9. AIR QUALITY 9.1 Introduction 2/ES...Having agreed with TCBC that the significance of the impact on local air quality would be negligible, this work concentrated on the potential

4339/1/ARM Harmers Limited November 2014

Environmental Statement

Glamorgan Power -83- Varteg Hill

9. AIR QUALITY

9.1 Introduction

9.1.1 This updated Environmental Statement chapter reviews the work done previously by AECOM on the air quality effects of the proposed Varteg Coal Extraction and Reclamation Works.

9.1.2 Initially, an air quality impact assessment of the proposed coal extraction and land

reclamation scheme at Varteg was undertaken by AECOM (then Faber Maunsell) in 2004 and submitted as part of the Environmental Statements produced in 2004 and 2009. This assessment focussed primarily on the effect of emissions of the additional heavy goods vehicles (HGVs) using the B4246 Varteg Road.

9.1.3 A further report was produced in June 2010 which assessed the impact of the coal

extraction and its associated operations on local air quality. This assessment followed the Welsh Assembly Government Guidance (Mineral Technical Advice Note 2: Coal (MTAN2)). This report examined both worst-case conditions with no dust mitigation measures in place and typical conditions with standard mitigation measures in place.

9.1.4 Following the rejection of this application by Torfaen County Borough Council

(TCBC) in January 2001, partly on the grounds of dust nuisance, further assessment work was undertaken and a report was subsequently produced in November 2011 prior to the Public Inquiry. Having agreed with TCBC that the significance of the impact on local air quality would be negligible, this work concentrated on the potential of the works to cause nuisance through dust deposition.

9.1.5 This report was reviewed by Peter Oates, Environmental Health Officer for TCBC.

Mr Oates requested further information and clarifications on the findings of this report. These clarifications were provided prior to the Public Inquiry which was held in February 2012. A Proof of Evidence was also produced by Dr Gareth Collins of AECOM for the Public Inquiry.

9.1.6 This ES chapter presents the detailed methodologies and findings of the June 2010

and November 2011 reports. It also provides updates from the work Dr Collins’ Proof of Evidence in January 2012, the correspondence with TCBC and any additional evidence provided at the Public Inquiry.

9.1.7 This report takes the form of the following structure:

• Section 9.2: Development Proposals; • Section 9.3: Pollutants and Prediction of Significance; • Section 9.4: Methodology and results for the 2009 Environmental Statement; • Section 9.5: Methodology and results for the June 2010 report; • Section 9.6: Methodology and results for the November 2011 Report; • Section 9.7: Public Inquiry, including proofs of evidence and additional

evidence provided to the Inquiry; and • Section 9.8: Conclusions.




9.2 Development Proposals

9.2.1 The development plans cover four phases. Phase maps are included in Appendix 9A. A brief description of each phase is included below.

Phase 1

9.2.2 The initial work would require overburden stripping. Soil would be removed to

create an area for site offices and a road to the south of the site. This soil would be loaded onto 33 tonnes trucks (unladen weight) in 40 tonnes loads. These loads would be taken to soil stockpiles to the north of the site and one to the south west of the site. In total it is planned to move 100,000 tonnes of soil: 60,000 tonnes to the southern soil stockpile; and 40,000 tonnes to the northern stockpile. Trucks would take overburden (20,000 m3 per week) from the eastern coal extraction area around the south of the mountain to the west and to an overburden storage area to the east of the site. The initial overburden taken to the eastern stockpile would be used to create a bund to mitigate noise and dust impacts on properties to the east of the site. A two – three metre outer bund would be maintained as the height of the stockpile increases. The overburden trucks would be approximately 33 tonnes (unladen weight) carrying 40 tonne loads of overburden. The coal would be taken in 12 tonne trucks (unladen weight) in 20 tonne loads from the central area via a haul road north to the site access at the northern end of the site. It is proposed to move 2,500 tonnes of coal per week. This coal would then be taken north to the Heads of the Valley road. All haul roads would be unpaved with the exception of the section of haul road from the site access to the site office.

9.2.3 This Phase is planned to last ten months.

Phase 2

9.2.4 Overburden stripping and coal mining would continue in the central area which

would extend to the north. The overburden (20,000 m3 per week) would be taken to the eastern overburden stockpile. Again 2,500 tonnes of coal per week would be mined and transported to the north. The western overburden stockpile and the soil stockpile next to it would be restored and re-vegetated to reduce wind-blown dust. This Phase is planned to last ten months.

Phase 3

9.2.5 During Phase 3, the central mining area would move further north. Overburden

(20,000 m3 per week) would be taken to the area mined in Phases 1 and 2 and this area would be restored in this Phase. 2,500 tonnes of coal per week would be mined and transported to the north. This Phase is planned to last twelve months.

Phase 4

9.2.6 Overburden (20,000 m3 per week) would be taken from the eastern stockpile to the

area mined in Phase 3 and this area would be restored in this Phase. No coal would




be mined during this Phase. This Phase is planned to last twelve months. No coal would be mined in this phase.

9.3 Pollutants and Prediction of Significance

Introduction

9.3.1 This section relates to the pollutants of concern and the determination of significance

that are common to all three assessments. This uses the latest guidance and information, which were not always available at the time of the assessment, but provides an update and a present-day context.

Pollutants

9.3.2 The pollutants of concern for this assessment are nitrogen dioxide (NO2) and particles

(PM10).

9.3.3 NO2 and nitric oxide (NO) are collectively known as oxides of nitrogen, or NOX. All combustion processes produce NOX emissions, predominantly in the form of NO, which then undergoes conversion in the atmosphere to NO2, mainly as a result of its reaction with ozone (O3). It is NO2 that has been most strongly associated with adverse effects upon human health. Nitrogen dioxide can irritate the lungs and lower resistance to respiratory infections such as influenza. Continued or frequent exposure to concentrations that are typically much higher than those normally found in the ambient air may cause increased incidence of acute respiratory illness in children.

9.3.4 The Government’s Air Quality Strategy objectives and EU limit values for nitrogen

dioxide (NO2) are:

• An annual mean concentration of 40 µg/m3; and • A one-hour mean concentration of 200 µg/m3, not to be exceeded more than

eighteen times per year.

9.3.5 Particulate matter is composed of a wide range of materials arising from a variety of sources, and is typically assessed as total suspended particulates, or as a mass size fraction. The PM10 and PM2.5 standards for the assessment of fine particulate matter has been adopted by both the UK Government and EU which express particulate levels as the total mass size fraction at or below an aerodynamic diameter of 10 µm and 2.5 µm respectively. PM10 particles are able to penetrate beyond the nose and throat deep into the respiratory system reaching the bronchi and lungs. PM2.5 particles are able to penetrate further and enter into the alveoli where gas exchange occurs, and very small particles (<0.1 µm) may penetrate the lung and enter the bloodstream, affecting other organs. Extensive scientific research has provided evidence of associations between exposure to fine particulate matter (PM) and increased morbidity and mortality.

9.3.6 The Government’s Air Quality Strategy objectives and the EU limit value for PM10

are:




• An annual mean concentration of 40 µg/m3 (gravimetric); and • A 24-hour mean concentration of 50 µg/m3 (gravimetric) to be exceeded no

more than 35 times per year.

9.3.7 These objectives are also EU limit values which are mandatory. At present there are no known exceedences of these objectives in Torfaen County.

9.3.8 The release of larger dust particles can be a nuisance. It can soil surfaces,

contaminate soils, vegetation and water bodies and affect personal comfort, amenity and health. Coal dust is highly visible and can result in an unsightly coating. There are no regulatory standards relating to dust deposition rate. However, an empirical relationship has been derived from monitoring, which suggests a rate of 200 mg/m2/day as a nuisance threshold at residential premises. As coal dust is darker than most dusts, Minerals Technical Advice Note 2: Coal from the Welsh Assembly Government1 recommends that the Mineral Planning Authority sets a condition of a maximum of 80 mg/m2/day as a weekly average. Background dust deposition rates are not available for the site but a typical figure for a suburban area or small town is 5 mg/m2/day.

9.3.9 Dispersal of dust is determined by how long the dust remains airborne and is highly

weather dependent. Dust from opencast sites is mainly coarse so settles out relatively quickly so dust concentrations decrease rapidly away from the source. Larger particles (>30 µm) return to the surface quickly, medium size particles (10-30 µm ) will generally travel 100-250 m from the source under normal conditions but in adverse conditions can travel 500 m from the source. Residents can potentially be affected by dust up to 1 km from the source but continual or severe concerns are most likely to be experienced near to dust sources (generally within 100 m)1.

Measuring the Significance of Effects

9.3.10 Air quality effects of a proposed scheme may be considered to be significant if air

quality objectives are predicted to be breached or if the development leads to significant effects on air quality at sensitive receptors. According to the Institute of Air Quality Management (IAQM)2 there are two main aspects which need to be taken into account when describing predicted impacts. These are:

• the magnitude of the change; and • the absolute concentration in relation to air quality objectives.

9.3.11 The first aspect is addressed in Table 9.1, in which impacts are assigned a magnitude

according to the absolute change in pollutant concentrations, derived based upon the predicted change in pollutant concentrations relative to the specific air quality objective or limit value in question.

Table 9.1 Assessment of the Magnitude of Change Magnitude of Change Annual Mean NO2/PM10 Large Increase / decrease >4 µg/m3




Magnitude of Change Annual Mean NO2/PM10 Medium Increase /decrease 2-4 µg/m3 Small Increase / decrease 0.4-2 µg/m3 Imperceptible Increase / decrease <0.4 µg/m3

9.3.12 The magnitude of change can then be compared to the absolute concentration in

relation to the relevant air quality standard in order to describe predicted air quality impacts as detailed in Table 9.2.

Table 9.2 Air Quality Impact Descriptors Absolute Concentration in Relation to Standard

Magnitude of Impact Small Medium Large

Above Objective/Limit Value With Scheme (>40 μg/m3)

Slight Adverse / Beneficial

Moderate Adverse / Beneficial

Substantial Adverse / Beneficial

Just Below Objective/Limit Value With Scheme (36-40 μg/m3)

Slight Adverse / Beneficial



Below Objective/Limit Value With Scheme (30-36 μg/m3) Negligible Slight Adverse /

Beneficial Slight Adverse /

Beneficial Well Below Objective/Limit Value With Scheme (<30 μg/m3)

Negligible Negligible Slight Adverse / Beneficial

9.3.13 The IAQM suggest that the following factors should be taken into account when

determining the overall significance of predicted air quality impacts:

• The magnitudes of the changes and the descriptions of the impacts at the receptors;

• The number of people affected by increases and/or decreases in concentrations and a judgement on the overall balance;

• Where new exposure is being introduced into an existing area of poor air quality, then the number of people exposed to levels above the objective or limit value will be relevant;

• Whether or not an exceedence of an objective or limit value is predicted to arise in the study area where none existed before or an exceedence area is substantially increased;

• Whether or not the study area exceeds an objective or limit value and this exceedence is removed or the exceedence area is reduced;

• Uncertainty, including the extent to which worst-case assumptions have been made; and

• The extent to which an objective or limit value is exceeded, e.g. an annual mean NO2 of 41 µg/m3 should attract less significance than an annual mean of 51 µg/m3.




9.4 2009 Environmental Statement Air Quality Chapter

Introduction

9.4.1 The effect of road traffic from the Reclamation Works was assessed for the 2009 planning application. This application used an assessment that was previously undertaken in 2004. The Design Manual for Roads and Bridges (DMRB) screening assessment (November 2003 version) was used to predict air quality concentrations. The DMRB methodology was originally designed for use in assessing the air quality effects of new trunk roads and motorway schemes. In this context, a forecast pollutant level above the standards and objectives is interpreted as indicating a recommendation to undertake a more detailed assessment.

9.4.2 The effect of air quality concentrations due to the 114 traffic movements

(approximately 45 HGV movements) per day were predicted for five pollutants at two sensitive receptors for a scenario without the Reclamation Works and a scenario with the Reclamation Works. The two receptors were chosen near to the routes affected by the proposed scheme. These receptors were the closest properties to the affected routes. The effect of the road traffic on concentrations was therefore determined by subtraction of the predicted concentration of the former scenario from the latter one.

9.4.3 Air quality was predicted for the following scenarios:

• Baseline scenario (2003); • Opening year (2007) Do-Minimum (DM) scenario (i.e. without the proposed

Reclamation Works); and • Opening year (2007) Do-Something (DS) scenario (i.e. with the proposed

Reclamation Works).

Results

9.4.4 The results for the two main pollutants, NO2 and PM10, are shown in Table 9.3. The effects on pollutant concentrations were predicted to be less than 0.1 µg/m3 at the two receptors. The significance of the effects was predicted to be negligible.

Table 9.3 Magnitude and Significance of Road Transport Effects, NO2 and PM10

Receptor Magnitude of Effect

Significance of Effect

Receptor 1 - Pembroke Terrace Imperceptible Negligible Receptor 2 - Opposite proposed site entrance, Varteg Road Imperceptible Negligible

9.4.5 A qualitative dust assessment was also undertaken, which suggested that with

appropriate mitigation, dust should not be a significant issue.




Conclusions

9.4.6 The predictions using the DMRB screening method clearly indicate that the significance of the air quality effects from the additional HGV movements was negligible. Subsequent analysis has led to a reduction of the equivalent HGV movements from approximately 45 per day to approximately 36 HGV movements per day). Therefore, the assessment of these HGVs was scoped out of the future assessments.

9.5 June 2010 Assessment

Introduction

9.5.1 The modelling assessment has been focussed on the effects of dust generated by the

activities involved with the coal extraction and the reclamation works. No modelling has been undertaken to determine the effects of the HGV emissions on the roads as it has been clearly identified that the significance of their impact is negligible. Therefore, particulate emissions have been modelled to determine the effects on PM10 concentrations, which has an objective to protect human health, and on dust deposition which can lead to nuisance impacts.

Estimation of Source Strengths

9.5.2 The US Environmental Protection Agency (US EPA) has published a compilation of

emission factors for estimating the dust produced for a number of dusty processes3. This report brings together the findings of a large number of monitoring exercises which have been carried out in a variety of industrial situations throughout the United States and is widely accepted as an authoritative reference for emissions factors.

9.5.3 The emission factor equations used are given in Appendix 9B. Most activities

produce quantities of dust which are directly proportional to the amount of bulk material moved.

9.5.4 The use of these equations was used to calculate emissions of Total Suspended

Particulate (TSP), which are particles of less than 30 µm, to determine dust deposition rates. Particles larger than 30 µm are likely to settle on the ground within a hundred metres of the source.

9.5.5 Emission factors for a 'typical'-case scenario have been calculated. The emission

factors are determined for expected operations, but using worst case meteorological data to cover the eventualities of the weather. Emissions of dust can be well-controlled and regulated using standard mitigation measures. It is widely accepted that these standard measures yield dust suppression of between 50% and 90%. As a worst case, the majority of the processes are assumed to have a mitigation of 50%.

9.5.6 The exception to this is for the unpaved roads within the site where a dust suppression

factor of 90% has been used to represent the fact that the moisture content of the road will be at least twice that taken from AP-42 due to the relatively damp conditions in South Wales compared to the Western United States and the supplementary spraying




by water bowsers that is standard practice with these type of activities. If dust is being raised during haulage, then water bowsers will be used on a continuous basis along the unpaved roads. As the unpaved roads are not of any great length it should be possible to achieve 90% mitigation with the additional measures that will be employed such as regular cleaning of the haul roads and regrading the roads on a regular basis to ensure a firm surface.

Phase 1

9.5.7 The modelling for this Phase has assumed that:

• Wind erosion is possible at the two overburden and the two soil stockpiles. • The western overburden and soil stockpiles are served by Haul Road 1. • The eastern overburden stockpile is served by Haul Road 2. • The northern soil stockpile and the coal trucks are served by Haul Road 3,

which is paved north of the site offices. • All loading is performed by excavators with a bucket capacity of 10 tonnes

per load. • Overburden and soil trucks are 33 tonnes unladen and 73 tonnes fully laden. • Coal trucks are 12 tonnes unladen and 32 tonnes fully laden.

9.5.8 Further assumptions for inputs to the equations listed in AP-42 are detailed in

Appendix 9B.

Phase 2


• Wind erosion is possible at the eastern overburden stockpile. • The eastern overburden stockpile is served by Haul Road 1. • The coal trucks are served by Haul Road 2, which is paved north of the site

offices. • All loading is performed by excavators with a bucket capacity of 10 tonnes

per load. • Overburden trucks are 33 tonnes unladen and 73 tonnes fully laden. • Coal trucks are 12 tonnes unladen and 32 tonnes fully laden.


Appendix 9B.

Phase 3


• Wind erosion is possible at the eastern overburden stockpile. • The restoration with overburden is served by Haul Road 1. • The coal trucks are served by Haul Road 2, which is paved north of the site

offices. • All loading is performed by excavators with a bucket capacity of 10 tonnes

per load.




• Overburden trucks are 33 tonnes unladen and 73 tonnes fully laden. • Coal trucks are 12 tonnes unladen and 32 tonnes fully laden.


Appendix 9B.

Phase 4


• The restoration with overburden from the eastern overburden stockpile is served by Haul Road 1.

• No coal is mined. • All loading is performed by excavators with a bucket capacity of 10 tonnes

per load. • Overburden trucks are 33 tonnes unladen and 73 tonnes fully laden.


Appendix 9B.

9.5.15 The PM10 modelling in this section was undertaken as part of the June 2010 report. The main difference between the modelling undertaken in June 2010 and that undertaken for dust deposition in the November 2011 report is the different meteorological data used. All the data used was from the St Athan site.

9.5.16 Smaller particles (PM10) are linked with adverse health effects ranging from minor

effects on the respiratory system to premature mortality. However, evidence suggests that it is the combustion-derived components of PM10 rather than particles from natural sources that are primarily responsible for harmful effects. For PM10, there are two UK air quality objectives. These are:

• An annual mean concentration of 40 µg/m3 (gravimetric); and • A 24-hour mean concentration of 50 µg/m3 (gravimetric) to be exceeded no

more than 35 times per year.

9.5.17 The background concentrations of PM10 used in the modelling in June 2010 was 12.9 µg/m3 (grid square centred on OS grid reference (326500, 206500) taken from the Air Quality Archive4). The latest background concentration (for 2015) for PM10 taken from the Defra website is 13.2 µg/m3 for the same grid square.

Modelling Methodology

9.5.18 The Lakes AERMOD model version 6.5.0 was used to calculate the dispersion of

dust from the proposed opencast workings. This model is one of the most highly developed models in the world and extensive validation tests have been carried out by the US EPA.

9.5.19 The modelling was carried out using area sources to represent the various activities at

the proposed workings. 24 sensitive receptors have been selected (see Figure 9.1)




and PM10 concentrations and dust deposition rates were calculated for all the scenarios. The closet receptors are within 100 metres of the site boundary so the contribution from the workings is likely to be highest at these locations.

Figure 9.1 Map of Sensitive Receptors

9.5.20 For the dust deposition, each source has been taken to release dust in three particle size ranges. The distribution of these size ranges varies for each source. More details can be found in Appendix 9B. Settling velocities for each particle size class were calculated by the AERMOD model according to the density specified for each source. The sources were assigned a density of 2.5 g/cm3 to represent coal and overburden dust.

9.5.21 Local topography has been included in the AERMOD model using terrain data. A

two metre bund has also been added to this terrain file for all the four phases. Due to the coal surface working, the topography will change during the mining but this has not been assessed in the dispersion modelling.




Meteorological Data

9.5.22 Meteorological data suitable for use in dispersion modelling was purchased from ADM Limited. Four years worth of data were obtained for a site in St Athan which is about 70 km from Varteg. This is the closest meteorological site to have cloud cover data. All four years of meteorological data were run in the model for one of the phases to determine which year led to the highest concentrations and to identify a year that was more typical. 2009 was found to be the worst year and 2008 was used as the more typical year.

Results

9.5.23 In the 2010 submission, further assessment work was required to predict the effects

on PM10 concentrations and dust deposition from the fugitive dust sources during the Reclamation Works. These effects were predicted at 24 sensitive receptors using dispersion modelling of the four proposed phases of work. The emission factors for the main activities were estimated using the US EPA AP-42 database of emission factors. The results for the magnitude and significance of the effects on PM10 concentrations for a typical scenario are detailed in Table 9.4. The greatest impact during the four phases was selected for each receptor. Although medium magnitude effects were predicted at some receptors for the effect on PM10 concentrations, the significance of the effects were predicted to be negligible due to the low absolute concentrations predicted. All concentrations were predicted to be below 20 µg/m3. Therefore, all concentrations were predicted to be less than 50% of the UK air quality annual mean objective for PM10 (40 µg/m3).




Table 9.4 Magnitude and Significance of Fugitive Dust Effects, PM10

Receptor Magnitude of Effect Significance of Effect Ty Rhodd Farm Imperceptible Negligible Ty Michael Farm Imperceptible Negligible Beachley Bungalow Imperceptible Negligible 1, Pembroke Place Medium Negligible 3, Pembroke Place Medium Negligible 1, Pembroke Terrace Medium Negligible 4, Pembroke Terrace Medium Negligible 7, Pembroke Terrace Medium Negligible 10, Pembroke Terrace Medium Negligible 20, Salisbury Terrace Medium Negligible 13, Salisbury Terrace Medium Negligible 2, Salisbury Terrace Small Negligible Apple Trees, Varteg Road Small Negligible Gladstone Terrace 1 Small Negligible Gladstone Terrace 2 Small Negligible Gladstone Terrace 3 Small Negligible Samson's Avenue 1 Small Negligible Samson's Avenue 2 Small Negligible Varteg Road 2 Small Negligible Varteg Road 3 Small Negligible Receptor south of Quarry Small Negligible School Small Negligible Spring Cottage Small Negligible Rose Cottage Small Negligible

9.5.24 Using the same dispersion modelling methods, the results for the magnitude and

significance of the effects on dust deposition for a typical scenario are detailed in Table 9.5. The greatest impact during the four phases was selected for each receptor. Exceedences of the weekly MTAN2 dust deposition threshold of 80 mg/m2/day were predicted at two receptors. The significance of the effect was deemed to be ‘moderate’ at 1 Pembroke Place, because the exceedance was deemed to be likely at this receptor for a period of two weeks. The significance of the effect was deemed to be ‘minor’ at 3 Pembroke Place, because the exceedance was deemed to be possible at this receptor for a period of just one week. The significance of the effects on the other receptors was deemed to be negligible, because the potential for exceedence of the MTAN2 threshold was deemed to be unlikely. The greatest effects at Pembroke




Place occurred during Phase 4 when restoration of the coal works is being undertaken.

Table 9.5 Fugitive Dust Effects, Dust Deposition, 2010 Modelling

Receptor Potential Exceedance of MTAN2 Threshold? Significance of Effect

Ty Rhodd Farm No Negligible Ty Michael Farm No Negligible Beachley Bungalow No Negligible 1, Pembroke Place Yes Moderate 3, Pembroke Place Yes Minor 1, Pembroke Terrace No Negligible 4, Pembroke Terrace No Negligible 7, Pembroke Terrace No Negligible 10, Pembroke Terrace No Negligible 20, Salisbury Terrace No Negligible 13, Salisbury Terrace No Negligible 2, Salisbury Terrace No Negligible Apple Trees, Varteg Road No Negligible Gladstone Terrace 1 No Negligible Gladstone Terrace 2 No Negligible Gladstone Terrace 3 No Negligible Samson's Avenue 1 No Negligible Samson's Avenue 2 No Negligible Varteg Road 2 No Negligible Varteg Road 3 No Negligible Receptor south of Quarry No Negligible School No Negligible Spring Cottage No Negligible Rose Cottage No Negligible

Conclusions

9.5.25 The predictions indicated that the effects of the fugitive dust likely to be produced by

the Reclamation Works were of negligible significance with regard to PM10 concentrations. Although the magnitudes of the effects at some of the receptors were of medium magnitude, the low absolute concentrations in the area resulted in the effects being deemed to be of negligible significance. The highest concentration predicted with the Reclamation Works in operation was below 20 µg/m3. Therefore,




all concentrations were predicted to be less than 50% of the UK air quality annual mean objective for PM10 (40 µg/m3).

9.5.26 The predictions of dust deposition indicate that exceedences of the weekly MTAN2

dust deposition threshold of 80 mg/m2/day were predicted at two receptors and that these exceedences would occur for at most two weeks during the entire duration of the surface workings.

9.6 November 2011 Assessment

Introduction

9.6.1 The previous assessment in June 2010 had indicated that impacts from dust emissions

on PM10 concentrations were of a negligible significance under typical working conditions and that overall annual mean PM10 concentrations were below 20 µg/m3 and therefore well below the EU limit value of 40 µg/m3. This conclusion was agreed on with Mr Oates of TCBC. However, there were still concerns regarding dust deposition. There was also concern that the use of the meteorological data from the nearest fully equipped meteorological station, St Athan, a coastal site, was not representative of the high valley location at Varteg. There was also concern regarding the dust suppression factor used for determining the fugitive dust emissions from the unpaved roads within the site.

9.6.2 This study has therefore concentrated on dust deposition rates which have the

potential to cause nuisance according to the MTAN2 threshold of 80 mg/m2/day as a weekly average. The study has also focussed on the parameters about which the representatives of TCBC had voiced concerns.

Meteorological Data

9.6.3 Meteorological data suitable for use in dispersion modelling was purchased from

ADM Limited. Four years worth of data were obtained for a site in St Athan which is about 70 km from Varteg. This is the closest meteorological site to have cloud cover data. In response to the comments by TCBC, a more local source was used to provide data for wind speed, wind direction and rainfall. This meteorological station was based in Twynyrodyn (Grid Reference 305796, 206028, 243 m AOD), near Merthyr Tydfil, which was deemed to be more representative of the Varteg site. This site is approximately 20 km from Varteg.

9.6.4 All four years of meteorological data were run in the model for one of the phases to

determine which year led to the highest concentrations and to identify a year that was more typical. 2009 was found to be the worst year and so this was used in the modelling study. Worst case rainfall data from Twynyrodyn was also used. A windrose for this year are shown in Appendix 9C.

Modelling Methodology

9.6.5 The Lakes AERMOD model version 7.3.0 was used to calculate the dispersion of

dust from the proposed opencast workings. This model is one of the most highly




developed models in the world and extensive validation tests have been carried out by the US EPA.

9.6.6 The modelling has been carried out using area sources to represent the various

activities at the proposed workings. Dust deposition rates have been calculated for the scenarios listed below for the same 24 sensitive receptors as in the June 2010 assessment (see Figure 9.1). The closest receptors are within 100 metres of the site boundary so the contribution from the workings is likely to be highest at these locations.

9.6.7 For the dust deposition, each source has been taken to release dust in three particle

size ranges. The distribution of these size ranges varies for each source. More details can be found in Appendix 9B. Settling velocities for each particle size class were calculated by the AERMOD model according to the density specified for each source. The sources were assigned a density of 2.5 g/cm3 to represent coal and overburden dust.

9.6.8 Local topography has been included in the AERMOD model using terrain data. A

two metre bund has also been added to this terrain file for all the four phases. Due to the coal surface working, the topography will change during the reclamation works but this has not been assessed in the dispersion modelling.

9.6.9 Four scenarios have been tested for each phase to examine the sensitivity of the

model to variations in two parameters for the dust emissions from unpaved roads. The previous study confirmed what other studies have found, i.e. that the emissions from unpaved roads are the predominant source of dust. The two parameters are: a mitigation factor for unpaved roads, which includes the suppression due to increased surface moisture provided by water bowsers; and the silt content of the unpaved road. The four scenarios are:

1. Mitigation factor of 90% and silt content of 8.4% (as recommended by AP-42); 2. Mitigation factor of 90% and silt content of 12.6% (representing a 50% increase

on the expected silt content); 3. Mitigation factor of 75% and silt content of 8.4%; and 4. Mitigation factor of 75% and silt content of 12.6%.

9.6.10 The use of a silt content of 8.4% is taken from US EPA AP-42 as the mean silt

content for haul roads for pits for the US industry category of Western Surface Coal Mining.

Results

9.6.11 The results are detailed in Table 9.6.




Table 9.6 Fugitive Dust Effects, Dust Deposition, 2011 Modelling

Receptor Potential Exceedance of MTAN2 Threshold? Scenario 1 Scenario 2 Scenario 3

Ty Rhodd Farm No No No Ty Michael Farm No No No Beachley Bungalow No No No 1, Pembroke Place No No Yes 3, Pembroke Place No No Yes 1, Pembroke Terrace No No Yes 4, Pembroke Terrace No No Yes 7, Pembroke Terrace No No Yes 10, Pembroke Terrace No No Yes 20, Salisbury Terrace No No Yes 13, Salisbury Terrace No No Yes 2, Salisbury Terrace No No Yes Apple Trees, Varteg Road No No No Gladstone Terrace 1 No No No Gladstone Terrace 2 No No No Gladstone Terrace 3 No No No Samson's Avenue 1 No No No Samson's Avenue 2 No No No Varteg Road 2 No No No Varteg Road 3 No No No Receptor south of Quarry No No No School No No No Spring Cottage No No No Rose Cottage No No No

9.6.12 The results indicate that the model is sensitive to the unpaved roads mitigation factor

and relatively insensitive to the slit loading factor.

Conclusions

9.6.13 For scenarios with the expected operational mitigation measures, impacts were predicted to be below the weekly threshold for the entire duration of the surface workings. For scenarios with a lower mitigation factor, exceedences of the weekly threshold were predicted at the closest receptors. These scenarios were run as sensitivity tests rather than as expected conditions as due to the small scale of the unpaved haul roads and the enhanced mitigation measures that will be employed at




the works, it is believed that the high level of mitigation modelled in the first two scenarios will be met even in the driest conditions.

9.7 Public Inquiry

Introduction

9.7.1 Following the three studies, the Planning Inquiry into the proposed land

reclamation/coal recovery scheme was held in January/February 2012.

Statement of Common Ground

9.7.2 Of the areas of agreement relating to the air quality there was just the one:

'There is agreement that there is no evidence of any material health impacts arising from the proposal.'

9.7.3 The areas of disagreement relating to air quality are listed below:

'There is disagreement that the impacts upon the amenities of local residents in relation to noise and dust are acceptable and that the benefits of the scheme outweigh the dis-benefits of any likely impacts.'

Proofs of Evidence

9.7.4 The main conclusions of the Proof of Evidence by Dr Gareth Collins, expert witness

on behalf of Glamorgan Power Company, are summarised below:

1. The proposed reclamation works at Varteg are predicted to lead to increased dust deposition at local sensitive receptors. The nuisance threshold used for comparison was the MTAN2 threshold of 80 mg/m2/day as a weekly average, which is for dark coal dust. The threshold employed is worst-case, as the majority of the dust generated would be from the overburden working rather than the coal working. Indeed other dust assessments have used higher thresholds.

2. For scenarios with the expected operational mitigation measures, the effects on dust deposition were predicted to be below the weekly threshold for the entire duration of the surface workings.

3. With a higher silt content (over 9.3%), one week of exceedence was predicted for the whole five year period. The modelling did not predict another weekly exceedence until the silt content was increased from 9.3% to 19.7%.

4. For scenarios with a lower suppression factor for unpaved roads, exceedences of the weekly threshold were predicted at the closest receptors. These scenarios were run as sensitivity tests rather than as expected conditions as due to the small scale of the unpaved haul roads and the enhanced mitigation measures that will be employed at the works, it is my professional opinion that the MTAN2 threshold will be met for the majority of the operational works even under the driest conditions.




5. As has been agreed with Torfaen County Borough Council, the predicted results do not indicate any exceedences of the UK or European ambient air quality standards.

9.7.5 The main conclusions of the Proof of Evidence by Mr Peter Oates, expert witness on

behalf of TCBC, are summarised below:

1. The 8.4% silt content used in the modelling does not represent the worst case scenario, it is a generic mean average value and in the absence of site specific data, actual conditions could potentially differ by an order of magnitude.

2. The dust suppression factors of 50% and of 90% for unpaved roads used in the modelling do not represent the worst case scenario and the use of these factors has not been justified. In the absence of site specific data actual conditions could be significantly different.

3. The percentage soil moisture content for handling materials such as soil and coal differ. Use of these factors has not been sufficiently justified and may not therefore represent the worst case scenario.

4. The weather data used in the modelling may not be representative of the conditions on site and may not therefore represent the worst case scenario.

5. The dispersion modelling assumes both coal and overburden to have a density of 2.5 g/cm3. Use of these factors has not been sufficiently justified and may not therefore represent the worst case scenario.

Public Inquiry

9.7.6 During the Inquiry, the conclusions made by Mr Oates were discussed in more detail.

Silt Content

9.7.7 The assumption for the silt content used in the modelling was 8.4% which is the

factor used for Western Surface Coal Mining taken from US EPA AP-42. The factor does have a range which could lead to a worst-case an order of magnitude larger. However, information came to light at the Inquiry that the haul roads would most likely to be made of sandstone a material more appropriate to that found for the category Taconite Mining and Processing. The average silt content for this category was 5.8% and the range is much less varied. This evidence provides robustness to the study given that the silt content used was more likely to be a conservative assumption.

Dust Suppression Factors

9.7.8 The US EPA emission factors were determined from a number of measurements

undertaken in the considerably drier environments generally found in the United States. Therefore, it has been standard practice to use a 50% suppression factor for all fugitive dust emissions when looking at the wetter environment of the UK.

9.7.9 The use of a 90% suppression factor for the unpaved roads was based primarily on

the operational experience of David Mason, the Expert Witness for Glamorgan Power Company on working methods. In order to effectively increase the suppression




factor, bowsers would be used on the unpaved haul roads. Bowsers are a simple and predictable mitigation measure and are easy to obtain and operate. At the Varteg site the haul roads would be short and spray machines could be used which extend to whole width of the roads. As part of Mr Mason's proof, he provided a calculation to show that it was possible to enact the suppression of a 'wet day' (as defined in the AP-42) using bowsers. This evidence was not challenged.

Soil Moisture Content

9.7.10 The factors used for the soil moisture content for coal and soil were taken straight

from the US-EPA AP-42 manual and were the best available data.

Meteorological Data

9.7.11 Following criticism of the meteorological data used in the June 2010 assessment, wind direction, wind speed and rainfall data were taken from a closer, inland site at Twynyrodyn. Although, not identical to Varteg, the data from this site represented a closer approximation of conditions likely to occur at Varteg. It was also stated at the inquiry that it was very unusual to have site-specific meteorological data for modelling studies. In addition, worst-case conditions were used taking higher wind speeds for deposition of dust. Worst case (i.e. lowest) rainfall data was taken from the more local site at Twynyrodyn.

Density of Coal

9.7.12 Mr Oates quite correctly pointed out that in the dispersion modelling, both coal and

overburden were assumed to have a density of 2.5 g/cm3. In fact, the coal will have a lower density being of the order of 1.4 g/cm3. This value was not used in the modelling submitted in the November report, as we concentrated on the parameters the model was most sensitive to, namely the dust suppression factor and silt content of unpaved roads, rather than a factor which, from experience, we know the model is not particularly sensitive to and is only a small proportion of the total dust.

9.7.13 The model was re-run using a particle density of 1.4 g/cm3 to confirm the sensitivity

of the model to this parameter. The results indicate that the dust deposition rates do increase, but by less than 0.2%. This level of increase would not affect the submitted results significantly and, therefore, the conclusions of the report remain the same.

Inspector's Recommendations

9.7.14 Following the Inquiry, the Inspector recommended that the appeal be allowed and

that planning permission be granted subject to conditions.

9.7.15 The initial conclusion of the Minister in February 2013 was that the 'The Minister is minded to accept the Inspector's recommendation subject to the Section 106 Unilateral Undertaking being re-written to contain terms akin to a bilateral agreement with the Council, and for the unilateral agreement to provide, amongst other things, details of the proposed Restoration Bond and the justification of the




proposed value of security offered.' No further objections were raised with regard to air quality.

9.7.16 However, in November 2013, the new Minister refused the application because he

was of the opinion that other alternatives for carrying out the reclamation apart from the removal of the coal had been sufficiently identified and analysed. The refusal did not include any aspect relating to air quality.

9.8 Conclusions

9.8.1 Following the three air quality assessments and the Public Inquiry, the following

conclusions can be drawn:

1. The significance of the effect of the HGVs on local air quality at sensitive receptors is negligible.

2. The predictions indicated that the effects of the fugitive dust likely to be produced by the reclamation works were of negligible significance with regard to PM10 concentrations.

3. As agreed with Torfaen County Borough Council, the predicted results do not indicate any exceedences of the UK or European ambient air quality standards.

4. For scenarios with the expected operational mitigation measures, impacts were predicted to be below the weekly dust deposition threshold for the entire duration of the surface workings.

5. For scenarios with a lower dust suppression factor, exceedences of the weekly dust deposition threshold were predicted at the closest receptors. These scenarios were run as sensitivity tests rather than as expected conditions as due to the small scale of the unpaved haul roads and the enhanced mitigation measures that will be employed at the works, it is believed that the high level of mitigation modelled in the first two scenarios will be met even in the driest conditions.

6. During the Public Inquiry, the issues relating to silt content, dust suppression factor, moisture contents, meteorological data and coal densities were resolved in a robust manner.

7. The Inspector recommended that the appeal be allowed and that planning permission be granted subject to conditions.

8. The original decision by the Minister that he was minded to agree to the Inspector's recommendations made no additional reference to air quality.

9. The subsequent decision by the new Minister to refuse the scheme was not on the basis of air quality issues.

10. The fugitive dust assessments undertaken for the June 2010 assessment and the November 2011 assessment are up-to-date and still valid. No further assessment is required for this air quality chapter.

Appendices Appendix 9A Phase Maps Figure 9A.1 Operational Phase 1 Figure 9A.2 Operational Phase 2 Figure 9A.3 Operational Phase 3 Figure 9A.4 Operational Phase 4 Appendix 9B Equations Used to Estimate Dust Deposition Appendix 9C Meteorological Data




APPENDIX 9A

Phase Maps

Figure 9A.1 Operational Phase 1

W1

W2

W3

Haul Route 3

Haul Route 1

Haul Route 2





W1

W2

Haul Route 1

Haul Route 2





W1

W2

Haul Route 1

Haul Route 2





W2

Haul Route 1

W1




9B Equations Used to Estimate Dust Deposition

B.1 Wind Erosion

∑−

=N

iiPkE

1

)(*25)(*58 **2**

tt uuuuP −+−=

Where Pi Erosion potential corresponding to the observed fastest mile of wind

for the ith period between disturbances / g/m2 N the number of disturbances k Particle Size Multiplier u* Friction Velocity (0.053 x Fastest Mile) / m/s u*t Threshold Friction Velocity / m/s E Emission Factor units / g/m2/yr

Assumptions:

• Disturbed daily (worst-case). • The peak speed can be used as a proxy for the fastest mile. • Particle size distribution: <2.5 µm, 0.075; 2.5-10 µm, 0.425; >10 µm,

0.500.

B.2 Paved Roads

−

−

=

NPCWsLkE

41

32

5.165.0

Where P Number of wet days with at least 0.254 mm of rain N the number of days in the averaging period k Particle Size Multiplier sL Silt Loading / g/m2 W Average weight (tons) of vehicles using the road C Emission factor of 1980s fleet / g/veh-km E Emission Factor / g/veh-km Assumptions:

• Silt loading 8.2 g/m2 for haul roads (used for quarries) and 0.2 g/m2 for Varteg Road (public road).

• Overburden trucks are 33 tonnes unladen and 73 tonnes fully laden. • Soil trucks are 12 tonnes unladen and 32 tonnes fully laden. • Coal trucks are 12 tonnes unladen and 32 tonnes fully laden.




• Particle size distribution: <2.5 µm, 0.028; 2.5-10 µm, 0.164; >10 µm, 0.808.

B.3 Unpaved Roads

( )

−

=

365365

312PWskE

ba

Where P Number of wet days with at least 0.254 mm of rain k Particle Size Multiplier s Silt Content / % W Average weight (tons) of vehicles using the road E Emission Factor / g/veh-km

Assumptions: • Silt content 8.4% for haul roads (AP42 Table 13.2.2-1). • Overburden trucks are 33 tonnes unladen and 73 tonnes fully laden. • Soil trucks are 12 tonnes unladen and 32 tonnes fully laden. • Coal trucks are 12 tonnes unladen and 32 tonnes fully laden. • Particle size distribution: <2.5 µm, 0.031; 2.5-10 µm, 0.276; >10 µm,

0.694.

B.4 Materials Handling

( )

= 4.1

3.1

2

2.20016.0M

U

kE

Where U Mean Wind Speed / m/s M Moisture Content / % k Particle Size Multiplier E Emission Factor / kg/tonne

Assumptions:

• Moisture content 6.9% for coal and 3.4% for overburden / soil (Western Surface Mining).

• Calculated daily using mean wind speed for that day. • Particle size distribution: <2.5 µm, 0.072; 2.5-10 µm, 0.401; >10 µm,

0.527.




B.5 Bulldozing

( )( )

= b

a

MskE

Where s Silt Content / % M Moisture Content / % k Particle Size Multiplier a Empirical Parameter (1.2 for TSP and 1.5 for PM10) b Empirical Parameter (1.4 for TSP(coal) and PM10; 1.3 for

TSP(overburden)) E Emission Factor / kg/hour

Assumptions: • Moisture content 10.4% for coal and 7.9% for overburden / soil (AP-42

Table 11.9-3). • Silt Content 8.6% for coal and 6.9% for overburden / soil (AP-42

Table 11.9-3). • Rain corrected as for unpaved roads. • Particle size distribution: <2.5 µm, 0.022; 2.5-10 µm, 0.156; >10 µm,

0.822.




9C Meteorological Data B.1.1 Meteorological data measured at Twynyrodyn for the year 2009 were used for this

modelling study. In the previous study four years of meteorological data were considered to account for fluctuations in weather conditions and 2009 was considered to be the worse-case year.

Figure 9C.1 Windrose, Twynyrodyn 2009




References 1 Welsh Assembly Government, Minerals Technical Advice Note 2:Coal, January 2009 2 Institute of Air Quality Management, Significance in Air Quality, November 2009. http://www.iaqm.co.uk/text/guidance/iaqm_significance_nov09.pdf 3 US Environmental Protection Agency, Compilation of Air Pollutant Emission Factors, Volume 1: Stationary Point and Area Sources, AP-42 Fifth Edition 4 Defra, Background Maps, http://laqm.defra.gov.uk/review-and-assessment/tools/background-maps.html

http://www.iaqm.co.uk/text/guidance/iaqm_significance_nov09.pdf

http://laqm.defra.gov.uk/review-and-assessment/tools/background-maps.html

Documents

9. AIR QUALITY 9.1 Introduction 2/ES...Having agreed with TCBC that the significance of the impact on local air quality would be negligible, this work concentrated on the potential