number of very shallow surface water pools (assumed to be

the remaining water from overland flow) that were drying rapidly when surveys were conducted in late August 2019

(Appendix J). A reduction of groundwater availability in this section of river will occur from mine development,

increasing over the following three years to a peak of 17% loss at the cessation of mining. This loss in available

groundwater then declines through the recovery period, eventually returning to a pre-mining state around a decade

after mining has ceased (Appendix H). As there is no permanent surface water in this section of the river, there are no

anticipated impacts on aquatic ecosystems. However, a reduction in available groundwater may shorten the time

period that surface water is available, i.e. where groundwater availability is reduced, riparian vegetation is likely to

utilise available surface moisture, thus reducing the duration that surface water is present.

However the rate of decline of surface water availability is not considered likely to increase such that natural

processes (such as egg laying, burrowing, aestivation, etc) would be impaired. As these pools dry naturally, mortality

of fish and invertebrates due to drying would not be considered an impact as a result of changes to groundwater

availability.

Given that water moves down-gradient along the McKinlay River below the surface of the riverbed, a reduction in

groundwater availability in the section upstream i.e. URSW03 to URSW04, may impact cumulatively on groundwater

available for riparian vegetation in the section between URSW04 and URSW10. However as previously stated, large

trees have survived a greater drawdown impact as a result of historical dewatering of the Crosscourse pit. It is

therefore not likely that groundwater dependent riparian vegetation will be impaired as a result of this project,

beyond their ability to recover, given groundwater availability increases again towards pre-mining levels over time.

Downstream of the project

The section of the McKinlay River between URSW08 and URSW10 comprises two isolated pools (MRWET12 and

MRWET13) which are considered to be permanent and maintained through the dry season by groundwater discharge.

The loss of groundwater availability in this section is predicted to be low compared with upstream sections, peaking at

just above 2% loss after mining has ceased, and returning to pre-mining levels after ten years. As mentioned above,

the cumulative loss of groundwater availability upstream is likely to impact on areas down-gradient of those losses.

Due to the location of permanent pools close to URSW10, and given that groundwater availability upstream is

impacted, there is likely to be some loss in recharge to these pools by groundwater. It should be noted however, that

these pools significantly decreased in volume in 2015, when dewatering was not taking place (Appendix J), suggesting

that the pools may recede naturally due to climatic factors. The loss of available groundwater from upstream sources

may therefore exacerbate any natural decline in surface water (should it take place), however there is almost no loss

predicted from groundwater drawdown directly at the pools.

The section below URSW08 is not predicted to experience any loss in groundwater availability as a result of the

project. Decreased groundwater flow from upstream sections is not likely to impact on riparian vegetation or

permanent water, as the section directly upstream has very low predicted changes in available groundwater. It is

therefore considered that there will be no impacts to riparian vegetation or aquatic ecosystem health in the McKinlay

River downstream of the study area.


Level of Impact from Groundwater Drawdown

The aquatic community present within permanent pools on the upper McKinlay River is likely to be made up of taxa

tolerant of conditions encountered in the late dry season, conditions associated with a reduction in surface water

volume such as lower dissolved oxygen, concentration of salts and increased temperature. Should any pool experience

reduction in surface water volume as a result of lowered groundwater availability, stress on those taxa is not likely to

be beyond natural processes that occur in the environment.

A reduction in surface water volume also results in reductions in available habitat, space and substrate, the results of

which are likely to alter the assemblage of taxa within isolated pools. Again, this is not atypical of ephemeral pools,

whose aquatic communities experience these conditions annually. Appendix J includes multiple lines of evidence of

natural variability in the aquatic environment, including inter-annual variations in rainfall, water availability and

macroinvertebrate community composition. Antecedent wet season conditions are likely to be the prominent driver

of aquatic community assemblages (Appendix J). It is therefore more likely that annual variation in wet season rainfall

will have a greater influence on the aquatic ecology of permanent pools than a small loss in surface water recharge

during the dry season from groundwater.

When lower than average wet season rainfall is recorded, permanent pools maintained by groundwater become

particularly important, where dry pools cannot provide refugial habitat. This is particularly the case for fish, which

cannot migrate to other areas when connectivity is lost, and (for most species) that cannot survive without surface

water. Although there is likely to be some reduction in surface water availability from groundwater migration and

availability downstream of the URPA as a result of project dewatering, it is not likely to be the cause of drying of any

permanent pool mapped in the upper McKinlay River. The two identified pools downstream of the URPA are likely to

be important refugial habitat during the dry season, and provide unique habitat compared with other permanent

pools. Their persistence through the dry season due to groundwater availability and antecedent wet season rainfall

may naturally fluctuate, but a short-term reduction in available water is not likely to result in a long-term impact to

the aquatic community or riparian vegetation health at these pools.

It is possible that Mertens Water Monitors are present, albeit in very low densities, though they were not observed

during survey or camera trapping in August 2019. Permanent water with appropriate bank characteristics for nesting

is critical to the persistence of Mertens Water Monitors, and these conditions have been identified at all permanent

pools within the upper McKinlay River. Reduction in surface water volume at isolated pools may reduce food

availability and increase risk of predation, yet a greater risk for the species is the drying of pools. Should they be

inhabiting pools in the downstream sections (MRWET12 and MRWET13), the proximity of permanent water upstream

(MRWET08 and MRBILL01) should allow for their migration to these areas, if pools downstream reduce in volume

significantly.

In each section of the river, losses in groundwater availability are low, yet their cumulative impact on subsurface flow

along the upper McKinlay River may impact on permanent surface water immediately downstream of the mining lease

boundary. Losses are not considered likely to result in the drying of these pools, but may reduce their volume,

especially towards the end of the dry season when evaporation is high. In years of low rainfall, isolated permanent

pools are especially important as they provide refuge for aquatic flora and fauna that propagate the river during the

wet season. As rainfall varies annually, it is difficult to predict if these conditions will occur during the life of the

project. The risk has been set at Medium, given the cumulative impact and a low rainfall scenario.

Ongoing monitoring of groundwater and surface water levels will be crucial in setting (and responding to) adaptive

management strategies, if required, to maintain the aquatic ecosystems of perennial surface water in the upper

McKinlay River during the project and at, and beyond, closure.

Although riparian vegetation may have reduced access to groundwater when peak losses are expected (end of

mining), the losses over the life of the project are low, and much lower than those that would have occurred as a

result of historical dewatering practices. The existence of vegetation that would have been present during that time

period, which is alive and growing vigorously (Appendix J) suggests a low likelihood of the project having a significant

impact on the health of riparian vegetation.


14.3.3 CHANGES TO WATER QUALITY

The results of groundwater modelling (Appendix H) where the project maintains a steady state water level in

Crosscourse pit by discharging treated water under a Waste Discharge Licence (WDL) is designed to reduce the

potential for groundwater seepage and poor quality water migration to the McKinlay River. Under this scenario, the

likelihood of poor quality water reaching the McKinlay River during mining is very low. Appendix I does note that

seepage of poor quality water from Dam B will reach the McKinlay River after four years, but any pollutants are likely

to be dispersed by sediments and diluted by baseflow and surface water flows.

When mining ceases in 2022, and groundwater discharge increases back to pre-mining volumes, seepage in Dam B will

reduce to pre-mining levels, and therefore will have negligible ongoing impact on water quality in the McKinlay River.


Whilst it is not considered that the project will impact significantly on aquatic ecosystems, it is acknowledged that

interactions between surface and groundwater are complex, and prevailing climate conditions cannot be confidently

predicted. Therefore, ongoing monitoring will be an effective tool to track the extent of groundwater drawdown, and

the impact on surface and groundwater flows, and any corresponding impact on the aquatic ecosystems during the

life of the mine and the recovery period. A monitoring plan will be a component of the URPA Site Water Management

Plan.

Beyond on-site water management that is proposed (including an application for a WDL) and ongoing monitoring,

mitigation measures are not currently required to manage any impacts associated with the project. In the unlikely

event that mitigation is required, the large water stores on site could be considered as temporary mitigation for

example as a one-off, out of seasons flush discharge to the McKinlay River (pending water quality results), or targeted

irrigation along the McKinlay River, e.g. at MRWET12 and MRWET13.


The results of groundwater modelling by GHD (2019) (refer Appendix H) predict very small changes in groundwater

availability during the mine establishment phase (2021) and so sufficient time exists to further characterise the

aquatic communities.

A Water Management Plan will include the development of trigger values for groundwater drawdown. High frequency

monitoring of groundwater levels (Chapter 12) between URPA and the river will also occur. The installation of a flow

gauge on the upper McKinlay River will assist in interpreting the results of annual biological monitoring, as taxa

adapted to intermittent waterways are highly influenced by wet season flow conditions.

Surface water quality sampling of isolated pools through the dry season will generate additional baseline data and

help to determine if water quality impacts associated with groundwater are becoming prevalent in the permanent

surface waters downstream of URPA.

14.5.1 ADDITIONAL CHARACTERISATION OF THE FAUNA COMMUNITY

Macroinvertebrate and fish sampling programs in the late dry season as per NT AusRivAS sampling protocols carry

significant safety risks, given the presence of estuarine crocodiles. Deployment of ‘artificial substrates’ into permanent

pools significantly reduces the risks. Using standardised, replicated artificial substrates in all permanent pools will

enable baseline macroinvertebrate data to be collected annually, to characterise macroinvertebrate communities

spatially and temporally, in permanent pools along the McKinlay River. This methodology has been used successfully

to characterise macroinvertebrate communities in waterbodies across Australia, including tropical intermittent

waterways. This will be an important tool in monitoring impacts to surface water ecosystems, particularly prior to the

peak of groundwater drawdown at the end of mining.

The late dry season aquatic ecosystem monitoring at permanent surface water sites will be in addition to the

continuation of the current, annual, early dry season macroinvertebrate monitoring program using NT AusRivAS


protocols. This program will provide insight into how the aquatic ecosystems recover after wet season rainfall. An

additional site, at the site of pools MRWET12 and MRWET13 will be implemented.

It is acknowledged that some time has passed since fish surveys were completed and fish communities have the

capacity to change over time, especially where very few barriers to wet season movement exist. An early dry season

fish survey using active methods (such as backpack electrofishing) will be implemented to further characterise the fish

community, and understand changes over time in the McKinlay River. The deployment of cameras to observe the fish

community in permanent pools in the late dry season will be used, where water clarity allows, to further characterise

the fish community in the permanent pools on the McKinlay River.

Remote fauna cameras were deployed for ten days at all sites during August 2019. Deployment of cameras as a

follow-up survey for an extended period, preferably three months, will allow for the capture of rarer species. The

timing of camera deployment will be altered to earlier in the dry season, when water monitors are more likely to be

mobile.

Surface water ecosystems are likely to show indications of stress related to groundwater impacts long before the

associated riparian vegetation. A pre-mining monitoring survey prior to the start of mining will add to baseline data

used to measure the impact (if any) at permanent pools as a result of drawdown. The use of methods for bio-

condition assessment (Appendix J) will allow for repeat monitoring to take place.

14.5.2 IDENTIFY REFERENCE LOCATIONS The sparse distribution of permanent surface water on the upper McKinlay River for 20 km downstream of the URPA

denotes that there are not likely to have been reference locations included in this survey (pending results of

groundwater modelling). Baseline monitoring of permanent pools outside of the modelled impact area will be used, in

combination with those in close proximity to the project, to quantify impacts of groundwater drawdown (if required).

Reference locations may include the billabong (MRBILL01), which is not predicted to experience any change in

groundwater availability, and provides a regionally appropriate control point.


The relatively short term duration of the project, and the apparent resilience of the aquatic ecosystems and riparian

vegetation community of the upper McKinlay River indicates there is little probability of residual impacts beyond the

recovery (post-closure) phase of the project.

Low magnitude, short-term changes to habitat availability, water availability and connectivity within the upper

McKinlay River as a result of operational dewatering and subsequent changes in groundwater discharge are expected.

The taxa present in permanent pools are adapted to such conditions. This is especially true for intermittent headwater

streams, where antecedent wet season conditions can have a greater impact on taxa present in permanent pools in

the dry season.

The project is not expected to result in any significant changes to the assemblages of aquatic biota in the upper

McKinlay River. Ongoing monitoring of the receiving environment, as described above, will be the most effective tool

in the management of potential aquatic ecosystem impacts.


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KLG, October 2019.

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Study, September 2019, provided in Appendix H.

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https://www.waterquality.gov.au/anz-guidelines


Higgins, P.J., and Davies, S., 1996. Handbook of Australian, New Zealand and Antarctic Birds. Volume 3. Snipe to

Pigeons. Oxford University Press, Melbourne.

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Orogen, Episodes, Vol 35 (1) pp. 264 to 272.

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Geneva Switzerland.

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February 2018.

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Natural Resources, Darwin NT.

NSR Consultants, 1993. The Shell Company of Australia Limited, Union Reefs Project, Draft Environmental Impact

Statement, Hawthorn, Victoria.

NT NRM Report Generated from NT Infonet, http://www.infonet.org.au 13/09/2019.

Ward, S., Woinarski, J., Griffiths, T. & McKay, L., 2006. Threatened Species of the Northern Territory: Merten’s Water

Monitor, Department of Environment and Natural Resources.

Woinarski, J., 2004. The forest fauna of the Northern Territory: knowledge, conservation and management. In

Conservation of Australia’s Forest Fauna (second edition) (ed. D. Lunney). pp. 36 to 55. Royal Zoological Society of

New South Wales, Sydney.

Woinarski, J., 2006. Threatened Species of the Northern Territory: Partridge Pigeon, Department of Environment and

Natural Resources.

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http://www.infonet.org.au/

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