Air Quality Report by East Hampshire District Council

Air Quality Assessment: Whitehill Bordon Eco-town Habitats Regulations Assessment November 2011

Whitehill Bordon Eco-town Habitats Regulations Air Quality Assessment

Document Control

Client

Principal Contact

UE Associates

Job Number

J1184

Report Prepared By:

Dr Ben Marner and Laurence Caird

Nick Pincombe

Document Status and Review Schedule Report No. 1184/3/F4

Date th

7 November2011

Status Final Report

Reviewed by Stephen Moorcroft (Director)

This report has been prepared by Air Quality Consultants Ltd on behalf of the Client, taking into account the agreed scope of works. Unless otherwise agreed, this document and all other Intellectual Property Rights remain the property of Air Quality Consultants Ltd. In preparing this report, Air Quality Consultants Ltd has exercised all reasonable skill and care, taking into account the objectives and the agreed scope of works. Air Quality Consultants Ltd does not accept any liability in negligence for any matters arising outside of the agreed scope of works. The Company operates a formal Quality Management System, which is certified to ISO 9001:2008. When issued in electronic format, Air Quality Consultants Ltd does not accept any responsibility for any unauthorised changes made by others. When printed by Air Quality Consultants Ltd, this report will be on Evolve Office, 100% Recycled paper.

Air Quality Consultants Ltd 23 Coldharbour Road, Bristol BS6 7JT Tel: 0117 974 1086 12 Airedale Road, London SW12 8SF Tel: 0208 673 4313 aqc@aqconsultants.co.uk Registered Office: 12 St Oswalds Road, Bristol, BS6 7HT Companies House Registration No: 2814570

Whitehill Bordon Eco-town Habitats Regulations Air Quality Assessment

Contents

Introduction ................................................................................................................... 2

Policy Context and Assessment Criteria........................................................................ 5

Methodology ............................................................................................................... 11

Site Description and Baseline Conditions .................................................................... 17

Impact Assessment ..................................................................................................... 21

Mitigation .................................................................................................................... 30

Summary and Conclusions ......................................................................................... 31

References.................................................................................................................. 32

Glossary...................................................................................................................... 34

A1 Appendix 1 â&#x20AC;&#x201C; Professional Experience ........................................................................ 35 A2 Appendix 2 â&#x20AC;&#x201C; Model Verification .................................................................................. 36

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Introduction

1.1

Air Quality Consultants Ltd has been commissioned to assess the air quality impacts of the Whitehill Bordon Eco-town development on nearby European-designated ecological sites (“European sites”)1. The assessment considers the potential impacts associated with road traffic and with energy generation, and focuses solely on ecological impacts. Air quality impacts on human health are not considered. www.whitehillbordon.com.

A description of the Eco-town proposals is provided at

Figure 1 shows the study area for this assessment and identifies the

European sites considered. 1.2

A range of transport model options have been considered in this study, based on traffic impacts predicted by MVA and Amey as part of the Eco-town project: •

2026 Sc4: transport model “Scenario 4”: 2026 Option 2 (5,300 dwellings), 50% car mode share, 50% trip containment, A325 ‘traffic management’;

•

2026 Sc13: transport model “Scenario 13”: 2026 Option 1 (4,000 dwellings), 75% car mode share, 30% trip containment, A325 ‘do nothing’;

•

2026 Sc3: transport model “Scenario 3”: 2026 Option 1 (4,000 dwellings), 50% car mode share, 50% trip containment, A325 ‘traffic management; and

•

2026 Sc17: transport model “Scenario 17”: 2026 Option 1 (4,000 dwellings), 75% car mode share, 30% trip containment, A325 ‘public transport only’.

These scenarios have been selected for the assessment as they represent the worst-case (maximum traffic generation) of all of the scenarios considered by Amey for the project, with the exception of Scenario 3, which represents the closest match to the June 2010 Draft Masterplan. Each scenario has been assessed against transport model “Scenario 1”, which represents conditions in the future without the Eco-town development (2026 Baseline). The assessment of traffic impacts has focused on the year 2026, which represents the anticipated completion year for the scheme. 1.3

In addition, a range of energy feasibility options have been considered, based on the Whitehill Bordon Energy Feasibility Study prepared by LDA Design (LDA, 2011). These are: •

energy feasibility “Option 1”2: Central CHP plant burning solid wood;

•

energy feasibility “Option 2”: Central CHP plant burning biogas produced by anaerobic digestion;

European sites are defined here as Special Areas of Conservation (SACs), Special Protection Areas (SPAs), and sites designated under the Ramsar convention. In this report, “Scenario” refers to traffic scenarios and “Option” refers to energy options.

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•

energy feasibility “Option 3”: Central CHP with gasification plant;

•

energy feasibility “Option 4”: Central CHP with decentralised biomass boilers serving the rest of the town;

•

energy feasibility “Option 5”: Decentralised boilers burning solid wood;

•

energy feasibility “Option 6”: Decentralised boilers burning biogas produced by gasification; and

•

energy feasibility “Option 7”: Baseline with future development (i.e. typical gas condensing boilers throughout).

1.4

The principal pollutant of concern associated with traffic emissions that might affect sensitive habitats is nitrogen oxides (NOx).

Road traffic emissions may increase the ambient NOx

concentrations to which vegetation is exposed.

NOx emissions may also, following chemical

conversion in the air to form nitrogen dioxide, deposit nitrogen (mainly via uptake through the stomata). This nitrogen deposition may affect the habitats by causing nutrient enrichment and also by acidifying the soils. 1.5

The principal pollutant of concern associated with each of the energy generation options is also NOx. Some of the energy options would also emit small amounts of sulphur oxides; the amount of sulphur emitted is dependent on the sulphur content of the fuel burnt, but most commercial sources of wood biomass used in the UK have a very low sulphur content. It is not practical to predict the sulphur content of the fuels that would be used in 2026, but professional experience suggests that the impact of principal concern is relate to emissions of NOx. The assessment has thus focused on NOx and nitrogen deposition. Potential impacts related to emissions of sulphur oxides have been scoped out.

1.6

The traffic flows considered do not include the additional vehicles required to service each of the energy options. The number of delivery vehicles needed for each option would be very small compared with the traffic generated by the Eco-town proposals, and any impacts have been scoped out.

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Figure 1: Study Area and European Sites Considered

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Policy Context and Assessment Criteria Air Quality Strategy

A1.1

The Air Quality Strategy (Defra, 2007) provides the policy framework for air quality management and assessment in the UK. It provides air quality standards and objectives for key air pollutants, which are designed to protect human health and the environment. It also sets out how the different sectors: industry, transport and local government, can contribute to achieving the air quality objectives.

Clean Air Act 1993 2.1

Small combustion plant of less than 20 MW net rated thermal input are controlled under the Clean Air Act 1993. This requires the local authority to approve the chimney height.

Policy for the Protection of Sensitive Ecosystems 2.2

European Council Directive 92/43/EEC on the Conservation of Natural Habitats and of Wild Fauna and Flora (the “Habitats Directive”) requires member states to introduce a range of measures for the protection habitats and species. The Conservation of Habitats and Species Regulations (2010) (Stationery Office, 2010), transposes the Directive into legislation in England and Wales. The Regulations require the Secretary of State to provide the European Commission with a list of sites which are important for the habitats or species listed in the Directive. The Commission then designates worthy sites as Special Areas of Conservation (SACs). The Regulations also require the compilation and maintenance of a register of European sites, to include SACs and Special Protection Areas (SPAs), with the latter classified under the Council Directive 79/409/EEC on the Conservation of Wild Birds. These sites form a network termed “Natura 2000”.

2.3

The Regulations primarily provide measures for the protection of European sites and European Protected Species, but also require local planning authorities to encourage the management of other features that are of major importance for wild flora and fauna.

2.4

In addition to SACs and SPAs, some internationally important UK sites are designated under the Ramsar Convention.

Originally intended to protect waterfowl habitats, the Convention has

broadened its scope to cover all aspects of wetland conservation. 2.5

The Habitats Directive (as implemented by the Regulations) requires the competent authority, in this case the local planning authority, to firstly evaluate whether the proposed development is likely to give rise to a significant effect on the European site. Where this is the case, it has to carry out an ‘appropriate assessment’ in order to determine whether the development will adversely affect the integrity of the site.

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2.6

Sites of national importance may be designated as Sites of Special Scientific Interest (SSSIs). Originally notified under the National Parks and Access to the Countryside Act 1949, SSSIs have been renotified under the Wildlife and Countryside Act 1981. Improved provisions for the protection and management of SSSIs (in England and Wales) were introduced by the Countryside and Rights of Way (CROW) Act 2000. If a development is “likely to damage” a SSSI, the CROW act requires that a relevant conservation body (i.e. Natural England) is consulted. The CROW act also provides protection for local nature conservation sites, which can be particularly important in providing ‘stepping stones’ or ‘buffers’ to SSSIs and European sites. In addition, the Environment Act (1995) and the Natural Environment and Rural Communities Act (2006) both require the conservation of biodiversity

2.7

National planning policy on biodiversity and conservation is set out in Planning Policy Statement 9 (PPS9) (ODPM, 2005). This explains that the aim of planning decisions should be to prevent harm to biodiversity.

It goes on to clarify that if significant harm cannot be prevented, adequately

mitigated against, or compensated for, then planning permission should be refused. 2.8

PPS9 explains that the most important sites for biodiversity are those identified through international conventions and European Directives; which enjoy statutory protection through the Habitats Regulations. PPS9 also notes that SSSIs should be given a high degree of protection under the planning system.

It also highlights the importance of networks of natural habitats,

explaining that local authorities should aim to avoid fragmentation and isolation of natural habitats.

Assessment Criteria 2.9

Objectives for the protection of vegetation and ecosystems have been set by the UK Government and were to have been achieved by 2000.

The objective relevant to this assessment is

summarised in Table 1 and is the same as the EU limit value. The objective only strictly applies a) more than 20 km from an agglomeration (about 250,000 people), and b) more than 5 km from Part A industrial sources, motorways and built up areas of more than 5,000 people. However, Natural England has adopted a more precautionary approach and applies the objective to all European sites. Table 1:

Relevant Vegetation and Ecosystem Objective

Pollutant Nitrogen Oxides (expressed as NO2) 2.10

Time Period

Objective

Annual mean

30 µg/m3

Critical loads for nitrogen deposition onto sensitive ecosystems have been specified by United Nations Economic Commission for Europe (UNECE). They are defined as the amount of pollutant deposited to a given area over a year, below which significant harmful effects on sensitive elements of the environment do not occur, according to present knowledge.

It must be

emphasised that exceedence of the critical load does not provide a quantitative estimate of

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damage to an ecosystem, but only the potential for damage to occur.

The critical loads for the

ecosystems under consideration in this assessment, as defined in the Air Pollution Information System (APIS, 2011), are provided in Table 2. APIS does not provide site-relevant critical loads for Ramsar sites, but the SAC-specific and SPA-specific critical loads are considered appropriate to protect the Ramsar site3. The Ramsar designation is thus not considered further in this report. For each European site there is a range of applicable loads. In order to simplify the assessment, while retaining a robust approach, the lowest (i.e. most stringent) critical load for each habitat has been selected. The assessment criteria used in the study are set out in Table 3.

The only Ramsar site in the study area is also designated both as a SAC and as a SPA. Using the critical loads specific to SACs and SPAs, none of the potentially significant impacts discussed in this report are within the Ramsar site.

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Table 2:

Critical Loads for the Habitats Considered in this Study a Critical Load

Site

East Hampshire Hangers SAC

Shortheath Common SAC Thursley, Ash, Pirbright and Chobham SAC

Feature of Interest

Wealden Heaths SPA Phase 2

max

min

max

Semi-natural dry grasslands and scrubland facies: on calcareous substrates (including orchid sites)

0.86

4.01

Asperulo-Fagetum beech forests

0.14

11.44

Tilio-Acerion forests of slopes, screes and ravines

0.14

11.44

Taxus baccata woods of the British Isles

0.14

11.44

Gentianella anglica

0.86

4.01

European dry heaths

0.89

1.46

Transition mires and quaking bogs

0.32

0.67

Bog woodland

0.32

0.67

Northern Atlantic wet heaths with Erica tetralix

0.64

2.40

European dry heaths

0.64

2.40

Depressions on peat substrates of the Rhynchosporion

0.32

0.68

Coniferous Woodland

0.14

3.48

Dwarf Shrub Heath

0.64

2.40

Coniferous Woodland

0.14

3.48

Dwarf Shrub Heath

0.64

2.40

Sylvia undata

Dwarf Shrub Heath

0.64

2.40

Caprimulgus europaeus

Coniferous Woodland

0.14

3.36

Dwarf Shrub Heath

0.71

2.43

Coniferous Woodland

0.14

3.36

Dwarf Shrub Heath

0.71

2.43

Dwarf Shrub Heath

0.71

2.43

Northern Atlantic wet heaths with Erica tetralix

1.04

1.37

Natural dystrophic lakes and ponds

n/a

European dry heaths

1.04

1.37

Transition mires and quaking bogs

0.32

0.70

Depressions on peat substrates of the Rhynchosporion

0.32

0.70

Lullula arborea

Lullula arborea Sylvia undata

Woolmer Forest SAC

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Acid N (kg/ha/yr)

min

Caprimulgus europaeus Wealden Heaths SPA Phase 1

Nutrient N (kg/ha/yr)

Critical loads are presented as ranges.

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Table 3:

Assessment Criteria Used

Annual Mean NOx

Nutrient N (kg/ha/yr)

Acid N (kg/ha/yr)

East Hampshire Hangers SAC

0.14

Shortheath Common SAC

0.32

Wealden Heaths SPA Phase 1

0.14

Wealden Heaths SPA Phase 2

0.14

Woolmer Forest SAC

0.32

Site

Thursley, Ash, Pirbright and Chobham SAC 30

Descriptors for Air Quality Impacts and Assessment of Significance 2.11

There is no official guidance in the UK on how to describe the nature of air quality impacts nor to assess their significance.

The approach provided by the Environment Agency for assessing

whether industrial emissions may give rise to significant impacts has thus been used, along with an approach developed by the Institute of Air Quality Management4 (IAQM, 2009) which has been incorporated in Environmental Protection UKâ&#x20AC;&#x2122;s guidance document on planning and air quality (EPUK, 2010). Environment Agency Assessment Criteria 2.12

The Environment Agency has considered potential impacts from industrial and boiler emissions in its H1 guidance (Environment Agency, 2010a).

This explains that regardless of the baseline

environmental conditions, a process can be considered as insignificant if: â&#x20AC;˘

the long-term (annual mean) process contribution is <1% of the long-term environmental standard.

2.13

It should be recognised that this criterion determines when an impact can be screened out as insignificant. It does not imply that impacts will necessarily be significant above this criterion, merely that there is a potential for significant impacts to occur that should be considered using a detailed assessment methodology, such as a detailed dispersion modelling study (as has been carried out for this project in any event).

2.14

This criterion is also used in guidance issued by the Environment Agency and Joint Nature Conservation Committee (JNCC) on applying the Habitats Regulations in relation to air quality impacts (Environment Agency, 2005). This states that:

The IAQM is the professional body for air quality practitioners in the UK.

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"Where the concentration within the emission footprint in any part of the European Site is less than 1% of the relevant benchmark, the emission is unlikely to have a significant effect irrespective of the background levels." 2.15

The approach taken in this assessment has been to apply a detailed dispersion modelling study in the first instance, and to apply the Environment Agency screening criteria to the model outputs. Where predicted concentrations and deposition rates are shown to be below these screening criteria, the impacts are judged to be insignificant regardless of the ambient background levels. Only if this initial screening shows the potential for significant impacts, is account taken of the total concentrations and fluxes.

Institute of Air Quality Management Impact Descriptors 2.16

The IAQM guidance is that the assessment of significance should be based on professional judgement, with the overall air quality impact of the scheme described as either, ‘insignificant’, ‘minor’, ‘moderate’ or ‘major’. A summary of the professional experience of staff contributing to this assessment is provided in Appendix A1.

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Methodology Existing Conditions

3.1

Existing air quality conditions within the study area have been defined using a number of approaches. Background NOx and nitrogen dioxide concentrations across the study area have been defined using the national pollution maps published by Defra (Defra, 2011). These cover the whole country on a 1x1 km grid. Separate maps have been published for each year up to 2020. The maps for 2020 have been used to represent conditions in 2026 which is a conservative approach. The 1x1 km grid concentrations have been interpolated across the study area in order to derive “smoothed” receptor-specific concentrations.

Background deposition fluxes to each

European site have been obtained from APIS (2011); these represent average fluxes across each site. APIS (2011) provides these data for 2005 and 2020 but does not provide projections for subsequent years. The assumption has been made that the critical loads which are exceeded in 2020 will also be exceeded in 2026. 3.2

The meteorological data used for dispersion modelling were for the most recent complete year (2010) of hourly data from the Meteorological Office monitoring station at Farnborough, which is considered suitable for this area.

Receptor Locations 3.3

Predictions have been made for a grid of 22,000 receptors spread across the study area. Outside of the European sites, a relatively coarse (1 km x 1 km) Cartesian grid of receptors was used. Within each European site, the grid resolution was increased to 200 m x 200 m. These Cartesian grids were supplemented with an “intelligent” grid of receptors with eight rows of receptors spaced between 6 m and 160 m from the centre of each road within and near to each European site, as well as a large number of additional receptors positioned at the edges of those sites nearest to the town and nearest to the proposed energy centre. The result of this approach is that sufficient receptors have been included to allow the worst-case impacts of the proposals to be identified, while also allowing contour isopleths to be drawn across each of the European sites.

Road Traffic Impacts 3.4

Predictions of ambient NOx concentrations have been made for a base year (2010), and the proposed year of scheme completion (2026).

For 2026, predictions have been made both

assuming that the Eco-town development does not go ahead (2026 Base), as well for each of the traffic model scenarios outlined in Section 1. 3.5

Predictions have been carried out using the ADMS-Roads dispersion model (v3), which uses Defra’s latest emission factors as published in the Emission Factor Toolkit (Version 4.2.2) (Defra,

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2011). These emission projections on go as far as 2025, so 2025-specific emissions have been applied to 2026. 3.6

Amey provided the traffic model outputs for key junctions associated with each scenario. These report the total peak hour flow, as well as a flow of “goods”. MVA subsequently provided a set of factors to derive 12-hour flows from the peak-hour data; as well as a set of factors to predict the number of Heavy Goods Vehicles (HGVs) within the “goods” dataset. It was assumed that these HGVs flows represent the Heavy Duty Vehicles (HDVs) flows5 required by ADMS-Roads. 24-hour flows were calculated from the 12-hour predictions using the national average diurnal flow profile published by the DfT (2011). Traffic speeds have been estimated from local speed restrictions and take account of the proximity to a junction.

The traffic data used in this assessment are

summarised in Table 4 and Figure 2. 3.7

The ADMS-Roads model has been verified against local measurements made within Bordon as explained in Appendix A2.

Figure 2:

Summary of Traffic Data Included in Study (Blue lines show roads included, yellow labels relate to flows in Table 4, and green areas show the European sites)

The terms HDV refers to all vehicles >3.5 tonnes and thus includes buses. The term HGV often excludes buses.

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Table 4:

Traffic Data Used in Assessment (24hr - Annual Average Daily Traffic)

2010 Rd

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2026 Base

2026 Sc4

2026 Sc13

2026 Sc17

2026 Sc3

V/da

8,877

1.3%

10,412

2.3%

9,968

1.7%

10,199

1.8%

10,368

1.8%

9,811

1.6%

2.1%

178

9.3%

217

9.1%

224

9.1%

187

9.3%

219

9.1%

5,927

1.8%

6,406

1.9%

6,291

2.2%

6,657

1.9%

6,530

2.0%

6,253

2.1%

9,147

1.4%

9,688

1.4%

10,314

1.6%

11,870

1.4%

11,816

1.4%

10,045

1.6%

6,380

1.1%

7,185

1.4%

7,432

1.6%

7,554

1.6%

7,552

1.6%

7,389

1.6%

8,398

1.4%

9,934

2.4%

9,440

1.8%

9,696

1.8%

9,779

1.8%

9,300

1.6%

8,757

1.4%

10,301

2.4%

10,037

2.1%

10,306

2.1%

10,413

2.1%

9,846

1.9%

234

1.8%

269

2.9%

1,139

5.5%

1,048

5.2%

910

5.0%

976

5.7%

8,131

1.5%

8,635

1.8%

9,805

2.2%

11,838

1.7%

11,985

1.7%

9,513

2.1%

3,585

1.4%

3,677

1.2%

5,152

1.3%

6,679

0.9%

8,026

1.1%

4,846

1.2%

6,204

1.9%

6,711

2.3%

7,004

4.3%

7,614

3.7%

6,972

3.7%

6,901

4.1%

15,956

1.6%

16,308

2.4%

22,249

6.1%

24,208

5.0%

22,557

5.2%

21,444

5.8%

3,454

1.9%

3,834

2.5%

3,721

2.6%

3,887

2.7%

4,077

2.7%

3,711

2.6%

703

1.1%

785

1.0%

928

2.5%

892

2.2%

1,000

2.6%

901

2.6%

12,901

1.9%

14,762

2.9%

18,124

4.5%

18,863

4.0%

18,703

4.0%

17,711

4.5%

3,039

1.6%

3,449

2.5%

4,402

3.3%

5,552

2.5%

5,620

2.5%

4,133

3.3%

8,026

1.7%

8,942

2.0%

8,943

2.0%

8,947

2.0%

8,949

2.0%

8,943

2.0%

2,377

0.8%

1,473

0.4%

1,559

0.9%

1,576

0.8%

1,536

0.7%

1,540

0.8%

1,374

1.4%

1,569

1.6%

1,569

1.6%

1,569

1.6%

1,569

1.6%

1,569

1.6%

2,862

0.8%

2,003

0.5%

2,089

0.8%

2,107

0.8%

2,064

0.7%

2,071

0.8%

1,472

1.2%

1,674

1.4%

1,674

1.4%

1,674

1.4%

1,674

1.4%

1,674

1.4%

5,716

1.6%

7,068

2.0%

7,155

2.0%

7,195

2.1%

7,228

2.2%

7,131

2.0%

2.1%

229

11.9%

336

13.5%

324

13.1%

305

13.8%

331

13.4%

10,769

2.0%

12,586

3.3%

15,104

4.5%

15,753

4.4%

15,350

4.1%

14,746

4.5%

20,204 10.0%

23,844 10.0%

24,125

10.0% 24,436

23,718 10.0%

10.0% 23,800 10.0%

Vehicles per day (24 hr Annual Average Daily Traffic).

% Heavy Duty Vehicle. For Road number 29 (the A3), the percentage HDV was not provided in the traffic model and a nominal value of 10% has been assumed.

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Impacts of the Energy Options 3.8

Ambient NOx concentrations arising from each of the seven energy options outlined in Section 1 have been predicted using the ADMS-4 dispersion model.

Emission Rates 3.9

Emission rates of NOx for each energy option were obtained from published sources. Emission rates for biomass and natural gas (Options 1, 4, 5 and 7) were taken from the European Environment Agency (EEA) air pollutant emission inventory guidebook (EMEP/EEA, 2009). Emission rates for combustion of biogas from anaerobic digestion (Option 2) were taken from research conducted by the Danish Gas Technology Centre (DGTC, 2004). Emission rates for combustion of biogas from gasification (Options 3 and 6) were taken from research carried out by Evergreen State College, Washington (USA) (ESC, 2011). The emission rates are set out in Table 5. The total predicted annual thermal and electrical outputs for each option were provided by LDA Design (2011).

3.10

It should be recognised that while the emission rates have been derived from the best available information currently available, they are based on current technologies and may not accurately represent actual emissions in 20266.

Furthermore, because of the range of technologies

considered, some of the emission factors are likely to be more reliable than others; data from the European Environment Agency can, for example, be considered more robust than those derived from a single research study.

Release Locations 3.11

The centralised CHP plant (Options 1-4) has been modelled at the site of the Louisville Barracks7 (grid ref x=478585, y=136600), which was identified as the preferred site in the energy options appraisal provided by LDA Design. In addition to the centralised plant location, the decentralised plant (Options 4-7) have been modelled as a single area source which covers the entire Whitehill Bordon Eco-town8.

Release Parameters 3.12

The proposed centralised CHP options have been selected based on size and type, with little detailed investigation into specific makes and models of CHP plant. As such, various model input parameters have necessarily been assumed based on professional experience of assessing

7 8

In practice, the emissions used are most likely to over-state the emissions in 2026 since they do not take account of the technological improvements likely to occur in the future. The emissions data thus represent conservative estimates. The actual location assumed was at grid ref x=478585, y=136600; which is indicative of the centre of the Barracks. i.e. including both the existing and proposed urban areas.

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similar plant elsewhere. Table 6 shows a summary of the model input parameters that have been used. Table 5:

Option

NOx Emissions Associated with Each Energy Option

Description

Thermal Output (MWh/yr)

Annual Electrical Output (MWh/yr)

Total Output (MWh/yr)

NOx Emission Rate (g/GJ)

Total NOx Emissions (te/yr)a

Centralised WoodFired CHP

16,000

4,000

20,000

150

10.8

Centralised BiogasFired CHP from anaerobic digestion

16,000

12,000

28,000

169

17.0

Centralised CHP with gasification

16,000

7,700

23,700

7.7

Centralised CHP with local biomass

62,205

4,000

46,205

150

24.9

Decentralised wood boilers

67,000

150

36.2

Decentralised biogas boilers

67,000

21.7

Traditional gas condensing boilers

67,000

16.9

Entered into the model as annual average emissions in g/s.

It has been assumed that Option 4 will be centralised biomass CHP with decentralised biomass boilers

Table 6

Centralised CHP Plant Model Input Parameters Centralised Biomass

Centralised Biogas from Anaerobic Digestion

Centralised Biogas from Gasification

(Options 1 & 4)

(Option 2)

(Option 3)

Stack Height (m)

Stack Diameter (m)

Exit Velocity (m/s)

Exit Temperature (째C)

100

Parameter

Chemical Conversions 3.13

Emissions of NOx from both road traffic and boiler plant are predominantly in the form of nitric oxide (NO) which is converted to nitrogen dioxide in the atmosphere via a series of chemical reactions, principally with ozone.

For road traffic, the contributions of local roads to NOx

concentrations have been combined with the mapped annual mean background nitrogen dioxide

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concentration within the “NOx to NO2 calculator” published by Defra (2011).

For the energy

options, the approach set out by the Environment Agency has been followed (Environment Agency, 2010b) i.e. assuming that 70% of annual mean NOx is in the form of nitrogen dioxide.

Deposition Calculations 3.14

Nitrogen deposition fluxes have been calculated from the predicted ambient nitrogen dioxide concentrations using the deposition velocity set out in Table 7. This is applied by multiplying the nitrogen dioxide concentration (µg/m3) by the velocity (m/s) to predict a deposition flux (µg/m2/s). Subsequent calculations required to present the data as kg/ha/yr and keq/ha/yr follow basic chemical and mathematical rules. Table 7: Deposition Velocity Used in This Assessment

3.15

Pollutant

Deposition Velocity (m/s)

Reference

Nitrogen Dioxide

0.001 m/s

Metcalfe (2001), Hall et al., (2008), Highways Agency, (2007)

Wet deposition has been discounted. Wet deposition of nitrogen dioxide within close proximity to emission sources is restricted to wash-out, or below-cloud scavenging. For this to occur, rain droplets must come into contact with the gas molecules before they hit the ground. Falling raindrops displace the air around them, effectively pushing gases away. The low solubility of nitrogen dioxide means that any scavenging of this gas will be a negligible factor.

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Site Description and Baseline Conditions

4.1

The proposed Eco-town and surrounding European sites lie south of the A31 and, mostly, north of the A3. The A325 runs through the centre of the propsed Eco-town and across the study area. There are no significant sources of industrial emissions in the area and the principal source of NOx emissions is road traffic.

Baseline NOx Concentrations 4.2

Table 8 summarises the background NOx concentrations across the study area, showing the maximum mapped background concentration9 within each site. All of the mapped background concentrations are well below the objective in 2010 and are predicted to be even lower in 2026. Table 8:

Maximum Mapped Background Annual Mean NOx Concentration (µg/m3) Within Each Site a East Hants Hangers SAC

Woolmer Forest SAC

Shortheath Common SAC

Thursley, Ash, … SAC

Wealden Heaths SPA P 1

Wealden Heaths SPA P 2

2010

11.4

15.5

11.3

21.2

15.4

15.5

2026 Baseline

7.9

9.4

8.0

14.1

9.9

10.5

Scenario

Objective 4.3

The ADMS-Roads model has been run to predict annual mean NOx concentrations across each European site in 2010 and 2026, without the proposed scheme (2026 Base)9. The results are summarised in Table 9 which shows the maximum predicted concentration in each site. Concentrations in 2010 were predicted to exceed the critical load at the kerbside within each of the European sites. Within the Wealden Heaths (Phase 2) SPA, annual mean NOx concentrations at the kerbside are predicted to be 214 µg/m3; with this maximum occurring adjacent to the A3 at Hindhead Common. It should be recognised that these are the maximum concentrations at the kerbside and that levels reduce very rapidly on moving futher back from the carriageway. The areas of exceedence typically extend no more than about 50 m from roads in 2010, with concentrations approaching background levels within 200 m from roads. By 2026, Defra expects a range of measures introduced at national and international levels to have reduced NOx concentrations below their current levels. In 2026, the objective is predicted to be exceeded only

Background concentrations represent conditions well away from any roads or other local emission sources. Concentrations near to roads, as predicted using the ADMS-Roads model, are much higher than the local background.

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at worst-case locations in Woolmer Forest SAC; Thursley Ash, Pirbright and Chobham SAC; Wealden Heaths SPA Phase 110; and Wealden Heaths SPA Phase 2. Contour isopleths have been plotted to show the area over which the 30 µg/m3 objective is

4.4

predicted to be exceeded in 2010, and in 2026 without the Eco-town proposals. These have been used to calculate the total exceedence area within each European site (Table 10). In 2010, the objective is predicted to be exceeded across 88 ha of Wealden Heaths SPA (Phase 2), but only across <0.1 ha of Shortheath Common SAC. By 2026, the extent of the exceedence areas is predicted to have reduced substantially, such that there are no predicted exceedences within the East Hants Hangers or Shortheath Common SACs, and the predicted exceedence areas within the other sites makes up only a small fraction of the total site. For example, by 2026 the predicted exceedence area within the Wealden Heaths SPA (Phase 2) represents only 0.3% of the total area. Table 9:

Maximum Predicted Annual Mean NOx Concentration (µg/m3) at Specific Receptor Locations within Each Site East Hants Hangers SAC

Woolmer Forest SAC

Shortheath Common SAC

Thursley, Ash, … SAC

Wealden Heaths SPA P 1

Wealden Heaths SPA P 2

2010

43.9

91.1

41.5

187.9

214.2

2026 Baseline

22.8

33.3

19.8

53.1

58.9

Scenario

Objective

Table 10:

Area (ha) Over Which the Annual Mean NOx Objective Is Predicted to be Exceeded East Hants Hangers SAC

Woolmer Forest SAC

Shortheath Common SAC

Thursley, Ash, … SAC

Wealden Heaths SPA P 1

Wealden Heaths SPA P 2

0.2

22.2

<0.1

40.6

88.4

2026 Baseline

0.5

6.5

6.9

Total Area of SAC/SPA in Study Area

572

670

3,288

1,880

2,057

Scenario

2010

In practice, this covers the same area as Thursley Ash, Pirbright and Chobham SAC, but is treated as a separate site in this assessment.

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Baseline Deposition Fluxes 4.5

Table 11 sets out the predicted background deposition fluxes to each area.

Unlike the NOx

concentrations, which are site-specific maxima, these values represent the average flux across each European site.

These background deposition fluxes, obtained from APIS (2011), take

account of local emissions but are dominated by inputs from further afield, with local roads only accounting for a relatively small proportion of the totals. Comparing the data in Table 11 with those in Table 2 shows that all of the lower-bound critical loads are predicted to be exceeded in 2020. 4.6

Table 11 shows that background deposition fluxes in 2020 are lower than those in 2005. Given that the critical loads are all estimated to be exceeded in 2020 it is likely that exceedences will persist in future years. The assumption has been made that the critical loads will continue to be exceeded across each site in 2026 without the proposed Eco-town.

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Table 11:

Area-Average Background Deposition Fluxes in 2005 and 2020

Site

East Hampshire Hangers SAC

Shortheath Common SAC Thursley, Ash, Pirbright and Chobham SAC

Feature of Interest

Wealden Heaths SPA Phase 2

2020

2005

2020

Semi-natural dry grasslands and scrubland facies: on calcareous substrates (including orchid sites)

22.1

15.5

1.58

1.11

Asperulo-Fagetum beech forests

41.0

29.0

2.93

2.07

Tilio-Acerion forests of slopes, screes and ravines

41.0

29.0

2.93

2.07

Taxus baccata woods of the British Isles

41.0

29.0

2.93

2.07

Gentianella anglica

22.1

15.5

1.58

1.11

European dry heaths

19.5

14.1

1.39

1.01

Transition mires and quaking bogs

19.5

14.1

1.39

1.01

Bog woodland

35.8

26.2

2.56

1.87

Northern Atlantic wet heaths with Erica tetralix

16.2

10.6

1.16

0.76

European dry heaths

16.2

10.6

1.16

0.76

Depressions on peat substrates of the Rhynchosporion

16.2

10.6

1.16

0.76

Coniferous Woodland

32.1

21.4

2.29

1.53

Dwarf Shrub Heath

17.1

11.2

1.22

0.8

Coniferous Woodland

32.1

21.4

2.29

1.53

Dwarf Shrub Heath

17.1

11.2

1.22

0.8

Sylvia undata

Dwarf Shrub Heath

17.1

11.2

1.22

0.8

Caprimulgus europaeus

Coniferous Woodland

36.1

25.2

2.58

1.8

Dwarf Shrub Heath

19.5

13.6

1.39

0.97

Coniferous Woodland

36.1

25.2

2.58

1.8

Dwarf Shrub Heath

19.5

13.6

1.39

0.97

Dwarf Shrub Heath

19.5

13.6

1.39

0.97

Northern Atlantic wet heaths with Erica tetralix

19.9

14.1

1.42

1.01

Natural dystrophic lakes and ponds

20.6

12.7

1.47

0.91

European dry heaths

19.9

14.1

1.42

1.01

Transition mires and quaking bogs

19.9

14.1

1.42

1.01

Depressions on peat substrates of the Rhynchosporion

19.9

14.1

1.42

1.01

Lullula arborea

Lullula arborea Sylvia undata

Woolmer Forest SAC

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Acid N (kg/ha/yr)

2005

Caprimulgus europaeus Wealden Heaths SPA Phase 1

Nutrient N (kg/ha/yr)

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Impact Assessment Ambient NOx Concentrations

5.1

Table 12 sets out the maximum predicted annual mean NOx process contribution associated with each individual energy option and traffic scenario within each European site.

It should be

recognised that these show the maxima from all 22,000 receptors; which for traffic impacts are at the very edge of the A325 at Broxhead Common. Further from the carriageway, the predicted impacts are much smaller than shown in Table 12. As explained in paragraphs 2.12 and 2.14, where a process contribution represents less than 1% of the relevant objective, impacts can be discounted as insignificant. Those values which represent more than 1% of the objective are shown in bold in Table 12. 5.2

The only energy option which would give rise to a potentially significant impact to any of the European sites is Option 2 (Central CHP plant burning biogas produced by anaerobic digestion). Even this option only contributes 0.32 Âľg/m3 (1.1% of the objective) even at the very edge of the Wealden Heaths SPA (Phase 2).

5.3

The contributions to ambient NOx concentrations associated with the road traffic scenarios are much higher than those from the energy options, but as explained in paragraph 5.1, these maxima represent concentrations close to the edge of roads and should not be interpreted as representing concentrations across entire habitats. At Wealden Heaths (Phase 2) all of the scenarios would contribute more than 63% of the objective level, rising to 82% for Scenario 13. Different traffic scenarios give rise to the greatest incremental changes at different European sites. For example Scenario 13 would create the largest incremental change at Wealden Heaths SPA (Phase 2), but Scenario 17 would create the largest incremental change at Shortheath Common SAC.

5.4

Table 13 shows the maximum predicted annual mean NOx concentrations within any of the European sites under a range of scenarios.

All of the predicted concentrations in 2026 are

significantly lower than those for 2010. The objective is predicted to be exceeded in both of the Wealden Heaths SPAs and two of the SACs whether the proposed scheme proceeds or not. Scenario 17 is predicted to cause the objective to be marginally exceeded within the Shortheath Common SAC.

It is clear that even the worst-case energy option (Option 2) has very little

influence on these predicted concentrations.

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Table 12:

Summary of Maximum Annual Mean NOx Individual Process Contributions at Each Site a

Scenario

East Hants Hangers SAC

Woolmer Forest SAC

Shortheath Common SAC

Thursley, Ash, … SAC

Wealden Heaths SPA P 1

Wealden Heaths SPA P 2

Maximum Energy Generation Process Contribution to Annual mean NOx (µg/m3) Opt 1

0.01

0.02

0.01

0.19

Opt 2

0.01

0.03

0.04

0.01

0.32

Opt 3

0.01

0.02

0.01

0.15

Opt 4

0.01

0.02

0.01

0.19

Opt 5

0.00

Opt 6

0.00

Opt 7

0.00

Maximum Incremental Increase in Road-NOx (µg/m3) (i.e. difference between each option and 2026 baseline) Sc4

4.18

6.83

4.62

0.46

21.79

Sc13

3.40

7.62

8.68

0.82

24.72

Sc17

3.00

7.41

13.04

1.32

20.93

Sc3

3.15

6.13

3.45

0.46

19.17

Objective a

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Values have been rounded, so those reported as 0.00 are >0.0005. Values exceeding 1% of the objective are shown in bold.

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Table 13:

Summary of Maximum Predicted Annual Mean NOx Concentration at Specific Receptor Locations within Each Site a East Hants Hangers SAC

Woolmer Forest SAC

Shortheath Common SAC

Thursley, Ash, â&#x20AC;Ś SAC

Wealden Heaths SPA P 1

Wealden Heaths SPA P 2

2010

43.9

91.1

41.5

187.9

214.2

2026 Baseline

22.8

33.3

19.8

53.1

58.9

Scenario

Traffic Scenarios Without Energy Contribution 2026 Sc4 b

21.6

40.1

24.4

53.3

72.9

2026 Sc13 b

22.0

40.9

28.5

53.9

75.8

2026 Sc17 b

22.1

40.7

32.8

54.4

72.1

2026 Sc3 b

21.3

39.4

23.2

53.3

70.3

Traffic Scenarios Plus Energy Option 2 Sc4 + Opt 2

21.7

40.1

24.4

53.3

73.0

Sc13 + Opt 2

22.0

40.9

28.5

54.0

75.9

Sc17 + Opt 2

22.1

40.7

32.9

54.4

72.1

Sc3 + Opt 2

21.3

39.4

23.3

53.3

70.4

Objective a

5.5

Exceedences of the 30 Âľg/m3 objective are highlighted in bold.

Table 14 shows the area of each European site over which the annual mean NOx objective is predicted to be exceeded. The areas of exceedence represent only very small fractions of each site in 2026 under all four scenarios, and are substantially smaller than those predicted in 2010. It should also be recognised that these exceedence areas represent relatively narrow (typically c.a. 10 m wide) strips along the edges of roads.

5.6

Table 15 expresses the increase in the predicted exceedence area (comparing each scenario + energy Option 2 against the 2026 baseline) as a percentage of the total area of each European site. It shows that, while the Eco-town proposals will increase the area over which the objective is predicted to exceed, these increases all represent extremely small (<0.1%) fractions of each site.

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Table 14:

Area (ha) Over Which the Annual Mean NOx Objective will be Exceeded East Hants Hangers SAC

Woolmer Forest SAC

Shortheath Common SAC

Thursley, Ash, … SAC

Wealden Heaths SPA P 1

Wealden Heaths SPA P 2

0.2

22.2

<0.1

40.6

88.4

2026 Baseline

0.5

6.5

6.9

Sc4 + Opt 2

0.6

6.6

7.8

Sc13 + Opt 2

0.7

6.7

8.4

Sc17 + Opt 2

0.7

<0.1

6.9

8.4

Sc3 + Opt 2

0.6

6.6

7.6

572

670

3,288

1,880

2,057

Scenario

2010

Total Area of SAC/SPA in Study Area Table 15:

Change in Extent of NOx Objective Exceedence (Compared with 2026 Baseline) as a Percentage of Each Site’s Total Area East Hants Hangers SAC

Woolmer Forest SAC

Shortheath Common SAC

Thursley, Ash, … SAC

Wealden Heaths SPA P 1

Wealden Heaths SPA P 2

Sc4 + Opt 2

0.01%

<0.01%

0.05%

Sc13 + Opt 2

0.03%

0.01%

0.07%

Sc17 + Opt 2

0.03%

<0.01%

0.01%

0.02%

0.08%

Sc3 + Opt 2

0.01%

<0.01%

0.04%

Scenario

Nutrient Nitrogen Deposition 5.7

Table 16 sets out the maximum predicted nutrient nitrogen deposition flux associated with each individual energy option and traffic scenario within each habitat site. It should be recognised that these show the maxima from all 22,000 receptors, which for traffic-related fluxes are at the very edge of the road. Further from the road, the predicted deposition fluxes are much smaller than shown here. As explained in paragraphs 2.12 and 2.14, where a process contribution represents less than 1% of the relevant environmental standard, impacts can be discounted as insignificant. Those values which represent more than 1% of the lower bound of the critical load range are shown in bold in Table 16.

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5.8

All of the energy options, individually, are judged to have an insignificant impact with regards to nutrient nitrogen deposition. All of the traffic scenarios considered have the potential to impact upon nearby habitat sites. Table 16:

Summary of Maximum Annual Mean Nutrient Nitrogen Deposition Fluxes at Each Site a

Scenario

East Hants Hangers SAC

Woolmer Forest SAC

Shortheath Common SAC

Thursley, Ash, â&#x20AC;Ś SAC

Wealden Heaths SPA P 1

Wealden Heaths SPA P 2

Maximum Energy Generation Contribution to Nutrient Nitrogen Deposition (kg/ha/yr) Opt 1

0.00

0.01

Opt 2

0.00

0.02

Opt 3

0.00

0.01

Opt 4

0.00

0.01

Opt 5

0.00

Opt 6

0.00

Opt 7

0.00

Maximum Incremental Increase in Nutrient Nitrogen Deposition (kg/ha/yr) (i.e. difference between each option and 2026 baseline) Sc4

0.23

0.35

0.25

0.03

1.01

Sc13

0.19

0.39

0.46

0.04

1.13

Sc17

0.17

0.38

0.69

0.06

0.97

Sc3

0.18

0.31

0.19

0.03

0.89

Critical Load a

5.9

Values have been rounded, so those reported as 0.00 are >0.0005. Values exceeding 1% of the lower bound critical load are shown in bold.

As explained in paragraph 4.6, it has been assumed that background nutrient nitrogen deposition fluxes will exceed the relevant critical loads at all of the European sites in 2026; a conservative assumption in this regard has been made that the lower bound of the critical load applies. For this reason, it is not appropriate to examine the area of critical load exceedence for nitrogen deposition. Emissions from road traffic and energy generation will add to these predicted exceedences, as shown in Table 16. Table 17 shows the area over which the combined influence of energy Option 2 and each traffic Scenario will increase fluxes by more than 1% of each site-specific critical load, while Table 18 shows these areas as a percentage of each European Site. Under Scenario 17, significant impacts cannot be discounted across 13.6% of the Shortheath Common SAC, and across 2.6% of the Wealden Heaths SPA (Phase 2).

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Table 17:

Area (ha) Over Which Nutrient Nitrogen Deposition Fluxes Will Increase by >1% of the Relevant Critical Load East Hants Hangers SAC

Woolmer Forest SAC

Shortheath Common SAC

Thursley, Ash, … SAC

Wealden Heaths SPA P 1

Wealden Heaths SPA P 2

Sc4 + Opt 2

0.8

9.4

0.6

37.7

Sc13 + Opt 2

0.5

11.7

4.8

55.9

Sc17 + Opt 2

0.4

10.6

8.0

0.9

52.5

Sc3 + Opt 2

0.4

7.8

0.1

31.0

Critical Load

Total Area of SAC/SPA in Study Area

572

670

3,288

1,880

2,057

Table 18:

Area Over Which Nutrient Nitrogen Deposition Fluxes Will Increase by >1% of the Relevant Critical Load as a Percentage of Each Site’s Total Area East Hants Hangers SAC

Woolmer Forest SAC

Shortheath Common SAC

Thursley, Ash, … SAC

Wealden Heaths SPA P 1

Wealden Heaths SPA P 2

Sc4 + Opt 2

0.1%

1.4%

0.9%

1.8%

Sc13 + Opt 2

0.1%

1.7%

8.2%

2.7%

Sc17 + Opt 2

0.1%

1.6%

13.6%

<0.1%

2.6%

Sc3 + Opt 2

0.1%

1.2%

0.1%

1.5%

Scenario

Acid Nitrogen Deposition 5.10

Table 19 sets out the maximum predicted acid nitrogen deposition fluxes.

All of the energy

options, individually, are judged to have an insignificant impact with regards to acid nitrogen deposition. All of the traffic scenarios considered have the potential to impact upon nearby habitat sites. As with nutrient nitrogen deposition, it is assumed that the acid nitrogen critical loads will be exceeded in the 2026 baseline and that contributions from energy generation and road traffic will add to the exceedences. Table 20 shows the area over which the combined influence of traffic energy Option 2 and each traffic Scenario will increase fluxes by more than 1% of the site-specific critical load, while Table 21 shows these areas as a percentage of each European site. Under Scenario 17, there is the potential for significant impacts across 26.4% of the Shortheath Common SAC, and across 2.9% of the Wealden Heaths SPA (Phase 2).

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Table 19:

Summary of Maximum Annual Mean Acid Nitrogen Deposition Fluxes at Each Site a

Scenario

East Hants Hangers SAC

Woolmer Forest SAC

Shortheath Common SAC

Thursley, Ash, … SAC

Wealden Heaths SPA P 1

Wealden Heaths SPA P 2

Maximum Energy Production Contribution to Acid Nitrogen Deposition (keq/ha/yr) Opt 1

0.000

0.001

Opt 2

0.000

0.002

Opt 3

0.000

0.001

Opt 4

0.000

0.001

Opt 5

0.000

Opt 6

0.000

Opt 7

0.000

Maximum Incremental Increase in Acid Nitrogen Deposition (keq/ha/yr) (i.e. difference between listed option and 2026 baseline)

Sc4

0.017

0.025

0.018

0.002

0.071

Sc13

0.014

0.028

0.033

0.003

0.081

Sc17

0.012

0.027

0.049

0.004

0.069

Sc3

0.013

0.022

0.013

0.002

0.063

Critical Load

0.14

0.32

0.14

0.32

Values have been rounded, so those reported as 0.000 are >0.0005. Values exceeding 1% of the critical load are shown in bold.

Table 20:

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Area (ha) Over Which Acid Nitrogen Deposition Fluxes Will Increase by >1% of the Relevant Critical Load East Hants Hangers SAC

Woolmer Forest SAC

Shortheath Common SAC

Thursley, Ash, … SAC

Wealden Heaths SPA P 1

Wealden Heaths SPA P 2

Sc4 + Opt 2

1.8

11.1

6.4

<0.1

43.5

Sc13 + Opt 2

1.6

13.7

11.3

7.4

63.3

Sc17 + Opt 2

1.5

12.5

15.6

14.6

60.4

Sc3 + Opt 2

1.4

9.3

3.6

<0.1

36.0

Critical Load

0.14

0.32

0.14

0.32

Total Area of SAC/SPA in Study Area

572

670

3,288

1,880

2,057

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Table 21:

Area Over Which Acid Nitrogen Deposition Fluxes Will Increase by >1% of the Relevant Critical Load as a Percentage of Each Siteâ&#x20AC;&#x2122;s Total Area East Hants Hangers SAC

Woolmer Forest SAC

Shortheath Common SAC

Thursley, Ash, â&#x20AC;Ś SAC

Wealden Heaths SPA P 1

Wealden Heaths SPA P 2

Sc4 + Opt 2

0.3%

1.7%

10.9%

<0.1%

2.1%

Sc13 + Opt 2

0.3%

2.0%

19.2%

0.2%

0.4%

3.1%

Sc17 + Opt 2

0.3%

1.9%

26.4%

0.4%

0.8%

2.9%

Sc3 + Opt 2

0.2%

1.4%

6.2%

<0.1%

1.7%

Scenario

Uncertainty 5.11

The emission rates derived for the various energy options have been based on current technologies and may not accurately represent actual emissions in 2026, which may reasonably be expected to be lower. Furthermore, because of the range of technologies considered, some of the emission factors are considered more reliable than others. Despite these limitations, the emission factors used are considered to represent the best information available at this time. The impacts associated with the energy options are also influenced by the assumed location of the plant, as well as the release parameters that were assumed.

5.12

In terms of road traffic emissions, there are many components that contribute to the uncertainty of modelling predictions. The model used in this assessment is dependant upon the traffic data that have been input, which will have inherent uncertainties associated with them. There are then additional uncertainties, as the model is required to simplify real-world conditions into a series of algorithms. An important stage in the process is model verification, which involves comparing the model output with measured concentrations (see Appendix A2). The level of confidence in the verification process is necessarily enhanced when data from an automatic analyser have been used, as has been the case for this assessment (see Appendix A2). The monitoring data against which the model has been verified relate to an urban location, but most of the European sites are outside of urban areas.

The ADMS-Roads model is known to perform differently in different

environments and adjustment factors derived in urban settings are likely to give precautionary results in more rural environments.

The predictions for 2010 may thus over-estimate

concentrations. 5.13

Predicting pollutant concentrations in a future year will always be subject to greater uncertainty. For obvious reasons, the model cannot be verified in the future, and it is necessary to rely on a series of projections as to what will happen to background pollutant concentrations, and to vehicle emissions. These projections are based on emission factors published by DfT.

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5.14

Recently however, a disparity between the road transport emission projections and measured annual mean concentrations of nitrogen oxides and nitrogen dioxide has been identified by Defra (Carslaw et al, 2011). This applies across the UK, although the effect appears to be greatest in inner London; there is considerable inter-site variation. Whilst the emission projections suggest that both annual mean nitrogen oxides and nitrogen dioxide concentrations should have fallen by around 15-25% over the past 6 to 8 years, at many monitoring sites levels have remained relatively stable, or have even shown a slight increase.

5.15

The precise reason for this disparity is not known, but is thought to be related to the actual on-road performance of diesel vehicles when compared to the calculations based on the Euro standards. It may therefore be expected that nitrogen oxides and nitrogen dioxide concentrations will not fall as quickly in the near future as the current projections indicate. By 2026, it is expected that much of the fleet will be Euro 6 or above. Current evidence suggests that such vehicles will provide the benefits that Defra and the DfT have predicted.

It should, however, be recognised that the

projections for 2026 cannot expect to take full account of the vehicle technology that will be in use at that time.

Discussion of Overall Impacts 5.16

The impact of all seven energy options is considered to be ‘insignificant’. This judgement takes account of the scale of the impact in relation to the Environment Agency screening criteria, as well as in relation to total predicted NOx concentrations and nutrient and acid nitrogen deposition fluxes in 2026.

5.17

Increased traffic emissions associated with the various scenarios considered will increase NOx concentrations and nutrient and acid nitrogen deposition fluxes within the European sites. If the affected areas contain plant species which are sensitive to these impacts then the proposals may have a ‘moderate’ or ‘substantial’ adverse impact. It is important to note that the assessment has been based on the conservative assumption that background NOx concentrations and nitrogen and acid deposition rates do not decline beyond 2020; furthermore the lower bound of the critical load range has been assumed in all cases.

5.18

It should also be recognised that the affected areas are confined to realatively narrow strips along the edges of existing roads, and that concentrations and deposition fluxes in 2026 are expected to be much smaller than those in 2010. It thus seems probable that the vegetation in these “roadside strips” will be relatively insensitive to these inputs.

If the affected areas do not contain any

sensitive vegetation in 2026, then the impacts could be classified as ‘insignificant’.

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Mitigation Energy Options

6.1

The assessment has shown that the energy options are unlikely to have a significant impact on any of the European sites. It should, however, be recognised that in the absence of more specific data, a number of assumptions had to be made; most importantly regarding plant location, stack height, exit velocity and temperature, and emission rate. It is recommended that prior to construction of any plant, a thorough assessment is carried out using site-specific data.

Traffic Scenarios 6.2

The assessment has shown that all of the scenarios considered have the potential to significantly impact on the nearby European sites. This is a direct response to the predicted increase in traffic volumes on roads running near to, and through, the sites. Reducing the number of additional vehicles on these roads would reduce the traffic impacts. The predicted impacts could also be alleviated by ensuring that new vehicles introduced as part of the Eco-town proposals meet certain emissions standards. This would also have benefits beyond the current study area. It is not possible at this time to specify what these standards should be or predict the impact that such measures would have, since little is known about the vehicle technology that will be available in 2026.

6.3

Buffers of tall vegetation between affected roads and any sensitive habitats may also help to reduce any adverse impacts. A specific threat to lowland heathland as a consequence of traffic emissions is the input of nutrient nitrogen, which can encourage changes in plant community composition. A variety of habitat management techniques are available to assist in removing nutrients from heathland sites, and may be worthy of consideration as a mitigation measure. The measures include (Underhill-Day, 2010) conservation mowing (particularly in relation to dry heath), grazing, controlled burning (especially in combination with a grazing regime) and carefully planned turf stripping. Any measure deployed would require consideration on a site by site basis and would need to be agreed with the relevant agencies (e.g. Natural England).

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Summary and Conclusions

7.1

The air quality impacts associated with the operation of the Whitehill Bordon Eco-town development on nearby European ecological sites have been assessed. A range of transport model scenarios, and a range of energy options have been considered. The assessment has focused on 2026, which the proposed year of completion for the development.

7.2

The principal pollutants of concern from the energy options and from the transport scenarios are nitrogen oxides (NOx) concentrations, nutrient nitrogen deposition fluxes, and acid nitrogen deposition fluxes. Existing conditions within the study area exceed the objective for NOx across large sections of all of the European sites. Most of the critical loads for nutrient and acid nitrogen deposition are also exceeded at present.

7.3

The largest impact associated with any of the energy options is an increase in annual mean NOx concentrations equal to 1.1% of the relevant objective within Wealden Heaths SPA (Phase 2). This impact is considered to be so small compared with existing conditions in the area that the impacts associated with all of the energy options are considered to be ‘insignificant’.

7.4

Increased traffic emissions associated with the various scenarios considered will increase NOx concentrations and nutrient and acid nitrogen deposition fluxes within the European sites. If the affected areas contain plant species which are sensitive to these impacts then the proposals may have a ‘moderate’ or ‘substantial’ adverse impact. It is important to note that the assessment has been based on the conservative assumption that the lower bound of the critical load range applies in all cases.

7.5

If the affected areas do not contain any

sensitive vegetation in 2026, then the impacts could be classified as ‘insignificant’.

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References APIS, 2011. Air Pollution Information System database, available at www.apis.ac.uk (accessed October 2011) Carslaw, D, Beevers, S, Westmoreland, E and Williams, M, 2011. Trends in NOx and NO2 emissions and ambient measurements in the UK. Available at: http://ukair.defra.gov.uk/library/reports?report_id=645 Defra, 2007. The Air Quality Strategy for England, Scotland, Wales and Northern Ireland. July 2007. Defra, 2011. Defra Air Quality Website at: http://www.defra.gov.uk/environment/quality/air/airquality/ DGTC, 2004 Danish Gas Technology Centre, Emission Factors for Gas-Fired CHP Units <25MW. Available at: http://www.dgc.eu/publications/pdf/pgk_igrc04.pdf DfT 2011 Department for Transport statistics, Table TRA0307 available at http://www.dft.gov.uk/pgr/statistics/datatablespublications/roads/traffic EMEP/EEA, 2009 EMEP/EEA Air Pollutant Emission Inventory Guidebook 2009. Available at: http://www.eea.europa.eu/publications/emep-eea-emission-inventory-guidebook-2009 ESC, 2011 Evergreen State College, Washington (USA), 2011. Carbon Neutrality by 2020 - Can Biomass Gasification Play a Role? Available at: http://www.co.thurston.wa.us/planning/biomass/docs-evergrn/TESC-Public-ConsultationBoards-Group-Edits-Feb-1st.pdf Environment Agency 2005 Further Guidance on Applying the Habitats Regulations to Integrated Pollution Control (IPC), Pollution Prevention and Control (PPC) and Control of Major Accident Hazards (COMAH), Comprising of Appendix 7A for IPC and PPC and Appendices 7B and 7C for COMAH. Number 37_02. Environment Agency 2010a Environment Agency 2010a Horizontal Guidance Note H1 – Annex (f) published at www.environment-agency.gov.uk Environment Agency, 2010b. Air Quality Frequently Asked Questions http://www.environmentagency.gov.uk/static/documents/Business/noxno2conv2005_1233043.pdf EPUK, 2010. Development Control: Planning for Air Quality (2010 Update) Hall et al (2008) Review of modelling methods of near-field acid deposition – Environment Agency Science Report – SC030172/SR4a Highways Agency 2007 Design Manual for Roads and Bridges Volume 11 Section 3 as updated by HA207/07. Institute of Air Quality Management, 2009. Position on the Description of Air Quality Impacts and the Assessment of their Significance, November 2009. LDA, 2011. Whitehill Bordon Energy Feasibility Study Metcalfe 2001 Developing the Hull acid rain model: Its validation and implication for policy makers. Environmental Science and Policy, 4, 25-37. ODPM, 2005. Planning Policy Statement 9 Stationery Office, 2010. The Conservation of Habitats and Species Regulations

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Underhill-Day J.C (2010) An appraisal of actions for future management of Thursley, Ockley, Elstead, Royal and Bagmoor Commons. Prepared for the Surrey Wildlife Trust, MoD / Defence Estates and Natural England, by Footprint Ecology.

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Glossary Objectives

A nationally defined set of health-based concentrations for nine pollutants, seven of which are incorporated in Regulations, setting out the extent to which the standards should be achieved by a defined date. There are also vegetation-based objectives for sulphur dioxide and nitrogen oxides.

Critical Load

The amount of pollutant deposited to a given area over a year, below which significant harmful effects on sensitive elements of the environment do not occur, according to present knowledge

Exceedence

A period of time when the concentration of a pollutant is greater than the appropriate air quality objective. This applies to specified locations.

ADMS-Roads Atmospheric Dispersion Modelling System for Roads

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ADMS-4

Atmospheric Dispersion Modelling System for Industrial Sources

NOx

Nitrogen oxides (taken to be NO2 + NO).

Âľg/m3

Microgrammes per cubic metre.

HDV

Heavy Duty Vehicles (> 3.5 tonnes)

LDV

Light Duty Vehicles (<3.5 tonnes)

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Appendix 1 â&#x20AC;&#x201C; Professional Experience Stephen Moorcroft, BSc (Hons) MSc DIC MIEnvSc MIAQM CEnv Mr Moorcroft is a Director of Air Quality Consultants, and has worked for the company since 2004. He has over thirty-five years postgraduate experience in environmental sciences. Prior to joining Air Quality Consultants, he was the Managing Director of Casella Stanger, with responsibility for a business employing over 100 staff and a turnover of ÂŁ12 million. He also acted as the Business Director for Air Quality services, with direct responsibility for a number of major Government projects. He has considerable project management experience associated with Environmental Assessments in relation to a variety of development projects, including power stations, incinerators, road developments and airports, with particular experience related to air quality assessment, monitoring and analysis. He has contributed to the development of air quality management in the UK, and has been closely involved with the LAQM process since its inception. He has given expert evidence to numerous public inquiries, and is frequently invited to present to conferences and seminars.

Dr Ben Marner, BSc PhD MIEnvSc MIAQM Dr Marner is a Technical Director of AQC, and has more than ten years relevant experience in the field of air quality. He has been responsible for air quality and greenhouse gas assessments of road schemes, rail schemes, airports, power stations, waste incinerators, commercial developments and residential developments in the UK and abroad. He has extensive experience of using detailed dispersion models, as well as contributing to the development of modelling best practices.

Dr Marner has arranged and overseen air quality monitoring surveys, as well as

contributing to Defra guidance on harmonising monitoring methods. He has been responsible for air quality review and assessments on behalf of numerous local authorities.

He has also

developed methods to predict nitrogen deposition fluxes on behalf of the Environment Agency, provided support and advice to the UK Governmentâ&#x20AC;&#x2122;s air quality review and assessment helpdesk, Transport Scotland, Transport for London, and numerous local authorities. Dr Marner has provided public inquiry expert witness services.

Laurence Caird, MEarthSci Mr Caird is a Senior Consultant with AQC, with over four years experience in the field of air quality including the completion of air quality assessments for local authorities, new commercial and residential developments, road schemes and industrial processes in the UK. He has experience in ambient air quality monitoring for numerous pollutants using a wide range of techniques and is also competent in the monitoring and assessment of nuisance odours and construction dust. Mr Caird has worked with a variety of clients to provide expert air quality services and advice, including local authorities, planners, developers and process operators. Full CVs are available at www.aqconsultants.co.uk

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Appendix 2 – Model Verification

A2.1

In order to ensure that ADMS-Roads accurately predicts local concentrations, it is necessary to verify the model against local measurements. This appendix describes this verification. It is not practical, nor usual, to verify the ADMS-4 model and because ADMS-4 does not rely on estimated road-vehicle emission factors, the adjustment used for ADMS-Roads cannot be applied to ADMS-4. Predictions made using ADMS-4 have thus not been verified.

A2.2

East Hampshire District Council operates a roadside automatic monitoring station in Bordon, which measures NOx and nitrogen dioxide concentrations. It also operates several diffusion tube sites which measure nitrogen dioxide concentrations at roadside sites in Bordon11. All of these monitors are central to the study area. East Hampshire Council has provided recent results from these sites (Table A2.1) and the model has been run to predict NOx concentrations at each site. Table A2.1: Measured Annual Mean Nitrogen Dioxide and NOx Concentrations in 2010 Site

Nitrogen Dioxide

NOx

Automatic Monitor a BR6

25.6

59.0

Diffusion Tube Sites b

A2.3

BR4

41.5

BR7

39.7

BR5

42.2

BR2

25.2

BR3

27.3

BR9

31.5

BR8

38.3

BR1

21.1

Data taken from www.easthants.gov.uk

Data supplied by East Hampshire District Council. Data adjusted for bias by the Council using a factor of 0.94

The model output of road-NOx (i.e. the component of total NOx coming from road traffic) has been compared with the ‘measured’ road-NOx.

Measured road-NOx was calculated from the NO2

measured using diffusion tubes and the predicted background NO2 concentration using the NOx

Tubes supplied and analysed by Gradko International using the 50% TEA in acetone method.

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from NO2 calculator available on the Defra LAQM Support website (Defra, 2010bc).

For the

automatic monitor it was calculated by subtracting the background NOx from the measured total. A2.4

A primary adjustment factor was determined as the slope of the best fit line between the ‘measured’ road contribution and the model derived road contribution, forced through zero (Figure A2.1). This factor was then applied to the modelled road-NOx concentration for each receptor to provide adjusted modelled road-NOx concentrations. This was then added to the background NOx concentration to give the total NOx concentration.

A2.5

In order to calculate nitrogen deposition, it is first necessary to calculate nitrogen dioxide concentrations.

These were determined by combining the adjusted modelled road-NOx

concentrations with the predicted background NO2 concentration within the recently updated NOx from NO2 calculator available on the Defra Air Quality website (Defra, 2010b).

A secondary

adjustment factor was finally calculated as the slope of the best fit line applied to the adjusted data and forced through zero (Figure A2.2). A2.6

The following primary and secondary adjustment factors have been applied to all modelled nitrogen dioxide data:

A2.7

•

Primary adjustment factor :

4.909

•

Secondary adjustment factor:

0.969

The results imply that the model was under-predicting the road-NOx contribution.

This is a

common experience with this and most other models. The final NO2 adjustment is minor. A2.8

Figure A2.3 compares final adjusted modelled total NO2 at each of the monitoring sites, to measured total NO2, and shows a 1:1 relationship.

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Figure A2.1: Comparison of Measured Road NOx to Unadjusted Modelled Road NOx Concentrations

Figure A2.2: Comparison of Measured Total NO2 to Primary Adjusted Modelled Total NO2 Concentrations

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Figure A2.3: Comparison of Measured Total NO2 to Final Adjusted Modelled Total NO2 Concentrations

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