Govt of Western Australia Dept of Water and Safety Environmental Regulation – Solomon Mine Decision Document (TPD1810051)

Contents

Decision Document                                                                                                                        1

Contents                                                                                                                                       2

1             Purpose of this Document                                                                                                      2

2             Administrative summary                                                                                                         2

3             Executive summary of proposal and assessment                                                                     3

4             Decision table                                                                                                                      13

5             Advertisement and consultation table                                                                                    19

6             Risk Assessment                                                                                                                 20

Appendix A                                                                                                                                  21

Appendix B                                                                                                                                  35

Appendix C                                                                                                                                  38

Appendix D                                                                                                                                  40

References                                                                                                                                  43

1                  Purpose of this Document

This decision document explains how DWER has assessed and determined the application and provides a record of DWER’s decision-making process and how relevant factors have been taken into account. Stakeholders should note that this document is limited to DWER’s assessment and decision making under Part V of the Environmental Protection Act 1986. Other approvals may be required for the proposal, and it is the proponent’s responsibility to ensure they have all relevant approvals for their Premises.

2                  Administrative summary

3                  Executive summary of proposal and assessment

The Solomon Mine (Premises) is operated by FMG Solomon Pty Ltd (Licensee), a wholly owned subsidiary of Fortescue Metals Group Ltd (FMG). The Premises has been assessed as a “prescribed premises” as it meets the requirements of categories 5, 54, 57, 61, 62, 64 and 73 activities under Schedule 1 of the Environmental Protection Regulations 1987 (EP Regulations). The Premises has been in operation since 2010.

Mining is undertaken using standard open cut methods, with overburden and waste stored in external waste dumps and/or backfilled to the mined out pit. Ore processing is undertaken using permanent and/or mobile ore processing facilities (OPF). The Premises currently consists of several iron ore mining areas including Firetail North and South, Valley of the Kings (Kings), Valley of the Queens (Queens), Trinity and Zion.

Tailings produced from the beneficiation of ore through the Kings OPF wet processing circuit are deposited into the Kings Tailings Storage Facility (TSF).

The Premises is supported by ancillary infrastructure including accommodation village wastewater treatment plants (WWTP), inert and putrescible landfills, used tyre storage areas, a bioremediation facility, bulk and satellite fuel storage areas, workshops and administration buildings.

The Licensee also accepts liquid waste from the Solomon Power Station, occupied by TEC Pipe Pty Ltd.

The Premises is located approximately 54 kilometres (km) north of Tom Price and 12 km north west of Karijini National Park in the Pilbara region of Western Australia as shown in Figure 1.

Figure 1: Regional location Premises description

The Licence is regulated for category 5, 54, 57, 61, 62, 64 and 73 activities as defined in Schedule 1 of the EP Regulations and as described below:

C ategory 5 – Processing or beneficiation of metallic or non-metallic ore

OPF and TSF

Mining at the Premises is conventional open pit method of drill and blast followed by load and haul. The Run of Mine (ROM) ore from each mining area is blended at a number of separate crushing hubs to ensure consistent mixing of ore and reduce ROM ore to 250 millimetres (mm) from a top lump size of 1,800 mm. Once the ore is crushed it is transported to either the Firetail or Kings OPF via an overland conveyor, which are designed to produce approximately 25 million tonnes per annum (Mtpa) and 48 Mtpa of produce ore respectively.

The ore is processed further at the OPFs using a grinding and gravity separation method. The OPFs operate in a similar manner and comprise of wet scrubbers, secondary and tertiary crushers, desand plant, jig plant (Firetail OPF only) and associated screens and conveyors.

The undersize fraction (<1 mm) is sent to the desand plant for removal of liberated gangue particles through gravity separation to produce an upgraded concentrate. The final concentrate from the desand plant is discharged onto the final product conveyor, while tailings are pumped to the TSF (discussed further in Appendix A) via the thickener.

A flocculent, Magnafloc 336, is added to the feed slurry entering into the thickener tank at the Firetail and Kings OPFs. Flocculated particles settle to the bottom and are pumped to the TSF, while the clarified water overflows the top of the thickener and into the process water system for reuse within the OPFs.

Processed ore is transported by conveyor to the rail stockyard, which consists of four stockpile ‘pods’ of approximately 130,000 tonnes each, as well as two stackers, conveyors and a reclaimer. From the stockpiles the ore is reclaimed and loaded onto trains and transported to the Licensee’s Port Hedland Port facility (Anderson Point Materials Handling Facility), for export.

Direct Shipping Ore Processing Plant (DSOPP)

The Licensee also operates DSOPP at the Premises, with a design capacity of 3.6 Mtpa. The DSOPP is comprised of a ROM stockpile, primary crusher, fixed rock breaker, tertiary cone crusher, product screening, product stockpile and oversize stockpiles.

Mobile Crushing Facilities (MCF)

Four MCF are also operated at the Premises as part of an additional ore program. In aggregate, these four facilities have a design capacity of 18.7 Mtpa.

Mine dewatering of the Channel Iron Deposits (CID) is required to access ore below the water table. Mine dewater is used onsite for processing and dust suppression. There are no specified emission points from which mine dewater is discharged to the environment, as such, the activity does not trigger category 6 (mine dewatering) under Schedule 1 of the EP Regulations.

Category 54 – Sewage facility

The Licensee operates two WWTPs at the Premises to treat wastewater produced from the site’s two accommodation villages. The Castle/Dally Camp WWTP and Kangi Camp WWTP have a combined treatment capacity of 1,178 cubic metres (m3) per day (m3/day). Treated wastewater from the WWTPs is disposed of via irrigation to two separate irrigation areas, or used for dust suppression throughout the Premises.

The WWTPs are sequence batch reactor (SBR) treatment trains. The process follows the SBR methodology of wastewater treatment, comprising of balance tanks, SBR treatment trains (anaerobic tanks, anoxic tanks, aeration tank and a classifier tank).

A sludge press has also been installed at the Kangi Camp WWTP. Sludge is conveyed from the sludge tanks to the polymer preparation station comprising a 200 litre (L) storage tank and dosing pump. The sludge is then conveyed to the screw press. As sludge enters the press, filtrate is drained and pressure is applied to the sludge to create a sludge cake. The filtrate discharged from the press is recirculated through the WWTP. Approximately 13.2 kilolitres of filtrate is recirculated through the WWTP per annum. Approximately 26.8 m3 of sludge cakes are produced and require disposal per annum. The sludge cakes are temporarily stored in a skip bin prior to disposal. The cakes meet the description of biosolids in the Landfill Waste Classifications and Waste Definitions 1996 so are suitable for disposal in Class I landfills.

Category 57 – Used tyre storage

The Licensee stores up to 2,500 tyres at the Premises at any one time.

 Category 61 – Liquid waste facility

The Licensee accepts liquid waste from the Solomon Power Station, occupied by TEC Pipe Pty Ltd. This liquid waste comprises of treated wastewater from a reverse osmosis plant, oily water separator and cooling tower blowdown.

Treated wastewater is pumped from a wastewater storage tank at the Solomon Power Station via an underground pipeline to a wastewater storage tank located at the Licensee’s stockyards. Treated wastewater is collected from this tank by water trucks and used for dust suppression on roads and stockpiles across the Premises. Up to 110,000 tonnes of liquid waste per annum is accepted onto the Premises.

 Category 62 – Solid waste depot

A waste transfer station has been constructed at the Premises to allow separation and temporary storage of up to 6,000 tonnes per annum of waste and recyclable material generated by construction and operation activities at the Premises.

Hazardous wastes, recyclables and non-recyclable waste streams are accepted at the waste transfer station for temporary storage prior to disposal or recycling. Hazardous waste storage at the waste transfer station are lined with high density polyethylene (HDPE) and stored in accordance with the Chemical and Hydrocarbon Management Plan. The waste transfer station inputs and outputs are described in Table 1.

Table 1: Waste transfer station inputs and outputs

The facility includes maintenance, office and ablution blocks and a bale shed for the baling of waste. Within the waste transfer station, separate areas are demarcated for the different waste types, with each area labelled. Storage areas for scrap metal, wood, conveyor belts, Intermediate Bulk Containers and smaller recyclable items are uncovered, while dispersible recyclable material (e.g. paper, plastic) are enclosed.

Non-recyclable waste streams may be taken to the waste transfer stations for sorting and temporary storage after which waste suitable for disposal onsite is disposed either at the landfill or in mined out pits and waste dumps. Recyclable and hazardous (controlled) waste is collected from the waste transfer station for disposal off site as required. Controlled waste transport is conducted by a licensed controlled waste contractor.

Areas for the temporary storage of chemical and hydrocarbon waste materials, and hazardous waste, are lined with HDPE or concrete with a permeability of 1 x 10-9 metres per second (m/s) or less, and are uncovered. The bunded area has a minimum capacity of 110% of the largest container stored within it, or 25% of the volume of all containers, whichever is the larger. Spill response equipment is in place to address any chemical or hydrocarbon spills which may occur in this area.

Asbestos is managed in accordance with the Environmental Protection (Controlled Waste) Regulations 2004. It is temporarily stored at the waste transfer station prior to disposal at a licensed disposal facility. It is separated from other wastes and wrapped or contained in a manner that prevents asbestos fibres entering the atmosphere. Storage is either within a waste skip bin with a lid, or an enclosed shipping container.

On completion of use, the waste transfer station will also be closed and rehabilitated in accordance with the Premises Mine Closure Plan, required by condition 15 of Ministerial Statement (MS) 1062.

Category 64 – Putrescible/Inert Landfills

The Licensee currently disposes of up to 14,000 tonnes per annum of waste at a number of disposal locations within the Premises. There are three major waste streams produced at the Premises, including solid waste (clean fill, inert waste type 1 and inert waste type 2, putrescible waste), recyclables and hazardous or controlled wastes.

Waste not meeting the requirements for a Class II landfill, as described in the Landfill Waste Classification and Waste Definitions 1996, is stored temporarily for collection and disposal off-site, with the exception of contaminated soil, which is disposed at the Licensee’s onsite soil bioremediation facility or removed off-site to a licensed facility for disposal.

The disposal of untreated wood is restricted to the Solomon Landfill, Firetail North Waste Dump, Firetail Waste Wood Disposal Area and the Kings Waste Dump. Tyres and other rubber waste are disposed of in the Solomon Landfill, Kings Pit, Kings Waste Dump, Firetail South Waste Dump, Firetail South Pit, Firetail North Pit, Trinity Waste Dump and Trinity Mine Pit.

C ategory 73 – Bulk storage of chemicals

The Licensee currently operates a bulk fuel storage facility (BFSF) at the Premises which comprises of two 3.25 million litre vertical diesel storage tanks, with a combined storage capacity of 6.5 million litres. The key components of the BFSF include a rail offloading station, road tanker offloading station and the diesel tank storage area.

The Licensee also operates a number of smaller fuel storage facilities at the Premises which have a combined storage volume of 1,221 m3.

Location and siting

 Sensitive land uses

The nearest sensitive receptors to the Premises is Hamersley Station, located approximately 33 km south-west and Hamersley Gorge (a popular tourist precinct used for recreational activities) located within Karijini National Park is approximately 13 km south, south-east of the Premises.

The workforce for the Premises operates on a fly-in/fly-out basis and is housed at the accommodation villages located within the prescribed premises boundary. As the accommodation villages are operated by the Licensee, they are not considered by DWER to be a sensitive land use or receptor for the purpose

of assessing the risks of emissions and discharges associated with the operation of the prescribed activities.

S pecified Ecosystems

The Guidance Statement: Environmental Siting describes specified ecosystems as areas of high conservation value and special significance that may be impacted as a result of activities or emissions and discharges from prescribed premises. The specified ecosystems relevant to the Premises are identified below:

The Premises is located at the headwaters of the Millstream Catchment. The western portion of the Kings mining area is situated within the Millstream Water Reserve, which is a Priority 2 Public Drinking Water Source Area (PDWSA). Mining, including the operation of TSFs for which tailings from physical separation processes is considered compatible in Priority 2 areas, is detailed in the Water Quality Protection Note 25: Land compatibility tables for public drinking water source areas. The TSF is not located within the PDWSA.

The Premises exists within the Proclaimed Pilbara Groundwater and Pilbara Surface Water Areas under the Rights in Water and Irrigation Act 1914 (RIWI Act).

The BFSF is located approximately 10 km north of Karijini National Park which is managed by the Department of Biodiversity, Conservation and Attractions.

The Fortescue Marsh a Priority 1, Priority Ecological Community (PEC) and nationally important wetland is located approximately 35 km east of the Premises.

The Priority 1, PEC of the Brockman Iron cracking clay communities of the Hamersley Range (DBCA, 2017a) and the Themeda Grasslands a Threatened Ecological Community (TEC) (DBCA, 2016) are located approximately 1 km south of the Premises.

Lepidium catapycnon (previously a Declared Rare Flora, now a Priority 4 Flora) (DBCA, 2017b) is located within the Premises.

V egetation and flora

The Premises lies within the Fortescue Botanical District of the Eremaean Botanical Province. The vegetation of this province is typically open, and frequently dominated by spinifex, wattles and occasional Eucalypts.

FMG, 2016 states that six priority flora species have been recorded within the Premises including:

• Gompholobium karijini (Priority 2);
• Acacia effusa (Priority 3);
• Acacia daweana (Priority 3);
• Indigofera gilesii subsp. gilesii (Priority 2);
• Eremophila magnifica subsp. magnifica (Priority 4); and
• Goodenia nuda (Priority 4).

T errestrial Fauna

FMG, 2016 states that conservation significant fauna species that have been found in the area include:

• Northern Quoll (Endangered under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) and Schedule 2 of the Wildlife Conservation (Specially Protected Fauna) Notice 2016);
• Pilbara Olive Python (Vulnerable under the EPBC Act and Schedule 3 of the Wildlife Conservation (Specially Protected Fauna) Notice 2016);

• Fork Tailed Swift (Migratory);
• Rainbow Bee-eater (Priority 5);
• Pebble-mound Mouse (Priority 4);
• Ghost Bat (Vulnerable under the EPBC Act and Schedule 3 of the Wildlife Conservation (Specially Protected Fauna) Notice 2016); and
• Blind snake (Priority 1).

G eology and soils

The Premises is located within the Hamersley Basin, which overlies the older Pilbara craton. The Hamersley Range extends across the central Pilbara from the north-west to the south-east. It is a large plateau approximately 400 km in length, ranging in width from 32 to 64 km; and consists of mostly banded iron formation, pelite (metamorphosed siltstone), chert and dolomite. Stony soils with shallow red loams and some red-brown non-cracking clays and red loamy earths cover much of the area.

The Brockman Iron Formation (BID) is the dominant lithology of the hills, plateaux and outcrops in the Premises area; with outcrops in the area consisting of the Dales Gorge, Whaleback Shale and Joffre members of the BID. The Mt McRae Shale overlies these members and outcrops at the surface within the valley floor of the Firetail anticline. The Mt McRae shale visible at surface is weathered and is geochemically dissimilar from potentially acid forming units found at depth.

Large paleochannels, one to two kilometres in width and tens of kilometres long, are incised into the bedrock. During the tertiary period weathering and erosion of iron-rich surrounds deposited iron rich material into these channels (CID) and this material has subsequently been buried and preserved. The younger Detrital Iron Deposits (DID) overlying the CID has been eroded from iron rich materials.

The Solomon iron ore deposits comprise all three of the deposits described above, being BID, CID and DID. The BID and DID are generally above the water table, with the CID being generally below the water table.

 Regional hydrology

The primary aquifer in the Premises area is associated with the Lower CID unit. Regional bedrock groundwater flow direction is from south to north, with the water table an average of more than 50 m below the surface. Groundwater quality is fresh to marginal, with total dissolved solids (TDS) ranging from 200 mg/L to 1,000 mg/L.

The Premises is located within the Lower Fortescue River Watershed which has an intermittent flow pattern resulting in river and creeks being dry for most of the year. Following significant rainfall, channels in the region carry large volumes of water with peak flows usually occurring within 24 hours of the rainfall event.

Three streams traverse operational areas of the Premises: Zalamea (South East flow), Kangeenarina (Central flow) and Queens (West flow). The western boundary of the Premises is formed by Weelumurra Creek.

 Meteorology

The Pilbara has an arid climate with two distinct seasons; a pronounced dry spell between August and October; and a wet season between December and March, continuing through until June and accounting for most of the average annual rainfall. The average yearly evaporation rate of 3,000 mm exceeds the average yearly rainfall of 457.9 mm. The region is characterised by low and variable rainfall, generally resulting from local thunderstorms and occasional high intensity cyclonic events.

Clearing

Clearing is not authorised under this Licence. The clearing of native vegetation is authorised under MS 1062.

Part IV of the EP Act

R eport 1386

The proposal to develop two new mines within the Solomon Project and to construct a 127 km railway for the new mines eastwards to the existing FMG railway, developed the Report and Recommendations of the Environmental Protection Authority (EPA) Report 1386, which resulted in MS 862 being issued on 20 April 2011.

The EPA determined that the following were key environmental factors relating to the proposal:

• Flora and Vegetation;
• Groundwater;
• Surface Water;
• Vertebrate Fauna;
• Invertebrate fauna; and
• Mine Closure and Rehabilitation.

 MS 862

MS 862 had conditions relating to the following:

• Priority Species and Significant Vegetation – Mine Site;
• Priority Species – Rail Corridor;
• Weeds;
• Rehabilitation;
• Surface Water;
• Groundwater;
• Vertebrate Fauna;
• Troglofauna;
• Mine Plan and Conceptual Closure Strategy; and
• Final Closure and Decommissioning Plan.

 Report 1588

The proposal to expand the Solomon Iron Ore Mine Project in order to sustain production for an additional 30 years from 2016 developed the Report and Recommendations of the EPA – Report 1588.

The EPA identified the following key environmental factors during the course of its assessment:

• Flora and Vegetation – impacts to conservation significant flora and vegetation as a result of large-scale clearing of native vegetation, and impacts to Groundwater Dependent Ecosystems as a result of groundwater abstraction for water supply purposes;
• Terrestrial Fauna – impacts to terrestrial fauna species as a result of clearing of habitat including riparian vegetation and permanent pools in Zalamea Creek;
  • Subterranean Fauna – loss of habitat for subterranean fauna species as a result of groundwater abstraction and excavation of mine pits;
  • Hydrological Processes – impacts to springs and pools including Hamersley Gorge and Weelumurra pools as a result of groundwater abstraction for water supply purposes;
  • Inland Waters Environmental Quality – impacts to groundwater quality as a result of in-pit tailings storage within the Millstream PDWSA and potential for disturbance or dewatering of lignite in the Queens area resulting in impacts to Weelumurra Creek ;

• Rehabilitation and Decommissioning (Integrating factor) – potential impacts to the above environmental factors if rehabilitation or decommissioning are unsuccessful; and
• Offsets (Integrating factor) – use of offsets to counterbalance the significant residual impact associated with clearing of 12,146 hectares (ha) of native vegetation in ‘good to excellent’ condition, loss of habitat for conservation significant fauna, clearing of riparian vegetation and clearing of 6 ha PEC.

M S 1062

MS 1062 was signed by the Minister for Environment on 3 October 2017 and supercedes MS 862.

MS 1062 has the following conditions relating to the Mine:

• Baseline surveys – Groundwater and surface water dependent vegetation and permanent pools;
• Inland waters environmental quality – lignite studies;
• Management-based Condition Environmental Management Plans;
• Flora and Vegetation – conservation significant flora species and vegetation;
• Flora and Vegetation – weeds;
  • Flora and Vegetation – groundwater and surface water dependent vegetation and water levels;
  • Inland waters environmental quality – prevent impacts to groundwater from exposure or interaction with Lignite;
  • Terrestrial Fauna – conservation significant fauna;
  • Hydrological Processes – groundwater drawdown within Karijini National Park;
  • Subterranean Fauna;
    • Rehabilitation and Closure – rehabilitation and decommissioning of the mine and borefield; and
    • Offsets – mine and borefield.

Other Approvals

 EPBC Act

The Solomon Project was referred to the Commonwealth government for assessment in relation to Matters of National Environmental Significance. Approval for the Solomon Project was issued by the Federal Minister for the Environment on 28 April 2011 (EPBC 2010/5567).

The Solomon Iron Ore Project – Sustaining Production proposal was also referred to the Commonwealth Department of Environment (DoE). The proposal was determined to be a controlled action under the EPBC Act on 18 August 2014 (EPBC 2014/7275) as it may impact on listed threatened species and communities.

 RIWI Act

Groundwater abstraction is undertaken to enable the mining of ore below the water table and provide mine site water supply. Groundwater is abstracted in accordance with the 5C licences issued under the RIWI Act.

 Mining Act 1978

The Department of Mines, Industry Regulation and Safety (DMIRS) administers and regulates the activities of the mining industry under the provisions of the Mining Act 1978. The Licensee has advised (FMG, 2016) that staged Mining Proposals have been submitted under the Mining Act 1978.

January 2018 amendment

A licence amendment application (FMG, 2017) was submitted by the Licensee on 3 October 2017 to remove a landfill ambient monitoring bore (GQ8, WF-MB001S) at the Premises.

This amendment – December 2018

A licence amendment application was submitted by the Licensee on 3 October 2018 (FMG, 2018b) for upgrades to the Dally Camp WWTP.

During this amendment the following changes have also been made to the Licence:

• Inclusion of crest elevation level for TSF1 in Table 1.2.1;
  • Inclusion of design and construction requirements for the Dally Camp WWTP to condition 1.2.8;
  • Inclusion of size of irrigation fields to Table 2.2.1 for both the Castle/Dally Camp WWTP and Kangi Camp WWTP; and
  • Inclusion of notification requirements for the upgrades to the Dally Camp WWTP for conditions 1.2.9 and 4.3.1.

DWER’s assessment and decision making with respect to emissions and discharges associated with the operation of the Premises are described in section 4 of this document.

4                  Decision table

All applications are assessed in line with the EP Act, EP Regulations and Guidance Statements: Decision Making and Risk Assessments. Where other references have been used in making the decision they are detailed in the Decision Document.

5                  Advertisement and consultation table

6                  Risk Assessment

Note: This matrix is taken from the Guidance Statement Risk Assessments

Table 2: Emissions Risk Matrix

Appendix A

Stormwater management

E mission Description

Emissions: Potentially contaminated and sediment laden stormwater from the landfilling operations, waste transfer station, bioremediation facility, treated wastewater irrigation areas, work areas (ROM, OPFs, workshops) and fuel storage areas.

Impact: Contamination of surrounding land and surface water drainage systems. Potential impacts on ecology of surface water from the addition of nutrients, heavy metals and/or hydrocarbons. Increased turbidity of surface water and sedimentation impacting aquatic biota and ecosystems.

Potential impacts to the Millstream Water Reserve, a Priority 2 PDWSA.

Controls: Surface water management at the sizing hubs, OPFs and rail stockyard, include the following:

• Key infrastructure located above the 100 year floodplain and/or protection in a 1 in 100 year rainfall event;
• Separation of clean and potentially contaminated stormwater using diversion measures;
• All potentially contaminated stormwater is directed to sedimentation basins or sediment traps prior to release; and
• Diversion drain to the north-east of the stockyard captures clean stormwater and directs it around the stockyard.

The following stormwater and surface water management measures have been implemented at the DSOPP:

• Perimeter drain and sediment traps located around the pit and stockpiles;
• Rock lined drains to ensure excess runoff is directed to sediment traps;
• Perimeter bunding (where practical) and internal drainage water from rainfall retained around ore stockpiles;
• Internally draining pit with rainwater collected for dust suppression purposed; and
• Runoff from stockpiles diverted to sediment trap.

The following management measures have been implemented at the MCF to manage stormwater:

• Potentially contaminated stormwater is contained and appropriately treated prior to disposal;
• The site has been graded to ensure that all stormwater, wash-down and spillage water runoff is directed to a collection and settling sump, where it is recycled for dust suppression purposes;
• MCF are contained within an earthen perimeter bund; and
• Runoff from stockpiles is diverted to the settling sump.

The landfill has a perimeter drainage channel and a drainage sump captures any potentially contaminated stormwater. This sump has been designed to prevent the discharge of stormwater from approximately a 1 in 20 year rainfall event.

The landfill and waste transfer station are located greater than 100 m from the nearest surface water feature and outside of the 1 in 100 year average return interval (ARI) flood plain. Surface water in the area consists of episodic drainage. The waste transfer station is inspected on a regular basis, and before anticipated significant rainfall events.

The following measures have been implemented at the fuel storage areas to minimise stormwater contamination from occurring:

• Concrete bunding to capture any spills during refuelling of light vehicles at some facilities;
• Drainage of oily water from the central facilities fuel storage area to a lined evaporation pond; and
• Spill grates collect stormwater runoff from around the tanks. Grates are inspected daily and pumped out as required.

Hydrocarbon storage areas across the Premises are appropriately bunded and potentially contaminated stormwater is diverted to oily water separators (OWS) for treatment prior to discharge. The OWS have been designed to treat wastewater to achieve a total recoverable hydrocarbon (TRH) concentration of less than 5 mg/L. The Licensee has installed and maintains OWS at the BFSF, Rail Fuel Siding, Castle Camp Washdown Bay, Trinity Fuel Farm, Kings Fuel Farm, Firetail Fuel Farm and the Kings OPF facility to treat potentially contaminated stormwater prior to discharge.

The Licensee has developed and implements the Surface Water Management Plan at the Premises, the objectives being:

• Maintain integrity of flow paths and water quantities to protect surface water dependent ecological systems;
• Minimise excessive turbidity and downstream sedimentation caused by erosion;
• Prevent and minimise impacts to surface water quality;
• Minimise impact of storm surge and flooding; and
• Monitor and report sufficiently to demonstrate compliance and enable management to make informed decisions than minimise environmental impacts to surface water dependent ecological systems.

Risk Assessment

Consequence: The Millstream Water Reserve has been identified as a sensitive receptor based on proximity to the Premises. The impact to the Millstream Water Reserve from stormwater runoff within and from the Premises could result in low level off-site impacts at a local scale. Therefore, the consequence is moderate.

Likelihood: Based on the Licensee controls (stormwater diversion, bunding, sediment basins), impacts to sensitive receptors from the discharge of contaminated and/or sediment laden stormwater will not occur in most circumstances. Therefore, the likelihood of the consequence is unlikely.

Overall Risk Rating: Comparison of the consequence and likelihood ratings described above with the Emissions Risk Matrix (Table 2) determines the overall rating of risk for discharges of contaminated and/or sediment laden stormwater to the environment to be medium, subject to regulatory control.

 Regulatory Controls

Condition 1.2.11 specifies the infrastructure to be maintained to ensure stormwater is appropriately managed. The requirements of this condition are consistent with the existing Licensee controls considered by the Delegated Officer in the risk assessment for stormwater.

Bulk and satellite fuel facilities

 Emission Description

Emission: Seepage of hydrocarbons to soil or groundwater from leaking bulk and satellite fuel facilities. Hydrocarbon spills outside of engineered containment infrastructure during refuelling and fuel transfer activities.

Impact: Soil contamination, impacts to surface water ecosystems, groundwater dependant ecosystems and terrestrial ecosystems from addition of hydrocarbons and other chemicals.

Controls: The Licensee has implemented the following measures to manage hydrocarbon/chemical storage on the Premises:

• The structural steel used to construct the tanks comply with requirements of AS/NZS 3678:2011;
• Diesel storage tanks, including pumps and pipe work, are located in a concrete bunded area designed to comply with requirements of AS 1940:2017;
• The tanks are fitted with Radar level transmitters in the roof with alarms to indicate high level which shut down the offload pumps;
• The tanks contain back-up overflow pipes extending down the tank side to direct any excess diesel to flow into the concrete bund at ground level;
• Each of the 12 train offloading arms have ‘catch pans’ under each rail car coupling and concrete bunding under the three train offloading pumps;
• All catch pans and concrete bunding are designed to have permeability of less than 10-9 m/s;
• The catch pans and bunded areas are gravity fed through piping to the OWS to treat any stormwater runoff captured within the bunded area to achieve a discharge quality of less than 5 parts per million (ppm) of total petroleum hydrocarbons; and
• Appropriate types and quantities of spill response equipment are maintained onsite proportionate to the volume of chemicals and hydrocarbons stored.

Risk Assessment

Consequence: The impact from spills/leaks of hydrocarbons from the bulk and satellite fuel facilities will result in minimal onsite impacts. Therefore, the consequence is slight.

Likelihood: Based on the Licensee controls, the frequent use and size of the fuel facilities, an environmental impact from spills and leaks of hydrocarbons/chemicals could occur at some time. Therefore, the likelihood of the consequence is possible.

Overall Risk Rating: Comparison of the consequence and likelihood ratings described above with the Emissions Risk Matrix (Table 2) determines the overall rating of risk for leaks and spills of hydrocarbons/chemicals to the environment to be low.

 Regulatory Controls

The Delegated Officer notes that the Licensee has developed and implements the Chemical and Hydrocarbon Management Plan, in accordance with Part IV of the EP Act.

Fuel facilities are managed under the Solomon Project Dangerous Goods Site Licence and

Dangerous Goods Safety Act 2004, administered by DMIRS.

The Delegated Officer is not imposing any specified conditions for the management of hydrocarbons, as sufficient regulatory control is currently imposed through approvals pursuant to Part IV of the EP Act and DMIRS.

Fuel storage areas at the Premises will be subject to DWER inspections, during which the management measures in place to minimise potential environmental impacts associated with chemical and hydrocarbon transport, storage, handling and disposal will be considered.

The general provisions of the EP Act with respect to the causing of pollution and environmental harm apply and discharges of hydrocarbons may be subject to the Environmental Protection (Unauthorised Discharges) Regulations 2004.

TSF

During the May 2017 amendment, the Licence was amended to approve the TSF embankment lift.

The Licensee has raised the existing TSF at the Premises from a crest elevation of 572 m Reduced Level (RL) to a crest elevation of 588.2 mRL (Stage 1) (TSF Embankment Lift Compliance Document). The Stage 1 embankment raise provides approximately 8 years’ storage life for tailings produced at the Kings OPF at a rate of approximately 6 Mtpa. The total raise is 33 m, and Stage 1 and Stage 2 (crest elevation to RL 605 m) are approximately 16.5 m each (SRK Consulting).

The tailings is delivered to the TSF via a tailings delivery pipeline from the Kings OPF. Tailings is deposited from spigots or open ended pipes located along the upstream crest of the raised embankment.

Surface water is decanted from the TSF via the decant tower. Decant water is discharged to the existing return water storage pond and pumped to the OPF for re-use via the return water pipeline.

The facility incorporates an emergency decant line to Kangeenarina Creek, which will operate as a contingency only (refer to Appendix D).

The TSF is located directly upstream of offices and workshops and mine access roads used by light vehicles, buses and trucks. In future mining plans, the open pit will also extend into the potential downstream breach-flow zone of the tailings dam.  Therefore, in accordance with the Code of Practice for Tailings Storage Facilities in Western Australia, the raised TSF will be classified as a High Hazard Category 1 facility.

Groundwater monitoring bores are utilised to monitor groundwater for seepage impacts. These bores will be effective until approximately 2020, after which time the level of the tailings will encroach on several of the monitoring bores. The Licensee has advised that a licence amendment application will be submitted for approval to replace the effected bores.

Normal operation

E mission Description

Emission: Seepage from the TSF migrating to groundwater. Tailings are a waste product from the gravity separation process conducted at the OPFs. The tailings are dosed with a flocculent at the OPFs to aid in the sedimentation of solids and upon arrival at the TSF the tailings are approximately 50% solids. The flocculent, Magnafloc 336, is non-toxic and is added at the recommended dose of 50-200 grams per tonne, or 0.05-0.2 ppm.

Approximately 45,000 L per month of treated oily water is discharged to the TSF via the OPF thickener.

Impact: Potential impacts to groundwater quality and groundwater levels (mounding). Changes to groundwater quality could impact on ecosystems receiving groundwater in the area. Mounding may impact on local vegetation, if it results in the growth medium becoming water logged. Groundwater is approximately 10 m below ground level (mbgl) at the location of the TSF.

Controls: The various rock formations underlying the TSF have permeability in the range of 1 x10-5 to 1×10-9 m/s. The base of the TSF is now covered by low permeability tailings which will minimise seepage.

Supernatant water is decanted to minimise ponding and losses through seepage.

The Licensee has prepared the Tailings Seepage Report, which compares the quality of groundwater in monitoring bores downgradient of the pre-existing TSF in order to determine whether there is any appreciable impact to the receiving environment. The report concludes that the likelihood of acid or metalliferous drainage is low for tailings, based on geochemical static and short-term kinetic testing of three samples and characterisation of 33 tailings samples for acid potential.

This conclusion is based on the assumption that environmentally harmful mine drainage will only occur in the presence of sulphide minerals or the reaction products of sulfide oxidation, and that acid- base accounting and short-term leaching tests will adequately characterise the risks of metals and metalloids being leached from tailings materials.

The Delegated Officer notes that this assumption is not always valid as environmentally harmful concentrations of some metals and metalloids have the potential to be leached from mine wastes under circum-neutral pH conditions, even in the absence of sulfide minerals (MEND, 2004). Metals and metalloids that are at particular risk of being leached in such circumstances are antimony, arsenic, cadmium, chromium, cobalt, copper, iron, manganese, mercury, molybdenum, nickel, selenium, uranium and zinc (MEND, 2004). Many of these elements are present at elevated concentrations in the tailing material, and additionally, boron and strontium are present at elevated levels in tailings supernatant. This issue could be better characterised by conducting long-term and/or sequential leaching tests on the tailings material. The Delegated Officer notes that at this time, the risks associated with tailings leachate can be appropriately addressed by the TSF design and management measures.

A drainage system has been installed on the existing TSF. This system involves a filter/drain and collection network, and discharges to the return water dam at the base of the TSF. No seepage from the embankment has occurred, and is not anticipated under normal operating conditions due to the distance from the decant pond, which is located around 1 km from the embankment.

Modelling indicates that seepage rates downstream of the embankment are unlikely to be sufficient to require installation of seepage recovery bores. During operation of the mine, drawdown of groundwater for mine pit dewatering mitigates any potential mounding due to seepage. If seepage exceeds the design prediction to the extent that an unacceptable water level rise occurs on the downstream side of the TSF, or water flows into the downstream mining area are excessive, seepage recovery bores will be installed.

With respect to the discharge of treated oily water, the Delegated Officer notes that the Ultraspin OWS is designed to reduce TRH in wastewater to less than 15 mg/L and that within the thickener treated wastewater will be diluted at a ratio of approximately 1:148.

The TSF is located approximately 5 km from the Millstream PDWSA. Kangeenarina Creek is located

1.5  km downstream of the TSF.

The Delegated Officer notes that the TSF has been assessed by the former Department of Mines and Petroleum pursuant to the Mining Act 1978.

Risk Assessment

Consequence: Based on the geochemical characterisation of the tailings and the tailings seepage report, the impact of TSF seepage to sensitive receptors could result in low level off-site impacts at a local scale. Therefore, the consequence is moderate.

Likelihood: Based on the Licensee controls (drainage system, distance to the Millstream PDWSA), the impact to sensitive receptors from TSF seepage will not occur in most circumstances. Therefore, the likelihood of the consequence is unlikely.

Overall Risk Rating: Comparison of the consequence and likelihood ratings described above with the Emissions Risk Matrix (Table 2) determines the overall rating of risk for TSF seepage to be medium, subject to regulatory control.

R egulatory Controls

Construction

Conditions 1.2.8 and 1.2.9 include construction requirements for the TSF embankment lift and the operation of the TSF in accordance with the conditions of the Licence following submission of compliance documentation, required under condition 4.3.1.

Operation

During this amendment (December 2018) the crest elevation to RL 605 m Australian Height Datum (AHD) has been specified within Table 1.2.1 for TSF1.

Condition 1.2.7 requires an annual water balance for the TSF to be undertaken. Condition 3.4.1 has process monitoring requirements for the TSF which relate to monitoring the volume and mass deposited into the TSF, volumes of water recovered from the TSF measured from the TSF return line and gravity decant return line.

Ambient groundwater monitoring is conducted at five locations around the TSF to determine if groundwater quality is being impacted by the operation of the TSF – refer to the section 4 under “ambient monitoring”.

The annual water balance, process monitoring and the ambient groundwater monitoring results are reported to DWER in the Annual Environmental Report (AER) for the Premises.

Abnormal Operation/Emergency Situation

 Emission Description

Emission: Release of tailings due to overtopping of the TSF or embankment breach.

The tailings will have been dosed with a flocculent at the OPFs to aid in the sedimentation of solids and upon arrival at the TSF the tailings are approximately 50% solids. The flocculent, Magnafloc 336, is non-toxic and will be added at the recommended dose of 50-200 grams per tonne, or 0.05-0.2 ppm.

Impact: Contamination of surrounding soil, impacts to surface water quality and groundwater. Vegetation stress/degradation if volume released is significant or exposure prolonged. Site facilities, including workshops, are located downstream of the TSF.

Controls: The TSF has been designed as a non-release facility, with sufficient capacity to accommodate at least a 1 in 100 year, 72 hour event and maintain a 500 mm total freeboard, as required by the DMIRS Guidelines. The TSF and TSF embankment lift have been assessed by DMIRS via the Mining Proposal.

If the maximum operating water level is reached, the OPF production and all production water inputs into the TSF will be halted to prevent overtopping. There is no emergency spillway, however the existing emergency decant line to Kangeenarina Creek remains in place for contingency discharge, if required (refer to Appendix D).

Risk Assessment

Consequence: Following consideration of the geochemical characterisation of the tailings and location of Kangeenarina Creek 1.5 km downstream, the impact to sensitive receptors from tailings discharge due to containment/embankment breach or overtopping could result in midlevel onsite impacts and low level off-site impacts at a local scale. Therefore, the consequence is moderate.

Likelihood: Based on the Licensee controls (designed to contain a 1 in 100 year, 72 hour event and maintain a 500 mm freeboard), an impact to sensitive receptors from tailings discharge as a result of a containment/embankment breach or overtopping will probably not occur in most circumstances.

Therefore, the likelihood of the consequence is unlikely.

Overall Risk Rating: Comparison of the consequence and likelihood ratings described above with the Emissions Risk Matrix (Table 2) determines the overall rating of risk for tailings discharge from loss of containment to be medium, subject to regulatory control.

Regulatory Controls

Condition 1.2.2 specifies requirements relating to containment infrastructure at the Premises, including the TSF and includes:

• Maintaining of a 500 mm freeboard;
  • Provision of additional sufficient freeboard to minimise the likelihood of erosion of the embankments by wave action; and
  • Installation and maintenance of a seepage collection and recovery system.

Condition 1.2.6 also requires daily visual inspections of the TSF to be undertaken to ensure freeboard capacity is maintained.

The Delegated Officer considers these measures as appropriate to prevent overtopping from the TSF and erosion which could compromise the integrity of the embankment.

The Licensee is also required to comply with the following obligations outlined in the Mining Proposal, issued under the Mining Act 1978:

• Implement the TSF1 Operation, Monitoring and Surveillance Manual;
• Daily operator inspection and routine higher level inspections and audits;
• Monitoring of water balance, including site rainfall and evaporation, tailings return water recovery volumes, seepage recovery volumes and volumes of tailings deposited; and
• An annual operational audit by an independent geotechnical or engineering specialist.

Abnormal Operation/Emergency Situation

Emission Description

Emission: Release of tailings due to pipeline rupture.

The tailings will have been dosed with a flocculent at the OPFs to aid in the sedimentation of solids and upon arrival at the TSF the tailings are approximately 50% solids. The flocculent, Magnafloc 336, is non-toxic and will be added at the recommended dose of 50-200 grams per tonne, or 0.05-0.2 ppm.

Impact: Contamination of surrounding soil, impacts to surface water quality and groundwater. Vegetation stress/degradation if volume released is significant or exposure prolonged.

Controls: The tailings pipeline runs along the overland conveyor route and consists of a 750 mm diameter carbon steel polyethylene pipeline. Leak detection is provided in the form of flow meters at the pumps and prior to discharge into the TSF. Pressure indication is also provided with the flow meters, with the pressure and flow differentials used to indicate a potential leak.

Risk Assessment

Consequence: Following consideration of the geochemical characterisation of the tailings and location of Kangeenarina Creek 1.5 km downstream of the TSF, the impact to sensitive receptors due to tailings discharge as a result of a pipeline rupture could result in midlevel onsite impacts and low level off-site impacts at a local scale. Therefore, the consequence is moderate.

Likelihood: Based on the Licensee controls (flow meters, pressure monitoring, pipe material) an impact to sensitive receptors from a tailing discharge as a result of a pipeline rupture will probably not occur in most circumstances. Therefore, the likelihood of the consequence is unlikely.

Overall Risk Rating: Comparison of the consequence and likelihood ratings described above with the Emissions Risk Matrix (Table 2) determines the overall rating of risk for tailings discharge from a pipeline rupture to be medium, subject to regulatory control.

Regulatory Controls

Condition 1.2.1 requires the tailings pipelines to be equipped with either telemetry, automatic cut-outs or secondary containment.

Condition 1.2.6 requires daily visual inspections of the tailings pipelines and tailings return water lines.

The Delegated Officer considers these measures as appropriate to minimise the impact of tailings discharge from pipeline ruptures.

WWTPs

The Premises has two WWTPs (Castle/Dally Camp WWTP and Kangi Camp WWTP) to treat wastewater produced from the site’s accommodation villages. Treated wastewater from the WWTPs is disposed of via irrigation to two separate irrigation areas, or used for dust suppression throughout the Premises. Refer also to Appendix B – emissions to land including monitoring.

During this amendment (December 2018) the Licensee is proposing to upgrade the Dally Camp WWTP at the Premises within the existing Dally WWTP footprint. An upgrade to the Dally Camp WWTP is proposed to support an equivalent of 1,200 people and treat a maximum throughput of 324 m3/day. There is no change to the design capacity of category 54 of the existing licence (1,178 m3/day).

The existing Dally Camp WWTP includes the following:

• Five chlorine tanks;
• One balance tank;
• One emergency overflow balance tank;
• One aeration tank;
• One anoxic tank;
• Two sludge tanks;
• One chlorination/irrigation station;
• 12.5 ha irrigation field;
• Fencing; and
• Associated pipework, pumps, electrical (including switchboard) and other sundry facilities to support the WWTP.

The Licensee is proposing to install the following additional infrastructure as part of the upgrade works and as shown in Figure 2:

• One SBR tank;
• One balance tank; and
• Associated pipework, pumps, electrical (including switchboard) and other sundry facilities to support the WWTP upgrade.

The WWTP will treat effluent to meet the specification detailed in Table 3. The treated effluent will be discharged to the existing 12.5 ha irrigation field.

Figure 2: Existing and proposed upgrades to the Dally Camp WWTP

E mission Description

Emission: Overflow of untreated and/or treated wastewater from the WWTP storage, treatment and sludge tanks.

Impact: Contamination of surrounding land and surface water drainage, potential for eutrophication of surface water due to elevated nutrients and ecosystem disruption.

Controls:

• Wastewater is treated to a High Exposure Risk Level (ERL) under Department of Health (DoH) guidelines at the Castle/Dally Camp and both Low ERL and High ERL at the Kangi Camp;
• High level audible and visual alarms are installed on the SBR and balance tanks;
• The WWTP tanks have the capacity to maintain one day freeboard; and
• The WWTP is located outside the 1 in 100 year floodplain.

Risk Assessment

Consequence: The impact of overflows of wastewater from the WWTP could result in minimal onsite impacts. Therefore, the consequence is slight.

Likelihood: Based on the location of the closest drainage line (170 m from the WWTP), distance to groundwater (40-50 mbgl) and location of the WWTP outside of the 1 in 100 year floodplain, an environmental impact from the overflow of wastewater will occur in exceptional circumstances.

Therefore, the likelihood of the consequence is rare.

Overall Risk Rating: Comparison of the consequence and likelihood ratings described above with the Emissions Risk Matrix (Table 2) determines the overall rating of risk for wastewater overflows to the environment to be low.

Regulatory Controls

Construction

During this amendment (December 2018) conditions 1.2.8 and 1.2.9 have been updated to include construction requirements for the upgrade works to the Dally Camp WWTP and operation in accordance with the conditions of the Licence following submission of compliance documentation, required under condition 4.3.1.

Operation

Discharges of sewage may be subject to the provisions of the Environmental Protection (Unauthorised Discharges) Regulations 2004.

Used tyre storage

Regulatory Controls

Condition 1.2.3 has management requirements for the storage of used tyres including:

• Not more than 2,500 used tyres to be stored at the Premises at any one time; and
• Used tyres shall not be stored closer than 6 m from any other tyre stack.

The Environmental Protection (Controlled Waste) Regulations 2004 sets out additional requirements for the acceptance of controlled waste (tyres).

Putrescible/Inert Landfills

Emission Description

Emissions: Potential leachate generation from inert and putrescible landfills.

Impact: Contamination of soil and groundwater, impacts to ecosystems receiving groundwater discharge from addition of hydrocarbons, nutrients and heavy metals. Potential impacts to the Millstream Water Reserve.

Controls: The Licensee has advised that the maximum depth to groundwater within the vicinity of the site’s putrescible landfill is approximately 50 mbgl; and the landfill is approximately 10 km from the groundwater bores used for potable water supply.

The Licensee restricts the type of waste that is accepted for burial at the in-pit and waste rock dump landfill locations. Only tyres, conveyor belts, concrete and untreated wood are allowed.

All wood loads are visually checked to confirm that the wood is untreated prior to disposal. A branding on the wood indicates whether the packaging has been heat–treated or fumigated with methyl bromide, and hence this will be checked prior to disposal.

Only inert and putrescible waste is accepted at the putrescible landfill. Weekly covering of waste and appropriate stormwater management onsite further reduces the risk of leachate from the landfill impacting on groundwater. A perimeter drainage channel around the putrescible landfill and a drainage sump captures any potentially contaminated stormwater.

The Licensee has installed monitoring bores upstream and downstream of the landfill and monitors them to determine if there are any impacts to groundwater quality as a result of waste disposal. The sample results are analysed and if there is a difference (>5%) between the results from each bore and the baseline samples, corrective actions are undertaken. The potential sources of the elevated concentrations are determined. If the landfill is confirmed as the source and no faults are identified, an investigation into the expected success of potential actions is undertaken with actions implemented based on the findings.

 Risk Assessment

Consequence: Leachate from the landfill facilities could result in low level onsite impacts and minimal off-site impacts at a local scale. Therefore, the consequence is minor.

Likelihood: Based on the Licensee controls (weekly covering of waste, stormwater diversion and management), depth to groundwater (50 mbgl), ephemeral nature of the creek systems in the area, landfill capacity and operational life, leachate from the landfills resulting in an environmental impact will probably not occur in most circumstances. Therefore, the likelihood of the consequence is unlikely.

Overall Risk Rating: Comparison of the consequence and likelihood ratings described above with the Emissions Risk Matrix (Table 2) determines the overall rating of risk for landfill leachate to be medium, subject to regulatory control.

Regulatory Controls

Condition 1.2.3 specifies requirements for the management of waste at the inert and putrescible landfills. The volume and types of waste is restricted to ensure that only that waste which has been assessed and approved for disposal is accepted at the landfills. Condition 1.2.5 specifies the landfill cover requirements, consistent with the controls proposed by the Licensee.

On completion of use, the landfill will be closed and rehabilitated in accordance with the Premises Mine Closure Plan, required by condition 15 of MS 1062. Closure will include fully covering all waste with inert material and creating a safe, stable, non-polluting landform. Topsoil will then be spread over the area to encourage revegetation.

HVWF

The Licensee has infrastructure onsite to contain potentially contaminated wash down water and stormwater runoff for treatment, or for holding prior to disposal.

E mission Description

Emission: Overflow of wastewater potentially contaminated with hydrocarbons and surfactants from the HVWF treatment ponds. Overflow of sumps or ponds used to store potentially contaminated stormwater.

Impact: Soil contamination, impacts to surface water ecosystems, groundwater dependant ecosystems and terrestrial ecosystems from addition of hydrocarbons and surfactants. Potential impacts to the Millstream Water Reserve.

Controls: The Licensee has stated the following (FMG, 2018a):

• Drainage infrastructure at the Premises is designed and managed in accordance with the

Surface Water Management Plan;

• The HVWF was constructed for a 5-year Average Recurrence Interval (ARI), with a 300 mm freeboard;
• The HVWF is located on a concrete slab with drainage directed to two pre-treatment ponds (one a sediment pond and the other a dirty water pond) prior to entering an oil water separator;
• The wastewater sumps associated with the HVWF are constructed of concrete with a permeability less than 1 x 10-9 m/s;
• The treated wastewater is stored in enclosed tanks and used for dust suppression or OPF water supply;
• The HVWF is located at least 1 km from the closest surface watercourse; and
• The HVWF is located within the Central Facilities Workshop Yard. This catchment is surrounded with a diversion bund to divert clean stormwater away from the workshop area, whilst a collection swale/trench directs potentially contaminated stormwater to a sediment basin.

R isk Assessment

Consequence: The impact from the discharge of potentially contaminated wastewater from the HVWF ponds could result in minimal on-site impacts. Therefore, the consequence is slight.

Likelihood: Based on the Licensee controls (concrete with permeability of less than 1 x 10-9 m/s, 300 mm freeboard), an environmental impact from the discharge of potentially contaminated wastewater from the HVWF ponds will not occur in most circumstances. Therefore, the likelihood of the consequence is unlikely.

Overall Risk Rating: Comparison of the consequence and likelihood ratings described above with the Emissions Risk Matrix (Table 2) determines the overall rating of risk for untreated wastewater emissions from the HVWF to be low.

R egulatory Controls

The Delegated Officer is not imposing any specified conditions for the HVWF ponds. The general provisions of the EP Act with respect to the causing of pollution and environmental harm apply and discharges of hydrocarbons may be subject to the Environmental Protection (Unauthorised Discharges) Regulations 2004.

Bioremediation Facility

The Licensee operates a bioremediation facility to treat hydrocarbon contaminated soils from within the Premises. As the bioremediation facility does not accept liquid waste from outside the Premises it does not trigger a category under Schedule 1 of the EP Regulations.

E mission Description

Emission: Leachate/runoff from the bioremediation facility containing elevated concentrations of hydrocarbons and heavy metals.

Impact: Contamination of surrounding land with hydrocarbons. Potential for migration to surface water drainage systems in times of high rainfall. Potential impacts to the Millstream Water Reserve.

Controls: The bioremediation treatment cells are lined with HDPE, with a secondary clay liner and a log book is maintained to record date of deposition, material and approximate volume in cubic metres.

R isk Assessment

Consequence: The impact of leachate/runoff from the bioremediation facility will result in minimal onsite impacts. Therefore, the consequence is slight.

Likelihood: Based on the depth to groundwater (50 mbgl) and ephemeral nature of the creek systems in the area and Licensee controls (HDPE liner with secondary clay liner), leachate/runoff impacts from the bioremediation facility will not occur in most circumstances. Therefore, the likelihood of the consequence is unlikely.

Overall Risk Rating: Comparison of the consequence and likelihood ratings described above with the Emissions Risk Matrix (Table 2) determines the overall rating of risk for leachate/runoff from the bioremediation facility to be low.

R egulatory Controls

The Delegated Officer is not applying any regulatory controls on the Licence with respect to the management of the bioremediation facility. The discharge of hydrocarbons to the environment is an unauthorised discharge under the Environmental Protection (Unauthorised Discharges) Regulations 2004. The general provisions of the EP Act with respect to the causing of pollution and environmental harm also apply.

Process limits

The recording and the establishment of limits for process throughputs is included in the Licence through condition 1.2.10. This ensures the Licensee does not exceed the approved throughputs for categories 5, 61, 62 and 73.

Appendix B

Emissions to land including monitoring WWTPs

The Castle/Dally Camp WWTP and Kangi Camp WWTP irrigation areas are 12.5 ha and 16.3 ha in

size, respectively. The irrigation areas are fenced with a 1.2 m high fence around the perimeter, to restrict access. Signs are fitted to all sides of the compounds.

E mission Description

Emission: Treated wastewater from the Castle/Dally Camp WWTP and Kangi WWTP discharged to the designated irrigation area, potentially with elevated concentrations of total nitrogen, total phosphorus, biochemical oxygen demand, total suspended solids and E.Coli.

Impact: Contamination of surrounding land and surface water drainage, potential for eutrophication of surface water due to elevated nutrients, ecosystem disruption and impacts to groundwater.

Controls: Wastewater is treated to a High ERL at the Castle/Dally Camp and both Low ERL and High ERL at the Kangi Camp. Refer also to Appendix A – WWTPs.

Wastewater is treated to the low exposure risk level, as outlined in the Guideline for the Non-potable Uses of Recycled Water in Western Australia.

There are no sensitive wetlands or drainage features in close proximity to the WWTPs irrigation areas. There are minor drainage lines throughout the area, with the closest approximately 170 m from the WWTP. However, these are ephemeral and only flow during significant storm events. The WWTP is located outside the 1 in 100 year floodplain. Groundwater is approximately 40-50 mbgl at the WWTPs.

R isk Assessment

Consequence: The impact from the irrigation of treated wastewater could result in low level onsite impacts and minimal off-site impacts at a local scale. Therefore, the consequence is minor.

Likelihood: Based on the location of the closest drainage line, distance to groundwater and location of the WWTP outside of the 1 in 100 year floodplain, an environmental impact from the irrigation of treated wastewater will not occur in most circumstances. Therefore, the likelihood of the consequence is unlikely.

Overall Risk Rating: Comparison of the consequence and likelihood ratings described above with the Emissions Risk Matrix (Table 2) determines the overall rating of risk for the irrigation of treated wastewater to be medium, subject to regulatory control.

R egulatory Controls

Condition 1.2.3 specifies a limit of 1,178 m3/day for sewage treatment to ensure that the WWTPs operate within the design specifications.

Condition 1.2.4 specifies requirements that need to be met with respect to the irrigation of treated wastewater. These management measures include no irrigation generated runoff, spray drift or discharge beyond the designated irrigation areas, wastewater is evenly distributed over the irrigation area, no soil erosion occurs, irrigation does not occur on land that is waterlogged and a healthy vegetation cover is maintained.

Condition 2.2.1 includes the two irrigation areas as specified emission points to land. During this amendment (December 2018) condition 2.2.1 has been updated to include the size of the irrigation fields 12.5 ha and 16.3 ha respectively for both the Castle/Dally Camp WWTP and Kangi Camp WWTP.

Condition 3.2.1 requires quarterly sampling of the treated wastewater to ensure discharge quality is acceptable. Condition 4.2.1 requires the Licensee to report the monitoring results in the AER and interpret results against the plant design specifications.

BFSF OWS

E mission Description

Emission: Discharge of potentially contaminated treated wastewater from the BFSF OWS.

Impact: Elevated concentrations of TRH in discharge could contaminate soil, impact surface water and groundwater quality; leading to ecosystem disruption.

Controls: There are two OWS located at the BFSF. Treated wastewater from these OWS is discharged, as part of the site stormwater system, into a nearby drainage line.

The OWS have been designed to treat wastewater to achieve a TRH concentration of less than 5 mg/L. Monthly inspections of the systems are carried out to check for the presence of visible hydrocarbon sheen and to ensure that the systems are operating as per manufacturer’s specifications.

The BFSF is located nearly 110 m from the nearest ephemeral surface water drainage line which eventually flows into Fortescue River.

R isk Assessment

Consequence: The impact from the discharge of treated wastewater from the BFSF OWS could result in low level onsite impacts and minimal off-site impacts at a local scale due to the size of the facility and volumes of water that require treatment. Therefore, the consequence is minor.

Likelihood: Based on the location of the closest drainage line, distance to groundwater and that the OWS has been designed to treat wastewater to achieve a TRH concentration less than 5 mg/L, the environmental impact of discharges of treated wastewater from the BFSF OWS will not occur in most circumstances. Therefore, the likelihood of the consequence is unlikely.

Overall Risk Rating: Comparison of the consequence and likelihood ratings described above with the Emissions Risk Matrix (Table 2) determines the overall rating of risk for treated wastewater discharged from the BFSF OWS to be medium, subject to regulatory control.

 Regulatory Controls

Condition 2.2.1 specifies the BFSF OWS treated wastewater discharge as an emission point to land. Condition 2.2.2 has been imposed to specify a limit for TRH in discharge water and monitoring requirements under condition 3.2.1.

Satellite Fuel Facilities OWS

 Emission Description

Emission: Discharge of treated wastewater from the satellite fuel facility and MVWF OWS with elevated concentrations of hydrocarbons.

Impact: Potential contamination of surrounding land, surface water drainage systems and groundwater, possible ecosystem disruption.

Controls: The OWS emission points are located within areas already disturbed for mining and supporting infrastructure. The discharged treated wastewater is contained within the Premises footprint; following release it evaporates or infiltrates.

Discharge points are located at least 50 m from the closest surface water drainage lines and conservation significant vegetation. Surface water drainage lines in the area are episodic, flowing following significant rainfall events.

Groundwater within the Premises area is greater than 10 mbgl.

Potentially contaminated water undergoes treatment prior to discharge to achieve a TRH concentration of less than 15 mg/L.

Further to this, OWS are maintained and regularly inspected by the Licensee to ensure they are functioning in accordance with manufacturer’s specifications. The Licensee also undertakes regular monitoring of the water discharged to validate that the OWS are effectively treating wastewater.

Monitoring results from the 2015 reporting period indicate that TRH concentration in treated water is of sufficient quality.

R isk Assessment

Consequence: The impact from the discharge of treated wastewater from the satellite fuel facilities OWS could result in minimal onsite impacts due to the location of the satellite fuel facilities in already disturbed mining areas. Therefore, the consequence is slight.

Likelihood: Based on the location of the closest drainage line, distance to groundwater and previous treated wastewater monitoring results, impacts to the environment from the discharge of treated wastewater from the satellite fuel facilities OWS will not occur in most circumstances. Therefore, the likelihood of the consequence is unlikely.

Overall Risk Rating: Comparison of the consequence and likelihood ratings described above with the Emissions Risk Matrix (Table 2) determines the overall rating for risk of treated wastewater discharged from the satellite fuel OWS to be low.

 Regulatory Controls

The Delegated Officer is not imposing any additional conditions on the Licence as the offence provisions relating to the causing of pollution and environmental harm outlined in Division 1, Part V of the EP Act apply, as does relevant subsidiary legislation including the Environmental Protection (Unauthorised Discharges) Regulations 2004.

The Premises is also subject to routine compliance inspections by DWER officers during which pollution control equipment, including OWS and the associated emission points will be inspected. The Delegated Officer notes that no issues were identified by DWER officers during the 2016 compliance inspection.

Appendix C

Fugitive dust emissions

E mission Description

Emission: Dust emissions generated from mining related activities such as transport, processing, movement and storage of iron ore.

Impact: Deterioration of local air shed, including potential health impacts to residents. Dust emissions can be harmful to human health and the environment. Elevated total suspended particulates (TSP) can impact ambient environmental quality resulting in amenity impacts and can smother vegetation.

Particulate matter that is less than 10 (PM10) or 2.5 (PM2.5) micrometres in diameter can be drawn deep into the lungs causing human health impacts. The chemical and physical properties of the particles, the size of the particles and the duration of exposure are all factors which may affect human health.

Controls: The following measures are implemented at the Premises to minimise dust emissions:

• Sprays or water trucks are used on ROM stockpiles to control fugitive dust;
• Dust suppression sprays have been fitted to crushers and conveyors;
• Water fogging sprays on the Sizing Hubs;
• Dry baghouse dust collection and ducting connected at all ore transfer points at the Firetail OPF;
• Water sprays are used at transfer points;
• Dust suppression sprays have been fitted to the screen to control fugitive dust emissions from product screening;
• Crushed material stockpiles (fines <12 mm) are sprayed (sprinklers and water trucks);
• In extreme conditions (high wind) the processing at the crushing facilities will cease until conditions improve;
• Water is added to the ore during processing and the final product will contain a moisture content of 6 – 8% moisture;
• A dust suppressant (e.g. Soiltac®) is applied to the stockpiles to prevent windblown dust;
• Dust emissions from the MCF crushed product stockpiles and feed stockpiles is minimised using water sprinklers and a water truck;
• Dust suppression sprinklers are fitted to the MCF to control dust from the grizzly, primary crusher screen, primary crusher, cone crusher and conveyors.

The Licensee has set the following objectives with respect to dust emissions during operation of the Premises:

• That implementation of the Premises does not lead to community complaints regarding dust emissions or their impacts; and
• The operations do not cause National Environmental Protection Management (NEPM) standards to be exceeded at the Premises boundary.

The Licensee has implemented a dust monitoring program for the greater Solomon Project which includes the installation of at least 5 dust monitoring stations (and 1 background station) at varying locations around the Premises to quantify the significance of dust emissions during operation and effectively monitor ambient dust concentrations. PM10 concentrations are monitored continuously from monitors located around the Premises whilst visible dust from the crushing facilities is monitored daily and as the opportunity arises.

The Licensee has prepared an overarching dust management plan which applies across it’s mine and rail sites and continues to implement this plan.

Each of the Licensee’s tenements issued under the Mining Act 1978 for the Premises also include conditions related to dust management. Further to this, conditions of the tenements require that the construction and operation of the project, and measures to protect the environment, are carried out generally in accordance with the submitted Mining Proposals. Each of the submitted Mining Proposals for the Premises has required dust management in accordance with the approved management plan.

R isk Assessment

Consequence: The closest sensitive receptors are Hamersley Gorge and Hamersley Station located 13 km and 33 km from the Premises respectively. The impact of fugitive dust emissions from the Premises would result in minimal impacts to amenity and health at these receptors, based on distance. Therefore, the consequence is slight.

Likelihood: Amenity and health impacts from fugitive dust emissions at these receptors will occur in exceptional circumstances. Therefore, the likelihood of the consequence is rare.

Overall Risk Rating: Comparison of the consequence and likelihood ratings described above with the Emissions Risk Matrix (Table 2) determines the overall rating of risk for fugitive dust emissions to be low.

R egulatory Controls

No specified conditions relating to fugitive dust emissions are imposed on the Licence. The Delegated Officer notes that the Licensee has implemented a range of dust suppression measures across the Premises to manage fugitive dust emissions to minimise environmental and human health impacts. In addition, a comprehensive dust monitoring network has been established by the Licensee to monitor ambient dust concentrations and visible dust from the crushing facilities is monitored daily.

The Delegated Officer also notes the regulation of dust from the Premises is also addressed under mining tenement conditions.

The Premises will be subject to future DWER inspections during which fugitive dust emissions and the effectiveness of existing dust mitigation measures will be assessed. If unreasonable dust emissions are identified, DWER will consider the inclusion of appropriate conditions to regulate dust. The general provisions of the EP Act also apply.

Appendix D

Process Monitoring

Solomon Power Station – Liquid Waste

The Licensee accepts liquid waste from the Solomon Power Station, occupied by TEC Pipe Pty Ltd. This liquid waste comprises of treated wastewater from a reverse osmosis plant, oil water separator and cooling tower blowdown. The treated wastewater is utilised for dust suppression on roads and stockpiles across the Premises.

The Licenses also utilises treated wastewater from the site’s OWS for use in dust suppression. The risk assessment for the BFSF OWS and satellite fuel facilities OWS is detailed in Appendix B.

Normal operation

E mission Description

Emission: Discharge of potentially contaminated treated wastewater to land.

Impact: Potential contamination of surrounding land, surface water drainage systems and groundwater.

Controls: The Licensee monitors the quality of the treated wastewater to ensure the concentration of TDS and TRH are within acceptable levels. In the event that the quality requirements have not been met, the treated wastewater from the Solomon Power Station is diverted to the stockyard drainage pond, where it is diluted until it meets the water quality requirements suitable for discharge.

R isk Assessment

Consequence: The impact from the discharge of treated wastewater from the Solomon Power Station for dust suppression will result in low level onsite impacts and minimal off-site impacts at a local scale. Therefore, the consequence is minor.

Likelihood: Based on the Licensee controls (monitoring of water quality), environmental impacts from the discharge of treated wastewater reused for dust suppression will not occur in most circumstances. Therefore, likelihood of the consequence is unlikely.

Overall Risk Rating: Comparison of the consequence and likelihood ratings described above with the Emissions Risk Matrix (Table 2) determines the overall rating of risk for treated wastewater reused for dust suppression to be medium, subject to regulatory control.

R egulatory Controls

Condition 3.4.1 includes monitoring requirements for the treated wastewater from the OWS (BFSF and satellite fuel facilities) used for dust suppression onsite.

Condition 3.4.1 also includes monitoring requirements for the treated wastewater accepted from the Solomon Power Station. Limits for concentrations of TDS and TRH in treated wastewater discharged apply and the Licensee is required to record the volume of treated wastewater discharged at the Premises.

Abnormal/Emergency situation

 Emission Description

Emission: Potential uncontrolled discharge of treated wastewater from the stockyard storage tanks.

Impact: Potential contamination of surrounding land and groundwater.

Controls: The Licensee stores the treated wastewater in an impermeable storage tank and maintains an operating vertical freeboard of 300 mm.

R isk Assessment

Consequence: The impact to the environment from the overflow of treated wastewater from the storage tanks will result in minimal onsite impacts, as any overflow would be isolated to the immediate area of the tanks and the water is treated. Therefore, the consequence is slight.

Likelihood: Based on the Licensee controls (freeboard), an environmental impact from the overflow of treated wastewater from the storage tanks will not occur in most circumstances. Therefore, the likelihood of the consequence is unlikely.

Overall Risk Rating: Comparison of the consequence and likelihood ratings described above with the Emissions Risk Matrix (Table 2) determines the overall rating of risk to the environment from treated wastewater overflows to be rare.

R egulatory Controls

The Delegated Officer is not imposing any additional conditions on the Licence as the offence provisions relating to the causing of pollution and environmental harm outlined in Division 1, Part V of the EP Act apply, as does relevant subsidiary legislation including the Environmental Protection (Unauthorised Discharges) Regulations 2004.

TSF Decant Line – Stormwater discharge to Kangeenarina Creek

The Licensee has an emergency decant line in place at the TSF to allow for discharge of decant water to Kangeenarina Creek, as a contingency measure during high rainfall events. DWER has assessed the contingency discharge of TSF decant water to Kangeenarina Creek, detailed below.

E mission Description

Emission: Contingency discharge of TSF decant water/stormwater to Kangeenarina Creek during high rainfall events.

Impact: Deterioration of surface water quality and increased turbidity/downstream sedimentation leading to ecosystem disruption. Kangeenarina Creek contains several groundwater fed pools which could be effected. Erosion of creek bed at discharge point.

Controls: The TSF provides sufficient capacity that storm events will generally not result in overtopping of the embankment. The decant line is a contingency measure to allow for discharge of decant water to Kangeenarina Creek, if required.

A contingency bypass pipeline extends past the decant/seepage water storage pond to allow for stormwater from an extreme storm event to be released to Kangeenarina Creek. Rock armouring has been constructed and a stilling basin installed to dissipate the energy of the flow.

Geochemical characterisation of mine waste samples has identified that tailings supernatant produced by the OPFs can be assumed to be geochemically inert and not considered a contaminant risk for surface waters.

The pools immediately downstream of the TSF contingency discharge point are located within the future Solomon mine pit area, and are therefore approved for disturbance under MS 1062. The Licensee has existing obligations under Part IV of the EP Act – MS 1062 condition 10-4 to “continue to implement the Kangeenarina Pools Supplementation Plan – Northern Pools Addendum 600SO- 00018-RP-HY-0003 until notified by the CEO that the plan meets the requirements of conditions 10- 1(3), and 10-1(4)”.

R isk Assessment

Consequence: The impact from the discharge of TSF decant water and stormwater to Kangeenarina Creek could result in midlevel onsite impacts and low level off-site impacts at a local scale due to the geochemical characterisation of the tailings and supernatant water. It is also noted that discharge will only occur during and/or following significant rainfall events; effectively diluting the tailings liquor prior to discharge. Therefore, the consequence is moderate.

Likelihood: Based on the Licensee controls (sediment and erosion control) and infrequent use of the contingency option, impacts to Kangeenarina Creek from the discharge of TSF decant water and stormwater will not occur in most circumstances. Therefore, the likelihood of the consequence is unlikely.

Overall Risk Rating: Comparison of the consequence and likelihood ratings described above with the Emissions Risk Matrix (Table 2) determines the overall rating of risk for the contingency discharge of decant water and stormwater from the TSF during high rainfall events to Kangeenarina Creek to be medium, subject to regulatory control.

R egulatory Controls

Condition 3.4.1 specifies monitoring requirements that need to be implemented when contingency discharge of decant water from the TSF is undertaken during high rainfall events. The results of this monitoring will be reported to DWER via the AER, required under condition 4.2.1.

The Delegated Officer notes that the ambient water quality of the northern pools of Kangeenarina Creek are monitored under the Kangeenarina Pools Supplementation Plan – Northern Pools Addendum 600SO-00018-RP-HY-0003 required under MS 1062. Noting this, conditions relating to the monitoring of the ambient surface water quality of Kangeenarina Creek have not been applied to the Licence.

The contingency discharge point will be inspected during DWER compliance inspections to determine if erosion at the discharge point is occurring.

References