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BROWNS RANGE RARE EARTHS PROJECT
ASSESSMENT ON PROPONENT INFORMATION – ENVIRONMENTAL REVIEW EPA ASSESSMENT NO: 1973
Northern Minerals ABN: 61 119 966 353
Level 1, 675 Murray Street, West Perth WA 6005 PO Box 669, West Perth WA 6872
Quality information
Document Browns Range Rare Earths Project – API – Environmental Review
Ref EPA Assessment No: 1973
Date June 2014
Prepared by Northern Minerals
Reviewed by R Jones
Revision Revision date Details Name
0 3/4/2014 Draft for OEPA review R Jones
1 13/6/2014 For OEPA assessment R Jones
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TABLE OF CONTENTS
1 INTRODUCTION ........................................................................................................................... 1-1 1.1 Overview .............................................................................................................................. 1-1 1.2 Purpose of document........................................................................................................... 1-2 1.3 Key project characteristics ................................................................................................... 1-2 1.4 Key project characteristics ................................................................................................... 1-3 1.5 The proponent ..................................................................................................................... 1-5 1.6 Regional setting.................................................................................................................... 1-5
2 DESCRIPTION OF PROPOSAL ....................................................................................................... 2-1 2.1 Tenure .................................................................................................................................. 2-1 2.2 The Browns Range deposits ................................................................................................. 2-1 2.3 Justification for proposal ..................................................................................................... 2-3 2.4 Mining .................................................................................................................................. 2-5
2.4.1 Mining methods ........................................................................................................... 2-5 2.4.2 Mine dewatering .......................................................................................................... 2-6 2.4.3 Waste rock management ............................................................................................. 2-6
2.5 Ore processing ................................................................................................................... 2-10 2.5.1 Beneficiation .............................................................................................................. 2-10 2.5.2 Hydrometallurgy ........................................................................................................ 2-11
2.6 Tailings disposal and storage ............................................................................................. 2-13 2.7 Management of radioactivity ............................................................................................ 2-14
2.7.1 Introduction ............................................................................................................... 2-14 2.7.2 Naturally occurring background radioactivity ........................................................... 2-15 2.7.3 Key actions for radiation management ...................................................................... 2-19
2.8 Support infrastructure ....................................................................................................... 2-20 2.8.1 Power supply .............................................................................................................. 2-20 2.8.2 Water supply .............................................................................................................. 2-20 2.8.3 Roads and transport ................................................................................................... 2-21 2.8.4 Accommodation ......................................................................................................... 2-21 2.8.5 Airstrip ........................................................................................................................ 2-21 2.8.6 Borrow pits ................................................................................................................. 2-21
2.9 Mine rehabilitation and closure ......................................................................................... 2-22 2.10 Alternatives considered ..................................................................................................... 2-24
2.10.1 Processing options ..................................................................................................... 2-24 2.10.2 Location of hydrometallurgical processing facility .................................................... 2-24 2.10.3 Location of tailings storage facility ............................................................................ 2-26 2.10.4 Tailings disposal options ............................................................................................ 2-26 2.10.5 Water supply and management options ................................................................... 2-29
3 STAKEHOLDER ENGAGEMENT ..................................................................................................... 3-1 4 ENVIRONMENTAL IMPACTS AND MANAGEMENT ...................................................................... 4-1
4.1 General approach................................................................................................................. 4-1 4.2 Preliminary key factors ........................................................................................................ 4-1 4.3 Other potential impacts and activities ................................................................................. 4-2
5 INLAND WATERS: SURFACE WATER ............................................................................................ 5-1 6 INLAND WATERS: GROUNDWATER ............................................................................................. 6-1 7 TERRESTRIAL VEGETATION AND FLORA ...................................................................................... 7-1 8 TERRESTRIAL VERTEBRATE FAUNA ............................................................................................. 8-1 9 TERRESTRIAL INVERTEBRATE FAUNA .......................................................................................... 9-1 10 SUBTERRANEAN FAUNA ............................................................................................................ 10-1 11 REHABILITATION AND CLOSURE ............................................................................................... 11-1 12 OTHER POTENTIAL IMPACTS AND ACTIVITIES .......................................................................... 12-1
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13 BIODIVERSITY OFFSETS .............................................................................................................. 13-1 14 SUMMARY AND CONCLUSIONS ................................................................................................ 14-1 15 GLOSSARY, ACRONYMS AND ABBREVIATIONS ......................................................................... 15-1 16 REFERENCES .............................................................................................................................. 16-1
FIGURES
Figure 1-1: Location of the Browns Range Project .............................................................................. 1-1 Figure 1-2: Schematic of Browns Range Project activities ................................................................... 1-2 Figure 1-3: Browns Range Project Development Envelope ................................................................. 1-4 Figure 1-4: Regional setting ................................................................................................................. 1-6 Figure 2-1: Browns Range Project – mine site layout .......................................................................... 2-2 Figure 2-2: Periodic table showing rare earth elements ..................................................................... 2-3 Figure 2-3: Criticality of rare elements in the short term (0–5 years) ................................................. 2-4 Figure 2-4: Distribution of rare earth elements in Browns Range ore ................................................ 2-5 Figure 2-5: Schematic of Wolverine, Gambit West and Gambit mines ............................................... 2-6 Figure 2-6: Ore and waste rock mined during Years 1 through 5 ........................................................ 2-7 Figure 2-7: Simplified process flowsheet ........................................................................................... 2-10 Figure 2-8: Beneficiation circuit flowsheet ........................................................................................ 2-11 Figure 2-9: Hydrometallurgical plant flowsheet ................................................................................ 2-12 Figure 2-10: Estimated disturbance by closure domain .................................................................... 2-24 Figure 2-11: Locations assessed during options study for ore processing facility ............................. 2-25 Figure 2-12: Location options for the tailings storage facility ........................................................... 2-28 Figure 5-1: Regional hydrology ............................................................................................................ 5-5 Figure 5-2: Regional sub-catchments................................................................................................... 5-6 Figure 5-3: Proposed surface water management measures .............................................................. 5-7 Figure 6-1: Hydrogeological features ................................................................................................... 6-9 Figure 6-2: Water modelling – borefield drawdown contours .......................................................... 6-10 Figure 7-1: Vegetation associations occurring within proposed Project area (north) ........................ 7-5 Figure 7-2: Vegetation associations occurring within proposed Project area (south) ........................ 7-6 Figure 8-1: Vertebrate fauna habitats ................................................................................................. 8-6 Figure 9-1: Short-range endemic invertebrate habitats ...................................................................... 9-3 Figure 10-1: Extent of Browns Range Metamorphics ........................................................................ 10-3 Figure 10-2: Browns Range Metamorphics – cross section ............................................................... 10-1
TABLES
Table 1-1: Key project characteristics .................................................................................................. 1-3 Table 2-1: Global JORC compliant Mineral Resource Estimate for four deposits at Browns Range ... 2-1 Table 2-2: Estimated waste rock tonnages by deposit ........................................................................ 2-7 Table 2-3: Typical trace elements concentrations in Browns Range waste rock ................................. 2-9 Table 2-4: Sources of tailings for disposal and storage in the tailings storage facility ...................... 2-13 Table 2-5: Criteria and assumptions used for design of the tailings storage facility ......................... 2-14 Table 2-6: Average uranium and thorium content of Browns Range soils and rock ......................... 2-15 Table 2-7: Background gamma radiation results ............................................................................... 2-15 Table 2-8: Seasonal average radon and thoron concentration in air ................................................ 2-16 Table 2-9: Summary of Browns Range groundwater baseline radionuclide analysis ........................ 2-16 Table 2-10: Summary of dust deposition results ............................................................................... 2-17 Table 2-11: Activity concentrations in Browns Range ore ................................................................. 2-18 Table 2-12: Predicted radionuclide concentrations in processing plant streams.............................. 2-19 Table 2-13: Estimated disturbance by project element..................................................................... 2-23 Table 2-14: Assessed locations and preference ranking .................................................................... 2-25
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Table 3-1: Summary of consultation to end May 2014 ....................................................................... 3-2 Table 4-1: Planned and completed studies for the Browns Range Rare Earths Project ...................... 4-3 Table 4-2: Supporting studies timeline ................................................................................................ 4-5 Table 4-3: EPA Guidance Statements, Environmental Assessment Guidelines, and Policies – outline of application in this assessment ............................................................................................................. 4-6 Table 4-4: Summary of key findings for the Browns Range Rare Earths Project ................................. 4-7 Table 5-1: Environmental factor: inland waters (surface water) ......................................................... 5-1 Table 6-1: Environmental factor: inland waters (groundwater) .......................................................... 6-1 Table 6-2: Summary of groundwater quality monitoring .................................................................... 6-6 Table 7-1: Environmental factor: terrestrial vegetation and flora ...................................................... 7-1 Table 7-2: Priority Flora and other species of conservation significance recorded in the Study Area 7-7 Table 8-1: Environmental factor: terrestrial vertebrate fauna ............................................................ 8-1 Table 9-1: Environmental factor: terrestrial invertebrate fauna (SRE invertebrate fauna) ................ 9-1 Table 10-1: Environmental factor: subterranean fauna .................................................................... 10-1 Table 11-1: Environmental factor: rehabilitation and closure ........................................................... 11-1 Table 12-1: Other potential impacts and activities – other legislation and approvals ...................... 12-1
APPENDICES
Appendix A: Environmental Scoping Guideline (July 2013) Appendix B: Browns Range Hydrogeology Appendix C: Geochemical Characterisation of Browns Range Waste Rock Appendix D: Preliminary Tailings Design Report Appendix E: Geotechnical testing of Browns Range tailings Appendix F1: Baseline Soils Characterisation Appendix F2: Analogue slopes soil and vegetation assessment Appendix G: Preliminary Geochemical Characterisation of Tailings Appendix H: Water Supply Investigations Appendix I: Surface Hydrology Appendix J: Vegetation and Flora Appendix K: Terrestrial Vertebrate Fauna Appendix L1: Short Range Endemic Invertebrates – baseline survey Appendix L2: Targeted Mygalomorph Spider Survey Appendix L3: Short Range Endemic Invertebrates - assessment Appendix M: Subterranean Fauna Appendix N: Air Quality Appendix O: Noise Appendix P1: Conceptual Mine Closure Plan Appendix P2: Pit lake assessment Appendix P3: Ecotox assessment Appendix P4: Pit lake impacts on fauna Appendix P5: Runoff sediment study Appendixt P6: TSF cover modelling Appendix Q1: Radiological Assessment of Tailings Appendix Q2: Radiation technical report Appendix R: Environmental Offsets Reporting Form
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1 INTRODUCTION
1.1 Overview
Northern Minerals Limited (NML) proposes to develop a rare earths mine and mineral processing operation at a location approximately 160 km south-east of Halls Creek, Western Australia. The project area is adjacent to the Western Australian/Northern Territory border (Figure 1-1). Northern Minerals holds the mineral rights to an extensive area of exploration tenements centred on the Browns Range dome, which straddles the Western Australian/Northern Territory border. To date, the exploration effort has focussed on targets in Western Australia, where the Company has discovered heavy rare earth dominant xenotime mineralisation. The Browns Range Rare Earth Project involves mining and processing activities only in WA.
Figure 1-1: Location of the Browns Range Project
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1.2 Purpose of document
The Western Australian Environmental Protection Authority (EPA) has determined that the environmental impacts associated with the Browns Range Rare Earth Proposal be assessed through the ‘Assessment on Proponent Information’ (API) – category A process. The EPA issued an Environmental Scoping Guideline for the Project on 26 July 2013 (Appendix A). This API document aims to satisfy EPA’s environmental impact assessment requirements, as described in the Environmental Scoping Guideline and in other relevant EPA publications (refer to Table 4-3).
1.3 Key project characteristics
The proposed Browns Range Rare Earths Project (the Project) comprises:
mining of xenotime ore from four deposits (Wolverine, Gambit, Gambit West and Area 5), initially using open cut mining methods, then transitioning to underground mining to access deeper ore bodies
treatment of ore to produce a mixed rare earth (RE) oxide product
transport of product by road to an export facility at Wyndham or Darwin.
Figure 1-2: Schematic of Browns Range Project activities
In addition to mining and processing of ore and shipment of mixed RE oxide product (Figure 1-2), the Project involves a range of related activities, including:
excavation and storage of overburden and waste rock
storage of wastes from ore processing (tailings)
mine dewatering and the construction and operation of a water supply borefield
transport, storage and use of fuels and reagents
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construction and operation of process water supply and evaporation ponds (both lined with a geomembrane to control seepage)
construction and operation of a mine accommodation village, power generating facilities, an airstrip, a landfill, water and sewage treatment facilities
upgrade or construction of mine access and haul roads
mine decommissioning, rehabilitation and closure.
1.4 Key project characteristics
Key characteristics of the Proposal are summarised in Table 1-1 and the development envelop is shown in Figure 1-3. A detailed project description is provided in Section 2.
Table 1-1: Key project characteristics
Proposal Title Browns Range Rare Earths Project
Proponent Name Northern Minerals Ltd
Short Description A proposed rare earths mine and processing facility at Browns Range, about 160 km south-east of Halls Creek in the Shire of Halls Creek
Life of Project (not including construction and closure phases)
10 years
Element Location Quantity or extent
Physical components
Mine pits and underground operations Figure 2-1 Clearing of no more than 711 ha within an 2,590 ha development envelope
Waste rock landforms Figure 2-1
Ore processing facilities and evaporation dam Figure 2-1
Tailings storage facility Figure 2-1
Other infrastructure (accommodation village, workshops and laydown areas, water management structures ,airstrip, telecommunications infrastructure and power supply, gravel and clay borrow pits, a landfill, haul roads and access roads)
Figure 2-1
Operational elements
Water abstraction from borefield Figure 2-1 Up to 1.3 GL/year
Mine dewatering (cumulative across all deposits)
Figure 2-1 Up to 0.79 GL/year
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Figure 1-3: Browns Range Project Development Envelope
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1.5 The proponent
The proponent for the Proposal is:
Northern Minerals Limited Level 1, 675 Murray Street WEST PERTH Western Australia 6005 ABN: 61 119 966 353
The key contact for this Proposal is:
Mr Robin Jones Project Manager Northern Minerals Limited PO Box 669 WEST PERTH Western Australia 6872 Tel: +61 08 9481 2344 Fax: +61 08 9481 5929 Email: rjones@northernminerals.com.au Website: http://www.northernminerals.com.au/
1.6 Regional setting
The Project area is located in the upper Sturt Creek Basin, in the southeastern Kimberley region, at the northern edge of the Tanami Desert (Figure 1-4). This area was traditionally owned by people of the Jaru language group.
The first non-Indigenous exploration of the region occurred in the mid-1800s. Traditional hunting and gathering continued into the late 19th century. Use of the land for cattle drives and other pastoral purposes increased from the 1880s to the 1920s. A pastoral station (Soakage Creek Station) was established at the site of the existing Gordon Downs pastoral lease in 1887. The Project lies within the Gordon Downs pastoral lease. Customary Aboriginal land uses and pastoral land use remain the dominant land uses in the project area.
The settlement of Kundat Djaru (Ringer Soak) was established in the mid-1980s on land excised from the Gordon Downs pastoral station. The land on which the township lies and a parcel of land lying mainly to the south of it have been formally gazetted as Crown Reserve 37670 under the Aboriginal Affairs Planning Authority Act 1972. The community is incorporated as the Kundat Djaru Aboriginal Corporation.
The closest Department of Parks and Wildlife (DPaW)-managed lands to the Project area include the Ord River Regeneration Reserve, located approximately 100 km north-west of the Project and the Wolfe Creek Meteorite Crater National Park, located approximately 120 km to the west-southwest.
The closest proposed protected area is the Gardiner Range proposed conservation area, located south and west of the Project. The proposed upgrade of the existing access track to Browns Range will occur within the northern part of the proposed Gardiner Range conservation area.
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Figure 1-4: Regional setting
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2 DESCRIPTION OF PROPOSAL
2.1 Tenure
The activities described in this API would take place on one mining lease tenement (M80/627) and two miscellaneous licence tenements (L80/76 and L80/77). The miscellaneous licence tenements would generally be used for linear infrastructure (pipelines, roads, power transmission) and support facilities (water abstraction). Mining, ore processing and storage of mine waste would occur on the mining lease tenement. The mine accommodation village, airstrip and power generating plant would also be located on the mining lease tenement.
Applications for grant of these tenements were lodged with the Department of Mines and Petroleum in November 2013 and January 2014, respectively. The locations and extents of the tenements included in this API are shown in Figure 2-1. The whole of the proposed Browns Range Project would occur on land that lies within the Gordon Downs pastoral station. The Project lies within the registered Jaru Native Title Claim (WAD45/2012) with the exception of a section of the proposed access road which falls under the Tjurabalan Native Title Claim (WAD160/1997).
2.2 The Browns Range deposits
Northern Minerals has identified four deposits containing economic resources of heavy rare earth elements in a xenotime (yttrium phosphate) mineralisation which occurs within hydrothermal silicified and hematitic breccias. The deposits and the ore they contain are listed in Table 2-1.
Table 2-1: Global JORC compliant Mineral Resource Estimate for four deposits at Browns Range
Deposit Category Mt TREO2
(%) Dy2O3
(kg/t) Y2O3
(kg/t) Tb4O7
(kg/t) HREO3
(%) TREO
(t)
Wolverine Indicated 2.66 0.89 0.78 5.17 0.12 89 23,705
Inferred 1.80 0.81 0.67 4.45 0.10 87 14,564
Total1 4.46 0.86 0.74 4.88 0.11 88 38,269
Gambit West Indicated 0.27 1.26 1.07 7.06 0.14 90 3,424
Inferred 0.12 0.64 0.54 3.67 0.07 85 753
Total1 0.39 1.07 0.91 6.04 0.12 89 4,177
Gambit Indicated 0.05 1.06 0.92 6.62 0.12 97 533
Inferred 0.06 1.20 1.01 6.80 0.15 95 671
Total1 0.11 1.13 0.97 6.72 0.13 96 1,204
Area 5 Indicated 1.38 0.29 0.18 1.27 0.03 69 3,953
Inferred 0.14 0.27 0.17 1.17 0.03 70 394
Total1 1.52 0.29 0.18 1.26 0.03 69 4,347
Total1 Indicated 4.37 0.72 0.61 4.07 0.09 83 31,615
Inferred 2.12 0.77 0.64 4.25 0.09 86 16,382
Total1 6.48 0.74 0.062 4.13 0.09 84 47,997
Notes: 1. Rounding may cause some computational discrepancies (TREO (metal) tonnes estimated from Mt x TREO%). 2. TREO = Total Rare Earth Oxides – La2O3, CeO2, Pr6O11, Nd2O3, Sm2O3, Eu2O3, Gd2O3, Tb4O7, Dy2O3, Ho2O3, Er2O3, Tm2O3, Yb2O3, Lu2O3, Y2O3. 3. HREO = Heavy Rare Earth Oxides – Total of Sm2O3, Eu2O3, Gd2O3, Tb4O7, Dy2O3, Ho2O3, Er2O3, Tm2O3, Yb2O3, Lu2O3, Y2O3.
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Figure 2-1: Browns Range Project – mine site layout
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2.3 Justification for proposal
‘Rare earths’ are a group of 16 moderately abundant chemical elements. They comprise yttrium (Y) and the lanthanides, a group of 15 chemically similar elements, including lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) and lutetium (Lu) (refer Figure 2-2).
Figure 2-2: Periodic table showing rare earth elements
Rare earths have diverse and useful properties. The rare earth magnet market is already mature and large, particularly in consumer electronics applications such as hard disk drives and smart phones. Small amounts of neodymium and dysprosium in some alloys increase permanent magnet strength by orders of magnitude, enabling miniaturisation of telecommunications devices and other electronic equipment, and also providing greater efficiency in energy efficiency applications such as wind turbines. Future growth in demand for rare earths is expected to be dominated by the use of rare earth elements in the manufacture of magnets, batteries and other components used in wind turbines, hybrid and electric cars, and other energy efficient technologies. Other applications requiring rare earth elements include production of phosphors, used for low-emission lighting and in the efficient thin-film semi-conductors for solar panels, and manufacture of hydrogen fuel cells (Jepson, 2012). Yttrium and some other rare earth elements also have medical applications.
For a range of geological, technical and geopolitical reasons, rare earths are currently considered the most ‘critical’ commodity at a global scale. A commodity is described as ‘critical’ when the risks of supply shortage and their impacts on the economy are higher than for most of the other raw materials (European Commission, 2010). In general, the heavy rare earth (HRE) elements are considered more critical than elements classified as light rare earths (LRE) (Figure 2-3). The heavy
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rare earth elements are defined as those with atomic numbers 62 through 71 (samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium). Yttrium, atomic number 39, is included in the HRE group based on its similar ionic radius and similar chemical properties.
Source: after Bauer et al (2010)
Figure 2-3: Criticality of rare elements in the short term (0–5 years)
China dominates production and currently accounts for 97% of the world’s rare earth mining (Jepson, 2012). Geoscience Australia considers that current and medium-term demand for light rare earth elements will probably be met with existing and planned new global production, but a shortfall in heavy rare earth elements production is projected (Skirrow et al, 2013). The Industrial Minerals Company of Australia (IMCOA) believes that only 15% (or less) of the global demand for heavy rare earth elements will be able to be met from sources outside of China in 2015.
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The xenotime deposits targeted by the Project are unusual in that they contain high proportions of heavy rare earth elements (Figure 2-4). The two most abundant rare earths at the Project are
dysprosium (Dy) and yttrium (Y), which are primarily used in rare earth magnets and energy efficient lighting, respectively. Both of these elements are considered as critical commodities. The Project is well placed to supply a strategically important commodity to support growing global demand for clean and energy efficient technologies. The Project resource occurs in a particularly disadvantaged part of regional Australia and implementation of the Browns Range Rare Earths Project has the potential to realise both social and economic benefits for the local and regional population.
Figure 2-4: Distribution of rare earth elements in Browns Range ore
2.4 Mining
2.4.1 Mining methods
Mining will be undertaken at each deposit using conventional open pit methods of drill and blast, load and haul. The largest of the proposed pits is the Wolverine pit. At its maximum extent, it will have a diameter of approximately 500 m, roughly twice the size of the Subiaco football oval.
Two deposits, Wolverine and Gambit West, will also have an underground mining phase. Underground operations will be developed from declines in each pit which will be established prior to the completion of open pit mining. Underground mining is proposed to be conducted using long hole retreat stoping mining methods which are suitable for steeply dipping ore bodies. At Wolverine, the portal and decline will be established approximately 50 m below surface in the Wolverine pit (Figure 2-5). This will enable underground ore production to commence before the open pit is
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complete. The portal location for Gambit West will be approximately 10 m above the bottom of the final Gambit West pit.
Figure 2-5: Schematic of Wolverine, Gambit West and Gambit mines
2.4.2 Mine dewatering
Typical depths to groundwater in the Project area range from about 10 m to about 45 m below ground level. As the depth of the proposed mine pits will range from approximately 40 m (in the central part of the Gambit deposit) to over 150 m (at Wolverine), mine dewatering will be required at each of the proposed mining operations areas.
Field pump tests have shown that the rate of groundwater inflow into the mine workings is generally expected to be low. Accordingly, it is likely that pits will be dewatered by pumping from in-pit sumps. The maximum inflow of groundwater into the Gambit West pit and underground operations was conservatively estimated at 27 L/s (Appendix B). The estimated maximum inflows for other operations are 23 L/s (Wolverine), 13 L/s (Area 5) and 9 L/s (Gambit). Actual inflows at any one time will be dependent on the stage of development of the particular operation. The water will be pumped to surface storage facilities for use in mineral processing and dust suppression.
2.4.3 Waste rock management
Most waste rock will be generated during the early stage of the Project (Years 1 through 3) when ore is being mined using open pit methods. The ratio of waste rock to ore will vary over time, decreasing as the depth of mining advances. The amount of ore recovered will remain relatively constant at approximately 750,000 tpa over the life of the Project (Figure 2-6). Once underground mining has commenced, very little waste rock will report to surface storages. Instead, waste rock is proposed to be backfilled into underground workings.
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Figure 2-6: Ore and waste rock mined during Years 1 through 5
The expected waste rock production from open pit and underground mining over the life of the project is shown in Table 2-2.
Table 2-2: Estimated waste rock tonnages by deposit
Deposit Waste rock1 (t)
Approximate footprint of waste landform (ha)
Wolverine 14,500,000 57
Gambit 1,750,000 642
Gambit West 2,300,000
Gambit Central 700,000
Area 5 2,600,000 13
Total 21,850,000 134
Note: 1. Rounded to nearest 1,000 t. 2. Area for Gambit/Gambit West waste rock landform does not include area occupied by tailings storage cells.
Three waste rock landforms (WRLs) will be constructed to store this material: one each at Wolverine, Gambit/Gambit West and Area 5 (see Figure 2-1). Each WRL will be constructed in accordance with Department of Mines and Petroleum guidelines to ensure that the structure is safe, stable and not prone to significant erosion. The Gambit/Gambit West waste rock landform will adjoin the tailings storage facility (TSF), forming an integrated waste rock landform. The maximum height of the waste landforms will be 25 m to enable the final landforms to blend with scale of natural rocky ridges in the surrounding terrain.
Approximately 85% to 90% of the waste rock that will be stored in the waste rock landforms will consist of variably weathered arenites and arkoses (sedimentary rocks comprising mainly quartz,
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with some feldspar and mica). Other rock types including conglomerate, quartz- or hematite-brecchias, siltstone and schist will be present in lesser proportions. The minor lithologies typically contribute less than 5% (per lithological group) to the overall waste rock mass. Geochemical testing has been carried out on waste rock to assess its potential for generation of saline, acidic, metalliferous or other potentially polluting seepage or runoff (Appendix C). The testing included static acid-base accounting, trace elements concentration determinations (Table 2-3), radionuclide analysis, and mineralogical characterisation. A series of complementary tests (including water and mild acid extraction and rapid peroxide oxidation to determine ‘net acid generation’) was also carried out to evaluate the potential environmental mobility of waste rock constituents.
Potential for acid mine drainage
The geochemical characterisation of the Project waste rock has shown that the majority (>99%) of the waste rock contains negligible sulphur (<0.1 wt% S). The median sulphur contents in all deposits were less than the detection limit of 0.025 wt% S. Average sulphur contents were approximately 0.03 wt% S for most areas; the highest average was calculated for the Area 5 deposit (0.06 wt% S). Additional information on the assessment of acid-generating properties of waste rock is provided in Appendix C.
Trace elements in waste rock
In samples collected from outside the ore zone, two trace elements (selenium and boron) were identified as ‘enriched’ in the Project waste rock on the basis that the total element concentration corresponded to a Global Abundance Index equal to or greater than 3. The Global Abundance Index (GAI) is a tool which provides a measure of geochemical enrichment relative to average crustal abundance (Bowen, 1979). The GAI scale ranges from 0 to 6. A GAI of 0 indicates that the content of the element is less than, or similar to, the average crustal abundance. A GAI of 3 corresponds to a 12-fold enrichment above the average crustal abundance and is generally a level at which elements are considered to be ‘enriched’.
Rock samples collected from within the ore zone contained enriched levels of the following trace elements: Ag, As, B, Bi, Ce, Dy, Er, Gd, Ho, La, Lu, Nd, Pr, S, Se, Sm, Tb, Te, Tm, Y and Yb. This material would typically report to the processing plant and ultimately to the tailings storage facility. Ore zone samples were included in the waste rock testing programme, as it is possible that a minor proportion of mineralised material may be exposed in the wall rock at completion of mining.
Typically, the Project waste rock material yielded neutral/mildly alkaline leachate solutions when leached with deionised water. The leachable trace metal concentrations of the waste rock samples (including samples taken from the ore zone) were generally low and often below detection limits. The leachable rare earth element concentrations from waste rock were predominantly below detection limit (<0.001 mg/L). Although selenium was identified as one of the two most enriched elements on the basis of the GAI assessment of the solid samples, no leachable selenium concentrations above detection level were obtained. Boron, the most commonly ‘enriched’ element within the solid samples, was present in the leach extractions (Table 2-3). Additional information and laboratory reports for testing the Project waste rock are provided in Appendix C.
Overall, the geochemical testing has shown that only a small proportion of the trace elements present in Project waste rock occurs in forms that are readily leachable under the geochemical conditions expected in the proposed waste rock landform: less than 1% under neutral pH conditions and less than 6% under acidic conditions (Appendix C). Neither acidic nor saline seepage is expected to occur at the waste rock landforms, as the waste rock stored there would be non-saline and have low acid-generating capacity.
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Table 2-3: Typical trace elements concentrations in Browns Range waste rock
Element LOD1 (mg/kg)
Lithological grouping GAI=3
Transported material, including alluvial sand, colluvial sand and alluvial clay
Weathered in situ materials – including mottled saprolite
Moderately weathered siltstones, arenites, arkoses
Ore zone deposits (brecciation or alteration common)
Wallrock, comprising arkose or arenite – rarely brecciated
As 0.5 3.1 5.2 3.8 23.6 12.8 18
B 50 84 155 165 126 225 120
Ce 0.01 32.46 50.29 71.65 406.42 79.34 816
Cu 1 10 4 2 73 3 600
Dy 0.01 1.60 1.64 4.18 110.64 2.27 72
Er 0.01 0.92 1.01 2.68 72.11 1.53 45.6
Eu 0.01 0.41 0.38 0.53 7.56 0.50 25.2
Gd 0.01 1.85 1.78 3.27 70.02 2.00 92.4
Ho 0.01 0.33 0.34 0.87 24.00 0.47 16.8
La 0.01 17.24 28.41 37.56 167.38 52.47 384
Lu 0.005 0.14 0.17 0.37 8.85 0.24 6.12
Nd 0.01 12.57 18.09 28.01 246.20 27.89 456
Pr 0.005 3.59 5.40 8.16 57.06 8.67 114
Sb 0.05 0.39 0.38 0.33 0.66 0.63 2.4
Se 0.5 0.63 0.6 0.7 0.6 0.63 0.6
Sm 0.01 2.24 2.63 4.19 49.12 3.45 94.8
Tb 0.005 0.27 0.27 0.60 15.33 0.34 13.2
Th 0.01 10.7 20.2 31.0 18.4 30.2 144
Tm 0.01 0.14 0.16 0.40 10.60 0.23 5.76
U 0.01 1.11 1.26 2.01 7.95 1.72 28.8
Y 0.05 8.13 9.68 23.45 656.75 13.95 360
Yb 0.01 0.98 1.06 2.62 65.88 1.64 39.6
Notes: 1. LOD means the analytical limit of detection. All values are in mg/kg.
Notwithstanding the low reactivity of the Project waste rock, the following control measures will be incorporated in waste rock landform design to minimise the risk of water quality impacts from surface storage of waste rock:
waste rock landforms will be set back from drainage lines: no part of the waste rock landform will encroach on the estimated 1-in-100 year floodplain
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cut drains will be provided to direct clean surface water runoff around the toe of the waste rock landform
sediment detention basins will be provided at the downstream toe of each waste rock landform, to reduce the sediment movement away from the waste rock landform (note the detention basins and spillways are designed to safely pass 1 in 100 year 72 hour flow events; the basins are designed to reduce sediment content but they are not water storage structures)
the waste rock landform will be designed to resist erosion, by incorporating slopes that do not concentrate surface flows and using slope gradients that are sufficiently flat to minimise the risk of rill and gully formation
if required, rock armouring will be provided to increase the erosion resistance of the toe and lower slopes of the landform.
2.5 Ore processing
Ore processing occurs via a two stage process which includes a beneficiation process and a hydrometallurgical process (Figure 2-7). The process has been designed to accommodate an annual throughput of up to 750,000 t.
Figure 2-7: Simplified process flowsheet
2.5.1 Beneficiation
A series of conventional unit operations at the beneficiation plant would be used to upgrade the ore, removing the gangue materials (mainly silica) and increasing the rare earth oxide (REO) concentrations. These unit operations are proposed to be:
crushing circuit
grinding in semi-autogenous grinding (SAG) mill and/or a ball mill
two stage wet high gradient magnetic separation (WHGMS) process
flotation circuit to produce a mineral concentrate
tailings thickening of residues from the WHGMS and flotation circuits co-mingling with the hydrometallurgical tailings for disposal in the tailings storage facility.
The following chemicals will be used in the beneficiation plant:
fatty acid collector to concentrate the valuable mineral
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sodium silicate to depress quartz and mica gangue minerals
pH modifier in the form of caustic soda or sodium carbonate
flocculants for settling solids in flotation feed, concentrate and tailings thickeners
frother used in the flotation circuit to create a stable medium to transport the concentrate.
A processing flowsheet for the beneficiation circuit is shown schematically in Figure 2-8.
CRUSHING &
MINING
MAGNETIC
SEPARATION
CLEANER
FLOTATIONTHICKENER
PRESSURE
FILTER
20% TREO
MINERAL
CONCENTRATE
TAILINGS
THICKENER
TAILINGS
STORAGE
FACILITY
TailsTails
Con
Con
Mag
Con
Return Water
Return Water
HYDRO-
METALLURGICAL
PROCESSING
FACILITY
HYDROMET
TAILINGS
Tails
Figure 2-8: Beneficiation circuit flowsheet
2.5.2 Hydrometallurgy
A hydrometallurgical plant would further process the mineral concentrate to extract the rare earths and to remove radioactive elements and other contaminants such as iron, phosphate and aluminium. An estimated 3,300 tpa of mixed rare earth (RE) oxide product containing greater than 92% total rare earth oxide (TREO) would be produced. A processing flowsheet for the hydrometallurgical circuit is shown schematically in Figure 2-9.
The hydrometallurgical plant process comprises:
drying of the mineral concentrate followed by acidification and roasting to crack the mineral structure
water leaching to bring metals into solution
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purification and ion exchange to remove impurities
precipitation of RE using oxalic acid and calcination to convert RE oxalates to oxides
neutralisation and thickening of waste streams prior to co-mingling with the beneficiation tailings and subsequent delivery to the tailings storage facility.
MINERAL
CONCENTRATE
DRYING
ACID MIXER
ACID BAKE KILN
&
SCRUBBER
WATER LEACH
PURIFICATIONION EXCHANGEOXALATE
PRECIPITATION
PACKAGING
&
TRANSPORT
CALCINATION
TailsBARREN LIQUOR
NEUTRALISATION
COMBINE WITH
BENEFICIATION
TAILINGS
Return Water
Tails
Tails
>92%
MIXED
RE OXIDE
Figure 2-9: Hydrometallurgical plant flowsheet
The following chemicals will be used in the hydrometallurgical plant
sulphuric acid
oxalic acid
quick lime slaked to hydrated lime
limestone
ferric sulphate
magnesium oxide
caustic (sodium hydroxide).
To avoid reintroduction of solutes to the plant, some disposal of process water is required. An evaporation dam of approximately 20 ha is proposed (Figure 2-1). The evaporation dam will lined with a geomembrane to control seepage. During the detailed design phase, alternative water treatment options will be investigated, particularly those that do not require disposal of process water and therefore do not require an evaporation dam.
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2.6 Tailings disposal and storage
Tailings from the beneficiation plant and the hydrometallurgical plant will require disposal and storage. The characteristics of the various sources of tailings are summarised in Table 2-4. Over the life of project approximately 6.3 Mt of tailings will be produced.
Table 2-4: Sources of tailings for disposal and storage in the tailings storage facility
Source Rate (t/h) Characteristics
Beneficiation plant (90% of tailings mass)
WHGMS circuit
70
Crushed and milled ore, no chemical processes
Flotation circuit Crushed and milled ore, trace amounts of flotation reagents
Hydrometallurgical plant (10% of tailings mass)
Leach residue
8
Traces of sulphuric acid, some uranium and thorium and other elements
Purification residue Contains iron, aluminium, thorium hydroxides and some uranium
Ion exchange (IX) residue Contains low level uranium and thorium
Waste water treatment plant residue Gypsum and remaining metals as hydroxides
Total 78
The processing aims to produce a saleable final product that meets customer specifications by extracting the rare earth minerals and rejecting the waste material and impurities (such as uranium and thorium and their decay products) to the tailings. The waste and residue streams from the different processes are combined prior to reporting to the tailings storage facility. The combined stream is known as the process tailings.
The radionuclide rejection into the waste streams has been experimentally verified by Australian Nuclear Science and Technology Organisation (ANSTO) and shows that 90% to 95% of the radionuclides report to the solids in the tailings stream, with the majority of the remaining radionuclides reporting to the tailings stream liquid.
As part of the Northern Minerals design controls, the tailings storage facility will be designed as a permanent facility with a low permeability liner to minimise seepage. The design would ensure that tailings are effectively contained in the long term.
The hydrometallurgical plant will produce tailings with low level radiation values. Beneficiation tailings are not classified as radioactive. The activity concentration of the comingled tailings will not exceed an overall average radioactivity concentration of 1 Becquerel per gram (Bq/g), the level at which materials are considered to warrant some form of radiological assessment and control (ARPANSA, 2005). Additional discussion on radiation management is provided in Section 2.7.The tailings storage has been designed using the criteria and assumptions given in Table 2-5 (Appendix D).
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Table 2-5: Criteria and assumptions used for design of the tailings storage facility
Criteria/assumption Value
Solids content (%) 50%–55%
Stored final dry density (t/m3) 1.4
Rate of rise (m/year) 2 or less
Minimum storm water storage capacity during operations 1-in-100 year, 72 hour storm
Maximum tolerable seepage rate 1 kL/ha/day
Minimum static factor of safety (geotechnical stability) 1.5
Minimum factor of safety (seismic – operating basis earthquake) 1.1
Maximum tolerable damage/deformation from seismic event < freeboard allowance; no release of tailings or water
The facility will comprise two cells between which tailings deposition will be cycled. The tailings containment cells will be engineered to ensure that seepage will not exceed an average amount of 1 kL/ha/day, as recommended in Water Quality Protection Guideline No 3, Mining and Mineral Processing – Liners for waste containment (Water and Rivers Commission and Department of Minerals and Energy, 2000). In practice, this will entail a geosynthetic liner.
The tailings storage will be developed as an integrated waste landform, using non-reactive waste rock from the Gambit open pits to construct the main embankment. Embankment raises are proposed to be effected using a downstream construction or modified centre line method. A starter embankment will be constructed from locally-sourced materials. Details of the tailings containment system and integrated waste landform design and construction standards will be provided in the Mining Proposal prepared for the Department of Mines and Petroleum.
At closure, the tailings containment system and associated drainage structures will be capable of safely conveying the “Probable Maximum Precipitation” event, as required by DMP and ANCOLD. The “PMP” event corresponds to a return interval greater than 1 in 10,000 years.
2.7 Management of radioactivity
2.7.1 Introduction
The region surrounding the Project has been subject to exploration for uranium and other minerals for almost four decades. The naturally elevated concentrations of uranium (and thorium) in the region have resulted in elevated environmental radiation levels compared to regions elsewhere in Australia.
The Project ore deposits also contain elevated concentrations of uranium and thorium, although not at levels that are economically recoverable. Northern Minerals has commissioned a number of radiation-related studies, including a baseline environmental radiation study to characterise the naturally occurring radiation levels and an assessment of the potential radiological impacts of the Project on workers, members of the public and the environment. Additional work was conducted by ANSTO to identify situations where processing of the xenotime ore could result in elevated radionuclide concentrations. The work identified that some radionuclides concentrate in specific parts of the process, requiring operational radiological controls to maintain safe occupational exposures.
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From a radioactivity perspective, 80 ppm of uranium (U) is approximately equivalent to 1 Bq/g and 240 ppm of thorium (Th) is approximately equivalent to 1 Bq/g. A radionuclide concentration of level of 1 Bq/g (head of chain) is generally considered to be the level at which a material should be subject to some form of assessment and control. Appropriate controls may range from monitoring through to active radiological control measures (ARPANSA, 2005). Below a level of 1 Bq/g, special measures to limit exposure are not required and the material is not classified as radioactive.
2.7.2 Naturally occurring background radioactivity
The baseline radiation monitoring survey was conducted to characterise the radiological profile of the region. Monitoring included: radionuclide analysis of soils and rock, a gamma radiation survey, monitoring of radionuclides in dust, monitoring of dust deposition, and measuring average radon and thoron concentrations in air. A summary of results is provided below.
Radionuclide content of soils and rock
Uranium and thorium characterisation of soils and rock in the Project area has been conducted and average results are provided in Table 2-6. A comparison with the world crustal average levels and the threshold value for classification as a radioactive material has been provided for comparison.
None of the average concentrations of uranium or thorium in soil or rock, including mineralised rock that would report to the processing facility, exceed the threshold concentrations for classification as a radioactive material, despite being above the world crustal average.
Table 2-6: Average uranium and thorium content of Browns Range soils and rock
Material Uranium (mg/kg) Thorium (mg/kg)
Soils (regional) 1.4 10
Soils (above ore body) 1.2 11
Barren overburden 2 15
Ore bodies (average) 40 30
World Crustal Average 3 6
Radioactivity Classification Threshold Level 81 240
Gamma radiation
A comprehensive gamma survey was conducted in the region and average results are given in Table 2-7.
Table 2-7: Background gamma radiation results
Area Range (μGy/h)
Mining village location 0.08–0.13
On surface above Wolverine deposit 0.10–0.15
On surface above Area 5, Area 5 North deposits 0.08–0.18
Typical for Australia1 0.02–0.10
Note: 1. Mudd (2002)
The natural background level is slightly elevated when compared to typical Australian levels. Higher levels are measured in the vicinity of the ore deposits.
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Radon and thoron in air
Radon (Rn222 from the uranium decay chain) and thoron (Rn220 from the thorium decay chain) concentrations in air have been monitored at the Project area using passive sampling devices placed into the field for periods of three months. Average concentrations for each monitoring period are presented in Table 2-8.
Table 2-8: Seasonal average radon and thoron concentration in air
Radon (Bq/m3) Thoron (Bq/m3)
Summer (Dec 2012 – Mar 2013) 23 13
Autumn (Apr 2013 – June 2013) 21 13
For comparison purposes, UNSCEAR (2000) reports worldwide average outdoor radon and thoron concentrations of 10 Bq/m3.
Radionuclides in water
The Australian Drinking Water Guidelines 6 (Australian Government, 2011) provides a guideline for uranium in water of 0.017 mg/L. No guideline value is provided for thorium. A summary of the baseline groundwater monitoring results is provided in Table 2-9 together with the Australian Government guidelines for drinking water quality (where available). The results indicate that there is a large natural variability in radionuclide levels in groundwater.
Table 2-9: Summary of Browns Range groundwater baseline radionuclide analysis
Water bore BRWW B001 B0030 Other bores Drinking Water Guideline1
U (μg/L) 5.5 0.7 1.3 17
U238 (Bq/L) 0.068 0.009 0.016
Th230 (Bq/L) 0.002 0.004 0.011 2
Ra226 (Bq/L) 0.044 0.155 0.256 0.037 2
Pb210 (Bq/L) 0.150 0.190 0.320 0.160
Po210 (Bq/L) 0.008 0.005 0.031 2
Th (μg/L) 0.04 0.29
Th232 (Bq/L) <0.001 0.001
Ra228 (Bq/L) 0.130 0.179 1.478 0.133 2
Th228 (Bq/L) 0.004 0.004 0.030 0.051
Notes: 1. Source: Australian Government (2011). 2. >0.5 Bq/L gross α/β triggers further investigation.
Radionuclides in deposited dust
Background dust monitoring in the Project area has been conducted using dust deposition gauges. A network of six stations were established in December 2012 and samples have been collected on a monthly basis during the 2013 calendar year. Samples were analysed for mass and total alpha counts and are summarised in Table 2-10.
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Table 2-10: Summary of dust deposition results
Sampling period Total dust deposition (g/m2/month)
Total alpha in collected particulates
(αdps)
14/12/2012–10/01/2013 4.0 0.015
10/01/2013–11/02/2013 8.1 0.024
11/02/2013–10/03/2013 7.0 0.039
10/03/2013–10/04/2013 6.2 <0.009
13/03/2014–10/05/2013 7.1 n/a1
13/05/2013–10/06/2013 5.5 <0.009
18/06/2013–18/07/2013 2.6 <0.009
18/07/2013–18/09/2013 2.6 0.012
18/09/2013–18/10/2013 3.5 0.025
Note: 1. n/a refers to no results for the sampling period.
Radiological characterisation of mined materials
The overall Project consists of a number of rare earth ore deposits which would be mined initially via open pit mining methods and subsequently using underground mining techniques. The ore would be treated in an on-site processing facility. Tailings from the process would be directed to a dedicated tailing storage facility. The main materials associated with the project are:
barren overburden (soils and waste rock)
ore containing the rare earth mineralisation and elevated uranium and thorium oxides
process materials:
- tailings - intermediate process streams - final product.
The radiological characteristics of each of these materials are described below.
Barren overburden
Barren overburden will be excavated to expose the ore bodies and will be placed in waste rock landforms. The overburden is not classified as radioactive material, with average U and Th levels of up to 15 ppm and 2 ppm, respectively. No special controls are required for the management of radioactivity in waste rock.
Ore
The mined ore is mineralised material that contains the rare earth minerals and oxides of uranium and thorium at average concentrations of approximately 40 ppm and 30 ppm, respectively. The mineralised material will also contain the decay products of uranium and thorium (from the U238, U235 and Th232 decay chains). Analysis by ANSTO has shown that the radionuclides in the respective decay chains are in secular equilibrium. (Note that secular equilibrium is when the activity concentration of each of the decay products is the same as the activity concentration of the head of chain radionuclide).
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At the expected concentrations, the activities of the decay chains are as listed in Table 2-11. The individual and combined concentrations of uranium and thorium in the mined ore do not require special management actions arising from radiological considerations.
Table 2-11: Activity concentrations in Browns Range ore
Decay chain Activity concentration (Bq/g)
U238 radionuclides 0.5
U235 radionuclides 0.02
Th232 radionuclides 0.13
Process materials
The metallurgical testwork has shown that some radionuclides concentrate through the processing plant as the ore undergoes a range of chemical and metallurgical processes. ANSTO conducted a radionuclide deportment study and additional testwork has been undertaken to determine radionuclide distribution through the processing facility (see Appendix ).
About 96% of the material entering the beneficiation plant is rejected as tailings. The remaining material forms a mineral concentrate that is processed further through the hydrometallurgical plant. The mineral concentrate stream produced at the beneficiation process is a slurry that contains concentrated rare earth minerals and accounts for approximately 4% of the mass flow. The beneficiation process also partially concentrates other heavy metals, including uranium and thorium. The concentrations of uranium and thorium in the mineral concentrate are expected to reach approximately 740 ppm and 220 ppm, respectively. At these levels, the mineral concentrate exceeds the threshold for classification as a radioactive material and therefore requires appropriate controls.
The mineral concentrate undergoes further processing in the hydrometallurgical plant, generating a a final product and a second tailings stream. The tailings from the hydrometallurgical process contains impurities including heavy metals and radionuclides. The concentrations of radionuclides in this tailings stream are elevated and for some radionuclides, exceed the threshold values for classification as a radioactive material. However, it is intended that the beneficiation tailings and the hydrometallurgical tailings are recombined for final disposal in a purpose-built, engineered tailings management facility. The concentration of radionuclides in the final combined tailings is practically identical to that of the ore which is not a radioactive material.
The final product would have the impurities removed and contains radionuclides below the classification threshold for a radioactive material. The product that will be shipped from the Project is not a radioactive material.
Table 2-12 provides a conservative estimate of the radionuclide content of the main process streams. (Note that radionuclides from the U235 decay have not been included due to their low concentration).
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Table 2-12: Predicted radionuclide concentrations in processing plant streams
Beneficiation plant Hydrometallurgical plant Combined tailings
Feed (Bq/g)
Concentrate (Bq/g)
Tailings (Bq/g)
Solids (Bq/g)
Liquids (Bq/L)
Solids (Bq/g)
Liquids (Bq/L)
U238 0.6 7.9 0.3 0.6 410 0.3 41
Th230 0.5 7.9 0.3 1.9 5 0.4 0.5
Ra226 0.6 7.9 0.3 3.1 2 0.6 0.2
Pb210 0.6 7.9 0.3 3.1 5 0.6 0.5
Th232 0.1 1.4 0.1 0.3 1 0.1 0.1
Ra228 0.1 1.4 0.1 0.6 1 0.1 0.1
Th228 0.1 1.4 0.1 0.3 1 0.1 0.1
U235 0.03 0.4 0.02 0.02 20.0 0.02 2.0
Note: the difference between radionuclide concentrations in ore and tailings is due to mass gain from reagents addition in the neutralisation of the waste liquid streams.
2.7.3 Key actions for radiation management
The mined overburden and ore are below the threshold value for classification as radioactive materials. However, the metallurgical processing indirectly concentrates radionuclides in specific areas of the processing plant. Therefore, Northern Minerals has committed to ensuring that radiation is appropriately managed and that potential impacts arising from occupational exposures are minimised.
Northern Minerals intends to manage radiation as one of the workplace and environmental hazards that exist as part of any mining and processing project. Information on the deportment of radionuclides through the processing plant will be used to ensure that designs are appropriate and for the estimation of potential doses to workers.
Detailed design is yet to occur; however, Northern Minerals has a commitment to best practice radiation controls at this stage of the Project through:
establishing radiation design criteria for the mine and processing facilities
designing, constructing and operating the tailings storage facility consistent with Australian National Committee on Large Dams (ANCOLD) guidelines and other relevant requirements
establishing and implementing specific radiation related management systems and control measures.
The primary management measures for control of radiation are as follows:
defining the whole of the mine site as a ‘supervised area’
defining the following areas as ‘controlled areas’:
- mineral concentrate handling area - hydrometallugical plant
restricting access to the main mining areas to appropriately trained and qualified personnel
ensuring that all heavy mining equipment is air conditioned
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installing a specially designed storage area for mineral concentrate to prevent loss of material
use of standard dust suppression techniques (wetting of materials before handling, wetting of roadways, provision of dust collection systems on drills, use of respiratory protection when dusty)
providing a wash-down pad within the site area for vehicles that have come from the mine and controlled areas
use of dedicated extraction systems for the dryers and the acid bake kiln
installation of scrubbers or bag houses where fumes or off gases are generated
provision of bunding to collect and contain spillages in areas where tanks are used to contain radioactive process slurries
bunding of tailings pipeline corridors to control spillage in the event of a pipeline failure
maintain sufficient access and egress for mobile equipment to allow clean-up where there is the possibility for large spillages
providing wash-down water points and hoses for spillage clean-up
establishment of an occupational and environmental monitoring programme.
The controls and programmes would be detailed in the Project Radiation Management Plan (RMP) which would be finalised for regulatory approval prior to construction and operation.
2.8 Support infrastructure
2.8.1 Power supply
To service the mine, processing facility and associated infrastructure, an estimated 11 MW generating capacity will be required. This will be supplied via a purpose-built power generation facility. During the next phase of Project design, the relative benefits of liquefied natural gas (LNG) and diesel powered generation will be assessed. Air quality impacts assessments and greenhouse gas emissions estimates prepared for the Browns Range Project have assumed that all power will be generated using diesel-fired equipment.
2.8.2 Water supply
The estimated average water demand for the Browns Range Project is 1.3 GL/year; most of which is required for ore processing. Lesser amounts are needed for dust suppression, fire protection and equipment washdown. A relatively small amount of water is required for drinking water, ablutions and other domestic purposes. Because the water demand is dominated by ore processing, the requirement for water is relatively constant throughout the year, although some water uses, such as dust suppression will be reduced during the wet season.
The processes for recovery of rare earths are very sensitive to water quality and are particularly influenced by the concentrations of magnesium, carbonate, sodium and suspended matter in the process water supply.
Preliminary investigations into water resources in the local area (Appendix H) have identified the Gardiner Sandstone aquifer, which lies near the western edge of the Project area, as a suitable water supply source. It is proposed to abstract water from an array of relatively shallow production wells, distributed along a north-south axis. Indicative production bore locations are shown in Figure 2-1.
Final production bore locations (all within the defined development envelope) will be confirmed during the detailed design phase.
Groundwater modelling has shown that abstraction of 1.3 GL/year of water from a distributed borefield constructed into the Gardiner Sandstone aquifer will not threaten the culturally significant Banana Springs and is unlikely to significantly impact on subterranean fauna habitats. Accordingly, the preferred option for satisfying project water requirements includes the following components:
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recycling of water from the tailings storage facility
harvesting of water from runoff in the processing plant
re-use of water from mine dewatering
abstraction of water from a production borefield accessing the Gardiner Sandstone aquifer.
The Project water supply strategy will adopt waste minimisation principles (reduce, reuse, recycle), while seeking to minimise biodiversity impacts associated with direct clearing for water storage and conveying, and for evaporation basins.
2.8.3 Roads and transport
Current access to the Browns Range Project site is from Halls Creek via Duncan Road (112 km), Gordon Downs Road to Ringer Soak (44 km) and then via an unformed road (58 km) to the Project area. Upgrade works are required on sections of the access route in order to provide safe and reliable transport of reagents and consumables to the Project site and product out of the site. The works will improve traffic safety and pavement strength (through formation and alignment changes, and gravel sheeting). These works, together with drainage works (floodway and culvert construction), will allow significantly greater wet season serviceability.
The existing unformed road between the Gordon Downs Road and the Project area passes through the eastern part of the Ringer Soak community. Northern Minerals recognises that it is undesirable for mine traffic to travel on roads in close proximity to a residential community. Accordingly, the activities included in this API include the construction of a new by-pass road so that project-related traffic will pass to the north of Ringer Soak, minimising the potential for adverse impacts on public safety and amenity.
Road improvements north and west of the intersection of the by-pass road and the Gordon Downs Road (an existing road maintained by the Shire of Halls Creek) are not part of this proposal. If road upgrade or maintenance works are required to existing Shire roads, these will be implemented by the Shire, with appropriate assistance from Northern Minerals.
2.8.4 Accommodation
A dedicated accommodation village will be required to house an estimated peak workforce of 265 people during operation and about 350 people during construction. Single storey accommodation units are proposed, as well as other remote mine site amenities including messing, laundry and leisure facilities.
Water for the village would be sourced from the borefield, but would have its own water storage, reverse osmosis (RO) plant and waste water treatment system. It is also proposed to generate power independently from the main power supply. Power demand is anticipated to be about 500 kW.
Sewerage and landfill facilities for putrescible waste are also proposed to service the accommodation village.
2.8.5 Airstrip
An airstrip located approximately 2 km south-east of the preferred plant site is proposed.
2.8.6 Borrow pits
A potential source of clay construction material has been identified south of the proposed operations. The material is primarily required for construction of the tailings storage facility starter embankments.
A gravel borrow pit has been identified to the north of the proposed airstrip. The gravel will be used for construction of roads, hardstands and the airstrip.
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2.9 Mine rehabilitation and closure
Northern Minerals has developed a conceptual rehabilitation and closure plan (Appendix P1). The rehabilitation and closure strategy for Browns Range is structured around six closure domains:
mine pits and underground workings
stockpiles and built landforms
water storages and drainage infrastructure
industrial plant, including fuel and reagent storage
roads and other linear infrastructure
support infrastructure (accommodation village, borrow pits, landfill, water supply pipelines and borefield, airstrip, etc)
.
Rehabilitation of exploration disturbance is administered under authorisations issued by the Department of Mines and Petroleum and does not form part of the activities described under this API.
The project elements that form part of this API will result in a combined disturbance footprint of approximately 711 ha (Table 2-13). The main contributors to disturbance are stockpiles and built landforms (including waste rock landforms and tailings storage facilities) and roads. Support infrastructure (accommodation village, borrow pits, airstrip, etc.) accounts for approximately 13% of the development footprint (Figure 2-10).
At closure, most disturbed areas will be recontoured, topsoiled and revegetated using local provenance vegetation. Northern Minerals does not propose to backfill mine pits at the completion of the 10-year programme described in this API. This is because the mineralisation on all deposits is open at depth and there is the possibility that future extraction of this mineralised material will be viable.
The following project elements will not be rehabilitated to a condition similar to the pre-mining condition:
mine pits
infrastructure (possibly including production bores, improved roads or the proposed airstrip) retained at the request of stakeholders and the relevant land manager.
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Table 2-13: Estimated disturbance by project element
Project element (does not include exploration disturbance) Estimated disturbance area (ha)
Mining
Area 5 open pit 13.89
Area 5 waste rock landform 12.86
Gambit Central open pit 9.23
Gambit West open pit 18.02
Gambit East open pit 11.88
Gambit waste rock landform 63.87
Wolverine open pit 31.18
Wolverine waste rock landform 56.64
Infrastructure
Process plant and ROM 43.26
Evaporation pond 20.25
Tailings storage facility 39.29
Access roads (inc. borrow pits) 251.82
Haul roads (inc. borrow pits) 36.26
Gravel pit 32.66
Airstrip 39.39
Accommodation village (inc. support services) 18.39
Administration offices 8.00
Magazine 4.00
Borefield 0.06
710.94
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Figure 2-10: Estimated disturbance by closure domain
2.10 Alternatives considered
During the scoping and design of the Project, the following alternatives were considered.
2.10.1 Processing options
At an early stage of project development, Northern Minerals considered a range of processing options. The main options were:
Option 1: Treat xenotime ore via a beneficiation process (with or without magnetic separation) to produce a mineral concentrate containing in the order of 30% TREO for export.
Option 2: Treat xenotime ore via a two stage process (beneficiation followed by hydrometallurgical extraction) to produce a mixed rare earth oxide, containing approximately 92% TREO for export.
Option 3: Treat xenotime ore via a three stage process (beneficiation followed by hydrometallurgical extraction, followed by solvent extraction) to produce high purity individual rare earth oxides for export.
The processing option selected for the Project is Option 2. This option was considered to offer the best balance of technical and environmental risk, commodity value adding, and capital and operating cost considerations.
2.10.2 Location of hydrometallurgical processing facility
While the location of the mineral deposits determines the location of the proposed mine and the beneficiation processing facility, Northern Minerals considered that a range of options should be examined in relation to the location of the hydrometallurgical processing facility. An options study was conducted to assess the benefits and disadvantages of siting the processing facilities at the mine
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site or at various locations remote from the mine site. Figure 2-11 shows the nine locations considered in the siting options study. A multi-criteria assessment was used to evaluate the potential processing facility locations. The options assessment included a number of base requirements, including a requirement that any wastes should be returned to the mine site tailings storage facility.
Figure 2-11: Locations assessed during options study for ore processing facility
The assessment ranking of the best and worst sites is shown in Table 2-14.
Table 2-14: Assessed locations and preference ranking
Preference Location Score
1 Mine site 86%
2 Darwin Port 70%
3 Kununurra & Geraldton 66–77%
8 Pinjarra 62%
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9 Muchea 58%
The siting of the hydrometallurgical processing facility at the mine site is the preferred option as it scored best—or equal best—for each assessment criterion considered in the following categories: environmental, social, capital and operating cost, and operational and project development risk.
2.10.3 Location of tailings storage facility
A total of four potentially suitable sites for the location of the tailings storage facility were considered (Figure 2-12). Site 4 was selected as the preferred site based on the following considerations:
proximity to sources of waste rock and clay for construction
located away from the proposed village site and Northern Territory border
topography suitable for blending in with surrounding terrain
avoidance of drainage lines and 1-in-100 year flood zones
avoidance of areas with strong potential to support short range endemic fauna and/or priority flora
some potential for future expansion.
While preliminary sterilisation drilling has been completed on the preferred site, further drilling and assessment is required to finalise the site.
2.10.4 Tailings disposal options
A number of alternatives were considered in relation to the management of tailings from the ore processing facilities. The alternatives included consideration of the relative merits of:
separate or combined disposal of beneficiation and hydrometallurgical tailings
disposal of tailings as a slurry, a thickened slurry or a paste
disposal of tailings in lined or unlined storages
storage of slurry tailings in conventional ‘paddock’ style cells
valley side disposal in topographically appropriate valleys and ridgelines
central thickened discharge on relatively flat areas.
Dry stacking of tailings was not considered as a viable option. In-pit storage of tailings was also not considered viable at this stage, as the mineralisation at all the deposits is open at depth and extraction may be viable in future.
The factors that influenced the short-listing of potential tailings disposal options included:
size of disturbance footprint and potential biodiversity impacts
pollution risk; implications of potential failure or loss of containment events
closure requirements
likely stakeholder acceptance
water efficiency
compliance with relevant industry standards and government guidelines
operational complexity and reliability
capital and operating costs.
On balance, Northern Minerals concluded that an option involving co-mingling of beneficiation and hydrometallurgical tailings as thickened slurry, offered the best outcomes. Development of a two-cell paddock-style tailings storage facility with downstream or modified centreline raises, and using non-reactive waste rock to form an integrated waste landform, was identified as an option offering a
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reduced disturbance footprint, efficient materials placement and low geotechnical risk. This is the option proposed under this API.
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Figure 2-12: Location options for the tailings storage facility
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A preliminary tailings storage design has been developed (Appendix D). Additional detail on the design, construction and monitoring of the proposed tailings storage facility will be provided in documentation submitted to the Department of Environmental Regulation (Part V works approval) and to the Department of Mines and Petroleum (mining proposal, tailings operating strategy, project management plan, mine rehabilitation and closure plan).
2.10.5 Water supply and management options
Northern Minerals’ water supply strategy has been shaped by considerations relating to water quantity, water quality and the rate at which water is required. Potential impacts on culturally significant sites, biodiversity impacts from direct clearing, and indirect effects on surface and groundwater hydrology have also been taken into account.
Northern Minerals considered a range of possible water sources to satisfy the Project water demand, including:
water sourced from dewatering of mine pits and underground workings
surface water runoff during the wet season
underground water from production bores accessing the Browns Range Metamorphic aquifer
underground water from productions bores drilled into the Gardiner Sandstone formation
underground water from shallow , unconfined alluvial aquifers in proximity to drainage lines
recycling of water from the processing plant and/or from the tailings storage facility.
Hydrogeological testing and modelling conducted as part of baseline investigations found that the likely supply from mine dewatering would not be sufficient to meet overall Project requirements. It would, however, be likely to be suitable for use as dust suppression. Water from shallow alluvial aquifers would not provide an adequate reliable, continuous source of water, and abstraction of water from shallow alluvial systems has the potential to affect water-reliant riparian vegetation. Harvesting of surface water runoff would generally only be possible during the December to March wet season, and the high evaporative demand in the Project area would necessitate the construction of substantial water storage dams if this option were selected. While runoff from the processing facility would be captured and re-used, the strategy of using surface water flows to meet all Project water demands is not considered viable.
Field pumping tests were conducted to assess sustainable groundwater yield in the Browns Range Metamorphics and in the Gardiner Sandstone aquifer (Appendix H). Based upon the field test results and associated hydrogeological modelling, Northern Minerals concluded that abstraction of groundwater from the Gardiner Sandstone aquifer provides the best source for reliable, good quality water.
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3 STAKEHOLDER ENGAGEMENT
Northern Minerals has been actively consulting with stakeholders since April 2012 and implemented a formal community engagement plan in April 2013. Table 3-1 outlines the stakeholder consultation efforts undertaken by Northern Minerals since 2012. While consultation in relation to environmental issues is relevant to this document, broader consultation often included environmental considerations as a component.
Community meetings in relation to the Project have been held in Halls Creek, Ringer Soak and Wyndham.
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Table 3-1: Summary of consultation to end May 2014
Stakeholder Date/s Stakeholder representative Key issues discussed/raised
State Government
Office of the Minister for Regional Development WA
24/4/2012 Principal Policy Advisers Project overview, discussion on community investment in East Kimberley
WA Department of Mines and Petroleum (DMP)
14/05/2012
02/10/2012
23/10/2012
08/04/2013
Director General
Deputy Director General - Strategic Policy
General Manager – Tenure and Native Title
Deputy Director General Approvals
Senior Environmental Inspector, Minerals Branch; A/Principal Policy Officer Approvals
Assistant Director, Geological Survey
Liaison Officer, Kimberley Region
Project briefing and exploration update
Discussed environmental assessment and mining approvals process and time line
DMP to decide if lead agency to be implemented
Support for decision to co-locate hydrometallurgy plant at project site
Discussion on tenure requirements and timing
Coordination meeting involving: DMP, WA Department of Environment and Conservation (DEC), WA Radiological Council and Department of Health (DoH)
03/04/2013 DMP: Senior Advisor
Senior Environmental Officer
Team Leader Environment; Minerals Manager - North Division
Mineral Titles Executive Director
DEC: Environmental Officer
Radiological Council: Council Secretary
DoH: Health Physicist
Briefing on proposed project development, operations including matters such as mine closure planning, environmental impact assessment and tenure
Mine closure plan will be assessed under Mining Act 1978 by DMP during Mining Proposal stage
Suitability of physical properties of mine waste for closure to be assessed
Discussed Native Title and cultural heritage
Ore, tailings and final product expected to be below state and national definitions of radioactive material
Assessment required on the fate of the uranium and thorium daughters in the hydrometallurgical plant
Office of the Minister for Mines and Petroleum WA
07/05/2012 Principal Policy Adviser High level briefing and overview of the Project and discussion around mining titles and Native Title
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Stakeholder Date/s Stakeholder representative Key issues discussed/raised
WA Environmental Protection Authority (EPA)
03/10/2012
12/03/2013
Director - Assessment and Compliance
Manager - Mining and Industrial Assessments
Chairman
Consultation on scope of the Proposal and de-coupling of the hydrometallurgical and beneficiation processes
Pre-referral briefing and project overview
Discussed status of existing studies and proposed studies
Discussion on approvals process and timelines for construction and production
Ore, tailings and final product expected to be below state and national definitions of radioactive material
Discussed stakeholder consultation completed and planned
WA Department of Water
27/03/2013
08/04/2013
Executive Director Regional Delivery and Regulation
Director Regions
Senior Hydrologist – North West
Regional Manager Kimberley Region
Team Leader Planning Kimberley Region
Project overview
Discussion on ground and surface water studies and anticipated management measures; groundwater potentially sourced from dewatering or water supply bores, quality needs assessment
Potential impact on other groundwater users not considered a factor
Proposal to determine risk of impacting on cultural and environmental receptors and provide management/mitigation if required
3D Modflow modelling not required, analytical model with sensitivities sufficient
Conduct assessment of the pit void water balance and the incorporation of the geochemical testing results
Assess impacts on groundwater dependent ecosystems (GDEs) if present
Surface water management, no significant concerns raised
Regional office will undertake the assessment
WA Department of Transport
26/03/2013 Harbour Master (Wyndam)
Deputy Harbour Master Operational Standard
Project overview and possible supply import and product export
Capacity or port sufficient to handle the small quantities
Contamination could possibly be a concern if product was not in containers
Mains Roads WA 08/04/2013 Regional Manager Kimberley Region Project overview, focus on road transport, provided trucking estimates for transport of product and supplies
Condition and category of Gordon Downs and Duncan Roads to accommodate increased truck movement needs to be assessed
No issues raised associated with increased vehicle movement on Great Northern Hwy
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Stakeholder Date/s Stakeholder representative Key issues discussed/raised
WA Department of Environment and Conservation (DEC)
05/07/2012
03/04/2013
Principal Environmental Officer/Area Manager North, Conservation and Developments Section, Environmental Management Branch
Regional Leader Industry Regulations – Kimberley Region
Environmental Officer; Environmental Regulation Division
Acting Section Coordinator, EIA and Industry North, Environment Management Branch
Project overview
Discussed the EPA assessment and approvals process and also subsequent DEC approvals
Discussed status of existing studies and proposed studies
Discussed methodology of invertebrate fauna study
Support for flora and vegetation survey methods and timing
Stakeholder communication important, road impact could be seen as significant
Proposal will be assessed by regional office
Kimberley Development Commission (WA)
29/06/2012
09/10/2012
16/11/2012
08/02/2013
06/02/2014
Chairman and CEO Project overview and site tour
Discussion local training and shipping opportunities
Support infrastructure requirements
WA Department of Indigenous Affairs
25/07/2012 Director General
Senior Project Officer
Project overview and discussion on challenges and opportunities for local community at Ringer Soak
Local employment and Kundat Djaru Corporation
Yaruman Arts Centre
Department of Training and Workforce Development
15/11/2013 Senior representatives Project overview
Local employment strategy
Shadow Minister for Mines and Petroleum
25/11/2013 Bill Johnston MLA Project overview
Department of Regional Development
06/02/2014; 23/05/2014
A/Executive Director, Economic Development and Diversification
Director General
Project update
Department of State Development; International Trade and Investment
20/05/14 General Manager, International Markets; Acting Country Manager
Project overview
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Stakeholder Date/s Stakeholder representative Key issues discussed/raised
Minister for Regional Development
22/05/14 Hon Terry Redman MLA; Principal Policy Advisor Project overview
Office of the Minister for Environment
05/02/2014 Chief of Staff; Principal Policy Officer Project overview
Environmental approval process
Various (OEPA, DER, DMP and DoW)
11/02/2014 Various representatives Modelling and assessment of water quality in pit lake voids
Various (OEPA, DER and DMP)
14/02/2014 Various representatives Tailings storage facility studies and options
Federal Government
Federal government 10/08/2012 Federal Minister for Resources and Energy
Minister for Tourism and Policy Adviser
Project overview and discussion on export options and Native Title
Supportive of minerals processing in Australia
Department of Sustainability, Environment, Water, Population and Communities (SEWPaC)
05/04/2013 Director and Senior Assessment Officer, North West Section, Environment Assessment and Compliance Division
Project overview
Discussed status of existing studies and proposed studies
Discussed the requirements and triggers for the Proposal to be assessed under the Environment Protection and Biodiversity Conservation Act 1999
Department of Resources, Energy and Tourism
05/04/2013 General Manager – Minerals Branch, Resources Division
Manager – Mineral Commodities Section, Resources Division
Project overview and discussion on funding, water, Indigenous community engagement, transport and export of product
Member for Durack 21/02/2014 Melissa Price MP Project overview
Member for Brand, Shadow Minister for Resources
25/01/2014 Gary Gray MP Project update
Northern Territory
NT Department of Mines and Energy
10/04/2013 Assistant Director/Chief Mining Engineer
Environmental Officer and Senior Environmental Officer, Mining Environmental Compliance Division
Project overview and rare earths, discussion regarding NT tenements
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Stakeholder Date/s Stakeholder representative Key issues discussed/raised
Darwin Port Authority
10/04/2013 General Manager Port Development Project overview and discussion on existing facilities and timelines, possible supply import and product export
Available capacity at port
Department of Transport
07/06/2013 Director General Project overview
Transportation routes
East Kimberley region
Traditional Owners, Jaru People
Numerous Representatives Overview and consultation on project
Heritage surveys undertaken
Co-existence agreement negotiations commenced; agreement reached for negotiation protocol
Shire of Halls Creek 21/06/2012; 04/12/2012; 07/02/2013; 22/11/2013; 19/03/2014; 16/04/2014
Chief Executive Officer; President
Manager Environmental Health and Regulatory Services;
Economic Development Officer;
Community Engagement Officer
Infrastructure and Assets Manager
Project overview and discussion on requirements for planning approval and building permits.
Discussion on Duncan Road, Gordon Downs Road, Sturt Creek crossing - use, classification, upgrades, maintenance and funding.
Supply regular progress reports and future work plans.
Development of MOU.
Shire of Wyndham - East Kimberley
09/04/2013; 15/05/2013; 15/11/2013
Chief Executive Officer;
Director of Community Development
Project overview with a focus on increased traffic and import and export out of Wyndham port
Cambridge Gulf (operators Wyndham Port)
22/08/2012 CEO and Port Manager Project overview and discussion on existing facilities and timelines, possible supply import and product export
Available capacity at port
Other business options such as fuel supply
Ord-East Kimberley Expansion Project
23/08/2013 Director Project overview
Discussed Indigenous employment strategy and local contracting opportunities
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Stakeholder Date/s Stakeholder representative Key issues discussed/raised
KRED 08/02/2013
21/02/2013
21/03/2013
08/05/2013
31/01/2014
Chief Executive Officer
General Legal Council
Environmental Consultant
Project overview and discussion of process to reach a co-existence agreement with Jaru People
KRED arranges heritage surveys
Heritage impact assessments
Heritage survey work
Environmental consultant to review API and technical documents and advise Jaru People
Kimberley Land Council
14/08/2012
20/12/2012
Principal Legal Officer; Chief Executive Officer Project overview
Engage with relevant anthropologists
Local employment and business opportunities
Heytesbury Cattle Company
10/04/2013 General Manger Project overview
As pastoralist, discussed road use, transport and sharing of resources
Kimberley Language Resource Centre
27/07/2013; ongoing
Research, Training and Development Manager Project overview
Contracted to deliver local cultural awareness training – capacity building in Jaru community
Local businesses operating around Halls Creek
Various Various Project overview
Local employment and contracting opportunities
Local service providers in Ringer Soak community
Various Various Ongoing support and updates on project status
Assistance provided through sponsorship and sharing of resources
Flora Valley Station May 2013 Managers Project overview
Traditional Owners – Tjurabalan
April 2014 Traditional Owners; KRED; KLC Project overview
Information of miscellaneous licence application
Community Information Forums
Halls Creek May 2013 60 community members Issues discussed include tailings, transport movements, radiation and water supply
Ringer Soak May 2013 28 community members
Wyndham May 2013 18 community members
Halls Creek May 2014 Eleven community members Project update and more information provided on outstanding issues raised in the previous forums. Ringer Soak May 2014 Twenty five community members
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Stakeholder Date/s Stakeholder representative Key issues discussed/raised
Wyndham May 2014 Six community members Additional questions and comments raised related to transport, mining, employment and training, radiation, local content and contracting.
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4 ENVIRONMENTAL IMPACTS AND MANAGEMENT
4.1 General approach
The Project was originally referred to the Environmental Protection Authority in May 2013. The EPA invited public comment on the proposal for a seven day period, but no comments were received.
The EPA decided that the Project required assessment under the Environmental Protection Act 1986 (WA) (Part IV) at the Assessment on Proponent Information (API) – category A level. This level of assessment is used where:
a) the proposal raises a limited number of key environmental factors that can be readily managed
and for which there is an established condition-setting framework
b) the proposal is consistent with established environmental policies, guidelines and standards
c) the proponent can demonstrate that it has conducted appropriate and effective stakeholder
consultation, in particular with decision-making authorities
d) there is limited or local concern only about the likely effect of the proposal, if implemented, on the environment.
In July 2013, the EPA released a scoping guideline (Appendix A) which:
a) directed Northern Minerals on the preliminary key environmental factors or issues that should
be addressed during the environmental review and preparation of the API document
b) identified the studies and investigations to be carried out and associated timelines for
completion
c) confirmed the stakeholders to be consulted during the environmental review and preparation of the API document.
This API document has been prepared in accordance with the EPA’s scoping guideline.
4.2 Preliminary key factors
The EPA’s scoping guideline listed the following preliminary key environmental factors:
inland waters: environmental quality
flora and vegetation
terrestrial fauna
subterranean fauna
rehabilitation and closure.
In order to assess these preliminary key factors, a series of investigations was undertaken. These investigations are listed in Table 4-1 with a timeline showing the field and desktop components in Table 4-2.
Table 4-3 outlines how EPA guidelines were referenced in undertaking these investigations.
An assessment of each preliminary key environmental factor is presented in tabular form in Sections 5 through 11. Note that the tables outline the EPA objective for the environmental factor, the existing environment, potential impacts (unmitigated) associated with the Project, the management proposed by Northern Minerals, and the predicted outcome. A summary of the findings for each preliminary key environmental factor is provided in Table 4-4.
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4.3 Other potential impacts and activities
While the preliminary environmental factors have been individually addressed, there are a number of other environmental factors relevant to the Project. These other issues can be readily managed by processes outside the Environmental Protection Act 1986 (WA) (Part IV). These issues are summarised in tabular form in Section 12, together with the applicable agency and legislation.
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Table 4-1: Planned and completed studies for the Browns Range Rare Earths Project
Factor Study Report
Inland Waters (surface water)
Surface water management and flood study Browns Range Project - Surface Water Management and Flood Study – June 2014 (Golder Associates, 2014a)
Inland Waters (groundwater)
Browns Range hydrogeology Browns Range HREE Project, Stage 2 - Hydrogeological Test Drilling, Aquifer Testing and Assessment (Klohn Crippen Berger, 2014b)
Water supply modelling Browns Range Project - Water Supply Modelling – January 2014 (Klohn Crippen Berger, 2014a)
Terrestrial vegetation and flora
Level 1 and 2 survey of flora and vegetation and impact assessment
Level 2 Vegetation and Flora Survey and Impact Assessment (Outback Ecology, 2014g)
Terrestrial vertebrate fauna
Baseline surveys Terrestrial Vertebrate Fauna Baseline Survey – October 2012 (Outback Ecology, 2012)
Targeted surveys for bilby, mulgara and spectacled hare-wallaby
Targeted Vertebrate Fauna Survey – January 2014 (Outback Ecology, 2014a)
Terrestrial vertebrate fauna impact assessment Terrestrial Vertebrate Fauna Impact Assessment – June2014 (Outback Ecology, 2014b)
Pre-clearing site clearances To be conducted prior to construction and operations
Terrestrial invertebrate fauna
Short range endemic invertebrate survey Terrestrial Short-range Endemic Invertebrate Fauna Baseline Survey – January 2013 (Outback Ecology, 2013a)
Targeted survey for mygalomorph spiders Targeted Mygalomorph Spider Survey – October 2013 (Outback Ecology, 2013b)
Short range endemic invertebrate impact assessment
Terrestrial Short-range Endemic Invertebrate Fauna Impact Assessment – June 2014 (Outback Ecology, 2014c)
Subterranean fauna
Subterranean fauna assessment (baseline surveys and impact assessment)
Subterranean Fauna Impact Assessment (Outback Ecology, 2014d)
Rehabilitation and closure
Geochemical assessment of waste rock Browns Range Rare Earth Element (REE) Project – Waste Rock Geochemical Characterisation – February 2014 (SRK Consulting, 2014)
Baseline soil and landform assessment Baseline Soil and Landform Assessment – June 2014 (Outback Ecology, 2014e)
Analogue slopes: soil and vegetation assessment Analogue Slopes: Soil and Vegetation Assessment – June 2014 (Outback Ecology, 2014f)
Preliminary geochemical assessment of tailings material
Browns Range Project Preliminary Geochemical Assessment of Tailings – June 2014 (Golder Associates, 2014b)
Radiological assessment of tailings Radiological Assessment of Tailings (JHRC Enterprises, March 2014)
Preliminary engineering design for TSF Browns Range Rare Earths Project – Tailings Storage Facility Summary Report (Knight Piésold, 2014).
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Factor Study Report
Rehabilitation and closure
Ecotoxicity of pit lakes Browns Range Brief Ecotoxicological Assessment on Pit Lake Water (Golder Associates, 2014c)
Landform erodibility Results of Runoff Sediment Study, Browns Range Rare Earth Project (Landloch Pty Ltd, 2014)
TSF cover design options TSF Cover Assessment (Klohn Crippen Berger, 2014d)
Pit lake water quality model Pit Lake Water Quality Assessment (Klohn Crippen Berger, 2014c)
Pit lake impacts on fauna Review of Impacts of Pit Lakes upon Fauna (Ecology Matters Pty Ltd et al, 2014)
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Table 4-2: Supporting studies timeline
Supporting studies 2011 and prior
Preliminary Key Environmental factors
Inland Waters (surface water)
Surface hydrology Field surveys
Pit lake water quality model Office- and laboratory-
Inland Waters (groundwater) based assessment
Browns Range hydrogeology
Water supply modelling
Flora and Vegetation
Baseline surveys and impact assessment
Terrestrial Fauna
Vertebrate fauna - baseline surveys
Vertebrate fauna - targeted surveys
Vertebrate fauna - impact assessment
Short-range endemic invertebrates - baseline survey
Short-range endemic invertebrates - impact assessment
Subterranean Fauna
Baseline surveys and impact assessment
Rehabilitation and Closure
Baseline soil and landform assessment
Analogue slopes: soil and vegetation assessment
Preliminary geochemical assessment
Waste rock geochemical characterisation
Preliminary geochemical assessment of tailings
Preliminary engineering design for TSF
Other Environmental Factors
Aboriginal heritage
Air quality
Energy and greenhouse gases
Noise
2012 2013 2014
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Table 4-3: EPA Guidance Statements, Environmental Assessment Guidelines, and Policies – outline of application in this assessment
EPA documentation Application in this assessment
Environmental Assessment Guideline No. 1 – Defining the Key Characteristics of a Proposal (EAG1)
Used to identify the key project characteristics as outlined in Section 1
Environmental Assessment Guideline No. 6 – Timelines for Environmental Impact Assessment of a Proposal (EAG6)
Used as a reference to ascertain likely timelines for the assessment process
Environmental Assessment Guideline No. 12 – Consideration of Subterranean Fauna in Environmental Impact Assessment in Western Australia (EAG12)
Used as a guide to interpret the results of subterranean fauna surveys and to form a view of the likely impact on subterranean fauna
EPA Position Statement No. 3 - Terrestrial Biological Surveys as an Element of Biodiversity Protection (PS3)
Used as guide to the overall approach to terrestrial fauna surveys; surveys were undertaken in accordance with PS3
EPA Guidance Statement No. 6 – Rehabilitation of Terrestrial Ecosystems (GS6) Used as a reference document in the development of the draft Mine Closure Plan
EPA Guidance Statement No. 19 – Environmental Offsets (GS19) Used as a guide to form a view of the likely offset requirements for the Project
EPA Guidance Statement No. 20 – Sampling of Short Range Endemic Invertebrate Fauna for Environmental Impact Assessment in Western Australia (GS20)
Used as a guide for the conduct of surveys for SRE invertebrates and to undertake the related impact assessment
EPA Guidance Statement No. 51 – Terrestrial Flora and Vegetation Surveys for Environmental Impact Assessment in Western Australia (GS51)
Used as a guide for the conduct of surveys for vegetation and flora and to undertake the related impact assessment. Surveys were undertaken in accordance with GS51
EPA Guidance Statement No. 54 – Consideration of Subterranean Fauna in Groundwater and Caves during EIA in WA (GS54)
Used initially but superseded by EAG 12
EPA Guidance Statement No. 54a –Sampling methods and survey considerations for subterranean fauna in Western Australia (GS54a)
Used to guide field surveys for subterranean fauna
EPA Guidance Statement No. 56 – Terrestrial Fauna Surveys for Environmental Impact Assessment in Western Australia (GS56)
Used as a guide for the conduct of surveys for terrestrial fauna and to undertake the related impact assessment
Guidelines for Preparing Mine Closure Plans (DMP and EPA, 2011) Used as a reference for the development of a draft Mine Closure Plan
Technical Guide – Terrestrial Vertebrate Fauna Surveys for Environmental Impact Assessment (EPA and DEC, 2010)
Used to guide survey methodologies for vertebrate fauna surveys
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Table 4-4: Summary of key findings for the Browns Range Rare Earths Project
Factor/aspect Key findings
Inland waters: surface water The risk of impacts to surface water is very low. Runoff from disturbed areas will be controlled using bunds, sediment ponds and diversion drains. Process water quality is such that even an embankment failure of the tailings storage facility is unlikely to cause surface water impairment beyond the immediate area. Civil road works, such as floodways and culverts, can be managed under the Rights in Water and Irrigation Act 1914.
Inland waters: groundwater The proposal is remote from existing groundwater users. Hydrogeological modelling of pit dewatering and extraction from the borefield has shown that no discernible impacts on existing water users, culturally significant water features or groundwater-dependent vegetation are likely. The mineral wastes arising from the Project are unlikely to significantly affect groundwater quality at a local or regional scale. Pit lakes will from in each of the proposed mine pits at closure. Water quality is expected to be brackish to moderately saline. The lakes will function as groundwater sinks.
Terrestrial vegetation and flora Establishment of the mine and infrastructure will require 711 ha of land clearing. No threatened species, Threatened Ecological Communities (TECs) or Priority Ecological Communities (PECs) will be affected. With respect to other species of conservation interest, impacts on the majority can be avoided. Impacts will occur on 2 Priority-listed species and 1 which is nominated for Priority listing. Impacts to a restricted vegetation association, VA13, will also occur, although alternatives are being considered to reduce or eliminate that impact.
Terrestrial vertebrate fauna Land clearing will remove fauna habitat, although habitat is widespread and in good condition. A range of measures has been identified to reduce the impact of the Project on terrestrial vertebrate fauna. These measures include pre-clearing surveys for key species, traffic controls and prevention of the establishment of local populations of feral animals.
Terrestrial invertebrate fauna 19 species of potential short-range endemic (SRE) invertebrates were identified. One habitat with high potential for SRE species can be avoided and will not be disturbed. A second habitat with moderate potential will be partially affected by land clearing. However, no loss of biodiversity is anticipated.
Subterranean fauna Surveys identified a number of species of stygofauna of potential conservation concern. However, stygofauna habitat is widespread in the Project area and it is unlikely that any species would be restricted to areas of impact. Surveys also recorded two species of troglofauna, but these were recorded outside of impact areas. No impact on the biodiversity of subterranean fauna is predicted.
Rehabilitation and closure At closure, land within the Project will revert to customary land uses and pastoral purposes. A conceptual mine closure plan has been prepared and will be updated during the life of the Project in consultation with the Traditional Owners and other stakeholders. No significant residual effects on public safety or environmental quality are predicted.
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5 INLAND WATERS: SURFACE WATER
Table 5-1: Environmental factor: inland waters (surface water)
EPA objective Existing environment Potential impact (without mitigation) Proposed management Predicted outcome
Maintain the quality of groundwater and surface water, sediment and/or biota so that the environmental values, both ecological and social, are protected.
A surface water management and flood study was undertaken for the Browns Range Project (Golder Associates, 2014a).
Records indicate the long-term average annual rainfall is ~409 mm with a distinct seasonal pattern, whereby ~80% occurs from December to March. Rainfall during this period is associated with the passage of tropical cyclones. The average annual evaporation is ~3005 mm.
The Project site is situated in the upper reaches of a minor tributary located centrally within the Sturt Creek drainage catchment. Runoff from the overall Sturt Creek system ultimately flows into Lake Gregory located 220 km downstream of the mine area (Figure 5-1). The area of the Sturt Creek drainage catchment is ~55,000 km2.
Sturt Creek comprises 2 major tributaries, one aligned in a NE-SW direction draining the northern section of the catchment and the other in a generally E-W direction draining the southern section. All watercourses in the catchment are ephemeral and typically only flow following larger storm events or prolonged periods of rainfall.
Several relatively small ephemeral watercourses drain the mine area in a westerly direction, joining the Sturt Creek 140 km upstream of Lake Gregory. No
Contamination of surface waters – tailings storage embankment failure
Though highly unlikely, an embankment failure at the TSF has the potential to cause process water to enter local drainage lines. Downstream contamination could result.
Golder Associates (2014a) undertook a dam break analysis. The analysis assumed a TSF crest height of 15 m and a tailings height of 11.5 m.
The analysis also assumed that a volume of water overlying the tailings and extending to the crest, ~450 ML, was lost in a failure.
Under wet season conditions, Golder Associates concluded that the discharge would comprise about 0.7% of the flow volume in sub-catchment 2 (Figure 5-2), about 0.05% of the flow volume at the confluence of sub-catchments 1 and 2, and about 0.02% of the flow volume at the inlet to Lake Gregory.
Tailings water will typically be a combination of water from the concentrator (75%) and from the hydrometallurgical plant (25%). Based on calculations of water quality from local water sources and considering the chemical amendments in each plant, the quality of tailings water would be expected to meet ANZECC and ARMCANZ guidelines (2000) for livestock, with the exception of TDS which will be slightly higher. Under a dam
The water management strategy does not require release of process water to the environment.
The TSF will be constructed in accordance with guidelines issued by the DMP. Design and construction of the facility will require separate approval under the Mining Act 1978.
Catchment and water quality calculations show that, in the unlikely event of a wall failure, there is little risk to sensitive downstream receptors, mainly due to the expected water quality in the TSF, the size of the catchment and the distance any discharge would need to travel.
Water quality in the TSF does not pose a risk to downstream receptors.
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EPA objective Existing environment Potential impact (without mitigation) Proposed management Predicted outcome
permanent or semi-permanent water bodies are located in the vicinity of the mine area.
The topography around the Project is generally subdued, rising from ~430 m AHD at the outlet of a drainage line south of the Project area to ~480 m AHD in the vicinity of the pits, WRLs and majority of mine infrastructure. Elevations rise to ~500 m AHD along ridges to the east and west of this infrastructure. Ground slopes along the main drainage lines through the mine area are low at ~5 m/km, increasing to ~10–15 m/km in the upslope areas. The rock outcrops in the area generally comprise Browns Range Metamorphics and Gardiner Sandstone.
Collection of baseline surface water quality has occurred since February 2013 and will continue through to and during operations (should the project be approved).
break scenario, water quality within the tailings storage facility would be diluted by rainfall occurring directly onto the facility.
Contamination of surface waters - sediments
In the event of heavy rainfall, disturbed land surfaces (WRLs, haul and access roads, processing area) have the potential to release sediment which could enter local drainage lines.
A range of water management measures is proposed (Figure 5-3):
diversion bunds around all pits and WRLs
sediment ponds collecting runoff from each WRL
a diversion drain around the airstrip.
Runoff from mine and processing and infrastructure areas potentially containing sediments and other materials can be readily managed.
Disruption of existing surface water flow patterns
The disruption of existing surface water flow patterns can lead to erosion and an increase in sediment content in surface water.
No rivers, creeks or drainage line will be blocked or diverted as part of this Project.
Within the mine and process plant area, minor diversions will be necessary to direct ‘clean’ water away from operational areas.
On the proposed access road, where floodways or culverts need to be constructed, applications will be made under section 17 of the Rights in Water and Irrigation Act 1914.
No significant changes to existing surface water flow patterns are proposed.
Contamination of surface waters - hydrocarbons
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EPA objective Existing environment Potential impact (without mitigation) Proposed management Predicted outcome
Diesel will be used to fuel the generators at the power station, haul trucks and light vehicles, and various other portable equipment. Leaks or spills of diesel, if substantial, could enter local drainage lines.
Diesel will be managed in accordance with AS 1940-2004.
Hydrocarbon spills occurring during field operations, e.g. burst hydraulic hose, will be managed according to management procedures covering the reporting and clean-up of spills away from controlled areas, such as workshops.
Hydrocarbons will be managed in accordance with industry standards.
Contamination of surface waters – acid rock drainage
SRK Consulting (2013) considered the potential for waste rock at the Browns Range Project to generate acid rock drainage. They concluded that the waste rock samples ‘possess both low acid generation potential and low acid neutralising capacity, and potential acid generation is considered to be of low significance at the site’.
The potential for acid rock drainage is low. No management measure proposed for waste rock landforms. Runoff and seepage of stockpiled mineralised materials (ore stockpiles) at the ore processing facility will be controlled by means of engineered drainage systems and lined runoff ponds The tailings storage facility will include a geosynthetic membrane liner, cutoff trench and seepage collection drains, a store and release cover system and groundwater monitoring bores.
Generation of acid rock drainage is not anticipated.
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Figure 5-1: Regional hydrology
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Figure 5-2: Regional sub-catchments
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Figure 5-3: Proposed surface water management measures
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6 INLAND WATERS: GROUNDWATER
Table 6-1: Environmental factor: inland waters (groundwater)
EPA objective Existing environment Potential impact (without mitigation) Proposed management Predicted outcome
Maintain the quality of groundwater and surface water, sediment and/or biota so that the environmental values, both ecological and social, are protected.
Flow systems Reduction in availability to other groundwater users
Baseline studies conducted for the Browns Range Project (Klohn Crippen Berger, 2013) have identified three water-bearing stratigraphic units in the Project area. The shallow stratigraphy of the Project area is shown in Figure 6-1. The main water bearing zones at Browns Range are:
1. Fractured rock aquifer – Browns Range Metamorphics: A thick sequence of metamorphosed sediments with limited primary porosity. The unit is confined to semi-confined by overlying transported sediment and in situ weathered materials. Localised zones of high hydraulic conductivity are associated with secondary structures (e.g. faults, shears, joints). A shear zone trending in a general NW-SE direction has been identified at the Area 5 deposit.
2. Fractured rock aquifer – Gardiner Sandstone: Outcrops at the western margin of the Project area and extends in westward from the outcrop. East of the outcrop, this unit is largely absent from the Project area. The sandstone comprises medium-grained quartz and lithic arenites. The unit is deep and regionally extensive. Some recharge occurs via outcropping zones of the Gardiner Sandstone unit.
Mine dewatering and abstraction of groundwater have the potential to lower groundwater levels in the Project area and to change groundwater flows such that less water would be available in existing registered groundwater bores; at culturally significant sites, such as Banana Springs; or to support the needs of stygofauna and other aquatic or groundwater dependent ecosystems.
Klohn Crippen Berger (2014a, b) has assessed potential groundwater drawdowns resulting from implementation of the Project. The modelling of groundwater drawdowns included sensitivity analysis. Hydrogeological modelling for the proposed borefield has concluded that neither the proposed borefield nor mine dewatering will have an impact on water supplies at Ringer Soak (Figure 6-2). Negligible impacts are predicted at Banana Springs, meaning that the potential change in flow at the spring will be within normal seasonal flow variation. No impacts on existing registered groundwater bores are expected.
The maximum extent of the 1 m groundwater drawdown cones arising from mine dewatering varies across the various mining areas are:
~600 m from the pit perimeter at the
The main management actions proposed are:
Further hydraulic testing of the fractured rock aquifer near Area 5 will be carried out to confirm aquifer parameters.
An expanded network of groundwater monitoring bores will be installed and monitored to enable regular checking of water levels and water quality between the mine site and Banana Springs.
The network of groundwater monitoring bores on the minesite will be expanded to enable routine monitoring of groundwater near the mine pits (to verify model predictions) and near potential pollution sources and or seepage sources—notably the processing plant, evaporation pond, WRLs and the TSF.
Further hydrogeological assessment of the Gardiner Sandstone aquifer will be conducted as part of detailed borefield design to confirm the predicted sustainable borefield yields estimated on the basis of studies completed to date.
No discernible impacts on the quantity of water available to existing bore users are predicted. No discernible impacts are likely to occur at culturally significant water features.
Permanent pit lakes will form at mine closure. The predicted average quasi steady-state pit lake levels of water in the pit lakes is expected to stabilise at levels below the pre-mining water levels (~2 m at Area 5 and up to 23 m at Wolverine). Because of high evaporation in the Project area, it is unlikely that quasi steady-state groundwater pit lake levels in the pit will ever fully recover to pre-mining levels.
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EPA objective Existing environment Potential impact (without mitigation) Proposed management Predicted outcome
3. Unconfined alluvial aquifer: This unit is mainly localised along drainage lines and saturated conditions in this layer are present only during and immediately following the wet season. Some seasonal leakage from the alluvial aquifers to underlying fractured rock aquifers is likely.
Overall, annual recharge to the fractured rock aquifers is expected to be low: in the order of 1–3% of annual precipitation.
The depth to groundwater in the Project area is variable, ranging from ~7 m to >25 m below ground surface, and reflects (in a subdued way) surface topography of the area. Static water levels in boreholes were observed to be shallower than the depths of water strike during drilling, which is an indication that the fractured aquifers are confined or semi-confined. The regional groundwater flow direction is from east to west, at an estimated hydraulic gradient of 0.001.
Wolverine deposit
~300 m from the pit perimeter at the Gambit and Gambit Central deposit
~660 m from the pit perimeter at the Gambit-West deposit
~220m from the pit perimeter at the Area 5 deposit; this drawdown cone will be elongated, with the long axis running parallel to the NW-SE trending shear zone.
In no instance will drawdown cones intersect existing registered groundwater bores, water dependent vegetation communities or culturally significant water features. The potential effects of groundwater drawdown on subterranean fauna are discussed in Section 11.
Water quality Contamination of groundwater
Groundwater quality in the project area is generally fresh to brackish, with an average total dissolved solids concentration of ~2000 mg/L (Table 6-2). There is one part of the mining tenement area (remote from any proposed mining or water abstraction activities) which is known to have much higher salinity, ~20,000 mg/L. Groundwater pH ranges from slightly acidic to slightly alkaline. Dissolved metals concentrations are generally low and with the exceptions of
The following proposed activities have the potential to affect groundwater quality in the Project area:
storage and handling of mineralised materials (ore, mineral concentrates, waste water evaporites)
storage of tailings
formation of permanent pit lakes at mine closure
transport, storage and use of fuels and reagents.
There is a very low likelihood of significant adverse impacts on beneficial use of groundwater in the Project area, as the mine wastes (including waste rock and tailings) are not radioactive, are non-saline and have a low risk of acid generation.
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EPA objective Existing environment Potential impact (without mitigation) Proposed management Predicted outcome
localized areas where the groundwater is naturally saline, the water is suitable for watering of livestock. The nearest DoW registered bore is located ~17 km NW of the proposed Wolverine pit.
Additional information on groundwater monitoring locations and results of groundwater monitoring to date is provided in Appendix B. Groundwater monitoring will continue to build the baseline database. Where required, ultratrace analyses will be used to inform closure planning.
Storage and handling of mineralised materials
Baseline studies have been conducted to assess the radiological and geochemical properties of waste rock, including mineralised waste rock (SRK Consulting, 2013; 2014), as described in Appendix C. While the ore is not radioactive, it does have some potential for acidification and also contains elevated total levels of some trace elements, notably rare earth elements, boron, selenium and arsenic. Leachability testing of the mineralised materials suggests that the metals and metalloids are sparingly soluble when exposed to water and runoff from stored materials is unlikely to contain dissolved contaminants at concentrations that would be harmful to people, plants or animals.
Mineralised materials including ore will be stored on engineered surfaces within the Browns Range ore processing facility. The storage areas will be provided with drainage to exclude surface water runoff from the stored materials. Any water (incident rainfall) that has been in contact with the mineralised materials will be collected and directed to a sump, from where the water can be recycled to the ore processing facility or (if unsuitable) disposed of in the evaporation pond.
Mineral concentrates and rare earth oxide product will be stored on concrete-paved and bunded areas. Frequent wash-down of these areas will be undertaken. Spillage will be promptly cleaned up and recycled back into the process stream.
Tailings storage
Tailings water will typically be a combination of water from the concentrator (75%) and from the hydrometallurgical plant (25%). Based on calculations of water quality from local water sources and considering the chemical amendments in each plant, the quality of tailings water would be expected to meet ANZECC and ARMCANZ (2000) guidelines for livestock, with the exception of TDS which will be slightly higher.
Tailings solids will mostly consist of rejects from the beneficiation plant (90% by mass). Mineralogical testing shows it consists mainly of non-reactive minerals (illite/muscovite and quartz). No sulphides were detected. Geochemical testing has
Tailings will be stored in engineered containment cells designed and operated in accordance with DMP and ANCOLD (2012) requirements. The cells will be sited, constructed and operated in a way that satisfies WQPN27 recommendations (DoW, 2013). Tailings pipelines outside the plant area will be installed within bunds, to limit contamination in the event of a loss of containment. Pipelines will be equipped with pressure sensors to detect changes in pressure that could indicate pipeline leakage or rupture. The tailings storage facility will include a geosynthetic membrane liner, cutoff trench and seepage collection drains, a store and release cover system and
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EPA objective Existing environment Potential impact (without mitigation) Proposed management Predicted outcome
been carried out on tailings from the beneficiation plant and the hydrometallurgical plant (Appendix G). Both total and leachate concentrations of trace elements in the combined tailings stream are likely to be low, although the salinity of tailings and the characteristics of the salts (magnesium and sulphate) are high enough to justify some seepage control measures. The tailings deposited in the TSF will not be radioactive.
groundwater monitoring bores.
Pit lakes
The geology of the material exposed in wall rock of the Browns Range pits and underground mines is neither saline, reactive (acid generating) nor radioactive. Groundwater in the area is generally fresh to brackish. Over time, however, even the low concentrations of dissolved salts and metals in groundwater will progressively increase, due to the high evaporation rate in the Tanami. A pit lake study has concluded that the final pit lake water quality at Browns Range will depend primarily upon pit geometry and local groundwater quality (Klohn Crippen Berger, 2014c). All pit lakes will act as sinks. The pit lake modelling does not predict the development of density-driven groundwater salinity plumes, though the pit lakes are predicted to become saline (Appendix E). This is because the salinities predicted to develop in the long term are still lower than the concentrations that would be required to cause density driven flow. Also, the transmissivity of the surrounding rock formations is generally
The pit lakes that will form at Browns Range will not be radioactive and are unlikely to be chemically hazardous (Appendices P2, P3 and P4) although over time pit lake water will become progressively more saline due to the strong evaporative demand in the project area. NML is currently exploring water management strategies for mine closure, including the possibility of directing surface runoff from some waste landforms into the pit voids to provide a periodic injection of freshwater. The main management actions required in relation to pit lakes relate to providing appropriate perimeter bunding to prevent accidental access to the pits by people or animals. In the long term, permanent pit lakes could attract a range of fauna, potentially leading to increased competition, predation or herbivory. At the same time, permanent pit lakes containing good quality water could offer potential benefits for post-mining land uses. NML proposes to consult with Traditional Owners and other stakeholders about the implementation of Caring for
Pit lakes will become progressively more saline over time due to evaporative concentration, but are not predicted to become acutely toxic. It is possible that in the very long term (hundreds or thousands of years), the salinity of water in some pits may become sufficiently saline to exert a slight downward force at the base of the pit, which could result in some density-driven flow.
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EPA objective Existing environment Potential impact (without mitigation) Proposed management Predicted outcome
very low. Country initiatives to manage pit lakes and other post-mining landforms in the long term.
Transport, storage and use of fuels and reagents
Diesel fuel and a range of reagents will be transported and stored in bulk for the Project. Details of the reagents used in the processing of xenotime ore were provided in Section 2. A catastrophic failure of bulk storage facilities at the ore processing plant or a serious road accident involving loss of containment could result in release of fuel or reagents to the environment. In the absence of appropriate clean up, this could result in groundwater contamination.
Diesel will be managed in accordance with AS 1940-2004.
Hydrocarbon spills occurring during field operations, e.g. burst hydraulic hose, will be managed according to management procedures covering the reporting and clean-up of spills away from controlled areas, such as workshops.
Fuels, acids, alkalis and all materials classified as dangerous goods or hazardous materials will be stored in accordance with relevant Australian Standards. Dangerous goods will be transported in accordance with the Australian Code for the Transport of Dangerous Goods by Road & Rail (National Transport Commission, 2011).
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Table 6-2: Summary of groundwater quality monitoring
Parameter Units No of Results
No of Detects
Min Conc
Max Conc
Average Conc
Median Conc
Alkalinity as CaCO3 mg/L 43 43 3 500 196 173
Aluminium mg/L 42 27 <0.01 3.97 0.61 0.105
Aluminium (Filtered) mg/L 44 19 <0.01 0.78 0.071 0.01
Ammonia as N µg/L 43 36 <10 2710 115 30
Anions Total meq/L 43 43 0.49 418 47 12.6
Antimony mg/L 42 6 <0.001 0.011 0.0011 0.0005
Antimony (Filtered) mg/L 42 0 <0.001 <0.005 0.00069 0.0005
Arsenic mg/L 42 17 <0.001 0.024 0.0028 0.0005
Arsenic (Filtered) mg/L 44 16 <0.001 0.022 0.0023 0.0005
Barium mg/L 42 42 0.007 0.855 0.099 0.0615
Barium (Filtered) mg/L 44 44 0.005 0.785 0.087 0.051
Beryllium mg/L 42 0 <0.001 <0.005 0.00069 0.0005
Beryllium (Filtered) mg/L 44 0 <0.001 <0.005 0.00068 0.0005
Bicarbonate mg/L 43 43 3 500 196 173
Boron mg/L 28 23 <0.05 1.48 0.37 0.245
Boron (Filtered) mg/L 28 23 <0.05 1.5 0.39 0.255
Cadmium mg/L 42 3 <0.0001 <0.0005 0.000075 0.00005
Cadmium (Filtered) mg/L 44 0 <0.0001 <0.0005 0.000068 0.00005
Calcium (Filtered) mg/L 43 42 <1 725 93 33
Carbonate mg/L 43 0 <1 <1 0.5 0.5
Cations Total meq/L 43 43 0.55 406 48 12.8
Chloride mg/L 43 43 12 12,300 1263 198
Chromium (III+VI) mg/L 42 20 <0.001 0.012 0.003 0.0025
Chromium (III+VI) (Filtered) mg/L 44 10 <0.001 0.005 0.0011 0.0005
Cobalt mg/L 42 18 <0.001 0.032 0.0022 0.001
Cobalt (Filtered) mg/L 44 13 <0.001 0.029 0.0018 0.0005
Copper mg/L 42 37 <0.001 0.372 0.019 0.005
Copper (Filtered) mg/L 44 31 <0.001 0.02 0.0036 0.002
Electrical conductivity *(lab) µS/cm 43 43 60 33,200 4085 1270
Fluoride mg/L 41 35 <0.1 1.2 0.55 0.6
Hardness as CaCO3 (Filtered) mg/L 41 40 <1 9720 1149 276
Ionic Balance % 31 31 0.05 5.73 2.2 1.99
Iron mg/L 44 32 <0.05 6.22 0.96 0.31
Iron (Filtered) mg/L 43 21 <0.05 3.65 0.33 0.06
Kjeldahl Nitrogen Total mg/L 16 11 <0.1 1.1 0.25 0.2
Lead mg/L 42 15 <0.001 0.02 0.0024 0.0005
Lead (Filtered) mg/L 44 2 <0.001 <0.005 0.0007 0.0005
Magnesium (Filtered) mg/L 43 42 <1 1920 211 40
Manganese mg/L 42 41 <0.001 2.19 0.16 0.0195
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Parameter Units No of Results
No of Detects
Min Conc
Max Conc
Average Conc
Median Conc
Manganese (Filtered) mg/L 44 41 <0.001 1.29 0.11 0.0195
Mercury mg/L 42 0 <0.0001 <0.0001 0.00005 0.00005
Mercury (Filtered) mg/L 44 0 <0.0001 <0.0001 0.00005 0.00005
Molybdenum mg/L 42 12 <0.001 0.013 0.0015 0.0005
Molybdenum (Filtered) mg/L 42 10 <0.001 0.01 0.0012 0.0005
Nickel mg/L 42 30 <0.001 0.043 0.0039 0.0025
Nickel (Filtered) mg/L 44 29 <0.001 0.035 0.0027 0.002
Nitrate (as N) mg/L 43 42 <0.01 4.97 1.2 0.97
Nitrite (as N) mg/L 43 7 <0.01 0.02 0.0067 0.005
Nitrogen (Total Oxidised) mg/L 43 42 <0.01 4.97 1.2 0.97
Nitrogen (Total) µg/L 16 14 <100 5900 1569 1250
pH (Lab) pH units 43 43 5.56 8.17
Phosphorus mg/L 16 12 <0.01 0.12 0.038 0.0275
Potassium (Filtered) mg/L 43 43 3 374 56 27
Reactive Phosphorus as P mg/L 42 19 <0.01 0.18 0.018 0.0075
Selenium mg/L 42 0 <0.01 <0.05 0.0069 0.005
Selenium (Filtered) mg/L 42 2 <0.01 0.06 0.0086 0.005
Sodium (Filtered) mg/L 43 43 6 4640 562 163
Sulphate (Filtered) mg/L 43 43 1 3180 367 79
TDS mg/L 28 28 39 20,100 2130 789.5
Thorium µg/L 42 21 <1 18 2.9 1.5
Thorium (Filtered) µg/L 42 2 <1 <5 0.71 0.5
Tin mg/L 42 3 <0.001 0.006 0.00089 0.0005
Tin (Filtered) mg/L 42 2 <0.001 <0.005 0.00071 0.0005
TSS mg/L 2 2 5 24 14.5
Uranium µg/L 42 27 <1 192 31 4
Uranium (Filtered) µg/L 42 25 <1 120 23 2.5
Vanadium mg/L 42 3 <0.01 <0.05 0.0077 0.005
Vanadium (Filtered) mg/L 44 2 <0.01 <0.05 0.007 0.005
Zinc mg/L 42 31 <0.005 1.29 0.21 0.031
Zinc (Filtered) mg/L 44 40 <0.005 1.35 0.18 0.017
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Figure 6-1: Hydrogeological features
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Figure 6-2: Water modelling – borefield drawdown contours
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7 TERRESTRIAL VEGETATION AND FLORA
Table 7-1: Environmental factor: terrestrial vegetation and flora
EPA objective Existing environment Potential impact (without mitigation) Proposed management Predicted outcome
Maintain the representation, diversity, viability and ecological functions at the species, population and community level.
Surveys were conducted across a Study Area of 16,135 ha in May 2012 and May 2013. The Study Area encompasses a Development Envelope of 8665 ha within which land clearing to implement the Project will occur. Land clearing of up to 711 ha for the Development Footprint is proposed.
The Project occurs within the Tanami 1 sub-region as defined within the Interim Bioregions of Australia (IBRA) classification system. Within the Study Area, 19 vegetation associations were identified across the study area (see Figure 7-1 and Figure 7-2). Three vegetation associations—Eucalyptus brevifolia (rocky hills), E. brevifolia (plains) and E. chlorophylla (plains)—comprise more than 70% of the study area. None of the vegetation associations identified represents a TEC or a PEC.
No groundwater-dependent ecosystem (GDE) was recorded within the study area. The nearest known GDE is Sturt Creek, to the north and west of the Study Area. However, 5 vegetation associations are associated with broad floodplain and drainage areas. While these are believed to be dependent on surface water flows rather than groundwater, some contain Eucalyptus victrix which is known to be a facultative phreatophyte i.e. it may use groundwater when available.
Loss of diversity - vegetation associations – through land clearing
Clearing of up to 711 ha is proposed. Over 70% of the proposed clearing will occur across 3 vegetation associations, all of which are widespread and common across the study area.
Most vegetation associations are well represented across the Study Area and will not be disproportionately affected by clearing to establish the Development Footprint.
VA13, E. victrix low-lying depression, was scheduled for clearing to access clay for construction materials. Following consultation with government, a geosynthetic membrane liner will now be used for the TSF. This will result in a significant reduction in the requirement for clay construction materials. Consequently, clearing of VA13 will not be required.
As a general principle, land clearing will only be conducted where it is necessary to establish operational areas for the Project. To ensure the land clearing process occurs under controlled conditions, a Ground Disturbance Permit (GDP) system will be introduced. The GDP system will require an internal application to clear land to be submitted. The application will be assessed against a database of approved areas and sensitive environmental and heritage locations. Clearing will only proceed with the approval of a senior manager. Depending on the area that is the subject of the GDP request, conditions may be applied. The performance of the GDP system will be audited. The extent of clearing will be reported in Annual Environmental Reports to the DMP.
Vegetation clearing will not affect any TECs or PECs. Clearing controls will be in place to minimise the Development Footprint to that necessary for construction.
Loss of diversity – flora – through land clearing
A total of 21 species of conservation interest have been identified (Table 7-2). These include Priority-listed species and other species for which significant range extensions have been recorded.
For 18 of these species, impacts can be readily avoided as they do not occur within the Development Footprint. For the remaining
While impacts on species of conservation interest can largely be avoided, the GDP system outlined above will provide protection from unintended impacts. Records of all known locations of Priority flora or other flora of interest will be maintained in a GIS database.
During detailed project design, opportunities
No threatened species was recorded during surveys. A small proportion of the local populations of 2 Priority-listed species which occur in the Study Area will need to be cleared.
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EPA objective Existing environment Potential impact (without mitigation) Proposed management Predicted outcome
Vegetation was recorded to be in largely excellent condition. Some populations of weed species occur near existing roads and tracks, and laydown areas associated with mineral exploration activities.
No species protected under either the Wildlife Conservation Act 1950 (WA) or the Environment Protection and Biodiversity Conservation Act 1999 (Commonwealth) were recorded during surveys. However, some species that are listed as Western Australian Priority Flora and a range of other species of conservation significance were recorded (see Table 7-2):
4 Priority-listed species
2 species nominated for inclusion as Priority species
6 species with ‘medium’ range extensions (see Table 7-2 for definition)
6 species with ‘high’ range extensions
2 species not previously recorded in Western Australia
1 undescribed species.
3 species, the following impact from clearing is anticipated:
Goodenia crenulata (P3) – 3 populations (~270 plants) will be cleared, representing about 4% of the total population recorded in the study area.
Trachymene villosa (P1) – 1 population of 1 plant will be cleared, representing about 2% of the total population recorded in the study area.
Brachychiton multicaulis (Nominated for Priority list) – 9 populations (~70 plants) will be cleared, representing about 26% of the total population recorded in the study area. This species has numerous records in the Northern Territory to the east of the Project site (see Figure 31 in Appendix J).
to reduce impacts on Brachychiton multicaulis will be examined.
While it is a requirement for all flora collection license holders to submit samples of the flora collected, including Priority, Potential Threatened Flora or other specimens of interest to the Western Australian Herbarium, this Project will result in a significant increase in the knowledge of the distribution, taxonomy and ecology of the flora of the Tanami region. Up to 200 vouchered specimens are expected to be contributed to the Western Australian Herbarium.
Losses will also occur of individuals of a third species which is nominated for the Priority list.
Increased competition for resources from weed species
Some weed species—notably Cenchrus setiger (birdwood grass) and Stylosanthes hamata (Verano stylo)—were recorded in disturbed areas. Construction and operations have the potential to introduce new weed populations or to spread existing ones. Weeds compete with native plant species for limited resources.
A weed hygiene system will be introduced. This system will apply to all construction and operational activities. The system will ensure that:
all equipment brought into the Project area is free of weed seed and soil material that could contain weed seeds;
known populations of weeds are recorded on a GIS database
the potential for spread of existing populations of weeds will be managed through the application of conditions on approved GDP applications
control measures (spraying or burial) will be used where necessary
weed management activities will be routinely reporting in Annual
There are some local weed populations. Measures will be implemented to prevent the spread of existing weed populations and the introduction of other weeds.
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EPA objective Existing environment Potential impact (without mitigation) Proposed management Predicted outcome
Environmental Reports for the DMP.
Indirect impacts (foliar dust deposition)
Mining and processing operations will generate dust. If not controlled, dust can settle on foliage near active areas, potentially reducing plant condition.
Wheel-generated dust from haul and access roads will be managed by water truck.
Within the concentrator, all transfer chutes will have water misting devices to contain dust. Potential dust generation points at the crusher, dryer and calciner will have their own dedicated bag houses complete with cyclones.
Establishment of vegetation on topsoil stockpiles will be encouraged.
Other measures, such as control of dust generation from ore stockpiles using sprinklers, will be considered during the detailed design phase.
Dust generation from mining and related activities can be readily managed so as to prevent any significant environmental impacts.
Indirect impacts (changes to surface water drainage patterns)
Significant changes to surface water drainage patterns can affect plant species adapted to particular flooding regimes, especially where the duration of inundation is changed.
Investigations by Golder Associates (2014a) show that the most significant features of the mine (open pits, waste rock landforms, process plant) occur at points high in the local catchment. Surface water drainage systems to the NW and SW of the Project will not need to be dammed or redirected to facilitate construction.
There will be no significant changes to surface water flows. Most of the Project infrastructure is located high in the local catchment. Bunding and diversion drains will be constructed to control localised storm flows.
Due to its location in the landscape, only minor drainage control measures will be necessary for the access road, with no implications for natural drainage patterns.
No significant changes to surface water flows will occur. Therefore, no impacts on vegetation from a changed hydrological regime are anticipated.
Reduced access to groundwater by groundwater-dependent species due to mine dewatering and borefield water extraction
There are no known GDEs occurring within the Study Area. However, E. victrix is known to use
No management measures proposed. No impact on GDEs or plant species known to
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groundwater if available. This species features in several of the vegetation associations recorded within the Study Area.
Groundwater drawdown will occur in association with pit dewatering and borefield operations. However, none of the vegetation associations which include E. victrix occur within the cones of depression associated with groundwater extraction. Therefore, E. victrix will be unaffected.
access groundwater is anticipated.
Changes to vegetation communities arising from a change in fire regime
Changes in fire frequency or intensity arising from the mine’s operations have the potential to alter vegetation communities. Changes could include local decline or extinction of some species and the spread of weeds.
Burning of vegetation for any purpose will not be permitted unless it is in association with an approved land management practice.
Activities where there is a risk of fire accidentally occurring, such as welding or cutting near flammable material, will be controlled through Hot Work Permits.
During detailed design, a regime of fire protection equipment will be selected for appropriate areas across the site.
Management measures will be in place to prevent a change to the fire regime as a consequence of the mine’s operations.
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Figure 7-1: Vegetation associations occurring within proposed Project area (north)
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Figure 7-2: Vegetation associations occurring within proposed Project area (south)
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Table 7-2: Priority Flora and other species of conservation significance recorded in the Study Area
Species Ranking Comment
Brachychiton multicaulis Nom 53 populations of 266 plants mostly on broad floodplains
Corynotheca micrantha var.gracilis M 5 populations recorded
Cyperus haspans subsp. ?juncoides H 1 population recorded (location unknown)
Eleocharis ochrostachys P3 1 population of 6 plants on Eucalyptus victrix floodplain
Euphorbia ?inappendiculata M 1 population recorded
Euphorbia armstrongiana var. ?distans H 1 population recorded
Exocarpos latifolius M 1 population recorded
Fimbristylis pauciflora (s.l.) H 1 population recorded
Gomphrena flaccida M 1 population recorded
Goodenia arachnoidea H 1 population recorded
Goodenia crenata P3 51 populations of approximately 6200 plants on floodplains
Goodenia goodeniacea N 12 populations of 265 plants on floodplain
Goodenia sp. nov. U 1 population of 1 plant on a broad drainage area
Heliotropium uniflorum P1 1 population of 1 plant on a rocky ridge
Polymeria lanata (s.l.) H 3 populations recorded
Sesbania muelleri N 2 populations of 60 plants on rocky ridge
Stemodia sp, Tanami (PK Latz 8218) Nom 5 populations of 20 plants on small emergent rocky outcrops
Swainsona formosa M 1 population recorded
Trachymene villosa P1 10 populations of 46 plants on foothills
Vigna vexillata var. angustifolia H 1 population recorded
Whiteochloa airoides M 1 population recorded
Notes: H – Taxa not listed or nominated as a Priority species, but local populations represent a ‘high’ range extension over previously known specimens. A ‘high’ range extension occurs where the nearest other record is 100 km away and the taxa has not been recorded in an adjacent bioregion (Ord Victoria Plain, Great Sandy Desert). M – Taxa not listed or nominated as a Priority species, but local populations represent a ‘medium’ range extension over previously known specimens. A ‘medium’ range extension occurs where the nearest other record is 200–500 km away but the taxa has been recorded in an adjacent bioregion (Ord Victoria Plain, Great Sandy Desert). N – Taxa not previously known to occur in Western Australia. Nom – nominated for Priority status. P1 – Taxa with few, poorly known populations on threatened lands. P3 – Taxa with several, poorly known populations, some on conservation lands. U – Taxa is undescribed.
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8 TERRESTRIAL VERTEBRATE FAUNA
Table 8-1: Environmental factor: terrestrial vertebrate fauna
EPA objective Existing environment Potential impact (without mitigation) Proposed management Predicted outcome
Maintain representation, diversity, viability and ecological function at the species, population and assemblage level.
A baseline fauna survey was conducted in May 2012 with a subsequent targeted survey undertaken in December 2013.
The Study Area comprised 16,294 ha containing a Development Envelope of ~8665 ha within which the Project will be established and operated. The Development Footprint is approximately 711 ha.
Six vertebrate fauna habitats have been identified across the Study Area. Of these, Open Shrubland over Mixed Grassland on Sandy Plain is by far the most widespread (Figure 8-1). Studies concluded that all habitats were of limited significance as they had no particular value in supporting fauna of conservation significance or distinct faunal assemblages.
With regard to vertebrate fauna assemblages, those found in the Development Envelope and the broader Study Area are consistent with those known to occur in the surrounding landscape. No vertebrate fauna assemblages are believed to be restricted to the Study Area.
A total of 16 species of conservation significance were identified by the baseline survey as potentially being present in the Study Area. Seven of these are known to occur or have occurred in the Development Envelope:
Loss of diversity through land clearing (direct mortality)
Land clearing will be necessary to develop the mine and supporting infrastructure. The potential exists for direct mortality of fauna to occur during the land clearing process.
Land clearing will be conducted only when required for Project development.
Prior to clearing, site inspections will be conducted for active burrows and other signs of fauna habitation. Where practicable, fauna will be captured and translocated to similar habitat elsewhere.
There is some potential for fauna to be injured or killed during the land clearing process. This potential will be minimised through pre-clearing surveys that will collect and translocate target species.
Loss of diversity through land clearing (loss of habitat)
The Open Shrubland over Mixed Grassland on Sandy Plain habitat will be subject to the greatest clearing impact from the Project in terms of the amount of habitat affected; 6607 ha of this habitat type occurs within the Development Envelope. This habitat is widespread in the Study Area (Figure 8-1) and wider region and is considered to be of limited significance.
The Hummock Grassland on Rocky Hill and Hummock Grassland on Stony Plain habitat types occur in relatively small, disconnected patches across the Study Area.
Drainage Line habitat is likely to play an important role in facilitating the dispersal of fauna across the Study Area and wider region.
Clearing will be controlled using a GDP
system (see Section 7). Impacts on
hummock grasslands and drainage lines will be minimised.
When mining is finished, rehabilitation will partially re-establish local habitats.
Loss of fauna habitat will occur through the land clearing process, although all habitats present are widespread in the local area. The potential for ‘over clearing’ will be greatly reduced or eliminated through the use of a GDP system. Particular habitats will be avoided where practicable. When mining is finished, rehabilitation will seek to establish local plants and vegetation communities.
Loss of diversity through land clearing (loss of fauna assemblages)
Land clearing could disrupt particular fauna assemblages where these are restricted in
No specific management measures proposed.
No impact on local fauna assemblages is anticipated.
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EPA objective Existing environment Potential impact (without mitigation) Proposed management Predicted outcome
Greater Bilby (Macrotis lagotis) - Schedule 1 (WC Act)
Major Mitchell’s Cockatoo (Lophochroa leadbeateri) - Schedule 4 (WC Act)
Spectacled Hare-wallaby (mainland subspecies) (Lagorchestes conspicillatus leichardti) Priority 3 (DPaW Priority Fauna list)
Lakeland Downs Mouse (Leggadina lakedownensis) – Priority 4 (DPaW Priority Fauna list)
Bush Stone-curlew (Burhinus grallarius) - Priority 4 (DPaW Priority Fauna list)
Australian Bustard (Ardeotis australis) - Priority 4 (DPaW Priority Fauna list)
Oriental Plover (Charadrius veredus) – Schedule 3 (WC Act).
The Brush-tailed Mulgara (Dasycercus blythi) was targeted in the December 2013 survey, but was not recorded.
distribution. However, field studies did not identify any fauna assemblages that were restricted or largely restricted to the Development Footprint, and the Study Area was not determined to be an area of exceptionally high biodiversity from a regional point of view.
Altered behaviour, displacement or mortality of fauna of conservation significance
While the expected impact is low, the fauna studies concluded that the Project is likely to have the greatest impact on the Greater Bilby, Spectacled Hare-wallaby and the Bush Stone-curlew. The impacts on all other species of vertebrate fauna are expected to be negligible or minimal.
Sightings of the Greater Bilby and the Spectacled Hare-wallaby will be reported to DPaW.
Site inductions will include information on the identification and protection of fauna of conservation significance.
As outlined above, all areas to be cleared will be subject to site inspections. While the Bush Stone-curlew would be expected to disperse ahead of clearing activity, both the Greater Bilby (in burrows) and the Spectacled Hare-wallaby (in mature spinifex hummocks) could shelter within target areas. In the event that an active burrow is discovered, trapping and/or burrow excavation and recovery of Greater Bilbies would be required, followed by translocation. Inspections are expected to flush any Spectacled Hare-wallaby although Outback Ecology (2014b) noted that mature spinifex hummocks are not well represented.
There is some low potential for the Project to affect individuals of conservation-significant species. All personnel will receive training in identification and reporting on local species of conservation significance and pre-clearing site inspections will be undertaken to minimise mortalities occurring during land clearing. If necessary, translocation of Greater Bilbies from areas to be cleared will be undertaken.
Increase in local populations of feral animals
Feral cats were recorded during surveys and foxes are known to occur in the area. Both species are implicated with declines in populations of native animals, especially
Sightings of key feral animal species (cats and foxes) will be recorded.
Putrescible waste will be managed so that it is not available as a food source for feral
The potential for Project infrastructure to inadvertently provide food and shelter to feral animals is acknowledged.
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EPA objective Existing environment Potential impact (without mitigation) Proposed management Predicted outcome
small marsupials, birds and reptiles. Infrastructure in a remote area can inadvertently supply food and shelter to feral animals, leading to an increase in the local population.
animals.
If required, trapping and humane disposal will be undertaken for any cats and foxes found in and around mine infrastructure.
Control measures are proposed to reduce or eliminate this potential.
Degradation of downstream habitat through changes to surface water drainage patterns
Significant changes to surface water patterns can degrade fauna habitat.
Surface water patterns will be retained to the extent practicable (see Section 5).
Degradation of downstream habitat through changes to surface water patterns is not anticipated as existing surface water patterns will be maintained.
Entrapment in trenches, drill holes, and dams
Various excavations, particularly during the construction phase, have the potential to entrap fauna species, leading to direct mortality or increased exposure to high ambient temperatures and predators.
During construction, regular inspection and clearing of trenches will be undertaken by environmental personnel to ensure small mammals and reptiles are able to take shelter.
All drill holes will be capped.
Lined water holding facilities will have fauna egress matting to allow a means of escape for small animals entering the water.
The Project poses some risks to fauna entering the site, particularly during construction. These risks can be managed using standard industry measures to minimise impacts on fauna.
Utilisation of water sources by fauna – toxicity effects
Several water sources will be potentially accessible to some fauna. These include a water storage dam and an evaporation pond in the process plant area and, post-closure, lakes will form in the open pits. However, human activity during operations is likely to discourage fauna use of the dams.
After closure, access to pit lakes by animals other than birds will be difficult due to the
No specific management measures proposed for dams.
Closure drainage design will be reviewed, with a view to assessing the effect of flooding of mine pits with low salinity runoff water on long term water quality. Northern Minerals will commit to adjusting the mine schedule to directly backfill the Gambit Central Pit from the adjacent Gambit Pit if further iexploration to the end
Data to date does not indicate any significant risk to fauna of water quality in pit lakes forming after closure.
Impacts on migratory birds are unlikely as main exposure to potentially hazardous dissolved substances in pit lake water would be through ingestion of drinking water for migratory
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EPA objective Existing environment Potential impact (without mitigation) Proposed management Predicted outcome
presence of abandonment bunds and the pit configurations (steep, high pit faces)Preliminary modelling of pit lake water quality up to 1000 years following cessation of mining has predicted that evaporative concentration of pit lake water will eventually result in concentration of salts and metals to a level that will, in some instances, exceed ANZECC ecological guideline values and/or livestock drinking water guidelines.
of Year 3 of the mining operation does not encounter additional mineable mineral resources below the current Gambit Central Pit design.
Pit lake water quality monitoring will be carried out at Area 5, which is predicted to fill within 1 year of cessation of mining, with a view to validating the modelled pit lake behaviours. Planned observations of fauna occurrence at the Area 5 pit lake will also be carried out and recorded.
Northern Minerals will consult with Traditional Owners about adopting “Caring for Country” land management approaches to manage feral animals that might be attracted to pit lakes in the post-closure period.
birds and the estimated intake of dissolved chemicals would be insufficient to result in significant impacts.
Impacts on waders and other water birds would chiefly arise through ingestion of aquatic plants and animals in the pit lakes. A preliminary assessment of pit lake ecology has concluded that the deep, and largely nutrient poor pit lakes would be unlikely to support sufficient plant and animal development to serve as a significant dietary source and the lack of a shoreline habitat would also deter use by some birds. Overall, the likelihood of significant ecotoxicity effects on migratory and water birds is low.
Mortality and injury related to vehicle movements
Fauna are susceptible to being hit by vehicles, especially at night.
Traffic controls (e.g. speed limits, night time restrictions) will be used across the mine operations. With the exception of Area 5, the project is spatially compact and interactions with fauna are not expected.
While impacts at the population level are highly unlikely, there is potential for individual animals to be killed or injured by vehicle traffic associated with the Project. The potential for this to occur will be reduced by the management measures proposed.
Noise and vibration
Noise and vibration associated with construction and operations can induce behavioural change in local fauna, e.g. nest
No specific management measures proposed.
A limited localised impact on vertebrate fauna from noise and
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EPA objective Existing environment Potential impact (without mitigation) Proposed management Predicted outcome
abandonment or emergence from burrows, leading to negative impacts on local populations. The impact, however, is expected to be localised.
vibration is expected.
Artificial lighting
Artificial lighting can disrupt normal activities for some nocturnal fauna. The impact will be localised.
Artificial lighting will be designed to illuminate designated operational areas and limit illumination of the surrounding landscape using light shields.
A limited localised impact on vertebrate fauna from artificial lighting is expected.
Other
Other potential impacts on vertebrate fauna include:
reduction of habitat through establishment and spread of introduced plant species
loss of habitat through dust impacts on vegetation
fire arising from the mine’s activities.
Management of other impacts is discussed
in Section 7.
Potential impacts on vertebrate fauna from introduced plant species, dust and fire can be
managed (see Section 7).
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Figure 8-1: Vertebrate fauna habitats
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9 TERRESTRIAL INVERTEBRATE FAUNA
Table 9-1: Environmental factor: terrestrial invertebrate fauna (SRE invertebrate fauna)
EPA objective Existing environment Potential impact (without mitigation) Proposed management Predicted outcome
Maintain representation, diversity, viability and ecological function at the species, population and assemblage level.
Two surveys for SRE invertebrate fauna have been conducted at the Project. Following an initial baseline survey in January-March 2012, a targeted survey for mygalomorph spiders was undertaken in January-April 2013.
The baseline survey identified 5 invertebrate habitat types across a Study Area within which the Development Envelope occurs (Figure 9-1). Two of these habitat types—Internal Drainage and Seasonal Drainage Surface—were considered to be restricted within the Study Area, although additional areas of Seasonal Drainage Surface were identified outside of the Study Area during the targeted survey for mygalopmorph spiders. Habitat types that are restricted are more likely to support species with restricted distributions, and therefore support true SRE species.
Based on current scientific knowledge, none of the species collected were confirmed to be SRE species. However, 19 species recorded during this assessment were considered potential SRE species as defined by criteria used by the Western Australian Museum. These species were:
6 mygalomorph spiders
1 selenopid spider
4 scorpions
2 pseudoscorpions
Loss of diversity through land clearing (loss of habitat)
Of the 5 invertebrate habitat types identified, vegetation clearing within 3 habitat types is not expected to have an impact on SREs as the habitat types are not restricted; that is, they occur across the study area, and have a low potential to support SREs.
Internal Drainage was considered to have a high potential of supporting SRE species. It occurs in 2 small areas within the Development Envelope, although not within the proposed Development Footprint. No direct impacts on this habitat are anticipated.
Seasonal Drainage Surface is considered as having a medium potential to supporting SRE species. A total of 14% of the mapped distribution within the Study Area occurs within the Development Footprint, but it has also been recorded outside of the Study Area.
During project design, an exclusion zone (see Figure 9-1) was established around an area of Internal Drainage habitat close to areas where infrastructure was proposed. Planning has avoided this area.
During detailed design, the opportunity to reduce impacts on Seasonal Drainage Surface habitat will be explored but its proximity to the proposed Wolverine pit suggests options will be limited.
Impacts on a habitat type with a high potential to support SRE fauna can be avoided. There will be some loss (~14%) of a habitat type with a medium potential to support SRE fauna.
Loss of diversity through land clearing (loss of individual species)
Using a risk-based approach, the basis for which is outlined within EPA (2009), habitat can be used as a surrogate for inferring the distributional boundaries of the species.
Four potential SRE species restricted to the Development Envelope all occur within habitat types with a low potential of supporting SRE species. Therefore, the Project is unlikely to affect the long-term
No specific management measures proposed. No impact on any potential SRE species is anticipated.
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2 millipedes
4 slaters.
Four potential SRE species—Aname ‘MYG287’, Karaops ‘sp. browns range’, Isometroides ‘kimb1’ and Helicopodosoma ‘DIP044’—have only been collected from inside the Development Envelope.
persistence of any species, even if they have only been recorded within the Development Envelope.
Adverse changes to the fire regime
A change to the existing fire regime as a consequence of the mine’s operations could have an adverse impact on SRE populations.
See management measures proposed in
Section 7.
No impact on any potential SRE species is anticipated.
Degradation of downstream habitat through changes to surface water drainage patterns
Most of the infrastructure associated with the Project occurs high in the local catchment. No significant changes to existing surface water patterns are anticipated.
See management measures proposed in
Section 7.
No impact on any potential SRE species is anticipated.
Introduction and spread of weed species
Establishment or spread of weed populations could have an adverse impact on SRE populations.
See management measures proposed in
Section 7.
No impact on any potential SRE species is anticipated.
Other impacts (noise and vibration, dust, light)
Various emissions associated with mining, processing and support infrastructure could potentially impact local populations of SRE species.
See management measures proposed in
Section 8.
No impact on any potential SRE species is anticipated.
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Figure 9-1: Short-range endemic invertebrate habitats
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10 SUBTERRANEAN FAUNA
Table 10-1: Environmental factor: subterranean fauna
EPA objective Existing environment Potential impact (without mitigation) Proposed management
Predicted outcome
Maintain representation, diversity, viability and ecological function at the species, population and assemblage level.
Subterranean fauna (stygofauna and troglofauna) occur in a variety of subterranean environments. Stygofauna (groundwater fauna) are predominantly comprised of invertebrates, particularly crustaceans. Troglofauna (air-breathing subterranean fauna) are often relictual forms related to surface dwelling (epigean) groups and can be distinguished by characteristics associated with a below-ground existence, such as lack of pigmentation and reduced or no vision.
The stygofauna survey effort involved 160 net haul samples from 115 bores taken over 5 survey periods between May 2012 and December 2013. There is a natural bias towards recording species in impact areas due to the disproportionate distribution of sample sites (bore holes).
A total of 21 stygofauna species was recorded from the Browns Range Metamorphics and Gardiner Sandstone fractured rock aquifer systems.
Of the 21 stygofauna species recorded, 9 species were considered of potential conservation concern, because they had not been collected from outside the proposed Development Footprint. Of those 9 species, 7 were recorded from within proposed pit boundaries only (Bathynellidae-OES19, Bathynellidae-OES24, Bathynellidae-OES25, Metacyclops-OES20, Parabathynellidae-OES18, Parabathynellidae-OES26, and Parabathynellidae-OES27). For the remaining 2 species of potential conservation concern, Dussartcyclops-OES2 and Parastenocaris-OES1, the most important factor is the potential drawdown of groundwater in the proposed borefield.
With regard to troglofauna, a total of 59 litter traps were
Loss of habitat (stygofauna) – mining operations
The proposed mining is not considered likely to pose a significant long-term conservation risk to the 9 species of conservation concern. The widespread distribution patterns of other members of the stygofauna assemblage (many occurring sympatrically) indicated that:
suitable and extensive habitat was present adjacent to and outside proposed mining impact areas
it was likely that seemingly restricted species possess broader distribution ranges that extend beyond the proposed pit boundaries and associated modelled groundwater drawdowns.
Also of consideration is the limited area of habitat removal associated with mining excavation, relative to the much greater expanse of adjacent habitat remaining within the Browns Range Metamorphics. This habitat area covers approximately 40 km2 (see Figure 10-1 and Figure 10-2). On this basis, pit development and significant drawdown from mine dewatering would comprise less than 5% of available habitat. This does not consider the possibility that habitat for species occurring in the Browns Range Metamorphics extends into the Gardiner Sandstone. Two species were recorded in both.
No specific management measures proposed.
No impact is anticipated on local stygofauna populations from the proposed mining operations.
Loss of habitat (stygofauna) – borefield
Groundwater drawdown in excess of 1 m, as modelled for the proposed borefield in the Gardiner Sandstone, is not considered likely to pose a significant long-term conservation risk when taking the following into consideration:
widespread distribution patterns of other members of the
No specific management measures proposed.
No impact is anticipated on local stygofauna populations from the proposed borefield
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EPA objective Existing environment Potential impact (without mitigation) Proposed management
Predicted outcome
deployed in uncased exploration bore holes over 3 survey periods. A further 150 net haul scrapes, whereby a net is scraped along the uncased wall of an unlined bore hole, were also used to survey for troglofauna.
Only 2 putative troglofauna species, Nicoletiinae-OES10 and Projapygidae-OES2, were collected. This indicates that the widespread and contiguous regolith and weathered fractured rock geologies of the Project study area do not harbour a diverse troglofauna assemblage. Both species were collected in scrape samples with no troglofauna collected from any of the litter traps.
stygofauna assemblage occurring sympatrically demonstrated the presence of suitable and extensive habitat adjacent to and outside of the modelled 1 m drawdown contour, and the likelihood that Dussartcyclops-OES2 and Parastenocaris-OES1 have broader distribution ranges that extend beyond the modelled 1 m drawdown zone
large extent of saturated habitat that would persist in the immediate vicinity of the production bore during the operational life of the borefield (the Gardiner Sandstone extends more than 35 km to the west of the project area)
limited area of habitat ‘removal’ associated with the operation of the proposed borefield, relative to the large expanse of adjacent habitat remaining within both the Gardiner Sandstone.
operations.
Loss of habitat (troglofauna)
Troglofauna inhabit subterranean caves and voids. They can be geographically restricted if their habitat is not extensive. However, surveys recorded only 2 species, both of which were collected from outside of proposed pit boundaries and modelled groundwater drawdown zones. Therefore, the Project is not expected to have any impact on troglofauna.
No specific management measures proposed.
No impact is anticipated on local troglofauna populations from the proposed Project.
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Figure 10-1: Extent of Browns Range Metamorphics
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Figure 10-2: Browns Range Metamorphics – cross section
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11 REHABILITATION AND CLOSURE
Table 11-1: Environmental factor: rehabilitation and closure
EPA objective Existing environment Potential impact (without mitigation) Proposed management Predicted outcome
Ensure that premises can be closed, decommissioned and rehabilitated in an ecologically sustainable manner, consistent with agreed outcomes and land uses, and without unacceptable liability to the State.
The existing topography consists of generally subdued terrain, consisting of undulating sandplains with small ranges of rocky hills or ridges to a maximum height of ~25 m above the surrounding plain. Erosion from the natural rocky hills is generally low, although the sandy and finer grained soils in the low lying drainage lines may be more susceptible to water or wind erosion.
Shallow soils are generally non-dispersive (but with some exceptions) and are non-saline.
There are no permanent water bodies or water courses in the Project area.
Vegetation cover in the area is generally in excellent condition, as there has been little grazing of the land in recent times. Weed occurrence is very limited, mainly occurring along the existing access road from Ringer Soak.
Concentrations of trace elements (including metals and metalloids) in shallow soils at the site are generally low, although some samples of shallow alluvial soils showed selenium concentrations above published values for average global crustal abundance (Appendix C, Appendix F). Uranium and thorium concentrations in surface soils and barren overburden above the ore bodies
Erosion, land stability and water quality
Implementation of the Project will result in the construction of engineered landforms for the storage of mine wastes (tailings and waste rock). Mechanical disturbance of soils and rock may result in increased susceptibility to erosion by wind or water. Excavation of mine pits will result in steep rock faces that may be susceptible to geotechnical instability and/or erosion.
Ineffective drainage and landform design or implementation could result in concentration of surface flow, increasing erosion hazard. In the case of the integrated waste landform (of which the TSF is part), inappropriate design and construction could result in failure of final cover layers or embankments.
Mechanical handling of soils and trafficking of soils by mobile plant has the potential to adversely affect the physical properties of soils as a result of compaction.
Reshaping of the land surface may alter surface hydrology, potentially affecting the frequency, magnitude and duration of flow and/or flood events at a local scale.
At Project completion, permanent pit lakes will form in each of the proposed mine pits (refer Table 6-1).
A conceptual mine closure and rehabilitation plan has been prepared (Appendix P1). The plan generally aims to ensure that post-mining land is safe, stable, non-polluting and suitable for customary land uses and pastoral purposes.
Rehabilitation of waste landforms will be implemented progressively. The scheduling of mine pit and underground development means that the Wolverine waste landform and the Gambit integrated waste landform will be largely available for rehabilitation trials and implementation of final rehabilitation works at least several years before the planned end of mining.
A post-mining pit lake is expected to form in the Area 5 open pit in approximately Year 5 or 6 of the 10 year mine life, which will provide an opportunity for observations on pit lake water quality and behaviour well before the end of the overall mine life
Detailed closure design will include consideration of various water management strategies, including possible diversion of some waste landform surface water flows to mine pits as an ongoing source of fresh water.
The built landforms at Browns Range are expected to blend visually with the surrounding natural terrain. There is a low risk of significant geotechnical instability or erosion that would result in sedimentation of receiving waters.
There will be ample opportunity to trial rehabilitation practices during the operating life of the Project.
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EPA objective Existing environment Potential impact (without mitigation) Proposed management Predicted outcome
are similar to the levels of these elements found in regional soils.
Soil contamination
In the absence of appropriate controls there is some potential for contamination of soils by spillage of fuels, reagents or process materials.
Uncontrolled seepage from stockpiled materials and/or from stored tailings could result in local salinization of soils.
Materials proposed to be stored in waste landforms and the TSF are not radioactive and are unlikely to give rise to acid or metalliferous drainage.
Major, undetected breaches of slurry pipelines are extraordinarily unlikely. Significant leakages of hydrometallurgical tailings could result in local contamination of soils and would require immediate response and clean up.
Operational controls will include spill response and clean-up procedures. A site contamination assessment will be conducted as part of planned mine closure. Sufficient baseline studies have been completed to allow an objective basis for assessing whether post-closure soil quality has been affected by mining operations.
Soil contamination that would affect the post-closure use of land for customary purposes or pastoral uses is not expected.
Biodiversity
Poor soil handling or storage practices could result in loss of topsoil or reduced viability of the soil seedbank.
Failure to implement appropriate machine and materials hygiene procedures could allow introduction or spread of weeds into an environment that is currently nearly free of weeds.
A topsoil inventory has been prepared as part of baseline studies. This inventory will be updated regularly during the operating phase of the Project.
Routine operational controls will include weed and pathogen hygiene measures.
NML proposes to seek the assistance and advice of Traditional Owners on the feasibility of implementing Caring for Country practices as a means of detecting and responding to weed or pest invasion.
Progress on mine rehabilitation will be reported annually to the DMP.
Some changes in vegetation type and vegetation cover will result from project implementation.
Management of weed and pathogen hygiene, in combination with Caring for Country initiatives should minimise weed incursion.
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EPA objective Existing environment Potential impact (without mitigation) Proposed management Predicted outcome
Public safety, land use and land access
Open pits, underground workings, drillholes and water impoundments constructed during Project implementation have the potential to adversely impact safety and could entrap fauna.
During the operations phase, access to the site will become easier as a result of road upgrades and the construction of an airstrip. Whether this increased accessibility should be retained at closure is a matter that will need to be discussed with stakeholders, especially Traditional Owners, as part of closure planning.
Final landform and pit design will be developed to satisfy DMP safety requirements. An updated mine closure plan will be submitted to the DMP as part of the Browns Range mining proposal. The rehabilitation and closure plan will be reviewed at least 3-yearly.
No significant risks to public safety are predicted at Project completion.
Land access arrangements at closure will take account of stakeholder preferences.
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12 OTHER POTENTIAL IMPACTS AND ACTIVITIES
Table 12-1: Other potential impacts and activities – other legislation and approvals
Environmental factor or issue
Description of impact or activity Approval mechanism
Responsible agency
Statute Management and mitigation
Air quality
Dust (mineral processing)
Crushing and milling of ore. Investigations involving air quality modelling are underway to identify any air quality issues that need to be considered during the detailed design phase.
Works Approval and Licence (Category 5)
Department of Environmental Regulation (DER)
Environmental Protection Act 1986 (Part V)
Water sprays in concentrator on conveyors and transfer points, not required in hydrometallurgical plant as it is a wet process.
Dust (mining) Wheel-generated dust, dust generated by blasting, dust from cleared areas. See above regarding air quality investigations.
Mining Proposal DMP Mining Act 1978 Deployment of a water truck on haul roads, stabilise topsoil stockpiles with vegetation.
Combustion emissions from power generation
Power station will emit CO, NOx, SO2 and VOCs. See above regarding air quality investigations.
Works Approval and Licence (Category 52)
DER Environmental Protection Act 1986 (Part V)
Maintain generators in good working order.
Gaseous emissions from hydrometallurgical pant
Likely off-gases yet to be determined. Works Approval and Licence (Category TBA)
DER Environmental Protection Act 1986 (Part V)
Scrubbers
Noise and vibration Noise and vibration associated with mining and processing activities. Investigations are underway to identify if any issues associated with the location of the village with respect to the process plant.
Compliance with the noise regulations.
DER Environmental Protection Act 1986 (Part V)
Environmental Protection (Noise) Regulations 1997
Design controls for occupational health and safety.
Aboriginal heritage Potential disturbance of Aboriginal heritage sites during land clearing. Two surveys have been conducted across the general area to date, primarily targeting areas associated with exploration activity for Browns Range. Further surveys will be required prior to construction.
Approval under Section 18.
Department of Aboriginal Affairs
Aboriginal Heritage Act 1972
Survey and assessment of all areas prior to construction. If necessary, submission of Section 18 application(s) to the Aboriginal Cultural Material Committee.
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Environmental factor or issue
Description of impact or activity Approval mechanism
Responsible agency
Statute Management and mitigation
Waste management Disposal of putrescible and inert wastes in a project landfill. Works Approval and Licence (Category 89)
DER Environmental Protection Act 1986 (Part V)
Environmental Protection (Rural Landfill) Regulations 2002
Construct and operate landfill in accordance with the regulations.
Greenhouse gas emissions
Emission of greenhouse gases, primarily through combustion of diesel fuel. An estimate of the expected annual Scope 1 greenhouse gas emissions has been compiled. The maximum annual Scope 1 emissions are approximately 72,000 t CO2e.
None required. Australian Government (Clean Energy Regulator)
National
Greenhouse and
Energy Reporting
Act 2007
Reporting to be conducted as required by Federal legislation.
Hazardous materials e.g. fuel, reagents
Transport and storage of hazardous materials: diesel fuel, explosives, other (H2SO4, NaOH, other reagents).
Dangerous Goods Licence
DMP (Resources Safety)
Dangerous Goods Safety Act 2004
Monitoring and compliance.
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13 BIODIVERSITY OFFSETS
Environmental offsets offer a way in which a project’s residual environmental impacts on critical or high value biodiversity assets can be ‘offset’. Offsets are actions that provide an environmental benefit (EPA, 2006b). These offsets can be direct (for example, rehabilitation of areas outside of the project to enhance biodiversity values) or indirect (such as a research programme into a critical environmental asset).
The Government of Western Australia (2011) identifies the principles on which decisions about offsets might be made:
Offsets are considered only after avoidance and mitigation options have been pursued.
Offsets are not appropriate where environmental impacts are minor.
Where offsets are appropriate, they should be proportionate to the significance of the environmental impact and based on sound information and knowledge.
Offsets should be adaptable where there is uncertainty.
Offsets should focus on longer term strategic outcomes.
In considering whether offsets are required under the Environmental Protection Act 1986, the EPA (2006b) recognises different environmental asset types:
‘critical assets’ which represent the State’s most important assets
‘high value assets’ which are not critical but are considered valuable
‘low to medium value assets’; offsets are not usually required for low to medium value assets.
Northern Minerals has considered the offset requirements for the Browns Range Project proposal and has completed the EPA’s Environmental Offsets Reporting Form (Appendix ). No critical assets will be affected by the Browns Range Project. However, good quality native vegetation is consistent with the definition of high value assets and an area of up to 711 ha will be cleared to implement the Project. While all disturbed areas will be rehabilitated at closure, some level of offset may be required to address the original disturbance.
Some preliminary internal discussions have been held in respect of land management initiatives that could occur within an Indigenous Protected Area (IPA), if the guidelines for establishment are met. IPAs are Australia’s equivalent to internationally recognised Community Conserved Areas, which are landscapes of natural or cultural significance that are voluntarily managed or conserved by local communities.
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14 SUMMARY AND CONCLUSIONS
Northern Minerals proposes to develop the Browns Range Rare Earths Project, a rare earths mine and mineral processing operation at a location approximately 160 km south-east of Halls Creek, Western Australia. The Project will produce rare earths for export. Rare earths are used in a wide range of technological applications with those occurring at Browns Range used particularly in clean energy applications.
In May 2013, the Project was referred to the Environmental Protection Authority for potential environment assessment under Part IV of the Environmental Protection Act 1986 (WA). After considering the referral, the EPA decided that the Project could be assessed using the Assessment on Proponent Information – category A level of assessment. The EPA subsequently produced a scoping guideline for the preparation of an environmental review (this document).
As required by the scoping guideline, the environmental review considers the following preliminary environmental factors:
inland waters: environmental quality
flora and vegetation
terrestrial fauna
subterranean fauna
rehabilitation and closure.
Each of these factors has been considered in detail through specialist studies, including baseline studies and impact assessment. The most significant impact relates to the clearing of up to 711 ha of native vegetation and fauna habitat to allow the establishment of the Project. While studies have shown that no threatened plant or animal species, or ecological communities will be affected, impacts will occur on some plant species and a vegetation association of conservation interest. Impacts in relation to other factors will also occur, but Northern Minerals has proposed a range of management measures to reduce impacts to acceptable levels. Overall, Northern Minerals is of the view that the EPA’s objectives can be met in relation to these preliminary environmental factors.
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15 GLOSSARY, ACRONYMS AND ABBREVIATIONS
Term Definition
Alkali A substance with a pH greater than 7.0 – also known as a ‘base’ or basic material
Alluvial Description of soil deposited by river or flooded water
Anion An ion possessing a negative electrical charge
Aquifer A water-bearing bed of permeable rock, sand or gravel
Areal The bounded part of the space on a surface
Arenite A sedimentary clastic rock with sand grain size between 0.0625 mm and 2 mm and containing less than 15% matrix
Arkose A detrital sedimentary rock, specifically a type of sandstone containing at least 25% feldspar
Arid An area with an average annual rainfall of less than 250 mm
Basin The area drained by a river or creek and its tributaries
Becquerel (Bq) The Standard International (SI) unit of measurement of radioactivity defined as one radioactive disintegration per second
Best practice The leading management practices used to prevent or minimise health, safety, environmental, social, cultural or economic impacts
Biodiversity The range of genetic, species and ecosystem diversity present in a given ecological community or system
Bioregion An area of land or water that contains a geographically distinct grouping of natural communities
Biota The sum of all living organisms of an ecosystem, or of a defined area or period
Blasting Detonation of explosive charge in a mine to break up rock
Bore A hole drilled into the ground to intersect an aquifer and from which water may be pumped
Brecciation The formation of breccia, or masses of rock composed of fragments of older rock fused together
Bund A wall constructed of earth, rock or concrete to prevent the inflow of stormwater to a mining or mineral processing operation or to act as a secondary containment to prevent the outflow of liquids from tanks or other storage vessels
Catchment The entire land area from which water (e.g. rainfall) drains to a specific water course or water body
Cation An ion possessing a positive electrical charge
Colluvial Describes material that has moved down slope due to gravitational forces
Cone of depression A cone-shaped draw down in the level of a water table caused by extraction of groundwater, usually by pumping
Cover sequence The layers of solid and sand rock overlying an orebody
Crusher That section of a processing plant that mechanically crushes the ore into smaller pieces
Cumulative effects The combined build-up of effects of multiple impacts of separate actions
Decay product The product of the spontaneous radioactive decay of a nuclide (a type of atom). A nuclide such as uranium-238 decays through a sequence of steps and has a number of successive decay products associated with it in a decay series
Decommissioning A formal process of removing a mine or infrastructure from being operational
Deposition Laying down of particulate materials (e.g. sediment in a lake or tailings solids in a tailings storage facility)
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Term Definition
Desktop study A study undertaken in the office rather than in the field
Dewater The removal of water
Dose equivalent A measure of the radiation dose to tissue where an attempt has been made to allow for different relative biological effects of different types of ionising radiation. Measured in Sieverts (Sv)
Dose (radiation) The radiation energy absorbed in a unit mass of material
Drawdown The fall of water-level in a natural reservoir such as an aquifer due to pumping or artesian flow
Ecology The science dealing with the relationships between organisms and their environments
Ecosystem The biotic (living) and abiotic (non-living) environment within a specified location in space and time
Emission A discharge of a substance such as dust into the environment
Endemic A species not naturally found elsewhere
Environmental Management System
A set of policies, procedures and practices detailing the approach required to protect environmental values at a given location
Ephemeral Something that is not permanent such as a stream that flows only seasonally or after rainfall, or a lake that periodically dries out, or a plant that is present seasonally
Ethnography The scientific description of societies and cultures of humankind
Evapotranspiration The sum of evaporation and plant transpiration from the Earth’s land surface to atmosphere. Evaporation accounts for the movement of water to the air from sources such as soil and water bodies. Transpiration accounts for the movement of water within a plant and the subsequent loss of water as vapour through the leaves
Fauna The animal life of a region or geological period
Feral An organism that has escaped from domestication and returned to its wild state
Flora The plants of a particular region, geological period or environment
Footprint The area of land taken up by a development
Frother A chemical additive which, when added to pulp, enables stable bubbles to be formed
Gamma radiation A form of electromagnetic radiation similar to light or x-rays, distinguished by its high energy and penetrating power
Grade The concentration of metal either in an individual rock sample or averaged over a specified volume of rock; uranium grade is usually given in per cent or ppm
Grader A vehicle used to smooth a soil or rock surface
Greenhouse gases The six gases listed in the Kyoto Protocol, capable of trapping heat within the Earth’s atmosphere: carbon dioxide: methane: nitrous oxide: hydrofluorocarbons: perfluorocarbons: sulphur hexafluoride
Groundwater Water that exists beneath the Earth’s surface in the pores and spaces of rock and soil
Groundwater mound The local rise of a water table above its natural level resulting from a localised source such as infiltration from the tailings storage facility
Habitat A specific place or natural condition in which a plant or animal lives
Halophytic A plant that naturally grows where it is affected by salinity in the root area or by salt spray
Haul trucks Heavy vehicles used to transport ore or waste rock
Hazard A source of potential harm, or a situation with a potential to cause loss or adverse impact
Heavy metals A metal of relatively high density (a specific gravity greater than about 5) or high relative atomic weight
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Term Definition
Heavy rare earth elements (HREE)
Elements with atomic numbers 62 through 71 (samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium).
Host rock Rock or geological formation that contains or surrounds an ore body
Hydrogeology The study of groundwater with particular reference to geology and including its origin, occurrence, movement and quality
Hydrology The study of water, particularly its movement in streams, rivers or underground
Indicator Any physical, chemical, biological, social or economic characteristic of the environment used to assess its environmental condition
Indigenous Belonging to or found naturally in a particular environment and referring to people of Aboriginal and Torres Strait Islander origin, including those who for census purposes, identify themselves as being of Indigenous origin
Infrastructure A set of interconnected structural elements that provide the framework supporting an entire structure including utilities and transport. It may refer to buildings, water pipelines, gas pipelines, transmission lines, roads, railways, airports
In situ In the natural or original position or place
Isotope Forms of a chemical element having the same number of protons but a different number of neutrons. All isotopes of the same element have the same chemical properties and therefore cannot be separated by chemical means
Leach Dissolution and removal of a soluble substance from a substrate
Leaching A chemical process for the extraction of minerals or solid constituent from ore
Light rare earth elements
The cerium group of elements (Sc, La, Ce, Pr and Nd)
Liquor An aqueous solution, emulsion or suspension
Mesa An elevated area of land with a flat top and steep sides
Mill Ore processing plant
Mine rock Overburden and mineralised rock that is uneconomic to process
Mine water All water used in mining and processing
Mineral resource A concentration or occurrence of material of intrinsic economic interest in or on the Earth’s crust in such form, quality and quantity that there are reasonable prospects for eventual economic extraction
Mineralisation The occurrence of metal or minerals within a rock sequence that may potentially constitute ore
Mineralogy The scientific study of minerals
Mitigation measure Action taken to minimise or lessen the impact of an activity on the environment or surrounding communities
Model A simplified representation (usually mathematical) of a complex system or event
Modelling The process of creating and using a model
Native Title The recognition in Australian law of the continued ownership of land by Indigenous Australians
Ore A mineral or mixture of minerals containing a metal in sufficient amounts for its extraction to be profitable
Ore body A solid mass of ore that is geologically distinct from the rock that surrounds it and can be mined profitably
Ore reserve The part of a mineral resource which can be mined and forms valuable or useful minerals that can be recovered economically
Overburden Material that is located above a deposit of ore, such as soil or rock which must be removed for the ore to be mined
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Term Definition
Particulate Tiny particles of solid or liquid suspended in a gas. They range in size from less than 10 nanometres to more than 100 micrometres in diameter
Permeability The capacity of a material to allow fluid(s) to pass through it
pH A measure of the degree of acidity or alkalinity of a solution expressed numerically on a scale of 1 to 14, on which 1 is most acidic, 7 is neutral and 15 is most basic (alkaline)
Potable water Water suitable for human consumption
Precipitation The process of changing from a dissolved compound into a solid, insoluble compound
Processing plant Where metals are extracted from a mined ore
Progeny The isotopes or elements formed by the nuclei of radionuclides during radioactive decay. Also known as ‘decay chain products’ and ‘daughter products’
Putrescible Predisposed to decompose, decay or spoil, especially by bacterial action
Radionuclide Any nuclide (isotope of an element) which is unstable and undergoes natural radioactive decay
Radon The heaviest of the inert gases. The predominant isotope, radon-222, is the decay product of radium-226. It has a half life of 3.8 days and decays to Polonium-218 by the emission of an alpha particle
Reagents The chemicals and solutions used in extracting metals from ore
Receiver A designated place at which an impact may occur
Receptor A designated place at which an impact may occur
Recharge The addition of water to an aquifer, directly from the surface, indirectly from the unsaturated zone, or by discharge from overlaying or underlying aquifer systems
Rehabilitation The process of restoring land to its previous natural state or to another use after mining has been completed
Reserve (mineral) The economically mineable part of a measured or indicated mineral resource
Resource A concentration or occurrence of natural, solid, inorganic or fossilised organic material in or on the earth’s crust in such form, quantity and quality that its extraction is likely to have economic benefit
Reverse osmosis Purification of water by forcing it under pressure through a membrane that is semi-permeable to remove impurities
Sedimentation The deposition of particles such as soil or organic material from a state of suspension in water or air
Seepage The flow of a fluid through soil pores
Semi-autogenous A form of grinding whereby grinding bodies, usually metal spheres, are added
Sensitive receiver A non-occupational area or group of people likely to be affected by potential impacts
Sievert (Sv) The SI derived unit of dose equivalent which attempts to reflect the biological effects of radiation as opposed to the physical aspects which are characterised by the absorbed dose and the quality factor and any modifying factor. It allows a comparison of the relatively greater biological damage caused by some particulates and fast neutrons. For most beta and gamma radiation, one sievert is equal to an absorbed dose of one joule per kilogram of biological matter
Speciation The conversion of one ion into another such as sulphide to sulphate
Stygofauna Fauna that live within groundwater systems, such as caves and aquifers
Sustainable development
Development that meets the needs of the present without compromising the ability of future generations to meet their own needs
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Term Definition
Tailings Crushed or finely ground mine rock suspended in water from which valuable minerals or metals have been extracted
Tailings storage facility
A retaining structure for tailings where the solids settle out and the tailings liquor is reclaimed for reuse or sent to evaporation ponds
Taxa A name designating an organism or group of organisms
Terrestrial Pertaining to land
Thickening The process of increasing the viscosity of concentrate and tailings by reducing the water content
Throughput Quantity of ore moving through an ore processing plant
Topography The study of the Earth’s surface features, concerned with local detail including relief and vegetative and human made features
Toxic Poisonous to a specific organism
Toxicity Effect of any substance that produces a harmful, acute or chronic effect on living organisms
Transect A line across a study area along which observations are made and changes can be observed
Transmissivity The rate at which groundwater is transmitted through rock of a specific dimension and at a specified hydraulic gradient
Troglofauna Subterranean animals adapted to life in permanent darkness. Unlike stygofauna, troglofauna live above the groundwater table (ie, they are not aquatic animals).
Water balance The sum of the inputs and outputs and changes in storage levels of water in a given locality
Water table The surface of the groundwater, below which soil and rock are saturated
Xenotime A phosphate mineral, mainly comprising yttrium phosphate (YPO4), but which also contains other rare earth elements including dysprosium, erbium, terbium and some metals such as thorium and uranium.
Abbreviation Description
ANCOLD Australian National Committee on Large Dams
ANSTO Australian Nuclear Science and Technology Organisation
ANZECC Australian and New Zealand Environment Conservation Council
ANZMEC Australian and New Zealand Minerals and Energy Council
API Assessment on Proponent Information
ARPANSA Australian Radiation Protection and Nuclear Safety Agency
DEC Department of Environment and Conservation
DER Department of Environmental Regulation
DITR Department of Industry, Tourism and Resources
DMA Decision-making authority
DMP Department of Mines and Petroleum
DoH Department of Health
DoW Department of Water
DPaW Department of Parks and Wildlife
EPA Environmental Protection Authority
EP Act Environmental Protection Act 1986
EPBC Act Environment Protection and Biodiversity Conservation Act 1999
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Abbreviation Description
GAI Global Abundance Index
GDE Groundwater dependent ecosystem
GDP Ground Disturbance Permit
GIS Geographic information systems
HRE Heavy rare earth
HREO Heavy rare earth oxide
IBRA Interim Bioregions of Australia
IMCOA Industrial Minerals Company of Australia
IPA Indigenous Protected Area
IX Ion exchange
LNG Liquefied natural gas
LOD Limit of detection
LRE Light rare earth
NML Northern Minerals Limited
OEPA Office of the Environmental Protection Authority
PEC Priority Ecological Community
pH Degree of alkalinity/acidity
RE Rare earth
REO Rare earth oxide
RMP Radiation Management Plan
RnDP Radon decay product
RO Reverse osmosis
ROM Run-of-mine
SAG Semi-autogenous grinding
SEWPaC Department of Sustainability, Environment, Water, Population and Communities
SRE Short-range endemic
TDS Total dissolved solids: a measure of salinity
TEC Threatened Ecological Community
TREO Total rare earth oxides
TSF Tailings storage facility
UNSCEAR United Nations Scientific Committee on the Effects of Atomic Radiation
WHGMS Wet high gradient magnetic separation
WRL Waste rock landform
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Abbreviation Description
2σ Two sigma means ‘two standard deviations’. The ‘standard deviation’ is a measure of the variability of a set of results. In a normally distributed population, 95% of the results lie within about 2 standard deviations of the mean value.
Bq Becquerel, a unit of radioactivity
Bqm-3 Becquerels per cubic metre. A volumetric measure of radioactivity.
CO2eq Carbon dioxide equivalent
GL/year Gigalitres per year. One gigalitre is equal to 1,000,000,000 litres, or one million cubic metres.
ha Hectare, equivalent to 10,000 m2
km Kilometre
m Metre
mg Milligram. One thousandth of a gram.
mg/L Milligram per litre, approximately equivalent to one part per million
µs Microsecond
µm Micro or micrometre, a unit of length equal to one millionth part of a metre
mSv Millisievert, a measure of radiation dose to tissue
Mtpa Million tonnes per annum. Same as ‘million tonnes per year’.
MW Megawatt (1,000,000 watts)
PM10 Particulate matter having an equivalent aerodynamic diameter equal to or less than 10 micrometres (a micrometre is one millionth of a metre)
ppb parts per billion
ppm parts per million
tpa Tonnes per annum
μg/m3 Micrograms per cubic metre
μS/cm Microsiemens per centimetre, a measure of electrical conductivity of water due to contained salts
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16 REFERENCES
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Appendix A: Environmental Scoping Guideline (July 2013)
Appendix B: Browns Range Hydrogeology
Appendix C: Geochemical Characterisation of Browns Range Waste Rock
Appendix D: Preliminary Tailings Design Report
Appendix E: Geotechnical testing of Browns Range tailings
Appendix F1: Baseline Soils Characterisation
Appendix F2: Analogue slopes soil and vegetation assessment
Appendix G: Preliminary Geochemical Characterisation of Tailings
Appendix H: Water Supply Investigations
Appendix I: Surface Hydrology
Appendix J: Vegetation and Flora
Appendix K: Terrestrial Vertebrate Fauna
Appendix L1: Short Range Endemic Invertebrates – baseline survey
Appendix L2: Targeted Mygalomorph Spider Survey
Appendix L3: Short Range Endemic Invertebrates - assessment
Appendix M: Subterranean Fauna
Appendix N1: Air Quality
Appendix N2: Air Quality – Modelling data inputs
Appendix O: Noise
Appendix P1: Conceptual Mine Closure Plan
Appendix P2: Pit lake assessment
Appendix P3: Pit lake ecotoxicity assessment
Appendix P4: Pit lake impacts on fauna
Appendix P5: Runoff sediment study
Appendix P6: TSF cover modelling
Appendix Q1: Radiological Assessment of Tailings
Appendix Q2: Radiation technical report
Appendix R: Environmental Offsets Reporting Form
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