Heritage Minerals has a unique approach to solving the economic barriers to treating low-grade tailings. A combination of the worlds best technology and many years of operational experience can turn around projects that are otherwise not feasible. Heritage Minerals designs and implements innovative solutions for technically tricky projects. They are also a environmentally and socially responsible problem solver.
Mount Morgan Mine Upper Mundic Gully TSF EA Amendment Supporting Information Report
Prepared for
Heritage Minerals
Date
29 May 2026
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Mount Morgan Mine Upper Mundic Gully TSF EA Amendment Supporting Information Report
Prepared for: Heritage Minerals
Date: 29 May 2026
Project number: 25B061
Page iii
Project details
25B061
Project number:
Mount Morgan Mine Upper Mundic Gully TSF EA Amendment Supporting Information Report
Document title:
V1-2
Revision:
29 May 2026
Date:
Heritage Minerals
Client:
Lachlan McQuire
Project manager:
Lachlan McQuire
Author:
SGME’s details
SGME Pty Limited
Legal name:
Unit 3, 37 McDonald Road, Windsor, Qld 4030
Address:
621 989 866
65 621 989 866
ACN:
ABN:
Timothy Rohde
Representative:
trohde@sgme.au
+61 7 3148 6288
Email:
Phone:
This Report is provided to you the abovenamed Client (Client, you or your) in respect of the above Project and in accordance with our Standard Terms. Capitalised terms that are not specifically defined in this Report have the meanings given to them in our Standard Terms. © Copyright 2025 SGME Pty Limited. The concepts and information contained in this document are the property of SGME Pty Limited. Use or copying of this document in whole or in part without the written permission of SGME Pty Limited constitutes an infringement of copyright. Data / confidentiality: This report contains information and data that is confidential and / or subject to restrictions in respect of Intellectual Property Rights (IP). Readers agree to be bound by confidentiality and IP provisions contained in our Standard Terms and the obligation not to cause any damage or hardship to SGME Pty Limited or the Client. Document history and status
Revision
Date
Description
By
Review
Approved
V1-1
21/04/26
Draft
Various
L McQuire
V1-2
29/05/26 Final
Various
L McQuire
L McQuire
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Contents
1.
Introduction
1
1.1
Purpose
1 1
1.2 1.3 1.4 1.5 1.6
Project Location
Environmental Authority Holder Environmentally Relevant Holder
3 3 3 6
Mining Tenements
Real Property Descriptions
2.
Overview of Proposed EA Amendments
11
2.1
Proposed Amendments
11 11
2.1.1
Proposed Amendment 1: Authorise Upper Mundic Gully TSF Location
2.1.2 2.1.3
Proposed Amendment 2: Update Table A1 and Figure 1
14 14 17 17 18 19 19 19
Proposed Amendment 3: Fix Minor Erroneous Issues in the EA
2.2
Amendment Justification
2.2.1
Justification for Proposed Amendment 1 Justification for Proposed Amendment 2 Justification for Proposed Amendment 3
2.2.2 2.2.3
2.3
Proposed Conditioning
2.3.1
Conditions within the EA Tables within the EA Figures within the EA
2.3.2 2.3.3
25 33 35 39 40
2.4 2.5 2.6
Summary of Risks and Likely Magnitude of Impacts on Environmental Values
Assessment Level Decision
Content of Supporting Information
3.
Overall Project Description
42
3.1
Overall Project History
42 42 43 43 44 46 46 48 48 48
3.1.1
Handover to the State
3.1.2 3.1.3 3.1.4
Abandoned Mine Status
Past Reprocessing Endeavours
Phase 3 Agreement
3.2
Alternatives to the Amendments
3.2.1
Amendment #1 Amendment #2 Amendment #3
3.2.2 3.2.3
3.3
Standard Criteria Assessment
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4.
Upper Mundic Gully Environmental Value Description
51
4.1
Upper Mundic Gully Location and Catchment Description
51
4.2 4.3 4.4
Topography and Drainage
55 60
Ephemeral Dam Water Quality
Dam 8 Description and Environmental Values
61
5.
Proposed TSF
63
5.1
Basis of Design
68 69
5.2 5.3
Ancillary Infrastructure
Dam Break and Consequence Category Assessment
71 71
5.3.1
Failure mechanisms
5.3.2
Consequence Category Assessment
72 76
5.4 5.5 5.6 5.7 5.8 5.9
Tailings and Water Management
Deposition Volumes
77
Decant Pond
80 80 80 84 85 85 88 90 92 92 94 96 97 98
Liner Requirements
Embankment Design and Geotechnical Considerations
Seepage Management
5.9.1
Seepage plan limitations
5.9.2
Seepage management Stage 1
5.10
Tunnel Management
5.11
Flood Potential
5.12 5.13 5.14
Clean Water Diversion
Potential impacts of future deposition expansion
Process Plant Flow Sheet
5.14.1
Tailings Geochemical Characterisation
5.15 5.16
Spillway design
Compliance with existing EA conditions
6.
Environmental Setting and Considerations
99
6.1
Climate Geology
99 101
6.2 6.3 6.4
Soils
103 104 104 104 106 109
Bioregion and subregion
6.4.1
Land Zones
6.5 6.6
Hydrology
Site Hydrogeology
6.6.1
Recent investigations
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6.6.2 6.6.3 6.6.4 6.6.5 6.6.6 6.6.7 6.6.8 6.6.9
Upper Mundic Gully Hydrogeological Conceptualisation
111
Hydraulic aquifer properties
112 112 113 113
Site Wide Groundwater Quality
Existing Groundwater Model
Site Wide Conceptual Site Model
Site Wide Groundwater Recharge and Discharge
123 124 129 130 130 132 133 138 140
Proposed monitoring bore installation
Proposed updates to groundwater model
6.7
Ecology
6.7.1
Desktop Assessment
6.7.2 6.7.3 6.7.4 6.7.5
Regional Ecosystems Field Verified
Ecological Surveys
Likelihood of Occurrence Analysis
Groundwater Dependant Ecosystems
7.
Potential Environmental Impacts and Management
144
7.1
Existing Management Practices
144 145 146 146 148 149 150 150 150
7.2 7.3
Ancillary Infrastructure
Surface Water and Wetlands
7.3.1
Values
7.3.2 7.3.3
Impact Assessment
Management Practices
7.4
Groundwater
7.4.1
Values
7.4.2 7.4.3 Land
Impact Assessment
Management Practices
151
7.5
153 153 154 158
7.5.1
Values
7.5.2 7.5.3 7.5.4 7.5.5
TSF Rehabilitation
Ancillary Infrastructure Rehabilitation
Impact Assessment
161 161
Management Practices
7.6
Noise and Vibration
162 162 163 163 164
7.6.1
Values
7.6.2 7.6.3
Impact assessment
Management Practices
7.7
Air Quality
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7.7.1
Values
164 164 165 165 165 166 166 166 166 167 168 168 195 196 196 197 197 198 198
7.7.2 7.7.3
Impact Assessment
Management Practices
7.8
Social and Community
7.8.1
Values
7.8.2 7.8.3
Impact Assessment
Management Practices
7.9
Cultural Heritage
7.9.1
Indigenous Heritage
7.9.2
Non-Indigenous Heritage
7.10
Nature Conservation
7.10.1
Significant Residual Impact Assessment
7.10.2 Management plans for impact to MSES species
7.11
Waste Management
7.11.1
Values
7.11.2 7.11.3
Impact Assessment
Management Practices
7.12
Greenhouse Gas Assessment
7.12.1
Values
7.12.2 Impact Assessment
200
7.12.3 Management Practices
202
8.
Environmental Risk Assessment
203
8.1
Overview
203 204 205 206
8.2 8.3 8.4
Risk Identification
Risk Analysis and Evaluation
Risk Assessment Results
9.
Forward Works Plan
213
10.
References
216
11.
Abbreviations
218
Tables Table 1
Environmental Authority Holder
3 3 4 6
Table 2 Table 3 Table 4 Table 5 Table 6
Current Authorised ERAs and Resource Activities
Mining Tenements
Underlying landholders on the relevant Mining Lease Proposed modifications and new conditions within the EA
20 25
Proposed Table A1 – Authorised mining activities and locations Replacement
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Table 7 Table 8
Proposed Table W1 – Groundwater monitoring locations and frequency
28 29 30 32 32 33 36 39 40 46 48 60
Proposed Table F1 Replacement
Table 9. Proposed Table F2 Replacement Table 10. Proposed Table H1 Replacement Table 11. Proposed Table H2 Replacement Table 12. Proposed Table H3 Replacement
Table 13. Environmental Values Risk Assessment Summary
Table 14. Minor amendment criteria Table 15. Table of Requirements
Table 16. Processed Tailings Disposal Options Assessment
Table 17. Standard Criteria Assessment Table 18. Ephemeral Dam Water Quality
Table 19 Dam 8 Water Quality
61
Table 20. Dam 8 Groundwater Records Table 21. Design Criteria and basis of design
62 68
Table 22. Summary of results for consequence category assessment
71 71
Table 23. Summary of Failure Mechanisms Assessed
Table 24. PAR estimates (ANCOLD) Table 25. PAR Estimates (DETSI)
73 73 73 74 74 75 76 77
Table 26. Consequence Category Assessment for Upper Mundic Gully TSF Table 27. Consequence Category Assessment - DETSI (Dam Break scenario) Table 28. Consequence Category Assessment – ANCOLD (Environmental Spill) Table 29. Consequence Category Assessment – ANCOLD (Environmental Spill) Table 30. Consequence Category Assessment– DETSI (Failure to contain – seepage)
Table 31. Estimated Tailings Storage
Table 32. Management measures to prevent ARD mobilisation Table 33. Tailings properties compared to Relevant Guidelines 97 Table 34. Mean, Maximum and Minimum Temperature for the Rockhampton Airport (BOM) 99 Table 35. Soil Type Summary 103 Table 36. Land Zones and associated geologies occurring in the project area 104 Table 37. Hydraulic parameters from existing hydrogeological studies 112 Table 38. Conceptual Source Pathway Receptors Current Conditions 116 Table 39. Conceptual Source Pathway Receptors Post Mining 118 Table 40. Simulated Groundwater Flows by Sub-Catchment 120 Table 41. Potential Scenarios for Groundwater/ Seepage Flows 121 Table 42. Proposed Monitoring Bores 127 Table 43. Desktop assessment information sources 131 Table 44. Descriptions for Regional Ecosystems Ground-truthed within the Project area 132 Table 45. Ecological Surveys 133 Table 46. Restricted matters and WoNs occurring in the project area 137 Table 47. Summary of likelihood of occurrence of MSES 138 Table 48. Subsequent species assessment 139 Table 49. Ancillary Infrastructure and Environmental Value 145 Table 50. Ancillary Infrastructure Rehabilitation 160 Table 51. Project Stakeholders 165 Table 52. Summary of SRI assessment results 169 Table 53. SRI assessment - Cycas megacarpa 171 Table 54. SRI assessment - Koala ( Phascolarctos cinereus ) 174 Table 55. SRI assessment - ghost bat ( Macroderma gigas ) 177 Table 56. SRI assessment - greater glider ( Petauroides volans ) 180 Table 57. SRI assessment - yellow-bellied glider ( Petaurus australis australis ) 182 Table 58. SRI assessment - white-throated needletail ( Hirundapus caudacutus ) 185 Table 59. SRI assessment - Grevillea hockingsii 187 82
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Table 60. SRI assessment - short-beaked echidna ( Tachyglossus aculeatus ) Table 61. SRI assessment – Northern Quoll ( Dasyurus hallucatus )
190 193 195 198 199 201 202 205 206 206 207
Table 62. SRI assessment - regulated vegetation – Category B
Table 63. DETSI Requirement Table 64. GHG Emission Inventory
Table 65. Estimated Scope 1 and 2 Emissions
Table 66. Management Practices to mitigate emissions
Table 67. Likelihood of Exposure of Hazard Table 68. Consequence Classification Table 69. Risk Level Classification Matrix
Table 70. Risk Assessment Results Table 71. Forward Works Plan
213
Figures Figure 1. Site Locality Figure 2. Mining Leases
2 5
Figure 3. Underlying Lots within Mining Lease Figure 4. Upper Mundic Gully TSF extent
10 13 14 15 16 17
Figure 5. Sandstone Gully TSF Storage Capacity (Golder, 2020)
Figure 6. Pipe Corridor Extent
Figure 7. Extract from 2019 PoO (Source AARC, 2019)
Figure 8. Extract from PoO 2017 (AARC)
Figure 9. Replacement Schedule I, Figure 1 in the EA
34 52 52 52 53 54 56 57 58 59 64 65 66 67 70 78 78 79 79 83 84
Figure 10. Waste Rock Disposal in Upper Mundic Gully from West to East (taken 1942) Figure 11. Waste Rock Disposal in Upper Mundic Gully Plan View (photograph taken 1953) Figure 12. Western Dump within Upper Mundic Gully from the south looking north Figure 13. Western Dump within Upper Mundic viewed from the base looking east
Figure 14. Western Dump footprint
Figure 15. Mount Morgan Drainage Network Current Figure 16. Mount Morgan Drainage Network Pre-Mining Figure 17. Sub Catchments occurring across Mount Morgan Mine Figure 18. Topography within Mount Morgan Mining Leases (QLD Globe)
Figure 19. General Arrangement Plan
Figure 20. Plan and Longitudinal Section Stage 1 Figure 21. Plan and Longitudinal Section Stage 2 Figure 22. Typical Embankment Section Figure 23. Ancillary Infrastructure Map Figure 24. Stage 1 Tailings Beach Surface Figure 25. Stage 1 Stage-Storage Curve Figure 26. Stage 2 Tailings Beach Surface Figure 27. Stage 2 Stage-Storage Curve Figure 28. Embankment Longitudinal Section Figure 29. Proposed seepage management approach Figure 30. Proposed Tunnel Portal Plug Design Section
89 Figure 31. Overtopping and piping failure configurations (US Army Corps of engineers, 2014) 90 Figure 32. Stage 1 Sunny Day Failure Maximum Depth (m) 91 Figure 33. Stage 2 Sunny Day Failure Maximum Depth (m) 92 Figure 34. Potential interaction of the Upper Mundic Gully TSF failure discharges with the proposed Sandstone Gully TSF embankment 93 Figure 35. Process Plant Flow Diagram 95 Figure 36. Mean maximum and minimum temperature at Rockhampton Aero (BOM) 99 Figure 37. Rockhampton Aero Mean Rainfall (BOM) 100
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Figure 38. Rockhampton Aero 9am and 3pm Wind Rose (BOM 2023)
100 102 103 107 108 110 115 124
Figure 39. Geological Map (WSP)
Figure 40. Soil Types Mount Morgan Area (ASRIS Level 4 Australian Soil Classification) Figure 41. Groundwater Levels and Flow Contours (Robertson Geoconsultants 2010)
Figure 42. Location of Groundwater Monitoring Bores (GHD, 2024) Figure 43. Groundwater bores installed December 2025 Figure 44. Upper Mundic Gully Conceptual Site Model Figure 45. Recharge Zones Assumed for model calibration
Figure 46. Proposed Drilling Locations 126 Figure 47. Population survey and mapped habitat for Grevillea hockingsii within TSF footprint 135 Figure 48. Population survey and mapped habitat for Cycas megacarpa within TSF footprint 136 Figure 49. Mapped potential GDEs and registered groundwater users within 10km of TSF 142 Figure 50. Sensitive Receptor Map (GHD) 162 Figure 51. Cultural Heritage Features 167 Figure 52. Camera Trap Locations 192 Figure 53. Waste and Resource Management Hierarchy 197 Figure 54. Estimated Scope 1 and 2 Emissions by Year 200 Figure 55. GHG Abatement Hierarchy (Source: DETSI, 2025) 202 Figure 56. ISO 31000: 2018 Risk management process 204
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Project number: 25B061
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1. Introduction
1.1 Purpose The purpose of this document is to describe the existing environmental values and assess the potential environmental impacts that may arise from the proposed amendments. The proposed amendments relate to: ∕ Authorise the location of the Upper Mundic Gully TSF by including it as a mine feature in the EA; ∕ Update Table A1, and associated Schedule I Figure 1, to address to be determined (TBDs) associated with the pipe corridor and exploration mine features; and ∕ Fix minor erroneous issues in the EA that impact on the processed tailings volumes for discharge into Sandstone Gully TSF. The Queensland Environmental Regulator Regulatory Strategy 2022-2027 articulates that a key focus area for DETSI is to “Regulate proportionate to risk”. To align with this focus area, this supporting information report provides a risk assessment that has been completed to identify potential impacts of the proposed amendments and appropriate mitigation measures. A summary of the risks and likely magnitude of impacts on environmental values is included in Section 2.4 whilst the full risk assessment is provided in Section 8. Throughout this document reference is made to the Upper Mundic Gully TSF (the project) and the Heritage Minerals Tailings Reprocessing (the overall project). 1.2 Project Location The Mount Morgan Mine is located near the town/location of Mount Morgan 38 kilometres south west of Rockhampton in Central Queensland. A site locality map is provided in Figure 1. The Mount Morgan Mine is largely bound to the east by the Dee River and bound to the north and west by undulating hills. Mount Morgan was founded as a gold mining town in 1882, with the Mount Morgan Mine located directly adjacent to the west. In addition to mining resources, the predominant land uses in the surrounding region is cattle grazing within native vegetation, with some areas of forestry and irrigated cropping. This region experiences a sub-tropical climate, with distinctive wet and dry seasons, with approximately 70 percent of rain fall during the wet season (between November and April). The Mount Morgan Mine is located alongside the Dee River, forming part of the Dee River Catchment. The catchment forms part of the larger Fitzroy River system within the Fitzroy River basin. The Dee River generally flows south to west into the Don River and Dawson River before reaching the Fitzroy River where it enters the ocean at Port Alma, downstream of Rockhampton.
Project number: 25B061
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Figure 1. Site Locality
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1.3 Environmental Authority Holder The Environmental Authority holder for the project is outlined in Table 1. The EA holder is a registered suitable operator for the purpose of carrying out an Environmentally Relevant Activity (ERA) under the EP Act. Table 1 Environmental Authority Holder
Name
ABN
Registered Address
Heritage Minerals Pty Ltd
61 633 121 954
Level 2, 267 St Georges Tce, Perth, WA, 6000
1.4 Environmentally Relevant Holder ERAs are prescribed activities with the potential to release emissions which may impact on the environment and surrounding land uses. ERAs and Resource Activities per Schedule 2 and Schedule 3 of the Environmental Protection Regulation 2008 (EP Reg) that are currently approved in the EA are listed in Table 2. There are no proposed amendments to other ERAs authorised under
the EA. Table 2
Current Authorised ERAs and Resource Activities
Reference
Description
ERAs 8 – Chemical storage
Chemical storage 2: Storing more than 500 cubic meters of chemicals of class C1 or Class C2 combustible liquids under AS 1940 or dangerous goods class 3 under subsection (1)(c) Mineral processing 2: Processing, in a year, the following quantities of mineral products, other than coke 2(b) more than 100,000t
31 – Mineral processing
Resources Activities 16 - Mining gold ore
Mining gold ore
17 – Mining copper ore
Mining copper ore
1.5 Mining Tenements The Mount Morgan Mine is the subject of 30 mining leases as described in Table 3 and displayed in Figure 2. Although Heritage Minerals is the holder of the Mining Leases (MLs) listed in Table 3, the site is managed by the Department of Natural Resources and Mines, Manufacturing and Regional and Rural Development (DNRMMRRD) through the Abandoned Mines Lands Program (AMLP). No other tenements exist over the site such as an EPM, EPC or Mineral Development License. As shown in Figure 4, the proposed Upper Mundic Gully TSF lies within ML5608 and ML5624. No change to any ML is necessary and no additional mining tenement would be required to accommodate the Upper Mundic Gully TSF.
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Table 3
Mining Tenements
Mining Lease
Permit Name
Holder
Expiry
Area (ha)
5589
Mickey Mouse
Heritage Minerals Pty Ltd
31 August 2025
82.56
5602
NA
Heritage Minerals Pty Ltd
31 August 2025
7.69
5608
Morgan 2
Heritage Minerals Pty Ltd
31 August 2025
121.40
5609
Morgan 3
Heritage Minerals Pty Ltd
31 August 2025
17.78
5612
NA
Heritage Minerals Pty Ltd
31 August 2025
19.42
Mount Morgan Mine
5613
Heritage Minerals Pty Ltd
31 August 2025
33.59
5614
NA
Heritage Minerals Pty Ltd
31 August 2025
3.16
5615
NA
Heritage Minerals Pty Ltd
31 August 2025
3.27
Sandstone Gully
5617
Heritage Minerals Pty Ltd
31 August 2025
2.90
5618
NA
Heritage Minerals Pty Ltd
31 August 2025
8.82
5619
NA
Heritage Minerals Pty Ltd
31 August 2025
8.98
5620
NA
Heritage Minerals Pty Ltd
31 August 2025
26.71
5621
NA
Heritage Minerals Pty Ltd
31 August 2025
6.33
5622
NA
Heritage Minerals Pty Ltd
31 August 2025
2.83
5623
NA
Heritage Minerals Pty Ltd
31 August 2025
14.48
5624
NA
Heritage Minerals Pty Ltd
31 August 2025
29.93
5625
NA
Heritage Minerals Pty Ltd
31 August 2025
21.45
5626
NA
Heritage Minerals Pty Ltd
31 August 2025
11.33
5627
NA
Heritage Minerals Pty Ltd
31 August 2025
4.43
5628
NA
Heritage Minerals Pty Ltd
31 August 2025
6.07
5633
Morgan 7
Heritage Minerals Pty Ltd
31 August 2025
14.21
5634
Morgan 6
Heritage Minerals Pty Ltd
31 August 2025
33.95
5635
Morgan No.8
Heritage Minerals Pty Ltd
31 August 2025
35.00
5648
Morgan 10
Heritage Minerals Pty Ltd
31 August 2025
2.02
5649
Morgan 9
Heritage Minerals Pty Ltd
31 August 2025
9.90
5658
Morgan 11
Heritage Minerals Pty Ltd
31 August 2025
12.53
5659
Morgan Number 12 Mt Morgan Number 13
Heritage Minerals Pty Ltd
31 August 2025
21.54
5660
Heritage Minerals Pty Ltd
31 August 2025
84.58
6692
NA
Heritage Minerals Pty Ltd
31 August 2025
16.14
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Figure 2. Mining Leases
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1.6 Real Property Descriptions The identification of all landholders within the mining leases across the project area are identified in Table 4. The various land parcels within the MLs are shown on Figure 3. For most of the lots where Heritage Minerals undertake mining activities, the State of Queensland through the DNRMMRRD is the underlying landholder. Table 4 Underlying landholders on the relevant Mining Lease
Tenement
Name
Lot on Plan
Registered Owners
Steven Charles Larson and Trudy Anne Larson Rockhampton Regional Council
ML5589
Mickey Mouse
Lot 107 on CP881492
Lot 203 on RN1556
Lot 1 on RP860374 Lot 1 on MPH10393 Lot 1 on MPH10396 Lot 1 on MPH10479 Lot 1 on MPH10729 Lot 1 on MPH10827 Lot 1 on MPH10850 Lot 1 on MPH10850 Lot 1 on MPH10966 Lot 1 on MPH11057 Lot 2 on MPH11057 Lot 1 on MPH11115 Lot 1 on MPH11441 Lot 1 on MPH11627 Lot 1 on MPH11642 Lot 1 on MPH11780 Lot 1 on MPH12202 Lot 1 on MPH25348 Lot 1 on MPH25461 Lot 2 on MPH25461 Lot 1 on MPH25473 Lot 1 on MPH25487 Lot 1 on MPH25494 Lot 90 on P42319 Lot 3 on USL42977 Lot 6 on USL42977 Lot 101 on SP139776 Lot 60 on USL42977 Lot 77 on USL42977 Lot 102 on USL42977 Lot 103 on USL42977 Lot 1 on MPH12108 Lot 2 on MPH25671
DNRMMRRD
ML5602
DNRMMRRD
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Tenement
Name
Lot on Plan
Registered Owners
Lot 101 on SP139776
DNRMMRRD
ML 5609
Morgan 3
Lot 101 on SP139776
DNRMMRRD
ML 5612
-
Lot 101 on SP139776
DNRMMRRD
ML 5613
Mount Morgan Mine
Lot 3 on RP601353
DNRMMRRD
Lot 1 on RP860374 Lot 3 on RP601353
ML 5614
-
Lot 1 on RP860374
DNRMMRRD
Lot 101 on SP139776
ML 5615
-
Lot 101 on SP139776
DNRMMRRD
ML 5616
Sandstone Gully
Lot 101 on SP139776
DNRMMRRD
ML 5617
-
Lot 101 on SP139776
DNRMMRRD
ML 5618
-
Lot 101 on SP139776
DNRMMRRD
ML 5619
-
Lot 203 on RN1556
DNRMMRRD
ML 5620
-
Lot 1 on MPH11067
Rockhampton Regional Council
Lot 2454 on MPH11067
DNRMMRRD
Lot 1 on MPH11169 Lot 2695 on MPH11180 Lot 2696 on MPH11180 Lot 3192 on MPH11410 Lot 3229 on MPH11497 Lot A on AP2444 Lot 3912 on MPH10386 Lot 5164 on MPH10386 Lot 1463 on MPH10760 Lot 2452 on MPH11067 Lot 3273 on MPH11435 Lot 3274 on MPH11435 Lot 3275 on MPH11435 Lot 3276 on MPH11435 Lot 3469 on MPH11435 Lot 1197 on MPH25518
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Tenement
Name
Lot on Plan
Registered Owners
Lot 1341 on MPH25518 Lot 1342 on MPH25518 Lot 17 on USL42984 Lot 118 on USL42984 Lot 101 on SP139776
ML 5621
-
Lot 101 on SP139776
DNRMMRRD
ML 5622
-
Lot 101 on SP139776
DNRMMRRD
ML 5623
-
Lot 101 on SP139776
DNRMMRRD
ML 5624
-
Lot 101 on SP139776
DNRMMRRD
ML 5625
-
Lot 101 on SP139776
DNRMMRRD
ML 5626
-
Lot 101 on SP139776
DNRMMRRD
ML 5627
-
Lot 101 on SP139776
DNRMMRRD
ML 5628
-
Lot 77 on USL42977
DNRMMRRD
Lot 103 on USL42977 Lot 107 on CP881492
ML 5633
Morgan 7
Lot 101 on SP139776
Steven Charles Larson and Trudy Anne Larson
Lot 107 on CP881492
DNRMMRRD
ML 5634
Morgan 6
Lot 101 on SP139776
Steven Charles Larson and Trudy Anne Larson
Lot 203 on RN1556
DNRMMRRD
ML 5635
Morgan No. 8
Lot 101 on SP139776
Rockhampton Regional Council
Lot 101 on SP139776
DNRMMRRD
ML 5648
Morgan 10
Lot 101 on SP139776
DNRMMRRD
ML 5649
Morgan 9
Lot 3 on RP601353
DNRMMRRD
Lot 2 on MPH11057 Lot 1 on MPH11057 Lot 60 on USL42977 Lot 63 on USL42977 Lot 64 on USL42977 Lot 65 on USL42977
Lot 66 on USL42977
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Tenement
Name
Lot on Plan
Registered Owners
Lot 67 on USL42977 Lot 68 on USL42977 Lot 69 on USL42977 Lot 101 on SP139776
ML 5658
Morgan 11
Lot 101 on SP139776
DNRMMRRD
ML 5659
Morgan Number 12
Lot 1 on RP860374
DNRMMRRD
Lot 3 on RP601353
DNRMMRRD
Lot 101 on SP139776 Lot 3 on RP601353
Lot 1 on RP860374
DNRMMRRD
Lot 101 on SP139776
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Figure 3. Underlying Lots within Mining Lease
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2. Overview of Proposed EA Amendments Applications to amend an EA must be made in accordance with s.224 and s.225 of the EP Act and meet the application requirements detailed in s.226. An application must also comply with s.226AA, s.226A, s.226B, s.227 and s.227AA to be considered ‘properly made’. The proposed amendments within this application intend to: ∕ Authorise the location of Upper Mundic Gully TSF by including it as a mine feature in the EA; ∕ Update Table A1, and associated Schedule I Figure 1, to address to be determined (TBDs) associated with the pipe corridor and exploration mine features; and ∕ Fix minor erroneous issues in the EA that impact on the processed tailings volumes for discharge into Sandstone Gully TSF.
2.1
Proposed Amendments
2.1.1 Proposed Amendment 1: Authorise Upper Mundic Gully TSF Location EA EPML00433013 currently authorises the disposal of processed tailings into the following locations: ∕ Up to 11.5 million cubic meters (Mm 3 ) into Sandstone Gully TSF; and ∕ Up to six million dry weight tonnes (6Mt) into Open Cut Pit (OCP). This EA amendment application seeks to authorise a new disturbance area to provide additional tailings storage in a facility known as Upper Mundic Gully TSF. Although the Sandstone Gully TSF is approved as a mine feature in the EA, significantly more latent tailings are present within the footprint than was previously assumed. To enable the construction of Sandstone Gully TSF, removal of latent tailings must occur. However, due to the ground conditions, the methodology to remove latent tailings will be slower than allowed for in the original mine plan. Any delay to removing latent tailings from Sandstone Gully directly impacts construction timeframes for Sandstone Gully TSF. Upper Mundic Gully TSF is not intended to receive any other form of water from the site during the construction phase (i.e. prior to it becoming the TSF). No transfer of water from the OCP to the Upper Mundic Gully TSF is proposed as part of this amendment. All references to an OCP-to-Upper Mundic Gully water transfer in the water balance report reflect a contingency scenario that was assessed for completeness of the risk assessment only and does not form part of the design or operational basis of the Upper Mundic Gully TSF. The water balance for the Upper Mundic Gully TSF has been assessed on the basis of no operational pond volume, with design storage sized to accommodate the Probable Maximum Precipitation (PMP) event without requiring an operational spillway. The OCP will continue to be managed independently in accordance with its existing approved water management framework. The proposed location of the Upper Mundic Gully TSF is displayed in Figure 4. The Upper Mundic Gully portion of the Mount Morgan Mine site is a highly disturbed environment that no longer free drains due to the historical placement of waste rock material and operation of a human made tunnel that diverts water from an ephemeral dam to Dam 8. Consequently, the hydrological regime of the Upper Mundic Gully area has been significantly altered due to the placement of waste rock
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and the artificially created OCP. The modifications to the Upper Mundic Gully landscape are described further in Section 4.1 of this report. The waste rock dump, referred to as the ‘Western Dump’ occupies a significant portion of the Upper Mundic Gully valley. This feature is not listed in Table A1 of the EA. There is no evidence that rehabilitation methods have been applied to this feature and it is likely, based on water quality sampling results from the ephemeral dam in Upper Mundic Gully, that the Western Dump is contributing Acid Rock Drainage (ARD) seepage into the environment. The Upper Mundic Gully TSF is proposed to tie into portions of the Western Dump to the extent practicable, ultimately sealing the currently exposed rock face, reducing potential ARD seepage into the surrounding environment.
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Figure 4. Upper Mundic Gully TSF extent
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2.1.2 Proposed Amendment 2: Update Table A1 and Figure 1 This amendment proposes to update the mining lease and location columns in Table A1 for the Pipe Corridor and Surface Exploration mine features which currently state “TBD, to be provided by 30 June 2025”. Pipe Corridor The pipe corridor connects the process plant to the Sandstone Gully TSF and is designed to transfer tailings in slurry form for permanent deposition. It is understood that at the time the administering authority issued the EA to Heritage Minerals in 2022, the mine plan was evolving and some details could not be provided to the administering authority for inclusion in the EA. Pipe corridor design has now been completed as shown in Figure 6. The maximum disturbance area of the pipe corridor is 1.17 ha which is within the maximum disturbance limit of 3ha specified in Table A1. This newly created pipe corridor disturbance area has been included as a polygon within the Schedule 1, Figure 1 of the EA as indicated in Figure 7 of this document. The pipe design layout is based on concept engineering. Proposed Amendment 3: Fix Minor Erroneous Issues in the EA The amendment proposes to modify Table H2 – Details of Regulated Structures of the EA to correct an erroneous value. 2.1.3 Table H2 currently authorises a maximum volume of 11,52,416 m 3 of tailings to be disposed in the Sandstone Gully TSF. The Sandstone Gully TSF Report prepared by WSP (issued 12 February 2020) provided a maximum cumulative storage capacity of 11,532,416 m 3 associated with tailings deposited to RL 319m. An extract of the relevant section from the TSF report is provided in Figure 5.
Figure 5. Sandstone Gully TSF Storage Capacity (Golder, 2020)
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Figure 6. Pipe Corridor Extent
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Surface Exploration This application intends to amend the EA to remove the exploration mine domain and associated mine feature from Table A1. Inclusion of the surface exploration domain into Table A1 represents a legacy issue that Heritage Minerals inherited from the previous EA holder. Mount Morgan Mine is a unique site in that waste material historically deposited at the site is now a resource for recovery. To inform the resource model historic exploration works were undertaken by previous EA holders involving drill of waste material. Heritage Minerals have not conducted any additional exploration works across the site and any prior disturbance associated with the surface exploration mine feature is associated with previous EA holders. The drilling process typically involves using a 50-200mm augur bit to obtain soil samples from comparatively shallow depths as the waste material was disposed above grade. As the drilling depths were shallow, construction of drill pads which would be typically for greenfield exploration activities did not appear warranted. Evidence from a previous Plan of Operations (PoO) (AARC, March 2019) indicated that 234 drill holes were rehabilitated during the previous PoO (2018) with the method being cut to ground level, capped and cemented. The PoO states that the drill holes were not formally certified and therefore still appear within financial assurance for the current PoO and subsequently carried forward to the Estimated Rehabilitation Cost (ERC) that is currently in place. An extract from the 2019 PoO is provided in Figure 7 whilst the complete report is provided in Appendix A.
Figure 7. Extract from 2019 PoO (Source AARC, 2019)
As exact coordinates of previous drill locations can not be determined, it is a reasonable assumption that historical drilling occurred within latent tailings, waste rock dumps and stockpile domains as these are key waste domains that contain resources. This is further evidenced by information from the 2017 Plan of Operations (AARC, August 2017) that references that drilling occurred at the following mine features: ∕ Mundic East and West; ∕ Red Oxide Tailings; ∕ No.2 Mill Tailings; ∕ Shepherd’s Gully Tailings Dam; ∕ Sandstone Gully; ∕ Frog Hollow Dump; ∕ Lower Linda Dump; ∕ Sandstone Gully; ∕ Mundic East and West; ∕ Rex Oxide Tailings ∕ No.2 Mill Tailings;
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∕ ∕ ∕
Shepherd’s Gully Tailings Dam;
Magazine Dump; and Mullock Dumps K and Q.
Figure 8. Extract from PoO 2017 (AARC)
2.2
Amendment Justification
2.2.1 Justification for Proposed Amendment 1 Upper Mundic Gully TSF approval will facilitate a life of mine permanent tailings location to support Heritage Mineral’s remediation project. Although the Sandstone Gully TSF is approved as a mine feature in the EA, significantly more latent tailings are present within the footprint than was previously assumed. To enable the construction of Sandstone Gully TSF, removal of latent tailings must occur. However, due to the ground
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conditions, the methodology to remove latent tailings will be slower than allowed for in the original mine plan. Any delay to removing latent tailings from Sandstone Gully directly impacts construction timeframes for Sandstone Gully TSF, and without a permanent location to discharge tailings the remediation project can not proceed. As described in Section 2.3.1, there are no other viable locations within the mining tenure to construct and operate a TSF. A vast majority of the Mount Morgan Mine site is highly disturbed through historical mining operations. An options assessment, presented in Section 2.3, determined that the Upper Mundic Gully area is the preferred location for construction and operation of the TSF primarily due to the favourable topography that allows a valley TSF geometry. Valley TSFs reduce stability risks as they leverage existing landforms as buttresses whilst limiting seepage of historically placed waste material. Establishing a TSF in Upper Mundic Gully, to be designed and operated in accordance with tailings management best practice, is considered a better environmental outcome than the current environmental setting whereby legacy waste rock can leach uncontrolled to the surrounding environment. Additionally, positioning the TSF in this location avoids sterilisation of resources as the TSF footprint will occur in an area with no known latent tailings resource. The Upper Mundic Gully TSF has been designed in accordance with best practice in accordance with relevant DETSI Guidelines and Australian National Committee on Large Dams (ANCOLD) and provides additional engineering controls in the form of robust bituminous geomembrane liner to reduce seepage. The setting within Upper Mundic Gully provides the most favourable location to mitigate potential environmental harm associated with typical TSF hazards such as overtopping and piping failure. Dam break and consequence category assessments have been performed and are provided in Section 5.2. Impacts to environmental values have been assessed in Section 2.4 and Section 7 whilst a risk assessment is presented in Section 8. Assessment outcomes are that this proposed amendment does not significantly increase the level of environmental harm caused by the relevant activity. Further justification for the proposed conditions requested as part of this application are provided in Section 2.3 of this report.
2.2.2
Justification for Proposed Amendment 2
Pipe Corridor The justification for this proposed amendment to update Table A1 of the EA with recent and relevant information pertaining to the Pipe Corridor mine feature alignment. The Pipe Corridor is already an approved feature in the EA, there are no impacts on any environmental values and this proposed amendment does not significantly increase the level of environmental harm caused by
the relevant activity. Surface Exploration
The removal of the exploration mine domain from Table A1 of the EA is justified on the grounds that progressive certification of point feature, that occupy a much larger mine domain polygon, is counterintuitive. Critically, previous drill locations that comprised the surface exploration domain are in fact point features that occur within much larger mine domains. The Mount Morgan Mine site is unique in that exploration has historically been undertaken within the boundaries of mine domains, which is not the case for brownfield site whereby exploration is typically conducted outside of established mine domain boundaries. The requirement to obtain progressive certification for boreholes that are located within larger domains raises concerns around practicality and duplication of the certification process. The definition of mine domain differs across jurisdictions however the precedence set in Queensland under the Progressive Rehabilitation and Closure Plan (PRCP) framework is that rehabilitation areas/improvement areas (which are typically identified through transitioning mine domains/mine
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features) have a clear boundary demarcating the spatial extent of a polygon or polyline. In the case of the surface exploration mine features, which are point features located within a much larger mine domain, progressively certifying the rehabilitation of each point feature would also apply to the polygon underneath. This is considered a perverse outcome as the progressive certification can not apply to two separate domains that occupy the same physical area. The progressive certification process articulated in the Progressive Certification for Resource Activities Guideline (ESR/2022/5900 Version 1.02) states that the content of a progressive certification report must, amongst other things, include GPS Coordinates of the corners of the certification area or metes and bounds of the perimeter of the certification area. As the size of the boreholes are estimated to be between 50-200mm in diameter, it is not considered practical to obtain GPS coordinates of the corners of the disturbance. Removal of the exploration mine domain does not prevent the EA holder from undertaking any future exploration works at the mine features listed in Table A1 as condition A14 of the EA states the following: “ A14 All exploration activities carried out at the licensed place must comply with each of the Standard Environmental Conditions contained in the most recent version of the Eligibility criteria and standard conditions for exploration and mineral development projects -ESR/2016/1985 ”. There are no impacts on any environmental values and this proposed amendment does not significantly increase the level of environmental harm caused by the relevant activity. 2.2.3 Justification for Proposed Amendment 3 The justification for the proposed amendment is that the maximum value currently in the EA was either erroneously applied for or erroneously transposed into the EA during a previous amendment. The maximum value of 11,52,416m 3 is incorrect and the EA should be amended to authorise the correct value of 11,532,416m 3 . The International System of Units promotes decimal separators to demarcate a factor of 1,000. It is abundantly apparent that the value of 11,52,416 incorrectly provides for a decimal separator of 100 associated with the numbers “52”, further supporting that the number “3” was erroneously omitted. There are no impacts on any environmental values and this proposed amendment does not significantly increase the level of environmental harm caused by the relevant activity. A revised Table H2 has been provided within Section 2.3.2 of this report. 2.3 Proposed Conditioning Proposed conditions to support the amendments are provided within this section of the report. Items proposed to be removed from the EA are crossed out whilst items for inclusion in the EA are highlighted in red. The proposed conditions have been organised into the following categories for ease of understanding: ∕ Section 2.2.1. Conditions within the EA proposed for inclusion and amendment; ∕ Section 2.2.2. Tables within the EA proposed to be amended; and ∕ Section 2.2.3. Figures within the EA proposed to be amended. Conditions within the EA Proposed modifications to existing EA conditions and proposed new conditions for inclusion in the EA are provided in Table 5. 2.3.1
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Table 5
Proposed modifications and new conditions within the EA
Schedule Reference
Current Wording
Proposed Wording
Justification
Schedule A – General
A14
All exploration activities carried out at the licensed place must comply with each of the Standard Environmental Conditions contained in the most recent version of the Eligibility criteria and standard conditions for exploration and mineral development projects— ESR/2016/1985. In respect to the requirements of condition A14, where a condition of this Environmental Authority refers to a matter addressed in the Eligibility Criteria and Standard Conditions for Exploration and Mineral Development Projects (ESR/2016/1985), the condition of this Environmental Authority prevails. Unless otherwise permitted under the conditions of this environmental authority, contaminants must only be released from the process plant to the Sandstone Gully Tailings Storage Facility A Water Management Plan that considers all mine features specified in Table A1 - Authorised mining activities and locations must be developed by a suitably qualified and experienced person and implemented, by 1 October 2022.
None – delete condition
Supports removal of exploration domain and activities from EA
All exploration activities carried out at the licensed place must comply with each of the Standard Environmental Conditions contained in the most recent version of the Eligibility criteria and standard conditions for exploration and mineral development projects—ESR/2016/1985.
A15
None – delete condition
In respect to the requirements of condition A14, where a condition of this Environmental Authority refers to a matter addressed in the Eligibility Criteria and Standard Conditions for Exploration and Mineral Development Projects (ESR/2016/1985), the condition of this Environmental Authority prevails.
Supports removal of exploration domain activities from EA
Schedule W – Water
W2
Unless otherwise permitted under the conditions of this environmental authority, contaminants must only be released from the process plant to the Sandstone Gully Tailings Storage Facility and the Upper Mundic Gully Tailings Storage Facility
Facilitates that Upper Mundic Gully TSF can receive contaminants
W3
A Water Management Plan that considers all mine features specified in Table A1 - Authorised mining activities and locations must be developed by a suitably qualified and experienced person and implemented, by 1 October 2022. 30 May 2026
Updated condition W3 to allow Heritage to update the WMP to include the Upper Mundic Gully TSF. Amendment to the WMP is required regardless under condition W5— updating condition W3 will set the new date from which the updated plan must be implemented and then annually reviewed.
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Schedule Reference
Current Wording
Proposed Wording
Justification
W17
NA – New condition proposed
Prior to the construction of the Upper Mundic Gully Tailings Storage Facility, the environmental authority holder must install and provide to the administering authority the locations of groundwater monitoring bores to monitor groundwater quality at the Upper Mundic Gully Tailings Storage Facility. Table W1 must be updated to include the name and location of the additional monitoring bores that are installed Prior to the construction of the Upper Mundic Gully Tailings Storage Facility, the environmental authority holder must update the existing site wide groundwater model to incorporate the Upper Mundic Gully Tailings Storage Facility.
Provides assurances that the groundwater quality of the project footprint will be monitored prior to construction of the Upper Mundic Gully TSF. Baseline results will be compared against results obtained during TSF operation to determine potential impacts to groundwater Provides assurance that the existing groundwater model will be updated to consider the potential impacts associated with UMG TSF operations and closure. As impact to Grevillea hockingsii can not be avoided, a management plan is proposed to mitigate impacts. Considering the historical disturbance and degraded nature of the project area, including existing ARD contamination in soil, the modified hydrology, and the presence of dense patches of weeds, it is likely that the population of Grevillea hockingsii within the project area will decline without intervention.
W18
NA – New condition proposed
Schedule F – Prescribed Environmental Matters
F8
NA – New condition proposed
Prior to the construction of the Upper Mundic Gully TSF, the authority holder must develop, document and implement an Impact Mitigation Management Plan for Grevillea hockingsii .
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