REPLACEMENT OF THE LAKESIDE ENERGY FROM WASTE … · to Slough Borough Council (SBC) for full...

REPLACEMENT OF THE LAKESIDE ENERGY FROM WASTE FACILITY AND HIGH TEMPERATURE INCINERATOR, COLNBROOK, SLOUGH ENVIRONMENTAL STATEMENT ADDENDUM LAKESIDE EFW LTD DECEMBER 2019

© Terence O’Rourke Ltd 2019. All rights reserved. No part of this document may be reproduced in any form or stored in a retrieval system without the prior written consent of the copyright holder. All figures (unless otherwise stated) © Terence O’Rourke Ltd 2019. Based upon the Ordnance Survey mapping with the permission of the Ordnance Survey on behalf of Her Majesty’s Stationery Office © Crown Copyright Terence O’Rourke Ltd Licence number 100019980.

REPLACEMENT OF THE LAKESIDE ENERGY FROM WASTE FACILITY AND HIGH TEMPERATURE INCINERATOR, COLNBROOK, SLOUGH ENVIRONMENTAL STATEMENT ADDENDUM LAKESIDE EFW LTD DECEMBER 2019

Issue / revision: 1 Prepared by Emma Robinson

Reference: 227705

This document is issued for Date December 2019

[ ] Information [ ] Approval Checked by Lauren Tinker

[ ] Comment [ X ] Submission

Comments

Date December 2019

Authorised by Steve Molnar

Date December 2019

Please return by N/A

Replacement of Lakeside EfW and HTI Facilities Lakeside EfW Ltd ES Addendum

Terence O’Rourke Ltd 227705 December 2019

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Contents

1.0 Introduction................................................................................................ 22.0 Amendments to the Environmental Statement ......................................... 33.0 Appendices .............................................................................................. 25

Appendix 1 Updated ES Chapter 12: Summary tables ..................................... 25Appendix 2 Amended Technical Appendix D: Air quality ................................... 25Appendix 3 Amended Technical Appendix E: Health Risk Assessment ............. 25Appendix 4 Amended Technical Appendix J0 Ecological Impact Assessment ... 25Appendix 5 Amended Technical Appendix J5 Updated Reptile Survey ............. 25Appendix 6 Amended Technical Appendix J9 Otter Survey .............................. 25



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1.0 Introduction

1.1 In June 2019 Lakeside EfW Ltd, Grundon Waste Management Limited and Viridor (hereafter collectively referred to as “Lakeside EfW Ltd”) submitted an application to Slough Borough Council (SBC) for full planning permission to replace the existing energy from waste (EfW) and high temperature incinerator (HTI) facilities at Lakeside Road with new facilities at a site to the immediate west of the existing Iver South Sludge Dewatering Centre, Colnbrook, Slough.

1.2 An environmental impact assessment (EIA) was undertaken as part of the application, in accordance with the Town and Country Planning (Environmental Impact Assessment) Regulations 2017 (as amended; hereafter the ‘EIA Regulations’) and an environmental statement (ES) was prepared to report the findings.

1.3 Since submission of the application in June and receipt of comments from key statutory consultees the applicant has updated the ES to take into account the following:

• Cumulative air quality impacts

• Otter technical appendix

• Updated report on reptiles

• Additional information for clarification

1.4 The purpose of this ES Addendum is therefore to set out those updates.



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2.0 Amendments to the Environmental Statement

Amendments to the figure list

2.1 No changes to the figure list are necessary.

Amendments to the Non-technical summary (NTS)

2.2 Paragraph NTS.38 has been amended to reflect the updated air quality cumulative effects assessment as follows:

An assessment of the potential for cumulative effects with other locally consented schemes has been undertaken. Due to a combination of: the location of the projects, the best practice mitigation measures that will be employed for each scheme, an absence of flue gas emissions from the other projects, and traffic movements that will not impact on the same areas of the network, or will not generate significant emissions, it was concluded that there is no potential for significant cumulative effects.

2.3 Paragraph NTS.72 has been updated as follows to remove reference to reptiles on site (see update on reptile survey work reported in this ES Addendum):

Protected species surveys found that the site is used by common reptiles, bats, breeding birds and insects. No evidence was recorded of great crested newts or common reptiles. Badgers were not recorded on site, but are present in the wider area. Otters have also been recorded in the wider area at Old Slade Lake Local Wildlife Site. A range of measures will be put in place to ensure there will be no significant adverse effects on these species during construction. These include carrying out update surveys before relevant construction works begin, moving reptiles to suitable areas of habitat off site, clearing vegetation outside the bird breeding season or under the supervision of a qualified ecologist, and covering excavations overnight to protect badgers.

Amendments to Chapter 1: Introduction

2.4 No changes to the text of chapter 1 are necessary.

Amendments to Chapter 2: Site description

2.5 Paragraph 2.16 states: ‘There is a historic hedgerow across the site that either follows a parish boundary, a historic parish boundary or corresponds with a boundary that also pre-dates 1850.’ This is incorrect. The text results from a previous access road alignment (as set out in paragraph 4.58 of chapter 4). The location of the ancient hedgerows are shown on ES Figure 8.1 – see TOR1-3, which are shown as ‘Monuments’. Paragraph 2.16 should therefore read: ‘There are two historic hedgerows to the west of the proposed access road that either follow a parish boundary, a historic parish boundary or corresponds with a boundary that also pre-dates 1850’. For the avoidance of doubt, the proposed development does not impact on any historic hedgerow.

Amendments to Chapter 3: Proposed development




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Amendments to Chapter 4: Alternatives


Amendments to Chapter 5: Environmental issues and methodology


Amendments to Chapter 6: Air quality

2.9 The measurement unit for dioxins and furans in table 6.7 is corrected from fg/m3 to fg TEQ/m3.

2.10 Paragraph 6.47 is revised as follows (additional text shown in italics):

Receptor R5 is located close to R4 but along North Road, which is fairly busy. There is a diffusion tube close to this receptor, which measures 39 µg/m3, but it is a kerbside tube only 1.6 m from the kerb. The houses along North Road are set back at least 4 m from the kerb, meaning that the concentration at these properties is likely to be lower than that monitored at the diffusion tube site. An adjustment for distance correction provided by Defra therefore needs to be applied to determine the likely concentration at the distance the receptors are from the road. The adjusted background concentration at this receptor is 36.7 µg/m3. Applying this as the baseline concentration at R5, as a conservative measure, means that the PEC is predicted to be 36.9 µg/m3, or 92.3% of the AQAL. Therefore, the impact of the replacement facilities will be negligible, as the annual mean process contribution is less than 1.5% of the AQAL and the PEC is less than 94.5% of the AQAL.

2.11 The penultimate sentence of paragraph 6.66 is revised to read as follows: However, monitoring from EfWs indicates that concentrations of cadmium are typically approximately 35% of the limit, or 7µg/Nm3.

2.12 The process contribution and PEC measurement units in table 6.18 are corrected from µg/m3 to pg/m3.

2.13 The following sentence and bullet points are added to the end of paragraph 6.91:

However, the Applicant can confirm that it will implement the highly recommended measures in the IAQM guidance if appropriate. In addition to the above, these include:

• Develop and implement a stakeholder communications plan that includes community engagement before work commences on site;

• Develop and implement a Dust Management Plan (DMP), which may include measures to control other emissions, approved by the Local Authority. The level of detail will depend on the risk, and should include as a minimum the highly recommended measures in this document. The desirable measures should be included as appropriate for the site. In London additional measures may be required to ensure compliance with the Mayor of London’s guidance. The DMP may include monitoring of dust deposition, dust flux, real-time PM10 continuous monitoring and/or visual inspections;



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• Carry out regular site inspections to monitor compliance with the DMP, record inspection results, and make an inspection log available to the local authority when asked;

• Increase the frequency of site inspections by the person accountable for air quality and dust issues on site when activities with a high potential to produce dust are being carried out and during prolonged dry or windy conditions;

• Agree dust deposition, dust flux, or real-time PM10 continuous monitoring locations with the Local Authority. Where possible commence baseline monitoring at least three months before work commences on site or, if it a large site, before work on a phase commences. Further guidance is provided by IAQM on monitoring during demolition, earthworks and construction;

• Erect solid screens or barriers around dusty activities or the site boundary that are at least as high as any stockpiles on site;

• Fully enclose site or specific operations where there is a high potential for dust production and the site is active for an extensive period;

• Avoid site runoff of water or mud;

• Cover, seed or fence stockpiles to prevent wind whipping;

• Ensure all on-road vehicles comply with the requirements of the London Low Emission Zone and the London NRMM standards, where applicable;

• Avoid the use of diesel or petrol powered generators and use mains electricity or battery powered equipment where practicable;

• Produce a Construction Logistics Plan to manage the sustainable delivery of goods and materials;

• Minimise drop heights from conveyors, loading shovels, hoppers and other loading or handling equipment and use fine water sprays on such equipment wherever appropriate;

• Use water-assisted dust sweeper(s) on the access and local roads, to remove, as necessary, any material tracked out of the site. This may require the sweeper being continuously in use;

• Avoid dry sweeping of large areas;

• Inspect on-site haul routes for integrity and instigate necessary repairs to the surface as soon as reasonably practicable;

• Install hard surfaced haul routes, which are regularly damped down with fixed or mobile sprinkler systems, or mobile water bowsers and regularly cleaned;

• Record all inspections of haul routes and any subsequent action in a site log book; and

• Access gates to be located at least 10 m from receptors where possible.

2.14 The following new paragraph is added below paragraph 6.91:



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The Applicant will also consider the additional mitigation measures that are ‘desirable’ for a medium risk site:

• Undertake daily on-site and off-site inspection, where receptors (including roads) are nearby, to monitor dust, record inspection results, and make the log available to the local authority when asked. This should include regular dust soiling checks of surfaces such as street furniture, cars and window sills within 100 m of site boundary, with cleaning to be provided if necessary;

• Impose and signpost a maximum-speed-limit of 15 mph on surfaced and 10 mph on un-surfaced haul roads and work areas (if long haul routes are required these speeds may be increased with suitable additional control measures provided, subject to the approval of the nominated undertaker and with the agreement of the local authority, where appropriate);

• Implement a Travel Plan that supports and encourages sustainable travel (public transport, cycling, walking, and car-sharing);

• Re-vegetate earthworks and exposed areas/soil stockpiles to stabilise surfaces as soon as practicable;

• Use Hessian, mulches or tackifiers where it is not possible to re-vegetate or cover with topsoil, as soon as practicable;

• Only remove the cover in small areas during work and not all at once;

• Ensure bulk cement and other fine powder materials are delivered in enclosed tankers and stored in silos with suitable emission control systems to prevent escape of material and overfilling during delivery; and

• For smaller supplies of fine power materials ensure bags are sealed after use and stored appropriately to prevent dust.

2.15 Paragraphs 6.95 and 6.96 are deleted and replaced with the following:

As set out in chapter 5, the potential for cumulative effects with other consented developments in the area has been examined, including:

• The Cemex Langley Site north of North Park Road

• Cemex operations at Datchet Quarry

• Thorney Mill/Link Park Heathrow

• The M4 Smart Motorway

Each of these schemes is considered below. Due to the location of the projects and the best practice mitigation measures that will be employed for each scheme, dust is not considered to give rise to significant cumulative effects. The assessment of cumulative effects has therefore focussed on the possibility of cumulative process and traffic emissions. For the reasons set out below, it is concluded that there is no potential for significant cumulative effects with the above schemes.



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Cemex Langley

This scheme does not include any process emissions. The ES for the scheme explains that traffic for the scheme will access the motorway network via North Park (but only the western direction away from Richings Park), Sutton Lane and junction 5 of the M4. This affects the Slough AQMA around the M4 junction but does not affect residents in Richings Park.

During construction, there will be additional traffic flows through the Slough AQMA, but the impact on the AQMA will be negligible. The greatest impact of the additional traffic is at Disraeli Court, on the corner of Sutton Lane and London Road. This is receptor RR6 in this assessment. The Cemex Langley ES also includes receptors in this area – their receptors R8 and R9. The predicted ground level concentration due to the Cemex traffic at these receptors is 0.2 to 0.3 ug/m3. The impact of the proposed development is 0.4 ug/m3 and the predicted environmental concentration (PEC) is 37.39 ug/m3. Both impacts are negligible as they are 1% or less of the AQAL. Adding the Cemex Langley impact to the PEC gives a total concentration of 37.39 ug/m3, so there is still no exceedance predicted.

During operation, there will be no change to traffic flows as a result of the proposed development and impacts from process emissions are negligible, as illustrated in Figure 12 in Appendix D. The predicted process contribution for nitrogen dioxide at receptor R8 in this assessment, which is on London Road, is 0.08 ug/m3, which is less than the impact of construction traffic.

Cemex Datchet

The ES for Cemex at Datchet Quarry shows that traffic accesses the M4 via Riding Court Road and Ditton Road, joining the A4 north of junction 5 of the M4. Therefore, there is no overlap with traffic for the proposed development, nor with the process emissions.

Thorney Mill/Link Park Heathrow

For this scheme, some of the traffic travels along North Park and Richings Way, so there may be a cumulative impact with the process emissions from the proposed development. There is no overlap with traffic movements.

Receptor R17 for the proposed development is close to receptors in the Thorney Mill air quality assessment, and receptors R4 and R5 for Thorney Mill are along Richings Way. The predicted impact at these receptors for Thorney Mill is 0.07 – 0.24 ug/m3, with the maximum at receptor R4. This is a negligible impact.

The combined impact on annual nitrogen dioxide emissions at receptor R17 (Thorney Mill receptor R3) and Thorney Mills receptor R4 has been evaluated, for which there is no direct analogue. It is noted that this may be excessive given that the contribution of each development individually is negligible.

At R17, the background concentration is taken as 37.3 ug/m3 and the PEC is 37.5 ug/m3. The contribution of Thorney Mill at its receptor R3 is 0.16 ug/m3. Therefore, there is no exceedance of the AQAL.



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Along Richings Way, the background concentration is taken as 36.7 ug/m3. The contribution of the proposed development at Thorney Mill’s receptor R4 is around 0.35 ug/m3 while the contribution from Thorney Mill is 0.24 ug/m3. Hence, the total predicted concentration is 37.3 ug/m3 so there is no exceedance.

M4 Smart Motorway

The air quality impacts of the M4 Smart Motorway were considered very thoroughly as part of the DCO Application process in 2015/2016. South Bucks District Council participated in the process and agreed a statement of common ground with the Applicant, in which they agreed that “the requirements in the Application meet South Bucks District Council’s concerns in relation to Air Quality.”

The air quality assessment for the M4 Smart Motorway specifically considered the impact at Old Slade Lane, with receptor X20 (shown on drawing 6.13 in the DCO Application) located at the most southern house, which is the same location as receptor R1 in this air quality assessment. The detailed results for this receptor can be found on page 139 of Appendix 6.6 in the DCO Application. The change in concentration as a result of the scheme was predicted to be +0.3 μg/m3. This is not a significant increase. If this contribution is added to the background concentration and the contribution from the proposed development, the total concentration is predicted to be 30.49 μg/m3, which is still well below the air quality standard of 40 μg/m3.

Amendments to Chapter 7: Community and health effects


Amendments to Chapter 8: Cultural heritage

2.17 Paragraph 8.24 of the ES refers to: ‘The location of the site in the Colne Valley would have attracted early human activity in view of its rich marine resources and the immediate landscape would have continued to be attractive for prehistoric settlers with favourable geology for early farming.’ It should have referred to ‘riverine’ rather than ‘marine’ resources.

2.18 Paragraph 8.62 states as follows: ‘No effects on known or recorded archaeological assets are predicted for any of the development scenarios so no formal mitigation measures are required’. Additional text has been added as follows:

However, it is recognised that there is an opportunity to apply best practice techniques to apply pre-construction geotechnical investigation upon areas of the site not previously investigated. This commitment will provide a clear indication of survival of archaeological deposits and former land surfaces and it will be clear whether particular development components and their varying impact will lead to negative effect. It is considered that this is unlikely as these archaeological horizons have previously been identified as deeply buried (over 5-metres below present ground level) prehistoric horizons.

2.19 An additional paragraph has been added at 8.63:



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The applicant will engage the services of a suitably qualified and experienced archaeologist to produce a Written Scheme of Investigation (WSI) for the future assessment of borehole information obtained from the pre-construction geotechnical investigation. The applicant will ensure the WSI is produced in accordance with best practice and endorsed by Berkshire Archaeology, the advisor to the local planning authority.

Amendments to Chapter 9: Ground conditions and the water environment


Amendments to Chapter 10: Landscape, townscape and visual effects


Amendments to Chapter 11: Natural heritage

2.22 The following sentence has been added to paragraph 11.17 to reflect the submission of an updated reptile report:

A further survey of the main site was undertaken in September 2019. Details of the refugia numbers and densities applied are set out in the updated Technical Appendix J5.

2.23 In line with the Otter Survey (see Appendix 6 to the ES Addendum) paragraph 11.24 has been amended to refer to the correct survey timescales as follows:

An otter (Lutra lutra) survey (in accordance with Chanin, 2003a and the DMRB) was undertaken between September 2017 and November 2017 September 2018 of any suitable habitat within the replacement site and within 100m of it.

2.24 Paragraph 11.49 has been updated to reflect the results of the recent reptile survey (see Appendix 5 to this ES Addendum) as follows:

The presence / likely absence survey in the wider area recorded the presence of two species, grass snake (Natrix natrix) and slow worm (see technical appendix J). The population class assessment survey recorded a good population of slow worms in the area around Old Slade Lake and Colnbrook West. A low population of grass snake and a good population of slow worm were recorded to the north of the sludge dewatering centre, on habitats similar to and connected to the replacement site itself. Reptiles are considered to be of local importance (low sensitivity). Recent reptile survey work undertaken on the main site has revealed that no reptiles were present.

2.25 Paragraph 11.58 has been updated in line with the updated text of the Ecological Impact Assessment ((see Appendix 4 to this ES Addendum):

A non-breeding non-natal otter holt was found along the Colne Brook, (technical appendix J) and otters have been recorded in the wider area at Orlitts Lake, Colnbrook West Lake and Old Slade Lake. Non-breeding Non-natal holts are below the LWS criteria for Berkshire, therefore in this context otters are considered to be of local value (low sensitivity).



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2.26 Paragraphs 11.79 and 11.80 have been replaced with text as follows:

The September 2019 reptile survey work found no reptiles at the main site and therefore there will be no construction-related effects on reptiles. The majority of the land within the red line boundary, including the temporary construction compound and much of the access road to the A4, is on short grassland and is unlikely to support reptiles, therefore there will be no effects on reptiles during construction in these areas either.

2.27 Following the results of the recent reptile survey, paragraph 11.101 has now been deleted as there are no reptiles on site.

Amendments to Chapter 12: Summary tables

2.28 Table 12.2: Secondary mitigation measures, has been updated to include reference to the additional dust mitigation measures highlighted in the air quality chapter and Technical Appendix D, the preparation of a WSI for the future assessment of borehole information obtained from the pre-construction geotechnical investigation and removal of reference to reptile mitigation. See Appendix 1 to this ES Addendum for a copy of the updated Table 12.2.

Amendments to Glossary

2.29 No changes to the glossary are necessary.

Amendments to Technical Appendix A: EIA scoping

2.30 No changes to Technical Appendix A: EIA scoping are necessary.

Amendments to Technical Appendix B: Competent experts involved in the preparation of the ES

2.31 No changes to Technical Appendix B: Competent experts involved in the preparation of the ES are necessary.

Amendments to Technical Appendix C: Framework construction environmental management plan

2.32 No changes to Technical Appendix C: Framework construction environmental management plan are necessary.

Amendments to Technical Appendix D: Air quality

2.33 In response to feedback from SBC during the consultation period, the following amendments have been made to Technical Appendix D: Air quality.

2.34 Table 25: Summary of baseline concentrations corrects the measurement unit for dioxins and furans to fg TEQ/m3.

2.35 The following additional information is provided under section 6.2: Emission limits at the end of the section:



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Slough BC asked for further evidence that the reduced emission limit for oxides of nitrogen can be achieved in practice. The Applicant notes that relatively few plants in Europe are required to achieve an emission limit of 100 mg/Nm3 using SNCR. Existing plants generally have an emission limit of 200 mg/Nm3 with SNCR or 70 mg/Nm3 with SCR. The applicant can provide the following evidence to support the assertion that the proposed emission limits can be achieved on a consistent basis.

As part of the data gathering exercise to support the new Waste Incineration BREF, emissions data was collected from a variety of energy-from-waste plants across Europe. The data is for plants operating in 2015. This data is published in Annex 8.6 of the draft final WI BREF. Figure 8.15, reproduced below, shows the plants with the lowest NOx emissions (Figures 8.16 and 8.17 show the plants with higher emissions and are therefore not attached). The figure shows, for each plant, the annual average (blue diamond), the highest daily average excluding other than normal operating conditions (“daily fine”, pink circles) and the highest daily average except for maintenance and when the plant is burning support fuel (“daily base”, green triangle). These are explained on page 149 of the draft final WI BREF. Of these, the most relevant is the “daily fine” as this shows the emissions data which are achieved on a consistent basis.

The figure shows that there are at least 9 lines across Europe which achieved annual average emissions of NOx below 100 mg/Nm3 with SNCR only (DE48-1, DE47-1R, DE48-2, DE47-2R, FR019R, DK02-2, IT1-2, IT1-1, FR087-3R) and that for seven of these lines, this emission level was achieved on a daily basis, excluding other than normal operating conditions (the “daily fine” concentration). The seven lines range from 7.5 tph to 320,000 tpa and are considered to be representative of the proposed capacity.



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The Applicant also notes that the range of achieved emissions with SNCR is shown in the final draft WI BREF as 80-180 mg/Nm3 (Table 4.31 on page 397). Therefore, the proposed emission limit falls within this range.

The Applicant’s consultant is involved with a number of different proposed energy-from-waste plants and has received proposals from a number of leading technology suppliers. While we cannot provide this information directly, we can confirm that a number of these companies are happy to guarantee a daily emission limit of 100 mg/Nm3 with ammonia slip of 10 mg/Nm3, and we note that these companies would be subject to significant financial penalties if these guarantees are not achieved.

The Applicant considers that this evidence shows that the proposed emission limits have been achieved at a number of European plants, that they are consistent with the draft WI BREF and that companies which are developing, selling and guaranteeing this technology are confident that they can be achieved.

2.36 Under section 6.5.3: Buildings, the following additional information has been provided at the end of the section:

Slough BC asked for further justification for the approach to the building inputs. A building interrupts a laminar airflow and the resulting effect is a recirculating flow region on the leeward side of the building and a turbulent wake, as set out in the following figure. Emissions from the stack can be entrained into this region causing elevated ground level concentrations.

The geometry of the building proposed (like the existing building) is such that the air would flow over the building and the building wake would be smaller than if the building was a simple box like structure. This is illustrated in the following figure.

Therefore, treating the building as a block with a height of 42m would significantly over estimate the effect of the building when winds blow along the length of the building, given the roofline geometry which minimises the building wake effect. Treating the building as a 34m high block would be more representative.



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If the wind were to be blowing across the building, then the recirculation zone would vary along the length of the building. By representing the building at 34m, which is taller than the building height close to the stack of around 27m, the modelling will overestimate the recirculation zone near to the stack. This is therefore conservative. If the building height in the model were increased to 42m, then the degree of overestimation would increase still further.

2.37 Section 6.7.2: Further assessment – annual mean nitrogen dioxide. The following new sentence is added at the end of the first paragraph:

The new facilities will not operate at the same time as the existing facilities.

2.38 Section 6.7.8 Further assessment – annual mean cadmium. The first paragraph is revised to add reference to ‘or 7μg/Nm3’ as follows:

As previously noted, this assessment has initially used a screening assumption that cadmium is released from the Proposed Development at the combined emission limit for cadmium and thallium. However, monitoring from waste incineration facilities has indicated that concentrations of cadmium are typically approximately 35% of the ELV, or 7μg/Nm3. Therefore, this assessment has considered the impact of cadmium under the following 3 scenarios:

2.39 The same section also includes the following additional text at the end of the section:

Slough Borough Council asked for further evidence that the typical level of cadmium could be achieved. The emissions of cadmium and thallium from European EfW plants are shown in the final draft Waste Incineration (WI) BREF. Figure 3.33 from page 180 of the final draft WI BREF is reproduced below and summarises emissions data from 197 municipal waste-to-energy lines. Only six of the reference lines had emissions which exceeded the BAT-AEL of 0.02 mg/Nm3. This was the evidence used to set the BAT-AEL and clearly shows that it can be consistently achieved.



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The detailed results presented in figures 8.130, 8.131 and 8.132 in the final draft WI BREF include 17 UK plants, all of which are equipped with bag filters, like the Facility. The average recorded concentration was 1.6 μg/Nm3, the highest recorded concentration of cadmium and thallium was 14 μg/Nm3 and only three lines recorded concentrations higher than 10 μg/Nm3.

In addition, we have reviewed the emissions of cadmium from the current Lakeside facility. The emissions from each line are measured every six months. The twelve most recent measurements were between 0.20 μg/Nm3 and 0.81 μg/Nm3, with an average of 0.42 μg/Nm3. The waste for the new Facility will be the same as that for the existing facility, so it is reasonable to assume that the concentration of cadmium would also be similar as this is dependent on the fuel composition.

Therefore, it can clearly be demonstrated that the facility will be able to achieve the BAT AEL and emissions are highly likely to be significantly below the limit. The use of 7 μg/Nm3 remains conservative as the average value monitored across the UK was only 1.6 μg/Nm3 or 8% of the BAT AEL of 0.02 mg/Nm3 and the average value monitored at the current facility was only 0.42 μg/Nm3, or 2% of the BAT AEL.

2.40 Table 56: Further analysis – annual mean PaHs, corrected the PC and PEC concentration references in the heading row to: pg/m3.

2.41 Section 6.7.12.1: Long term results, now includes the following paragraphs for clarification at the end of the section:

Slough Borough Council asked for clarification that use of the average chromium VI discharge concentration is appropriate. The concentration of chromium (VI) in the emissions to atmosphere is not measured at the current facility, or at any EfW



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facilities, as the concentration is too low to be measured. The specification of chromium into the different species is measured in the APC residues. The analysis presented in the EA’s metal guidance uses the measured concentration of total chromium and the fraction of chromium (VI) in the APC residues to calculate a concentration of chromium (VI).

The twelve most recent measurements of chromium at the existing plant were between 0.006 mg/Nm3 and 0.0249 μg/Nm3, with an average of 0.0117 μg/Nm3. The EA metals guidance has an average measured concentration of 0.0084 mg/Nm3 and a maximum concentration of 0.092 mg/Nm3. This confirms that emissions from the current facility are more similar to the average across the UK rather than the peak.

The waste for the new Facility will be the same as that for the existing facility, so it is reasonable to assume that the concentration of chromium would also be similar as this is dependent on the fuel composition. Therefore, it is appropriate to use the mean chromium (VI) data for the purpose of the assessment to represent likely impacts from the new Facility.

"#&"! Section 6.7.12.3 has been renumbered as section 6.7.13 “Impact at ecological receptors” and updated with the following text in order to clarify the assessment approach at the front of the section:

6.7.13.1 Calculation methodology – nitrogen deposition

The impact of deposition has been assessed using the methodology detailed within the Habitats Directive AQTAG 6 (March 2014). The steps to this method are as follows.

1." Determine the annual mean ground level concentrations of nitrogen dioxide and ammonia at each site.

2." Calculate the dry deposition flux (μg/m2/s) at each site by multiplying the annual mean ground level concentration by the relevant deposition velocity presented in Table 61.

3." Convert the dry deposition flux into units of kgN/ha/yr using the conversion factors presented in Table 61.

4." Compare this result to the nitrogen deposition Critical Load.

Table 61: Deposition Factor

PollutantDeposition Velocity (m/s) Conversion Factor

(μg/m2/s to kg/ha/year) Grassland Woodland

Nitrogen dioxide 0.0015 0.003 96.0

Sulphur dioxide 0.0120 0.024 157.7

Ammonia 0.0200 0.030 259.7

Hydrogen chloride 0.0250 0.060 306.7

6.7.13.2 Calculation methodology - acidification



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Deposition of nitrogen, sulphur, hydrogen chloride and ammonia can cause acidification and should be taken into consideration when assessing the impact of the Proposed Development.

The steps to determine the acid deposition flux are as follows.

1. Determine the dry deposition rate in kg/ha/yr of nitrogen, sulphur, hydrogen chloride and ammonia using the methodology outlined above.

2. Apply the conversion factor for N outlined in Table 61 to the nitrogen and ammonia deposition rate in kg/ha/year to determine the total keq N/ha/year.

3. Apply the conversion factor for S to the sulphur deposition rate in kg/ha/year to determine the total keq S/ha/year.

4. Apply the conversion factor for HCl to the hydrogen chloride deposition rate in kg/ha/year to determine the dry keq Cl/ha/year.

5. Determine the wet deposition rate of HCl in kg/ha/yr by multiplying the model output by the factors presented in Table 62.

6. Apply the conversion factor for HCl to the hydrogen chloride deposition rate in kg/ha/year to determine the wet keq Cl/ha/year.

7. Add the contribution from S to HCl dry and wet and treat this sum as the total contribution from S.

8. Plot the results against the Critical Load functions.

Table 62: Conversion Factors

Pollutant Conversion Factor (kg/ha/year to keq/ha/year) Nitrogen Divide by 14 Sulphur Divide by 16 Hydrogen chloride Divide by 35.5

The March 2014 version of the AQTAG 6 document states that, for installations with an HCl emission, the PC of HCl, in addition to S and N, should be considered in the acidity Critical Load assessment. The H+ from HCl should be added to the S contribution (and treated as S in the APIS tool). This should include the contribution of HCl from wet deposition.

Consultation with AQMAU confirmed that the maximum of the wet or dry deposition rate for HCl should be included in the calculation. For the purpose of this analysis it has been assumed that wet deposition of HCl is double dry deposition.

The contribution from the Proposed Development has been calculated using the APIS formula:

Where PEC N Deposition < CLminN:

PC as % of CL function = PC S deposition / CLmaxS



17

Where PEC N Deposition > CLminN:

PC as % of CL function = (PC S + N deposition) / CLmaxN

2.43 Section numbers all alter from 6.7.13.3 onwards due to the addition of the above information.

2.44 A new section 6.7.14: Additional assessment of Windsor Forest and Great Park is now included as follows:

Windsor Park and Great Park SAC is located 7km to the south-west of the proposed development. The closest point in the site to the proposed development was identified and used in the assessment. However, following consultations with Slough BC after the application was submitted, it has been accepted that the SAC, although distant from the proposed development, is large enough that it is appropriate to consider more than one point.

The modelling has been re-run with a modified grid extended to cover the SAC with the same spatial resolution as the standard modelling domain. The maximum annual mean ammonia concentration across the SAC, as a percentage of the Critical Level for lichen sensitive communities, has been calculated as 1.1%. This occurs in the eastern corner of the SAC for some, but not all, years of weather data. However, this does not account for the contribution already been made by the existing EfW and HTI plants, which will be decommissioned if and when the new facilities are operational. To determine the net change in impact, for each point the maximum predicted impact at the same point from the existing EfW and HTI has been subtracted from the impact of the proposed development. This has shown that at any point in the SAC the maximum net impact is 0.55% of the Critical Level for lichen sensitive communities.

A plot file showing the maximum net change in impact as a percentage of the Critical Level for lichen sensitive communities is provided in Figure 23. As shown, the net change in impact is well below 1% across the SAC. Therefore, the impact of ammonia emissions can be screened out as insignificant at Windsor Park and Great Park SAC.

2.45 Section 7.1 Operational phase, now includes the following paragraph at the end of the section:

The effect of reducing the building height was considered at an earlier stage of the project. This analysis set out that it may be possible to lower the entire building by up to 5m by additional excavation, but it would be necessary to make more fundamental changes to reduce the height any further. In addition, consideration was given to underground services and structures such as the new Heathrow rail link, as well as the neighbouring Thames Water works which might make excavations impractical. The analysis showed that lowering the building by 5m would reduce the peak impact, which occurs in a field to the north of the M25 where there are no residential receptors. When considering the distribution of emissions, the ground level impacts would be slightly lower at the areas of relevant exposure, but the overall conclusions of the assessment would be the same.



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2.46 Section 7.2 Construction phase now includes the following additional information at the end of the section:

However, the Applicant can confirm that it will implement the highly recommended measures in the IAQM guidance if appropriate. In addition to those above, these include:







• Fully enclose site or specific operations where there is a high potential for dust production and the site is actives for an extensive period;









19
















2.47 Section 9 Cumulative effects is replaced with the following text:

A number of local projects have been identified which may have cumulative effects with the Proposed Development. These are:



20

1. The Cemex Langley Site north of North Park Road;

2. Cemex operations at Datchet Quarry;

3. Thorney Mill/Link Park Heathrow;

4. The M4 Smart Motorway; and

5. The M25 junction 10/A3 Wisley interchange improvement.

Each of these schemes is considered below. For the reasons set out below, it is concluded that there is no potential for significant cumulative effects with the above schemes.

9.1 Cemex Langley

This scheme does not include any process emissions.

The Environmental Statement for the scheme explains that traffic for the scheme will access the motorway network via North Park (but only the western direction away from Richings Park), Sutton Lane and junction 5 of the M4. This affects the Slough AQMA around the M4 junction but doesn’t affect residents in Richings Park. The impacts of the Proposed Development on the Slough AQMA are considered in the Environment Statement.

During construction, there will be additional traffic flows through the Slough AQMA but the impact on the AQMA will be negligible. The greatest impact of the additional traffic is at Disraeli Court, on the corner of Sutton Lane and London Road. This is receptor RR6 in this assessment. The Cemex Langley ES also includes receptors in this area – their receptors R8 and R9. The predicted ground level concentration due to the Cemex traffic at these receptors is 0.2 to 0.3 ug/m3. The impact of the Proposed Development is 0.4 ug/m3 and the predicted environmental concentration (PEC) is 37.39 ug/m3. Both impacts are negligible as they are 1% or less of the AQAL. Adding the Cemex Langley impact to the PEC gives a total concentration of 37.39 ug/m3, so there is still no exceedance predicted.

During operation, there will be no change to traffic flows as a result of the Proposed Development and impacts from process emissions are negligible, as illustrated in Figure 12 in Appendix D. The predicted process contribution for nitrogen dioxide at receptor R8 in this assessment, which is on London Road, is 0.08 ug/m3, which is less than the impact of construction traffic.

9.2 Cemex Datchet

The Environmental Statement for Cemex at Datchet Quarry shows that traffic accesses the M4 via Riding Court Road and Ditton Road, joining the A4 north of junction 5 of the M4. Therefore, there is no overlap with traffic for the Proposed Development, nor with the process emissions.

9.3 Thorney Mill/Link Park Heathrow

For this scheme, some of the traffic travels along North Park and Richings Way, so there may be a cumulative impact with the process emissions from the Proposed Development. There is no overlap with traffic movements.



21

Receptor R17 for the Proposed Development is close to receptors in the Thorney Mill air quality assessment, and receptors R4 and R5 for Thorney Mill are along Richings Way. The predicted impact at these receptors for Thorney Mill is 0.07 – 0.24 ug/m3, with the maximum at receptor R4. This is a negligible impact.

We have evaluated the combined impact on annual nitrogen dioxide emissions at our receptor R17 (Thorney Mill receptor R3) and Thorney Mills receptor R4, for which there is no direct analogue. We note that this may be excessive given that the contributions of each development individually is negligible.

At R17, the background concentration is taken as 37.3 ug/m3 (see section 6.7.2 above) and the PEC is 37.5 ug/m3. The contribution of Thorney Mill at its receptor R3 is 0.16 ug/m3. Therefore, there is no exceedance of the AQAL.

Along Richings Way, the background concentration is taken as 36.7 ug/m3. The contribution of the Proposed Development at Thorney Mill’s receptor R4 is around 0.35 ug/m3 while the contribution from Thorney Mill is 0.24 ug/m3. Hence, the total predicted concentration is 37.3 ug/m3 so there is no exceedance.

9.4 M4 Smart Motorway

The air quality impacts of the M4 Smart Motorway were considered very thoroughly as part of the DCO Application process in 2015/2016. South Bucks District Council participated in the process and agreed a statement of common ground with the Applicant, in which they agreed that “the requirements in the Application meet South Bucks District Council’s concerns in relation to Air Quality.”

The air quality assessment for the M4 Smart Motorway specifically considered the impact at Old Slade Lane, with receptor X20 (shown on drawing 6.13 in the DCO Application) located at the most southern house, which is the same location as receptor R1 in this air quality assessment. The detailed results for this receptor can be found on page 139 of Appendix 6.6 in the DCO Application. The change in concentration as a result of the scheme was predicted to be +0.3 μg/m3. This is not a significant increase. If this contribution is added to the background concentration and the contribution from the Proposed Development, the total concentration is predicted to be 30.49 μg/m3, which is still well below the air quality standard of 40 μg/m3.

9.5 M25 Junction 10

This scheme is located approximately 20 km to the south of the Proposed Development (as the crow flies). Therefore, there is little risk of cumulative impacts with the Proposed Development.

2.48 Appendix A: Figures - as noted above a new Figure 23: Ammonia annual average, has been added to the Air Quality Technical Appendix and is included in the complete amended version in Appendix 2 to this ES Addendum.

2.49 Appendix C: APIS critical loads, Table 69: Acid deposition critical loads, table header, is revised to clarify that the minimum critical load function in keq/ha/yr applies to each habitat present.



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2.50 Appendix D: Deposition analysis at ecological sites, Table 71, Deposition calculation – grassland, a note is added as follows:

This table presents the results for deposition over grassland for all sites, although for some sites the dominant deposition velocity class is Woodland.

Amendments to Technical Appendix E: Health risk assessment

2.51 Section 7.1.3.1 Nickel ingestion now includes the following additional paragraphs at the end of the section:

The twelve most recent measurements from the existing facilities have a range of 0.004 to 0.0333 mg/Nm3 and an average of 0.0086 mg/Nm3, or 2.9% of the BAT-AEL. This suggests that the existing facilities operate below the average levels of other UK facilities and supports the use of 5% of the BAT-AEL as a conservative but realistic assumption.

If it is assumed instead that the plant operates at the average monitored level from the existing facilities, which is reasonable as this is a long term health impact and the waste will be the same, the contribution of the Proposed Development would be 0.34% of the TDI, which is not significant.

Amendments to Technical Appendix F: Health impact assessment

2.52 No changes to Technical Appendix F: Health impact assessment are necessary.

Amendments to Technical Appendix G: Cultural heritage

2.53 No changes to Technical Appendix G: Cultural heritage are necessary.

Amendments to Technical Appendix H: Ground conditions and the water environment

2.54 No changes to Technical Appendix H: Ground conditions and the water environment are necessary.

Amendments to Technical Appendix I: Landscape, townscape and visual effects

2.55 No changes to Technical Appendix J: Landscape, townscape and visual effects are necessary.

Amendments to Technical Appendix J: Natural heritage

Appendix J:5 – Updated reptile report

2.56 At the time of the original submission (June 2019) access had not been granted to survey the main footprint of the proposed new development and therefore the results from surveys of the adjacent land were used as a proxy. Post-submission, the applicant’s ecologist was granted access and a reptile survey was undertaken in September 2019 to inform the pre-construction mitigation strategy.



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2.57 The September 2019 survey work found no reptiles at the main site and therefore no further mitigation was considered necessary. The majority of the land within the red line boundary, including the temporary construction compound and much of the access road to the A4, is on short grassland unlikely to support reptiles and needs no mitigation.

2.58 See Appendix 5 to this ES Addendum for the updated reptile report.

New Appendix J:9 – Otter survey

2.59 It is important to note that data on the presence of otters, that followed standard practice guidance, was collected for the Heathrow Airport Ltd expansion plans between September 2017 and September 2018 and was used to inform the Lakeside ES. The results of the otter surveys were included within the Ecological Impact Assessment (EcIA) which formed ES Technical Appendix J:0. A specific otter survey report was not submitted in June with the rest of the application documents, however, at the subsequent request of SBC, one has now been prepared, see Appendix 6 of this ES Addendum. A confidential plan showing the location of local otter activity has been submitted separately to SBC as otters can suffer from persecution.

2.60 The otter report, which now forms Technical Appendix J:9 (or Appendix 6 to this ES Addendum) includes details of the survey methodology and survey results. The findings of the survey, as they were used to inform the ES that was submitted in June, clearly do not alter any of the conclusions of the ES.

Appendix J:0 – Updated Ecological Impact Assessment

2.61 Technical Appendix J:0 has been updated in light of the updated reptile report and the new otter report (J:9), please see Appendix 4 of this ES Addendum. Minor formatting amends have not been highlighted here, only the key text changes, as follows.

2.62 Paragraph J.5.19 has been amended as follows to reflect the updated reptile survey results:

The areas surveyed for reptiles and the results of the survey are shown in Appendix J.5 Figure 3. Due to access restrictions the site could not be surveyed prior to 2019. Reptiles have been recorded in habitats linked to the site in 2017-18. Approximately 2 ha of habitat suitable for reptiles exists within the Proposed Development, however, surveys that took place on site in 2019 revealed that no reptiles were present.

2.63 Paragraph J.5.25 has been updated to reflect the results of the otter survey as follows:

The results of the otter survey are shown in a confidential Figure 3.1 from Appendix J.9. Evidence of otters was recorded along the Colne Brook and around the lakes making up Old Slade Lake LWS. This included spraints, footprints, laying up points and non-natal holts. The nearest holt was approximately 650 m upstream of the site.



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2.64 Table J.7: Likely effects, Zols and justification for scoped in ecological features, has been amended to reflect the updated reptile report and the new otter report. Reference to reptiles has been deleted from the table and reference to otters has been amended to read:

Non-natal holts were found along the Colne Brook, into which the drainage discharges. Non-natal holts are below the LWS criteria for Berkshire (BMERC & TVERC 2009) therefore otters are considered of local value in this context.

2.65 Section J.12: Assessment of effects: Reptiles, has been deleted in line with recent survey work that demonstrates there are no reptiles on site.

2.66 Section J.14: Assessment of effects: otters, paragraph J.14.3 has been updated to include reference to ‘laying up places’.

2.67 In line with recent survey findings, reference to reptiles has been deleted from Table J.10: Summary of significance of adverse effects.

2.68 In line with recent survey findings, reference to reptiles has been deleted from section J.17: Consideration of additional mitigation or compensation.

2.69 The second sentence of paragraph J.17.5 has been updated to read:

Mitigation will require pre-commencement surveys to evaluate an up-to-date status of the territory, e.g. have any natal holts been built.

2.70 In line with recent survey findings, reference to reptiles has been removed from section J.18: Conclusions of significance evaluation and section J.19: Implementation of environmental measures.

2.71 Table J.10.1: Importance of ecological features, has been updated to reflect the recent reptile survey findings and now refers to:

Reptiles – negligible importance as no reptiles were found within the site; populations were found nearby. Reptiles scoped out of the assessment.

2.72 The same table has also been amended to refer to: ‘non-natal’ otter holts.

2.73 In line with recent survey findings, reference to reptiles has been removed from Table J.10.2: Scoping of ecological features of local or above importance and those receiving legal protection.

2.74 In line with recent survey findings, Table J.11.3: Summary of the assessment of effects on reptiles due to land take has been deleted.

2.75 Table J.11.6: Summary of the assessment of disturbance to otters due to construction of drainage works has been updated to refer to ‘non-natal holts’.



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3.0 Appendices

Appendix 1 Updated ES Chapter 12: Summary tables

Appendix 2 Amended Technical Appendix D: Air quality

Appendix 3 Amended Technical Appendix E: Health Risk Assessment

Appendix 4 Amended Technical Appendix J0 Ecological Impact Assessment

Appendix 5 Amended Technical Appendix J5 Supplementary Reptile Survey

Appendix 6 New Technical Appendix J9 Otter Survey



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Appendix 1 Updated ES Chapter 12: Summary tables

Replacement of Lakeside EfW and HTI Facilities Lakeside EfW Ltd ES Chapter 12: Summary tables


12-1

Deleted: June

12 Summary tables

Introduction

12.1 This chapter summarises the findings of the EIA. A comprehensive assessment has been undertaken of the potential environmental effects arising from the proposed development. Where possible, measures have been incorporated into the development proposals to prevent or reduce the potential for adverse environmental effects. These primary mitigation measures are an integral part of the design and were taken into account in the impact assessments. The primary mitigation measures are summarised in table 12.1.

12.2 Measures to help mitigate adverse effects identified during the assessment process have also been proposed for some of the environmental topics. These secondary mitigation measures are summarised in table 12.2.

12.3 The residual effects, i.e. the significant effects remaining after mitigation, are summarised in table 12.3. The measures envisaged for monitoring adverse effects are set out in table 12.4.



12-2

Deleted: June

Table 12.1: Primary mitigation measures

Design description / detail / operational measure Environmental issue addressed / avoided / reduced or environmental benefit

A north - south orientation for the EfW plant minimises the outline of the main building when viewed from Richings Park to the north and Colnbrook to the south.

Reduced visual impact

The air-cooled condensers are located to the south west, so they are as far away as possible from the nearest existing properties.

Avoid noise impact

During design of the site layout and buildings consideration was given to the massing, height and scale of the different elements of the proposals in order to minimise impacts on the surrounding area. The buildings have been designed to occupy the smallest footprint in order to reduce, as far as is practicably possible, the building’s mass. The curved building / roof profile is also considered to be less obtrusive.


To avoid the visual impact of sun reflection a gentle curved roof profile has been adopted for the EfW building and the materials have been selected for the walls of the main process buildings that will absorb light, whilst also providing contrasting texture, natural weathering and visual softening to the scale of the building.


The EfW facilities will generate energy through the combustion of waste and effectively represent a low carbon energy source. The generation of low carbon energy can assist in the reduction of greenhouse gas emissions by displacing more carbon-intensive energy sources such as coal and natural gas. The existing EfW facility generates 40.5 MW of electricity, 37 MW of which is exported to the local grid. As well as ensuring that this low carbon energy generation will continue, the improvements in efficiency mean that the relocated EfW will increase electricity generation to approximately 44 MW and the export of electricity to 39 MW.

Generation low carbon energy

Steam created by the HTI process will be added to that of the EfW to improve the efficiency of the EfW process. Improving energy efficiency of the plant processes

Up to 20 MWth of heat from the EfW facility will be available for export to potential local heat users. Depending on the requirements of any heat users, either high pressure steam or hot water could be supplied. High pressure steam could be extracted from the turbine and piped directly to heat users. Alternatively, low pressure steam exiting the turbine (prior to the condensers) could pass through an onsite heat exchanger to heat up water for use in a heat network. The volume of steam extracted would vary depending on the heat load requirements of the heat users.

Opportunities for CHP

The south-facing roof of the EfW building will be fitted with 1,500m2 of photovoltaic panels which will make a further contribution to renewable energy generation at the site.

Renewable energy generation

The replacement EfW and HTI’s lighting design is based on the use of appropriate lighting to provide safe working conditions, whilst minimising light pollution and the visual impact on the local environment. The luminaires used will not

Reduced visual impact and effect on bats



12-3

Deleted: June


project light above the horizontal plane, ensuring that direct upward light pollution will be zero and will be glare rated to minimise the impact on both human and ecological receptors.

The education facility within the EfW building will include a multi-functional meeting room with capacity for accommodating up to 45 people and exhibition space. The education centre will provide the opportunity to promote the importance of good waste management. Grundon Waste Management and Viridor have a history of supporting education and research projects and specific provision will be made for the presentation of the facilities and operations as a resource for local schools and educational establishments.

Education opportunities – improved awareness and understanding of waste management issues

Twenty-four secure spaces for bicycles and up to five motor cycle spaces will be provided adjacent to the EfW building for use by staff and visitors.

Opportunities for sustainable travel encouraged

Of the 120 staff and visitor parking spaces 10% will be provided with electric charging points to encourage the uptake of electric vehicles. There is the ability to increase provision should there be greater demand in the future.

Opportunities for air quality improvement

Surface water run-off from the site will be collected via rainwater down pipes, linear drainage channels and a number of external gullies, passed through oil interceptors and silt traps and then discharged via gravity into two below ground attenuation crates. Here the surface water will be attenuated, prior to discharge at greenfield run off rates, into the existing ditch to the north of the site boundary. A Class 1 by-pass separator is also proposed to minimise the pollution generated from vehicles accessing the site and the car parking area. The surface water drainage strategy also incorporates a 40% allowance for climate change which will ensure that the proposed development will not be at increased risk of flooding as a result of climate change.

Avoidance of surface water pollution and avoidance of flooding both on and off site

A rainwater harvesting tank will be installed to collect rainwater from building roof areas. This water will be used on site to support site activities / processes where appropriate.

Efficient use of water resource

Where practicable, waste waters generated from the processes will be re-used / recycled within the facilities. Process effluents and wash down waters collected from internal process areas will be collected in a process effluent system. The process effluents will then be collected within the process water drainage systems for re-use.

Water pollution avoidance

The proposed new access road is designed to include a 3m wide shared footway / cycleway Encourage sustainable travel to and from the site

While not screening the EfW and HTI buildings, the proposed planting will assist in breaking up the building mass and a degree of the ground level activity.


Water-efficient fittings will be specified for the staff facilities where possible. Efficient use of water resource

Incinerator bottom ash (IBA) from the EfW will be recycled and used to make sustainable aggregates suitable for construction and road projects. 100% of the IBA will be used for secondary aggregate production.

Reduced use of primary resources for aggregate production and avoided the need for landfill



12-4

Deleted: June


Air pollution control residues (APCr) from the EfW will be sent for treatment and used to create a lightweight, high quality, sustainable carbon-negative aggregate called Carbon8 Aggregate which is used to make carbon negative building blocks as well as in other construction material products. The APCr from the replacement facility will also be treated in this way. It is proposed where possible that the carbon negative blocks will be used in the construction of the replacement EfW facility, which will reduce the use of primary resources in the development.

Reduced use of primary resources for aggregate production

The APCr will be removed from the EfW in enclosed tankers thereby minimising the chance of spillage and dust emissions. Avoidance of water / ground / air pollution

The facilities will be built in accordance with the requirements of the prevailing Building Regulations in relation to target emission rates of CO2 and target fabric energy efficiency rates.

Reduce CO2 emissions

The combustion chamber of the EfW will use a moving grate to agitate the fuel bed and promote good burnout of the waste, ensuring a uniform heat release.

Maximise the efficiency of the process and energy generation

The combustion chamber of the EfW will be designed to achieve the requirements of the IED with respect to minimum temperatures (850°C). During normal operations the heat required for compliance with the IED will come entirely from the feedstock and no auxiliary fuel will be required.

Protection of health, avoidance of deterioration in local air quality and minimal use of additional fuel

Flue gases generated from the EfW combustion process will be cleaned before being released into the atmosphere to the appropriate standards required to protect human health and the environment. The flue gas treatment (FGT) systems will be designed to comply with the requirements of the Waste Incineration BAT reference document.

Protection of health and avoidance of deterioration in local air quality

The height of the stacks was determined following consultation with Heathrow Airport Limited, National Air Traffic Services and the Civil Aviation Authority, and extensive computer dispersion modelling of emissions and evaluation of the resulting dispersion plumes. Ground level concentrations of key pollutants will be kept within acceptable levels under all operating conditions, including emergency shutdowns.


Emissions from each of the EfW stacks will be continuously monitored using a continuous emission monitoring system (CEMS) for the following pollutants: particulates, sulphur dioxide, hydrogen chloride, carbon monoxide, nitrogen oxides, ammonia and VOC’s, expressed as total organic carbon. There will be two CEMS systems, one per waste incineration line and an installed back-up which can operate on both lines in the event of a CEMS failure. In addition, periodic monitoring will be undertaken of pollutants which are not able to be monitored continuously, such as hydrogen fluoride, metals and dioxins and furans.


All raw materials required for the EfW processes will be stored safely on site, in suitable tanks, silos or bunded areas as appropriate.

Avoidance of water and ground pollution

HTI waste will be stored within bins in designated secure storage areas until such time as it can be incinerated. Avoidance of water and ground pollution and protection of human health



12-5

Deleted: June


Once emptied, the HTI waste bins will be washed, disinfected and moved to a clean storage area ready for collection and reuse.

Re-use of bins / avoidance of waste generation

The combustion chamber of the HTI will be designed to achieve the requirements of the IED with respect to minimum temperatures (1,000-1,100°C). During normal operations the heat required for compliance with the IED will come entirely from the feedstock and no auxiliary fuel will be required.


Bottom ash from the HTI combustion chamber will fall from the end of the grate into a fully sealed system to prevent dust emissions.

Prevent dust emissions

Heat will be recovered from the HTI flue gases by means of a waste heat recovery boiler where the heat in the gases will be used to produce saturated steam. Provision will be made for heat to be exported to the EfW plant when it is in operation, to increase energy efficiency.

Heat recovery and increased energy efficiency

Flue gases generated from the HTI combustion process will be cleaned before being released into the atmosphere to the appropriate standards required to protect human health and the environment. The FGT system will be designed to comply with the requirements of the Waste Incineration BAT Reference document.


The HTI acid gas abatement system will utilise a dry system, using lime as a reagent to reduce concentrations of acid gases, such as SOx and HCl, in the flue gas stream. This abatement technology has the benefit that it does not produce a liquid effluent.

Avoidance of potential water / ground pollution

Emissions from the stack connected to the HTI will be continuously monitored using a CEMS for the same pollutants as the EfW emissions noted above. Flow rate and oxygen content will also be measured. There will be an installed back-up CEMS which can operate in the event of a CEMS failure.


All raw materials required for the HTI processes will be stored safely on site, in suitable tanks, silos or bunded areas as appropriate.


The EfW and HTI facilities will operate a detailed maintenance programme to ensure systems and equipment operate safely, effectively and reliably. The maintenance programmes for the two facilities will aim to maintain and improve overall efficiency, reduce emergency repairs, reduce unscheduled equipment shutdowns and the duration of such shutdowns, decrease process faults or reduced performance due to equipment problems and extend the useful life of equipment, repairing and adapting it where necessary.

Avoidance of pollution events through good site management

Spill procedures will be produced covering spillage of raw material inputs to the plant, ready use consumables and waste material outputs. Suitable equipment will be maintained on site (such as spill kits) in order to deal with the predicted scale of possible spillages of material. Staff will receive training in the use of the spill kits and will regularly practise as part of the normal operation of the facility. Under all circumstances, priority will be given to the potential environmental and health and




12-6

Deleted: June


safety impacts of spillages. Engineering controls will be employed where these would reduce the potential for spillage (or minimise the impact of spillage) e.g. bunded areas for fuel storage above ground.

Procedures and training will be in put in place for dealing with abnormal operating conditions. The EfW and HTI facilities will be designed to avoid the need for regular shutdowns but if any incident endangers or is likely to endanger personnel, or there is a risk of serious damage to the facilities, or there is a complete power failure, an emergency shutdown will be necessary (a standby generator will be present on site to support the safe shut down of the facilities at any time). A full set of procedures will be developed and implemented on site for an emergency shutdown. These will be published in an Emergency Plan. Appropriate drill and training exercises will be undertaken at regular intervals to ensure that all plant operatives are aware of and are competent to identify and respond to plant emergencies.

Efficient emergency shutdowns will avoid the potential for water, ground and air pollution. High standards of health and safety will be maintained for staff and visitors.

The EfW and HTI facilities will be equipped with comprehensive fire protection and detection systems which will comply with the requirements of the National Fire Protection Association’s recommended practice for fire protection for electricity generating plants and high voltage direct current converter stations (NFPA 850). Automatic fire alarm detection will be provided throughout specified areas as well as manual alarm break glass call points. An underground fire main will encircle the EfW and HTI plant facilities and will supply a number of fire hydrants and will spur off at strategic points to supply the water-based fire protection system. Within the HTI a water deluge system will also be employed.

Avoidance of pollution from fire water. Safety of staff and visitors is maintained.

Dust and odour control

• Combustion air will be drawn from above the waste pit so that odours and airborne dust are drawn from the bunker into the incineration line, thus preventing their escape to atmosphere.

• Odour will also be controlled by keeping the doors between the waste tipping area and the waste bunker closed when there are no waste deliveries occurring.

• Waste feed hoppers will be designed to ensure that emissions of dust and odours are minimised. • Potential emissions of dust and fumes from the bottom ash discharger will be minimised by the quenching process and

storage systems proposed. • Dust level checks will be carried out on a regular basis in operational areas of the EfW facility where high dust levels

may be present. This will provide an early warning of increasing dust levels, at which point action will be taken to reduce dust levels.

• Daily olfactory checks will be carried out around the perimeter of the site to check for odours. • In the event of a plant shutdown the doors to the bunker will be kept shut. If necessary fresh waste will be used to cap

older waste in order to minimise odours. A water-based deodoriser will also be hired if necessary to assist in odour management.

• Odour control in the HTI facility will be managed in a similar manner. Waste will be stored in secure, air-tight containers. Waste is then loaded onto the belt feeder and transferred to the furnace. The primary air for the

Protection of air quality and avoidance of odour and dust nuisance issues



12-7

Deleted: June


combustion process is taken from within the HTI building, providing a level of negative pressure and minimising the emissions of odour from the facility.

• Dust from the HTI bottom ash will be contained within a fully sealed system and the building will be under negative pressure.

• The site access road will be properly maintained and regular checks will be carried out on road conditions. Cleaning will be carried out as necessary. Vehicles will also be checked to ensure that they are clear of loose waste and that their loads are secure.

Noise control

• Most noisy plant items will be installed inside the EfW and HTI buildings rather than outside, and equipped with noise insulation if necessary.

• The air-cooled condensers have been designed to reduce noise and tonal components, and have been located to the south west of the site in order to have minimum noise impact on permanent local receptors.

• Doors will be kept closed when not in use to prevent noise egress. • A sound attenuator will be fitted to the exhaust of the EfW and HTI flue gas ID fans. • Waste vehicle movements at night will be limited. • Regular maintenance of plant items will ensure noise does not become a problem. • Mobile plant for the site will comply with the most up-to-date standards, including noise emissions. All mobile plant will

be operated and maintained in accordance with the manufacturers instructions. Mobile plant that does not comply with the agreed operating noise limits will be taken out of service until compliance is achieved.

• Noise level checks will be carried out on a regular basis in operational areas of the EfW and HTI facilities where high noise levels may be present. Early warning of increasing noise levels will result in a noise reduction or mitigation programme.

Prevention / avoidance of excessive noise emissions

Pest control

• Waste delivered for disposal will only be stored in the designated areas of the two buildings and any spillage of waste will be recovered in accordance with specific, time limited procedures. This will reduce the potential for feeding patterns to be established by vermin and therefore discourages infestation.

• The design of the waste bunker for the EfW will ensure that the bunker is watertight and this will prevent access to the contained waste by burrowing pests such as rats or squirrels.

• The waste bunker of the EfW will also be enclosed and under cover thereby reducing access to waste for birds and the tipping hall will be designed so as to eliminate roosting points for birds.

• Routine cleaning and good housekeeping will reduce the potential for the facilities to provide an attractive environment for vermin and this will be implemented through the maintenance programmes.

Avoidance of health / hygiene issues and general nuisance



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• In the event that pests are identified, an action plan will be developed to eliminate or reduce the potential for nuisance to neighbours.

• Daily visual checks will be undertaken of the waste storage areas and EfW tipping hall / waste bunker area, as well as the access road and the site generally. If pests are reported appropriate measures will be taken and pest control specialists utilised where necessary.

• The EfW tipping hall will be washed periodically and standard pest control methods will be implemented.

Litter control

• All vehicles carrying waste into or out of the EfW facility will be covered or sheeted, thereby ensuring the potential for litter to escape is minimised.

• The delivery and storage of all waste within buildings on site further minimises the potential for wind-blown litter to occur.

• A daily check will also be made to key areas of the site (e.g. the tipping hall) to identify any build-up of waste.

Avoidance of nuisance

The EfW and HTI will both operate 24 hours a day, seven days a week, though there will be periods of annual maintenance when waste processing is reduced. The majority of deliveries and collections will be received / made between 05:00 and 22:00 hours Mondays to Fridays and 06:00 and 14:00 hours on Saturdays.

Prevention of noisy activities during quieter periods of the day / night

Lakeside EfW Ltd will operate a good neighbour culture. Implementation of this culture includes the maintenance of a local liaison group which meets on a regular basis to discuss the operation of the plant and any potential issues or queries that those in the local community have. It provides a forum for community stakeholders to be informed and consulted regarding site operations and procedures. Liaison group members will continue to include locally elected representatives of the community as well as representatives of the Environment Agency, SBC and other stakeholders as appropriate.

Building good community relations with neighbours and good avenues of communication.

The existing EfW and HTI facilities at Lakeside Road are both currently certified to ISO14001 Environmental Management System with the BSI accreditation body. They also meet ISO9001 Quality Management and OHSAS18001 Occupational Health and Safety requirements. These quality management systems will be implemented at the replacement Lakeside EfW and HTI facilities, thus indicating Lakeside EfW Ltd’s aim to achieve the highest practical standards of quality, safety, occupational health and environmental control and performance at the replacement site.

Demonstrates ongoing commitment to protecting all facets of the local environment (air quality, noise, water, ground conditions, traffic, etc.).



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Table 12.2: Secondary mitigation measures

Potential effect Mitigation Air quality

Dust generation during construction

A range of measures will be implemented through the construction environmental management plan (CEMP). Appropriate measures for a site of this size include the following:

• Displaying the name and contact details of person(s) accountable for dust issues on the site boundary. This may be the environment manager / engineer or the site manager

• Displaying the head or regional office contact information • Recording all dust and air quality complaints, identifying the cause(s), taking appropriate measures to reduce emissions in a timely manner and

recording the measures taken • Making the complaints log available to Slough Borough Council when asked • Recording any exceptional incidents that cause dust and / or air emissions, either on or off site, and the action taken to resolve the situation in the

logbook • Planning the site layout so that machinery and dust-causing activities are located away from receptors, as far as possible • Keeping site fencing, barriers and scaffolding clean using wet methods • Removing materials that have the potential to produce dust from site as soon as possible, unless these are being re-used on site. If they are being

re-used on site, covering, seeding or fencing stockpiles to prevent wind whipping • Ensuring all vehicles switch off engines when stationary and there are no idling vehicles • Only using cutting, grinding or sawing equipment fitted, or in conjunction, with suitable dust suppression techniques, such as water sprays or local

extraction, e.g. suitable local exhaust ventilation systems • Ensuring an adequate water supply on the site for effective dust / particulate matter suppression / mitigation, using non-potable water where

possible and appropriate • Ensuring equipment is readily available on site to clean any dry spillages and cleaning up spillages as soon as reasonably practicable after the event

using wet cleaning methods • Prohibiting bonfires and burning of waste materials • Ensuring sand and other aggregates are stored in designated areas and are not allowed to dry out, unless this is required for a particular process,

in which case ensuring that appropriate additional control measures are in place • Ensuring vehicles entering and leaving the site are covered to prevent escape of materials during transport • Implementing a wheel wash system • Ensuring there is an adequate area of hard surfaced road between the wheel wash facility and the site exit

In addition to the above, the highly recommended measures in the IAQM guidance will be implemented if appropriate, including:

• Develop and implement a stakeholder communications plan that includes community engagement before work commences on site; Formatted: Indent: Left: 0 cm, Hanging: 0.63 cm, No bullets or numbering



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Potential effect Mitigation • Develop and implement a Dust Management Plan (DMP), which may include measures to control other emissions, approved by the

Local Authority. The level of detail will depend on the risk, and should include as a minimum the highly recommended measures in this document. The desirable measures should be included as appropriate for the site. In London additional measures may be required to ensure compliance with the Mayor of London’s guidance. The DMP may include monitoring of dust deposition, dust flux, real-time PM10 continuous monitoring and/or visual inspections;




• Erect solid screens or barriers around dusty activities or the site boundary that are at least as high as any stockpiles on site; • Fully enclose site or specific operations where there is a high potential for dust production and the site is actives for an extensive

period; • Avoid site runoff of water or mud; • Cover, seed or fence stockpiles to prevent wind whipping; • Ensure all on-road vehicles comply with the requirements of the London Low Emission Zone and the London NRMM standards,

where applicable; • Avoid the use of diesel or petrol powered generators and use mains electricity or battery powered equipment where practicable; • Produce a Construction Logistics Plan to manage the sustainable delivery of goods and materials; • Minimise drop heights from conveyors, loading shovels, hoppers and other loading or handling equipment and use fine water sprays

on such equipment wherever appropriate; • Use water-assisted dust sweeper(s) on the access and local roads, to remove, as necessary, any material tracked out of the site.

This may require the sweeper being continuously in use; • Avoid dry sweeping of large areas; • Inspect on-site haul routes for integrity and instigate necessary repairs to the surface as soon as reasonably practicable; • Install hard surfaced haul routes, which are regularly damped down with fixed or mobile sprinkler systems, or mobile water bowsers

and regularly cleaned; • Record all inspections of haul routes and any subsequent action in a site log book; and • Access gates to be located at least 10 m from receptors where possible.

Consideration will also be given to additional mitigation measures that are ‘desirable’ for a medium risk site:

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Potential effect Mitigation • Undertake daily on-site and off-site inspection, where receptors (including roads) are nearby, to monitor dust, record inspection

results, and make the log available to the local authority when asked. This should include regular dust soiling checks of surfaces such as street furniture, cars and window sills within 100 m of site boundary, with cleaning to be provided if necessary;


• Implement a Travel Plan that supports and encourages sustainable travel (public transport, cycling, walking, and car-sharing); • Re-vegetate earthworks and exposed areas/soil stockpiles to stabilise surfaces as soon as practicable; • Use Hessian, mulches or tackifiers where it is not possible to re-vegetate or cover with topsoil, as soon as practicable; • Only remove the cover in small areas during work and not all at once; • Ensure bulk cement and other fine powder materials are delivered in enclosed tankers and stored in silos with suitable emission

control systems to prevent escape of material and overfilling during delivery; and • For smaller supplies of fine power materials ensure bags are sealed after use and stored appropriately to prevent dust.

Community and health effects

No significant adverse effects predicted

In addition to the measures that are integral to the design and management of the plant, as set out in table 12.1, the HIA recommends the following mitigation measures are put in place:

• Establish a community complaints procedure during the construction phase that should be advertised widely, including the steps that will be taken once a complaint is received and the timescale in which a response and resolution can be expected

• Communicate information regarding construction activities throughout the construction period to the most local communities via channels such as a liaison group or a website

• Ensure the construction site is secure and not vulnerable to trespass through adequate fencing and, if appropriate, the use of security guards

• Implement a traffic management plan during construction, working closely with Slough Borough Council and the local highways authority to implement measures to deal with unusual traffic movements (such as large loads), consult with the council to evaluate the need to install traffic calming and control measures, and adopt procedures for liaison with the local emergency services in case of accidents

• Inform police and emergency services of any issues relating to site safety and access post-construction

• Encourage local employment and procurement during construction. If feasible and available, local suppliers should be used for goods and services. Jobs created during construction should also be advertised and made available in the local area initially

• Ensure open communication and sharing of information (as occurs for the existing facilities), including the display of emissions data on a website, in a form that is accessible and as close to real time as possible

• Implement a traffic management plan during operation Cultural heritage

Formatted: Indent: Left: 0 cm, Hanging: 0.63 cm, No bullets or numbering

Deleted: ¶ ... [1]



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Potential effect Mitigation

None required, however, the applicant will engage the services of a suitably qualified and experienced archaeologist to produce a Written Scheme of Investigation (WSI) for the future assessment of borehole information obtained from the pre-construction geotechnical investigation. The applicant will ensure the WSI is produced in accordance with best practice and endorsed by Berkshire Archaeology, the advisor to the local planning authority.’

Ground conditions and the water environment

Risks to human health and the water environment from existing contamination during and post-construction

The construction of the proposed development will be carried out in line with a CEMP, which will include best practice measures to manage potential effects associated with ground conditions and the water environment At the current level of knowledge on the site’s level of contamination, it is anticipated that standard personal protective equipment will be sufficient to provide protection to ground workers, although asbestos may need a specific protocol and equipment.

Construction works will be carried out in accordance with the Environment Agency’s (2007) Pollution Prevention Guideline 5: Works and Maintenance on or Near Water.

In addition to the CEMP, the following mitigation measures and further work will be undertaken in relation to ground conditions:

• Additional ground investigations and ongoing monitoring of groundwater quality and levels and ground gas concentrations • Incorporation of gas protection measures into the design of the buildings if the gas monitoring indicates that this is required • Development of a waste soils management strategy • Completion of a foundation works risk assessment, in accordance with Environment Agency standards, prior to construction to inform the potential

risks associated with foundation types under consideration or to identify mitigation measures that may be needed • Further interpretation of existing ground investigation information with regard to existing surface water and groundwater quality and leachate results • Minimisation of dewatering requirements by programming excavation works to be as short as possible. The need for an environmental permit to

undertake dewatering will be established and the necessary applications made as required. Coordination with Thames Water will be undertaken regarding dewatering activities should a potential risk to the deeper chalk aquifer be identified as part of the interpretation of ground investigation data and the environmental permit risk assessment process

• Development of a remediation strategy (if needed), together with validation and verification documentation as necessary • Development of a materials management strategy • Development of an asbestos management and health and safety plan • Confirmation from Slough Borough Council as to any restrictions or requirements at the site with respect to minerals extraction

Effects on surface water and groundwater quality from pollution during construction

The implementation of a CEMP during construction will include best practice measures to minimise potential effects on the water environment. These will include the preparation of a pollutants, water and sediment management protocol to inform construction works, which will set out measures such as the following:

• Minimise storage of hazardous chemicals on site and, where storage is necessary, use anti-pollution measures such as bunded trays or leak-proof containers

• Use designated refuelling sites, located away from open water • Any cleaning materials or chemicals used during the construction phase are not to be hazardous to the water environment • No storage of potentially contaminating materials in areas liable to water inundation

Formatted: Left



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Potential effect Mitigation • Use of electrical power, rather than diesel, where possible • Design of construction methods to minimise disturbance to, and mobilisation of, sediment • No washing down of plant while on site • Implementation of piling design with tight quality assurance / quality controls • Oil spill kits to be kept on site, and site staff trained in their use

Landscape, townscape and visual effects

Damage to trees in temporary construction compound during construction

It is proposed to fence off any mature trees within the proposed temporary construction compound during site preparation and construction activities in accordance with BS 5837: 2012

Natural heritage

Damage to trees in temporary construction compound during construction

It is proposed to fence off any mature trees within the proposed temporary construction compound during site preparation and construction activities in accordance with BS 5837: 2012

Risk to badgers present in the wider area during construction

Any excavations left open overnight will be covered where possible or a suitable means of escape for any animal that might fall in will be provided. Speed limits will be put in place and enforced along the proposed new access road. Drivers will be informed of the presence of badgers during the site induction.

Killing or injuring nesting birds during the construction phase

To ensure legal compliance, where possible vegetation removal will be undertaken outside of the breeding bird period (March to September, inclusive). Should clearance be required to be undertaken within this period, all work will be supervised by an appropriately qualified ecologist. In the event that nesting birds are present, all clearance of the relevant area will cease until chicks have fledged.

Killing, injuring or displacing reptiles during the construction phase

Pre-commencement reptile surveys covering the suitable habitats within the application boundary will be undertaken prior to any on-site works. If any reptiles are recorded, an appropriate receptor habitat will be found and improved (e.g. by allowing grass growth, opening up scrub areas and creating refugia from logs/rubble/soil piles) in order to increase the number of reptiles it can support. Reptiles will then be moved from the replacement facilities site to the receptor site.

The severing of a bat foraging route by the new access road (both the physical loss

A ‘hop-over’ vegetation bridge will be established at the start of the construction phase at the point at which the access road cuts through the existing scrub vegetation to provide a vegetation link for brown long-eared bats.

Formatted: Strikethrough



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Potential effect Mitigation of existing vegetation and lighting)

Disturbance of otter using Colne Brook during construction and any necessary maintenance of the drainage pipe

Prior to any works being undertaken in the vicinity of Colne Brook, an updated otter survey will be undertaken to check on the status of any territories. Specific standard mitigation measures will be proposed as necessary.



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Table 12.3: Significant residual effects

Significant residual effect Sensitivity of receptor

Magnitude of change

Nature Duration Degree of effect

Level of certainty

Air quality

No residual air quality effects Community and health effects

No residual community and health effects Cultural heritage

No residual cultural heritage effects

Ground conditions and the water environment

No residual ground condition or water environment effects Landscape, townscape and visual effects

Change to views from residents on Old Slade Lane, The Poynings (V2)

High / medium Medium Adverse Short and long term Moderate Reasonable

Change to views from PROW adjacent to site (V4) Medium Medium / large Adverse Short and long term Moderate Reasonable

Change to views from PROW north of M4 (V7) Medium Medium Adverse Short and long term Moderate Reasonable

Change to views from road users on Old Slade Road and The Poynings (V15)

Medium Medium / small Adverse Short and long term Moderate Reasonable

Natural heritage

Loss of broadleaved woodland on site Low Large Adverse Long term Moderate Absolute

Temporary severance of brown long-eared bat commuting route by site access road while ‘hop-over’ establishes

Low Medium Adverse Short term Moderate Reasonable



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Table 12.4: Proposed monitoring measures

Adverse effect Proposed monitoring measure Responsibility for monitoring

Generation of dust during construction (mitigated through CEMP)

Regular site inspections to monitor compliance with the dust management plan and recording of results

Contractor

Potential for ground and water pollution during site preparation / construction activities

Regular on-site monitoring of the works will be undertaken by an environmental specialist during the construction phase. This will include groundwater sampling, surface water inspections, surface water runoff management observations and materials handling observations. The detailed scope of the monitoring will be refined following detailed interpretation of the existing ground investigation data and data from any additional ground investigations undertaken.

Environmental specialist appointed by the contractor

Need to meet appropriate standards required to protect human health and the environment

Comprehensive monitoring of emissions will be undertaken at both the EfW and HTI facilities in line with their environmental permits. No additional operational mitigation or monitoring is required beyond that embedded into the design and required by legislation.

Environment Agency in line with the environmental permits

The severing of a bat foraging route by the new access road (both the physical loss of existing vegetation and lighting)

Bat activity in this area will need to be subject to ongoing monitoring to determine if the proposed ‘hop-over’ vegetation is well situated and sufficiently dense.

Contractor



27

Appendix 2 Amended Technical Appendix D: Air quality

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Lakeside EfW

04 December 2019 Air Quality Assessment

S2680-0030-0002SMO Page 2

Document approval Name Signature Position Date

Prepared by: Rhys Weir Environmental Scientist 23/05/2019

Checked by: Stuart Nock Environmental Consultant

23/05/2019

Approved by: Stephen Othen Technical Director 23/05/2019

Document revision record Revision no Date Details of revisions Prepared by Checked by

0 23/05/2019 First Issue RW SMO

1 31/05/2019 Final draft following Client review SMN SMO

2 13/06/2019 Updated traffic assessment SMN SMO

3 17/06/2019 Final SMN SMO

4 22/07/2019 Correction to Table 39 SMN JRS

5 26/11/2019 Additions during consultation process SMN SMO

© 2019 Fichtner Consulting Engineers. All rights reserved.

This document and its accompanying documents contain information which is confidential and is intended only for the use of Lakeside EfW. If you are not one of the intended recipients any disclosure, copying, distribution or action taken in reliance on the contents of the information is strictly prohibited.

Unless expressly agreed, any reproduction of material from this document must be requested and authorised in writing from Fichtner Consulting Engineers. Authorised reproduction of material must include all copyright and proprietary notices in the same form and manner as the original and must not be modified in any way. Acknowledgement of the source of the material must also be included in all references.

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Management Summary Lakeside EfW Ltd is a joint venture between Grundon Waste Management Limited and Viridor. It operates the existing Lakeside Road Energy from Waste (EfW) facility in Colnbrook, Slough. Grundon Waste Management is the sole owner / operator of the high temperature incinerator (HTI) adjoined to the EfW on Lakeside Road. Lakeside EfW Ltd, Grundon Waste Management Limited and Viridor are hereafter collectively referred to as “Lakeside EfW Ltd”.

The proposed expansion of Heathrow Airport requires the removal of the existing facilities, so Lakeside EfW Ltd proposes to replace the facilities on a like-for-like basis. The replacement facilities ("the Proposed Development") will be located on nearby land situated to the west of the Iver South Sludge Dewatering centre and south of the M4 Motorway, London.

Review of Legislation In the UK, the levels of pollution in the atmosphere are controlled by the National Air Quality Strategy and a number of European Directives which have been fully implemented. These have led to the setting of a number of Air Quality Assessment Levels (AQALs) for pollutants. The AQALs are set at a level well below those at which significant adverse health effects have been observed in the general population and in particularly sensitive groups.

In addition, Critical Levels have been set for the protection of ecosystems. Deposition of nitrogen and acid gases can cause nitrification and acidification of habitats. The Air Pollution Information System (APIS) provides Critical Loads for different habitats which consider the existing pollution loading for the site.

Review of Ambient Air Quality Monitoring information collected by the UK Government and by local authorities has been used to assess the current levels of pollutants in the atmosphere close to the Proposed Development. Where local monitoring data is not available, conservative estimates based on national monitoring results have been used as a background concentration.

Identification of Sensitive Receptors When assessing the impact of the Proposed Development, the assessment considers the point of maximum impact as a worst-case. In addition, the impact has been assessed at a number of identified sensitive receptors including the closest residential properties and ecologically sensitive receptors.

Dispersion Modelling of Emissions The ADMS dispersion model is routinely used for air quality assessments to the satisfaction of local authorities and the Environment Agency. The model uses weather data from the local area to predict the spread and movement of the exhaust gases from the stack for each hour over a five-year period. The model takes account of wind speed, wind direction, temperature, humidity and the amount of cloud cover, as all of these factors influence the dispersion of emissions. The model also takes account of the effects of buildings and terrain on the movement of air.

To set up the model, it has been conservatively assumed that the Proposed Development operates for the whole year and releases emissions at the daily or short-term emission limits continuously.

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The model was used to predict the ground level concentration of pollutants on a long-term and short-term basis across a grid of points. In addition, concentrations were predicted at the identified sensitive receptors.

Approach and Assessment of Impact on Air Quality – Protection of Human Health The impact of air quality on human health has been assessed using a standard approach based on guidance provided by the Institute of Air Quality Management (IAQM) and the Environment Agency where appropriate.

Using this approach, the following can be concluded from the assessment.

1. In relation to the impact on human health:

a. In accordance with Environmental Agency Guidance, the impact of all long-term process emissions associated with the ‘Main Case’ scenario can be considered ‘not significant’ at the point of maximum impact with the exception of the following pollutants:

i. Annual mean and short-term nitrogen dioxide;

ii. Short-term sulphur dioxide;

iii. Annual mean particulate matter (as PM2.5);

iv. Annual mean VOCs; and

v. Annual mean cadmium;

b. Using the IAQM 2017 screening criteria, the impact of all long-term process emissions associated with the ‘Main Case’ scenario can be considered ‘negligible’ at the point of maximum impact with the exception of the following pollutants:



iii. Annual mean particulate matter (as PM10);

iv. Annual mean particulate matter (as PM2.5);

v. Annual mean VOCs;

vi. Annual mean cadmium; and

vii. Annual mean PaHs.

2. For all of the pollutants listed above, the magnitude of change assessed in accordance with IAQM 2017 criteria is no worse than ‘slight adverse’ at all areas of relevant exposure.

3. The Environment Agency’s approach to assessing the impact of metals has been used which considers the risk of exceeding the AQAL based on the existing background levels and contribution from the Facility. Using this approach, it has been determined that there is no risk of exceeding any AQAL for heavy metals.

Approach and Assessment of Impact on Air Quality – Protection of Ecosystems The impact of emissions on atmospheric air quality in sensitive ecosystems has been assessed using a standard approach.

1. If the process contribution within a protected site is less than 1% of the long-term and less than 10% of the short-term benchmark, the emissions are ‘not significant’ and it can be concluded

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that there will be ‘no likely significant effect either alone and in-combination with other sources of pollutants, irrespective of background levels’.

2. If the process contribution at European and UK designated sites is greater than 1% of the relevant long-term, or 10% of the short-term benchmark, but the total predicted concentration including background levels is less than 70% of the relevant benchmark, the emissions are ‘not likely to have a significant effect’.

3. If the process contribution at locally designated sites is less than the relevant benchmark, the emissions are ‘not likely to have a significant effect’.

The impact of the deposition of nitrogen and acid gases on sensitive habitats has been assessed using the following approach.

1. It has been assumed that the Facility operates at the emission limits for the entire year.

2. Habitats have been assessed assuming all habitats are present at the point of greatest impact within each ecological site.

3. Where a feature consists of multiple locations, modelling has been undertaken at each of the closest points to the Facility and the maximum across all locations has been calculated to represent the feature.

4. The impact has been calculated based on the maximum predicted concentration over a five-year period at each ecological site and applying conservative deposition assumptions.

5. The results have been compared to habitat specific Critical Loads. The most sensitive habitat type has been conservatively assumed for each feature.

Two statutory designated sites and one locally designated site have been identified as requiring consideration within this assessment. At all of the sites, emissions from the operation of the Proposed Development can be screened out as ‘not significant’.

Significance of Impact Professional judgement has been used to determine the resulting significance of the effect of emissions associated with the operation of the Proposed Development. The assessment has shown that the operation of the Proposed Development will not cause a breach of any AQAL, that the annual mean magnitude of change can be described as no worse than ‘slight adverse’ for all pollutants at all areas of relevant exposure and that the magnitude of change is only slight adverse in small areas. Therefore, we conclude that the overall effect of the Proposed Development on local air quality will be ‘not significant’. As such, there should be no air quality constraint in granting planning permission for the Proposed Development.

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Contents Management Summary ................................................................................................................................................ 3

1 Introduction ........................................................................................................................................................ 9 1.1 Background .............................................................................................................................................. 9 1.2 Report structure ....................................................................................................................................... 9

2 Legislation and Policy ....................................................................................................................................... 10 2.1 European legislation............................................................................................................................... 10 2.2 National legislation and policy ............................................................................................................... 10 2.3 Local Air Quality Management ............................................................................................................... 11 2.4 Industrial Pollution Regulation............................................................................................................... 11

3 Methodology .................................................................................................................................................... 13 3.1 Air Quality Standards, Objectives and Guidelines ................................................................................. 13

3.1.1 Nitrogen dioxide ..................................................................................................................... 13 3.1.2 Sulphur dioxide ....................................................................................................................... 13 3.1.3 Particulate matter ................................................................................................................... 14 3.1.4 Carbon monoxide ................................................................................................................... 14 3.1.5 Hydrogen chloride .................................................................................................................. 14 3.1.6 Hydrogen fluoride ................................................................................................................... 15 3.1.7 Ammonia ................................................................................................................................ 15 3.1.8 Metals ..................................................................................................................................... 15 3.1.9 Volatile Organic Compounds (VOCs) ...................................................................................... 16 3.1.10 Dioxins and furans .................................................................................................................. 16 3.1.11 Polychlorinated biphenyl (PCBs) ............................................................................................. 17 3.1.12 Polycyclic Aromatic Hydrocarbons (PAHs).............................................................................. 17 3.1.13 Summary ................................................................................................................................. 17

3.2 Construction Assessment ....................................................................................................................... 19 3.3 Process Emissions Assessment .............................................................................................................. 25

3.3.1 Stack Emissions ....................................................................................................................... 25 3.3.2 Plume Visibility ....................................................................................................................... 28

3.4 Traffic Emissions Assessment................................................................................................................. 28 3.5 Significance of effect .............................................................................................................................. 29

4 Baseline Conditions .......................................................................................................................................... 30 4.1 Baseline Concentrations ........................................................................................................................ 30

4.1.1 National modelling – mapped background data .................................................................... 30 4.1.2 AURN and LAQM monitoring data ......................................................................................... 31 4.1.3 National monitoring data ....................................................................................................... 35

4.1.3.1 Hydrogen chloride ................................................................................................ 35 4.1.3.2 Hydrogen fluoride ................................................................................................. 36 4.1.3.3 Ammonia .............................................................................................................. 36 4.1.3.4 Volatile Organic Compounds ................................................................................ 37 4.1.3.5 Metals ................................................................................................................... 37 4.1.3.6 Dioxins, furans and polychlorinated biphenyl (PCBs) ........................................... 37 4.1.3.7 Polycyclic Aromatic Hydrocarbons (PAHs) ............................................................ 38

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4.2 Summary ................................................................................................................................................ 39 4.3 Sensitive Receptors ................................................................................................................................ 40

4.3.1 Dust Sensitive Receptors ........................................................................................................ 40 4.3.2 Vehicle Emission Sensitive Receptors ..................................................................................... 41 4.3.3 Process Emission Sensitive Receptors .................................................................................... 41 4.3.4 Air Quality Management Areas (AQMAs) ............................................................................... 42 4.3.5 Ecological Sensitive Receptors ................................................................................................ 43

5 Effect of proposals during construction ........................................................................................................... 45 5.1 Dust ........................................................................................................................................................ 45

5.1.1 Dust emission magnitude ....................................................................................................... 45 5.1.2 Sensitivity of the area ............................................................................................................. 45 5.1.3 Dust impact risk assessment .................................................................................................. 46

5.2 Construction phase traffic emissions ..................................................................................................... 46 5.2.1 Traffic generation rates .......................................................................................................... 46

5.3 Methodology .......................................................................................................................................... 49 5.3.1 Emissions factors and background concentrations ................................................................ 49 5.3.2 Approach to modelling queueing traffic ................................................................................. 50 5.3.3 Roads NOx conversion to NO2 ................................................................................................ 50 5.3.4 Model verification .................................................................................................................. 51

5.4 Results .................................................................................................................................................... 51

6 Effect of proposals during operation ............................................................................................................... 54 6.1 Selection of model ................................................................................................................................. 54 6.2 Emission limits ........................................................................................................................................ 54 6.3 Source and emissions data ..................................................................................................................... 56 6.4 Scenarios considered ............................................................................................................................. 59 6.5 Other Inputs ........................................................................................................................................... 59

6.5.1 Modelling domain ................................................................................................................... 59 6.5.2 Meteorological data and surface characteristics ................................................................... 60 6.5.3 Buildings.................................................................................................................................. 60 6.5.4 Terrain..................................................................................................................................... 61 6.5.5 Chemistry ................................................................................................................................ 62

6.6 Sensitivity Assessment ........................................................................................................................... 62 6.6.1 Surface Roughness .................................................................................................................. 62 6.6.2 Buildings.................................................................................................................................. 63 6.6.3 Terrain..................................................................................................................................... 63

6.7 Modelling Results – Main Case .............................................................................................................. 64 6.7.1 Results at the point of maximum impact ............................................................................... 64 6.7.2 Further assessment – annual mean nitrogen dioxide ............................................................ 67 6.7.3 Further assessment – hourly mean nitrogen dioxide ............................................................. 69 6.7.4 Further assessment – annual mean PM as PM10 .................................................................... 71 6.7.5 Further assessment – annual mean PM as PM2.5 ................................................................... 72 6.7.6 Further assessment – annual mean VOCs (as benzene)......................................................... 74 6.7.7 Further assessment – annual mean VOCs (as 1,3-butadiene) ................................................ 75 6.7.8 Further assessment – annual mean cadmium........................................................................ 77 6.7.9 Further assessment – annual mean PaHs ............................................................................... 80 6.7.10 Further assessment – 99.73rd %ile of hourly means sulphur dioxide ................................... 81

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6.7.11 Further assessment – 99.9th %ile of 15-minute means sulphur dioxide ................................ 82 6.7.12 Metals assessment ................................................................................................................. 84

6.7.12.1 Long-term results .................................................................................................. 87 6.7.12.2 Short-term results ................................................................................................. 87

6.7.13 Impact at ecological receptors ............................................................................................... 88 6.7.13.1 Calculation methodology – nitrogen deposition .................................................. 88 6.7.13.2 Calculation methodology - acidification ............................................................... 88 6.7.13.3 Atmospheric emissions - Critical Levels ................................................................ 89 6.7.13.4 Deposition of emissions - Critical Loads ............................................................... 90 6.7.13.5 Deposition of emissions - Critical Loads - results ................................................. 90

6.7.14 Additional assessment of Windsor Forest and Great Park ..................................................... 91 6.8 Modelling Results – Commissioning ...................................................................................................... 91

6.8.1 Results at the point of maximum impact ............................................................................... 91 6.9 Plume Visibility ....................................................................................................................................... 93

6.9.1 Base assumptions ................................................................................................................... 93 6.9.2 Plume visibility results ............................................................................................................ 93

6.10 Operational phase traffic emissions ...................................................................................................... 94 6.11 Significance of effect .............................................................................................................................. 94

7 Mitigation and Monitoring ............................................................................................................................... 95 7.1 Operational phase .................................................................................................................................. 95 7.2 Construction Phase ................................................................................................................................ 95

8 Residual Effects ................................................................................................................................................ 98 8.1 Construction Phase ................................................................................................................................ 98 8.2 Operational Phase .................................................................................................................................. 98

9 Cumulative Effects ............................................................................................................................................ 99 9.1 Cemex Langley ....................................................................................................................................... 99 9.2 Cemex Datchet ..................................................................................................................................... 100 9.3 Thorney Mill/Link Park Heathrow ........................................................................................................ 100 9.4 M4 Smart Motorway ............................................................................................................................ 100 9.5 M25 Junction 10 ................................................................................................................................... 100

10 Summary and Conclusions ............................................................................................................................. 102

11 References ...................................................................................................................................................... 104

Appendices ............................................................................................................................................................... 106 A Figures ............................................................................................................................................................ 109 B Roads Modelling Verification Procedure........................................................................................................ 132 C APIS Critical Loads .......................................................................................................................................... 137 D Deposition Analysis at Ecological Sites ........................................................................................................... 139

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1 Introduction

1.1 Background Lakeside EfW Ltd is a joint venture between Grundon Waste Management Limited and Viridor. It operates the existing Lakeside Road Energy from Waste (EfW) facility in Colnbrook, Slough. Grundon Waste Management is the sole owner / operator of the high temperature incinerator (HTI) adjoined to the EfW on Lakeside Road. Lakeside EfW Ltd, Grundon Waste Management Limited and Viridor are hereafter collectively referred to as “Lakeside EfW Ltd”.

The proposed expansion of Heathrow Airport requires the removal of the existing facilities, so Lakeside EfW Ltd proposes to replace the facilities on a like-for-like basis. The replacement facilities will be located on nearby land situated to the west of the Iver South Sludge Dewatering centre and south of the M4 Motorway.

The replacement EfW facility (the Facility), just like the existing facility, will process approximately 440,0000 tonnes per annum of non-hazardous residual municipal solid waste (MSW) and commercial and industrial waste (C&I) primarily sourced within West London and the M4 corridor areas. The Facility has been designed to generate approximately 44 MWe at the design point and export approximately 39 MWe.

The HTI will process up to 10,000 tonnes per annum of mainly clinical hazardous waste.

1.2 Report structure This report has the following structure.

• National and international air quality legislation and guidance are considered in Section 2.

• The current ambient air quality levels are detailed separately in Section 3.

• Section 4 outlines a review of local and national baseline air quality and highlights the residential properties and ecological receptors which are sensitive to changes in air quality associated with the Proposed Development.

• Section 5 considers the impact of the construction of the Proposed Development.

• Section 5.2 considers the impact of the operation of the Proposed Development.

• Section 7 considers any mitigation and monitoring which might be required.

• Section 8 reports the residual effects.

• Cumulative impacts of other developments are considered in section 9.

• The summary of the assessment can be found in Section 10.

• The Appendices include dispersion diagrams and detailed results tables from the analysis of the impact at ecological receptors.

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2 Legislation and Policy

2.1 European legislation European air quality legislation is consolidated under Directive 2008/50/EC, which came into force on 11 June 2008. This Directive consolidates previous legislation which was designed to deal with specific pollutants in a consistent manner and provides new air targets and limits for fine particulates. The consolidated Directives include:

• Directive 99/30/EC – the First Air Quality "Daughter" Directive – which sets Ambient Air Directive (AAD) Limit Values for nitrogen dioxide and oxides of nitrogen, sulphur dioxide, lead and particulate matter;

• Directive 2000/69/EC – the Second Air Quality "Daughter" Directive – which sets AAD Limit Values for benzene and carbon monoxide; and

• Directive 2002/3/EC – the Third Air Quality "Daughter" Directive – which seeks to establish long-term Target Values, an alert threshold and an information threshold for concentrations of ozone in ambient air.

The fourth daughter Directive – 2004/107/EC - was not included within the consolidation. It sets health-based Target Values for polycyclic aromatic hydrocarbons, cadmium, arsenic, nickel and mercury, for which there is a requirement to reduce exposure to as low as reasonably achievable.

2.2 National legislation and policy The Air Quality Standards Regulations (2010) seek to transpose Directive 2008/50/EC and the Fourth Daughter Directive within the UK. The regulations also extend powers, under Section 85(5) of the Environment Act (1995), for the Secretary of State to give directions to local authorities for the implementation of these Directives.

The UK Government and the devolved administrations are required under the Environment Act (1995) to produce a national air quality strategy. This was published in 2007. The Air Quality Strategy (AQS) sets out the UK's air quality objectives and recognises that action at national, regional and local level may be needed, depending on the scale and nature of the air quality problem. This includes additional targets and limits for 15-minute sulphur dioxide and 1,3-butadiene and more stringent requirements for benzene and PAHs known as AQS Objectives. Environmental Assessment Levels (EALs) for other pollutants are presented on the gov.uk website as part of the Environment Agency's Environmental Management Guidance (Air emissions risk assessment for your environmental permit), which was last updated on 1st March 2016 and is referred to here as EA (2016). AAD Target and Limit Values, AQS Objectives, and EALs are set at levels well below those at which significant adverse health effects have been observed in the general population and in particularly sensitive groups. For the remainder of this report, these are collectively referred to as Air Quality Assessment Levels (AQALs). The AQALs used in this assessment are considered in section 3 below.

The UK Government published the Clean Air Strategy (CAS) in January 2019. This sets out the methods by which air pollution from all sectors will be reduced. The CAS has not introduced any new AQALs.

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Local Air Quality Management Technical Guidance 16 (updated February 2018), referred to as LAQM (TG16), outlines that the AQALs apply in the following locations:

• Annual mean - all locations where members of the public might be regularly exposed - i.e. building facades of residential properties, schools, hospitals, care homes etc.

• 24-hour mean and 8-hour mean - all locations where the annual mean objective would apply together with hotels and gardens of residential properties.

• 1-hour mean - all locations where the annual mean, 24-hour and 8-hour mean apply together with kerbside sites and any areas where members of the public might be reasonably expected to spend one hour or more.

• 15-minute mean - all locations where members of the public might reasonably be exposed for a period of 15 minutes or more.

2.3 Local Air Quality Management Under Section 82 of the Environment Act (1995) (Part IV), local authorities 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 assessing present and likely future ambient pollutant concentrations against AQALs. If it is predicted that levels at the façade of buildings where members of the public are regularly present (normally residential properties) are likely to be exceeded, the local authority is required to declare an Air Quality Management Area (AQMA). For each AQMA, the local authority is required to produce an Air Quality Action Plan (AQAP), the objective of which is to reduce pollutant levels in pursuit of the relevant AQALs.

There are a number of AQMAs in the vicinity of the Proposed Development. These are discussed in section 4 below.

2.4 Industrial Pollution Regulation Atmospheric emissions from industrial processes are controlled in the UK through the Environmental Permitting (England and Wales) Regulations (2010), and subsequent amendments. The Proposed Development will be regulated by the Environment Agency and need an Environmental Permit to operate. The Environmental Permit will include conditions to prevent fugitive emissions of dust and odour beyond the boundary of the installation. The Environmental Permit will also include limits on emissions to air.

The Industrial Emissions Directive (IED) (Directive 2010/75/EU) was adopted on 7th January 2013 and is the key European Directive which covers almost all regulation of industrial processes in the EU. Within the IED, the requirements of the relevant sector Best Available Techniques Reference Document (BREF) become binding as Best Available Techniques (BAT) guidance, as follows.

• Article 15, paragraph 2, of the IED requires that Emission Limit Values (ELVs) are based on BAT.

• Article 13 of the IED, requires that 'the Commission' develops BREFs.

• Article 21, paragraph 3, of the IED, requires that when updated BAT conclusions are published, the Competent Authority (in England this is the Environment Agency) has up to four years to revise permits for facilities covered by that activity to comply with the requirements of the sector specific BREF.

The Final Draft Waste incineration BREF was published by the European IPPC Bureau in December 2018 and is expected to be formally adopted in Q3 2019. Upon formal adoption, it is highly likely that the BREF will be implemented in the UK. The Environment Agency will be required to review

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and implement conditions within all permits which require operators to comply with the requirements set out in the BREF. This will include the Proposed Development. As currently drafted, the BREF will introduce BAT-AELs (BAT Associated Emission Limits) which are more stringent than those currently set out in the IED. The EfW Plant and HTI will be designed to meet the requirements of the BREF. Therefore, it has been assumed that the emissions from the Proposed Development will need, as a minimum, to comply with the BAT-AELs set out in the BREF for new plants.

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3 Methodology

3.1 Air Quality Standards, Objectives and Guidelines In the UK, AAD Limit Values, Targets, and air quality standards and objectives (AQOs) for major pollutants are described in The Air Quality Strategy (AQS). In addition, the Environment Agency include Environmental Assessment Levels (EALs) for other pollutants in the environmental management guidance document ‘Air Emissions Risk Assessment for your Environmental Permit’1 (“Air Emissions Guidance”). The long-term and short-term EALs from this document have been used when the AQS does not contain relevant objectives. Standards and objectives for the protection of sensitive ecosystems and habitats are also contained within the Air Emissions Guidance and the Air Pollution Information System (APIS).

3.1.1 Nitrogen dioxide

All combustion processes produce nitric oxide (NO) and nitrogen dioxide (NO2), known by the general term of nitrogen oxides (NOx). In general, the majority of the NOx released is in the form of NO, which then reacts with ozone in the atmosphere to form nitrogen dioxide. Of the two compounds, nitrogen dioxide is associated with adverse effects on human health, principally relating to respiratory illness. The World Health Organisation (WHO) has stated that “many chemical species of nitrogen oxides exist, but the air pollutant species of most interest from the point of view of human health is nitrogen dioxide”.

The major sources of NOx in the UK are road transport and power stations. According to the most recent annual report from the National Atmospheric Emissions Inventory (NAEI)2, in 2016 road transport accounted for 34% of UK emissions, with power stations accounting for a further 22%. High levels of NOx in urban areas are almost always associated with high traffic densities.

The AQS includes two objectives to be achieved by 31 December 2005. Both of these objectives are included in the Air Quality Directive, with an achievement date of 1st January 2010.

• A limit for the one-hour mean of 200 µg/m³, not to be exceeded more than 18 times a year (equivalent to the 99.79th percentile).

• A limit for the annual mean of 40 µg/m³.

In addition, the AQS includes objectives for the protection of sensitive vegetation and ecosystems of 30 µg/m³ for the annual mean, and 75 µg/m³ for the daily mean concentration of nitrogen oxides.

3.1.2 Sulphur dioxide

Sulphur dioxide is predominantly released by the combustion of fuels containing sulphur. Around 68% of UK emissions in 2004 were associated with power stations, with much of the remainder associated with other combustion processes. Emissions of sulphur dioxide have reduced by 87% since 1970, due to a reduction in the number of coal-fired combustion plants, the installation of flue gas desulphurisation plants on a number of large coal-fired power stations and the reduction in sulphur content of liquid fuels.

1 https://www.gov.uk/guidance/air-emissions-risk-assessment-for-your-environmental-permit#environmental-

standards-for-air-emissions 2 NAIE Air Pollution Inventories for England, Scotland, Wales and Northern Ireland: 1990-2016, DEFRA.

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The AQS contains three objectives for the control of sulphur dioxide:

• A limit for the 15-minute mean of 266 µg/m³, not to be exceeded more than 35 times a year (the 99.9th percentile) to be achieved by 31st December 2005.

• A limit for the one hour mean of 350 µg/m³, not to be exceeded more than 24 times a year (the 99.73rd percentile) to be achieved by 31st December 2004.

• A limit for the daily mean of 125 µg/m³, not to be exceeded more than 3 times a year (the 99.2nd percentile) to be achieved by 31st December 2004.

The hourly and daily objectives are included in the Air Quality Directive.

In addition, the AQS includes two objectives for the protection of vegetation and ecosystems. These are a concentration of 20 µg/m³ (reduced to 10 µg/m³ where lichens or bryophytes are present) as an annual mean and as a winter average.

3.1.3 Particulate matter

Concerns over the health impact of solid matter suspended in the atmosphere tend to focus on particles with a diameter of less than 10 µm, known as PM10s. These particles have the ability to enter and remain in the lungs. Various epidemiological studies have shown increases in mortality associated with high levels of PM10s, although the underlying mechanism for this effect is not yet understood. Significant sources of PM10s are road transport (22%), quarrying (16%) and stationary combustion (34%).

The AQS includes two objectives for PM10s to be achieved by the end of 2004, both of which are included in the Air Quality Directive.

• A limit for the annual mean of 40 µg/m³, to be achieved by 2004.

• A daily limit of 50 µg/m³, not to be exceeded more than 35 times a year (the 90.41st percentile) to be achieved by 2004.

The previous AQS included some provisional objectives for 2010. These have been replaced by an exposure reduction objective for PM2.5 in urban areas and a target value for PM2.5 of 25 µg/m³ as an annual mean. This target value is included in the Air Quality Directive.

3.1.4 Carbon monoxide

Carbon monoxide is produced by the incomplete combustion of fuels containing carbon. By far the most significant source is road transport, which produces 67% of the UK’s emissions. Carbon monoxide can interfere with the processes that transport oxygen around the body, which can prove fatal at very high levels.

Concentrations in the UK are well below levels at which health effects can occur. The AQS includes the following objective for the control of carbon monoxide, which is also included in the Air Quality Directive:

• A limit for the 8-hour running mean of 10 mg/m³, to be achieved by 1st January 2005.

The Air Emissions Guidance also defines a short-term (1-hour) EAL of 30 mg/m³. There is no long-term EAL.

3.1.5 Hydrogen chloride

There are no AQOs for hydrogen chloride contained within the AQS. However, the Air Emissions Guidance defines the short-term EAL as 750 µg/m³. There is no long-term EAL.

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3.1.6 Hydrogen fluoride

There are no AQOs for hydrogen fluoride contained within the AQS. However, the Air Emissions Guidance defines the short-term EAL as 160 µg/m³ and the long-term EAL as 16 µg/m³.

The Air Emissions Guidance also provides Critical Levels for the protection of vegetation and ecosystems of 5 μg/m³ as a daily mean and 0.5 μg/m³ as a weekly mean concentration of hydrogen fluoride.

3.1.7 Ammonia

There are no AQOs for ammonia contained within the AQS. However, the Air Emissions Guidance defines the short-term EAL as 2,500 µg/m³ and the long-term EAL as 180 µg/m³. The Guidance also provides Critical Levels for the protection of vegetation and ecosystems. These are a concentration of 3 µg/m³ as an annual mean, reduced to 1 µg/m³ where lichens or bryophytes are present.

3.1.8 Metals

Lead is the only metal included in the AQS. Lead can have many health effects, including effects on the synthesis of haemoglobin, the nervous system and the kidneys. Emissions of lead in the UK have declined by 98% since 1970, due principally to the virtual elimination of leaded petrol.

The AQS includes objectives to limit the annual mean to 0.5 µg/m³ by the end of 2004 and to 0.25 µg/m³ by the end of 2008. Only the first objective is included in the Air Quality Directive.

The fourth Daughter Directive on air quality (Commission Decision 2004/107/EC) includes target values for arsenic, cadmium and nickel. However, the preamble to the Directive makes it clear that the use of these target values is relatively limited. Paragraph (5) states:

“The target values would not require any measures entailing disproportionate costs. Regarding industrial installations, they would not involve measures beyond the application of best available techniques (BAT) as required by Council Directive 96/61/EC of 24 September 1996 concerning integrated pollution prevention and control (5) and in particular would not lead to the closure of installations. However, they would require Member States to take all cost-effective abatement measures in the relevant sectors.”

And paragraph (6) states:

“In particular, the target values of this Directive are not to be considered as environmental quality standards as defined in Article 2(7) of Directive 96/61/EC and which, according to Article 10 of that Directive, require stricter conditions than those achievable by the use of BAT.”

Although these target values have been included in the assessment, it is important to note that the application of the target values would not have an effect on the design or operation of the EfW Plant or the HTI. These will be designed in accordance with BAT and include cost effective methods for the abatement of arsenic, cadmium and nickel, including the injection of activated carbon and a fabric filter.

Emissions limits will be set in the EP for a number of heavy metals which do not have air quality standards associated with them. The EALs for these metals, and lead, are summarised in Table 1.

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Table 1: Environmental Assessment Levels (EALs) for Metals

Metal Daughter Directive Target Level (µg/m³)

EALs (µg/m³)

Long-term Short-term

Arsenic 0.006 0.003 -

Antimony - 5 150

Cadmium 0.005 0.005 -

Chromium (II & III) - 5 150

Chromium (VI) - 0.0002 -

Cobalt - - -

Copper - 10 200

Lead - 0.25 -

Manganese - 0.15 1500

Mercury - 0.25 7.5

Nickel 0.020 0.020 -

Thallium - - -

Vanadium - 5 1

3.1.9 Volatile Organic Compounds (VOCs)

A variety of VOCs could be released from the stack, of which benzene and 1,3-butadiene are included in the AQS and monitored at various stations around the UK. The AQS includes the following objectives for the running annual mean:

• Benzene – 5 µg/m³ to be achieved by 2010; and

• 1,3-butadiene – 2.25 µg/m³ to be achieved by 2003.

The Air Emissions Guidance includes a short-term EAL for benzene, calculated from occupational exposure. This is a limit of 195 µg/m³ for an hourly mean. There are no short-term EALs for 1,3-butadiene.

3.1.10 Dioxins and furans

Dioxins and furans are a group of organic compounds with similar structures, which are formed as a result of combustion in the presence of chlorine. Principal sources include steel production, power generation, coal combustion and uncontrolled combustion, such as bonfires. The Municipal Waste Incineration Directive and UK legislation imposed strict limits on dioxin emissions in 1995, with the result that current emissions from incineration of municipal solid waste in the UK in 1999 were less than 1% of the emissions from waste incinerators in 1995. The Waste Incineration Directive, now included in the IED, imposed even lower limits, reducing the limit to one tenth of the previously permitted level.

One dioxin, 2,3,7,8-TCDD, is a definite carcinogen and a number of other dioxins and furans are considered to be possible carcinogens. A tolerable daily intake (TDI) for Dioxins, furans and dioxins like PCBs has been recommended by the Committee on the Toxicity of Chemicals in Food, Consumer Products and the Environment of 2 pg I-TEQ per kg bodyweight per day.

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Dioxins are not normally compared with set EALs, but the probable ingestion rates of dioxins by different groups of people is considered as part of the Human Health Risk Assessment contained as a separate document within the application.

3.1.11 Polychlorinated biphenyl (PCBs)

PCBs have high thermal, chemical and electrical stability and were manufactured in large quantities in the UK between the 1950s and mid-1970s. Commercial PCB mixtures, which contained a range of dioxin-like and non-dioxin like congeners, were sold under a variety of trade names, the most common in the UK being the Aroclor mixtures. UK legislative restrictions on the use of PCBs were first introduced in the early 1970s.

Although now banned from production current atmospheric levels of PCBs are due to the ongoing primary anthropogenic emissions (e.g. accidental release of products or materials containing PCBs), volatilisation from environmental reservoirs which have previously received PCBs (e.g. sea and soil) or incidental formation of some congeners during the combustion process.

There are no AQOs for PCBs contained within the AQS. However, the Air Emissions Guidance defines the short-term EAL as 6 µg/m³ and the long-term EAL as 0.2 µg/m³.

A number of PCBs are considered to possess dioxin like toxicity and are known as dioxin-like PCBs. The total intake from dioxins, furans and dioxins like PCBs is compared to the TDI for dioxins, furans and dioxin like PCBs as part of the Human Health Risk Assessment contained as a separate document within the application.

3.1.12 Polycyclic Aromatic Hydrocarbons (PAHs)

PAHs are members of a large group of organic compounds widely distributed in the atmosphere. The best-known PAH is benzo[a]pyrene (B[a]P). The AQS included an objective to limit the annual mean of B[a]P to 0.25 ng/m³ by the end of 2010. This goes beyond the requirements of European Directives, since the fourth Daughter Directive on air quality (Commission Decision 2004/107/EC) includes a target value for benzo(a)pyrene of 1 ng/m³ as an annual mean.

3.1.13 Summary

AAD Target and Limit Values, AQS Objectives, and EALs are set at levels well below those at which significant adverse health effects have been observed in the general population and in particularly sensitive groups. As noted earlier, these are collectively referred to as Air Quality Assessment Levels (AQALs). Table 2 and Table 3, along with Table 1 above for metals, summarise the air quality objectives and guidelines used in this assessment. The sources for each of the values can be found in the preceding sections.

Table 2: Air Quality Assessment Levels (AQALs)

Pollutant Limit Value (µg/m³) Averaging Period Frequency of Exceedances

Nitrogen dioxide 200 1 hour 18 times per year (99.79th percentile)

40 Annual -

Sulphur dioxide 266 15 minutes 35 times per year (99.9th percentile)

350 1 hour 24 times per year (99.73rd percentile)

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Pollutant Limit Value (µg/m³) Averaging Period Frequency of Exceedances

125 24 hours 3 times per year (99.18th percentile)

Particulate matter (PM10)

50 24 hours 35 times per year (90.41st percentile)

40 Annual -

Particulate matter (PM2.5)

25 Annual -

Carbon monoxide 10,000 8 hours, running -

30,000 1 hour

Hydrogen chloride 750 1 hour -

Hydrogen fluoride 160 1 hour -

16 Annual -

Ammonia 2,500 1 hour -

180 Annual -

Lead 0.25 Annual -

Benzene 5.00 Annual -

195 1 hour -

1,3-butadiene 2.25 Annual, running -

PCBs 6 1-hour -

0.2 Annual -

PAHs 0.00025 Annual -

Table 3: Critical Levels for the Protection of Vegetation and Ecosystems

Pollutant Concentration (µg/m³)

Measured as

Nitrogen oxides

(as nitrogen dioxide)

75 Daily mean

30 Annual mean

Sulphur dioxide 10 Annual mean

for sensitive lichen communities and bryophytes and ecosystems where lichens and bryophytes are an important part of the ecosystem’s integrity

20 Annual mean

for all higher plants

Hydrogen fluoride 5 Daily mean

0.5 Weekly mean

Ammonia 1 Annual mean

for sensitive lichen communities and bryophytes and ecosystems where lichens and bryophytes are an important part of the ecosystem’s integrity

3 Annual mean for all higher plants

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3.2 Construction Assessment There is the potential for dust to be released into the atmosphere as a result of construction and demolition phase activities. These fugitive dust emissions have been assessed on a qualitative basis in accordance with the methodology outlined within the 2014 Institute of Air Quality Management (IAQM) guidance document 'Guidance on the assessment of dust from demolition and construction'. This guidance sets out the methodology for assessing the air quality impacts of construction and demolition and identifies good practice for mitigating and managing air quality impacts. It is noted that the quantity of dust emitted would be directly related to the area of land being worked and the nature, magnitude and duration of construction activities.

The assessment methodology is based on the risk of a construction site giving rise to dust impacts and the sensitivity of the surrounding area. Activities are divided into four types to reflect their different potential impacts. These are:

• demolition;

• earthworks;

• construction; and

• trackout.

Trackout is a less well-known term. It is defined by the IAQM as:

"The transport of dust and dirt from the construction / demolition site onto the public road network, where it may be deposited and then re-suspended by vehicles using the network. This arises when lorries leave the construction / demolition site with dusty materials, which may then spill onto the road, and/or when lorries transfer dust and dirt onto the road having travelled over muddy ground on site."

The assessment methodology considers three separate dust effects:

• annoyance due to dust soiling;

• harm to ecological receptors; and

• the risk of health effects due to significant increase in exposure to PM10 (particulate matter with a diameter less than 10µm).

The first stage of the assessment for the impact of fugitive emissions of dust during construction is to determine whether the impact can be screened out as ‘negligible’, or whether a more detailed assessment is required. The IAQM recommends that the developer will normally be required to undertake a detailed assessment where there is:

• a human receptor within 350m of the boundary of the Site;

• an ecological receptor within 50m of the boundary of the Site; or

• a human or ecological receptor within 50m of the route(s) used by construction vehicles on the public highway, up to 500m from the Site entrance(s).

If the development cannot be screened out, the developer is to provide a clear description of the proposed demolition and construction activities, their location and duration, and any phasing of the development.

A human receptor, in this context, is any location where a person may experience the annoyance effects of airborne dust or dust soiling or suffer exposure to PM10 over a period of time relevant to the AQALs. These include:

• residential dwellings;

• schools;

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• hospitals;

• care homes;

• hotels;

• gardens (where relevant public exposure is likely i.e. excluding extremities of gardens or front gardens); and

• sensitive commercial premises including; vehicle showrooms, food manufacturers; and electronics manufacturers.

Ecological receptors should include statutory and non-statutory designated sites.

If a detailed assessment is required, the second stage is to assess the risk of dust effects arising. A site is allocated to a risk category based on two factors; dust emission magnitude; and the sensitivity of the area. These factors are combined to give the risk of dust impact as described below.

The dust emission magnitude should be determined by considering the following criteria:

Table 4: Dust Emission Magnitude Criteria

Magnitude Description

Demolition Activities

Large total building volume > 50,000m³, potentially dusty construction material (i.e. concrete), on-site crushing and screening, demolition activities > 20m above ground level

Medium total building volume 20,000 - 50,000m³, potentially dusty construction material, demolition activities 10 – 20m above ground level

Small total building volume < 20,000m³, construction material with low potentially for dust release (i.e. metal cladding or timber), demolition activities <10m above ground level, demolition during wetter months

Earthworks

Large total size area > 10,000m², potentially dusty soil type (e.g. clay, which will be prone to suspension when dry due to small particle size), > 10 heavy earth moving vehicles active at any one time, formation of bunds > 8m in height, total material moved > 100,000 tonnes

Medium total size area 2,500 – 10,000m², moderately dusty soil type (i.e. silt), 5 – 10 heavy earth moving vehicles active at any one time, formation of bunds 4 – 8m in height, total material moved 20,000 – 100,000 tonnes

Small total size area < 2,500m², soil type with large grain size (i.e. sand), < 5 heavy earth moving vehicles active at any one time, formation of bunds < 4m in height, total material moved < 10,000 tonnes, earthworks during wetter months

Construction Activities

Large total building volume > 100,000m³, piling, on site concrete batching, sandblasting

Medium total building volume 25,000 – 100,000m³, potentially dusty construction material (e.g. concrete), piling, on site concrete batching

Small total building volume < 25,000m³, construction material with low potential for dust release (e.g. metal cladding or timber)

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Magnitude Description

Trackout

Large > 50 HDV (> 3.5t) trips in any one day, potentially dusty surface material (e.g. high clay content), unpaved road length > 100 m

Medium 10 – 50 HDV (> 3.5t) trips in any one day, moderately dusty surface material (e.g. high clay content), unpaved road length 50 – 100 m

Small < 10 HDV (> 3.5t) trips in any one day, surface material with low potential for dust release, unpaved road length < 50 m

Only receptors within 50 m of the routes(s) used by vehicles on the public highway and up to 500 m from the Site entrance(s) are considered to be at risk from the effects of dust.

The sensitivity of the area takes account of a number of factors:

• the specific sensitivities of receptors in the area;

• the proximity and number of those receptors;

• in the case of PM10, the local background concentration; and

• site-specific factors, such as whether there are natural shelters, such as trees or other vegetation, to reduce the risk of wind-blown dust.

The type of receptors at different distances from the Site boundary or, if known, from the dust generating activities, should be included. Consideration also should be given to the number of `human receptors’. Exact counting of the number of `human receptors’ is not required. Instead the guidance recommends that judgement is used to determine the receptors (a residential unit is one receptor) within each distance band.

There is no unified sensitivity classification scheme that covers the different potential effects on property, human health and ecological receptors. However, the following guidance is provided on the sensitivity of different types of receptors. For the sensitivity of people and their property to soiling it is recommended that professional judgement is used to identify where on the spectrum between high and low sensitivity a receptor lies, taking into account the following principles.

Table 5: Sensitivity to Dust Soiling Effects

Sensitivity Justification

High Users can reasonably expect an enjoyment of a high level of amenity; or

The appearance, aesthetics or value of their property would be diminished by soiling; and

the people or property would reasonably be expected to be present continuously, or at least regularly for extended periods as part of the normal pattern of use of the land.

Indicative examples include dwellings, museums and other culturally important collections, medium and long term car parks and car showrooms.

Medium Users would expect to enjoy a reasonable level of amenity but would not reasonably expect to enjoy the same level of amenity as in their home; or

The appearance, aesthetic or value of their property could be diminished by soiling; or

The people or property would not reasonably be expected to be present here continuously or regularly for extended periods as part of the normal pattern of use of the land;

Indicative examples include parks and places of work.

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Low The enjoyment of amenity would not reasonably be expected; or

Property would not reasonably be expected to be diminished in appearance, aesthetics or value by soiling; or

There is transient exposure, where the people or property would reasonably be expected to be present only for limited periods of time as part of the normal pattern of use of the land.

Indicative examples include playing fields, farmland (unless commercially-sensitive horticultural), footpaths, short-term car parks and roads.

For the sensitivity of people to the health effects of PM10 the IAQM Guidance recommends that there are three sensitivities based on whether or not the receptor is likely to be exposed to elevated concentrations over a 24-hour period.

Table 6: Sensitivity to Heath Effects of PM10


High Locations where members of the public are exposed over a time period relevant to the air quality objective for PM10 (in the case of the 24-hour objectives, a relevant location would be one where individuals may be exposed for eight hours or more in a day).

Indicative examples include residential properties. Hospitals, schools and residential care homes should also be considered as having equal sensitivity to residential areas for the purposes of this assessment.

Medium Locations where the people exposed are workers, and exposure is over a time period relevant to the air quality objective for PM10 (in the case of the 24- hour objectives, a relevant location would be one where individuals may be exposed for eight hours or more in a day).

Indicative examples include office and shop workers, but will generally not include workers occupationally exposed to PM10, as protection is covered by Health and Safety at Work legislation.

Low Locations where human exposure is transient.

Indicative examples include public footpaths, playing fields, parks and shopping streets

The following table provides an example of possible sensitivities of receptors to ecological effects.

Table 7: Sensitivity to Ecological Effects


High Locations with an international or national designation and the designated features may be affected by dust soiling; or

Locations where there is a community of a particularly dust sensitive species such as vascular species included in the Red Data List for Great Britain.

Indicative examples include a Special Area of Conservation (SAC) designated for acid heathlands or a local site designated for lichens adjacent to the demolition of a large site containing concrete (alkali) buildings.

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Medium Locations where there is a particularly important plant species, where its dust sensitivity is uncertain or unknown; or

Locations with a national designation where the features may be affected by dust deposition.

Indicative example is a Site of Special Scientific Interest (SSSI) with dust sensitive features.

Low Locations with a local designation where the features may be affected by dust deposition.

Indicative example is a local Nature Reserve with dust sensitive features.

The following tables show how sensitivity of the area should be determined for dust soiling, human health and ecosystem impacts respectively. The sensitivity of the area should be derived for demolition, construction, earthworks and trackout.

Table 8: Sensitivity of the Area to Dust and Soiling Impacts on People and Property

Receptor Sensitivity

Number of Receptors

Distance from the Source (m)

<20 <50 <100 <350

High >100 High High Medium Low

10-100 High Medium Low Low

1-10 Medium Low Low Low

Medium >1 Medium Low Low Low

Low >1 Low Low Low Low

Table 9: Sensitivity of the Area to Human Health Impacts


Annual Mean PM10 Conc.

No. of Receptors


<20 <50 <100 <200 <350

High >32 µg/m³ >100 High High High Medium Low

10-100 High High Medium Low Low

1-10 High Medium Low Low Low

28 - 32 µg/m³

>100 High High Medium Low Low



24 - 28 µg/m³

>100 High Medium Low Low Low


1-10 Medium Low Low Low Low

<24 µg/m³ >100 Medium Low Low Low Low

10-100 Low Low Low Low Low


Medium >32 µg/m³ >10 High Medium Low Low Low

1-10 Medium Low Low Low Low

>10 Medium Low Low Low Low

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Annual Mean PM10 Conc.

No. of Receptors


<20 <50 <100 <200 <350

28 - 32 µg/m³


24 - 28 µg/m³

>10 Low Low Low Low Low


<24 µg/m³ >10 Low Low Low Low Low


Low - >1 Low Low Low Low Low

Table 10: Sensitivity of the Area to Ecological Impacts

Receptor Sensitivity Distance from the Source (m)

<20 <50

High High Medium

Medium Medium Low

Low Low Low

The dust magnitude and sensitivity of the area should be combined to determine the risk of impacts with no mitigation applied. The following matrices should be used. For the cases where the risk category is ‘negligible’, no mitigation measures beyond those required by accepted best practice would be necessary.

Table 11: Risk of Dust Impacts – Level of Mitigation Required

Sensitivity of Area Dust Emission Magnitude

Large Medium Small

Demolition

High High Risk Medium Risk Medium Risk

Medium High Risk Medium Risk Low Risk

Low Medium Risk Low Risk Negligible

Earthworks

High High Risk Medium Risk Low Risk

Medium Medium Risk Medium Risk Low Risk

Low Low Risk Low Risk Negligible

Construction


Medium Medium Risk Medium Risk Low Risk


Trackout


Medium Medium Risk Low Risk Negligible


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3.3 Process Emissions Assessment

3.3.1 Stack Emissions

The EPUK and IAQM (2017) guidance document has been developed for professionals operating within the planning system. It provides them with a means of reaching sound decisions, having regard to the air quality implications of development proposals. This is not intended to replace the guidance that exists for industrial developments which require a permit, but the guidance notes that the Environment Agency guidance has not been developed for conducting an assessment to accompany a planning application. The IAQM (2017) guidance states that it may be adapted using professional judgement. Therefore, where appropriate, Environment Agency guidance has been incorporated.

The IAQM (2017) guidance includes the following matrix which should be used to describe the impact based on the change in concentration relative to the AQAL and the overall predicted concentration with the scheme - i.e. the future baseline plus the process contribution.

Table 12: IAQM Impact Descriptors

Long term average concentration at receptor in assessment year

% change in concentration relative to Air Quality Assessment Level (AQAL)

1 2-5 6-10 >10

75% or less of AQAL Negligible Negligible Slight Moderate

76-94% of AQAL Negligible Slight Moderate Moderate

95-102% of AQAL Slight Moderate Moderate Substantial

103-109% of AQAL Moderate Moderate Substantial Substantial

110% or more of AQAL Moderate Substantial Substantial Substantial

It is intended that the change in concentration relative to the AQAL (the process contribution) is rounded to the nearest whole number. Therefore, any impact which is between 0.5% and 1.5% would be classified as a 1% change in concentration. An impact of less than 0.5% is described as negligible irrespective of baseline concentrations.

In order to be consistent with the methodology adopted in other sections of the Environmental Statement, only impacts described as moderate or above are considered to be significant in EIA terms.

The above matrix is only designed to be used with annual mean concentrations. For short term concentrations (i.e. those averaged over a period of an hour or less) the following descriptors of change should be used to describe the impact:

• < 10% - negligible;

• 10 - 20% - slight;

• 20 - 50% - moderate; and

• > 50% - substantial.

The approach for assessing the impact of short term emissions has been carried out in line with the IAQM (2017) guidance and does not take into account the background concentrations as it is noted that background concentrations are less important in determining the severity of impact for short term concentrations.

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The IAQM (2017) guidance states that it is likely that a ‘medium’ or ‘high’ impact will give rise to a significant effect. The significance of the effect is determined based on professional scientific judgement, taking into account the severity of the impact, the extent of exposure, and the influence and validity of any assumptions made.

The IAQM (2017) guidance does not provide any descriptors for averaging periods of between 1 hour and a year. Therefore, for these periods the EA (2016) criteria have been used, which state 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."

Where an impact cannot be screened out as "insignificant" based on the outputs of the initial screening and modelling, the significance of the effect is determined based on professional scientific judgement of the likelihood of emissions causing an exceedance of an AQAL. This is a standard approach which allows the risk and likelihood of exceedance to be investigated and assessed in detail, following the first stage assessment.

For environmental permitting, consultation with the Environment Agency has revealed that if the long-term predicted environmental concentration (PEC) is below 70% of the AQAL, or the short-term process contribution is less than 20% of the headroom3 it can be concluded that “there is little risk of the PEC exceeding the AQAL”, and the impact can be considered to be ‘not significant’.

In addition, the Environment Agency guidance document 'Guidance on assessing group 3 metals stacks emissions from incinerators - V.4 June 2016' for assessing the impact of emissions of metals relative to their respective AQALs states that where the process contribution (PC) for any metal exceeds 1% of the long term or 10% of the short term environmental standard (in this case the AQAL), this is considered to have potential for significant pollution. Where the PC exceeds these criteria, the PEC should be compared to the environmental standard. The PEC can be screened out where the PEC is less than the environmental standard. Where the impact is within these parameters it can be concluded that there is no risk of exceeding the AQAL and, as such, the magnitude of change and significance of effect is considered negligible.

For those substances which have the potential to accumulate in the environment, Tolerable Daily Intakes (TDI) (the amount of contaminant which can be ingested daily over a lifetime without appreciable health risk), and Index Doses (ID) (a level of exposure which is associated with a negligible risk to human health) are defined. Where the impact of process emissions is within these levels, emissions are expected to make a negligible impact on human health.

The IAQM (2017) guidance specifically states that it is not designed for assessing the impact at ecological sites. In lieu of any specific guidance for planning, the Environment Agency's guidance has been applied. This approach is considered appropriate as the EfW plant and HTI will also require an Environmental Permit to operate.

The Environment Agency's Operational Instruction documents explain how to assess atmospheric emissions from new or expanding Integrated Pollution Prevention and Control (IPPC) regulated industry applications, issued under the Environmental Permitting Regulations at ecologically sensitive sites. The process to follow to satisfy the requirements of the Conservation of Habitats and Species Regulations 2017 (as amended), Countryside and Rights of Way (CRoW) Act 2000, and the Environment Agency's wider duties under the Environment Act 1995 and the Natural Environment and Rural Communities Act 2006 (NERC06) are outlined.

3 Calculated as the AQAL minus twice the long-term background concentration

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Operational Instruction 67_12 "Detailed assessment of the impact of aerial emissions from new or expanding IPPC regulated industry for impacts on nature conservation"

Table 13: Ecological Screening Criteria

Threshold European Sites SSSIs NNR, LNR, LWS, ancient woodland

Y (% threshold long-term) 1 1 100

Y (% threshold short-term) 10 10 100

Z (% threshold) 70 70 100

NOTES:

Short term considers both daily and weekly.

SSSI – Site of Special Scientific Interest

NNR – National Nature Reserve

LWS – Local Wildlife Site

Where:

• Y is the long term process contribution (PC) calculated as a percentage of the relevant Critical Level or Load; and

• Z is the long term PEC calculated as a percentage of the relevant Critical Level or Load.

Operational Instruction 67-12 states if:

• PC is less than Y% Critical Level and Load then emissions from the application are not significant, and

• PEC is less than Z% Critical Level and Load it can be concluded 'no likely significant effect' (alone and in-combination).

AQTAG 17 - "Guidance on in combination assessments for aerial emissions from EPR permits" states that:

"Where the maximum process contribution (PC) at the European site(s) is less than the Stage 2 de-minimis threshold of the relevant critical level or load [i.e. the criteria detailed in Table 13.13 above], the PC is considered to be inconsequential and there is no potential for an alone or in-combination effects with other plans and projects."

This assessment has been undertaken using the ADMS 5.2 dispersion model and the five most recent years for which weather data is available. Full details of the dispersion modelling methodology and inputs can be found in section 5.2. The model has been used to predict the ground level concentration of pollutants on a long and short-term basis across a grid of points. It has also been used to predict the concentration at specified points to present sensitive receptors.

For some pollutants which accumulate in the environment, inhalation is only one of the potential exposure routes. Therefore, other exposure routes have been considered. A detailed Human Health Risk Assessment has been carried out using the Industrial Risk Assessment Program-Human Health (IRAP-h View - Version 5.0). The programme, created by Lakes Environmental, is based on the United States Environment Protection Agency (USEPA) Human Health Risk Assessment Protocol. This Protocol is a development of the approach defined by Her Majesty's Inspectorate for Pollution (HMIP) in 1996, taking account of further research since that date. Full details of the modelling methodology and inputs can be found in the separate Human Health Risk Assessment report.

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3.3.2 Plume Visibility

There is the potential for the plume to be visible under certain circumstances. This is caused by water vapour in the exhaust gases condensing as the exhaust gases cool, so that the plume appears visible. However, the water vapour in the gases mix with the ambient air as the plume disperses, so that the plume ceases to be visible once the water vapour content is low enough. If the exhaust gases are hot and dry, or if the weather conditions promote rapid dispersion and slow cooling, it is more likely that the water vapour will disperse before it condenses, so that the plume is not visible at all.

ADMS 5.2 includes a plume visibility module, which models the dispersion and cooling of water vapour and predicts whether the plume will be visible, based on the liquid water content of the plume. This module has been used to quantify the number of visible plumes likely to occur during the operation of the EfW and HTI facility.

A previous version of Environment Agency guidance note H1 – July 2003 - provided a methodology to quantify the potential impact from visible plumes. This methodology has not been incorporated into the latest version of the Environment Agency’s guidance. However, in lieu of any other appropriate methodology this has been used for the purpose of this assessment. The criteria against which the results of the dispersion modelling can be assessed are detailed in the following table. A ‘medium’ or ‘high’ impact is likely to give rise to a significant effect.

Table 14: Summary of Qualitative Plume Visibility Assessment Criteria

Impact Qualitative Description

Zero No visible impacts resulting from the operation

Insignificant Plume length exceeds boundary <5% of the daylight hours per year

No local sensitive receptors

Low Plume length exceeds boundary <5% of the daylight hours per year

Sensitive local receptors

Medium Plume length exceeds boundary >5% of the daylight hours per year


High Plume length exceeds boundary >25% of the daylight hours per year with obscuration


3.4 Traffic Emissions Assessment In order to assess the impact of the operational phase traffic, dispersion modelling has been undertaken using the ADMS-Roads model version 4.1. Full details of the methodology are presented in Section 5.2.

The maximum impact has been modelled using the same five years of meteorological data used for the process emissions modelling. Vehicles have been modelled at the following speeds, with the exception of slow-down sections within 50 m of major junctions which have been modelled at 20 kph for all vehicles:

• Site access: 20 kph;

• A4 London Road West of Colnbrook Bypass: 64 kph;

• A4 London Road (Colnbrook Bypass): 80kph.

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The modelling has been undertaken assuming that vehicle emissions do not vary throughout the day. This is conservative as the majority of development-generated traffic occurs during daylight hours, when conditions are typically more conducive to dispersion of pollutants from road traffic. Emissions factors appropriate to the assessment years have been taken from the Department for Environment Food and Rural Affairs (DEFRA) Emissions Factor Toolkit (EFT) version 9.0.

The background concentrations of nitrogen dioxide for the assessment of traffic emissions have been taken from the DEFRA mapped background concentrations for the grid square of each receptor. Further details of the basis of the mapped background concentrations is provided in Section 4.1.1.

Model verification has been undertaken in accordance with the methodology prescribed by DEFRA is the guidance document ‘Local Air Quality Management -Technical Guidance (TG)16, which was last updated in February 2018. Details of the model verification procedure are provided in Appendix B.

Assessment of the impact of traffic emissions has been undertaken with reference to the IAQM criteria detailed in Table 12.

3.5 Significance of effect For the purpose of this assessment, the IAQM and EA criteria outlined above have been used to define the magnitude of change associated with the Facility. In accordance with IAQM 2017 guidance, professional judgement has then been used to determine the overall significance of effect of the development at receptor locations (i.e. as either ‘significant’ or ‘not significant’). This judgement has considered:

• the existing air quality in the local area;

• the extent of the predicted impacts from the proposed development; and

• the influence and validity of the assumptions adopted in the dispersion modelling.

The IAQM 2017 guidance states that:

“In most cases, the assessment of impact severity for a proposed development will be governed by the long-term exposure experienced by receptors and it will not be a necessity to define the significance of effects by reference to short-term impacts. The severity of the impact will be substantial when there is a risk that the relevant AQAL for short-term concentrations is approached through the presence of the new source, taking into account the contribution of other prominent local sources.”

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4 Baseline Conditions Reference should be made to Figure 1 in Appendix A which shows the site location and boundary of the Proposed Development. In this chapter we have reviewed the baseline air quality and defined appropriate baseline concentrations to be used in the EIA. We have also identified sensitive receptors in the area.

4.1 Baseline Concentrations

4.1.1 National modelling – mapped background data

In order to assist local authorities with their responsibilities under Local Air Quality Management, the DEFRA provides modelled background concentrations of pollutants across the UK on a 1 km by 1 km grid. This model is based on known pollution sources and background measurements and is used by local authorities in lieu of suitable monitoring data. Mapped background concentrations have been downloaded for the grid squares containing the Proposed Development and immediate surroundings. In addition, mapped atmospheric concentrations of ammonia are available from DEFRA via the National Environment Research Council (NERC) Centre for Ecology and Hydrology (CEH) throughout the UK on a 5 km by 5 km grid.

The mapped background data is calibrated against monitoring data. For instance, the 2015 mapped background concentrations are based on 2015 meteorological data and are calibrated against monitoring undertaken in 2015. As a conservative approach where mapped background data is used the concentration for the year against which the data was validated has been used. This eliminates any potential uncertainties over anticipated trends in future background concentrations.

It is noted that concentrations will vary over the modelling domain area. Therefore, the maximum mapped background concentration within the modelling domain has been calculated as presented in Table 15, together with the concentration at the Proposed Development site. The concentrations of nitrogen dioxide in each square surrounding the Proposed Development are shown in Figure 2, which shows that mapped background concentrations in the closer squares are below the maximum.

Table 15: Mapped Background Data

Pollutant Annual Mean Concentration (µg/m³) Dataset

At Proposed Development

Max Within Modelling

Domain

Nitrogen dioxide 31.3 44.3 DEFRA 2015 Dataset

Oxides of nitrogen 48.9 86.5 DEFRA 2015 Dataset

Sulphur dioxide 4.0 33.0 DEFRA 2001 Dataset

Particulate matter (as PM10) 17.0 18.0 DEFRA 2015 Dataset

Particulate matter (as PM2.5) 11.0 11.6 DEFRA 2015 Dataset

Carbon monoxide 456 506 DEFRA 2001 Dataset

Benzene 0.88 1.0 DEFRA 2001 Dataset

1,3-butadiene 0.41 0.6 DEFRA 2001 Dataset

Ammonia 1.7 1.7 DEFRA (CEH) 2014

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4.1.2 AURN and LAQM monitoring data

The UK Automatic Urban and Rural Network (AURN) is a country-wide network of air quality monitoring stations operated on behalf of the DEFRA. This includes automatic monitoring of oxides of nitrogen, nitrogen dioxide, sulphur dioxide, ozone, carbon monoxide and fine particulate matter.

The closest AURN monitoring stations to the Proposed Development are:

• London Hillingdon, a suburban background site located approximately 3.1 km to the east of the Proposed Development; and

• London Harlington, an urban background site located approximately 4.4 km east of the Proposed Development.

In addition to the AURN site, three continuous analysers are operated by local authorities within 5 km of the Proposed Development.

• Slough Colnbrook, an urban background site located 1.3 km south of the Proposed Development;

• Slough Lakeside 1, an urban background site located 0.8 km south of the Proposed Development; and

• Slough Lakeside 2, an urban background site located 0.7 km south of the Proposed Development.

The monitoring results from these five stations are shown below.

Table 16: Summary of Continuous Monitoring Results

Site Name 2014 2015 2016 2017 2018 Average

Annual Mean Nitrogen Dioxide (µg/m3)

London Hillingdon 58.0 52.0 52.0 53.0 48.4 52.7

London Harlington 36.0 32.0 34.0 32.0 30.3 32.9

Slough Colnbrook 31.0 29.0 29.0 25.0 22.0 27.2

Slough Lakeside 2 34.0 29.0 32.0 26.0 27.0 29.6

Annual Mean PM10 (µg/m3)

Slough Colnbrook 20.0 20.0 15.0 16.0 - 17.8

Slough Lakeside 1 19.3 18.7 14.0 14.0 - 16.5

Slough Lakeside 2 13.2 13.9 15.0 14.0 - 14.0

Annual Mean PM2.5 (µg/m3)

Slough Colnbrook 7.2 7.0 6.0 7.0 - 6.8

Slough Lakeside 1 8.6 7.1 6 6 - 6.9

Slough Lakeside 2 7.3 5.2 6.0 7.0 - 6.4

Slough Borough Council, South Buckinghamshire District Council and London Borough of Hillingdon all operate networks of diffusion tubes to measure nitrogen dioxide, listed in Table 17. The results of all measurements within 5 km of the Proposed Development which were operational at some point after 2014 are shown in

Table 18. Most of the diffusion tubes are located close to busy roads, which will not be representative of background locations.

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As there is a lot of data, the locations of the monitoring stations and the average concentrations for 2014-2018 are shown in Figure 3, with the measured and mapped concentrations closer to the Proposed Development shown in Figure 4. This shows that the maximum measured nitrogen dioxide concentration closest to the plant on Old Slade Lane, Iver (SB1) is below the AQAL at 27.5 µg/m3. The concentrations further north, along Richings Way, are at or close to the AQAL of 40 µg/m3 and then they fall away again, but these are measured at roadside tubes.

The background concentration has been taken as the measured concentration at SB1, as this is the most representative tube. However, the background concentration closer to main roads will be higher and this will be considered for each receptor.

Table 17: Summary of Diffusion Tubes

Site Name Reference Grid Reference Type*

Distance (km)

Bearing (°) X Y

Heathrow Close HD61 504848 176770 R 1.95 132

Harmondsworth Green HD60 505753 177760 R 2.38 97

49 Zealand Avenue Lamp Post

HD200 505920 177188 R 2.68 109

28 Pinglestone Close HD65 506081 177071 R 2.87 110

AURN Sipson HD31 506951 178605 R 3.60 81

1 Porters Way HD205 506503 179510 B 3.43 65

7 Bomber Close HD59 507294 177322 R 3.97 101

31 Tavistock Road HD67 505729 180290 R 3.23 46

4 Colham Avenue HD51 506334 180266 R 3.68 53

104 Yiewsley High Street HD204 506108 180493 B 3.64 48

5-7 Mulberry Crescent HD206 507141 179628 B 4.06 67

35 Emden Close HD207 507580 179812 R 4.54 67

Brendan Close HD58 508412 177124 R 5.11 101

25 Cranford Lane, Harlington

HD57 508756 177717 R 5.38 94

10 West End Lane HD213 508773 177352 B 5.43 98

Lakeside Road* (Grundon)

SLO12 503877 177459 I 0.78 141

Pippins SLO14/15/16 503542 176827 S 1.25 173

Colnbrook By-pass SLO7 503196 177349 I 0.74 195

Elbow Meadows SLO13 503856 176538 S 1.60 163

Horton Road (Caravan Park)

SLO17 503136 175654 S 2.42 186

Rogans (Colnbrook by-pass)

SLO28 501941 177633 R 1.51 253

Brands Hill (B) SLO32 501853 177620 R 1.60 254

Brands Hill SLO18 501798 177659 R 1.64 256

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Site Name Reference Grid Reference Type*

Distance (km)

Bearing (°) X Y

Sutton Lane SLO56 502241 178679 R 1.30 298

London Road SLO10 501733 177725 R 1.69 258

London Road (B) SLO39 501734 177733 R 1.69 259

London Road (C) SLO45 501658 177781 R 1.76 261

Torridge Road SLO11 501637 177999 S 1.76 268

Tweed Road SLO9 501501 177879 O 1.90 264

Parlaunt Road SLO55 503690 179278 K 1.74 301

Grampian Way SLO8 501382 178101 O 2.01 271

High Street Langley (A) SLO53 503936 180547 R 2.30 289

Ditton Road SLO19 503972 179701 R 2.55 266

High Street Langley (B) SLO54 501256 179067 R 2.36 295

Langley Road SLO51 501014 179316 R 2.69 298

Station Road SLO52 501161 179538 R 2.67 303

Iver, Old Slade Lane SB1 503679 178586 R (B) 0.60 29

Richings Way SB21 503690 179278 R 1.25 14

Tower Arms Thorney Lane Sth

SB32 504047 179475 R 1.56 25

Tower Arms Thorney Lane Sth

SB33 504047 179475 R 1.56 25

Thorney Lane South SB22 503972 179701 R 1.74 20

Grand Union House SB38 503618 180518 R 2.46 5

Thorney Lane North SB23 503936 180547 R 2.54 12

Iver, Victoria Crescent SB2 504056 180901 R 2.91 13

6 Thorney Lane North SB30 503924 181127 R 3.11 10

6 Thorney Lane North SB31 503924 181127 R 3.11 10

Swan Pub, Iver SB28 503899 181199 R 3.18 9

Swan Pub, Iver SB29 503899 181199 R 3.18 9

Langley Park Road SB24 503050 181176 R 3.13 354

Iver, High Street SB3 503688 181299 R 3.25 5

Bangors Road South SB25 503604 181378 R 3.32 4

Notes: *B = Background, R = Roadside, K = Kerbside, I = Industrial, S = Suburban, O = Other

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Table 18: Summary of Diffusion Tube Results

Site Name 2014 2015 2016 2017 Average

HD61 36.9 34.4 31.9 34.0 34.3

HD60 31.6 26.8 24.2 27.8 27.6

HD200 40.4 35.2 29.4 42.7 36.9

HD65 33.7 29.9 26.7 30.0 30.1

HD31 46.8 40.7 34.3 45.3 41.8

HD205 41.5 41.1 35.9 37.9 39.1

HD59 33.3 29.1 30.3 32.6 31.3

HD67 30.4 28.7 25.8 26.9 28.0

HD51 36.3 33.3 32.3 32.9 33.7

HD204 39.3 40.9 32.0 37.0 37.3

HD206 34.6 30.0 29.6 34.7 32.2

HD207 37.7 31.2 24.9 33.3 31.8

HD58 39.5 37.2 34.2 47.5 39.6

HD57 39.5 35.6 35.5 39.4 37.5

HD213 39.4 37.0 37.4 45.6 39.9

SLO12 45.4 42.9 44.3 38.6 42.8

SLO14/15/16 30.3 29.9 30.8 26.0 29.3

SLO7 39.0 39.1 38.7 38.7 38.9

SLO13 37.9 34.9 35.9 30.5 34.8

SLO17 33.4 30.0 30.0 25.6 29.8

SLO28 50.9 56.3 58.1 45.3 52.7

SLO32 42.1 40.1 39.3 36.3 39.5

SLO18 53.1 61.1 63.7 55.2 58.3

SLO56 - - 43.9 37.8 40.9

SLO10 51.2 48.3 52.3 45.3 49.3

SLO39 38.6 37.1 37.0 33.1 36.4

SLO45 36.6 33.5 32.7 31.4 33.5

SLO11 36.3 36.9 37.3 32.7 35.8

SLO9 39.0 35.6 37.4 35.3 36.8

SLO55 - - 36.9 31.4 34.2

SLO8 42.4 40.0 41.3 40.4 41.0

SLO53 - - 48.6 42.1 45.4

SLO19 38.8 41.1 40.0 34.6 38.6

SLO54 - - 39.6 35.4 37.5

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Site Name 2014 2015 2016 2017 Average

SLO51 - - 42.8 37.8 40.3

SLO52 - - 41.5 36.4 39.0

SB1 30.0 26.0 27.0 26.9 27.5

SB21 - - 38.0 39.0 38.5

SB32 - - - 40.9 40.9

SB33 - - 34.0 33.6 33.8

SB22 - - - 26.8 26.8

SB38 - - 35.0 35.0 35.0

SB23 33.0 28.0 30.0 26.9 29.5

SB2 - - - 46.5 46.5

SB30 - - - 44.1 44.1

SB31 - - - 41.4 41.4

SB28 - - - 37.7 37.7

SB29 - - 28.0 30.7 29.3

SB24 31.0 31.0 32.0 30.9 31.2

SB3 - - 27.0 30.2 28.6

SB25 42.0 38.0 40.0 42.1 40.5

For particulate matter (as PM10 and PM2.5), the maximum measured concentrations closest to the plant at the Slough-Lakeside 2 continuous monitoring station are below the AQALs at 15.0 µg/m3 and 7.3 µg/m3 for PM10 and PM2.5 respectively. For the purpose of this analysis the maximum monitored PM10 and PM2.5 concentrations from Slough-Lakeside 2 continuous monitoring station has been used as the baseline concentration in this assessment. However, the background concentration closer to main roads will be higher and this will be considered for each receptor.

4.1.3 National monitoring data

4.1.3.1 Hydrogen chloride

Hydrogen chloride is measured on behalf of DEFRA as part of the UK Eutrophying and Acidifying Atmospheric Pollutants (UKEAP) project. This consolidates the previous Acid Deposition Monitoring Network (ADMN), and National Ammonia Monitoring Network (NAMN). There are no monitoring locations within 10 km of the Proposed Development. A summary of data from all UK monitoring sites is presented in Table 19. The UK ceased monitoring of hydrogen chloride at the end of 2015.

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Table 19:National Monitoring – Hydrogen Chloride

Site Type Quantity AQAL Annual Mean Concentration (µg/m³)

2012 2013 2014 2015 2016

All Min - 0.11 0.15 0.10 0.12 -

Max 0.49 0.50 0.54 0.71 -

Average 0.27 0.31 0.26 0.24 -

In lieu of any local monitoring, the UK maximum from the national monitoring network has been used for the purpose of this assessment as a conservative estimate (0.71 µg/m3 – 2015). The choice of baseline concentration will be considered further if the impact of the Proposed Development cannot be screened out as negligible irrespective of baseline concentrations – i.e. the long-term process contribution is greater than 0.5% of the AQAL.

4.1.3.2 Hydrogen fluoride

Baseline concentrations of hydrogen fluoride 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 halides in ambient air for protecting human health against acute irritancy effects’ contains some estimates of baseline levels, reporting that measured concentrations have been in the range of 0.036 µg/m3 to 2.35 µg/m3.

In lieu of any local monitoring, the maximum measured baseline hydrogen fluoride concentration (2.35 µg/m³) has been used for the purpose of this assessment as a conservative estimate. The choice of baseline concentration will be considered further if the impact of the Proposed Development cannot be screened out as negligible irrespective of baseline concentrations – i.e. the long-term process contribution is greater than 0.5% of the AQAL.

4.1.3.3 Ammonia

Ammonia is also measured as part of the UKEAP project. There are no UKEAP monitoring locations within 10 km of the Proposed Development. A summary of data from all UK monitoring sites is presented in the following table.

Table 20: Ammonia Monitoring – UKEAP

Site Quantity AQAL (µg/m³)

Annual Mean Concentration (µg/m³)

2011 2012 2013 2014 2015

All Min 180 0.1 0.1 0.1 0.1 0.1

Max 180 7.7 7.2 8.5 5.5 5.5

Average 180 2.1 1.5 1.7 1.5 1.7

In lieu of any UKEAP monitoring, the maximum mapped background over the modelling domain has been used for the purpose of this assessment, noting that this may be an overestimation. The choice of baseline concentration will be considered further if the impact of the Proposed Development cannot be screened out as negligible irrespective of baseline concentrations – i.e. the long-term process contribution is greater than 0.5% of the AQAL.

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4.1.3.4 Volatile Organic Compounds

As part of the Automatic and Non-Automatic Hydrocarbon Network, benzene concentrations are measured at sites co-located with the AURN across the UK. In 2007, due to low monitored concentrations of 1,3-butadiene at non-automatic sites, DEFRA took the decision to cease non-automatic monitoring of 1,3-butadiene.

There are no monitoring locations within 10 km of the Proposed Development.

In lieu of any local monitoring of benzene or 1,3-butadiene, the maximum mapped background concentration within the modelling domain has been used as the baseline concentration for the purpose of this assessment. The choice of baseline concentration will be considered further if the impact of the Proposed Development cannot be screened out as negligible irrespective of baseline concentrations – i.e. the long-term process contribution is greater than 0.5% of the AQAL.

4.1.3.5 Metals

Metals are measured as part of the Rural Metals and UK Urban/Industrial Networks (previously the Lead, Multi-Element and Industrial Metals Networks). There are no metals monitoring locations within 10 km of the Proposed Development. It is considered that the urban background monitoring sites are likely to be most like the conditions close to the Proposed Development. A summary of data from all UK urban background monitoring sites is presented in Table 21.

Table 21: Metals Monitoring - Average of all Urban background Sites

Substance Annual Mean Concentration (ng/m³) Max (as % of

AQAL) AQAL 2013 2014 2015 2016 2017

Arsenic 3 0.59 0.66 0.79 0.73 0.74 26.47%

Cadmium 5 0.20 0.20 0.26 0.19 0.20 5.14%

Chromium 5000 3.27 7.76 8.48 13.16 9.25 0.26%

Copper 10000 7.82 8.26 11.10 10.40 10.37 0.11%

Mercury 250 2.25 2.09 3.69 2.54 2.47 1.47%

Manganese 150 6.26 8.54 10.90 8.77 8.26 7.27%

Nickel 20 1.96 2.86 6.61 5.95 5.29 33.03%

Lead 250 8.39 9.65 10.35 9.70 8.30 4.14%

Vanadium 5000 1.15 1.24 1.55 0.92 0.92 0.03%

Antimony* 5000 0.00%

Cobalt - 0.17 0.20 0.25 0.23 0.25 -

*Notes: Antimony is not monitored at any urban background sites. The average across all UK monitoring sites has been used.

4.1.3.6 Dioxins, furans and polychlorinated biphenyl (PCBs)

Dioxins, furans and PBCs are monitored on a quarterly basis at a number of urban and rural stations in the UK as part of the Toxic Organic Micro Pollutants (TOMPs) network. There are no monitoring locations within 10 km of the Proposed Development.

A summary of dioxin and furan and PCB concentrations from all monitoring sites across the UK is presented in Table 22 and Table 23.

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Table 22:TOMPS – Dioxin and Furans Monitoring

Site Annual Mean Concentration (fgTEQ/m³)

2012 2013 2014 2015 2016

Auchencorth Moss 0.13 0.85 0.01 0.01 0.18

Hazelrigg 8.75 2.03 2.59 5.29 3.10

High Muffles 4.33 0.60 1.09 0.54 4.40

London Nobel House 15.45 3.50 2.87 4.35 18.67

Manchester Law Courts 33.00 10.20 16.95 5.95 8.67

Weybourne 9.25 2.33 1.62 1.42 20.37

Table 23:TOMPS – PCB Monitoring

Site Annual Mean Concentration (pg/m³)

2012 2013 2014 2015 2016

Auchencorth Moss 10.46 10.48 22.96 24.30 25.90

Hazelrigg 28.78 28.78 25.90 41.48 21.92

High Muffles 13.74 13.75 26.02 33.12 33.17

London Nobel House 83.20 83.20 107.04 121.17 118.40

Manchester Law Courts 101.72 101.73 127.46 97.74 99.60

Weybourne 19.54 19.53 16.97 20.92 41.88

As shown, the concentrations vary significantly between sites and years. As no site is located in close proximity to the Development, the maximum monitored concentration has been used as the background concentration within this assessment (33.00 fg/TEQ/m³ for dioxins and furans and 127.46 pg/m³ for PCBs). The choice of baseline concentrations will be considered further if the impact of the Proposed Development cannot be screened out as negligible irrespective of baseline concentrations – i.e. the long-term process contribution is greater than 0.5% of the AQAL.

4.1.3.7 Polycyclic Aromatic Hydrocarbons (PAHs)

Polycyclic Aromatic Hydrocarbons (PAHs) are monitored at a number of stations in the UK as part of the PAH network. There are no monitoring locations within 10 km of the Proposed Development. For the purpose of this assessment, benzo(a)pyrene is considered as this is the only PAH which an AQAL has been set. A summary of benzo(a)pyrene concentrations from all monitoring sites within the UK is presented in Table 24.

Table 24: National Monitoring - Benzo(a)pyrene

Site Type Quantity AQAL Annual Mean Concentration (ng/m³)

2013 2014 2015 2016 2017

Urban background

Min 0.25 0.05 0.04 0.03 0.03 0.03

Max 3.87 3.72 3.50 1.30 0.87

Average 0.48 0.49 0.37 0.34 0.26

As shown, there is an exceedance of the AQAL for BaP across the UK urban background sites in all years. However, The Fourth Daughter Directive outlines target assessment thresholds for benzo(a)pyrene of 1.0 ng/m³ total content in the PM10 fraction averaged over a calendar year, with

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an upper assessment threshold of 0.6 ng/m³ and a lower assessment threshold of 0.4 ng/m³. In all years the average at a background site is less than the Fourth Daughter Directive assessment threshold.

In lieu of any local monitoring of PAHs, the maximum of the UK average concentrations has been used (0.49 ng/m³ – 2014). It is noted that this exceeds the AQAL. The choice of baseline concentration will be considered further if the impact of the Development cannot be described as negligible irrespective of the total concentration.

4.2 Summary The preceding sections have provided a review of the baseline local and national monitoring data and national modelled background concentrations. Table 25 presents the values for the annual baseline concentrations that have been used to evaluate the impact of the Proposed Development as part of this assessment.

Table 25: Summary of Baseline Concentrations

Pollutant Annual Mean Concentration

Units Source

Nitrogen dioxide 27.5 µg/m³ Maximum monitored concentration - Old Slade Lane, Iver diffusion tube

Sulphur dioxide 33.0 µg/m³ Maximum mapped background concentration from across the modelling domain – DEFRA 2001 dataset.

Particulate matter (as PM10)

15.0 µg/m³ Maximum monitored concentration -Slough-Lakeside 2 continuous monitoring station

Particulate matter (as PM2.5)

7.3 µg/m³ Maximum monitored concentration - Slough-Lakeside 2 continuous monitoring station

Carbon monoxide 506 µg/m³ Maximum mapped background concentration from across the modelling domain – DEFRA 2001 dataset

Benzene 1.0 µg/m³ Maximum mapped background concentration from across the modelling domain – DEFRA 2001 dataset

1,3-butadiene 0.6 µg/m³ Maximum mapped background concentration from across the modelling domain – DEFRA 2001 dataset

Ammonia 1.7 µg/m³ Maximum mapped background concentration from across the modelling domain – DEFRA (CEH) 2014

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Pollutant Annual Mean Concentration

Units Source

Hydrogen chloride 0.7 µg/m³ Maximum monitored concentration across the UK 2011 to 2015

Hydrogen fluoride 2.3 µg/m³ Maximum measured concentration from EPAQS report

Mercury 3.7 ng/m³ Maximum average annual monitored concentration across all UK urban background sites 2013 to 2017

Cadmium 0.26 ng/m³

Dioxins and Furans 33.0 fFg ITEQ /m³

Maximum monitored across the UK 2012 to 2016

Dioxin-like PCBs 127.5 pg/m³

PaHs 0.49 ng/m³ Maximum of the UK average concentrations

Arsenic 0.79 ng/m³ Maximum monitored concentration at all urban background sites across the UK 2013 to 2017

Antimony - ng/m³

Chromium 13.16 ng/m³

Cobalt 0.25 ng/m³

Copper 11.10 ng/m³

Lead 10.35 ng/m³

Manganese 10.90 ng/m³

Nickel 6.61 ng/m³

Vanadium 1.55 ng/m³

4.3 Sensitive Receptors As part of this assessment, the predicted process contributions at a number of sensitive receptors has been evaluated.

4.3.1 Dust Sensitive Receptors

The following table outlines how many sensitive receptor locations have been identified in the relevant distance bands from the boundary of the Site and construction compound. For clarity, the IAQM methodology states that one residential unit is one high sensitivity receptor. No potentially dust sensitive ecological receptors have been identified in the relevant screening distances from the Site. The Old Slake Lake LWS lies to the east of the Site; however this lies more than 50 m from the Site boundary at the closest point. Therefore, impact of the construction phase of the Proposed Development on ecological receptors is not considered further.

Table 26: Dust Sensitive Receptors - Number of Human Receptors

Distance from the source (m)

Estimated number of human receptors

From Site Boundary From Site Access Routes*

Receptor Sensitivity High Medium High Medium

<20 0 0 0 4

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Distance from the source (m)

Estimated number of human receptors

From Site Boundary From Site Access Routes*

<50 0 0 0 8

<100 0 1 - -

<350 0 2 - -

Note:

*Distance from site access routes is used in the assessment of trackout, and only receptors within 50m of the edge of the road (up to 500m from the Site entrance) need to be considered.

4.3.2 Vehicle Emission Sensitive Receptors

The roadside human sensitive receptors (labelled as Roads Receptors, RRs) along the roads for which traffic data is available (see Section 5.2) are listed in Table 27 and displayed in Figure 6 of appendix A [Roads Modelling Setup].

Table 27: Vehicle Sensitive Receptors

ID Name Location

x y

RR1 2 Colnbrook Bypass 505352 177099




RR5 8 Orchard Court, the Island 505075 177097

RR6 Disraeli Court, London Road 501736 177731

RR7 540 London Road 501662 177732

RR8 563 London Road 501632 177792

RR9 2 Laburnum Grove 501552 177801

RR10 2 Tweed Road 501539 177846

4.3.3 Process Emission Sensitive Receptors

The human sensitive receptors included in this assessment are listed in Table 28 and displayed in Figure 5 of appendix A [Human Sensitive Receptors].

Table 28: Human Sensitive Receptors

ID Name Location Distance from the stack (m) x y

R1 Old Slade Lane 1, Richings Park 503732 178404 482



R4 Main Drive, Richings Park 503282 179033 976

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ID Name Location Distance from the stack (m) x y

R5 North Park, Richings Park 503018 179083 1086

R6 Sutton Lane 1, Langley 502272 178911 1404

R7 Sutton Lane 2, Langley 502424 178468 1048

R8 London Road, Colnbrook 501993 177564 1484

R9 Vicarage Way, Colnbrook 502680 177297 1045

R10 The Hawthrorns, Colnbrook 503618 176909 1177

R11 The Island, Longford 505036 177064 1925

R12 Verbena Close, West Drayton 505678 178424 2315

R13 Lily Drive, West Drayton 505588 178837 2329

R14 The Common, West Drayton 505107 178577 1791

R15 Mayfield Park, West Drayton 505169 179072 2044

R16 Thorney Mill Road, Thorney 504785 179368 1909

R17 Richings Way, Richings Park 504037 179425 1507

R18 Parlaunt Park Primary Academy 501849 179291 1971

R19 Foxborough Primary School 501419 178285 1984

R20 Colnbrook CoE School 502604 177047 1285

R21 Harmondsworth Primary School 505572 177500 2253

R22 Laurel Lane Primary School 505971 178915 2717

R23 St Catharine Catholic Primary School

505728 179521 2754

The impacts of emissions from the Proposed Development have been assessed at these receptor locations and are discussed in Section 6.7.

4.3.4 Air Quality Management Areas (AQMAs)

Under Section 82 of the Environment Act (1995) (Part IV), local authorities are required to undertake an ongoing exercise to review air quality within their area of jurisdiction. Slough Borough Council has declared four Air Quality Management Areas (AQMAs) due to concerns over nitrogen dioxide concentrations. Of these, three lie within 5 km of the Proposed Development and have been included in the assessment. A review of AQMAs declared by neighbouring councils has shown that three additional AQMAs lie within 5 km of the Proposed Development. Details of these AQMAs are provided in the table below.

Table 29: AQMAs

AQMA name Reason for declaration Distance from stack at closest point (km)

Bearing

South Borough Council

Slough AQMA No.1

Annual mean nitrogen dioxide 1.5 West

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AQMA name Reason for declaration Distance from stack at closest point (km)

Bearing

Slough AQMA No.2

Annual mean nitrogen dioxide 1.5 South-west

Slough AQMA No.4

Annual mean nitrogen dioxide 4.7 North-West

South Bucks District Council

South Bucks district Council AQMA No. 2

Annual mean nitrogen dioxide 0.1 North

Hillingdon London Council

Hillingdon AQMA Annual mean nitrogen dioxide 1.0 East

Spelthorne Borough Council

Spelthorne AQMA

Annual mean nitrogen dioxide 2.4 South

4.3.5 Ecological Sensitive Receptors

A study was undertaken to identify the following sites of ecological importance in accordance with the Air Emissions Guidance criteria:

• Special Protection Areas (SPAs), Special Areas of Conservation (SACs), or Ramsar sites within 10 km of the stack of the Proposed Development;

• Sites of Special Scientific Interest (SSSIs) within 2 km of the stack of the Proposed Development; and

• National Nature Reserves (NNR), Local Nature Reserves (LNRs), Local Wildlife Sites (LWSs) and ancient woodlands within 2 km of the stack of the Proposed Development.

The sensitive ecological receptors identified as a result of the study are displayed in Figure 8 [Ecological Sensitive Receptors] and listed in Table 30. A review of the citation and APIS website for each site has been undertaken to determine if lichens or bryophytes are an important part of the ecosystem's integrity. If lichens or bryophytes are present, the more stringent Critical Level has been applied as part of the assessment.

Table 30: Sensitive Ecological Receptors

ID Site Designation Closest point to Proposed

Development

Distance from stack at closest point

(km)

Lichens or bryophytes

present

X Y

European and UK Designated Sites

E1 South West London Waterbodies

SPA/Ramsar 502730 175700 2.5 No

E2 Windsor Forest & Great Park

SAC 497500 174150 7.0 Yes

Locally Designated Sites

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ID Site Designation Closest point to Proposed

Development

Distance from stack at closest point

(km)

Lichens or bryophytes

present

X Y

E3 Old Wood Ancient Woodland

503240 178260 0.2 Yes(1)

E4 Old Slade Lake LWS 503730 178160 0.3 Yes(1)

E5 Opposite Iver Station

BNS(2) 503410 179910 Yes(1)

E6 Lower Colne SINC(3) 504890 178180 1.5 Yes(1)

E7 Queen Mother Reservoir

LWS 501700 177463 1.8 Yes(1)

Notes:

(1) It is not known from the citations whether lichens or bryophytes are present at the locally designated sites. As a conservative measure it has been assumed that lichens amd bryophytes are present and the lower Critical Levels presented in Table 3 have been applied.

(2) Biological Notification Site

(3) Site of Importance for Nature Conservation

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5 Effect of proposals during construction

5.1 Dust It is anticipated that construction activities will take place at various locations across the Site. However, as a worst-case assumption, it has been assumed that dust generating activities will occur at the boundary of the Site and construction compound.

The IAQM methodology detailed in Section 3.2 is based on:

• The dust emission magnitude for the Site – which is based on the type of activities undertaken; and

• The sensitivity of the area – which is based on the number of properties within certain distances of the boundary of the works.

5.1.1 Dust emission magnitude

The quantity of dust emitted is related to the area of land being worked and the level of construction activities, in terms of the nature, magnitude and duration of those activities. The wind direction, wind speed and rainfall at the time when a construction activity is taking place will also influence whether there is likely to be a dust impact. Atmospheric conditions which promote adverse impacts can occur in any direction from the Proposed Development. However, adverse impacts are more likely to occur downwind of the prevailing wind direction and / or close to the worked areas. Impacts are also more likely to occur during drier periods as rainfall acts as a natural dust suppressant.

The dust emission magnitude has been classified for each type of activity using the criteria outlined in Table 4:

• Demolition – There are only very minor demolition/removal activities associated with the Proposed Development. As such, demolition impacts have been scoped out of this assessment.

• Earthworks - The total area of the Site is >10,000 m². There will be substantial earthworks involved in the construction of the development platform. On this basis, the dust emission magnitude is deemed to be 'large'.

• Construction - The total building volume will be >100,000m³ and involve potentially dusty activities. As a conservative assumption, the dust emission magnitude is deemed to be 'large'.

• Trackout – The Transport Assessment has identified that peak HGV construction traffic will be around 340 HGV movements in total. Therefore, the dust emission magnitude from trackout is deemed to be 'large'.

5.1.2 Sensitivity of the area

As detailed in Section 4.3.1, no high sensitivity human receptors (i.e. residential dwellings, hospitals or schools) have been identified within the relevant screening distances (i.e. within 350m of the boundary of the Site and construction compound, or within 50m of any route used by construction vehicles on the public highway, up to 500m from the Site entrance).

The medium sensitivity receptors identified are places of work and a golf course, the closest being the industrial premises on the land adjacent to the Proposed Development. The IAQM guidance does not indicate the number of receptors that should represent a place of work. However, according to the criteria, as there are no medium sensitivity receptors within 20 m and no high

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sensitivity receptors in the area, the sensitivity of the area to dust deposition effects should be classed as low.

As shown in Table 9, the sensitivity of the area to human health effects of dust depends on the annual mean PM10 concentration. The annual mean background concentration of PM10 is 15 µg/m³. Using the criteria in Table 9 and taking into account this background concentration, the sensitivity of the area to human health effects is ‘low’ as there are no high sensitivity receptors within 20 m of the Site.

A summary of the sensitivity of the area is provided in the table below.

Table 31: Sensitivity of the Surrounding Area

Potential Impact Earthworks Construction Trackout

Dust deposition Low Low Medium

Human health Low Low Low

5.1.3 Dust impact risk assessment

The risk of dust emissions from a construction site causing loss of amenity and / or health or ecological effects is related to:

• the activities being undertaken (number of vehicles and plant etc.);

• the duration of these activities;

• the size of the site;

• the meteorological conditions (wind speed, direction and rainfall);

• the proximity of receptors to the activity;

• the adequacy of the mitigation measures applied to reduce or eliminate dust; and

• the sensitivity of the receptors to dust.

The risk of dust impacts from construction phase activities is summarised in the following table using the criteria outlined in Section 3.2. This is based on the dust emission magnitude and the sensitivity of the area.

Table 32: Summary of Dust Risk to Define Site Specific Mitigation

Potential Impact Earthworks Construction Trackout

Dust deposition Low Risk Low Risk Medium Risk

Human health Low Risk Low Risk Low Risk

In summary, the Proposed Development has been assessed to be a medium risk site. As the highest risk category is greater than ‘negligible’, site-specific mitigation measures will need to be implemented. Suitable mitigation measures are detailed in Section 7.

5.2 Construction phase traffic emissions

5.2.1 Traffic generation rates

24-hour AADT flows were provided by the Transport Consultant for the baseline year in which traffic surveys were undertaken (2019), along with a growth factor to factor the baseline traffic to be representative of the opening year (2023). The profile of construction traffic flows has also been provided. This profile shows that:

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• peak numbers of HGVs occur in Q4 of year 1 (i.e. Q4 of 2020), with 340 HGV movements, 680 passenger vehicle movements and 2 abnormal loads daily; and

• peak total vehicle movements occur in Q2 of 2021, with 250 HGV movements, 1000 passenger vehicle movements and 6 abnormal loads daily.

The maximum impact of vehicle emissions could occur either during the peak HGV movements or peak total movements. Therefore, both scenarios have been assessed, but only the maximum has been reported. The assessment considers the following scenarios:

• 2021 ‘Do minimum’; and

• 2021 ‘Do something’.

The ‘Do minimum’ scenario represents the traffic in the absence of the Proposed Development (i.e., the future baseline), and has been factored from 2019 survey data using the factor provided by the Transport Consultant. The ‘Do something’ scenario is the future baseline traffic plus the traffic generated by the construction phase of the Proposed Development. Although the peak HGV traffic is predicted to occur in Q4 of 2020 and peak total traffic in Q2 of 2021, for simplicity both have been assessed as occurring in 2021. This is considered conservative as the ‘Do minimum’ traffic flows are slightly higher in 2021 than 2020. The assessment showed that the impact of the peak HGV traffic is greater than the impact of peak total traffic at all receptor locations considered. Therefore, the results for the peak HGV traffic are presented in Section 5.4 below.

The baseline data can be used for model verification purposes. However, the most recent pollutant monitoring data available is from 2017. Therefore, the traffic data has been factored using a growth factor provided by the Transport Consultant to obtain traffic flows representative of 2017. In addition, traffic data has been provided for the Site access road and the A4 Colnbrook Bypass east and west of the Site access, whilst monitoring data available for model verification purposes is mostly from sites located on the A4 London Road west of the Colnbrook Bypass. Therefore, traffic flows for the A4 London Road west of the Colnbrook Bypass for 2017 have been downloaded from the Department for Transport (DfT) website4 for count point 78344 for use in the assessment.

Table 33 shows a summary of the construction phase traffic flows as Annual Average Daily Traffic (AADT) for the above scenarios, and for the development impact (i.e. Do something – Do minimum).

4 https://roadtraffic.dft.gov.uk/#6/55.254/-6.064/basemap-regions-countpoints

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Table 33: Construction Phase Traffic - AADT

Road link 2017 Baseline(1) 2021 Do Minimum 2021 Do Something Development Impact

LDVs HDVs LDVs HDVs LDVs HDVs LDVs HDVs

Site Access 0 0 0 0 680 342 680 342(3)

A4 Colnbrook Bypass east of site access 12,099 3,688 12,583 3,815 12,911 4,005 967 284

A4 Colnbrook Bypass west of site access 12,099 3,688 12,583 3,815 12,934 4,118 1,033 228

A4 London Road west of Colnbrook Bypass(2) 20,542 3,162 20,949 3,225 21,300 3,377 1,033 228

Notes:

(1) Data factored from 2019 to 2017 for use in model verification study using the growth factor provided by Transport Consultant.

(2) Data for A4 London Road west of Colnbrook Bypass obtained from DfT count point 78344 and factored to 2021 flows using the growth factor provided by Transport Consultant.

(3) HGVs generated by the Construction Phase of the Proposed Development includes abnormal loads.

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5.3 Methodology In order to assess the impact of the construction phase traffic, dispersion modelling has been undertaken using the ADMS-Roads model version 4.1. The meteorological and surface characteristics used are the same as those used for the assessment of process emission presented in Section 6.5.2.

Vehicles have been modelled at the following speeds, with the exception of slow-down sections within 50 m of major junctions which have been modelled at 20 kph for all vehicles:

• Site access: 20 kph;

• A4 London Road West of Colnbrook Bypass: 64 kph;

• A4 London Road (Colnbrook Bypass): 80kph.

The modelling has been undertaken assuming that vehicle emissions do not vary throughout the day. This is conservative as the majority of development-generated traffic occurs during daylight hours, when conditions are typically more conducive to dispersion of pollutants from road traffic.

Assessment of the impact of traffic emissions has been undertaken with reference to the IAQM criteria detailed in Table 12.

5.3.1 Emissions factors and background concentrations

Emissions factors have been taken from the Department for Environment Food and Rural Affairs (DEFRA) Emissions Factor Toolkit (EFT) version 9.0. Emissions factors for 2017 have been used for the verification year (2017). Whilst it may be considered appropriate to use 2021 emission factors for the opening year, this relies on projections of reducing average emissions from the vehicle fleet in future years. Therefore, 2019 emissions factors have been used for the 2021 scenarios as a conservative measure, i.e., it is assumed that average emissions will not reduce from current levels.

The background concentrations of nitrogen dioxide for the assessment of traffic emissions have been taken from the 2017 DEFRA mapped background concentrations for the grid square of each receptor. As a conservative measure it has been assumed that background concentrations will not decrease in future years. Further details of the basis of the mapped background concentrations are provided in Section 4.1.1. The mapped background concentrations for each roads receptor are detailed below.

Table 34: Background Concentrations for traffic emissions assessment

Receptor 2017 Mapped Background Concentration (µg/m³)

Nitrogen Dioxide PM10 PM2.5

RR1 2 Colnbrook Bypass 29.35 16.69 11.53




RR5 8 Orchard Court, the Island 29.35 16.69 11.53

RR6 Disraeli Court, London Road 23.79 17.37 12.04

RR7 540 London Road 23.79 17.37 12.04

RR8 563 London Road 23.79 17.37 12.04

RR9 2 Laburnum Grove 23.79 17.37 12.04

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Receptor 2017 Mapped Background Concentration (µg/m³)

Nitrogen Dioxide PM10 PM2.5

RR10 2 Tweed Road 23.79 17.37 12.04

5.3.2 Approach to modelling queueing traffic

A review of typical traffic conditions has been undertaken using Google Maps. This has indicated that during weekdays there is typically heavy queueing along the A4 at the western end of Colnbrook Bypass and on the A4 London Road between the Colnbrook Bypass and the M4. This information has been used to determine representative queue zones for use in the model.

Guidance has been taken from CERC guidance note 60 – Modelling queuing traffic5. This note recommends the following approach:

1. Assume a representative average vehicle length – the project Transport Consultant recommended 5.75 m which is the highways industry standard.

2. Assume that the vehicles are travelling at the slowest speed it is possible to model (5 km/h).

3. Calculate a representative AADT for the queue zones. The AADT can be calculated as:

AADT = [speed(m/hour)/vehicle length(m)] x 24 4. Using the assumed values from (1) and (2), this gives a representative AADT of 20,870 vehicles.

In addition to the above methodology, the following points should be noted:

• The queue zones are either on, off or set to a factor of 0.5 depending upon the hour of the day, based upon the hours of queueing identified from Google Maps traffic data.

• Factoring the queue zones and slow-down phases by 0.5 assumes queue conditions for 50% of the hour factored. This has been used to represent the hours when queueing is present only some of the time, when less severe congestion has been identified either from Google Maps traffic data.

• There is no information as to how queue length or duration will change in future years. Extrapolating from queue length information on Google Maps is not possible. Therefore, the queue lengths and durations are identical in all scenarios.

5.3.3 Roads NOx conversion to NO2

The background NO2 concentrations have been used to convert modelled road contribution of NOx to NO2 in accordance with the methodology outlined in LAQM.TG(16) using the DEFRA NOx to NO2 calculator (version 7.1, April 2019).

When converting from NOx to NO2 the following inputs have been used:

• The year has been taken as the same as the emissions data, i.e. 2017 or 2019 (conservatively selected to assess traffic in 2021) as appropriate;

• The local authority has been selected as “Slough”; and

• The traffic mix has been selected as “All London traffic”.

5 CERC note 60, Modelling queuing traffic, August 2004

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5.3.4 Model verification

Model verification has been undertaken in accordance with the methodology prescribed by DEFRA in the guidance document ‘Local Air Quality Management -Technical Guidance (TG16) (referred to hereafter as LAQM.TG(16)), which was last updated in February 2018. Details of the model verification procedure are provided in Appendix B.

The verification procedure has produced an adjustment factor of 1.3469. This factor has been applied to the modelled road-NOx concentrations. In the absence of any monitoring data for PM10 and PM2.5 suitable for verification, it is considered appropriate to apply the adjustment factor for NOx to concentrations of PM10 and PM2.5.

5.4 Results The impact of vehicle emissions of nitrogen dioxide generated during the construction phase of the Proposed Development is presented in Table 35 below.

Table 35: Construction Phase Annual Mean Nitrogen Dioxide Impact at Roadside Receptors

Receptor 2021 Do Minimum PEC

2021 Do Something PEC

Proposed Development Impact

Magnitude of Change

µg/m³ % of AQAL

µg/m³ % of AQAL

µg/m³ % of AQAL

RR1 35.92 89.80% 36.08 90.20% 0.16 0.40% Negligible*

RR2 36.10 90.25% 36.27 90.68% 0.17 0.42% Negligible*

RR3 36.24 90.60% 36.42 91.05% 0.18 0.45% Negligible*

RR4 36.16 90.40% 36.33 90.83% 0.17 0.43% Negligible*

RR5 31.12 77.80% 31.18 77.95% 0.06 0.15% Negligible*

RR6 36.99 92.48% 37.39 93.48% 0.40 1.00% Negligible

RR7 31.94 79.85% 32.18 80.45% 0.24 0.60% Negligible

RR8 35.56 88.90% 35.85 89.63% 0.29 0.72% Negligible

RR9 31.82 79.55% 32.02 80.05% 0.20 0.50% Negligible

RR10 34.88 87.20% 35.17 87.93% 0.29 0.72% Negligible

Note: * Negligible irrespective of total concentration

The impact of vehicle emissions of particulate matter (as PM10) generated during the construction phase of the Proposed Development is presented in Table 36 below.

Table 36: Construction Phase Annual Mean PM10 Impact at Roadside Receptors




Magnitude of Change

µg/m³ % of AQAL

µg/m³ % of AQAL

µg/m³ % of AQAL

RR1 17.85 44.63% 17.89 44.74% 0.041 0.10% Negligible*

RR2 17.89 44.73% 17.93 44.84% 0.042 0.11% Negligible*

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Magnitude of Change

µg/m³ % of AQAL

µg/m³ % of AQAL

µg/m³ % of AQAL

RR3 17.92 44.80% 17.96 44.91% 0.043 0.11% Negligible*

RR4 17.91 44.78% 17.95 44.89% 0.043 0.11% Negligible*

RR5 17.14 42.86% 17.16 42.91% 0.018 0.04% Negligible*

RR6 18.86 47.16% 18.91 47.27% 0.046 0.12% Negligible*

RR7 18.36 45.90% 18.39 45.97% 0.029 0.07% Negligible*

RR8 19.32 48.30% 19.37 48.44% 0.053 0.13% Negligible*

RR9 18.59 46.49% 18.63 46.57% 0.032 0.08% Negligible*

RR10 19.08 47.69% 19.12 47.81% 0.046 0.11% Negligible*


The impact of vehicle emissions of particulate matter (as PM2.5) generated during the construction phase of the Proposed Development is presented in Table 37 below.

Table 37: Construction Phase Annual Mean PM2.5 Impact at Roadside Receptors




Magnitude of Change

µg/m³ % of AQAL

µg/m³ % of AQAL

µg/m³ % of AQAL

RR1 12.21 48.86% 12.24 48.95% 0.023 0.09% Negligible*

RR2 12.24 48.95% 12.26 49.04% 0.024 0.10% Negligible*

RR3 12.25 49.01% 12.28 49.11% 0.025 0.10% Negligible*

RR4 12.25 48.99% 12.27 49.09% 0.025 0.10% Negligible*

RR5 11.80 47.19% 11.81 47.23% 0.010 0.04% Negligible*

RR6 12.96 51.84% 12.99 51.95% 0.028 0.11% Negligible*

RR7 12.64 50.58% 12.66 50.65% 0.017 0.07% Negligible*

RR8 13.20 52.81% 13.23 52.93% 0.030 0.12% Negligible*

RR9 12.77 51.10% 12.79 51.17% 0.019 0.08% Negligible*

RR10 13.07 52.26% 13.09 52.37% 0.027 0.11% Negligible*


As shown, the impact of construction phase vehicle emissions of nitrogen dioxide at five receptor locations is less than 0.5% of the AQAL and the magnitude of change can be screened out as ‘negligible’ irrespective of the total concentration. At the remaining five receptor locations the impact rounds to 1% of the AQAL and the PEC is less than 94.5% of the AQAL, so the magnitude of change is described as ‘negligible’.

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The impact of construction phase vehicle emissions of particulate matter (as PM10 and PM2.5) at all receptor locations considered is less than 0.5% of the AQAL and the magnitude of change can be screened out as ‘negligible’ irrespective of the total concentration.

As the impact can be described as ‘negligible’ at al receptor locations considered, we conclude that the overall effect of vehicle emissions during the construction phase of the Proposed Development on local air quality will be ‘not significant’.

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6 Effect of proposals during operation

6.1 Selection of model Detailed dispersion modelling was undertaking using the model ADMS 5.2, developed and supplied by Cambridge Environmental Research Consultants (CERC). This is a new generation dispersion model, which characterises the atmospheric boundary layer in terms of the atmospheric stability and the boundary layer height. In addition, the model uses a skewed Gaussian distribution for dispersion under convective conditions, to take into account the skewed nature of turbulence. The model also includes modules to take account of the effect of buildings and complex terrain.

ADMS is routinely used for modelling of emissions for planning and Environmental Permitting purposes to the satisfaction of the Environment Agency and Local Authorities. An analysis of the variation in model outputs has been undertaken and the maximum predicted concentration for each pollutant and averaging period has been used to determine the significance of any potential impacts.

6.2 Emission limits The IED (Directive 2010/75/EU), adopted on 7th January 2013, is the key European Directive which covers almost all regulation of industrial processes in the EU. Within the IED, the requirements of the relevant sector BREF become binding as BAT guidance, as follows.

• Article 15, paragraph 2, of the IED requires that Emission Limit Values (ELVs) are based on best available techniques, referred to as BAT.

• Article 13 of the IED, requires that 'the Commission' develops BAT guidance documents (referred to as BREFs).

• Article 21, paragraph 3, of the IED, requires that when updated BAT conclusions are published, the Competent Authority (in England this is the Environment Agency) has up to four years to revise permits for facilities covered by that activity to comply with the requirements of the sector specific BREF.

The Final Draft Waste incineration BREF was published by the European IPPC Bureau in December 2018. Formal adoption of the BREF is expected in Q3 2019. Upon adoption of the final BREF, the Environment Agency will be required to review and implement conditions within all permits which require operators to comply with the requirements set out in the BREF. This will include the Proposed Development. As currently drafted, the BREF will introduce BAT-Associated Emission Limits (BAT-AELs) which are more stringent than the ELVs currently set out in the IED. It has been assumed that emissions from the Proposed Development will comply with the BAT-AELs, or the emission limits from Annex VI Part 3 of the Industrial Emissions Directive (IED) for waste incineration plants where BAT-AELs are not applicable. As an exception, lower emission limits are proposed for oxides of nitrogen from the EfW plant, due to the sensitivity of the local area, and a lower short term emission limit is proposed for sulphur dioxide.

Slough BC asked for further evidence that the reduced emission limit for oxides of nitrogen can be achieved in practice. The Applicant notes that relatively few plants in Europe are required to achieve an emission limit of 100 mg/Nm3 using SNCR. Existing plants generally have an emission limit of 200 mg/Nm3 with SNCR or 70 mg/Nm3 with SCR. The applicant can provide the following evidence to support the assertion that the proposed emission limits can be achieved on a consistent basis.

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As part of the data gathering exercise to support the new Waste Incineration BREF, emissions data was collected from a variety of energy-from-waste plants across Europe. The data is for plants operating in 2015. This data is published in Annex 8.6 of the draft final WI BREF. Figure 8.15, reproduced below, shows the plants with the lowest NOx emissions (Figures 8.16 and 8.17 show the plants with higher emissions and are therefore not attached). The figure shows, for each plant, the annual average (blue diamond), the highest daily average excluding other than normal operating conditions (“daily fine”, pink circles) and the highest daily average except for maintenance and when the plant is burning support fuel (“daily base”, green triangle). These are explained on page 149 of the draft final WI BREF. Of these, the most relevant is the “daily fine” as this shows the emissions data which are achieved on a consistent basis.

The figure shows that there are at least 9 lines across Europe which achieved annual average emissions of NOx below 100 mg/Nm3 with SNCR only (DE48-1, DE47-1R, DE48-2, DE47-2R, FR019R, DK02-2, IT1-2, IT1-1, FR087-3R) and that for seven of these lines, this emission level was achieved on a daily basis, excluding other than normal operating conditions (the “daily fine” concentration). The seven lines range from 7.5 tph to 320,000 tpa and are considered to be representative of the proposed capacity.

The Applicant also notes that the range of achieved emissions with SNCR is shown in the final draft WI BREF as 80-180 mg/Nm3 (Table 4.31 on page 397). Therefore, the proposed emission limit falls within this range.

The Applicant’s consultant is involved with a number of different proposed energy-from-waste plants and has received proposals from a number of leading technology suppliers. While we cannot provide this information directly, we can confirm that a number of these companies are happy to guarantee a daily emission limit of 100 mg/Nm3 with ammonia slip of 10 mg/Nm3, and we note that these companies would be subject to significant financial penalties if these guarantees are not achieved.

The Applicant considers that this evidence shows that the proposed emission limits have been achieved at a number of European plants, that they are consistent with the draft WI BREF and that

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companies which are developing, selling and guaranteeing this technology are confident that they can be achieved.

6.3 Source and emissions data The principal inputs to the model with respect to the emissions to air from the Proposed Development are presented in Table 38 to Table 40.

Table 38: Stack Source Data, Proposed Development

Item Unit HTI EfW (per line)

Stack Data

Height m 55 55

Internal diameter – effective diameter m 0.86 2.34

Location m, m 503390.9, 178063.5

503390.9, 178063.5

Flue Gas Conditions

Temperature °C 140 140

Exit moisture content % v/v 8.9% 16.08%

Exit oxygen content % v/v dry 13.00% 7.00%

Reference oxygen content % v/v dry 11.00% 11.00%

Volume at reference conditions (dry, ref O2) Nm³/s 4.10 50.50

Volume at actual conditions Am³/s 8.71 64.92

Flue gas exit velocity m/s 15 15.1

Note: The Proposed Development will operate two independent EfW lines as well as the HTI. The data in this table is for each line individually.

Table 39: Stack Emissions Data – Daily Averages

Pollutant Daily or Periodic ELV HTI EfW (per line)

Conc. (mg/Nm³) Release Rate (g/s)

Oxides of nitrogen (as NO2) 120 (HTI), 100 (EfW) 0.492 5.050

Sulphur dioxide 30 0.123 1.515

Carbon monoxide 50 0.205 2.252

Fine Particulate Matter (PM)(1) 5 0.0205 0.2525

Hydrogen chloride 6 0.0246 0.3030

Volatile organic compounds (as TOC)

10 0.410 0.5050

Hydrogen fluoride 1 0.0410 0.0505

Ammonia 10 0.410 0.5050

Cadmium and thallium 0.02 0.082 mg/s 1.010 mg/s

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Mercury 0.02 0.082 mg/s 1.010 mg/s

Other metals(2) 0.3 1.23 mg/s 15.15 mg/s

Benzo(a)pyrene (PaHs)(3) 0.04 µg/Nm³ 0.164 µg/s 2.020 µg/s

Dioxins and furans and PCBs 0.06 ng/Nm³ 0.246 ng/s 3.030 ng/s

Notes: All emissions are expressed at reference conditions of dry gas, 11% oxygen, 273.15K. (1) As a worst-case it has been assumed that the entire PM emissions consist of either PM10 or PM2.5 for comparison with the relevant AQALs. (2) Other metals consist of antimony (Sb), arsenic (As), lead (Pb), chromium (Cr), cobalt (Co), copper (Cu), manganese (Mn), nickel (Ni) and vanadium (V). (3) The 90th %ile recorded emission concentration of B[a]P from the first Draft Waste incineration BREF, published by the European IPPC Bureau, was 0.04 ug/Nm³, or 0.00004 mg/Nm³ (dry, 11% oxygen, 273K). This is assumed to be the emission concentration for the Proposed Development.

Table 40: Stack Emissions Data – Half hourly Averages

Pollutant Half-hourly ELV HTI EfW (per line)


Oxides of nitrogen (as NO2) 200 0.820 10.100





If the Proposed Development continually operated at the half-hourly limits, the daily limits would be exceeded. The Proposed Development is designed to achieve the daily limits and as such will only operate at the short-term limits for short periods on rare occasions.

Additionally, the Proposed Development is designed to operate at full capacity and is not anticipated to have significant changes in loading. Therefore, it is appropriate to base the assessment on the design point of the system.

We have also modelled the impact of the existing Lakeside facilities, so that this can be subtracted from the impact of the proposed facilities to give a net change in permitted impacts. This is also used to consider the impacts during commissioning. The stack emissions data for these is shown below.

Table 41: Stack Source Data, Current Facilities


Stack Data

Height m 75 75

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Internal diameter – effective diameter m 0.86 2.52

Location m, m 503390.9, 178063.5

503901.2, 177366.2

Flue Gas Conditions

Temperature °C 140 145

Exit moisture content % v/v 8.9% 16.08%

Exit oxygen content % v/v dry 13.00% 11.00%

Reference oxygen content % v/v dry 11.00% 18.00%

Volume at reference conditions (dry, ref O2) Nm³/s 4.10 40.00

Volume at actual conditions Am³/s 8.71 73.78

Flue gas exit velocity m/s 15 14.8

Note: The existing plant includes two independent EfW lines as well as the HTI. The data in this table is for each line individually.

Table 42: Stack Emissions Data for existing facilities – Daily Averages



Oxides of nitrogen (as NO2) 200 0.82 8.0





Volatile organic compounds (as TOC)

10 0.041 0.4

Hydrogen fluoride 1 0.0041 0.04

Ammonia 10 0.41 0.4

Cadmium and thallium 0.05 0.205 mg/s 2.0 mg/s

Mercury 0.05 0.205 mg/s 2.0 mg/s

Other metals(2) 0.5 2.05 mg/s 20.0 mg/s

Benzo(a)pyrene (PaHs)(3) 0.04 µg/Nm³ 0.164 µg/s 1.6 µg/s

Dioxins and furans and PCBs 0.1 ng/Nm³ 0.41 ng/s 4.0 ng/s

Notes: All emissions are expressed at reference conditions of dry gas, 11% oxygen, 273.15K. (1) As a worst-case it has been assumed that the entire PM emissions consist of either PM10 or PM2.5 for comparison with the relevant AQALs. (2) Other metals consist of antimony (Sb), arsenic (As), lead (Pb), chromium (Cr), cobalt (Co), copper (Cu), manganese (Mn), nickel (Ni) and vanadium (V).

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Conc. (mg/Nm³) Release Rate (g/s) (3) The 90th %ile recorded emission concentration of B[a]P from the first Draft Waste incineration BREF, published by the European IPPC Bureau, was 0.04 ug/Nm³, or 0.00004 mg/Nm³ (dry, 11% oxygen, 273K). This is assumed to be the emission concentration for the existing facilities.

6.4 Scenarios considered To determine the difference in air quality impacts, this assessment has compared the following two scenarios:

1. ‘Best-case’– based on The Proposed Development operating at the emission limits as described in Table 32; and

2. ‘Commissioning’ – based on the Proposed Development operating one line at the emission limits detailed in Table 32 simultaneously with one line of the operational Lakeside EfW and HTI operating at the IED limits.

For this assessment, the modelling of both scenarios has been undertaken using ADMS version 5.2. The same five years of meteorological data (2014 – 2018) have been used in each model to allow for a comparison between the results.

6.5 Other Inputs

6.5.1 Modelling domain

Modelling has been undertaken over an 8 km x 8 km grid with a spatial resolution of 80m. The grid spacing in each direction is less than 1.5 times the minimum stack height considered in accordance with the Environment Agency’s modelling guidance. Reference should be made to Figure 9 for a graphical representation of the modelling domain used. The extent of the modelling domain is detailed in Table 43.

Table 43: Modelling Domain

Grid Quantity Value

Grid spacing (m) 80

Grid points 101

Grid Start X (m) 499400

Grid Finish X (m) 507400

Grid Start Y (m) 174100

Grid Finish Y (m) 182100

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6.5.2 Meteorological data and surface characteristics

The impact of meteorological data was taken into account by using weather data from the Heathrow Airport meteorological recording station for the years 2014 – 2018. Heathrow Airport is located adjacent to the Proposed Development.

The period 2014 to 2018 was chosen as this was the most recent full set of data available at the time of starting the air quality modelling. The Environment Agency recommends that 5 years of data are used to take into account inter-annual fluctuations in weather conditions. Wind roses for each year can be found in Figure 10.

The minimum Monin-Obukhov length can be selected in ADMS for both the dispersion site and the meteorological site. This is a measure of the minimum stability of the atmosphere and can be adjusted to account for urban heat island effects which prevent the atmosphere in urban areas from ever becoming completely stable. The minimum Monin-Obukhov length has been set to 30 m for both the dispersion site and the meteorological site. This value is considered appropriate as both the dispersion site and the meteorological site due to their location on the edge of a large city.

The surface roughness length can be selected in ADMS for both the dispersion site and the meteorological site. The surface roughness has been set to 0.5m for the meteorological site and 0.5 m for the dispersion site. The value of 0.5 m is appropriate for the both sites which accounts for the mixture of surrounding suburban and industrial areas, open fields and woodland.

6.5.3 Buildings

The presence of adjacent buildings can significantly affect the dispersion of the atmospheric emissions in various ways:

• Wind blowing around a building distorts the flow and creates zones of turbulence. The increased turbulence can cause greater plume mixing.

• The rise and trajectory of the plume may be depressed slightly by the flow distortion. This downwash leads to higher ground level concentrations closer to the stack than those which would be present without the building.

The Environment Agency recommends that buildings should be included in the modelling if they are both:

• Within 5L of the stack (where L is the smaller of the building height and maximum projected width of the building); and

• Taller than 40% of the stack.

The ADMS 5.2 user guide also states that buildings less than one third of the stack height will not have any effect on dispersion.

A review of the site layout has been undertaken and the details of the applicable buildings are presented in Table 44. The building has a variable height of between 16 m and 42m with an aerodynamic shape and it was considered that including the full height of the building would overstate its effect on dispersion. Therefore, a more representative height of 34 m was used. A site plan showing which buildings have been included in the model is presented in Figure 11.

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Table 44: Building Details

Buildings Centre Point Height (m)

Width (m)

Length (m)

Angle (°)

X (m) Y (m)

North 503393.8 178040.6 34 45 62.15 358

South 503396.5 177964.4 34 75 91.26 358

Slough BC asked for further justification for the approach to the building inputs. A building interrupts a laminar airflow and the resulting effect is a recirculating flow region on the leeward side of the building and a turbulent wake, as set out in the following figure. Emissions from the stack can be entrained into this region causing elevated ground level concentrations.

The geometry of the building proposed (like the existing building) is such that the air would flow over the building and the building wake would be smaller than if the building was a simple box like structure. This is illustrated in the following figure.

Therefore, treated the building as a block with a height of 42m would significantly over estimate the effect of the building when winds blow along the length of the building, given the roofline geometry which minimises the building wake effect. Treating the building as a 34m high block would be more representative.

If the wind were to be blowing across the building, then the recirculation zone would vary along the length of the building. By representing the building at 34m, which is taller than the building height close to the stack of around 27m, the modelling will overestimate the recirculation zone near to the stack. This is therefore conservative. If the building height in the model were increased to 42m, then the degree of overestimation would increase still further.

6.5.4 Terrain

It is recommended that, where gradients within 500 m of the modelling domain are greater than 1 in 10, the complex terrain module within ADMS (FLOWSTAR) should be used. A review of the local area has deemed that the effect of terrain does not need to be taken into account in the modelling.

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6.5.5 Chemistry

The Proposed Development will release nitric oxide (NO) and nitrogen dioxide (NO2) which are collectively referred to as NOx. In the atmosphere, nitric oxide will be converted to nitrogen dioxide in a reaction with ozone which is influenced by solar radiation. Since the air quality objectives are expressed in terms of nitrogen dioxide, it is important to be able to assess the conversion rate of nitric oxide to nitrogen dioxide.

Ground level NOx concentrations have been predicted through dispersion modelling. Nitrogen dioxide concentrations reported in the results section assume 70% conversion from NOx to nitrogen dioxide for annual means and a 35% conversion for short term (hourly) concentrations, based upon the worst-case scenario in the Environment Agency methodology. Given the short travel time to the areas of maximum concentrations, this approach is considered conservative.

6.6 Sensitivity Assessment

6.6.1 Surface Roughness

The sensitivity of the results to surface roughness length has been considered by running the model with a range of surface roughness lengths for the dispersion site. The following parameters were kept constant:

• model – ADMS 5.2;

• stack height – 55 m;

• buildings – included;

• meteorological site surface roughness – 0.5 m;

• dispersion site Monin-Obukhov length – 30 m;

• meteorological site Monin-Obukhov length – 30 m;

• terrain – excluded; and

• meteorological data used – Heathrow Airport 2015.

Table 45 presents the ground level concentration of oxides of nitrogen at the point of maximum impact for each surface roughness value.

Table 45: Choice of Dispersion Site Surface Roughness Length

Surface Roughness Length (m)

NOx Process Contribution (µg/m³)

Annual Mean Max 1-hour 99.79%ile of 1-hour

0.2 2.43 18.39 17.68

0.3 2.72 17.51 16.95

0.5 3.08 16.36 15.97

1 3.89 14.77 14.23

As shown, using varying surface roughness values leads to slightly different concentrations on an annual mean and short-term basis, with higher surface roughness values resulting in greater the peak annual mean impacts and smaller short-term impacts. The 0.5 m surface roughness value was selected for the model as this was deemed the most appropriate for the relatively urban surroundings of the dispersion site.

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6.6.2 Buildings

The sensitivity of the results to the effect of buildings has been considered by running the model with and without building inputs. The following parameters were kept constant:



• dispersion site surface roughness value – 0.5 m;


• dispersion site Monin-Obukhov length – 30 m


• terrain – excluded; and


Table 46 presents the ground level concentration of oxides of nitrogen at the point of maximum impact for each building scenario.

Table 46: Effect of Buildings

Scenario used in model NOx Process Contribution (µg/m³)


Buildings 3.08 16.36 15.97

No buildings 0.94 7.69 5.21

As shown, modelling the presence of buildings results in a greater peak annual concentration than the ‘no buildings’ scenario. Based on the layout of the Proposed Development, it is expected that building downwash effects will influence the dispersion of pollutants. As such, buildings have been included in the dispersion model as this represents a realistic and conservative approach.

6.6.3 Terrain

The sensitivity of the results to the effect of terrain has been considered by running the model with and without a terrain file. The following parameters were kept constant:



• dispersion site surface roughness value – 0.5 m;


• dispersion site Monin-Obukhov length – 30 m;


• buildings – included; and


Table 47 presents the ground level concentration of oxides of nitrogen at the point of maximum impact for each terrain scenario.

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Table 47: Effect of Terrain

Scenario used in model NOx Process Contribution (µg/m³)


Terrain 3.12 16.36 15.91

No terrain 3.08 16.36 15.97

As shown, the presence of terrain has a minimal impact on the long-term and short-term concentrations. As such, terrain has been excluded from the dispersion model.

6.7 Modelling Results – Main Case The general approach of this assessment is to evaluate the highest predicted process contribution to ground level concentrations over the five modelled years (2014 – 2018), known as the point of maximum impact. In addition, the predicted impacts have been evaluated at the human sensitive receptors presented in Section 4.3.2.

6.7.1 Results at the point of maximum impact

Table 48 presents the maximum predicted impact of process emissions for the five modelled years (2014 – 2018) at the point of maximum impact for the Proposed Development. The results are compared to the relevant AQALs. Impacts that do not screen out as ‘insignificant’ in accordance with Environment Agency guidance are highlighted, and impacts that cannot be described as ‘negligible’ irrespective of the total concentration in accordance with the IAQM 2017 criteria are shown in bold.

If either of these criteria are exceeded, further analysis has been undertaken.

It should be noted that this assessment is considered highly conservative as it assumes that:

• the Proposed Development continually operates at the emission limits outlined in Section 6.2;

• for comparison with short term AQOs, the Proposed Development operates at the short term ELVs during the worst-case conditions for dispersion of emissions;

• the entire PM emissions consist of either PM10 or PM2.5;

• the entire VOC emissions consist of either benzene or 1,3-butadiene; and

• cadmium is released at 100% of the combined emission limit for cadmium and thallium.

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Table 48: Dispersion Modelling Results for Proposed Development – Point of Maximum Impact

Pollutant Quantity Units AQAL Background conc.

Process Contribution (PC) Max PC PEC

2014 2015 2016 2017 2018 Conc. Max as % of

AQAL

Conc. Max as % of AQAL

Nitrogen dioxide

Annual mean µg/m³ 40 27.5 2.58 3.74 2.60 2.62 1.99 3.74 9.36% 31.24 78.11%

99.79th %ile of hourly means*

µg/m³ 200 55.00 38.08 38.97 37.99 38.07 37.07 38.97 19.49% 93.97 46.99%

Sulphur dioxide

99.18th %ile of daily means

µg/m³ 125 66.00 9.87 11.42 9.75 9.70 8.60 11.42 9.14% 77.42 61.94%

99.73rd %ile of hourly means*

µg/m³ 350 66.00 48.55 49.48 48.43 48.68 47.32 49.48 14.14% 115.48 32.99%

99.9th %ile of 15 min. means*

µg/m³ 266 66.00 51.68 52.80 51.73 51.95 50.22 52.80 19.85% 118.80 44.66%

Particulates (PM10)

Annual mean µg/m³ 40 15.00 0.18 0.26 0.18 0.18 0.14 0.26 0.66% 15.26 38.16%

90.41 %ile of daily means

µg/m³ 50 30.00 0.68 0.88 0.59 0.68 0.53 0.88 1.75% 30.88 61.75%

Particulates (PM2.5)

Annual mean µg/m³ 25 7.30 0.18 0.26 0.18 0.18 0.14 0.26 1.05% 7.56 30.25%

Carbon monoxide

8 hour running mean†

µg/m³ 10,000 1012.00

27.31 27.02 26.94 25.85 25.99 27.31 0.27% 1039.31 10.39%

Hydrogen chloride

Hourly mean*

µg/m³ 16 1.40 34.33 34.20 34.31 34.53 42.06 42.06 5.61% 43.46 5.80%

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2014 2015 2016 2017 2018 Conc. Max as % of

AQAL


Hydrogen fluoride

Hourly mean*

µg/m³ 160 4.60 2.29 2.28 2.29 2.30 2.80 2.80 1.75% 7.40 4.63%

Ammonia Annual mean µg/m³ 180 1.70 0.36 0.53 0.36 0.37 0.28 0.53 0.29% 2.23 1.24%

Hourly mean µg/m³ 2,500 3.40 5.72 5.70 5.72 5.75 7.01 7.01 0.28% 10.41 0.42%

VOCs (as benzene)

Annual mean µg/m³ 5 1.00 0.36 0.53 0.36 0.37 0.28 0.53 10.52% 1.53 30.52%

Hourly mean*

µg/m³ 195 2.00 5.72 5.70 5.72 5.75 7.01 7.01 3.60% 9.01 4.62%

VOCs (as 1,3-butadiene)

Annual mean µg/m³ 2.25 0.60 0.36 0.53 0.36 0.37 0.28 0.53 23.37% 1.13 50.03%

Mercury Annual mean ng/m³ 250 3.70 0.72 1.05 0.73 0.73 0.56 1.05 0.42% 4.75 1.90%

Hourly mean ng/m³ 7,500 7.40 11.44 11.40 11.44 11.51 14.02 14.02 0.19% 21.42 0.29%

Cadmium Annual mean ng/m³ 5 0.26 0.72 1.05 0.73 0.73 0.56 1.05 21.03% 1.31 26.23%

Hourly mean ng/m³ - 0.52 11.44 11.40 11.44 11.51 14.02 14.02 - 14.54 -

PaHs Annual mean pg/m³ 250 490.00 1.45 2.10 1.46 1.47 1.11 2.10 0.84% 492.10 196.84%

Dioxins and Furans

Annual mean fg/m³ - 33.00 2.17 3.15 2.19 2.20 1.67 3.15 - 36.15 -

PCBs Annual mean ng/m³ 200 127.50 0.18 0.26 0.18 0.18 0.14 0.26 0.13% 127.76 63.88%

PCBs

Hourly mean ng/m³ 6,000 255.00 2.86 2.85 2.86 2.88 3.51 3.51 0.06% 258.51 4.31%

* - run at the half-hourly emission limit.

† - run at the 10 minute emission limit.

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As shown in Table 48, the following pollutants do not screen out as ‘insignificant’ in accordance with Environment Agency guidance or ‘negligible’ irrespective of the total concentration in accordance with the IAQM 2017 criteria:

• Annual mean and short-term nitrogen dioxide;

• Short-term sulphur dioxide;

• Annual mean particulate matter (as PM2.5);

• Annual mean VOCs;

• Annual mean cadmium; and

• Annual mean PaHs.

In addition, annual mean particulate matter (as PM10) and annual mean PaHs do not screen out as ‘negligible’ irrespective of the total concentration, but do screen out as ‘insignificant’ in accordance with Environment Agency guidance.

Further analysis of these pollutants has been carried out at sensitive receptors, taking account of background concentrations.

The long-term and short-term impact of the Proposed Development for all other pollutants can be screened out as ‘insignificant’ in accordance with Environment Agency guidance and ‘negligible’ irrespective of the total concentration in accordance with the IAQM 2017 criteria based on the process contribution alone, and so further assessment is not required.

6.7.2 Further assessment – annual mean nitrogen dioxide

Table 49 shows the maximum predicted annual mean nitrogen dioxide concentrations over the five modelled years (2014 – 2018) at the point of maximum impact and at each identified receptor location, in addition to the contribution from background sources. For this assessment of annual mean nitrogen dioxide, the impact of the existing Lakeside facilities has been subtracted to give a net change in permitted impacts. This is because the emission limit for the replacement EfW and HTI plant is half the emission limit for the existing EfW and HTI plant and therefore there is a potential benefit from the change. The new facilities will not operate at the same time as the existing facilities.

Impacts that do not screen out as ‘insignificant’ in accordance with Environment Agency guidance are highlighted, and impacts that cannot be described as ‘negligible’ irrespective of the total concentration in accordance with the IAQM 2017 criteria are shown in bold.

Table 49: Further Analysis – Annual Mean Nitrogen Dioxide

Receptor ID

Receptor Name Net PC PEC

Conc. (µg/m³)

as % of AQAL

Conc. (µg/m³)

as % of AQAL

Point of maximum impact 3.45 8.6% 30.95 77.4%

R1 Old Slade Lane 1, Richings Park 2.69 6.7% 30.19 75.5%



R4 Main Drive, Richings Park 0.40 1.0% 27.90 69.8%

R5 North Park, Richings Park 0.24 0.6% 27.74 69.4%

R6 Sutton Lane 1, Langley 0.06 0.2% 27.56 68.9%

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Receptor ID

Receptor Name Net PC PEC

Conc. (µg/m³)

as % of AQAL

Conc. (µg/m³)

as % of AQAL


R8 London Road, Colnbrook 0.08 0.2% 27.58 69.0%

R9 Vicarage Way, Colnbrook 0.26 0.6% 27.76 69.4%

R10 The Hawthrorns, Colnbrook 0.05 0.1% 27.55 68.9%

R11 The Island, Longford -0.12 -0.3% 27.38 68.5%

R12 Verbena Close, West Drayton 0.01 <0.1% 27.51 68.8%

R13 Lily Drive, West Drayton -0.03 -0.1% 27.47 68.7%

R14 The Common, West Drayton -0.01 <0.1% 27.49 68.7%

R15 Mayfield Park, West Drayton -0.08 -0.2% 27.42 68.5%

R16 Thorney Mill Road, Thorney 0.07 0.2% 27.57 68.9%

R17 Richings Way, Richings Park 0.36 0.9% 27.86 69.7%

R18 Parlaunt Park Primary Academy 0.03 <0.1% 27.53 68.8%

R19 Foxborough Primary School 0.06 0.1% 27.56 68.9%

R20 Colnbrook CoE School 0.15 0.4% 27.65 69.1%

R21 Harmondsworth Primary School -0.28 -0.7% 27.22 68.1%

R22 Laurel Lane Primary School -0.01 <0.1% 27.49 68.7%


-0.07 -0.2% 27.43 68.6%

Note:

PEC includes contribution of 27.50 µg/m³ which is the maximum monitored at the SB1 diffusion tube.

Assumes 70% conversion of NOx to NO2.

As shown, the annual mean net process contribution from the Proposed Development cannot be screened out as ‘insignificant’ at the point of maximum impact. In addition, the PEC is predicted to be greater than 70% of the AQAL and as such it can be concluded that the impact of emissions cannot be screened out as ‘not significant' under EA guidance. Using the IAQM guidance the magnitude of change of can be described as described as ‘moderate adverse’ as the annual mean net process contribution is 5.5 - 10.5% of the AQAL and the PEC is less than 94.5% of the AQAL. In addition, this impact occurs in a small area within the South Buck District Council AQMA No. 2, declared for annual mean nitrogen dioxide concentrations. However, a review of local air quality monitoring data shows that baseline concentrations in the AQMA where the impact occurs are likely to be no more than 27.5 µg/m³ (the average monitored concentration at the SB1 Iver, Old Slade Lane). The impacts at areas of relevant exposure within the AQMA are described below.

Figure 12 shows the spatial distribution of emissions in relation to the human sensitive receptors identified for assessment. An analysis of the plot files shows that the area which cannot be screened out as ‘insignificant’ in accordance with Environment Agency guidance and ‘negligible’ irrespective of the total concentration in accordance with the IAQM 2017 criteria extends across a small area along Old Slade Lane, i.e. an area where the AQAL applies.

To assess the impact at areas of relevant exposure, the impact at sensitive receptors has been considered.

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Under the IAQM guidance, the impact at all but seven sensitive receptors is less than 0.5% of the AQAL, and so can be described as ‘negligible’ irrespective of the total concentration. R1, R2 and R3 are all located on Old Slade Lane and R4 is located in close proximity, on Main Drive. Therefore, the background concentration presented in

Table 18 (27.5 µg/m³ monitored at SB1 Iver, Old Slade Lane) is applicable. When this background concentration is applied the impact of the Proposed Development at R1 is described as ‘slight adverse’ as the annual mean process contribution is 5.5 - 10.5% of the AQAL and the PEC is less than 75.5% of the AQAL. The impact of the Proposed Development at R2, R3 and R4 is described as ‘negligible’ as the annual mean process contribution is less than 5.5% of the AQAL and the PEC is less than 75.5% of the AQAL.

R5 is located along North Park, which is a fairly busy road. There are a number of houses along this road where the impact cannot be screened out as ‘negligible’ irrespective of the total concentration. There is a diffusion tube on this road which measures 39 µg/m3, but this is only 1.6 m from the kerbside. Along North Park, the closest house to the road is 4m away and by applying an adjustment for distance correction provided by DEFRA6, the approximate background concentration is 36.7µg/m3. Applying this as the baseline concentration at R5, the PEC is predicted to be 36.94 µg/m³, or 92.3% of the AQAL. Therefore, the impact of the Proposed Development at R5 is described as ‘negligible’ as the annual mean process contribution is less than 1.5% of the AQAL and the PEC is less than 94.5% of the AQAL.

R9 in located in Colnbrook. Measured concentrations in Colnbrook away from main roads are up to 29 µg/m³. When this background concentration is applied, the PEC is predicted to be 29.26 µg/m3 or Therefore, the impact of the Proposed Development at R9 is described as ‘negligible’ as the annual mean process contribution is less than 1.5% of the AQAL and the PEC is less than 75.5% of the AQAL.

R17 is located away from a busy road between Richings Way and Thorney Lane South. A review of local air quality monitoring data shows that baseline concentrations close to this receptor are likely to be no more than 37.3 μg/m³ (the average maximum monitored at a roadside location near the receptor in the last four years – at the SB32 and SB33 Tower Arms, Thorney Lane co-located diffusion tubes). Applying this as the baseline concentration at R17 as a conservative measure, the PEC is predicted to be 37.5 µg/m³, or 93.9% of the AQAL. Therefore, the impact of the Proposed Development at R17 is described as ‘negligible’ as the annual mean process contribution is less than 1.5% of the AQAL and the PEC is less than 94.5% of the AQAL.

6.7.3 Further assessment – hourly mean nitrogen dioxide

Table 50 shows the maximum predicted nitrogen dioxide 99.79th percentile of hourly means concentrations over the five modelled years (2014 – 2018) at the point of maximum impact and at each identified receptor location, in addition to the contribution from background sources.


These results assume that the EfW Facility operates at the half-hourly emission limit of 200 mg/Nm3. In reality, the EfW Facility will mainly run below the daily emission limit of 100 mg/Nm3, so the results are considered conservative.

6 Available from https://laqm.defra.gov.uk/tools-monitoring-data/no2-falloff.html

https://laqm.defra.gov.uk/tools-monitoring-data/no2-falloff.html

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Table 50: Further Analysis – Hourly Mean Nitrogen Dioxide

Receptor ID

Receptor Name PC PEC

Conc. (µg/m³)

as % of AQAL

Conc. (µg/m³)

as % of AQAL












R11 The Island, Longford 5.73 2.9% 60.73 30.4%

R12 Verbena Close, West Drayton 4.73 2.4% 59.73 29.9%

R13 Lily Drive, West Drayton 4.48 2.2% 59.48 29.7%

R14 The Common, West Drayton 5.82 2.9% 60.82 30.4%

R15 Mayfield Park, West Drayton 5.13 2.6% 60.13 30.1%



R18 Parlaunt Park Primary Academy 5.34 2.7% 60.34 30.2%



R21 Harmondsworth Primary School 4.86 2.4% 59.86 29.9%

R22 Laurel Lane Primary School 4.18 2.1% 59.18 29.6%


4.23 2.1% 59.23 29.6%

Using the IAQM guidance the magnitude of change at the point of maximum impact can be described as described as ‘slight adverse’ as the annual mean process contribution at the point of maximum impact is >10% of the short-term AQAL. The impact at all but one sensitive receptor is less than 10% of the AQAL, and so can be described as ‘negligible’ irrespective of the total concentration. At R1, the process contribution is predicted to be 25.1 µg/m³, or 12.6% of the short-term AQAL. Therefore, the impact of the Proposed Development at R1 is described as ‘slight adverse.’

Under EA guidance, the short-term process contribution from the Proposed Development cannot be screened out as ‘insignificant’ at the point of maximum impact. Considering background concentrations, the headroom is 200 µg/m³ - (27.5µg/m³ x 2) = 145 µg/m³. The process contribution

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is 38.97 µg/m³, which is 26.87% of the headroom. Based on the predicted short-term process contribution, it cannot be concluded that there is little risk of the PEC exceeding the AQAL.

Figure 13 shows the spatial distribution of emissions in relation to the human sensitive receptors identified for assessment. This shows the area that cannot be screened out as ‘insignificant’ in accordance with Environment Agency guidance and ‘negligible’ irrespective of the total concentration in accordance with the IAQM 2017 criteria. An analysis of the plot files shows that the process contribution only exceeds 10% of the AQAL in a small area along Old Slade Lane, which only includes one receptor, R1. However, there is a very low likelihood of emissions at the half-hourly ELV coinciding with the worst-case weather conditions for dispersion, and the PEC is less than half of the AQAL.

Under the EA Guidance, the process contribution at R1 is 17.3% of the headroom, which is less than 20%, and therefore there is little risk of the AQAL being exceeded.

6.7.4 Further assessment – annual mean PM as PM10

Table 51 shows the maximum predicted annual mean particulate matter concentrations (as PM10) over the five modelled years (2014 – 2018) at the point of maximum impact and at each identified receptor location, in addition to the contribution from background sources. This analysis conservatively assumes that the entire PM is released at the ELV for total dust and the entire emissions consist of only PM10.

Table 51: Further Analysis - Annual Mean Particulate Matter (As PM10)

Receptor ID


Conc. (µg/m³)

as % of AQAL

Conc. (µg/m³)

as % of AQAL







R6 Sutton Lane 1, Langley 0.01 <0.1% 15.01 37.5%


R8 London Road, Colnbrook 0.01 <0.1% 15.01 37.5%


R10 The Hawthrorns, Colnbrook 0.01 <0.1% 15.01 37.5%

R11 The Island, Longford 0.02 <0.1% 15.02 37.5%






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Receptor ID


Conc. (µg/m³)

as % of AQAL

Conc. (µg/m³)

as % of AQAL



R19 Foxborough Primary School 0.01 <0.1% 15.01 37.5%


R21 Harmondsworth Primary School 0.02 <0.1% 15.02 37.5%



0.02 <0.1% 15.02 37.5%

Note:

PEC includes contribution of 15.00 µg/m³ which is the maximum monitored concentration from the Slough Lakeside 2 continuous monitor.

The PC is less than 1% of the AQAL at all sensitive receptor locations considered, and therefore the impact at all sensitive receptors can be screened out as ‘insignificant’ using the Environment Agency’s screening criteria.

Using the IAQM guidance, the impact at all but one sensitive receptor is less than 0.5% of the AQAL, and so can be described as ‘negligible’ irrespective of the total concentration. At R1 the annual mean process contribution is 0.5% of the AQAL and the PEC is 38.0% of the AQAL, and therefore the impact can be described as ‘negligible’ as the annual mean process contribution is less than 1.5% of the AQAL and the PEC is less than 75.5% of the AQAL.

6.7.5 Further assessment – annual mean PM as PM2.5

Table 52 shows the maximum predicted annual mean particulate matter concentrations (as PM2.5) over the five modelled years (2014 – 2018) at the point of maximum impact and at each identified receptor location, in addition to the contribution from background sources. This analysis conservatively assumes that the entire PM is released at the ELV for total dust and the entire emissions consist of only PM2.5.

Table 52: Further Analysis - Annual Mean Particulate Matter (As PM2.5)

Receptor ID


Conc. (µg/m³)

as % of AQAL

Conc. (µg/m³)

as % of AQAL









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Receptor ID


Conc. (µg/m³)

as % of AQAL

Conc. (µg/m³)

as % of AQAL

















0.02 0.1% 7.32 29.3%

Note:

PEC includes contribution of 7.30 µg/m³ which is the maximum monitored concentration from the Slough Lakeside 2 continuous monitor.

Using the IAQM guidance the magnitude of change can be described as ‘negligible’ as the annual mean process contribution is less than 1.5% of the AQAL and the PEC is less than 75.5% of the AQAL.

Under EA guidance, the annual mean process contribution from the Proposed Development cannot be screened out as ‘insignificant’ at the point of maximum impact. However, when the background concentration is applied the PEC is predicted to be less than 70% of the AQAL and as such the impact of emissions can be screened out as ‘not significant' using the EA guidance. The PC is less than 1% of the AQAL at all sensitive receptor locations considered, and therefore the impact at these receptors can be screened out as ‘insignificant’ using the Environment Agency’s screening criteria.

Figure 15 shows the spatial distribution of emissions in relation to the human sensitive receptors identified for assessment. This shows the area that cannot be screened out as ‘insignificant’ in accordance with Environment Agency guidance and ‘negligible’ irrespective of the total concentration in accordance with the IAQM 2017 criteria is uninhabited and the annual mean AQAL does not apply.

Using the IAQM guidance, the impact at all but one sensitive receptor is less than 0.5% of the AQAL, and so can be described as ‘negligible’ irrespective of the total concentration. At R1 the annual mean process contribution is 0.9% of the AQAL and the PEC is 30.1% of the AQAL, and therefore the impact can be described as ‘negligible’ as the annual mean process contribution is less than 1.5% of the AQAL and the PEC is less than 75.5% of the AQAL.

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6.7.6 Further assessment – annual mean VOCs (as benzene)

Table 53 shows the maximum predicted annual mean VOC concentrations (as benzene) over the five modelled years (2014– 2018) at the point of maximum impact and at each identified receptor location, in addition to the contribution from background sources. It should be noted that this conservatively assumes that all the VOC released from the Proposed Development consist of only benzene.

Table 53: Further Analysis – Annual Mean VOCs as Benzene

Receptor ID


Conc. (µg/m³)

as % of AQAL

Conc. (µg/m³)

as % of AQAL

























0.03 0.7% 1.03 20.7%

Note:

PEC includes contribution of 1.0 µg/m³ which is the maximum mapped background concentration over the modelling domain.

As shown, the annual mean process contribution from the Proposed Development cannot be screened out as ‘insignificant’ under EA guidance at the point of maximum impact. However, when

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the background concentration is applied the PEC is predicted to be less than 70% of the AQAL and as such it can be concluded that the impact of emissions is ‘not significant'.

Using the IAQM Guidance, the magnitude of change associated with process emissions from the Proposed Development is described as ‘moderate adverse’ as the annual mean process contribution is >10% of the AQAL and the PEC is less than 75.5% of the AQAL. Figure 16 shows the spatial distribution of emissions in relation to the human sensitive receptors identified for assessment. This shows the area that cannot be screened out as ‘insignificant’ in accordance with Environment Agency guidance and ‘negligible’ irrespective of the total concentration in accordance with the IAQM 2017 criteria. As shown, the point of maximum impact is uninhabited and the annual mean AQAL does not apply.

To assess the impact at areas of relevant exposure the impact at sensitive receptors has been considered. The change in impact at 10 sensitive receptors is less than 1% of the AQAL and can be screened out as ‘insignificant’. At 13 sensitive receptor locations the impact of the Proposed Development is greater than 1%. However, when the background concentration is applied the PEC is below 70% of the AQAL. Therefore, using the Environment Agency’s screening criteria, the impact of the Proposed Development at the sensitive receptors can be screened out as ‘not significant’.

Under the IAQM guidance, the impact at two sensitive receptors is less than 0.5% of the AQAL, and so can be described as ‘negligible’ irrespective of the total concentration. The impact at 20 sensitive receptor locations is 0.5% - 5.5% of the AQAL. When the background concentration is applied the impact can be described as ‘negligible’, as the annual mean process contribution is less than 5.5% of the AQAL and the PEC is less than 75.5% of the AQAL.

At R1 the impact is predicted to be 8.5% of the AQAL and the PEC is 28.6% of the AQAL. Therefore, when the background concentration is applied, the impact is described as ‘slight adverse’. However, this is highly conservative, as it assumes that all the VOCs released from the Proposed Development consist of only benzene. In reality, benzene makes up less than 20% of VOC emissions and EfW plants operate with VOC concentrations below 20% of the emission limit. This means that the actual process contribution will be less than 0.5% of the AQAL.

6.7.7 Further assessment – annual mean VOCs (as 1,3-butadiene)

Table 54 shows the maximum predicted annual mean VOC concentrations (as 1,3-butadiene) over the five modelled years (2014 – 2018) at the point of maximum impact and at each identified receptor location, in addition to the contribution from background sources. It should be noted that this conservatively assumes that all the VOC released from the Proposed Development consist of only 1,3-butadiene.

Table 54: Further Analysis – Annual Mean VOCs as 1,3-Butadiene

Receptor ID


Conc. (µg/m³)

as % of AQAL

Conc. (µg/m³)

as % of AQAL







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Receptor ID


Conc. (µg/m³)

as % of AQAL

Conc. (µg/m³)

as % of AQAL



















0.03 1.5% 0.63 28.1%

Note:

PEC includes contribution of 0.60 µg/m³ which is the maximum mapped background concentration over the modelling domain.

As shown, the annual mean process contribution from the Proposed Development cannot be screened out as ‘insignificant’ at the point of maximum impact under EA guidance. However, when the background concentration is applied the PEC is predicted to be less than 70% of the AQAL and as such it can be concluded that the impact of emissions is ‘not significant'.

Using the IAQM guidance the magnitude of change associated with process emissions from the Proposed Development is described as ‘moderate adverse’ as the annual mean process contribution is >10% of the AQAL and the PEC is less than 75.5% of the AQAL. Figure 17 shows the spatial distribution of emissions in relation to the human sensitive receptors identified for assessment. This shows the area that cannot be described as ‘negligible’ irrespective of the total concentration in accordance with the IAQM 2017 criteria. As shown, the point of maximum impact is uninhabited and the annual mean AQAL does not apply.

To assess the impact at areas of relevant exposure the impact at sensitive receptors has been considered. The impact at all but two sensitive receptors is greater than 1% of the AQAL. However, when the background concentration is applied, the overall PEC is below 70% of the AQAL. Therefore, using the Environment Agency’s screening criteria, the impact of the Proposed Development at all sensitive receptors can be screened out as ‘not significant’.

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Under the IAQM guidance, the impact at 20 sensitive receptors is 0.5% - 5.5% of the AQAL. When the background concentration is applied, the impact can be described as ‘negligible’ as the annual mean process contribution is less than 5.5% of the AQAL and the PEC is less than 75.5% of the AQAL.

At R2 and R3 the impact is described as ‘slight adverse’ as the annual mean process contribution is 5.5 -10.5% of the AQAL and the PEC is less than 75.5% of the AQAL.

At R1 the impact is described as ‘moderate adverse’ as the annual mean process contribution is greater than 10.5% of the AQAL and the PEC is less than 75.5% of the AQAL.

However, this is highly conservative, as it assumes that all the VOCs released from the Proposed Development consist of only 1,3-butadiene. In reality, 1,3-butadiene makes up less than 10% of VOC emissions and EfW plants operate with VOC concentrations below 20% of the emission limit. This means that the actual process contribution will be less than 0.5% of the AQAL.

6.7.8 Further assessment – annual mean cadmium

As previously noted, this assessment has initially used a screening assumption that cadmium is released from the Proposed Development at the combined emission limit for cadmium and thallium. However, monitoring from waste incineration facilities has indicated that concentrations of cadmium are typically approximately 35% of the ELV, or 7µg/Nm3. Therefore, this assessment has considered the impact of cadmium under the following three scenarios:

1. screening – assumes cadmium is released at 100% of the combined ELV;

2. worst-case – assumes cadmium is released at 50% of the combined ELV; and

3. typical – assumes cadmium is released at 35% of the combined ELV.

Table 55 shows the maximum predicted annual mean cadmium concentrations over the five modelled years (2014 – 2018) at the point of maximum impact and at each identified receptor location.

Table 55: Further Analysis – Annual Mean Cadmium

Site ID Site Name PC PEC

Conc. (ng/m³)

as % of AQAL

Conc. (ng/m³)

as % of AQAL

Point of maximum impact – screening 1.05 21.0% 1.31 26.2%

Point of maximum impact – worst-case 0.53 10.5% 0.79 15.7%

Point of maximum impact – typical 0.37 7.4% 0.63 12.6%

Receptors – Typical










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Site ID Site Name PC PEC

Conc. (ng/m³)

as % of AQAL

Conc. (ng/m³)

as % of AQAL















0.07 0.5% 0.33 6.5%

Note: PEC includes contribution of 0.26 ng/m³ which is the maximum annual average monitored concentration from UK urban background sites (2013 – 2017)

As shown, in the ‘screening scenario’, the annual mean process contribution from the Proposed Development cannot be screened out as ‘insignificant’ at the point of maximum impact using EA guidance. However, the PEC is predicted to be less than 70% of the AQAL and as such it can be concluded that the impact of emissions is ‘not significant'. Using the IAQM guidance the magnitude of change associated with process emissions from the Proposed Development is described as ‘moderate adverse’ as the annual mean process contribution is >10% of the AQAL and the PEC is less than 75.5% of the AQAL. However, this is extremely conservative as monitoring data from facilities processing a similar fuel has indicated concentrations of cadmium are usually about 35% of the limit. The annual mean cadmium process contribution as a percentage of the AQAL for this screening assumption is presented in Figure 18.

To assess the impact at areas of relevant exposure, the impact at sensitive receptors has been considered using the ‘typical scenario’. The change in impact at 16 sensitive receptors is less than 1% of the AQAL and can be screened out as ‘insignificant’. At seven sensitive receptor locations the impact of the Proposed Development is greater than 1%. However, when the background concentration is applied the PEC is below 70% of the AQAL. Therefore, using the Environment Agency’s screening criteria, the impact of the Proposed Development at the sensitive receptors can be screened out as ‘not significant’.

Under the IAQM guidance, the impact at eight sensitive receptors is less than 0.5% of the AQAL, and so can be described as ‘negligible’ irrespective of the total concentration. The impact at 14 sensitive receptors is 0.5% - 5.5% of the AQAL. When the background concentration is applied, the impact can be described as ‘negligible’ as the annual mean process contribution is less than 5.5% of the AQAL and the PEC is less than 75.5% of the AQAL. At R1 the impact is predicted to be 5.5% -

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10.5% of the AQAL and the PEC is predicted to be below 75.5% of the AQAL. Therefore, the impact is described as ‘slight adverse’ at this receptor only.

Slough Borough Council asked for further evidence that the typical level of cadmium could be achieved. The emissions of cadmium and thallium from European EfW plants are shown in the final draft Waste Incineration (WI) BREF. Figure 3.33 from page 180 of the final draft WI BREF is reproduced below and summarises emissions data from 197 municipal waste-to-energy lines. Only six of the reference lines had emissions which exceeded the BAT-AEL of 0.02 mg/Nm3. This was the evidence used to set the BAT-AEL and clearly shows that it can be consistently achieved.

The detailed results presented in figures 8.130, 8.131 and 8.132 in the final draft WI BREF include 17 UK plants, all of which are equipped with bag filters, like the Facility. The average recorded concentration was 1.6 µg/Nm3, the highest recorded concentration of cadmium and thallium was 14 µg/Nm3 and only three lines recorded concentrations higher than 10 µg/Nm3.

In addition, we have reviewed the emissions of cadmium from the current Lakeside facility. The emissions from each line are measured every six months. The twelve most recent measurements were between 0.20 µg/Nm3 and 0.81 µg/Nm3, with an average of 0.42 µg/Nm3. The waste for the new Facility will be the same as that for the existing facility, so it is reasonable to assume that the concentration of cadmium would also be similar as this is dependent on the fuel composition.

Therefore, it can clearly be demonstrated that the facility will be able to achieve the BAT AEL and emissions are highly likely to be significantly below the limit. The use of 7 µg/Nm3 remains conservative as the average value monitored across the UK was only 1.6 µg/Nm3 or 8% of the BAT AEL of 0.02 mg/Nm3 and the average value monitored at the current facility was only 0.42 µg/Nm3, or 2% of the BAT AEL.

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6.7.9 Further assessment – annual mean PaHs

Table 56 shows the maximum predicted annual mean PaHs over the five modelled years (2014 – 2018) at the point of maximum impact and at each identified receptor location, in addition to the contribution from background sources.

Table 56: Further Analysis - Annual Mean PaHs

Receptor ID


Conc. (pµg/m³)

as % of AQAL

Conc. (pµg/m³)

as % of AQAL









R8 London Road, Colnbrook 0.12 <0.1% 490.12 196.0%



R11 The Island, Longford 0.12 <0.1% 490.12 196.0%













0.13 0.1% 490.13 196.1%

Note:

PEC includes contribution of 490.0 µg/m³ which is the maximum of the UK average concentrations.

As shown, the annual mean process contribution from the Proposed Development can be screened out as ‘insignificant’ at the point of maximum impact using EA guidance.

Using the IAQM guidance, the magnitude of change can be described as ‘moderate adverse’ as the annual mean process contribution is less than 1.5% of the AQAL and the PEC is greater than 110%

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of the AQAL. Baseline concentrations in the vicinity of the Proposed Development are already high at 196.0% of the AQAL, and the process contribution from the Proposed Development is very small at 0.8% of the AQAL. Therefore, emissions from the Proposed Development represent a small proportion of the long-term average concentration.

Figure 19 shows the spatial distribution of emissions in relation to the human sensitive receptors identified for assessment. This shows the area that cannot be described as ‘negligible’ irrespective of the total concentration in accordance with the IAQM 2017.

As shown, the PC is less than 1% of the AQAL at all sensitive receptor locations considered, and therefore the impact at these receptors can be screened out as ‘insignificant’ using the Environment Agency’s screening criteria.

Using the IAQM guidance, the impact at all but one sensitive receptor is less than 0.5% of the AQAL, and so can be described as ‘negligible’ irrespective of the total concentration. At R1 the annual mean process contribution is 0.7% of the AQAL and the PEC is 196.7% of the AQAL, and therefore the impact is described as ‘moderate adverse’. Excluding the process contribution from the Proposed Development, the PEC is already predicted to be 196.0% of the AQAL. Therefore, emissions from the Proposed Development represent a small proportion of the long-term average concentration at R1 (0.7% of the AQAL).

6.7.10 Further assessment – 99.73rd %ile of hourly means sulphur dioxide

Table 57 shows the maximum predicted 99.73rd %ile of hourly mean sulphur dioxide concentrations over the five modelled years (2014 – 2018) at the point of maximum impact and at each identified receptor location, in addition to the contribution from background sources.


Table 57: Further Analysis – 99.73rd %ile of Hourly Means Sulphur Dioxide

Receptor ID


Conc. (µg/m³)

as % of AQAL

Conc. (µg/m³)

as % of AQAL












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Receptor ID


Conc. (µg/m³)

as % of AQAL

Conc. (µg/m³)

as % of AQAL














5.11 1.5% 71.11 20.3%

As shown, the short-term process contribution from the Proposed Development cannot be screened out as ‘insignificant’ at the point of maximum impact. The headroom is 350 µg/m³ - (33.0 µg/m³ x 2) = 284 µg/m³. The process contribution is 49.4 µg/m³, which is 17.4% of the headroom. Therefore, for 1-hour sulphur dioxide concentrations, it can be concluded that “there is little risk of the PEC exceeding the AQAL”, and the impact can be considered to be ‘not significant’.

Using the IAQM guidance the magnitude of change at the point of maximum impact can be described as ‘slight adverse’ as the process contribution is >10% of the short-term AQAL. Figure 20 shows the spatial distribution of emissions in relation to the human sensitive receptors identified for assessment. This shows the area that cannot be described as ‘negligible’ irrespective of the total concentration in accordance with the IAQM 2017 criteria. An analysis of the plot files shows that the process contribution exceeds 10% of the AQAL in a small area along Old Slade Lane and neighbouring golf course, i.e. an area where the AQAL applies. However, there is a very low likelihood of emissions at the half-hourly ELV coinciding with the worst-case weather conditions for dispersion.

To assess the impact at areas of relevant exposure the impact at sensitive receptors has been considered. The change in impact at all sensitive receptors is less than 10% of the AQAL and can be screened out as ‘insignificant’.

Under the IAQM guidance, the impact at all sensitive receptors is less than 10% of the AQAL, and so can be described as ‘negligible’ irrespective of the total concentration.

6.7.11 Further assessment – 99.9th %ile of 15-minute means sulphur dioxide

Table 58 shows the maximum 99.9th %ile of 15-minute mean concentrations over the five modelled years (2014 – 2018) at the point of maximum impact and at each identified receptor location, in addition to the contribution from background sources.

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Table 58: Further Analysis – 99.9th %ile of 15-minute means sulphur dioxide

Receptor ID


Conc. (µg/m³)

as % of AQAL

Conc. (µg/m³)

as % of AQAL

























8.44 3.2% 74.44 28.0%

As shown, the short-term process contribution from the Proposed Development cannot be screened out as ‘insignificant’ at the point of maximum impact. The headroom is 266 µg/m³ - (33.0 µg/m³ x 2) = 284 µg/m³. The process contribution is 52.8 µg/m³, which is 26.4% of the headroom. Therefore, for 15-minute mean sulphur dioxide concentrations, it cannot be concluded that “there is little risk of the PEC exceeding the AQAL”, and the impact cannot be considered to be ‘not significant’. Using the IAQM guidance the magnitude of change of can be described as described as ‘slight adverse’ as the process contribution is >10% of the short-term AQAL.

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Figure 21 shows the spatial distribution of emissions in relation to the human sensitive receptors identified for assessment. This shows the area that cannot be described as ‘negligible’ irrespective of the total concentration in accordance with the IAQM 2017 criteria.

To assess the impact at areas of relevant exposure the impact at sensitive receptors has been considered. The change in impact at 21 sensitive receptors is less than 10% of the AQAL and can be screened out as ‘insignificant’. At two sensitive receptor locations the impact of the Proposed Development is greater than 10%. However, when the background concentration is applied, the PEC is predicted to be well below the short-term AQAL and therefore there is little risk of the AQAL being exceeded.

Under the IAQM guidance, the impact at all but two sensitive receptors is less than 10% of the AQAL, and so can be described as ‘negligible’ irrespective of the total concentration. At R1 and R2 the process contribution is predicted to be greater than 10 % of the short-term AQAL. Therefore, the impact of the Proposed Development at R1 and R2 is described as ‘slight adverse.’

6.7.12 Metals assessment

The Environment Agency document ‘Guidance to Applicants on Impact Assessment for Group 3 Metals Stack Releases – V.4 June 2016’7 (“Metals Guidance”) outlines the following two-stage assessment methodology for detailed modelling of Group 3 metals.

1. First it should be assumed that each metal is released at 100% of the total metal ELV (i.e. 0.3 mg/Nm³).

2. If the impact cannot be ‘screened out’ under the first-stage assessment, it should be assumed that each metal is released at the maximum concentration monitored at an existing facility8.

The Metals Guidance states that where the process contribution for any metal exceeds 1% of the long-term AQAL or 10% of the short-term AQAL, there is potential for significant pollution. Where the process contribution exceeds these criteria, the PEC should be compared to the AQAL. The impact can be screened out as ‘not significant’ where the PEC is less than 100% of the environmental standard.

7 Available at:

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/532474/LIT_7349.pdf

8 Data sourced from 18 municipal waste incinerators and waste wood co-incinerators between 2007 and 2015, as stated in Appendix A of the Metals Guidance document

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Table 59: Long-Term Metals Results for Proposed Development – Point of Maximum Impact

Metal AQAL (ng/m³)

Background conc. (ng/m³)

Stage 1 assessment (1) Stage 2 assessment (2)

PC PEC Metal as % of total ELV

PC PEC

ng/m³ as % AQAL

ng/m³ as % AQAL

ng/m³ as % AQAL

ng/m³ as % AQAL

Arsenic 3 0.79 15.77 525.75% 16.56 552.08% 8.3% 1.31 43.81% 2.10 70.15%

Antimony 5,000 - 15.77 0.32% - - 3.8% 0.60 0.01% - -

Chromium 5,000 13.16 15.77 0.32% 28.93 0.58% 30.7% 4.84 0.10% 18.00 0.36%

Chromium (VI) 0.2 2.63 15.77 7886.25% 18.40 9202.25% 0.012% 0.006 3.42% 2.63 1316.92%

Cobalt - 0.25 15.77 - 16.02 - 1.9% 0.29 - 0.54 -

Copper 10,000 11.10 15.77 0.16% 26.87 0.27% 9.7% 1.52 0.02% 12.62 0.13%

Lead 250 10.35 15.77 6.31% 26.12 10.45% 16.8% 2.64 1.06% 12.99 5.20%

Manganese 150 10.90 15.77 10.52% 26.67 17.78% 20.0% 3.15 2.10% 14.05 9.37%

Nickel 20 6.61 15.77 78.86% 22.38 111.91% 73.3% 11.57 57.83% 18.18 90.88%

Vanadium 5,000 1.55 15.77 0.32% 17.32 0.35% 2.0% 0.32 0.01% 1.87 0.04%

Notes: (1) Assumes that each metal is released at 100% of the total metal ELV (i.e. 0.3 mg/Nm³). (2) Assumes that each metal is released at the maximum concentration monitored at an existing facility, as presented in Appendix A of the Environment Agency Metals Guidance. (3) There is no monitoring of the separate species of chromium in the UK. This assessment assumes that background concentrations of chromium (VI) equate to 20% of the total chromium concentration, as required by the Metals Guidance methodology.

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Table 60: Short-Term Metals Results for Proposed Development – Point of Maximum Impact

Metal AQAL (ng/m³ Baseline Concentration

(ng/m³)

Assuming each metal emitted at 100% of the group ELV

Metal (as % of ELV)

Assuming each metal emitted as per Environment Agency

maximum monitored

PC as % of AQAL PEC as % of AQAL

PC as % of AQAL PEC as % of AQAL

Arsenic - 1.58 - - 8.3% - -

Antimony 150,000 - 0.14% - 3.8% 0.01% -

Chromium 150,000 26.32 0.14% 0.16% 30.7% 0.04% 0.06%

Chromium (VI) - 5.26 - - 0.04% - -

Cobalt - 0.50 - - 1.9% - -

Copper 200,000 22.20 0.11% 0.12% 9.7% 0.01% 0.02%

Lead - 20.70 - - 16.8% - -

Manganese 1,500,000 21.80 0.01% 0.02% 20.0% 0.003% 0.004%

Nickel - 13.22 - - 73.3% - -

Vanadium 1,000 3.10 21.03% 21.34% 2.0% 0.42% 0.73%

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6.7.12.1 Long-term results

As shown in Table 59 if it is assumed that the entire emissions of metals consist of only one metal, the annual process contributions of arsenic, chromium (VI), cobalt, lead, manganese and nickel are predicted to be greater than 1% of the long-term AQAL at the point of maximum impact. However, only the PEC for arsenic, chromium (VI) and nickel is predicted to be greater than 100% of the AQAL under this worst-case screening assumption.

If it is assumed that the Proposed Development will perform no worse than a currently permitted facility, the predicted process contribution is below 1% of the AQAL for all metals with the exception of arsenic, chromium (VI), lead, manganese and nickel. However, the PECs for arsenic, lead, manganese and nickel are well below 100% of the AQAL, and so the impacts can be screened out. Using the Environment Agency guidance criteria, it can be concluded that there is no risk of exceeding the long-term AQAL for all metals, with the exception of chromium (VI).

The predicted process contribution for chromium (VI) exceeds 1% of the AQAL and the PEC exceeds 100% of the AQAL. However, this assumes that each metal is released at the maximum concentration monitored at an existing facility. The average concentration monitored at an existing facility is 0.001 ng/m³. Using this as the emission concentration for the Proposed Development, the impact is predicted to be 0.92% of the AQAL. Hence, this can be screened out and there is no potential for significant pollution.

Slough Borough Council asked for clarification that use of the average chromium VI discharge concentration is appropriate. The concentration of chromium (VI) in the emissions to atmosphere is not measured at the current facility, or at any EfW facilities, as the concentration is too low to be measured. The specification of chromium into the different species is measured in the APC residues. The analysis presented in the EA’s metal guidance uses the measured concentration of total chromium and the fraction of chromium (VI) in the APC residues to calculate a concentration of chromium (VI).

The twelve most recent measurements of chromium at the existing plant were between 0.006 mg/Nm3 and 0.0249 µg/Nm3, with an average of 0.0117 µg/Nm3. The EA metals guidance has an average measured concentration of 0.0084 mg/Nm3 and a maximum concentration of 0.092 mg/Nm3. This confirms that emissions from the current facility are more similar to the average across the UK rather than the peak.

The waste for the new Facility will be the same as that for the existing facility, so it is reasonable to assume that the concentration of chromium would also be similar as this is dependent on the fuel composition. Therefore, it is appropriate to use the mean chromium (VI) data for the purpose of the assessment to represent likely impacts from the new Facility.

6.7.12.2 Short-term results

As shown, even if it is assumed that each metal is released from the Proposed Development at the total metal ELV, the maximum 1-hour process contribution at the point of maximum impact is predicted to be less than 10% of the short-term AQAL, with the exception of vanadium. However, the PEC for vanadium is well below 100% of the AQAL, and so the impacts can be screened out. Therefore, using the Metals Guidance criteria, it can be concluded that:

• there is no risk of exceeding the short-term AQAL for any metal;

• there is no potential for significant pollution;

• the impact can be ‘screened out’ under the first-stage assessment; and

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• there is no requirement for further assessment using the second-stage methodology.

6.7.13 Impact at ecological receptors

6.7.13.1 Calculation methodology – nitrogen deposition

The impact of deposition has been assessed using the methodology detailed within the Habitats Directive AQTAG 6 (March 2014). The steps to this method are as follows.

1. Determine the annual mean ground level concentrations of nitrogen dioxide and ammonia at each site.

2. Calculate the dry deposition flux (µg/m2/s) at each site by multiplying the annual mean ground level concentration by the relevant deposition velocity presented in Table 61.

3. Convert the dry deposition flux into units of kgN/ha/yr using the conversion factors presented in Table 61.

4. Compare this result to the nitrogen deposition Critical Load.

Table 61: Deposition Factors

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

Grassland Woodland

Nitrogen dioxide 0.0015 0.003 96.0

Sulphur dioxide 0.0120 0.024 157.7

Ammonia 0.0200 0.030 259.7

Hydrogen chloride 0.0250 0.060 306.7

6.7.13.2 Calculation methodology - acidification

Deposition of nitrogen, sulphur, hydrogen chloride and ammonia can cause acidification and should be taken into consideration when assessing the impact of the Proposed Development.

The steps to determine the acid deposition flux are as follows.

1. Determine the dry deposition rate in kg/ha/yr of nitrogen, sulphur, hydrogen chloride and ammonia using the methodology outlined above.

2. Apply the conversion factor for N outlined in Table 61 to the nitrogen and ammonia deposition rate in kg/ha/year to determine the total keq N/ha/year.

3. Apply the conversion factor for S to the sulphur deposition rate in kg/ha/year to determine the total keq S/ha/year.

4. Apply the conversion factor for HCl to the hydrogen chloride deposition rate in kg/ha/year to determine the dry keq Cl/ha/year.

5. Determine the wet deposition rate of HCl in kg/ha/yr by multiplying the model output by the factors presented in Table 62.

6. Apply the conversion factor for HCl to the hydrogen chloride deposition rate in kg/ha/year to determine the wet keq Cl/ha/year.

7. Add the contribution from S to HCl dry and wet and treat this sum as the total contribution from S.

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8. Plot the results against the Critical Load functions.

Table 62: Conversion Factors

Pollutant Conversion Factor (kg/ha/year to keq/ha/year)

Nitrogen Divide by 14

Sulphur Divide by 16

Hydrogen chloride Divide by 35.5

The March 2014 version of the AQTAG 6 document states that, for installations with an HCl emission, the PC of HCl, in addition to S and N, should be considered in the acidity Critical Load assessment. The H+ from HCl should be added to the S contribution (and treated as S in the APIS tool). This should include the contribution of HCl from wet deposition.

Consultation with AQMAU confirmed that the maximum of the wet or dry deposition rate for HCl should be included in the calculation. For the purpose of this analysis it has been assumed that wet deposition of HCl is double dry deposition.

The contribution from the Proposed Development has been calculated using the APIS formula:

Where PEC N Deposition < CLminN:

PC as % of CL function = PC S deposition / CLmaxS

Where PEC N Deposition > CLminN:

PC as % of CL function = (PC S + N deposition) / CLmaxN

6.7.12.36.7.13.3 Atmospheric emissions - Critical Levels

The impact of emissions from the Proposed Development has been compared to the Critical Levels listed in Table 13. In accordance with the stated assessment methodology, further assessment would be undertaken where the PC of a particular pollutant is greater than 1% of the long term or 10% of the short-term Critical Level for European and UK designated sites, and where the PC of a particular pollutant is greater than 100% of the Critical Level for locally-designated sites. The process contribution has been calculated based on the maximum predicted using all five years of weather data.

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Table 63: Impact of Emissions at Ecological Sites – as % of Critical Level

As shown in Table 63, at all locally designated ecological sites the process contribution is less than 100% of the Critical Level for all pollutants considered. Therefore, the impact of the Proposed Development can be screened out as ‘not significant’.

At all European and UK statutory designated sites the process contribution is less than 1% of the long-term and less than 10% of the short-term Critical Level for all pollutants and can be screened out as ‘not significant’.

6.7.12.46.7.13.4 Deposition of emissions - Critical Loads

In addition to the Critical Levels for the protection of ecosystems, habitat specific Critical Loads for nature conservation sites at risk from acidification and nitrogen deposition (eutrophication) are outlined in the APIS.

An assessment has been made for each habitat feature identified in APIS for the specific site. The site-specific features tool has been used to identify the feature habitats, and then the search by location tool to find the habitat specific Critical Load for the specific points assessed within the designated sites. The relevant Critical Loads are presented in Appendix C [APIS Critical Loads].

If the impact of process emissions upon nitrogen or acid deposition is greater than 1% of the Critical Load, further assessment has been undertaken.

APIS does not include site specific Critical Loads for non-designated sites. In lieu of this, the search by location function of APIS has been used. The Critical Loads using this function are based on a broad habitat type and location.

6.7.12.56.7.13.5 Deposition of emissions - Critical Loads - results

Appendix D [Deposition Analysis at Ecological Sites] presents the results at each of the identified statutory designated ecological receptors. The contribution from the Proposed Development has been assessed against the most sensitive feature in each statutory designated site.

Site NOx SO2 HF NH3

Annual Mean

Daily Mean

Annual Mean

Weekly Mean

Daily Mean

Annual Mean

European designated sites (within 10km) and UK designated sites (within 2km)

South West London Waterbodies

0.7% 4.7% 0.3% 2.9% 0.7% 0.7%

Windsor Forest & Great Park (1) 0.3% 1.4% 0.3% 0.9% 0.2% 0.9%

Locally designated sites (within 2km)

Old Wood (1) 3.4% 26.9% 2.9% 12.9% 4.0% 9.7%

Old Slade Lake(1) 10.8% 39.2% 9.5% 30.2% 5.9% 31.5%

Opposite Iver Station (1) 1.6% 5.5% 1.4% 3.2% 0.8% 4.7%

Lower Colne(1) 3.2% 7.3% 2.8% 5.7% 1.1% 9.5%

Queen Mother Reservoir(1) 0.8% 6.7% 0.7% 4.9% 1.0% 2.4%

Notes:

(1) Lower critical levels for sulphur dioxide (10 µg/m³) and ammonia (1 µg/m³) for the protection of lichens and bryophytes have been applied.

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As shown in Appendix D, at all locally designated sites the process contribution is less than 100% of the relevant Critical Loads, and the impact of the Proposed Development can be screened out as ‘not significant’.

At all identified European and UK statutory designated sites, the process contribution is less than 1% of the relevant Critical Loads and can be screened out as ‘not significant’.

6.7.14 Additional assessment of Windsor Forest and Great Park

Windsor Park and Great Park SAC is located 7km to the south-west of the proposed development. The closest point in the site to the proposed development was identified and used in the assessment. However, following consultations with Slough BC after the application was submitted, it has been accepted that the SAC, although distant from the proposed development, is large enough that it is appropriate to consider more than one point.

The modelling has been re-run with a modified grid extend to cover the SAC with the same spatial resolution as the standard modelling domain. The maximum annual mean ammonia concentration across the SAC, as a percentage of the Critical Level for lichen sensitive communities, has been calculated as 1.1%. This occurs in the eastern corner of the SAC for some, but not all, years of weather data. However, this does not account for the contribution already been made by the existing EfW and HTI plants, which will be decommissioned if and when the new facilities are operational. To determine the net change in impact, for each point the maximum predicted impact at the same point from the existing EfW and HTI has been subtracted from the impact of the proposed development. This has shown that at any point in the SAC the maximum net impact is 0.55% of the Critical Level for lichen sensitive communities.

A plot file showing the maximum net change in impact as a percentage of the Critical Level for lichen sensitive communities is provided in Figure 23). As shown, the net change in impact is well below 1% across the SAC. Therefore, the impact of ammonia emissions can be screened out as insignificant at Windsor Park and Great Park SAC.

6.8 Modelling Results – Commissioning

6.8.1 Results at the point of maximum impact

Table 64 presents the predicted impact of process emissions for the five modelled years (2014 – 2018) at the point of maximum impact for the commissioning phase of the Proposed Development. The results presented are limited to annual mean nitrogen dioxide, maximum hourly hydrogen chloride, and all pollutants which are assessed using percentiles. A discussion of the implications for all other pollutants is presented below Table 64.

The results are compared to the relevant AQALs. Impacts that do not screen out as ‘insignificant’ in accordance with Environment Agency guidance are highlighted, and impacts that cannot be described as ‘negligible’ irrespective of the total concentration in accordance with the IAQM 2017 criteria are shown in bold.

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Table 64: Dispersion Modelling Results for Commissioning Phase of Proposed Development – Point of Maximum Impact



2014 2015 2016 2017 2018 Conc. Max as % of

AQAL


Nitrogen dioxide

Annual mean µg/m³ 40 27.5 2.10 2.66 1.95 2.00 1.65 2.66 6.64% 30.16 75.39%

99.79th %ile of hourly means

µg/m3 200.00 55.00 24.29 23.35 22.70 22.67 23.17 24.29 12.15% 79.29 39.65%

Sulphur dioxide

99.18th %ile of daily means

µg/m³ 125 66.00 7.19 6.94 5.86 5.73 5.11 7.19 5.75% 73.19 58.55%

99.73rd %ile of hourly means*

µg/m³ 350 66.00 31.59 30.21 29.47 29.69 30.12 31.59 9.02% 97.59 27.88%

99.9th %ile of 15 min. means*

µg/m³ 266 66.00 35.34 34.31 33.77 34.19 34.34 35.34 13.29% 101.34 38.10%

Particulates (PM10)

90.41 %ile of daily means

µg/m³ 50 30.00 0.49 0.58 0.44 0.46 0.38 0.58 1.17% 30.58 61.17%

Carbon monoxide

8 hour running mean†

µg/m³ 10,000 1012.00

14.18 14.59 14.64 14.45 13.95 14.64 0.15% 1026.64 10.27%

Carbon monoxide

Hourly mean *

µg/m³ 30,000 1012.00

60.18 55.50 78.63 54.80 88.20 88.20 0.29% 1100.20 3.67%

Hydrogen chloride

Hourly mean*

µg/m³ 16 1.40 21.90 21.31 31.45 21.10 35.28 35.28 4.70% 36.68 4.89%

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As shown in Table 64, the long-term and short-term impacts from the commissioning phase of the Proposed Development are predicted to be lower than the base-case scenario at the point of maximum impact. As Table 64 considers the impact over all relevant averaging periods, it is concluded that the impact of the commissioning phase is lower than the base-case scenario for all pollutants at the point of maximum impact.

The change in impact at certain sensitive receptors closer to the operational Lakeside Facility are predicted to be higher than in the best-case scenario. However, due to the decommissioning of one line, the impacts at these receptors will be lower than the impact with the currently permitted Lakeside Facility.

6.9 Plume Visibility

6.9.1 Base assumptions

The plume visibility assessment has been undertaken using ADMS 5.2. The assessment has been undertaken on the basis of a plume moisture content from the EfW of 16.1% by volume, or 0.115 kg water per kg dry gas, and gas exit temperature of 140°C, and a plume moisture content from the HTI of 8.9% by volume, or 0.059 kg water per kg dry gas, and gas exit temperature of 140°C

6.9.2 Plume visibility results

Table 65 details the plume visibility results during daylight hours.

Table 65: Plume Visibility Results

Weather Data Year

Percentage of daylight hours the plume is visible

Percentage of daylight hours with a visible

plume extending beyond Site boundary

Furthest distance from stack a plume is visible

(m)

2014 5.9% 2.3% 284

2015 6.6% 1.7% 241

2016 8.3% 2.9% 289

2017 8.3% 2.9% 393

2018 9.9% 3.2% 284

A visible plume extends beyond the Site boundary for less than 5% of daylight hours. In accordance with the EA significance criteria detailed in Table 14, as the plume length exceeds the distance to the site boundary for less than 5% of the year and there are local sensitive receptors, the visual impact of the plume is assessed to be ‘low’. In addition, although visible plumes are predicted to occasionally extend over the M4 motorway, the results of the modelling show that there are no occasions where a visible plume reaches the ground. Therefore, there is no risk of a visible plume causing obscured vision for drivers on the M4 motorway or any other road.

A visual representation of the maximum distance a visible plume extends in each direction from the stack is shown in Figure 22. The furthest distance from the stack visible plume is predicted to reach is 393 m.

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6.10 Operational phase traffic emissions As the Proposed Development is a like-for-like replacement for the existing Facilities, the operational traffic already forms the existing baseline. The only change to traffic during the operational phase is that the Site access for the Proposed Development is slightly further west along the A4 than the site access for the existing facilities. Therefore, there will only be a net change in development-generated traffic between the existing site access and the Proposed Development Site access. There are no residential sensitive receptors along this stretch of road. As such, there is no relevant exposure and it is concluded that the impact of operational phase traffic emissions is ‘negligible’.

6.11 Significance of effect Professional judgement has been used to determine the resulting significance of the effect of emissions associated with the operation of the Proposed Development. This judgement has been based on dispersion modelling using the following conservative assumptions:

• the Proposed Development will continually operate at the ELVs, except for the pollutants detailed below;

• the worst-case assumption for the conversion of NOx to nitrogen dioxide has been applied;

• the Proposed Development will operate at the short-term ELVs during worst-case meteorological conditions for dispersion; and

• the impacts presented are based on the maximum concentrations from five years of weather data.

The assessment has shown that the operation of the Proposed Development will not cause a breach of any AQAL, and the annual mean magnitude of change can be described as no worse than ‘slight adverse’ for all pollutants at all areas of relevant exposure. This judgment has been based on typical speciation and emissions of VOCs, cadmium and chromium (VI) from existing waste incineration facilities, and operation at the ELVs for all other pollutants.

The magnitude of change of short-term nitrogen dioxide and sulphur dioxide concentrations is described as ‘slight adverse’ at some areas of relevant exposure, but the extent of these impacts is limited and is only predicted to occur under the conservative assumptions listed above. As noted in Section 3.5, the IAQM 2017 guidance states that the significance of effect “will be governed by the long-term exposure experienced by receptors and it will not be a necessity to define the significance of effects by reference to short-term impact”. Therefore, we conclude that the overall effect of the Proposed Development on local air quality will be ‘not significant’. As such, there should be no air quality constraint in granting planning permission for the Proposed Development.

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7 Mitigation and Monitoring

7.1 Operational phase No additional mitigation is required beyond that imbedded into the design and required by legislation that will be regulated by the Environment Agency under the Environmental Permit. This is described in chapter 3 of the Environmental Statement.

The effect of reducing the building height was considered at an earlier stage of the project. This analysis set out that it may be possible to lower the entire building by up to 5m by additional excavation, but it would be necessary to make more fundamental changes to reduce the height any further. In addition, consideration should be made of underground services such as the underground network and the new Heathrow rail link, which might make excavations impractical. The analysis showed that lowering the building by 5m would reduce the peak impact, which occurs in a field to the north of the M25 where there are no residential receptors. When considering the distribution of emissions, the ground level impacts would be slightly lower at the areas of relevant exposure, but the overall conclusions of the assessment would be the same.

7.2 Construction Phase The construction dust assessment has identified the Site as a 'medium risk' site. Appropriate mitigation measures will be based on best practice for a site and will be detailed in a Construction Environmental Management Plan (CEMP) for the Proposed Development. A framework CEMP is included in technical appendix C of the ES. Appropriate mitigation measures for a site of this size and nature that could be implemented are as follows:

• Display the name and contact details of person(s) accountable for dust issues on the Site boundary. This may be the environment manager / engineer or the Site manager.

• Display the head or regional office contact information.

• Record all dust and air quality complaints, identify cause(s), take appropriate measures to reduce emission in a timely manner, and record the measure taken.

• Make the complaints log available to the local authority (Slough Borough Council) when asked.

• Record any exceptional incidents that cause dust and/or air emission, either on- or off- site, and the action taken to resolve the situation in the logbook.

• Plan site layout so that machinery and dust causing activities are located away from receptors, as far as possible.

• Keep site fencing, barriers and scaffolding clean using wet methods.

• Remove materials that have a potential to produce dust from site as soon as possible, unless being re-used on site. If they are being re-used on-site cover, seed or fence stockpiles to prevent wind whipping.

• Ensure all on vehicles switch off engines when stationary - no idling vehicles.

• Only use cutting, grinding or sawing equipment fitted or in conjunction with suitable dust suppression techniques such as water sprays or local extraction, e.g. suitable local exhaust ventilation systems.

• Ensure an adequate water supply on the Site for effective dust / particulate matter suppression /mitigation, using non-potable water where possible and appropriate.

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• Ensure equipment is readily available on site to clean any dry spillages and clean up spillages as soon as reasonably practicable after the event using wet cleaning methods.

• Prohibit bonfires and burning of waste materials.

• Ensure sand and other aggregates are stored in designated areas and are not allowed to dry out, unless this is required for a particular process, in which case ensure that appropriate additional control measures are in place.

• Ensure vehicles entering and leaving the Site are covered to prevent escape of materials during transport.

• Implement a wheel washing system.

• Ensure there is an adequate area of hard surfaced road between the wheel wash facility and the Site exit.

The mitigation measures stated above are based on best practice for a site of the size and nature. It is considered that with the implementation of these measures any residual impacts would not be significant, either alone or in-combination with other developments.

However, the Applicant can confirm that it will implement the highly recommended measures in the IAQM guidance if appropriate. In addition to those above, these include:







• Fully enclose site or specific operations where there is a high potential for dust production and the site is actives for an extensive period;





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8 Residual Effects

8.1 Construction Phase The impact of construction phase dust emissions will be mitigated by the implementation of mitigation measures such as those detailed in Section 7. These mitigation measures are based on best practice for a site of this size and nature and scale of the Proposed Development. With the implementation of these measures any residual construction dust impacts will be ‘negligible’ and the residual effect will be not significant.

8.2 Operational Phase No additional mitigation measures have been recommended and therefore the effects will remain as described in Section 7.

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9 Cumulative Effects A number of local projects have been identified which may have cumulative effects with the Proposed Development. These are:

1. The Cemex Langley Site north of North Park Road;

2. Cemex operations at Datchet Quarry;

3. Thorney Mill/Link Park Heathrow; and

4. The M4 Smart Motorway; and

4.5. The M25 junction 10/A3 Wisley interchange improvement.

However, none of these cumulative schemes include process emissions, and therefore have no potential for cumulative impacts with emissions from the stack of the Proposed Development.

The North Park Cemex project has the potential to generate dust from mineral activities. However, the site is approximately 1km from the Site boundary and cumulative impacts are considered extremely unlikely at that distance. In addition, the environmental statement for North Park concludes that the magnitude of dust effects at receptors would be ‘negligible’.

Each of these schemes is considered below. ThereforeFor the reasons set out below, it is concluded that there is no potential for significant cumulative effects with the above schemes.

9.1 Cemex Langley This scheme does not include any process emissions.

The Environmental Statement for the scheme explains that traffic for the scheme will access the motorway network via North Park (but only the western direction away from Richings Park), Sutton Lane and junction 5 of the M4. This affects the Slough AQMA around the M4 junction but doesn’t affect residents in Richings Park. The impacts of the Proposed Development on the Slough AQMA are considered in the Environment Statement.

During construction, there will be additional traffic flows through the Slough AQMA but the impact on the AQMA will be negligible. The greatest impact of the additional traffic is at Disraeli Court, on the corner of Sutton Lane and London Road. This is receptor RR6 in this assessment. The Cemex Langley ES also includes receptors in this area – their receptors R8 and R9. The predicted ground level concentration due to the Cemex traffic at these receptors is 0.2 to 0.3 ug/m3. The impact of the Proposed Development is 0.4 ug/m3 and the predicted environmental concentration (PEC) is 37.39 ug/m3. Both impacts are negligible as they are 1% or less of the AQAL. Adding the Cemex Langley impact to the PEC gives a total concentration of 37.39 ug/m3, so there is still no exceedance predicted.

During operation, there will be no change to traffic flows as a result of the Proposed Development and impacts from process emissions are negligible, as illustrated in Figure 12 in Appendix D. The predicted process contribution for nitrogen dioxide at receptor R8 in this assessment, which is on London Road, is 0.08 ug/m3, which is less than the impact of construction traffic.

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9.2 Cemex Datchet The Environmental Statement for Cemex at Datchet Quarry shows that traffic accesses the M4 via Riding Court Road and Ditton Road, joining the A4 north of junction 5 of the M4. Therefore, there is no overlap with traffic for the Proposed Development, nor with the process emissions.

9.3 Thorney Mill/Link Park Heathrow For this scheme, some of the traffic travels along North Park and Richings Way, so there may be a cumulative impact with the process emissions from the Proposed Development. There is no overlap with traffic movements.

Receptor R17 for the Proposed Development is close to receptors in the Thorney Mill air quality assessment, and receptors R4 and R5 for Thorney Mill are along Richings Way. The predicted impact at these receptors for Thorney Mill is 0.07 – 0.24 ug/m3, with the maximum at receptor R4. This is a negligible impact.

We have evaluated the combined impact on annual nitrogen dioxide emissions at our receptor R17 (Thorney Mill receptor R3) and Thorney Mills receptor R4, for which there is no direct analogue. We note that this may be excessive given that the contributions of each development individually is negligible.

At R17, the background concentration is taken as 37.3 ug/m3 (see section 6.7.2 above) and the PEC is 37.5 ug/m3. The contribution of Thorney Mill at its receptor R3 is 0.16 ug/m3. Therefore, there is no exceedance of the AQAL.

Along Richings Way, the background concentration is taken as 36.7 ug/m3. The contribution of the Proposed Development at Thorney Mill’s receptor R4 is around 0.35 ug/m3 while the contribution from Thorney Mill is 0.24 ug/m3. Hence, the total predicted concentration is 37.3 ug/m3 so there is no exceedance.

9.4 M4 Smart Motorway The air quality impacts of the M4 Smart Motorway were considered very thoroughly as part of the DCO Application process in 2015/2016. South Bucks District Council participated in the process and agreed a statement of common ground with the Applicant, in which they agreed that “the requirements in the Application meet South Bucks District Council’s concerns in relation to Air Quality.”

The air quality assessment for the M4 Smart Motorway specifically considered the impact at Old Slade Lane, with receptor X20 (shown on drawing 6.13 in the DCO Application) located at the most southern house, which is the same location as receptor R1 in this air quality assessment. The detailed results for this receptor can be found on page 139 of Appendix 6.6 in the DCO Application. The change in concentration as a result of the scheme was predicted to be +0.3 µg/m3. This is not a significant increase. If this contribution is added to the background concentration and the contribution from the Proposed Development, the total concentration is predicted to be 30.49 µg/m3, which is still well below the air quality standard of 40 µg/m3.

9.5 M25 Junction 10 This scheme is located approximately 20 km to the south of the Proposed Development (as the crow flies). Therefore, there is little risk of cumulative impacts with the Proposed Development.

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Therefore, it is concluded that there is no potential for significant cumulative effects with the above schemes.

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10 Summary and Conclusions The impact of the Proposed Development has been assessed as part of this assessment using industry standard approaches. The main air quality effect would be as a result of emissions from the stack of the Proposed Development.

Within this air quality assessment, the following two scenarios have been considered:

• The Proposed Development operating at the emission limits as set out in Table 39 (“Main Case”); and

• The Proposed Development operating one line at the emission limits as set out in Table 39 simultaneously with one line of the operational Lakeside EfW and CWI operating at the IED limits (“Commissioning Phase”).

This assessment has included a review of baseline pollution levels, dispersion modelling of emissions and quantification of the impact of these emissions on local air quality.

The primary conclusions of the assessment are presented below.

1. In relation to the impact on human health:

a. Using the IAQM 2017 screening criteria, the impact of all long-term process emissions associated with the ‘Main Case’ scenario can be considered ‘negligible’ at the point of maximum impact with the exception of the following pollutants:



iii. Annual mean particulate matter (as PM10);

iv. Annual mean particulate matter (as PM2.5);

v. Annual mean VOCs;

vi. Annual mean cadmium; and

vii. Annual mean PaHs.

b. In accordance with Environmental Agency Guidance, the impact of all long-term process emissions associated with the ‘Main Case’ scenario can be considered ‘not significant’ at the point of maximum impact with the exception of the following pollutants:



iii. Annual mean particulate matter (as PM2.5);

iv. Annual mean VOCs; and

v. Annual mean cadmium;

2. For all of the pollutants listed above, the magnitude of change assessed in accordance with IAQM 2017 criteria is no worse than ‘slight adverse’ at all areas of relevant exposure.

3. In relation to the impact on ecologically sensitive sites:

a. At all of the statutory designated sites, the impact of process emissions from the ‘Main Case’ scenario of the Proposed Development can be screened out as ‘not significant’.

b. At all non-statutory designated sites, the impact of process emissions from the ‘Main Case’ scenario of the Proposed Development can be screened out as ‘not significant’.

4. The impact of all long-term and short-term process emissions associated with the commissioning phase scenario is no higher than process emissions associated with the best-case scenario.

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Based on the above, professional judgement has been used to determine the resulting significance of the effect of emissions associated with the operation of the Proposed Development.

The assessment has shown that the operation of the Proposed Development will not cause a breach of any AQAL, and the annual mean magnitude of change can be described as no worse than ‘slight adverse’ for all pollutants at all areas of relevant exposure. Therefore, we conclude that the overall effect of the Proposed Development on local air quality will be ‘not significant’.

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11 References European Parliament and Council, 2008, Directive 2008/80/EC on ambient air quality and cleaner air for Europe.

European Parliament and Council, 2004, Directive 2004/107/EC relating to arsenic, cadmium, mercury, nickel and polycyclic aromatic hydrocarbons in ambient air.

Her Majesty’s Stationary Office (HMSO), 2010, Statutory Instrument 2010 No. 1001 Air Quality Standards Regulations 2010.

HMSO, 1995, The Environment Act (1995)

Department for Environment, Food and Rural Affairs (Defra), 2007, The Air Quality Strategy for England, Scotland, Wales and Northern Ireland

Defra, 2019, Clean Air Strategy 2019

HMSO, 2016, The Environmental Permitting (England and Wales) (Amendment) (No. 2) Regulations 2016.

The Air Pollution Information System (APIS) website: http://www.apis.ac.uk/

Environment Agency, 2016, Air Emissions Risk Assessment for Your Environmental Permit Guidance

Defra, 2018, National Atmospheric Emissions Inventory: Air Pollution Inventories for England, Scotland, Wales and Northern Ireland: 1990-2016

Institute of Air Quality Management (IAQM), 2014, Guidance on the Assessment of Dust from Demolition and Construction

Environmental Protection UK (EPUK) & IAQM, 2017, Land-Use Planning & Development Control: Planning for Air Quality

Environment Agency, 2016, Guidance on assessing group 3 metals stack emissions from incinerators - V.4

Environment Agency, 2012, Operational Instruction 67_12 - Detailed assessment of the impact of aerial emissions from new or expanding IPPC regulated industry for impacts on nature conservation

Environment Agency, 2012, Operational Instruction 66_12 - Simple assessment of the impact of aerial emissions from new or expanding IPPC regulated industry for impacts on nature conservation

Environment Agency, 2013, AQTAG 17 – Guidance on in combination assessments for aerial emissions from Environmental Permitting Regulations (EPR) permits

Environment Agency, 2003, Horizontal Guidance Note IPPC H1 Integrated Pollution Prevention and Control (IPPC) Environmental Assessment and Appraisal of BAT

Defra, 2018, Local Air Quality Management – Technical Guidance (TG)16

Expert Panel on Air Quality Standards (EPAQS), 2006, Guidelines for Halogens and Hydrogen Halides in Ambient Air for Protecting Human Health against Acute Irritancy Effects

Department for Transport (DfT) Traffic Counts website: https://roadtraffic.dft.gov.uk/#6/55.254/-6.064/basemap-regions-countpoints

Cambridge Environmental Research Consultants (CERC), 2004, Note 60, Modelling Queuing Traffic

Defra, 2018, Nitrogen dioxide fall off with distance calculator v4.2

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Appendices

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Appendices

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A Figures Figure 1: Site Location

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Figure 2: Mapped Background Nitrogen Dioxide concentrations

Source: UK Air – background mapping data for local authorities

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Figure 3: Nitrogen Dioxide measured concentrations

Source: Local authority reports and AURN database

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Figure 4: Nitrogen dioxide - mapped and measured concentrations

Source: Local authority reports and AURN database

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Figure 5: Human Sensitive Receptors

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Figure 6: Roads Modelling Setup

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Figure 7: Monitoring Sites for Roads Model Verification

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Figure 8: Ecological Sensitive Receptors

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Figure 9: Modelling Domain

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Figure 10: Wind Roses

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Figure 11: Building Details

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Figure 12: Annual Mean NO2 Analysis – Main Case

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Figure 13: 99.79%ile 1-hour Nitrogen Dioxide Analysis

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Figure 14: Annual Mean PM 10 Analysis

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Figure 15: Annual Mean PM 2.5 Analysis

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Figure 16: Annual Mean VOCs (as benzene) Analysis

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Figure 17: Annual Mean VOCs (as 1,3-Butadiene) Analysis

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Figure 18: Annual Mean Cadmium ‘Typical Scenario’ Analysis

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Figure 19: Annual Mean PaH Analysis

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Figure 20: 99.73rd %ile of 1-Hour Sulphur Dioxide Analysis

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Figure 21: 99.9th %ile of 15. Min Sulphur Dioxide Analysis

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Figure 22: Plume Visibility

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Figure 23: Ammonia, annual average

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B Roads Modelling Verification Procedure The ADMS Model has been validated against real world monitoring, however LAQM.TG(16) recommends that the model output is verified. The verification process should involve the comparison between predicted and measured concentrations at one or more suitable local sites and forms an essential component of a detailed assessment for road traffic models. Part of the verification process involves improvements to the base model to provide a better representation of the monitored data. This includes checks on:

• Traffic data;

• Road widths;

• Distance between sources and monitoring locations;

• Speed estimates;

• Street canyons;

• Background concentrations; and

• Monitoring data.

All of these have been reviewed and the model refined to increase the accuracy as much as possible.

Five monitoring locations have been identified as suitable for model verification. The results of the verification procedure are detailed below.

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Table 66: Verification Procedure: Initial Comparison (All Pollutant Concentrations Expressed as µg/m³)

Monitoring Site

Location 2017 monitored

NO2

2017 mapped background

NO2

2017 monitored

road NOx

2017 modelled road NOx

Ratio of monitored to

modelled road NOx

2017 modelled total NO2

Ratio of monitored to

modelled total NO2

X Y

SLO9 501501 177879 35.3 23.8 26.0 17.5 1.5 31.73 0.90

SLO10 501733 177725 45.3 23.8 52.3 36.9 1.4 39.59 0.87

SLO39 501734 177733 33.1 23.8 20.7 24.7 0.8 34.75 1.05

SLO45 501658 177781 31.4 23.8 16.8 20.1 0.8 32.81 1.04

SLO28 501941 177633 45.3 23.8 52.3 29.5 1.8 36.68 0.81

Note: All NOx to NO2 conversions undertaken using DEFRA’s NOx to NO2 calculator V7.1, for 2017 and using the ‘All London traffic’ traffic mix setting.

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In lieu of sufficient roadside monitoring to undertake verification for modelled concentrations of PM10 and PM2.5, as set out in LAQM.TG(16) the model adjustment factor for NO2 (1.3469) has been applied to the modelled road-PM10 and road-PM2.5

outputs.

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C APIS Critical Loads Table 68: Nitrogen Deposition Critical Loads

Site Habitat Type NCL Class Lower Critical Load

(kgN/ha/yr)

Upper Critical Load

(kgN/ha/yr)

Maximum Backgroun

d (kgN/ha/yr

)

European designated sites (within 10km)


Standing open water and canals

No comparable habitat with established critical load estimate available

- - 11.2

Windsor Forest & Great Park Old acidophilous oak woods with Quercus robur on sandy plains (H9190)

Acidophilous Quercus-dominated woodland 10 15 28.14


Old Wood Broadleaved, Mixed and Yew Woodland

Acidophilous Quercus-dominated woodland 10 20 30.8

Old Slade Lake Broadleaved, Mixed and Yew Woodland

Broadleaved deciduous woodland 10 20 30.66

Opposite Iver Station Neutral grassland Low and medium altitude hay meadows 20 30 17.78

Lower Colne Neutral grassland Low and medium altitude hay meadows 20 30 17.78

Queen Mother Reservoir Standing open water and canals

No comparable habitat with established critical load estimate available

- - -

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Table 69: Acid Deposition Critical Loads

Site Habitat Type Acidity Class Minimum Critical Load Function for each habitat present (keq/ha/yr)

Maximum Background (keq/ha/yr)

CLminN CLmaxN CLmaxS N S



Standing open water and canals

Not sensitive - - - 0.8 0.25

Windsor Forest & Great Park

Old acidophilous oak woods with Quercus robur on sandy plains (H9190)

Unmanaged Broadleafed/Coniferous Woodland

0.357 2.756 2.399 1.82 0.22


Old Wood Broadleaved, Mixed and Yew Woodland


0.357 3.204 2.847 2.2 0.26

Old Slade Lake Broadleaved, Mixed and Yew Woodland


0.357 3.204 2.847 2.19 0.31

Opposite Iver Station Neutral grassland Calcareous grassland (using base cation)

1.071 5.071 4 1.27 0.26

Lower Colne Neutral grassland Calcareous grassland (using base cation)

1.071 5.071 4 1.27 0.26

Queen Mother Reservoir Standing open water and canals

Not sensitive - - - - -

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D Deposition Analysis at Ecological Sites

Table 70: Annual Mean Process Contribution used for Deposition Analysis

Site Annual Mean Process Contribution (ng/m³)

Nitrogen Dioxide

Sulphur Dioxide

Hydrogen Chloride

Ammonia

European and UK designated sites (within 10km)


152.8 64.3 12.8 21.3

Windsor Forest & Great Park 61.2 26.0 5.2 8.6


Old Wood 707.7 296.2 58.1 96.8

Old Slade Lake 2260.1 957.9 189.0 315.1

Opposite Iver Station 332.1 145.7 28.1 46.8

Lower Colne 673.9 292.9 56.8 94.7

Queen Mother Reservoir 169.2 70.7 14.3 23.8

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Table 71: Deposition Calculation – Grassland

Site Deposition Velocity Class

Dry Deposition (kg/ha/yr) Total N Deposition (kgN/ha/yr)

Acid Deposition keq/ha/yr

Nitrogen Dioxide

Sulphur Dioxide

Hydrogen Chloride

Ammonia N S



Grassland 0.02 0.12 0.10 0.11 0.13 0.01 0.01

Windsor Forest & Great Park Woodland 0.01 0.05 0.04 0.04 0.05 0.004 0.01


Old Wood Woodland 0.10 0.56 0.45 0.50 0.60 0.04 0.06

Old Slade Lake Woodland 0.33 1.81 1.45 1.64 1.96 0.14 0.19

Opposite Iver Station Grassland 0.05 0.28 0.22 0.24 0.29 0.02 0.03

Lower Colne Grassland 0.10 0.55 0.44 0.49 0.59 0.04 0.06

Queen Mother Reservoir Grassland 0.02 0.13 0.11 0.12 0.15 0.01 0.01

Note: This table presents the results for deposition over grassland for all sites, although for some sites the dominant deposition velocity class is Woodland.

Table 72: Deposition Calculation – Woodland




Nitrogen Dioxide

Sulphur Dioxide

Hydrogen Chloride

Ammonia N S


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Nitrogen Dioxide

Sulphur Dioxide

Hydrogen Chloride

Ammonia N S


Grassland 0.04 0.24 0.24 0.17 0.20 0.01 0.03

Windsor Forest & Great Park Woodland 0.01 0.10 0.10 0.07 0.08 0.01 0.01


Old Wood Woodland 0.20 1.12 1.07 0.75 0.96 0.07 0.13

Old Slade Lake Woodland 0.65 3.63 3.48 2.45 3.11 0.22 0.42

Opposite Iver Station Grassland 0.10 0.55 0.52 0.36 0.46 0.03 0.06

Lower Colne Grassland 0.19 1.11 1.05 0.74 0.93 0.07 0.13

Queen Mother Reservoir Grassland 0.05 0.27 0.26 0.19 0.23 0.02 0.03

Table 73: Detailed Results – Nitrogen Deposition

Site NCL Class Deposition Velocity

Process Contribution

PC N dep (kgN/ha/yr)

% of Lower CL % of Upper CL



No comparable habitat with established critical load estimate available Grassland 0.13 - -


Acidophilous Quercus-dominated woodland Woodland 0.08 0.85% 0.57%


Old Wood Broadleaved deciduous woodland Woodland 0.96 9.58% 4.79%

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Site NCL Class Deposition Velocity

Process Contribution

PC N dep (kgN/ha/yr)

% of Lower CL % of Upper CL

Old Slade Lake Broadleaved deciduous woodland Woodland 3.11 31.06% 15.53%

Opposite Iver Station Low and medium altitude hay meadows Grassland 0.29 1.45% 0.97%

Lower Colne Low and medium altitude hay meadows Grassland 0.59 2.94% 1.96%

Queen Mother Reservoir No comparable habitat with established critical load estimate available Grassland 0.15 - -

Table 74: Detailed Results – Acid Deposition

Site Acidity Class Deposition Velocity

Process Contribution Predicted Environmental Concentration

N (keq/ha/yr)

S (keq/ha/yr)

% of Min CL Function

N (keq/ha/yr)

S (keq/ha/yr)

% of Min CL

Function



Not sensitive Grassland 0.01 0.01 - 0.81 0.26 -



Woodland 0.01 0.01 0.64% 1.83 0.23 74.66%


Old Wood Unmanaged Broadleafed/Coniferous Woodland

Woodland 0.07 0.13 6.20% 2.27 0.39 82.98%

Old Slade Lake Unmanaged Broadleafed/Coniferous Woodland

Woodland 0.22 0.42 20.11% 2.412 0.733 98.14%

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Site Acidity Class Deposition Velocity

Process Contribution Predicted Environmental Concentration

N (keq/ha/yr)

S (keq/ha/yr)

% of Min CL Function

N (keq/ha/yr)

S (keq/ha/yr)

% of Min CL

Function

Opposite Iver Station Calcareous grassland (using base cation)

Grassland 0.02 0.03 0.99% 1.291 0.289 31.16%

Lower Colne Calcareous grassland (using base cation)

Grassland 0.04 0.06 2.00% 1.312 0.319 32.17%

Queen Mother Reservoir

Not sensitive Grassland 0.01 0.01 - 0.011 0.015 -

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Kingsgate (Floor 3), Wellington Road North, Stockport, Cheshire, SK4 1LW,

United Kingdom

t: +44 (0)161 476 0032 f: +44 (0)161 474 0618

www.fichtner.co.uk



28

Appendix 3 Amended Technical Appendix E: Health Risk Assessment

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Lakeside EfW

26 November 2019 Human Health Risk Assessment

S2680-0030-0005RDW Page 2

Document approval Name Signature Position Date Prepared by: Rhys Weir Environmental Scientist 23/05/2019

Stuart Nock Environmental Consultant

28/05/2019

Checked by: Stephen Othen Technical Director 28/05/2019

Document revision record Revision no Date Details of revisions Prepared by Checked by

0 28/05/2019 First issue RDW/SMN SMO

1 30/05/2019 Updated following comments SMN SMO

2 14/06/2019 Final issue SMN SMO

3 26/11/2019 Consultation amendments SMN SMO

© 2019 Fichtner Consulting Engineers. All rights reserved.

This document and its accompanying documents contain information which is confidential and is intended only for the use of Lakeside EfW. If you are not one of the intended recipients any disclosure, copying, distribution or action taken in reliance on the contents of the information is strictly prohibited.

Unless expressly agreed, any reproduction of material from this document must be requested and authorised in writing from Fichtner Consulting Engineers. Authorised reproduction of material must include all copyright and proprietary notices in the same form and manner as the original and must not be modified in any way. Acknowledgement of the source of the material must also be included in all references.

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Contents 1 Introduction ........................................................................................................................................................ 5

2 Issue Identification ............................................................................................................................................. 6 2.1 Issue ......................................................................................................................................................... 6 2.2 Chemicals of Potential Concern (COPC) ................................................................................................... 6

3 Assessment Criteria ............................................................................................................................................ 8 3.1 Chromium .............................................................................................................................................. 10 3.2 Cadmium ................................................................................................................................................ 10 3.3 Nickel ...................................................................................................................................................... 10

4 Conceptual Site Model ..................................................................................................................................... 11 4.1 Conceptual site model ........................................................................................................................... 11 4.2 Pathways excluded from assessment .................................................................................................... 13

4.2.1 Dermal absorption .................................................................................................................. 13 4.2.2 Groundwater .......................................................................................................................... 13 4.2.3 Surface water .......................................................................................................................... 13 4.2.4 Fish consumption .................................................................................................................... 14

5 Sensitive Receptors .......................................................................................................................................... 15

6 IRAP Model Assumptions and Inputs ............................................................................................................... 16 6.1 Concentrations in soil............................................................................................................................. 16 6.2 Concentrations in plants ........................................................................................................................ 16 6.3 Concentrations in animals ...................................................................................................................... 16 6.4 Concentrations in humans ..................................................................................................................... 16

6.4.1 Intake via inhalation ............................................................................................................... 16 6.4.2 Intake via soil ingestion .......................................................................................................... 17 6.4.3 Ingestion of food..................................................................................................................... 17 6.4.4 Breast milk ingestion .............................................................................................................. 17

6.5 Estimation of COPC concentration in media .......................................................................................... 17 6.6 Modelled emissions ............................................................................................................................... 18

7 Results .............................................................................................................................................................. 23 7.1 Assessment against TDI - point of maximum impact ............................................................................. 23

7.1.1 Cadmium ................................................................................................................................. 24 7.1.2 Chromium ............................................................................................................................... 25 7.1.3 Nickel ...................................................................................................................................... 25

7.1.3.1 Ingestion ............................................................................................................... 25 7.1.3.2 Inhalation .............................................................................................................. 26

7.1.4 Dioxins .................................................................................................................................... 26 7.2 Breast milk exposure .............................................................................................................................. 26 7.3 Assessment against ID - point of maximum impact ............................................................................... 26 7.4 Maximum impact at a receptor ............................................................................................................. 27 7.5 Uncertainty and sensitivity analysis ....................................................................................................... 29 7.6 Upset process conditions ....................................................................................................................... 29

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8 Conclusions ....................................................................................................................................................... 31

Appendices ................................................................................................................................................................. 32 A Detailed Results Tables .................................................................................................................................... 33 B Location of Sensitive Receptors ....................................................................................................................... 40

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1 Introduction Fichtner Consulting Engineers Ltd (Fichtner) has been engaged to undertake a Human Health Risk Assessment (HHRA) to support the planning application for the replacement Lakeside Energy from Waste plant and High Temperature Incinerator (HTI) (the Facility).

As the fuel combusted at the Facility will be sourced from waste, the limits on emissions to air will be based on those outlined in Chapter IV and Annex VI of the Industrial Emissions Directive (IED) (2010/75/EU) for waste incineration and co-incineration plants. This will include limits on emissions of heavy metals and dioxins and furans from the Facility. Within the IED, the requirements of the relevant sector Best Available Techniques(BAT) Reference document (BREF) become binding as BAT guidance.

The Final Draft Waste incineration BREF was published by the European IPPC Bureau in December 2018. Formal adoption of the BREF is expected in the third quarter of 2019. Upon adoption of the final BREF, the Environment Agency will be required to review and implement conditions within all permits which require operators to comply with the requirements set out in the BREF within four years of adoption. This will apply to the Facility. As currently drafted, the BREF will introduce BAT-Associated Emission Levels (BAT-AELs), some of which are more stringent than the Emission Limit Values (ELVs) currently set out in the IED. It has been assumed that emissions from the Facility will comply with the draft BAT-AELs.

The advice from health specialists such as the Health Protection Agency that the damage to health from emissions from incineration and co-incineration plants is likely to be very small, and probably not detectable. Nevertheless, the specific effects on human health of the proposed plant have been considered, and are presented in this report.

For most substances released from the Facility, the most significant effects on human health will arise by inhalation. The Air Quality Assessment Levels (AQALs) outlined within the Air Quality Assessment have been set by the various authorities at a level which is considered to present minimum or zero risk to human health. It is widely accepted that, if the concentrations in the atmosphere are less than the AQALs, then the pollutant is unlikely to have an adverse effect on human health.

For some pollutants which accumulate in the environment, inhalation is only one of the potential exposure routes. Therefore, other exposure routes are considered in this assessment.

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2 Issue Identification

2.1 Issue The key issue for consideration is the release of substances from the Facility to atmosphere which have the potential to harm human health. No other sources will include emissions of either metals or dioxins.

The existing Lakeside EfW and HTI facilities are on part of the land identified as being required for the proposed Heathrow expansion and would need to be demolished to accommodate this. Replacement EfW and HTI facilities are now therefore proposed on a ‘like for like’ basis on nearby land situated to the west of the Iver South Sludge Dewatering Centre and south of the M4 motorway.

The Facility will be designed to meet the BAT-AELs outlined in the Draft WI BREF. Limits have been set for pollutants known to be produced during the combustion of municipal waste which have the potential to impact upon the local environment either on human health or ecological receptors. These pollutants include:

• nitrogen dioxide, sulphur dioxide, particulate matter, carbon monoxide, ammonia;

• acid gases - hydrogen chloride, and hydrogen fluoride;

• total organic carbon;

• metals - mercury, cadmium, thallium, antimony, arsenic, lead, cobalt, copper, manganese, nickel and vanadium;

• dioxin and furans;

• dioxin like PCBs; and

• polycyclic aromatic hydrocarbons (PAHs).

For most substances released from the Facility, the most significant effects on human health will arise by inhalation. An Air Quality Assessment has been undertaken to determine the impact of atmospheric concentrations of the pollutants listed above based on the levels transposed under UK Law in the UK Air Quality Strategy and those set by the Environment Agency. These levels have been set at a level which is considered to present minimum or zero risk to human health.

Some pollutants, including dioxins, furans, dioxin-like polychlorinated biphenyls (PCBs) and heavy metals, accumulate in the environment, which means that inhalation is only one of the potential exposure routes. Therefore, impacts cannot be evaluated in terms of their effects on human health by simply reference to ambient air quality standards. An assessment needs to be made of the overall human exposure to the substances by the local population and the risk that this exposure causes.

2.2 Chemicals of Potential Concern (COPC) The substances which have been considered within this assessment are those which are authorised (as listed above). Although Emission Limit Values (ELVs) for PAHs are not currently set from installations, monitoring is required by legislation in the UK. Therefore, benzo(a)pyrene has been included in the assessment to represent PAH emissions. The following have been considered COPCs for the purpose of this assessment:

• PCDD/Fs (individual congeners) and dioxin like PCBs;

• Benzene;

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• Benzo(a)pyrene;

• Mercury (Hg);

• Mercuric chloride;

• Cadmium (Cd);

• Arsenic (As);

• Chromium (Cr), trivalent and hexavalent; and

• Nickel (Ni).

This risk assessment investigates the potential for long term health effect of these COPCs through other routes than just inhalation.

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3 Assessment Criteria IRAP calculates the total exposure through each of the different pathways so that a dose from inhalation and ingestion can be calculated for each receptor. By default, these doses are then used to calculate a cancer risk, using the USEPA’s approach. However, the Environment Agency recommends that the results be assessed using the UK’s approach, which is explained in the Environment Agency’s document “Human Health Toxicological Assessment of Contaminants in Soil”, ref SC050021. This approach involves two types of assessment: • For substances with a threshold level for toxicity, a Tolerable Daily Intake (TDI) is defined. This

is “an estimate of the amount of a contaminant, expressed on a bodyweight basis, which can be ingested daily over a lifetime without appreciable health risk.” A Mean Daily Intake (MDI) is also defined, which is the typical intake from background sources (including dietary intake) across the UK. In order to assess the impact of the Facility, the predicted intake of a substance due to emissions from the Facility is added to the MDI and compared with the TDI.

• For substances without a threshold level for toxicity, an Index Dose (ID) is defined. This is a level of exposure which is associated with a negligible risk to human health. The predicted intake of a substance due to emissions from the Facility is compared directly with the ID without taking account of background levels.

Substances can reach the body either through inhalation or through ingestion (oral exposure) and the body handles chemicals differently depending on the route of exposure. For this reason, different TDI and IDs are defined for inhalation and oral exposure.

The following table outlines the MDIs (the typical intake from existing background sources) for the pollutants released from the Facility. These figures are defined in the “Contaminants in soil: updated collation of toxicology data and intake values for humans” series of toxicological reports, available from the Environment Agency’s website. The values for nickel have been taken from the Environment Agency’s August 2015 document following the publication of the new expert opinion by the European Food Safety Authority.

Table 1: Mean Daily Intake of Each Substance

Substance Mean Daily Intake, 70 kg adult (µg/kg bw/day)

Mean Daily Intake, 20 kg child (µg/kg bw/day)

Intake Ingestion Intake, Inhalation


Arsenic 0.07 0.0002 0.19 0.0005

Benzene 0.04 2.9 0.11 7.4

Benzene(a)pyrene - - - -

Cadmium 0.19 0.0003 0.5 0.0007

Chromium 1.81 0.0009 4.70 0.002

Chromium VI 0.18 - 0.47 -

Methyl mercury 0.007 - 0.019 -

Mercuric chloride 0.014 - 0.037 -

Nickel 1.9 0.0037 4.96 0.0096

Dioxins and dioxin like PCBs

0.7 pg WHO-TEQ/kg bw/day 1.8 pg WHO-TEQ/kg bw/day

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Table 2: Tolerable Daily Intake of Each Substance (µg/kg bw/day)

Substance Index dose, Ingestion

Index dose, Inhalation

TDI, Ingestion TDI, Inhalation

Arsenic 0.3 0.002 - -

Benzene 0.29 1.4 - -

Benzene(a)pyrene 0.02 0.00007 - -

Cadmium - - 0.36 0.0014

Chromium - 0.001 3 -

Chromium VI - - 3 -

Methyl mercury - - 0.23 0.23

Mercuric chloride - - 2 0.06

Nickel - - 2.8 0.006


- - 2 pg WHO-TEQ/kg bw/day

To allow comparison with the TDI for dioxins, intake values for each dioxin are multiplied by a factor known as the WHO-TEF. A full list of the WHO-TEF values for each dioxin is provided in Appendix A.

The following table presents the MDI for an adult and child as a proportion of the TDI.

Table 3: Mean Daily Intake of Each Substance as a % of the TDI

Substance Mean Daily Intake, 70 kg adult (µg/kg bw/day)

Mean Daily Intake, 20 kg child (µg/kg bw/day)



Cadmium 53.2% 20.4% 137.7% 52.9%

Chromium 60.5% - 156.6% -

Methyl mercury 3.1% - 8.0% -

Mercuric chloride

0.7% - 1.9% -

Nickel (screening)

68.4% 61.7% 177.1% 159.7%

Nickel (based on monitoring data)

- 31.5% - 81.5%


35.00% 90.65%

The TDI for each pollutant has been set at a level which can be ingested daily over a lifetime without appreciable health risk, and the ID for each pollutant without a toxicity threshold has been set at a level which is associated with a negligible risk to human health. Therefore, if the total exposure is less than the TDI or ID for a pollutant, it can be concluded that the impact of the Facility is negligible and the effect is not significant.

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As shown, the MDI of cadmium, chromium and nickel from existing sources exceeds the TDI for children. The implications of the MDI exceeding the TDI for these pollutants are discussed below.

3.1 Chromium The MDI for chromium is set for chromium III and taken from the DEFRA report “Contaminants in Soil: Collation of Toxicological Data and Intake Values for Humans. Chromium”. This states that there are no published reports on the adverse effects in humans resulting from ingested chromium III. Almost all toxicological opinion is that chromium III compounds are of low oral toxicity, and indeed the UK Committee on Medial Aspects of Food Policy recommends chromium III in the diet. The World Health Organisation (WHO) have reviewed the daily intake of chromium from foods and found that existing levels do not represent a toxicity problem. The WHO conclude that “in the form of trivalent compounds, chromium is an essential nutrient and is relatively non-toxic for man and other mammalian species”.

The DEFRA report explains that the TDI has been derived from the USEPA’s Reference Dose of 3 µg/kg bw/day for chromium VI. This is the only explicitly derived safety limit for oral exposures of chromium. DEFRA recommends that the USEPA Reference Dose is applied to all the chromium content as a starting point. Therefore, the TDI presented in Table 2 is actually the TDI for chromium VI, not total chromium. Assessing the total dietary intake of chromium against this TDI is highly conservative.

3.2 Cadmium The key determinant of cadmium’s toxicity potential is its chronic accumulation in the kidney The Environment Agency in their toxicology report “Contaminants in Soil: Collation of Toxicological Data and Intake Values for Humans. Cadmium” explains that chronic exposure to levels in excess of the TDI might be associated with an increase in kidney disease in a proportion of those exposed, but (small) exceedances lasting for shorter periods are of less consequence. Therefore, assessing a lifetime exposure is appropriate. If we assess the exposure of a receptor over a lifetime (i.e. a period as a child and adult) the lifetime MDI is below the TDI.

3.3 Nickel The MDI and TDI (oral) for nickel have been revised following the publication by the European Food Safety Authority of new expert opinion relating to the reproductive and developmental effects in experimental animals. The MDI exceeds the TDI for children for both inhalation and ingestion. The updated MDI for inhalation is 0.259 µg/day for an adult which, assuming an inhalation rate of 20 m³/day, equates to an atmospheric concentration of 13.0 ng/m³. The background concentration used in the Air Quality Assessment is 6.61 ng/m³, which is the highest annual concentration averaged across all urban background sites across the UK from 2013 to 2017. As such, it is considered that an MDI based on an atmospheric concentration of 13.0 ng/m³ is over-conservative. Therefore, a concentration of 6.61 ng/m³ as used in the Air Quality Assessment has been used as the basis for the MDI for the inhalation of nickel.

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4 Conceptual Site Model

4.1 Conceptual site model A detailed Human Health Risk Assessment has been carried out using the Industrial Risk Assessment Program-Human Health (IRAP-h View – Version 5.0). The programme, created by Lakes Environmental, is based on the United States Environment Protection Agency (USEPA) Human Health Risk Assessment Protocol for Hazardous Waste Combustion Facilities1. This Protocol is a development of the approach defined by Her Majesties Inspectorate on Pollution (HMIP) in the UK in 19962, taking account of further research since that date. The exposure pathways included in the IRAP model are shown in Table 4.

Exposure to gaseous contaminants has the potential to occur by direct inhalation or vapour phase transfer to plants. In addition, exposure to particulate phase contaminants may occur via indirect pathways following the deposition of particles to soil. These pathways include:

• ingestion of soil and dust;

• uptake of contaminants from soil into the food-chain (through home-grown produce and crops); and

• direct deposition of particles onto above ground crops.

The pathways through which inhalation and ingestion occur and the receptors that have been considered to be impacted via each pathway are shown in the table below.

Table 4: Pathways Considered

Pathway Residential Agricultural Direct inhalation Yes Yes

Ingestion of soil Yes Yes

Ingestion of home-grown produce Yes Yes

Ingestion of drinking water Yes Yes

Ingestion of eggs from home-grown chickens - Yes

Ingestion of home-grown poultry - Yes

Ingestion of home-grown beef - Yes

Ingestion of home-grown pork - Yes

Ingestion of home-grown milk - Yes

Ingestion of breast milk (infants only) Infants only

Some households may keep chickens and consume eggs and potentially the birds. The impact on these households is considered to be between the impact at an agricultural receptor and a standard resident receptor. The approach used considers an agricultural receptor at the point of maximum impact as a complete worst case.

As shown in Figure 1, the pathway from the ingestion of mother’s milk in infants is considered within the assessment. This considers all dioxins and dioxin-like PCBs. The IRAP model calculates

1 USEPA (2005) Human Health Risk Assessment Protocol for Hazardous Waste Combustion Facilities. 2 HMIP (1996) Risk Assessment of Dioxin Releases from Municipal Waste Incineration Processes.

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the amount of these COPCs entering the mother’s milk and being passed on to the infants. The impacts are then compared against the TDI.

Figure 1: Conceptual Site Model – Exposure Pathways

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4.2 Pathways excluded from assessment The intake of dioxins via dermal absorption, groundwater and surface water exposure pathways is very limited and as such these pathways are excluded from the HHRA. The justification for excluding these pathways is highlighted in the following sections.

4.2.1 Dermal absorption

Both the HMIP and the USEPA note that the contribution from dermal exposure to soils impacted from thermal treatment facilities is typically a very minor pathway and is typically very small relative to contributions resulting from exposures via the food chain.

The USEPA3 provide an example from the risk assessment conducted for the Waste Technologies, Inc. hazardous thermal treatment in East Liverpool, Ohio. This indicated that for an adult subsidence farmer in a subarea with high exposures, the risk resulting from soil ingestion and dermal contact was 50-fold less than the risk from any other pathway and 300-fold less than the total estimated risk.

The HMIP document4 provides a screening calculation using conservative assumptions, which states that the intake via dermal absorption is 30 times lower than the intake via inhalation, which is itself a minor contributor to the total risk.

As such the pathway from dermal absorption is deemed to be an insignificant risk and has been excluded from this assessment.

4.2.2 Groundwater

Exposure via groundwater can only occur if the groundwater is contaminated and consumed untreated by an individual.

The USEPA5 have concluded that the build-up of dioxins in the aquifer over realistic travel times relevant to human exposure was predicted to be so small as to be essentially zero.

As such the pathway from groundwater is deemed to be an insignificant risk and has been excluded from this assessment.

4.2.3 Surface water

A possible pathway is via deposition of emissions directly onto surface water – i.e. local drinking water supplies or rainwater storage tanks.

Surface water generally goes through several treatment steps and as such any contaminants would be removed from the water before consumption. Run off to rainwater tanks may not go through the same treatment. However, rain water tanks have a very small surface area and as such the potential for deposition and build-up of COPCs is limited. As such, the pathway from contaminated surface water is deemed to be an insignificant risk and has been excluded from this assessment.

3 USEPA (2005) Human Health Risk Assessment Protocol for Hazardous Waste Combustion Facilities. 4 HMIP (1996) Risk Assessment of Dioxin Releases from Municipal Waste Incineration Processes. 5 USEPA (2005) Human Health Risk Assessment Protocol for Hazardous Waste Combustion Facilities.

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4.2.4 Fish consumption

The consumption of locally caught fish has been excluded from the assessment. Whilst fish makes up a proportion of the UK diet, it is not likely that this would be sourced wide-scale from close proximity to the Facility.

A review of the local waterbodies has been undertaken to see if there are any game fishing lakes in the local area6. None have been identified within the modelling domain. The closest game fishing lake is the Halliford Mere Trout Fishery approximately 12.5 km to the south-east of the Facility. Due to the distance from the Facility, emissions from the Facility would not have a significant impact at this location and as such this pathway has been excluded from this assessment.

River fishing may be undertaken in the local area. However, river-caught fish will not be a significant pathway as any small amounts of contaminants would be washed downstream rather than accumulating. Therefore, there is little risk of significant amounts of contaminants from the Proposed Development accumulating in fish in the local area and this pathway has been excluded from this HHRA.

6 Locations Map, http://www.fisharound.net/where-to-fish/locations-map

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5 Sensitive Receptors This assessment considers the possible effects on human health at key receptors, where humans are likely to be exposed to the greatest impact from the Facility, and at the point of maximum impact of annual mean emissions.

For the purposes of this assessment, receptor locations have been categorised as ‘residential’ or ‘agricultural’. Residential receptors represent a known place of residence that is occupied within the study area. Agricultural receptors represent a farm holding or area land of horticultural interest.

The ground-level concentrations resulting from emissions from the Facility are highest only in the locality of the plant. A subset of the specific receptors identified in the Air Quality Assessment have been considered in this Assessment; these are the receptors closest to the Facility which are predicted to experience the highest impact. In addition, a receptor has been assessed at the point of maximum impact. These sensitive receptors are listed in Table 5. Reference should be made to Appendix B which shows the location of these receptors with respect to the Facility.

Table 5: Sensitive Receptors

ID Receptor Name Location Type of Receptor X Y

MAX Point of maximum impact 503640 178340 Agricultural / Residential

R1 Old Slade Lane 1, Richings Park 503732 178404 Residential



R4 Main Drive, Richings Park 503282 179033 Residential

R5 North Park, Richings Park 503018 179083 Residential

R6 Sutton Lane 1, Langley 502272 178911 Residential

R7 Sutton Lane 2, Langley 502424 178468 Agricultural

R8 London Road, Colnbrook 501993 177564 Residential

R9 Vicarage Way, Colnbrook 502680 177297 Residential

R10 The Hawthrorns, Colnbrook 503618 176909 Residential

R11 Colnbrook CoE School 502604 177047 Residential

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6 IRAP Model Assumptions and Inputs The following section details the user defined assumptions used within the IRAP model and provides justifications where appropriate.

6.1 Concentrations in soil The concentration of each chemical in the soil is calculated from the deposition results of the air quality modelling for vapour phase and particle phase deposition. The critical variables in calculating the accumulation of pollutants in the soil are as follows:

• the lifetime of the Facility is taken as 30 years; and

• the soil mixing depth is taken as 2 cm in general and 30 cm for produce.

The split between the solid and vapour phase for the substance considered depends on the specific physical properties of each chemical.

In order to assess the amount of substance which is lost from the soil each year through volatilisation, leaching and surface run-off, a soil loss constant is calculated. The rates for leaching and surface runoff are taken as constant, while the rate for volatilisation is calculated from the physical properties of each substance.

6.2 Concentrations in plants The concentrations in plants are determined by considering direct deposition and air-to-plant transfer for above ground produce, and root uptake for above ground and below ground produce.

The calculation takes account of the different types of plant. For example, uptake of substances through the roots will differ for below ground and above ground vegetables, and deposition onto plants will be more significant for above ground vegetables.

6.3 Concentrations in animals The concentrations in animals are calculated from the concentrations in plants, assumed consumption rates and bio-concentration factors. These vary for different animals and different substances, since the transfer of chemicals between the plants consumed and animal tissue varies.

It is also assumed that 100% of the plant materials eaten by animals is grown on soil contaminated by emission sources. This is likely to be a highly pessimistic assumption for UK farming practice.

6.4 Concentrations in humans

6.4.1 Intake via inhalation

This is calculated from inhalation rates of typical adults and children and atmospheric concentrations. The inhalation rates used for adults and children are:

• adults - 20m³/day; and

• children – 7.2m³/day.

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These are as specified within the Environment Agency series of reports: “Contaminants in soil: updated collation of toxicology data and intake values for humans”. The calculation also takes account of time spent outside, since most people spend most of their time indoors.

6.4.2 Intake via soil ingestion

This calculation allows for the ingestion of soil and takes account of different exposure frequencies. It allows for ingestion of soil attached to unwashed vegetables, unintended ingestion when farming or gardening and, for children, ingestion of soil when playing.

6.4.3 Ingestion of food

The calculation of exposure due to ingestion of food draws on the calculations of concentrations in animals and plants and takes account of different ingestion rates for the various food groups by different age groups.

For most people, locally-produced food is only a fraction of their diet and so exposure factors are applied to allow for this.

6.4.4 Breast milk ingestion

For infants, the primary route of exposure is through breast milk. The calculation draws on the exposure calculation for adults and then allows for the transfer of chemicals in breast milk to an infant who is exclusively breast-fed.

The only pathway considered for dioxins for a breast feeding infant is through breast milk. The modelled scenario consists of the accumulation of pollutants in the food chain up to an adult receptor, the accumulation of pollutants in breast milk and finally the consumption of breast milk by an infant.

The assumptions used were:

• Exposure duration of infant to breast milk 1 year

• Proportion of ingested dioxin that is stored in fat 0.9

• Proportion of mother’s weight that is stored in fat 0.3

• Fraction of fat in breast milk 0.04

• Fraction of ingested contaminant that is absorbed 0.9

• Half-life of dioxins in adults 2,555 days

• Ingestion rate of breast milk 0.688kg/day

6.5 Estimation of COPC concentration in media The IRAP-h model uses a database of physical and chemical parameters to calculate the COPC concentrations through each of the different pathways identified. The base physical and chemical parameters have been used in this assessment.

In order to calculate the COPC concentrations, a number of site specific pieces of information are required.

Weather data was obtained for the period 2014 to 2018 from the London Heathrow weather station, as used within the Air Quality Assessment. This provides the annual average precipitation which can be used to calculate the general IRAP-h input parameters, as presented in Table 6.

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Table 6: Ground Type Dependent Properties

Input Variable Assumption Value (cm/year) Annual average evapotranspiration 70% of annual average precipitation 43.54

Annual average irrigation 0% of annual average precipitation 0.00

Annual average precipitation 100% of annual average precipitation 62.21

Annual average runoff 10% of annual average precipitation 6.22

The average wind speed was taken as 4.14 m/s, calculated from the average of the five years of weather data used in the Air Quality Assessment.

A number of assumptions have been made with regard to the deposition of the different phases. These are summarised in the following table.

Table 7: Deposition Assumptions

Deposition Phase Dry Deposition Velocities (m/s)

Ratio Dry deposition to Wet deposition Dry Deposition Wet Deposition

Vapour 0.005 1.0 2.0

Particle 0.010 1.0 2.0

Bound particle 0.010 1.0 2.0

Mercury vapour 0.029 1.0 0.0

Note: the above deposition velocities have been agreed with the UK Environment Agency for all IRAP based assessments where modelling of specific deposition of pollutants is not undertaken. These are considered to be conservative.

These deposition assumptions have been applied to the annual mean concentrations predicted using the dispersion modelling which was undertaken as part of the Air Quality Assessment, to generate the inputs needed for the IRAP modelling. For details of the dispersion modelling methodology please refer to the Air Quality Assessment.

6.6 Modelled emissions For the purpose of this assessment it is assumed that the Facility operates at the BAT-AELs within the Draft WI BREF for its entire operational life. In reality the Facility will be shut down for periods of maintenance and monitoring of similar facilities in the UK shows that they operate below the emission limits prescribed in their permits.

The following tables present the emissions rates of each COPC modelled and the associated ELVs which have been used to derive the emission rate.

Table 8: COPC Emissions Modelled

COPC Emission Limit Value (mg/Nm³)

Emission rate Units

Benzene 10 1051.0 mg/s

PAHs (Benzo(a)pyrene) 0.00004 4.20 µg/s

Elemental mercury 0.00004 4.20 µg/s

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COPC Emission Limit Value (mg/Nm³)

Emission rate Units

Mercuric chloride 0.024 1.01 mg/s

Cadmium 0.010 1.05 mg/s

Arsenic 0.025 2.63 mg/s

Chromium 0.092 9.67 mg/s

Chromium VI 0.00004 3.68 µg/s

Nickel 0.220 23.12 mg/s

Table 9: COPC Emissions Modelled

COPC Emission Limit Value (ng I-TEQ/Nm³)

Emission rate (ng/s)

2,3,7,8-TCDD

0.06

0.195

1,2,3,7,8-PeCDD 1.545

1,2,3,4,7,8-HxCDD 1.809

1,2,3,6,7,8-HxCDD 1.626

1,2,3,7,8,9-HxCDD 1.292

1,2,3,4,6,7,8-HpCDD 10.742

1,2,3,4,6,7,8,9-OctaCDD 25.481

2,3,7,8-TCDF 1.746

1,2,3,7,8-PCDF 1.746

2,3,4,7,8-PCDF 3.373

1,2,3,4,7,8-HxCDD 13.737

1,2,3,6,7,8-HxCDF 5.087

1,2,3,7,8,9-HxCDF 0.265

2,3,4,6,7,8-HxCDF 5.491

1,2,3,4,6,7,8-HpCDF 27.706

1,2,3,4,7,8,9-HpCDF 2.704

1,2,3,4,6,7,8,9-OctaCDF 22.480

Dioxin like PCBs 0.0092 0.967

A number of points should be noted for each group of COPCs:

1. Benzene (Table 8). a. It has been assumed that the entire TOC emissions consist of only benzene.

b. It has been assumed that TOC emissions are emitted at the daily ELV.

2. PAHs (Table 8). a. It has been assumed that the entire PAH emissions consist of only benzo(a)pyrene.

b. Benzo(a)pyrene is not a regulated pollutant within the IED. The 90th %ile recorded emission concentration of benzo(a)pyrene from the first Draft Waste incineration BREF, published by

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the European IPPC Bureau, was 0.04 ug/Nm³, or 0.00004 mg/Nm³ (dry, 11% oxygen, 273K). This is assumed to be the emission concentration for the Facility.

3. Group 1 metals - mercury and compounds (Table 8). a. It has been assumed that the ELV of total mercury is 0.02 mg/Nm³.

b. The concentration of elemental mercury has been taken as 0.2% of the total mercury and compounds ELV.

c. The concentration of mercury chloride has been taken as 48% of the total mercury and compounds ELV.

d. The losses to the global cycle have been taken as 51.8% of the total mercury and compounds ELV.

4. Group 2 metals – cadmium and compounds (Table 8). a. The assessment is based on the ELV of 0.02 mg/Nm³ for cadmium and compounds.

b. It is assumed that the emissions of cadmium and thallium are each half of the combined ELV.

5. Group 3 metals – arsenic, chromium, and nickel (Table 8).

The emissions of arsenic, total chromium and nickel have been taken as no worse than a currently operating facility as detailed in Table A1 of the Environment Agency “Guidance on assessing group 3 metals stack emissions from incinerators – v4”, which is reproduced in Table 10. This data is based on monitoring at 18 MWI and Waste Wood Co-Incinerators between 2007 and 2015 operating under the IED in the UK. In line with the metals analysis undertaken as part of the Air Quality Assessment, the emission concentration of chromium VI has been assumed to be the average concentration at an existing facility.

6. Dioxins and furans (Table 9).

These are a group of similar halogenated organic compounds, which are generally found as a complex mixture. The toxicity of each compound is different and is generally expressed as a Toxic Equivalent Factor (TEF), which relates the toxicity of each individual compound to the toxicity of 2,3,7,8-TCDD, the most toxic dioxin. A full list of the TEF values for each dioxin is provided in Table 11. The total concentration is then expressed as a Toxic Equivalent (TEQ).

The split of the different dioxins and furans is based on split of congeners for a release of 0.06 ng I-TEQ/Nm³ as presented in Table 11

The split of the different dioxins and furans is based on split of congeners for a release of 1 ng I-TEQ/Nm³ as presented in Table 11. To determine the emission rates, this split of the different dioxins has been multiplied by normalised volumetric flow rate to determine the release rate of each congener. The output of the IRAP model is then multiplied by the relevant TEFs to determine the total intake TEQ for comparison with the TDI.

Dioxin like PCBs (Table 9)

There are a total of 209 PCBs, which act in a similar manner to dioxins, are generally found in complex mixtures and also have TEFs.

The UK Environment Agency has advised that 44 measurements of dioxin like PCBs have been taken at 24 MWIs between 2008 and 2010. The following data summarises the measurements, all at 11% reference oxygen content:

• Maximum = 9.2 x 10-3 ng[TEQ]/m³

• Mean = 2.6 x 10-3 ng[TEQ]/m³

• Minimum = 5.6 x 10-5 ng[TEQ]/m³

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For the purpose of this assessment, as a conservative assumption, the maximum monitored PCB concentration has been used which has been converted to an emission rate using the volumetric flow rate at reference conditions.

The IRAP software, and the HHRAP database which underpins it, does not include any data on individual PCBs, but it does include data for take-up and accumulation rates within the food chain for two groups of PCBs, known as Aroclor 1254 and Aroclor 1016. Each Arocolor is based on a fixed composition of PCBs. Since we are not aware of any data on the specification of PCBs within incinerator emissions, as a worst-case assumption we have assumed that the PCBs are released in each of the two Aroclor compositions.

Table 10: Monitoring Data from Municipal Waste Incinerators

Pollutant Measured Concentration as % of IED Group 3 ELV (i.e. Draft BAT-AEL) Mean Max Min

Arsenic 0.33% 8.33% 0.07%

Chromium 2.80% 30.67% 0.07%

Chromium VI 0.012% 0.043% 0.0008%

Nickel 5.00% 73.33% 0.83%

Note:

The two highest nickel concentrations are outliers being 73%, as above, and 27% of the ELV. The third highest concentration is 0.053 mg/Nm³ or 18% of the ELV.

Table 11: Basis for the Emission Rate of Dioxins and Furans

Dioxin / furan Split of Congeners for a release of 1 ng I-TEQ/Nm³

I-TEFs for the congeners

Emission concentration

(ng/Nm³)


2,3,7,8-TCDD 0.031 1 0.0019 0.195

1,2,3,7,8-PeCDD 0.245 0.5 0.0147 1.545

1,2,3,4,7,8-HxCDD 0.287 0.1 0.0172 1.809

1,2,3,6,7,8-HxCDD 0.258 0.1 0.0155 1.626

1,2,3,7,8,9-HxCDD 0.205 0.1 0.0123 1.292

1,2,3,4,6,7,8-HpCDD 1.704 0.01 0.1022 10.742

1,2,3,4,6,7,8,9-OctaCDD 4.042 0.001 0.2424 25.481

2,3,7,8-TCDF 0.277 0.1 0.0166 1.746

1,2,3,7,8-PCDF 0.277 0.05 0.0166 1.746

2,3,4,7,8-PCDF 0.535 0.5 0.0321 3.373

1,2,3,4,7,8-HxCDD 2.179 0.1 0.1307 13.737

1,2,3,6,7,8-HxCDF 0.807 0.1 0.0484 5.087

1,2,3,7,8,9-HxCDF 0.042 0.1 0.0025 0.265

2,3,4,6,7,8-HxCDF 0.871 0.1 0.0522 5.491

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Dioxin / furan Split of Congeners for a release of 1 ng I-TEQ/Nm³

I-TEFs for the congeners

Emission concentration

(ng/Nm³)


1,2,3,4,6,7,8-HpCDF 4.395 0.01 0.2636 27.706

1,2,3,4,7,8,9-HpCDF 0.429 0.01 0.0257 2.704

1,2,3,4,6,7,8,9-OctaCDF 3.566 0.001 0.2139 22.480

Total (I-TEQ) 20.150 - 1.2086 127.027

Note:

Split of the congeners is taken from Table 7.2a from the HMIP document and factored by the ELV to determine the split for the proposed ELV. This has then been multiplied by the Normalised Volumetric Flow rate to determine the release rate in g/s.

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7 Results

7.1 Assessment against TDI - point of maximum impact The following tables present the impact of emissions from the Facility at the point of maximum impact for an ‘Agricultural’ receptor. As explained in section 3, this receptor type assumes the direct inhalation, and ingestion from soil, drinking water, and home-grown eggs and meat, beef, pork, and milk. This assumes that the person lives at the point of maximum impact and consumes home-grown produce etc. Reference should be made to Appendix B for the location of the point in relation to the Facility.

Where appropriate a comparison has been made to the TDI or ID.

Table 12: Impact Analysis – TDI – Point of Maximum Impact - Adult

Substance MDI (% of TDI) Process Contribution (% of TDI)

Overall (% of TDI)

Inhalation Ingestion Inhalation Ingestion Inhalation Ingestion Agricultural Cadmium 20.41% 53.17% 10.73% 0.30% 31.14% 53.47%

Chromium - 60.48% - 3.10% - 63.57%

Chromium VI - 6.05% - 0.0012% - 6.05%

Methyl mercury - 3.11% - 0.11% - 3.22%

Mercuric chloride

- 0.71% - 0.41% - 1.13%

Mercury 1.19% - 0.0010% - 1.19% -

Nickel 31.48% 68.37% 55.08% 5.72% 86.55% 74.08%


35.00% 19.55% 54.55%

Residential Cadmium 20.41% 53.17% 10.73% 0.19% 31.14% 53.37%

Chromium - 60.48% - 0.25% - 60.72%

Chromium VI - 6.05% - 0.00009% - 6.05%

Methyl mercury - 3.11% - 0.04% - 3.15%

Mercuric chloride

- 0.71% - 0.04% - 0.76%

Mercury 1.19% - 0.0010% - 1.19% -

Nickel 31.48% 68.37% 55.08% 0.53% 86.55% 68.90%


35.00% 0.44% 35.44%

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Table 13: Impact Analysis – TDI – Point of Maximum Impact - Child


Overall (% of TDI)

Inhalation Ingestion Inhalation Ingestion Inhalation Ingestion Agricultural Cadmium 52.86% 137.72% 13.52% 0.69% 66.38% 138.42% Chromium - 156.63% - 4.99% - 161.63% Chromium VI - 15.66% - 0.0019% - 15.67%

Methyl mercury - 8.04% - 0.23% - 8.27%

Mercuric chloride

- 1.85% - 0.65% - 2.50%

Mercury 3.08% - 0.0013% - 3.08% -

Nickel 81.52% 177.07% 69.40% 8.71% 150.92% 185.78% Dioxins and dioxin like PCBs

90.65% 27.63% 118.28%

Residential Cadmium 52.86% 137.72% 13.52% 0.46% 66.38% 138.18% Chromium - 156.63% - 0.69% - 157.32% Chromium VI - 15.66% - 0.00% - 15.66%

Methyl mercury - 8.04% - 0.11% - 8.16%

Mercuric chloride

- 1.85% - 0.18% - 2.03%

Mercury 3.08% - 0.0013% - 3.08% -


90.65% 1.36% 92.01%

The TDI is an estimate of the amount of a contaminant, expressed on a bodyweight basis, which can be ingested daily over a lifetime without appreciable health risk. As shown in Table 12 and Table 13, for the worst-case receptor the overall impact (including the contribution from existing dietary intakes) is less than the TDI for chromium VI and mercury (including compounds). Therefore, there would not be an appreciable health risk based on the emission of these pollutants.

For a child receptor the total ingestion of cadmium, chromium and nickel, total inhalation of nickel, and the total intake of dioxins exceed the TDI. A discussion of the impact from each of these pollutants is provided below.

7.1.1 Cadmium

Total ingestion of cadmium exceeds the TDI for the child receptor. However, this is a reflection of the fact the MDI is over 100% of the TDI. The process contribution is small at only 0.69% of the ingestion TDI for an agricultural child at the point of maximum impact.

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As noted in Section 3.2, the key determinant of cadmium’s toxicity potential is its chronic accumulation in the kidney. The Environment Agency explains that chronic exposure to levels in excess of the TDI might be associated with an increase in kidney disease in a proportion of those exposed, but (small) exceedances lasting for shorter periods are of less consequence. When lifetime exposure is assessed (i.e. a period being a child and an adult) the overall intake is well below the TDI. Therefore, there would not be an appreciable health risk based on the emission of cadmium over a lifetime of an individual.

7.1.2 Chromium

As shown in Table 10, concentrations of total chromium in emissions from municipal waste incineration processes are typically 2.80% of the draft BAT-AEL, with only a fraction of this being in the hexavalent form. Using the worst case assumption that emissions of chromium are the maximum monitored from an existing waste incineration facility (30.67% of the draft BAT-AEL), the process contribution is 4.99% of the TDI for an agricultural child at the point of maximum impact. If emissions are taken to be the average emission concentration shown in Table 10 (2.80% of the draft BAT-AEL), the process contribution is only 0.46% of the TDI.

Almost all toxicological opinion is that chromium III compounds are of low oral toxicity and the WHO state that “in the form of trivalent compounds, chromium is an essential nutrient and is relatively non-toxic for man and other mammalian species”. Although the TDI is predicted to be exceeded, this is due to existing dietary intake.

The TDI is based on the USEPA’s Reference Dose for chromium VI. Assessing the total dietary intake of chromium against this TDI is highly conservative. As the process contribution is small, the existing levels of chromium do not represent a toxicity problem and the TDI is highly conservative, there would not be an appreciable health risk based on the emissions of chromium over the lifetime of an individual.

7.1.3 Nickel

7.1.3.1 Ingestion

The total ingestion of nickel exceeds the TDI for the child receptor. However, this is a reflection of the fact the MDI is over 100% of the TDI. The process contribution is 8.71% of the TDI. This is based on the conservative assumption that the process contribution is based on emissions of nickel at 73.3% of the draft Group 3 metals BAT-AEL. As outlined in Table 10, this is the maximum of the monitoring data and is an outlier. The mean concentration is only 5% of the draft Group 3 metals BAT-AEL. If it is assumed that the Facility operates at 5% of the draft Group 3 metals BAT-AEL, the process contribution would be only 0.59% of the ingestion TDI at the point of maximum impact for the agricultural child receptor. On this basis, it is considered that the Facility would not significantly increase the health risks for children from the ingestion of nickel.

The twelve most recent measurements from the existing facilities have a range of 0.004 to 0.0333 mg/Nm3 and an average of 0.0086 mg/Nm3, or 2.9% of the BAT-AEL. This suggests that the existing facilities operate below the average levels of other UK facilities and supports the use of 5% of the BAT-AEL as a conservative but realistic assumption.

If it is assumed instead that the plant operates at the average monitored level from the existing facilities, which is reasonable as this is a long term health impact and the waste will be the same, the contribution of the Proposed Development would be 0.34% of the TDI, which is not significant.

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7.1.3.2 Inhalation

The total inhalation of nickel exceeds the TDI for the child receptor and the process contribution is 69.4% of the TDI. However, applying the same method as above in which it is assumed that the Facility operates at 5% of the draft Group 3 metals BAT-AEL, the process contribution is 4.7% of the TDI and the total inhalation is 86.3% of the TDI. As the total inhalation does not exceed the TDI, it is not considered that the Facility would not significantly increase the health risks for children from the inhalation of nickel.

7.1.4 Dioxins

The total ingestion and inhalation of dioxins exceeds the TDI for an agricultural child at the point of maximum impact. However, the predicted impact is based on the child receptor being exposed to the maximum airborne concentrations and consuming produce, eggs, meat and milk grown at the point of maximum impact. As this is unrealistic, the impact at the maximum impacted receptor has been considered further in Section 7.4.

In addition, when lifetime exposure is assessed (i.e. a period being a child and an adult) the overall impact is well below the TDI. Therefore, there would not be an appreciable health risk based on the emissions of dioxins over a lifetime of an individual.

7.2 Breast milk exposure The total accumulation of dioxins in an infant, considering the breast milk pathway and based on an adult agricultural receptor at the point of maximum impact feeding an infant, is 3.034 pg WHO-TEQ / kg-bw / day which is 151.7% of the TDI. For a residential type receptor this is only 0.056 pg WHO-TEQ / kg-bw / day which is 2.8% of the TDI. There are no ingestion pathways besides breast milk ingestion for an infant receptor.

The process contribution for the hypothetical maximum impacted receptor (an agricultural receptor at the point of maximum impact) exceeds the TDI. However, this receptor does not exist in reality. The impact at the maximum impacted receptor is considered in Section 7.4.

7.3 Assessment against ID - point of maximum impact Table 14 and Table 15 outline the impact of emissions from the Facility for an ‘agricultural’ and a ‘residential’ receptor located at the point of maximum impact as a percentage of the ID.

Table 14: Impact Analysis – ID – Point of Maximum Impact - Adult

Substance Inhalation (% of ID) Ingestion (% of ID) Agricultural Arsenic 18.78% 1.52%

Benzene 10.73% 2.47%

Benzo[a]pyrene 0.86% 1.80%

Chromium 138.19% -

Residential Arsenic 18.78% 0.56%

Benzene 10.73% 2.62%


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Substance Inhalation (% of ID) Ingestion (% of ID) Chromium 138.19% -

Table 15: Impact Analysis – ID – Point of Maximum Impact - Child

Substance Inhalation (% of ID) Ingestion (% of ID) Agricultural Arsenic 23.66% 2.65%

Benzene 13.52% 5.80%


Chromium 174.12% -

Residential Arsenic 23.66% 1.35%

Benzene 13.52% 4.65%


Chromium 174.12% -

The ID is the level of exposure which is associated with a negligible risk to human health. As shown, for this worst-case receptor the process contribution is well below the ID for all pollutants except chromium. However, this is based on the worst case assumption that emissions of chromium are the maximum monitored from an existing waste incineration facility (30.67% of the draft BAT-AEL). If emissions are taken to be the average emission concentration shown in Table 10 (2.80% of the draft BAT-AEL), the process contribution is only 12.6% of the ID for an adult receptor and 15.9% of the ID for a child receptor. Under this assumption the process contribution is well below the ID, so emissions from the Facility are considered to have a negligible impact on human health.

7.4 Maximum impact at a receptor The following tables outline the impact of emissions from the Facility at the most affected receptors for inhalation and ingestion of emissions. The receptor with the greatest impact from inhalation is R1 - Old Slade Lane 1, Richings Park and the receptor with the greatest impact from ingestion is R7 – Sutton Lane 2, Langley, which is an agricultural receptor. Where appropriate a comparison has been made to the TDI or ID.

Table 16: Impact Analysis – TDI –Maximum Impacted Receptor


Overall (% of TDI)

Inhalation Ingestion Inhalation Ingestion Inhalation Ingestion Adult Cadmium 20.41% 53.17% 8.85% 0.16% 29.26% 53.33%

Chromium - 60.48% - 0.204% - 60.68%

Chromium VI - 6.05% - 0.0001% - 6.05%

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Overall (% of TDI)

Inhalation Ingestion Inhalation Ingestion Inhalation Ingestion Methyl mercury - 3.11% - 0.035% - 3.14%

Mercuric chloride

- 0.71% - 0.037% - 0.75%

Mercury 1.19% - 0.0008% - 1.19% -

Nickel 31.48% 68.37% 45.44% 0.44% 76.92% 68.80%


35.00% 1.07% 36.07%

Child Cadmium 52.86% 137.72% 11.15% 0.38% 64.01% 138.10% Chromium - 156.63% - 0.57% - 157.20% Chromium VI - 15.66% - 0.0002% - 15.66%

Methyl mercury - 8.04% - 0.09% - 8.14%

Mercuric chloride

- 1.85% - 0.15% - 2.00%

Mercury 3.08% - 0.0010% - 3.08% -


90.65% 1.52% 92.17%

As shown, for the most impacted receptor the overall impact (including the contribution from existing dietary intakes) is less than the TDI for chromium VI, mercury (including compounds) and dioxins. Therefore, there would not be an appreciable health risk based on the emission of these pollutants.

For a child receptor the total ingestion of cadmium, chromium and nickel and the total inhalation of nickel exceed the TDI. However, the process contribution for ingestion is small (a maximum of 1.05% of the TDI for nickel) and the exceedance is a reflection of the fact the MDI is over 100% of the TDI. On this basis, it is considered that the Facility would not lead to a significant increase in health risks from the ingestion of cadmium, chromium or nickel for children.

The inhalation of nickel is based on the conservative assumption that the process contribution is based on emissions of nickel at 73.3% of the draft Group 3 metals BAT-AEL. As outlined in Table 10, this is the maximum of the monitoring data and is an outlier. If it is assumed that the Facility operates at the average concentration monitored – i.e. 5% of the draft Group 3 metals BAT-AEL - the process contribution would be only 3.9% of the TDI and the total intake would be 85.4% of the TDI. As the total inhalation does not exceed the TDI, it is considered that the Facility would not significantly increase the health risks for children from the inhalation of nickel.

The total accumulation of dioxins in an infant, considering the breast milk pathway and based on the adult residential receptor at R7 feeding an infant, is 0.167 pg WHO-TEQ / kg bw / day which is 8.33% of the TDI. As the process contribution is less than the TDI, it is considered that the Facility will not increase the health risks from the accumulation of dioxins in infants significantly.

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Table 17: Impact Analysis – ID – Maximum Impacted Receptor

Substance Inhalation (% of ID) Ingestion (% of ID) Adult – Agricultural Arsenic 15.49% 0.46%

Benzene 8.85% 2.16%


Chromium 114.02% -

Child – Agricultural Arsenic 19.52% 1.11%

Benzene 11.15% 3.83%


Chromium 143.66% -

As shown, for the maximum impacted receptor the process contribution is well below the ID for all pollutants considered, except chromium. However, this is based on the worst case assumption that emissions of chromium are the maximum monitored from an existing waste incineration facility (30.67% of the draft BAT-AEL). If emissions are taken to be the average emission concentration shown in Table 10 (2.80% of the draft BAT-AEL), the process contribution is only 10.4% of the ID for an adult receptor and 13.1% of the ID for a child receptor. Under this assumption the process contribution is well below the ID, so emissions from the Facility are considered to have a negligible impact on human health.

7.5 Uncertainty and sensitivity analysis To account for uncertainty in the modelling the impact on human health was assessed for a receptor at the point of maximum impact.

To account for uncertainty in the dietary intake of a person, both residential and agricultural receptors have been assessed. The agricultural receptor is assumed to consume a greater proportion of home grown produce, which has the potential to be contaminated by the COPCs released, than for a residential receptor. In addition, the agricultural receptor includes the pathway from consuming animals grazed on land contaminated by the emission source. This assumes that 100% of the plant materials eaten by the animals is grown on soil contaminated by emission sources.

The agricultural receptor at the point of maximum impact is considered the upper maximum of the impact of the Facility.

7.6 Upset process conditions Article 46(6) of the IED (Directive 2010/75/EU) states that:

“… the waste incineration plant … shall under no circumstances continue to incinerate waste for a period of more than 4 hours uninterrupted where emission limit values are exceeded.

The cumulative duration or operation in such conditions over 1 year shall not exceed 60 hours.”

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Article 47 continues with:

“In the case of a breakdown, the operator shall reduce or close down operations as soon as practicable until normal operations can be restored.”

In addition Annex VI, Part 3, 2 of the IED states the emission limit values applicable in the circumstances described in Article 46(6) and Article 47:

“The total dust concentration in the emissions into the air of a waste incineration plant shall under no circumstances exceed 150 mg/Nm³ expressed as a half-hourly average. The air emission limit values for TOC and CO set out in points 1.2 and 1.5(b) shall not be exceeded.”

The conditions detailed in Article 46(6) are considered to be “Upset Operating Conditions”. As identified these periods are short term events which can only occur for a maximum of 60 hours per year.

Start-up of the Facility from cold will be conducted with clean support fuel (low sulphur light fuel oil). During start-up waste will not be introduced onto the grate unless the temperature within the oxidation zone is above the 850ºC as required by Article 50, paragraph 4(a) of the IED. During start-up, the flue gas treatment plant will be operational as will be the combustion control systems and emissions monitoring equipment.

The same is true during plant shutdown where waste will cease to be introduced to the grate. The waste remaining on the grate will be combusted, the temperature not being permitted to drop below 850ºC through the combustion of clean support auxiliary fuel. During this period the flue gas treatment equipment is fully operational, as will be the control systems and monitoring equipment. After complete combustion of the waste, the auxiliary burners will be turned off and the plant will be allowed to cool.

Start-up and shutdown are infrequent events. The Facility is designed to operate continuously, and ideally only shutdown for its annual maintenance programme.

In relation to the magnitude of dioxin emissions during plant start-up and shutdown, research has been undertaken by AEA Technology on behalf of the Environment Agency7. Whilst elevated emissions of dioxins (within one order of magnitude) were found during shutdown and start-up phases where the fuel was not fully established in the combustion chamber, the report concluded that:

“The mass of dioxin emitted during start-up and shutdown for a 4-5 day planned outage was similar to the emission which would have occurred during normal operation in the same period. The emission during the shutdown and restart is equivalent to less than 1 % of the estimated annual emission (if operating normally all year).”

There is therefore no reason why such start-up and shutdown operations or upset operating conditions will affect the long term impact of the Facility.

7 AEA Technology (2012) Review of research into health effects of Energy from Waste facilities.

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8 Conclusions This HHRA has been undertaken based on the following conservative assumptions:

• the Facility will operate continually at the draft BAT-AELs, i.e. at the maximum concentrations which it is expected that the Facility will be permitted to operate at; where this assumption results in unrealistic impacts, further analysis has been undertaken.

• exposure to emissions is based on lifetime exposure assuming continual operation of the Facility, when in reality the Facility will have an operational lifetime of approximately 30 years; and

• the hypothetical maximum impacted receptor (an agricultural receptor at the point of maximum impact) only ingests food and drink sourced from the area with the maximum contribution from the Facility.

The results of the assessment show that, for an agricultural child receptor at the point of maximum impact, the total ingestion of cadmium, chromium and nickel, total inhalation of nickel, and the total intake of dioxins exceed the TDI. In addition, the intake of dioxins exceeds the TDI for an agricultural infant receptor at the point of maximum impact, and the inhalation of chromium is predicted to exceed the ID for a child and adult receptor at the point of maximum impact.

Further analysis of the impact of these pollutants has been undertaken, with the following conclusions:

1. For the ingestion of cadmium and chromium, when lifetime exposure is assessed (i.e. a period being a child and an adult) the overall intake is well below the TDI. Therefore, there would not be an appreciable health risk over a lifetime of an individual.

2. For nickel, if it is assumed that emissions from the Facility are as the average from the available monitoring data, the process contribution for ingestion is small at 0.59% of the TDI, and total inhalation is below the TDI. Therefore, it is considered that the Facility would not significantly increase the health risks for children from the ingestion or inhalation of nickel.

3. For the total intake of dioxins, the predicted impact is based on the child receptor being exposed to the maximum airborne concentrations and consuming produce, eggs, meat and milk grown at the point of maximum impact. In reality, there is no agricultural interest at the point of maximum impact, so the impact at the maximum impacted receptor has been assessed. This shows that the total intake of dioxins is below the TDI and the Facility would not significantly increase the health risks from the intake of dioxins.

4. Similarly, for the intake of dioxins by an infant, the impact at the maximum impacted receptor has been assessed. This shows that the process contribution is less than the TDI, so it is considered that the Facility will not increase the health risks from the accumulation of dioxins in infants significantly.

5. For the inhalation of chromium, the process contribution exceeds the ID if it is assumed that emissions are as the maximum monitored from a waste incineration facility. If emissions are taken to be the average monitored emission concentration the process contribution is well below the ID for adult and child receptors, so emissions from the Facility are considered to have a negligible impact on human health.

For all other pollutants, the combined impact from the Facility plus the existing MDI is below the TDI, and the impact of the Facility is below the ID, so there would not be an appreciable health risk based on the emission of these pollutants.

In conclusion, the operation of the Facility will not result in appreciable health risks.

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Appendices

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A Detailed Results Tables

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Table 18: Comparison with ID Limits for Adult Receptors

Receptor Ingestion (% of ID) Inhalation (% of ID) Arsenic(1) Benzene Benzo(a)pyrene Arsenic(1) Benzene Benzo(a)pyrene Chromium(1)

Point of maximum impact - agricultural

1.516% 2.468% 1.800% 18.776% 10.729% 0.858% 138.191%

Point of maximum impact - residential

0.562% 2.619% 0.017% 18.776% 10.729% 0.858% 138.191%

R1 0.463% 2.160% 0.014% 15.491% 8.852% 0.708% 114.017% R2 0.233% 1.086% 0.007% 7.789% 4.451% 0.356% 57.326%

R3 0.162% 0.755% 0.005% 5.413% 3.093% 0.247% 39.837%

R4 0.102% 0.475% 0.003% 3.407% 1.947% 0.156% 25.077%

R5 0.068% 0.318% 0.002% 2.281% 1.303% 0.104% 16.786%

R6 0.029% 0.136% 0.001% 0.975% 0.557% 0.045% 7.175%

R7 0.083% 0.135% 0.099% 1.031% 0.589% 0.047% 7.589%

R8 0.031% 0.144% 0.001% 1.032% 0.590% 0.047% 7.595%

R9 0.068% 0.318% 0.002% 2.278% 1.302% 0.104% 16.767%

R10 0.026% 0.119% 0.001% 0.856% 0.489% 0.039% 6.302%

R11 0.056% 0.263% 0.002% 1.886% 1.078% 0.086% 13.880%

Note:

(1) Assumes emissions at the maximum monitored concentrations shown in Table 10.

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Table 19: Comparison with ID Limits for Child Receptors

Receptor Ingestion (% of ID) Inhalation (% of ID) Arsenic(1) Benzene Benzo(a)pyrene Arsenic(1) Benzene Benzo(a)pyrene Chromium(1)


2.652% 5.797% 2.600% 23.657% 13.519% 1.081% 174.121%


1.352% 4.646% 0.045% 23.657% 13.519% 1.081% 174.121%

R1 1.115% 3.832% 0.037% 19.519% 11.154% 0.892% 143.662% R2 0.561% 1.927% 0.019% 9.814% 5.608% 0.449% 72.230%

R3 0.390% 1.339% 0.013% 6.820% 3.897% 0.312% 50.195%

R4 0.245% 0.843% 0.008% 4.293% 2.453% 0.196% 31.597%

R5 0.164% 0.564% 0.005% 2.874% 1.642% 0.131% 21.151%

R6 0.070% 0.241% 0.002% 1.228% 0.702% 0.056% 9.040%

R7 0.146% 0.318% 0.143% 1.299% 0.742% 0.059% 9.562%

R8 0.074% 0.255% 0.002% 1.300% 0.743% 0.059% 9.570%

R9 0.164% 0.564% 0.005% 2.870% 1.640% 0.131% 21.126%

R10 0.062% 0.212% 0.002% 1.079% 0.616% 0.049% 7.940%

R11 0.136% 0.466% 0.005% 2.376% 1.358% 0.109% 17.489%

Note:


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Table 20: Comparison with TDI Limits for Adult Receptors

Receptor Ingestion (% of ID) Inhalation (% of ID) Cadmium Chromium(1) Chromium

VI(1) Methyl

Mercury Mercuric Chloride

Nickel(1) Cadmium Mercury Nickel(1)

MDI of TDI (%) 53.17% 60.48% 6.05% 3.11% 0.71% 68.37% 20.41% 1.19% 31.48%


53.471% 63.573% 6.0488% 3.218% 1.128% 74.083% 31.137% 1.191% 86.552%


53.366% 60.724% 6.0477% 3.148% 0.759% 68.897% 31.137% 1.191% 86.552%

R1 53.333% 60.680% 6.0477% 3.141% 0.751% 68.804% 29.260% 1.191% 76.918%

R2 53.254% 60.579% 6.0477% 3.123% 0.733% 68.587% 24.859% 1.191% 54.324%

R3 53.230% 60.547% 6.0476% 3.118% 0.727% 68.520% 23.501% 1.191% 47.354%

R4 53.209% 60.521% 6.0476% 3.113% 0.722% 68.463% 22.355% 1.191% 41.471%

R5 53.198% 60.506% 6.0476% 3.111% 0.720% 68.432% 21.711% 1.191% 38.166%

R6 53.185% 60.489% 6.0476% 3.108% 0.717% 68.395% 20.965% 1.191% 34.336%

R7 53.191% 60.646% 6.0477% 3.112% 0.737% 68.681% 20.997% 1.191% 34.501%

R8 53.185% 60.490% 6.0476% 3.108% 0.717% 68.396% 20.998% 1.191% 34.503%

R9 53.198% 60.506% 6.0476% 3.111% 0.720% 68.432% 21.710% 1.191% 38.159%

R10 53.183% 60.487% 6.0476% 3.108% 0.716% 68.391% 20.897% 1.191% 33.988%

R11 53.194% 60.501% 6.0476% 3.110% 0.719% 68.420% 21.486% 1.191% 37.008%

Note:


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Table 21: Comparison with TDI Limits for Child Receptors

Receptor Ingestion (% of ID) Inhalation (% of ID) Cadmium Chromium(1) Chromium

VI(1) Methyl

Mercury Mercuric Chloride

Nickel Cadmium Mercury Nickel(1)

MDI of TDI (%) 137.72% 156.63% 15.66% 8.04% 1.85% 177.07% 52.86% 3.08% 81.52%


138.416% 161.626% 15.665% 8.273% 2.496% 185.785% 66.376% 3.085% 150.919%


138.184% 157.319% 15.664% 8.158% 2.029% 178.345% 66.376% 3.085% 150.919%

R1 138.103% 157.199% 15.664% 8.138% 1.997% 178.122% 64.011% 3.084% 138.780% R2 137.914% 156.918% 15.663% 8.091% 1.924% 177.600% 58.465% 3.084% 110.311% R3 137.855% 156.831% 15.663% 8.077% 1.901% 177.438% 56.754% 3.084% 101.529% R4 137.806% 156.758% 15.663% 8.064% 1.882% 177.303% 55.310% 3.084% 94.117%

R5 137.778% 156.717% 15.663% 8.057% 1.872% 177.226% 54.499% 3.083% 89.953%

R6 137.746% 156.669% 15.663% 8.049% 1.859% 177.138% 53.559% 3.083% 85.126%

R7 137.760% 156.907% 15.663% 8.056% 1.885% 177.550% 53.600% 3.083% 85.334%

R8 137.748% 156.671% 15.663% 8.050% 1.860% 177.141% 53.600% 3.083% 85.337%

R9 137.778% 156.717% 15.663% 8.057% 1.872% 177.226% 54.497% 3.083% 89.943%

R10 137.743% 156.665% 15.663% 8.049% 1.858% 177.129% 53.474% 3.083% 84.688%

R11 137.769% 156.702% 15.663% 8.055% 1.868% 177.199% 54.215% 3.083% 88.494%

Note:


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Table 22: Comparison with Total Dioxin TDI Limits for Adult Receptors

Receptor Total Inhalation, (pg WHO-TEQ kg-1 bw day -1)

Total Ingestion, (pg WHO-TEQ kg-1 bw day -1)

Total uptake, (pg WHO-TEQ kg-1 bw day -1)

Comparison (% of limit)

MDI (% of TDI) 35.00% Point of maximum impact - agricultural

1.05E-03 3.90E-01 3.91E-01 54.551%


1.05E-03 7.71E-03 8.77E-03 35.438%

R1 8.68E-04 6.36E-03 7.23E-03 35.362%

R2 4.37E-04 3.20E-03 3.64E-03 35.182%

R3 3.03E-04 2.22E-03 2.53E-03 35.126%

R4 1.91E-04 1.40E-03 1.59E-03 35.080%

R5 1.28E-04 9.37E-04 1.06E-03 35.053%

R6 5.46E-05 4.00E-04 4.55E-04 35.023%

R7 5.78E-05 2.14E-02 2.15E-02 36.074%

R8 5.78E-05 4.24E-04 4.82E-04 35.024%

R9 1.28E-04 9.36E-04 1.06E-03 35.053%

R10 4.80E-05 3.52E-04 4.00E-04 35.020%

R11 1.06E-04 7.75E-04 8.80E-04 35.044%

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Table 23: Comparison with Total Dioxin TDI Limits for Child Receptors

Receptor Total Inhalation, (pg WHO-TEQ kg-1 bw day -1)

Total Ingestion, (pg WHO-TEQ kg-1 bw day -1)

Total uptake, (pg WHO-TEQ kg-1 bw day -1)

Comparison (% of limit)

MDI (% of TDI) 90.65% Point of maximum impact - agricultural

1.33E-03 5.51E-01 5.53E-01 118.285%


1.33E-03 2.59E-02 2.73E-02 92.013%

R1 1.09E-03 2.14E-02 2.25E-02 91.774%

R2 5.50E-04 1.08E-02 1.13E-02 91.215%

R3 3.82E-04 7.47E-03 7.85E-03 91.043%

R4 2.41E-04 4.70E-03 4.94E-03 90.897%

R5 1.61E-04 3.15E-03 3.31E-03 90.815%

R6 6.88E-05 1.35E-03 1.41E-03 90.721%

R7 7.28E-05 3.03E-02 3.03E-02 92.167%

R8 7.29E-05 1.42E-03 1.50E-03 90.725%

R9 1.61E-04 3.15E-03 3.31E-03 90.815%

R10 6.05E-05 1.18E-03 1.24E-03 90.712%

R11 1.33E-04 2.60E-03 2.74E-03 90.787%

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B Location of Sensitive Receptors Figure 2: Location of Sensitive Receptors

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Kingsgate (Floor 3), Wellington Road North, Stockport, Cheshire, SK4 1LW,

United Kingdom

t: +44 (0)161 476 0032 f: +44 (0)161 474 0618

www.fichtner.co.uk



29

Appendix 4 Amended Technical Appendix J0 Ecological Impact Assessment

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June 2019

Contents

J. Biodiversity J-5 J.5 Overall Baseline J-12

Current Baseline J-12 Ecological Features J-16 Spatial Scope J-17 Temporal Scope J-20 Introduction J-20

J.10 Assessment of Effects: Broadleaved woodland (on site) J-23 Baseline Conditions J-23 Current Baseline J-23 Predicted Effects and their Significance J-23 Summary of effects on broadleaved woodland (on site) J-23

J.11 Assessment of Effects: Invertebrates J-23 Baseline Conditions J-23 Current Baseline J-23 Predicted Effects and their Significance J-24 Summary of effects on invertebrates J-24

J.12 Assessment of Effects: Breeding birds J-24 Current Baseline J-24 Predicted Effects and their Significance J-25 Summary of effects on breeding birds J-25

J.13 Assessment of Effects: Bats J-25 Baseline Conditions J-25 Current Baseline J-25 Predicted Effects and their Significance J-26 Summary of effects on bats J-27

J.14 Assessment of Effects: Otters J-27 Baseline Conditions J-27 Predicted Effects and their Significance J-27 Summary of effects on otters J-28

J.15 Assessment Summary J-28 Cemex Langley site J-30 Cemex Datchett Quarry site J-30 Thorney Mill Road/Link Park Heathrow J-30 M4 Smart Motorway J-30

J.20 References J-32

Table J.1 National Planning Policy Issues Considered within the Assessment of Biodiversity J-6 Table J.2 Development Plan Policy Issues Considered within the Assessment of Biodiversity J-6 Table J.3 Information Relevant to the Desk Study J-8 Table J.4 Sources of Desk Study Data J-9 Table J.5 Summary of Ecological Surveys J-10 Table J.6 Importance of the Proposed Development for Ecological Features J-16 Table J.7 Likely Effects, ZoIs and Justification for Scoped in Ecological Features J-19 Table J.8 Summary of the Embedded Environmental Measures and how these Influence the Biodiversity Assessment

J-20 Table J.9 Guidelines for the Assessment of the Scale of Magnitude J-22 Table J.10 Summary of Significance of Adverse Effects J-29 Table J.11 Summary of Environmental Measures Relevant to Biodiversity J-32

Figure J.1 Study Area

Figure J.2 Statutory Nature Conservation Sites

Appendix J.1 Baseline Report – Extended Phase 1 Habitat Survey Appendix J.2 Baseline Report – National Vegetation Classification (NVC) Survey Appendix J.3 Baseline Report – Invertebrate Survey Appendix J.4 Baseline Report – Great Crested Newt Survey

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Appendix J.5 Baseline Report – Reptile Survey Appendix J.6 Baseline Report – Ornithological Survey Appendix J.7 CONFIDENTIAL Baseline Report – Badger Survey Appendix J.8 Baseline Report – Bat Survey Appendix J.9 Baseline Report – Otter Survey Appendix J.10 Scoping of the Assessment - Summary Appendix J.11 Assessment of Effects – Summary Tables

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Extended Phase 1 Habitat Survey¶Appendix J.2➝ Baseline Report – National

Vegetation Classification (NVC) Survey¶Appendix J.3➝ Baseline Report –

Invertebrate Survey¶Appendix J.4➝ Baseline Report – Great

Crested Newt Survey¶Appendix J.5➝ Baseline Report – Reptile

Survey¶Appendix J.6➝ Baseline Report –

Ornithological Survey¶Appendix J.7➝CONFIDENTIAL Baseline

Report – Badger Survey¶Appendix J.8➝ Baseline Report – Bat

Survey¶Appendix J.9➝ Scoping of the Assessment -

Summary¶Appendix J.10➝ Assessment of Effects –

Summary Tables¶


June 2019

J. Biodiversity

J.1 Introduction

J.1.1 This ecological impact assessment (EcIA) assesses the likely significant effects1 of the Proposed

Development with respect to biodiversity, including terrestrial ecology and ornithology. The EcIA

should be read in conjunction with the development description provided in Chapter 3 and with

respect to relevant parts of chapters or technical reports on Air Quality, Noise and vibration,

Drainage and Landscape, townscape and visual effects, where common receptors have been

considered and where there is an overlap or relationship between the assessments of effects. In

this EcIA, receptors are referred to as ecological features, to accord with the Chartered Institute of

Ecology and Environmental Management (CIEEM 2018) “Guidelines for Ecological Impact Assessment in the UK and Ireland: Terrestrial, Freshwater, Coastal and Marine”. The term

ecological feature is defined in the guidance as pertaining to habitats, species and ecosystems.

J.1.2 Potential effects on European sites2 are considered with regard to the Conservation of Habitats and

Species Regulations 2017 within the Habitats Regulations Assessment (HRA). A Shadow Habitat

Regulations screening report is provided as a technical appendix to the Environmental Statement.

J.2 Limitations of this Assessment

J.2.1 Field surveys predominantly followed the survey guidance that is widely recognised by the relevant

statutory nature conservation body Natural England. However, where deviations occurred due to

issues including adverse weather, health and safety concerns and problems with land access,

these are described in the accompanying survey reports (Appendix J.1-J.8).

J.2.2 Access was not always possible for the survey work within the red line boundary. This is detailed

in the relevant appendices (Appendices J.1-J.8). Where access was not possible the site was

either viewed from adjacent accessible land or results were extrapolated from nearby similar

habitats.

J.2.3 However, it is considered that the issues encountered have not affected the robustness of the

survey data collected or the assessment of likely significant effects resulting from the Proposed

Development.

J.3 Relevant Legislation, Planning Policy, Technical Guidance

Legislative Context

J.3.1 The following legislation has been considered in the assessment of the effects on ecological

features3:

l The Conservation of Habitats and Species Regulations 2017 (the Habitats Regulations);

l Natural Environment and Rural Communities Act 2006 (NERC Act);

1 In the EcIA, the term “potentially significant effects” is used in the sections prior to the “scope of the assessment”

(Section J.7) being determined, as it accords with CIEEM guidance. The term “likely significant effects” is used once the

scope of the assessment has been determined. The use of this term is not to be confused with Likely Significant Effects

(LSEs) as used in the context of the Habitats Regulations Assessment. 2 European sites include Special Protection Areas (SPA), Special Areas of Conservation (SAC), candidate SACs (cSAC)

and Sites of Community Importance (SCI); these sites are collectively referred to as Natura 2000 sites. Potential SPAs

(pSPA), possible SACs (pSACs), Ramsar sites and proposed Ramsar sites should also be considered in the same

manner in accordance with national planning policy. 3 The Chartered Institute for Ecology and Environmental Management (CIEEM) refer to biodiversity receptors within

technical guidance (see paragraph J.3.5) as ecological features.


June 2019

l The Hedgerows Regulations 1997;

l Protection of Badgers Act 1992;

l The Countryside and Rights of Way Act 2000; and

l Wildlife and Countryside Act 1981 (as amended) (WCA).

Planning Policy Context

National Policies

J.3.2 A summary of the relevant national planning policies is given in Table J.1.

Table J.1 National Planning Policy Issues Considered within the Assessment of Biodiversity

Policy reference Policy issue Considered in Section

National planning policies

National Planning Policy Framework (NPPF)

Section 15 of the NPPF requires planning policies and decisions to

contribute to the protection and enhancement of biodiversity sites

commensurate with their status and hierarchy, to provide benefit from

natural capital and ecosystem services and to minimise impacts on, and

provide net gain for, biodiversity (para 170).

Plans should protect and enhance local and wider biodiversity interest,

including corridors and stepping stones, designated sites, as well as

biodiversity potential identified by local and national partnerships. Policies

should promote opportunities for conservation, restoration and

enhancement including priority habitats and species, as well as securable

net gain (para 174 & 175). If significant harm to biodiversity will result,

permission will be refused unless the benefits of development outweigh

impacts, or exceptional reasons and compensation apply (para 175),

Potential, possible, listed or proposed sites, and those that are an

identified compensatory measure, are to be protected as the equivalent

designation (para 176). Potential impacts on sites requiring appropriate

assessment will be considered ahead of the presumption for sustainable

development.

J.10-J.14

Development Plan Policies

J.3.3 A summary of the relevant development plan policies is given in Table J.2.

Table J.2 Development Plan Policy Issues Considered within the Assessment of Biodiversity


Development plan policies

Slough Local Development Framework Core Strategy

Development Plan Document (DPD) 2006-2026 Core

Policy 9 (Natural and Built Environment).

This policy outlines protection and improvement of water

bodies and their margins, as well as natural habitats in

general. It also refers to the protection and

enhancement of biodiversity corridors between important

features

J.10-J.14

Slough Local Development Framework Site Allocations

DPD Site Reference SSA25

The Site Allocation provides the Slough Borough Council

(BC) approach to planning requirements for the site.

These are to enhance and/or create new habitat along

with managing public access for the benefit of the site’s

wildlife.

J.8

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The Local Plan for Slough (saved policies) Policy EN22 Slough BC have identified Wildlife Heritage Sites and

potential Wildlife Heritage Sites, within which

development may be permitted, but where nature

conservation is very important in the decision making

process. Any impacts on nature conservation interest will require measures to avoid habitat loss.

J.12 and

J.13

The Local Plan for Slough (saved policies) Policy EN23 Opportunities will be taken to not only protect the sites

identified as Wildlife Heritage Sites but, in some cases,

create new habitat and enhance the sites overall.

J.12 and

J.13

Technical Guidance

J.3.4 Publications that provide guidance that is relevant to the assessment of potentially significant

effects on biodiversity are listed below.

l Chartered Institute of Ecology and Environmental Management (CIEEM 2018). Guidelines for

Ecological Impact Assessment in the UK and Ireland: Terrestrial, Freshwater, Coastal and

Marine;

l Biodiversity: Code of practice for planning and development published by the British Standards

Institution (BS 42020:2013);

J.3.5 Technical guidance that has been used to define the survey methods used to inform this

assessment is referenced in Section J.4 and in Appendices J.1-J.8.

J.4 Data Gathering Methodology

Study Area(s)

J.4.1 The study area encompasses the area over which all desk-based and field data was gathered to

inform the assessment presented in this EcIA. Due to the presence of multiple ecological features

and many potential effects, the level and type of data collection varies across the study area. The

“study area” comprises:

l The Proposed Development (the initially anticipated developable area produced early in the

design process);

l The desk study area for European sites;

l The desk study area for legally protected and notable ecological features; and

l The field survey areas.

J.4.2 The extent of the desk study areas and field survey areas (see Table J.3) were determined based

on best practice guidance and a high-level overview of the types of ecological features present,

and the potential effects that could occur (see Figures J.1 and J.2 for the study area). The study

area was defined on a precautionary basis to ensure that, as a minimum, the ZoI relevant to all

ecological features (see Table J.6 and Section J.7) were covered during baseline data collection

activities.

J.4.3 As the design process has evolved iteratively, the study area, and its constituent parts, has been

regularly reviewed to ensure that its extent was adequate to enable the assessment of all

potentially significant effects of the ecological features identified. Changes to the initial developable

area, or the precise nature of the development, have been reviewed in light of the ecological

features present (which was in turn informed by the data gathering exercise) and the potential

effects that could occur. These ecological features and respective study area(s) are defined in the

following paragraphs and are shown on Figure J.1 and J.2 and Appendices J.1-J.8.

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J.4.4 At each stage of design evolution, the extent of the study area, including all of its components, was

tested using the methodology described in Section J.7 to ensure adequate information was

available on which to base an assessment. The assessment of impacts on bats at the scoping

stage noted that the construction compound and access road were located close to an important

foraging and commuting area. These areas (the compound and road) have been moved away

from the important bat areas to reduce the impact on this ecological feature.

Desk Study

J.4.5 A desk-based data-gathering exercise was undertaken to obtain existing information relating to

relevant ecological features; these are statutory and non-statutory biodiversity sites, habitats and

species of principal importance4, legally protected and controlled species and other conservation

notable species that have been recorded over the previous 10 years (i.e. 2009 to 2019). Table J.3

lists the data compiled within the desk study area, which is the Proposed Development boundary

and the additional areas of search beyond as indicated, and as shown on Figure J.1 and J.2.

Table J.3 Information Relevant to the Desk Study

Ecological Feature Example / Description Desk Study Areas5

Statutory sites designated under international conventions or European Directives

Wetlands of International Importance (also known as Ramsar sites),

Special Areas of Conservation (SACs) and Special Protection Areas

(SPAs)

The Proposed Development

area and within 10 km of it.

Statutory sites designated under national legislation

Sites of Special Scientific Interest (SSSIs), National Nature Reserves

(NNRs) and Local Nature Reserves (LNRs))



Locally designated sites The study area encompasses four counties/metropolitan areas, each

with their own terms for local designated sites:

Berkshire – Local Wildlife Sites (LWS)

Buckinghamshire - LWS or Biological Notification Sites (BNS)

Greater London –Sites of importance for Nature Conservation

(SINC)

Surrey – Sites of Nature Conservation Importance (SNCI)



HPI and SPI, Red listed species6 and Legally protected species.

HPIs and SPIs, species recorded on The IUCN Red List of

Threatened Species and/or local Red Lists for the UK or relevant

sub-units (e.g. regions or counties) and legally protected habitats

and species include those listed on Schedules 1, 5 and 8 of the

Wildlife and Countryside Act 1981 (as amended), those included on

Schedules 2 and 5 of the Habitats Regulations. Badger and

Hedgerows are provided protection under the Protection of Badgers

Act 1992 and the Hedgerows Regulations 1997 respectively



Legally controlled species Legally controlled species include those listed on Schedule 9 of the

Wildlife and Countryside Act 1981 (as amended).



Bat roosting locations Bat roost locations are considered separately from other species

records in accordance with guidance.



Water body locations Water bodies may support species within the groups listed above

(for example legally protected great crested newts).


area and within 0.5 km of it.

4 Habitats of Principal Importance and Species of Principal Importance are referred to in this EcIA as HPI and SPI

respectively. 5 Justification for the extent of the desk study areas is provided in Appendix J.1. 6 Red listed species for the purposes of this assessment refer to those noted using IUCN criteria as being “Near

Threatened”, “Vulnerable”, “Endangered” and “Critically Endangered”, and those on present on local Red Lists in the

categories "Nationally Scarce” and “Nationally Rare”.

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J.4.6 Table J.4 lists the organisations and other sources that have supplied desk study data, together

with the nature of the data.

Table J.4 Sources of Desk Study Data

Source Summary of information provided

Magic.gov.uk Locations of statutorily designated sites, locations of HPIs mapped on the Priority

Habitat Inventory, locations of European Protected Species licenced projects between

2009 and 2019.

Thames Valley Environmental Records Centre (TVERC) (covering Berkshire)

Information on Local Wildlife Sites, records of HPIs and SPIs made between 2009 and

2019, records of legally protected and controlled species made between 2009 and

2019.

Buckinghamshire and Milton Keynes Environmental Records Centre (BMERC)



2019.

Greenspace Information for Greater London (GIGL)



2019.

Surrey Biodiversity Information Centre (SBIC)



2019.

Botanical Society for Britain and Ireland (BSBI)

Information on botanical records made between 2009 and 2019

British Bryological Society (BBS) Information on bryophyte (mosses and liverwort) records made between 2009 and

2019

Surrey Amphibian and Reptile Group (SARG)

Information on local amphibian and reptile records made between 2009 and 2019

Berkshire Ornithological Club (BOC) Information on ornithological records made between 2009 and 2019

Royal Society for the Protection of Birds (RSPB)

Information on ornithological records made between 2009 and 2019

WEBS/British Trust of Ornithology Information on ornithological records made between 2009 and 2019

Binfield Badger Club (BBC) Information on badger records made between 2009 and 2019

Berkshire and South Buckinghamshire Bat Group (BSBBG)

Information on local bat records (roosts and bats in flight) made between 2009 and

2019

London Bat Group (LBG) Information on local bat records (roosts and bats in flight) made between 2009 and

2019

Surrey Bat Group Information on local bat records (roosts and bats in flight) made between 2009 and

2019

Survey Work

J.4.7 A list of the ecological field surveys carried out to inform the preparation of this EcIA is provided in

Table J.5. The detailed methodologies for, and results of, these surveys can be found in

Appendices J.1-J.9. The confidential appendix (J.7) detailing locations of badger setts and a

confidential plan showing the location of otter holts, has been supplied to the planning authority and

Natural England.

J.4.8 Table J.5 lists the data compiled within the field survey areas as shown on Figures in technical

Appendices J.1 to J.9.

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Table J.5 Summary of Ecological Surveys

Survey Relevant guidance Field Survey Area Survey period Reference

Phase 1 Habitat Survey

For Phase 1 categorisation; Joint Nature Conservation Committee (JNCC) (2010) Handbook for Phase 1 Habitat Survey. Determining ‘importance’ of hedgerows: The Hedgerows Regulations 1997 Schedules 1-4

The Proposed Development area and within 100 m of it.

2017 Appendix J.1

National Vegetation Classification (NVC) Survey

National Vegetation Classification: User’s Handbook (Rodwell, 2006) The Proposed Development area and within 100 m of it.

2017-2018 Appendix J.2

Invertebrate Survey

Surveying terrestrial and freshwater invertebrates for conservation evaluation (Drake et al., 2007); Handbook of Biodiversity Methods (Hill et al., 2005); A Methodology for the Rapid Preliminary Assessment of Invertebrate Habitat Quality Potential, in the course of Extended Phase I Habitat Survey (Dobson unpublished)

The Proposed Development area and within 100 m of it.

2017-2018 Appendix J.3

Great crested newt presence/ absence survey

Natural England (2015) Great crested newts: surveys and mitigation for development projects Great crested newt mitigation guidelines English Nature 2001 Guidance for eDNA survey Biggs et al. 2014

Suitable habitat in the Proposed Development area and within 500m of it

April to June 2018 Appendix J.4

Reptile presence/absence and population estimate surveys

Griffiths and Inns (1998), Froglife (1999) Suitable habitat in the Proposed Development area and within 100 m of it

April-September 2017 April-October 2018 September 2019

Appendix J.5

Wintering bird surveys

Wetland Bird Survey (WeBS) Core Counts adapted from Bibby et al 2000. Winter Farmland Bird Survey (Atkinson et al. 2006).

Old Slade Lake LWS Suitable habitat in the Proposed Development area and within 100 m of it

Non breeding season 2014/15-2017/18 September 2017- March 2018

Appendix J.6

Breeding bird surveys

British Trust for Ornithology’s Common Bird Census (CBC) methodology (Gilbert et al., 1998), Waterways Breeding Bird Surveys, barn owl survey (Shawyer 2011)

Suitable habitat in the Proposed Development area and within 100 m of it

Mid-March to mid-June 2017 (CBC), mid May to mid-June 2017, May-July 2018 (Kingfisher) April, June-August 2018 (barn owls)

Appendix J.6


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Survey Relevant guidance Field Survey Area Survey period Reference

Badger survey Harris et al. (2001) Suitable habitat in the Proposed Development area and within 150 m of it

November 2017 Appendix J.7

Bat roost survey Bat Survey for Professional Ecologists: Good Practice Guidelines (Collins 2016)

Suitable habitat in the Proposed Development area and within 1 km m of it

July-August 2018 (buildings) May – October 2018 (Underpasses) January to April, Jun-September 2018 (Climbed tree inspection) May to August 2018 (Tree emergence survey)

Appendix J.8

Bat activity survey

Bat Survey for Professional Ecologists: Good Practice Guidelines (Collins 2016)

Suitable habitat in the Proposed Development area and within 100 m of it

April-October 2017 May to August 2017 (Advanced survey) May to August 2018 (Advanced survey)

Appendix J.8

Otter survey Monitoring the Otter (Chanin 2003a) Design Manual for Roads and Bridges (Highways Agency1999)

Suitable habitat in the Proposed Development area, connected waterbodies 500 m up and downstream of it.

May 2017 to October 2018 Appendix J.9

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J.5 Overall Baseline

J.5.1 The description of the ecological features below provides a summary of the biodiversity baseline as determined through desk study and field survey. Further details of the desk study and field survey programme are provided in Sections J.10–J.14, and detailed descriptions of the desk study and field survey results are provided in Appendices J.1 – J.9.

Current Baseline

Site Context and Surrounding Habitats

J.5.2 The land within the Proposed Development area covers approximately 13.7 ha, comprising of the broad habitat types grassland, woodland, scrub and water bodies. The Proposed Development area and surroundings are topographically relatively featureless; the land gently slopes down to the drain running north-west-south east through the north of the Proposed Development area. The M4 Motorway runs close to the northern boundary with the M25 Motorway approximately 800 m to the east. The surrounding landscape is heavily influenced by humans and includes arable land, golf courses, a restored quarry, urban areas, industrial and commercial complexes, and man-made waterbodies.

J.5.3 The land management is split to the north and south of the Proposed Development area approximately bisected by the drain. The south is dominated by horse grazed pasture cut to a very short level with only sparsely scattered trees providing any height. To the north is part of a shooting range; the firing range itself has been cut short, but large areas have been left alone leaving vegetation to grow tall allowing scrub and trees to dominate. The Proposed Development area does not appear to be actively manged for biodiversity.

Statutory Nature Conservation Sites (International/European)

J.5.4 Figure J.2 illustrates the locations of the statutory nature conservation sites designated under international conventions or via European directives. These comprise:

l South-West London Waterbodies Ramsar (1.8 km south of the Proposed Development );

l South-West London Waterbodies SPA (1.8 km south of the Proposed Development); and

l Windsor Forest and Great Park SAC (6.5 km south-west of the Proposed Development).

J.5.5 Burnham Beeches SAC lies 10.0 km to the north west of the Proposed Development red-line boundary. However it is over 10 km from the location of the stack, i.e. the source of the emissions. Airborne emissions from the Proposed Development are the only impact likely to be felt over 10 km, therefore this site was not considered as within the study area.

Statutory Nature Conservation Sites (National)

J.5.6 Figure J.2 illustrates the locations of the statutory nature conservation sites designated under national legislation. These comprise:

l Wraysbury Reservoir SSSI (1.75 km south of the Proposed Development);

l Staines Moor SSSI (1.98 km south-east of the Proposed Development);

Non-Statutory Nature Conservation Sites

J.5.7 Appendix J.1 Figure 1 illustrates the locations of the LWS; these comprise of three LWSs, one SNCI, one Metropolitan SINC and one BNS. They were designated by Slough or Windsor and Maidenhead Councils (the LWS), the Greater London Authority (Metropolitan SINC), Spelthorne Council (SNCI) and South Buckinghamshire Council (BNS). and are as follows:

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l Old Slade Lake LWS (0.10 km east of the Proposed Development);

l Lower Colne (Metropolitan) SINC (0.73 km east of the Proposed Development);

l Queen Mother Reservoir LWS (1.34 km south-west of the Proposed Development);

l Arthur Jacobs Nature Reserve LWS (1.46 km south-west of the Proposed Development);

l West of Poyle Meadows SNCI (1.56 km south of the Proposed Development);

l Opposite Iver Station BNS (1.76 km north of the Proposed Development).

Habitats

J.5.8 Appendix J.1 Figure 2 shows the habitats within and around the Proposed Development.

Broadleaved woodland

J.5.9 A wet woodland has developed along the ditch running through the site (north-west to south-east of the construction area). The woodland appears unmanaged but with regular human disturbance from the adjacent gun club (north of woodland).

Scattered trees

J.5.10 A small number (< 10) of trees were found along the eastern edge of the Proposed Development and within the construction compound area. These were semi-mature/mature individuals of broadleaved species.

Scrub

J.5.11 Dense and scattered scrub was found where management had been relaxed in the north-western and south western parts of the Proposed Development. This had grown to a medium height (3-5m) and contained a mix of woody and herbaceous plants.

Improved grassland

J.5.12 The improved grassland dominated the construction area and made up most of a large horse pasture.

Poor semi improved grassland

J.5.13 On the access road, close to the proposed junction with the A4, there was a section of semi-improved grassland which with no management was being taken over by tall ruderal vegetation.

Tall ruderal vegetation

J.5.14 Tall ruderal habitat occurs around the development and mixed with other habitats. It is the dominant habitat within sections of the gun club (northern end of the Proposed Development).

Stream

J.5.15 A fast flowing stream runs through the Proposed Development area approximately from the north-west to the south-east of the construction area. The banks of the stream are well vegetated including with tree species. A dry ditch runs along the east boundary of the site of the new facilities. As this contained no water the vegetation was consistent with the habitats it ran through, woodland and scrub.


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Amenity grassland

J.5.16 This comprised the more regularly used sections of the gun club including around the buildings and the car park. The diversity of this habitat is limited to species which can tolerate a regular cutting regime .

Species

Invertebrates

J.5.17 The habitats surveyed for invertebrates are shown in Appendix J.3 Figure 3.1. Within the survey area 588 invertebrate species were recorded, 33 of which are notable species.

Great crested newt

J.5.18 The water bodies surveyed for GCN are shown in Appendix J.4 Figure 3.1. All water bodies tested for GCN were found to have no evidence of their presence.

Reptiles

J.5.19 The areas surveyed for reptiles and the results of the survey are shown in Appendix J.5 Figure 3. Due to access restrictions the site could not be surveyed prior to 2019. Reptiles have been recorded in habitats linked to the site in 2017-18. Approximately 2 ha of habitat suitable for reptiles exists within the Proposed Development, however, surveys that took place on site in 2019 revealed that no reptiles were present.

Wintering birds

J.5.20 The areas surveyed for wintering birds are shown in Appendix J.6 Figure 2.1. The survey area encompassed the site and waterbodies which make up the Old Slade Lake LWS. Eleven notable species were recorded using the site overwinter and during the non-breeding season. Seventeen species of waterbirds used at least one lake within the LWS.

Breeding birds

J.5.21 The areas surveyed for breeding birds are shown in Appendix J.6 Figure 2.1 and the results of the survey in Appendix J.6 Figures 3.1-3.3. Nine species bred within the survey area. Kingfishers were observed and may have bred along the Colne Brook close to the site.

Badgers

J.5.22 The areas surveyed for badgers and evidence found are shown in Appendix J.7 Figure 3.1 . Setts were found approximately 100 m from the Proposed Development, with other evidence (mammal paths, latrines etc.) found within 150 m of the boundary.

Bats; Roosting

J.5.23 The results of the bat roost surveys are shown in Appendix J.8 Figure 3.7. Twenty-one bat roosts were found within 1 km of the site, covering four species and a range from solitary individuals to maternity colonies. Trees, buildings and road underpasses were used. Roosts were found during ‘traditional’ emergence and return surveys as well as advanced radiotracking works.

Bats; Foraging and commuting

J.5.24 The survey routes (transects) are shown in Appendix J.8 Figure 3.4 with figure 3.5 showing the results of the survey. The greatest activity recorded within 1 km of the site was along the Colne Brook, and around Orlitts and Slade Lake to the east. At least eight species of bats were recorded.

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Otters

J.5.25 The results of the otter survey are shown in a confidential Figure 3.1 from Appendix J.9. Evidence of otters was recorded along the Colne Brook and around the lakes making up Old Slade Lake LWS. This included spraints, footprints, laying up points and non-natal holts. The nearest holt was approximately 650 m upstream of the site.

Future Baseline

J.5.26 Determining a future baseline draws upon information about the likely future use and management of the site in the absence of development, known population trends (for species), climate change and any other Proposed Developments (consented or otherwise) that may act cumulatively with the Proposed Development to affect ecological features.

J.5.27 The future baseline of the study area will largely be driven by changes in land use. The major changes with planning consent are in relation to restoration of quarries and landfill. There are many sites in the area and details on the planned restorations are not always available. The interaction between sites may be complex with the network of sites potentially supporting more biodiversity than the sum of their parts. How beneficial the network of restoration will depend on the value of their individual biodiversity, how well linked they are, and the timing of restoration.

J.5.28 In the absence of the Proposed Development it is most likely there will be a minor improvement in biodiversity for the local area, although it is difficult to say that it will be markedly different. Overall land use/management is currently anticipated to remain largely unchanged in the absence of development and it is therefore considered appropriate to use the current baseline for the purpose of this assessment.

J.6 Consultation

J.6.1 No formal consultation has taken place and no responses have been received in relation to ecology.

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J.7 Scope of the Assessment

J.7.1 The method for determining the scope of the assessment within the EcIA differs from that used in other technical chapters within the ES in order to correspond with topic specific guidance (i.e. CIEEM 2018). However, the relevant receptors (i.e. ecological features), the spatial and the temporal scope are all defined in this section. The method has multiple stages enabling the scope of the assessment to be progressively refined.

Ecological Features

Scoping - Determining Importance

J.7.2 For this biodiversity assessment the first stage in determining the scope of the assessment is to identify which ecological features identified through the desk study and field surveys (see section J.5) are ‘important’7 in the context of the Proposed Development. Following CIEEM (2018) guidance, the importance of ecological features is first determined with reference to UK legislation and policy and then with regard to the extent of habitat or size of population that may be affected by the Proposed Development.

J.7.3 As the importance of ecological features is determined with regard to the extent of habitat or size of population that may be affected by the Proposed Development, each status can differ from that which would be conferred by legislative protection or identification as a conservation notable species. For example, house sparrow is important at a national level because it is a SPI and features on the Birds of Conservation Concern red list. However, a small population that could be affected by a development would be assessed as being of less than national importance due to the large, albeit declining, national population (in excess of 5 million pairs). Similarly a small length of hedgerow, a HPI, even if deemed to be ‘Important’ with regard to the Hedgerow Regulations may be considered to be less than of national importance due to the extent of this habitat type across a given county.

J.7.4 Wherever possible, information regarding the extent and population size, population trends and distribution of the ecological features has been used, to inform the categorisation described in Table J.6 to determine importance at the project level. Where detailed criteria or contextual data are not available, professional judgement was used to determine importance.

J.7.5 A justification of all determinations of importance are provided in this section, Table J.7 (for scoped in ecological features) and Appendices J.9.1 and J.9.2 (for all ecological features i.e. those scoped in and scoped out) to ensure transparency.

Table J.6 Importance of the Proposed Development for Ecological Features

Geographic context of importance Example / Description

International or European 1. European sites including SPAs, SACs, candidate SACs and Sites of Community Importance (SCI). Potential SPAs (pSPA), possible SACs (pSACs), Ramsar sites (designated under international convention) and proposed Ramsar sites should also be considered in the same manner in accordance with national planning policy. 2. Areas of habitat or populations of species8 which meet the published selection criteria based on discussions with Natural England and field data collected to inform the EcIA for designation as a European site or Ramsar site, but which are not themselves currently designated at this level.

7 Importance relates to the quality and extent of designated sites and habitats, habitat/species rarity and its rate of decline. Ecological features that are not considered to be important are those that are sufficiently widespread, unthreatened and resilient and with populations that will remain viable and sustainable irrespective of the Proposed Development. 8 This includes habitats and species listed under Annex I and Annex II of the Habitats Directive, birds listed under Annex I of the Birds Directive and all regularly occurring migratory birds.


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Geographic context of importance Example / Description

National 1. Nationally designated sites including SSSIs and National Nature Reserves (NNRs). 2. Areas (and the populations of species which inhabit them) which meet the published selection criteria guidelines for selection of biological SSSIs but which are not themselves designated based on field data collected to inform the EcIA, and in agreement with Natural England. 3. HPI and SPI, Red listed and legally protected species that are not addressed directly in Part 2 of the “Guidelines for Selection of Biological SSSIs” but can be determined to be of national importance using the principles described in Part 1 of the guidance. 4. Areas of Ancient Woodland e.g. woodland listed within the Ancient Woodland Inventory and ancient and veteran trees.

Regional (e.g. south-east)

1. Regularly occurring HPI and populations of SPI, Red listed and legally protected species may be of regional importance in the context of published information on population size and distribution.

County/Metropolitan 1. LNRs and Non-Statutory Designated sites including: LWSs, SINC of Metropolitan Importance, SNCI and, BNSs designated in the county/metropolitan context. 2. Areas which based on field data collected to inform the EcIA meet the published selection criteria for those sites listed above (for habitats or species, including those listed in relevant Local Biodiversity Action Plans) but which are not themselves designated.

Borough 1. Designated sites: SINCs designated in the sub-county (Borough or Local level) area context 2. Areas of habitats or populations of species identified during field data collection to inform the EcIA which meet the published selection criteria for those sites listed above.

Local 1. HPI and SPI, Red listed and legally protected species that based on their extent, population size, quality etc are determined to be at a lesser level of importance than the geographic contexts above. 2. Common and widespread semi-natural habitats occurring within the study area in proportions greater than may be expected in the local context. 3. Common and widespread native species occurring within the study area in numbers greater than may be expected in the local context.

Negligible 1. Common and widespread semi-natural habitats and species that do not occur in levels elevated above those of the surrounding area. 2. Areas of heavily modified or managed land uses (e.g. hard standing used for car parking, as roads etc.)

J.7.6 Where protected species are present and there is the potential for a breach of the legislation, those species should always be considered as ‘important’ features. With the exception of such species receiving specific legal protection, or those subject to legal control (e.g. invasive species), all ecological features that were determined to be important at negligible level have been scoped out of the assessment at this stage. Further, ecological features of local importance, where there was a specific technical justification, were also scoped out at this stage. This is because effects on them would not influence the decision-making about whether or not consent should be granted for the Project (in other words a significant effect in EIA terms could not occur). This approach is consistent with that described in CIEEM 2018. Specific justification for exclusion of each of these ecological features is provided in Appendix J.10.1 and J.10.2.

J.7.7 All legally protected species and ecological features that are of sufficient importance were then taken through to the next stage of the scoping assessment.

Spatial Scope

J.7.8 The construction and operation phases of the Proposed Development may result in the following environmental changes that could significantly affect ecological features/receptors:

l Land take/land use change;

l Changes to the surface hydrology;

l Increased light, noise and vibration (disturbances);



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l Exposure to contamination, i.e. via direct contact, air or water.

J.7.9 Key to establishing which environmental changes may result in likely significant effects, is the determination of a ZoI for each important ecological feature identified. ZoIs differ depending on the type of environmental change (i.e. the change from the existing baseline) as a result of the Proposed Development and the ecological feature being considered.

J.7.10 The most straightforward ZoI to define is the area affected by land-take and direct land-cover changes associated with the Proposed Development. This ZoI is the same for all affected ecological features.

J.7.11 By contrast, for each environmental change that can extend beyond the area affected by land-take and land-cover change (e.g. increased noise associated with construction activities within the land-take area), the ZoI may vary between ecological features, dependent upon their sensitivity to the change and the precise nature of the change. For example, a dormouse might only be disturbed by noise generated very close to its nest, while nesting marsh harrier might be disturbed by noise generated at a much greater distance, and other species (e.g. many invertebrates) may be unaffected by changes in noise. In view of these complexities, the definition of the ZoI that extends beyond the land-take area was based upon professional judgement informed (as far as possible) by a review of published evidence (e.g. disturbance criteria for various species) and discussions with the technical specialists who are working on other chapters of the ES.

J.7.12 It should be noted that the avoidance of potentially significant effects through the design process are implicitly taken in to account through the consideration of each ZoI, as are standard construction practices that are common place. When scoping in or out ecological features from further assessment, environmental measures (see Section J.8) associated with general good practice that are described within the Code of Construction Practice have been taken in to account (e.g. dust suppression, appropriately scheduled vegetation removal etc.) and referenced in Appendix J.10.

J.7.13 Ecological features that are scoped into the assessment (i.e. those of sufficient importance occurring within a relevant ZoI) are summarised in Table J.7, along with a summary of the justification for inclusion (see Appendix J.10.1 and J.10.2 for further details on those scoped out). For each ecological feature presented in Table J.7, the potential environmental changes and significant effects resulting from the Proposed Development are provided.

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Table J.7 Likely Effects, ZoIs and Justification for Scoped in Ecological Features

Ecological Feature Importance – legislation and policy

Importance – Proposed Development

Environmental changes and likely significant effects

Zone of Influence Relevant assessment criteria and scoped in justification

Broadleaved woodland On site

National Local Land take Within Proposed Development This habitat, within the Proposed Development boundary, qualifies as HPI. However, its small area and poor structure due to lack of management, as well as frequent occurrence of similar habitats within the surrounding area make it of no more than local importance. This semi-natural broadleaved woodland occurs within the footprint of the Proposed Development

Invertebrates Local Local Land take Within Proposed Development Six notable species were found within habitats linked to those found on site which were listed as nationally scarce or notable. This falls below the LWS criteria for Berkshire, therefore the invertebrates are considered of local importance in this context (BMERC & TVERC 2009).

Breeding birds National Negligible and legally protected

Land take Within Proposed Development All bird species are protected under the WCA. Numbers of bird territories were noted at similar levels to that found within the surrounding area therefor the bird assemblages are of negligible value.

Bats foraging and commuting

International Local (and legally protected)

Land take Within Proposed Development Small numbers of rarer species of bats were found on the site (in accordance with Wray et al. 2010).

Bats foraging and commuting

International Local (and legally protected)

Disturbance Within Proposed Development and 100 m around to allow for light and noise spill.

Small numbers of rarer species of bats were found on the site (in accordance with Wray et al. 2010).

Otters International Local and legally protected

Disturbance Within Proposed Development and 100 m around

Non-natal holts were found along the Colne Brook, into which the drainage discharges. Non-natal holts are below the LWS criteria for Berkshire (BMERC & TVERC 2009) therefore otters are considered of local value in this context.

Formatted Table

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Temporal Scope

J.7.14 The temporal scope of the assessment of the Biodiversity Assessment is consistent with the period over which the development would be carried out and therefore covers the construction and operational periods 2020-23 and 2023-48 respectively.

J.7.15 The environmental changes identified in paragraph J.7.8 can occur during the construction phase, operational phase, decommissioning phase or all phases of the Proposed Development. For the purposes of the assessment, all land take is assumed to take place in the construction phase. The effects of the environmental changes are considered with respect to their duration, frequency, timing and reversibility for each of the scoped in ecological features in Table J.7.

J.8 Environmental Measures Embedded into the Development Proposals

J.8.1 A range of environmental measures have been embedded into the development proposals. Table J.7 outlines how these embedded measures will influence the biodiversity assessment.

Table J.8 Summary of the Embedded Environmental Measures and how these Influence the Biodiversity Assessment

Ecological feature

Changes and effects Embedded measures and influence on assessment

Scattered trees

Several trees lie within the construction compound area. Uncontrolled works or vehicular movements could damage roots and negatively impact the trees

Trees will be fenced off and protected in line with BS 5837: 2012.

Scattered trees and scrub

The majority of the scrub and many scattered trees will be removed during the development of the site.

Landscape planting will include native species within the Proposed Development site, and along the access road. The road verges will also be re-seeded with grasses.

Badgers No badgers will be directly impacted by development, but there is a small chance they could be hit by vehicles during construction or operation.

Speed limits will be put in place and enforced. Vehicle drivers will be informed, during site induction, of the potential for badgers to be crossing the road at night.

J.9 Assessment Methodology

Introduction

J.9.1 The generic project-wide approach to the assessment methodology is set out in Chapter 4, and specifically in sections 4.5 to 4.7. However, whilst this has informed the approach that has been used in this biodiversity assessment, it is necessary to align with the standard industry guidance provided by CIEEM (2018).

J.9.2 The assessment has been based upon not only the results of the desk study and field surveys, but also relevant published information (for example on the status, distribution, sensitivity to environmental changes and ecology of the features scoped in to the assessment, where this information is available), and professional knowledge of ecological processes and functions.

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J.9.3 For each scoped-in ecological feature (see Table J.7), effects were assessed against the predicted future baseline conditions (see Section J.5.26 to J.5.28) for that feature during construction, operation and decommissioning.

J.9.4 Throughout the assessment process, the initial results of the assessment regarding potentially significant effects have been used to inform whether additional baseline data collection is required, together with the identification of environmental measures that should be embedded into the development proposals to avoid or reduce adverse effects or to deliver enhancements (see Section J.8). The results of the assessment, as set out in Section J.10 to J.14, therefore reflect the final scheme design (i.e. incorporating the environmental measures described in Section J.8 and Table J.8).

J.9.5 The spatial extent of the assessment (see Table J.7) reflects the area occupied by the ecological feature that is being assessed and, as a minimum, the ZoI of the changes that are likely to affect it.

J.9.6 Where part of a designated site is located within the ecological ZoI relating to a particular biophysical change as a result of the Proposed Development, an assessment has been made of the effects on the designated site as a whole. A similar approach has been taken for areas of notable habitat.

J.9.7 For species that occur within the ZoI, the assessment has considered the total area that is used by the affected individuals or the local population of the species (e.g. for foraging or as breeding territories).

Significance Evaluation Methodology

Overview

J.9.8 CIEEM (2018) defines a significant effect as one “that either supports or undermines biodiversity conservation objectives for ‘important ecological features’ or for biodiversity in general”.

J.9.9 When considering potentially significant effects on ecological features, whether these be adverse or beneficial, the following characteristics of environmental change are taken into account9:

l Extent – the spatial or geographical area over which the environmental change may occur;

l Magnitude – the size, amount, intensity or volume of the environmental change;

l Duration – the length of time over which the environmental change may occur;

l Frequency – the number of times the environmental change may occur;

l Timing – the periods of the day/year etc. during which an environmental change may occur;

l Reversibility – whether the environmental change can be reversed through restoration actions.

Magnitude of Change

J.9.10 Although the characteristics described above are all important in assessing effects by using information about the way in which habitats and species are likely to be affected, a scale for the magnitude of the environmental change, as a result of the Proposed Development, has been described in Table J.9 to provide an understanding of the relative change from the baseline position, be that adverse or beneficial changes.

9 The definitions of the characteristics of environmental change are based on the descriptions provided in CIEEM 2018. Other chapters in the ES may use some of the same terms albeit with a different definition.


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Table J.9 Guidelines for the Assessment of the Scale of Magnitude

Scale of change Criteria and resultant effect

High The change permanently (or over the long-term) affects the conservation status of a habitat/species, reducing or increasing the ability to sustain the habitat or the population level of the species within a given geographic area. Relative to the wider habitat resource/species population, a large area of habitat or large proportion of the wider species population is affected. For designated sites, integrity is compromised. There may be a change in the level of importance of the receptor in the context of the project.

Medium The change permanently (or over the long term) affects the conservation status of a habitat/species reducing or increasing the ability to sustain the habitat or the population level of the species within a given geographic area. Relative to the wider habitat resource/species population, a small-medium area of habitat or small-medium proportion of the wider species population is affected. There may be a change in the level of importance of this receptor in the context of the project.

Low The quality or extent of designated sites or habitats or the sizes of species’ populations, experience some small-scale reduction or increase. These changes are likely to be within the range of natural variability and they are not expected to result in any permanent change in the conservation status of the species/habitat or integrity of the designated site. The change is unlikely to modify the evaluation of the receptor in terms of its importance.

Very Low Although there may be some effects on individuals or parts of a habitat area or designated site, the quality or extent of sites and habitats, or the size of species populations, means that they would experience little or no change. Any changes are also likely to be within the range of natural variability and there would be no short-term or long-term change to conservation status of habitats/species receptors or the integrity of designated sites.

Negligible A change, the level of which is so low, that it is not discernible on designated sites or habitats or the size of species’ populations, or changes that balance each other out over the lifespan of a project and result in a neutral position.

Determining Significance - Adverse and Beneficial Effects

J.9.11 Adverse effects are assessed as being significant if the favourable conservation status of an ecological feature would be lost as a result of the Proposed Development. Beneficial effects are assessed as those where a resulting change from baseline improves the quality of the environment (e.g. increases species diversity, increases the extent of a particular habitat etc., or halts or slows down an existing decline). For a beneficial effect to be considered significant, the conservation status would need to positively increase in line with a magnitude of change of “high” as described in Table J.1.

J.9.12 Conservation status is defined as follows (as per CIEEM 2018):

l “For habitats, conservation status is determined by the sum of the influences acting on the habitat that may affect its extent, structure and functions as well as its distribution and typical species within a given geographical area;

l For species, conservation status is determined by the sum of influences acting on the species concerned that may affect its abundance and distribution within a given geographical area”.

J.9.13 The decision as to whether the conservation status of an ecological feature would alter has been made using professional judgement, drawing upon the information produced through the desk study, field survey and assessment of how each feature is likely to be affected by the Proposed Development.

J.9.14 A similar procedure is used where designated sites may be affected by the Proposed Development, except that the focus is on the effects on the integrity of each site; defined as:

l “The coherence of its ecological structure and function, across its whole area, that enables it to sustain the habitat, complex of habitats and/or the levels of populations of the species for which it was classified”.

J.9.15 The assessment of effects on integrity draws upon the assessment of effects on the conservation status of the features for which the site has been designated.

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J.10 Assessment of Effects: Broadleaved woodland (on site)

Baseline Conditions

Current Baseline

J.10.1 Within the redline boundary there is 0.46 ha of wet woodland forming part of the 7.79 ha of woodland on the land between the M4, M25, A4 and Horton Brook. The wet woodland is categorised under the National Vegetation Classification (NVC) system as W6b and fits the criteria of an HPI. The woodland is dominated by willow with the canopy around 15 m and has a ruderal-dominated understorey. It appeared unmanaged and in poor condition, though clearly disturbed by people as shown by a large quantity of broken ‘clay pigeons’.

Predicted Effects and their Significance

Land take: Loss of all wet woodland to make way for the development.

J.10.2 During the construction of the Proposed Development the woodland within the red-line boundary (approximately 0.46 ha) will be felled to make way for the new structures. New tree and shrub species will be planted along the northern and western boundary of the proposed facility along with a small copse in the south-eastern corner. This planting consists of a native species mix, similar to that found around the Proposed Development at present and will cover approximately 0.2 ha. This will take approximately 20-30 years to reach the maturity of the current habitat. There will be a non-significant negative impact on woodland at the local level.

J.10.3 A table is provided in Appendix J.11 summarising the assessment of land take on the broadleaved woodland on site. This summary demonstrates how the argument provided reflects the characteristics identified in CIEEM 2018 (as per paragraph J.9.9).

Summary of effects on broadleaved woodland (on site)

J.10.4 Given that all of the woodland on the site will be lost through the development, the overall magnitude of change on the broadleaved woodland is considered to be adverse and low and the resultant effect on its conservation status is non-significant.

J.11 Assessment of Effects: Invertebrates

Baseline Conditions

Current Baseline

J.11.1 Twelve land parcels were considered for invertebrate surveys based on rapid phase 1 survey and aerial photographs. Of these five were taken forward for targeted invertebrate surveys. The majority of these (three) consisted of complexes of open water, woodland fringe, marginal vegetation, deadwood, and ephemeral vegetation, one was scrub and wood, and the final one was the horse grazed pasture. The horse grazed pasture is the only habitat on site, the rest lie within 100 m of the Proposed Development boundary. The pasture was not considered to require a full suite of surveys but was subject to hornet robberfly surveys along with ‘incidental’ recording of species at times when other land parcels were subject to survey.

J.11.2 During the surveys a total of 588 invertebrate species were identified during the field surveys, thirty-three of which have a specific UK status associated with them. Of the notable species found:

l Within open water/woodland fringe/marginal & ephemeral vegetation and deadwood complex there were:

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� Two Red Data Book 2 species;

� Two Red Data Book 3 species;

� Thirteen nationally scarce species;

� Four notable species; and

� One data deficient species.

l In the scrub and woodland there were

� One vulnerable species;

� One Red Data Book 1 species;

� One nationally rare species;

� One nationally scarce species; and

� One notable species.

l In the pasture (within the Proposed Development boundary) there were:

� Three nationally scarce species and

� Three notable species.


Land take: Loss of grassland during construction to make way for the Proposed Development and temporarily for the construction compound

J.11.3 During the construction of the Proposed Development the grassland will be completely removed from the site of the Proposed Development and access road. This comprises approximately 13 % of the grazed grassland. A further 10% of this grassland will be temporarily lost as the construction compound is laid out. Given the extent and quality of this grassland (i.e. it comprises of relatively common species), it is likely that it will be quickly recolonised. Due to the relatively small extent of habitat lost permanently and relatively low value of the invertebrates found there will be no significant impact as a result of land take.

J.11.4 A table is provided in Appendix J.11 summarising the assessment of land take on invertebrates This summary demonstrates how the argument provided reflects the characteristics identified in CIEEM 2018 (as per paragraph J.9.9).

Summary of effects on invertebrates

J.11.5 Given the short term medium level change in construction, the short term low change in operation, and temporary medium change in decommissioning, the overall magnitude of change on the invertebrates is considered to be adverse and low, and the resultant effect its conservation status is Not Significant.

J.12 Assessment of Effects: Breeding birds

Current Baseline

J.12.1 During the breeding surveys nine species of birds were confirmed as breeding within the red line boundary or 100 m of it. This included three SPI, two of which, linnet and song thrush are on the

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Deleted: <#>Assessment of Effects: Reptiles¶<#>Baseline Conditions¶<#>Current Baseline¶<#>Land outside the red line boundary connected, and similar in composition to habitats on site have been surveyed for reptiles. These have been used as proxies for the on-site habitats which were inaccessible at the time of surveys (2017 and 2018). Both a ‘good’ population of slow worms and a ‘low’ population of grass snake have been found. Further survey will be required on the Proposed Development to confirm this, and identify likely impacts.¶<#>Predicted Effects and their Significance¶<#>Land take: Killing or injury of individuals during construction.¶<#>During the construction of the Proposed Development the scrub and taller grassland habitats which could support reptiles will be removed. Without mitigation if reptiles are present through the actions of construction vehicles (e.g. driving over animals, or digging them up) individuals could be killed or injured.¶<#>Any individuals not harmed would be pushed into adjacent habitats where there are already populations of reptiles. Increasing populations in these areas could result in competition for resources (food, dwellings) and reduce the survival of those animals.¶<#>A table is provided in Appendix J.10 summarising the assessment land take on reptiles This summary demonstrates how the argument provided reflects the characteristics identified in CIEEM 2018 (as per paragraph J.9.9). ¶<#>Summary of effects on reptiles¶<#>As there is only a small area of habitat being removed in the context of the local area the overall magnitude of change on reptiles is considered to be negligible and the resultant effect on its conservation status is not significant. Mitigation will be required as reptiles are protected from killing and injury under the WCA. ¶


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Birds of Conservation Concern (BoCC) red list, and the third dunnock is on the amber list. Kingfisher is likely to be breeding along the nearby Colne Brook. No evidence was found of barn owls using nearby trees; the closest observation of this species is north of the M4 motorway.


Land take: Damage or destruction of nests during construction and killing or injury of birds

J.12.2 During construction of the Proposed Development if vegetation is removed in the breeding season (approximately March to September inclusive), nests could be damaged or destroyed and birds in them killed or injured. This would be an offence contravening the WCA. The impact will only occur during construction, and other options for nesting are available in the local area for the following season or second broods of the same season.

J.12.3 A table is provided in Appendix J.11 summarising the assessment of land take on nesting birds. This summary demonstrates how the argument provided reflects the characteristics identified in CIEEM 2018 (as per paragraph J.9.9).

Summary of effects on breeding birds

J.12.4 The magnitude of impact on breeding birds is low as a relatively small area, and hence small number of birds and nests will be affected. Furthermore the effects will be temporary, birds can rebuild their nests and have new broods. Therefore a conclusion of no significant effect can be drawn. Mitigation will be required as breeding birds are legally protected

J.13 Assessment of Effects: Bats

Baseline Conditions

Current Baseline

J.13.1 Twenty one roosts were found within 1 km of the site. These included maternity roosts for:

l Soprano pipistrelle;

l Brown long-eared bat; and

l Daubenton’s bat;

J.13.2 A potential maternity roost for common pipistrelle was also found. No other bat species was found roosting in that area, and no roosts were found within the red line boundary.

J.13.3 Activity was greatest to the east of the site along the Colne Brook and by Orlitts and Old Slade Lakes. Bat activity was notable along the ditch running through the Proposed Development site (though less than around the feature above). The following species were found:

l Common pipistrelle.

l Soprano pipistrelle.

l Nathusius’ pipistrelle.

l Noctule.

l Leisler’s bat.

l Serotine.

l Brown long-eared bat.

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l Daubenton’s bat

l Myotis sp.

J.13.4 Along the Horton Brook west of the Proposed Development, radio tracking survey indicated the stream, woodland and grassland was especially important for an isolated population of brown long-eared bat, hence as detailed in Section J.4.3 the construction compound was moved out of this area.


Land take: Loss of foraging and commuting habitats

J.13.5 During the construction of the Proposed Development there will be a loss of scrub and ditch habitats where the new facilities will be and scrub along the access road. These features were used by bats, notably the scrub on the access road linking a brown long eared roost south of the A4 to foraging grounds along the Horton Brook, and to a lesser extent the ditch within the site which was used by multiple species

J.13.6 The brown long-eared population was noted during radio tracking to spend much of its time on the Horton Brook river corridor south of the M4 and north of Colne Brook, which may be man-made barriers to their further dispersal. If the foraging link is severed by the access road (including easement for construction vehicles) this may confine them to a small space where they cannot sufficiently forage to breed and significantly impact the favourable conservation status of this population. Gaps of more than 10 m should be avoided where possible as it is likely this could restrict bats ability to cross, in particular woodland specialists such as brown long eared bats (Gunnell et al 2012).

J.13.7 Bats of at least five species were recorded flying along the ditch through the site, though the activity is much lower than the broadly parallel Colne Brook. Construction on this ditch is likely to lead to reduced activity, however landscaping along the site boundary will provide an alternate route for bats travelling from Old Slade Lake LWS area to Old Wood (north-west of the Proposed Development) and any impacts would not be significant on the local populations of bats.

J.13.8 A table is provided in Appendix J.11 summarising the assessment of land take impacts on bats This summary demonstrates how the argument provided reflects the characteristics identified in CIEEM 2018 (as per paragraph J.9.9).

Disturbance: Lighting impacts on bats

J.13.9 The Proposed Development will require lighting both in the construction and operational phases for safety and security. Lighting could impact bats through several means. Firstly some species of bats are light averse and will actively avoid lit areas, these species include brown long eared bats and Myotis species, which are found around the Proposed Development. In this case bats may not be able to take advantage of the best foraging areas or even be prevented from accessing foraging areas if their way from the roost is ‘blocked’ by lit areas (Institute of Lighting Professionals 2018, Voight et al 2018) .

J.13.10 This could be the case for the brown long eared bats crossing the A4 to reach the Horton Brook via the route of the proposed access road. In this case the bats could be prevented from crossing the access road by lighting. The main effect will be in the operational phase, though some lighting may be required during construction.

J.13.11 Second lighting attracts insects and can effectively ‘vacuum’ them from nearby dark areas where the light adverse bats are feeding. This exacerbates the impacts caused by bats being restricted in their choice foraging areas by lighting or habitat fragmentation.

J.13.12 Finally some species of bats can take advantage of lights attracting insects and can forage around lights, but this may increase the risk of them being predated by birds which could otherwise not see them at night (Institute of Lighting Professionals 2018).

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J.13.13 A table is provided in Appendix J.11 summarising the assessment of disturbance impacts on the bats This summary demonstrates how the argument provided reflects the characteristics identified in CIEEM 2018 (as per paragraph J.9.9).

Summary of effects on bats

J.13.14 The impacts on land take and disturbance on bats in the absence of mitigation is likely to result in bats being blocked from their commuting routes. At the site of the new facility there will be alternative routes which are not lit. However the brown long eared bats roosting south of the A4 may well be prevented from reaching their main foraging areas due to the access road severing their commuting routes and lighting the resultant gap. The overall magnitude of change on the bats is adverse and medium as it may affect an entire local population, and the resultant effect its conservation status is Significant.

J.14 Assessment of Effects: Otters

Baseline Conditions

Current Baseline

J.14.1 Otters have been recorded along the following water bodies in the vicinity of the Proposed Development:

l Colne Brook;

l Orlitts Lake;

l Colnbrook West Lake; and

l Old Slade Lake

J.14.2 In the context of the Heathrow area the lakes where otters have been recorded have prey (fish) and good terrestrial habitat; levels of otter activity are higher where the watercourses are in proximity to lakes.

J.14.3 Evidence of otters included:

l Holts;

l Laying up places

l Spraints;

l Footprints;

l Slides; and

l Feeding remains


Disturbance: Noise and human activity during construction, maintenance and removal

J.14.4 During the construction of the Proposed Development there will be noise generated as well as an increased human presence in areas used by otters. Otters can adapt to human disturbance and they are found in many towns and cities (Chanin 2003b), however the Proposed Development will cause disturbance they have not habituated to in this location (e.g. construction vehicles, personnel

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in hi-visibility clothing). In the absence of mitigation, it is likely that otters will move away from the source of the disturbance temporarily.

J.14.5 A table is provided in Appendix J.11 summarising the assessment of disturbance impacts on otters This summary demonstrates how the argument provided reflects the characteristics identified in CIEEM 2018 (as per paragraph J.9.9).

Summary of effects on otters J.14.6 The impacts of disturbance on otters in the absence of mitigation is likely to result in animals being

disturbed from part of their territories. The overall magnitude of change on the otters is adverse and low, and the resultant effect on its conservation status is not significant.

J.15 Assessment Summary

J.15.1 A summary of the assessment is provided in Table J.10(overleaf).

J.15.2 The summary assessment below deals in an integrated way, with the effects of all phases of the Proposed Development. Potential effects are considered together as the assessment focuses on the favourable conservation status of each feature and as such, is be assessed throughout the lifespan of the Proposed Development. Often changes to a feature would occur during several stages of the development and the resultant effect may reverse during different phases. For example, during construction a population may decline, however, this effect may be reversed during operation. The summary below presents the magnitude of overall change, and whether that is adverse, beneficial or negligible.

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Table J.10 Summary of Significance of Adverse Effects

Receptor and summary of predicted effects Importance of Ecological Feature1

Magnitude of change2

Significance3 Summary rationale

Broadleaved woodland • Land take

Local

Adverse, low

Not significant

Loss of a small are of wet woodland due to construction, this habitat is found relatively frequently in the local landscape

Invertebrates • Land take

Local

Negligible

Not significant

Area taken for development is small. Temporarily used land (construction compound) will be likely quickly recolonised.

Breeding birds • Land take

Negligible (Legally protected)

Negligible

Not significant

Nesting birds likely to be killed or injured during construction and nests may be destroyed.

Bats foraging and commuting • Land take

• Disturbance

Local (legally protected Local (legally protected)

Adverse, medium Adverse, medium

Significant Significant

Land take and disturbance are likely to act together to prevent a population of bats from travelling between roosts and foraging areas.

Otters • Disturbance

Local (legally protected

Adverse, low

Not Significant

Disturbance both from construction noise and construction/maintenance personnel are likely to disturb otters

1. The importance of the feature is defined as per Table J.8, Section J.7, using the criteria set out in Table J.7, and method in Section J.7. 2. The magnitude of change on a receptor resulting from activities relating to the development is defined using the criteria set out in Section J.9, Table J.10 above and is defined as negligible, very low, low, medium, and high. 3. The significance of the environmental effects are either significant or not significant subject to the evaluation methodology outlined in Section J.9.

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J.16 Assessment of Cumulative Effects

J.16.1 As outlined in Section 4.8, consideration has been given as to whether any of the ecological features that have been taken forward for assessment in this EcIA are likely to be subject to cumulative effects on ecological features because of the effects generated by other developments.

Cemex Langley site

J.16.2 This agricultural site is proposed for a new quarry approximately 1 km north-west of the Proposed Development. The habitats impacted are relatively low value and there were no significant adverse effects on the biodiversity because of the quarry proposal. Some new water bodies will be created which may be beneficial to wintering birds using the Old Slade Lake LWS. Overall there is likely to be no significant cumulative impacts between the Proposed Development and the Cemex Langley site.

Cemex Datchett Quarry site

J.16.3 This quarry 3.7 km west of the Proposed Development was approved for planning in 2015, and extraction is now occurring. Previous to this it was agricultural land and of relatively low value. The proposed restoration includes some new water bodies which may be of benefit to wintering birds, though less likely to have an effect on individuals using Old Slade Lake LWS which is over 4 km from the quarry, with a large reservoir in between. Overall there is likely to be no significant cumulative impacts between the Proposed Development and the Cemex Datchett Quarry site.

Thorney Mill Road/Link Park Heathrow

J.16.4 This proposed storage centre 2 km north-east of the Proposed Development is on a brownfield site in Hillingdon. No ecological features were found on the brownfield site, although the land is adjacent to a complex of water bodies (including Thorney Pool and Maryfields Lake), likely to be functionally linked to Old Slade Lake LWS, along with the South London Waterbodies SPA and Ramsar as well as the SSSI which make up these international sites.

J.16.5 Although no assessment has been made it is feasible that birds using Thorney Pool, Maryfield Lake and others over winter could be disturbed by noise, light and construction workers from the brownfield site. However, as the Proposed Development will have no significant effect on birds using Old Slade Lakes (and the functionally linked habitats) even assuming the Thorney Mill Road/Link Park Heathrow does, there will be no significant cumulative effects between the two developments.

M4 Smart Motorway

J.16.6 The alteration of the M4 to a ‘smart’ motorway is taking place between Junction 3, 4 km east of the site, running past the site to Junction 5 2 km west and along to junction 12 (south of Reading, Berkshire). The development received DCO approval in September 2016.

J.16.7 Ecological impacts along these stretches include those on bats due to bridge works. They include works on the hard shoulder running along above underpasses known to be used by bats (see Appendix J.8). In the absence of mitigation this could reduce the value of bats, and act cumulatively with the Proposed Development which is has a non-significant effect on commuting bats, some of which may roost in the underpass. Within the mitigation for the smart motorway, there are measures to avoid impacts upon bats. With these measure in place there is anticipated to be no cumulative impacts on biodiversity between the M4 Smart Motorway and the Proposed Development.


June 2019

J.17 Consideration of Additional Mitigation or Compensation

J.17.1 Due to the effects of development on ecological receptors additional mitigation will be required for:

l Breeding birds

l Bats

l Otters

J.17.2 To avoid impacts on nesting birds where possible such works will be programmed to avoid the breeding season which generally runs from March to September inclusive. If this is not possible vegetation will be cleared after checking by a suitably competent ecologist. If birds are found to be nesting mitigation will involve setting up no-work zones around the nest until the young have fledged.

J.17.3 To reduce the impact on commuting bats resulting from the new access road, a hop-over of vegetation (a shrub or tree canopy grown from either side to meet in the middle) will maintain a physical link. Monitoring will be required to determine its effectiveness and decide if it is well situated and/or dense enough.

J.17.4 The hop-over if sufficiently dense will block out some light during late-spring and summer when the trees are in full leaf and bats are most active. Light pollution may also be reduced by creating a lighting strategy. The purpose if the strategy will be to minimise light spill onto the trees at the height where bats are flying. The strategy will take into account:

l The need for lighting, e.g. can lights be turned off late evening/early morning when bats are most active;

l Bulb type, using designs which minimise disturbance to bats, and emit little ultra-violet light (which attracts insects);

l Designing the height and angles of lamps to minimise light spill;

l Use lamps with designs that minimise the spread of lighting.

J.17.5 For otters further details on the construction and maintenance methods will be required to design sufficient mitigation. Mitigation will require pre-commencement surveys to evaluate an up-to-date status of the territory, e.g. have any natal holts been built. It is likely a method statement will be required for disturbance of otters, and mitigation design will include use of screens and/or noise baffles to prevent significant disturbance.

J.18 Conclusions of Significance Evaluation

J.18.1 Following the assessment of impacts in Sections J.10-J.14 as well as a summary in Table J.10 along with the mitigation outlined in J.17 significant effects will be avoided.

J.18.2 With appropriate timing of the vegetation clearance and a pre-commencement nesting bird check the magnitude of impacts as a result of the works on breeding birds is considered to be negligible, and the resultant effect its conservation status is Not Significant.

J.18.3 Assuming the vegetation can be joined up to facilitate bats crossing any gaps and that the lighting scheme can be maintained at existing levels the magnitude of impacts due to the works on foraging and commuting bats is considered to be negligible and the resultant effect on its conservation status is Not Significant.

J.18.4 Where noise and visual disturbance to otters is minimised through the use of appropriate acoustic and visual fencing the magnitude of impact on otters is considered to be negligible and the resultant effect on the conservation status is Not significant.

Deleted: <#>Reptiles¶

Deleted: <#>To avoid impacts upon reptiles pre-commencement site surveys covering the suitable habitats on site will take place. If animals are found, an appropriate receptor habitat will be found and improved to increase the number of reptiles it can support. This can be done through allowing grass to grow tall, opening up scrub and creating refugia from log/rubble/soil piles. Reptiles will be moved from the construction site to this receptor habitat.¶

Deleted: breeding

Deleted: J.14J.15

Deleted: Table J.10

Deleted: J.18

Deleted: <#>As any reptile population found on the site will be removed prior to development, and the remaining suitable habitat in the local landscape is substantial the overall magnitude of change on reptiles is considered to be negligible and the resultant effect on its conservation status is Not Significant. ¶


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J.19 Implementation of Environmental Measures

J.19.1 Table J.11 describes the environmental measures embedded within the Proposed Development and the mechanism by which they will be implemented (e.g. planning condition, Section 106 agreements etc.) and who is responsible for their implementation.

Table J.11 Summary of Environmental Measures Relevant to Biodiversity

Environmental measure Responsibility for implementation

Compliance mechanism EcIA Section Reference

Protection of trees and roots Developer/Contractor Planning condition or CEMP J.10

Landscape planting Developer/Contractor Planning condition or CEMP J.10

Nesting bird check Developer/contractor Planning condition or CEMP J.12

Provision of hop over for bats Developer/contractor Planning condition J.13

Sensitive lighting strategy Developer with advice from lighting engineer and ecologist

Planning condition J.13

Otter surveys, acoustic and visual fencing

Developer/contractor advised by ecologist

Planning condition or CEMP J.14

Speed limits to avoid road injury/killing animals

Developer/contractor Planning condition

J.20 References

Bibby, C.J., Burgess, N.D., Hill, D.A., and Mustoe, S.H. (2000). Bird Census Techniques, 2nd Ed. London: Academic Press,.

Biggs J, Ewald N, Valentini A, Gaboriaud C, Griffiths RA, Foster J, Wilkinson J, Arnett A, Williams P and Dunn F (2014). Analytical and methodological development for improved surveillance of the Great Crested Newt. Appendix 5. Technical advice note for field and laboratory sampling of great crested newt (Triturus cristatus) environmental DNA. Freshwater Habitats Trust, Oxford.

Buckinghamshire and Milton Keynes Environmental Records Centre and Thames Valley Environmental Records Centre (2009) Criteria for the Selection of Local Wildlife Sites in Berkshire, Buckinghamshire and Oxfordshire

British Standards Institution (2013). Biodiversity: Code of practice for planning and development (BS 42020:2013) London BSI p1-92

Chanin, P. (2003a). Monitoring the Otter Lutra lutra. Conserving Natura 2000 Rivers Monitoring Series No. 10, Peterborough: English Nature.

Chanin P (2003b). Ecology of the European Otter. Conserving Natura 2000 Rivers Ecology Series No. 10. English Nature, Peterborough.

Chartered Institute of Ecology and Environmental Management (2018) Guidelines for ecological impact assessment in the UK and Ireland: terrestrial, freshwater, coastal and marine. Winchester: CIEEM p. 1-86

Deleted: Table J.11

Deleted: Reptile surveys and mitigation... [5]Deleted: J.12J.13

Deleted: J.13J.14

Deleted: J.13J.14

Deleted: J.14J.15


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Collins, J. (2016). Bat survey for professional ecologists: Good practice guidelines. London: Bat Conservation Trust

Cutts, N, Hemmingway, K and Spencer, J. (2013) Waterbird Disturbance Mitigation Toolkit: Informing Estuarine Planning and Construction Projects Hull: Institute of Estuarine & Coastal Studies, University of Hull

Dobson, J. R. (2011). A methodology for the rapid preliminary assessment of invertebrate habitat quality potential, in the course of extended Phase 1 habitat survey. Unpublished Consultation Draft.

English Nature 2001 Great Crested Newt Mitigation Guidelines Peterborough: English Nature,

Froglife (1999). Froglife Advice Sheet 10: Reptile survey: an introduction to planning, conducting and interpreting surveys for snake and lizard conservation. Halesworth: Froglife, p. 1-11.

Griffiths, R. and Inns, H. (1998). Surveying. In: Gent, A. H. and Gibson, S. D. eds. Herpetofauna workers’ manual. Peterborough: Joint Nature Conservation Committee, p.1-13.

Gunnell, K. Grant, G. and Williams, C. (2012) Landscape and Unban design for bats and Biodiversity. London: Bat Conservation Trust.

Harris, S., Cresswell, P., and Jefferies, D. J. (2001) Surveying badgers. London: Mammal Society

Highways Agency (1999). Design Manual for Roads and Bridges – Volume 10 – Section 4 Part 4 – Nature Conservation Advice in Relation to Otters. London: Highways Agency.

Hill, D., Fasham, M., Tucker, G., Shewry, M., Shaw, P. (2005). Handbook of biodiversity methods. Cambridge University Press. United Kingdom.

Institute of Lighting Professionals (2018) Guidance Note 08/18: Bats and Artificial lighting in the UK: Bats and the Built Environment Series. Rugby: Institute of Lighting Professionals

Joint Nature Conservation Committee (2010) Handbook for Phase 1 habitat survey. Peterborough: JNCC

Rodwell, J. S. (2006) National Vegetation Classification: User’s handbook. Peterborough: Joint Nature Conservation Committee

Voigt, C.C., Azam, C., Dekker, J., Ferguson, J., Fritze, M., Gazaryan, S., Hölker, F., Jones, G., Leader, N., Lewanzik, D., Limpens, H.J.G.A., Mathews, F., Rydell, J., Schofield, H., Spoelstra, K., Zagmajster, M., (2018): Guidelines for consideration of bats in lighting projects. EUROBATS Publication Series No. 8. Bonn: UNEP/EUROBATS Secretariat,

Websites

Natural England (2015) Great crested newts: surveys and mitigation for development projects. Available at https://www.gov.uk/guidance/great-crested-newts-surveys-and-mitigation-for-development-projects#decide-if-you-need-to-survey. Accessed 6 March 2019

The Hedgerow Regulations 1997 (SI 1997/1660) Available at http://www.legislation.gov.uk/uksi/1997/1160/introduction/made Accessed 13 March 2019

Government Publications

Drake, C.M., Lott, D.A., Alexander, K.N.A. & Webb J. (2007). Surveying terrestrial and freshwater invertebrates for conservation evaluation. Natural England Research Report NERR005.

Ministry for Housing, Communities and Local Government, (2019). National Planning Policy Framework. London: MHCLG, p 4-75


June 2019

Slough Borough Council, (2004). The Local Plan for Slough. Slough: SBC. p88-91

Slough Borough Council, (2008). Slough Local Development Framework Core Strategy Development Plan Document 2006-2026. Slough: SBC. p46-47

Slough Borough Council, (2010). Slough Local Development Framework Site Allocations Development Plan Document. Slough: SBC. p88

J.1 © Wood Environment & Infrastructure Solutions UK Limited

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Appendix J.1 Baseline Report – Extended Phase 1 Habitat Survey


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Appendix J.2 Baseline Report – National Vegetation Classification (NVC) Survey


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Appendix J.3 Baseline Report – Invertebrate Survey


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Appendix J.4 Baseline Report – Great Crested Newt Survey


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Appendix J.5 Baseline Report – Reptile Survey


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Appendix J.6 Baseline Report – Ornithological Survey


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Appendix J.7 CONFIDENTIAL Baseline Report – Badger Survey


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Appendix J.8 Baseline Report – Bat Survey


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Appendix J.9 Baseline Report – Otter Survey

Deleted: ➝CONFIDENTIAL


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J.10.1 © Wood Environment & Infrastructure Solutions UK Limited

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Appendix J.10 Scoping of the Assessment - Summary

This appendix provides the rationale for the scope of the assessment and comprises two tables. Table J.10.1 describes and justifies the level of importance assigned to the ecological features identified during the data gathering exercise carried out to inform this assessment. Table J.10.2 determines and justifies whether those ecological features require further assessment as they have either sufficient legal protection for a breach in legislation to occur or are of sufficient importance that a significant effect may occur as a result of the Proposed Development.

Within Table J.10.1, consideration is given to both the importance of ecological features based on legislation and policy (refer to paragraphs J.7.2 to J.7.4) and importance with regard to the Proposed Development (refer to paragraph J.7.2 to J.7.4 and Table J.6). The justification provided for the decision to scope in or out each ecological feature is based on information on its status both with regard to the Proposed Development, and the local, county, regional, national or international context, where available.

Table J.10.1 – Importance of Ecological Features

Ecological Feature Importance – Legislation & Policy

Importance – Proposed Development Justification Scoped Out of Assessment (Y/N)

South West London Waterbodies Ramsar

International National This site is designated under the Ramsar convention as a Wetland of International Importance. Linked to the proposed designation by wintering birds which use the adjacent waterbodies and the designated site.

N

South West London Waterbodies SPA (includes Wraysbury Reservoir SSSI and Staines Moor SSSI)

European (National for SSSI)

National This site is designated in accordance with the EC Birds Directive. Linked to the proposed designation by wintering birds which use the adjacent waterbodies and the designated site. (For SSSI’s these sites are designated under the WCA as a SSSI. Linked to the proposed designation by wintering birds which use the adjacent waterbodies and the designated site.)

N

Windsor Forest and Great Park SAC

European National This site is designated in accordance with the EC habitats directive. A section of the SAC lies within 10km of the Proposed Development therefore it is of national importance in this context.

N



Deleted: 9


Deleted: 9Deleted: Table J.6

Deleted: 9


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Deleted: 9

Old Slade Lake LWS County County The site is designated by the borough council under criteria set for the county of Berkshire. The LWS lies within 300 m of the Proposed Development.

N

All LWS within 2km County County The sites are designated by the borough councils under criteria set for the relevant county. All are within 2 km and could be affected by airborne contaminants.

N

Broadleaved woodland On site

National Local This habitat, within the Proposed Development boundary, qualifies as HPI. Its small area and poor structure due to lack of management, as well as frequent occurrence of similar habitats within the surrounding area make it of no more than local importance.

N

Broadleaved woodland Off Site

National County This habitat qualifies as HPI. The amount of habitat, relative to that found in the surrounding area make it of county importance.

Y

Scattered Trees National Negligible Veteran trees are of note in national planning policy, however the trees found here are semi-mature/mature, none of which are veteran and similar trees are found relatively frequently in the local landscape.

Y

Scrub Negligible Negligible Common and widespread, fast growing habitat Y

Improved grassland Negligible Negligible Common and widespread, fast growing habitat Y

Poor semi-improved grassland

Local Negligible Common and widespread, fast growing habitat Y

Tall ruderal vegetation Negligible Negligible Common and widespread, fast growing habitat Y

Stream National Negligible The stream does not fit HPI or county designation criteria. It has relatively low quality water and acts as a drainage ditch.

Y

Amenity grassland Negligible Negligible Common and widespread, fast growing habitat Y

Invertebrates National County Six notable species were found within habitats linked to those found on site which were listed as nationally scarce or notable.

N



Great crested newt European Negligible Not found within 500 m of the Proposed Development Y

Reptiles National Negligible No reptiles were found within the site; populations were found nearby. Y

Deleted: Ecological Feature

Deleted: Local (and legally protected)

Deleted: Populations of reptiles found in similar habitats, connected to the site

Deleted: N


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Deleted: 9

Wintering birds International National Migratory wetland birds over winter on the nearby Old Slade Lake LWS which could be influenced by development

N

Breeding birds National Negligible but legally protected All bird species are protected under the WCA. Numbers of bird territories were noted at similar levels to that found within the surrounding area therefor the bird assemblages are of negligible value.

N

Badgers National Negligible but legally protected No setts found within 50 m of the Proposed Development Y

Bats; roosting European Negligible but legally protected No Roosts found within the Proposed Development Y

Bats commuting and foraging

European Local (and legally protected) Small numbers of rarer species of bats were found on the site (in accordance with Wray et al. 2010).

N

Otters European Local (and legally protected) Otter holt (not natal) found along the Colne Brook which lies within 100 m of the Proposed Development

N

For those ecological features that remain scoped in following the process as described in Table J.10.1, the following are provided in Table J.10.2: description of the potential environmental change and associated effect (refer to paragraphs J.7.7– J.7.10); a description of the zone of influence for each ecological feature (refer to paragraph J.7.7– J.7.10 and Table J.7); justification of the decision to scope in or out each ecological feature based on the likely scale of the potential effect, general working measures (i.e. those covered within the Code of Construction Practice) that negate the effect and relevant information on the features status within the local, county, regional, national or international context where that is available.

Table J.10.2 – Scoping of Ecological Features of local or Above Importance and those Receiving Legal Protection

Ecological Feature Environmental Change and potential effect

Zone of Influence Scoped Out (Y/N) Justification

South West London Waterbodies Ramsar

Disturbance to overwintering birds using functionally linked habitat

Functionally linked habitats within 100 m of the Proposed Development boundary

Y The Noise and Vibration Assessment indicates that during construction maximum noise levels will reach 96 dB on site. Where noise is at this intensity, the minimum distance birds must be from the source to exhibit little or no behavioural change (i.e. they can be said to be undisturbed), is approximately 20 m. At this distance the noise is at or below 70 dB, the threshold below which birds are less likely to be

Deleted: not used for breeding

Deleted: 9

Deleted: 9Deleted: Table J.7

Deleted: 9


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Deleted: 9



‘disturbed’ (Cutts et al. 2013). No part of the site is within 20 m of the LWS therefore there will be no effect on the birds during construction. At the LWS the peak noise generated by construction is likely to be around 53-58 dB and no behavioural response is expected from the birds (Cutts et al.2013). Furthermore the birds suffer high levels of disturbance from Heathrow, the M25 and M4 along with existing industrial facilities within 100m including the current lakeside EfW Noise levels generated during operation are likely to exceed the disturbance threshold within or very close to (10 -15 m from) the new buildings. The noise level at the LWS caused by the development will be much lower than the threshold to cause disturbance (expected to be <45 dB). The Zone of Theoretical Visibility (ZTV) plan (Chapter 10: Landscape, townscape and visual effects) shows that due to the topology of the site (the waterbodies are in a slight hollow) and the tree line on the western edge of the Old Slade Lakes LWS (i.e. the side facing the Proposed Development) worker and vehicles will not be visible to birds on the water.


Disturbance to overwintering birds using functionally linked habitat

Functionally linked habitats within 300 m of the Proposed Development boundary

Y See South West London Waterbodies Ramsar


Exposure to contamination

Within Proposed Development boundary and within 2 km of it to account for maximum dispersal of airborne contaminants.

Y The development is a like-for-like replacement for an existing facility and therefore the air quality effect of the Proposed Development is not Significant (see the Air Quality Assessment). Furthermore the location, close to two major motorways, The Air Quality Assessment (Technical Appendix D to the Environmental Statement) showed that critical levels of all pollutants considered and critical loads of nitrogen and acid deposition on the SPA and SSSIs were below 1 %. No proposed or consented developments were identified which required an assessment of in combination effects on air quality. Therefore no significant impact is expected and the assessment has not been taken further.

Windsor Forest and Great Park SAC

Exposure to contamination leading to damage to habitat within the site


Y The development is a like-for-like replacement for an existing facility and therefore the air quality effect of the Proposed Development is not Significant (see the Air Quality Assessment) The Air Quality Assessment (Technical Appendix D to the Environmental Statement) showed that critical levels of all pollutants considered and critical loads of nitrogen and acid deposition on the SAC were below 1 %. No proposed or consented developments were identified which required an assessment of in combination effects on air quality. Therefore no significant impact is expected and the assessment has not been taken further.


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Deleted: 9



Old Slade Lake LWS Disturbance to overwintering birds

Suitable habitats within 300 m of the Proposed Development boundary

Y See South West London Waterbodies Ramsar

All LWS within 2km Exposure to contamination


Y The development is a like-for-like replacement for an existing facility and therefore unlikely to increase airborne contamination. Furthermore the location, close to two major motorways, Heathrow Airport and industrial complexes would indicate that the area is already subject to significant amounts of airborne contaminants. The Air Quality Assessment (Technical Appendix D to the Environmental Statement) showed that critical levels of all pollutants considered and critical loads of nitrogen and acid deposition on all LWS were below 100 %. This is the level at which more assessment would be triggered. Therefore no significant impact is expected and the assessment has not been taken further.

Broadleaved woodland On Site

Land take leading to loss of woodland within the Proposed Development

Within Proposed Development boundary only

N The woodland within the red line boundary is a HPI and will be removed completely as a result of the development. Any replacement will take time (20-30 years) to reach the stage of maturity the current woodland.

Broadleaved woodland Off site

Changes to the surface hydrology

Within the footprint of the Proposed Development and along the waterbodies either side running between the Horton Brook and Colne Brook.

Y No change of flow on downstream receptors as a result of the drainage strategy.

Invertebrates Exposure to contamination leading to changes in habitats which support invertebrates

Within the Proposed Development boundary and 100 m of it

Y See all LWS within 2 km. Changes on the habitats which support invertebrates as a result of exposure to contamination are not predicted to be significant. Therefore it is not anticipated that there will be any impact on the animals which use those habitats.

Invertebrates Land take resulting in loss of habitats which support invertebrates

Within the Proposed Development boundary

N Of the grazed grassland in the local, connected, landscape 2.5% will be lost permanently and 10 % temporarily during the construction period. This potentially could significantly affect the invertebrates supported by that habitat including species of note.

Wintering birds Disturbance to overwintering birds

Suitable habitats within 100 m of the Proposed Development boundary

Y See South West London Waterbodies Ramsar Deleted: Reptiles ... [6]


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Deleted: 9



Breeding birds Land take resulting in killing or injuring birds, or destruction of nests


N Removal of scrub and trees could kill or injure birds, or destroy nests contravening the legal protection covering all wild birds.

Breeding birds Land take resulting in loss of opportunity for nesting


Y Sufficient alternative nesting opportunities are available elsewhere near to the Proposed Development.


Land take resulting in severance of commuting routes


N Removal of hedgerow during construction for the access road will sever an important bat commuting corridor.


Disturbance resulting in severance of commuting routes via lighting


N Lighting for the access road will increase disturbance of light averse bats potentially blocking their commuting route between roost and foraging area.

Otters Disturbance as a result of construction activities


N Construction of a drainage system from the access road into the Colne Brook may temporarily disturb otters, a European Protected Species using the waterbody.


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Deleted: 0

Appendix J.11 Assessment of Effects – Summary Tables

Table J.11.1 – Summary of the Assessment of Degradation of broadleaved woodland due to land take

Characteristic Summary

Importance Local

Positive / negative Negative

Extent All woodland within the red line boundary will be lost

Magnitude Approximately 0.46 ha of wet woodland will be lost equating to approximately 6 % of the woodland within the immediate area.

Duration The effect will last the duration of the operation of the Proposed Development.

Timing The effect will occur throughout the construction period at all times.

Frequency Once during the construction period

Reversibility Effects will be reversible in the long term following demolition of the Proposed Development with new woodland likely to take 20-30 years after demolition is complete.

Outcome The effect on woodland is low due to the small extent affected and the potential for habitats to be restored in the long term. Therefore a conclusion of a not significant negative effect can be drawn.

Deleted: 0

Deleted: 0


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Deleted: 0

Table J.11.2 – Summary of the Assessment of effects on invertebrates due to land take


Importance Local


Extent A portion of the grassland will be permanently lost to construction, with a larger area temporarily lost during the construction phase for the compound and plant access, restored at the end of the construction phase.

Magnitude Approximately 6.5 ha of grazed grassland will be permanently lost which is 13 % of the total area of grassland locally, 5.0 ha of grazed grassland will be temporarily lost during construction which is 10 % of the total area of grassland locally

Duration The permanently lost grassland will be gone for the duration of the construction, operation and decommissioning phase. At the end of the construction period the rest of the grassland will be restored

Timing The permeant loss of grassland will occur during the construction, operation and decommissioning period at all times, temporary loss will occur during the construction period at all times


Reversibility Effects will be reversible in the short term; as soon as the land is available it will be restored within 2-3 years

Outcome The effect on invertebrates is low due to the small extent of habitat effected permanently and the potential for habitats to be restored in the short term, to be re colonised by adjacent populations of invertebrates. Therefore a conclusion of a no significant negative effect can be drawn.

Deleted: 0


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Deleted: 0

Table J.11.3 – Summary of the Assessment of Effects on breeding birds due to land take


Importance Local


Extent All the scrub and woodland habitat within the Proposed Development boundary will be lost, these could be used by nesting birds

Magnitude Approximately 1 ha of woodland and scrub, approximately 9 % of that found in the local area will be lost during the construction phase and unavailable during the lifetime of the Proposed Development.

Duration The effect will last the duration of the operation of the Proposed Development.

Timing The effect will occur throughout the construction period during the breeding season (generally March to September)


Reversibility E.g. Effects will be reversible in the medium term following the decommissioning of the development, suitable habitats for birds will recover within 5-10 years post-decommissioning

Outcome The effect on breeding birds is low due to the relatively small numbers affected and the potential for successful restoration. Therefore a conclusion of no significant effect can be drawn. Mitigation will be required as breeding birds are legally protected

Deleted: Table J.10.3 – Summary of the Assessment of effects on reptiles due to land take¶Characteristic ... [7]Deleted: 9Deleted: 0

Deleted: 4


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Deleted: 0

Table J.11.4 – Summary of the Assessment of effects on bats due to land take Characteristic Summary

Importance Local


Extent The route of the access road runs through and area of scrub approximately 30-40 m wide

Magnitude A medium adverse effect could occur along the access road as it passes through the scrub. A population of brown long-eared bats uses this as a commuting route to foraging grounds.

Duration The access road will be in place during the lifetime of this project.

Timing The effect will occur through the construction and operation period at all times

Frequency Once during the construction period.

Reversibility Effects would be reversible in the medium term by allowing the tree canopy to grow over the road and meet. With appropriate management it is anticipated this would take 5-10 years following construction of the road to be sufficient.

Outcome The effect on bats is medium due to the impacts on the whole population found in this area. Therefore a conclusion of significant effect can be drawn.



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Deleted: 0

Table J.11.5 – Summary of the Assessment of Disturbance of Bats due to Lighting


Importance Local


Extent The route of the access road runs through an area of scrub approximately 30-40 m wide. This area will be lit up for safety

Magnitude An adverse effect could occur along the access road as it passes through the scrub. A population of brown long-eared bats uses this as a commuting route to foraging grounds.

Duration The access road and lighting will be in place during the lifetime of this project.

Timing The effect will occur through the construction and operation period at night time (i.e. when bats are active)

Frequency Nightly during the operation period

Reversibility Effects would be reversible in the short term by switching the lights off.

Outcome The effect on bats is medium and adverse due to the impacts on the whole population found in this area. Therefore a conclusion of significant effect can be drawn.



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Deleted: 0

Table J.11.6 – Summary of the Assessment of Disturbance of Otters due to Construction of Drainage works


Importance Local


Extent The drainage for the southern end of the access road will be channelled into the Colne Brook.

Magnitude An adverse effect could occur during the construction phase due to noise and the presence of workers in areas used by otters. Non-natal holts have been found along the Colne Brook.

Duration The duration will depend on the design of drainage system chosen. As a minimum it will occur for a short time during the construction period, and during the operational period when maintenance is required. If it is removed during decommissioning the disturbance will occur during the removal process.

Timing The effect will occur through the construction throughout the installation and operation period when maintenance is required, as well as decommissioning when it is removed.

Frequency During the construction period, as required during Operation and once during decommissioning (if removed)

Reversibility Effects would be reversible in the short term when construction/maintenance/removal ceases

Outcome The effect on otters is low and adverse due to the restriction in range (i.e. the otters are reliant on water bodies). Therefore a conclusion of not significant effect can be drawn.


Deleted: A n

Deleted: breeding holt

Deleted: s



30

Appendix 5 Amended Technical Appendix J5 Supplementary Reptile Survey

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2 © Wood Environment & Infrastructure Solutions UK Limited

October 2019 Doc Ref. 41488-WOD-ZZ-XX-RP-OE-0005_A_P01.5

Report for Lakeside Energy from Waste

Main contributors Rachel Bamford Tim Bradford

Issued by ................................................................................. Tim Bradford

Approved by ................................................................................. Sabrina Bremner

Wood Floor 23 25 Canada Square Canary Wharf London E14 5LB United Kingdom Tel +44 (0)20 3215 1610 Doc Ref. 41488-WOD-ZZ-XX-RP-OE-0005_A_P01.5 H:\Projects\41488 Lakeside Energy from Waste\G - General\Biodiversity\Baseline reports\Appendix 9.5 Reptiles

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Document revisions

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3 Third Draft 21.05.19

4 Issue 17.06.19

5 Re-issue following further survey 01.10.19



Executive summary

Purpose of this report

This report has been produced for the purpose of supporting a planning application and identifying pre-construction mitigation measures recommended for the relocation of reptiles from the site at Lakeside Energy from Waste, Slough, Berkshire1.

Methods The Site location and the area this report focusses on has been based upon the red-line boundary given in drawing number 2277 05/SK012. Baseline data for reptiles was collated in four distinct stages: desk study, field survey scoping, presence/likely absence surveys and population size class assessments (where appropriate). The desk study and field survey scoping identified the presence of suitable habitats capable of supporting reptiles to be present within the Site or within 100m of the Site boundary (to determine the context of reptile populations locally). In 2017 and 2018 it was not possible to gain access to survey the Site; therefore surveys were undertaken on the land adjacent.

Where access was available, those areas of habitat previously identified as being suitable to support reptiles were subject to presence/likely absence surveys, comprising seven survey visits undertaken between April and September 2017. The 2017 survey work recorded the presence of grass snake and slow worm within the survey areas. Subsequent population size class assessment surveys, comprising 20 survey visits, were undertaken between April and October 2018.

Following access to the Site being granted in 2019 additional survey work was undertaken within the Site and at a receptor site situated nearby.

Results The results of these surveys indicated that a ‘low’ population of grass snakes and ‘good’ population of slow worms were present near the Site.

Further surveys undertaken during the 2019 produced no records of reptiles within the Site. A population of grass snakes was recorded at the receptor site being surveyed at the same time.

Limitations of the results are given in Section 4.5.

Recommendations In 2019, no reptiles were found within the Site, therefore no translocation from the Site will be needed.

However, due to the presence of populations of reptiles nearby the Site ( as recorded in 2017), it is recommended that a destructive search should be undertaken, comprising the cutting of vegetation within the site in two stages followed by scraping off of the topsoil. The works should be done under the supervision of an ecologist and carried out in mild and dry weather conditions, when reptiles are active.

Prior to these works commencing a nesting bird check should also be undertaken.

1 Hereinafter referred to as the ‘Site’. 2 Terence O’Rourke Replacement Lakeside EfW and HTI Facilities: Planning Application Boundary Revision B. Drawn 28/05/19



Contents

1. Introduction 6

1.1 Background 6 1.2 Site location 6 1.3 Purpose of the report 6

2. Legislative and planning context 7

2.1 Legislation 7 2.2 Planning Policy 7

3. Methods 8

3.1 Desk study and field survey scoping 8 3.2 Field surveys 8

Presence/likely absence surveys 8 Population size class assessment 9 Weather conditions 10

4. Results 11

4.1 Desk study and field survey scoping 11 4.2 Presence/likely absence survey: 2017 and 2018 11 4.3 Population size class assessment survey: 2018 11

Population size class assessment 12 4.4 Presence/likely absence survey: 2019 12 4.5 Deviations, constraints and limitations 12

5. Conclusions and recommendations 13

5.1 Reptiles population on Site 13 5.2 Recommended precautionary measures: vegetation clearance 13

Reptiles 13 Nesting birds 14

5.3 Habitat creation and enhancement 14

Table 2.1 Biodiversity policy issues considered 7 Table 3.1 Total refugia numbers and approximate refugia densities within each survey area in 2017 9 Table 3.2 Total refugia numbers and approximate refugia densities within each survey area in 2019 9 Table 3.3 Total refugia numbers and approximate refugia densities within each survey area in 2018 10 Table 3.4 Reptile population size class 10 Table 4.1 Presence/likely absence survey results in 2017 11 Table 4.2 Population size class assessment survey results in 2018 11 Table 4.3 Presence/likely absence survey results in 2019 12



Figure 1 Survey areas 2017/2018 A1 Figure 1.1 Survey areas 2019 A1 Figure 2 Refugia distribution 2017/2018 A1 Figure 3 Reptile survey results 2017 and 2018 A1 Figure 3.1 Reptile survey results Rifle Range (2019) A1 Figure 3.2 Reptile survey results Receptor site at Thorney Park Golf Club (2019) A1

Bibliography 15

Appendix A Figures Appendix B Reptile survey weather conditions Appendix C Reptile survey results Appendix D Scientific names of species described in this report



1. Introduction

1.1 Background

Lakeside Energy from Waste (EfW) commissioned Wood to produce ecological baseline survey reports to support an Ecological Impact Assessment (EcIA) as part of the planning submission (Slough Borough Council application reference P/17826/000) for a replacement EfW facility in Slough, Berkshire (hereafter referred to as ‘the Site’).

At the time of the submission (June 2019) access had not been granted for survey on the main footprint of the new facility within the Site and therefore the results from survey of the adjacent land were used as a proxy. Post submission, the surveyors obtained land access and the Site was surveyed in September 2019 to inform the pre-construction mitigation strategy. The surveyors also visited a ‘receptor’ site which would receive any animals moved from the development area within the Site. It was necessary to survey the receptor site to determine what the current status of reptiles there was before introducing new ones, and to find out if habitat improvements were needed to make sure it could support the introduced reptiles.

The Site consists of the construction site of the new EfW facility, a construction compound and an access road leading to the A4 (Colnbrook By-pass) which will be used both during construction and for bringing materials on and off site during operations. A detailed description of the development has been included within Chapter 3 of the Environmental Statement3.

1.2 Site location

The Site is located south-west of the M4/M25 motorways’ junction and is centred approximately at Ordnance Survey National Grid reference TQ 03351 78005, immediately west of Thames Water’s Iver South Sludge Dewatering Centre, Lakeside Road, Slough, Berkshire. The nearest postcode is SL3 0ED. Figure 1 (Appendix A) shows the Site location.

The study area for the September 2019 survey work was the Richings Park Airgun Club land (the ‘rifle range’) which lies in the north of the Site (approximate centre at TQ 0341 7806). The surveys for the receptor site were situated on two parts of Thorney Park Golf Club (two areas centred at TQ 0431 7971 and TQ 0458 7967). Figure 3.1. (Appendix A) shows the location of the September 2019 survey areas. Land outside this area on site was not surveyed in September 2019 as it was either unsuitable (See Section 3.1) or the impacts were negligible.

1.3 Purpose of the report

This reptile report is intended to provide the results of baseline surveys which will be interpreted within the Natural Heritage Chapter (Chapter 11) of the Environmental Statement.

The report will also provide recommendations with the objective of mitigating for impacts on any reptiles present on Site.

3 Terrence O‘Rourke (2019) Replacement Lakeside EfW and HTI Facilities: Environmental statement



2. Legislative and planning context

2.1 Legislation

All six species of reptiles native to the UK are protected under the Wildlife and Countryside Act 1981 (as amended) and benefit from various levels of protection. The most widespread species: adder, grass snake, slow-worm) and viviparous lizard receive partial or full protection under Section 9 of the Wildlife and Countryside Act 1981 (as amended). This legislation makes it an offence to:

⚫ Intentionally or recklessly kill or injure these animals; and

⚫ Sell, offer for sale, possess or transport for the purpose of sale or publish advertisement to buy or sell individual reptiles.

2.2 Planning Policy

National and local policies apply protection to reptiles in the planning process. The relevant policies are detailed in Table 2.1 below.

Table 2.1 Biodiversity policy issues considered

Policy reference Relevance to the proposed scheme

National planning policy

National Planning Policy Framework (NPPF)

Section 15 of the NPPF requires planning policies and decisions to minimise impacts on, and provide net gain for, biodiversity (para 170). Plans should protect and enhance local and wider biodiversity interest, including corridors and stepping stones, designated sites, as well as biodiversity potential identified by local and national partnerships. Policies should promote opportunities for conservation, restoration and enhancement including priority habitats and species, as well as securable net gain (para 174 & 175). If significant harm to biodiversity will result, permission will be refused unless the benefits of development outweigh impacts, or exceptional reasons and compensation apply (para 175).

Local planning policy

Slough Local Development Framework Core Strategy Development Plan Document (DPD) 2006-2026 Core Policy 9 (Natural and Built Environment).

This policy outlines protection and improvement of water bodies and their margins, as well as natural habitats in general. It also refers to the protection and enhancement of biodiversity corridors between important features.

Slough Local Development Framework Site Allocations DPD Site Reference SSA25

The Site Allocation provides the Slough Borough Council (BC) with an approach to planning requirements for the site. These are to enhance and/or create new habitat along with managing public access for the benefit of the site’s wildlife.



3. Methods

3.1 Desk study and field survey scoping

High-level Phase 1 survey data4, aerial photography and satellite imagery were used to identify areas of land within the Site boundary, or within 100m of the Site boundary, that would be potentially suitable to support reptiles, following standard survey guidance

A field survey scoping exercise was subsequently undertaken in these areas to determine their potential to support reptiles. Key habitat features identified during the walkover included:

⚫ Vegetation with dense structure and suitable height (>10cm);

⚫ presence of suitable foraging habitat (e.g. proximity to standing water for grass snakes);

⚫ presence of suitable breeding sites (e.g. compost/vegetation heaps within which grass snakes could incubate eggs);

⚫ connectivity with the wider landscape;

⚫ land use/management practices (e.g. grazing at commercial stocking rates is negatively correlated to reptile presence): and

⚫ presence of hibernacula (e.g. log piles, rubble piles, embankments with mammal burrows etc).

During the desk study and field survey scoping exercise habitats not deemed suitable to support reptile populations, and subsequently scoped out of further survey, were:

⚫ Areas of hard standing, bare ground and rubble/gravel;

⚫ arable fields (due to intensive management/disturbance, application of chemicals and limited habitat along margins);

⚫ grazing fields (due to short sward height of vegetation and risk of injury to reptiles under refugia from trampling): and

⚫ vegetation lacking a dense thatch at ground level (e.g. tall ruderal vegetation growing on gravel) or part of a linear feature that is discontinuous/patchy.

3.2 Field surveys

Presence/likely absence surveys

All land within the Site or within 100m of the Site boundary that was assessed as having potential to support reptiles, and where access was permitted, was included for presence/likely absence surveys (Figure 1.1, Appendix A). A total of seven presence/likely absence survey visits were conducted between April and September 2017 (active reptile season) in accessible areas (outside the Site on adjacent land) identified as supporting habitats suitable for reptiles. Once access had been granted to the Site, in 2019, further surveys

4 See Wood (2019) Lakeside Energy From Waste: Phase 1 Habitat Survey Report



were carried out on the rifle range and receptor site in September 2019 (See Figure 1.1. for coverage of this survey).

The survey comprised the following methods, based on those recommended by Griffiths and Inns (2003) 5, and Froglife (1999) 6.:

⚫ Direct observation – recording the locations of any reptiles observed in the open (e.g. basking);

⚫ Refugia searches – inspection of existing potential refugia, especially discarded wood or old carpet, which is carefully lifted, and the area underneath searched for reptiles;

⚫ Artificial refugia – roofing felt and corrugated metal sheets measuring approximately 0.5m x 1m were placed at a density of 10-15 refugia per hectare7 of suitable habitat. Refugia were placed in excess of the density recommended by Froglife (10 per hectare), to maximise encounter rates. All refugia were numbered and the location recorded to an accuracy of, at least, ±10m. Artificial refugia were positioned in locations that provide basking opportunities (i.e. not in full shade) and left for at least two weeks to bed into the vegetation before commencing the survey visits. Survey visits recorded all reptiles observed under, on top of or next to these refugia.

The total number and density of refugia placed in each survey area is detailed at Table 3.1 (2017 surveys) and Table 3.2 (2019). The locations of the reptile refugia can be seen in Figure 2 (2017-18 surveys), Figure 3.1 (Site - Rifle Range, 2019) and Figure 3.2 (Receptor Site, 2019); these figures are presented in Appendix A.

Table 3.1 Total refugia numbers and approximate refugia densities within each survey area in 2017

Survey area Total no. of refugia Approx. refugia density (no. per hectare)

9 47 11

10 30 12



Rifle range 19 11

Receptor area 21 13

Population size class assessment Where presence/likely absence surveys established the presence of reptiles in 2017, a full population size class assessment survey was conducted in 2018 as per current guidance (Froglife 1999). Refugia numbers and densities applied in each survey area are detailed at Table 3.3.

5 Griffiths, R. and Inns, H. (2003). Surveying. In: Gent, A. H. and Gibson, S. D. eds. Herpetofauna workers’ manual. Peterborough: Joint Nature Conservation Committee, p.1-13. [Online] Available from: http://archive.jncc.gov.uk/default.aspx?page=3325 6 Froglife (1999). Froglife Advice Sheet 10: Reptile Survey: An Introduction to Planning, Conducting and Interpreting Surveys for Snake and

Lizard Conservation [Online] Available from: https://www.froglife.org/wp-content/uploads/2013/06/Reptile-survey-booklet-3mm-bleed.pdf 7 The minimum requirement is 5-10 per hectare. This has been increased to detect low density populations.

http://archive.jncc.gov.uk/default.aspx?page=3325

https://www.froglife.org/wp-content/uploads/2013/06/Reptile-survey-booklet-3mm-bleed.pdf

https://www.froglife.org/wp-content/uploads/2013/06/Reptile-survey-booklet-3mm-bleed.pdf





9 35* 11

10 30 12

*A smaller number of refugia were deployed in 2018 due to a strip of grassland being taken out of the survey programme as

no reptiles were recorded during the presence/likely absence surveys in 2017.

The classification of the relative population size for reptile species can be assessed on the basis of maximum survey counts of adults seen by observation and/or under artificial refugia, by one person in one day during the course of a 20-visit survey. Where juveniles or sub-adults are recorded, but no adults, these species will be recorded as ‘present’. The criteria for population size, based on the Froglife guidelines are outlined in Table 3.4. All survey visits were spaced out across the survey season, from April to October 2018, with a greater proportion of the visits conducted between the key months of April, May and September.

Table 3.4 Reptile population size class

Species Low population Good population Exceptional population

Adder < 5 5 – 10 > 10

Grass snake < 5 5 – 10 > 10

Slow worm < 5 5 – 20 > 20

Viviparous lizard < 5 5 – 20 > 20

Weather conditions

Reptile activity is highly dependent on the weather, as reptiles must bask in order to warm themselves and become active. April, May and September are key months for basking reptiles, as more continuous mid-summer heat means reptiles require less basking time to become active, however successful surveys may still be carried out from June to August and in October if weather conditions are suitable.

The influence of weather on reptile detection is complex and may vary depending on the target species (for example different species have different optimal body temperatures, with studies indicating that slow worms have a preferred body temperature of 14.5-28°C and grass snakes of 26-30°C (Beebee and Griffiths, 2000)), the time of year (whether early or late in the survey season), the prevailing weather conditions in the weeks prior to the survey, and the geographic location in which the survey is being carried out. In general, guidance suggests that reptile surveys should ideally be conducted on warm, dry days with intermittent sunshine; particularly after a spell of cooler or wetter weather.

Outside of these conditions weather may still be suitable for surveying (for example surveys during light summer showers interspersed with sunny spells can be very productive). Therefore, while survey visits were conducted as far as was practically possible in optimum conditions8 (see Appendix B: Reptile survey weather conditions), an element of professional judgement was applied by the most experienced surveyor leading the survey work as to what constituted suitable conditions.

8 Temperatures between 9°C and 18-20°C, no rain and little wind.



4. Results

4.1 Desk study and field survey scoping

The initial survey scoping identified habitats as having habitats such as rough grassland, scrub and waterbodies with the potential to support reptiles and as requiring presence/likely absence surveys.

4.2 Presence/likely absence survey: 2017 and 2018

The 2017 presence/likely absence surveys of land adjacent to the Site confirmed the presence of two species of reptiles (grass snake and slow worm) using suitable habitats within the Site.

Details of the refugia numbers and densities applied, and a summary of the survey results, are provided in Table 3.1 and Table 4.1. The distribution of reptile refugia and reptile records in 2017 are shown on Figure 2 and Figure 3, in Appendix A.

Table 4.1 Presence/likely absence survey results in 2017

Survey area Peak counts (adults)

Other life stages of reptile species present

Grass snake Slow worm

9 0 6 Sub-adult grass snake, and sub adult and juvenile slow worms

10 1 6 Sub-adult grass snake, and sub adult and juvenile slow worms

4.3 Population size class assessment survey: 2018

Reptiles were confirmed to be present within both survey areas in 2017, and population size class assessment surveys were therefore undertaken in 2018. This comprised an additional 20 survey visits that were undertaken between April and October 2018 in optimal weather conditions9 to identify the population size class of reptiles in each area. Details of the refugia numbers and densities applied, and a summary of the survey results, are provided in Table 3.3 and Table 4.2. The distribution of reptile refugia and reptile records in 2018 are shown at Figure 2 and Figure 3, Appendix A.

Table 4.2 Population size class assessment survey results in 2018

Survey area Peak counts (adults)10 Other life stages of reptile species

present Grass snake Slow worm

9 0 5 (6) Juvenile grass snake, and sub-adult and juvenile slow worms

9Temperatures between 9oC and 18-20oC, intermittent sunshine and little or no wind. 10 Froglife (1999) guidelines state that population size classes (refer to Table 3.4) are based upon a refugia density of 10 per hectare, and therefore the peak count of adult reptiles has been adjusted to account for the higher density of refugia deployed in the survey areas. The numbers in brackets represent the unadjusted peak counts.



Survey area Peak counts (adults)10 Other life stages of reptile species

present Grass snake Slow worm

10 0.6 (1) 12 (16) Sub-adult and juvenile slow worms

Population size class assessment

The results of the survey work undertaken in 2018 indicate that overall for survey areas 9 and 10 a ‘low’ population of grass snakes and ‘good’ population of slow worms are present.

4.4 Presence/likely absence survey: 2019

The 2019 surveys of the Site (rifle range) recorded no reptiles; two juvenile grass snakes were recorded within the proposed receptor site. No population size class surveys were undertaken at either site.

Details of the refugia numbers and densities applied, and a summary of the survey results, are provided in Table 3.2 and Table 4.3. The locations of the rifle range area of the Site and receptor site are shown on Figure 1.1. and in detail on Figure 3.1 and Figure 3.2 respectively, all in Appendix A.

Table 4.3 Presence/likely absence survey results in 2019

Survey area Peak counts (adults)

Other life stages of reptile species present


Rifle range 0 0 -

Receptor site 0 0 2 juvenile grass snakes

4.5 Deviations, constraints and limitations

The maximum temperature recorded exceeded the optimum temperature range on two out of seven dates and four out of 20 dates that reptile surveys were undertaken in 2017 and 2018 respectively. However, as reptiles were recorded during all dates in 2017 and 2018 where the temperatures exceeded the maximum, including the highest peak count of slow worms in survey area 10, this was not considered to have an impact on the results of survey work undertaken.

On two occasions in the 2019 there was some light rain during the survey. Although no reptiles were found on these dates this was consistent with the surveys undertaken in optimal conditions) and the weather conditions are not expected to have been a significant limitation on the survey.



5. Conclusions and recommendations

5.1 Reptiles population on Site

Situated to the west of the M25, the survey areas are relatively isolated due to the presence of motorways to the north and east, and urban development to the south and west, restricting the ability of reptiles to move to and from these areas from elsewhere within the landscape. Despite the relative isolation of the survey areas, in 2017 and 2018 both grass snakes and slow worms were recorded along the northern margin of Old Slade Lake in survey area 9, and within a parcel of grassland and scrub within survey area 10 (Figure 1, Appendix A). There is potential for grass snakes to move from one side of the M25 to the other via Colne Brook which flows through underpasses beneath the M4 from survey area 9 and under the M25 towards the east. However, due to the lack of other suitable connected habitat within the survey areas, the population of slow worms recorded may be restricted to the northern boundary of survey areas 9 and 10.

With respect to the Site, the closest records for reptiles were made within 75 metres (m) of the Site, in 2017 and 2018 ; a ‘good’ population of slow worm. These were recorded in Area 10 (Figure 3, Appendix A)

No reptiles were found within the Site during the 2019 surveys, therefore no further mitigation was considered necessary, and it was unnecessary to survey the receptor area further. The majority of the land in the red line boundary including the temporary construction compound and much of the access road to the A4 (See Figure 1 Appendix A) is on short grassland unlikely to support reptiles and needs no mitigation.

As reptiles have been found within 75 metres (m) of the Site (within Area 10, to the north-east of the rifle range); and given the absence of a notable boundary to dispersal of reptiles between the Site and this area and the presence of some suitable habitat within the Site, there remains the possibility that a very small population of reptiles (most likely slow worm) exists within the Site, and this was not detected during the 2019 survey period.

5.2 Recommended precautionary measures: vegetation clearance

Reptiles To minimise the risk of killing or injuring reptiles and contravening the Wildlife and Countryside Act 1981 (as amended), a programme of managed vegetation clearance under the supervision of an Ecological Clerk of Works (ECoW) should take place during the reptiles’ active period (approximately March-October inclusive) as described below:

⚫ Suitable vegetation for reptiles should be cleared between March and October to avoid impacting hibernating animals. The suitable vegetation includes scrub, tall grassland and herbaceous vegetation.

⚫ Prior to each cut the ECoW will check and supervise the dismantling (where possible) of likely reptile refugia such as log or rubble piles. The ECoW will then supervise vegetation clearance and the soil scrape.

⚫ Vegetation should be cut in two stages which can be within the same day dependant on the weather. The first cut should be down to no less than 300 millimetres (mm) using strimmers or brush cutters. Following this a second cut can take place later in the day if the weather is mild and dry. If the weather is poor (e.g. wet or cold) a period of 24 hours should be left giving reptiles time to move away.



⚫ During the second cut the vegetation should be cut to ground level then the topsoil removed using an excavator with a toothed bucket. If there is not enough time in the day to do the soil scrape after the second cut, the cuttings should be removed from the area. This will avoid reptiles moving into the cut material and being impacted when the soil scrape does occur.

⚫ Any reptiles found should be caught and moved off site into suitable habitat.

Once the soil scrape has been completed the land can be considered clear of reptiles and construction may start. As there is likely to be a pause between vegetation clearance and construction commencing the construction area must be kept clear of vegetation to prevent animals moving back into the works area. This could be done by regular checks of the site to make sure there is no regrowth and cutting back where necessary. Alternatively, a membrane, gravel layer or other barrier could be laid over the construction area. Please note that if the vegetation is allowed to regrow when reptiles are active (March to October), the land can no longer be considered cleared of reptiles and the clearance methods above including supervision by an ECoW would need to be repeated.

Nesting birds

Within the works area of the Site, vegetation to be cleared such as dense scrub has the potential to support nesting birds. Clearance works are proposed beyond the main breeding season, but there remains the potential for late broods of dependant young to be present.

Therefore all vegetation clearance work will be subject to a nest check beforehand, comprising the following steps:

⚫ Prior to commencing work in an area, the vegetation will be checked by an ECoW for active nests or evidence of these (e.g. adults bringing food).

⚫ If there are active nests these must be left undisturbed, and a buffer set up around these within which no work should take place.

⚫ The size of the buffer will depend on the species and level of disturbance but should be 5 m as a minimum.

⚫ The ECoW would need to return to the site on a second visit to confirm that all young have fledged the nest, before clearance could recommence.

5.3 Habitat creation and enhancement

Due to the proposed major construction work planned in the area it is not recommended that large scale enhancement are necessary. Expanding populations of widespread reptile species such as slow worm and grass snake around the EfW site could be at risk from impact in the near future. Lakeside EfW has some vegetated road verges on the approach road (see Replacement EfW and HTI Facilities: Landscape Proposals

drawing number TOR-227705/P004) and these could be enhanced to support existing populations.

On completion of the proposed works, grass verges will be established along the side of the roads. It is recommended these are seeded with a native species mix and allowed to grow tall, with no more than one vegetation cut a year, preferably in August/September after the grasses have set seed. The tall grasses will provide cover for reptiles, as well as providing habitat for the invertebrates on which they feed. Branches and trunks of trees and shrubs as well as rubble and excess soil produced by the works should be used to create reptile refuges; piles of materials within which reptiles can hide from predators and spend the winter.



Bibliography

Beebee, T.J.C. and Griffiths, R.A. (2000). Amphibians and Reptiles: A Natural History of the British Herpetofauna. London: Harper-Collins, New Naturalist, p. 158-159.

Froglife (1999). Froglife Advice Sheet 10: Reptile survey: an introduction to planning, conducting and

interpreting surveys for snake and lizard conservation. Halesworth: Froglife, p. 1-11.

Griffiths, R. and Inns, H. (2003). Surveying. In: Gent, A. H. and Gibson, S. D. eds. Herpetofauna workers’ manual. Peterborough: Joint Nature Conservation Committee, p.1-13.

Ministry for Housing, Communities and Local Government, (2019). National Planning Policy Framework. London: MHCLG, p 4-75

Slough Borough Council, (2008). Slough Local Development Framework Core Strategy Development Plan Document 2006-2026. Slough: SBC. p46-47

Slough Borough Council, (2010). Slough Local Development Framework Site Allocations Development Plan Document. Slough: SBC. p88

A1 © Wood Environment & Infrastructure Solutions UK Limited


Appendix A Figures

Figure 1 Survey areas 2017/2018

Figure 1.1 Survey areas 2019

Figure 2 Refugia distribution 2017/2018

Figure 3 Reptile survey results 2017 and 2018

Figure 3.1 Reptile survey results Rifle Range (2019)

Figure 3.2 Reptile survey results Receptor site at Thorney Park Golf Club (2019)

B1 © Wood Environment & Infrastructure Solutions UK Limited


Appendix B Reptile survey weather conditions

2017 presence/likely absence survey weather conditions

Survey visit Date

Weather conditions

Temperature (oC) Wind Cloud (%) Ground Rain

1 24 April 2017 13 Light 100 Damp Light before survey

2 23 May 2017 14-19 Calm 50 Dry None

3 12 June 2017 15-21 Calm 90 Dry None

4 04 July 2017 15-22 Calm 60 Dry None

5 02 August 2017 17-18 Light 100 Wet None

6 05 September 2017 18-20 Calm 100 Wet Light before survey

7 19 September 2017 17-18 Calm 30 Dry None

2018 population size class assessment survey weather conditions:

Survey visit Date

Weather conditions


1 12 April 2018 10-11 Calm 100 Wet Rain shower

2 17 April 2018 14-19 Calm 70 Damp None

3 10 May 2018 12-17 Light-moderate 35 Damp None



4 15 May 2018 15-21 Light-moderate 0 Damp None

5 23 May 2018 14-19 Light-moderate 20-100 Dry None

6 31 May 2018 17-24 Calm 100 Dry None

7 05 June 2018 15-18 Calm 100 Wet Drizzle then dry



10 04 July 2018 18 Calm 30 Dry None

11 24 July 2018 22-23 Calm 0 Dry None

12 09 August 2018 16 Light-moderate 70-100 Wet None

13 21 August 2018 17-18 Calm 50 Dry None

14 05 September 2018 14-17 Calm 80-90 Dry None

15 12 September 2018 14-17 Calm 10-80 Damp None

16 18 September 2018 17 Calm 80 Damp None

17 26 September 2018 12-18 Light 20-30 Damp None

18 11 October 2018 16-18 Calm 60-100 Damp None

19 16 October 2018 15-18 Calm 70-100 Wet None

20 23 October 2018 15-16 Calm 50-80 Dry None



2019 presence/likely absence survey weather conditions: rifle range

Survey visit Date

Weather conditions


1 05 August 2019 14 Calm 85 Dry None

2 03 September 2019 18-19 Light 50 Dry None

3 09 September 2019 15-16 Light 100 Wet Light

4 11 September 2019 20 Light 100 Wet Light

5 13 September 2019 16 Calm 0 Moist None

6 17 September 2019 17 Calm 10 Dry None

7 19 September 2019 14-16 Calm 0 Moist None

2019 presence/likely absence survey weather conditions: Receptor site at Thorney Park Golf Club

Survey visit Date

Weather conditions



2 05 September 2019 14 Calm 85 Dry None

3 09 September 2019 15-16 Calm 100 Wet Light

4 11 September 2019 20 Light 100 Wet Light

5 13 September 2019 16 Calm 0 Moist None


7 19 September 2019 16 Calm 0 Wet None

C1 © Wood Environment & Infrastructure Solutions UK Limited


Appendix C Reptile survey results

2017 presence/likely absence survey results – survey area 9:

Survey visit Date


Adult Sub-adult Juvenile Adult Sub-adult Juvenile

1 24 April 2017 0 1 0 2 1 1

2 23 May 2017 0 0 0 6 2 0

3 12 June 2017 0 1 0 5 1 0

4 04 July 2017 0 0 0 0 1 0

5 02 August 2017 0 0 0 3 4 1

6 05 September 2017 0 0 0 1 2 0

7 19 September 2017 0 0 0 4 1 0



2017 presence/likely absence survey results – survey area 10:

Survey visit Date


Adult Sub-adult Juvenile Adult Sub-

adult Juvenile

1 24 April 2017 0 0 0 2 1 1

2 23 May 2017 0 1 0 0 1 0

3 12 June 2017 0 0 0 6 1 1

4 04 July 2017 0 0 0 0 1 0

5 02 August 2017 1 0 0 4 2 1

6 05 September 2017 0 0 0 3 1 1

7 19 September 2017 0 1 0 3 1 0

2018 population size class assessment survey results – survey area 9:

Survey visit Date



adult Juvenile

1 12 April 2018 0 0 0 0 0 0

2 17 April 2018 0 0 0 0 0 0

3 10 May 2018 0 0 0 1 1 3

Survey visit Date



adult Juvenile

4 15 May 2018 0 0 0 2 0 5



5 23 May 2018 0 0 0 6 0 6

6 31 May 2018 0 0 0 3 0 10

7 05 June 2018 0 0 0 3 1 6

8 12 June 2018 0 0 0 2 0 6

9 19 June 2018 0 0 0 1 0 1

10 04 July 2018 0 0 0 0 0 1

11 24 July 2018 0 0 1 0 0 0

12 09 August 2018 0 0 0 0 0 0

13 21 August 2018 0 0 0 0 0 0

14 05 September 2018 0 0 0 0 0 2

15 12 September 2018 0 0 0 0 0 1

16 18 September 2018 0 0 0 0 0 0

17 26 September 2018 0 0 0 0 0 0

18 11 October 2018 0 0 0 0 0 0

19 16 October 2018 0 0 0 0 0 0

20 23 October 2018 0 0 0 0 0 0

2018 population size class assessment survey results – survey area 10:

Survey visit Date



1 12 April 2018 0 0 0 3 0 0

2 17 April 2018 0 0 0 7 0 0



3 10 May 2018 1 0 0 6 0 0

4 15 May 2018 1 0 0 6 1 0

5 23 May 2018 0 0 0 1 1 0

6 31 May 2018 0 0 0 16 0 4

7 05 June 2018 0 0 0 6 4 2

8 12 June 2018 0 0 0 12 1 4

9 19 June 2018 0 0 0 9 1 0

10 04 July 2018 0 0 0 3 0 0

11 24 July 2018 0 0 0 0 0 0

12 09 August 2018 0 0 0 0 0 0

13 21 August 2018 0 0 0 0 0 0

14 05 September 2018 0 0 0 0 0 0

15 12 September 2018 0 0 0 0 0 0

16 18 September 2018 0 0 0 0 0 0

17 26 September 2018 0 0 0 1 0 0

18 11 October 2018 0 0 0 0 0 1

19 16 October 2018 0 0 0 0 0 0

20 23 October 2018 0 0 0 0 0 0



2019 presence/likely absence survey results – Rifle range:

Survey visit Date



1 03 September 2019 0 0 0 0 0 0

2 05 September 2019 0 0 0 0 0 0

3 09 September 2019 0 0 0 0 0 0

4 11 September 2019 0 0 0 0 0 0

5 13 September 2019 0 0 0 0 0 0

6 17 September 2019 0 0 0 0 0 0

7 19 September 2019 0 0 0 0 0 0

2019 presence/likely absence survey results – Rifle range: Thorney Park Golf Club

Survey visit Date



1 03 September 2019 0 0 1 0 0 0

2 05 September 2019 0 0 0 0 0 0

3 09 September 2019 0 0 0 0 0 0

4 11 September 2019 0 0 0 0 0 0

5 13 September 2019 0 0 1 0 0 0

6 17 September 2019 0 0 0 0 0 0

7 19 September 2019 0 0 0 0 0 0

D1 © Wood Environment & Infrastructure Solutions UK Limited


Appendix D Scientific names of species described in this report

English name Scientific name

Adder Vipera berus

Grass snake Natrix natrix

Slow worm Anguis fragilis

Viviparous lizard Lacerta vivipara

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31

Appendix 6 New Technical Appendix J9 Otter Survey (confidential otter activity plan submitted separately)

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June 2019

Doc Ref. 41488-WOD-ZZ-XX-RP-OE-0009_S0_P01.1

Report for Lakeside Energy from Waste

Main contributors Tim Bradford

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Tim Bradford

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Wood Floor 23

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H:\Projects\41488 Lakeside Energy from Waste\G -

General\Biodiversity\Baseline reports\Appendix 9.9 Otter

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Document revisions

No. Details Date

1 First draft 26/11/2019


November 2019

Doc Ref. 41488-WOD-ZZ-XX-RP-OE-0009_S0_P01.1.

Executive summary

Purpose of this report

This report has been produced for the purpose of supporting a planning application for relocation of

Lakeside Energy from Waste, Slough, Berkshire. The report is a factual assessment of the status of otters to

be used within the Ecological Impact Assessment (EcIA) as part of the current baseline. The site location and

the area this report focusses on has been based upon the red-line boundary given in drawing number 2277

05/SK001

Methods

An initial scoping of the survey areas was undertaken to establish suitable habitat for otters and refine the

study area. The follow up survey involved four visits between September 2017 and September 2018.

Transects were walked along/around suitable habitat following best practice to identify evidence of use by

otters including resting places.

Results

Evidence of otter was found along the Colne Brook close to the site boundary. Otter spraints and tracks were

found within 20 m of the site boundary where the river passes under the A4. The closest resting place was a

laying up sites approximately 150 m north-east of the site with holts, spraints and other evidence of otters

found within the Old Slade Lake Local Wildlife Site (LWS) approximately 500 m north east of the site

boundary. No natal holts were found.


November 2019


Contents

1. Introduction 5

1.1 Background 5 1.2 Purpose of the report. 5

2. Methods 6

2.1 Otter scoping survey 6 2.2 Otter field survey 6

3. Results 8

3.1 Scoping 8 3.2 Detailed field surveys 8

Figure 3.1 Field signs recorded during the otter survey 1

Bibliography 9

Appendix A Figures


November 2019


1. Introduction

1.1 Background

Lakeside Energy from Waste (EfW) commissioned Wood to produce baseline survey

reports to support an Ecological Impact Assessment (EcIA) as part of the planning

submission for a replacement EFW facility (hereafter referred to as ‘the Site’). The Site is

located south-west of the M4/M25 motorways’ junction, and is centred approximately at Ordnance Survey National Grid reference TQ 03351 78005, immediately west of Thames

Water’s Iver South Sludge Dewatering Centre, Lakeside Road, Slough, Berkshire. The

nearest postcode is SL3 0ED.

A detailed description of the development will be included within Chapter 3 of the

Environmental Statement. The Site consists of the construction site of the new EfW facility,

a construction compound and an access road leading to the A4 (Colnbrook By-pass) which

will be used both during construction and for bringing materials on and off site during

operations.

1.2 Purpose of the report.

This otter report is intended to provide the results of baseline surveys which will be interpreted within the

Natural Heritage Chapter (Chapter 11) of the Environmental Statement.


November 2019


2. Methods

2.1 Otter scoping survey

An otter scoping assessment was undertaken to identify and map aquatic habitat and associated terrestrial

habitat suitable for use by otter. Scoping surveys covered aquatic habitat within the site plus linked water

bodies to approximately 500 m upstream and downstream. The entire Old Slade Lake LWS was also

considered due to potential impacts from construction noise. Scoping visits allowed for the identification of

features which could not be identified from Ordnance Survey (OS) maps and aerial photography to be

recorded, in addition to familiarising individuals with the survey area in advance of undertaking field surveys.

2.2 Otter field survey

Otter transects were completed during the period from September 2017 to September 2018, covering all

areas of suitable aquatic and associated terrestrial habitat in the survey area, where access was permitted.

Otter survey visits were carried out in accordance with the best practice survey guidelines as detailed in the

Biodiversity Method Statements Document. Best practice guidelines included survey methodology collated

from Monitoring the Otter Lutra lutra (2003) and Design Manual for Roads and Bridges (1999).

Survey visits were undertaken four times with at least a three-month gap between each visit. This makes sure

the survey visits were undertaken across a range of seasons, capturing seasonal changes in otter activity and

distribution.

Where access allowed, survey visits were undertaken along each water body, with surveyors searching for

signs of otter presence. Survey visits included the water body, any accessible in-channel features and

adjacent terrestrial habitat.

The otter survey involved an assessment of suitable habitat within the survey area for otter signs such as:

1. Holts and potential holt sites (including both those used for and not used for breeding);

2. Laying up sites;

3. Couches;

4. Spraints;

5. Anal jelly and tar spots;

6. Tracks and footprints; and

7. Silt, sand heaps and slides.

Otter rest sites (holts, laying up sites, and couches) are spilt into categories based on the physical structure of

the feature. These broad categories recognise the fact that features vary in regards to form and will not

always fully fit the description. The definition of otter rest sites varies depending on the source used. For the purposes of these surveys rest sites have been defined and assessment uses the following categories.

1. Couch: A couch is an above ground feature where an otter is resting in amongst vegetation. This may be

amongst long grass, reed or tall ruderal vegetation. The couch will usually comprise of an area of bedded

down material;

2. Laying up site: A sheltered feature which may have overhanging aspects such as bank, rock, vegetation and

trees. Some of the features included in this category may be considered by other professionals to be a hover,


November 2019


a hover being a feature where an otter may rest which has an overhanging structure. The term laying up site,

includes a wide range of structures and features;

3. Holt: A feature which usually has some form of tunnel and is at least partially enclosed. This includes a

range of features including those which are entirely within earth and features which comprise combination of

material (trees, vegetation and rocks) forming an enclosed feature. This can include man-made features such

as pipework and rubble; and

4. Natal Holt: A holt feature which is used to shelter or rear young.


November 2019


3. Results

3.1 Scoping

The Site contains two sections of water course. The first, a ditch running through the construction site

footprint is connected to the Horton Brook in Old Wood (west of the site boundary). The second is a stretch

of the Colne Brook where the surface water drainage will lead. The terrestrial habitat around the Colne Brook

was optimal for otters (i.e. there was suitable habitat for otters to rest), the more intensely managed habitat

along the ditch was suboptimal for otters with little opportunity for them to rest.

3.2 Detailed field surveys

Results of the survey are shown in Figure 3.1 (Appendix A). No evidence of otters was found within the red

line boundary. Immediately downstream (ca. 20 m south-west) of the red line boundary there were several

spraints found along with otter tracks. The position by the A4 road bridge indicates otters will be crossing

underneath the road at that point.

The nearest laying up point was approximately 150m upstream (north-east) on the Colne Brook. Within the

Old Slade Lake LWS , approximately 500 m north east of the site, there were two confirmed and three

suitable holts as well as confirmed and suitable laying up sites, spraints and tracks. No natal holts were

found during the survey.


November 2019


Bibliography

Chanin, P. (2003). Monitoring the Otter Lutra lutra. Conserving Natura 2000 Rivers Monitoring Series No. 10,

English Nature, Peterborough.

Highways Agency (1999). Design Manual for Roads and Bridges –Volume 10 –Section 4 Part 4 –Nature Conservation Advice in Relation to Otters. Highways Agency, London.

A1 © Wood Environment & Infrastructure Solutions UK Limited

November 2019


Appendix A Figures

Figure 3.1 Field signs recorded during the otter survey

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