Works Approval Supporting Document

Paraburdoo Iron Ore Mine – L5275/1972/12

July 2020

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Disclaimer and Limitation

This report has been prepared by Rio Tinto Iron Ore (Rio Tinto), on behalf of Hamersley Iron Pty Limited, specifically for the Paraburdoo Iron Ore Mine and Eastern Range Project. Neither the report nor its contents may be referred to without the express approval of Rio Tinto, unless the report has been released for referral and assessment of proposals.

Document Status

Rev Author Reviewer/s Date Approved for Issue

To Whom Date

A Jaclyn Ennis-John

Jennifer Major

Jessica Hay

Ewan Botterill

Cecilia LazoSkold

Jason Lee

Kiarrah Thomas

Lisa Terrusi

June 2020 Department of Water and Environmental Regulation

Date 1 July 2020

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TABLE OF CONTENTS

1 APPLICANT DETAILS ............................................................................................ 4

2 INTRODUCTION ..................................................................................................... 5

3 PREMISES DETAILS.............................................................................................. 8 3.1 Premises Description ............................................................................................................... 8 3.1 Land Tenure ............................................................................................................................ 8

4 PROPOSED ADMINSTRATIVE CHANGES ......................................................... 12

5 TSF1 NORTHER CELL RAISE - PROPOSED INFRASTRUCTURE AND EQUIPMENT ......................................................................................................... 14

5.1 Overview ................................................................................................................................ 14 5.2 Construction Phase ............................................................................................................... 16 5.1 Environmental Commissioning .............................................................................................. 16 5.2 Time Limited Operations........................................................................................................ 17 5.3 Operations and Monitoring .................................................................................................... 17 5.4 Design and Tailings Studies .................................................................................................. 20

6 WASTE DUMP LANDFILL - PROPOSED INFRASTRUCTURE AND EQUIPMENT ......................................................................................................... 24

6.1 Overview ................................................................................................................................ 24 6.2 Construction ........................................................................................................................... 25 6.3 Time Limited Operations........................................................................................................ 25 6.4 Operations ............................................................................................................................. 25 6.5 Subsequent Landfill Facilities ................................................................................................ 26

7 CLEARING ........................................................................................................... 28

8 STAKEHOLDER AND COMMUNITY CONSULTATION ....................................... 28 8.1 Regulator Consultation .......................................................................................................... 28 8.2 Community Consultation........................................................................................................ 28 8.3 Traditional Owners ................................................................................................................. 29

9 OTHER APPROVALS, LICENCES AND PERMITS ............................................. 29 9.1 State Agreement Act .............................................................................................................. 29 9.2 Environmental Protection Act 1986 (Part IV) ......................................................................... 29 9.3 Environmental Protection Act 1986 (Part V) .......................................................................... 30 9.1 Mining Act 1978 ..................................................................................................................... 30 9.2 Rights in Water and Irrigation Act 1914 ................................................................................. 31

10 SITING AND LOCATION ...................................................................................... 31

11 ENVIRONMENTAL SITING CONTEXT ................................................................ 39 11.1 Climate ................................................................................................................................... 39 11.2 Topography ............................................................................................................................ 39 11.3 Geology and Soils .................................................................................................................. 39 11.4 Hydrology ............................................................................................................................... 41 11.5 Hydrogeology ......................................................................................................................... 41 11.6 Flora and Fauna .................................................................................................................... 44

12 RISK IDENTIFICATION AND ASSESSMENT...................................................................... 46

13 EMISSIONS, MANAGEMENT AND CONTROLS ................................................................ 54 13.1 Discharges to the Environment – Windblown litter ................................................................ 54 13.2 Discharges to the Environment – Liquid Waste .................................................................... 54

14 REHABILITATION AND CLOSURE ..................................................................................... 55

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15 PROJECT COSTS ................................................................................................................ 56

REFERENCES ...................................................................................................................................... 57

Appendix 1 ........................................................................................................................................... 58

Paraburdoo Tailings Storage Facility Part V Works Approval Application Supporting Documentation (GHD, 2020a) ............................................................................................. 58

Appendix 2 ........................................................................................................................................... 59

Proposed Landfill – Distance to Groundwater ................................................................................. 59

Appendix 3 ........................................................................................................................................... 61

Flocculant Safety Data Sheet ............................................................................................................. 61

TABLES

Table 3-1: Indicative coordinates of the proposed TSF1 Northern Cell Wall Raise ............................ 8 Table 3-2: Indicative coordinates of the proposed Landfill .................................................................. 8 Table 4-1: Indicative coordinates of the removed and replaced monitoring bores ............................ 12 Table 5-1: Proposed TSF 1 Embankment Raise Infrastructure and Equipment ............................... 15 Table 5-2: Proposed waste fines water quality monitoring schedule................................................. 18 Table 5-3: Stability Assessment Results ........................................................................................... 21 Table 9-1: Prescribed Premise category details under existing Licence L5275/1972/12 .................. 30 Table 10-1: Nearby environmentally sensitive receptors and aspect .................................................. 32 Table 11-1: Records of Conservation Significance Flora Species identified in Project Area .............. 44 Table 11-2: Weeds of National Significance Identified in Project Area ............................................... 45 Table 12-1: Risk Rating Matrix............................................................................................................. 46 Table 12-2: Consequence Matrix ......................................................................................................... 47 Table 12-3: Likelihood Matrix ............................................................................................................... 47 Table 12-4: Risk Assessment - TSF 1 Northern Cell Wall Raise ........................................................ 48 Table 12-5: Risk Assessment – Proposed Landfill .............................................................................. 50 Table 15-1: Estimated Project Costs ................................................................................................... 56 Table 15-2: Prescribed Premise category related to application ......................................................... 56 Table A1-1 Landfill Monitoring Bores .................................................................................................... 60 FIGURES Figure 2-1: Regional Location ............................................................................................................... 7 Figure 3-1: Prescribed Premises Boundary and Project Tenure ........................................................ 10 Figure 3-2: Proposed Project Works ................................................................................................... 11 Figure 4-1: Replaced Monitoring Bores .............................................................................................. 13 Figure 5-1: Northern Cell Raise Arrangement (GHD, 2020a) ............................................................. 15 Figure 5-2: Site Monitoring Bores and Proposed and Licensed TSF1 Groundwater Monitoring

Locations .......................................................................................................................... 19 Figure 10-1: Nearest Sensitive Receptors ............................................................................................ 34 Figure 10-2: Project Siting - Ecological Receptors – Surrounding Flora .............................................. 35 Figure 10-3: Project Siting - Ecological Receptors – Surrounding Fauna ............................................ 36 Figure 10-4: Project Siting - Hydrological Receptors - Surrounding Water Bodies .............................. 37 Figure 10-5: Project Siting - Surrounding Heritage Sites ...................................................................... 38 APPENDICES Appendix 1: Tailings Storage Facility Part V Works Approval Supporting Document (GHD, 2020a). Appendix 2: Proposed Landfill Distance to Groundwater Appendix 3: Flocculant Safety Data Sheet.

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Abbreviations

AER Annual Environmental Report

AMD Acid mine drainage

ANZECC Australian and New Zealand Environment and Conservation Council

AWTP Acid water treatment plant

BGL Below ground level

CCIR Critical Containment Infrastructure Report

CPS Clearing Permit

DMIRS Department of Mines, Industry Regulation and Safety

DoH Department of Health

DRF Declared Rare Flora

DWER Department of Water and Environmental Regulation

EPA Environmental Protection Authority

EPAS EPA Services

EP Act Environmental Protection Act 1986

EPBC Act Environment Protection and Biodiversity Conservation Act 1999

GWL Groundwater Licence

HSEC Health, Safety, Environment and Communities and Social

IBRA Interim Biogeographic Regionalisation of Australia

ILUA Indigenous Land Use Agreement

LIC Local Implementation Committee

Mining Act Mining Act 1978

ML State Agreement Mineral Lease

P Priority

PAF Potentially acid forming

PEC Priority Ecological Community

PDWSA Public Drinking Water Source Area

PIL3 Pilbara Bioregion

RiWI Act Rights in Water and Irrigation Act 1914

RT Rio Tinto

SCARD Spontaneous Combustion and Acid Rock Drainage

TEC Threatened Ecological Community

TSF Tailings storage facility

WFSF Waste fines storage facility

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1 APPLICANT DETAILS

This report provides the supporting information for the Works Approval Application (WAA) being submitted by Pilbara Iron for proposed works at the Paraburdoo Iron Ore Mine (Paraburdoo), part of the Greater Paraburdoo Operations. The Applicant (the Licensee) of the land subject to this Works Approval application is: Pilbara Iron Company (Services) Pty Ltd (PICS) L 18, Central Park 152-158 St Georges Terrace Perth, WA, 6000 ACN: 107 210 248 The scope of this WAA includes:

• Paraburdoo Tailings Storage Facility (TSF) 1 Northern Cell upgrades, involving:

o Two metre upstream embankment raises

o Relocation of existing deposition pipework

o Deposition of waste fines into northern cell.

• Construction and operation of a Category 64 Paraburdoo Ex Pit Waste Dump Landfill (Landfill).

• Administrative changes related to the

o Removal and replacement of two TSF monitoring bores. The authorized representative for the Works Approval application is: Jennifer Major Senior Advisor – Government Approvals Rio Tinto 152-158 St Georges Terrace Perth, WA, 6000 Mobile: 0459 835 617 Email : Jennifer.Major@riotinto.com

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2 INTRODUCTION

The proposed works are located in the Shire of Ashburton approximately nine km south from the processing plant and six km from the Paraburdoo township on Mining Lease ML246SA and General Purpose Leases (AG) AG70/14 and AG 70/04 (Figure 2-1). The TSF1 Northern Cell is approximately three km from the Further Fines Processing Plant (FFPP) and not currently in use. The Landfill will be located within the Waste Rock dump near the TSF northern cell embankment, within the same tenement boundaries, and the bores within these bounds. This Works Approval application seeks approval for:

• Construction and operation of an upstream wall raise of TSF1 Northern Cell

• Construction and operation of a Category 64 Waste Dump Landfill.

• Construction and operation of additional Landfill cells (inert and putrescible) throughout licence duration.

• Removal and replacement of two listed monitoring bores.

The TSF1 has been approved for waste acceptance since 1995. The currently active TSF1 Southern Cell will reach capacity in mid-2021, and it is proposed that an upstream wall raise of the Northern Cell embankments is completed to increase storage capacity beyond this date. The works will consist of a 2m upstream raise of the confining embankments from 371 RL to 373 RL which is within the height approved by the existing Mining Proposal for the Northern Cell (Reg ID 5930, approved December 2007). It is anticipated that waste fine deposition into TSF1 Northern Cell will commence in Quarter 2 2021 and will continue for approximately four years. There are no changes to existing operational controls and practices proposed. The currently approved, design capacity and the TSF1 footprint will remain unchanged. A risk assessment of the proposed raise identified that there were two potential pathways from the TSF, saline liquor seepage from the base of the TSF into the groundwater, and slow migration of the existing saline water in the groundwater (identified at the toe of the Main Embankment) towards down-gradient receptors. However, given that groundwater and ecological studies determined that salinities are decreasing over time; migration rates are low; and groundwater analysis identified that flow lines would converge towards the 4E terminal lake, impacts on potential receptors is limited. The proposed Landfill will be sized to accept approximately 3000 tonnes of waste per annum and will replace existing licenced landfill cells as they reach capacity and will be placed in the location of the existing 4EE Waste Dump, north of the TSF. Construction will commence in parallel with TSF1 Northern Cell works and will be ready for waste acceptance once construction is complete. It is requested that the assessment of this works approval application includes the provision for the construction, commissioning and operation of subsequent landfills within the Prescribed Premises that may be required to support ongoing operations. Landfills will be only constructed and operated as needed and will remain within

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the licenced premises capacity of 5 000 tonners per annum. To help facilitate this flexibility within the licence, standard controls to ensure the risk to the environment is appropriately managed have been proposed. In addition to the works proposed above, an amendment to the monitoring bores currently licenced is requested as part of the works approval application assessment. TSF1 groundwater monitoring bores PTD02D and PTD03 have been identified during monitoring as being consecutively dry and two new bores have since been drilled to replace these, MB18TSF0001 and MB18TSF0002. It is requested that the licence be amended to address this change.

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Figure 2-1: Regional Location

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3 PREMISES DETAILS

3.1 Premises Description

Greater Paraburdoo Operations (GPO), located approximately six km south-west of Paraburdoo town, comprises of operating mines at Paraburdoo, Eastern Range and Channar, with central processing facilities at Paraburdoo. Mining operations commenced at Paraburdoo in 1972, at Channar in 1990, and at Eastern Range in 2004. The proposed works are located within, and adjacent to the existing TSF1 at the Paraburdoo mine within the existing Prescribed Premise boundary (Figure 3-1). The indicative coordinates for each facility are provided in Table 3-1 and Table 3-2 below and shown in Figure 3-2. Table 3-1: Indicative coordinates of the proposed TSF1 Northern Cell Wall Raise

Corner Easting (m) Northing (m) 1 563104.43 7427133.76 2 562684.22 7427133.89 3 562940.93 7428317.83 4 563260.91 7428727.59 5 563696.53 7428243.90 6 564003.91 7428065.00 7 564056.23 7427917.00 8 564598.62 7427619.64 9 564426.50 7427179.43 10 563561.03 7426986.39

All coordinates are provided using map projection MGA 94 Zone 50 Table 3-2: Indicative coordinates of the proposed Landfill

Corner Easting (m) Northing (m) 1 561662.78 7429372.44 2 562832.10 7429373.99 3 563035.58 7428784.26 4 562760.05 7428073.24 5 561329.57 7428449.41 6 560197.87 7428945.22 7 560625.94 7430086.71

All coordinates are provided using map projection MGA 94 Zone 50

3.1 Land Tenure

Rio Tinto operates the Paraburdoo mine which is 100% owned by Hamersley Iron Pty Limited (a wholly owned subsidiary of Rio Tinto Limited). PICS currently holds Licence L5275/1972 for the Paraburdoo Iron Ore Mine and Eastern Range Project Prescribed Premises, granted under Part V of the Environmental Protection Act 1986 (EP Act).

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As identified in Figure 3-1 the proposed works are partially located on State Agreement Mining Lease ML246SA granted pursuant to the Iron Ore (Hamersley Range) Agreement Act 1968 and General Purpose Leases G4SA and G14SA, granted under the Mining Act 1978 (WA) (Mining Act).

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Figure 3-1: Prescribed Premises Boundary and Project Tenure

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Figure 3-2: Proposed Project Works

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4 PROPOSED ADMINSTRATIVE CHANGES

There have been minor amendments to the ground water monitoring regime since the last assessment, and therefore the following change is being requested. Amendment to Active Monitoring Bores TSF1 groundwater monitoring bores PTD02D and PTD03 have been identified during consecutive monitoring rounds as dry and two new bores have since been drilled to replace these, MB18TSF0001 and MB18TSF0002. The decommissioned and newly installed monitoring bores are listed in Table 4-1 and also identified in Figure 4-1. The Licensee requests that the this is addressed it the Works Approval and subsequent License Amendment. Table 4-1: Indicative coordinates of the removed and replaced monitoring bores

Removed Bore Replacement Bore Easting (m) Northing (m) PTD02D MB18TSF0001 562,909 7,428,439

PTD03 MB18TSF0002 562,806.2 7,428,240.3

All coordinates are provided using map projection MGA 94 Zone 50

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Figure 4-1: Replaced Monitoring Bores

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5 TSF1 NORTHER CELL RAISE - PROPOSED INFRASTRUCTURE AND EQUIPMENT

5.1 Overview

The FFPP was commissioned in 1995 and processes ore from the Paraburdoo, Eastern Range and Channar mines. Processing does not include grinding and the by-product is a fines slurry deposited as tailings into TSF1. A flocculant is added to the process and the current Safety Data Sheet is provided in Appendix 3. The TSF1 is an above ground cross-valley storage facility. Deposition of fines into the original TSF1 area, now known as the ‘Northern cell’ commenced in 1995, with construction of the main embankment (also known as the Dividing Embankment) undertaken in 2000 to divide the TSF into the Northern Cell and Southern Cell. Tailings in the Northern Cell are contained by the western main embankment and tailings in the southern cell are contained by the western and south-eastern saddle embankments. Tailings are deposited through perimeter deposition along the embankment walls, coordinated in a manner to manage the decant pond of each cell around the central decant structure. The decant structures feed water into the return water pond, from which water is recycled and transferred back to the FFPP. There have been a number of staged works to increase the embankment height during operation. Each raise has undergone various environmental assessments and regulatory approval. The current facility has been approved by the Department of Mines, Industry Regulation and Safety (DMIRS) under Mining Proposal Reg ID 5930 and Reg ID 60720. The Southern Cell was approved to a maximum height of RL 371 m (in 2016) and the Northern Cell to RL 393 m (in 2007). The last Department of Water and Environmental Regulation (DWER) assessment of the facility was a 2016 licence amendment to approve the southern cell embankment raise to RL 371 m. The proposed TSF1 embankment raise will include the following infrastructure as detailed in Table 5-1 and shown on Figure 5-1. The operation of raised TSF1 Northern Cell will be consistent with the current operational philosophy, with equal perimeter discharge and a central decant pond at the location of the current decant tower.

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Table 5-1: Proposed TSF 1 Embankment Raise Infrastructure and Equipment

Infrastructure and Equipment Relevant Categories

Site Plan Reference

CCIR Required

Env. Commissioning

TSF1 Northern Cell Raise. Upstream raise of the confining embankments by 2 m from 371 mAHD to 373 mAHD by upstream construction method.

5 Refer Figure 3-2 and Figure 5-1

Y

Y

Upgrade of decant system. Comprising of the replacement of the siphon decant system with a skid/trailer mounting pump system.

5

Ramp construction. Potential construction of a ramp from the decant access way to the tailings surface to position a decant pump

-

Relocation of road access. Relocation of the existing access road around the eastern perimeter along the natural topography or raised in its current location.

-

Figure 5-1: Northern Cell Raise Arrangement (GHD, 2020a)

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5.2 Construction Phase

Construction works are planned to be undertaken between January and June 2021, with the majority of earthworks being completed in the first quarter. Civil works will be undertaken with the raised embankment being partially founded on the existing Main Embankment crest and partially on the adjacent tailings beach. This would result in the raising of all confining structures of the Northern Cell (Main Embankment and Dividing Embankment) and the perimeter road by 2 m, resulting in a crest elevation of RL373 m AHD that will not change the footprint of TSF1. GHD (2020b) detailed that the construction will consist of:

• Relocation of the topsoil stockpile east of the Northern Cell. There is a risk of construction activities impacting the topsoil stockpile therefore the topsoil stockpiles will be relocated to the west of the Southern Cell, where an existing topsoil stockpile has been established.

• Site preparation works, including clearing, grubbing and stripping and stockpiling of topsoil and subsoil from the natural ground that is within the footprint of the raise. This has been estimated to be minimal.

• Establishment of a borrow area. • Excavation and preparation of the embankment foundations, decant accessway and

perimeter roads. The foundation of the embankment raises will include existing embankment surfaces, tailings beaches and natural ground. The foundation preparation activities will include excavation of unsuitable materials (e.g. wearing course, loose materials, etc.), ripping and watering foundation surfaces and mixing and compacting with select fill).

• Construction of confining embankments, decant accessway and perimeter roads. This will involve hauling, placing and compaction of suitable material (select fill and wearing coarse), in accordance with the construction technical specification.

• Construction of surface water management structures. This will involve hauling, placement and compaction of rock fill and rip rap in accordance with the construction technical specification at the required locations.

• Raising of the existing spillway. Works to raise the spillway will include excavation of tailings and the top layer of material at the existing spillway. Select fill will be hauled, placed and compacted in accordance with the construction technical specification to the required spillway elevation. A rip rap layer will be placed on top of the completed select fill surface to provide erosion protection.

When construction is completed, a compliance document detailing compliance with commitments made in Works Approval application will be submitted to the Department.

5.1 Environmental Commissioning

Commissioning will involve the testing of pipe work and pumps installed for the Northern Cell. The deposition pipeline will be blanked at each spigot location and the deposition pipeline will be hydrostatically tested. The deposition pipeline will be visually inspected for

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leaks during the hydrostatic testing. Following the successful completion of the hydrostatic testing the valves and spigots will be installed and deposition of tailings will commence. There are no additional emissions related to this phase of work. The potential for emission and the controls in place for the commissioning phase are the same for Time Limited Operations and Operations and are detailed below in Sections 5.4, 5.5 and Appendix A.

5.2 Time Limited Operations

It is requested that Time Limited Operation be undertaken under the Works Approval, to allow for the assessment and determination of a Licence Amendment application. Conditions are proposed to be included in the Works Approval to regulate the proposed tailing deposition and waste disposal during the time limited operational phase. The conditions of the Works Approval are proposed to be transferred, as appropriate, into the Licence and transition to operation under Licence conditions will commence once a Licence Amendment is approved. Pumping rates and proposed emissions are the same as operations and are detailed below in Section 5.5.

5.3 Operations and Monitoring

The operation of TSF1 will be consistent with the current operational philosophy, with equal perimeter discharge around the raised TSF1 with the decant pond being centred at the location of the current decant tower. Operating procedures will be updated for the operation and management of the raised TSF1 Northern Cell once the detailed design has been completed. This will include:

• Preparation of a revised Operating Manual for TSF1 (including the tailings pipeline) - including preparation of operational and maintenance requirements and identification of operational hazards to meet HSEQ requirements and achieve Operations Readiness.

• Preparation of commissioning and deposition plan for inclusion in the Operating Manual.

Monitoring of the TSF1 will continue consistent with current site operations licencing requirements. The current licenced monitoring requirements are detailed in Table 5-2. Figure 5-2 shows site monitoring bores as well as the proposed and actual TSF1 monitoring bore locations.

Historical groundwater data for these bores and additional monitoring bores is provided in Appendix D – Summary of Laboratory Results of the Paraburdoo Tailings Storage Facility Part V Works Approval Application Supporting Documentation (GHD, 2020a) attached in Appendix A.

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Table 5-2: Proposed waste fines water quality monitoring schedule

Monitoring Location Monitoring parameter Criteria Frequency

MB18TSF0001 MB18TSF0002 MB18TSF0003 MB18TSF0004 MB18TSF0005 MB18TSF0006 PTD04D* PTD05D* PTD06D* PTD07D* PTD08D* PTD09D* PTD10* PTD11* PTD12* PTD22D PTD23D PTD24D PTD21 PTD26

Field Chemistry - pH (pH units)1, Electrical conductivity1, Temperature. Standard chemical suite: pH, EC, TDS, TSS, alkalinity. Major ions (mg/L) – Ca, HCO3, CO3, Cl, F, Mg, K, Na, SO4, Si, Al, Fe. Trace metals: Ag, As, Ba, B, Cd, Cr, Co, Cu, Hg, Mn, Mo, Ni, Pb, Sb, Se, Sn, Sr, U, V, Zn. Nutrients: NO3, NO2, Total N, NH3, Total P.

ANZECC Guidelines for Fresh and Marine Water Quality

Annually

Note 1: In-field non-NATA accredited analysis permitted

Note: * existing TSF1 Licensed Groundwater Monitoring Sites

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Figure 5-2: Site Monitoring Bores and Proposed and Licensed TSF1 Groundwater Monitoring Locations

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5.4 Design and Tailings Studies

5.4.1 Overview

A feasibility study (GHD 2020b) for the proposed 2m raise determined the raise to be compatible with the whole of facility TSF1 design completed in 2018. The Northern Cell raise has been designed to:

• Maintain a 200 m exclusion zone from confining embankment under operational conditions.

• Maintain a target operational decant pond radius of 300 m (distance to embankment 650 m; distance to exclusion zone 450 m).

• Returned decant water to the FFPP during operations conditions.

• Return decant water and 1:100 year 72 hour event storm water to FFPP over 6 months whilst keeping the decant pond away from the confining embankments (decant pond radius < 525 m).

• To store other extreme weather events (PMP/PMF, 1:5,000 year 72 hour event, etc.) in the Northern Cell and discharge the storm water through the spillway located on main embankment.

A review of existing data and completion of additional studies, where required, was completed of the tailings and decant, proposed embankment material and surrounding groundwater conditions. A summary of the key design studies and findings is provided below in Sections 5.6.2 to 5.6.7 and additional information on the assessment of the TSF1 raise is provided in Paraburdoo Tailings Storage Facility Part V Works Approval Application Supporting Documentation (GHD, 2020a) attached in Appendix A.

5.4.2 Design

TSF1 Northern Cell will be raised by 2 m from RL 371 m to RL 373 m to address waste fine storage requirements up to 2024. The proposed arrangement of the Northern Cell raise is shown in Figure 5-1.

The embankment raise geometry from the last two TSF1 raises was adopted for this raise to comply with ANCOLD guidelines and Rio Tinto Pit Demarcation and Barricading Standards. The embankment raise geometry of the Northern Cell comprises of:

• Upstream raise method. This choice of raise method is supported by the historical strength of tailings as a result of well managed tailings deposition and conditions encouraging sufficient consolidation and strength gain of tailings (i.e. large beach and TSF1 area, high evaporation) and does not change the facility footprint.

• 7m wide crest.

• 1V:3H batters.

• Homogeneous embankment constructed from select fill (non-dispersive).

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5.4.3 Stability analysis

Following ANCOLD Guidelines a preliminary stability analysis (SLOPE/W) of the embankment has been undertaken during the Pre-Feasibility Study (PFS) during in varying conditions, including fully saturated. Tailings strength was estimated using the results of Cone Penetration Tests (CTP) from 2016, 2017 and 2020. As shown in Table 5-3 studies completed have demonstrated that the embankments are stable (Factor of Safety (FoS) greater than 1.5). More information estimated shear strength and strength ratios and the study parameters is provided in Section 5.3 of Appendix 1. Table 5-3: Stability Assessment Results

Case Embankment ANCOLD FoS Guideline

Estimated FoS

Drained condition Dividing Embankment 1.5 3.1 Undrained Condition Dividing Embankment 1.5 2.9 Post-Seismic Dividing Embankment 1.1 1.2 Drained condition Main Embankment 1.5 2.5 Undrained condition Main Embankment 1.5 1.9 Post-seismic Main Embankment 1.1 1.5 Undrained condition and fully saturated. Main Embankment 1.5 1.9

5.4.1 Liquefaction Assessment

Liquefaction assessments were conducted during the design of the previous lifts (2013 and 2016) using the grading of the waste fines. The liquefaction assessments have demonstrated that liquefaction of the tailings was unlikely.

5.4.2 Waste fines deposition

Waste fines will be delivered to the Northern Cell using the existing, 3.2 km long, HDPE lined, steel tailings delivery pipeline. Deposition will be in batches utilising the current deposition system, with spigots spaced 40 to 80 m around the cell perimeter, achieving a beach slope of 0.5% to 0.7%. Currently, slurry tailings with a solids content of 34 to 40% (w/w), produced by the FFPP, is deposited in TSF1 at a rate of 2.3 Mt per year which equated to a rate of rise of approximately 0.5 m per year, it is anticipated that rate will continue. The decant system will remain the same, decanting into the return water sump, pumping decant water to the FFPP using the existing return water transfer pipeline.

5.4.3 Waste fine characterisation

Tailings properties were characterised in 2007, 2013 and 2014 and 2017. The tailings characterisation confirmed that the tailings properties have remained constant from 2007 to

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2017. The 2017 tailings characterisation was conducted by Knight Piésold (2017) and comprised sampling of the tailings from the FFPP and collection of supernatant liquor samples from the decant system. Collected samples were analysed in the laboratory for the following:

• Classification tests to determine:

o Particle size distribution of the tailings.

o Supernatant liquor density and pH.

o Atterberg limits of the tailings solid.

o Tailings solids particle density.

• Undrained and drained sedimentation tests.

• Air drying tests.

• Permeability and consolidation tests.

• Geochemistry test.

The results of the test on the 2017 sample are summarised below:

• Tailings slurry comprised 37% solids w/w.

• Solids particle density of 3.93 t/m3.

• Supernatant density of 1.0 t/m3.

• Supernatant pH of 8.38.

• Liquid Limit of 33%.

• Plastic Limit of 21%.

• Plasticity Index of 12%.

• Linear Shrinkage of 7%.

• The tailings consisted of 1% sand, 69% silt and 30% clay. The testing indicated that the material is Low Plasticity Silty Clay (CL) based on the Unified Soil Classification System (Geotechnical Site Investigation, AS1726-1993). The grading of the sample largely falls outside the boundary of tailings materials with low resistance to liquefaction.

• Sedimentation test showed an increase in dry density from 0.87 to 1.28 and a reduction in void ratio from 3.53 to 2.08 following deposition.

• Air drying tests indicated that following air drying the final dry density is 1.74 t/m3.

• Compression index (CC) of 1.401.

• Coefficient of consolidation (CV) of 2.9 m2/y.

• Tailings permeability ranges from 4 x 10-7 to 4 x10-8 m/s. Several studies (EGI, 2007; RTIO 2015; RTIO, 2016a) have indicated that the tailings material within TSF1 is largely non-acid forming (NAF). Samples taken from the TSF1 have

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however had high concentrations of mobile elements, resulting in high concentrations of cations and anions that were readily mobilised during de-ionised water leaches (RTIO, 2016a). It is suspected that the source of the readily mobile elements comes from the process water, which undergoes evapo-concentration when sent to TSF 1 (RTIO, 2019c).

Multi-element analysis for the tailing were screened against the Department of Environment and Conservation (DEC) Contaminated Sites Management Series Assessment levels for Soil, Sediment and Water. February 2010, Version 4, Revision 1. The screening identified exceedance for the Ecological Investigation Levels for Chromium, Manganese and Phosphorus.

Analysis for supernate liquor were screened Livestock Watering ANZECC (2000) and Drinking ADWG (2011) water quality objectives. The screening identified exceedance for the water quality objectives for TDS, Chloride and Sodium.

Additional details on the geochemical properties is provided in Section 4.5 and a discussion of the exceedances in Section 11.0 Paraburdoo Tailings Storage Facility Part V Works Approval Application Supporting Documentation provided in Appendix 1.

5.4.4 Water balance

A water balance (GHD, 2020a) has been carried out using Microsoft Excel to identify the water return infrastructure requirements and indicative stored water over time based on expected tailings throughputs, tailings properties and climatic data available for Paraburdoo. The water balance assessed inflows and outflows of water for identified water inputs and outputs for the TSF during operation. The water balance considered the following water inputs and outputs:

• Inputs

o Water from tailings slurry

o Rainfall from “frequent” and “rare” rainfall events

• Outputs

o Decanted water

o Evaporation

o Seepage

o Interstitial water within the tailings fines matrix In summary, the results indicated that for an assumed decant pump rate of 22.3 L/s at 74% pump utilisation, the decant pond never exceeds the maximum pond area of 30 ha (pond radius of 310 m) for both the average and wet cases. An additional check was carried out to determine compliance with the requirement to contain a 1:100 AEP, 72 hour flood duration event, with a minimum total freeboard of 500 mm. It was determined that at all times the freeboard would be greater than 500 mm for both scenarios.

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As part of the water balance a Conceptual Hydrogeological Model was prepared by GHD (2020a) and is included in Section 9.0 in the Paraburdoo Tailings Storage Facility Part V Works Approval Application Supporting Documentation

5.4.5 Seepage analysis

Seepage from TSF1 was estimated using the SEEP/W software from GeoStudio and GHD’s inhouse numerical model for the calculation of seepage due to consolidation of the tailings associated with loading. The seepage calculations indicate that raising the Northern Cell of TSF1 by 2 m results in an increase of 9% in the seepage. The increase in the total seepage of 119 m3/day is not considered significant and will not impact the hydrogeological regime beneath TSF1 (GHD, 2020a).

6 WASTE DUMP LANDFILL - PROPOSED INFRASTRUCTURE AND EQUIPMENT

6.1 Overview

The Paraburdoo operations currently dispose of general wastes to the existing, approved landfill, refer to licence amendment L5275/1972/12, issued 19/05/2016. The existing facility is nearing capacity and new landfill cells are required to support ongoing operations. It is proposed that a Category 64 (inert) Waste Dump Landfill is to be constructed adjacent to the Northern Cell main embankment (Figure 4-1), it will mainly be used for rubber disposal however it is requested that it is approved to accept the same waste types as currently licenced, including:

• Clean fill

• Inert Type 1 waste (including conveyor belts, screen mats, concrete rubble and steel products)

• Inert Type 2 waste (including tyres and plastics)

• Special Waste Type 1

• Putrescible waste (wooden packaging and pallets only).

(As defined in the Landfill Waste Classification and Waste Definitions 1996 (as amended 2019) (Landfill Definitions)).

The site wide licenced capacity under Category 64 will remain unchanged at 20 tonnes or more per year and 5 000 tonnes per annum. The proposed landfill facility will have a design capacity of 3 000 tonnes per annum, replacing the existing licenced cells as they reach capacity. The landfill is proposed to be located with the boundary of the 4EE Waste Dump located near the TSF 1 Northern Cell. The coordinates of the proposed facility are provided in Table

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3-2 and the boundary is shown in Figure 3-2. As per the proposed landfill management commitments, the closest water course, Seven Mile Creek, is over 2 km away and the base of the landfill will be between 36 and 38 m AHD dependent on season. Recent monitoring data is provided in Appendix 2.

6.2 Construction

The landfill is proposed for construction during in Quarter 1 2021 pending approval. However, as the location of the landfill is potentially within one of the proposed borrow areas for the TSF1 Northern Cell raise embankments, the construction of the landfill may not commence until Quarter 2 2021. Should the material be determined as being suitable for borrow material, the required volumes will be removed prior to the construction of the landfill. The construction phase will involve the following:

• Clearing, authorised under Native Vegetation Clearing Permits (NVCP) (CPS 5090 and CPS 4594).

• Removal of borrow material for TSF 1 raise, if required.

• Earthworks - Trenches will be constructed as ‘drive-in’ to reduce the amount of wind-blown rubbish, with a tipping area of less than 30 m. The depth of each trench is expected to be on average 3 m deep. The width of the trenches will be 30 m and the length up to 50 m.

• Stormwater management - An earthen bund will also be constructed around the perimeter to divert surface water flows away from the landfill and prevent storm water from coming into contact with waste. In addition, a sump or bunding will be constructed to collect any surface water that has come into contact with waste.

When construction is completed, a compliance document detailing compliance with commitments made in Works Approval application will be submitted to the Department.

6.3 Time Limited Operations

It is requested that Time Limited Operation be undertaken under the Works Approval, to allow for the assessment and determination of a Licence Amendment application. Conditions are proposed to be included in the Works Approval to regulate the proposed and waste disposal during the time limited operational phase. The conditions of the Works Approval are proposed to be transferred, as appropriate, into the Licence and transition to operation under Licence conditions will commence once a Licence Amendment is approved. Potential emissions are the same as operations and are detailed below in section 6.4.

6.4 Operations

The landfill will be operated to the same standards as existing site landfills approved by L5275/1972. Only the following wastes will be accepted into the facility, as defined in the Landfill Definitions, and currently authorised on the existing Licence:

• Clean Fill

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• Inert Waste Type 1

• Inert Waste Type 2

• Special Waste Type 1

• Putrescible waste (wooden pallets and wooden packaging only). It is proposed that disposal of waste into the landfill will commence as soon as construction is completed and will be managed as per current site operating requirements. Key management measures include:

• Tipping area not greater than 30 m in length and at least 3 m above ground level height.

• Waste will be covered on an ad-hoc basis when required to at least 200 mm at final landform design.

• Signage will be installed around the facility indicating what waste can be accepted.

6.5 Subsequent Landfill Facilities

To assist with ongoing site waste management, it is requested that conditions are included in the existing Licence (L5275/1972) for the management of subsequent inert and putrescible landfill facilities (for the ongoing disposal of up to 5,000 tonnes of wastes per annual period without requiring further amendments to the Licence). Putrescible landfill facilities will be able to accept inert wastes however, it is expected that wherever practical, bulky inert waste will be disposed of to waste dump landfill facilities to allow for best management of the two types of landfill facilities Subsequent landfill facilities are proposed to be located and managed in accordance with the criteria detailed in Sections 6.4.1 to 6.4.5

6.5.1 Waste Acceptance

The proposed Landfill facilities will accept only the following types of waste at putrescible landfills:

• Clean Fill

• Inert Type 1 waste

• Inert Type 2 waste

• Putrescible waste

• Special Type 1 waste

• Other wastes that comply with the Class II criteria as defined in Landfill Definitions.

Inert landfills will accept similar wastes but will not accept putrescible wastes.

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6.5.2 Location

The proposed Landfill facilities will:

• be located within Prescribed Premise boundary.

• not be located within an Environmentally Sensitive Area.

• be located more than 100 m from any permanent or perennial watercourse.

• be located so that vertical distance between the waste and the highest seasonal and expected post mining ground water level is no less than 3 m (waste dump landfill) or 10 m (putrescible landfill).

6.5.3 Construction

Prior to construction of this and any future landfills, the Licensee will confirm that it will:

• be located more than 100 m from any permanent or perennial watercourse.

• be located so that vertical distance between the waste and the highest seasonal and expected post mining ground water level is no less than 3 m.

• include installation of signage indicating what waste can be is accepted.

• include construction of surface water management structures (i.e. bunding) to divert surface water flows away from the landfill.

• include a sump or bunding to collect any surface water that has come into contact with waste.

6.5.4 Lifespan

• Landfill facilities will have an approximate lifespan of at least five years.

6.5.5 Waste facility management

The following management measures will apply to all Landfill facilities onsite, operational and proposed:

• Landfill facilities will only accept approved types of waste, as per the Licence L5275/1972.

• Waste disposed of to landfill facilities to be recorded.

• Putrescible waste facilities will be fenced to an appropriate height, gated and locked to minimise unauthorised access and windblown waste. Fencing surrounding the perimeter will be regularly inspected for damage and cleared of waste.

• Landfill facilities will include a sign which clearly defines what waste is accepted.

• Landfill facilities will have a firebreak at least 3 metres in width around the boundary.

• The tipping area of putrescible landfill facilities will not be greater than 30 m in length and 2 m above ground level height.

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• Waste in putrescible landfill facilities will be covered weekly to at least 200mm so that no waste is left exposed (including at final landform design).

• Waste in waste dump landfill facilities will be covered on an ad-hoc basis when required, to at least 200mm at final landform design.

There may be a brief transitional period when existing landfill facilities are operating at the same time as the disposal of waste to new landfill facilities commences.

Compliance with the conditions of the Licence will be presented in the Annual Environmental Report.

7 CLEARING

Clearing of native vegetation will be required for the Landfill and borrow areas. All clearing completed for the proposed works is authorised under Native Vegetation Clearing Permit (NVCP) 5090 and CPS 4594. Clearing will be controlled through the NVCP conditions and by the Rio Tinto Approvals Coordination process. This ensures that the following is completed prior to commencing clearing activities: all heritage and biological reviews are undertaken; legal access to the land is in place; other necessary approvals are obtained; and the critical clearing boundary is inspected prior. Ground disturbance activities will be planned to ensure minimal disturbance is achieved through the use of appropriate ground engaging plant, use of designated tracks, roadways and use of pre‐existing disturbed areas.

8 STAKEHOLDER AND COMMUNITY CONSULTATION

8.1 Regulator Consultation

Rio Tinto meets with the DWER quarterly to provide an overview of upcoming proposals. The Department was provided with updates on this proposal in March, September and December 2019, April 2020, and a detailed scoping meeting was held in May 2020.

8.2 Community Consultation

The Licensee has a long-term commitment to working with Pilbara communities and recognises that local communities have a direct interest in their activities. Substantial community consultation and public review of existing and proposed future operations at the Paraburdoo Iron Ore Mine and Eastern Range Project has occurred as part of environmental approval processes. Community consultation will continue to be undertaken to keep relevant communities up to date throughout the operations and during closure of the Paraburdoo Iron Ore Mine. The construction and operation of the proposed works are not expected to affect any communities and therefore no specific community consultation has been undertaken.

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8.3 Traditional Owners

The Paraburdoo Iron Ore Mine is located wholly within the Yinhawangka Part A (WC2010/16) native title claim area. Yinhawangka Aboriginal Corporation (YWAC) is currently working with Yamatji Marlpa Aboriginal Corporation (YMAC) on cultural heritage matters as YWAC rebuilds internal capacity. The selection of Yinhawangka representatives for consultations and heritage surveys is undertaken via the Yinhawangka Heritage and Environment Committee (HEC) which has been appointed by the Yinhawangka Local Implementation Committee (LIC) to manage all heritage matters. Ongoing engagement with the Yinhawangka Aboriginal Corporation and the Yinhawangka People through survey work and formal episodes of consultation such as Heritage and Environment Committee (HEC) forums and Local Implementation Committee (LIC) forums provide opportunities for clear communication and collaboration across relevant issues and opportunities as they arise. The heritage values of the Paraburdoo mine site is well understood (through extensive surveys and consultation). The identification and management of cultural heritage within the traditional lands of the Yinhawangka People is in accordance with the principles and practices outlined within Rio Tinto’s Communities and Social Performance Guidelines, the Rio Tinto Cultural Heritage Group Procedure, and the heritage protocols within the Participation Agreement and Indigenous Land Use Agreement. Extensive heritage surveys have been conducted for the Paraburdoo Iron Ore Mine and Eastern Range Project, including the location of the proposed landfill facility. These surveys have identified significant Aboriginal heritage values which include artefact scatters, rock shelters, scarred trees, quarries and ethnographic sites.

9 OTHER APPROVALS, LICENCES AND PERMITS

9.1 State Agreement Act

The proposed works are approved under the existing Iron Ore (Hamersley Range) Agreement Act 1968 (Paraburdoo).

9.2 Environmental Protection Act 1986 (Part IV)

The works proposed as part of this works approval application are not included in the scope of the Greater Paraburdoo Iron Ore Hub Part IV proposal assessment as it is they are included under the State Agreement and can be suitably assessed under Part V of the EP Act. The Project is not regarded as warranting referral to the Environmental Protection Authority under Section 38 of the Environmental Protection Act 1986 (EP Act) by virtue of its minimal impact on the environment and its existing and effective management under Part V of the EP Act.

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9.3 Environmental Protection Act 1986 (Part V)

The existing Paraburdoo Iron Ore Mine and Eastern Range Project has been assessed as ‘Prescribed Premises’, as defined by Schedule 1 of the Environmental Protection Regulations 1987 (as amended). The Licensee currently holds Part V Operating Licence L5275/1972/12 for the Prescribed Premises, which includes the categories and design capacities shown in Table 9-1.

TSF1 has undergone multiple Part V assessments as part of licence L5275/1972/12, the most recent assessment under Category 5 was the 2016 Licence Amendment for the South Cell wall raise.

The site is also licenced under Category 64 and approved to accept clean fill, inert waste type 1, putrescible waste and special waste type 1 and 2 (as defined in the landfill definitions). The proposed landfill will not change these waste types or licenced category.

Table 9-1: Prescribed Premise category details under existing Licence L5275/1972/12

Category Number

Category Description

Category Premises Production or Design Capacity

This Application

5 Processing or beneficiation of metallic or non-metallic ore

50,000 tonnes or more per year

30,000,000 tonnes per annual period

Works Proposed. No change to category/capacity.

6 Mine dewatering 50 000 tonnes or more per year

800,000 tonnes per annual period

No works proposed. Not applicable to this Works Approval Application (WAA).

12 Screening, etc. of material

50,000 tonnes or more per year

10,000,000 tonnes or more per annual period

No works proposed. Not applicable to this WAA

52 Electrical power generation

10 MW or more in aggregate

127.5 MW No works proposed. Not applicable to this WAA

64 Class II putrescible landfill site

20 tonnes or more per year

5,000 tonnes per annual period

Works Proposed. No change to category/capacity.

73 Bulk storage of chemicals, etc

1,000 cubic metres in aggregate

5,903 cubic metres in aggregate

No works proposed. Not applicable to this WAA.

9.1 Mining Act 1978

The TSF is located on General Purpose Leases (AG) AG70/14 and AG 70/04 and State Agreement Mining Lease 246. TSF1 has been approved under the Mining Act under a series of Notice of Intents and Mining Proposals. The upstream raise proposed as part of this works approval application has previously been assessed by Department of Mines, Industry Regulation and Safety (DMIRS) thought the submission of a Mining Proposal (Reg ID 5930) application in 2007, approving the height up to RL 393.

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9.2 Rights in Water and Irrigation Act 1914

The Premises is located within the Ashburton sub area of the Pilbara groundwater allocation plan. Water supply for the existing Greater Paraburdoo operations is sourced from the 4E and 4W dewatering borefields, Southern borefield, Turee Creek borefield, Channar borefield and Northern borefield. Collectively the borefields supply the Greater Paraburdoo Operations Water Scheme (GPOWS). Current groundwater abstraction occurs under Groundwater Licence (GWL) 109318, issued under the Rights in Water and Irrigation Act 1914. GWL 109318 allows for abstraction of up to 9 GL/a for operational purposes, dust suppression, ore processing, mine dewatering and water supply. Supplementary supply if required is from the Turee Creek (GWL 107413) and Channar (GWL 107414) borefields, with an annual allocation of 1.4 GL and 3.23 GL/a, respectively. Potable water is sourced from the Northern Borefield.

10 SITING AND LOCATION

There are no sensitive receptors that are located in the immediate vicinity of the proposed works. Table 10-1 summarises the nearby environmentally sensitive receptors and proposed controls to prevent or mitigate any potential adverse impacts are detailed in Section 11. Receptors identified in Table 10-1 are shown in Figure 10-1 to Figure 10-5.

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Table 10-1: Nearby environmentally sensitive receptors and aspect

Classification Description Distance from works

Proposed controls to prevent or mitigate adverse impacts (if applicable)

Other /

Sensitive Receptors.

The Paraburdoo town site is the nearest residential sensitive receptor.

The Paraburdoo mining operations are surrounded by pastoral stations (see Figure 3-1) of which Mininer and Rocklea Pastoral Stations.

6 km (to the north east)

Any potential impacts are mitigated by the distance to the receptor.

Threatened Ecological Communities (TEC)

The Project area is heavily disturbed, and no TEC were recorded within the proposed work area.

- -

Threatened and/or priority flora

The Project area is heavily disturbed, and no Threatened/Priority Ecological Communities, Declared Rare Flora, or Priority flora species were recorded with the proposed work area. There were two priority species listed (Table 11-1), Hibiscus campanulatus (P1) and Ptilotus trichocephalus (P4) recorded in the proposed project area. Hibiscus campanulatus has a known range of approximately 50 km and Ptilotus trichocephalus a known range of approximately 277 km in NatureMap (DBCA 1998 - 2019).

At least 1 km from Northern Cell boundary

Any impact on the Priority species will be avoided where possible. Both species occur in the wider area and as such the potential loss is not expected to have a significant impact on the conservation status or representation of this species at a local or regional scale

Threatened and/or priority fauna

No conservation listed fauna has been recorded or are considered likely to occur within the Project area. Only one fauna species of conservation significance, the Common Sandpiper (Actitis hypoleucos), listed under the EPBC Act and the WC Act Schedule 5, has been recorded on the TSF1.

0 m The Common Sandpiper is a non-breeding visitor to all States and Territories within an international distribution (DotEE 2020), it has been recorded within the greater Paraburdoo area. There have been no identified impacts to date from the operation of the TSF1 on the species.

Aboriginal and other heritage sites

Heritage surveys (archaeological and ethnographic) have been conducted in conjunction with the Yinhawangka Traditional Owner group over large portions of the Project area since 2001 with key sites of significance identified within GPO area. There are three sites within the Waste Dump boundary, PB08-11, PARA-A-02B and PB03-13.

The identification and management of cultural heritage within the traditional lands of the Yinhawangka People is in accordance with the principles and practices outlined within Rio Tinto’s Communities and Social Performance Guidelines, the Rio Tinto Cultural Heritage Group Procedure, and the heritage protocols within the Participation Agreement and Indigenous Land Use Agreement. If required a s18 will be applied for prior to works commencing.

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Classification Description Distance from works

Proposed controls to prevent or mitigate adverse impacts (if applicable)

Rivers, lakes, oceans and other bodies of surface water, etc.

There are a number of surface water bodies surrounding the project area, these include:

• Turee Creek – 3 km to the south east

• Seven mile creek – 3 km to the west north west

• Pirraburdu Creek – 5 km to the north west

• Bellary Creek – 7 km to the north east

• Tableland Creek – 7 km to the north east

• Two Ephermeral creeks – both flowing to the west of the TSF.

Ranging from 3 – 7 km away

Seven Mile Creek was identified as a potential receptor in TSF1 Northern Cell Raise impact assessment. However, studies identified that raise in the TSF is not consider to result in further degradation of the groundwater environment. Refer to Section 11.4 and GHD (2020a) for additional information potential impacts and

Public Drinking Water Source Area (PDWSA)

No Public Drinking Water Source Areas are located within the Project area, with the nearest being the Paraburdoo Water Reserve.

10 km to the north‐east.

Groundwater flows is not toward the PDWSA and has not been identified as a potential receptor in the assessment of TSF1 Northern Cell Raise. Refer to Section 11.5 and GHD (2020a) for additional information on regional groundwater.

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Figure 10-1: Nearest Sensitive Receptors

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Figure 10-2: Project Siting - Ecological Receptors – Surrounding Flora

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Figure 10-3: Project Siting - Ecological Receptors – Surrounding Fauna

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Figure 10-4: Project Siting - Hydrological Receptors - Surrounding Water Bodies

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Figure 10-5: Project Siting - Surrounding Heritage Sites

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11 ENVIRONMENTAL SITING CONTEXT

11.1 Climate

The climate at the Paraburdoo mine is predominantly arid, with hot summers and mild winters. The area receives summer rainfall, generally associated with episodic events such as tropical depressions or cyclones that can bring heavy rain. Due to the episodic nature of these rainfall events annual rainfall has significant variation. Mean annual pan evaporation range from 3,000 to 4,000 mm across the region, approximately an order of magnitude greater than mean annual rainfall which varies between 200 mm and 500 mm (RTIO, 2019a).

11.2 Topography

Regional topography is denominated by two main landscape features; the Hamersley Range to the north of the Prescribed Premises and the lower areas of flats and undulating plains. The top of the Hamersley Range plateau is a series of rounded hills and narrower ridges, reaching an elevation of 1,245 m above sea level at its highest point. The plateau forms the watershed between the Fortescue River to the north and the Ashburton River to the south. Numerous rivers and streams have dissected the plateau, forming gorges and broader scree and rubble-filled valleys (Copp 2005). The Newman Land System makes up the greatest proportion of the Hamersley Range and is characterised by rugged plateaus, ridges and mountains supporting spinifex grassland (van Vreeswyk et al. 2004).

11.3 Geology and Soils

A summary of the geology and soil of the Paraburdoo region is provided below, with additional information provided in Section 6.2 of Paraburdoo Tailings Storage Facility Part V Works Approval Application Supporting Documentation provided in Attachment 1. The geology of the Pilbara region is dominated by the Hamersley Province which is a depositional basin of the Lower Proterozoic sediments. The sediments of the Hamersley Province lie in a sequence of supercrustal rocks comprising of the Fortescue, Hamersley and Turee Creek groups. The Paraburdoo Mine occurs within the Hamersley Plateau Province, which is primarily a complex of Lower Proterozoic rocks of the Hamersley and Fortescue groups. The rocks are mainly jaspilite and basalt with pockets of dolomite, shale, silt stone and acid volcanics. The sparse vegetation cover and the erosive force of heavy summer cyclonic rains causes much of the soil on the hill slopes to be transported down to the valleys and plains. This is an intermittent and slow process which occurs over a long period of time. Thus, species and associations of vegetation on the hills and slopes tend to be correlated to geology rather than soil type. Along drainage lines, superficial deposits influence the distribution of vegetation, but the presence of surface and ground water is also a major determining factor.

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TSF1 lies between a ridge of iron bearing Hamersley Basin sediments (Hamersley Group) to the north, and a ridge comprising Ashburton Basin rocks (Wyloo Group) to the south. The valley has been infilled with Cainozoic sediments including alluvium, and colluvium. The Paraburdoo TSF is located on top of recent clayey gravelly alluvial deposits and older Tertiary alluvium between 3 to 6 m thick. The alluvium is deposited within palaeo topography eroded into the Proterozoic bedrock. The valley in which the TSF is located is bounded to the north by a ridge line of Marra Mamba Formation, Mt McRae Shale and Brockman Iron Formation. These sequences are unconformably bounded to the south by the sandstone and siltstone dominated Mt McGrath Formation that forms the bedrock beneath the valley floor and the ridge line south of the TSF. The upper section of the Mt McGrath Formation is partially weathered and oxidised.

11.3.1 Soils

The Department of Agriculture produced mapping of the state which broadly classifies Land Systems (Rangelands) (Van Vreeswyck et al. 2004). These units broadly describe regions by their physiographic classification. The Project Area occurs within the Boolgeeda and Capricorn land systems. The following land system descriptions are adapted from Van Vreeswyck et al (2004):

• Boolgeeda Land System – Stony lower slopes and plains below hill systems supporting hard and soft spinifex grasslands or mulga shrublands.

• Capricorn Land System – Rugged sandstone hills, ridges, stony foot slopes and interfluves supporting low acacia shrublands or hard spinifex grasslands with scattered shrubs.

Potentially Acid Forming (PAF) materials Exposure of potentially acid forming (PAF) materials, if encountered and not appropriately managed, can potentially cause Acid Mine Drainage (AMD). Rio Tinto has undertaken an extensive program of geochemical testing over several years to understand the potential for acidification and/or metalliferous drainage to occur as a result of exposing various waste rock types common to mining operations in the Pilbara. The most significant geochemical risk in Pilbara iron ore bodies is associated with sulfides, such as pyrite (FeS2), which can form sulfuric acid when exposed to oxygen and water. The geological unit most commonly associated with pyrite and AMD in the Pilbara is the Mount McRae Shale (MCS), which is exposed at Paraburdoo. Pyrite can also occur within other stratigraphies, including black shale in the Mount Sylvia Formation (MTS) as well as in the Wittenoom Formation (WF), which underlie the orebody in some pits at Paraburdoo. Sulfate minerals also found in Pilbara rock types include alunite and jarosite, as well as schwertmannite, which can also pose a geochemical risk, albeit the risk is lower due to self-limiting chemical processes. Sulfur may also be present as gypsum and within goethite, which would be unlikely to produce acid. Given the proposed works and the location of the landfill, borrow material locations, the likelihood of encountering PAF materials during the construction is a low risk. However, the

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licensee will implement site management strategies which comply with the Rio Tinto Iron Ore (WA) Spontaneous Combustion and ARD (SCARD) Management Plan. Fibrous materials Fibrous minerals present a health hazard if fibres of a (defined) respirable size become airborne and are inhaled. There have not been any hazardous fibrous occurrences during mining to date at the Paraburdoo operations. Rio Tinto has well established management strategies to manage potentially hazardous materials at its Pilbara operations. Whilst the likelihood of encountering fibrous materials is low, if encountered, fibrous materials will be appropriately managed via existing management strategies specified in the Rio Tinto Iron Ore (WA) Fibrous Minerals Management Plan.

11.4 Hydrology

The footprint of TSF1 is located in the valley of a side-arm of Seven Mile Creek. The major drainage system of Paraburdoo is Turee Creek; however additional creeks including Seven Mile Creek, Pirraburdu Creek, Bellary Creek and Tableland Creek also ephemerally flow around and throughout Paraburdoo. Both the Turee Creek and Seven Mile Creek ultimately flow into the Ashburton River some 58 km downstream of Paraburdoo. Seven Mile Creek is ungauged, however, it periodically has significant flows following heavy rainfalls (RTIO 2018b). Seven Mile Creek is located approximately 3 km to the west north‐west of the TSF1 and could be classified as a receptor. The riparian vegetation communities along Seven Mile Creek and Pirraburdu Creek are considered locally significant, particularly those in association with permanent water (e.g. Ratty Spring) and more groundwater dependent species. However, groundwater studies have indicated that existing mine dewatering operations (4E dewatering, Channar and Turee borefield abstraction and intermittent recovery activities) have reduced groundwater – surface water connectivity of this system (GHD, 2020a). Two ephemeral creeks flow to the west of the TSF. There is a creek flowing from the decant pond and also a creek flowing from the toe of the western embankment. These creeks connect downstream and are likely to be connected to the previous hydrological layout of the area prior to the construction of the TSF.

11.5 Hydrogeology

Groundwater throughout the Prescribed Premises is located within shallow alluvial aquifers and underlying fractured basement rocks of the Hamersley and Wyloo Groups. Groundwater recharge in the area occurs via the infiltration of rainfall during intense rainfall events when evaporation is low. Recharge will be enhanced in zones of high permeability such as outcrops/subcrops of mineralised and fractured bedrock and also along minor drainage lines (Seven Mile, Pirraburdu and Turee Creeks) where increased surface water runoff occurs.

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Valley fill aquifers in the region comprise alluvium and colluvium in often complex sedimentary sequences, reflecting the various nodes of deposition. The alluvium tends to be clayey with interbedded sands and gravel lenses. Colluvial materials tend to comprise cobble size detritals within a clay matrix. There can be basal sand lenses. The valley fill forms an unconfined or water table aquifer, although the aquifer may be confined or semi-confined locally by sediments of low permeability. The aquifer is hydraulically connected with the underlying fractured rock aquifers. Groundwater flows in the valley fill is down-gradient in the direction of the surface water catchment. Discharge occurs as outflow to river springs and pools, evapotranspiration from vegetation, and evaporation through the unsaturated zone where the water table shallows. Groundwater is extracted by the Licensee to dewater orebodies, but also to support mineral ore processing, dust suppression and water supply purposes. The Licensee has existing water supply borefields operating to the west and east of TSF1. These borefields have their own local monitoring network to assess the performance of the pumping operations. Post mine closure the land could be returned for use for low density stock grazing purposes, and therefore groundwater quality should be maintained to protect this environmental value. It is noted the water quality objectives to protect aquatic ecosystems tend to be more conservative (lower concentrations) compared to those required to protect groundwater for livestock watering. Additional information provided in Sections 6.3 – 6.6 of Paraburdoo Tailings Storage Facility Part V Works Approval Application Supporting Documentation provided in Appendix 1. A summary of the geology and soil of the Paraburdoo region is provided below.

11.5.1 Groundwater Quality

Over the last 20 years groundwater bores at TSF1 have been monitored at a range of frequencies, and for varying analytes. The Paraburdoo Tailings Storage Facility Part V Works Approval Application Supporting Documentation provided in Attachment 1 provides an analysis of the data in Section 8.0 and a summary of the data has been provided in Appendix D, with spatial information for key elements (Salinity, chloride, pH, sulphate and EC) included in Appendices E to I. GHD (2020a) and Rio Tinto (2016a) made the following observations on groundwater quality:

• The groundwater in the monitoring bores adjacent to the embankment are enriched with chloride. However, there is a low likelihood of a conservative species (chloride) migrating towards Seven Mile Creek based on the migration pathway being modelled as moving away from Seven Mile Creek and towards 4E pit and the time taken for any migration to occur.

• Nitrogen concentrations in groundwater are around 20 mg/L (except near Seven Mile Creek and TSF1). Groundwater in some TSF1 monitoring bores have concentrations over 1,000 mg/L. The majority of laboratory analysis has been for nitrate nitrogen. Nitrate concentrations at TSF1, and remote from TSF1, exceed the revised ANZECC (2000) guideline of 4.9 mg/L for the 99% protection of aquatic ecosystems. It is

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suspected that nitrogen may be leached from the subsoil into the aquifer through changes in land use, e.g. clearing of vegetation.

• Concentrations of organic constituents such as TRH and BTEX have been generally not been identified above the laboratory limit of reporting (LOR) for the majority of samples. Concentrations above the LOR have been periodically identified in bores PTD04D, PTD05D, PTD08D PTD09D, PTD10D, and PTD20D. Organic analytes have been removed from the analytical program in the last 4 years and therefore the current condition with respect to these organics is not known. Most detections have been in the mid chain length fraction which suggests that it may be introduced through drilling processes, and below 2 mg/L. Residence time of fluids within TSF1 is likely to support attenuation of organic substances.

• A range of the heavy metals such as copper, boron, chromium and zinc have been identified above LOR, and at or marginally above their respective ANZECC (2000) guidelines for the protection of aquatic ecosystems. There is significant variation in dissolved metals identified in individual bores, e.g. iron, which possibly suggests some inconsistencies in sample collect or analysis.

• The background groundwater quality of the region is relatively good, with salinities generally below 1,500 mg/L TDS. The saline groundwater identified at the toe of the TSF embankments has not migrated significant distances west of the TSF over the last 20 years based upon review of available monitoring data, as characterised by the available monitoring network sites. There is some evidence that indicates that salinities are decreasing over time (but remain well elevated above background). Migration rates are low based upon low aquifer hydraulic conductivities derived from quantitative assessment of the catchment water balance. Under these circumstances, the raise in the TSF is not consider to result in further degradation of the groundwater environment.

11.5.2 Groundwater Level

Over the last 20 years groundwater bores at TSF1 have been monitored at a range of frequencies, and for varying analytes. Monitoring bores have also been installed downstream of TSF1 and as well as Vibrating Wire Piezometers (VWPs) have also been installed within the TSF1. An analysis was completed of the downstream bores, VWP as well as other monitoring bores within the area of Seven Mile Creek and 4E Pit. Based on the available data, ground water elevations were interpreted showing average mounding recession and drawdown influence at the end of 2000, 2010 and 2019 and steady state conditions (1996). The contours indicated that groundwater flow was primarily westwards towards Seven Mile Creek with groundwater mounding occurring following TSF1 commissioning, however, the mounding subsequently receded, and water levels have continued to drawdown as a result of on-going dewatering associated with the 4E pit to the northwest. An analysis of groundwater level data is provided in Section 7.0 and copies of the contour plots are provided in Appendix B of the Paraburdoo Tailings Storage Facility Part V Works Approval Application Supporting Documentation provided in Attachment 1.

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11.6 Flora and Fauna

The Project Area occurs within the Pilbara Bioregion (Chichester and Fortescue sub‐regions) as classified by the Interim Biogeographic Regionalisation for Australia. A significant number of biological surveys have been undertaken across the Greater Paraburdoo Prescribe Premises from 2009 to 2018 by Astron Environmental Services, Biologic Environmental Survey, Biota Environmental Sciences, Ecologia Environment and internal Rio Tinto botanists. Within the area covering TSF1 and the proposed landfill (refer Figure 10-2):

• None of the Vegetation represents a PEC or TEC or is considered a Groundwater Dependant Ecosystem (GDE).

• None of the weeds are declared pests.

• No threatened flora occur within the vicinity of the proposed works or are expected to occur.

Additional details are provided in the section 11.5.1 and 11.5.2 below.

11.6.1 Vegetation and Flora

The proposed works are located within the region described by Beard as the Fortescue Botanical District (Eremaean Botanical Province) (Beard 1975a, 1975b). The vegetation of this province is typically open and frequently dominated by spinifex, wattles and scattered eucalypts. Numerous vegetation and flora surveys undertaken within the GPO have mapped and described the vegetation, providing a detailed understanding including conservation significance of the vegetation communities and condition present. Astron (2018) provides a consolidated coverage and combined assessment of all previous detailed flora and vegetation surveys and is considered the most relevant report for the Project area. Within or surrounding the TSF1 or proposed landfill there were no TECs listed under the Commonwealth Environmental Protection and Biodiversity Conservation Act 1999 (EPBC Act) or State Biodiversity Conservation Act 2016 (BC Act), or PECs listed by the Department of Biodiversity, Conservation and Attractions (DBCA). There were two priority species listed (Table 11-1). Hibiscus campanulatus (P1) and Ptilotus trichocephalus (P4) were recorded in the project area. Hibiscus campanulatus has a known range of approximately 50 km and Ptilotus trichocephalus a known range of approximately 277 km in NatureMap (DBCA 1998 - 2019). Any impact on the Priority species will be avoided where possible. Both species occur in the wider area and as such the potential loss is not expected to have a significant impact on the conservation status or representation of this species at a local or regional scale. Table 11-1: Records of Conservation Significance Flora Species identified in Project Area

Category Number Rank Records No. Individuals

Hibiscus campanulatus P1 8 62

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Ptilotus trichocephalus P4 15 71

Introduced taxa have been recorded within the proposed works area however, none are Declared Pests as defined by the Biosecurity and Management Act 2007 (BAM Act) and/or Weeds of National Significance (WoNS). Weed species diversity and densities are high in areas associated with drainage features, tracks and historically disturbed sites. Ten species are known to occur in the TSF1 and proposed Landfill area and are listed in Table 11-2. Table 11-2: Weeds of National Significance Identified in Project Area

Category Number Category Description

Aerva javanica Kapok

Bidens bipinnata Bipinnate Beggartick

Cenchrus ciliaris Buffel Grass

Cenchrus setiger Birdwood Grass

Cynodon dactylon Couch Grass

Flaveria trinervia Speedy Weed

Malvastrum americanum Spiked Malvastrum

Rumex vesicarius Ruby Dock

Trianthema portulacastrum Giant Pigweed

Vachellia farnesiana Mimosa Bush

11.6.2 Fauna

The GPO Project area has been comprehensively surveyed, resulting in a detailed understanding including conservation significant species present and habitat values. Astron (2018) presents an integrated report that consolidates the results of numerous surveys and is considered the most relevant report for the Project area. Only one fauna species of conservation significance, the Common Sandpiper (Actitis hypoleucos), listed under the EPBC Act and the WC Act Schedule 5, has been recorded within the TSF1 area. The Common Sandpiper is a non-breeding visitor to all States and Territories within an international distribution (DotEE 2020), it has been recorded within the greater Paraburdoo area.

11.6.3 Subterranean Fauna

Stygofauna and Troglofauna have been identified downstream of the TSF1. Studies identified the following within the GPO:

• Stygofauna (21 species at Pirraburdu Creek and 19 species at Seven Mile Creek)

• Troglofauna

o Isopoda - Troglamadillo sp at Seven Mile Creek

o Zygentoma specie - Trinemura sp at Pirraburdu Creek and 4EE

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o Polyxenida – Lophoturus madecassus, Hemiptera – Phaconeura sp, Zygentoma – Dodecastyla

o sp, and Pauropoda - Decapauropus sp at the WTSF The licensee has commissioned subterranean fauna surveys, e.g. Biologic (2019a, b). Sampling generally targeted bores in the ranges, but included both areas of existing and proposed mining impact, as well as non-impacted reference areas. Biologic (2019b) completed a targeted survey for subterranean fauna, 19 Species of stygofauna and troglofauna (Troglamadillo sp.) has been identified at Seven Mile Creek. The survey also included the sampling of bores MB18TSF0003 and MB18TSF0004, located 1 km and 2 km west of the TSF however, no evidence of stygofauna, to date, was identified. The assessment undertaken by GHD (2020a) on the groundwater and interpreted travel times would suggest that there is a low likelihood of a conservative species (chloride) migrating towards Seven Mile Creek, and subterranean fauna. The migration pathway would suggest that the Seven Mile Creek would not be the receptor, as water levels would be deeper in the 4E pit, well below Seven Mile Creek elevations. Therefore, the terminal 4E pit lake is interpreted to form the ultimate receptor of elevating concentrations emanating from TSF1. The magnitude of time required for elevated concentrations to migrate such distances further suggests that it is susceptible to dilution, hydrodynamic dispersion, and rainfall recharge events.

12 RISK IDENTIFICATION AND ASSESSMENT

A risk assessment has been prepared to identify the potential emissions from the proposed activities and the potential sources, pathways and receptors of those emissions, and proposed controls to manage potential emissions to determine a risk rating. The risk assessment has been based on the DWER Guidance Statement: Risk Assessments (released by the then named Department of Environmental Regulation in 2017) and the Rio Tinto risk assessment process, based on the following risk rating matrix (Table 10-1):

Table 12-1: Risk Rating Matrix

Consequence Likelihood Slight Minor Moderate Major Severe Almost Certain Medium High High Extreme Extreme

Likely Medium Medium High High Extreme

Possible Low Medium Medium High Extreme

Unlikely Low Medium Medium Medium High

Rare Low Low Medium Medium High

Risk = consequence x likelihood

The following criteria (DWER 2017) are used to determine the consequence and likelihood of a risk event occurring (Table 10-2 and Table 10-3).

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Table 12-2: Consequence Matrix

Consequence Consequence description

Environment Health

Severe

On-site impacts: catastrophic Off-site impacts (local scale): high level Off-site impacts (wider scale): mid level Mid to long term or permanent impact to an area of high conservation value or special significance

Loss of life Adverse health effects: high level or ongoing medical treatment Local scale impacts: permanent loss of amenity

Major

On-site impacts: high level Off-site impacts (local scale): mid level Off-site impacts (wider scale): low level Short term impact to an area of high conservation value or special significance

Adverse health effects: mid level or frequent medical treatment Local scale impacts: high level impact to amenity

Moderate On-site impacts: mid level Off-site impacts local scale: low level Off-site impacts wider scale: minimal

Adverse health effects: low level or occasional medical treatment Local scale impacts: mid level impact to amenity

Minor On-site impacts: low level Off-site impacts (local scale): minimal Off-site impacts (wider scale): not detectable

Local scale impacts: low level impact to amenity

Slight On-site impacts: minimal Local scale impacts: minimal impacts to amenity

Table 12-3: Likelihood Matrix

Likelihood Likelihood description

Almost certain The risk event is expected to occur in most circumstances.

Likely The risk event will probably occur in most circumstances.

Possible The risk event could occur at some time.

Unlikely The risk event will probably not occur in most circumstances.

Rare The risk event may only occur in exceptional circumstances.

The potential emissions, sources, pathways and receptors that have been identified for the construction, commissioning and operation of the proposal are outlined in Table 10-4. This table also identifies the potential impacts, proposed controls and associated risk ratings. A detailed risk assessment will be undertaken for any activity which has been identified as having a ‘Medium’ risk rating or higher (Section 13). Detailed risk assessment includes:

• A description of the potential emissions, sources, pathways and receptors.

• Any controls that have been identified for the risk event.

• An assessment of the consequence and likelihood.

• Risk rating.

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Table 12-4: Risk Assessment - TSF 1 Northern Cell Wall Raise

Source Potential Emissions

Potential Pathway Potential Receptors Potential Impacts Proposed Controls Consequence Likelihood Risk Rating Detailed Assessment Required?

Category 5: TSF 1 Northern Cell Extension

Construction of TSF 1 Northern Cell Extension

Dust: Release of particulate matter from construction activities and vehicular movements.

Air: Transport through air then transport through the respiratory system

Residential:

None, the nearest receptors are the residents of the township of Paraburdoo, more than 6 km away.

Human health Impacts – respiratory illness.

Given the distance to the nearest receptor, impacts to public health or amenity from nuisance dust are expected to be limited.

Dust will be managed via the requirements of the Works Approval, Part V Licence L5275/1972, Vegetation Clearing Permit (5090) and standard operating procedures, including:

- Clearing will be managed to ensure that areas are only cleared as required and rehabilitation of cleared areas is implemented as construction is completed; and

- Dust suppression will be implemented (including use of water trucks, control of vehicle movements / restricted speeds).

Standard management procedures are expected to effectively mitigate the risk of dust emissions during construction.

Minor Rare Low Risk pathway is low, detailed assessment is not required.

Air: Transport through air then deposition

Riparian vegetation along the ephemeral creeks that flow to west from the TSF

Smothering and the potential suppression of photosynthetic and respiratory functions of vegetation.

Terrestrial ecosystems:

Native fauna

Dust may impact habitats which represent shelter, foraging and dispersal habitats for native fauna.

Given the distance from potential dust sources, dust is expected to have a negligible impact on native fauna.

Noise and vibration: associated with construction activities and vehicular movements.

Air or other physical medium: Vibration of particles.

Residential:

None, the nearest receptors are the residents of the township of Paraburdoo, more than 6 km away.

Human health Impacts – respiratory illness.

Given the distance to the nearest receptor, impacts to public health or amenity from nuisance dust are expected to be limited.

Environmental Protection (Noise) Regulations 1997 and standard operating procedures are expected to effectively mitigate the risk of noise during construction. Specific controls are not proposed.

Minor Rare Low Risk pathway is low, detailed assessment is not required.

Terrestrial ecosystems:

Nocturnal native fauna

Noise may disrupt nocturnal foraging behaviour.

Noise is expected to be limited at night when nocturnal native fauna are expected to be foraging and as such, noise is expected to have a negligible impact on native fauna.

Light Air: light spill generated during construction activities.

Residential:

None, the nearest receptors are the residents of the township of Paraburdoo, more than 6 km away.

Health and amenity:

Given the distance to the nearest receptor, impacts to public health or amenity from light spill are expected to be limited.

Standard operating procedures are expected to effectively mitigate the risk of light spill during construction. Specific controls are not proposed.

Minor Rare Low Risk pathway is low, detailed assessment is not required.

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Source Potential Emissions

Potential Pathway Potential Receptors Potential Impacts Proposed Controls Consequence Likelihood Risk Rating Detailed Assessment Required?

Terrestrial ecosystems:

Nocturnal native fauna

Light may disrupt nocturnal foraging behaviour:

Light spill is expected to be limited at night when nocturnal native fauna are expected to be foraging and as such, light is expected to have a negligible impact on native fauna.

Hydrocarbons Hydrocarbon spill causing soil contamination

Land Soil contamination. Hydrocarbons will be managed via relevant legislation (including Australian Standard AS 1940-2004: Storage and handling of flammable and combustible liquids), the requirements of the Works Approval, Part V Licence L5275/1972 and standard operating procedures, including:

- Fuel storage tanks will be designed and constructed to AS 1940-2004: The storage and handling of flammable and combustible liquids;

- Management structures (bunding / secondary containment) will be installed at all hydrocarbon storage and refuelling facilities to ensure any spills are contained; and

- Spill response will be provided.

Standard hydrocarbon management procedures are expected to effectively mitigate the risk of hydrocarbon spills during construction

Minor Rare Low Risk pathway is low, detailed assessment is not required.

Seepage of hydrocarbon spill to groundwater causing contamination

Groundwater of beneficial use (livestock watering).

Groundwater contamination (and declining health of any groundwater dependent vegetation):

Given the vertical distance to the groundwater and the groundwater pathway any hydrocarbon spills are not expected to seep to groundwater (or affect any associated terrestrial ecosystems).

Terrestrial ecosystems (vegetation communities dependant on groundwater):

Migration of hydrocarbon spill to surface water causing contamination

Surface waters and Terrestrial ecosystems (riparian vegetation):

None, the nearest receptors are Turee Creek and Seven Mile Creek (approx. 3 km from TSF1).

Surface water contamination (and declining health of any riparian vegetation):

Given the distance to the nearest receptors, any hydrocarbon spills are not expected to migrate to surface waters (or affect any associated terrestrial ecosystems).

Wastes General wastes generated during construction activities

Residential:

None, the nearest receptors are the residents of the township of Paraburdoo, more than 6 km away.

Health and amenity:

Given the distance to the nearest receptor, impacts to public health or amenity from general wastes are expected to be limited.

General wastes will be managed via the requirements of the Works Approval, Part V Licence L5275/1972 and standard operating procedures including:

- Sufficient recycling and general waste collection areas will be established and labelled with the relevant waste type to facilitate the management of waste;

- Recyclable materials will be separated from other waste and recycled wherever possible; and

- Non-recyclable materials will be disposed of at an approved landfill facility.

Standard waste management procedures are expected to effectively mitigate the risk of general wastes during construction.

Minor Rare Low Risk pathway is low, detailed assessment is not required.

Terrestrial ecosystems:

Native fauna.

Local increase in feral fauna (scavengers attracted to putrescible wastes) could result in predation and replacement of native fauna.

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Source Potential Emissions

Potential Pathway Potential Receptors Potential Impacts Proposed Controls Consequence Likelihood Risk Rating Detailed Assessment Required?

Category 5: In-pit Waste Fines Storage Facility

Operation of waste fines storage facility

The detailed risk assessment for the operation of the TSF 1 Northern Cell, 2m raise is included within Section 10 and 11 of the Paraburdoo Tailings Storage Facility Part V Works Approval Application Supporting Documentation provided in Attachment 1

Table 12-5: Risk Assessment – Proposed Landfill

Source Potential Emissions

Potential Pathway Potential Receptors Potential Impacts Proposed Controls Consequence Likelihood Risk Rating Detailed Assessment Required?

Category 64: Putrescible / Waste Dump Landfill

Construction of facility

Dust: Release of particulate matter from construction activities and vehicular movements.

Air: Transport through air then transport through the respiratory system

Residential:

None, the nearest receptors are the residents of the township of Paraburdoo, more than 6 km away.

Human health Impacts – respiratory illness.

Given the distance to the nearest receptor, impacts to public health or amenity from nuisance dust are expected to be limited.

Dust will be managed via the requirements of the Works Approval, Part V Licence L5275/1972 and standard operating procedures, including:

- Clearing will be managed to ensure that areas are only cleared as required and rehabilitation of cleared areas is implemented as construction is completed; and

- Dust suppression will be implemented (including use of water trucks, control of vehicle movements / restricted speeds).

Standard management procedures are expected to effectively mitigate the risk of dust emissions during construction.

Additionally, the distance from Paraburdoo town site further reduces the potential for impact.

Minor Rare Low Risk pathway is low, detailed assessment is not required.

Air: Transport through air then deposition

Riparian vegetation along the ephemeral creeks that flow to west from the TSF

Smothering and the potential suppression of photosynthetic and respiratory functions of vegetation.

Dust Declining health of vegetation including reduced ability for photosynthesis due to dust deposition / smothering.

Given that native vegetation is expected to be reasonably tolerant to dust deposition, dust generated during operations is expected to have a negligible impact on vegetation health.

Terrestrial ecosystems:

Native fauna

Dust may impact habitats which represent shelter, foraging and dispersal habitats for native fauna:

Given the distance from potential dust sources, dust is expected to have a negligible impact on native fauna.

Noise Air: windborne noise emissions generated during construction activities

Residential:

None, the nearest receptors are the residents of the township of Paraburdoo, more than 6 km away.

Health and amenity:

Given the distance to the nearest receptor, noise generated during construction is not expected to affect public health or amenity.

Environmental Protection (Noise) Regulations 1997 and standard operating procedures are expected to effectively mitigate the risk of noise during construction. Specific controls are not proposed.

Minor Rare Low Risk pathway is low, detailed assessment is not required.

Terrestrial ecosystems: Native fauna, including the Common Sandpiper.

Noise is unlikely to affect the species. It has been identified as a non-breeding visitor to all states and territories.

Noise generated during construction is expected to be limited and as such, is expected to have a negligible impact on native fauna.

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Source Potential Emissions

Potential Pathway Potential Receptors Potential Impacts Proposed Controls Consequence Likelihood Risk Rating Detailed Assessment Required?

Light Air: light spill generated during construction activities

Residential:

None, the nearest receptors are the residents of the township of Paraburdoo, more than 6 km away.

Health and amenity:

Given the distance to the nearest receptor, light emissions are not expected to affect health or amenity.

Light spill will be managed via the requirements of the Works Approval, Part V Licence L5275/1972 and standard operating procedures, including:

- Lighting design in areas that require night lighting will ensure light is directed to work areas and minimal light spill occurs (including use of directional lighting and covered lenses).

Standard management procedures are expected to effectively mitigate the risk of light spill during construction.

Minor Rare Low Risk pathway is low, detailed assessment is not required.

Terrestrial ecosystems: Most construction activities will be conducted in daylight hours. Light spill during construction is expected to be limited at night (when nocturnal native fauna are foraging), and as such, is expected to have a negligible impact on native fauna.

Hydrocarbons from fuel storage and refuelling during construction

Hydrocarbon spill causing soil contamination

Land Soil contamination

Hydrocarbons will be managed via relevant legislation (including Australian Standard AS 1940-2004: Storage and handling of flammable and combustible liquids), the requirements of the Works Approval, Part V Licence L5275/1972 and standard operating procedures, including:

- Fuel storage tanks will be designed and constructed to AS 1940-2004: The storage and handling of flammable and combustible liquids;

- Management structures (bunding / secondary containment) will be installed at all hydrocarbon storage and refuelling facilities to ensure any spills are contained; and

- Spill response will be provided.

Standard hydrocarbon management procedures are expected to effectively mitigate the risk of hydrocarbon spills during construction

Minor Rare Low Risk pathway is low, detailed assessment is not required.

Seepage of hydrocarbon spill to groundwater causing contamination

Groundwater of beneficial use (suitable for stock watering): None, the vertical distance to groundwater is more than 10 m.

Groundwater contamination with potential impacts to beneficial use of the groundwater (and declining health of any vegetation dependent on groundwater):

Given the vertical distance to the groundwater, any hydrocarbon spills from storage and refuelling during construction are not expected to seep to groundwater (or affect any associated terrestrial ecosystems).

Terrestrial ecosystems: Vegetation, including vegetation communities of elevated conservation significance located within and adjacent to the Premises

Solid / Liquid Waste

General wastes generated during construction activities

Residential:

None, the nearest receptors are the residents of the township of Paraburdoo, more than 6 km away.

Health and amenity:

Given the distance to the nearest receptor, general wastes are not expected to affect public health or amenity.

General wastes will be managed via the requirements of the Works Approval, Part V Licence L5275/1972 and standard operating procedures including:

- Sufficient recycling and general waste collection areas will be established and labelled with the relevant waste type to facilitate the management of waste;

- Recyclable materials will be separated from other waste and recycled wherever possible; and

- Non-recyclable materials will be disposed of at an approved landfill facility.

Standard waste management procedures are expected to effectively mitigate the risk of general wastes during construction.

Minor Rare Low Risk pathway is low, detailed assessment is not required.

Terrestrial ecosystems: Native fauna

Local increase in feral fauna (scavengers attracted to putrescible wastes) could result in predation and replacement of native fauna.

Category 64: Class II putrescible landfill site

Operation of landfill facilities

Dust Air: windborne particulate (dust) emissions generated from unsealed surfaces during operation of landfill facilities

Residential:

None, the nearest receptors are the residents of the township of Paraburdoo, more than 6 km away.

Health and amenity:

Given the distance to the nearest receptor, dust generated from the landfill is not expected to affect public health or amenity.

Dust emissions will be managed via the Works Approval, Part V Licence L5275/1972 and standard operating procedures, including:

- clearing will be managed to ensure that areas are only cleared as required;

Minor Rare Low Risk pathway is low, detailed assessment is not required.

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Source Potential Emissions

Potential Pathway Potential Receptors Potential Impacts Proposed Controls Consequence Likelihood Risk Rating Detailed Assessment Required?

Terrestrial ecosystems: Vegetation, including vegetation communities of elevated conservation significance within and adjacent to the Premises.

Declining health of vegetation including reduced ability for photosynthesis due to dust deposition / smothering.

Given that native vegetation is expected to be reasonably tolerant to dust deposition, dust generated from the landfill is expected to have a negligible impact on vegetation health.

- rehabilitation of cleared areas will be implemented as construction is completed;

- dust suppression will be implemented (including use of water trucks, control of vehicle movements / restricted speeds) during operations;

- weather forecasts will be monitored, activities that have the potential to generate high dust levels may be restricted if there is a risk of windy conditions; and

- waste in landfill facilities will be covered so that no waste is left exposed.

Appropriate design, management, inspection and maintenance of landfill facilities is expected to mitigate the risk of dust emissions.

Odour associated with putrescible waste.

Air: windborne odour generated during disposal of putrescible waste

Residential:

None, the nearest receptors are the residents of the township of Paraburdoo, more than 6 km away.

Health and amenity:

Given the distance to the nearest receptor, any odour associated with putrescible waste is not expected to affect public health or amenity.

Odour emissions should also be negligible for a properly functioning landfill.

Putrescible wastes will be disposed of at landfill facilities, managed via the requirements of the Works Approval, Part V Licence L5275/1972/12 and standard operating procedures including.

- Total landfill waste will be 5,000 tonnes per annual period.

- Landfill facilities will only accept approved types of waste (putrescible wastes in waste dump landfills will be wooden only (not odorous));

- Landfill facilities will include a sign which clearly defines what waste is accepted; and

- Waste will be covered so that no waste is left exposed.

Appropriate design, management, inspection and maintenance of landfill facilities is expected to mitigate the risk of odour emissions.

Minor Rare Low Risk pathway is low, detailed assessment is not required.

Solid Waste Air: Windblown litter Residential:

None, the nearest receptors are the residents of the township of Paraburdoo, more than 6 km away.

Health and amenity:

Given the distance to the nearest receptor, any windblown litter associated with disposal of waste to the landfill is not expected to affect public health or amenity.

Wastes will be managed via the requirements of the Works Approval, Part V Licence L5275/1972 and standard operating procedures including:

- Sufficient recycling and general waste collection areas will be established and labelled with the relevant waste type to facilitate the management of waste;

- Recyclable materials will be separated from other waste and recycled wherever possible;

- Non-recyclable materials will be disposed of at an approved landfill facility;

- Total landfill waste will not exceed 5,000 tonnes per annual period;

- Landfill facilities will only accept approved types of waste;

- Putrescible landfill facilities will be fenced to an appropriate height, gated and locked to contain windblown waste and exclude scavenging animals;

- Fencing surrounding the perimeter of putrescible landfill facilities will be regularly inspected for damage and cleared of waste;

- Landfill facilities will include a sign which clearly defines what waste is accepted; and

- Waste will be covered so that no waste is left exposed.

Appropriate design, management, inspection and maintenance of landfill facilities is expected to mitigate the risk of windblown litter.

Minor Rare Low Risk pathway is low, detailed assessment is not required.

Terrestrial ecosystems: Native fauna

Local increase in feral fauna (scavengers attracted to putrescible wastes) could result in predation and replacement of native fauna.

Minor Unlikely Medium Detailed assessment provided in Section 13

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Source Potential Emissions

Potential Pathway Potential Receptors Potential Impacts Proposed Controls Consequence Likelihood Risk Rating Detailed Assessment Required?

Liquid Waste Seepage of landfill leachate to soil or groundwater, adverse impacts to the health of vegetation dependent upon groundwater.

Land Soil contamination (nutrients, heavy metals)

Wastes will be managed via the requirements of the Works Approval, Part V Licence L5275/1972 and standard operating procedures including:

- Landfill facilities will be located more than 100 m from any permanent or perennial watercourse;

- Landfill facilities will be located so that vertical distance between the waste and the highest seasonal and expected post mining ground water level is no less than 3 m (waste dump landfill) or 10 m (putrescible landfill);

- Landfill facilities will only accept approved types of waste;

- Landfill facilities will include a sign which clearly defines what waste is accepted;

- Surface water management structures (i.e. bunding) will divert surface water away from landfill facilities;

- A sump or bunding will collect any surface water that has come into contact with waste; and

- Waste will be covered so that no waste is left exposed.

- Groundwater monitoring will occur downstream of landfill facilities, monitoring potential any changes to groundwater quality.

Appropriate design, management, inspection and maintenance of landfill facilities is expected to mitigate the risk of soil, groundwater or surface water contamination from landfill leachate.

Minor Unlikely Medium

Detailed assessment provided in Section 13

Groundwater of beneficial use: None, the vertical distance to groundwater is more than 10 m.

Deterioration of groundwater quality with potential impacts to beneficial use of the groundwater (and declining health of any vegetation dependent on groundwater):

Migration of landfill leachate could also result in contamination or elevated nutrient levels (eutrophication) in surface water. However, the proposed landfill facilities will be located where the vertical distance to groundwater is more than 10 m and where the distance to the nearest (ephemeral) surface water, Turee Creek is more than 3 km. Any future landfill facilities will be located where the vertical distance to groundwater is more than 3 m below ground level (waste dump landfill) or 10 m below ground level (putrescible landfill) and where the distance to any permanent or perennial watercourse is more than 100 m.

Given the depth to groundwater and distance to the nearest surface water, landfill leachate is not expected to seep to groundwater or migrate to surface water.

Terrestrial ecosystems: Riparian vegetation of Turee Creek and Seven Mile Creek ( approx. 3 km from TSF1).

Migration of landfill leachate could result in contamination or elevated nutrient levels (eutrophication) in surface water.

Surface water: The nearest surface water receptors are within 3 km from the Landfill with ephemeral creeks flowing from the TSF.

Surface water contamination or eutrophication (and declining health of riparian vegetation):

Given the distance to the nearest surface water, any landfill leachate is not expected to migrate to surface water (or affect any associated terrestrial ecosystems).

Riparian vegetation of Turee Creek and Seven Mile Creek (approx. 3 km from TSF1).

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13 EMISSIONS, MANAGEMENT AND CONTROLS

The Licensee operates under an integrated Health, Safety, Environment and Communities and Social (HSEC) Management System which includes processes, procedures and plans that ensure environmental controls are developed for key environmental risks, legal compliance is maintained and continuous improvement is achieved through a formal review process. Subject to approval, the construction, commissioning and operation of the proposed facility will be in accordance with the requirements of the HSEC Management System, the Works Approval and Licence L5275/1972 (and any amendments, as required). A detailed risk assessment has been undertaken for any activity in Table 12-5 which has been identified as having a ‘Medium’ risk rating or higher. Risks associated with the TSF1 Northern Cell operation have been addressed in Section 10.0 and 11.0 of the Paraburdoo Tailings Storage Facility Part V Works Approval Application Supporting Documentation provided in Attachment 1

13.1 Discharges to the Environment – Windblown litter

13.1.1 Description of Risk Event

The operation of the proposed landfill facilities (putreciable) could potentially result in windblown litter causing a localised increase in feral fauna (scavengers attracted to putrescible wastes) which could result in predation and replacement of native fauna.

13.1.2 Proposed Environmental Controls

Landfill facilities are proposed to be located and managed in accordance with specific criteria limiting impacts to potential receptors. Management controls are detailed in sections 6.3 and 6.4 and include specific location, design and management (e.g. coverage) controls. Appropriate design, management, inspection, and maintenance controls are expected to effectively mitigate the risk of increases in feral fauna competing with native wildlife.

13.1.3 Residual Risk to the Environment

The Licensee considers that the residual risk to the environment from windblown litter from the proposed facilities is ‘low’ given the proposed environmental controls to be implemented.

13.2 Discharges to the Environment – Liquid Waste

13.2.1 Description of Risk Event

The operation of the proposed landfill facilities could potentially result in seepage of landfill leachate to soil or groundwater. Migration of landfill leachate could also result in contamination or elevated nutrient levels (eutrophication) in surface water.

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13.2.2 Proposed Environmental Controls

Distance to ground water level and operational controls are the key controls to manage this risk. As per the commitments, the proposed landfill is located more than 3 m above ground level. Bores in the vicinity of the proposed landfill show that groundwater levels are recorded as between 30 to 90 mbgl meeting this commitment. Any future landfill facilities will be located where the vertical distance to groundwater is more than 3 m below ground level (waste dump landfill) or 10 m below ground level (putrescible landfill) and where the distance to any permanent or perennial watercourse is more than 100 m. Landfill facilities are proposed to be managed in accordance with specific criteria limiting pathways to potential receptors. Management controls are detailed in sections 6.3 and 6.4 and include specific location, design and management (e.g. coverage) controls. Appropriate design, particularly distance to ground water levels, management, inspection and maintenance controls are expected to effectively mitigate the risk of potentially contaminated discharges from landfills.

13.2.3 Residual Risk to the Environment

The Licensee considers that the residual risk to the environment from potentially contaminated discharges (soil contamination, seepage to groundwater or migration to surface waters) from the proposed facilities is ‘low’ given the distance from sources to potentially sensitive receptors and the proposed environmental controls to be implemented. Given the depth to groundwater and distance to the nearest surface water, landfill leachate is not expected to seep to groundwater or migrate to surface water. The risk to groundwater quality, surface water quality and any associated terrestrial ecosystems is therefore considered low.

14 REHABILITATION AND CLOSURE

Closure plans document the most up to date closure knowledge base for the operation, outline the objectives that need to be met upon closure, set out the strategies to achieve the closure objectives and the criteria that will be used to assess the success of closure. The closure concept of TSF1 north is detailed in the “Paraburdoo Closure Plan” (RTIO, 2019b). The concept proposed the use of a shedding cover to rehabilitate the surface of the tailings. The cover will be designed to match the sloped tailings beach surface at the time of decommissioning as closely as possible to minimise the volume of earthworks required. The properties of the tailings will be considered in determining the required thickness of the capping layer to reduce impacts on future vegetation growth.

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15 PROJECT COSTS

The following information has been provided to support the Total Works Approval Fee calculation of $16 4433.00

Table 15-1: Estimated Project Costs

Proposed Costs Description Costs (AUD)

TSF1 Northern Cell Embankment Raise $11 000 000.00

Waste Dump Landfill $100 000.00

Total Costs $11 100 000.00

Cost category – More thank $10 000 000, but not more than $15 000 000.00

$16 443.00

Table 15-2: Prescribed Premise category related to application

Category Number

Category Description Capacity Range

5 Processing or beneficiation of metallic or non-metallic ore

More than 5 000 000 tonnes per year

64 Class II putrescible landfill site More than 5 000 but no more than 50 000 tonnes per year

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REFERENCES ANCOLD, 2012. Guidelines on Tailings Dams: Planning, Design, Construction, Operation and Closure, Australian National Committee on Large Dams, May 2012. ANZECC 2000. Australian and New Zealand Guidelines for Fresh and Marine Water Quality, Volume 1. Australian and New Zealand Environment and Conservation Council, Agriculture and Resource Management Council of Australia and New Zealand. October 2000. DWER 2017 Guideance Statements – Risk Assessment EGi, 2007. Paraburdoo Geochemical Characterisation and ARD Assessment of Fine Tailings from Paraburdoo. April 2007. Report 3805-5/754 by Environmental Geochemistry International Pty Ltd. GHD 2020a. Paraburdoo Tailings Storage Facility Part V Works Approval Application Supporting Documentation. Report Reference 12510535. June 2020. GHD 2020b Paraburdoo Tailings Storage Facility PFS Pre-Feasibility Study Report. Revision 0. Report Reference 12510535. June 2020. Knight Piésold 2017: Paraburdoo Mine Operational Tailings Samples Testing Rio Tinto, 2016a. Seepage Assessment -Paraburdoo Tailings Storage Facility (TSF). Report reference: RTIO-PDE-0147681. Report dated November 2016. Rio Tinto, 2016b. Paraburdoo Iron Ore Mine. MINING PROPOSALTailings Storage Facility Southern Cell Expansion ‐ Version 2 General Purpose Leases 14SA & 4SA. Report Reference RTIO-HSE-0294773. Report dated October 2016. Rio Tinto, 2017. 2016 Review of Existing Water Quality Data Greater Paraburdoo. Report reference: RTIO-PDE-0154092. Report dated September 2017 Rio Tinto, 2019a. 4East Extension &Western Range Hydrogeological Assessment. Report reference: RTIO-PDE-0163098. Report dated January 2019 RTIO, 2019b. Paraburdoo Closure Plan 2019. Report Reference RTIO-HSE-0071355. Report (version 1) dated September 2019.

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Appendix 1

Paraburdoo Tailings Storage Facility Part V Works Approval Application Supporting Documentation (GHD, 2020a)

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Appendix 2

Proposed Landfill – Distance to Groundwater

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Provided in Table A1-1 below are the locations of bores surrounding the proposed Landfill and the depth to groundwater (recorded in 2019). Table A1-1 Landfill Monitoring Bores

Monitoring Bore ID GDA94 X GDA 94 Y Depth to GW (mbgl)

MB0910E01 562044.4094 7429251.299 49.56

MB0910E02 562477.8978 7428768.958 37.01

MB18TSF0001 562932.6 7428445 38.32

MB18TSF0002 562844.6 7428245 30.17

MB18TSF0003 561789.7 7428334 27.89

PTD22D 562509.266 7428430.822 31.57

PZ084E0002 562264.3172 7429376.968 95.3

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Appendix 3

Flocculant Safety Data Sheet