Chapter 2.10. Air Quality Assessment - WordPress.com · 1/2/2014 · South Bristol Link:...

Chapter 2.10. Air Quality Assessment

10. Air Quality

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10. Air Quality

10.1. Introduction and Scope

10.1.1. This chapter presents the air quality assessment for the South Bristol Link (SBL). The scope of the assessment has been established by the EIA scoping stage and subsequent scoping responses, details of which are set out in Chapter 1 of this Environmental Statement (ES) and through consultation with the Programme Co-ordinator for Air Environment at Bristol City Council (BCC). The assessment addresses those impacts that have been scoped in as potentially significant in the context of the SBL; including:

Construction phase impacts, with focus on the risk of dust impacts

Operational phase impacts due to road traffic emissions affecting local air quality at sensitive

human receptors

Carbon emissions from road traffic

10.1.2. The following section briefly outlines the relevant legislation, policy and guidance that inform the assessment and its findings. This is followed by a description of the assessment methodology. Baseline local air quality conditions are then described, followed by the assessment of the potential impacts of the SBL. Mitigation measures are then described to address any potentially significant adverse effects. Remaining (residual) effects are considered and likely cumulative effects considered. The key findings and overall conclusions of the assessment are then presented in a summary section at the end of this chapter, with supporting information in an appendix to this chapter in Volume 3.

10.2. Air Pollutants

10.2.1. Dust is important in terms of amenity. Dust levels that are substantially elevated above the norm can cause annoyance. This commonly relates to increased rates of dust deposition on exposed surfaces and/or soiling (discolouration/contamination).

10.2.2. The local air pollutants of concern are nitrogen dioxide (NO2) and particulate matter (PM). The key sources of these pollutants in relation to the SBL are road traffic (NO2 and PM10

1) and

construction activities (general PM, including PM10 and larger particle size fractions, which is collectively referred to as ‘dust’

2).

10.2.3. NO2 and PM10 are important in terms of public health, and account for the vast majority of designated air quality problem areas in the UK. Concentrations of these pollutants in excess of standards can be considered to have potentially adverse consequences at locations where there is relevant public exposure.

10.2.4. Carbon dioxide (CO2) is an important ‘Greenhouse Gas’. It is also considered as an air pollutant but in a wider regional context at national and international scales in relation to its impact on climate change rather than local air quality and public health. Road traffic is a substantial emitter of carbon dioxide.

10.3. Policy Context and Guidelines of Relevance

Planning Policy Guidance

10.3.1. Regional and Local Planning policy is set out in detail in Chapter 7 of this ES. It includes a description of the regional planning context for the scheme.

1

PM10 = particulate matter with an aerodynamic diameter less than 10 micrometres (µm) 2 Dust = defined as all particulate matter up to 75 μm in diameter and comprising both suspended and deposited dust

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10.3.2. Local planning policy guidance relevant to air quality and pollution control is also discussed in Chapter 7, including:

BCC Core Strategy policy BCS23 Pollution;

BCC 1997 Adopted Local Plan ‘saved’ policy ME2 Location and Design of Development;

BCC emerging policy DM33 Pollution Control, Air Quality and Water Quality; and,

North Somerset Core Strategy policy CS3 Environmental Impacts and Flood Risk

Assessment.

10.3.3. In March 2013, BCC published an ’Air Quality and Land Use Planning Guide’. This document includes a discussion on planning policy relevant to BCC, making specific reference to Core Strategy policy BCS23 (referenced above) and the general requirement to try and reduce pollution throughout the city and to improve air quality in the inner city and AQMA. The guidance relates specifically to the land development sector (residential, commercial and industrial development) in the local BCC context but is concordant with more widely applicable guidance relating to air quality impact assessment (see sub-section on ‘Relevant Guidance’ below).

Legislation and Other Policy Advice

10.3.4. Mandatory European Union (EU) air quality limit values are given in The Air Quality Standards Regulations 2010 (Ref. AQ1). Compliance with these limit values is the responsibility of the UK Government’s Secretary of State.

10.3.5. At a local level, air quality objectives are given by The Air Quality (England) Regulations 2000 (Ref.

AQ2) and The Air Quality (England) (Amendment) Regulations 2002

(Ref. AQ3). These objectives are

to be achieved by local authorities in accordance with the UK Government’s Air Quality Strategy (AQS)

(Ref. AQ4). The AQS objectives only apply in locations with ‘relevant exposure’, i.e. where

members of the public are exposed for periods equal to or exceeding the averaging periods set for the standards. Relevant local air quality criteria for NO2 and PM10 are given in Table 10.1.

10.3.6. There are no statutory standards for ambient dust levels, although general provisions for controlling dust emissions from construction sites are included under the Environmental Protection Act 1990

(Ref. AQ5) in relation to ‘Statutory Nuisance’. Detection and the requirement for

action to stop any Statutory Nuisance are responsibilities of the relevant local authority. To avoid causing a Statutory Nuisance, use of ‘Best Practicable Means’ (BPM) to limit emissions must be evident.

Table 10.1: Relevant Local Air Quality Assessment Criteria

Pollutant Objective

Nitrogen dioxide (NO2)

Hourly average concentration should not exceed 200 µg/m3 more than 18 times a

year

Annual mean concentration should not exceed 40 µg/m3

PM10 (gravimetric) 24-hour mean concentration should not exceed 50 µg/m3 more than 35 times a

year

Annual mean concentration should not exceed 40 µg/m3

Notes:

µg/m3 = micrograms per cubic metre

National Planning Guidance

10.3.7. The planning guidance of general relevance for air quality is found within the National Planning Policy Framework

(Ref. AQ6). Paragraph 124 states that:

“Planning policies should sustain compliance with and contribute towards EU limit values or national objectives for pollutants, taking into account the presence of Air Quality Management Areas and the cumulative impacts on air quality from individual sites in local areas. Planning

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decisions should ensure that any new development in Air Quality Management Areas is consistent with the local air quality action plan.”

Local Air Quality Management

10.3.8. Under Part IV of the Environment Act 1995 (Ref. AQ7), all local authorities are responsible for LAQM in accordance with the AQS. Under the LAQM regime, a local authority is responsible for regular review and assessment of local air quality, the findings of which are reviewed by the Department for Environment, Food & Rural Affairs (Defra) prior to publication by the local authority. If an area is identified as being unlikely to achieve an AQS objective and there is relevant exposure, then the local authority is required to designate an Air Quality Management Area (AQMA) and develop an Action Plan to improve local air quality.

Joint Local Transport Plan 3

10.3.9. The Joint Local Transport Plan 3 (JLTP3) has been produced by the West of England Partnership authorities

(Ref. AQ8) and includes commitment to reduce transport related carbon emissions by:

“... focusing on the promotion of lower carbon travel choices, providing alternatives to the car, influencing travel behaviour and managing demand.”

10.3.10. The JLTP3 also commits to integration with LAQM aims, in particular local air quality Action Plans to stabilise and improve local air quality within AQMA

“...we [West of England Partnership] will continue to ensure that the policies and measures they [West of England Partnership authorities] put forward [in local air quality Action Plans] are integrated with those in the JLTP3...”

Relevant Guidance

10.3.11. Specific guidance for assessment of road infrastructure schemes is given by the Highways Agency’s Design Manual for Roads and Bridges in Volume 11, Section 3, Part 1 ‘Air Quality’ (DMRB)

(Ref. AQ9). This guidance covers the assessment of impacts of road schemes on local and

regional air quality, and in relation to designated ecological sites. The DMRB also provides a simple procedure for considering road scheme construction dust impacts. Additional guidance concerning local air quality is given by Defra’s AQS technical guidance LAQM.TG(09)

(Ref. AQ10);

whilst this primarily addresses LAQM activities, the guidance provides relevant methods concerning treatment and interpretation of data that are not completely addressed by the DMRB.

10.3.12. Guidance relating to new developments, including those requiring new transport infrastructure, has been developed by Environmental Protection UK (EPUK) in conjunction with the Institute of Air Quality Management (IAQM) and published in the document ‘Development Control: Planning For Air Quality (2010 Update)’

(Ref. AQ11). The guidance provides assessment scoping criteria

applicable to proposals affecting road transport, which complement the more specific scoping criteria for road schemes given in the DMRB. The guidance also provides significance criteria for air quality assessment.

10.3.13. Guidance regarding assessment of construction dust is provided by Greater London Authority and London Councils’ ‘The control of dust and emissions from construction and demolition - Best Practice Guidance’

(Ref. AQ12).

10.4. Assessment Methodology

Identification of Baseline Conditions and Sensitivity

10.4.1. The discussion of baseline air quality conditions draws on information provided by BCC, including LAQM reports and local monitoring data, and from Defra’s UK-AIR information resource

(Ref. AQ13),

which includes background concentration data.

10.4.2. Relevant locations with public exposure that are potentially sensitive to NO2 and PM10 - including residential, medical and educational premises - have been identified from Ordnance Survey data and aerial photographs. Potentially sensitive ecological sites, which are defined by the DMRB as

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sites with statutory designation of national and international importance (i.e. SSSI, SPA, SAC and Ramsar), have been identified using GIS-based data obtained from Natural England

(Ref. AQ14).

Methodology for Construction Impacts

10.4.3. Construction impacts are likely to be limited to dust associated with construction sites and emissions from site vehicles/plant and road traffic. Dust may have two impacts:

Cause annoyance due to surface deposition/soiling, with potential to cause a statutory

nuisance if inadequately mitigated; and/or

Reduce local air quality due to emissions of PM from construction activities and site

vehicles/plant (potentially affecting PM10 concentrations), with potential to cause significant

effects if inadequately mitigated.

10.4.4. Significant local air quality effects due to road traffic may result if there are substantial movements of construction vehicles and/or disruption to general traffic due to traffic management measures (including diversion) over the period of construction. However significant effects would only be expected if such a situation were to occur over periods of one year or more in locations where there is relevant exposure within 200 m of affected routes and poor baseline air quality.

10.4.5. For this assessment, construction impacts have been considered in qualitative terms, with reference to the GLA and London Councils’ best practice guidance. Risk of causing adverse significant impacts has been considered to inform recommendations for mitigation.

10.5. Methodology for Operational Impacts

Local Air Quality (Public Health)

Overview

10.5.1. To assess potential operational road traffic impacts on local air quality, guidance given in the DMRB, LAQM.TG(09) and EPUK have been referred to. The spatial extent of the study area for assessment has been defined using scoping criteria adopted from the guidance, as agreed in the scoping report

(Ref. AQ15).

10.5.2. Quantification of operational road traffic air quality impacts has been undertaken by dispersion modelling using ADMS Roads software. Dispersion modelling enables the estimation of pollutant concentrations at receptors using data defining:

source activity;

local meteorological conditions, which are responsible for pollutant dispersion between

source and receptor; and

the position of sensitive receptors relative to sources.

10.5.3. Models of three main scenarios have been produced, as follows:

2011 base year, to permit verification against any available relevant monitoring data;

2016 do-minimum (including committed development but without the SBL); and

2016 do-something (including committed development but with the SBL).

10.5.4. Significance criteria given in the EPUK guidance have been applied. The criteria enable significance to be determined according to the differences in concentrations estimated for the do-something and do-minimum scenarios and take into account any exceedances of air quality criteria that would be created or removed, worsened or lessened.

10.5.5. The BCC Programme Co-ordinator for Air Environment has been consulted on the modelling methodology and the spatial extent of the study area, which are agreed

(Ref. AQ16).

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Traffic Data

10.5.6. Traffic data were supplied by the Atkins transport modelling team from the ‘G-BATS3’ traffic model. For each scenario, the data comprised:

Annual average daily traffic (AADT) flows by light duty vehicle (LDV) and heavy duty vehicle

(HDV) types, and speeds;

AM peak, inter-peak and PM peak LDV and HDV flows and average speeds; and

Diurnal total traffic flow profiles for a typical weekday, Saturday and Sunday.

10.5.7. The AADT data were used to define the affected road network (those roads meeting the relevant change criteria – defined below), which was then used to determine the study area/overall model domain

3.

Spatial Scope – Study Area

10.5.8. The first step has been to identify the ‘affected road network’ (ARN), i.e. those road sections where changes in traffic conditions brought about by the SBL could result in significant impact. For road schemes, it is standard practice to apply DMRB (HA 207/07) criteria that define a road link as ‘affected’ if:

road alignment will change by 5 m or more; or

daily traffic flows will change by 1,000 AADT flow or more; or

HDV flows will change by 200 AADT or more; or

daily average speed will change by 10 km/hr or more; or

peak hour speed will change by 20 km/hr or more.

10.5.9. Additional scoping criteria have been provided by Environmental Protection UK (as updated in 2010) to determine whether a road may be considered ‘affected’ and therefore subject to further assessment:

Proposals that will give rise to a significant change in either traffic volumes, typically a

change in AADT or peak traffic flows of greater than ±5% or ±10%, depending on local

circumstances (a change of ±5% will be appropriate for traffic flows within an AQMA), or in

vehicle speed (typically of more than ±10 kph), or both, usually on a road with more than

10,000 AADT (5,000 if narrow and congested); or

Proposals that would significantly alter the traffic composition on local roads, for instance,

increase the number of HDVs (>200 movements or more per day), due to the development

of a bus station or a HGV park (professional judgement will be required, taking account of

the total vehicle flow as well as the change); or

Proposals that include significant new car parking, which may be taken to be more than 100

spaces outside an AQMA or 50 spaces inside an AQMA. Account should also be taken of

car park turnover, i.e. the difference between short-term and long-term parking, which will

affect the traffic flows into and out of the car park. This should also include proposals for new

coach or lorry parks. These criteria are designed to trigger the requirement for the

assessment of traffic on the local roads. It may also be appropriate to assess the emissions

from within the car park itself.

10.5.10. As agreed in the scoping report for the SBL, the ARN has been determined by employing the two sets of criteria as follows:

The DMRB change criteria were applied to traffic model links that are not within the BCC

AQMA or AQMA buffer zone.

The EPUK criteria were applied to traffic model links that are within the BCC AQMA or

AQMA buffer zone.

10.5.11. In both cases, the changes have been considered using combined two-way traffic data, which is in accordance with the guidance on defining ARN.

3 In fact, three model domains were defined. This is discussed in subsequent sections.

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10.5.12. In defining the ARN, due consideration has been given to uncertainties associated with the traffic model data, in particular the spatial extent to which the traffic model yields reliable data and the reliability of the derived parameters that are themselves not direct outputs of the traffic model; these derived parameters include total AADT, HDV numbers and speeds. Apart from road alignment change, the key statistic (most reliable and wide ranging) in defining the ARN is usually the change in total AADT. The traffic model’s detailed focus is on the Bristol road network to the south of the River Avon. This area is defined in the Local Model Validation Report (LMVR) as the ‘Area of Detailed Modelling’

(Ref. AQ17). Traffic model links considered for inclusion in the ARN have

been based on: a) routes within the ‘Area of Detailed Modelling’ and b) those routes within the ‘Fully Modelled Area’ that have been validated by traffic counts - including the A370 in North Somerset.

10.5.13. The ARN has then been reviewed to identify locations where there are relevant receptors within 200 m of an affected road, where there are relevant AQMA, and locations of relevant air quality monitoring sites to be used in verification of the local air quality base model.

10.5.14. Where receptors have been identified close to affected roads, then the detailed air quality model makes use of all available and relevant traffic links within 200 m of the receptor (i.e. not just the ARN). The resultant study area is shown in Figure 10.1.

10.5.15. For modelling purposes, the study area was divided in to three separate domains, as follows:

Model domain 1: representing the area of Bristol to the south of the River Avon including

Bedminster

Model domain 2: representing the Bishopsworth suburb of Bristol to the south of model

domain 1, and including the elements of the SBL scheme

Model domain 3: representing the rural area of North Somerset to the west of model domain

2, and including the elements of the SBL scheme

Figure 10.1: Study Area for Local Air Quality Assessment

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Emission Factors

10.5.16. Vehicle exhaust emissions of NOx for light duty vehicles (LDV) and heavy duty vehicles (HDV) have been calculated using Defra’s Emission Factor Toolkit (EFT), version 5.2c

(Ref. AQ18), for each

road link in each modelled scenario.

Meteorological Data

10.5.17. Hourly sequential meteorological data were obtained for the nearest suitable weather station, in this case Bristol Lulsgate with missing data from Lyneham, for the year 2011 (the base year in the assessment). The basic data include: date, hour, direction that the wind is blowing from, wind speed, how many eighths (‘oktas’) of the sky are covered by cloud, and surface air temperature.

10.5.18. A windrose for Lulsgate is presented in Figure 10.2; this shows winds predominantly (i.e. prevailing) from the west-southwest.

10.5.19. When the dispersion model is run, the meteorological data are processed an hour at a time to generate values for other parameters that describe atmospheric turbulence. These data are then used to calculate dispersion and thus estimate pollutant concentrations in ambient air.

10.5.20. The surface roughness value assumed for Lulsgate was 0.2 m. The surface roughness for the study area was assumed to be 0.5 m in the urban/more central Bristol area, and 0.3 m in the western, more rural section of study area. The value for the parameter that limits occasions of very stable conditions with minimal thermal turbulence, known as the ‘minimum Monin-Obukhov length’, was assumed to be as per the model default for both Lulsgate and the wider study area. In this model default setting, the minimum Monin-Obukhov length is calculated based on the specified surface roughness.

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Figure 10.2: Windrose for Lulsgate Weather Station, 2011

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Receptors

10.5.21. Relevant receptors in terms of public health include residential properties and sites where there are likely to be vulnerable occupants, such as hospitals, nursing homes and schools. There are no designated ecological sites that would be affected within 200 m of the ARN.

10.5.22. Concentrations have been estimated at discrete receptors. To sufficiently capture the impact of the SBL, more than 200 receptors representative near road properties have been included in modelling; these are shown in Figure 10.1. Generally, these receptors are the nearest to the affected road network and will reflect the greatest changes in concentrations with the SBL. Additional receptor points representing roadside monitoring sites have also been included for model verification (discussed below).

Background Concentrations

10.5.23. When estimating (total) pollutant concentrations, it is necessary to specify background concentrations onto which the road contribution can be added. Estimates of current and future year background pollutant concentrations in the UK are available on Defra’s air quality website. Background estimates are available for one kilometre grid squares throughout the UK for years between 2010 and 2030.

10.5.24. Estimated background concentrations for the years 2011 (assessment base year) and 2016 (SBL opening year) for NO2 and PM10 were obtained from the background mapping provided on the Defra website. For a conservative assessment, ‘in square’ major road source sector contributions have not been removed in locations where these sources have been explicitly represented as sources in the dispersion model.

Conversion of NOX to NO2

10.5.25. To derive total NO2 concentrations from the modelled road NOx concentrations (and hence to allow a comparison with the air quality criteria) the method described in Defra’s AQS technical guidance LAQM.TG(09) was used. Total annual mean NO2 was calculated from the modelled road NOx and total background NO2 component from Defra background mapping.

10.5.26. The conversion was carried out using the ‘NOx to NO2 conversion spreadsheet’ version 3.2, which is available from the Defra website. An ‘all UK traffic’ vehicle fleet mix was assumed to approximate primary NO2 emissions from vehicles on local roads and the regional fraction of NOx emitted as NO2.

Model Uncertainty

10.5.27. Any dispersion model has inherent areas of uncertainty, including:

Traffic data;

Appropriateness of emissions data;

Simplifications in model algorithms and empirical relationships that are used to simulate

complex physical and chemical processes in the atmosphere;

Appropriateness of background concentrations; and

Appropriateness of meteorological data.

10.5.28. Uncertainty associated with traffic data has been minimised by using validated traffic model data.

10.5.29. Uncertainties associated with emissions and background concentration data have been minimised by using the most recent appropriate published data from Defra.

10.5.30. Uncertainties associated with model algorithms and empirical relationships have been minimised by using algorithms and relationships that have been independently validated and judged as fit for purpose.

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10.5.31. Lulsgate is the nearest and most representative weather station that can provide the necessary data for modelling. To account for differences in land use, which affects atmospheric turbulence (at the weather station and in the study area), separate appropriate surface roughness coefficients have been assigned. Also, to better reflect the influences of natural and paved surfaces on thermal turbulence, an appropriate minimum Monin-Obukhov length has been assigned.

10.5.32. Another uncertainty is with using historical meteorological data to estimate future concentrations. The key limiting assumption is that conditions in the future will be the same as in the past; however, in reality no two years are - or will be - the same. Defra’s guidance LAQM.TG(09) reviews a number of studies examining inter-annual variability of meteorological data and the effect on dispersion model output; it is suggested that variability in source contribution should be no more than 30% between any two years.

Model Verification

10.5.33. Model verification is the process by which uncertainties in the modelling are investigated and, wherever possible, minimised. The verification step involves comparison of modelled pollutant concentrations at suitable monitoring sites with monitored values that are representative of the base model period (in this case 2011). Verification is discussed further under the following section 0 before presenting the assessment of local air quality impacts.

Sensitivity Test

10.5.34. As it is unclear from UK NO2 monitoring data as to whether or not downwards trends in annual mean concentrations can be assumed at roadside and background sites (at least in the next few years up until 2017), the models for 2016 have been re-run on the assumption that individual vehicle emissions and background concentrations do not change from 2011. This consideration is in keeping with LAQM guidance, published in April 2012, on projecting NO2 concentrations

(Ref.

AQ19).

Significance Criteria

10.5.35. Relevant air quality criteria are given in Table 10.1. Estimated ambient concentrations in the existing and future years of assessment, and the change due to the proposed SBL, have been compared with these criteria. Criteria for assessing the magnitude of likely impacts are provided below.

10.5.36. Descriptors for changes in ambient concentrations of NO2 and PM10 have been developed by the IAQM and are provided in the EPUK’s air quality guidance for developments. Descriptors for magnitude of change are given in Table 10.2 and are as agreed in the SBL scoping report.

10.5.37. The impact significance descriptors take account of the magnitude of change (both positive and negative) and the absolute concentration in relation to the AQS objective. These descriptors are provided in Table 10.3 for annual mean NO2 and PM10 and Table 10.4 in relation to the 24-hour PM10 AQS objective.

Table 10.2 EPUK Descriptors for Changes in Ambient Concentrations of NO2 and PM10

Magnitude of Change Annual Mean PM10/NO2 Number of Days PM10 Concentration Above 50 µg/m

3

Large Increase/Decrease >4 µg/m3 Increase/decrease >4 days

Medium Increase/Decrease 2 - 4 µg/m3 Increase/decrease 2 - 4 days

Small Increase/Decrease 0.4 – 2 µg/m

3

Increase/decrease 1 – 2 days

Imperceptible Increase/Decrease <0.4 µg/m3 Increase/decrease <1 day

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Table 10.3: EPUK Descriptors for Impact Significance for Annual Mean NO2 and PM10

Absolute Concentration in Relation to AQS Objective

Change in Concentration

Small Medium Large

Increase with SBL

Above AQS Objective with SBL (>40 µg/m3)

Slight Adverse Moderate Adverse

Substantial Adverse

Just below AQS Objective with SBL (36 - 40 µg/m3)

Slight Adverse Moderate Adverse

Moderate Adverse

Below AQS Objective with SBL (30 -36 µg/m3)

Negligible Slight Adverse Slight Adverse

Well Below AQS Objective with SBL (<30 µg/m3)

Negligible Negligible Slight Adverse

Decrease with SBL

Above AQS Objective without SBL (>40 µg/m3)

Slight Beneficial Moderate Beneficial

Substantial Beneficial

Just below AQS Objective without SBL (36 - 40 µg/m3)

Slight Beneficial Moderate Beneficial

Moderate Beneficial

Below AQS Objective without SBL (30 - 36 µg/m3)

Negligible Slight Beneficial Slight Beneficial

Well Below AQS Objective without SBL (<30 µg/m3)

Negligible Negligible Slight Beneficial

Table 10.4: EPUK descriptors for impact significance for 24-hour mean PM10

Absolute Concentration in Relation to AQS Objective

Change in Concentration

Small Medium Large

Increase with SBL

Above AQS Objective with SBL (>35 days) Slight Adverse

Moderate Adverse

Substantial Adverse

Just below AQS Objective with SBL (32 - 35 days)

Slight Adverse

Moderate Adverse

Moderate Adverse

Below AQS Objective with SBL (26 -32 days) Negligible Slight Adverse Slight Adverse

Well Below AQS Objective with SBL (<26 days) Negligible Negligible Slight Adverse

Decrease with SBL

Above AQS Objective with SBL (>35 days) Slight Beneficial

Moderate Beneficial

Substantial Beneficial

Just below AQS Objective with SBL (32 35 days)

Slight Beneficial

Moderate Beneficial

Moderate Beneficial

Below AQS Objective with SBL (26 -32 days) Negligible Slight Beneficial Slight Beneficial

Well Below AQS Objective with SBL (<26 days) Negligible Negligible Slight Beneficial

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Regional Greenhouse Gas Emissions

10.5.38. Traffic data for the regional assessment were supplied by the Atkins transport modelling team from the ‘G-BATS3’ traffic model.

10.5.39. Five scenarios have been considered:

2011 base year;

2016 opening year do-minimum;

2016 opening year do-something;

2031 SBL design year do-minimum; and

2031 SBL design year do-something.

10.5.40. The assessment focuses on traffic model links with a combined two-way AADT flow change in 2016 of greater than 10% with the SBL - compared to without the SBL. Operational emissions of carbon have been quantified using current emission factors for carbon dioxide included in EFT version 5.2c. For every tonne of carbon dioxide emitted, approximately 0.273 tonnes is carbon.

10.5.41. The EFT includes DfT and Defra supported assumptions for gradual improvements in vehicle related technologies spreading across the vehicle fleet which would result in progressive reduction in average vehicle carbon emissions up to 2030. Total annual carbon emissions have been calculated for 2011 and do-minimum and do-something scenarios in 2016 and 2031, and the differences between the years and scenarios considered. As there are no significance criteria for greenhouse gases, only commentary on the changes has been provided.

10.6. Baseline Conditions and Sensitivity

Local Air Quality

10.6.1. In undertaking its LAQM duties, BCC carries out routine monitoring of local air quality; these sites are concentrated towards the central Bristol area with no sites in the vicinity of the SBL route. NSC has no monitoring sites in the vicinity of the SBL scheme. To indicate baseline concentrations along the SBL route, where there are no established monitoring sites, Atkins was commissioned to undertake a three month NO2 diffusion tube survey in 2012.

10.6.2. There are 20 BCC monitoring sites within the study area; these are listed in Table 10.5 and shown in Figure 10.3. All but one (Greville Smyth Park) is within the Bristol AQMA. All monitor annual mean concentrations of NO2. Of the 20 sites, 19 are passive diffusion tubes and one is a continuous monitoring station (CMS), which is located at Parson Street School (BCC site reference: 215). There is no monitoring of PM10 within the study area. There are no long term monitoring sites in the vicinity of the ARN within North Somerset.

10.6.3. Annual mean concentrations of NO2 for the years 2007 to 2011 inclusive at BCC sites are given in Table 10.5. With the exception of three monitoring sites (BCC site refs: 99, 465 and 468), exceedances of the annual mean air quality objective for NO2 (40 µg/m

3) have been observed

consistently at roadside locations over the five-year period presented.

10.6.4. Concentrations in the area around Parson Street railway station at BCC site refs: 215, 238, 239, 240, 242, 243, 418 and 419 – as shown in Figure 10.3 - have been consistently very high. This is consistent with increased vehicle emissions during the periods of severe traffic congestion that are experienced around this location, and also the road gradients in the area. With the exception of BCC site ref. 5, concentrations at roadside sites away from the Parson Street area are noticeably lower; this is likely to reflect less severe traffic congestion and the relatively gentle road gradients. The BCC site ref. 5 on Bedminster Parade is located in a street with relatively tall buildings either side of the footways; the high concentrations at this site are likely to be due to a ‘street canyon’ effect whereby in-street pollutants can build up and result in higher concentrations than would be experienced in a more open situation.

10.6.5. Annual mean concentrations of NO2 at the urban background site at Greville Smyth Park (BCC site ref. 99) have been below the annual mean air quality objective in recent years, indicating that

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at locations away from the main traffic routes, annual mean concentrations of NO2 are likely to be below the relevant air quality objective.

Table 10.5 Annual Mean NO2 Concentrations (µg/m3) Measured by BCC (2007 to 2011)

BCC site ref

Site name Type X Y 2007 2008 2009 2010 2011

5 Bedminster Parade R 358723 171704 72.1 57.8 60.3 66.6 57.2

99 Greville Smyth Park UB 357099 171627 33.4 30.8 26.9 32.7 28.1

215 Parson Street School (CMS)

R 358042 170582 49.8 50.5 50.3 50.5 48.2

238 Parson Street School R 358005 170504 59.7 57.2 58.9 54.7 52.4

239 Parson Street A38 East

R 357880 170506 83.1 87.8 83.5 81.3 82.0

240 Parson Street A38 West

R 357599 170474 53.2 50.7 56.1 54.9 47.3

242 Bedminster Down Road

R 357510 170401 60.9 65.3 72.0 80.3 75.5

243 Parson Street Chip Shop

R 357897 170606 48.5 46.3 51.1 49.1 44.6

418 Bedminster Down Lamppost

RF 357737 170642 92.4 89.4 94.6 92.9 90.5

419 Parson Street Lamppost

RF 357832 170686 66.5 58.5 63.8 63.2 54.7

420 North Street/Dean Lane

RF 358274 171561 47.6 44.0 42.0 43.8 39.6

422 North Street/Langton Park

RF 358168 171525 44.0 41.7 43.1 43.4 41.2

439 Parson Street School R 358042 170582 45.6 43.5 44.3 41.9 40.9

465 North Street School Fence

R 357361 171713 No Data

No Data

28.6 34.6 30.2

466 Savanna Coffee Drainpipe

R 357466 171622 No Data

No Data

37.9 41.1 39.7

467 Strada Exeter Road R 357568 171537 No Data

No Data

32.4 40.7 33.4

468 Facade of North Street near Myrtle Street

R 357839 171427 No Data

No Data

26.6 31.8 28.5

472 Jamiesons Autos R 358226 171284 No Data

No Data

47.0 52.4 47.4

473 B&G Snax West Street

R 358105 171124 No Data

No Data

46.1 49.2 43.1

474 Martial Arts West Street

R 357991 170979 No Data

No Data

42.9 45.1 39.7

Notes:

R = roadside, RF = roadside facade, UB = urban background

Concentrations shown in bold are in excess of the AQS objective of 40 µg/m3

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194

Figure 10.3: Local Authority Monitoring Sites in Study Area

10.6.6. BCC’s 2012 LAQM Updating and Screening Assessment (Ref. AQ20)

indicates that NO2 concentrations as measured at BCC monitoring stations throughout the city have been relatively stable between 2002 and 2011, with concentrations in 2010 being slightly higher at many sites. This is true of the diffusion tube monitoring data for the study area (Table 10.5), where annual mean NO2 concentrations in 2011 are, in the majority of cases, slightly lower than in 2010.

10.6.7. BCC has observed that concentrations of PM10 as measured at the Old Market (roadside) and St. Pauls (AURN, urban background) automatic monitoring sites have been consistently below the annual mean air quality objective (40 µg/m

3) between 2007 to 2011 inclusive. A clear downward

trend in PM10 concentrations the Old Market roadside monitoring site has been noted, whilst concentrations at St. Pauls urban background site have fluctuated.

10.6.8. Results from the three month diffusion tube survey conducted by Atkins in 2012 along the SBL route (Figure 10.4) are given in Table 10.6 together with indicative annual mean concentrations. To indicate tube bias compared to BCC continuous measurements of NO2 and permit bias correction, a triplicate tube set was co-located at the Parson Street School CMS (BCC ref. 215). The results of the survey suggest that baseline concentrations along the route are relatively low and are consistent with the rural/suburban nature of the area. Concentrations at Highridge Green (Atk107), Chestnut Cottage (Atk108) and Castle Farm (Atk109) are typical of the rural environment away from major pollutant sources.

SBL ES: 2.10


195

Figure 10.4: Atkins Monitoring Sites in Study Area

SBL ES: 2.10


196

Table 10.6: Results of Atkins NO2 Diffusion Tube Survey in 2012

Site Id Site Name X Y May June July Raw average

Corrected average**

Annualised average***

Atk101 a

Parson Street school (co-location with BCC CMS site ref. 215)

358038 170584 47.1 33.3 45.6 42.0 36.1 47.7

b 45.1 * 44.6 44.9 38.6 51.0

c 45.1 * 43.1 44.1 37.9 50.1

Atk102 Whitland Road 357738 168485 27.7 11.2 18.7 19.2 16.5 21.8

Atk103 Cornleaze 357383 168358 17.6 7.7 10.7 12.0 10.3 13.6

Atk104 Innox Gardens 357239 168222 * 11.2 * N/A N/A N/A

Atk105 King George’s Road 1

356821 168224 21.4 * 15.4 18.4 15.8 20.9

Atk106 King George’s Road 2

356721 168218 * 6.7 10.1 8.4 7.2 9.5

Atk107 Highridge Green

356353 168552 16.8 7.0 9.4 11.1 9.5 12.6

Atk108 Chestnut Cottage

356329 168668 12.5 * 3.5 8.0 6.9 9.1

Atk109 Castle Farm 355734 168967 13.9 * 13.7 13.8 11.9 15.7

Atk110 Brook Gate 356082 170230 * * * N/A N/A N/A

Notes:

All concentrations in µg/m3

* Tube missing

** Correction factor = 0.86, as the ratio of the period average of the BCC CMS and Atk101 tubes a, b, c

*** Using LAQM.TG(09) method and data from all BCC CMS


10.6.9. Background annual mean concentrations of NOx, NO2 and PM10, which are indicative of all contributions from pollution sources across the study area, are provided by Defra background mapping. Maximum, minimum and average background concentrations for the base model year 2011 and SBL opening year of 2016 are given in Table 10.7. The highest background concentrations occur in the vicinity of Ashton Gate, near the River Avon. The lowest background concentrations occur to the west of Bishopsworth.

Table 10.7: Annual Mean background concentrations (µg/m3) within Study Area

Concentration units: µg/m3

NOx 2011 NO2 2011 PM10 2011 NOx 2016 NO2 2016 PM10 2016

Max 63.0 34.9 19.6 55.8 32.1 17.9

Min 19.3 13.6 13.6 15.9 11.4 12.8

Average 32.0 20.7 15.5 26.5 17.8 14.5

10.6.10. Potentially sensitive receptors with relevant public exposure have been identified in the study area, mainly residential premises. The locations of these are shown in Figure 10.1

SBL ES: 2.10


197

10.6.11. There are no potentially sensitive ecological sites designated as SSSI, SPA, SAC or Ramsar that would be affected within the study area. The air quality assessment therefore focuses on locations with relevant public exposure – i.e. local air quality (human health).


10.6.12. Estimated CO2 emissions data for the local authorities that make up the West of England Partnership (Bristol City Council, North Somerset Council, South Gloucestershire Council and Bath & North East Somerset Council) were obtained from the Department of Energy and Climate Change (DECC)

4 to provide an indication of current CO2 emissions in the SBL scheme area. The

most recent data sets available are for the year 2010.

10.6.13. Figure 10.5 and Figure 10.6 present estimated CO2 emissions in 2010 for BCC and NSC (combined) and the West of England Partnership authorities respectively. The data are presented on a sector basis, comprising emissions from industrial and commercial sources, domestic sources, road transport and all other sources

5.

10.6.14. Road transport in the BCC and NSC areas combined emitted approximately 1,028 kT (kilo or thousand tonnes) of CO2 in 2010, which equates to approximately 28% of total emissions (3,641 kT). Road transport sources across all West of England Partnership authorities emitted nearly 2,200 kT of CO2 in 2010, or approximately 32% of total emissions (6,797 kT).

Figure 10.5: Estimated CO2 Emissions for Bristol City Council and North Somerset Council in 2010

4 Local and Regional CO2 Estimates for 2005-2010; DECC (23/08/2012):

https://www.gov.uk/government/publications/local-authority-emissions-estimates 5 Includes CO2 emissions associated with land use, land use change and forestry

SBL ES: 2.10


198

Figure 10.6: Estimated CO2 Emissions for all West of England Partnership Authorities in 2010

10.7. Identification and Assessment of Likely Significant Effects

Construction Phase Effects

10.7.1. The potential area with construction activities is highlighted in Figure 10.7. The key area where fugitive dust emissions may arise is along the alignment of the SBL. The total area of the site exceeds the GLA’s criterion of 15,000 square metres and so results in a definition of ‘a high risk site’ for particulate emissions. Construction activities including site preparation, materials handling, stockpiling, and plant and vehicle movements over unpaved and paved surfaces all have the potential to generate fugitive dust emissions, particularly during dry conditions.

10.7.2. Construction dust impacts have the potential to affect approximately 2,280 residential properties, which are situated within 200 m of the site boundary. Over the period of construction, if there is inadequate mitigation, dust impacts have the potential to cause a ‘significant adverse’ effect; however, application of appropriate mitigation would be expected to minimise the risk to a ‘negligible’ effect.

10.7.3. Figure 10.2 shows the extent over which construction dust impacts could potentially occur and highlights the location of sensitive receptors. Receptors to the east of SBL are most at risk from windblown dust from site areas due to west-south westerly prevailing winds (Figure 10.2).

10.7.4. With regard to emissions of fine particulates, such as PM10, from construction vehicle and equipment exhaust systems, the impact is unlikely to be noticeable at receptors given low background concentrations in the affected areas and the temporary nature of the works.

SBL ES: 2.10


199

Figure 10.7: Construction Dust Impact

10.8. Operational Phase Effects

Local Air Quality Model Verification and Adjustment

10.8.1. Model verification has been undertaken for NO2 only. There are no suitable monitoring sites for PM10 within the study area. The verification process and model adjustment has been discussed and agreed with BCC

(Ref. AQ16).

10.8.2. Verification of the 2011 base model has been undertaken with comparison of modelled concentrations against those derived from monitoring at 15 BCC monitoring sites (shown in Figure 10.3). Verification determines model performance compared to real world measurements and enables adjustment – or calibration – to compensate for systematic error to bring estimated concentrations more into line with monitoring.

10.8.3. Overall, the model has required adjustment to address annual mean NO2 concentrations that would otherwise be underestimated. With adjustment the findings of the assessment as reported below are considered to be robust. Details of the verification and adjustment processes are given in Volume 3, Appendix 10.1.

Potential Local Air Quality Impacts

10.8.4. The effect of the SBL in terms of annual mean NO2 is presented in Table 10.8 (model domain 1), Table 10.9 (model domain 2) and Table 10.10 (model domain 3). The top ten receptors (residential properties and schools) with the highest do-something concentrations of NO2 in model domains 1 and 2 are shown. Concentrations for nine receptors in model domain 3 are given, as there are only nine in total. Results for all receptors are illustrated in Figure 10.8 (model domain 1),Figure 10.9 (model domain 2) and Figure 10.10 (model domain 3), and provided in Table B1 in Appendix 10.2 (Volume 3).

SBL ES: 2.10


200

10.8.5. For the 2016 do-minimum and do-something scenarios, two predicted (modelled) annual mean NO2 concentrations are presented: lower (L), representing standard model results, i.e. 2016 traffic data, 2016 emission factors and 2016 background concentrations; and upper (U), representing the sensitivity test, i.e. 2016 traffic data, 2011 emission factors and 2011 background concentrations. This approach therefore provides the likely range of concentrations for each modelled receptor in the 2016 assessment year.

Table 10.8: Model Domain 1 Annual Mean NO2 Concentrations (µg/m3) and Impacts

Receptor X Y 2011 base

2016 DM

2016 DS

Change (DS-DM)

Impact Magnitude

Impact

D1_180: Bedminster Road, Bristol, BS3 5NP

357972 170559 70.2 L:60.0

U:70.9

L:59.1

U:69.8

L:-0.9

U:-1.1

L:Small

U:Small

L:Slight beneficial

U:Slight beneficial


358031 170600 60.8 L:51.4

U:60.7

L:51.1

U:60.3

L:-0.3

U:-0.4

L:Imperceptible

U:Small

L:Negligible

U:Slight beneficial

D1_254: Parson Street Primary School, Bedminster Road, Bristol

357977 170531 69.8 L:60.4

U:71.6

L:59.6

U:70.7

L:-0.8

U:-0.9

L:Small

U:Small

L:Slight beneficial

U:Slight beneficial

D1_257: Parson Street Primary School, Parson Street, Bristol

357994 170508 60.7 L:52.6

U:63.0

L:51.8

U:62.1

L:-0.8

U:-0.9

L:Small

U:Small

L:Slight beneficial

U:Slight beneficial

D1_1000: Bedminster Road, Bristol, BS3 5NQ

357608 170480 66.7 L:56.3

U:68.1

L:51.4

U:62.1

L:-4.9

U:-6.0

L:Large

U:Large

L:Substantial beneficial

U:Substantial beneficial

D1_3000: Parson Street, Bristol, BS3 5PT

357943 170565 69.3 L:58.9

U:70.9

L:55.9

U:67.2

L:-3.0

U:-3.7

L:Medium

U:Medium

L:Moderate beneficial

U:Moderate beneficial

D1_7000: Temple Street, Bedminster, Bristol, BS3 3NF

357843 170683 65.2 L:55.1

U:67.2

L:51.8

U:63.1

L:-3.3

U:-4.1

L:Medium

U:Large

L:Moderate beneficial


D1_10000: Winterstoke Close, Bristol, BS3 2NG

357708 170659 65.3 L:55.3

U:66.9

L:51.0

U:61.8

L:-4.3

U:-5.1

L:Large

U:Large



D1_11000: Winterstoke Road, Bristol, BS3 2NQ

357644 170659 79.6 L:67.2

U:80.1

L:60.1

U:72.3

L:-7.1

U:-7.8

L:Large

U:Large



1_12000: Bedminster Down Road, Bristol, BS13 7AB

357709 170625 71.5 L:60.9

U:73.5

L:56.2

U:67.8

L:-4.7

U:-5.7

L:Large

U:Large



Notes:

L = lower estimate (standard model); U = upper estimate (sensitivity test)

SBL ES: 2.10


201


Figure 10.8: Model Domain 1 Annual Mean NO2 Concentrations (µg/m3) Without and With SBL (Lower Estimate)

SBL ES: 2.10


202



2016 DM

2016 DS

Change (DS-DM)

Impact Magnitude

Impact

D2_99: Bridgwater Road, Bristol, BS13 7AX

356346 169346 37.2 L:32.5

U:38.4

L:29.5

U:35.7

L:-3.0

U:-2.7

L:Medium

U:Medium

L:Slight beneficial


D2_4: Cater Road, Bristol, BS13 7SR

357415 168560 39.8 L:33.9

U:41.8

L:29.0

U:36.2

L:-4.9

U:-5.6

L:Large

U:Large

L:Slight beneficial


D2_36: Whitchurch Road, Bristol, BS13 7RS

357242 168702 38.1 L:32.8

U:40.3

L:27.7

U:34.4

L:-5.1

U:-5.9

L:Large

U:Large

L:Slight beneficial


D2_1001: Highridge Green, Bristol, BS13 8AB

356474 168444 22.7 L:19.3

U:23.1

L:27.5

U:33.0

L:8.2

U:9.9

L:Large

U:Large

L:Slight adverse

U:Slight adverse

D2_20001: Highridge Green, Bristol, BS13 8AA

356582 168332 23.5 L:19.9

U:24.2

L:27.4

U:33.2

L:7.5

U:9.0

L:Large

U:Large

L:Slight adverse

U:Slight adverse

D2_10001: Queens Road, Bishopsworth, Bristol, BS13 8LG

356991 168164 27.5 L:23.7

U:28.7

L:27.2

U:32.9

L:3.5

U:4.2

L:Medium

U:Large

L:Negligible

U:Slight adverse

D2_42: Queens Road, Bishopsworth, Bristol, BS13 8LG

356976 168134 28.1 L:24.2

U:29.5

L:26.7

U:32.2

L:2.5

U:2.7

L:Medium

U:Medium

L:Negligible

U:Slight adverse

D2_3: Whitchurch Road, Bristol, BS13 7RU

357342 168612 34.8 L:29.7

U:36.7

L:25.6

U:31.9

L:-4.1

U:-4.8

L:Large

U:Large

L:Slight beneficial


D2_16001: Highridge Road, Bishopsworth, Bristol, BS13 8HP

356605 168321 23.9 L:19.8

U:24.3

L:25.5

U:31.2

L:5.7

U:6.9

L:Large

U:Large

L:Slight adverse

U:Slight adverse

D2_17001: Grange Road Bishopsworth, Bristol

357045 168204 22.4 L:19.0

U:23.0

L:24.7

U:30.3

L:5.7

U:7.3

L:Large

U:Large

L:Slight adverse

U:Slight adverse

Notes:



SBL ES: 2.10


203

Figure 10.9: Model Domain 2 Annual Mean NO2 Concentrations (µg/m3) Without and With SBL

SBL ES: 2.10


204



2016 DM

2016 DS

Change (DS-DM)

Impact Magnitude

Impact

D3_97: Bridgwater Road, Bristol, BS13 8AE

356210 169283 33.0 L:27.2

U:34.1

L:23.0

U:28.2

L:-4.2

U:-5.9

L:Large

U:Large

L:Slight beneficial

U:Slight beneficial

D3_98: Bridgwater Road, Bristol, BS13 8AJ

355983 169376 20.2 L:19.1

U:20.4

L:19.7

U:21.3

L:0.6

U:0.9

L:Small

U:Small

L:Negligible

U:Negligible

D3_116: Property off Yanley Lane, Long Ashton

354998 170023 23.1 L:20.0

U:24.2

L:19.2

U:23.1

L:-0.8

U:-1.1

L:Small

U:Small

L:Negligible

U:Negligible

D3_117: Northleaze Primary School, Long Ashton

354957 170358 19.0 L:16.5

U:19.4

L:17.4

U:20.7

L:0.9

U:1.3

L:Small

U:Small

L:Negligible

U:Negligible

D3_118: Property off Yanley Lane, Long Ashton

354918 170187 20.0 L:17.3

U:20.7

L:18.0

U:21.7

L:0.7

U:1.0

L:Small

U:Small

L:Negligible

U:Negligible

D3_119: Residential property on Glebe Road, Long Ashton

355028 170446 21.9 L:18.9

U:22.4

L:19.8

U:23.7

L:0.9

U:1.3

L:Small

U:Small

L:Negligible

U:Negligible

D3_120: Residential property on Parsonage Road, Long Ashton

355156 170475 22.9 L:19.7

U:23.6

L:22.1

U:27.0

L:2.4

U:3.4

L:Medium

U:Medium

L:Negligible

U:Negligible

D3_122: Residential property on Parsonage Road, Long Ashton

355202 170590 21.9 L:18.9

U:22.4

L:20.4

U:24.5

L:1.5

U:2.1

L:Small

U:Medium

L:Negligible

U:Negligible

Notes:



SBL ES: 2.10


205

Figure 10.10: Model Domain 3 Annual Mean NO2 Concentrations (µg/m3) Without and With SBL

10.8.6. Of the 191 receptors modelled, only 16 locations are predicted to experience a ‘slight adverse’ impact in terms of annual mean NO2. These are all located in and around the route of the SBL in Bishopsworth (model domain 2). Beneficial (ranging from ‘slight beneficial’ to ‘substantial beneficial’) impacts are predicted at a total of 38 receptors, and ‘negligible’ impacts are predicted at 149 modelled receptors.

10.8.7. Under the sensitivity test, a total of 26 receptors are predicted to experience a ‘slight adverse’ impact in terms of annual mean NO2. Again, these are locations in and around the SBL in Bishopsworth, and also in the Ashton Gate area near the junction of the A370 and A3029 (model domain 1). A single receptor location on the A38 Bridgwater Road (model domain 3) is also predicted to experience a ‘slight adverse’ impact. Beneficial (ranging from ‘slight beneficial’ to ‘substantial beneficial’) impacts are predicted at 60 receptor locations under the sensitivity test, with ‘negligible’ impacts predicted at 117 of the modelled receptors.

10.8.8. Under the 2016 do-minimum scenario, exceedance of the annual mean air quality objective for NO2 is predicted at 30 locations, all within model domain 1 and all but two (D1_172: Bedminster

SBL ES: 2.10


206

Down Road, Bristol, BS13 7AF, D1_207: Winterstoke Road, Bristol, BS3 2NY – see Table B1 in Appendix 10.2 (Volume 3) for further information) within the BCC AQMA.

10.8.9. Under the 2016 do-something scenario, a total of 29 receptor locations are predicted to experience an exceedance of the annual mean air quality objective for NO2. However, under the 2016 do-something scenario, 26 of these 29 exceedance locations are predicted to experience an improvement in air quality in terms of annual mean NO2. The other three exceedance locations are expected to experience a negligible change in annual mean NO2 concentrations with the SBL in place. On this basis, the SBL scheme would assist with reducing the scale of the AQMA exceedances.

10.8.10. Under the upper case (using the sensitivity test), exceedance of the annual mean air quality objective for NO2 is predicted at 48 locations under the 2016 do-minimum scenario. Under the 2016 do-something scenario, a total of 44 receptor locations are predicted to experience an exceedance of the annual mean air quality objective for NO2. Of the four receptors that would no longer experience exceedance one is located at the very edge of the AQMA (D1_217: Coronation Road, Bristol, BS3 1RT), and three are located to the south of the AQMA (D1_24: Bridgwater Road, Bristol, BS13 7AQ, D2_4: Cater Road, Bristol, BS13 7SR, D2_36: Whitchurch Road, Bristol, BS13 7RS – see Table B2 in Appendix 10.2, Volume 3 for further information). However, 45 of the 48 exceedance locations from the do-minimum are predicted to experience an improvement in air quality in terms of annual mean NO2 with the SBL in place. The other three exceedance locations are expected to experience a negligible change in annual mean NO2 concentrations with the SBL in place.

10.8.11. All assessed receptor locations within the BCC AQMA, (with three exceptions of receptors D1_213, D1_214 and D1_215), are predicted to experience decreases (or negligible changes) in annual mean NO2 concentrations in 2016 with the SBL in place. Although annual mean NO2 concentrations are expected to increase at receptors D1_213, D1_214 and D1_215, no exceedance of the annual mean air quality objective is predicted at these particular locations under the 2016 do-something scenario. Outside of model domain 1, no exceedance of the annual mean air quality objective for NO2 is predicted under the 2016 do-something scenario (including under the more conservative sensitivity test).

10.8.12. The effect of the SBL in terms of annual mean PM10 concentrations is presented in Table 10.11. The top ten receptors (residential properties and schools) with the highest 2016 do-something concentrations are shown (Table B2 in Appendix 10.2, Volume 3 provides results for all modelled receptors). Maximum annual mean PM10 concentrations are predicted in model domain 1 under all three assessment scenarios.

10.8.13. There would be no exceedance of the AQS objective for PM10 at any of the receptors in both the do-minimum and do-something scenarios in 2016. Considering the IAQM criteria in Table 10.2, changes in concentration from do-minimum to do-something would be ‘imperceptible’. Referring to Table 10.3, the overall impact of the SBL for these receptors - and those outside of the top ten - is ‘negligible’. The SBL would therefore not have a significant effect on annual mean PM10 concentrations.

Table 10.11: Annual Mean PM10 Concentrations (µg/m3) at Receptors and Impacts


2016 DM

2016 DS

Change (DS-DM)

Impact Magnitude

Impact


357644 170659 18.9 17.4 17.3 -0.1 Imperceptible Negligible

D1_172: Bedminster Down Road, Bristol BS13 7AF



357972 170559 18.5 17.0 17.1 0.1 Imperceptible Negligible

SBL ES: 2.10


207

D1_252: Coronation Road, Bristol






D1_13000: Bower Ashton Terrace, Bristol, BS3 2LE


D1_18: Church Lane, Bedminster, Bristol, BS3 4NE




D1_5000: Mansfield Street, Bristol


Notes:


10.8.14. The effect of the SBL in terms of 24-hour mean PM10 is presented in Table 10.12. The top ten receptors (residential properties and schools) with the highest number of do-something exceedances of the 50 µg/m3 threshold are shown (Table B2 in Appendix 10.2, Volume 3, provides results for all modelled receptors).

10.8.15. The AQS objective for 24-hour mean concentrations would be met at all receptors in all cases. Considering the IAQM criteria in Table 10.2, changes in the number if exceedances from do-minimum to do-something would be ‘imperceptible’. Referring to Table 10.4, the overall impact of the SBL for these receptors - and those outside of the top ten - is ‘negligible’. The SBL would therefore not have a significant effect on 24-hour mean PM10 concentrations.

Table 10.12: Number of Exceedances of 24-hour Hour Mean PM10 Threshold of 50 µg/m3 at Receptors and Impacts


2016 DM

2016 DS

Change (DS-DM)

Impact Magnitude

Impact

D1_18: Church Lane, Bedminster, Bristol, BS3 4NE

358596 171392 2 1 1 <1 Imperceptible Negligible

D1_20: West Street, Bedminster, Bristol, BS3 3NN


D1_172: 168 Bedminster Down Road, Bristol, BS13 7AF






SBL ES: 2.10


208



D1_190: West Street, Bedminster, Bristol


D1_207: Winterstoke Road, Bristol, BS3 2NY


D1_210: Smyth Road, Bristol, BS3 2DP


D1_212: Bower Ashton Terrace, Bristol, BS3 2LE



10.8.16. The SBL scheme will bring about changes in road vehicle routing, particularly in the local area around the SBL. This will impact on vehicle emissions of CO2 and therefore carbon. Annual total carbon emissions have been calculated for affected road links in 2011 and do-minimum and do-something scenarios in 2016 and 2031; these are presented in Table 10.13. Affected road links were defined according to the methodology set out in the previous section.

Table 10.13: Impact on Road Transport Carbon Emissions

Scenario Total Emissions, Carbon tonnes/year

Total Emissions, Carbon Dioxide tonnes/year

Base Year (2011) 6,747 24,740

DM (2016) 6,961 25,523

DS (2016) 7,188 26,355

Change from DM (2016) 227 832 3.3%

Change from Base Year (2011) 440 1,615 6.5%

DM (2031) 7,710 28,270

DS (2031) 8,330 30,544

Change from DM (2031) 620 2,274 8.0%

Change from Base Year (2011) 1,583 5,804 23.5%

10.8.17. Annual emissions of carbon are predicted to increase with the SBL scheme in place, by approximately 230 tonnes in 2016 and 620 tonnes in 2031. Overall, with the scheme in place, annual CO2 emissions in 2031 are expected to be approximately 24% higher than estimated for the 2011 base year.

10.8.18. The increases in emissions can be attributed to the reassignment of vehicle journeys from routes that become less attractive with the SBL scheme, and increases in actual vehicle trips as the SBL scheme will make travel by road more viable.

10.8.19. In the wider context the impacts will be very small. According to DECC, total road transport CO2 emissions for the BCC and NSC combined area in 2010 were 1,028,000 tonnes (see Section 0). With reference to Table 10.13, the total estimated for the regional affected road network in the 2011 base year is 24,740 tonnes, which is approximately 2.4% of the DECC total for BCC and NSC. If total road traffic emissions are 3.3% higher in 2016 than they are in 2011 then total road

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transport CO2 emissions for the BCC and NSC combined area will be approximately 1,061,924 tonnes (assuming that DECC estimates for 2010 are the same in 2011). This means that the additional 832 tonnes of CO2 with the SBL scheme in 2016 represents an increase of 0.078% in total road transport CO2 emissions for the BCC and NSC area. By the 2031 design year total road transport emissions with the SBL scheme will be 0.194% higher for the BCC and NSC area than without the scheme. In the context of the even wider West of England Partnership area the impacts are extremely small.

10.9. Mitigation Measures

Construction Phase Mitigation

10.9.1. Mitigation measures will be required to ensure that the risk of dust from construction operations and sites resulting in a significant adverse effect is minimised. These measures will be in accordance with current industry best practice and will be included within the Construction Environmental Management Plan (CEMP). Typically the construction contractor would be required to:

Erect solid screens or barriers around the site boundary where there are adjacent residential

properties.

Only use cutting, grinding or sawing equipment fitted or in conjunction with suitable dust

suppression techniques such as water sprays or local extraction, e.g. suitable local exhaust

ventilation systems.

Damp down dusty materials and exposed surfaces during dry weather.

Ensure sand and other aggregates are stored in bunded areas and are not allowed to dry

out.

Use enclosed chutes, conveyors, and covered skips, where practicable.

Make sure that any stockpiles exist for the shortest possible time.

Avoid creating steep sided stockpiles or mounds or those that have sharp changes in shape.

Whenever possible keep stockpiles or mounds away from the site boundary, sensitive

receptors, watercourses and surface drains.

Wherever possible, enclose stockpiles or keep them securely sheeted.

Take into account the predominant wind direction when locating stockpiles to reduce the

likelihood of affecting sensitive receptors.

Take appropriate action to stabilise any long term stockpiles to prevent loss of material by

wind erosion.

Impose an appropriate onsite speed limit.

Ensure that all vehicles carrying dusty material should be securely covered before leaving

the site.

Regularly inspect and maintain all site access points and the public highway in the vicinity of

access points free from accumulations of mud and other debris.

Employ vehicle cleaning equipment to ensure that vehicles leaving the site do not track mud

onto the public highway.

Prohibit burning on site.

10.9.2. Daily site management of emission control measures will be undertaken, with visual inspections of activities and control measures carried out every day during dry conditions. Visual inspections will include recording of activities, controls, weather and ground conditions, and observations of surface dust deposits at and beyond the site boundary in the vicinity of receptors.

Operational Phase Mitigation

10.9.3. No significant adverse effects are expected to occur as a consequence of the SBL. No specific mitigation is therefore required.

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10.10. Residual Effects

Construction Phase Residual Effects

10.10.1. Negligible residual effects are expected to occur as a consequence of the SBL construction assuming that appropriate mitigation measures to prevent and control dust emissions are maintained by the construction contractor.

Operational Phase Residual Effects

10.10.2. No significant adverse residual effects are expected to occur as a consequence of the SBL after opening.

10.11. Consideration of Likely Cumulative Effects

10.11.1. To account for possible cumulative effects resulting from the operation of the SBL and the Ashton Vale to Temple Meads (AVTM) schemes, an additional model run was completed for the 2016 do-something scenario, which included traffic data associated with the AVTM. North Fringe Hengrove (NFH) traffic data is not yet available, so cannot be included. Potential air quality effects resulting from traffic emissions associated with other committed developments were already included in the 2016 do-something model run for the SBL.

Construction Phase Cumulative Effects

10.11.2. It has not been possible to consider cumulative effects for construction phase impacts since the likelihood of construction work for SBL coinciding with other nearby construction is unknown; however, provided any other independent construction works in the area also ensure appropriate emissions prevention and control measures, the cumulative effect should not be significant (i.e. will be negligible).

Operational Phase Cumulative Effects

10.11.3. For the standard model (i.e. not upper range sensitivity test) Table 10.14 presents the top ten receptors with the highest 2016 do-something with AVTM annual mean NO2 concentrations (Table B3 in Appendix 10.2, Volume 3, provides results for all modelled receptors). Operation of the AVTM in combination with the SBL is not expected to result in significant adverse air quality effects. No new exceedances are predicted with the AVTM in operation. Cumulative impacts are not expected to be materially different in either lower (standard) or upper (sensitivity test) cases to those predicted with just the SBL in operation.

10.11.4. The maximum difference in NO2 concentrations under the 2016 do-something scenario with the AVTM in place compared to that with the SBL only is -0.6 µg/m

3, which is less that 2% of the

annual mean air quality objective for NO2. As previously discussed, under the 2016 do-something scenario (with the SBL only) 29 receptor locations, which are all within model domain 1, are predicted to experience annual mean NO2 concentrations in exceedance of the AQS objective. With the AVTM in place this is still the case, but all but one of the 29 locations are actually expected to experience a marginal decrease or no difference (compared to with the SBL only) in annual mean NO2 concentrations with the AVTM operating concurrently with the SBL.

10.11.5. The maximum difference in annual mean PM10 concentrations under the 2016 do-something scenario with the AVTM in place compared to that with the SBL only is +/-0.1 µg/m

3, which is less

that 1% of the annual mean air quality objective for PM10. None of the assessed receptor locations are predicted to experience an exceedance of the annual mean air quality objective for PM10 either with the SBL in operation on its own, or in combination with the AVTM.

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Table 10.14: Changes in Annual Mean NO2 and PM10 Concentrations (µg/m3) with the AVTM

Receptor X Y NO2 PM10

2016 DS (SBL)

2016 DS (SBL & AVTM)

Difference (SBL & AVTM – SBL)

2016 DS (SBL)

2016 DS (SBL & AVTM)

Difference (SBL & AVTM – SBL)


357644 170659 60.1 60.1 0.0 17.3 17.3 0.0


357977 170531 59.6 59.6 0.0 17.0 17.0 0.0


357972 170559 59.1 59.0 -0.1 17.1 17.1 0.0


357943 170565 55.9 55.9 0.0 17.0 17.0 0.0

D1_12000: Bedminster Down Road, Bristol, BS13 7AB

357709 170625 56.2 55.6 -0.6 16.8 16.8 0.0

D1_257: Parson Street Primary School, Parson Street, Bristol

357994 170508 51.8 51.8 0.0 16.6 16.6 0.0

D1_7000: Temple Street, Bedminster, Bristol, BS3 3NF

357843 170683 51.8 51.6 -0.2 16.8 16.8 0.0


357608 170480 51.4 51.1 -0.3 16.8 16.8 0.0


358031 170600 51.1 51.0 -0.1 16.1 16.1 0.0


357708 170659 51.0 50.7 -0.3 16.6 16.6 0.0

Notes:


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10.12. Summary and Conclusions

10.12.1.1. An air quality assessment has been undertaken with consideration of impacts that were identified as being potentially significant in the EIA Scoping Report, including: impacts from dust and particulates during construction of the SBL scheme; and operational air quality impacts due to changes in traffic conditions with the scheme.

Significant Construction Phase Effects

10.12.2. With appropriate mitigation to prevent and control dust emissions, there would be no significant construction phase effects with the SBL.

Significant Operational Phase Effects

10.12.3. There would be no significant operational phase effects on local air quality with the SBL (with or without AVTM). The scheme is likely to have beneficial effects at locations with relevant public exposure within the Bristol AQMA, particularly in the Bedminster area around Parson Street station where traffic conditions will be eased. Although locations adjacent to the SBL will experience increased pollutant concentrations, these are likely to be substantially lower than the relevant air quality criteria.

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10.13. References and Sources

10.13.1. Ref. AQ1: The Air Quality Standards Regulations 2010: http://www.legislation.gov.uk/uksi/2010/1001/contents/made

10.13.2. Ref. AQ2: The Air Quality (England) Regulations 2000: http://www.legislation.gov.uk/uksi/2000/928/contents/made

10.13.3. Ref. AQ3: The Air Quality (England) (Amendment) Regulations 2002: http://www.legislation.gov.uk/uksi/2002/3043/contents/made

10.13.4. Ref. AQ4: Defra. UK Air Quality Strategy: http://www.defra.gov.uk/environment/quality/air/air-quality/approach/

10.13.5. Ref. AQ5: Environmental Protection Act 1990: http://www.legislation.gov.uk/ukpga/1990/43/contents

10.13.6. Ref. AQ6: Department for Communities and Local Government (March 2012). National Planning Policy Framework: https://www.gov.uk/government/policies/making-the-planning-system-work-more-efficiently-and-effectively

10.13.7. Ref. AQ7: Environment Act 1995: http://www.legislation.gov.uk/ukpga/1995/25/contents

10.13.8. Ref. AQ8: West of England Partnership. Joint Local Transport Plan 3: http://www.travelplus.org.uk/our-vision/joint-local-transport-plan-3

10.13.9. Ref. AQ9: Highways Agency Design Manual for Roads and Bridges: http://www.dft.gov.uk/ha/standards/dmrb/vol11/section3/ha20707.pdf

10.13.10. Ref. AQ10: Defra Local Air Quality Management Technical Guidance (LAQM.TG(09): https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/69334/pb13081-tech-guidance-laqm-tg-09-090218.pdf

10.13.11. Ref. AQ11: EPUK. Development Control: Planning For Air Quality (2010 Update): http://www.iaqm.co.uk/guidance.html

10.13.12. Ref. AQ12: Greater London Authority. The control of dust and emissions from construction and demolition, Best Practice Guidance: http://www.london.gov.uk/thelondonplan/guides/bpg/bpg_04.jsp

10.13.13. Ref. AQ13: Defra. UK-AIR information resource: http://uk-air.defra.gov.uk/

10.13.14. Ref. AQ14: Natural England: http://www.naturalengland.org.uk/publications/data/default.aspx

10.13.15. Ref. AQ15: Atkins. South Bristol Link – Environmental Scoping Report. March 2012

10.13.16. Ref. AQ16: Discussions between Atkins (Andy Talbot) and BCC (Andrew Edwards) on 04/04/2013, 08/04/2013 and 26/04/2013

10.13.17. Ref. AQ17: Atkins. South Bristol Link HAM LMVR, North Somerset Council. April 2013

10.13.18. Ref. AQ18: Defra, EFT version 5.2c: http://laqm.defra.gov.uk/review-and-assessment/tools/emissions.html#eft

http://www.legislation.gov.uk/uksi/2010/1001/contents/made



http://www.defra.gov.uk/environment/quality/air/air-quality/approach/

http://www.legislation.gov.uk/ukpga/1990/43/contents

https://www.gov.uk/government/policies/making-the-planning-system-work-more-efficiently-and-effectively

https://www.gov.uk/government/policies/making-the-planning-system-work-more-efficiently-and-effectively

http://www.legislation.gov.uk/ukpga/1995/25/contents

http://www.travelplus.org.uk/our-vision/joint-local-transport-plan-3

http://www.dft.gov.uk/ha/standards/dmrb/vol11/section3/ha20707.pdf

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/69334/pb13081-tech-guidance-laqm-tg-09-090218.pdf

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/69334/pb13081-tech-guidance-laqm-tg-09-090218.pdf

http://www.iaqm.co.uk/guidance.html

http://www.london.gov.uk/thelondonplan/guides/bpg/bpg_04.jsp

http://uk-air.defra.gov.uk/

http://www.naturalengland.org.uk/publications/data/default.aspx

http://laqm.defra.gov.uk/review-and-assessment/tools/emissions.html#eft

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10.13.19. Ref. AQ19: Report for Defra. Trends in NOx and NO2 emissions and ambient measurements in the UK (2011): http://uk-air.defra.gov.uk/library/reports?report_id=645

10.13.20. Ref. AQ20: Bristol City Council LAQM Updating and Screening Assessment (2012):http://www.bristol.gov.uk/sites/default/files/documents/environment/air_quality/Bristol%20City%20Council_%20USA_2012v1sml.pdf

http://uk-air.defra.gov.uk/library/reports?report_id=645

http://www.bristol.gov.uk/sites/default/files/documents/environment/air_quality/Bristol%20City%20Council_%20USA_2012v1sml.pdf

http://www.bristol.gov.uk/sites/default/files/documents/environment/air_quality/Bristol%20City%20Council_%20USA_2012v1sml.pdf

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