CDO Cells 1/2 Stage 8 Embankment Raise

CDO Cells 1/2 Stage 8 Embankment Raise


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Contents

1.0 Premise Details ................................................................................................................................. 1

1.1 Occupier of Premises .................................................................................................................... 1

1.2 Location of Premises ..................................................................................................................... 1

1.3 Prescribed Premises Category ..................................................................................................... 4

1.5 History ........................................................................................................................................... 4

1.6 Current Operations ........................................................................................................................ 5

2.0 DESCRIPTION OF ACTIVITY .......................................................................................................... 6

2.1 Outline of Proposed Activity .......................................................................................................... 6

2.2 Construction and Operation of Cell 1/2 Stage 8 Embankment ..................................................... 6

2.4 Nature of Discharges .................................................................................................................... 7

2.4.1 Dust ........................................................................................................................................ 7

2.4.2 Tailings ................................................................................................................................... 8

2.4.3 Seepage ................................................................................................................................. 9

3.0 Existing Environment ...................................................................................................................... 11

3.1 Regional Setting .......................................................................................................................... 11

3.2 Geology ....................................................................................................................................... 11

3.3 Land Systems and Soils.............................................................................................................. 14

3.4 Flora and Fauna .......................................................................................................................... 14

3.4.1 Flora ..................................................................................................................................... 14

3.4.2 Fauna ................................................................................................................................... 15

3.4.3 Malleefowl ............................................................................................................................ 15

3.5 Hydrology .................................................................................................................................... 15

3.5.1 Surface Water ...................................................................................................................... 15

3.5.2 Groundwater ........................................................................................................................ 15

3.5.2 Ferrolysis .............................................................................................................................. 19

3.6 Climate ........................................................................................................................................ 19

4.0 Sensitive Receptors ........................................................................................................................ 20

4.1 Threatened Ecological Communities and Priority Species ......................................................... 20

4.2 Groundwater ............................................................................................................................... 20

4.3 Lake Rebecca ............................................................................................................................. 20

4.4 Stygofauna .................................................................................................................................. 20

5.0 Assessment of Environmental Risks from Emissions ..................................................................... 21

5.1 Risk Identification ........................................................................................................................ 21

5.2 Risk Assessment ......................................................................................................................... 21

5.3 Discussion of Key Risks .............................................................................................................. 27

5.3.1 Dust ...................................................................................................................................... 27


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5.3.2 Damage to vegetation through direct contact with hypersaline water or tailings from pipeline leaks, over topping or dam break .................................................................................................. 27

5.3.3 Damage to vegetation through rise in groundwater levels ................................................... 30

5.3.4 Contaminate groundwater through seepage of tailings liquor ............................................. 32

5.3.5 Fauna death through tailings exposure or entrapment ........................................................ 34

5.3.6 Damage to Lake Rebecca.................................................................................................... 34

6.0 OTHER APPROVALS ..................................................................................................................... 34

6.1 Part IV Environmental Protection Act 1986, Environmental Impact Assessment ....................... 34

6.2 Other Decision-Making Authorities ............................................................................................. 34

6.2.1 Department of Mines and Petroleum ................................................................................... 34

Department of Water ..................................................................................................................... 35

Department of Planning, Lands and Heritage ............................................................................... 35

7.0 References ...................................................................................................................................... 36

Figures

Figure 1: Location of the Carosue Dam Project ...................................................................................... 2

Figure 2: Location of the Cell 1/2 Tailings Storage Facility in relation to other infrastructure at Carosue Dam and Cadastral boundaries .............................................................................................................. 3

Figure 3: Water Balance for the Tailings Storage Facility and Associated Processing Infrastructure .. 10

Figure 4: Contours of the Carosue Dam Area. ..................................................................................... 12

Figure 5: Geology of the Carosue Dam Area ........................................................................................ 13

Figure 6: Surface water catchment and flow directions ........................................................................ 17

Figure 7: Groundwater contours of Carosue Dam Area (Rockwater, 2000) ......................................... 18

Figure 8: Rainfall comparison for Carosue Dam and Kalgoorlie airport 2000 to 2017 (No or limited data 2000, 2005-2007) .......................................................................................................................... 19

Figure 9: Modelled outflow of tailings in a dry slump type embankment failure at Cell 3 (Knight Pièsold, 2016) ....................................................................................................................................... 29

Figure 10: Modelled outflow of tailings in a dry slump type embankment failure at Cell 1 (Golder, 2019). .................................................................................................................................................... 30

Figure 11: Carosue Dam TSF monitoring bores ................................................................................... 32

Figure 12: Groundwater levels in the existing TSF monitoring bores ................................................... 32

Figure 13: Total Dissolved Solids in the existing TSF monitoring bores .............................................. 33

Figure 14: pH in the existing TSF monitoring bores ............................................................................. 33

Tables

Table 1: Northern Star Contact Details ................................................................................................... 1

Table 2: Tenements, Local Government and Pastoral Lease Details .................................................... 1

Table 3: Prescribed Premises for Carosue Dam Operations .................................................................. 4

Table 4: Compaction, Layer and Moisture Content Specifications ......................................................... 6

Table 5: Carosue Dam tailings properties ............................................................................................... 8


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Table 6: Geology and Permeability of Subsurface materials underlying Cell 3 .................................... 11

Table 7: Assessment of risk and its management Cells 1 / 2 Stage 8 - construction and operation .... 23

Appendices

Appendix A – NSR Authorised Signatories- DWER

Appendix B – Proof of Occupier Status Transcript

Appendix C - Cells 1/2 Stage 8 Construction Drawings


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Glossary of Tailings Terminology

Beach: tailings surface between discharge point and supernatant pond.

Cut off trench: trench either open or in-filled with low permeability material designed to limit or stop seepage from passing.

Downstream: side of the embankment away from tailings, outside of the embankment.

Downstream Construction: construction of embankment so that material is placed on the outside wall of the embankment, uses more material than upstream construction, however the tailings deposition area increases with each lift. Downstream construction is considered more stable than upstream construction.

Decant tower: structure used to collect decant water, so it can be recycled to the processing plant.

Decant water: water on the surface of the tailing storage after the solids have settled, also known as supernatant water or free water.

Embankment: barrier built of rock or other materials (including tailings) to contain tailings material.

Free water: water liberated from the tailings as solids settle out, also known as supernatant water.

Freeboard: the vertical distance between the operating or predicted water level in the TSF and the minimum crest level of the embankment.

In-pit TSF: tailings storage facility located in a disused open pit void, tailings located below ground generally no embankments required.

Lift: vertical raising of embankment (either upstream or downstream) to provide additional storage capacity.

Paddock tailings: Tailing Storage Facility constructed above ground enclosed completely by embankments, often square or rectangular giving rise to name paddock.

Piezometer: device for measuring liquid pressure in a system, installed into the embankments of TSF behind Zone A to measure seepage through the embankment. The higher the water in the piezometer the higher the pressure.

Mt: Million tonnes.

Return water: water (supernatant and or underdrainage) pumped back to the processing plant for recycling.

Spigot: short length of pipe with clamp or other device for controlling the flow of tailings.

Submersible pump: a pump and its electric motor together in a protective housing which permits the unit to operate under water.

Settlement pins: metal pin inserted in concrete, used to accurately determine if the surrounding ground is moving.

Supernatant water/pond/liquid: water “floating” on the surface of the tailings, also known as decant water or free water.


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Tailings: slurry of ground rock, water and chemicals remaining after the desired minerals (e.g. Gold) have been removed from the ore, also refers to ground rock remaining when water removed.

Tailings Storage Facility: a structure constructed to settling and storage tailings solids with features that allow collection of process water.

Thickener: A Thickener is a piece of infrastructure responsible for a process where a slurry or solid-liquid mixture is separated to a dense slurry containing most of the solids and an overflow of essentially clear water (or liquor in leaching processes).

TSF: common abbreviation for Tailings Storage Facility.

Upstream: side of the embankment in contact with tailings, inside of the embankment.

Upstream Construction: construction of embankment so that material is placed on the inside wall of the embankment, usually partially overlying the tailings surface, uses less material than downstream construction, however tailings deposition area becomes smaller with each lift.

Underdrainage: drainage system located beneath the tailings, usually at ground level or in base of a pit to collect and drain seepage from the tailings.


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Figure 1: Location of the Carosue Dam Project


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Figure 2: Location of the Cell 1/2 Tailings Storage Facility in relation to other infrastructure at

Carosue Dam and Cadastral boundaries


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In February 2004, both cells were raised (Stage 4) to an embankment level of RL369.0 m;

In August 2005, both cells were nominally full (Stage 4) when the operation was put on care and maintenance;

A recommissioning audit was carried out in 2008 by Knight-Pièsold prior to both cells being raised in December 2009 (Stage 5) to an embankment level of RL371.9m;

In April 2012, Cell 1 was raised to RL375.5m (Stage 6);

Cell 2 (Stage 6) embankment raise to RL375.5m was undertaken in November 2013;

Between July and December 2014, Cell 3 Stage 1 was constructed to provide a 1270m x 540m (69ha) catchment basin. Cell 3 was constructed as downstream construction with external wall to 375.5mRL, internal construction then completed under Works Approval W5241/2013/1 to 371.5mRL (see Cell 3 Stage 1 construction report for details);

Between July 2017 and October 2017, Cell 3 Stage 2 embankment was constructed to an elevation of RL375.5 m with a Zone A raise of approximately 4.0 m. Completion of Cell 3 Stage 2 provided a cumulative storage of 10.0 Mt. Cell 3 Stage 2 embankment was constructed with an upstream slope of 1V:2.0H, a downstream slope of 1V:2.75H and a crest width of 6 m, using tailings sourced from the Cell 3 Stage 1 beach;

In July to October 2019 Cell 1/2 Stage 7 was raised by upstream construction;

In July 2019, the Carosue Dam Paste Plant was commissioned and deposition into Cell 1/2 continued at a reduced rate of 2.2 Mtpa;

The Carosue Dam Processing Plant upgrade to 4.0MT per annum was commissioned on the 1st of November 2020; and

Construction works are currently underway on the TSF Cell 3 Stage 3 embankment raise.

1.6 Current Operations

Northern Star currently operate the Carosue Dam Processing Plant under L7465/1999/8 with a throughput of up to 4MT per annum. Tailings are currently discharged to TSF Cell 1/2 Stage 7, whilst an embankment raise of TSF Cell 3 Stage 3 is being completed. The TSF Cell 3 Stage 3 raise will provide Northern Star with approximately 8 months of capacity on completion (currently scheduled for mid to late June 2021), providing discharge capacity for Carosue Dam until the 1st of February 2022. Construction of the TSF Cell 1 / 2 Stage 8 lift will take approximately 3 months to complete from approval date.

Northern star are mindful of the current assessment timeframes required for Works Approvals in the resources sector. Therefore, Northern Star has expedited its own processes to allow as much time as possible for DWER to assess the application, and request that the current TSF Cell 1 / 2 Stage 8 Works Approval be given priority over the remainder of the Northern Star Works Approvals applications currently in the system. Based on current assessments of timing, Northern Star would need to gain approval to start construction no later than the 25th of October 2021 to avoid potential processing plant shut-down.


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Approved General Fill Zone D

General Fill 500 95% of Standard Max Dry Density

Optimum +3%

Optimum -3%

Zone E Erosion Protection 300 Uniform Density Free From Cavities

Not Required

Decant Surrounds Zone G

Rock Fill N/A Uniform Density Free From Cavities

Not Required

Embankment Foundation (Scarify and Re-Compact)

In-Situ Fill 300 98% of Standard Max Dry Density

Optimum +3%

Optimum -3%

The combined Cells 1 and Cell 2 pond will migrate towards the existing western wall of Cell 1 and Cell 2. The existing Stage 7 decant tower in the centre of the two cells on the western divider wall will be raised and continue to operate for the rest of the facility life. The decant tower comprises the following components:

An access causeway constructed of Zone D material; A decant tower, consisting of an 1,800 mm diameter slotted concrete pipe surrounded by

clean waste rock (Zone G); A submersible pump and pipework (designed by others); and A hoist and pulley to raise and lower the pump (designed by others).

All pipelines will be double skinned PE100 and will be constructed and installed in accordance with AS4130 and AS413, and the Plastics Industry Pipe Association of Australia Limited (PIPA) Guideline POP003. Additional monitoring infrastructure (settlement pins) will be constructed to ensure safe operation of the containment facility. It is noted that the existing Stage 6 and 7 Piezometers are considered to be sufficient for the monitoring requirements of the containment facility.

Operation

Once completed, tailings will be deposited from the northern, eastern and southern perimeter embankments maintaining the pond centrally around the decant tower in the middle of the western embankment. Processing personnel will manually control the formation of the beach and location of supernatant pond via operation of spigot clamps. A submersible pump will be located in the decant and underdrainage towers to continually recover supernatant water and return it back to the processing plant.

Cell 1/2 Stage 8 will have a capacity of 2.6Mt of dry tailings, and will be operated as a standalone facility. A minimum embankment freeboard of 300mm will be maintained at all times within these Cells. The facility will be inspected at minimum every 12 hours including:

(i) Tailings delivery lines;

(ii) Return water lines;

(iii) Tailings Deposition;

(iv) Pond on surface of the TSF;

(v) Internal embankment freeboard; and

(vi) The external walls of the TSF.

Survey pins and/or prisms, Piezometers and Monitoring Bores will be monitored monthly.

2.4 Nature of Discharges

2.4.1 Dust

Potential sources of dust generated under the proposed works are via vehicle movements along access roads and other hardstand areas during construction of the embankment walls. Dust has the potential to create local and offsite pollution, through visual impact and coating (choking) of vegetation. Minimal dust is expected during construction of Cells 1/2 Stage 8 based on previous dust emissions observed during past lifts. Saline water for dust suppression will be administered as


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Further geochemical characterisation was undertaken in 2014 (Knight Piesold, 2014) to test the acid forming potential of tailings with a higher composition of sulphidic Red October ore (17%) within the process blend. A sample of tailings from was supplied to NATA accredited Genalysis Laboratory for analysis. The following conclusions were drawn from analysis:

Acid forming potential of the tailings sample was determined based on the acid base accounting and the net acid generation test. The tailings sample was classified as Non Acid Forming.

Tailings have a moderate number of elemental enrichments, with arsenic, chloride and sulphur found to be highly enriched with bismuth, molybdenum and selenium also found to be significantly enriched (Knight Pièsold, 2014).

2.4.3 Seepage

An investigation into dewatering of Whirling Dervish pit conducted by Pennington Scott (2012a), found that although there appears to be significant groundwater mounding around the TSF, the actual volumes of TSF seepage may be very low due to the low permeability of the clayey upper saprolite horizon. The TSF seepage rate has been steadily declining since the start of mining as the ground water mound has developed. During the initial wetting phase, the TSF would have been losing up to 8L/s through its base, which has declined to its current rate of around 3.5L/s.

Hydraulic modelling, conducted by Pennington Scott (2012a) indicates that the majority of the dewatering flows into the Whirling Dervish pit can be explained by inflow from the Saprolite aquifer. Recirculation of TSF seepage accounts for about 10% of the dewatering from Whirling Dervish.

Monitoring of embankment piezometers and surrounding bores has shown no indication of embankment seepage during the operation of any past and present lifts on Cells 1 and 2. Three piezometers (PZ04, PZ05 and PZ06) on Cell 2 have sporadically recorded evidence of lateral movement of water within the eastern embankment wall, however the volume of seepage is extremely minor and is showing no external surface expression on the outer embankment of the cell.

Figure 3 provides a water balance for the Tailings Storage facility and associated Processing infrastructure. Approximately 25% of all water sent to the Tailings Storage facility is returned to the Process Plant for reuse through underdrainage and decant return pumps. The Carosue Dam Thickener also directly returns approximately 150,000kl per month to the processing circuit which would otherwise report directly to the TSF. No significant changes are proposed to the overall water circuit as part of the TSF Cell 1/2 Stage 8 lift.


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Figure 3: Water Balance for the Tailings Storage Facility and Associated Processing Infrastructure


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Figure 4: Contours of the Carosue Dam Area.


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Figure 5: Geology of the Carosue Dam Area


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3.3 Land Systems and Soils

The Cell 1 / 2 Tailings Storage Facility is located within the Deadman (Dea) and Morarity (Mor) land system of Pringle et al, 1994.

The Deadman land system is characterised by level to gently undulating plains of deep red calcareous earths and red loams over calcrete. These soils are often covered by mixed or singular pebble mantles of quartz, ferruginous gravel and occasionally calcrete. Pebbles are occasionally abundant on gentle elevations, forming a stony surface. Brown loamy soils over calcrete with ironstone gravel are common on drainage flats and level to gently sloping alluvial plains of the Deadman land system. Occasional variations of these soils include brown loamy clays over calcrete and shallow (less than 60 centimetres) calcareous red earths with calcrete rubble. Greenstones are common and occur on low rises. Vegetation consists of Casuarina-Acacia shrublands/woodlands. This land system is generally not susceptible to soil erosion.

The Morarity land system in the Cell 1/2 area consists of alluvial plain, level to very gently inclined plains with sparse mantles of quartz and ironstone pebbles, with deep red clay soils characterised by scattered shrub land of halophytic shrubs with scattered Eucalypt or Casuarina Cristata over story. And Drainage Zones, unchannelled central drainage tracts to 400m wide, with shallow duplex soils, characterised by scattered low chenopod shrublands, often dominated by Atriplex spp. and locally with Eremophila salubris over story. This land system is moderately susceptible to soil erosion if vegetation cover is removed and soil surface disturbed.

No new disturbance is proposed through the Cell 1 /2 Stage 8 Project, therefore no impacts are expected to occur to land systems or soils.

3.4 Flora and Fauna

3.4.1 Flora

The region lies within the Eremaean botanical province mainly in the Austin botanical district with the eastern edge approaching the Helms botanical district (Beard, 1990). Lake Ballard/Lake Rebecca forms a major vegetation divide with characteristic Acacia aneura (mulga) low woodlands associated with red loams over siliceous hard pan to the north and low woodlands of mixed mulga and Casuarina pauper (black oak) and Eucalyptus sp. on alkaline and calcareous soils to the south. Spinifex hummock grassland with eucalypt overstory on sand plain is common. Halophytic vegetation occurs throughout the region on paleo-drainage systems, breakaways and on some stony and alluvial plains. Highly saline soils support Atriplex (saltbush), Maireana (bluebush) and Tecticornia (samphire) shrublands, while less saline soils support mulga with saltbush or bluebush understoreys (Pringle et al., 1994).

A total of 69 vascular plant taxa from 31 genera and 19 families were recorded within the Karari pit extension area. The majority of taxa was recorded within the Fabaceae (16 taxa), Scrophulariaceae (11 taxa) and Chenopodiaceae (10 taxa) families. No introduced or threatened flora taxa were found. Two potential range extensions, Eremophila drummondii(?) and Maireana villosa(?) were found at a number of sites, however, more reproductive material is needed to confirm these species. No suitable habitat was observed for Thryptomene eremaea (Priority 2).

Nine vegetation communities were defined, based on the constituent Eucalyptus sp. and Mulga species. The vegetation communities defined are at a finer level than as mapped by Beard in 1975. However, the communities relate to his associations (Mattiske 2010).

No new disturbance is proposed through the Cell 1 /2 Stage 8 Project.


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3.4.2 Fauna

An assessment of the vertebrate fauna of the Carosue Dam and Safari Bore area was conducted for Son of Gwalia in June 2002. The assessment comprised a field survey and desktop review. The study concluded that vertebrate fauna is likely to be typical of a broad area of the Eastern Goldfields, that is, moderately rich in reptiles and birds (Metcalf and Bamford, 2002), however, less common types of habitat are likely to increase biodiversity at a local scale. These include:

Breakaways, rock outcrops and rocky hills may harbour isolated populations of sedentary species.

Drainage lines often provide dense vegetation utilised by a variety of bird species and may act as refuge areas during dry periods.

After heavy rainfall events, salt lakes may be used as breeding sites for a variety of migratory and non-migratory wader species, and other waterbird species.

No new disturbance is proposed through the Cell 1 /2 Stage 8 Project.

3.4.3 Malleefowl

Malleefowl are regularly sighted at Carosue Dam. Mound preparation begins between May and June. Egg laying usually begins in September and can continue until mid to late summer. Incubation periods vary, but is about 60 days. Chicks typically begin hatching and emerging from mounds in November, hatching may continue until March in some seasons, most chicks usually emerge from mounds before January (from National Malleefowl Recovery Team web site).

Northern Star anticipates no impacts to the local Malleefowl population in relation to the TSF Cell 1 / 2 Stage 8 raise as no new clearing is required and TSF operations have been conducted for >10 years with no negative impacts observed.

3.5 Hydrology

The terrain of the north-eastern Goldfields is generally flat to gently undulating, relatively low lying and covered mainly by thin superficial soils and occasionally by low hills of bedrock. It is traversed in a east-south-easterly direction by broad saline paleodrainages of which the closest to the Carosue Dam Project area is Lake Rebecca (Figure 1). The lake receives surface drainage from the surrounding country and very occasionally fills.

3.5.1 Surface Water

Surface water (as sheet flow) flows east from breakaways and hills of underlying bedrock to the west to a broad drainage line east of Whirling Dervish, then north toward Lake Rebecca (Carrick Consulting, 2015). Surface water flow in the area has been significantly modified by existing mining infrastructure. The newly constructed sheet flow diversion drain has been designed to capture ~90% of water flows moving in an easterly direction towards the mining operations (Figure 6).

There are no permanent or semi-permanent surface water bodies within the Carosue Dam Project area.

3.5.2 Groundwater

Groundwater occurs throughout the region within sparse fractures in basement rocks, within the weathering profile, and in alluvial sediments. Groundwater recharge occurs from major, but infrequent, rainfall events, mainly on drainage divides, and locally at site specific intake areas such as drainage lines or sand plains and dune fields. Groundwater is in hydraulic continuity and flows from drainage divides towards paleo-drainages and then south-easterly toward the Nullarbor Plain. Groundwater beneath catchment divides occurs as lenses of less than 5000 mg/L TDS which are


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superimposed on a regional field of saline groundwater with linear bodies of hypersaline groundwater along paleo-drainages, and local brine pools associated with salt lakes (Allen, 1994).

Two groundwater bores drilled in 1999 by Rockwater, as part of the initial groundwater study and search for suitable groundwater sources, are located upstream of the proposed TSF. CDHY2 (1.8km from the existing TSF; Figure 11) had a salinity of 6,930mg/L TDS and SWL 32.2m below surface, the hole is located in a creek line and may intersect a perched low salinity aquifer. CDHY18 drilled 1.5km to the east of the existing TSF did not intersect water (drilled to 60m). CDHY11 drilled downstream of the existing TSF had a salinity of 120,000mg/L with a standing water level 22.46m below ground level (prior to construction and operation of the existing TSF).

Rockwater (2000) described the pre mining groundwater flows in the Carosue Dam Area. Water levels generally fall from the elevated areas such as Relief Hill area (east of the mine) and the granite batholith (west of the mine) from levels at 350 and 360mAHD respectively (Figure 7) to 336mAHD in the Whirling Dervish pit area. From here groundwater flows northwards in the direction of the Lake Tana Palaeochannel towards Lake Rebecca.

Productive aquifers in the Carsoue Dam area occur within the bedrock and locally in the alluvium. Shear zones within the volcaniclastic strata constitute the main bedrock aquifers, these are commonly associated with ore bodies and of limited extent. Permeability is enhanced in the zone of weathered rock between the saprolite and fresh rock, giving rise to a sub-horizontal aquifer zone 20 to 50m thick. This aquifer lies about 45m below the ground surface and is overlain by low–permeability saprolite that constitutes a hydraulic confining layer (Knight Piésold, 1999).

Groundwater in the TSF area has been modified by the construction and operation of the existing TSF as well as dewatering and mining of the Whirling Dervish open pit. Groundwater mounding is evident in the TSF area with water levels raising slightly in the north and west. In contrast, dewatering at Whirling Dervish has created a groundwater sink with water levels in the South east corner (MB1D) falling 26m. Water levels around the existing TSF vary depending on which cell is in operation. Standing water level is highest on the north-eastern margin of the facility at MB6s (7.57mBGL in August 2016). Saracen anticipates no pronounced change in standing water level due to works proposed in this application.

Abstraction of groundwater to meet the demand for drinking water is covered by two Department of Water (DoW) groundwater licences. Pumping of water at SB02 is permitted under the Carosue Dam Palaeochannel GWL103538/5. SB02 lies within the Southern Borefield which includes nine production bores and accompanying monitoring bores. Historically, groundwater sourced from the Southern Borefield is acidic and hypersaline due to its proximity to Lake Rebecca. Water quality at SB02 is markedly better as it’s perched higher in the aquifer in contrast to the other bores. To satisfy the additional demand for RO feed water Northern Star will operate SB03 in conjunction with SB02 to ensure a sustainable supply. Groundwater abstraction is assessed annually with trends reported to the DoW in accordance with licence requirements.


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Figure 6: Surface water catchment and flow directions


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3.5.2 Ferrolysis

Dewatering and abstraction activities at several pits in the Carosue Dam district has been associated with strong acidification of groundwater, with the pH dropping from neutral to as low as 2 including in the Southern Borefield, Twin Peaks dewatering bores, Safari Haul Road bores and TSF. Where it occurs, high acidity has been observed in production and monitoring water bores, but not in any pit voids (Pennington Scott, 2012b).

The process causing the highly acidic groundwater is known as ferrolysis, which is a common phenomenon in Western Australia’s iron rich goldfields region. Ferrolysis occurs wherever oxygenated groundwater mixes with reduced iron rich groundwater, and commonly occurs naturally beneath the margins of salt lakes (Pennington Scott, 2012b).

Anoxic groundwater conditions in the deeply weathered terrain are conducive to soluble iron occurring in the Fe2+ redox state. The reduced Fe2+ ions, however, rapidly oxidise when mixed with oxidised infiltrating water such as rainfall recharge or migration of shallow fresh water lenses into a borefield area. The ferrolysis reaction is a particularly significant phenomena in the goldfields region because it can produce strongly acidic groundwater conditions, where the pH may be as low as 2 (Pennington Scott, 2012b).

Fe2+ (aq) + 2H2O FeO(OH) (s)+ 3H+(aq) + e- pK=13.53

During a previous review (Knight Piesold, 2004) the lowering of the groundwater pH was attributed to ferrolysis-type reactions between the regolith and the groundwater mound which has developed beneath the facility.

3.6 Climate

The Goldfields region is arid to semi-arid with average annual rainfall decreasing from about 250mm (Kalgoorlie) in the south-west to 200mm in the north-east (Laverton). Rainfall varies widely between years and droughts are common. Remnants of tropical cyclones occasionally bring heavy summer rain. The area is transitional between summer and winter dominated rainfall and desert: non-seasonal bioclimatic (Beard, 1990).

Since the commencement of rainfall recording in 2001 the total annual rainfall recorded at Carosue Dam is average or significantly below (2002, 2005, 2006, 2007) that recorded at Kalgoorlie-Boulder airport.

Rainfall for Carosue Dam and Kalgoorlie-Boulder airport is shown in Figure 8.

Figure 8: Rainfall comparison for Carosue Dam and Kalgoorlie airport 2000 to 2017 (No or limited

data 2000, 2005-2007)


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4.0 Sensitive Receptors

4.1 Threatened Ecological Communities and Priority Species

The Carosue Dam area lies in the south-eastern corner of the Murchison 1 (MUR1 – East Murchison) IBRA sub-region. There are no identified threatened ecological communities (TECs) on Saracen (now NSR) tenements or in the entire MUR1 biogeographic subregion (Cowan, 2001).

There are no listed priority ecological communities (PECs) in the area (Holm, 2012).

A Priority 3 Species Eremophila arachnoides is known to exist in the local area, with the closest individuals present, some 500m to the north west of the facility. No impacts are expected to populations of this species through the construction or operation of the facility.

4.2 Groundwater

Groundwater is considered a sensitive receptor for the TSF, a hypersaline, static water table existed at about 20m below ground level prior to the construction of the existing TSF. The main use for hypersaline groundwater is mining. Northern Star are currently dewatering the Whirling Dervish open pit 500m to the south–east of the TSF, this dewatering has created a ground water sink which draws down water levels in to the south east of the existing TSF.

The nearest stock watering point is Relief Hill Well (not in use) located 5.5km to the east of the TSF. The use of the existing TSF and dewatering of Whirling Dervish have not affected Relief Hill Well.

4.3 Lake Rebecca

Lake Rebecca is a large ephemeral salt lake covering an area of approximately 270km2 and is part of the

Yindarlgooda Palaeoriver system. The lake has been divided into two main sections by the Safari haul road causeway. There is limited movement of water between the two sections during minor flooding and essentially they would act as two lakes until a major flood occurred.

Lake Rebecca lies approximately 8km north-east of the TSF and surface and groundwater water flows toward Lake Rebecca (Figure 6 & Figure 7). The TSF and associated infrastructure (i.e. pipelines, roads) have already impacted natural surface water flows in the area, with the Whirling Dervish Underground mine acting as a sink between the TSF and the Lake.

Impacts from surface water and/or groundwater movement to Lake Rebecca are therefore not expected from the expansion of the TSF expansion.

4.4 Stygofauna

Stygofauna are common in the Yilgarn region within numerous isolated calcretes and there are numerous records from both the Carey and Raeside palaeo-drainages where groundwater calcretes are prominent (Bill Humphreys Western Australian Museum pers. comm. 4/3/2003 to Biota). No calcrete is present below standing groundwater table depths near the TSF; furthermore groundwater is hypersaline (up to 250,000 mg/L TDS; Saracen 2008-2009 environmental report), and therefore stygofauna are unlikely to be present or affected by the proposed works.


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5.3 Discussion of Key Risks

5.3.1 Dust

Potential dust emissions associated with the construction of TSF Cell 1/2 stage 8 will be most likely to occur during:

Preparation of the existing Cell 1/2 embankment crest by removing the wearing course, scarifying, wetting and re-compacting the Zone A fill;

Raising the TSF embankment Zone A to the design levels and grades; and Placing Zone E erosion protection material on the eastern margin.

To minimise the potential of dust emitting beyond the TSF perimeter, saline water will be administered via watercart. Northern Star recognises that Saline water used for dust suppression has the potential to adversely affect vegetation if plants are exposed to contained salt through over-spraying or runoff into vegetated areas.

The following management practices will be implemented to minimise the impact on surrounding vegetation:

Dusting is likely to occur during the handling of embankment materials, vehicular movement and the profiling of embankment walls. Material stockpiles will watered down during the rehandle phase to ensure that dusting is adequately managed. If local wind speeds are conducive to elevated dusting, construction works will be terminated until conditions improve.

Windrows will be constructed along roads and hardstand areas to prevent saline water from draining into the surrounding environment.

Watercarts will administer water via a roof mounted cannon to the Cell 1/2 embankment during the compaction phase. Wind direction and speed will be observed daily by the contract shift supervisor. If the prevailing wind direction poses a risk of overspray emitting beyond the facility perimeter watercart operations will be terminated until that risk abates. Wetting down of roads/access tracks will be undertaken with dribble bars, which is a Northern Star requirement for all watercarts working outside mining areas (i.e. Haul roads).

Water truck operators are instructed to avoid over spraying/watering and report any damaged bunding or saline runoff containment infrastructure.

5.3.2 Damage to vegetation through direct contact with hypersaline water or tailings from pipeline leaks, over topping or dam break

All pipelines will be double skinned PE100 and constructed and installed to Australian Standards AS4130 and AS413 and Plastics Industry Pipe Association of Australia Limited (PIPA) Guideline POP003. Only qualified poly welders will be employed to construct the pipelines and welding certificates will be retained on site to be presented upon request. Bunding has been constructed to contain spills and leaks for the tailings pipeline in accordance with Licence condition 1.2.1. All tailings and dewatering/process water pipelines are connected to Citect Process Monitoring System which monitors water levels and pressure in tanks, dams and pipelines. The pipelines and TSF will be inspected twice per 12 hour shift as a part of daily processing plant operations. Inspections undertaken at the frequency stated above either meet or exceed DWER licence condition 1.2.6. All these management actions are aimed at preventing spillage of hypersaline water and/or tailings from the pipeline.

In the event of a hypersaline water or tailings spill, telemetry will automatically shut off pumps and isolation valves will be closed by site personnel. Bunding will assist in containing the spill. If bunding fails to contain the spill as a result of a major pipeline break and/or the failure of the above management actions, the tailings flow or return water flow would be stopped. Earthmoving machinery will be mobilised to contain the spill. Environmental personnel will assess the extent of the contamination and, if necessary, contaminants removed using earthmoving equipment and remediation of the area completed (ripping, seeding) if required.

Any spills will be reported to DWER within 24 hours as per Operating Licence condition 4.3.1. A detailed written report describing remedial actions and any other information requested by DWER will


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be prepared and forwarded to DWER within 7 days of the incident. Monitoring of the spill site would continue quarterly for a minimum of twelve months, and all monitoring results will be reported in the Annual Environmental Report.

TSF Cells 1/2 Stage 8 has been designed with a minimum top of embankment freeboard of 300mm to prevent over topping by tailings or incident rainfall. The level of tailings will be monitored visually on a daily basis. Cells 1/2 Stage 8 will be used in conjunction with the existing Cell 3 if emergency events are encountered.

The TSF has been designed in accordance with DMIRS and ANCOLD guidelines to minimise the risk of dam break (wall failure). Construction will be supervised by a suitably qualified engineer to ensure it is constructed according to design. Operational, inspection and monitoring conditions are in place to minimise risk of dam break.

Knight Piésold conducted an initial dam break study as part of the design of Cell 3. Modelling was conducted on the final embankment height of 22m when the TSF will be at its maximum storage volume to determine worst case scenario. The assessment was reviewed to specifically model Stage 3 capacity (Knight-Pièsold, 2016). Modelling indicates the following:

A dam breach could occur on either the northern or southern embankment of Cell 3;

A tailings storage volume at Stage 2 capacity (worst case scenario) is estimated at 7.7Mm3 at an embankment height of 15.5m;

An estimated outflow volume as a result of embankment failure of 2.56Mm3 based on the Rico 2007 regression;

The localised detailed topography around the immediate vicinity of the TSF (Cell 3) was assessed for the case of a dry condition embankment slump type failure. An outflow volume of approximately 2.56Mm3 with a failure breach slope 1V:180H is shown below in (Figure 9).

For the breach occurring on the northern embankment, the predicted impacted area is 251ha and the run out distance is approximately 3km. For a breach on the southern embankment the area of impact is approximately 65ha and the run out distance is 1km.

Embankment failure modelling indicates that the ANCOLD Consequence Category remains unchanged as a ‘High C’ due to the risk of at least one life being lost in the event of a failure.


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Figure 9: Modelled outflow of tailings in a dry slump type embankment failure at Cell 3 (Knight Pièsold, 2016)

Golder Associates Pty Ltd conducted an updated dam break study as part of the design of Cell 1/2 Stage 7 in August 2019. Modelling was conducted on the final embankment height of 378mRL being filled to capacity to determine worst case scenario. A review was completed on the adequacy of the dam break safety bund which exists between the Whirling Dervish Pit (and operational underground mine) and TSF Cell 1 (as this is the only cell from which a dam break scenario could affect the underground mine). Modelling indicated the following:

A dam breach could occur from the Cell 1 area which could affect the underground mine in Whirling Dervish;

A tailings storage volume at Stage 7 capacity (worst case scenario) is estimated at 12.3Mm3.

An estimated outflow volume as a result of embankment failure of 2.6Mm3 has been assumed;

A dam break bund has been constructed between the Whirling Dervish Pit and the TSF to account for a dam break scenario;

The dam break safety bund has adequate Factors of Safety to withstand dynamic forces for sliding to a factor ~6;

The bund has been constructed to ensure there is 0.5m freeboard in the event an embankment event occurs.

To ensure that operation of Cell 1/2 Stage 8 is safe and meets best practise, monitoring of groundwater at existing downstream monitoring bores will continue at the prescribed licenced frequency. Existing piezometers will continue to be monitored monthly to assess embankment stability. New crest settlement survey pins will be installed prior to operation to track movement of the embankment during deposition. Modelling is currently in progress for impacts associated with the Stage 8 raise of Cells 1/2, which may result in the dam break bund being raised again. This will be submitted through an associated Mining Proposal and Closure Plan to DMIRS for assessment and approval.


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Figure 10: Modelled outflow of tailings in a dry slump type embankment failure at Cell 1 (Golder, 2019).

An Emergency Action Plan has been developed in the unlikely event that a dam break event occurs. The Plan is incorporated in the Tailings Storage Facility Operating Manual which will be revised in parallel with the construction of the Stage 8 lift of Cells 1 & 2.

5.3.3 Damage to vegetation through rise in groundwater levels

Pre-mining groundwater levels around the TSF area were about 20m below ground level (mBGL) prior to the construction of TSF Cell 1 and 2. Current groundwater standing water level ranges between 8.54mBGL (MB5D) and 23.11mBGL (MB8D) (Figure 11). Standing water level at both the shallow and deep allotments of MB5, MB6, and MB7 indicate groundwater mounding is in effect beneath the Cells 1 and 2 (Figure 12). With operation of Cell 3 (commenced January 2015), standing water level at these bores has gradually abated as the tailings material transitions into a drying phase. To date, monitoring bores on the western margin of Cell 3 (MB9, MB10 and MB11) remain dry indicating (apart from MB9D- 14.70mbgl) that hydraulic pressure associated with tailings deposition isn’t affecting groundwater.

The damage to vegetation is most likely to occur if groundwater level rises into the root zone. The landscape surrounding the TSF is described as alluvial plains with mixed halophyte low shrublands and generally scattered low shrublands of Acacia aneura and Acacia spp (Pringle et al., 1994). Mulga-dominated woodland is not regarded as a ground-water dependent ecosystem, it is shallow-rooted and will not be affected by rises in ground water to at least the DWER licence limit of 4m from the surface; Knight Pièsold estimates the root zone at a depth of 3mBGL.

Three vegetation monitoring transects were established in March 2009 (prior to the recommencement of tailings deposition) around the existing TSF (TSF East, West and North). Following construction of Cell 3 Stage 1 new monitoring sites were erected in August 2015 by Alexander Holm and Associates (Holm, 2016). Annual monitoring has shown little change in species diversity or abundance since monitoring began. The vegetation monitoring sites are monitored annually.

Groundwater levels around the TSF will be monitored on a quarterly basis as per existing DWER licence conditions. If groundwater levels in monitoring bores reach 6mBGL standing water level in the


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monitoring bores will be monitored monthly, and preparations will be made to implement a groundwater recovery system if groundwater reaches the 4mBGL DWER limit. Existing vegetation monitoring points around the TSF will continue to be monitored annually until the TSF is decommissioned and rehabilitated.


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Figure 11: Carosue Dam TSF monitoring bores

5.3.4 Contaminate groundwater through seepage of tailings liquor

Groundwater surrounding the TSF has recorded a TDS of between 40,000 and 170,000mg/L (Figure 13). The main use of this water is for mining purposes. The nearest stock watering bore is Relief Hill well located 5.5km to the east of the existing TSF.

Geochemical characterization undertaken by Aquaterra (2010b) and Knight Pièsold (2014) indicate the tailings material is relatively inert, with concentrations of most environmentally significant elements below ecological investigation levels. The bioavailability of the majority of elements is also low, and together with their low solids content, the quality of any water from the pit entering the surrounding aquifer is unlikely to be of any environmental concern. The Cyanide concentration in the tailings discharge is expected to be around 60-70mg/L volatising to 10mg/L in supernatant liquor, WAD-CN concentration in monitoring bores that surround the TSF are predominately <0.2mg/L, indicating seepage is not an issue.

Monitoring data for pH at bores that surround the TSF is shown in (Figure 14). pH ranges widely from acidic (MB6d, MB7d and MB8d) to near-neutral (MB1d, MB5s/d). Low pH in TSF monitoring bores is caused by a ferrolysis reaction (oxidization of Fe). This reaction is exacerbated when bores are not purged and acid builds up in the water column. The ferrolysis reaction is a particularly significant phenomena in the WA Goldfields region because it can produce strongly acidic groundwater conditions, where the pH can be as low as 2 (Pennington Scott, 2012b).

Figure 12: Groundwater levels in the existing TSF monitoring bores

*Bores MB9 (shallow), MB10 (shallow & deep) and MB11 (shallow & deep) constructed during Cell 3 Stage 1 have remained dry since deposition begun in January 2015.


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Figure 13: Total Dissolved Solids in the existing TSF monitoring bores

*Bores MB9 (shallow), MB10 (shallow & deep) and MB11 (shallow) constructed during Cell 3 Stage 1 have remained dry since deposition begun in January 2015.

Figure 14: pH in the existing TSF monitoring bores

*Bores MB9 (shallow), MB10 (shallow & deep) and MB11 (shallow & deep) constructed during Cell 3 Stage 1 have remained dry since deposition begun in January 2015.

Metals and WAD-CN concentration within groundwater has been monitored around the TSF since 2000. Historically WAD-CN has returned lab concentrations <0.2mg/L, well below DWER’s limit of 0.5mg/L.

Groundwater levels and chemistry will continue to be monitored quarterly to comply with DWER licence conditions. If monitoring indicates a decline in water quality or rise in SWL above 4mBGL, a groundwater recovery system will be designed and implemented.


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5.3.5 Fauna death through tailings exposure or entrapment

The death of fauna through exposure or entrapment in tailings has not been an issue at Carosue Dam to date, due to the salinity of process water and obstacles which prevent access to the tailings beach. The TSF will continue to be inspected for evidence of fauna exposure or entrapment; any animals sighted in the vicinity of the TSF will be discouraged or removed. Any fauna deaths related to the TSF will be reported to DWER; if fauna death becomes an issue, management measures to prevent fauna accessing the TSF (i.e. fencing) will be implemented.

5.3.6 Damage to Lake Rebecca

Lake Rebecca lies approximately 8km to the north-east of the TSF and surface water flows toward Lake Rebecca. The TSF and associated infrastructure (i.e. waste dump, roads and pipelines) have already impacted surface water flow in the area. Further impacts to surface water and hence Lake Rebecca are not excepted from the internal raise of the TSF.

Seepage from the TSF is not expected to reach Lake Rebecca due to the isotropic nature of aquifers in the Carosue Dam area. Seepage is more likely to extend north–west /south-east direction parallel to Lake Rebecca than across strike toward Lake Rebecca (Aquaterra, 2010b) and is heavily influenced by the Whirling Dervish pit creating a drawdown effect.

6.0 OTHER APPROVALS

6.1 Part IV Environmental Protection Act 1986, Environmental Impact Assessment

The TSF Embankment Raise does not trigger any of the nine criteria for referral to the EPA under the memorandum of Understanding between DMIRS and the EPA.

6.2 Other Decision-Making Authorities

6.2.1 Department of Mines and Petroleum

Resources Safety Division

A Project Management Plan for the entire Carosue Dam operations has been approved by the Department of Mines, Industry Regulation and Safety.

The embankment raise on Cells 1 / 2 Stage 8 has been designed in accordance with the requirements of the Dept. of Minerals and Energy “Guidelines on the Safe Design and Operating Standards for Tailings Storage”. In accordance with these guidelines the facility is classified as Category 1 storage with a ‘Significant’ hazard rating.

Environment Division

The embankment raise on Cells 1 / 2 Stage 8 of the TSF were approved by the DMIRS Environment Division on the 2nd of September 2013 through Mining Proposal RegID39084 and again more recently through RegID91990.

Native Vegetation Branch

A Clearing Permit (CPS8000/1) for clearing of up to 375Ha was granted on 3 May 2018 for clearing of the Carosue Dam Expansion Project. This Clearing Permit remains active. However, no clearing is required for this project.

Dangerous Goods

There will be no additional dangerous goods or hazardous substances generated by this proposal above and beyond what is already licensed at Carosue Dam.


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Department of Water

Northern Star currently holds groundwater licence: GWL157428(5), for dewatering of the Karari, Whirling Dervish, Luvironza, Twin Peaks and Monty’s open pits.

Department of Planning, Lands and Heritage

No clearing will be required as part of this proposal therefore the development does not trigger any of the requirements of the Aboriginal Heritage Act 1972.


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7.0 References

Allen, A. D. 1994. Hydrogeology. Pages 36-58 in K. M. W. Howes, editor. An inventory and condition survey of rangelands in the north-eastern Goldfields, Western Australia. Department of Agriculture, Perth Western Australia.

ALS Metallurgy. 2021. Carosue Dam (COF & Tails) Gold Ore Samples. Report for Saracen Gold Mines Pty Ltd, Perth, Western Australia.

Aquaterra. 2010. Luvironza In-Pit Tailings Disposal – Hydrogeological Assessment and Tailings Characterisation, prepared for Saracen Gold Mines Pty Ltd dated 6 September 2010.

Beard, J. S. 1975. Vegetation Survey of Western Australia. Nullarbor 1:1,000,000 Vegetation Series. University of Western Australia Press, Nedlands.

Beard, J. S. 1990. Plant Life of Western Australia. Kangaroo Press, Kenthurst, NSW Biologica 2010-08-10.

Biologica 2010; Level 1 Survey for a Proposed Pipeline from GCT to Carosue Dam and Power line form Black Swan to Carosue Dam. Unpublished report prepared for AngloGold Ashanti Australia and Saracen.

Carrick Consulting, 2015. Surface Water Management Assessment for the Carosue Dam Operations.

Memo prepared for Saracen Gold Mines Pty Ltd.

Cowan, M. 2001. Murchison 1 (MUR1 - East Murchison subregion). Pp 466-479 in N. L. McKenzie and J. E. May, (ed.) A biodiversity audit of Western Australia's 53 biogeographical subregions in 2002. Department of Conservation and Land Management, Perth, Western Australia.

Desmond, A., M. Cowan, and A. Chant; 2002. Murchison 2 (MUR2 - Western Murchison subregion (Graeme Campbell and Associates, 2007). Pp 480-496 in N. L. McKenzie, J. E. May, and S. McKenna(ed.). A Biodiversity Audit of Western Australia’s 53 Biogeographical Subregions in 2002. Department of Conservation and Land Management, Perth, Western Australia.

Golder Pty Ltd, 2019; Dam Break Assessment and Pit Protection Bund Analysis. Report for Saracen Gold Mines Pty Ltd, Perth, Western Australia.

Holm A. & Associates. 2006. Environmental Impact Assessment and Environmental Management Commitments and Procedures. Report for Saracen Gold Mines Pty Ltd, Perth, Western Australia.

Holm A. & Associates., 2012; Environmental Assessment: Tailings Storage Facility Expansion. Unpublished report prepared for Saracen Gold Mines. December 2012.

Knight Piésold, 1999. Tailings Storage Facility Notice of Intent – Carosue Dam Project – prepared for Oriole Resources Ltd November 1999 Ref 682/3.

Knight Piésold, 2004. Carsoue Dam gold Project – TSF Monitoring Bore Review November 2004, Memo report for Sons of Gwalia December 2004

Knight Piésold, 2012; various meeting, memos and documents regarding the expansion of Carosue Dam Tailings Storage facility, between David Morgan and Saracen Gold Mines.

Knight Piésold, 2013. Tailings Storage Facility permitting Design, Prepared for Saracen Gold Mines, March 2013.

Knight Piésold, 2014. Carosue Gold Project – Tailings Geochemical Characterisation, Prepared for Saracen Gold Mines, August 2014.

Knight Piésold, 2016. Tailings Storage Facility permitting Design, Prepared for Saracen Gold Mines, August 2016.

Metcalf, B. and Bamford, M. 2002. Vertebrate fauna of the proposed Carosue Dam – Safari haul road. Report for Sons of Gwalia Ltd, Perth, Western Australia.

NEPC (National Environment Protection Council) (1999). National Environment Protection (Assessment of Site Contamination) Measure – Schedule B(1) Guideline on Investigation Levels for EilSoil and Groundwater. http://www.ephc.gov.au/taxonomy/term/44 [accessed 4 September 2009]

Pennington Scott, 2012a. Whirling Dervish Underground, Dewatering Investigation, prepared for Saracen Minerals Holdings Ltd, 14 February 2012.

Pennington Scott, 2012b. Carosue Dam operations, Triennial Groundwater Monitoring Review 1 July 2009 to 30 June 2012. Prepared for Saracen Gold Mines, October 2012.


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Pringle, H.J.R., Van Vreeswyk, A.M.E., & Gilligan, S.A. 1994. An Inventory and Condition Survey of Rangelands in the North-eastern Goldfields, Western Australia, Report 87. Department of Agriculture, Perth, Western Australia.

Rockwater 2000. Groundwater supply and dewatering assessment - Completion Report for Drilling , Bore Construction and test-pumping. Prepared for Pacmin Mining Corporation, September 2000


APPENDIX A

NSR Authorised Signatories- DWER

30 March 2021

LETTER OF AUTHORITY IN REGARD TO APPROVAL APPLICATIONS

Please be advised the following people are authorised to sign each of the following on behalf of Northern Star Resources Ltd and its subsidiaries:

- Application for: Clearing Permit (Area Permit or Purpose Permit) / Amendment to aclearing permit / Surrender a clearing permit / Notificaton of change of land ownership

- Application form: Works Approval / Licence / Renewal / Amendment / Registration /Surrender works approval or licence / Transfer works approval or licence or Notify newoccupier of registered premises

- Application for a water licence under section 26D of the Rights in Water and IrrigationAct 1914

- Application for a 5C licence to take groundwater- Application for a section 11/17/21A permit to interfere with bed and banks- Annual Audit Compliance Report- Annual Environmental Report


APPENDIX B

Proof of Occupier Status Transcript

Australian Company

NORTHERN STAR (CAROSUE DAM) PTY LTDACN 116 649 122

10/06/2021 AEST 11:50:30 1

Extracted from ASIC's database at AEST 11:50:30 on 10/06/2021

Company Summary

Name: NORTHERN STAR (CAROSUE DAM) PTY LTD

ACN: 116 649 122

ABN: 14 116 649 122

Registration Date: 13/10/2005

Next Review Date: 13/10/2021

Former Name(s): SARACEN GOLD MINES PTY LIMITED

Status: Registered

Type: Australian Proprietary Company, Limited By Shares

Locality of Registered Office: SUBIACO WA 6008

Regulator: Australian Securities & Investments Commission

Further information relating to this organisation may be purchased from ASIC.


APPENDIX C

Cells 1 / 2 Stage 8 Design Drawings

Documents

CDO Cells 1/2 Stage 8 Embankment Raise