Bengalla Mining Company Coal Mine Particulate Matter Control … · 2016-01-31 · Page number. Glossary . v Project overview . vii. 1. Introduction 9. 1.1 Background 9 1.2 PRP U2

Coal Mine Particulate Matter Control Best Practice Management Determination

February 2012

Bengalla Mining Company

Revision Details Date Amended By

A Draft Final 27/01/12 Y. Scorgie

B Final 3/02/12 Y. Scorgie

C Revision 1 22/02/12 Y.Scorgie

Authors : Y. Scorgie

Signed :

Reviewer : A. Harburg

Signed : …………………………........

Approved by : A. Sutton

Signed : …………………………........

Date : 2 March 2012

Distribution:

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BMC BMP Determination 22 Feb 2012.docx Page i

Contents Page number

Glossary v

Project overview vii

1. Introduction 9

1.1 Background 9

1.2 PRP U2 Coal Particulate Matter Control Best Practice 10

1.3 Scope of Assessment 12

1.3.1 Additions and Clarifications for OEH Mining Activity Categories 13 1.3.2 Costing of Control Measures 14

2. Overview of Operations and Management 15

2.1 Overview of Operations 15

2.2 Mine Activities with Potential Particulate Matter Emissions 18

2.3 Overview of Air Quality Monitoring at Bengalla 18

3. Current Emissions and Control Measures 21

3.1 Limitations of Emission Estimation Process 21

3.2 Existing Particulate Matter Emissions and Controls 21

3.3 Ranking of Mine Activities Based on Controlled Emissions 29

3.4 Top Four Mining Activities 30

4. Potential Measures to Minimise Emissions 31

4.1 Best Management Practice Measures for Top Sources 31

4.1.1 Wheel Generated Dust (Unpaved Roads) 31 4.1.2 Truck Loading and Dumping of Overburden 34 4.1.3 Bulldozing of Overburden 36 4.1.4 Wind Erosion of Overburden Emplacement Areas 37

4.2 Potential Additional Controls for Top Four Mine Activities 38

4.2.1 Wheel Generated Dust (Unpaved Roads) 38 4.2.2 Truck Loading and Dumping of Overburden 40 4.2.3 Bulldozing of Overburden 41 4.2.4 Wind Erosion of Overburden Emplacement Areas 41

4.3 Emission Reductions Achievable due to Additional Controls 42

5. Practicability of Additional Measures 45

5.1 Evaluation of Practicability 45

5.2 Best Practice Measures Selected for Implementation 46

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6. Implementation Timeline 47

7. References 50

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List of tables Page number Table 1.1 Mining activities defined within the OEH Guideline 14 Table 3.1 Current control measures applied at Bengalla 22 Table 3.2 Control efficiencies applied for current controls, where quantifiable 27 Table 3.3 Partially uncontrolled emissions for base case year 2011(a) 28 Table 3.4 Emissions for base case year 2011 with current controls 29 Table 3.5 Ranking of activities based on base case year 2011 annual emissions with current

controls in place 30 Table 3.6 Top four mining activities 30 Table 4.1 Control measures for wheel generated dust from material haulage along unpaved

surfaces, and associated control efficiencies from the literature 32 Table 4.2 Control measures for truck loading and dumping of overburden, and associated control

efficiencies from the literature 35 Table 4.3 Control measures for reducing wind-blown dust from overburden emplacement areas,

and associated control efficiencies from the literature 38 Table 4.4 Control measures for truck loading and dumping of overburden, and extent to which such

measures are applied at Bengalla 40 Table 4.5 Control measures for bulldozing of overburden, and extent to which such measures are

applied at Bengalla 41 Table 4.6 Summary of additional control measures identified, and associated control efficiencies,

where quantifiable 43 Table 4.7 Annual emission reduction estimated due to implementation of the additional control

measures identified at Bengalla 44 Table 5.1 Summary of additional control measures identified, and associated control efficiencies,

where quantifiable 45 Table 6.1 Tasks and implementation timelines for the application of additional control measures at

Bengalla 48

List of figures Page number Figure 1.1 Bengalla Locality Map 11 Figure 2.1 Bengalla Mining Method Schematic 17 Figure 2.2 Location of Bengalla’s TSP, PM10 and Meteorological Monitoring Stations 20

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Appendices

Appendix A Cost Information for Best Practice Measures Appendix B Emission Estimation Method Appendix C Haul Road Dust Control Efficiency Estimation Appendix D Photographs of Bengalla Operations

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Glossary

ACARP Australian Coal Association Research Program AEMR Annual Environmental Management Report BAM Beta Attenuation Monitor bcm Bench cubic metres - a measure of volumes mined, equal to the weight of

material divided by its specific gravity. BMC Bengalla Mining Company BMP Best Management Practice BoM Australian Bureau of Meteorology CARB California Air Resources Board CHPP Coal Handling and Preparation Plant EPA Environmental Protection Authority EPL Environmental Protection Licence FEL Front end loader HVAS High Volume Air Sampler µm Micrometre or micron (metre x 10-6) m² Square metre m3 Cubic metre Mt Megatonne (million tonne) MOP Mine Operating Plan NPI National Pollutant Inventory NSW EPA New South Wales Environmental Protection Authority OCE Open Cut Examiner OEH Office of Environment and Heritage PM10 Particulate matter less than 10microns in aerodynamic diameter PM2.5 Particulate matter less than 2.5microns in aerodynamic diameter PRP Pollution Reduction Program RTCA Rio Tinto Coal Australia RTEMS Bengalla’s Real Time Environmental Management System ROM Run of Mine TSP Total Suspended Particulate USEPA United States Environmental Protection Agency

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Executive Summary

Bengalla Mining Company (BMC) holds an Environmental Protection Licence (EPL number 6538) under the Protection of the Environment Operations Act 1997. This licence is administered by the Office of Environment and Heritage (OEH). On 8 August 2011, BMC was issued with notice amending EPL 6538 to include a Pollution Reduction Program that requires BMC to undertake a Best Management Practice (BMP) Determination comprising the following main components:

1. Estimate baseline emissions and determine the four mining activities that currently generate the most particulate matter;

2. Estimate the reduction in emissions that could be achieved by applying best practice measures;

3. Assess the practicability of each of these measures; and 4. Propose a timetable for the implementation of any practical measures.

The BMP Determination has been completed and is documented within this report.

Top Four Mining Activities

The top four mining activities, contributing the highest emissions of TSP, PM10 and PM2.5 during 2011, were identified as:

• wheel generated dust (unpaved roads); • loading/dumping overburden; • bulldozing overburden; and • wind erosion of overburden emplacement area.

When combined, the emissions from the above activities are estimated to contribute approximately 80 percent of the particulate matter emissions from Bengalla’s operations.

Additional Control Measures

Best management practices were reviewed and a gap analysis undertaken considering Bengalla’s current control measures, to identify additional control measures which could be applied at the site. Additional control measures identified are as follows:

OEH Mining Activity

Category Additional Control Measures

Wheel Generated Dust (Unpaved Roads)

Primary measure: Chemical suppression on unpaved haul roads Supporting measures: Documentation of the haul road management program for consistent implementation Measurement of the control effectiveness through dust monitoring

Truck Loading/Dumping of Overburden

No additional controls identified.

Bulldozing of Overburden No additional controls identified.

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OEH Mining Activity Category Additional Control Measures

Wind Erosion of Overburden

Interim stabilisation through vegetation and/or chemical suppression

All practicable measures for reducing dust emissions from bulldozer operations and overburden loading and dumping operations are currently implemented at Bengalla. The importance of continued implementation of current controls was however recognised.

Annual emission reductions estimated due to the implementation of the additional control measures were estimated to be in the range of 447 to 865 tonnes per year for TSP, with PM10 emission reductions in the range 158 to 300 tonnes per year, and PM2.5 emission reductions of the order of 17 to 32 tonnes per year.

All of the additional control measures identified were concluded by Bengalla to be practicable and an implementation timeline is provided in the report for their introduction.

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1. Introduction

1.1 Background

The Bengalla Mining Company Pty Ltd (BMC) operates the Bengalla Coal Mine (Bengalla) in the Upper Hunter Valley of New South Wales, approximately 4 kilometres west of Muswellbrook (refer to Figure 1.1). Bengalla is generally bound by Wybong Road to the north, Overton Road to the east, the Muswellbrook to Ulan Rail Line and the Hunter River Floodplain to the south and Roxburgh Road to the west.

BMC was granted a development consent (Development Application, DA, 211/93) by the then Minister for Urban Affairs and Planning on 7 August 1995 for the construction and operation of a surface coal mine, coal preparation plant, rail loop, loading facilities and associated facilities. Bengalla was originally approved to operate for a 21 year period from 1996 and to produce up to 8.7 Million tonnes per annum (Mtpa) of Run of Mine (ROM) coal.

Bengalla commenced operations in October 1998. Since approval, the Bengalla development consent has been modified four times providing for an increase in the maximum extraction rate to 10.7 Mtpa of ROM coal; an increase in the maximum height of the overburden dump to RL 270 metres; an extension of the coal extraction footprint by 32 hectares (ha) in the south (Wantana Extention Area), with an approved production rate for mining in this area of 2.5 Mtpa of ROM coal; and implementation of an Overburden Emplacement Area (OEA) Strategy to alleviate the shortage of emplacement capacity. This strategy involves extending the footprint and associated landform of the existing OEA to the south-east, relocation of the already approved temporary OEA to the west of the current operations; and delay in the finalisation and rehabilitation of the existing OEA.

BMC holds an Environmental Protection Licence (EPL number 6538) under the Protection of the Environment Operations Act 1997. This licence is administered by the Office of Environment and Heritage (OEH).

In 2010, the Office of Environment and Heritage commissioned Katestone Environmental Pty Ltd to prepare NSW Coal Mining Benchmarking Study: International Best Practice Measures to Prevent and/or Minimise Emissions of Particulate Matter from Coal Mining (Katestone, June 2011). A conclusion of the study was that substantial reductions in particulate matter emissions from coal mines in NSW could be achieved with the application of best practice measures. A key recommendation of this study is as follows:

Require …. existing coal mines to conduct site specific BMP determinations to identify the most technically and economically feasible options to reduce emissions. ……. For existing Premises the BMP determination could be required through a pollution reduction program (PRP) and the outcomes implemented through EPL conditions.

On 8 August 2011, BMC was issued with notice amending EPL 6538 to include a Pollution Reduction Program on the licence that requires BMC to follow a four step assessment process:

1. Estimate baseline emissions and determine the four mining activities that currently generate the most particulate matter;


2. Estimate the reduction in emissions that could be achieved by applying best practice measures;

3. Assess the practicability of each of these measures; and

4. Propose a timetable for the implementation of any practical measures.

More specific information on the BMP determination required is provided in the subsequent section. This Report documents the outcomes of the particulate matter control best practice assessment undertaken to meet regulatory requirements, including the proposed implementation timeframe for applying additional control measures identified.

1.2 PRP U2 Coal Particulate Matter Control Best Practice

The Best Management Practice determination requirements are set out in PRP U2 Coal Mine Particulate Matter Control Best Practice as follows:

U2.1 The Licensee must conduct a site specific Best Management Practice (BMP) determination to identify the most practicable means to reduce particle emissions.

U2.2 The Licensee must prepare a report which includes, but is not necessarily limited to, the following: - identification, quantification and justification of existing measures that are being

used to minimise particle emissions; - identification, quantification and justification of best practice measures that

could be used to minimise particle emissions; - evaluation of the practicability of implementing these best practice measures;

and - a proposed timeframe for implementing all practicable best practice measures.

In preparing the report, the Licensee must utilise the document entitled Coal Mine Particulate Matter Control Best Practice – Site Specific Determination Guideline - August 2011.

U2.3 All cost related information is to be included as Appendix 1 of the Report required by condition U1.2 above.

U2.4 The report required by condition U1.2 must be submitted by the Licensee to the Office of Environment and Heritage’s Regional Manager Hunter, at PO Box 488G, NEWCASTLE by 6 February 2012

U2.5 The report required by condition U1.2 above, except for cost related information contained in Appendix 1 of the Report, must be made publicly available by the Licensee on the Licensee’s website by 13 February 2012.

PRP U2 makes specific reference to the OEH Coal Mine Particulate Matter Control Best Practice – Site Specific Determination Guideline dated August 2011. It is however noted that this guideline was revised in November 2011.


Figure 1.1 Bengalla Locality Map


1.3 Scope of Assessment

The BMP determination followed the process outlined in the OEH Coal Mine Particulate Matter Control Best Practice – Site Specific Determination Guideline, November 2011, (hereafter referred to as the “OEH Guideline”). This process requires that the following steps be followed, as a minimum:

1. Identify, quantify and justify existing measures that are being used to minimise particle emissions

1.1. Estimate baseline emissions of TSP, PM10 and PM2.5 (tonne per year) from each mining activity. This estimate must:

- Utilise USEPA AP42 emission estimation techniques (or other method as approved in writing by the EPA)

- Calculate uncontrolled emissions (with no particulate matter controls in place); and

- Calculate controlled emissions (with current particulate matter controls in place).

Note: These particulate matter controls must be clearly identified, quantified and justified with supporting information.

1.2. Using the results of the controlled emissions estimates generated from Step

1.1, rank the mining activities according to the mass of TSP, PM10, and PM2.5 emitted by each mining activity per year from highest to lowest.

1.3. Identify the top four mining activities from Step 1.2 that contribute the highest emissions of TSP, PM10 and PM2.5.

2. Identify, quantify and justify the measures that could be used to minimise particle emissions

2.1. For each of the top four activities identified in Step 1.3, identify the measures that could be implemented to reduce emissions taking into consideration:

- The findings of Katestone (June 2011). NSW Coal Mining Benchmarking Study – International Best Practice Measures to Prevent and/or Minimise Emissions of Particulate Matter from Coal Mining;

- Any other relevant published information; and

- Any relevant industry experience from either Australia or overseas.

2.2. For each of the top four activities identified in Step 1.3, estimate emissions of TSP, PM10 and PM2.5 from each mining activity following the application of the measures identified in Step 2.1.


3. Evaluate the practicability of implementing these best practice measures

3.1. For each of the best practice measures identified in Step 2.1, assess the practicability associated with their implementation, by taking into consideration:

- Implementation costs; - Regulatory requirements; - Environmental impacts; - Safety implications; and - Compatibility with current processes and proposed future

developments.

3.2. Identify those best practice measures that will be implemented at the premises to reduce particle emissions.

4. Propose a timeframe for implementing all practicable best practice measures

4.1. For each of the best practice measures identified as being practicable in Step 3.2, provide a timeframe for their implementation.

In evaluating practicability in Step 3, the following specific information is to be documented:

- Estimated capital, labour, materials and other costs for each best practice measure on an annual basis for a ten year period. This information must be set out in the format provided in Appendix A and included as an attachment to the report;

- The details of any restrictions on the implementation of each best practice measure due to an existing approval or licence;

- Quantification of any new or additional environmental impacts that may arise from the application of a particular best practice measure, such as increased noise or fresh water use;

- The details of safety impacts that may result from the application of a particular best practice measure;

- The details of any incompatibility with current operational practices on the premises; and

- The details of any incompatibility with future development proposals on the premises.

1.3.1 Additions and Clarifications for OEH Mining Activity Categories

Mining activities are defined in the OEH Guideline as including any of the activities listed in Table 1.1.


Table 1.1 Mining activities defined within the OEH Guideline

Mining Activities Mining Activities

• Wheel generated particles on unpaved roads

• Loading and dumping overburden

• Blasting • Bulldozing coal • Trucks unloading overburden • Bulldozing overburden • Front-end loaders on overburden • Wind erosion of exposed areas • Wind erosion of coal stockpiles • Wind erosion of overburden

emplacement areas • Unloading from coal stockpiles • Dragline • Trucks unloading coal • Loading coal stockpiles • Graders • Drilling • Coal crushing • Material transfer of coal • Scrapers on overburden • Train loading • Screening • Material transfer of overburden

The mining activities defined within the OEH Guidelines were extended to include “trucks loading coal”, specifically applicable for excavators/loaders loading coal trucks.

“Trucks unloading coal” was specifically defined for the purpose of this BMP determination as trucks unloading ROM coal to the ROM hopper, with “material transfer of coal” applied for conveyor transfers.

Loading and unloading of coal stockpiles was taken to refer to stacking and reclaiming operations respectively.

“Loading and dumping overburden” was taken to mean the loading of trucks with overburden and trucks dumping overburden respectively. Whereas the handling of overburden by draglines, was accounted for under the dragline activity specified. Given that there are no other transfers of overburden, the “material transfer of overburden” activity category was omitted.

Emission factors applied for crushing operations encompass the entire crushing circuit including screening operations. The “coal crushing” and “screening” activity categories were therefore combined for the purpose of this study.

1.3.2 Costing of Control Measures

According to the NSW Environmental Protection Agency (EPA), the cost information referred to in the OEH Guideline is required to verify that a particular best practice measure is not practicable for implementation at a mine site. In subsequent advice provided, the EPA indicated that any licensee may choose not to submit cost information for best practice measures that are either currently being implemented, or that are considered by the licensee to be practicable (personal communication, Mitchell Bennett, Head, Regional Operational Unit – Hunter, NSW EPA, 27 January 2012).


2. Overview of Operations and Management This section provides an overview of Bengalla’s mining and coal processing operations, and identifies specific mining activities which are associated with particulate matter emissions.

A summary of the overall environmental management procedures and systems at Bengalla, pertinent for the control of particulate matter emissions, is also provided.

2.1 Overview of Operations

An overview of recent operations at Bengalla is given in this section, referencing the BMC Annual Environmental Management Report 2010.

Bengalla comprises an open pit mine, using strip mining methods, and a processing plant. Mining advances to the west based on dragline strips approximately 60 metres in width. The multi-seam coal deposit at Bengalla will include 30 strips being mined during the approved mine life. Mining operations are conducted 24 hours a day, 7 days a week.

The operation consists of the following facilities and equipment necessary for the extraction, washing and distribution of coal:

• Infrastructure area, comprising three coal stockpiles, a coal handling and preparation plant (CHPP), workshop and nearby office complex;

• Rail load out facilities; • Mobile plant and equipment; • Dragline; • ROM hopper; and • Mobile equipment fleet.

Figure 2.1 provides a schematic of the mining method utilised at Bengalla. Pre-strip mining (overburden removal prior to dragline excavation) is carried out by utilising three hydraulic excavators, a loader and a fleet of trucks which mine down to the Piercefield coal seam.

The P&H 9020 electric powered dragline is the primary piece of machinery used for removal of interburden waste from the multi-seam coal deposits at Bengalla. The waste material is removed to the Vaux seam in the first pass and to the Broonie / Bayswater seams in the second pass, each time placing the waste in the spoil adjacent to the strip mine. Spoil (the waste overburden material) is typically dumped at an angle of repose of 37 degrees. The dragline then moves onto the spoil created by the first and second passes (the low wall) where it removes the waste to the Wynn seam and, in a second low wall pass, the waste to the lower most coal seam, the Edderton seam.

The overburden and coal are accessed via haul road ramps which are formed as the mine proceeds westward. Haul trucks transport the overburden to overburden emplacement areas. Coal is hauled from the mining face to the ROM hopper which is located to the southwest of the operations next to the mining infrastructure area, where the coal is crushed to less than 250 millimetre. The crushed coal is then transported


along a 300 metre conveyor to the crushing station. The coal is crushed to a top size of 50 millimetre and can be bypassed to product stockpiles, direct fed into the CHPP or transported and stockpiled on the raw coal stockpile. Where practical conveyors are enclosed to reduce both noise and dust emissions.

The CHPP is located in the mine infrastructure area and houses the coal washery modules, each containing a dense medium cyclone and spirals to separate mineral contaminants. After processing, the product coal is centrifuged for the purpose of moisture reduction and then stacked onto one of two 250,000 tonne clean coal stockpiles. The product coal is then reclaimed from the stockpiles and conveyed to Bengalla’s rail loading facility which is fully automated from the CHPP control room in the main administration complex, supporting a loading rate of 4,000 tonnes per hour. Product coal is loaded onto trains and taken either to the Port Waratah Coal Loader at Newcastle for export or railed directly to local power stations where it is used to produce electricity for the NSW power grid.

Bengalla’s CHPP has three coal stockpiles, including one raw coal stockpile and two clean coal stockpiles. The ROM coal stockpile has a capacity of 200,000 tonnes and the two product stockpiles hold a combined volume of 500,000 tonnes. The CHPP and stockpiles are surrounded by bunds to reduce visual impacts of the plant on surrounding areas. Dust from stockpile areas are managed by an automatic sequential spray system that is activated when wind speed exceeds 5.6 metres per second (m/s).

Unlike conventional coal processing plants, Bengalla has no tailings dam and ultrafine material less than 0.125 millimetre is thickened, dewatered on belt press filters and then combined with other reject streams for final disposal back into the spoil. Reject material is combined onto a single reject belt and stored in a reject bin prior to being hauled back to the pit area where it is dried in cells before being buried within the spoil area and capped with a minimum of five metres of inert overburden material. This external rehabilitated surface is then shaped back to a slope of 10 degrees or less. The handling of reject material is undertaken in accordance with mining operations plan commitments and operational procedures for coarse rejects and tailings disposal.


Figure 2.1 Bengalla Mining Method Schematic


2.2 Mine Activities with Potential Particulate Matter Emissions

Bengalla’s mining activities which are associated with potential particulate matter emissions are as follows:

• Scraper stripping topsoil; • Drilling and blasting of coal and overburden; • Bulldozer operations on coal and overburden (in pit); • Dragline operations; • Loading and dumping of overburden; • Loading and unloading of coal; • Hauling of overburden to OEAs; • Hauling of coal to ROM hopper; • Coal crushing and screening; • Conveyors and conveyor transfer points (raw coal; product coal; reject); • Stacking/reclaiming from coal stockpiles; • Train loading; • Coal stockpiles, topsoil stockpiles, active mining area, overburden emplacement

areas, unsealed roads (wind erosion of exposed areas); • Grader operations; and • Other vehicle activity on site (light vehicles, fuel trucks, water trucks, delivery

trucks).

2.3 Overview of Air Quality Monitoring at Bengalla

Particulate matter monitoring at Bengalla forms an integral part of the site’s operational dust management and a summary of this monitoring is therefore provided.

Bengalla’s monitoring network is comprised of:

• Five High Volume Air Samplers (HVAS) measuring TSP • Four HVAS measuring PM10 • 29 depositional dust gauges • Four real-time air monitors (E-bams) measuring PM10, linked to the Real Time

Environmental Management System (RTEMS). The real-time particulate matter monitors are used for proactive management of dust, informing the application of operational controls to reduce the potential for dust impacts.

Real-time data from the PM10 monitors located upwind and downwind of the mine (Figure 2.2), are combined with wind speed and direction data from the meteorological station, to assess potential dust impacts from the site. This enables air quality to be regularly assessed, with operations modified or ceased if impacts are deemed significant. The monitors have been integrated into the site’s dispatch system to enable constant monitoring of dust impacts. Dust alarms and wind speed alarms alert pit the Open Cut Examiner (OCE) and environmental staff about operational dust impacts.


Bengalla ceases operations during high dust periods (as informed by the site’s real-time air quality monitoring system). When hourly average wind speeds are above 5.6 m/s the site does not operate on the elevated areas of its overburden emplacement area, pre-strip area or the run of mine infill area.

This system operates 24 hours a day seven days a week and the mine actively tracks its performance against results of this monitoring.


Figure 2.2 Location of Bengalla’s TSP, PM10 and Meteorological Monitoring Stations


3. Current Emissions and Control Measures The purpose of this section is to provide an estimate of baseline emissions and identify the four mining activities that currently generate the most particulate matter. Key components include:

• Estimation of TSP, PM10 and PM2.5 emissions (tonnes per year) from each mining activity using USEPA AP42 emission estimation techniques, including uncontrolled emissions and emissions with current controls in place.

• Ranking of mining activities according to the mass of TSP, PM10, and PM2.5 emitted by each mining activity per year.

• Identification of the top four mining activities that comprise the greatest contribution to emissions of TSP, PM10 and PM2.5.

3.1 Limitations of Emission Estimation Process

The OEH Guideline requires that uncontrolled and controlled emissions be quantified. A significant number of management measures are integrated within the mine design and site operations which are not quantifiable, rendering it impractical to provide an accurate assessment of uncontrolled emissions. For example: air quality considerations accounted for within the selection of the haul truck fleet (trucks with larger payload capacity); ongoing practices to minimise areas of disturbance and haul distances; current progressive rehabilitation; placement of plant within more sheltered areas; wind sheltering through the use of bunds; and use of draglines to replace movement of overburden by truck and shovel. For the purpose of the current study, additional control measures, other than those of the type listed here, were excluded to provide a partial approximation of the extent of ‘uncontrolled’ emissions.

Furthermore, control efficiencies cannot be established for all types of management measures which are applied. For example, emission reductions realised by experienced personnel applying operational measures to reduce visible dust emissions in the field are not readily quantifiable. The practice of undertaking overburden dumping at sheltered locations during high winds provides a further example.

The effectiveness of control measures for fugitive dust sources typically varies temporally and, in some instances, spatially. Control efficiencies documented in the literature are applicable for estimating annual emissions for an activity, but are less accurate in characterising changes in the control efficiency on a time-resolved basis and spatial differences in control efficiency.

3.2 Existing Particulate Matter Emissions and Controls

Annual TSP, PM10 and PM2.5 emissions (tpa) were estimated based on USEPA AP42 emission estimation techniques and site-specific information as documented in Appendix B. To support the estimation of controlled emissions existing mitigation measures were inventoried and control efficiencies allocated, where possible.

Existing particulate matter control measures being implemented at Bengalla are documented within Table 3.1.


Table 3.1 Current control measures applied at Bengalla

Mining Activity

Category

Current Control Measures

Blasting • Air quality impacts of blast operations are managed under the environmental procedure Environmental Procedure EP9.2 Blasting (including Air Quality and Vibration), and under other relevant safe work procedures such as PRO-0538 Drill & Blast Design Standard.

• EP9.2 aims to ensure that blasting operations comply with all Development Consent and EPL requirements and cause minimum dust effects at neighbouring properties. PRO-0538 aims to ensure that all blast designs and drill plans at Bengalla are to a standard and consider a number of inputs before drilling and blasting is undertaken, and to ensure that results for all blasts are collected and stored for future reference.

• At Bengalla blasting is restricted, only being permitted between 7 am and 5 pm, Monday to Saturday (daylight hours only), with restrictions to blasting also applied on public holidays. Individual blasts are designed to limit the potential for environmental impacts taking into account the size of individual charges, their proximity to roads and neighbouring residences, the nature of the stemming material and weather conditions.

• Reference is made to on-line Bureau of Meteorology forecasts during blast planning. Weekly blast scheduling references 7 day weather forecasts prior to schedule publication. During scheduling consideration is given to: - Wind direction and wind speed - Probability of rain - Temperature inversion - Blast pattern location relative to the extremities of the mining areas and the mines

neighbours - Size of the blast pattern area - Material type - Expected dust and or blast fume generation potential - Sleep time - Hot or reactive ground

• Public roads within 500 metres of the blast site are closed during the blast and until they are confirmed clear of dust and fume affecting visibility.

• Blasting operations are also informed by the Blasting Permission System which integrates real-time meteorology (wind speed, inversion strength, wind direction). The potential for dust impacts is primarily addressed by the wind speed and wind direction criteria, with inversion strength specified primarily to address noise impact potentials. Detailed blasting restrictions are outlined in the document Bengalla Meteorological Restrictions for Blasting. If real-time data is not available, wind speed and direction is assessed using a hand held compass and anemometer from an elevated vantage point.

• Real-time meteorological data is supplied on Bengalla’s Real Time Monitoring System.

• At least 1 hour prior to a scheduled blast time, Bengalla Environmental Services checks the real-time meteorological information for wind speed and direction before the blast is fired. Blasts are avoided under adverse meteorological conditions.

• 2 minutes prior to the scheduled blast time, the shot firer reconfirms the wind speed and direction.

• In the event that a blast needs to be delayed Environmental Services and the Superintendent Dragline Drill and Blast is notified. If the delay will extend beyond the permitted time of day for blasting then BMC Procedure PRO-077 Tie In Procedure is followed for postponing tie shots.

• Near neighbours are notified by phone and a ‘Blasting Hotline’ provides the community with daily blast times and locations via a free-call number.

• The location of neighbouring properties that may be affected by blasting operations has been taken into account in the placement of particulate matter monitoring stations.

• The Site Environmental Advisor is responsible for checking meteorological conditions prior to blasting, ensuring all blast exceedances are analysed and confirmed, preparing blast


Mining Activity

Category


monitoring reports and notifying OEH of any exceedances. • Environmental data for each blast is stored including weather (inversion strength, wind

speed, wind direction) and blast monitor results (air overpressure and ground vibration). • In addressing blast fume generation the following measures are implemented:

- Restrictions are placed on permissible sleep times. Blasts in weathered material are not permitted to be slept any greater than 48 hours without the approval of the Drill and Blast Superintendent and no other blasts are permitted to be planned to be slept any greater than 5 days without the approval of the Drill and Blast Superintendent.

- Use of blast fume scale and logging of fume incidences. Blast fumes are ranked as per Bengalla’s Blast Fume Scale.

- Trialling different explosives (e.g. Flexigel trials) - Blasts are filmed where practicable to provide a library of reference data for planning

and problem resolution.

Bulldozing Coal • Dozers travel on watered routes between work areas. Bulldozing Overburden

• Dozers travel on watered routes between work areas.

• Ceasing of operations at exposed areas during high dust periods (as informed by the site’s real-time air quality monitoring system).

Coal Crushing and Screening

• Crushing plant enclosed within internal water sprays.

Coal stockpiles Loading coal stockpiles Unloading coal stockpiles

• Dust generation from the coal stockpile area is addressed within environmental work instruction CNA-10-EWI-SITE-E2-001. Provision is made for: - Automated initiation of coal stockpile sprays when the wind exceeds 5.6 m/s. Coal

stockpile spray systems are informed by on-line meteorological data. - Monitoring of the stacking machine and stockpile height, wherever possible, to

minimize drop heights. - Visual triggers – visible dust not to rise above the boom height of the stacker or

reclaimer or leave the bounds of the stockpile being worked. - Close monitoring of reclaim operations where the machine is working raw coal or

performing final cut reclaiming. - Use of stockpile sprays and/or water carts where dust cannot be controlled within the

confines of the stockpile. - Bengalla uses automated stacker/reclaimers which vary their height by sensor. - Stockpiling and recovery of ROM coal is minimised as practical. ROM coal is usually

trucked from the pit to the ROM hopper, with a limited ROM stockpile maintained in case of poor weather.

Dragline • Dragline dust controls are documented within work instruction CNA-1-EWI-SITE-E2-004. Operational measures applied are as follows: - Avoiding over-dragging and overflowing the material in the bucket, - Lift bucket cleanly away from the dig face -hoist up with minimum spillage, and - Restrict the drop height as far as practical, particularly during windy conditions - Placement of material in a manner which avoids large rocks rolling down the spoils. - Regular assessment of dust from dragline operations throughout the shift by the dragline

operator and mine supervisor / team leader (or nominated representative). - Implementation of measures to ensure that visible dust from active work wares does not

leave the mine site and encroach on normal private property. This is given as potentially requiring changes to operations or, during poor conditions, temporarily stopping operations.

- Suspension of operations during dry, windy conditions. In 2009, by example, dragline operations ceased as a dust mitigation measure for 280 hours, including 96 hours in August.


Mining Activity

Category


• Dust-related dragline stoppages are logged.

• The use of water cannons was investigated a number of years ago but found not to be viable at that time (personal communication, Danny Brooks, Dragline Drill & Blast Superintendent, Bengalla).

Drilling • All drill rigs are equipped with dust suppression systems (vacuum systems).

• Provision is made within environmental work instructions (CNA-10-EWI-SITE-E2-004) for the following measures: - Inspection of drill dust suppression systems to ensure they are fully operational at the

start of each shift (water sprays, vacuum equipment, dust skirts to be fully operational). - Ceasing operations if systems are not operating properly resulting in visible dust. The

drill is stood down pending repairs being carried out. - When moving off a drill hole, operators are required to take care not to disturb drill

cuttings. - Blast crew must ensure disturbance to the crust on the drill cuttings is kept to a minimum

when loading the shot. - Visible dust triggers for suspending operations (visible dust cloud rising above drill deck

is unacceptable). • Operators can call for a water cart if the drill bench is dusty (small water cart available for

this purpose).

Graders • Graders travel on watered roads. Wheel Generated (Unpaved Roads)

• Access roads with high traffic volumes are paved.

• Trafficable areas are clearly demarcated and vehicle movements largely restricted to these areas.

• All trafficable areas and vehicle manoeuvring areas are maintained. • Fleet optimisation to reduce vehicle kilometres travelled. Bengalla’s haul road fleet

comprises three haul trucks with payload capacities of approximately 170 tonnes (3 Euclid R190 Rear Haul Trucks), 10 haul trucks with payloads of 280 Tonnes (1 Euclid R280 and 9 Hitachi 4500-2 Rear Haul Trucks) and 11 haul trucks with payloads of 209 Tonnes (11 Komatsu 830E Rear Haul Trucks).

• Wet suppression is applied using water carts.

• Levels of visible dust are assessed regularly by operators and the mine supervisor.

• Additional wet suppression is called for when elevated dust occurs. • Interim measures taken to reduce dust levels (pending additional wet suppression) may

include reduced vehicle speed or suspension of operations. Loading/Dumping Overburden

• Ceasing of operations during high dust periods (as informed by the site’s real-time air quality monitoring system).

• Maximum overburden dump distances are restricted to 7 metres due to the lift height being 7 metres.

Material Transfer of Coal (Conveying; transfer points)

• Enclosure or partial enclosure of conveyors. • Skirting fitted to conveyors at transfer points. • Use of belt cleaning. • Enclosed chutes.

Scrapers • Scrapers travel on watered roads. • Suspension of topsoil stripping operations during dry, windy conditions.

Train Loading • Rail loading operations at Bengalla comprise automated loading systems, with provision made for telescopic chutes and load profiling. Such systems limit the potential for the collection of coal fines collecting on rail wagon sills and for wind entrainment during transit.

• Provision is made within environmental work instruction CNA-10-EWI-SITE-E2-001 for rail


Mining Activity

Category


loading facilities to be closely monitored for the spillage of coal fines and material in the vicinity of the loading bin and rail siding. Coal spillage is required to be collected and disposed of on a regular basis to eliminate the potential for wind-blown dust.

Trucks Loading Coal

• Drop heights are reduced as far as practicable by excavator operators.

Trucks Unloading Coal (ROM Hopper)

• ROM hopper is equipped with a roof and is enclosed on 3-sides with automated water curtain.

• Dust generation at the ROM hopper is addressed within environmental work instruction CNA-10-EWI-SITE-E2-001. Provision is made for:

• Visual triggers for safety purposes (visible dust should preferably not rise above the operator cabin to ensure visibility is not compromised).

• Visual trigger for dust mitigation. Dust mitigation measures are called for if dust is observed to rise above the top of the tray.

• Application of wind speed thresholds (5.6 m/s) for defining moderate to strong winds for dust management purposes. Under such winds dust should not consistently rise over and above the operator cabin, unless other controls are in place (e.g. wind breaks or sprays) that effectively prevent dust from leaving the immediate area.

• Dust suppression sprays (or water cart) availability for use at all times during coal handling or dumping – and in use if dust cannot be controlled below cabin height.

• Modification of operations (e.g. slower tipping) if dust cannot be controlled in the manner specified.

• Ceasing of operations when visible dust leaves the mine site. Wind Erosion of Exposed Areas

• Minimisation of disturbed areas. All site disturbances are managed via the ground disturbance permit system.

• Topsoil stripping and topsoil stockpile volumes are tracked (and mapped) on an on going basis (topsoil stockpiled register).

• Topsoil stockpiles in place for longer than 3 months are revegetated to minimise dust generation.

• Topsoil stockpiles have gently battered slopes with heights limited to 3 metres. • Topsoil stripping is not undertaken during high winds. • Bengalla has no tailings dam (fine material is thickened, dewatered and then combined with

other reject streams for emplacement within the spoil area and capped with a minimum of five metres of inert overburden material.)


Mining Activity

Category



• Permanent rehabilitation in line with mining operation plan (MOP) targets. Bengalla rehabilitated 37.1 hectares in 2011; above its 2011 target of 36 hectares.

• Rehabilitation methods and procedures are undertaken in accordance with the Coal & Allied Rehabilitation Procedure and Bengalla’s approved Rehabilitation and Landscape Management Plan.

As rehabilitation progresses the vegetation is actively managed. This includes annual weed inspections and weed spraying programmes, vegetation control and slashing to mimic grazing and any remedial requirements such as repairing surface erosion.

Rehabilitation is completed opportunistically to ensure plant establishment occurs reducing dust generation from uncovered areas. Warmer months are targeted for seeding, with increased soil temperatures that assist seed germination in native species.

• Rehabilitation monitoring is undertaken to assess the long term viability of rehabilitation. Monitoring methods used derive from ACARP Hunter Valley Project C13048 ‘Development of Rehabilitation Completion Criteria for Native Ecosystem Establishment on Coal Mines in the Hunter Valley’.

• Annual audit of rehabilitated areas to assess on going success of rehabilitation and identify areas that need remedial work. External consultants engaged to complete audits. The audit includes the review of Bengalla’s initial rehabilitation completion criteria and other relevant statutory rehabilitation obligations.

• Specialist rehabilitation consultants are engaged to assist in rehabilitation techniques.

• Alternative rehabilitation techniques and soil improvement options are often trialled at Bengalla to improve the rehabilitation success of both pasture species and native tree species. Previous trials have included the use of bio solids, and the trialling of an organic growth medium (OGM) in 2010 consisting of municipal waste compost on a 2 hectare area of native seed.

• Hydromulch has been applied on temporarily inactive open spoils. Bengalla has applied hydromulching on a number of areas. Hydromulching is a type of rehabilitation often used for areas that topsoil cannot be applied and is commonly used for temporary rehabilitation. Hydro mulch contains a mixture of straw, seeds, water and a sticking agent so that it can be sprayed onto surfaces and will stick (then the seeds germinate). The temporary dump face facing Wybong Road was hydromulched in December 2010, increasing the visual amenity of the dump face and reducing the potential for dust from this dump face.

• In summary, Bengalla currently undertakes rehabilitation of areas as soon as they become available (including grass cover on windrows and temporary slopes). In addition, Bengalla will be increasing the amount of interim stabilisation of exposed areas.

Control efficiencies are not readily quantifiable for all measures applied Where control efficiencies for measures exist, they have been based on published control factors or site-specific calculations, as documented in Table 3.2. Site-specific calculations undertaken to quantify the effectiveness of Bengalla’s haul road watering strategy are presented in Appendix C. Emission reductions due to rehabilitation efforts are accounted for by emission estimates only being quantified for exposed, unrehabilitated areas.


Table 3.2 Control efficiencies applied for current controls, where quantifiable

Mining Activity

Category Control Measure(s) Providing Basis for

Control Efficiency Allocated(a) Control Efficiencies (%)

TSP PM10 PM2.5 Coal Crushing and Screening

Crushing plant are enclosed within internal water sprays(b)

87.5 87.5 87.5

Coal Stockpiles Water sprays 50 50 50 Drilling Water sprays 70 70 70 Loading Coal Stockpiles

Water sprays and variable height stacker(d) 62.5 62.5 62.5

Material Transfer of Coal

Enclosed/partially enclosure of coal and reject conveyors

70 70 70

Train Loading Retractable chute 70 70 70 Trucks Unloading Coal

ROM hopper is enclosed (roof, 3 sides) with automated water curtain(e)

85 85 85

Wheel Generated (Unpaved Roads)

Wet suppression (water cart)(f) 75 75 75

Wind Erosion of Exposed Areas

Wet suppression (water cart)(f) 75 75 75

Dragline Minimise drop height to within 5 metres(c) 53 38 53 Notes: (a) Control efficiencies were derived from the NPI EETM Mining (2011), and the USEPA AP42 Emission Factor literature unless specified otherwise. (b) Crushers are enclosed with internal water sprays. A control efficiency of 75 percent was applied for enclosure, and an additional 50 percent control efficiency for water sprays, giving a combined control efficiency of 87.5 percent. (c) The control effectiveness of reducing the dragline drop height from 10m to 5m was estimated by varying the drop height within the dragline emission factor. (d) A control efficiency of 50 percent was applied for water sprays, and an additional 25 percent control efficiency for the use of variable height stackers, giving a combined control efficiency of 62.5 percent. (e) A control efficiency of 70 percent was applied for hopper enclosure (3 sides and roof), and an additional 50 percent control efficiency for the use of automated water sprays, giving a combined control efficiency of 85 percent. (f) A control efficiency of approximately 75 percent was calculated based on the site’s haul road watering practices (refer to Appendix C); this coincides with the control efficiency specified in NPI EETM Mining (2011) for Level 2 watering, and with the maximum control efficiency indicated by the USEPA (2006) to be achievable through wet suppression.

Annual TSP, PM10 and PM2.5 emissions (tpa) estimated for each OEH-defined mining activity utilising USEPA AP42 emission estimation techniques are provided for 2011 Operations for:

• Partially uncontrolled emissions (with no additional particulate matter controls in place) (Table 3.3); and

• Controlled emissions (with current particulate matter controls in place, where such controls are quantifiable and control efficiencies available) (Table 3.4).

The overall control effectiveness, between the partially uncontrolled and currently control annual emission estimates, was calculated to be 65 percent for TSP, 63 percent for PM10 and 51 percent for PM2.5.


Table 3.3 Partially uncontrolled emissions for base case year 2011(a)

Mining Activity Category

Partially Uncontrolled Emissions (kg/annum) Percent of Total Emissions

TSP PM10 PM2.5 TSP PM10 PM2.5

Blasting

64,969

34,315

1,983 0.6 0.9 0.4

Bulldozing Coal

41,241

14,514

1,210 0.4 0.4 0.3

Bulldozing Overburden

268,758

101,336

37,626 2.5 2.7 8.2


313,972

122,858

4,710 2.9 3.3 1.0

Coal stockpiles

10,440

5,220

783 0.1 0.1 0.2

Dragline

258,604

92,489

8,793 2.4 2.5 1.9

Drilling

31,382

16,319

941 0.3 0.4 0.2

Graders

60,590

21,864

1,878 0.6 0.6 0.4

Loading Coal Stockpiles

1,327

628

95 0.0 0.0 0.0

Loading/Dumping Overburden

493,996

186,998

68,617 4.6 5.0 15.0


6,479

3,065

464 0.1 0.1 0.1

Scrapers

9,055

2,898

424 0.1 0.1 0.1

Train Loading

1,810

856

130 0.0 0.0 0.0

Trucks Loading Coal

194,537

47,132

6,160 1.8 1.3 1.3

Trucks Unloading Coal

324,228

49,096

6,160 3.0 1.3 1.3

Unloading Coal Stockpiles

1,333

630

95 0.0 0.0 0.0


8,212,646

2,787,245

283,500 77.0 75.1 61.9


161,530

119,717

18,607 1.5 3.2 4.1


208,879

104,440

15,666 2.0 2.8 3.4

Total

10,665,775

3,711,620

457,842 (a) Termed partially uncontrolled since these emission estimates do include a number of mitigation measures

which are already incorporated within the site’s design and operations. This includes emission reductions due to the use of trucks with larger payloads, rehabilitation, use of the dragline for the movement of about 50 percent of the overburden by tonnage, minimised haul distances (etc.). These emission estimates take into account pit retention (i.e. retention of emissions within the pit for in pit activities) and natural attenuation due to rainfall.


Table 3.4 Emissions for base case year 2011 with current controls

Mining Activity Category

Current Emissions (kg/annum) Percent of Total Emissions TSP PM10 PM2.5 TSP PM10 PM2.5

Blasting

64,969

34,315

1,983 1.7 2.5 0.9

Bulldozing Coal

41,241

14,514

1,210 1.1 1.0 0.5

Bulldozing Overburden

268,758

101,336

37,626 7.2 7.3 16.7


39,246

15,357

589 1.1 1.1 0.3

Coal stockpiles

7,057

3,528

529 0.2 0.3 0.2

Dragline

120,768

56,973

4,106 3.2 4.1 1.8

Drilling

9,415

4,896

282 0.3 0.4 0.1

Graders

60,590

21,864

1,878 1.6 1.6 0.8

Loading Coal Stockpiles

498

235

36 0.0 0.0 0.0

Loading/Dumping Overburden

493,996

186,998

68,617 13.3 13.4 30.4


3,664

1,733

262 0.1 0.1 0.1

Scrapers

9,055

2,898

424 0.2 0.2 0.2

Train Loading

543

257

39 0.0 0.0 0.0

Trucks Loading Coal

194,537

47,132

6,160 5.2 3.4 2.7

Trucks Unloading Coal

48,634

7,364

924 1.3 0.5 0.4

Unloading Coal Stockpiles

1,333

630

95 0.0 0.0 0.0


2,053,162

696,811

70,875 55.1 50.1 31.4


101,435

89,669

14,100 2.7 6.4 6.3


208,879

104,440

15,666 5.6 7.5 7.0

Total

3,727,777

1,390,951

225,402

3.3 Ranking of Mine Activities Based on Controlled Emissions

OEH-defined mining activities were ranked based on their contribution to total annual TSP, PM10 and PM2.5 emissions estimated for 2011 operations with current control measures in place (Table 3.5).


Table 3.5 Ranking of activities based on base case year 2011 annual emissions with current controls in place

Mining Activity Categories

RANKING TSP PM10 Emissions PM2.5 Emissions

Blasting 8 8 8

Bulldozing Coal 11 11 10

Bulldozing Overburden 3 4 3

Coal Crushing and Screening 12 10 12

Coal stockpiles 15 14 13

Dragline 6 6 7

Drilling 13 13 15

Graders 9 9 9

Loading Coal Stockpiles 19 19 19

Loading/Dumping Overburden 2 2 2

Material Transfer of Coal 16 16 16

Scrapers 14 15 14

Train Loading 18 18 18

Trucks Loading Coal 5 7 6

Trucks Unloading Coal 10 12 11

Unloading Coal Stockpiles 17 17 17

Wheel Generated Dust (Unpaved Roads) 1 1 1

Wind Erosion of Exposed Areas 7 5 5

Wind Erosion of Overburden 4 3 4

3.4 Top Four Mining Activities

Based on the assigned rankings, the top four mining activities that contribute the highest emissions of TSP, PM10 and PM2.5 for the 2011 base case year were identified as wheel generated dust (unpaved roads), loading/dumping overburden, bulldozing overburden and wind erosion of overburden emplacement area (Table 3.6). When combined, the emissions from these activities, are estimated to contribute approximately 80 percent of the particulate matter emissions from Bengalla’s operations.

Table 3.6 Top four mining activities

Rank

Mining Activity Categories

Emissions (kg/annum) Contribution to Total Annual Emissions ( percent)

TSP PM10 PM2.5 TSP PM10 PM2.5

1 Wheel Generated Dust (Unpaved Roads)

2,053,162

696,811

70,875 55.1 50.1 31.4

2 Loading/dumping Overburden

493,996

186,998

68,617 13.3 13.4 30.4

3 Bulldozing Overburden 268,758

101,336

37,626 7.2 7.3 16.7

4 Wind Erosion of Overburden Emplacement Areas

208,879

104,440

15,666 5.6 7.5 7.0

Total 3,024,794 1,089,584 192,784 81.1 78.3 85.5


4. Potential Measures to Minimise Emissions

4.1 Best Management Practice Measures for Top Sources

Best practice is not defined within air related legislation or regulations within NSW. In assessing best management practices implementable at coal mining operations, only available, technically and economically viable (or potentially viable) measures were inventoried. In Section 5, the practicability of potential measures will be reviewed taking into account local factors at Bengalla. This approach is consistent with the approach to best practice that is widely adopted, inter-state and internationally (EPA Victoria, 2007; WA DEC, 2003; EC, 2009; US Regulation 40 CFR Part 60).

4.1.1 Wheel Generated Dust (Unpaved Roads)

Factors affecting the extent of wheel generated road dust include: traffic activity rates (vehicle kilometres travelled, VKT), silt content of the road surface material (i.e. fraction <75µm in diameter), vehicle weight and speed, and moisture content of the road which is a function of the precipitation and evaporation.

Based on a comprehensive review of the literature, and including Katestone (2011), dust control practices for unpaved roads were identified as follows:

Source Reduction: • Ripping and revegetation of obsolete roads • Prioritise source reduction measures by: taking the most direct route, undertaking

back-hauling, using conveyors in place of haul roads, and/or using larger trucks to minimize trip numbers

• Sealing roads with high traffic volumes and hardstand areas with frequent mobile equipment activity

Haul Road Design:

• Optimise surface drainage, particularly at intersections • Optimise base materials to reduce silt content and increase the retention of larger

aggregates, particularly at intersections

Haul Road Maintenance and Management: • Restrict vehicle speeds on roads (Katestone 2011 refers to 40 km/hr or less) • Regular grading and gravelling of heavy traffic areas such as intersections • Watering, application of chemical suppressants or paving of light traffic areas,

such as the CHPP, workshop and administrative areas • Regular resurfacing of high traffic areas such as intersections to reduce silt build

up • Regular maintenance of drainage design features at intersections • Diligent monitoring and application of controls as surface dries out to avoid

excessive emissions. Real-time triggers used to identify problem areas for targeted application of controls.

http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?sid=f07430ab163e3fffac41a40e70b19774&c=ecfr&tpl=/ecfrbrowse/Title40/40cfrv6_02.tpl


• Regular watering of haul roads and at the direction of haul truck operators or the Open Cut Examiner (OCE)

• Avoid overwatering of haul roads • Regular grading and maintenance of intersections • Application of preventative measures to prevent material deposition on haul

roads, such as: - Avoid overloading which could result in spillage. - Provide for storm water drainage to prevent water erosion onto stabilised

unsealed roads. - Prevent wind erosion from adjacent open areas.

• Documentation of the haul road management program for consistent implementation

• Ongoing visual monitoring of dust • Periodic control efficiency measurement

Examples of dust control efficiency measurement methods include: roadside dust monitors, in situ road surface entrainment testing, mobile monitoring or road material bulk surface silt loading analysis (Cowherd and Muleski, 2008; Cowherd, 2009; Kavouras et al., 2009; Fitz and Bumiller, 2008)

Katestone (2011) concluded best practice control measures for unpaved haul roads to be the application of chemical suppression. Additionally, visual monitoring of dust above the deck, wheels or tray of the haul trucks was noted to be used as a trigger for the application of additional watering. Haul truck drivers were noted to play an important role in dust management.

A summary of several control measures and associated control efficiencies from the literature is given in Table 4.1.

Table 4.1 Control measures for wheel generated dust from material haulage along unpaved surfaces, and associated control efficiencies from the literature

Type of Measure Control Measure PM Control Efficiency Reference

Source reduction Usage of conveyors in place of haul roads 95% Katestone (2011)

Paving of the travel surface >90% MRI (2006) ; Bohn et al. (1978)

Surface improvement

Low silt aggregate 30% Bohn et al. (1978) Application of geotextiles to gravel-surfaced haul roads 56-75% Freeman (2006)

Speed restrictions Reducing truck speed from 75 km/hr to 50km/hr 40-75% Foley et al. (1996)

Reducing truck speed from 65 km/hr to 30 km/hr 50-85% Foley et al. (1996)

Wet suppression Watering (standard procedure) 10% - 75% MRI (2006) Level 1 watering : 2L/m²/hr 50% NPI EETM Mining (2011) Level 2 watering : > 2L/m²/hr 75% NPI EETM Mining (2011) Watering twice a day for industrial unpaved road 55% MRI (2006)


Type of Measure Control Measure PM Control Efficiency Reference

Surface treatment Petroleum resin (after 5 months of application) 80%

USEPA AP42 Chapter 13.2.2 Unpaved Roads (2006)

Oil and double chip surface 80% Bohn et al. (1978) Chemical suppression 84% MRI (2006)

Chemical suppression 40-98% Foley et al. (1996)

Hygroscopic salt application (control efficiency effectiveness over 14 days)

45% Thompson et al. (2007)

Hygroscopic salt application: (control efficiency effectiveness within 2 weeks)


Lignosulphonate application: (control efficiency effectiveness over 23 days)


Lignosulphonate application: (control efficiency effectiveness over 23 days - upper bound)


Polymer emulsions (control efficiency effectiveness over 58 days)


Tar and bitumen emulsions (control efficiency effectiveness over 20 days)


Chemical suppression using EK35 63-94%+(a) USEPA (2006a)

Chemical suppression using EnviroKleen 20-99%+(a) USEPA (2006b)

Chemical suppression using DustGard 58-90%+(a) USEPA (2006c)

Chemical suppression using PetroTac 73-94%(a) USEPA (2006d)

Chemical suppression using Techsuppress 43->90%(a) USEPA (2006e)

Use of trucks with larger payloads

Usage of larger vehicles rather than smaller vehicles, 90t to 220t

40% Katestone (2011)





Notes: (a) The dust control efficiency is published by particle size fraction as follows:

Product

Dust Control Efficiency (%) Total Particulate

Matter (TPM) PM10 PM2.5 EK35 63 - 87 84 - 90 56 - 94+ EnviroKleen 78 - 99+ 87 - 91+ 20 - 87+ DustGard 75 - 86 88 - 90+ 58 - 59 PetroTac 74 - 94 73 - 98 >90 Techsuppress 62 - 84 43 - 76 >90


4.1.2 Truck Loading and Dumping of Overburden

Emissions from overburden loading derive from the use of a shovel, excavator or loader scooping up the load, moving into a loading position and dumping material into a truck, reloading and repeating the process. Overburden dumping is a more straight-forward batch drop type process with emissions occurring due to material becoming airborne due to entrainment whilst being dumped.

Factors which influence the extent of emissions from overburden handling include: volume of overburden handled, material moisture and silt content, wind speed and the extent to which operations take place within the pit or within sheltered areas.

Based on a comprehensive review of the literature and of dust control practices at coal mines in the Hunter Valley and elsewhere, dust control practices for overburden loading and dumping were identified as follows:

• Use of dragline operations for overburden handling in place of ‘truck and shovel’ operations

• Modifying or ceasing operations during dry, windy conditions. Modification of operations may comprise sheltered to avoid exposure to high winds

• Avoiding the double handling of material where possible • Minimising the drop height when loading and dumping • Reducing the roll distance of overburden when dumping • Identifying material types that contain more dusty material, and modifying

operations in the handling of such materials • Use of bund walls, where practical, to shelter overburden tipping

The use of water carts with boom sprays or emerging wet suppression systems such as mobile fogger sprays is under investigation for potential use for overburden transfers, e.g. dragline operations. The watering of overburden extraction areas (work benches) prior to overburden extraction and loading is implemented on a limited scale by some mining operations specifically targeting overburden areas overlying spontaneous combustion.

Katestone (2011) specifies best practice measures for minimising emissions from overburden handling to be:

• Use of water sprays or water carts with boom sprays • Cease of modify activities on dry windy days • Minimise dump height

The use of water sprays or water carts for overburden loading and dumping is specified by Katestone (2011) on the basis of the Australian Government Department of Resources, Energy and Tourism (2009) publication Leading Practice Sustainable Development Program for the Mining Industry, Airborne Contaminants, Noise and Vibration. Katestone (2011, p. 184) states that this reference “suggests that the application of water can achieve a reduction in particulate emissions from truck dumping”. It is however noted that the reference referred to addresses primarily the use of water trucks and water cannons on material stockpiles, and the use of water sprays on coal in transit (e.g. conveyor transfers). The application or effectiveness of using water sprays to control dust from overburden loading or dumping operations is not addressed.


Katestone (2011) documents that 92 percent of mines in the NSW Greater Metropolitan Region with open-cut operations use water application by fixed sprays or water cart. It is however, not made clear which if any of these operations use these sprays or carts for controlling dust from overburden loading and dumping operations. Nor is the use of water sprays or water carts with boom spray costed for such an application.

Water sprays are not routinely used to control dust from overburden loading and dumping operations due to practical constraints on the positioning of such sprays relative to operations, particularly during overburden dumping operations when ambient wind effects on the water sprayed need to be taken into account. The application of mobile sheltering devices is similarly discounted on the basis of it being impractical. Despite the constraints noted, some mines are trialling the use of mobile water fogger cannons for overburden transfer points, e.g. draglines, as mentioned previously. Further development of this technology may render wet suppression feasible for future applications. Based on the approach adopted for identifying best practice measures, the application of wet suppression is not identified as a best practice measure.

A summary of several control measures and associated control efficiencies from the literature is given in Table 4.2.

Table 4.2 Control measures for truck loading and dumping of overburden, and associated control efficiencies from the literature

Applicability of Measure Control Measure PM Control

Efficiency References

Truck loading/dumping (and hauling)

Replacement of ‘truck and shovel’ operations with dragline Site-specific(a)

Avoid double handling of material 100% for avoided handling

Overburden loading by excavator

Minimise drop height from 3 metres to 1.5 metres 30% Katestone

(2011)(b)

Modify operations during dry, windy conditions Not applicable(c)

Truck dumping Minimise drop height from 3 metres to 1.5 metres 30% Katestone

(2011)(b) Modify operations during dry, windy conditions Not quantifiable(d)

Reduce roll distance of overburden when dumping Not quantifiable

(a) The control efficiency achieved depends on the site-specific emission intensity (kg emissions / tonne handled) of dragline operations relative to ‘truck and shovel’ handling.

(b) Reductions are inferred from emission factor for dragline operations which accounts for drop height (Refer to Appendix B), and founded down to the nearest 10 percent.

(c) This measure addresses the potential for off-site impacts by reducing emissions on days when airborne particles are more likely to be dispersed off-site, rather than reducing overall annual emissions.

(d) Depends on the prevailing wind speed, sheltered dump space availability and the wind speed at which modified operations are implemented. The control efficiency is therefore site-specific, likely to vary substantially over time, and cannot be quantified with sufficient certainty.


4.1.3 Bulldozing of Overburden

Dozers are used at the overburden tip face, assisting overburden emplacement and smoothing/compacting the dump surface to ensure safe access by haul trucks. Dozers are also used for shaping overburden emplacement areas during rehabilitation.

The extent of emissions from bulldozing operations is determined primarily by activity rates (hours of operation) and material silt and moisture content. The prevailing wind speed and the nature of the dozing operation also determine the extent of emissions although these parameters are not accounted for in emission factors for dozer operations. Dust generation by dozer cooling fans and exhaust systems, when airflow vents are angled towards the material being handled or traverse over, also influence the extent of emissions.

Based on a review of the literature, and local and international mine practices, the following control measures were identified for bulldozers operating on overburden:

• Avoid dozer operations at wind exposed areas during dry, windy conditions • Minimising the travel speed and distance travelled by bulldozers • Designate and maintain dozer routes between work areas (Refer to unpaved

road control measures) • Visual monitoring of dust levels from dozer operations by trained personnel, with

operations modified or ceased when elevated dust levels are observed to occur • Modification of mobile plant to redirect the air blast from their cooling and exhaust

emission systems away from the material being traversed and/or handled (where applicable)

Significant reductions to the operational hours of dozers at existing mining operations would necessitate a substantial redesign of mining operations. This measure is not considered practicable for operating mines. Katestone (2011) also reaches this conclusion.

Katestone (2011) initially considered the application of watering of overburden ahead of such material being handled as a control measure for dozer operations. This measure was however estimated to cost $141,103 per tonne of PM10 reduced (a factor of 30 times higher compared to measures such as chemical suppression of haul roads; $4,710 per tonne). The control effectiveness used by Katestone (2011) to quantify the emission reduction of watering (50 percent) was based on a control factor derived from the literature for scrapers operating on topsoil.

The addition of sufficient moisture to a sufficient depth, to substantially influence dust emissions from dozers handling overburden, is impractical and unlikely to achieve the control efficiency allocated by Katestone (2011). This measure is therefore not considered further.

It is noted that Katestone (2011) concluded the best practice control measures for bulldozing to be:


• Minimising travel speed and distance travelled by bulldozers, and • Application of water to keep travel routes moist

Control efficiencies are not available for any of the control measures identified, including those designated to be best practice by Katestone (2011).

4.1.4 Wind Erosion of Overburden Emplacement Areas

Particulate matter emissions due to wind erosion of overburden emplacement areas is a function of the extent of the exposed area, the velocity of the wind at the surface, in situ overburden moisture content and particle size distribution, and the extent to which the surface has crusted.

Based on a review of the literature, and local and international mine practices, the following control measures were identified for reducing the wind erosion potential of overburden emplacement areas:

• Maximise in-pit emplacement so that emplacement areas are sheltered from the prevailing wind

• Progressive rehabilitation, with rehabilitation progressing as soon as practical after a landform has obtained its final height. Rehabilitation comprises use of vegetation and land-contouring to produce the final postmining land-form

• Application of interim stabilisation (vegetation; chemical suppression) for overburden emplacement areas which are to be in place for extended periods prior to reaching the required heights for final landforming and rehabilitation. Vegetation could take the form of hydraulic mulch seeding, direct seeding or aerial seeding. Aerial seeding is more cost-effective if applied on larger areas, and is particularly suitable for areas that may not easily be accessible on the ground, e.g. dragline spoils.

• Restricting vehicle access to formed roads on overburden emplacement areas The timeframe for how long an overburden emplacement area should be permitted to remain exposed prior to interim stabilisation being applied represents a further consideration. This period is however dependent on the time of the year the area becomes available for interim stabilisation and the method selected for such stabilisation. A period of 3 to 6 months is likely to be practicable in many instances.

Other practices to reduce wind entrainment include wind sheltering measures (e.g. wind fences, treelines) and rock cladding. Given however the size of overburden emplacement areas, the manner in which they are constructed, and the aim of maximising rehabilitation, these measures are not well suited. Interim stabilisation, pending rehabilitation, and avoidance of disturbance represent more suitable measures.


Best practice measures are identified by Katestone (2011) as follows:

• Maximise rehabilitation works • If exposed area is a potential source of particulate matter emissions and is likely

to be exposed for more than 3-months, revegetation should take place • Strategic use of watering, suppressants and hydraulic mulch seeding depending

on circumstances

A summary of control measures applicable for overburden emplacement areas, and associated control efficiencies from the literature is given in Table 4.3. Control efficiencies in the range of 40 percent to 100 percent are given as being applicable for permanent rehabilitation depending on duration in place, coverage and demonstration of being self-sustaining.

Table 4.3 Control measures for reducing wind-blown dust from overburden emplacement areas, and associated control efficiencies from the literature

Type of Measure Control Measure PM Control

Efficiency References

Rehabilitation Fully rehabilitated (release) vegetation 100% NPI EETM Mining (2011)

Rehabilitation 99% Katestone (2011) citing NPI EETM Mining (2001)

‘Secondary rehabilitation’ 60% NPI EETM Mining (2011)

‘Primary rehabilitation’ 30% NPI EETM Mining (2011)

Interim stabilisation Chemical suppression 84% CARB (2002)

Revegetation 90% NPI EETM Mining (2011)

Chemical suppression 70% Bohn et al. (1978)

Wet suppression (watering) 50% Bohn et al. (1978)

Avoid disturbance

Restrict vehicle access Not quantifiable

Emplacement of dustier material in more sheltered areas Not quantifiable

4.2 Potential Additional Controls for Top Four Mine Activities

Based on the inventoried best practice control measures, a gap analysis was undertaken of Bengalla’s current control measures, and potential additional controls identified for consideration.

4.2.1 Wheel Generated Dust (Unpaved Roads)

Bengalla implements the haul road design and source reduction measures identified including ripping and revegetation of obsolete roads, and reducing VKT through taking the most direct route, backhauling, use of conveyors where practicable, and by using


trucks with larger capacities. Bengalla’s haul road fleet comprises three haul trucks with payload capacities of approximately 170 tonnes (3 Euclid R190 Rear Haul Trucks), 10 haul trucks with payloads of 280 Tonnes (1 Euclid R280 and 9 Hitachi 4500-2 Rear Haul Trucks) and 11 haul trucks with payloads of 209 Tonnes (11 Komatsu 830E Rear Haul Trucks).

The majority of the haul road maintenance and management measures inventoried are implemented at Bengalla with the exception of the following:

• Chemical suppression on unpaved haul roads (USEPA, 2006; MRI, 2006); • Documentation of the haul road management program. • Measurement of the dust control effectiveness (Cowherd and Muleski, 2008;

Cowherd, 2009; Kavouras et al., 2009; Fitz and Bumiller, 2008). • Restriction of vehicle speed to 40 km/hr or less (Katestone, 2011).

The first three measures listed represent potential additional measures implementable at Bengalla to improve dust management along its haul roads. Whereas chemical suppression represents a primary measure, with an associated control efficiency, the other two measures (haul road management program documentation and measurement of dust control efficiencies) represent supporting measures.

The control efficiency achievable through the application of chemical suppression ranges significantly (20 percent to over 90 percent) across studies, sites, applications, products applied and particle size ranges (Table 4.1). In several of the studies the control efficiency is given as being in the range of 70 percent to 90 percent with a control efficiency of approximately 80 percent referenced by a number of studies including within the USEPA AP42 Chapter 13.2.2 Unpaved Roads (November 2006).

The likelihood of achieving higher control efficiencies due to chemical suppression is considered to improve given the implementation of the aforementioned supporting measures. Furthermore, it is noted that Bengalla is estimated to currently achieve an average dust control efficiency of approximately 75 percent through its watering program. For the purpose of evaluating potential emission reduction measures achievable, it is therefore assumed that a dust control efficiency in the range of 80 percent to 85 percent is feasible through the application of chemical suppression with supporting measures.

Katestone (2011) accurately indicates that a number of mining operations within the Hunter Valley use speed restrictions to limit dust generation. However, Katestone (2011) provides no justification for its specification of a vehicle speed of 40 km/hr as best practice. No specific control efficiency is provided for this vehicle speed restriction, nor the practicability or such a restriction addressed.

The maximum speed of the haul truck fleet used at Bengalla is in the range of 55 km/hr to 65 km/hr. In practice, operators drive to conditions, and actual speeds are frequently much lower, particularly on ramps, when loaded, and in the vicinity of intersections and other operational equipment. Furthermore, speed reduction is routinely applied by haul truck operators to reduce dust generation potentials when increased dust levels are visible. For the above reasons, and considering current practices at Bengalla, the restriction of vehicle speed to within 40 km/hr is not selected for further consideration.


In summary the following potential additional control measures and supporting measures (and associated control efficiency) are identified for further consideration for unpaved haul roads:

Measures: • Chemical suppression on unpaved haul roads • Documentation of the haul road management program for consistent

implementation • Measurement of the dust control effectiveness, e.g. through the use of dust

monitors Control Efficiency:

• Overall dust control efficiency range achievable: 80 to 85 percent (not taking into account site-specific control efficiencies due to current measures)

4.2.2 Truck Loading and Dumping of Overburden

The extent to which the control measures identified are applied at Bengalla is documented in Table 4.4. Based on the gap analysis, no additional measures were identified for application at Bengalla. The importance of continuing with the consistent application of the current control measures was however recognised.

Table 4.4 Control measures for truck loading and dumping of overburden, and extent to which such measures are applied at Bengalla

Control Measures Identified

Extent Applied at Bengalla

Use of dragline operations for overburden handling in place of ‘truck and shovel’ operations.

Measure is applied. Dragline in use at Bengalla; handled 36.7 Mtpa, comprising 50 percent of the total overburden handled in 2011. Based on site-specific emission intensities calculated for dragline operations (0.0016 kg PM10/tonne) and ‘truck and shovel’ operations (0.016 kg PM10/tonne; including loading, hauling and dumping), it is estimated that the use of the dragline resulted in an approximate reduction in PM10 emissions of about 530 tonnes during 2011.

Avoiding the double handling of material where possible.

Measure is applied. During 2011, overburden rehandling was limited to less than 3 percent of the overall overburden handled.

Reducing the roll distance of overburden when dumping.

Measure is applied. The extent of the overburden lifts at Bengalla, and hence the maximum roll distance, is confined to 7 metres.

Use of bund walls, where practical, to shelter overburden tipping.

Applied where practical.

Modifying or ceasing operations during dry, windy conditions. Modification of operations may comprise sheltered to avoid exposure to high winds.

Measure is applied. Bengalla ceases operations during high dust periods (as informed by the site’s real-time air quality monitoring system). When hourly average wind speeds are above 5.6 m/s Bengalla does not operate on the elevated areas of its overburden emplacement area.

Minimising the drop height when loading and dumping.

Measure is applied. Bengalla trains its operators to reduce the drop height, for safety and dust mitigation reasons. The drop height achieved varies across equipment (excavators; loaders), operators (different




levels of experience) and conditions.

4.2.3 Bulldozing of Overburden

The extent to which the control measures identified for dozer operations on overburden are applied at Bengalla is documented in Table 4.5. All practicable measures identified are currently applied at Bengalla. The importance of continued application of the current control measures is recognised.

Table 4.5 Control measures for bulldozing of overburden, and extent to which such measures are applied at Bengalla



Avoid dozer operations at wind exposed areas during dry, windy conditions.

Measure is applied. When hourly average wind speeds are above 5.6 m/s Bengalla does not operate on the elevated areas of its overburden emplacement area. (Measure is informed by the site’s real-time air quality monitoring system.)

Minimising the travel speed and distance travelled by bulldozers.

Measure is applied to the extent practical. Travel speeds are reduced by operators to ensure that visible dust is managed in line with environmental work instruction CNA-10-EWI-SITE-E2-004. Travel distances are determined by mine design and planning.

Designate and maintain dozer routes between work areas.

Measure is applied. Dozers primarily travel on designated, watered routes between work areas.

Visual monitoring of dust levels from dozer operations by trained personnel, with operations modified or ceased when elevated dust levels are observed to occur.

Measure is applied. In line with environmental work instruction CNA-10-EWI-SITE-E2-004 operators must report dusty conditions to the mine supervisor / team leader and take interim measures to ensure that visible dust is managed. This may require temporarily modifying or stopping operations.

Modification of mobile plant to redirect the air blast from their cooling and exhaust emission systems away from the material being traversed and/or handled (where applicable).

Measure is not applicable given the design of the dozers used at Bengalla (Caterpillar D10 and D11 track dozers).

4.2.4 Wind Erosion of Overburden Emplacement Areas

In-pit emplacement is practiced due to the strip mining approach and dragline operation implemented at Bengalla.

Bengalla currently undertakes rehabilitation of areas as soon as they become available (including grass cover on windrows and temporary slopes). Furthermore, Bengalla restricts vehicle access to designated roads on overburden emplacement areas.


Reference is made in Table 3.1 to past campaigns undertaken by Bengalla to vegetate temporarily inactive open spoils through the application of hydraulic mulch seeding (hydomulching). The temporary dump face facing Wybong Road was, for example, hydromulched in December 2010, increasing the visual amenity of the dump face and reducing the potential for dust from this dump face. Bengalla plans to increase the use of interim stabilisation for suitable exposed areas.

Interim stabilisation efforts at Bengalla could be enhanced by implementing the following supporting measures:

• Review currently exposed overburden emplacement areas to assess: – the period over which such areas are to remain inactive – material and surface characteristics (moisture content; particle size

distribution; evidence of crusting), – exposure to prevailing winds, and – proximity to environmental receivers

• Establish and implement the interim stabilisation method most suited for application to the areas identified (e.g. hydromulching, chemical stabilisation, direct seeding and aerial seeding)

• Apply a limit on the time period inactive overburden emplacement areas with dust generation potentials, are permitted to stay exposed prior to their being scheduled for interim stabilisation

• Establish a process whereby mine planning identifies, on a monthly basis, areas available for application of interim dust suppression measures. Include this accountability in relevant procedures

• Establish time periods within which interim stabilisation measures are to be applied for identified areas (e.g. time periods in the range of 1-3 months are practicable for chemical suppression; and 3-6 months for vegetation, depending on what time of the year areas become available for vegetation)

The control effectiveness of the interim stabilisation support measures will depend on the extent of the exposed overburden emplacement areas which are likely to remain inactive for 3 months, thus warranting such stabilisation. This extent is not known. For the purpose of estimating potential emission reductions, it is assumed that 20 percent of Bengalla’s unrehabilitated overburden emplacement areas (245.74 hectares) are to remain inactive for 3 months (i.e. 49 hectares). Furthermore, that a control efficiency in the range of 80 percent to 90 percent could be achieved through interim stabilisation of these areas (refer to Table 4.3).

4.3 Emission Reductions Achievable due to Additional Controls

A summary is provided in Table 4.6 of the additional control measures identified for potential application at Bengalla, and the emission reductions estimated to be achievable through the implementation of such measures, where reductions could be quantified. Control efficiencies in the literature were found to be most typically expressed in terms of TSP emission reductions achievable. For the purpose of the current assessment such control efficiencies were taken to be applicable for estimating emission reductions for PM10 and PM2.5.


Table 4.6 Summary of additional control measures identified, and associated control efficiencies, where quantifiable

OEH Mining Activity Category Additional Control Measures

Control Efficiency Range of Measure

(%)

Estimated Additional Control

Efficiency (%) Wheel Generated Dust (Unpaved Roads)

Primary measure: Chemical suppression on unpaved haul roads Supporting measures: Documentation of the haul road management program for consistent implementation Measurement of dust control effectiveness, e.g. through using dust monitors

80 - 85% 5 – 10%(a)

Truck Loading/Dumping of Overburden

No additional controls identified. NA NA

Bulldozing of Overburden No additional controls identified. NA NA


Interim stabilisation (e.g. vegetation; chemical suppression)

80 - 90% 16 - 18%(b)


Chemical suppression on unpaved haul roads

80 - 85% 2.4 - 3.6%(c)

NA – Not applicable

(a) The current watering measure is estimated to have a control efficiency of 75 percent, the additional control efficiency achievable due to the application of chemical suppression is therefore estimated to be in the range of 5 - 10 percent. This equates to an overall 20 to 40 percent reduction in current wheel generated emission estimates.

(b) It is assumed that 20 percent of Bengalla’s unrehabilitated overburden emplacement areas (245.74 hectares) are to remain inactive for 3 months (i.e. 49 hectares). Given a control efficiency in the range of 80 percent to 90 percent for interim stabilisation methods (e.g. chemical suppression, vegetation), the reduction in total emissions from wind erosion of overburden is estimated to be of the order of 16 percent to 18 percent.

(c) Although wind erosion of exposed areas is not in the top four activities, emission reductions for this source will be realised due to the application of chemical suppression on unpaved haul roads. Unpaved roads cover about 70 hectares, comprising approximately 30 percent of the exposed areas at the site (excluding overburden emplacement areas).

Annual emission reductions estimated due to the implementation of the additional control measures identified at Bengalla are presented in Table 4.7. These emission reductions were based on the emission estimates for the base case year (2011). Overall TSP emission reductions were estimated to be in the range of 447 to 865 tonnes per year; PM10 emission reductions in the range 158 to 300 tonnes per year; and PM2.5 emission reductions of the order of 17 to 32 tonnes per year.


Table 4.7 Annual emission reduction estimated due to implementation of the additional control measures identified at Bengalla

Rank OEH Mine Activity Category

Lower Bound Annual Emission Reduction Estimate

Upper Bound Annual Emission Reduction Estimate

TSP (kg/year)

PM10 (kg/year)

PM2.5 (kg/year)

TSP (kg/year)

PM10 (kg/year)

PM2.5 (kg/year)

1 Wheel Generated Dust (Unpaved Roads)

410,632 139,362

14,175

821,265

278,725

28,350

2 Truck Loading/Dumping of Overburden

- -

-

-

-

-

3 Bulldozing of Overburden

- -

-

-

-

-

4 Wind Erosion of Overburden

33,421 16,710

2,507

37,598

18,799

2,820

5 Wind Erosion of Exposed Areas

2,975 1,488

223

5,950

2,975

446

Total

447,028 157,560

16,905

864,813

300,499

31,616


5. Practicability of Additional Measures

5.1 Evaluation of Practicability

Potential additional control measures were workshopped by relevant safety, environment, approvals, mine planning, technical services and operations personnel, to identify potential risks associated with identified measures. Specific consideration was given to:

• Any restrictions on the implementation of such measures due to an existing approval or licence;

• New or additional environmental impacts that may arise from the application of the measures;

• Safety implications; • Implementation costs; • Regulatory requirements; • Incompatibility with current operational practices; and • Incompatibility with future development proposals on the premises.

Conclusions reached regarding the practicability of measures, and factors to consider in the implementation of such measures, are summarised in Table 5.1.

Table 5.1 Summary of additional control measures identified, and associated control efficiencies, where quantifiable

OEH Mining Activity

Category Additional Control

Measures Conclusions Regarding Practicability and

Considerations for Implementation

Wheel Generated Dust (Unpaved Roads) Wind Erosion of Exposed Areas (Unpaved Roads)

Primary measure: Chemical suppression on unpaved haul roads Supporting measures: Documentation of the haul road management program for consistent implementation Measurement of dust control effectiveness, e.g. through the use of dust monitors

Measure is considered practicable taking into account: anticipated costs; application of the measure at other coal mines; compatibility with current and future operational practices; and availability of product types on the market which have records of their not posing a risk to human health and the environment. A product will need to be identified and an application strategy devised to ensure:

• Compatibility with Bengalla’s haul roads; • No additional risks in terms of road safety; • Product poses no risks to human health and the

environment; and • Achievement of a control efficiency of at least 80%

(as demonstrated through particulate matter measurement).

Findings of ACARP Project C20023, Improvement of Haul Road Dust Emission Estimation and Controls at Coal Mines, will be reviewed when available to support implementation of this measure. The chemical suppression measure should be integrated within a coherent haul road management system.


OEH Mining Activity


Measures Conclusions Regarding Practicability and

Considerations for Implementation


Interim stabilisation (e.g. vegetation; chemical suppression)

Measure is considered practicable taking into that hydromulching has successfully been used at the site, and that Bengalla plans to increase the use of hydromulching to address dust emissions from temporarily inactive exposed areas. The potential application of chemical suppression, particularly for steep areas, is also considered practicable. This conclusion is reached taking into account: anticipated costs; application of the measure at other sites; and availability of product types which are environmentally benign. In the event that chemical suppression is applied a product will need to be identified and an application strategy devised to ensure:

• Product poses no risks to human health and the environment; and

• Surface coverage can be achieved to provide a control efficiency of at least 80%.

Aerial seeding may not be suitable for application at Bengalla given that this technique is more suitable for larger areas.

5.2 Best Practice Measures Selected for Implementation

All additional control measures identified were concluded to be practicable, as indicated in Table 5.1, and will be implemented by Bengalla to reduce particulate matter emissions. The implementation timeline for such measures is provided in Section 6.


6. Implementation Timeline Tasks to be undertaken for the implementation of the additional control measures identified are outlined in Table 6.1, and the timeline for implementing such tasks specified.


Table 6.1 Tasks and implementation timelines for the application of additional control measures at Bengalla

OEH Mining Activity Category

Additional Control Measures Tasks Implementation Timeline

Wheel Generated Dust (Unpaved Roads) Wind Erosion of Exposed Areas (Unpaved Roads)

Primary measure: Chemical suppression on unpaved haul roads Supporting measures: Documentation of the haul road management program for consistent implementation Measurement of dust control effectiveness, e.g. through the use of dust monitors

Identify a product and devise an application strategy. February – 30 June 2012

Identify a method of measuring the dust control effectiveness appropriate for haul roads.

February – 30 June 2012

Undertake dust measurement to establish the control effectiveness achieved by chemical suppression, and compare with the dust control efficiency target of 80 percent.

July – 30 September 2012

Documentation of the haul road management program.

July – 30 September 2012

Application of chemical suppression, integrated within the site’s haul road management program.

October 2012 onwards

Review findings of ACARP Project C20023, Improvement of Haul Road Dust Emission Estimation and Controls at Coal Mines, when available, to further support implementation of this measure.

Date dependent on study completion.


OEH Mining Activity


Measures Tasks Implementation Timeline


Interim stabilisation through vegetation and/or chemical suppression

Review currently exposed overburden emplacement areas to assess: • the period over which such areas are to remain inactive • material and surface characteristics (moisture content; particle

size distribution; evidence of crusting), • exposure to prevailing winds, and • proximity to environmental receivers.

February – June 2012

Establish and implement the most suitable interim stabilisation methods to the currently exposed overburden emplacement areas identified (e.g. hydromulching, chemical stabilisation, direct seeding, aerial seeding).

February – December 2012

Determine a suitable time limit for inactive overburden emplacement areas with dust generation potentials to remain exposed, following which interim stabilisation is required.


Establish timelines within which interim stabilisation measures are to be applied for future years (e.g. time periods in the range of 1-3 months are practicable for chemical suppression; and 3-6 months for vegetation, depending on what time of the year areas become available for vegetation).


Establish a process whereby mine planning identifies, on a monthly basis, areas available for application of interim dust suppression measures. Include this accountability in relevant procedures.

July – December 2012

On-going monthly identification of areas for interim stabilisation, and implementation of such stabilisation within established timelines.

January 2013 onwards


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Midwest Research Institute (2006). Background Document for Revisions to Fine Fraction Ratios used for AP-42 Fugitive Dust Emission Factors, MRI Project No. 110397, Western Governors' Association, Western Regional Air Partnership (WRAP).

Nichols W. (2004). Development of Rehabilitation Completion Criteria for Native Ecosystem Establishment on Coal Mines in the Bowen Basin, ACARP Project No. C1204501/05/2004.

NIOSH (2005). Technology news 512: Improve drill dust collector capture through better shroud and inlet configurations. Pittsburgh, PA: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 2006–108.

NIOSH (2010). Best Practices for Dust Control in Coal Mining, Pittsburgh, PA: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 2010-110, Information Circular 9517, 2010 Jan; :1-76.

NPI EETM (1999). National Pollutant Inventory, Emission Estimation Technique Manual for Fugitive Emissions, December 1999, Environment Australia.

NPI EETM (2000). National Pollutant Inventory, Emission Estimation Technique Manual for Mining and Processing of Non-Metallic Minerals, Version 2.0, August 2000, Environment Australia.

NPI EETM (2001). National Pollutant Inventory, Emission Estimation Technique Manual for Mining, Version 2.3, December 2001, Environment Australia.

NPI EETM (2008). National Pollutant Inventory, Emission Estimation Technique Manual for Explosives Detonation and Firing Ranges, Version 2.0, January 2008, Environment Australia.


NPI EETM (2011). National Pollutant Inventory, Emission Estimation Technique Manual for Mining, Version 3.0, Environment Australia.

OEH (2011). Coal Mine Particulate Matter Control Best Practice – Site Specific Determination Guideline, NSW Office of Environment and Heritage, November 2011.

Ohio EPA (1980). Reasonably Available Control Measures for Fugitive Dust Sources. Office of Air Pollution Control, Division of Engineering, Columbus OH, 43216. NTIS Report No. PB82-103805

PAEHolmes (2010). Air Quality Assessment for the Bengalla Consent Modification.

Park C.W., Lee S.J. (2002). Verification of the Shelter Effect of a Windbreak on Coal Piles in the POSCO Open Storage Yards at the Kwang-Yang works, Atmospheric Environment, 36, 13, 2171-2185.

Planner J. (2010). Coal Dust Control Techniques – Review of Current Practice, ACARP Project C19007, Published 1 May 2010.

Queensland EPA (1995). Technical Guidelines for the Environmental Management of Exploration and Mining in Queensland.

Personal communication, Danny Brooks, Dragline Drill & Blast Superintendent, Bengalla.

Personal communication, Mitchell Bennett, Office of Environment and Heritage, 10 October 2011.

Personal communication, Mitchell Bennett, Office of Environment and Heritage, 27 January 2012.

Pitts O. (2005). Improvement of NPI Fugitive Particulate Matter Emission Estimation Techniques, Final Report, Sinclair Knight Merz, RFQ No. 0027/2004.

Reed W.R., Organiscak J.A., Page S.J. (2004). New approach controls dust at the collector dump point, Engineering Mining Journal, 205(7), 29–31.

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SPCC (1986). Particle Size Distributions in Dust from Open Cut Coal Mines in the Hunter Valley, Report Number 10636-002-71, State Pollution Control Commission of NSW, 1986

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Stevenson T. (2004). Dust Suppression on Wyoming’s Coal Mine haul Roads, Recommended Practices and Best Available Control Measures (BACT), A Manual, Prepared for Industries of the Future Converse Area new Development, October 2004.

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BMC BMP Determination 22 Feb 2012.docx Page A-1

Appendix A

Cost Information for Best Practice Measures

BMC BMP Determination 22 Feb 2012.docx Page A-2

According to the NSW Environmental Protection Agency (EPA), the cost information referred to in the OEH Guideline is required to verify that a particular best practice measure is not practicable for implementation at a mine site. In subsequent advice provided, the EPA indicated that any licensee may choose not to submit cost information for best practice measures that are either currently being implemented, or that are considered by the licensee to be practicable (personal communication, Mitchell Bennett, Head, Regional Operational Unit – Hunter, NSW EPA, 27 January 2012).

Given that all best practice measures identified as being additional to Bengalla’s current practices are to be adopted for implementation by Bengalla, the costing of measures is not required.

BMC BMP Determination 22 Feb 2012.docx Page B-1

Appendix B

Emission Estimation Method


Appendix B - Emission Estimation Method The emission estimation method for the study was developed by ENVIRON Australia (Pty) Ltd, in consultation with the Office of Environment and Heritage (OEH).

Annual TSP, PM10 and PM2.5 emissions (tpa) were estimated for each mining activity utilising USEPA AP42 emission estimation techniques, and taking into account site-specific material properties, meteorology, mine activities and activity rates and current control measures.

The emission estimation method comprised the following main steps:

• Selection of suitable emission factor equations, in consultation with OEH (Section B.1).

• Collation of the site-specific material property and meteorological data required as input to equations (Section B.2).

• Calculation of site-specific emission factors for uncontrolled activities (Section B.3).

• Designation of pit retention factors for sources taking place within the open cut pit (Section B.4).

• Collation of site-specific mine activity data for the base case year 2011 (Section B.5).

• Identification of controls measures for which control factors can be assigned (Section B.6)

• Quantification of uncontrolled emissions for the base case year 2011, taking into account pit retention and natural attenuation due to rainfall (Section B.7).

• Quantification of emissions given current controls for the base case year 2011 (Section B.8).

Whereas detailed emission estimates are provided within this appendix, a summary of the emission projections by OEH-defined activity category is given within the main report.

B.1 Emission Factor Equations Applied

Unpaved Roads

The emissions factor for unpaved roads is taken from USEPA AP42 Chapter 13.2.2 Unpaved Roads (November 2006) as follows:

E = k (s/12)a(W/3)b

Where:

E = Emissions Factor (lb/VMT, i.e. pounds per vehicle miles travelled)

s = surface material silt content (%)

W = mean vehicle weight (Short Tonnes US).


The following constants are applicable:

Constant TSP (based on PM30) PM10 PM2.5

K (lb/VMT) 4.9 1.5 0.15

A 0.7 0.9 0.9

B 0.45 0.45 0.45

The metric conversion from lb/VMT to g/VKT (grams per vehicle kilometre travelled) is as follows:

1 lb/VMT = 0.2819 kg/VKT

The surface material silt content and mean vehicle weight information is site specific as documented in the following section.

Rainfall Adjustment Factor

All roads are subject to some natural mitigation due to precipitation. The above unpaved road emission factor can be extrapolated to annual average uncontrolled conditions (but including natural mitigation dur to precipitation) under the simplifying assumption that annual average emissions are inversely proportional to the number of days with measureable (more than 0.254 mm) precipitation as follows:

Eext = E [(365-P)/365]

where:

Eext = annual size-specific emission factor extrapolated for natural mitigation (lb/VMT)

E = unpaved road emission factor (given above)

P = number of days in a year with at least 0.254 mm of precipitation

Paved Roads

The emissions factor for paved roads is taken from USEPA AP42 Chapter 13.2.1 Paved Roads (January 2011) as follows:

E = k (sL)0.91(W)1.02

Where:

E = Emissions Factor (g/VKT, i.e. grams per vehicle kilometre travelled)

K = particle size multiplier for particle size range and units of interest (See table below)

sL = Road surface silt loading (grams per square meter) (g/m2), and


W = mean vehicle weight (tonnes)

The following constants are applicable:

Constant TSP (based on PM30) PM10 PM2.5

K 3.23 0.62 0.15

Questions have been raised in regard to the accuracy of the January 2011 revision of the Paved Road equation. OEH has however indicated that emission factors from AP42 Section 13.2.1 January 2011 should be used in the quantification of paved road emissions since this is official USEPA guidance (personal communication, Mitchell Bennett, Office of Environment and Heritage, 10 October 2011).

The road surface silt loading and mean vehicle weight information is site specific as documented in the following section.

Topsoil Scraper

The emissions factors for topsoil scraping activities are taken from USEPA AP42 Chapter 11.9 Western Surface Coal Mining (October 1998) as documented in the table below. No PM10 and PM2.5 factors defined for this activity, with reference made to the PM10/TSP and PM2.5/TSP ratios specified for this activity within the OEH 2008 GMR Emissions Inventory. The emission factors are expressed in kilograms of emissions per tonne of material (topsoil) stripped.

Activity TSP PM10 PM2.5 Units

Topsoil stripping 0.029 TSP*0.32 TSP x 0.0468 kg/tonne

Scraper unloading (batch drop)

0.02 TSP*0.32 TSP x 0.0468 kg/tonne

Dragline

The emissions factors for dragline activities are taken from USEPA AP42 Chapter 11.9 Western Surface Coal Mining (October 1998) as documented in the table below. The emission factors are expressed in kg of emissions per bulk cubic metre of material (overburden) moved.

TSP PM10 PM2.5 Units

0.0046(𝑑)1.1

(𝑀)0.3

0.0029(𝑑)0.7

(𝑀)0.3 × 0.75

0.0046(𝑑)1.1

(𝑀)0.3 × 0.017 kg/m³

Where: d = drop height (m)

M = material moisture content (%)


The average drop height and material moisture content is site specific and is provided in the next section.

Blasting

Emissions factors for blasting are taken from USEPA AP42 Chapter 11.9 Western Surface Coal Mining (October 1998) as documented in the table below. The emission factors are expressed in kilogram of emissions per blast, with a single emissions factor specified for blasting of coal and overburden.

Material TSP PM10 PM2.5 Units

Overburden or Coal 0.00022(A)1.5 TSP x 0.52 TSP x 0.03 kg/blast

Where: A= horizontal area (m2) with blasting depth ≤ 21.

The average blast area is site specific and is addressed in the subsequent section.

Drilling

The TSP emissions factors for drilling activities are taken from USEPA AP42 Chapter 11.9 Western Surface Coal Mining (October 1998) as documented in the table below. The emission factors are expressed in kilogram of emissions per hole drilled, with separate factors specified for drilling of coal and overburden. Given that there are no PM10 and PM2.5 emissions factors for drilling, the PM10 and PM2.5 to TSP ratios for blasting overburden and coal were applied.


Overburden 0.59 TSP x 0.52 TSP x 0.03 kg/hole

Coal 0.1 TSP x 0.52 TSP x 0.03 kg/hole The number of holes is site specific and is addressed in the subsequent section.

Bulldozing

The emissions factors for bulldozing activities are taken from USEPA AP42 Chapter 11.9 Western Surface Coal Mining (October 1998) as documented in the table below. The emission factors are expressed in kilogram of emissions per hour of dozer activity, with separate factors specified for dozers operating on coal and overburden.


Overburden 2.6(𝑠)1.2

(𝑀)1.3

0.45(𝑠)1.5

(𝑀)1.4 × 0.75 2.6(𝑠)1.2

(𝑀)1.3 × 0.105 kg/hr

Coal 35.6(𝑠)1.2

(𝑀)1.3

8.44(𝑠)1.5

(𝑀)1.4 × 0.75 35.6(𝑠)1.2

(𝑀)1.3 × 0.022 kg/hr

Where: s = material silt content (%)

M = material moisture content (%)


The material silt content and material moisture content are site specific and are addressed in the subsequent section.

Trucks Loading Coal and Overburden

The emissions factors for truck loading are taken from USEPA AP42 Chapter 11.9 Western Surface Coal Mining (October 1998) as documented in the table below. These emission factors, expressed in kilogram of emissions per metric tonne of material loaded, are applicable for operations involving loading by shovels, excavator or front end loaders. In the case of truck loading of overburden, this chapter only specifies a TSP emission factor. To derive PM10 and PM2.5 emissions factors for truck loading of overburden, reference was made to the PM10/TSP and PM2.5/TSP ratios for bulldozing of overburden.


Coal 0.58

(𝑀)1.2

0.0596(𝑀)0.9

× 0.75 TSP x 0.019 kg/Mg

Overburden (a) 0.018 𝑇𝑆𝑃 × 0.29 TSP x 0.105 kg/Mg

(a) See justification for use of this emission factor provided below.

Where: M = material moisture content (%)

The material moisture content is site specific and are provided in the subsequent section.

OEH recommended that the material handling emission factor equation from USEPA AP42 Chapter 13.2.4 Aggregate Handling and Storage Piles (November 2006) be applied in the estimation of truck loading of overburden (as documented below) (personal communication, Mitchell Bennett, Office of Environment and Heritage, 10 October 2011). Although this emission factor equation, which takes into account the site-specific wind speed, was initially applied it was found to substantially under predict the emissions from this activity for the site when site-specific wind data was applied. This confirmed the conclusion reached by Pitts (2005) that there is an apparent large underestimation in emissions when using the materials handling equation compared to measurements at Australian mines.

The AP42 materials handling equation gives lower dust emissions when compared to measurements undertaken during Australian research (NERDCC, 1988 and SPCC, 1983), and earlier US research (1981). Holmes (1998) indicated that this is likely to be due to earlier equations treating the entire loading operation as a single operation. The entire operation comprises the use of a shovel/excavator or front end loader scooping up a load, moving into a loading position, dumping material into a truck, reloading and repeating the process. The materials handling equation by comparison considers the batch or continuous load-out operation in isolation, and is therefore more applicable for estimating emissions for conveyor transfers or loading from a conveyor to a stockpile.

To provide a more realistic (potentially upper bound) estimate of emissions from trucks loading overburden reference was therefore made to the default emission factor from USEPA AP42 Chapter 11.9 Western Surface Coal Mining (October 1998) as documented in the table above.


Trucks Dumping Coal and Overburden

The emissions factors for trucks dumping of coal are taken from USEPA AP42 Chapter 11.9 Western Surface Coal Mining (October 1998) as documented in the table below. The emission factors are expressed in kilogram of emissions per metric tonne of material dumped.

In the case of trucks dumping overburden, reference is made to the materials handling equation from USEPA AP42 Chapter 13.2.4 Aggregate Handling and Storage Piles (November 2006) as recommended by OEH. Whereas the default ‘truck loading overburden’ emission factor was applied to more comprehensively account for the entire loading process, the truck dumping of overburden represents a more simple batch drop process render in the use of the material handling equation for its quantification appropriate.


Coal (a) 0.58

(𝑀)1.2

0.0596(𝑀)0.9

× 0.75 TSP x 0.019 kg/Mg

Overburden Refer to the Materials Handling Equation (b)

(a) AP42 Chapter 11.9 gives a default TSP emission factor for truck dumping of coal (0.033 kg/Mg). OEH however recommended that the emission factors for trucks loading coal be applied, as drawn from this chapter of the AP42 and documented above (personal communication, Mitchell Bennett, Office of Environment and Heritage, 10 October 2011).

(b) AP42 Chapter 11 gives a default TSP emission factor for truck dumping of overburden (0.001 kg/Mg). OEH however recommended that the materials handling equation from USEPA AP42 Chapter 13.2.4 Aggregate Handling and Storage Piles (November 2006) be applied in the estimation of trucks dumping overburden (personal communication, Mitchell Bennett, Office of Environment and Heritage, 10 October 2011).

The material moisture content (%) specified in the above equation is site specific and is provided in the subsequent section.

Grading

Emissions factors for grading are taken from USEPA AP42 Chapter 11.9 Western Surface Coal Mining (October 1998) as documented in the table below. The emission factors are expressed in kilogram of emissions per vehicle kilometre travelled (VKT).


0.0034 (S)2.5 0.0056 (S)2.0 x 0.6 TSP x 0.031 kg/VKT

Where:

VKT= Vehicles Kilometres Travelled

S = mean vehicle speed (km/h)


The mean vehicle speed of the grader when operating is site specific and is documented in the subsequent section.

Materials Handling

Reference was made to the materials handling equation from USEPA AP42 Chapter 13.2.4 Aggregate Handling and Storage Piles (November 2006) for the quantification of emissions from the following batch and continuous drop operations:

• Trucks dumping overburden • Conveyor transfer points • Stacking to stockpiles This equation is expressed as follows:

𝐸 = 𝑘 0.0016 �𝑈

2.2�1.3

�𝑀2�−1.4

Where:

E = Emissions factor (kg/Mg)

k = 0.74 for particles less than 30 micrometres

k = 0.35 for particles less than 10 micrometres

k = 0.053 for particles less than 2.5 micrometres

U = mean wind speed (m/s)

M = material moisture content (%).

The mean wind speed and material moisture content are site specific and are documented in the subsequent section.

Crushing and Screening of Coal

No specific emission factors are given for coal crushing and screening operations within AP42 or within other widely referenced emission estimation methodologies. A conservative approach (i.e. expected to provide an upper bound emission estimate) is adopted in which reference is made to emissions factors for crushing and screening contained within USEPA AP42 Chapter 11.24 Metallic Minerals Processing (January 1995). The emissions factors from this chapter are documented for high moisture content and low moisture content ores, with high moisture content defined as being greater than or equal to 4 percent by weight.

According to USEPA AP42 Chapter 11.24, a single crushing operation is likely to include a hopper or ore dump, screen(s), crusher, surge bin, apron feeder, and conveyor belt transfer points, with emissions from these various pieces of equipment frequently being ducted to a single control device. The emission factors provided for in USEPA AP42 Chapter 11.24 for primary, secondary, and tertiary crushing operations are for process units that are typical arrangements of the aforementioned equipment. For this reason the emission factors for crushing were taken to be applicable for the quantification of coal crushing and screening operations.


No PM2.5 factors are given within USEPA AP42 Chapter 11.24, reference was therefore made to the PM2.5 fraction specified for Category 3 emissions within USEPA AP42 Appendix B.2 Generalized Particle Size Distribution (January 1995). Category 3 covers materials handling and processing of aggregate and unprocessed ore, including emissions from milling, grinding, crushing, screening, conveying, cooling, and drying of material.

A summary of the emission factors applied for coal crushing and screening operations is given in the table below, expressed as kilograms of emissions per metric tonne of coal.

Material Process TSP PM10 PM2.5 Units

High moisture coal (≥4% wt)

Primary Crushing 0.01 0.004 TSP x 0.15 kg/Mg

Secondary Crushing 0.03 0.012 TSP x 0.15 kg/Mg

Tertiary Crushing 0.03 0.01 TSP x 0.15 kg/Mg

Low moisture coal (<4% wt)

Primary Crushing 0.2 0.02 TSP x 0.15 kg/Mg

Secondary Crushing 0.6 0.24(b) TSP x 0.15 kg/Mg

Tertiary Crushing 1.4 0.08 TSP x 0.15 kg/Mg

Wind Erosion of Overburden Emplacement Areas and Other Exposed Areas

The TSP emissions factor taken from the USEPA AP42 Chapter 11.9 Western Surface Coal Mining (October 1998) was applied in the quantification of wind blown dust from overburden emplacement areas and other exposed areas (but excluding coal stockpiles). In designating PM10 and PM2.5 emission factors, reference was made to the PM10/TSP and PM2.5/TSP ratios specified within USEPA AP42 Chapter 13.2.5 Industrial Wind Erosion (November 2006). Emission factors, expressed in metric tonnes per hectare of exposed area per year (Mg/ha/yr), are given in the table below.


0.85 TSP x 0.5 TSP x 0.075 Mg/ha/yr

The TSP emission factor is specified for seeded land, stripped overburden and graded overburden. This factor was derived based on upwind downwind sampling of exposed areas at coal mines in the US. Pitts (2005) noted that these coal mines, documented within the background document to USEPA AP42 Chapter 11.9 Western Surface Coal Mining (October 1998), are located within reasonably dry areas (rainfall in the range of 280 to 430 mm/year) characterised by relatively high wind speeds (four sites with average wind speeds of 4.8 to 6 m/s, and one with 2.3 m/s). Pitts (2005) therefore concluded that the equation appears to be based on reasonably dry and windy sites.


The above emission factors are applied in the assessment of wind erosion from shaped and unshaped overburden emplacement areas, including freshly placed areas, graded areas and seeded areas. The factors are also applied to vegetated overburden emplacement areas, with control factors being taken into account contingent upon the level of vegetation coverage achieved.

These emission factors are also applied in the quantification of wind blown dust from other general exposed areas, such as unsealed roads, active mining areas and topsoil stockpiles. Wind erosion of coal stockpiles is however not quantified using these factors.

Wind Erosion of Active Coal Stockpile

A TSP emission factor for active coal storage piles is given in USEPA AP42 Chapter 11.9 Western Surface Coal Mining (October 1998) as follows:

ETSP = 1.8 x u

Where:

ETSP = TSP emissions in kg/ha/hr (kilograms per hectare per hour)

U = mean wind speed (m/s)

The above emission factor is however given for wind erosion and stockpile maintenance. The Mining Activities defined by OEH for BMP determination purposes lists specifically wind erosion of coal stockpiles, with dozers on coal being defined as a separate activity. This distinction is understandable given that separate measures may be applied to address particular emissions arising from wind erosion of stockpiles and maintenance of such stockpiles by mobile equipment. Given that the above emission factor does not distinguish between wind erosion and maintenance emissions, an alternative approach was adopted. Bulldozer operations were addressed using the bulldozer on coal emission factors documented previously.

Wind blown dust from coal stockpiles was estimated by applying the complex, predictive emission estimation procedure documented within USEPA AP42 Chapter 13.2.5 Industrial Wind Erosion (November 2006) as described below.

The predictive emission factor equation for industrial wind erosion is given as follows:

𝐸𝑚𝑖𝑠𝑠𝑖𝑜𝑛 𝑓𝑎𝑐𝑡𝑜𝑟 = 𝑘�𝑃𝑖𝑁

𝑖=1

Where,

k = particle size multiplier (k = 1 for TSP, 0.5 for PM10 and 0.075 for PM2.5)

N = number of disturbances per year

Pi = erosion potential corresponding to the observed (or probable) fastest mile of wind for the ith period between disturbances (g/m²), calculated by:

P = 58(u* - ut*)2 + 25(u* - ut*)

P = 0 for u* ≤ ut*


Where,

u* = friction velocity (m/s)

ut* = threshold friction velocity (m/s)

The following steps were followed in applying this equation:

Step 1 – The fastest mile of wind was determined between disturbances.

The coal stockpiles were conservatively assumed to be subject to disturbance on a continuous (hourly) basis to provide an upper bound estimate of emissions (i.e. N=8760). Emissions were calculated on an hourly basis for the base case emission inventory year based on measured site-specific wind speed data for this year.

The fastest mile of wind was calculated from the hourly average wind speed based on the gust factor range documented by Pitts (2005) drawing on the work of Krayer and Marshall (1992). Fastest mile wind speeds are given by Pitts (2005) as being in the range of approximately 1.18 to 1.27 times the hourly wind speed. A factor of 1.27 was used to provide an upper bound estimate of emissions.

Step 2 – The friction velocity was derived for several stockpile sub-areas to account for different wind exposures.

Given that coal stockpiles typically penetrate the surface wind layer (i.e. piles with height-to-base ratios exceeding 0.2), it is necessary to consider that different areas of a stockpile have different exposures to the wind. The friction velocity (u*) must therefore be calculated taking into account the surface wind speed distribution (us

+) which is estimated as follows:

++ = 10uuuu

r

ss

where,

us+ = surface wind speed distribution

us = surface wind speed (m/s), measured at 25 cm from the pile’s surface

ur = approach wind speed (m/s), or reference wind speed measured at a height of 10 m.

𝑢10+ = gust wind speed at reference height of 10 m for periods between disturbances (m/s)

The shape of the pile and its orientation to the prevailing wind determine wind exposure patterns (us/ur ratios) at the pile surface. USEPA AP42 Chapter 13.2.5 Industrial Wind Erosion (November 2006) documents wind exposure patterns for two coal stockpile configurations based on wind tunnel studies undertaken. The two pile shapes are a conical pile and an oval pile with a flat top, both with 37 degree side slopes. Contours of normalised surface wind speeds (us/ur) for both pile shapes are illustrated Figure B.1, with provision made for differences in the contours for the oval, flat topped stockpile given different approach wind bearings. The percentage of the pile surface areas represented by us/ur ratio is given in the table below.


Figure B.1 Contours of normalised surface wind speed (us/ur) for conical and oval, flat topped stockpiles (after USEPA AP42 Chapter 13.2.5 Industrial Wind Erosion, November 2006)

Pile Sub-area (us/ur)

Percent of Pile Surface Area

Pile A Pile B1 Pile B2 Pile B3 Generic

0.2 40% 36% 31% 28% 27%

0.6 48% 50% 51% 54% 54%

0.9 12% 14% 15% 14% 15%

1.1 0% 0% 3% 4% 4%


Allowing for variations in actual stockpile shapes, a generic set of pile surface areas was established for application in the emission estimates (as shown in above table). In deriving this generic set reference was made to the maximum areas across stockpile types covered by sub-areas with higher us/ur ratios.

Based on the surface wind speed distribution (us+), the friction velocity (u*) was calculated for each pile

sub-area, taking into account the non-uniform wind exposure of stockpiles, by applying the following equation:

++

== ss uuu 10.0

)5.0ln

25(

4.0*

Step 3 – A threshold friction velocity was determined.

Reference was made to the literature to identify threshold friction velocities for use in the erosion potential calculations. Threshold friction velocities for coal piles are given as being in the range of 0.7 m/s to 1.12 m/s (USEPA, 1988; USEPA AP42 Chapter 13.2.5 Industrial Wind Erosion, November 2006; Sullivan and Ajwa, 2011). For the purpose of this assessment the lower threshold friction velocity of 0.7 m/s was applied.

Step 4 – Calculation of annual erosion potential for the entire pile

The erosion potential (P) was calculated for each stockpile sub-area, for each hour, based on the calculated friction velocity (u*) and the selected threshold friction velocity (ut*) as follows:

P = 58(u* - ut*)2 + 25(u* - ut*)

P = 0 for u* ≤ ut*

The erosion potentials were then summed across stockpile sub-areas and across hours to give the total annual erosion potential for the entire pile.


B.2 Site-specific inputs

Site-specific information input into the emission estimation calculations is provided in the table below.

Parameter Value Units Comments Material Properties Moisture Content of ROM Coal 9.5 % Sampling at Bengalla Moisture Content of Product Coal 11.0 % Sampling at Bengalla Moisture Content of Raw Coal 8.8 % Sampling at Bengalla Moisture Content of Road Material 1.0 % Sampling at Bengalla Moisture Content of Overburden 6.0 % Sampling at Bengalla Moisture Content Rejects 30.0 % Sampling at Bengalla Moisture Content of Topsoil 15 % Sampling at Bengalla Silt Content of ROM Coal 8.6 % USEPA AP42 Default for Coal Silt Content of Product Coal 8.6 % USEPA AP42 Default for Coal Silt Content of Topsoil 24.3 % Sampling at Bengalla Silt Content of Road Material 8.7 % Sampling at Bengalla Silt Content of Overburden Dumps 26.5 % Sampling at Bengalla Silt Content of Overburden Bulldozed 26.5 % Sampling at Bengalla

Meteorological Data Mean Wind Speed 1.97 m/s Based on 2010 Bengalla Tower wind

speed data at 10 m Time wind exceeds 5.4m/s 8.7 % Based on 90m Bengalla Tower data No of Rain Days (>0.25mm) 86.3 days Jerrys Plains PO Meteorological Station Wheel Generated Dust - Vehicles Grader Speed 7.5 km/hr Site-specific Weight of Grader 17.8 Tonnes Caterpillar 16H weight Weight of Haul Trucks 240 Tonnes Average weight across haul fleet (including

and excluding load) Weight of Light Vehicles 2 Tonnes Site-specific Weight of Fuel Trucks 33 Tonnes Site-specific Weight of Other Trucks 8 Tonnes Site-specific Dragline Drop height (uncontrolled) 10 m Assumed drop height if uncontrolled Drop height (controlled) 5 m Site-specific drop height

Rainfall Adjustment Rainfall adjustment for Road Dust (natural control due to rainfall)

0.764

Notes: Moisture content of coal represents average across a number of samples taken during the period January 2011 to November 2011 as follows:

Maximum Moisture Content (%)

Average Moisture Content (%)

Minimum Moisture Content (%) Total No. Samples

Product Coal 26.0 11.0 5.8 2544

Raw Coal 25.8 9.5 5.4 1456 Moisture and silt contents of unsealed road surface material, topsoil and overburden were determined based on grab sampling of in situ material and subsequent laboratory analysis by Simtars (the Safety in Mines Testing and Research Station, Department of Employment, Economic Development and Innovation). Reference was made to the procedures outlined in USEPA AP42 Appendix C.1 Procedures for Sampling Surface / Bulk Dust Loading (July 1993) and USEPA AP42 Appendix C.2 Procedures for Laboratory Analysis of Surface / Bulk Dust Loading Samples (July 1993).


Details regarding the samples taken and results obtained are as follows:

Location of Grab Samples:

Results by Sample:

Average Properties by Material Type: Material Type Moisture Content (%) Moisture Content (%) Unsealed road surface material 1 8.7

Topsoil 15 24.3 Overburden 6 26.5

No. Material Type Moisture Content (%) Silt Content (%) 1 Road surface material 1 5.8 2 Road surface material <1 11.5 3 Topsoil 15 24.3 4 Overburden 4 22.3 5 Overburden 8 36.4 6 Overburden 6 20.8


B.3 Site-specific Emission Factors (excluding Pit Retention and Controls)

Site-specific emission factors were calculated based on the equations presented in Section B.1 and taking into account the site-specific data listed in Section B.2. These emission factors, which exclude the effect of pit retention and control measure efficiencies, are as follows:

Source

Unit

Calculated Uncontrolled Emission Factor (Integrating Site-specific Data)

TSP PM10 PM2.5 Blasting Coal kg/blast 280 146 8 Blasting Overburden kg/blast 450 234 14 Bulldozing Coal kg/hr 25.22 6.83 0.55 Bulldozing Overburden kg/hr 12.92 3.75 1.36 Primary Crusher and Screening kg/tonne 0.010 0.004 0.00015 Secondary Crusher and Screening kg/tonne 0.03 0.012 0.00045 Tertiary Crusher and Screening kg/tonne 0.030 0.01 0.00045 Coal stockpiles (wind erosion) kg/ha/yr 792 396 59 Dragline (assuming uncontrolled drop height of 10 m) kg/BCM 0.03 0.006 0.00058 Drilling Coal kg/hole 0.10 0.052 0.003 Drilling Overburden kg/hole 0.59 0.31 0.02 Graders Working kg/VKT 0.52 0.189 0.02 Stacker loading coal stockpiles (Product) kg/tonne 0.00009 0.0000446 0.00001 Stacker loading coal stockpiles (Raw Coal) kg/tonne 0.00013 0.0000610 0.00001 Excavator/Loader loading overburden to trucks kg/tonne 0.018 0.0052 0.0019 Trucks Dumping Overburden kg/tonne 0.00022 0.0001042 0.00002 Product Coal Conveyor Transfers kg/tonne 0.00009 0.0000446 0.00001 Raw Coal Conveyor Transfers kg/tonne 0.00013 0.0000610 0.00001 Reject Conveyor Transfers kg/tonne 0.00002 0.0000109 0.00000 ROM Coal Conveyor Transfers kg/tonne 0.00012 0.0000548 0.00001 Scraper stripping topsoil kg/tonne 0.029 0.01 0.0014 Scraper unloading topsoil (batch drop) kg/tonne 0.020 0.01 0.0009 Train Loading Transfer Point kg/tonne 0.00009 0.0000446 0.00001 Excavator/Loader loading coal to trucks kg/tonne 0.0389 0.0059 0.00074 Trucks Dumping Coal (Hopper) kg/tonne 0.0389 0.0059 0.00074 Unloading Coal Stockpiles (Raw Coal) kg/tonne 0.00013 0.0000610 0.00001 Wheel Generated Dust (Unpaved Roads) – Fuel Trucks kg/VKT 2.477 0.711 0.071 Wheel Generated Dust (Unpaved Roads) - Haul Trucks kg/VKT 6.050 1.737 0.174 Wheel Generated Dust (Unpaved Roads) - Light Vehicles (<5 tonnes)

kg/VKT 0.702 0.201 0.020

Wheel Generated Dust (Unpaved Roads) - Other Trucks kg/VKT 1.309 0.376 0.038 Wind Erosion of Exposed Areas (active mining area; topsoil stockpiles)

kg / hectare / yr

850 425 64

Wind Erosion of Overburden Emplacement Areas kg / hectare / yr

850 425 64


B.4 Pit Retention Factors

Emission from mining activities situated within the open pit may be reduced due to so called ‘pit retention’. This factor is more significant for larger particles, whereas fine particles have longer atmospheric residence times and are less likely to be removed from the air by deposition or impaction in the near field even given their release within the confines of an open cut pit. The National Pollutant Inventory (NPI) Emission Estimation Technique Manual (EETM) Version 3.0 dated 2011 gives the pit retention factor as being 50 percent for TSP and 5 percent for PM10. These factors were applied to account for reductions in emission for activities occurring within the pit. No pit retention factor was applied for PM2.5.

The percentage emission reduction estimated for each activity based on the abovementioned pit retention factors and the extent to which activities occur within the pit are as follows:

Activity Extent to which Activity occurs within the Pit (as %)

Pit Retention (%) TSP PM10 PM2.5

Blasting Coal 30% activity in pit 15 2 0 Dozers on Coal 50% activity in pit 25 3 0 Dozers on Overburden 50% activity in pit 25 3 0 Dragline Overburden 100% in pit 50 5 0 Excavator/Loader loading overburden to trucks 50% activity in pit

25 3 0

Excavator/Loader loading coal to trucks 80% activity in pit 40 4 0 Haul Trucks on Haul Roads 40% activity in pit 20 2 0 Other Trucks on Haul Roads 30% activity in pit 15 2 0 Bengalla Open Pit 100% activity in pit 50 5 0

No pit retention factor was applied for other activities not listed in the above table.

Overall the application of the pit retention factor was estimated to reduce uncontrolled annual TSP emission estimates by 18.4 percent and PM10 estimates by 1.8 percent.


B.5 Site-specific Mine Activity Data for 2011

OEH Defined Categories Mine Activity Activity Input Parameters Activity Rates for 2011

Unit

Blasting Blasting Coal No. of coal blasts per year 27 No. Blasts/yr Blasting Blasting Coal Average horizontal area of a coal blast 11,755 m²/blast Blasting Blasting Overburden No. of overburden blasts per year 130 No. Blasts/yr Blasting Blasting Overburden Average horizontal area of an overburden

blast 16,120 m²/blast

Bulldozing Coal Wheel Dozers on Coal Operational hours per year of dozers on coal 2180 Hrs/yr Bulldozing Overburden Track Dozers on Overburden Operational hours per year of dozers on

overburden 27735 Hrs/yr

Coal Crushing and Screening Primary Crusher (CR101) Mass crushed per year - primary crusher 6825471 Tonnes/yr Coal Crushing and Screening Secondary Crusher (FB101) Mass crushed per year - secondary crusher 6825471 Tonnes/yr Coal Crushing and Screening Tertiary Crusher (CR102) Mass crushed per year - tertiary crusher 1365094 Tonnes/yr Coal stockpiles Emergency Stockpile Area of stockpile 1.00 Hectare Coal stockpiles Product Coal Stockpiles Area of stockpile 8.55 Hectare Coal stockpiles Raw Coal Stockpiles Area of stockpile 3.64 Hectare Dragline Dragline Overburden Volume of overburden handled per year 15288090 BCM /yr Drilling Drilling Coal No. holes drilled in coal per year 7854 No. holes Drilled Drilling Drilling Overburden No. holes drilled in overburden per year 51859 No. holes Drilled Graders Graders Working Vehicle kilometres travelled per year 115682 VKT/year Loading Coal Stockpiles Stacker loading coal stockpiles (Product Coal)

(SK802) Mass handled per year 2995610 Tonnes/yr

Loading Coal Stockpiles Stacker loading coal stockpiles (Product Coal) (SK801)

Mass handled per year 2885120 Tonnes/yr

Loading Coal Stockpiles Stacker loading coal stockpiles (Raw Coal) (SK101)


Loading/Dumping Overburden Excavator/Loader loading OB to trucks Mass handled per year 36004711 Tonnes/yr Loading/Dumping Overburden Trucks Dumping Overburden Mass handled per year 36004711 Tonnes/yr Material Transfer of Coal Product Coal Conveyor (CV805) Mass handled per year 2995610 Tonnes/yr Material Transfer of Coal Product Coal Conveyor (CV808) Mass handled per year 2995610 Tonnes/yr Material Transfer of Coal Product Coal Conveyor (CV806) Mass handled per year 2885120 Tonnes/yr Material Transfer of Coal Product Coal Conveyor (CV804) Mass handled per year 2885120 Tonnes/yr Material Transfer of Coal Product Coal Conveyor (CV810) Mass handled per year 5376483 Tonnes/yr Material Transfer of Coal Product Coal Conveyor (CV801) Mass handled per year 3946100 Tonnes/yr Material Transfer of Coal Product Coal Conveyor (CV809) Mass handled per year 2995610 Tonnes/yr Material Transfer of Coal Product Coal Conveyor (CV807) Mass handled per year 2885120 Tonnes/yr Material Transfer of Coal Product Coal Conveyor (CV820) Mass handled per year 1430383 Tonnes/yr Material Transfer of Coal Raw Coal Conveyor (CV105 – SK101) Mass handled per year 5995430 Tonnes/yr


OEH Defined Categories Mine Activity Activity Input Parameters Activity Rates for 2011

Unit

Material Transfer of Coal Raw Coal Conveyor (CV302 – raw coal to surge bin)


Material Transfer of Coal Raw Coal Conveyor (CV401 – Mod 1 feed) Mass handled per year 2632390 Tonnes/yr Material Transfer of Coal Raw Coal Conveyor (CV501 – Mod 2 feed) Mass handled per year 2632390 Tonnes/yr Material Transfer of Coal Raw Coal Conveyor (CV301 – direct feed) Mass handled per year 830041 Tonnes/yr Material Transfer of Coal Reject Conveyor (CV702) Mass handled per year 1728290 Tonnes/yr Material Transfer of Coal Reject Conveyor (CV703) Mass handled per year 1728290 Tonnes/yr Material Transfer of Coal Reject Conveyor (CV701) Mass handled per year 345658 Tonnes/yr Material Transfer of Coal ROM Coal Conveyor (CV102) Mass handled per year 6825471 Tonnes/yr Material Transfer of Coal ROM Coal Conveyor (CV104) Mass handled per year 6825471 Tonnes/yr Scrapers Scraper stripping and loading topsoil Mass of topsoil stripped per year 184,800 Tonnes/yr Train Loading Train Loading Transfer Point (BN101) Mass handled per year 6825471 Tonnes/yr Train Loading Train Loading Transfer Point (BN802) Mass handled per year 5376483 Tonnes/yr Train Loading Train Loading Transfer Point (BN301) Mass handled per year 5264780 Tonnes/yr Train Loading Train Loading Transfer Point (BN701) Mass handled per year 1728290 Tonnes/yr Trucks Loading Coal Excavator/Loader loading coal to trucks Mass handled per year 8330870 Tonnes/yr Trucks Unloading Coal Trucks Dumping Coal (Hopper) Mass handled per year 8330870 Tonnes/yr Unloading Coal Stockpiles Reclaimer on coal stockpiles (RC301) Mass handled per year 4462170 Tonnes/yr Unloading Coal Stockpiles Reclaimer on coal stockpiles (RC802) Mass handled per year 2995610 Tonnes/yr Unloading Coal Stockpiles Reclaimer on coal stockpiles (RC801) Mass handled per year 2885120 Tonnes/yr Wheel Generated Dust (Unpaved Roads) Fuel Trucks on Unsealed Roads Vehicle kilometres travelled per year 294000 VKT/year

Wheel Generated Dust (Unpaved Roads) Haul Trucks on Unsealed Roads Vehicle kilometres travelled per year 1305146 VKT/year

Wheel Generated Dust (Unpaved Roads)

Light Vehicles (<5 tonnes) on Unsealed Roads

Vehicle kilometres travelled per year 982738 VKT/year

Wheel Generated Dust (Unpaved Roads) Other Trucks on Unsealed Roads Vehicle kilometres travelled per year 429240 VKT/year

Wind Erosion of Exposed Areas Bengalla Pit Area of open pit 203.67 Hectare Wind Erosion of Exposed Areas Haul Roads Area of unpaved road network 70 Hectare Wind Erosion of Exposed Areas Topsoil Stockpiles Area of topsoil stockpiles 18.20 Hectare Wind Erosion of Overburden Overburden Dumps (unrehabilitated) Area of unrehabilitated overburden

emplacement areas 245.74 Hectare


B.6 Current Control Measures and Associated Control Efficiencies

OEH Defined Categories Mine Activity Controls for which Control Efficiencies could be Established(a)

Control Effectiveness (%) TSP PM10 PM2.5

Coal Crushing and Screening Primary Crusher (CR101) Enclosed with water sprays(b) 87.5 87.5 87.5 Coal Crushing and Screening Secondary Crusher (FB101) Enclosed with water sprays(b) 87.5 87.5 87.5 Coal Crushing and Screening Tertiary Crusher (CR102) Enclosed with water sprays(b) 87.5 87.5 87.5 Coal stockpiles Product Coal Stockpiles Water sprays 50 50 50 Dragline Dragline Overburden Minimise drop height to within 5 metres(c) 53 38 53 Drilling Drilling Coal Dust suppression system 70 70 70 Drilling Drilling Overburden Dust suppression system 70 70 70 Loading Coal Stockpiles Stacker loading coal stockpiles Water sprays and variable height stackers(d) 62.5 62.5 62.5 Material Transfer of Coal Conveyors Enclosed/partially enclosed conveyors 70 70 70 Train Loading Train Loading Transfer Points Retractable chute 70 70 70 Trucks Unloading Coal Trucks Dumping Coal (Hopper) Enclosed (roof, 3 sides) with automated water curtain(e) 85 85 85 Wheel Generated Dust (Unpaved Roads) Truck and Vehicle Traffic Wet suppression(f) 75 75 75 Wind Erosion of Exposed Areas Haul Roads Wet suppression(f) 75 75 75 Wind Erosion of Exposed Areas Topsoil Stockpiles Rehabilitation (100% stability ratio) 90 90 90

Notes: (a) Control efficiencies were derived from the NPI EETM Mining (2011), and the USEPA AP42 Emission Factor literature unless specified otherwise. (b) Crushers are enclosed with internal water sprays. A control efficiency of 75 percent was applied for enclosure, and an additional 50 percent control efficiency for water sprays, giving a combined control efficiency of 87.5 percent. (c) The control effectiveness of reducing the dragline drop height from 10m to 5m was estimated by varying the drop height within the dragline emission factor. (d) A control efficiency of 50 percent was applied for water sprays, and an additional 25 percent control efficiency for the use of variable height stackers, giving a combined control efficiency of 62.5 percent. (e) A control efficiency of 70 percent was applied for hopper enclosure (3 sides and roof), and an additional 50 percent control efficiency for the use of automated water sprays, giving a combined control efficiency of 85 percent. (f) A control efficiency of approximately 75 percent was calculated based on the site’s haul road watering practices (refer to Appendix C); this coincides with the control efficiency specified in NPI EETM Mining (2011) for Level 2 watering, and with the maximum control efficiency indicated by the USEPA (2006) to be achievable through wet suppression.


B.7 Uncontrolled Emissions for Base Case Year 2011 (taking Pit Retention and Natural Attenuation due to Rainfall into Account)

OEH Defined Categories Mine Activity Uncontrolled Emissions (kg/year)

TSP PM10 PM2.5

Blasting Blasting Coal 6,435 3,878 227

Blasting Blasting Overburden 58,534 30,437 1,756

Bulldozing Coal Wheel Dozers on Coal 41,241 14,514 1,210

Bulldozing Overburden Track Dozers on Overburden 268,758 101,336 37,626

Coal Crushing and Screening Primary Crusher (CR101) 68,255 27,302 1,024

Coal Crushing and Screening Secondary Crusher (FB101) 204,764 81,906 3,071

Coal Crushing and Screening Tertiary Crusher (CR102) 40,953 13,651 614

Coal stockpiles Emergency Stockpile 792 396 59

Coal stockpiles Product Coal Stockpiles 6,768 3,384 508

Coal stockpiles Raw Coal Stockpiles 2,881 1,441 216

Dragline Dragline Overburden 258,604 92,489 8,793

Drilling Drilling Coal 785 408 24

Drilling Drilling Overburden 30,597 15,910 918

Graders Graders Working 60,590 21,864 1,878

Loading Coal Stockpiles Stacker loading coal stockpiles (Product Coal) (SK802) 282 134 20


Loading Coal Stockpiles Stacker loading coal stockpiles (Raw Coal) (SK101) 773 365 55

Loading/Dumping Overburden Excavator/Loader loading Overburden to trucks 486,064 183,246 68,049

Loading/Dumping Overburden Trucks Dumping Overburden 7,932 3,752 568

Material Transfer of Coal Product Coal Conveyor (CV805) 282 134 20




TSP PM10 PM2.5








Material Transfer of Coal Raw Coal Conveyor (CV105 – SK101) 773 365 55

Material Transfer of Coal Raw Coal Conveyor (CV302 – raw coal to surge bin) 575 272 41

Material Transfer of Coal Raw Coal Conveyor (CV401 – Mod 1 feed) 339 160 24


Material Transfer of Coal Raw Coal Conveyor (CV301 – direct feed) 107 51 8

Material Transfer of Coal Reject Conveyor (CV702) 40 19 3



Material Transfer of Coal ROM Coal Conveyor (CV102) 790 374 57


Scrapers Scraper stripping and loading topsoil 9,055 2,898 424

Train Loading Train Loading Transfer Point (BN101) 644 304 46




Trucks Loading Coal Excavator/Loader loading coal to trucks 194,537 47,132 6,160

Trucks Unloading Coal Trucks Dumping Coal (Hopper) 324,228 49,096 6,160

Unloading Coal Stockpiles Reclaimer on coal stockpiles (RC301) 575 272 41



TSP PM10 PM2.5



Wheel Generated Dust (Unpaved Roads) Fuel Trucks on Unsealed Roads 728,360 209,078 20,908

Wheel Generated Dust (Unpaved Roads) Haul Trucks on Unsealed Roads 6,317,008 2,221,316 226,665

Wheel Generated Dust (Unpaved Roads) Light Vehicles (<5 tonnes) on Unsealed Roads 689,554 197,939 19,794

Wheel Generated Dust (Unpaved Roads) Other Trucks on Unsealed Roads 477,724 158,912 16,133

Wind Erosion of Exposed Areas Bengalla Pit 86,560 82,232 12,984

Wind Erosion of Exposed Areas Haul Roads 59,500 29,750 4,463

Wind Erosion of Exposed Areas Topsoil Stockpiles 15,470 7,735 1,160

Wind Erosion of Overburden Overburden Dumps (unrehabilitated) 208,879 104,440 15,666

TOTAL UNCONTROLLED 10,665,775 3,711,620 457,842


B.8 Emissions for Base Case Year 2011 with Current Controls

OEH Defined Categories Mine Activity Controlled Emissions (kg/year)

TSP PM10 PM2.5

Blasting Blasting Coal 6,435 3,878 227

Blasting Blasting Overburden 58,534 30,437 1,756

Bulldozing Coal Wheel Dozers on Coal 41,241 14,514 1,210

Bulldozing Overburden Track Dozers on Overburden 268,758 101,336 37,626

Coal Crushing and Screening Primary Crusher (CR101) 8,532 3,413 128

Coal Crushing and Screening Secondary Crusher (FB101) 25,596 10,238 384

Coal Crushing and Screening Tertiary Crusher (CR102) 5,119 1,706 77

Coal stockpiles Emergency Stockpile 792 396 59

Coal stockpiles Product Coal Stockpiles 3,384 1,692 254

Coal stockpiles Raw Coal Stockpiles 2,881 1,441 216

Dragline Dragline Overburden 120,768 56,973 4,106

Drilling Drilling Coal 236 123 7

Drilling Drilling Overburden 9,179 4,773 275

Graders Graders Working 60,590 21,864 1,878



Loading Coal Stockpiles Stacker loading coal stockpiles (Raw Coal) (SK101) 290 137 21

Loading/Dumping Overburden Excavator/Loader loading Overburden to trucks 486,064 183,246 68,049

Loading/Dumping Overburden Trucks Dumping Overburden 7,932 3,752 568







TSP PM10 PM2.5






Material Transfer of Coal Raw Coal Conveyor (CV105 – SK101) 773 365 55

Material Transfer of Coal Raw Coal Conveyor (CV302 – raw coal to surge bin) 575 272 41



Material Transfer of Coal Raw Coal Conveyor (CV301 – direct feed) 32 15 2






Scrapers Scraper stripping and loading topsoil 9,055 2,898 424





Trucks Loading Coal Excavator/Loader loading coal to trucks 194,537 47,132 6,160

Trucks Unloading Coal Trucks Dumping Coal (Hopper) 48,634 7,364 924






TSP PM10 PM2.5

Wheel Generated Dust (Unpaved Roads) Fuel Trucks on Unsealed Roads 182,090 52,270 5,227

Wheel Generated Dust (Unpaved Roads) Haul Trucks on Unsealed Roads 1,579,252 555,329 56,666

Wheel Generated Dust (Unpaved Roads) Light Vehicles (<5 tonnes) on Unsealed Roads 172,389 49,485 4,948

Wheel Generated Dust (Unpaved Roads) Other Trucks on Unsealed Roads 119,431 39,728 4,033

Wind Erosion of Exposed Areas Bengalla Pit 86,560 82,232 12,984

Wind Erosion of Exposed Areas Haul Roads 14,875 7,438 1,116

Wind Erosion of Exposed Areas Topsoil Stockpiles - - -

Wind Erosion of Overburden Overburden Dumps (unrehabilitated) 208,879 104,440 15,666

TOTAL CONTROLLED 3,727,777 1,390,951 225,402

BMC BMP Determination 22 Feb 2012.docx Page C-1

Appendix C

Haul Road Dust Control Efficiency Estimation


Haul Road Dust Control Efficiency Estimation Watering by water carts represents the primary measured applied by Bengalla to control dust emissions from unpaved haul roads. The control efficiency obtained by wet suppression is cyclic rather than continuous by nature. The efficiency afforded by the application of water, requires periodic reapplication to maintain the desired average efficiency (Cowherd et al., 1988).

In establishing the control efficiency of this measure, reference was initially made to the literature. Control efficiencies given for watering were found to vary significantly, reflecting variations in the effectiveness of watering strategies given site-specific practices and climatic factors. The NPI EETM for Mining (2011), by example, defines control efficiencies for two levels of watering as follows:

• 50 percent dust control efficiency for level 1 watering (2 litres/m²/hour) • 75 percent dust control efficiency for level 2 watering (>2 litres/m²/hour) The manner in which these control efficiencies were derived, and the circumstances under which they are applicable (e.g. number of traffic passes; rainfall and evaporation ranges; etc.) are not documented in the manual.

A detailed analysis was undertaken of the watering rate achieved at Bengalla, and the control efficiency achieved, taking into account site specific conditions including the number of traffic passes, rainfall and evaporation rates, and the frequency and intensity of watering. A model was derived, based on the empirical model of Cowherd et al. (1988), for the estimation of the average control efficiency of watering.

c = 100 - (0.8 m d t)/i

where,

c = average control efficiency (%)

d = average hourly daytime traffic rate (hr-1)

i = application intensity (litres per m2)

t = time between applications (hrs)

m = potential average hourly daytime moisture deficit (mm/hr), derived from the average evaporation rate minus the average rainfall rate

The information derived for the application of this model is documented below.

Water Application Intensity

Bengalla operates 3 water carts (Euclid R90) for its haul roads, with water primarily obtained from the ROM Truck Fill Point. One smaller water cart is also used on site for watering on the drill bench and at exploration drill sites (provides water to the sumps for drill rigs). This small water cart obtains water from the West Truck Fill Point. The volumes of water measured to have been dispensed at these fill points during the January to November 2011 period are as follows:


West Truck Fill point

ROM Truck Fill Small Water cart Megalitres Water carts (3) Megalitres Flow total (Jan to Nov 2011) 85.35 Flow total (Jan to Nov 2011) 227.69 Monthly Average 7.76 Average monthly 20.70 Weekly Average 1.94 Weekly Average 8.39 Daily Average 0.277 Daily Average 1.199

Bengalla has about 26 kilometres of unpaved haul roads, of which about 10.6 kilometres are on average active (i.e. approximately 40 percent active). Haul roads are 30 metres wide. The average area of active haul roads is therefore of the order of 317,600 m2. Water cart use is highly variable depending on evaporation and rainfall rates, heavy vehicle movement and prevailing dust levels. Most of the water is applied during the daytime 10 hour shift. Based on the water consumption data, active haul road area and information about water cart practices, daytime water application rates were calculated as follows:

Period

Water Applied

(Megalitres)

Active Haul Road Area

(m²) Total No.

Days No. of Rain

Days

Estimated No. of

Application Days

Daytime Application

Rate (litres/m²/hr)

October 2011 33.56 317,600 31.00 8 23.00 0.459 Jan to Nov 2011 (11 months) 313.04 317,600 334.00 79 255.00 0.387

To provide more certainty on the application rate achieved during summer months, detailed water application data was collated for four days in January 2012 (6th, 7th, 8th and 10th January), and used to project the monthly water usage. There was an estimated 620 water cart refills for the month, based on an average water cart refill of 21 times per day. Total water consumption was projected to be 46.3 megalitres. Active haul routes were mapped during this period to provide a more accurate assessment of the area over which the water was being applied. Total haul distances (shown in green) and active haul distances (shown in white) for are illustrated in the figures overleaf for North and South Haul Routes. The active haul routes were estimated to have a total length of 9.9 km. Based on the information collated, water application rates for January 2012 were estimated as follows:

Period

Water Applied

(Ml)

Active Haul Road Area

(m²) Total No.

Days No. of Rain

Days

Estimated No. of

Application Days

Daytime Application

Rate (litres/m²/hr)

January 2012 46.30 297,826 30.00 6.40 23.60 0.656

Average Hourly Daytime Traffic Rate

The number of haul truck passes on the Northern run was counted to be 42. The number of haul truck passes on the Southern run was counted to be 36. The number of truck passes was taken to be 42 passes per hour for the model to provide a conservative estimate of the control efficiency.


Moisture Deficit Rate

The average monthly moisture deficit was derived based on long-term rainfall and evaporation records from the Bureau of Meteorology Jerrys Plains Station.

Model Application

As illustrated, water application rates are highly variable, depending primarily on evaporation and rainfall rates, given that heavy vehicle movements remain relatively consistent on active haul roads. To account for such variations, water application rates were varied on a monthly basis in line with calculated moisture deficit rates for each month as illustrated below.

Month

D i T p CE

No. of truck passes per hour

Water Application

Rate (litres/m²)

Time between Applications

(hrs)

Moisture Deficit Rate

(mm/hr)

Control Efficiency

Calculated (%) Jan 42 0.65 1.00 0.46 76 Feb 42 0.48 1.00 0.34 76 Mar 42 0.44 1.00 0.31 76 Apr 42 0.36 1.00 0.25 76 May 42 0.22 1.00 0.16 76 Jun 42 0.06 1.00 0.04 76 Jul 42 0.13 1.00 0.09 76 Aug 42 0.20 1.00 0.14 76 Sep 42 0.33 1.00 0.23 76 Oct 42 0.51 1.00 0.36 76 Nov 42 0.63 1.00 0.45 76 Dec 42 0.62 1.00 0.44 76 Annual 42 0.39 1.00 0.27 76

The annual average control efficiency was estimated to be 76 percent. In the event that water application rates are varied to account for changes in rainfall and evaporation, this control efficiency could be maintained despite seasonal weather variations (as illustrated above).

To assess the extent to which water application rates are varied in practice at Bengalla, reference was made to the water application rates modelled and measured for October 2011 and January 2012. The modelled water application rates were found to approximate the measured rates for October and January.

Measured Water Application Rates (litres/m²/hr)

Modelled Water Application Rates (litres/m²/hr)

October 2011 0.46 0.51 January 2012 0.66 0.65 Annual (based on Jan to Nov 2011) 0.39 0.39

The control efficiency derived by the empirical model provides a more robust estimate of the effectiveness of the haul road watering strategy being applied at Bengalla. Given that the predicted control efficiency (76 percent) closely approximates the control efficiency specified in NPI EETM Mining (2011) for Level 2 watering (75 percent), and with the maximum control efficiency indicated by the USEPA (2006) as being achievable through wet suppression (75 percent), a control efficiency of 75 percent was adopted for use in the study..


North Haul Routes – all (green) and active (white) – January 2012


South Haul Routes – all (green) and active (white) – January 2012

BMC BMP Determination 22 Feb 2012.docx Page D-1

Appendix D

Photographs of Bengalla Operations


Water cart operations at Bengalla

Water cart and haul truck operations at Bengalla


Near photograph of the haul road surface

Dragline operations at Bengalla


Bulldozer on overburden at Bengalla (in pit)

Excavator loading overburden to a haul truck at Bengalla


Bengalla ROM Hopper

Bengalla CHPP with enclosed conveyors evident


Bengalla coal stockpile area

Application of hydromulch at Bengalla


Established rehabilitation at Bengalla (cover photograph)

Documents

Bengalla Mining Company Coal Mine Particulate Matter Control … · 2016-01-31 · Page number. Glossary . v Project overview . vii. 1. Introduction 9. 1.1 Background 9 1.2 PRP U2