Coal Mine Particulate Matter Control Best Practice Management Determination

Transcription

1 Coal Mine Particulate Matter Control Best Practice Management Determination February 2012 Bengalla Mining Company

2 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: Please note that when viewed electronically this document may contain pages that have been intentionally left blank. These blank pages may occur because in consideration of the environment and for your convenience, this document has been set up so that it can be printed correctly in double-sided format

3 Contents Page number Glossary Project overview v vii 1. Introduction Background PRP U2 Coal Particulate Matter Control Best Practice Scope of Assessment Additions and Clarifications for OEH Mining Activity Categories Costing of Control Measures Overview of Operations and Management Overview of Operations Mine Activities with Potential Particulate Matter Emissions Overview of Air Quality Monitoring at Bengalla Current Emissions and Control Measures Limitations of Emission Estimation Process Existing Particulate Matter Emissions and Controls Ranking of Mine Activities Based on Controlled Emissions Top Four Mining Activities Potential Measures to Minimise Emissions Best Management Practice Measures for Top Sources Wheel Generated Dust (Unpaved Roads) Truck Loading and Dumping of Overburden Bulldozing of Overburden Wind Erosion of Overburden Emplacement Areas Potential Additional Controls for Top Four Mine Activities Wheel Generated Dust (Unpaved Roads) Truck Loading and Dumping of Overburden Bulldozing of Overburden Wind Erosion of Overburden Emplacement Areas Emission Reductions Achievable due to Additional Controls Practicability of Additional Measures Evaluation of Practicability Best Practice Measures Selected for Implementation 46 BMC BMP Determination 22 Feb 2012.docx Page i

4 6. Implementation Timeline References 50 BMC BMP Determination 22 Feb 2012.docx Page ii

5 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, PM 10 and Meteorological Monitoring Stations 20 BMC BMP Determination 22 Feb 2012.docx Page iii

6 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 BMC BMP Determination 22 Feb 2012.docx Page iv

7 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 m 3 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 PM 10 Particulate matter less than 10microns in aerodynamic diameter PM 2.5 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 BMC BMP Determination 22 Feb 2012.docx Page v

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9 Executive Summary Bengalla Mining Company (BMC) holds an Environmental Protection Licence (EPL number 6538) under the Protection of the Environment Operations Act 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, PM 10 and PM 2.5 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 Wheel Generated Dust (Unpaved Roads) Additional Control Measures 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 Bulldozing of Overburden No additional controls identified. No additional controls identified. BMC BMP Determination 22 Feb 2012.docx Page vii

10 OEH Mining Activity Category Wind Erosion of Overburden Additional Control Measures 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 PM 10 emission reductions in the range 158 to 300 tonnes per year, and PM 2.5 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. BMC BMP Determination 22 Feb 2012.docx Page viii

11 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 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 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; BMC BMP Determination 22 Feb 2012.docx Page 9

12 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 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 PRP U2 makes specific reference to the OEH Coal Mine Particulate Matter Control Best Practice Site Specific Determination Guideline dated August It is however noted that this guideline was revised in November BMC BMP Determination 22 Feb 2012.docx Page 10

13 Figure 1.1 Bengalla Locality Map BMC BMP Determination 22 Feb 2012.docx Page 11

14 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, PM 10 and PM 2.5 (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 Using the results of the controlled emissions estimates generated from Step 1.1, rank the mining activities according to the mass of TSP, PM 10, and PM 2.5 emitted by each mining activity per year from highest to lowest Identify the top four mining activities from Step 1.2 that contribute the highest emissions of TSP, PM 10 and PM 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 For each of the top four activities identified in Step 1.3, estimate emissions of TSP, PM 10 and PM 2.5 from each mining activity following the application of the measures identified in Step 2.1. BMC BMP Determination 22 Feb 2012.docx Page 12

15 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 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 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. BMC BMP Determination 22 Feb 2012.docx Page 13

16 Table 1.1 Mining activities defined within the OEH Guideline Mining Activities Wheel generated particles on unpaved roads Mining Activities 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 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). BMC BMP Determination 22 Feb 2012.docx Page 14

17 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 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 BMC BMP Determination 22 Feb 2012.docx Page 15

18 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 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. BMC BMP Determination 22 Feb 2012.docx Page 16

19 Figure 2.1 Bengalla Mining Method Schematic BMC BMP Determination 22 Feb 2012.docx Page 17

20 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 PM depositional dust gauges Four real-time air monitors (E-bams) measuring PM 10, 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 PM 10 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. BMC BMP Determination 22 Feb 2012.docx Page 18

21 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, prestrip 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. BMC BMP Determination 22 Feb 2012.docx Page 19

22 Figure 2.2 Location of Bengalla s TSP, PM 10 and Meteorological Monitoring Stations BMC BMP Determination 22 Feb 2012.docx Page 20

23 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, PM 10 and PM 2.5 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, PM 10, and PM 2.5 emitted by each mining activity per year. Identification of the top four mining activities that comprise the greatest contribution to emissions of TSP, PM 10 and PM 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, PM 10 and PM 2.5 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. BMC BMP Determination 22 Feb 2012.docx Page 21

24 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 BMC BMP Determination 22 Feb 2012.docx Page 22

25 Mining Activity Category Current Control Measures 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 Bulldozing Overburden Coal Crushing and Screening Coal stockpiles Loading coal stockpiles Unloading coal stockpiles Dragline Dozers travel on watered routes between work areas. 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). Crushing plant enclosed within internal water sprays. Dust generation from the coal stockpile area is addressed within environmental work instruction CNA-10-EWI-SITE-E 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 dust controls are documented within work instruction CNA-1-EWI-SITE-E 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. BMC BMP Determination 22 Feb 2012.docx Page 23

26 Mining Activity Category Drilling Dust-related dragline stoppages are logged. Current Control Measures 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). 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) Loading/Dumping Overburden Material Transfer of Coal (Conveying; transfer points) 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 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. 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. 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 BMC BMP Determination 22 Feb 2012.docx Page 24

27 Mining Activity Category Trucks Loading Coal Trucks Unloading Coal (ROM Hopper) Wind Erosion of Exposed Areas Current Control Measures 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. Drop heights are reduced as far as practicable by excavator operators. 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-E 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. 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.) BMC BMP Determination 22 Feb 2012.docx Page 25

28 Mining Activity Category Wind Erosion of Overburden Current Control Measures 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 sitespecific 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. BMC BMP Determination 22 Feb 2012.docx Page 26

29 Table 3.2 Control efficiencies applied for current controls, where quantifiable Mining Activity Category Coal Crushing and Screening Control Measure(s) Providing Basis for Control Efficiency Allocated(a) Crushing plant are enclosed within internal water sprays(b) Control Efficiencies (%) TSP PM 10 PM Coal Stockpiles Water sprays Drilling Water sprays Loading Coal Water sprays and variable height stacker(d) Stockpiles Material Transfer of Enclosed/partially enclosure of coal and reject Coal conveyors Train Loading Retractable chute Trucks Unloading ROM hopper is enclosed (roof, 3 sides) with Coal automated water curtain(e) Wheel Generated Wet suppression (water cart)(f) (Unpaved Roads) Wind Erosion of Wet suppression (water cart)(f) Exposed Areas Dragline Minimise drop height to within 5 metres(c) 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, PM 10 and PM 2.5 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 PM 10 and 51 percent for PM 2.5. BMC BMP Determination 22 Feb 2012.docx Page 27