pedigree power, biomass facility - revised aq assessment ...€¦ · following further process...

Contents

Executive Summary ........................................................................................................................... 1

1 Introduction .............................................................................................................................. 2

1.1 Background ....................................................................................................................................2

1.2 Site Location and Context ..............................................................................................................2

1.3 Existing Site Activities ....................................................................................................................2

1.4 Proposed Site Activities .................................................................................................................2

2 Legislation and Policy ................................................................................................................ 4

2.1 European Legislation .....................................................................................................................4

2.2 UK Legislation ................................................................................................................................4

2.3 Local Air Quality Management ......................................................................................................5

2.4 Industrial Pollution Control Legislation .........................................................................................6

2.5 Environmental Assessment Levels .................................................................................................6

2.6 Critical Loads and Levels ................................................................................................................7

3 Baseline .................................................................................................................................... 8

3.1 Local Air Quality Management ......................................................................................................8

3.2 Air Quality Monitoring ...................................................................................................................8

3.3 Background Pollutant Concentrations ........................................................................................ 10

3.4 Sensitive Receptors ..................................................................................................................... 11

4 Assessment Methodology........................................................................................................ 14

4.1 Dispersion Modelling .................................................................................................................. 14

4.2 Model Input Parameters............................................................................................................. 17

4.3 Baseline Concentrations ............................................................................................................. 20

4.4 15-minute Sulphur Dioxide Concentration Predictions ............................................................... 20

4.5 Deposition Rates ......................................................................................................................... 20

4.6 Assessment Criteria .................................................................................................................... 21

4.7 Modelling Uncertainty ................................................................................................................ 21

4.8 Environment Agency Dispersion Modelling Report Requirements ............................................. 22

5 Results .................................................................................................................................... 23

5.1 Sensitive Receptors ..................................................................................................................... 23

5.2 Ecological Receptors ................................................................................................................... 39

6 Conclusions ............................................................................................................................. 46

References ...................................................................................................................................... 47

Abbreviations .................................................................................................................................. 48

Appendix I Figures ...................................................................................................................... 50

Quality Assurance

Author: Checked by: Issued by:

Gabor Antony

MSc, MIEnvSc, MIAQM

Robert Edwards

BSc, MSc, MIEMA

Gabor Antony

MSc, MIEnvSc, MIAQM

Disclaimer

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control and notify ADAS UK Ltd.

This report has been commissioned for the exclusive use of the commissioning party unless otherwise

agreed in writing by ADAS UK Ltd; no other party may use, make use of or rely on the contents of the

report. No liability is accepted by ADAS UK Ltd for any of this report, other than for the purposes for which

it was originally prepared and provided.

Opinions and information provided in this report are on basis of ADAS UK Ltd using due skill, care and

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made.

Version History

Version Date Amendments

Draft 28th September 2015 Initial Report

Client Draft 5th October 2015 Reviewed and approved for client issue

First Issue 22nd October 2015 First issue following client approval

Proposed Biomass and Waste Water Treatment Plant - Browns Road, Daventry Air Quality Assessment

© ADAS 1

ADAS UK Ltd was commissioned by Pedigree Power to undertake an Air Quality Assessment for a proposed

Biomass Combustion and Wastewater Treatment Plant on land off Browns Road, Daventry.

The plant will comprise a biomass combustion plant, heat recovery boiler, two screw expanders (up to

1.0MWe of renewable electricity generation) and four evaporative waste water treatment units.

Atmospheric emissions from the proposed combustion processes have the potential to cause increases in

ground level pollutant concentrations. As such, an Air Quality Assessment was required to quantify

impacts in the vicinity of the site. This was submitted in support of the Planning Application.

Following further process design a number of exhaust gas parameters were revised from the values used

in the initial assessment. The dispersion modelling was therefore updated to take account of the amended

data and quantify impacts at both human and ecological receptors.

Impacts on existing pollutant concentrations were not predicted to be significant at any location within

the assessment extents.

Nitrogen and acid gas deposition rates were also predicted at the relevant ecological sites. Results

indicated that emissions from the installation would not significantly affect existing conditions at any

designation.

It should be noted that predicted impacts were predicted based on a worst-case assessment scenario of

the facility constantly emitting the maximum permitted concentration of each pollutant throughout an

entire year. As such, predicted concentrations and deposition rates are likely to overestimate actual

impacts.


© ADAS 2

This Air Quality Assessment has been prepared by ADAS UK Ltd under instruction from Pedigree Power

for a proposed Biomass Combustion and Wastewater Treatment Plant (WwTP) on land off Browns Road,

Daventry.

Atmospheric emissions of combustion products from the proposed combustor unit have the potential to

cause increases in ground level pollutant concentrations. An Air Quality Assessment was therefore

required to consider impacts as a result of emissions from the installation in order to support the

Environmental Permit Application for the installation.


in the initial assessment. The dispersion modelling was therefore updated to take account of the amended

data and the results are provided in the following report.

The site is located west of Daventry at approximate National Grid Reference (NGR): 455500, 262500 and

is bounded to the east by the Ford Distribution Centre, to the north by agricultural land, and to the west

and south by leisure and sport facilities. The total area of the site is approximately 0.6ha. Figure 1 in

Appendix I shows a location plan.

The plant will comprise a Combined Heat and Power (CHP) unit which will consist of a Biomass Combustion

Plant, heat recovery boiler and two screw expanders (up to 1.0MWe of renewable electricity generation)

and a WwTP containing four waste water treatment evaporator units with associated storage tanks.

Atmospheric emissions from the proposed combustion processes have the potential to cause increases in

ground level pollutant concentrations at sensitive receptor locations. As such, an Air Quality Assessment

was required to quantify impacts in the vicinity of the site. This is detailed in the following report.

The current activities on site include the processing of green waste (Earthworm Plc) with approximately

1% food waste, which is taken in to an existing Reception Hall where it is shredded and loaded into an in-

vessel composting (IVC) unit. After 5-days residence time in the 10 in-vessel cells the material is chopped

and conveyed out into the Maturation Hall.

Both buildings and the IVC vessels are under air extraction and the extracted air is treated in an existing

biofilter which is designed to reduce odour emissions from the processing activities.

As part of the proposed development green waste processing and composting will cease and the plant

will instead take in pre-shredded waste wood at a rate of up to 30,000 tonnes per annum. The biomass

will be delivered into a storage hall with 4-days capacity and then onto a self-feeder floor to supply the

proposed new biomass plant on demand.

The biomass will be fed into the combustion plant to create steam to supply 15 tonnes per hour of 190°C

steam at 22bar.The biomass plant will be free-standing in the yard between the two site buildings. Figure

1 shows a site layout plan.


© ADAS 3

The steam generated will pass through two 500kWe screw expanders, which will generate electricity,

initially to meet on site demand with the balance exported to the grid. Once the steam has passed through

the screw expanders it will be ducted into the water process hall where it will operate four evaporators,

each with the capacity to process 1,800 litres of wastewater per hour. The evaporators will be skid-

mounted units, automated to run unattended 24-hours a day.

Waste water will be transported to the site via tanker and discharged into the two 98,000 litre storage

tanks located along the Waste Water Treatment Building. The holding tanks will supply the evaporators

on demand. Evaporated water vapour will either be condensed or vented to atmosphere. The condensed

water will be recirculated to one of the holding tanks and discharged to drain in some proportion,

depending on the remaining level of contamination.

Woody biomass fuel will be delivered into the storage hall at a rate of up to 30,000 tonnes per annum.

Different types of biomass will be loaded onto the self-feeding floor to average out variations in feedstock.

Waste water will be transported to the site via tanker and discharged into storage tanks. If there is a large

amount of re-distilling necessary, lower volumes of waste water will be imported. The exact volume of

water received will be scaled up or down according to the process capacity at that point in time, for

example if one of the evaporators were not working at full capacity then the intake of waste water will be

reduced in proportion. This will ensure that the storage capacity on site is never exceeded.

Steam from the CHP unit will be used to drive the screw expanders, generating electricity. The site power

needs will be drawn from the screw expanders electrical output and the balance generated will be sold

via a two-way meter to the National Grid.

Ash from the combustion plant totalling about 0.4 tonnes per day will be exported, along with the small

amount of dry solids from the evaporators, to composting operations at other sites.

All the steam generated will be delivered through the screw expanders to the evaporator units.

Wastewater stored in holding tanks can be run through any or all of the evaporator units. One of the units

will be equipped with a condenser which will be used for water streams that generate vapour that is

potentially too odorous to release directly to atmosphere or through a biofilter. The site will have a 40ft

containerised biofilter which will be used to abate odour emissions in extracted air from both the

feedstock store and the WwTP.

The condenser evaporator will be capable of re-distilling the vapour as much as is necessary to reduce the

odour and further clean and clarify the water for discharge to drain. Prior to the discharge of condensed

clean water to surface water it will be stored in a 72,000 litre galvanised steel water storage tank located

to the south of the Waste Water Treatment Building.

The combustion plant, screw expanders and evaporators will run 24-hours a day, 8,000-hours per year.

Biomass loading, wastewater reception and maintenance will be completed during the working day.


© ADAS 4

European Union (EU) air quality legislation is provided within Directive 2008/50/EC, which came into force

on 11th June 2008. This Directive consolidated previous legislation which was designed to deal with specific

pollutants in a consistent manner and provided new air quality objectives for particulate matter with an

aerodynamic diameter of less than 2.5µm (PM2.5). The consolidated Directives include:

Directive 99/30/EC - the First Air Quality "Daughter" Directive - sets ambient Air Quality Limit Values (AQLVs) for nitrogen dioxide (NO2), oxides of nitrogen (NOx), sulphur dioxide, lead and particulate matter with an aerodynamic diameter of less than 10µm PM10;

Directive 2000/69/EC - the Second Air Quality "Daughter" Directive - sets ambient AQLVs for benzene and carbon monoxide; and,

Directive 2002/3/EC - the Third Air Quality "Daughter" Directive - seeks to establish long-term objectives, target values, an alert threshold and an information threshold for concentrations of ozone in ambient air.

The fourth daughter Directive was not included within the consolidation and is described as:

Directive 2004/107/EC - sets health-based limits on polycyclic aromatic hydrocarbons, cadmium, arsenic, nickel and mercury, for which there is a requirement to reduce exposure to as low as reasonably achievable.

The Air Quality Standards Regulations (2010) came into force on 11th June 2010 and transpose the EU

Directive 2008/50/EC into UK law. AQLVs were published in these regulations for 7 pollutants, as well as

Target Values for an additional 5 pollutants.

Part IV of the Environment Act (1995) requires UK government to produce a national Air Quality Strategy

(AQS) which contains standards, objectives and measures for improving ambient air quality. The most

recent AQS was produced by the Department for Environment, Food and Rural Affairs (DEFRA) (and its

devolved counter-parts in Scotland, Wales and Northern Ireland) and published in July 20071. The AQS

sets out Air Quality Objectives (AQOs) that are maximum ambient pollutant concentrations that are not

to be exceeded either without exception or with a permitted number of exceedences over a specified

timescale. These are generally in line with the AQLVs, although the requirements for compliance vary

slightly.

Table 1 presents the AQLVs and AQOs for the pollutants considered within this assessment.

Table 1 Air Quality Limit Values and Objectives

Pollutant Air Quality Limit Value

Concentration (µg/m3) Averaging Period

NO2 40 Annual mean

200 1-hour mean; not to be exceeded more than 18 times a year

PM10 40 Annual mean


1 The Air Quality Strategy for England, Scotland, Wales and Northern Ireland, DEFRA, 2007.


© ADAS 5



SO2



266 15-minute mean; not to be exceeded more than 35 times a year

C6H6 5 Annual mean

Pb 0.25 Annual mean

PM2.5 25 Annual mean

CO 10,000 8-hour running mean

Table 2 presents the Air Quality Target Values for pollutants considered within this assessment.

Table 2 Air Quality Target Values


Concentration (ng/m3) Averaging Period

As 6 Annual mean

Cd 5 Annual mean

Ni 20 Annual mean

Table 3 presents the critical levels for the protection of vegetation for pollutants considered within this

assessment.

Table 3 Critical Levels for the Protection of Vegetation



NOx 30 Annual mean

75 24-hour mean

SO2 20 Annual mean

Ammonia

(NH3)

3 Annual mean for all higher plants

1

Annual mean for sensitive lichen communities and bryophytes and

ecosystems where lichens & bryophytes are an important part of

the ecosystem’s integrity

Hydrogen

fluoride

(HF)

5 Daily mean

0.5 Weekly mean

It should be noted that the critical levels for NH3 and HF are provided in EA Guidance H1 Annex F - Air

Emissions2 and are not included within the Air Quality Standards Regulations (2010) or AQS.

Under Section 82 of the Environment Act (1995) (Part IV) Local Authorities (LAs) are required to

periodically review and assess air quality within their area of jurisdiction under the system of Local Air

Quality Management (LAQM). This review and assessment of air quality involves considering present and

2 Horizontal Guidance Note H1 - Annex (f), Environment Agency, 2010.


© ADAS 6

likely future air quality against the AQOs. If it is predicted that levels at locations of relevant exposure

(normally residential properties) are likely to be exceeded, the LA is required to declare an Air Quality

Management Area (AQMA). For each AQMA the LA is required to produce an Air Quality Action Plan, the

objective of which is to reduce pollutant concentrations in pursuit of the AQOs.

Atmospheric emissions from industry are controlled in England through the Environmental Permitting

(England and Wales) Regulations (2010) and subsequent amendments. The development will be classified

as a Part A1 process under the Regulations, and as such will operate under the requirements of an

environmental permit as defined by the EA. Amongst conditions of operation will be stated Emission Limit

Values (ELVs) for various pollutants produced by the process, as well as best practice guidelines for fugitive

dust and odour control. Compliance with these conditions must be demonstrated through periodic

monitoring requirements, which have been set in order to limit potential impacts in the surrounding area.

An Environmental Assessment Level (EAL) is the concentration of a substance, which, in a particular

environmental medium, the regulators regard as an appropriate value to enable a comparison between

the environmental effects of different substances in that medium and between environmental effects in

different media, enabling the summation of those effects.

Ideally EALs to fulfil this objective would be defined for each pollutant:

Based on the sensitivity of particular habitats or receptors (in particular three main types of receptor should be considered, protection of human health, protection of natural ecosystems and protection of specific sensitive receptors, e.g. materials, commercial activities requiring a particular environmental quality);

Be produced according to a standardised protocol to ensure that they are consistent, reproducible and readily understood;

Provide similar measure of protection for different receptors both within and between media; and,

Take account of habitat specific environmental factors such as pH, nutrient status, bioaccumulation, transfer and transformation processes where necessary.

EALs used in this assessment were obtained from H1 Annex F - Air Emissions2 and are summarised in

Table 4.

Table 4 Environmental Assessment Levels

Pollutant Environmental Assessment Level (µg/m3)

Long Term (Annual) Short Term (1-hour)

Hydrogen chloride (HCl) - 750

HF 16 160

Benzo-a-pyrene (BaP) 0.00025 -

Hg 0.25 7.5

Polychlorinated biphenyls (PCBs) 0.2 6

Antimony (Sb) 5 150

As 0.003 -

Chromium (Cr), Cr (II) and Cr (III) 5 150

Cr (VI) 0.0002 -


© ADAS 7

Pollutant Environmental Assessment Level (µg/m3)

Long Term (Annual) Short Term (1-hour)

Copper (Cu) 10 200

Manganese (Mn) 0.15 1,500

Vanadium (V) 5 1

It should be noted that the EAL for As of 0.003μg/m3 is lower than the Air Quality Target Value of

0.006μg/m3 and has therefore been used throughout this assessment.

A critical load is defined by the UK Air Pollution Information System (APIS)3 as:

"A quantitative estimate of exposure to deposition of one or more pollutants, below which significant

harmful effects on sensitive elements of the environment do not occur, according to present

knowledge. The exceedance of a critical load is defined as the atmospheric deposition of the pollutant

above the critical load."

A critical level is defined as:

"Threshold for direct effects of pollutant concentrations according to current knowledge. Exceedance

of a critical level is defined as the atmospheric concentration of the pollutant above the critical level."

A critical load refers to deposition of a pollutant, while a critical level refers to pollutant concentrations in

the atmosphere (which usually have direct effects on vegetation or human health).

When pollutant loads (or concentrations) exceed the critical load or level it is considered that there is a

risk of harmful effects. The excess over the critical load or level is termed the exceedence. A larger

exceedence is often considered to represent a greater risk of damage.

Maps of critical loads and levels and their exceedences have been used to show the potential extent of

pollution damage and aid in developing strategies for reducing pollution. Decreasing deposition below

the critical load is seen as means for preventing the risk of damage. However, even a decrease in the

exceedence may infer that less damage will occur.

Critical loads have been designated within the UK based on the sensitivity of the receiving habitat and

have been reviewed for the purpose of this assessment.

3 UK Air Pollution Information System, www.apis.ac.uk.


© ADAS 8

Existing air quality conditions in the vicinity of the site were identified in order to provide a baseline for

assessment. These are detailed in the following Sections.

As required by the Environmental Act (1995), Daventry District Council (DDC) has undertaken a Review

and Assessment of air quality within its area of jurisdiction. This process has indicated that air quality is

generally good in DDC's area of jurisdiction and as such, no AQMAs have been declared.

Monitoring of pollutant concentrations is undertaken by DDC using periodic methods throughout their

area of jurisdiction. A review of the most recent Air Quality Progress Report4 indicated the closest diffusion

tube monitor to the proposed development is N26 on Braunston Road at NGR: 456477, 262953. This is

approximately 1km east of the site at a kerbside location. Recent monitoring results are shown in Table 5.

Table 5 DDC Diffusion Tube Monitoring Results

Site ID Location Type Distance to

Application Site

Located

Within

AQMA?

Annual Mean NO2

Concentrations (µg/m3)

2013

N25 Ashby Road Kerbside 1.6km east No 22.90

N26 Braunston Road Kerbside 1.0km east No 20.65

As indicated in Table 5, there have not been exceedences of the annual mean AQO for NO2 at the closest

diffusion tubes during 2013. Reference should be made to Figure 1 for DDC’s non-automatic monitoring

locations in the vicinity of the site.

Monitoring of heavy metals is carried out by DEFRA at 24 sites throughout the UK. The closest monitoring

location to the facility with validated data capture is Walsall Bilston Lane (NGR: 397197, 298370) at an

'urban industrial' location situated approximately 68km north-west of the facility. It is noted that the

closest monitoring site is at Fenny Compton, 17km south-west of the proposed development site. Given

that monitoring data was only available for a period of one month during December 2014 at this site, it is

not considered to be a representative source of monitoring data, and as such was not considered further

within this assessment. The most recent data available from the Walsall Bilston Lane site is from 2014, as

summarised in Table 6.

Table 6 Metals Monitoring Results

Species 2014 Annual Mean Concentration (ng/m3)

As 1.24

Cd 2.72

Cr 3.72

Cu 85.37

4 2013 Air Quality Progress Report for Daventry District Council, DDC, 2014.


© ADAS 9


Hg (total gaseous mercury for 2013) 2.30

Mn 12.44

Ni 2.34

Pb 73.68

V 1.13

Monitoring of dioxins and PCBs is undertaken throughout the UK through the Toxic Organic Micro

Pollutants (TOMPs) network. Throughout this report, the term 'dioxins' is taken to mean the family of 210

compounds or congeners comprising polychlorinated dibenzodioxins (PCDDs) and polychlorinated

dibenzofurans (PCDFs). If both PCDDs and PCDFs are present, these have been referred to as PCDD/Fs.

The summation of the concentrations of 17 toxic PCDD and PCDF congeners, weighted relative to the

toxicity of 2,3,7,8-TCDD, is given in the form of Toxic Equivalents (TEQ).

There are very few TOMPs monitoring sites in England, with the closest to the application site being at

London Nobel House at an 'urban background' location. The most recent data available from this site is

from 2010 and is summarised in Table 7.

Table 7 Dioxins and Furans and Polychlorinated Biphenyls Monitoring Results

Species Unit 2010 Annual Mean Concentration

PCDD/Fs TEQ fg/m3 38.60

PCBs pg/m3 15.7*

Note: * Based on Σ7PCB = Sum of PCB 28+31, PCB 52, PCB 90/101, PCB 118, PCB 138, PCB 153+132, PCB180

Monitoring of BaP is undertaken throughout the UK by the PAH network. The closest monitoring site is

Birmingham Tyburn at an 'urban background' location. The most recent data available from this site is

from 2014 and is summarised in Table 8.

Table 8 Benzo-a-pyrene Monitoring Results


BaP 0.21

Concentrations of HCl and SO2 are monitored in the UK through the UK Eutrophying and Acidifying

Pollutants (UKEAP) network. The closest site to the development is Sutton Bonnington. The most recent

data available from this site is from 2014, as summarised in Table 9.

Table 9 Acid Gas Monitoring Results

Species 2014 Annual Mean Concentration (µg/m3)

HCl 0.25

SO2 0.80

Baseline concentrations of HF are not measured locally or nationally, since these are not generally of

concern in terms of local air quality. However, the EPAQS report "Guidelines for halogens and hydrogen


© ADAS 10

halides in ambient air for protecting human health against acute irritancy effects" contains some

estimates of baseline levels. This indicates that measured concentrations have been in the range of

0.036μg/m3 to 2.35μg/m3.

In lieu of local monitoring, the maximum measured baseline HF concentration has been used for the

purpose of this assessment.

Concentrations of NH3 are also monitored through the UKEAP network. The closest site to the

development is Drayton 3. The most recent data available from this site is from 2014, as summarised in

Table 10.

Table 10 Ammonia Monitoring Results


NH3 1.04

Predictions of background pollutant concentrations on a 1km by 1km grid basis have been produced by

DEFRA for the entire of the UK to assist LAs in their Review and Assessment of air quality. The site is

located in grid square NGR: 455500, 262500. The most recent data for this location, released in June 2014,

was downloaded from the DEFRA website5 for the purpose of this assessment and is summarised in

Table 11.

Table 11 Predicted Background Pollutant Concentrations


NOx 16.80

NO2 12.31

PM10 17.11

PM2.5 11.27

SO2 2.63

C6h6 0.218

CO 261

It should be noted that background concentrations of NO2, NOx, PM10 and PM2.5 were predicted for 2015

in order to consider the closest possible opening year of the plant. The background concentration of

benzene was predicted for 2010, whilst SO2 and CO were predicted for 2001. These are the most recent

predictions available from DEFRA and are therefore considered to provide a reasonable representation of

background concentrations in the vicinity of the site.

5 http://uk-air.defra.gov.uk/data/laqm-background-maps?year=2011.


© ADAS 11

A sensitive receptor is defined as any location which may be affected by changes in air quality. These have

been defined for human and ecological receptors in the following sections.

A desk-top study was undertaken in order to identify any sensitive receptor locations in the vicinity of the

site that required specific consideration during the assessment. These are summarised in Table 12.

Table 12 Sensitive Receptor Locations

Receptor NGR (m)

ID Location X Y

R1 Elderstubbs Farm 455317.0 262489.2

R2 Ashtree Farm 454935.2 261809.6

R3 The Tollgate 455279.1 261822.4

R4 Drayton Lodge 455689.1 261933.6

R5 15 The Cherwell 455818.2 262123.7

R6 12 The Leam 455862.8 262220.9

R7 46 The Witham 455951.7 262338.2

R8 1 Eden Close 456091.7 262494.3

R9 Ford Centre Service Yard 455538.0 262591.0

The sensitive receptors identified in Table 12 represent worst-case locations. However, this is not an

exhaustive list and there may be other locations within the vicinity of the site that may experience air

quality impacts as a result of the development that have not been individually identified above. Reference

should be made to Figure 1 for a graphical representation of sensitive receptor locations.

Atmospheric emissions from the facility have the potential to impact on receptors of ecological sensitivity

within the vicinity of the site. A study was undertaken to identify any habitat sites within 10km of the

source as required by the EA's H1 guidance2 for:

Special Areas of Conservation (SACs) and candidate SACs (cSACs) designated under the EC Habitats Directive;

Special Protection Areas (SPAs) and potential SPAs designated under the EC Birds Directive; and

Ramsar Sites designated under the Convention on Wetlands of International Importance.

And also within 2km of the source for:

Sites of Special Scientific Interest (SSSI) established by the 1981 Wildlife and Countryside Act;

National Nature Reserves (NNR);

Local Nature Reserves (LNR);

Local Wildlife Sites (LWS, Sites of Interest for Nature Conservation, SINC and Sites of Local Interest for Nature Conservation, SLINC); and

Ancient woodlands.


© ADAS 12

The study was completed using the Multi-Agency Geographic Information for the Countryside (MAGIC)

web-based interactive mapping service6, which draws together information on key environmental

schemes and designations for any statutory designations. A further data search was prepared by the

Northamptonshire Biodiversity Records Centre (NBRC) to identify any non-statutory sites within 2km of

the proposed installation.

A summary of the identified ecological receptors is provided in Table 13. It should be noted that a number

of receptors have been identified on each designation to provide consideration of impacts throughout the

relevant site.

Table 13 Ecological Receptor Locations

Receptor NGR (m)

ID Location X Y

ER1 Elderstubbs Farm Pasture LWS 454945 262526



ER4 Oak Spinney (Daventry) LWS 455799 261354

ER5 Pond Spinney LWS 455917 261185

ER6 Staverton Clump LWS 454907 261279

ER7 Staverton Wood LWS 455116 261523

ER8 Staverton Wood LWS 455329 261399

ER9 Stepnell Spinney LWS 455606 261537

ER10 Stepnell Spinney LWS 455718 261586

Reference should be made to Figure 1 for maps of the sensitive ecological receptor locations.

Critical loads have been designated within the UK based on the sensitivity and relevant features of the

receiving habitat. A review of the APIS website3 was undertaken in order to identify the most suitable

habitat description and associated critical load for the area of each designation considered within the

model. This was undertaken using the 'search by location' and 'habitat/pollutant impacts' functions within

APIS. The habitat types within each designation are listed in accordance with the UK Biodiversity Action

Plan (BAP) criteria, which are then split further by the European Nature Information System (EUNIS)

habitat type. These were reviewed, along with the habitat maps available through MAGIC and the NBRC,

to define the relevant classification at each of the receptor locations. It should be noted that separate

habitat types are often listed for European and National designations, although the geographical areas

covered are the same. When this was the case the most suitable classification for the area of interest was

selected. The relevant critical loads are presented in Table 14.

Table 14 Critical Loads

Re

cep

tor

APIS Habitat Critical Load Class

Critical Load

Nitrogen Critical Load (kgN/ha/yr)

Acid (keq/ha/yr)

Low High CLmaxS CLminN CLmaxN

ER1

Neutral Grassland 20 30 3.89 0.85 4.75 ER2

ER3

6 Multi-Agency Geographic Information for the Countryside, www.magic.gov.uk.


© ADAS 13

Re

cep

tor

APIS Habitat Critical Load Class

Critical Load

Nitrogen Critical Load (kgN/ha/yr)

Acid (keq/ha/yr)

Low High CLmaxS CLminN CLmaxN

ER4 Broadleaved, Mixed and Yew Woodland 10 20 2.57 0.36 2.92




ER8


ER10

It should be noted that the information shown in Table 14 represents the most sensitive habitat within

each designation for pollutant deposition.

Background deposition rates at each ecological receptor location were obtained from the APIS website

using the 'search by location' function and are summarised in Table 15.

Table 15 Background Deposition Rates

Receptor APIS Habitat Critical Load Class

Deposition Rate

Nitrogen (kgN/ha/yr)

Acid (keq/ha/yr)

S N

ER1

Neutral Grassland 19.18 0.26 1.49 ER2

ER3

ER4 Broadleaved, Mixed and Yew Woodland 33.18 0.32 2.37




ER8


ER10


© ADAS 14

Emissions associated with the proposed combustion unit have the potential to cause increases in pollutant

concentrations in the vicinity of the site. These have been quantified through dispersion modelling in

accordance with the methodology outlined in the following Sections.

An industry standard atmospheric dispersion model, ADMS 5, was used to model releases of the identified

substances. The dispersion modelling procedure was as follows:

Information on stack dimensions and position were obtained via plans from Earthworm;

Process conditions were obtained from Earthworm;

Emission rates were calculated based on combustor specifications obtained from Earthworm;

Appropriate data to describe meteorological conditions in the vicinity of the site was obtained from the UK Met Office;

A receptor grid of potentially sensitive locations was identified in the vicinity of the installation using digital mapping;

The above information was entered into the dispersion model;

The dispersion model was run to determine pollutant levels in the vicinity of the site. The results interpretation was based on the 5-year average modelled concentration at any location of relevant exposure; and,

The study results were compared with the relevant assessment criteria.

Dispersion modelling was undertaken using ADMS 5.1 (v5.1.2.0), which has been developed by Cambridge

Environmental Research Consultants (CERC) Ltd. ADMS 5 is a steady-state atmospheric dispersion model

that is based on modern atmospheric physics. It is a new generation model utilising boundary layer height

and Monin-Obukhov length to describe the atmospheric boundary layer and a skewed Gaussian

concentration distribution to calculate dispersion under convective conditions.

The model utilises hourly meteorological data to define conditions for plume rise, transport and diffusion.

It estimates the concentration for each source and receptor combination for each hour of input

meteorology, and calculates user-selected long-term and short-term averages.

ADMS 5 has been chosen because it is "fitted for the purpose of the modelling procedure" as defined by

the guidelines published by the Royal Meteorological Society (Britter et al, 1995 and Ireland et al, 2006).

The group that leads the development of ADMS 5 is CERC, but the UK Met Office and others have made

significant contributions. The model has been extensively validated against site measurements. Details of

these validation studies and information on the development of ADMS are available on the CERC website.

The dispersion modelling considered the combustor unit to be operational under normal conditions

continuously 24-hours per day throughout the year, as such providing a robust assessment of likely

operating conditions. Abnormal operating conditions would only occur during the start-up of the plant.

The unit will be installed with a gas oil start-up burner, for bed preheating, which would produce up to

2MWth independently of the bed. This will allow rapid start-up and full load is readily attained from cold

in approximately 1-hour.

The plant will be expected to operate seven days per week 24-hours per day outside of the planned

inspection and maintenance period which would only occur once per year. Therefore, the abnormal

operating conditions associated with the start-up of the combustor unit are not considered to have any

significant impact on the surrounding environment. As such, abnormal operations have not been

considered further within this assessment.


© ADAS 15

The scenarios considered in the modelling assessment are summarised in Table 16.

Table 16 Dispersion Modelling Scenarios

Parameter Modelled As

Short Term Long Term

NO2 99.79%-ile 1-hour mean Annual mean

NOx 24-hour mean Annual mean

PM10 90.41%-ile 24-hour mean Annual mean

SO2

99.9%-ile 15-minute mean Annual mean

Annual mean 99.73%-ile 1-hour mean

99.18%-ile 24-hour mean

Total volatile organic compounds (VOCs) as C6H6 - Annual mean

HCl 1-hour mean -

HF

1-hour mean

Annual mean 24-hour mean

7-day mean

CO 8-hour mean -

Cd and Tl (as Cd) - Annual mean

Hg 1-hour mean Annual mean

Metals (total Sb, As, Pb, Cr, Co, Cu, Mn, Ni, V and

their compounds) 1-hour mean Annual mean

PCBs 1-hour mean Annual mean

BaP - Annual mean

Dioxins and furans (PCDD/Fs) - Annual mean

Nitrogen deposition - Annual deposition

Acid deposition - Annual deposition

Some short-term air quality criteria are framed in terms of the number of occasions in a calendar year on

which the concentration should not be exceeded. As such, the percentiles (%-ile) shown in Table 16 were

selected to represent the relationship between the permitted number of exceedences of short-period

concentrations and the number of periods within a calendar year.

Predicted pollutant concentrations were summarised in the following formats:

Process contribution (PC) - Predicted pollutant concentration as a result of emissions from the facility only; and

Predicted environmental concentration (PEC) - Total predicted pollutant concentration as a result of emissions from the facility and existing baseline levels.

Predicted ground level pollutant concentrations and deposition rates were compared with the relevant

AQLVs, EALs, Critical Levels and Critical Loads identified. These criteria are collectively referred to as

Environmental Quality Standards (EQSs).

Combustion products from the proposed combustor unit will be emitted from a dedicated stack. Plant

operating conditions were provided by Earthworm Plc. Relevant details are presented in Table 17.


© ADAS 16

Table 17 Process Conditions

Parameter Value Unit

Stack location 455472.3, 262573.0 NGR (X, Y; m)

Internal Stack diameter 1.05 m

Stack height 17.2 M

Flue gas efflux velocity (actual) 13.509 m/s

Flue gas temperature 150 °C

Flue gas volumetric flow rate (actual) 42,110 m3/h

Reference should be made to Figure 1 for a graphical representation of the proposed stack location.

The pollutants considered within this assessment and their associated ELVs at a temperature of 273,15K,

at 11% reference oxygen, as stated within the Industrial Emissions Directive (IED), are shown in Table 18.

Table 18 Pollutants and Emission Limit Values

Pollutant Emission Limit Value (mg/Nm3)

NOx 200

Particulate matter (PM) 10

SO2 50

Total VOCs 10

HCl 10

HF 1

CO (as half-hourly average value) 100

Cd and Tl 0.05

Hg 0.05

Metals (total Sb, As, Pb, Cr, Co, Cu, Mn, Ni, V and their

compounds)

0.5

PCDD/Fs 1 x 10-7 TEQ

NH3 0.5406

BaP 1.5 x 10-4

PCBs 0.005

It should be noted that ELVs have not been designated for NH3, BaP and PCBs in the IED. As such, suitable

concentrations were determined based on the following:

NH3 - experience of similar facilities and the likely performance of the potential plant;

BaP - The highest recorded emission concentration from the EA's public register was 0.105µg/m3 at 11% O2; and

PCBs - The waste incineration BREF provides a range of values for PCB emissions to air from European municipal waste incineration plants. This states that the annual average total PCB concentration is less than 0.005mg/Nm3 (dry, 11% oxygen, 273.15K). In lieu of other available data, this has been assumed to be the emission concentration for the facility.


© ADAS 17

Mass emission rates for use in the assessment were derived from the ELVs shown in Table 18 and are

summarised in Table 19. This represents a conservative assessment approach with emissions assumed to

be the maximum permitted with the plant operating in accordance with the relevant authorisation limits.

Table 19 Mass Emission Rates

Pollutant NOx Emissions

Concentration (mg/m3) Actual Mass Emission Rate (g/s)

NOx 129.0780 1.509854

PM 6.4539 0.075493

SO2 32.2695 0.377464

Total VOCs 6.4539 0.075493

HCl 6.4539 0.075493

HF 0.6454 0.007549

CO 64.5390 0.754927

Cd and Tl 0.0323 0.000377

Hg 0.0323 0.000377

Metals 0.3227 0.003775

PCDD/Fs 6.45 x 10-8 7.55 x 10-10

NH3 0.3489 0.004081

BaP 0.0001 0.000001

PCBs 0.0032 0.000038

Emissions of total NOx from combustion processes are predominantly in the form of nitric oxide (NO).

Excess oxygen in the combustion gases and further atmospheric reactions cause the oxidation of NO to

NO2. Comparisons of ambient NO and NO2 concentrations in the vicinity of point sources in recent years

has indicated that it is unlikely that more than 30% of the NOx is present at ground level as NO2.

Ambient NOx concentrations have been predicted through dispersion modelling. NO2 concentrations

reported in the results section assume 70% conversion from NOx to NO2 for annual means and a 35%

conversion for short term (hourly) concentrations, based upon Environment Agency (EA) methodology7.

The ELV for PM is stated as total dust. However, for the purposes of dispersion modelling it was considered

that the entire PM emission consisted of only PM10 or PM2.5. This allowed the maximum ground level

impacts, with respect to the relevant criteria, to be assessed. Actual plant emissions of PM are unlikely to

only consist of only one PM fraction, resulting in a worst-case assessment.

The ELV for VOC is stated as total organic carbon (TOC). However, for the purposes of dispersion modelling

it was considered that the entire TOC emission consisted of only benzene. This allowed the maximum

ground level impacts to be assessed with respect to the AQLV. Actual plant emissions of TOC are unlikely

to only consist of one species, resulting in a worst-case assessment. It should be noted that emissions

were modelled as TOC and results factored to benzene using the relative atomic mass to carbon ratio.

7 Conversion Ratios for NOx and NO2, Environment Agency, undated.


© ADAS 18

The ELV for Cd and Tl is stated as a total of both metals. However, for the purposes of dispersion modelling

it was considered that the entire emission consisted of only Cd. This allowed the maximum ground level

impacts, with respect to the EQS to be assessed. Actual plant emissions of Cd and Tl are unlikely to consist

of only one species, resulting in a worst-case assessment.

The ELV for Sb, As, Pb, Cr, Co, Cu, Mn, Ni and V is stated as total Group 3 metals. Due to the low EQSs that

have been designated for Cr (VI), As and Ni, the EA has issued guidance8 on the modelling of Group 3

metals in support of energy recovery plants. This was reviewed for the purpose of this assessment and

the following staged approach adopted:

Potential impacts on annual mean Cr(VI), As and Ni and 1-hour mean V concentrations were assessed as these represent the lowest EQSs;

Stage 1 - The full metal emission was considered to consist of only one species. Any species with predicted exceedences of the EQSs or that could not be screened out in accordance with the EA criteria were progressed to Stage 2;

Stage 2 - The emission was apportioned equally between the relevant species. This resulted in 11% of the ELV being apportioned to each metal. Any species with predicted exceedences of the EQSs or that could not be screened out in accordance with the EA criteria were progressed to Stage 3; and

Stage 3 - Review EA data for specific species.

Emissions were assumed to be constant, with the plant in operation 24-hours per day, 365- days per year.

This is considered to be a worst-case assessment scenario as plant shut-down or periods of reduced work

load are not reflected in the modelled emissions.

Ambient concentrations for human receptors were predicted over the area NGR: 454700, 261800 to

456200, 263300. A second Cartesian Grid was utilised to predict impacts at sensitive ecological receptors

over the area NGR: 454200, 261150 to 456700, 263650. The two Cartesian grids with the resolution of

20 and 25m respectively were included in the model. It should be noted that these are less than 1.5 times

the stack height, in accordance with the relevant Environment Agency guidance. Results were

subsequently used to produce contour plots within the Surfer software package.

Ordnance Survey Landform Panorama terrain data was included for the site and surrounding area in order

to take account of the specific flow field produced by variations in ground height throughout the

assessment extents. This was pre-processed using the dedicated terrain function within ADMS 5.

The dispersion of substances released from elevated sources can be influenced by the presence of

buildings close to the emission point. Structures can interrupt the wind flows and cause significantly

higher ground-level concentrations close to the source than would arise in the absence of the buildings.

Analysis of the site layout indicated that a number of structures in the vicinity of the combustor unit

should be included within the model in order to take account of effects on pollutant dispersion. Building

input geometries are shown in Table 20.

8 Releases from municipal waste incinerators - Guidance to applicants on impact assessment for group 3 metals stack, EA, 2012.


© ADAS 19

Table 20 Building Geometries

Building NGR (m) Height (m)

Length/ Diameter (m)

Width (m)

Angle (˚)

ID Description X Y

1 Fuel Hall 455443.4 262620.8 9.30 45.00 30.00 69.0

2 Walking Floor 455452.3 262596.9 5.00 6.00 14.50 69.0

3 WwTP 455475.4 262548.1 8.80 35.30 23.00 69.0

4 Offices 455485.9 262511.7 6.50 13.20 14.40 66.0

5 Wastewater Tank 1 455476.9 262523.4 3.04 5.50 - -

6 Wastewater Tank 2 455490.3 262528.6 3.04 7.30 - -

7 Wastewater Tanks 3 455483.6 262526.0 3.04 7.30 - -

8 Filters and Condensate Tank 455465.5 262570.2 3.00 5.00 8.20 69.0

9 Biomass Combustion Plant 455472.3 262573.0 17.20 8.15 - -

10 Proposed Biofilter 455497.8 262517.0 2.60 12.20 2.40 66.0

11 Ford Centre 455646.8 262761.7 9.00 238.10 604.50 72.8

12 Existing Biofilter 455483.8 262526.2 3.00 23.00 11.46 69.0

Reference should be made to Figure 1 for a graphical representation of the modelled building layout and

for the ADMS 5 model input.

A roughness length (z0) of 0.5m was used in the dispersion modelling study. This value of z0 is considered

appropriate for the morphology of the assessment area and is suggested within ADMS 5 as being suitable

for 'parkland, open suburbia'. A roughness length (z0) of 0.2m was considered appropriate for the

morphology of the meteorological station and is suggested within ADMS 5 as being suitable for

'agricultural areas (min)'.

The Monin-Obukhov length provides a measure of the stability of the atmosphere. A minimum Monin-

Obukhov length of 30m was used in the dispersion modelling study. This value is considered appropriate

for the nature of the assessment area and is suggested within ADMS 5 as being suitable for 'mixed

urban/industrial'. A minimum Monin-Obukhov length of 10m was considered appropriate for the

morphology of the meteorological station and is suggested within ADMS 5 as being suitable for 'small

towns < 50,000'.

Meteorological data used in this assessment was taken from Church Lawford meteorological station, over

the period 1st January 2010 to 31st December 2014 (inclusive). Church Lawford meteorological station is

located at NGR: 445632, 273629 which is approximately 18km north-west of the proposed development.

LAQM.TG(09)9 recommends meteorological stations within 30km of an assessment area as being suitable

for detailed modelling.

9 Local Air Quality Management Technical Guidance LAQM.TG(09), DEFRA, 2009.


© ADAS 20

All meteorological data used in the assessment was provided by the UK Met Office. Reference should be

made to Figure 2 for wind roses of the utilised meteorological data.

A review of existing data in the vicinity of the site was undertaken in Section 3 of this report in order to

define baseline pollutant levels. These were subsequently utilised in the assessment to represent existing

concentrations in the vicinity of the site.

It is not possible to add short-term peak baseline and process concentrations. This is because the

conditions which give rise to peak ground-level concentrations of substances emitted from an elevated

source at a particular location and time are likely to be different to the conditions which give rise to peak

concentrations due to emissions from other sources. This point is addressed in EA guidance H12, which

advises that an estimate of the maximum combined pollutant concentration can be obtained by adding

the maximum predicted short-term concentration due to emissions from the source to twice the annual

mean baseline concentration. This approach was adopted throughout the assessment.

Throughout the assessment, 15-minute mean SO2 concentrations have been calculated using the following

correction factor based upon empirical relationships with the 99.9th%-ile of 1-hour means, as described in

EA guidance H1:

99.9th%-ile of 15-minute means = 1.34 x 99.9th%-ile of 1-hour means.

Deposition rates were calculated using the conversion factors provided within EA document 'Technical

Guidance on Detailed Modelling approach for an Appropriate Assessment for Emissions to Air AQTAG

06'10. Predicted pollutant concentrations were multiplied by the relevant deposition velocity and

conversion factor to calculate the speciated dry deposition flux.

The conversion factors used are presented within Table 21.

Table 21 Deposition Rates

Pollutant Deposition Velocity (m/s) Conversion Factor (μg/m2/s to

kg/ha/yr of pollutant species) Grassland Forest

NO2 0.0015 0.003 96.0

SO2 0.0120 0.024 157.7

NH3 0.02 0.03 259.7

HCl 0.025 0.06 306.7

Due to the nature of the modelling area the deposition velocity for 'grassland' was used for the calculation

of deposition throughout the assessment.

Acid deposition occurs as a result of NO2, NH3, SO2 and HCl. Predicted ground level pollutant

concentrations of all these species were converted to kilo-equivalent ion depositions (keq/ha/yr) for

comparison with the critical load for acid deposition at each of the identified ecological receptors.

10 Technical Guidance on Detailed Modelling approach for an Appropriate Assessment for Emissions to Air AQTAG 06, EA, 2006.


© ADAS 21

The conversion to units of equivalents, a measure of the potential acidifying effect of a species, was

undertaken by multiplying the dry deposition flux by the standard conversion factors shown in Table 22.

Table 22 Conversion Factors to Units of Equivalents

Species Conversion Factor from kg/ha/yr to keq/ha/yr

N Divide by 14

S Divide by 16

HCl Divide by 35.5

The total N proportion was calculated from NO2 and NH3 concentrations, whilst the HCl equivalent was

added to the S proportion, in accordance with the methodology outlined in AQTAG 0610. The proportion

of the EQS consisting of the PC and PEC were then calculated using the tool available on the APIS website.

The effects of wet HCl deposition was undertaken using the 'falling drop method' included within ADMS 5,

with an initial pH value of droplets above the plume of 5.6, as detailed within the ADMS 5 user guide11.

Plume depletion was turned off in order to provide a worst-case assessment. The modelled outputs in

μg/m2/s were multiplied by 8.63, as provided in AQTAG 0610, to provide deposition in keq/ha/yr.

HCl deposition was then defined as the maximum calculated wet or dry value.

EA Horizontal Guidance Note H1 states that:

"process contributions can be considered insignificant if:

the long term process contribution is <1% of the long term environmental standard; and,

the short term process contribution is <10% of the short term environmental standard."

In addition, the following screening criteria are outlined in EA guidance document "Guidance to Applicants

on Impact Assessment for Group 3 Metals Stack Releases - V.3 September 2012" for metal concentrations:

Long-term PC <1% and short-term PC <10%; or,

Long-term and short-term PEC <100% (taking likely modelling uncertainties into account).

For screening purposes only, the EA methodology assumes that Cr (VI) comprises 20% of the total

background Cr.

Predicted PCs have been compared to the relevant EQSs and the criteria stated above. Where the impact

is within these parameters, the EA concludes that impacts associated with an installation are acceptable.

Uncertainty in dispersion modelling predictions can be associated with a variety of factors, including:

Model uncertainty - due to model limitations;

Data uncertainty - due to errors in input data, including emission estimates, land use characteristics and meteorology; and,

Variability - randomness of measurements used.

Potential uncertainties in model results have been minimised as far as practicable and worst-case inputs

used in order to provide a robust assessment. This included the following:

11 ADMS 5 Atmospheric Dispersion Modelling System User Guide Version 5.1, CERC, 2015.


© ADAS 22

Choice of model - ADMS 5 is a commonly used atmospheric dispersion model and results have been verified through a number of studies to ensure predictions are as accurate as possible;

Meteorological data - Modelling was undertaken using 5-years of annual meteorological data sets from a representative observation site to take account of local conditions;

Plant operating conditions - Plant operating conditions were provided by Earthworm Plc based on the anticipated fuel and plant size. As such, these are considered to be representative of operating conditions;

Emission rates - Emission rates were derived from the relevant ELVs and therefore represent the maximum potential emissions with the plant operating within the conditions of the IED. Emissions were also assumed to be constant throughout the modelling period, which does not allow for plant shut down or reduced load. These assumptions are likely to overestimate actual emissions and therefore result in a worst case assessment;

Background concentrations - Obtained from the DEFRA mapping study and national monitoring networks. Although these may underestimate actual concentrations in the vicinity of pollutant sources, such as roads, they are considered suitable for an assessment of this nature;

Receptor locations - A Cartesian Grid was included in the model in order to calculate maximum predicted concentrations throughout the assessment extents. Receptor points were also included at sensitive locations to provide additional consideration of these areas; and,

Variability - All model inputs are as accurate as possible and worst-case conditions were considered as necessary in order to ensure a robust assessment of potential pollutant concentrations.

Results were considered in the context of the relevant AQLVs, AQOs and EALs. It is considered that the

use of the stated measures to reduce uncertainty and the use of worst-case assumptions when necessary

has resulted in model accuracy of an acceptable level.

The EA dispersion modelling report requirements and their reference locations within the report is

summarised in Table 23.

Table 23 Dispersion Modelling Report Requirements

Item Reference within Report

Location map Figure 1

Site plan Figure 1

List of pollutants modelled and relevant air quality

guidelines

Table 16, Table 1, Table 2, Table 3 and Table 4

Details of modelled scenarios Table 16

Details of relevant ambient concentrations used Table 5, Table 6, Table 7, Table 8, Table 9 and Table 10

Model description and justification Section 4.1

Special model treatments used Section 4

Table of emission parameters used Table 18 and Table 19

Details of modelled domain and receptors Sections 4.2.2, 3.4.1 and 3.4.2

Details of meteorological data used (including origin)

and justification

Section 4.2.7

Details of terrain treatment Section 4.2.3

Details of building treatment Section 4.2.4

Sensitivity analysis Section 4.7


© ADAS 23

Dispersion modelling was undertaken with the inputs described in Section 4. Reference should be made

to Figures 3 to 34 in Appendix I for graphical representations of predicted pollutant concentrations,

inclusive of background, throughout the assessment extents.

It should be noted that the data shown in the Figures are predictions from the meteorological data set

which resulted in the maximum pollutant concentration. For example, the maximum annual mean NO2

concentration was predicted using the 2011 meteorological data set. As such, the contours shown in

Figure 3 were produced from the 2011 model outputs.

Predicted concentrations of each pollutant at the sensitive receptor locations identified in Table 11 are

summarised in the following Sections.

Annual Mean

Predicted annual mean NO2 concentrations are summarised in Table 24. Figure 3 provides graphical

representations of predicted concentrations throughout the assessment area.

Table 24 Predicted Annual Mean NO2 Concentrations

Receptor Predicted Annual Mean NO2

Concentration (µg/m3) Proportion of the EQS (%)

ID Location PC PEC PC PEC

R1 Elderstubbs Farm 1.57 13.88 3.92 34.70

R2 Ashtree Farm 0.30 12.61 0.75 31.53

R3 The Tollgate 0.34 12.65 0.84 31.62

R4 Drayton Lodge 0.20 12.51 0.50 31.27

R5 15 The Cherwell 0.43 12.74 1.07 31.85

R6 12 The Leam 0.57 12.88 1.41 32.19

R7 46 The Witham 0.61 12.92 1.52 32.29

R8 1 Eden Close 0.36 12.67 0.91 31.69

R9 Ford Centre Service Yard 9.45 21.76 23.62 54.39

As indicated in Table 24, predicted concentrations of NO2 were below the annual mean EQS at all sensitive

receptor locations.

As indicated in Table 24, the PC proportion of the EQS is more than 1% at five receptor locations. However,

the PEC is less than the EQS at all locations. As such, impacts are not considered to be significant. It should

be noted that the assessment considered the facility emitting the maximum permitted pollutant

concentration at all times. As such, predicted concentrations are likely to be an overestimation of actual

impacts.

1-hour Mean

Predicted 99.79%-ile NO2 concentrations are summarised in Table 25. Figure 4 provides graphical



© ADAS 24

Table 25 Predicted 99.79%-ile 1-hour Annual Mean NO2 Concentrations

Receptor Predicted 99.79%-ile 1-hour

Mean NO2 Concentration (µg/m3) Proportion of the EQS (%)



R2 Ashtree Farm 2.39 27.01 1.19 13.50

R3 The Tollgate 2.79 27.41 1.39 13.70

R4 Drayton Lodge 2.98 27.60 1.49 13.80

R5 15 The Cherwell 4.15 28.77 2.08 14.39

R6 12 The Leam 4.67 29.29 2.34 14.65

R7 46 The Witham 4.51 29.13 2.25 14.56

R8 1 Eden Close 3.86 28.48 1.93 14.24


As indicated in Table 25, predicted concentrations of NO2 were below the annual mean AQO at all

sensitive receptor locations.

As indicated in Table 25, the PC proportion of the EQS is less than 10% at all receptor locations with the

exception of R9. However, the PEC is significantly below the EQS at all locations. As such, impacts are not

considered to be significant. It should be noted that the assessment assumes that the facility is emitting

the maximum permitted pollutant concentration at all times. As such, predicted concentrations are likely

to be an overestimation of actual impacts.

Annual Mean PM10

Predicted annual mean PM10 concentrations are summarised in Table 26. Figure 5 provides graphical


Table 26 Predicted Annual Mean PM10 Concentrations

Receptor Predicted Annual Mean PM10




R2 Ashtree Farm 0.02 17.13 0.05 42.83

R3 The Tollgate 0.02 17.13 0.06 42.84

R4 Drayton Lodge 0.01 17.12 0.04 42.81

R5 15 The Cherwell 0.03 17.14 0.08 42.85

R6 12 The Leam 0.04 17.15 0.10 42.88

R7 46 The Witham 0.04 17.15 0.11 42.88

R8 1 Eden Close 0.03 17.14 0.07 42.84


As indicated in Table 26, predicted concentrations of PM10 were below the annual mean AQO at all

sensitive receptors.


© ADAS 25

As indicated in Table 26, the PC proportion of the EQS is less than 1% at all but one receptor locations.

However, at this location the PEC is considerably lower than the EQS. As such, impacts on annual mean

PM10 concentrations are considered to be insignificant. Furthermore this is a non-sensitive area which

would not be considered relevant to the AQO, as outlined in Table 1. As such, they are not considered

relevant to the assessment.

24-hour Mean PM10

Predicted 90.41%-ile 24-hour mean PM10 concentrations are summarised in Table 27. Figure 6 provides

graphical representations of predicted concentrations throughout the assessment area.

Table 27 Predicted 90.41%-ile 24-hour Mean PM10 Concentrations

Receptor

Predicted 90.41%-ile 24-hour

Mean PM10 Concentration

(µg/m3)

Proportion of the EQS (%)



R2 Ashtree Farm 0.09 34.31 0.18 68.62

R3 The Tollgate 0.09 34.31 0.18 68.62

R4 Drayton Lodge 0.06 34.28 0.12 68.56

R5 15 The Cherwell 0.12 34.34 0.25 68.69

R6 12 The Leam 0.16 34.38 0.32 68.76

R7 46 The Witham 0.16 34.38 0.32 68.76

R8 1 Eden Close 0.10 34.32 0.19 68.63


As indicated in Table 27, predicted concentrations of PM10 were below the 24-hour mean AQO at all


As indicated in Table 27, the PC proportion of the EQS is less than 10% at all receptor locations. As such,

impacts on 24-hour mean PM10 concentrations are considered to be insignificant in accordance with the

EA screening criteria.

Annual Mean PM2.5

Predicted annual mean PM2.5 concentrations are summarised in Table 28. Figure 7 provides graphical


Table 28 Predicted Annual Mean PM2.5 Concentrations

Receptor Predicted Annual Mean PM2.5




R2 Ashtree Farm 0.02 11.29 0.09 45.17

R3 The Tollgate 0.02 11.29 0.10 45.18

R4 Drayton Lodge 0.01 11.28 0.06 45.14

R5 15 The Cherwell 0.03 11.30 0.12 45.20

R6 12 The Leam 0.04 11.31 0.16 45.24

R7 46 The Witham 0.04 11.31 0.17 45.25


© ADAS 26

Receptor Predicted Annual Mean PM2.5



R8 1 Eden Close 0.03 11.30 0.10 45.18


As indicated in Table 28, predicted concentrations of PM2.5 were below the annual mean AQO at all




PM2.5 concentrations are considered to be insignificant. Furthermore this is a non-sensitive area which


relevant to the assessment.

24-hour Mean

Predicted 99.18%-ile 24-hour mean SO2 concentrations are summarised in Table 29. Figure 8 provides


Table 29 Predicted 99.18%-ile 24-hour Mean SO2 Concentrations


Mean SO2 Concentration (µg/m3) Proportion of the EQS (%)



R2 Ashtree Farm 0.44 5.70 0.35 4.56

R3 The Tollgate 0.45 5.71 0.36 4.57

R4 Drayton Lodge 0.30 5.56 0.24 4.45

R5 15 The Cherwell 0.61 5.87 0.48 4.69

R6 12 The Leam 0.80 6.06 0.64 4.85

R7 46 The Witham 0.79 6.05 0.63 4.84

R8 1 Eden Close 0.47 5.73 0.38 4.59


As indicated in Table 29, predicted 99.18%-ile 24-hour mean SO2 concentrations were below the relevant

EQS at all sensitive receptor locations


impacts on 24-hour mean SO2 concentrations are considered to be insignificant in accordance with the EA

screening criteria.

1-hour Mean

Predicted 99.73%-ile 1-hour mean SO2 concentrations are summarised in Table 30. Figure 9 provides



© ADAS 27

Table 30 Predicted 99.73%-ile 1-hour Mean SO2 Concentrations





R2 Ashtree Farm 1.68 6.94 0.48 1.98

R3 The Tollgate 1.97 7.23 0.56 2.07

R4 Drayton Lodge 2.10 7.36 0.60 2.10

R5 15 The Cherwell 2.94 8.20 0.84 2.34

R6 12 The Leam 3.30 8.56 0.94 2.44

R7 46 The Witham 3.18 8.44 0.91 2.41

R8 1 Eden Close 2.70 7.96 0.77 2.27


As indicated in Table 30, predicted 99.73%-ile 1-hour mean SO2 concentrations were below the relevant

EQS at all sensitive receptor locations.


However, the PEC is significantly below the EQS at all locations. As such, impacts are not considered to be

significant. It should be noted that the assessment assumed that the facility would be emitting the

maximum permitted pollutant concentration at all times. As such, predicted concentrations are likely to

be an overestimation of actual impacts.

15-minute Mean

Predicted 99.9%-ile 15-minute mean SO2 concentrations are summarised in Table 31. Figure 10 provides


Table 31 Predicted 99.9%-ile 15-minute Mean SO2 Concentrations

Receptor Predicted 99.9%-ile 15-minute




R2 Ashtree Farm 2.42 7.68 0.91 2.89

R3 The Tollgate 2.96 8.22 1.11 3.09

R4 Drayton Lodge 3.10 8.36 1.16 3.14

R5 15 The Cherwell 4.11 9.37 1.55 3.52

R6 12 The Leam 4.64 9.90 1.75 3.72

R7 46 The Witham 4.49 9.75 1.69 3.66

R8 1 Eden Close 4.00 9.26 1.50 3.48


As indicated in Table 31, predicted 99.9%-ile 15-minute mean SO2 concentrations were below the relevant



However, the PEC is significantly below the EQS at all locations. As such, impacts are not considered to be

significant. It should be noted that the assessment assumed that the facility would be emitting the


© ADAS 28

maximum permitted pollutant concentration at all times. As such, predicted concentrations are likely to

be an overestimation of actual impacts.

Predicted annual mean VOC concentrations (as C6H6) concentrations are summarised in Table 32.

Figure 11 provides graphical representations of predicted concentrations throughout the assessment

area.

Table 32 Predicted Annual Mean VOC (as C6H6) Concentrations

Receptor Predicted Annual Mean VOC (as

C6H6) Concentration (µg/m3) Proportion of the EQS (%)



R2 Ashtree Farm 0.02 0.46 0.43 9.15

R3 The Tollgate 0.02 0.46 0.48 9.20

R4 Drayton Lodge 0.01 0.45 0.28 9.00

R5 15 The Cherwell 0.03 0.47 0.61 9.33

R6 12 The Leam 0.04 0.48 0.81 9.53

R7 46 The Witham 0.04 0.48 0.87 9.59

R8 1 Eden Close 0.03 0.46 0.52 9.24


As indicated in Table 32, predicted annual mean VOC (as C6H6) concentrations were below the relevant


As indicated in Table 32, the PC proportion of the EQS is above 1% at two receptor locations. However, at

these locations the PEC is considerably lower than the EQS. As such, impacts on annual mean VOC

(as C6H6) concentrations are considered to be insignificant.

Predicted 1-hour mean HCl concentrations are summarised in Table 33. Figure 12 provides graphical


Table 33 Predicted 1-hour Mean HCl Concentrations

Receptor Predicted 1-hour Mean HCl




R2 Ashtree Farm 0.46 0.96 0.06 0.13

R3 The Tollgate 0.58 1.08 0.08 0.14

R4 Drayton Lodge 0.64 1.14 0.09 0.15

R5 15 The Cherwell 0.74 1.24 0.10 0.16

R6 12 The Leam 0.74 1.24 0.10 0.16

R7 46 The Witham 0.72 1.22 0.10 0.16

R8 1 Eden Close 0.71 1.21 0.09 0.16


© ADAS 29

Receptor Predicted 1-hour Mean HCl




As indicated in Table 33, predicted 1-hour mean HCl concentrations were below the relevant EQS at all



impacts on annual mean HCl concentrations are considered to be insignificant in accordance with the EA

screening criteria.

Annual Mean

Predicted annual mean HF concentrations are summarised in Table 34. Figure 13 provides graphical


Table 34 Predicted Annual Mean HF Concentrations

Receptor Predicted Annual Mean HF




R2 Ashtree Farm 0.00 2.35 0.01 14.70

R3 The Tollgate 0.00 2.35 0.02 14.70

R4 Drayton Lodge 0.00 2.35 0.01 14.70

R5 15 The Cherwell 0.00 2.35 0.02 14.71

R6 12 The Leam 0.00 2.35 0.03 14.71

R7 46 The Witham 0.00 2.35 0.03 14.71

R8 1 Eden Close 0.00 2.35 0.02 14.70


As indicated in Table 34, predicted annual mean HF concentrations were below the relevant EQS at all



impacts on annual mean HF concentrations are considered to be insignificant in accordance with the EA

screening criteria.

1-hour Mean

Predicted 1-hour mean HF concentrations are summarised in Table 35. Figure 14 provides graphical


Table 35 Predicted 1-hour Mean HF Concentrations

Receptor Predicted 1-hour Mean HF





© ADAS 30

Receptor Predicted 1-hour Mean HF



R2 Ashtree Farm 0.05 4.75 0.03 2.97

R3 The Tollgate 0.06 4.76 0.04 2.97

R4 Drayton Lodge 0.06 4.76 0.04 2.98

R5 15 The Cherwell 0.07 4.77 0.05 2.98

R6 12 The Leam 0.07 4.77 0.05 2.98

R7 46 The Witham 0.07 4.77 0.05 2.98

R8 1 Eden Close 0.07 4.77 0.04 2.98


As indicated in Table 35, predicted 1-hour mean HF concentrations were below the relevant EQS at all



impacts on 1-hour mean HF concentrations are considered to be insignificant in accordance with the EA

screening criteria.

Predicted maximum daily running 8-hour mean CO concentrations are summarised in Table 36. Figure 15

provides graphical representations of predicted concentrations throughout the assessment area.

Table 36 Predicted Maximum Daily Running 8-hour Mean CO Concentrations

Receptor

Predicted Maximum Daily

Running 8-hour mean CO

Concentration (mg/m3)




R2 Ashtree Farm 0.0002 0.52 0.00 5.22

R3 The Tollgate 0.0002 0.52 0.00 5.22

R4 Drayton Lodge 0.0001 0.52 0.00 5.22

R5 15 The Cherwell 0.0003 0.52 0.00 5.22

R6 12 The Leam 0.0004 0.52 0.00 5.22

R7 46 The Witham 0.0004 0.52 0.00 5.22

R8 1 Eden Close 0.0003 0.52 0.00 5.22


As indicated in Table 36, predicted maximum daily running 8-hour mean CO concentrations were below

the relevant EQS at all sensitive receptor locations.


impacts on maximum daily running 8-hour mean CO concentrations are considered to be insignificant in

accordance with the EA screening criteria.


© ADAS 31

Predicted annual mean Cd concentrations are summarised in Table 37. Figure 16 provides graphical


Table 37 Predicted Annual Mean Cd Concentrations

Receptor Predicted Annual Mean Cd

Concentration (ng/m3) Proportion of the EQS (%)



R2 Ashtree Farm 0.11 2.83 2.15 56.55

R3 The Tollgate 0.12 2.84 2.40 56.80

R4 Drayton Lodge 0.07 2.79 1.42 55.82

R5 15 The Cherwell 0.15 2.87 3.06 57.46

R6 12 The Leam 0.20 2.92 4.03 58.43

R7 46 The Witham 0.22 2.94 4.33 58.73

R8 1 Eden Close 0.13 2.85 2.60 57.00


As indicated in Table 37, predicted annual mean Cd concentrations were below the relevant EQS at all


As indicated in Table 37, the EA criteria for 'insignificant' impacts was not achieved for annual mean Cd

concentrations. However, this represents an extreme worst-case where the entire ELV for Cd and Tl was

considered to consist of only one species. As such, actual concentrations are likely to be lower than those

predicted. Additionally, the maximum PEC proportion of the EQS at receptor locations which are

considered relevant to the EQS was 65.59%. This provides significant headroom and it is therefore

considered unlikely that exceedences of the EQS for annual mean Cd would occur at relevant locations as

a result of emissions from the installation.

The modelling results indicated exceedences of the annual mean EQS for Cd at one location. However,

this receptor is representative of non-sensitive areas which would not be considered relevant to the

annual mean EQS. As such, it is not considered relevant to the assessment.

Annual Mean

Predicted annual mean Hg concentrations are summarised in Table 38. Figure 17 provides graphical


Table 38 Predicted Annual Mean Hg Concentrations

Receptor Predicted Annual Mean Hg




R2 Ashtree Farm 0.11 2.41 0.04 0.96

R3 The Tollgate 0.12 2.42 0.05 0.97

R4 Drayton Lodge 0.07 2.37 0.03 0.95


© ADAS 32

Receptor Predicted Annual Mean Hg



R5 15 The Cherwell 0.15 2.45 0.06 0.98

R6 12 The Leam 0.20 2.50 0.08 1.00

R7 46 The Witham 0.22 2.52 0.09 1.01

R8 1 Eden Close 0.13 2.43 0.05 0.97


As indicated in Table 38, predicted annual mean Hg concentrations were below the relevant EQS at all



However, this receptor is representative of non-sensitive areas which would not be considered relevant

to the annual mean EQS. As such, it is not considered relevant to the assessment.

1-hour Mean

Predicted Maximum 1-hour mean Hg concentrations are summarised in Table 39. Figure 18 provides


Table 39 Predicted Maximum 1-hour Mean Hg Concentrations

Receptor Predicted Maximum 1-hour

Mean Hg Concentration (ng/m3) Proportion of the EQS (%)



R2 Ashtree Farm 2.28 6.88 0.03 0.09

R3 The Tollgate 2.88 7.48 0.04 0.10

R4 Drayton Lodge 3.19 7.79 0.04 0.10

R5 15 The Cherwell 3.67 8.27 0.05 0.11

R6 12 The Leam 3.68 8.28 0.05 0.11

R7 46 The Witham 3.61 8.21 0.05 0.11

R8 1 Eden Close 3.53 8.13 0.05 0.11


As indicated in Table 39, predicted Maximum 1-hour mean Hg concentrations were below the relevant



impacts on 1-hour mean Hg concentrations are considered to be insignificant in accordance with the EA

screening criteria.

A staged assessment methodology was utilised for the prediction of grouped metal concentrations as

outlined previously. Potential impacts on annual mean Cr (VI), As and Ni and 1-hour mean V

concentrations were assessed as these represent the lowest EQSs. The results are outlined below.


© ADAS 33

Stage 1

Predicted concentrations with the full metal emission considered to consist of only one species, based on

results at the most significantly affected relevant receptor location, are summarised in Table 40.

Table 40 Predicted Metal Concentrations - Stage 1

Pollutant Averaging

Period EQS (ng/m3)

PC (ng/m3) PEC (ng/m3)

Predicted PC Proportion

of EQS (%)

Predicted

PEC

Proportion

of EQS (%)

As Annual 3 5.60 186.70 6.84 228.03

Cr (VI) Annual 0.2 5.60 2,800.47 6.34 3,172.47

Ni Annual 20 5.60 28.00 7.94 39.70

V 1-hour 1,000 508.38 50.84 510.64 51.06

As indicated in Table 40, the EA criteria were exceeded for predicted PCs for all considered metals. The

predicted annual mean Ni and the 1-hour mean V concentrations were below the relevant EQS at all

relevant sensitive receptor locations. It is considered unlikely that exceedences of the relevant EQS would

occur for Ni and V. As such, the second EA criteria is achieved and there was no requirement to proceed

to a Stage 2 Assessment for these species.

As and Cr (VI) were progressed to the Stage 2 Assessment.

Stage 2

Predicted concentrations with the metal emission distributed equally between all species are summarised

in Table 41.


Pollutant Averaging

Period EQS (ng/m3)



of EQS (%)

Predicted

PEC

Proportion

of EQS (%)

As Annual 3 0.62 20.54 1.86 61.87

Cr (VI) Annual 0.2 0.62 308.05 1.36 680.05

As indicated in Table 41, the EA criteria were exceeded for predicted PCs of As and Cr (VI).

Due to the low PEC of As it is considered unlikely that exceedences of the relevant EQS would occur. As

such, the second EA criteria is achieved and there was no requirement to proceed to a Stage 3 Assessment

for this species.

Cr (VI) was progressed to a Stage 3 Assessment.

Stage 3

The third stage of the assessment was to consider site specific assumptions. The facility will incorporate a

flue gas treatment system to remove heavy metals from the exhaust gas stream before emission to

atmosphere. The flue gas treatment system will have to be Best Available Technique (BAT) for the sector

and as such will be similar to those in use at other UK incineration and gasification facilities. It is therefore

anticipated that the performance of the proposed flue gas treatment system will be as effective in

removing heavy metals as the same system employed at a typical facility.

An analysis of the metal content in air pollution control residues recorded over three years between 2008

and 2010 at the Wilton 10 Biomass Facility was undertaken in order to determine the likely proportion of


© ADAS 34

each species. This facility utilises similar materials to those proposed for the Daventry proposal and

therefore the data is considered suitable for an assessment of this nature. The results are summarised in

Table 42.

Table 42 Metal Data from the Wilton 10 Biomass Facility

Pollutant Measured Concentration as Proportion of ELV (%)

Minimum Mean Maximum

As 0.12 0.82 1.60

Cr 0.64 1.87 3.57

Co 0.08 0.25 0.53

Cu 0.43 2.88 5.02

Mn 6.08 15.93 28.34

Ni 0.83 3.63 7.10

Pb 1.40 10.65 19.15

Sb - - -

Sn - - -

V 0.05 0.10 0.18

Total metals 9.63 36.14 65.47

Note: Sb and Sn are not monitored in the air pollution control residues.

As shown in Table 42, Cr emissions, including a proportion of Cr (VI), contribute a maximum of 3.57% of

the ELV.

The EA guidance also provides data on the proportion of Cr (VI) in total Cr. This indicates the total Cr

emission consists of 0.32% of Cr (VI). Applying these data to the measured Cr proportion shown in Table 42

and the total metals ELV provides an emission rate for Cr (VI) of 5.73 x 10-5mg/m3 The predicted maximum

PC and PEC utilising this data is summarised in Table 43.


Pollutant Averaging

Period EQS (ng/m3)



of EQS (%)

Predicted

PEC

Proportion

of EQS (%)

Cr (VI) Annual 0.2 0.0006 0.32 0.74 372.32

As indicated in Table 43, the predicted PC proportion of the EQS is significantly less than 1%. This therefore

complies with the EA criteria, although it is noted that the EQS is predicted to be exceeded, mainly due to

the high background value utilised within the assessment.

Chromium

Predicted annual mean Cr (VI) concentrations using the Stage 3 Assessment results are summarised in

Table 44. Figure 19 provides graphical representations of predicted concentrations throughout the

assessment area.


© ADAS 35

Table 44 Predicted Annual Mean Cr (VI) Concentrations

Receptor Predicted Annual Mean Cr (VI)




R2 Ashtree Farm 0.0001 0.74 0.06 372.06

R3 The Tollgate 0.0001 0.74 0.07 372.07

R4 Drayton Lodge 0.0001 0.74 0.04 372.04

R5 15 The Cherwell 0.0002 0.74 0.09 372.09

R6 12 The Leam 0.0002 0.74 0.12 372.12

R7 46 The Witham 0.0002 0.74 0.12 372.12

R8 1 Eden Close 0.0001 0.74 0.07 372.07


As indicated in Table 44, predicted annual mean Cr (VI) concentrations were above the relevant EQS at all

sensitive receptor locations. This is due to the background concentration of 0.74ng/m3, which exceeds the

EQS as a base condition.

As indicated in Table 44, the PC proportion of the EQS is less than 1% at all but one receptor location.

However, this receptor is representative of non-sensitive areas which would not be considered relevant

to the annual mean EQS. As such, it is not considered relevant to the assessment. Therefore, impacts on

annual mean Cr(VI) concentrations are considered to be insignificant in accordance with the EA screening

criteria

Arsenic

Predicted annual mean As concentrations using the Stage 2 Assessment results are summarised in

Table 45. Figure 20 provide graphical representations of predicted concentrations throughout the

assessment area.

Table 45 Predicted Annual Mean As Concentrations

Receptor Predicted Annual Mean As




R2 Ashtree Farm 0.12 1.36 3.94 45.27

R3 The Tollgate 0.13 1.37 4.41 45.74

R4 Drayton Lodge 0.08 1.32 2.61 43.94

R5 15 The Cherwell 0.17 1.41 5.62 46.95

R6 12 The Leam 0.22 1.46 7.40 48.74

R7 46 The Witham 0.24 1.48 7.94 49.27

R8 1 Eden Close 0.14 1.38 4.78 46.11


As indicated in Table 45, the EA criteria for 'insignificant' impacts was not achieved for annual mean As

concentrations. However, the maximum PEC proportion of the EQS at receptor locations which are

considered relevant to the EQS was 61.87%. This provides significant headroom and it is therefore


© ADAS 36

considered unlikely that exceedences of the EQS for annual mean As would occur at relevant locations as

a result of emissions from the installation.

The modelling results indicated exceedences of the annual mean EQS for As at one location. However,

this receptor is representative of non-sensitive areas which would not be considered relevant to the

annual mean EQS. As such, it is not considered relevant to the assessment.

Nickel

Predicted annual mean Ni concentrations using the Stage 2 Assessment results are summarised in

Table 46. Figure 21 provides graphical representations of predicted concentrations throughout the

assessment area.

Table 46 Predicted Annual Mean Ni Concentrations

Receptor Predicted Annual Mean Ni




R2 Ashtree Farm 0.12 2.46 0.59 12.29

R3 The Tollgate 0.13 2.47 0.66 12.36

R4 Drayton Lodge 0.08 2.42 0.39 12.09

R5 15 The Cherwell 0.17 2.51 0.84 12.54

R6 12 The Leam 0.22 2.56 1.11 12.81

R7 46 The Witham 0.24 2.58 1.19 12.89

R8 1 Eden Close 0.14 2.48 0.72 12.42


As indicated in Table 46, predicted annual mean Ni concentrations were below the relevant EQS at all


As indicated in Table 46, the PC proportion of the EQS is above 1% at a number of receptors. However,

the PEC is significantly below the EQS at all locations. As such, the resultant impacts are not considered

to be significant.

Vanadium

Predicted maximum 1-hour mean V concentrations using the Stage 1 Assessment results are summarised

in Table 47. Figure 22 provides graphical representations of predicted concentrations throughout the

assessment area.

Table 47 Predicted Maximum 1-hour Mean V Concentrations


Mean V Concentration (ng/m3) Proportion of the EQS (%)



R2 Ashtree Farm 22.86 25.12 2.29 2.51

R3 The Tollgate 28.84 31.10 2.88 3.11

R4 Drayton Lodge 31.94 34.20 3.19 3.42

R5 15 The Cherwell 36.80 39.06 3.68 3.91


© ADAS 37


Mean V Concentration (ng/m3) Proportion of the EQS (%)


R6 12 The Leam 36.81 39.07 3.68 3.91

R7 46 The Witham 36.12 38.38 3.61 3.84

R8 1 Eden Close 35.39 37.65 3.54 3.77


As indicated in Table 47, predicted maximum 1-hour mean V concentrations were below the relevant EQS

at all sensitive receptor locations.

As indicated in Table 47, the PC proportion of the EQS is above 10% at two receptors using the Stage 1

Assessment results. However, the PEC is significantly below the EQS at all locations. As such, the resultant

impacts are not considered to be significant.

Annual Mean

Predicted annual mean PCB concentrations are summarised in Table 48. Figure 23 provides graphical


Table 48 Predicted Annual Mean PCB Concentrations

Receptor Predicted Annual Mean PCB




R2 Ashtree Farm 0.01 0.03 0.01 0.01

R3 The Tollgate 0.01 0.03 0.01 0.01

R4 Drayton Lodge 0.01 0.02 0.00 0.01

R5 15 The Cherwell 0.02 0.03 0.01 0.02

R6 12 The Leam 0.02 0.04 0.01 0.02

R7 46 The Witham 0.02 0.04 0.01 0.02

R8 1 Eden Close 0.01 0.03 0.01 0.01


As indicated in Table 48, predicted annual mean PCB concentrations were below the relevant EQS at all


As indicated in Table 48, the PC proportion of the EQS is significantly below the 1% at all receptor

locations. As such, impacts on annual mean PCB concentrations are considered to be insignificant in


1-hour Mean

Predicted Maximum 1-hour mean PCB concentrations are summarised in Table 49. Figure 24 provides



© ADAS 38

Table 49 Predicted Maximum 1-hour Mean PCB Concentrations

Receptor Predicted 1-hour Mean PCB




R2 Ashtree Farm 0.23 0.26 0.00 0.00

R3 The Tollgate 0.29 0.32 0.00 0.01

R4 Drayton Lodge 0.32 0.35 0.01 0.01

R5 15 The Cherwell 0.37 0.40 0.01 0.01

R6 12 The Leam 0.37 0.40 0.01 0.01

R7 46 The Witham 0.36 0.39 0.01 0.01

R8 1 Eden Close 0.36 0.39 0.01 0.01


As indicated in Table 49, predicted Maximum 1-hour mean PCB concentrations were below the relevant


As indicated in Table 49, the PC proportion of the EQS is considerably below the 10% at all receptor

locations. As such, impacts on 1-hour mean PCB concentrations are considered to be insignificant in


Predicted annual mean BaP concentrations are summarised in Table 50. Figure 25 provides graphical


Table 50 Predicted Annual Mean BaP Concentrations

Receptor Predicted Annual Mean BaP




R2 Ashtree Farm 0.0003 0.21 0.11 84.11

R3 The Tollgate 0.0003 0.21 0.13 84.13

R4 Drayton Lodge 0.0002 0.21 0.08 84.08

R5 15 The Cherwell 0.0004 0.21 0.16 84.16

R6 12 The Leam 0.0005 0.21 0.21 84.21

R7 46 The Witham 0.0006 0.21 0.23 84.23

R8 1 Eden Close 0.0003 0.21 0.14 84.14


As indicated in Table 50, predicted annual mean BaP concentrations were below the relevant EQS at all




BaP concentrations are considered to be insignificant. Furthermore this is a non-sensitive area which


© ADAS 39


relevant to the assessment..

Predicted PCDD/F concentrations are summarised in Table 51. Reference should be made to Figure 26

and Figure 27 for graphical representations of predicted concentrations throughout the assessment

extents. It should be noted that EQSs have not been designated for this pollutant species and

concentrations are reported for completeness only.

Table 51 Predicted PCDD/F Concentrations

Receptor Predicted Annual Mean PCDD/F

Concentration (fg/m3)

Predicted Maximum 1-hour Mean

PCDD/F Concentration (fg/m3)



R2 Ashtree Farm 0.21 38.81 4.54 81.74

R3 The Tollgate 0.24 38.84 5.73 82.93

R4 Drayton Lodge 0.14 38.74 6.35 83.55

R5 15 The Cherwell 0.30 38.90 7.31 84.51

R6 12 The Leam 0.40 39.00 7.31 84.51

R7 46 The Witham 0.43 39.03 7.18 84.38

R8 1 Eden Close 0.26 38.86 7.03 84.23


As indicated in Table 51, the maximum modelled annual mean process contribution for dioxins and furans

associated with the operation of the facility was 1.11fg/m3 and is not expected to significantly increase

the airborne concentration or deposition rate of dioxins and furans above that already experienced in the

area. The corresponding predicted maximum 1-hour mean dioxins and furans concentration is

30.41fg/m3.This means that assuming the maximum hourly PC throughout the whole day, an average

body mass of 70kg, a worst-case adult breathing rate12 of 20m3/day and assuming that all dioxins and

furans inhaled are absorbed by the individual (i.e. none are exhaled), the uptake of dioxins and furans via

inhalation is estimated to be 0.014% of the tolerable daily intake recommended by the Committee On

Toxicity Of Chemicals in Food, Consumer Products and the Environment (COT)13. The potential effects of

dioxins released by the proposed facility can therefore be considered insignificant.

12 Technical Support Document for Exposure Assessment and Stochastic Analysis, Office of Environmental Health Hazard

Assessment California Environmental Protection Agency, 2000. 13 Statement on the Tolerable Daily Intake for Dioxins and Dioxin-like Polychlorinated Biphenyls, COT, undated.


© ADAS 40

Annual Mean

Predicted annual mean NOx concentrations at the ecological receptors are summarised in Table 52.

Reference should be made to Figure 28 for a graphical representation of predicted concentrations

throughout the assessment extents.

Table 52 Predicted Annual Mean NOx Concentrations

Receptor Predicted Annual Mean NOx


ID Designation PC PEC PC PEC

ER1 Elderstubbs Farm Pasture LWS 0.56 17.36 1.85 57.85



ER4 Oak Spinney (Daventry) LWS 0.16 16.96 0.52 56.52

ER5 Pond Spinney LWS 0.14 16.94 0.45 56.45

ER6 Staverton Clump LWS 0.28 17.08 0.95 56.95

ER7 Staverton Wood LWS 0.35 17.15 1.16 57.16


ER9 Stepnell Spinney LWS 0.22 17.02 0.73 56.73


As indicated in Table 52, predicted annual mean NOx concentrations were below the relevant EQS at all


As indicated in Table 52, the PC proportion of the EQS is slightly above 1% at a number of receptors.

However, the PEC is less than the EQS at all locations. As such, impacts are not considered to be significant.

It should be noted that the assessment assumed that the facility would be emitting the maximum

permitted pollutant concentration at all times. As such, predicted concentrations are likely to be a

significant overestimation of actual impacts.

24-hour Mean

Predicted 24-hour mean NOx concentrations at the ecological receptors are summarised in Table 53.



Table 53 Predicted 24-hour Mean NOx Concentrations

Receptor Predicted 24-hour Mean NOx










© ADAS 41

Receptor Predicted 24-hour Mean NOx







As indicated in Table 53, predicted 24-hour mean NOx concentrations were below the relevant EQS at all


As indicated in Table 53, the PC proportion of the EQS is slightly above 10% at a number of receptors.

However, the PEC is less than the EQS at all locations. As such, impacts are not considered to be significant.

It should be noted that the assessment considered the facility emitting the maximum permitted pollutant

concentration at all times. As such, predicted concentrations are likely to be a significant overestimation

of actual impacts.

Predicted annual mean SO2 concentrations at the ecological receptors are summarised in Table 54.



Table 54 Predicted Annual Mean SO2 Concentrations

Receptor Predicted Annual Mean SO2













As indicated in Table 54, predicted annual mean SO2 concentrations were below the relevant EQS at all


As indicated in Table 54, the PC proportion of the EQS is slightly above 1% at two receptors. However, the

PEC is less than the EQS at all locations. As such, impacts are not considered to be significant. It should be

noted that the assessment assumed that the facility would be emitting the maximum permitted pollutant

concentration at all times. As such, predicted concentrations are likely to be a significant overestimation

of actual impacts.


© ADAS 42

Predicted annual mean NH3 concentrations at the ecological receptors are summarised in Table 55.



Table 55 Predicted Annual Mean NH3 Concentrations

Receptor Predicted Annual Mean NH3













As indicated in Table 55, predicted annual mean NH3 concentrations were below the relevant EQS at all



impacts on annual mean NH3 concentrations are considered to be insignificant in accordance with the EA

screening criteria.

Predicted annual mean nitrogen deposition rates are summarised in Table 56. Reference should be made

to Figure 32 for a graphical representation of predicted concentrations throughout the assessment

extents.

Table 56 Predicted Annual Mean Nitrogen Deposition Rates

Receptor Predicted Annual Mean Nitrogen

Deposition Concentration (kg N/ha/yr)


Low EQS High EQS

ID PC PEC PC PEC PC PEC

ER1 0.09 19.27 0.44 96.34 0.29 64.23

ER2 0.15 19.33 0.75 96.65 0.50 64.43

ER3 0.17 19.35 0.87 96.77 0.58 64.51

ER4 0.02 33.20 0.25 332.05 0.12 166.02

ER5 0.02 33.20 0.22 332.02 0.11 166.01

ER6 0.04 33.50 0.45 335.05 0.22 167.52

ER7 0.06 33.24 0.55 332.35 0.28 166.18

ER8 0.04 33.22 0.42 332.22 0.21 166.11

ER9 0.03 33.21 0.34 332.14 0.17 166.07

ER10 0.03 33.21 0.31 332.11 0.16 166.06


© ADAS 43

As indicated in Table 56, predicted annual mean nitrogen deposition rates were above the relevant EQS

at a number of sensitive receptor locations. This is due to the high background deposition rates, which

exceed the EQSs as a base condition.


impacts on annual mean nitrogen deposition rates are considered to be insignificant in accordance with

the EA screening criteria.

Hydrogen Chloride Deposition

Wet and dry HCl deposition rates were predicted. The results are shown in Table 57. These are the

maximum values predicted for any of the five meteorological data sets modelled.

Table 57 Predicted HCl Deposition Rates

Receptor Predicted HCl Deposition Rates (keq/ha/yr)

ID Designation Wet Dry

ER1 Elderstubbs Farm Pasture LWS 0.0000 0.0012



ER4 Oak Spinney (Daventry) LWS 0.0000 0.0003

ER5 Pond Spinney LWS 0.0000 0.0003

ER6 Staverton Clump LWS 0.0000 0.0003

ER7 Staverton Wood LWS 0.0000 0.0004

ER8 Staverton Wood LWS 0.0000 0.0003

ER9 Stepnell Spinney LWS 0.0000 0.0003

ER10 Stepnell Spinney LWS 0.0000 0.0004

Total Acid Deposition

Total acid deposition rates were predicted. The results are shown in Table 58. These include contributions

from NO2, NH3, SO2 and the maximum of wet or dry HCl.

Table 58 Predicted Annual Mean Acid Deposition Rates

Receptor Predicted Annual Mean Acid Deposition Rate (keq/ha/yr) Proportion of the EQS (%)*

ID S N HCl PC PEC

ER1 0.0164 0.0046 0.0012 0.4 37.3

ER2 0.0281 0.0078 0.0012 0.8 37.7

ER3 0.0325 0.0090 0.0012 0.8 37.7

ER4 0.0046 0.0013 0.0003 0.3 92.5

ER5 0.0040 0.0011 0.0003 0.3 92.5

ER6 0.0084 0.0023 0.0003 0.9 231.9

ER7 0.0103 0.0029 0.0004 0.3 92.5

ER8 0.0078 0.0022 0.0003 0.3 92.5

ER9 0.0065 0.0018 0.0003 0.3 92.5

ER10 0.0058 0.0016 0.0004 0.3 92.5

Note: * Based on the Critical Load Function Tool of the APIS Website3


© ADAS 44

As indicated in Table 58, predicted annual mean acid deposition rates were below the relevant EQS at all

but one sensitive receptor locations. This is due to the high background deposition rates, which exceed

the EQSs as a base condition.


impacts on annual mean acid deposition rates are considered to be insignificant in accordance with the

EA screening criteria.

Weekly Mean

Predicted maximum weekly mean HF concentrations are summarised in Table 59. Reference should be

made to Figure 33 for a graphical representation of predicted concentrations throughout the assessment

extents.

Table 59 Predicted Maximum Weekly Mean HF Concentrations

Receptor Predicted Maximum Weekly Mean

HF Concentration (µg/m3) Proportion of the EQS (%)












As indicated in Table 59, predicted maximum weekly mean HF concentrations were above the relevant

EQS at all sensitive receptor locations. This is due to the background concentration of 4.70µg/m3, which

exceeds the EQS as a base condition.


impacts on weekly mean HF concentrations are considered to be insignificant in accordance with the EA

screening criteria.

24-hour Mean

Predicted maximum 24-hour mean HF concentrations are summarised in Table 60. Reference should be

made to Figure 34 for a graphical representation of predicted concentrations throughout the assessment

extents.

Table 60 Predicted Maximum 24-hour Mean HF Concentrations

Receptor Predicted Maximum 24-hour Mean






© ADAS 45

Receptor Predicted Maximum 24-hour Mean











As indicated in Table 60, predicted maximum 24-hour mean HF concentrations were below the relevant



impacts on 24-hour mean HF concentrations are considered to be insignificant in accordance with the EA

screening criteria.


© ADAS 46

ADAS UK Ltd was commissioned by Pedigree Power to undertake an Air Quality Assessment for a proposed

Biomass and Wastewater Treatment Plant on land off Browns Road, Daventry.

The plant will comprise a combustion plant, two screw expanders (up to 1.0MWe of renewable electricity

generation) and four evaporator waste water treatment units.


in the initial assessment. The ADMS 5 dispersion modelling was therefore updated to take account of the

amended data. Impacts at both human and ecological receptors were quantified and the results compared

with the relevant EQS.

Impacts on existing pollutant concentrations were not predicted to be significant at any location within

the assessment extents in accordance with the EA criteria.

Nitrogen and acid gas deposition rates were also predicted at the relevant ecological sites. Results

indicated that emissions from the installation would not significantly affect existing conditions at any

designation.

Impacts were predicted based on a worst-case assessment scenario of the facility constantly emitting the

maximum permitted concentration of each pollutant throughout an entire year. As such, predicted

concentrations and deposition rates are likely to overestimate actual impacts.


© ADAS 47

1 The Air Quality Strategy for England, Scotland, Wales and Northern Ireland, DEFRA, 2007

2 Horizontal Guidance Note H1 - Annex (f), Environment Agency, 2010

3 UK Air Pollution Information System, www.apis.ac.uk

4 2013 Air Quality Progress Report for Daventry District Council, DDC, 2014

5 http://uk-air.defra.gov.uk/data/laqm-background-maps?year=2011

6 Multi-Agency Geographic Information for the Countryside, www.magic.gov.uk

7 Conversion Ratios for NOx and NO2, Environment Agency, undated

8 Releases from municipal waste incinerators - Guidance to applicants on impact assessment for

group 3 metals stack, EA, 2012

9 Local Air Quality Management Technical Guidance LAQM.TG(09), DEFRA, 2009

10 Technical Guidance on Detailed Modelling approach for an Appropriate Assessment for

Emissions to Air AQTAG 06, EA, 2006

11 ADMS 5 Atmospheric Dispersion Modelling System User Guide Version 5.1, CERC, 2015

12 Technical Support Document for Exposure Assessment and Stochastic Analysis, Office of

Environmental Health Hazard Assessment California Environmental Protection Agency, 2000.

13 Statement on the Tolerable Daily Intake for Dioxins and Dioxin-like Polychlorinated Biphenyls,

Committee On Toxicity Of Chemicals in Food, Consumer Products and the Environment, undated


© ADAS 48

ADM Atmospheric Dispersion Modelling APIS Air Pollution Information System AQLV Air Quality Limit Value AQMA Air Quality Management Area AQO Air Quality Objective AQS Air Quality Strategy As Arsenic BaP Benzo-a-pyrene BAT Best Available Technique C6H6 Benzene Cd Cadmium CERC Cambridge Environmental Research Consultants CO Carbon monoxide Cr Chromium Cu Copper DEFRA Department for Environment, Food and Rural Affairs DDC Daventry District Council EA Environment Agency EAL Environmental Assessment Level ELV Emission Limit Value EQS Environmental Quality Standard EU European Union HCl Hydrogen chloride HF Hydrogen fluoride Hg Mercury IED Industrial Emissions Directive LA Local Authority LAQM Local Air Quality Management LNR Local Nature Reserves LWS Local Wildlife Site MAGIC Multi-Agency Geographic Information for the Countryside Mn Manganese NGR National Grid Reference NH3 Ammonia Ni Nickel NNR National Nature Reserves NO Nitrogen oxide NO2 Nitrogen dioxide NOx Oxides of nitrogen PAH Polycyclic aromatic hydrocarbon Pb Lead PC Process contribution PCB Polychlorinated biphenyl PCDD Polychlorinated dibenzodioxins PCDF Polychlorinated dibenzofurans PEC Predicted environmental concentration PM Particulate matter PM10 Particulate matter with an aerodynamic diameter of less than 10μm PM2.5 Particulate matter with an aerodynamic diameter of less than 2.5μm SAC Special Area of Conservation Sb Antimony


© ADAS 49

SINC Sites of Interest for Nature Conservation SLINC Sites of Local Interest for Nature Conservation SO2 Sulphur dioxide SPA Special Protection Area SSSI Site of Special Scientific Interest TEQ Toxic Equivalents TOC Total organic carbon TOMPS Toxic Organic Micro Pollutants UKEAP UK Eutrophying and Acidifying Pollutants V Vanadium VOC Volatile Organic Compound WID Waste Incineration Directive z0 Roughness length

pedigree power, biomass facility - revised aq assessment ...€¦ · following further process...

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