air quality assessment for the skardon river bauxite mine eis · document control deliverable #:...

Air Quality Assessment for the Skardon River Bauxite Mine EIS

Prepared for:

Gulf Alumina Ltd

July 2015

Final

Prepared by:

Katestone Environmental Pty Ltd ABN 92 097 270 276 Ground Floor, 16 Marie Street | PO Box 2217 Milton, Brisbane, Queensland, 4064, Australia

www.katestone.com.au [email protected]

Ph +61 7 3369 3699 Fax +61 7 3369 1966

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This document, electronic files or software are the copyright property of Katestone Environmental Pty. Ltd. and the information contained therein is solely for the use of the authorised recipient and may not be used, copied or reproduced in whole or part for any purpose without the prior written authority of Katestone Environmental Pty. Ltd. Katestone Environmental Pty. Ltd. makes no representation, undertakes no duty and accepts no responsibility to any third party who may use or rely upon this document, electronic files or software or the information contained therein.

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Document Control

Deliverable #: D14059-6

Title: Air Quality Assessment for the Skardon River Bauxite Mine EIS

Version: 1.1 (Final)

Client: Gulf Alumina Ltd

Document reference: D14059-6 Skardon Mine Air Quality Report v1.1.docx

Prepared by: Andrew Vernon, Michael Burchill and Sarah Richardson

Reviewed by: Natalie Shaw and Simon Welchman

Approved by:

Natalie Shaw

06/07/2015

http://katestone.com.au/disclaimer/

Katestone Environmental Pty Ltd D14059-6 Gulf Alumina Ltd Air Quality Assessment for the Skardon River Bauxite Mine EIS – Final

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Contents Executive Summary ............................................................................................................................................................ iv 1. Introduction .......................................................................................................................................................... 1

1.1 Background .............................................................................................................................................................. 1 1.2 The Project ................................................................................................................................................................ 1 1.3 Scope of work .......................................................................................................................................................... 3

2. Considerations for assessing air quality ............................................................................................................ 4 2.1 Air pollutants emitted from the Project ................................................................................................................ 4 2.2 Legislative Framework for Air Quality ................................................................................................................... 4 2.3 Environmental Authority ......................................................................................................................................... 6 2.4 Existing Conditions ................................................................................................................................................... 6

2.4.1 EHP Model Mining Conditions ............................................................................................................... 6 3. Existing Environment ............................................................................................................................................ 8

3.1 Local terrain and land-use ..................................................................................................................................... 8 3.2 Sensitive receptors ................................................................................................................................................... 8 3.3 Meteorology ............................................................................................................................................................. 9

3.3.1 Temperature ............................................................................................................................................ 9 3.3.2 Rainfall .................................................................................................................................................... 10 3.3.3 Relative humidity................................................................................................................................... 11 3.3.4 Surface Atmospheric Pressure ............................................................................................................ 12 3.3.5 Wind speed and wind direction ......................................................................................................... 13 3.3.6 Frequency of thunderstorms, lighting and tropical cyclones ........................................................ 15

3.4 Existing air quality ................................................................................................................................................... 15 3.4.1 Proposed bauxite projects .................................................................................................................. 16 3.4.2 Bauxite Hills Project ............................................................................................................................... 16 3.4.3 South of Embley Project ....................................................................................................................... 16 3.4.4 Hey Point Bauxite Project ..................................................................................................................... 16

4. Emissions Inventory............................................................................................................................................. 17 5. Air Quality Impact Assessment ........................................................................................................................ 18

5.1 South of Embley Air Quality Assessment ............................................................................................................ 18 5.2 Project Impact ....................................................................................................................................................... 19

5.2.1 Sensitive Receptors - Mapoon ............................................................................................................ 19 5.2.2 Sensitive Receptor – Bauxite Hills Project Accommodation Camp .............................................. 19 5.2.3 Impacts on Vegetation ........................................................................................................................ 20

6. Project Controls/ Mitigation Measures ........................................................................................................... 22 7. References .......................................................................................................................................................... 23 Appendix A Methodology for calculating dust emissions from individual emission sources ....................... 24

A1 Conveyors ............................................................................................................................................................... 24 A2 Scrapers – topsoil/subsoil ...................................................................................................................................... 24 A3 Material handling – Topsoil/Subsoil ..................................................................................................................... 25 A4 Material handling – Bauxite ................................................................................................................................. 25 A5 Bulldozing ................................................................................................................................................................ 26 A6 Wind erosion of active stockpiles ........................................................................................................................ 26 A7 Wind erosion of exposed areas ........................................................................................................................... 27 A8 Wheel generated dust from unpaved haul roads ........................................................................................... 27 A9 Crushing .................................................................................................................................................................. 28 A10 Transhipping ........................................................................................................................................................... 28

Tables Table 1 Ambient air quality objectives (Air EPP) ................................................................................................................... 5 Table 2 Summary of BoM Weipa monitoring parameters used in the climate summary .............................................. 9 Table 3 Average daily temperature at the Weipa Airport monitoring station (1992 to 2014) ...................................... 9 Table 4 Minimum, average and maximum monthly rainfall at the Weipa Airport monitoring station for the

period 1990 to 2015 ................................................................................................................................................... 10 Table 5 Summary of the Skardon River Bauxite Project Dust Emissions Inventory .......................................................... 17 Table 6 Summary of South of Embley Dust Emissions Inventory ........................................................................................ 18

Figures Figure 1 Location of Skardon River Bauxite Mine Project ..................................................................................................... 2 Figure 2 Location of sensitive receptors .................................................................................................................................. 8


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Figure 3 Mean daily minimum and maximum temperature at Weipa Airport (°C) ...................................................... 10 Figure 4 Minimum, average and maximum monthly rainfall recorded at Weipa Airport monitoring station for

the 1990 to 2015 period (mm/month) .................................................................................................................... 11 Figure 5 Relative humidity at 9am (1992 to 2011) and 3pm (1992 to 2010) by month at Weipa Airport (%) ............. 12 Figure 6 Monthly average surface pressure at Weipa Airport for October 1995 to February 2015............................. 13 Figure 7 Annual wind rose of wind speed (m/s) and wind direction (°) recorded at Weipa Airport monitoring

station during January 1995 to December 2014 .................................................................................................. 14 Figure 8 Seasonal wind rose of wind speed (m/s) and wind direction (°) recorded at Weipa Airport

monitoring station during January 1995 to December 2014 .............................................................................. 14 Figure 9 Diurnal wind rose of wind speed (m/s) and wind direction (°) recorded at Weipa Airport monitoring

station during January 1995 to December 2014 .................................................................................................. 15 Figure 10 Project map (left) showing locations of activities and buffer distances from the edge of the mining

lease. Activity area colours correspond to the pie chart (right) showing the distribution of estimated PM10 emissions. ........................................................................................................................................................... 21


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Glossary

Term Definition Mt Megatonne (1,000,000 tonnes)

Mtpa Million tonnes per annum °C degrees Celsius km kilometre

km/h kilometre per hour t tonne

Nomenclature TSP Total Suspended Particles PM10 particulate matter with a diameter less than 10 micrometres PM2.5 particulate matter with a diameter less than 2.5 micrometres

Abbreviations Air EPP Environmental Protection (Air) Policy 2008

DSO Direct Shipping Ore EA Environmental Authority EF Emission Factor

EHP Department of Environment and Heritage Protection (Qld) EIS Environmental Impact Statement ML Mining Lease NPI National Pollutant Inventory

PoO Plan of Operation


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EXECUTIVE SUMMARY

Katestone Environmental Pty Ltd (Katestone) was commissioned by Gulf Alumina Ltd (Gulf) to complete an Air Quality Assessment of the Skardon River Bauxite Mine (the Project) for inclusion within an Environmental Impact Statement (EIS).

The Project involves the construction and operation of an open cut bauxite mine on the western Cape York Peninsula, 80km north of the town of Weipa. The Project involves mining a bauxite ore body of around 50 million tonnes (Mt) and is anticipated to initially produce 3 million tonnes per annum (Mtpa) of bauxite, rising to 5 Mtpa subject to market conditions.

The bauxite ore will be mined and transported via haul roads to a crushing and stockpile facility at the Port of Skardon River. The bauxite product will be loaded onto barges and transported to bulk carriers in deep water beyond the mouth of the river for export. The Project’s life expectancy is 10 years.

The most important air pollutant emitted from the Project will particulate matter (dust). The Project activities that contribute to the largest emissions of dust include:

• Bauxite mining (excavation) • Bauxite material handling (loading trucks and dumping at stockpile area) • Haul truck movements of topsoil, subsoil and bauxite on unpaved roads • Barge loading of bauxite at port • Ship loading of bauxite at sea

The location of the Project is relatively remote. The nearest sensitive receptor is located approximately 11 km southwest of the nearest active mine area (pit) and 30 km from the port facilities on the Skardon River. The Mapoon town is approximately 16 km southwest of the nearest active mine area. The meteorological conditions in the region have been inferred from data measured at Weipa Airport and show a dominance of winds from an east to southeast direction. Therefore, the most likely areas to be impacted by emissions from the Project would be in a westerly to northwesterly direction.

A dust emissions inventory was calculated for the Project based on the following operational parameters, information and assumptions:

• 5 Mtpa bauxite throughput (maximum capacity) • 0.9 Mtpa topsoil and 2.3 Mtpa subsoil (maximum combined throughput, planned to occur in 2023) • 11 km average product haul • A maximum cleared area of 717 ha (planned to occur in 2017 and 2021)

The following possible options for bauxite haulage have been considered as part of the assessment:

• High speed dump trucks with 70 t payload • Dump trucks with 200 t payload • Road trains with 350 t payload

Air quality impacts for the Project have been inferred from an approved air quality assessment report for a mining activity that has a similar dust emissions inventory, the South of Embley Project located in western Cape York to the south of Weipa. The South of Embley Project EIS was approved in 2012 and included a dispersion modeling study of dust emissions from a proposed 50 Mtpa bauxite mine. The dispersion modelling study indicated that air quality impacts would not occur at distances greater than 5 km from mining areas.

Using the air quality results from the South of Embley EIS it can be inferred that the air quality impacts from the Project would be low at the nearest sensitive receptors. This is due to the large buffer distance of 11 km and the


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fact that the predominant prevailing wind direction is from the east to southeast.

The Bauxite Hills Project is a 2 Mtpa bauxite mine proposed in the area adjacent to Gulf's Project and focused around the Skardon River. Assuming the Bauxite Hills Project has similar activities to Gulf's Project and is less than half the size (2 Mtpa), air quality impacts are assumed not to occur beyond 2.5 km from their mining activities. Conservatively, cumulative air impacts are therefore not predicted to occur beyond 7.5 km from both projects and therefore impacts at the nearest sensitive receptors would be low.

Notwithstanding the low risk to air quality from the Project, operational management practices will be implemented to ensure ongoing environmental commitments to minimise dust emissions and include the use of water on haul roads and stockpiles and the progressive rehabilitation of mined areas.


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1. INTRODUCTION

Gulf Alumina Ltd (Gulf) proposes to establish the Skardon River Bauxite Mine (the Project), a bauxite mine located in Cape York in Northern Queensland with the capacity to produce up to 5 million tonne per annum (Mtpa).

Katestone Environmental Pty Ltd (Katestone) has been commissioned by Gulf to complete an Air Quality Assessment for inclusion within an Environmental Impact Statement (EIS) for the Project.

1.1 Background

Gulf gained full ownership of the three Skardon River mining leases (ML) from ACC Ecominerals in January 2012 and is the sole holder of the existing Environmental Authority (EA) EPML 00967013 which permits mining and processing of kaolin, brick clay and quartz within MLs 40082, 40069 and 6025.

The current EA comes under the Environmental Management Overview Strategy (EMOS) submitted to Queensland Mines and Energy in August 1998, by the original owner of the Skardon River Mine, Australian Kaolin Ltd (AKL). AKL went into liquidation in July 2010 and terminated operations in October 2011.

A Plan of Operations (PoO) for the Skardon River Mine was submitted by Gulf in accordance with the EA EPML 00967013 for the 12 month period from February 2015 to February 2016. The PoO covers the decommissioned kaolin mining and processing operation under care and maintenance, processing plant decommissioning and includes Gulf’s rehabilitation plan for the former kaolin mine.

The kaolin mine decommissioning and rehabilitation does not form part of the Skardon River Bauxite Mine Project EIS as these activities are already approved under the existing EA and PoO. A new EA will be sought for the Project.

1.2 The Project

The Project involves the construction and operation of an open cut bauxite mine in Western Cape York Peninsula. The Project involves mining a bauxite ore body of around 50 million tonnes (Mt) and is anticipated to initially produce 3 Mtpa of bauxite suitable as direct shipping ore (DSO), rising to 5 Mtpa subject to market conditions. DSO does not require beneficiation of the bauxite and hence beneficiation and associated tailings management are not part of the Project.

The bauxite ore will be mined and transported via existing, upgraded haul roads to a crushing and stockpile facility at the Port of Skardon River. The bauxite product will be loaded onto barges and transported to bulk carriers in deep water beyond the mouth of the river for export. Construction is planned to commence in early 2016 with bauxite mining and shipping in late 2016 / early 2017 (excluding the wet season period). The Project life is expected to be 10 years. A map of the project is shown in Figure 1.


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Figure 1 Location of Skardon River Bauxite Mine Project


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1.3 Scope of work

This study summarises the aspects of the Project that may result in emissions to the atmosphere, as well as the legislation, policies and guidelines that are relevant to the assessment and management of air emissions in Queensland and Australia.

The objective of this assessment is to:

• Define the air quality regulatory requirements relevant to the Project • Describe the existing environment in the region, including:

o Terrain features o Dominant land-uses o Climate and meteorology. o Sensitive receptors o Existing air quality

• Detail an inventory of air pollutant emissions associated with the Project • Evaluate and compare levels of air pollutants as a result of the Project with other similar projects in the

region • Compare levels with the relevant air quality regulatory requirements • Consider the cumulative impact of the Project with other proposed projects in the region • Describe the mitigation and management procedures for the Project

This report describes the methods and findings of the assessment of air quality associated with the construction and mining operations of the Project.


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2. CONSIDERATIONS FOR ASSESSING AIR QUALITY

2.1 Air pollutants emitted from the Project

The most important air pollutant emitted from the Project will particulate matter (dust). Elevated levels of dust have the potential to cause adverse impacts on the amenity and health of people living in the vicinity. Emissions of dust from the Project may occur during both the construction and operational phase. The Project activities that may contribute to emissions of dust include:

• Land clearing

• Topsoil stripping

• Topsoil and subsoil handling (loading trucks and dumping at stockpile area)

• Bauxite mining (excavation)

• Bauxite material handling (loading trucks and dumping at stockpile area)

• Haul truck movements of topsoil, subsoil and bauxite on unpaved roads

• Stockpiling of topsoil, subsoil and bauxite (wind erosion)

• Barge loading of bauxite at Port

• Ship loading of bauxite at sea.

Fleet vehicle exhaust emissions will also be a source of air pollutant emissions. The combustion of fuel (diesel) in vehicles will result in emissions of oxides of nitrogen (NOx), carbon monoxide (CO), particulate matter, sulfur dioxide (SO2) and carbon dioxide (CO2). Trace amounts of hydrocarbons will also be present in the vehicle exhaust. The air emissions from the fleet vehicles would be transient and far smaller than emissions of particulate matter from mining activities and have not been considered further in this assessment.

A complete inventory of significant sources of air pollutant emissions for the Project is detailed in Section 4.

2.2 Legislative Framework for Air Quality

The Environmental Protection Act 1994 (EP Act) provides for the management of the air environment in Queensland. The EP Act gives the Department of Environment and Heritage Protection (EHP) the power to create Environmental Protection Policies that identify, and aim to protect, environmental values of the atmosphere that are conducive to the health and well-being of humans and biological integrity. The Environmental Protection (Air) Policy (Air EPP) was made under the EP Act and gazetted in 1997; the Air EPP was revised and reissued in 2008.

The objective of the Air EPP is:

...to identify the environmental values of the air environment to be enhanced or protected and to achieve the objective of the Environmental Protection Act 1994, i.e. ecologically sustainable development.

The environmental values to be enhanced or protected under the Air EPP are the qualities of the environment that are conducive to:

• protecting health and biodiversity of ecosystems;

• human health and wellbeing;


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• protecting the aesthetics of the environment, including the appearance of building structures and other property; and

• protecting agricultural use of the environment.

The administering authority must consider the requirements of the Air EPP when it decides an application for an environmental authority, amendment of a licence or approval of a draft environmental management plan. Schedule 1 of the Air EPP specifies air quality indicators and objectives for approximately 93 contaminants that may be present in the air environment.

The Air EPP air quality objectives relevant to the key air pollutants that may be generated from the Project are presented in Table 1.

Table 1 Ambient air quality objectives (Air EPP)

Pollutant Environmental value Averaging period Air quality objective (µg/m³)

Number of days of exceedance

allowed per year

TSP Health and wellbeing Annual 90 N/A

PM10 Health and wellbeing 24-hour 50 5

PM2.5 Health and wellbeing 24-hour 25 N/A

1-year 8 N/A

Dust deposition* Nuisance Maximum monthly average 120

mg/m2/day N/A

Note: * Dust deposition is not specified in the Air EPP. The objective used here has been reproduced from the EHP Guidelines for Model Mining Conditions (EML944 - version 5)

There is no statutory limit for protecting health and biodiversity of ecosystems for key air pollutants (dust) generated from the Project. EHP provides design guidance for dust deposition for the avoidance of dust nuisance, which is related to human perception. The effect of dusts on vegetation is principally through interception of light by leaves and the consequential effects on the rates of photosynthesis and plant health and growth. However, there are no prescribed assessment criteria for dust loads on vegetation associated with reduced physiological activity. For this assessment the dust deposition nuisance guideline has been adopted to determine impacts on vegetation.

Also relevant is the EHP's Application requirements for activities with impacts to air, which outlines the information to be provided to EHP as part of the application process for environmentally relevant activities and how the information is used. This outlines how the proposed activity will be assessed by comparison with the requirements stipulated in the EP Act. In particular, this requires an application to include, if applicable:

• Description of the site and surrounding areas, including topography, prevailing winds and ambient air quality

• Identification of any nearby sensitive places must be identified and assessed appropriately

• Identification and evaluation of possible impacts on air quality

• Proposed management

This air quality assessment has been conducted in accordance with these requirements.


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2.3 Environmental Authority

2.4 Existing Conditions

Gulf is the sole holder of the existing EA EPML 00967013 which permits mining and processing of Kaolin, brick clay and quartz within MLs 40082, 40069 and 6025 but the Kaolin mine has been under care and maintenance since 2011. A Plan of Operations (PoO) for the Skardon River Mine was submitted by Gulf in accordance with the EA EPML 00967013 for the 12 month period from February 2015 to February 2016. The PoO covers Gulf's decommissioning and rehabilitation plan of the existing kaolin mining and processing operation currently under care and maintenance. Following submission of the Project EIS a new EA will be issued by EHP for the Project and is likely to reflect the EHP Guidelines for Model Mining Conditions (EML944 - version 5).

2.4.1 EHP Model Mining Conditions

EHP has developed model conditions to form general environmental protection commitments and EA conditions for mining activities and was released in November 2014 (EML944 - version 5). The conditions that relate to air pollutants that may be generated from the Project (particulate matter - air quality) are detailed in Schedule B (Air) and are reproduced below.

“Schedule B – Air

Dust and particulate matter monitoring

(B4) The Proponent shall ensure that all reasonable and feasible avoidance and mitigation measures are employed so that the dust and particulate matter emissions generated by the mining activities do not cause exceedances of the following levels when measured at any sensitive or commercial place:

a) Dust deposition of 120 milligrams per square metre per day, averaged over one month, when monitored in accordance with the most recent version of Australian Standard AS3580.10.1 Methods for sampling and analysis of ambient air—Determination of particulate matter—Deposited matter – Gravimetric method.

b)* A concentration of particulate matter with an aerodynamic diameter of less than 10 micrometres (PM10) suspended in the atmosphere of 50 micrograms per cubic metre over a 24-hour averaging time, for no more than five exceedances recorded each year, when monitored in accordance with the most recent version of either:

1. Australian Standard AS3580.9.6 Methods for sampling and analysis of ambient air—Determination of suspended particulate matter—PM10 high volume sampler with size-selective inlet – Gravimetric method, or

2. Australian Standard AS3580.9.9 Methods for sampling and analysis of ambient air—Determination of suspended particulate matter—PM10 low volume sampler—Gravimetric method.

c)** A concentration of particulate matter with an aerodynamic diameter of less than 2.5 micrometres (PM2.5) suspended in the atmosphere of 25 micrograms per cubic metre over a 24-hour averaging time, when monitored in accordance with the most recent version of AS/NZS3580.9.10 Methods for sampling and analysis of ambient air—Determination of suspended particulate matter—PM (sub)2.5(/sub) low volume sampler—Gravimetric method.

d) A concentration of particulate matter suspended in the atmosphere of 90 micrograms per cubic metre over a 1 year averaging time, when monitored in accordance with the most recent version of AS/NZS3580.9.3:2003 Methods for sampling and analysis of ambient air—


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Determination of suspended particulate matter—Total suspended particulate matter (TSP)—High volume sampler gravimetric method.

* Explanatory note - The five exceedances for the PM10 standard outlined in B4(b) were introduced to account for the impact of bushfires, dust storms and fuel burning for fire management purposes. The five exceedances are in essence arbitrary in that the number was chosen as it is difficult to determine exactly the number of times these events may happen in any one year. More than five exceedances as a result of one or more of these events would not be considered to be a breach of condition.

** Explanatory note - Sources of PM2.5 are primarily from combustion sources and PM2.5 is unlikely to be elevated if significant combustion sources are not present. Condition B4(c) will therefore only be required if there is a significant source of air emissions from combustion sources


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3. EXISTING ENVIRONMENT

3.1 Local terrain and land-use

The Project is located approximately 90 km north of Weipa on the western Cape York Peninsula in Far North Queensland. The Project site (MLs 40082, 40069 and 6025) is located on land between the Ducie River to the south and the Skardon River to the north.

The terrain of the region is relatively flat and comprised of coastal plains and riverbeds typical of Cape York. Larger terrain features that can influence the meteorology are not prevalent in this area. The predominant land use in the Project region is tropical scrublands, the Gulf of Carpentaria (to the west) and a number of rivers and creek beds.

3.2 Sensitive receptors

The closest township to the Project ML is Mapoon, approximately 16 km southwest of the southernmost ML (6025) and 34 km southwest of the Port facilities on the Skardon River. A number of isolated homesteads are located along the coastline between Cullen Point and Mapoon. Cullen Point is approximately 10 km southwest of ML 6025 and the nearest sensitive receptor is 11 km southwest of the nearest active mine area and 30 km from the Port of Skardon River.

Cape Alumina’s proposed Bauxite Hills Project's accommodation camp is the only other potential sensitive receptor. However, the location of this accommodation camp is unknown at this stage.

A map of the known sensitive receptor locations is presented in Figure 2.

Figure 2 Location of sensitive receptors


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3.3 Meteorology

Twenty five years of meteorological monitoring data (1990 to 2015) measured at the Bureau of Meteorology (BoM) Weipa Airport station, 80 km south of the Project site, have been used to characterise the long term climate of the Skardon River region. The data at the BoM Weipa Airport station is expected to be representative of the Project site due to the relative proximity of locations, similarity in surrounding terrain and the coastal location. A summary of the measured meteorological parameters is provided in Table 2.

Table 2 Summary of BoM Weipa monitoring parameters used in the climate summary

Site Data format Parameters Record period

Weipa Airport

Climate statistics available on the Bureau of Meteorology website (www.bom.gov.au)

Temperature 1992 to 2014

Solar exposure 1990 to 2014

Rainfall 1990 to 2015

Relative humidity 9am 1992 to 2011

Relative humidity 3pm 1992 to 2010

1-hour average data Wind speed and wind direction January 1996 to December 2014

Monthly average data Surface pressure October 1995 to February 2015

Weipa Annual averages maps available on the Bureau of Meteorology website (www.bom.gov.au)

Thunderstorm frequency 1990 to 1999

Lightning frequency 1995 to 2002

Tropical cyclone frequency 1906 to 2006

3.3.1 Temperature

The average daily minimum and maximum temperature at Weipa Airport between 1992 and 2014 is presented in Table 2 for each season, and graphically for each month in Figure 3. The summary identifies a seasonal temperature profile typical of the tropical Queensland climate, with hot spring and summer months of October through December and cooler autumn and winter months of May through September. As shown in Table 3, during the data period (1992 to 2014) the temperature extremes included a minimum daily average temperature of 10.2°C (29 June 2007) and a maximum daily average temperature of 39.2°C (20 November 2014).

Table 3 Average daily temperature at the Weipa Airport monitoring station (1992 to 2014)

Parameter Season

Spring Summer Autumn Winter

Average daily minimum temperature (°C) 21.6 24.2 22.6 19.2 Average daily maximum temperature (°C) 35.2 32.4 31.9 31.4

Lowest daily temperature (°C) 14.7 20.5 12.7 10.2 Highest daily temperature (°C) 39.2 38.7 35.3 35.9


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Figure 3 Mean daily minimum and maximum temperature at Weipa Airport (°C)

3.3.2 Rainfall

The minimum, average and maximum monthly rainfall recorded at the Weipa Airport monitoring site for the 1990 to 2015 period is presented in Figure 4 (BoM website, as accessed February 2015). The total annual average rainfall at Weipa Airport was 2,001 mm/year while the maximum total annual rainfall was 2,719 mm recorded in 1996. The data are consistent with a tropical climate, with the wetter summer months of December through to March, and the dryer winter months of May through to October. In particular, the months of December, January, February and March account for, on average, 87% of the annual rainfall. It should be noted that the Project will not operate during the wet season (generally 3 months between December and March).

Table 4 Minimum, average and maximum monthly rainfall at the Weipa Airport monitoring station for the period 1990 to 2015

Month Minimum (mm) Maximum (mm) Average (mm) Monthly rainfall distribution (%)

January 0 909.8 481.9 24.5 February 127.2 932.6 544.6 27.7 March 149 986.4 409 20.8 April 0.2 328 99.4 5.1 May 0 137.8 17.7 0.9 June 0 23.6 3.9 0.2 July 0 9.2 1.5 0.1 August 0 59.2 5.8 0.3


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Month Minimum (mm) Maximum (mm) Average (mm) Monthly rainfall distribution (%)

September 0 16.6 1.3 0.1 October 0 132.6 22.7 1.2 November 4.2 339.6 109.2 5.5 December 59.2 876 270.8 13.8

Figure 4 Minimum, average and maximum monthly rainfall recorded at Weipa Airport monitoring station for the 1990 to 2015 period (mm/month)

3.3.3 Relative humidity

The monthly average relative humidity at 9am and 3pm at Weipa Airport is presented in Figure 5 for the period from 1992 to 2011 (9am) and to 2010 (3pm).

The figure shows that the annual trend in the relative humidity at 9am is similar to the trend at 3pm, with the monthly average relative humidity showing high levels of humidity during the summer months of December through to March compared to the drier months of August through November.


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Figure 5 Relative humidity at 9am (1992 to 2011) and 3pm (1992 to 2010) by month at Weipa Airport (%)

3.3.4 Surface Atmospheric Pressure

The monthly average surface pressure at Weipa Airport is presented in Figure 6. The annual pattern of peaks and troughs in the monthly average pressure field indicates that the month of January is generally dominated by low pressure features that are typically associated with wetter summer conditions, while the month of July is generally dominated by high pressure features that are typically associated with clear, drier conditions.


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Figure 6 Monthly average surface pressure at Weipa Airport for October 1995 to February 2015

3.3.5 Wind speed and wind direction

Wind speed and direction are important parameters for the transport and dispersion of air pollutants, with the proximity to the coastline and the local terrain features providing a number of complexities in the flow of winds across the region.

The annual, seasonal and diurnal wind roses for the 1-hour average measurements of wind speed and wind direction from the Weipa Airport monitoring site for the period 1 January 1995 to 31 December 2014 presented in Figure 7, Figure 8 and Figure 9 respectively.

The Weipa Airport site is dominated by winds from the east to southeast, with approximately 65% of the annual winds recorded from these sectors. Winds from other sectors do not occur for more than 10% of the time e.g. winds from the west occur for 6% of the time. The annual wind rose indicates that the air pollutant emissions released into the atmosphere would generally be transported to the west and northwest.

The seasonal pattern of winds at the Weipa airport show the dominance of the east to south-easterly winds, especially in autumn, winter and spring. Summer winds are more distributed between east to west winds with few winds occurring from the southwest.

The diurnal winds at Weipa Airport show light winds from the east to southeast between midnight and 6 am, increasing to stronger winds from the same direction between 6 am and midday. Strong winds continue from the east to southeast during the afternoon (midday to 6pm) and then decrease in speed from 6pm to midnight. A relatively strong west wind also occurs during the afternoon (indicating a sea breeze).


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Figure 7 Annual wind rose of wind speed (m/s) and wind direction (°) recorded at Weipa Airport monitoring station during January 1995 to December 2014

Figure 8 Seasonal wind rose of wind speed (m/s) and wind direction (°) recorded at Weipa Airport monitoring station during January 1995 to December 2014


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Figure 9 Diurnal wind rose of wind speed (m/s) and wind direction (°) recorded at Weipa Airport monitoring station during January 1995 to December 2014

3.3.6 Frequency of thunderstorms, lighting and tropical cyclones

The Bureau of Meteorology reports the following frequencies of thunder, lightning and cyclones in the Weipa region:

• Fifty days of thunderstorms per year (based on ten years of data from 1990 – 1999)

• Two to three ground strikes of lightning per square kilometre per year (based on approximately eight years of data, 1995 to 2002)

• For 101 years from 1906 to 2006:

o 14 tropical cyclones within 50 kilometres of Weipa

o 25 tropical cyclones within 100 kilometres of Weipa

3.4 Existing air quality

There are no air quality monitoring stations at the Project site or at the nearest town of Mapoon. The air quality at the Project site would be dominated by natural sources of wind blown dust from exposed ground, particles generated from bushfires and salt spray particles from the Gulf of Carpentaria. The former kaolin mine would have been a source of dust when it was operating but has been under care and maintenance for a number of years.

The largest source of anthropogenic dust in the region is the existing bauxite mine at Weipa, operated by Rio Tinto Alcan, and 80 km from the Project site. The Weipa bauxite mine is a well established operation. In 2012 the Weipa mine shipped 23.1 Mt of product (RTA, 2015). The Weipa mine includes two mine areas, directly to


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the east and north of the town, as well as two beneficiation plants and associated transport and shiploading facilities.

3.4.1 Proposed bauxite projects

There are a number proposed bauxite mining projects in the region that could contribute to air quality levels in the future. The Bauxite Hills Project is proposed to be located on MLs adjacent to the Project in the Skardon River region. There are also two projects proposed to the south of Weipa; the South of Embley Project and the Hey Point Bauxite Project. The following sections provide a brief summary of each of the proposed projects.

3.4.2 Bauxite Hills Project

Cape Alumina is currently in the approvals phase for the Bauxite Hills Project, a 2 Mtpa bauxite mine located within tenements to the south of the Skardon River and adjacent to the Gulf Project (see Figure 1). The Bauxite Hills Project lifetime is expected to be approximately 20 years. The mining methods and shiploading methods will be similar to the Gulf Project.

The environmental assessment for the Bauxite Hills Project is currently being completed and is expected to released by the end of 2015. Therefore, specific information on the air quality impact from the Bauxite Hills Project cannot be determined at this stage. However, it is likely that emissions will be of a similar nature to Gulf’s Project. If approved, the Bauxite Hills Project accommodation camp would be the nearest sensitive receptor to the Project but at this stage the location of the camp is unknown.

3.4.3 South of Embley Project

The South of Embley Project is an approved 50 Mtpa bauxite mine located to the south of Weipa. An EIS for the South of Embley Project (Rio Tinto Alcan, 2012 and 2013) was approved by the State Government in 2012 and by the Commonwealth in 2013. The South of Embley Project EIS stated that air quality impacts were not predicted to occur at distances greater than 5 km from mining areas.

3.4.4 Hey Point Bauxite Project

The Hey Point Bauxite Project is a 1.6 Mtpa bauxite mine expected to operate for three to four years. The Hey Point Project is located approximately 10 km south of Weipa and 5 km south of the community of Napranum. A site specific application for an Environmental Authority for the Hey Point Bauxite Project was released in 2014 (MET Serve, 2014). The report application concluded that the risk of air quality impacts at the nearest receptors 5 km away was low.


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4. EMISSIONS INVENTORY

Emissions to the atmosphere are likely to be produced during the construction and operation of the Project. Dust emissions will be generated through clearing of land and the handling and transportation of topsoil, subsoil and bauxite. Wind erosion of exposed areas, including cleared areas and stockpiles, will also generate dust emissions. Dust emissions associated with construction activities will be lower than operational emissions and, consequently, construction emissions have not been explicitly quantified.

The Project is expected to operate for 10 years with a peak extraction rate of 5 Mtpa of bauxite. Beneficiation of the bauxite is not required and hence beneficiation and associated tailings management are not part of the Project. This assessment has estimated the dust emissions for a worst case year of the Project based on the following information and assumptions:

• 5 Mtpa bauxite throughput (maximum capacity) • 0.9 Mtpa topsoil and 2.3 Mtpa subsoil (maximum combined throughput, planned to occur in 2023) • 11 km average product haul • A maximum cleared area of 717 ha (planned to occur in 2017 and 2021)

The following possible options for bauxite haulage have been considered as part of the assessment:

• High speed dump trucks with 70 t payload • Dump trucks with 200 t payload • Road trains with 350 t payload

Dust emissions from the Project were calculated using emission factors from the National Pollutant Inventory (NPI) Emission Estimation Technique (EET) Manual for Mining (NPI, 2012) and the US EPA AP42 documents. A detailed list of the emission factors, activity rates and assumptions is included in Appendix A. The estimated annual emission rate for each set of activities is shown in Table 5 along with location of activities. The table shows that handling of bauxite represents the greatest proportion of emissions, followed by haulage. The choice of haul option changes the total emission rate by less than 10%.

Table 5 Summary of the Skardon River Bauxite Project Dust Emissions Inventory

Activity Location Estimated annual dust emission rate (tpa)

TSP PM10 PM2.5 Topsoil/subsoil excavation & handling

Active mining areas 102 28 10

Topsoil/subsoil stockpile wind erosion Exposed areas 296 148 22

Topsoil/subsoil haul Active mining areas 120 34 3

Bauxite excavation Active mining areas 3,208 1,465 237

Bauxite stockpile wind erosion Processing area 394 197 30

Bauxite haul (range) Haul roads 727 - 2,041 207 - 582 21 - 58 Bauxite handling - including processing area

Processing area 8,005 3,387 577

Wind erosion - exposed area Exposed areas 366 183 27

Shiploading Transhipper 1,800 851 129

Total 15,017 - 16,330 6,500 - 6,874 1,056 - 1,094


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5. AIR QUALITY IMPACT ASSESSMENT

This section describes similar projects that have been approved in the region (South of Embley EIS) and draws conclusions about the necessary buffer required between mining activities and sensitive receptors in and near Mapoon that would result in a low air quality risk. This buffer is then applied to the Project and a determination of air quality risks is made. Due to the very low risk of air quality impacts from the Project, no dispersion modelling was conducted.

5.1 South of Embley Air Quality Assessment

The South of Embley Project EIS (Rio Tinto Alcan, 2012 and 2013) has been approved by the State and Commonwealth Governments and the air quality assessment has been used in this assessment to determine air quality risks. A comparison of the magnitudes of the projects shows that the production rate of the South of Embley Project is ten times larger (50 Mtpa) than the Project (5 Mtpa maximum).

Table 6 presents a summary of the emissions inventory detailed in the South of Embley Project EIS Air Quality Assessment (EIS Volume 2 Chapter 9).

Table 6 Summary of South of Embley Dust Emissions Inventory

Activity Estimated annual dust emission rate (tpa)

TSP PM10 PM2.5

Excavator on subsoil 76 36 4

Excavator on bauxite 76 36 4

OB haul truck move 588 120 14

OB haul truck dump 846 304 36

Dozer 1,192 280 34

Grader 391 98 12

Wind erosion 5,110 2,554 306

Dumping 706 296 36

Handling 0.40 0.20 0.02

All roads combined 9,385 1,925 231

Total 18,370 5,649 677

A comparison of the dust emissions inventories of the Project (Table 5) and the South of Embley Project (Table 6) indicate a similar total level of dust emissions even though the scale of the projects are different. This can be partially explained by the methods of mining between the two projects, with the South of Embley Project using conveyors to transport some of the bauxite from pit to port. Using conveyors results in lower dust emissions compared to using trucks on unpaved haul roads, as proposed for the Project.

It is not possible to directly compare the two dust emissions inventories due to a lack of detailed information that was used to estimate dust emissions in the South of Embley air quality assessment. Detailed information regarding the estimation of dust emissions for the Project are described in Appendix A.

Notwithstanding this, as the magnitude of emissions are similar between the two projects the dispersion modelling results from the South of Embley air quality assessment can be used to infer impacts from the Project.


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The South of Embley Project air quality assessment detailed that impacts were not predicted to occur beyond 5 km from mining activities.

5.2 Project Impact

Air quality impacts from the Project operating in isolation are not predicted to occur beyond 5 km from mining activities. This is based on the South of Embley Project air quality assessment dispersion modelling study. Therefore, ground-level concentrations at sensitive receptors are not expected to exceed the air quality criteria due to the Project.

The Bauxite Hills Project is also proposed in the area, adjacent to Gulf's Project and focused around the east and west of the Skardon River Project (See Figure 2). Cumulative dust impacts have not been explicitly assessed as the Bauxite Hills Project EIS is not complete.

However, assuming the Bauxite Hills Project has similar activities to Gulf's Project and is less than half the size (2 Mtpa), air quality impacts are assumed not to occur beyond 2.5 km from their mining activities. Conservatively, cumulative air impacts are therefore not predicted to occur beyond 7.5 km from both projects. Therefore, ground-level concentrations at sensitive receptors are not expected to exceed the air quality criteria as a result of cumulative impacts.

5.2.1 Sensitive Receptors - Mapoon

The nearest sensitive receptors to the Project in and near Mapoon are 11 km or more to the southwest of the closest active mining areas and approximately 30 km from the processing area where over 50% of emissions are estimated to occur (Figure 10).

Based on the estimated cumulative impact buffer distance of 7.5 km and the fact that winds in the region predominantly occur from the east to southeast, the minimum buffer distance of 11 km is considered to be more than adequate to ensure that the nearest receptors are not impacted by any dust emissions from the two projects.

As previously discussed, dispersion modeling of dust emissions has not been conducted due to the relatively large buffer distances between mining activities and sensitive receptors highlighting a low risk of air quality impacts.

5.2.2 Sensitive Receptor – Bauxite Hills Project Accommodation Camp

The location of the accommodation camp for the Bauxite Hills Project is unknown at this stage. Based on the cumulative impact results, accommodation camps are required to be located more than 7.5 km away from mining activities in order to comply with air quality criteria. However, it may not be feasible to locate accommodation camps greater than 7.5 km from mining activities.

As both projects are planning accommodation camps it is likely that both projects will generate dust at the adjacent accommodation camp without appropriate mitigation measures. It is assumed that a mutual agreement between Gulf and Cape Alumina will be entered into later in the development of the Project to manage air quality impacts at the respective accommodation camps. In addition the Project will implement measures to achieve workplace health and safety air quality criteria.

This agreement could involve operational controls to reduce dust, construction methods for the camp accommodation to limit dust within accommodation units, timing and location of mining activities, air quality monitoring at camps and plans to alter mining activities should air quality levels at the camps not achieve compliance.


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5.2.3 Impacts on Vegetation

The deposition rate of dust decreases with distance from mining activity. The South of Embley EIS predicted that dust deposition rates would fall below nuisance guidelines at a distance of 1 km from a source. The vegetation in the immediate vicinity of the Project activities is primarily classed as "least concern". However, it will be located within a few hundred metres of mining activities.

Whilst there are no statutory guidelines for dust impacts on vegetation, a study by Doley (2006) indicated that sensitive plants can tolerate dust deposition level up to twice the nuisance guideline. The vegetation in the Project region is classed as "least concern" and coupled with the dust management controls the mine will implement (Section 6), the impact to vegetation is considered to be low.

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6. PROJECT CONTROLS/ MITIGATION MEASURES

While there is a low risk of potential impact from the Project, good practice dictates that dust emissions are minimised are far as practicable. It is likely the control of dust emissions will be primarily required to manage workplace health and safety risks and dust levels at the accommodation camps, rather than exposure to dust at the nearest receptors in and near Mapoon. The Project will have, as a minimum, the following dust mitigation measures in place:

• Watering of haul roads and stockpiles

• Use of dust suppressants as required

• Progressive rehabilitation of mined areas


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7. REFERENCES

Australian Bureau of Meteorology (BOM) (11 March 2015)

http://www.bom.gov.au/jsp/ncc/climate_averages/thunder-lightning/index.jsp

http://www.bom.gov.au/jsp/ncc/climate_averages/thunder-lightning/index.jsp?maptype=otdg

http://www.bom.gov.au/cgi-bin/silo/cyclones.cgi?region=aus&syear=1906&eyear=2006 &loc=1&txtloc=&radius=100&ulat=12.679119&ulon=141.925173

Doley, 2006, Airborne particles and vegetation: Review of physical interactions, Clean Air and Environmental Quality 40 (2), 36-41

Environmental Protection (Air) Policy 2008, Queensland Government

Environmental Protection Act 1994, Queensland Government

GHD Oceanics, 1975. Hay Point Environmental Planning Study, report to the Queensland Coordinator General.

MET Serve (November 2014) Site Specific Application Hey Point Bauxite Project. MET Serve Pty Ltd for Green Coast Resources

National Pollutant Inventory (NPI) (2012), “Emission Estimation Technique Manual for Mining v3.1”. National Environment Protection Council.

RTA (April 2015). http://www.riotintoalcan.com/ENG/ourproducts/1803_weipa.asp. Visited April, 2015.

US EPA (1998), “Western surface coal mining”, AP-42 Chapter 11.9, USEPA Office of Air Quality Planning and Standards.

US EPA (August 2004), AP-42 document, Chapter 11.19.2 "Crushed Stone Processing and Pulverized Mineral Processing", USEPA Office of Air Quality Planning and Standards

US EPA (November 2006a), AP-42 document, Chapter 13.2.2 "Unpaved Roads", USEPA Office of Air Quality Planning and Standards

US EPA (November 2006b), AP-42 document, Chapter 13.2.4 "Aggregate Handling and Storage Piles", USEPA Office of Air Quality Planning and Standards

Rio Tinto Alcan (2012), Environmental Impact Statement for South of Embley Project

Rio Tinto Alcan (2013), Final Environmental Impact Statement for South of Embley Project

Witt P, Carey K and Nguyen T 1999, Prediction of dust loss from conveyors using CFD modeling, Second International Conference on CFD in the Minerals and Process Industries, CSIRO, Melbourne


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APPENDIX A METHODOLOGY FOR CALCULATING DUST EMISSIONS FROM INDIVIDUAL EMISSION SOURCES

A1 CONVEYORS

Emission rates for conveyors were calculated using the following equation:

𝐸𝐹𝑇𝑆𝑃 = 0.031 × 0.2 ×𝑎𝑈𝑎𝑣𝑔2 + 𝑏𝑈𝑎𝑣𝑔 + 𝑐𝑎𝑈𝑟𝑒𝑓2 + 𝑏𝑈𝑟𝑒𝑓 + 𝑐

where:

EFTSP emission factor for TSP (g/m/s)

Uavg average wind speed on site (3.1 m/s, BOM)

Uref reference wind speed

a constant (0.00006)

b constant (-0.0002)

c constant (0.0001)

TSP emissions are based on the speed of prevailing winds, referenced on the study by GHD and Oceanics Australia (GHD-Oceanics, 1975), using a reference emission rate of 0.031 g/s/m at a reference wind velocity of 10 m/s (Uref). A factor of 0.2 is used to account for the difference in particle size distribution between particulate matter sampled in the GHD Oceanics study and the normal TSP size fraction of PM30-50.

The remaining ratio of quadratics is a correction for the wind speed based on the work of Witt et al. (1999).

Of TSP emissions, 47% are estimated to be PM10 and 7% of TSP emissions are estimated to be PM2.5. The particulate matter distribution is based on size ratios of dust emitted from transfers.

The emission factor defines emissions of dust based on the length of the conveyor (g/m/s). Total emissions are dependent on conveyor length.

The total length of conveyors in the processing area has been conservatively estimated to be 200 m. All conveyors are assumed to have two sides and a roof, providing a 70% control efficiency.

A2 SCRAPERS – TOPSOIL/SUBSOIL

Topsoil and subsoil is removed using a scraper. Emission rates for scraping of topsoil and subsoil were calculated using the following emission factors (NPI, 2012)

EFTSP = 0.029

EFPM10 = 0.0073

PM2.5 is assumed to be 10.5% of TSP, based on AP42 size ratio for bulldozing on overburden (AP42 Chapter 11.9, Table 11.9-2 ).

No controls have been applied to the emissions from scraping. Emissions were calculated based on 0.9 Mt of topsoil and 2.3 Mt of subsoil moved in the modelled year.


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A3 MATERIAL HANDLING – TOPSOIL/SUBSOIL

Material handling emissions are dependent on the amount of materials transferred (kg/tonne of material).

Emission rates for material handling were calculated using the following equation (NPI, 2012):

𝐸𝐹 = 𝑘 × 0.0016 × �𝑈

2.2�1.3

�2𝑀�1.4

where:

k: 0.74 for particles less than 30 μm

0.35 for particles less than 10 μm

0.053 for particles less than 2.5 μm

U: Mean wind speed in m/s (3.1 m/s, BOM)

M: Material moisture content, 3.4% adopted in this study, AP42 Table 13.2.4-1

Movement of topsoil and subsoil including through front end loaders, material pick up and dumping at stockpiles were modelled as material handling. No controls were assumed to be in place for any handling of topsoil or subsoil.

Emissions from the handling of topsoil were calculated based on 0.9 Mt of topsoil moved in the modelled year, handled a total of three times (drop onto an intermediate stockpile, pick up and final placement).

Emissions from the handling of subsoil were calculated based on 2.3 Mt of subsoil moved in the modelled year, handled a total of three times (drop onto an intermediate stockpile, pick up and final placement).

A4 MATERIAL HANDLING – BAUXITE

Material handling emissions are dependent on the amount of materials transferred (kg/tonne of material).

Emission rates for material handling (bauxite) were calculated using the bauxite specific emission factor (NPI, 2012):

𝐸𝐹 = 0.6

Of TSP emissions, 47% are estimated to be PM10 and 7% of TSP emissions are estimated to be PM2.5. The particulate matter distribution is based on size ratios of dust emitted from transfers.

Movement of bauxite including through front end loaders, material pick up and dumping at stockpiles, reclaiming and ship loading were modelled as material handling (bauxite). No controls were assumed to be in place for any handling of bauxite with the exception of the barge loading of product controlled by a cantilevered telescoping boom (70% control efficiency).

Emissions from the handling of bauxite were calculated based on 5 Mt of bauxite moved in the modelled year, handled a total of four times (Excavation, drop onto product stockpile, reclaiming and barge loading).


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A5 BULLDOZING

Bulldozing of bauxite occurs in-pit as well as at the product stockpiles. Emissions from dozing are dependent on hours of operation (kg/hr).

The TSP and PM10 emission factors for bulldozing on coal were calculated using the following equations (NPI, 2012):

𝐸𝐹𝑇𝑆𝑃 = 35.6 ×𝑠1.2

𝑀1.4

𝐸𝐹𝑃𝑀10 = 6.33 ×𝑠1.5

𝑀1.4

where

s: Bauxite silt content, 7.5% adopted in this study based on the mean value defined in AP42

M: Bauxite moisture content, 2% adopted in this study, which is Project specific

PM2.5 emissions are assumed to be 10.5% of TSP emissions, based on the PM2.5 to TSP ratio for bulldozing of overburden (AP42 Chapter 11.9, Table 11.9-2 ).

No control factors have been applied for dozer activity. Two bulldozers were assumed to be operating at all times.

A6 WIND EROSION OF ACTIVE STOCKPILES

Emissions of dust from wind erosion of stockpiles are dependent on the surface area of the stockpiles (kg/ha/hr). The emission rate of dust from the stockpiles has been calculated using the emission factor for active storage piles from the AP42 Chapter 11.9. In equation form, the emission factor for TSP is defined as:

𝐸𝐹𝑇𝑆𝑃 = 1.8 × u

where

u: Wind speed (m/s)

Of TSP emissions, 50% are estimated to be PM10 and 7.5% of TSP emissions are estimated to be PM2.5. The particulate matter distribution is based on size particle distribution for wind erosion as defined in the AP42 and the NPI. No controls were assumed to be applied to the active stockpiles.

The wind erosion emissions due to active stockpiles were based on the following conservative estimates of exposed stockpile area:

• 2 ha topsoil stockpile

• 4 ha subsoil stockpile


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• 8 ha product stockpile

A7 WIND EROSION OF EXPOSED AREAS

Emissions of dust from wind erosion of exposed areas are dependent on the size of the exposed areas (Mg/ha/yr). The emission rate is based on the equation defined in the AP42 for estimating emissions of wind exposed areas. A rain factor was not applied. The TSP emission factor was estimated using the following equation:

𝐸𝐹𝑇𝑆𝑃 = 0.85

Of TSP emissions, 50% are estimated to be PM10 and 7.5% are estimated to be PM2.5. The particulate matter distribution is based on the size particle distribution for wind erosion as defined in the AP42 and the NPI.

Clear and grubbing will occur in two campaigns (mining years 1 and 5). Emissions were estimated based on the assumption that half of the total area is exposed as a worst case (717 ha), which will only occur at the very beginning of the period before it is mined and then rehabilitated. Some vegetation will remain until mining begins, therefore the area will not be totally exposed and a 40% control for some vegetation cover (“Vegetation established but not demonstrated to be self-sustaining”) has been applied.

A8 WHEEL GENERATED DUST FROM UNPAVED HAUL ROADS

Wheel-generated dust was estimated using the emission factor defined in AP42 for haulage of materials on unpaved roads. The emission factor for wheel-generated dust on haul roads is dependent on the size of the truck and the silt content of the road. In equation form, the emission factors (g/VKT) for dust are defined using the following equations:

𝐸𝐹𝑇𝑆𝑃 = 281.9 × 4.9 × �𝑠

12�0.7

× �𝑊3�0.45

𝐸𝐹𝑃𝑀10 = 281.9 × 1.5 × �𝑠

12�0.9

× �𝑊3�0.45

𝐸𝐹𝑃𝑀2.5 = 281.9 × 0.15 × �𝑠

12�0.9

× �𝑊3�0.45

where:

s: Silt content of the road, 8.4% adopted in this study, AP42 – Western Surface Coal Mining

W: mean vehicle weight (tons)

The total emissions are dependent on the total distance travelled by the truck, which is based on truck capacity and the length of the haul road to be travelled. Level 2 watering has been assumed to be applied, providing a control efficiency of 75%.


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Emissions from the haulage of topsoil and subsoil were based on a truck with a capacity of 70 t and an average operating weight (empty and full) of 90 t.

The emissions for three bauxite haul scenarios were estimated based on the following truck types:

• Road train with a capacity of 350 t and an average operating weight (empty and full) of 325 t

• Dump truck with a capacity of 200 t and an average operating weight (empty and full) of 250 t

• Dump truck with a capacity of 70 t and an average operating weight (empty and full) of 90 t

A9 CRUSHING

Dust emitted during crushing of bauxite was estimated based on the uncontrolled emission factors defined in NPI mining (2012) for primary crushing of low moisture content ores. TSP and PM10 emission factors are 0.0027 kg/Mg and 0.0012 kg/Mg, respectively. The ratio of PM2.5 to TSP emissions is based on the size distribution of the materials handling emission factors (7.2%). This ratio was applied to the TSP emission rate in order to estimate PM2.5 emissions.

No controls were assumed to be applied to the active stockpiles. Emissions from the crushing of bauxite were calculated based on 5 Mt of bauxite processed in the modelled year.

A10 TRANSHIPPING

Emissions due to transhipping were estimated based on handling 5 Mtpa of bauxite twice, and a conveyor (50 m) using the emission factors described in sections A1 and A4.

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