volume 1, chapter 14 - airport expansion consultation · 2020. 6. 19. · 14.2.1 this section...

Heathrow Expansion PRELIMINARY ENVIRONMENTAL INFORMATION REPORT

© Heathrow Airport Limited 2019

Volume 1, Chapter 14 LAND QUALITY

PRELIMINARY ENVIRONMENTAL INFORMATION REPORT CHAPTER 14 LAND QUALITY

DOCUMENT NUMBER: INSERT HERE



CONTENTS

14. Land Quality 1

14.1 Introduction 1

14.2 Relevant legislation, policy and other important and relevant matters 2 Introduction 2 Legislation and national planning policy 2 Regional and local planning policy 7

14.3 Scoping and engagement 8 Overview 8 Scoping Opinion 8 Technical engagement 10

14.4 Scope of the assessment 13 Overview 13 Spatial scope and study area 13 Temporal scope 14 Receptors 15 Identification of potential effects 17 Effects no longer being considered 20

14.5 Embedded environmental measures 21

14.6 Methodology for baseline data gathering 31 Desk study 31 Survey work 34

14.7 Assessment methodology for PEIR 36 Assessment methodology evolution 39

14.8 Assumptions and limitations of this PEIR 40 Land contamination 40 Agricultural land quality 40 Minerals safeguarding 41

14.9 Overall baseline 42 Current baseline 42 Future baseline 51

14.10 Assessment of land quality effects 54 Phase 1: c. 2022-2026 - Land contamination 54 Phase 2: c. late 2026-2035 - Land contamination 64 Phase 3: 2036-2050 - Land contamination 65 Phase 1: c. 2022-2026 - Agricultural land quality 66 Phase 2: c. late 2026-2035 – Agricultural land quality 67 Phase 3: c. 2036-2050 – Agricultural land quality 67 Phase 1: c. 2022-2026 – Minerals safeguarding 67 Phase 2: c. late 2026-2033 – Minerals safeguarding 74 Phase 3: c. 2034-2050 – Minerals safeguarding 74

14.11 Preliminary assessment of significance 74

14.12 Assessment of cumulative effects 81 Introduction 81 Phase 1: c. 2022-2026 83 Phase 2: c. late 2026-2033 84 Phase 3: c. 2034-2050 84

14.13 Consideration of additional environmental measures or compensation 90



14.14 Next steps 90 Baseline data and assessment 90 Scoping and engagement 92

TABLES Table 14.1: Legislation relevant to land quality 3 Table 14.2: National planning policy relevant to land quality 4 Table 14.3: PINS Scoping Opinion consultation 8 Table 14.4: Receptors requiring assessment for land quality 16 Table 14.5: Potential effects on land contamination receptors scoped in for further assessment 17 Table 14.6: Potential effects on agricultural land quality receptors scoped in for further assessment 18 Table 14.7: Potential effects on minerals safeguarding receptors scoped in for further assessment 20 Table 14.8: Effects no longer considered in this PEIR 21 Table 14.9: Summary of the embedded environmental measures in the design and how these influence the land quality assessment 22 Table 14.10: Summary of the good practice environmental measures and how these influence the land quality assessment 24 Table 14.11: Data sources used to inform the land quality assessment 31 Table 14.12: Land quality survey programme 34 Table 14.13: Land quality survey work undertaken 35 Table 14.14: Assessments supporting the land contamination assessment of effects in the construction and operational phases 36 Table 14.15: Minerals safeguarding assessment methodology amendments 38 Table 14.16: Assessment methodology for the PEIR and ES 39 Table 14.17: Land contamination preliminary screening of soil data 45 Table 14.18: Land contamination preliminary screening of groundwater data 46 Table 14.19: Land contamination preliminary screening of surface water data 48 Table 14.20: Summary of significance of positive and negative effects 75 Table 14.21: Land quality CEA screening criteria 82 Table 14.22: Developments brought forward for CEA 83 Table 14.23: Phase 1 CEA of DCO Project-wide effects, and DCO Project-wide effects with ‘other developments’ unrelated to the DCO Project 85 Table 14.24: Areas of further engagement prior to ES 92 Table 14.25: Glossary of terms for land quality assessment Error! Bookmark not defined.

FIGURES

Figure 14.1 Land Quality Study Area Figure 14.2 Ground Investigation and Soil sample Locations Figure 14.3 Ground Investigation and groundwater sample Locations Figure 14.4 Surface Water Sampling Locations Figure 14.5 Schematic Conceptual Site Model - Current use Figure 14.6 Schematic Conceptual Site Model - Future use Figure 14.7 Soilscape map Figure 14.8 Provisional Agricultural Land Classification Mapping Figure 14.9 Site Specific Agricultural Land Classification Studies (Post 1988 ALC field studies) Figure 14.10 Geodiversity sites Figure 14.11 Minerals Safeguarding Sites

APPENDICES Appendix 14.1 Human Health and Controlled Waters Screening Criteria



Appendix 14.2 Updated Minerals Safeguarding Approach Appendix 14.3 Approach to Collection of Quantitative Asbestos Release Data Appendix 14.4 Assessment of Land Contamination Effects Appendix 14.5 Assessment of Minerals Safeguarding Effects


14-1 © Heathrow Airport Limited 2019

14. LAND QUALITY

14.1 Introduction

14.1.1 This chapter of the Preliminary Environment Information Report (PEIR) presents the preliminary results of the assessment of likely significant effects of the DCO Project with respect to land quality, including land contamination, agricultural land quality (including soils) and minerals safeguarding. It should be read in conjunction with the project description provided in Chapter 6: DCO Project description and the relevant parts of the following chapters:

Chapter 7: Air quality and odour - for assessment of effects on potential odour and nuisance arising from excavation of landfills

Chapter 8: Biodiversity - for assessment of effects on ecological receptors

Chapter 16: Major accidents and disasters - for assessment of effects of contamination arising from a major accident or disaster

Chapter 18: Socio-economics and employment - for assessment of effects on the socio-economic aspects of agriculture (i.e. effects on farming businesses) and socio-economic aspects of minerals (i.e. effects on minerals or aggregates businesses)

Chapter 21: Water environment - for assessment of effects on groundwater and surface water levels, flows and interactions

Chapter 23: Bibliography

Glossary of terms and list of abbreviations.

14.1.2 This chapter describes:

The legislation, planning policy and other documentation that has informed the assessment (Section 14.2: Relevant legislation, policy and other important and relevant matters)

The outcome of consultation and external engagement that has been undertaken to date, including how matters relating to land quality within the Scoping Opinion adopted by PINS on behalf of the Secretary of State on 2nd July 2018 have been addressed (Section 14.3: Scoping and engagement)

The scope of the assessment for land quality (Section 14.4: Scope of the assessment)

Embedded environmental measures relevant to land quality (Section 14.5: Embedded environmental measures)



The methods used for the baseline data gathering (Section 14.6: Methodology for baseline data gathering)

The assessment methods used for the PEIR (Section 14.7: Assessment methodology for PEIR)

The assumptions and limitations of the PEIR assessment (Section 14.8: Assumptions and limitations of this PEIR)

The overall baseline (Section 14.9: Overall baseline)

The assessment of land quality effects (Section 14.10: Assessment of effects)

A summary of significance of positive and negative land quality effects identified in the PEIR (Section 14.11: Preliminary assessment of significance).

The assessment of cumulative effects (Section 14.12: Assessment of cumulative effects)

Consideration of any additional environmental measures or compensation required (Section 14.13: Consideration of additional environmental measures or compensation)

An outline of further work to be undertaken for the Environmental Statement (ES) (Section 14.14: Next steps).

14.1.3 In-combination effects are addressed in Chapter 22: In-combination effects.

14.2 Relevant legislation, policy and other important and relevant matters

Introduction 14.2.1 This section identifies the legislation, policy and other documentation that has

informed the assessment of effects with respect to land quality. Further information on policies relevant to the EIA and their status is provided in Chapter 2: Legislative and policy overview of this PEIR.

Legislation and national planning policy 14.2.2 Table 14.1 lists the legislation relevant to the assessment of the effects on land

quality receptors.



Table 14.1: Legislation relevant to land quality

Legislation description Relevance to assessment

Part 2A of the Environmental Protection Act 1990 (Part 2A) including DEFRA’s Part 2A Contaminated Land Statutory Guidance

The Environmental Protection Act 1990 makes provision for the improved control of pollution arising from certain industrial and other processes. Part 2A of the Act provides the regulatory basis for the identification, designation and remediation of Contaminated Land.

The DCO Project could have an effect on land potentially affected by historic contamination which requires assessment to ensure it is suitable for the proposed land-use and that following completion of the DCO Project, the land cannot be determined as Contaminated Land under the Act.

Water Resources Act (1991) as amended by the Water Act (2003)

The Acts provide the definition of and regulatory controls for the protection of water resources including the quality standards expected for controlled waters.

The DCO Project could have an effect on controlled waters which requires assessment in line with the Act.

The Environment Act 1995

The Act established the Environment Agency and gave it responsibility for environmental protection of controlled waters.

The DCO Project could have an effect on controlled waters which requires assessment in line with the Act.

The Environmental Permitting (England and Wales) Regulations 2016 which includes transposing into domestic law the EU Landfill Directive (1999/31/EC) (LFD)

Regulations to manage and reduce pollution from certain industrial activities through permitting, monitor compliance with permit conditions and promote environmental standard practice in operation of the activities covered by a permit.

The DCO Project could have an effect on a number of historic and authorised landfills and waste management facilities and incudes proposed new landfills and other waste management operations which would require management under the regulations.

The Water Environment (Water Framework Directive) (England and Wales) Regulations 2017 transposing into domestic law The EU Water Framework Directive (2000/60/EC) (WFD)

The aim of the WFD is for all water bodies to achieve Good Status by 2027 (comprised of scores for Ecological Status and Chemical Status) and to ensure no deterioration from current status.

A WFD assessment is required to be undertaken for the DCO Project. A preliminary assessment is included within Chapter 21.

Environmental Damage (Prevention and Remediation) (England) Regulations 2015

Regulations implementing the EU directive on environmental liability setting out the principles for prevention and remedy of environmental damage.

Construction and operational airport activities have the potential to cause pollution and the regulations place emphasis on businesses to proactively implement pollution prevention measures so that damage to the environment does not arise.



14.2.3 Table 14.2 lists the national planning policy relevant to the assessment of the effects on land quality receptors.

Table 14.2: National planning policy relevant to land quality

Policy description Relevance to assessment

Airports National Policy Statement (ANPS), (Department for Transport, 2018)

Chapter 2: Legislative and policy overview provides an explanation of the relevance of the ANPS to the DCO Project in general terms. The ANPS is the primary basis for decision making on the DCO Project. The following paragraphs of the ANPS are of relevance to the assessment presented in the chapter in relation to land contamination:

1. Paragraph 4.54 2. Paragraph 5.110 3. Paragraph 5.116

and paragraphs 5.226 to 5.229 relevant to land instability.

Of particular note is paragraph 5.110 which in relation to existing land contamination states:

‘Risks would require consideration in accordance with the contaminated land statutory guidance as a

minimum.’ In relation to agricultural land quality and soils, the following paragraphs are relevant to the assessment:

1. Paragraph 5.108 2. Paragraph 5.109 3. Paragraph 5.115 4. Paragraph 5.118 5. Paragraph 5.126

In relation to minerals safeguarding, the following paragraphs are relevant to the assessment:

1. Paragraph 5.117 2. Paragraph 5.121 and 5.122

The ANPS establishes a requirement to undertake an assessment of any likely significant land quality effects of the DCO Project within the draft DCO limits (‘the Site’) and surrounding area. The approach to the assessment of potentially significant land quality effects is addressed in Section 14.7 of this PEIR with the outputs of the assessment presented in Section 14.10. The consideration of environmental measures including how the scheme has been designed to reduce land quality effects is addressed in Section 14.5. The approach to the land contamination assessment has been developed in line with the UK legislation (see Table 14.1). Along with the proposed land quality environmental measures (see Section 14.5), this ensures a risk-based decision-making approach around land potentially affected by contamination and the suitable for use approach set out in the UK legislation (and reflected in Paragraph 5.110 of the ANPS) is embedded into the DCO Project. This also ensures that the potential for ground instability is considered and measures to minimise risks incorporated into the design and construction of new structures as reflected in Paragraphs 5.226 to 5.229 of the ANPS. Section 3.3 of Chapter 3: DCO Project alternatives outlines the process by which the principal components of the DCO Project design were evaluated. Loss of Best and Most Versatile (BMV) agricultural land was one of the evaluation criteria used to ensure that proper consideration was given to the value of BMV agricultural land in design decision-making and where possible, poorer quality land was proposed for development of the DCO Project in preference to that of a higher quality. Table 14.10 outlines good practice environmental measures which seek to minimise




effects on soil quality and protect soils during construction. Section 14.5 outlines where mineral resources have been safeguarded as part of the DCO Project or where environmental measures have been put forward to reduce the potential effect of the DCO Project on mineral resources.

National Policy Statement for National Networks, (NN NPS, Department for Transport, 2014)

Chapter 2: Legislative and policy overview provides an explanation of the relevance of the NN NPS to the DCO Project in general terms. The following paragraphs of the NN NPS are of relevance to the assessment presented in the chapter in relation to land quality:

1. Paragraphs 5.116 to 5.119 2. Paragraphs 5.168 and 5.176 3. Paragraph 5.169 4. Paragraph 5.182 and 5.183

Of particular note is paragraph 5.168 which states

‘For developments on previously developed land, applicants should ensure they have considered the risk posed by land contamination and how it is proposed to address this’ [referencing Environment Agency Guidance CLR11]. and paragraph 5.176 which states: ‘The decision-maker should give little weight to the

loss of agricultural land in grades 3b, 4 and 5, except in areas (such as uplands) where particular agricultural practices may themselves contribute to the quality and character of the environment or the

local economy.’

The NN NPS establishes a requirement to undertake an assessment of any likely significant land quality effects of the DCO Project. The approach to the assessment of potentially significant land quality effects is addressed in Section 14.7 of this PEIR and includes reference to relevant guidance (for example CLR11 in the case of land contamination). The outputs of the assessment of likely significant effects are presented in Section 14.10. The consideration of environmental measures including how the scheme has been designed to reduce land quality effects is addressed in Section 14.5. The approach to the land contamination assessment has been developed in line with the UK guidance (see Table 14.1 and in particular CLR-11) and, along with the proposed land quality environmental measures, ensures risk-based decision making around land affected by contamination and the suitable for use approach set out in the UK legislation and reflected in Paragraph 168 of the NN NPS is embedded into the DCO Project. This also ensures that the potential for ground instability is considered and measures to minimise risks incorporated into the design and construction of new structures as reflected in Paragraphs 5.182 and 5.183 of the NN NPS Section 3.3 of Chapter 3: DCO Project alternatives outlines the process by which the principal components of the DCO Project design were evaluated. Loss of Best and Most Versatile (BMV) agricultural land was one of the evaluation criteria used to ensure that proper consideration




was given to the value of BMV agricultural land in design decision-making and where possible, poorer quality land was taken for development of the DCO Project in preference to that of a higher quality. In addition, only the loss of BMV agricultural land is considered to be significant within the PEIR/ES so as to give little weight to the loss of land in Agricultural Land Classification (ALC) grades 3b to 5 as reflected in Paragraph 176 of the NN NPS. Table 14.10 outlines good practice environmental measures which seek to minimise effects on soil quality and protect soils during construction. Section 14.5 outlines where mineral resources have been safeguarded as part of the DCO Project or where environmental measures have been put forward to reduce the effect of the DCO Project on mineral resources as reflected in Paragraphs 5.169 and 5.182 of the NN NPS.

National Planning Policy Framework, (NPPF), Ministry of Housing, Communities and Local Government, 2019)

Chapter 2: Legislative and policy overview provides an explanation of the relevance of the NPPF to the DCO Project in general terms. The following paragraphs of the NPPF are of relevance to the assessment presented in the chapter in relation to land quality:

1. Paragraphs 15.178 and 15.179 2. Paragraph 15.170 3. Paragraphs 17.203 to 17.206

and of particular note is Paragraph 17.204(d) which states that planning policies should: ‘set out policies to encourage the prior extraction of

minerals, where practicable and environmentally feasible, if it is necessary for non-mineral

development to take place’

The approach to the assessment of potentially significant land quality effects is addressed in Section 14.7 of this PEIR and includes reference to relevant legislation and guidance (including Part 2A of the Environmental Protection Act 1990 in the case of land contamination). The outputs of the assessment of likely significant effects are presented in Section 14.10. The consideration of environmental measures including how the scheme has been designed to reduce land quality effects is addressed in Section 14.5 and includes measures to prevent land and soil pollution during the construction and operational phases of the DCO Project. Table 14.10 outlines good practice environmental measures which seek to minimise effects on soil quality and protect soils during construction. Section 14.5 outlines where mineral resources have been safeguarded as part of the DCO Project or where environmental measures have been put forward to reduce the potential effect of the DCO Project on mineral resources. The approach to the minerals safeguarding assessment includes




consideration of Minerals Safeguarded Areas (MSAs) and locally and nationally important mineral resources. Environmental measures will consider the requirement for prior extraction where practicable and feasible as part of the DCO Project as reflected in Paragraph 204(d) of the NPPF.

Regional and local planning policy 14.2.4 Appendix 2.1: Regional and local planning policy and other important and

relevant matters, Volume 3 presents the full list of the regional and local planning policies relevant to the assessment of effects on land quality receptors.

14.2.5 The local planning policies from the following local planning authorities which fall within the land quality study areas (and in the case of the minerals safeguarding assessment also cover the regional area of the DCO Project or joint planning policies with neighbouring local planning authorities) have been considered:

Greater London Authority

London Borough of Hillingdon

London Borough of Hounslow

Slough Borough Council

The Royal Borough of Windsor and Maidenhead

South Bucks District Council

Spelthorne Borough Council

Surrey County Council

Buckinghamshire County Council

Central and Eastern Berkshire Authorities (joint policy covering Bracknell Forest Council, Reading Borough Council, The Royal Borough of Windsor & Maidenhead and Wokingham Borough Council).

14.2.6 Other important and relevant matters a summary of other documentation relevant to the assessment undertaken in land quality is provided within Appendix 2.1.

14.2.7 Due regard has also been given to the UK Government’s ‘A Green Future: Our 25-Year Plan to Improve the Environment’, DEFRA 2018 (25-Year Environment Plan), where relevant as set out in Appendix 2.1.



14.3 Scoping and engagement

Overview 14.3.1 This section describes the outcome of, and response to, the Scoping Opinion in

relation to the land quality assessment and also provides details of the ongoing technical engagement that has been undertaken with stakeholders and individuals. An overview of engagement undertaken can be found in Section 1.5 of Chapter 1: Introduction.

14.3.2 Engagement has taken the form of stakeholder meetings and requests for baseline information and is summarised in the following sections.

Scoping Opinion 14.3.3 A Scoping Report requesting a Scoping Opinion was submitted to the Secretary of

State, administered by the Planning Inspectorate (PINS) on behalf of the Secretary of State on 21 May 2018. The Scoping Report set out the proposed land quality assessment methodologies, outlined the baseline data collected to date and that proposed for the ES.

14.3.4 A Scoping Opinion was adopted by PINS on behalf of the Secretary of State on 2 July 2018. Table 14.3 sets out the comments received in Section 4 of the PINS Scoping Opinion (‘Aspect based scoping tables’) for land quality and how they have been addressed in this PEIR. A full list of the PINS Scoping Opinion comments and responses is provided in Appendix 5.1: Response to the Scoping Opinion, Volume 3. The information provided in the PEIR is preliminary and therefore not all the Scoping Opinion comments have been able to be addressed at this stage, however all comments will be addressed within the ES.

Table 14.3: PINS Scoping Opinion consultation

PINS ID number

Scoping Opinion comment How is this addressed?

109 Loss of non-Best and Most Versatile Land - The Inspectorate considers that the agricultural land quality assessment should focus on assessing the loss of BMV land (as defined in the National Planning Policy Framework). The Inspectorate therefore considers that an assessment of the loss of non-BMV agricultural land is not required, although such loss should be quantified within the ES.

PEIR assessment focuses on the likely effect on agricultural land, the quality of that land using the agricultural land classification (ALC) system and quantifying the permanent or temporary loss of BMV and non-BMV land as a desk-based exercise, see Section 14.10. ES will include the results of detailed ALC field surveys to quantify the temporary or permanent loss of agricultural land, its breakdown by ALC grade and the quantum of



PINS ID number


permanent or temporary losses of BMV and non BMV land.

110 Temporary loss of access to mineral deposits preventing extraction - The Scoping Report does not provide any specific information to support the request to scope this matter out. In absence of detail relating to the specific sites and the consequential impacts that may occur should their current or planned mineral extraction status change, the Inspectorate considers that temporary loss of access to mineral deposits preventing their extraction may result in significant effects and this matter cannot be scoped out from assessment in the ES.

Minerals safeguarding methodology has been updated so that temporary loss of access to mineral sites is scoped into the assessment (see Section 14.7). Assessment of the effects on minerals sites arising from the temporary loss of access as a result of the DCO Project have been considered in the PEIR and will be considered for the ES.

111 Study area - The Inspectorate recommends that interpretative reports are sectioned by local authority area in order to facilitate understanding of the potential effects at a local level.

The feasibility of presenting the ground investigation survey data and data screening outputs by local authority will be considered for the ES. Where feasible, outputs from land contamination screening will be referenced back to local authority areas to allow clarity on sites where land contamination risks have been identified which may require remediation activities to be undertaken.

112 Level of data collected to support the ES will be dependent on the availability of site access to undertake ground investigation surveys - The Applicant must ensure that sufficient baseline information has been obtained to inform an adequate assessment of effects and to demonstrate the required mitigation within the ES. Additional baseline with respect to landfill and minerals sites is provided in the local authority consultation responses (eg Surrey CC, Spelthorne BC and South Bucks DC).

Additional information provided in the local authority consultation responses has been incorporated into the DCO Project baseline (see Section 14.9). Sufficient data to characterise the baseline conditions and inform the assessment of effects is considered to be available and will be provided as part of the ES.

113 Agricultural Land Classification survey methodology - In accordance with the Natural England guidance, the list of activities should also include consideration of local climate and site data as part of the reporting process.

Agricultural Land Classification (ALC) surveys will include consideration of local climate and site data as part of the reporting process.



PINS ID number


114 Minerals safeguarding significance criteria - The Scoping Report indicates that only effects with major magnitude would be assessed as being significant. The Scoping Report does not explain why medium magnitude effects would not be significant when they include ‘permanent effects that will sterilise a significant proportion of a mineral deposit’. The ES should provide further justification to support the methodology applied in determining significance.

Minerals safeguarding methodology has been updated to include medium magnitude effects as significant in the assessment (see Section 14.7). The magnitude of effect criteria present in the Scoping Report should not have included temporary access effects. However, in response to PINS ID110, the minerals safeguarding methodology has been updated to include temporary effects and therefore the magnitude of effect criteria are now correct.

115 Bibliography - BS1075:2011+A2:2017 replaces the 2013 version of the standard and should be used to undertake the assessment

Assessment is being undertaken in line with the latest version of the standard (+A2 2017).

Technical engagement 14.3.5 Technical engagement has been ongoing with a number of prescribed and non-

prescribed consultation bodies in relation to land quality. A summary of engagement undertaken up to finalisation of this PEIR is outlined in this section.

Environment Agency 14.3.6 Engagement with the Environment Agency has been ongoing since June 2017 in

the form of meetings and document sharing. Areas of engagement have included:

Technical discussions on landfill permitting and earthworks strategy, including potential construction of river diversions and flood storage through or on historic landfill sites

Technical discussions on holistic screening criteria to be adopted in the Human Health and Controlled Waters Risk Assessments (see Appendix 14.1: Human health and controlled waters screening criteria, Volume 3)

Environmental measures including potential remediation requirements and draft Code of Construction Practice (CoCP)

Provision of desk study data from which to compile the baseline conditions presented in Section 14.9.

14.3.7 The outputs of the technical discussions have informed the approach to the assessment including the controlled waters source-pathway-receptor linkages being considered in the land contamination risk assessment (see Section 14.7)



and the environmental measures being embedded as part of the scheme (see Section 14.5).

14.3.8 In a memo dated 18 February 2019, the Environment Agency provided their broad agreement to the screening criteria being used in the holistic risk assessment methodology and also provided a number of comments and observations which have been taken into account in the risk assessment methodology presented in Appendix 14.1.

Heathrow Strategic Planning Group (HSPG) 14.3.9 Engagement with the HSPG has been ongoing since July 2017 in the form of

meetings and document sharing. Focus areas of engagement have included:

Technical discussions on holistic screening criteria to be adopted in the Human Health and Controlled Waters Risk Assessments (see Appendix 14.1)

Environmental measures including potential remediation requirements and draft CoCP

Minerals safeguarding

Provision of desk study data from which to compile the baseline conditions presented in Section 14.9.

14.3.10 The outputs of the technical discussions have informed the approach to the assessment including the human health source-pathway-receptor linkages being considered in the land contamination risk assessment (see Section 14.4) and the environmental measures being embedded as part of the scheme (see Section 14.5).

14.3.11 In addition, in emails and letters dated between 19 December 2018 and 11 January 2019 the HSPG have provided their broad agreement to the screening criteria being used in the holistic risk assessment methodology and also provided a number of comments which have been taken into account in the risk assessment methodology presented in Appendix 14.1.

14.3.12 In their Scoping Response, Surrey CC provided the following specific comment relating to a site within the land required for the DCO Project which is designated as a Preferred Area for concreting aggregate in the Surrey Minerals Local Plan Core Strategy Development Plan Document 2011 (Preferred Area G: Homers Farm, Bedfont):

‘Site E3: The mineral should be won from the site first, before any development goes ahead….’

14.3.13 The land quality team have noted this comment, and this is addressed as part of the baseline data presented in Section 14.9.



14.3.14 In addition, Surrey CC also provided the following comment relating to a site within the proposed land for the DCO Project:

‘The northern part of the Hithermoor Quarry site, which currently hosts an aggregate recycling facility and a soil remediation facility, is also identified as the preferred location for the processing of sand and gravel should extraction commence from the King George

VI reservoir, which is identified as Preferred Area K (estimated reserve of 3.24 million tonnes) in the adopted Surrey Minerals Plan (Primary Aggregates DPD).’

14.3.15 Spelthorne Borough Council also provided a similar comment during technical engagement undertaken through the HSPG as part of the waste assessment (Chapter 20: Waste).

14.3.16 The likely effects with respect to loss of existing businesses (for example the existing Hithermoor Quarry recycling facility) will be addressed in conjunction with Chapter 18. However, these comments have been noted in respect of the minerals safeguarding assessment which assesses the likely effects on Preferred Areas for aggregate minerals and this is addressed in Section 14.10.

Natural England 14.3.17 Natural England was consulted prior to issue of the Scoping Report on the

approach to the agricultural land quality assessment and no concerns were raised over the approach being adopted.

14.3.18 An update on the agricultural land quality assessment was provided to Natural England in December 2018 to outline how the Scoping Opinion responses have been addressed in this PEIR, the approach to the collection of baseline data and assessment in this PEIR and the agricultural land quality measures included within the draft CoCP.

14.3.19 Natural England’s soil specialists responded on 14 December 2018 giving their broad agreement to the approach being taken and providing a number of comments on the draft CoCP and Agricultural Land Classification (ALC) terminology which have been incorporated into this PEIR.

Other stakeholders

14.3.20 In addition to the technical engagement described in this section, engagement has been undertaken with Network Rail and various private companies operating within the land quality study area to obtain desk study data from which to compile the baseline conditions presented in Section 14.9. A full list of the organisations that have supplied desk study data is provided in Table 14.11.



14.4 Scope of the assessment

Overview 14.4.1 This section describes the spatial and temporal scope for the assessment as it

applies to land quality and outlines the receptors on which assessment has been undertaken.

14.4.2 This scope has been developed as the DCO Project has evolved and responds to feedback received to date as detailed in Section 14.3. The information presented in the PEIR is by its nature preliminary and should not be considered a ‘draft’ ES (in accordance with PINS Advice Note Seven). Further scope refinement may be required to take full account of the preferred DCO Project design and subsequent engagement.

Spatial scope and study area 14.4.3 The spatial scope of the land quality assessment covers the area of the Site,

together with the Zones of Influence (ZOIs) that have formed the basis for the study area described in this section.

Land Contamination 14.4.4 For land contamination, the spatial scope of the assessment covers the area of the

Site and a 500m ZOI extending outwards from the Site as shown on Figure 14.1, Volume 2.

14.4.5 As presented in the Scoping Report, the rationale for the study area is informed by professional judgement when considering:

The spatial extent (taking into account contaminant degradation, dilution and dispersion in the environment) at which significant land quality effects are likely to have the potential to be realised through potentially active contaminant linkages

The spatial extent from which off-site sources of contamination are likely to have the potential to present significant effects on receptors within the Site

The spatial extent from which geohazards such as compressible and collapsible ground and ground gases are likely to have the potential to present significant effects on receptors within the Site.

Agricultural land quality 14.4.6 For agricultural land quality, the spatial scope of the assessment and the study

area covers the land contained within the Site as shown in Figure 14.1.



14.4.7 As presented in the Scoping Report, the rationale for the study area is that agricultural land quality (including soils and geodiversity) is geographically discrete and not substantially influenced by changes to the surroundings. That is to say, agricultural land quality and geodiversity will only be significantly affected by changes or activities (temporary or permanent) taking place on or at the resource itself, and therefore no ZOI around the Site is required.

Minerals safeguarding 14.4.8 For minerals safeguarding, the spatial scope of the assessment and the study

area covers the land contained within the Site and a 500m ZOI extending outwards from the Site as shown in Figure 14.1.

14.4.9 As presented in the Scoping Report, the rationale for the study area is based on the spatial extent of the DCO Project under which mineral resources have the potential to be directly or indirectly affected through mineral sterilisation or extraction. The 500m ZOI has been introduced in order to identify any minerals sites which could be affected by nearby operational development, where those operations introduce a land use that could be affected by the minerals extraction.

Temporal scope 14.4.10 The DCO Project will be developed in a phased approach meaning that in some

periods and/or some locations both construction and operational activities will take place in parallel. Three phases have been identified to broadly correspond with the most prevalent activities that will arise as a result of the DCO Project.

14.4.11 A number of years have been selected for assessment within each phase, the approach for which is described in Chapter 5: Approach to the EIA. The assessment of likely significant effects has been undertaken in phases which have been developed to be broadly representative of the different phases of construction and operation of the DCO Project. The phased approach draws on assessment years in each of the phases to identify likely significant effects as described in Chapter 5.

14.4.12 As outlined in Chapter 5, in order to provide appropriate flexibility in the design of the DCO Project post grant of the DCO and at the same time maintain a rigorous EIA process, a reasonable worst-case approach has been undertaken for each aspect assessment. For the purposes of defining a reasonable worst case for land quality, the following points have been assumed for this PEIR assessment.

For the land contamination assessment, any effects identified in Phase 1 are generally expected to continue through Phase 2 although the specific location of those effects may differ during the Phases. However, given the peak construction activities occur during Phase 1, the effects in Phase 1 are



considered to be most representative of the likely significant effects of the DCO Project and the assessments for Phase 2 and 3 are therefore not repeated for this PEIR assessment. In addition, any effects identified in Phase 1 overall will be the same for each individual year throughout Phase 1

All of the loss/change effects related to land take/land cover (such as topsoil stripping, loss of agricultural land and sterilisation of minerals resources) occurs at a single point in time at the start of the Phase 1 of the DCO Project.

14.4.13 The likely significant effects at this stage of the DCO Project are being considered with regard to broad definitions of environmental change. At the time of the ES, the increased levels of information regarding construction methods and timings and a more evolved understanding of the infrastructure (including green infrastructure) integral to the DCO Project will allow subdivision (for example changes to land use between years) of the likely significant effects in each Phase where appropriate.

Receptors 14.4.14 The spatial and temporal scope of the assessment enables the identification of

receptors which may experience a change as a result of the DCO Project.

14.4.15 The receptors identified that may experience likely significant effects for land quality are outlined in Table 14.4. This includes receptors identified following incorporation of the updates to the minerals safeguarding approach with regard to the PINS Scoping Opinion (see PINS ID 114 in Table 14.3).

14.4.16 The following likely significant effects on receptors have been taken into account elsewhere in this PEIR:

Likely significant effects with respect to potential odour and nuisance arising from excavation of landfills are addressed in Chapter 7Air quality and odour

Likely significant effects on ecological receptors are addressed in Chapter 8 Biodiversity

Likely significant effects of contamination arising from a major accident or disaster are addressed in Chapter 16 Major accidents and disasters

Likely significant effects with respect to the socio-economic aspects of agriculture (i.e. effects on farming businesses) are addressed in Chapter 18 Socio economics and employment

Likely significant effects with respect to the socio-economic aspects of minerals (i.e. effects on minerals/aggregates businesses) are addressed in Chapter 18

Likely significant effects on groundwater and surface water levels, flows and interactions are addressed in Chapter 21: Water environment.



Table 14.4: Receptors requiring assessment for land quality

Receptor group Receptor included within group

Land contamination

Human health 1. Residential 2. Allotments 3. Commercial/industrial 4. Public open space 5. Land and property (including land used for

agriculture (crops and livestock), existing and future structures, utilities and infrastructure)

6. Surface water (in relation to human health) 7. Construction workers (during the construction

activities)

Controlled water receptors 1. Groundwater in superficial deposits (Principal and Secondary A Aquifers)

2. Groundwater in bedrock (Lambeth Group Secondary A Aquifer/Chalk Principal Aquifer)

3. Surface waters (i.e. reservoirs, streams, rivers, lakes and ponds).

Agricultural land quality

Best and Most Versatile (BMV) agricultural land

Agricultural land in grades 1,2 or 3a of the ALC

Soils Topsoil and sub-soil

Geodiversity sites 1. Regionally Important Geological Site (RIGS) 2. Locally Important Geological Sites (LIGS)


Aggregate minerals 1. Sites, whether currently active or inactive, which have existing, valid planning permissions for minerals extraction and which have not been exhausted by previous extraction. Also included here are rail depots which have permission for the importation of sand and gravel

2. Sites designated as preferred areas for mineral extraction in Mineral Planning Authority (MPA) local plans

3. Sites designated as safeguarded sites and areas in MPA local plans

4. Mineral deposits on undesignated sites which are not currently sterilised by other developments or land uses



14.4.17 The list of receptors will be kept under review during the EIA as more detailed information is obtained during baseline surveys and other forms of data collection by other aspects and will be reflected in the final ES.

Identification of potential effects

Land contamination 14.4.18 Potential effects on land contamination receptors that have been scoped in for

assessment are summarised in Table 14.5.

Table 14.5: Potential effects on land contamination receptors scoped in for further assessment

Receptor or receptor group Activity Effect

Construction

Controlled waters receptors (groundwater in superficial deposits and surface waters)

Construction activities located on, or adjacent to landfills and other potentially contaminated sites such as industrial/waste management facilities and fuel storage/distribution facilities

Mobilisation of contamination via numerous pathways (including groundwater, surface water and leaching from soil) resulting in contamination of controlled waters

Human health receptors (residential, allotments, commercial/industrial and public open space)

Mobilisation of contamination via numerous pathways (including groundwater, surface water, leaching from soil, migration of vapours and windblown dusts) resulting in health effects

Human health receptors (residential, commercial/industrial and land and property)

Build-up of gases in confined spaces in existing or newly constructed infrastructure on and adjacent to the land required for the DCO Project

Human health receptors (construction workers)

Exposure to contamination via direct contact, inhalation and/or ingestion of soils and dusts resulting in health effects

Human health receptors (land and property)

Damage to newly constructed infrastructure from aggressive ground conditions (such as sulphate attack on concrete) and geohazards including unstable ground conditions

Human health receptors (residential, commercial/industrial), Controlled waters receptors (groundwater in superficial deposits and surface waters)

Excavation of borrow pits which are restored using excavated materials as part of the earthworks programme

Creation of new sources of contamination which have the potential to result in contamination of controlled waters and risks to human health during construction




Controlled waters receptors (groundwater in bedrock)

Construction of piled foundations or boreholes that may extend below the base of the London Clay

Contaminant migration via the potential to introduce preferential pathways which would otherwise not be present resulting in potential contamination of controlled waters

Human health receptors (construction workers) Controlled waters receptors (groundwater in superficial deposits and surface waters)

Construction vehicle and equipment maintenance and storage of fuels/oils for construction vehicles and equipment

Accidental spillages and leaks resulting in ground contamination and risks to human health during construction

Operation

Controlled waters receptors (groundwater in superficial deposits and surface waters)

Presence of significant quantities of Artificial Ground, disturbed landfill material or excavated and re-used landfill material beneath permanent infrastructure

Generation of landfill leachate, which, if not properly managed, could accumulate and/or migrate to controlled waters

Human health receptors (land and property)

Damage to infrastructure from aggressive ground conditions and geohazards including unstable ground conditions and settlement

Human health receptors (residential, commercial/industrial and land and property)

Build-up of landfill gases in confined spaces in existing or newly constructed infrastructure on and adjacent to the development boundary

Human health receptors (commercial/industrial) Controlled waters receptors (groundwater in superficial deposits and surface waters)

Operational vehicle, aircraft and equipment maintenance and storage of fuels/oils/de-icers for operational vehicles, aircraft and equipment

Accidental spillages and leaks resulting in ground and/or controlled waters contamination

Agricultural land quality 14.4.19 Potential effects on agricultural land quality receptors that have been scoped in for


Table 14.6: Potential effects on agricultural land quality receptors scoped in for further assessment


Construction

BMV agricultural land Permanent loss of BMV agricultural land

Soils Permanent loss of topsoil and subsoil




Construction activities on land permanently taken for the DCO Project

Changes to soil structure due to inappropriate storage and/or handling of soils or due to the use of heavy machinery which causes compaction

Soil erosion due to inappropriate storage and/or construction activities

Geodiversity site (proposed Sipson Lane RIGS and proposed Bedfont Lakes LIGS)

Permanent loss of geodiversity sites (RIGS/LIGS)

BMV agricultural land Construction activities on land temporarily required for construction of permanent infrastructure

Temporary loss of, or damage to BMV agricultural land

Soils Temporary loss of topsoil and subsoil

Changes to soil structure due to inappropriate storage and/or handling of soils or due to the use of heavy machinery

Soil erosion due to inappropriate storage and/or construction activities

Geodiversity sites (proposed Sipson Lane RIGS and proposed Bedfont Lakes LIGS)

Temporary loss of, or damage to geodiversity sites (RIGS/LIGS)

Operation

The likely significant effects on agricultural land quality only occur where land is permanently taken for the DCO Project or temporarily used for construction activities. Therefore, there is no potential for significant agricultural land quality effects to occur following completion of the construction activities (i.e. in the operational phase).

Minerals safeguarding 14.4.20 Potential effects on minerals safeguarding receptors that have been scoped in for




Table 14.7: Potential effects on minerals safeguarding receptors scoped in for further assessment


Construction

Sites, whether currently active or inactive, which have existing, valid planning permissions for minerals extraction and which have not been exhausted by previous extraction. Also included here are rail depots which have permission for the importation of sand and gravel. Sites designated as preferred areas for mineral extraction in local planning authority (LPA) local plans Sites designated as safeguarded sites and areas in LPA local plans Mineral deposits on undesignated sites which are not currently sterilised by other developments or land uses

Construction activities on land temporarily or permanently taken for the DCO Project Use of borrow pits for the extraction of minerals to provide fill and aggregates to support the construction activities

Permanently prevent viable exploitation of a resource (through sterilisation or adjacent development) that is of a high significance, regionally or nationally Significant loss of a resource (through extraction as part of the DCO Project) that cannot be accommodated by alternative sites at a local or regional level Viability of the operation of an ongoing mineral extraction site is clearly and demonstrably reduced Temporary sterilisation of a significant proportion of a mineral deposit (excluding those under ongoing extraction), but which would be expected to be reversed in the short to medium term Temporary reversal of previous sterilisation allowing access to unworked minerals for a limited period prior to the new development being constructed

Operation

The likely significant effects for minerals safeguarding only occur where land is temporarily or permanently taken for the DCO Project, or where the DCO Project introduces neighbouring land uses in the construction phase which are incompatible with minerals extraction on adjoining land. Therefore, the potential for significant mineral safeguarding effects to occur following completion of the construction activities (i.e. in the operational phase) has been assessed in the construction phase.

Effects no longer being considered 14.4.21 The following effects have been scoped out of the assessment for the reasons

summarised in Table 14.8.



Table 14.8: Effects no longer considered in this PEIR

Receptor Activity Effect Justification

Non-BMV agricultural land

Construction activities on land permanently taken for the DCO Project or on land temporarily required for construction of permanent infrastructure

Permanent or temporary loss of, or damage to non-BMV agricultural land

As agreed in the PINS Scoping Opinion (noting that in line with the Scoping Opinion, the area of non-BMV land lost to the development will still be quantified in the ES) and agreed with Natural England during engagement on approach to the assessment

14.5 Embedded environmental measures

14.5.1 The DCO Project will consider a number of environmental measures to avoid or minimise likely significant effects. This approach is described in Chapter 5 Approach to the EIA. Some of these environmental measures have been embedded into the DCO Project design. Those embedded environmental measures that influence the assessment of land quality are set out in Table 14.9.

14.5.2 Good practice environmental measures would occur with or without input from the EIA feeding into the design process. They include actions that would be undertaken to meet other existing legislative requirements, or that are considered to be standard practices. Those good practice environmental measures that influence the assessment of land quality are set out in Table 14.10.



Table 14.9: Summary of the embedded environmental measures in the design and how these influence the land quality assessment

Receptor Changes and effects Embedded measures and influence on assessment Land contamination

Human Health (adjacent site users, residential, commercial/industrial)

Mobilisation of contamination via numerous pathways (including groundwater, surface water, leaching from soil, migration of vapours and windblown dusts) resulting in health effects.

The scheme layout will be optimised to ensure that where feasible: 1. Excavation of previously existing landfill waste is minimised through

in-situ ground improvement and piling rather than bulk excavation and granular replacement.

2. Soil treatment centre, if required, is located away from off-site receptors.

3. Haulage routes, where practicable, are kept distant from off-site receptors.

Human Health (adjacent site users, residential, commercial/industrial, land and property)

Build-up of gases in confined spaces in existing or newly constructed infrastructure. Damage to newly constructed infrastructure from aggressive ground conditions (such as sulphate attack on concrete) and geohazards including unstable ground conditions.

Within areas of known or suspected contamination, buried services will be designed to reduce ingress of mobile and aggressive contaminants. Clean or lined service corridors will be installed to provide a suitable barrier for ground gas. Vapour protection will be incorporated into the design of new structures (such as basements or commercial properties) to provide protection against potential vapour intrusion. Foundation design and construction methodology will account for geohazards and ground instability on new infrastructure and impact of construction on existing infrastructure.

Human Health (construction workers and adjacent land users)

Mobilisation of contaminants through stockpiling materials and material reuse resulting in ground contamination and risks to Human Health during construction.

A draft Materials Management Plan (MMP) will be prepared for engagement with stakeholders that outlines how excavated non-waste materials will be reused, where practicable and feasible, during the construction earthworks. The MMP will document the proposed chemical and geotechnical reuse screening criteria and material flows onsite, including how those material flows will be documented and verified. The draft MMP will be submitted as part of the application for development consent.



Receptor Changes and effects Embedded measures and influence on assessment Controlled Waters (surface water and superficial deposits)

Mobilisation of contamination resulting from the inappropriate re-use of contaminated soils/materials during construction phase

A draft MMP will be prepared for engagement with stakeholders that outlines how excavated non-waste materials will be reused, where practicable and feasible, during the construction earthworks. The MMP will document the proposed chemical and geotechnical reuse screening criteria and material flows onsite, including how those material flows will be documented and verified. The draft MMP will be submitted as part of the application for development consent.

Controlled Waters (surface water and superficial deposits)

Mobilisation of contamination via numerous pathways (including groundwater, surface water and leaching from soil) resulting in controlled waters effects.

The scheme layout will be optimised to ensure that where feasible: Excavation of previously existing landfill waste is minimised through in-situ ground improvement and piling rather than bulk excavation and granular replacement.

Soil treatment centre, if required, is located away from surface water receptors.

Haulage routes, where practicable, are kept distant from surface water receptors.


Accidental spillages and leaks resulting in ground contamination and risks to controlled waters

The scheme layout will be optimised to ensure that: New fuel offloading and storage facilities are kept distant from surface water receptors.

Best practice containment measures embedded into design of fuel offloading and storage facilities

Controlled Waters (bedrock)

Creation of preferential pathways for contaminant migration during installation of non-potable water or thermal energy supply boreholes through base of London Clay into Chalk Aquifer

Where non-potable water supply or thermal energy supply boreholes will be installed into the Chalk Aquifer, they will be located away from land affected by contamination (for example outside of known landfill sites) and installed using best practice techniques (for example use of environmental seals during drilling and installation of secure headworks).



Receptor Changes and effects Embedded measures and influence on assessment Agricultural land quality

BMV agricultural land The development of agricultural land will be necessary and high-quality agricultural land will be lost.

Section 3.3: The Evaluation Process of Chapter 3: DCO Project alternatives outlines the process by which the principal components of the DCO Project design were evaluated. Loss of BMV agricultural land was one of the evaluation criteria used to ensure that proper consideration was given to the value of BMV agricultural land in design decision-making and where possible, poorer quality land was proposed for development of the DCO Project in preference to that of a higher quality

Minerals Safeguarding

Aggregate minerals The development has the potential to sterilise mineral resource and place pressure on local and regional mineral resources

Construction and Earthworks Strategies will be prepared and implemented that will seek to maximise the reuse of excavated clean mineral resources from within the Site and, where feasible and practical, prior extraction of mineral resources from safeguarded areas or those areas exposed by demolition of existing infrastructure will be undertaken.

Table 14.10: Summary of the good practice environmental measures and how these influence the land quality assessment

Receptor Changes and effects Good practice measures and influence on assessment

Land Contamination Human Health (construction workers and adjacent land users)

Risk of encountering unexploded ordnance during excavation and construction works

In areas with a moderate UXO hazard level, and above, clearance certification for borehole or pile locations will be carried out. Where deep excavations are required, and practical feasibility allows, investigation by non-intrusive geophysical methods will be undertaken. In this case, excavations will be supervised by an explosive ordnance clearance (EOC) operative Site induction process, toolbox talks and appropriate training



Receptor Changes and effects Good practice measures and influence on assessment Preparation of an emergency response plan in accordance with ‘Unexploded ordnance, A guide for the construction industry CIRIA C681


Mobilisation of contamination via numerous pathways (including migration of vapours and windblown dusts (resulting in health effects)

Dust, air pollution, plant-related emissions and odour will be managed in accordance with best practicable means at the time of implementation. Management plans will be used to document the approach to managing construction related dust and odour, focusing in particular on the risks arising from the excavation of the historic and authorised landfill sites beneath the construction area, the excavation of new borrow pits to extract aggregate minerals and the infilling of new landfills with waste materials generated from the earthworks (including landfill material). Demolition activities will include prior hazardous materials surveys, stripping of interiors, and adoption of measures to limit dust generation


Build-up of gases and vapours in confined spaces in existing or newly constructed infrastructure on the Site.

In the event of identification of ground gas issues during ground investigation, additional monitoring will be carried out if appropriate and, where relevant, ground gas protection measures will be provided. Any construction work proposed in locations where confined spaces may occur will be subject to HSE guidance on confined space working.


Exposure to contamination via direct contact, inhalation and/or ingestion of soils and dusts resulting in health effects.

Adherence to risk assessments and method statements (RAMS) including use of Personal Protection Equipment (PPE) and Respiratory Protective Equipment (RPE) by construction workers throughout the DCO Project lifecycle.




Accidental spillages and leaks resulting in ground contamination and risks to Human Health during construction


Mobilisation of unexpected contamination identified during construction works

Management of land contamination in line with UK statutory guidance, CLR-11. An unexpected contaminated land protocol will be produced to be implemented if contamination over and above that identified during ground investigation is encountered during construction (where routine monitoring for contamination, for example odours, unusual staining, oily or tarry and fibrous materials will be undertaken). In the event such contamination is suspected, works in the immediate area will be made safe and secure. A contaminated land specialist will inspect the Site and advise on further action, where necessary, including risk assessment to determine if further remediation is required.


Mobilisation of contaminants through stockpiling materials and material reuse resulting in ground contamination and risks to Human Health during construction.

Pre-classification testing of soils will be carried out prior to reuse of site won materials. Imported fill must meet soil and leachate acceptance criteria. Stockpiles will be placed on hardstanding or impermeable lining to prevent leaching to ground, with geotextiles used as necessary to shield stockpiles. Stockpiles to be left for more than three months will be seeded. Dust suppression measures will be utilised (covering, fencing, watering). A draft Materials Management Plan (MMP) will be prepared for engagement with stakeholders that outlines how excavated non-waste materials will be reused, where practicable and feasible, during the construction earthworks. The MMP will document the proposed chemical and geotechnical reuse screening criteria and material flows onsite, including how those material flows will be documented and



Receptor Changes and effects Good practice measures and influence on assessment verified. The draft MMP will be submitted as part of the application for development consent


Exposure to asbestos via direct contact, inhalation and/or ingestion of soils, including migration of and windblown dusts resulting from disturbance of asbestos in soils during excavations

Construction works will comply with the requirements of the Control of Asbestos Regulations 2012 (CAR-2012), the approved code of practice (ACoP) ‘Managing and working with asbestos’ and the HSE approved CL:AIRE guidance document ‘Interpretation for Managing and working with Asbestos in Soil and Construction and Demolition Materials (CAR-SOILTM)’. The potential for Asbestos Containing Materials (ACM) to be present in buildings/materials which will be demolished/dismantled as part of the construction works will be assessed through pre-construction hazardous materials surveys and, where identified, will be removed by licenced contractors under appropriate controls and Duty of Care in line with CAR-2012 and the ACoP. Where ground investigation works identify the presence of asbestos in soils, a review of the control measures for the management of construction works in line with CAR-2012 and its interpretation for soil within CAR-SOILTM will be undertaken and, where appropriate, additional monitoring and control measures will be implemented to reduce the risks from asbestos in soils (for example additional dust suppression, real-time air monitoring, changes to working times etc).

Human Health (residential, commercial/industrial and land and property)

Build-up of gases in confined spaces in existing or newly constructed infrastructure on the Site.

In the event of ground gas issues identified by the ground gas investigation, appropriate monitoring will be carried out and, where relevant, ground gas protection measures will be provided. Implementation of a gas and vapour monitoring strategy in line with relevant guidance. Any construction work proposed in locations where confined spaces may occur will be subject to HSE guidance on confined space working.




Human Health (residential, commercial/industrial and land and property)

Migration of contaminants along existing and newly installed service routes.

Removal or isolation of redundant services to prevent contaminant migration pathways.



Best practice containment measures embedded into siting and operation of fuel offloading and storage facilities and maintenance activities during construction eg use of hardstanding areas, bunded storage tanks and spill kits


Mobilisation of contamination via numerous pathways (including leaching from stockpiled soils)

Best practice containment measures embedded into stockpile management eg siting on impermeable surfacing, use of stockpile covers to prevent rainwater infiltration, bunding of stockpiles


Mobilisation of unexpected contamination identified during construction works

An unexpected contaminated land protocol will be produced Management of land contamination in line with UK statutory guidance, CLR-11


Mobilisation of contamination resulting from the inappropriate re-use of contaminated soils/materials during construction phase

Ground investigation to identify existing contamination nature and extent. A draft Materials Management Plan (MMP) will be prepared for engagement with stakeholders that outlines how excavated non-waste materials will be reused, where practicable and feasible, during the construction earthworks. The MMP will document the proposed chemical and geotechnical reuse screening criteria and material flows onsite, including how those material flows will be documented and verified. The draft MMP will be submitted as part of the application for development consent.



Good practice containment measures embedded into operation of fuel offloading and storage facilities and maintenance activities during operation.




Agricultural land quality Soils During development topsoils may

become buried under sub-soils or topsoils may be sterilised by development. Development may also sterilise sub-soils. This will have an adverse effect on the soil resource.

The following measures will be implemented during construction: Topsoils will be removed from areas where it is likely to be affected by development and, where possible, will be reused on site (for example within landscaping schemes/green space areas). The same applies to subsoils (although as they are less valuable than topsoil, reuses may be for restoring landfills/spoil tips etc). Where there is surplus topsoils, the contractors will be required to identify ways to use surplus for suitable landscape schemes elsewhere rather than it being sent to landfill (form example through local community or allotment schemes, if practicable). The same applies to subsoils although there is likely to be lower demand for these soils.

Inappropriate storage and/or handling of soils during construction may degrade soil structure, as may the use of heavy machinery. Soil erosion may take place on exposed sandy soils if left exposed to the elements and if being driven on by plant/machinery.

The following measures will be implemented during construction: Topsoil and subsoil will be stripped separately, where possible in dry weather. Soils should not be stripped/stored during or after heavy rainfall or if the soil is already saturated with water. Topsoil and subsoil will be stored separately using a methodology that will be defined with reference to best practice. (BS 3882:2015 and BS 86001:2013). Where soils are exposed, particularly on slopes, they will be covered with suitable barrier material (for example tarpaulin), to prevent erosion and gullying due to the effects of wind and rain. The use of plant and machinery on soils potentially vulnerable to erosion will be minimised. Outside areas of excavation, soil compaction will be minimised by a combination of temporary tracks, low ground pressure vehicles and low axle loads and by limiting the use of machinery in wet weather. Reinstated soils/natural soils over which construction vehicles have travelled will be surveyed to determine whether there is a need for soil ripping/loosening of soils to reduce compaction or for vegetation to be established.




Soils Some construction activities may damage the drainage of adjacent land.

A pre-construction survey of existing land drainage will be carried out to identify any drainage modification required to avoid adversely affecting the drainage of adjacent agricultural or other land (for example drainage ditches are not blocked).

Minerals Safeguarding Aggregate minerals The development has the potential to

sterilise mineral resource and place pressure on local and regional mineral resources

Construction and Earthworks Strategies will be prepared and implemented that will seek to maximise the reuse of excavated clean mineral resources from within the Site and, where feasible and practical, prior extraction of mineral resources from safeguarded areas or those areas exposed by demolition of existing infrastructure will be undertaken.



14.6 Methodology for baseline data gathering

14.6.1 Baseline data collection has been undertaken to obtain information over the study areas described in Section 14.4. This section provides the approach to collecting baseline data.

14.6.2 Baseline data collected through desk studies and site surveys has been obtained in line with the requirements and guidance set out in Section 14.2.

Desk study 14.6.3 A summary of the organisations that have supplied data, together with the nature

of that data is outlined in Table 14.11.

Table 14.11: Data sources used to inform the land quality assessment

Organisation Data provided Data time period Date received

Gov.uk open data Rivers shapefile Source Protection Zones (SPZs) Historic and Authorised landfills shapefiles Environmental Pollution incidents (database) Consented discharge data LiDAR topographic data Provisional ALC and detailed (Post 1988) ALC data

Various Accessed online in 2017 / 2018

Environment Agency Groundwater level and quality data SPZs Historic and Authorised landfills data Groundwater vulnerability maps Pollution incident details

Various Accessed online 2017 / 2018

Magic.gov.uk website Designated sites Soilscape Aquifer designations and groundwater vulnerability Provisional ALC, detailed (Post 1988) ALC and geological Sites of Special Scientific Interest (SSSIs) information.

Various Accessed online January 2018

Cranfield Soil and Agrifood Institute

Soilscape mapping data Various Accessed online January 2019




Ordnance Survey 1:50,000 and 1:25,000 mapping 2018 Accessed online January 2018

British Geological Survey

On-line Geoindex 1:50,000 digital geology Borehole Record Viewer (offers access to the National Geoscience Data Centre collection of onshore scanned boreholes, shafts and well records)

Various Accessed online 2017 / 2018

Heathrow Airport Limited

Historic site investigation reports for Heathrow and surrounding developments/land parcels Operational site activities information Aerial drone photography

Various from 1993-2004

Reports provided 2017 / 2018

Slough Borough Council London Borough of Hounslow Spelthorne Borough Council South Bucks District Council Buckinghamshire County Council

Environmental site register data Contaminated land register data Landfills data

2017 / 2018 Responses to data requests in 2017/2018

Operators/Permit Holders of Authorised Landfills (Grundons, SITA Ltd, BA Ltd)

Landfill and environmental permit data

Various Responses to data requests in 2017/2018

Landmark Information Group

1:10,000 and 1:50,000 historical mapping Historic and current aerial photography and mapping Environmental data (Envirocheck® Report)

Various Landmark Envirocheck® Reports obtained in 2017 and 2018

Zetica Limited Unexploded Ordnance (UXO) Desk Study Risk Assessment

2017/2018 2017/2018

National Soils Research Institute data

Soil descriptions and characteristics

Various Accessed online January 2018

London Geopartnership

Information on geological SSSIs, Regionally Important Geological Sites (RIGS) and Local Important

Various Accessed online January 2018 and January 2019




Geological Sites (LIGS) within London

Greenspace Information Centre for Greater London (GiGL)

Non-statutory geological sites Various Accessed online March 2019

Buckinghamshire County Council London Borough of Hillingdon London Borough of Hounslow Slough Borough Council Surrey County Council The Royal Borough of Windsor and Maidenhead Council Greater London Authority

On-line planning portal data on existing and former mineral extraction sites Local mineral planning policies in existing and emerging development plans

Various Accessed online 2017 / 2018 / 2019

South East England Aggregates Working Party London Aggregates Working Party Greater London Authority London Borough of Hillingdon Buckinghamshire County Council Surrey County Council Joint Central and Eastern Berkshire partnership

South East Aggregates Monitoring Report 2014 & 2015, (South East England Aggregates Working Party), (SEEAWP 16/03) (September 2016) Local Aggregates Assessment for London 2018 (July 2018) (Greater London Authority for the London Boroughs) London Borough of Hillingdon Local Aggregates Assessment Update Report (October 2017) (Jacobs) Buckinghamshire County Council Local Aggregates Assessment 2017 (October 2018) Surrey County Council Local Aggregate Assessment (December 2017) Central and Eastern Berkshire Authorities Joint Minerals and Waste Plan Local Aggregates Assessment (November 2017)

Various Accessed online 2017 / 2018 / 2019




Network Rail Ground investigation data for Western Rail Link to Heathrow (WRLtH)

Various Response to data request in 2017/2018

Total (UK) Limited Historic site investigation and borehole data for existing Colnbrook Rail Terminal (fuel offloading for Heathrow)

Various Response to data request in 2017

Grundons Limited Historic borehole and environmental analysis data for Lakeside Energy from Waste plant


Ingerbourne Valley Ltd

Hydrogeological impact assessment and environmental data for Harmondsworth quarry


Survey work 14.6.4 A programme of land contamination and ALC surveys commenced within the

study area in 2017 and is currently ongoing.

14.6.5 The methodologies for the land contamination and ALC surveys are based on the relevant technical guidance documents set out in Section 14.2.

14.6.6 Table 14.12 provides further information on the survey programme and Table 14.13 shows the dates of survey work completed to date and planned future surveys.

Table 14.12: Land quality survey programme

Survey type Primary guidance Notes

Land contamination

Ground investigation CLR-11 (Environment Agency, 2004) BS1075:2011+A2:2017 BS5930:2015 BSEN1997-2:2007 Eurocode 7

This survey relates to collection of data to support the determination of the nature and extent of contamination which may be present in soil, groundwater and soil vapour (including bulk ground gases).

Surface water sampling programme

CLR-11 (Environment Agency, 2004) BS1075:2011+A2:2017 BS5930:2015

This survey relates to collection of data from surface water features within the study area to determine the nature and extent of contamination which may be present in surface water.




Survey type Primary guidance Notes

ALC surveys Natural England 2018 and MAFF 1988

This survey relates to collection of detailed ALC data for land which is currently in agricultural use1 and not covered by an existing detailed ALC survey carried out in line with the MAFF 1988 guidance. ALC surveys are being undertaken using the methodology outlined in the Natural England 2018 guidance.

Table 14.13: Land quality survey work undertaken

Survey type Surveys completed Dates of future surveys

Land Contamination

Ground Investigation Surveys (including groundwater and ground gas/vapour monitoring)

A plan showing the ground investigation and soil sampling locations is included as Figures 14.2 A plan showing the ground investigation and groundwater sampling locations is included as Figures 14.3 Ground investigation have been ongoing since September 2017 comprising packages of borehole drilling followed by up to 12 rounds of monthly groundwater and 12 rounds of fortnightly in-situ ground gas sampling for each package

Ongoing

Surface Water Sampling Programme

A plan showing the surface water sampling locations is included as Figure 14.4 14 no. rounds of surface water monitoring have been undertaken on a monthly basis between December 2017 and January 2019.

Ongoing


Detailed (Post 1988) ALC surveys

The detailed ALC survey locations are included on Figure 14.9

Ongoing

1 This is land classified as arable or grassland through land use mapping. The following land uses are excluded from the ALC survey: surface water bodies, woodland, un-restored or working quarries, hardstanding, buildings and amenity grassland (for example parks and recreation grounds).



14.7 Assessment methodology for PEIR

Introduction 14.7.1 The generic project-wide approach to the assessment methodology is set out in

Chapter 5 Approach to the EIA. This has informed the approach used in this land quality assessment.

14.7.2 In addition, the assessment of effects on land quality receptors during the construction phase will draw on elements of the plans and strategies that will be developed to support the construction phase including the draft CoCP which outlines measures for pollution prevention, protection of soil and mineral resources and management of land affected by contamination.

Land contamination 14.7.3 In line with the methodology presented in the Scoping Report, the land

contamination assessment will be undertaken on a source-pathway-receptor linkage basis supported by the qualitative and quantitative analysis detailed in Table 14.14.

14.7.4 Where quantitative assessment has been undertaken, the detailed approach including the proposed human health and controlled waters screening criteria is outlined in Appendix 14.1.

14.7.5 The supporting assessments will take into account the relevant documents set out in Section 14.2.

Table 14.14: Assessments supporting the land contamination assessment of effects in the construction and operational phases

Assessment Description

Geo-Environmental Desk Study

The desk study summarises the existing geo-environmental information obtained to support the land contamination assessment and has established the existing baseline conditions of the study area. The output from the desk study is a preliminary assessment of the potential land contamination risks to be considered in the EIA for the DCO Project including a Conceptual Site Model (CSM) for the current use of the study area. The desk study represents the Preliminary Risk Assessment stage of the CLR-11 process.

Generic Quantitative risk assessment

As detailed in Appendix 14.4: Assessment of land contamination effects the assessment for land contamination is being undertaken principally by reviewing potential changes in the CSM and SPR-linkages.



Assessment Description

The Generic Quantitative Risk Assessment (GQRA) is a preliminary assessment which provides quantitative screening of the available ground investigation data on soil and water quality and presence of ground gas and vapour in order to inform this approach. The GQRA supports a preliminary assessment of the potential risks to controlled waters and human health receptors arising from the presence of contamination in soil, groundwater, surface water or soil vapour (including bulk ground gases) based on the proposed use of the land required for the DCO Project including consideration of updated conceptual site models (CSMs). This preliminary assessment draws on information from the geo-environmental desk study and the ongoing ground investigation to present an overall picture of potential land contamination risks and identify those areas of the Site or those contaminants which require further detailed assessment in line with the staged approach to land contamination in CLR-11. The overall approach to the human health and controlled waters risk assessment is unchanged from that presented in the Scoping Report. The approach to the quantitative assessment including the holistic human health and controlled waters screening criteria is outlined in Appendix 14.1.

Agricultural land quality 14.7.6 The methodology for the assessment of likely significant effects on agricultural

land quality remains unchanged since the production of the Scoping Report and is based on the extent of BMV agricultural land, soils and geodiversity sites that might be affected by the development and whether those effects would be permanent or temporary.

14.7.7 The evaluation of significance for agricultural land quality has been undertaken using professional judgement, drawing upon information about the area of BMV agricultural land (defined as Grade 1, 2 and 3a of the ALC) which might be lost or damaged together with contextual data about BMV land within the study area.

14.7.8 The ANPS (Paragraphs 5.118 and 5.126) requires effects on soils or soil resources to be minimised. In addition, the NPPF (Paragraph 15.70 (a)), NN NPS (Paragraph 5.179) and Natural England 2018 guidance seek to protect and enhance soils as a resource. Ensuring healthier soils is also recognised in the UK Government 25 Year Environment Plan (Defra, 2018). Consequently, soils are assessed to be of sufficient value on their own that an effect on them could be significant. The evaluation of significance for soils will be undertaken using professional judgement, drawing upon information about the nature and extent of the soil resources present.

14.7.9 The ANPS (Paragraph 5.84) and NN NPS (Paragraph 5.20) require geological conservation interests to be assessed. In addition, Paragraph 15.170 (a) of the



NPPF states that in relation to protection of sites of geological value, protection should be:

‘in a manner commensurate with their statutory status or identified quality in the development plan’.

14.7.10 For this reason, and in the absence of any international or national geodiversity sites in the Study area, only RIGS and LIGS are assessed to be of sufficient value that an effect on them could be significant in terms of geodiversity.

14.7.11 The evaluation of significance for geodiversity sites has been undertaken using professional judgement, drawing upon information about the value of the geodiversity feature which might be lost (that is to say the reason for its designation and the extent to which there are other examples of the designated geodiversity features within the vicinity of the application).

14.7.12 An informed judgement will then be made as to whether an agricultural land quality, soil or geodiversity effect is either ‘significant’ or ‘not significant’.


14.7.13 The methodology for the minerals safeguarding assessment has been amended since the production of the Scoping Report. The reasons for the amendments are in response to issues raised during the Scoping Opinion and are described in detail in Table 14.15.

Table 14.15: Minerals safeguarding assessment methodology amendments

Scoping Report sections

Scoping Report methodology

PEIR sections

PEIR methodology

Justification for change

Paragraph 14.9.55 Table 14.11 Appendix 14.5 Minerals Safeguarding Assessment Approach

The methodology in the Scoping Report proposed that only effects with major magnitude would be assessed as being significant for the purposes of the EIA. The Scoping Report also proposed to scope out of the assessment temporary loss of access to aggregate minerals.

Appendix 14.2: Updated minerals safeguarding assessment approach, Volume 3.

The updated methodology proposes that both major and moderate magnitude effects be assessed as being ‘significant’ in EIA terms.

Methodology updated to reflect comments received from PINS (see Table 14.3)

14.7.14 An updated version of the approach to minerals safeguarding is included as Appendix 14.2.



14.7.15 It is noted that there is no established methodology for assessing the environmental effects of a development on mineral safeguarding. The proposed methodology presented in Appendix 14.2 has therefore been developed based on the documents set out in Section 14.2 and professional experience.

Assessment methodology evolution 14.7.16 At this stage of the EIA, the DCO Project is still under development and is the

subject of statutory consultation. The likely significant environmental effects are presented at this preliminary stage. Further, more detailed assessment work will be undertaken between PEIR and preparation of the ES on the final DCO Project.

14.7.17 The methodology for the ES may therefore develop further from that used for the PEIR and described in this section. Anticipated changes in the assessment methodology are s

14.7.18 Summarised in Table 14.16, with reasons for any likely amendments detailed.

Table 14.16: Assessment methodology for the PEIR and ES

Effect Assessment methodology used for this PEIR

Assessment methodology to be used for the ES

Land Contamination Risks to Human Health and Controlled Waters

As detailed in Appendix 14.4 the assessment for land contamination is being undertaken principally by reviewing potential changes in the CSM and SPR-linkages. By comparing the difference in risk of each SPR-linkage at baseline to those at construction and at operational stages, this provides a way of assessing both the adverse and beneficial effects during construction and the operational period. Quantitative screening of the available ground investigation data on soil and water quality and presence of ground gas and vapour has been carried out as detailed in Appendix 14.1 in order to inform the assessment.

The assessment methodology presented in this PEIR will be used for the ES. A more robust dataset will also be available for quantitative analysis following completion of ground investigation works at the Site. The ground investigation results will provide further data on soil and water quality and presence of ground gas and vapour which will inform the assessment.

Agricultural Land Quality Loss of BMV agricultural Land

Incomplete coverage of detailed ALC survey data (surveys carried out in line with the MAFF 1988 and Natural England 2018 guidance) has meant that the assessment at PEIR is largely based on existing ALC data, namely:

Additional detailed ALC surveys on land currently in agricultural use within the study area should be available for the ES. This will enable a more accurate baseline to be established and the identification of BMV agricultural land.



Effect Assessment methodology used for this PEIR

Assessment methodology to be used for the ES

1. Provisional ALC mapping data; and 2. A limited number of, site specific, detailed ALC surveys. This may result in an overestimate of the quantum of permanent loss of agricultural BMV land, principally where sites which have a Provisional Grade 3 ALC (which would be counted as BMV land) are found, through the detailed (Post 1988) assessment process, to have a Grade 3b ALC (which would be non-BMV land)

Minerals Safeguarding Sterilisation of mineral resources

The assessment is being undertaken in line with Appendix 14.2.

The assessment methodology presented in this PEIR will be used for the ES.

14.8 Assumptions and limitations of this PEIR

Land contamination 14.8.1 At the time of writing the PEIR, ground investigation surveys from across the study

area are ongoing and there is only a limited dataset available for analysis. The PEIR assessment, where appropriate, uses the quantitative data which is currently available to support the assessment of land contamination effects, and a full assessment of the available quantitative land contamination data will be used in the ES.

14.8.2 The extent of the ground investigation surveys will also be dependent on the availability of site access. Significant efforts are currently being made to access as wide an area as is possible within the Site. However, where site access is not available (and therefore quantitative land contamination data will not be available), the land contamination assessment will be undertaken in the ES using the available desk study data.

Agricultural land quality 14.8.3 Provisional ALC mapping, although appropriate for strategic use, is not sufficiently

accurate for use in assessment of individual developments (Natural England, 2018 and 2012a). Likewise, the ALC Strategic Map, which predicts the likelihood of best and most versatile land, is also designed for strategic use and should not be used for site specific assessments (Natural England, 2018 and 2012b). It is the site specific ALC field survey data carried out according to Natural England 2018 and



MAFF 1988, known as detailed (or ‘Post 1988’) ALC field surveys, that provides the most reliable detailed information on agricultural land quality at the site level.

14.8.4 As detailed ALC field surveys have not been undertaken on the majority of the agricultural land within the study area at this stage, the baseline conditions and identification of potentially significant effects in this PEIR are based on Provisional ALC mapping (where no detailed survey is yet available).

14.8.5 As outlined in Section 14.6, further detailed ALC surveys are planned prior to the submission of the application for development consent which could change the understanding of the baseline.

14.8.6 The extent of these baseline field surveys will also be dependent on the availability of site access to undertake detailed ALC surveys, where required. Significant efforts are currently being made to access as wide an area as is possible within the study area. However, where detailed ALC surveys are required and site access is not available, existing ALC data (from the Provisional mapping data) will be used to undertake the assessment. In the absence of new detailed ALC surveys, this may result in an overestimate of the quantum of permanent loss of agricultural BMV land, principally where sites which have a Provisional Grade 3 ALC (which would be counted as BMV land) are found, through new detailed ALC surveys to have a Grade 3b ALC (which would be non-BMV land).

Minerals safeguarding 14.8.7 Where minerals resources are subject to safeguarding policies within the study

area, limited information is available to enable detailed quantification of the distribution and volume of ‘workable’ mineral resources to be assessed. The preliminary assessment is therefore focused on a qualitative assessment of these receptors.

14.8.8 The DCO Project will be developed on land beneath which are sand and gravel deposits safeguarded under county-wide policies which cover all sand and gravel deposits in that county’s area (as opposed to specific Safeguarded or Preferred Areas identified in local level policies). The land uses for the DCO Project may require some degree of prior extraction of sand and gravel to enable the development finish levels to be created. However, it is currently unclear how much of this material would be extracted. Therefore, a worst-case scenario has been considered for this PEIR where all the sand and gravel beneath these areas of the DCO Project would be sterilised.



14.9 Overall baseline

14.9.1 This section provides a description of the current baseline identified from baseline data collection to date, and an outline of the predicted future baseline in the absence of the DCO Project.

Current baseline

Land contamination

Geo-Environmental desk study 14.9.2 The land contamination baseline conditions are presented in detail in the Geo-

Environmental Desk Study (desk study) which will form an appendix to the ES. The baseline conditions presented in the desk study are summarised briefly in this section.

14.9.3 In line with the approach set out in CLR11, the desk study presents a Preliminary Risk Assessment in order to develop a Conceptual Site Model (CSM). The CSM identifies the potential contaminant linkages between contaminants (sources) and receptors present in the study area (known as Source-Pathway-Receptor contaminant linkages). A copy of the schematic CSM for the current use of the Site is reproduced from the geo-environmental desk study as Figure 14.5, Volume 2. The CSM for the future use of the Site is presented in as Figure 14.6, Volume 2.

14.9.4 The principal source of contamination identified in the desk study comprises the historic landfills2 and authorised landfills3 which are present across a large proportion (approximately 60%) of the land within the study area.

14.9.5 These landfills vary in age and design and in the nature and composition of the wastes deposited. Many of the historic sites and older authorised sites closed before the requirements of the Landfill Directive (LFD) came into force in July 2001 and were therefore constructed on the ‘dilute and disperse’ principle with little or no basal lining system. Furthermore, the historic sites and older authorised sites may have received additional non-reported material types. Those sites which are ‘LFD compliant’ are designed to modern standards with a fully engineered basal and sidewall lining system as well as capping systems and leachate and gas management infrastructure in place.

2 Historic landfill sites are known areas of landfilling where there is no pollution prevention control (PPC) permit or waste management licence currently in force. This includes sites that existed before the waste licensing regime and sites that have been licensed in the past but where this licence has been revoked, ceased to exist or surrendered and a certificate of completion has been issued. 3 Authorised landfill sites are known areas of landfilling currently authorised by the Environment Agency under the Environmental Permitting Regulations. Landfill permits are authorised by a Waste Management Licence, a PPC Permit or an Environmental Permit.



14.9.6 Principal contaminants produced by landfills are in the form of leachate and landfill gas generated by decomposition of the organic components of the waste mass. The composition of the leachate at each location is highly dependent on the material deposited within the landfill. Decomposition of the waste mass within a landfill may span decades and its rate is highly dependent on a number of factors including the composition of the waste mass and the moisture content. During this time leachate and landfill gas may be generated.

14.9.7 Other key sources of potential contamination identified in the desk study include the existing bulk fuel storage facilities located both on and surrounding the current Airport, waste transfer sites and a number of industrial facilities.

14.9.8 The natural geology beneath the study comprises the following key units:

Alluvium

River Terrace Deposits

London Clay

Lambeth Group and Chalk Group.

14.9.9 Groundwater is principally present within the shallow River Terrace Deposits and at depth within the Chalk Group which are classed by the Environment Agency as Principal Aquifers. From the desk study data, the London Clay is noted to have a minimum thickness of around 25m across the study area, meaning (due to the significant thickness) that it acts as a low permeability barrier, making it extremely unlikely that contamination can migrate vertically between the shallow and deep aquifer units in the absence of a preferential pathway.

14.9.10 A detailed groundwater and surface water baseline is included within Chapter 21 Water environment.

14.9.11 It is noted that a review of the desk study data on the risks associated with geohazards (including compressible and collapsible ground, seismic activity, running sand and landslides) indicates that the risks from land instability and geohazards across the study area are generally classified as being negligible to low.

Ground Investigation

14.9.12 A ground investigation for the DCO Project is currently being progressed and draft data have been reviewed for this PEIR. Data reviewed in relation to human health, includes soil/ landfill waste composition and quality, together with volatile groundwater contamination data. Data reviewed in relation to controlled waters includes groundwater and surface water quality data.



14.9.13 The certified laboratory data sheets which report the results of the soil, groundwater, surface water and soil vapour sampling are part of factual ground investigation reports which will form an annex to the ES.

14.9.14 Data received to date are currently in draft format and therefore no results have been analysed in detail. Only a high-level review has been undertaken to help inform this assessment. Once further data are received, more detailed analysis will be undertaken and incorporated into risk assessments that will support the ES and form part of the embedded and good practice environmental measures required by the draft CoCP.

14.9.15 The approach to Human Health and Controlled Waters Risk Assessment (HHRA and CWRA) has been developed to meet the requirements of the UK legislative framework for the assessment and management of potential contaminated land and incorporate current best practice including statutory and non-statutory guidance and codes of good practice. The methodology is unchanged from that presented in the EIA Scoping Report - Land Quality Approach to Human Health and Controlled Waters Risk Assessment.

14.9.16 At the time of reporting, the locations from which soil and groundwater data are available for review is shown on Figures 14.2 and 14.3, Volume 2.

14.9.17 The land from which the data is available is currently in use as open space, agricultural land, recreational or community spaces with offices, existing car parking and for utility/drainage infrastructure. The land is known to be underlain predominantly by historical landfills that are known to have accepted a range of inert, industrial, commercial and household wastes.

14.9.18 The land from which the data is available is proposed to be redeveloped as part of the proposed runway / taxiway infrastructure and other supporting infrastructure such as terminal buildings, new road alignments, flood storage and drainage sites and commercial offices.

Contamination in soils

14.9.19 In terms of land use, it is likely that the Generic Assessment Criteria (GAC) for light industrial or commercial end use would apply to much of the DCO Project, although public open space (park) would be used where soft landscaping areas are proposed to ensure that the likely exposure scenarios are appropriate to the type of development proposed. Whilst some areas (such as the relocated Immigration Removal Centre) may require assessment against even more sensitive assessment criteria (for example residential end-use without gardens), these are likely to be very limited and will be addressed on a case by case basis in the required land contamination assessments.



14.9.20 At the time of writing a high-level review of the available quantitative laboratory data has been undertaken. Contaminants were screened against GACs for commercial end use and public open space (POS) end use. Where no UK derived GAC for a contaminant were available for the relevant end use, results have been screened against non-UK criteria (Dutch Intervention Value and United States Environmental Protection Agency (USEPA) Industrial Soil values).

14.9.21 Based on a review of this preliminary screening of a total of 1,998 soil samples, the following key contaminants have been identified as exceeding the GAC and will therefore represent a focus of further assessment as part of the ES. This is shown in Table 14.17.

Table 14.17: Land contamination preliminary screening of soil data

GAC (as defined in Appendix 14.1)

Key contaminants exceeding GAC

Commercial Polycyclic Aromatic Hydrocarbon (PAH) compounds: Benzo(a)pyrene, Benzo(b)fluoranthene, Chrysene and Dibenz-a-h-anthracene;

Metals: Cadmium, Lead and Nickel

Public Open Space

PAH compounds: Benzo(a)pyrene, Dibenz-a-h-anthracene, Benzo(b)fluoranthene, Chrysene and Indeno(1,2,3-cd)pyrene

Metals: Lead, Nickel and Copper;

Petroleum hydrocarbons: Aliphatics >C21-35

SVOC: Di-N-Butyl Phthalate

Non-UK guidelines

Polychlorinated Biphenyls (PCBs)

Cyanides

Asbestos

14.9.22 Laboratory results have recorded the presence of asbestos located in samples taken from made ground at the Site. All three main types of asbestos were recorded: Chrysotile, Amosite and Crocidolite.

14.9.23 Further assessment of the risks from asbestos in soils to human health receptors will be undertaken as part of the ongoing ground investigations and reported in the ES. A scope of works is being implemented to provide quantitative airborne asbestos fibre release data to support the assessment of potential risks from asbestos in soil tracked back into buildings and from asbestos release to air during



the construction earthworks. The scope of works, a copy of which is included in Appendix 14.3: Approach to collection of qualitative asbestos release data, Volume 3, has been developed in conjunction with, and endorsed by, the Institute of Occupational Medicine (IOM).

14.9.24 The potential for Asbestos Containing Materials (ACM) to be present in buildings/materials which will be demolished/dismantled as part of the construction works will be assessed through pre-construction hazardous materials surveys and, where identified, removed by licenced contractors under appropriate controls and Duty of Care in line with the Control of Asbestos Regulations 2012 (CAR-2012) and the approved code of practice ‘managing and working with asbestos’.

Groundwater vapour

14.9.25 The presence of vapours potentially arising from contaminated groundwater was assessed by comparing measured volatile contaminant concentrations in groundwater against the Generic Assessment Criteria for Groundwater Vapour (GACgwvap) for both a residential and a commercial end use.

14.9.26 Exceedances of the relevant commercial and residential guidance values were recorded and further assessment of the risks from volatile contaminant concentrations in groundwater will be undertaken to inform the requirement for additional environmental measures (such as remediation) once further data is available.

Contamination in Groundwater

14.9.27 At the time of writing, a high-level review of the available groundwater data has been undertaken, noting that a full year of groundwater monitoring has not yet been completed in many locations from which to undertake detailed trend analysis.

14.9.28 Concentrations of contaminants in groundwater were screened against Drinking Water Standards (DWS) reflective of the Lower Thames Gravels WFD groundwater body being located in a drinking water protected area.

14.9.29 The groundwater quality results indicate that across the areas sampled to date, the following contaminants are above the DWS and will require further assessment as part of the ES. This is shown in Table 14.18.

Table 14.18: Land contamination preliminary screening of groundwater data

Groundwater Screening Criteria

Key contaminants exceeding screening criteria

Screening criteria in Appendix 14.1

Firefighting compounds and breakdown products: PFOS compounds, HBCDD



Groundwater Screening Criteria


Polycyclic Aromatic Hydrocarbon (PAH) compounds: Anthracene, benzo(g,h,i)perylene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(k)fluoranthene, indeno(1,2,3-cd)pyrene, fluoranthene, naphthalene

Phthalates: Bis(2-ethylhexyl)phthalate

Petroleum hydrocarbons: GRO >C5-12, C6-C7 aromatic TPH

VOCs: 1,3,5-trichlorobenzene, 2,4,5-trichlorophenol, 2,4,6-trichlorophenol, benzene, cis-1,2-dichloroethene, gamma-HCH, toluene, vinyl chloride

Phenols: Phenol, pentachlorophenol, nonylphenol, octylphenol

Herbicides/pesticides: Aminopyralid, benazolin, clopyralid, dicamba, fenuron, fluroxypyr, mecoprop, monuron, picloram, fenoprop, triadimefon, 4-CPP

Chloroalkanes >C10-13

Metals: Arsenic, boron, cadmium, chromium (III and VI), iron, lead, mercury, nickel, selenium, zinc

Inorganics: Ammoniacal nitrogen, bromate, chloride, cyanide, chlorine, nitrate, nitrite, bromate

Laboratory detection limit (for compounds with no screening criteria in Appendix 14.1)

Petroleum hydrocarbons: Total TPH

Polychlorinated Biphenyls (PCBs): Total PCBs, various congeners

Metals: Manganese

Dibenzofuran compounds

Ethylene glycol

Acetate

VOC: 2,4-dichlorophenol

Pathogens: E coli, faecal streptococci


14.9.30 Further information on groundwater is included within Chapter 21 including a preliminary WFD assessment.



Contamination in Surface Water

14.9.31 At the time of writing a high-level review of the available surface water data was undertaken, noting that in a number of locations, a full year of monitoring has not yet been undertaken from which to undertake detailed trend analysis (and in particular that the screening criteria outlined in Appendix 14.1 are based on annual averages).

14.9.32 Nevertheless, concentrations of contaminants in surface water were screened against the UK Environmental Quality Standards (EQS) for freshwater watercourses.

14.9.33 The surface water quality results indicate that across the areas sampled to date, the following contaminants were detected at concentrations above the EQS and will require further assessment as part of the ES once a more detailed dataset is available. This is shown in Table 14.19.

Table 14.19: Land contamination preliminary screening of surface water data

Surface Water Screening Criteria


Screening criteria in Appendix 14.1

Firefighting compounds and breakdown products: PFOS compounds,

PAH compounds: Anthracene, benzo(g,h,i)perylene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(g,h,i)perylene, benzo(k)perylene, fluoranthene, indeno(1,2,3-cd)pyrene, naphthalene

Phthalates: bis(2-ethylhexyl)phthalate,

Metals: Chromium, cadmium, iron, lead, manganese, mercury, nickel, zinc

Inorganics: Bromate, chloride, chlorine, cyanide (total and free), nitrate, nitrite, ammoniacal nitrogen

Petroleum hydrocarbons: GRO >C5-12


VOCs: 2,4,6-trichlorophenol, dichloromethane

Phenols: Phenol, nonylphenols, octylphenols

Herbicides/pesticides: 2,4-D, dicamba, fluroxypyr, MCPA, triallate, triclopyr, trifluralin

Laboratory detection limit (for compounds with no screening

Polychlorinated Biphenyls (PCBs): Total PCBs, congener 118

Petroleum hydrocarbons: Total TPH



Surface Water Screening Criteria


criteria in Appendix 14.2)

Dibenzofurans

Cyanides

Acetate

Formate

Ethylene glycol

14.9.34 Further information on the surface water is included within Chapter 21.

Soils 14.9.35 The Soilscape Map (included as Figure 14.7, Volume 2) indicates that the soils of

the study area are generally classified as ‘freely draining slightly acid loamy soils’. ‘Loamy and clayey floodplain soils with naturally high groundwater’ occur along the river valleys whilst to the east and north of the study area soils are classified as ‘loamy soils with naturally high groundwater’.


14.9.36 The ALC system classifies land into five grades, with Grade 3 subdivided into Subgrades 3a and 3b. Best and Most Versatile (BMV) agricultural land is defined as Grades 1, 2 and 3a.

14.9.37 The Provisional ALC mapping indicates the study area as being predominantly ‘non-agricultural’ and ‘urban’ land with some agricultural land classified as Grades 1, 2 and 3, refer to Figure 14.8, Volume 2.

14.9.38 However, it is the site specific ALC survey data carried out according to MAFF guidance (MAFF, 1988), known as ‘detailed’ ALC field surveys, that provides detailed information on ALC grades at the level required to identify the presence of BMV agricultural land.

14.9.39 Where detailed ALC field surveys have taken place within the study area (refer to Figure 14.9, Volume 2) the results show agricultural land being a mix of grades, with Grades 1, 2 and 3a (ALC grades used to classify BMV agricultural land) being present. Non-BMV agricultural land is also present.

14.9.40 Copies of the detailed ALC surveys carried out to date as part of the DCO Project will form an appendix to the ES.



Geodiversity

14.9.41 There are no international or national geodiversity sites located within the study area.

14.9.42 There are currently no RIGS or LIGS located within the study area.

14.9.43 In October 2016, the London Geodiversity Partnership (LGP) published a list of candidate sites for proposed consultation which were considered worthy of inclusion as LIGS or RIGS. Of these, one, the proposed Sipson Lane Complex (LGP ref. GLA 62), is located within the study area and is adjacent to the east of the existing M4 spur road, refer to Figure 14.10, Volume 2, where the proposed northern parkway will be developed. The LGP have proposed the Sipson Lane Complex as a RIGS based on preserving a face of the only remaining working quarry in west London within the Greater London Authority (GLA) and providing a detailed view through the Langley Silts and river terrace deposits.

14.9.44 Another candidate site Bedfont Lakes (LGP ref. GLA 68) is located immediately adjacent to the southernmost extent of the study area to the east of the B3003/Clockhouse Lane, refer to Figure 14.10, Volume 2, but will remain untouched as part of the DCO Project. The LGP have proposed Bedfont Lakes as a LIGS due to the presence of Kempton Park Gravel exposures.

14.9.45 A review of the Draft New London Plan (2017) does not identify either Sipson Lane or Bedfont Lakes as candidate RIGS/LIGS which suggests that neither of these sites have been considered to be recommended by the GLA for designation in local development plans. This is consistent with the London Foundations Supplementary Planning Guidance (SPG, 2012) which considers both sites to have a geodiversity value of zero (noting in the accompanying comments that Sipson Lane is a ‘landfill site’ and Bedfont Lakes is ‘restored and landscaped; recreation ground’) and does not recommend that either site is visited in the future to determine whether they should be protected

14.9.46 Therefore, for the purposes of this PEIR it is assumed that both these candidate geodiversity sites will remain undesignated at the time of the application for development consent. However, if either site was to be designated before the application for development consent, this would be taken into account in the ES.

Minerals safeguarding 14.9.47 The sand and gravel river terrace deposits constitute the principal primary

aggregate mineral resource in the study area, but London Clay (which is not an aggregate mineral) is also extracted commercially.

14.9.48 Historically, the area surrounding Heathrow has been extensively worked for minerals (sand and gravel) for many decades and there are still several active



sand and gravel quarries and other areas with unworked sand and gravel resources within the study area, refer to Figure 14.11, Volume 2.

14.9.49 Many of these extraction pits have since been backfilled and are recorded as historic or authorised landfills.

14.9.50 Within the study area a number of sites with valid planning permissions to extract sand and gravel exist, and a number of other sites within the study area are designated in the local planning authority local plans for possible future extraction. Other areas are known to contain minerals deposits which may be suitable for extraction in the future and these areas are safeguarded from development which may sterilise those potential resources. There are also parcels of land where it is known or expected that mineral deposits exist, but they are not designated or safeguarded under any policy. Where this information is available, these sites are also included, refer to Figure 14.11, Volume 2.

14.9.51 A full list of the minerals sites identified as part of the desk study are presented in Appendix 14.5: Assessment of mineral safeguarding effects, Volume 3.

14.9.52 In their Scoping Response, Surrey CC highlighted a Preferred Area for concreting aggregate in the Surrey Minerals Local Plan Core Strategy Development Plan Document 2011 (Preferred Area G: Homers Farm, Bedfont).

14.9.53 A review of this site as part of the baseline data collection indicates that an existing time limited planning permission has already been granted to extract the sand and gravel from the site, infill the resulting void with inert waste and restore the site to agriculture.

14.9.54 At the time of writing this PEIR, the operator of the site has begun extracting the sand and gravel and is expected to have completed works prior to the commencement of construction of the DCO Project. On this basis, the assessment presented in this PEIR considers that the mineral will have been fully won from this site prior to development.

Future baseline 14.9.55 In the absence of the DCO Project, there is likely to be a change in baseline

conditions as a result of other development being pursued at Heathrow Airport. The Kilobox Apron Development and Runway Access Taxiway projects, described in Table 5.1 of Chapter 5, would be completed prior to the commencement of construction of the DCO Project.

14.9.56 The assessment presented in Section 14.10 assumes the presence of these developments in the baseline, against which the effects of the DCO Project are compared. However, it is noted that for land quality there are no implications of these two projects on the current baseline as summarised below:



For the land contamination assessment, the developments do not introduce new potential sources of contamination or new human health and controlled waters receptors that are not already considered in the current baseline (i.e. they are extensions of the existing operational Airport and its activities)

For the agricultural land quality and minerals safeguarding assessment, the developments are contained within the existing Airport boundary and will therefore not alter the baseline with respect to the presence of agricultural land, soils or geodiversity and do not interact with existing or proposed minerals safeguarding sites.

14.9.57 Additional Heathrow Airport Supporting Development (ASD) may also come forward in the future (with their construction and operation phases overlapping with the construction and/or operation phases of the DCO Project). Such development is presented and assessed within Section 14.11.

14.9.58 There will also be other changes in baseline conditions in the wider area as a result of land use changes through development un-related to Heathrow Airport. Such ‘other development’ could result in new receptors or result in other cumulative effects with the DCO Project. Where these developments are built out before the construction of the DCO Project commences, or where the construction and operation phases of these developments overlap with the construction and/or operation phases of the DCO Project, they are assessed in Section 14.11.

Land contamination

14.9.59 In the absence of the DCO Project, there are no other known trends or factors that are expected to affect the current baseline conditions and as such the existing baseline conditions will be used for this PEIR assessment.

14.9.60 Whilst expanded in quantum in a future baseline, the nature of the existing Airport operational activities (for example maintenance and refuelling of operational vehicles), would remain unchanged with respect to potential sources of land contamination. In particular, the existing Perry Oaks fuel storage facility proposed to be expanded in the future and developments/alterations to existing terminal infrastructure will not introduce new receptors that are not already considered under the existing baseline which will be used for this assessment. The implications for the presence of these developments in the future to change the conclusions of the primary assessment are outlined as part of the cumulative effects assessment in Section 14.11.

14.9.61 It is noted that there may be a number of parcels of land affected by contamination (including the historic and authorised landfills and existing industrial estates) which prior to the DCO Project may be subject to remediation measures designed to



mitigate the effects of land contamination (either by the existing owners or as part of future development).

14.9.62 However, as it is not possible to predict the timing or extent of such remediation and given that any remediation would only improve the condition of the land parcels with respect to land contamination, the use of the existing baseline conditions is considered to be appropriate and represents a conservative position for this PEIR assessment.

Agricultural land quality 14.9.63 Baseline conditions for agricultural land, soils and geodiversity are geographically

discreet and not substantially influenced by changes to the surroundings. That is to say, agricultural land, soils and geodiversity will only be influenced by changes or activities taking place on or at the resource itself.

14.9.64 The baseline conditions for existing agricultural land, soils and geodiversity are therefore unlikely to change over the lifetime of the DCO Project. However, it is noted that there are a number of existing and former mineral extraction sites (such as Homer’s Farm, Hithermoor Quarry and Stanwell Moor) which as part of their planning permissions are due to be restored to agricultural use in the future.

14.9.65 Where planning permissions indicate that restoration is due to be completed prior to the commencement of construction of the DCO Project, the proposed restoration to agricultural land will be taken into account when assessing the future baseline conditions of the land lost to the DCO Project.


14.9.66 It is likely that there would be changes in the mineral reserves baseline as existing sand and gravel quarries continuously work a reserve. These changes may be an increase and decrease in terms of quantity resulting from:

A change in location of resource (sites working different phases, and sites being worked out, and consented sites becoming operational)

Extensions (both lateral and vertical) to existing sites through the grant of planning permission

Granting new consents to work mineral resources.

14.9.67 There is also the potential that land use would change at mineral sites. These changes may be through:

The submission, approval and implementation of a restoration scheme (in addition to that submitted as part of the application process (ie the restoration strategy))



A change to a consented restoration plan.

14.9.68 It is not however possible to accurately predict what these changes would be as the nature and timing of any such changes would arise in response to the supply and demand circumstances in the future. The most accurate way of assessing future baseline reserves or resources is therefore to identify those sites designated or safeguarded for future minerals extraction in planning policy documents and consider those as part of the assessment process. However, as minerals deposits will not change naturally over time, no differentiation has been made between the current and future minerals baseline and all of the designated or safeguarded deposits are included in the current baseline data.

14.10 Assessment of land quality effects

14.10.1 Table 6.1 in Chapter 6: DCO Project description outlines the key construction and operational activities that will be occurring in Phases 1 to 3 of the DCO Project.

14.10.2 The key activities and assessment of the effects of the DCO Project on land quality is described for each Phase in the following sections.

Phase 1: c. 2022-2026 - Land contamination

Activities

Introduction to construction activities 14.10.3 Exploratory ground investigation and environmental surveys are currently ongoing

and will be used to inform the EIA, design development and delivery stages prior to submission of the application for development consent. Further investigations that may be necessary following the DCO process will be undertaken early in this phase (for example hazardous materials surveys prior to demolition or additional ground investigation to confirm foundation designs of new infrastructure).

14.10.4 Construction activities are programmed to start at the beginning of Phase 1 with site establishment works (site fencing, environmental measures, construction compounds and associated facilities).

14.10.5 Construction works are then at their peak in the middle to end of Phase 1 when both the North West Runway and the terminals and associated infrastructure will be under construction.



Earthworks

14.10.6 Earthworks for the DCO Project are substantial, totalling around 21 million m3 of earth moving across the programme (airfield, M25, rivers, local roads etc.). The peak of the quantity of the material that must be moved will be approximately 8 million m3 in the 2023 earthworks season.

14.10.7 Earthworks material will be mainly generated from borrow pits, cut/fill operations to form the expanded operational Airport and the demolition of existing buildings / infrastructure.

14.10.8 Whilst the majority of earthworks would be expected in the naturally occurring geology, this is frequently overlain by made ground. In addition, there has been abundant landfilling of waste materials in the voids left by the extensive sand and gravel extraction in the area, which may be encountered during earthworks.

14.10.9 The new airfield will be developed over landfill sites of varying waste composition, age and depth. The current earthworks strategy has been developed to minimise the excavation of landfilled material. The adopted engineering solutions for the airfield earthworks strategy include:

Excavation and replacement of landfill waste with suitable engineering fill

Earthworks pillar – landfill is only excavated and replaced with engineering fill beneath runway and taxiway support zones

Piled support slabs – would act to transfer loads through landfilled materials into the London Clay Formation below.

14.10.10 It is noted in the earthworks strategy that none of the proposed earthworks activities involve penetration of the London Clay into the underlying Chalk Principal Aquifer.

14.10.11 Despite the measures taken to reduce bulk excavation of wastes, the earthworks required within the Site will still result in a substantial volume of historic landfill material being displaced. In order to limit transportation of waste materials off-site, it is proposed that three new landfills be created to dispose of waste unable to be reused/recovered as part of the earthworks. The new landfills will be constructed at the Northern Strip, Taxiways islands and Old Slade Lake.

14.10.12 The proposed airfield earthworks platform also extends over Colnbrook West Lake and Orlitts Lake to the west of the M25, both of which will require dewatering and infilling.

14.10.13 Borrow pits will produce a combination of granular and cohesive fill material derived from the River Terrace Deposits and underlying London Clay respectively. Four borrow pits are proposed (Northern Strip and Taxiway islands, BP03 (north of Harmondsworth) and BP04 (north of M4)). Construction of BP04 will include



dewatering from Old Slade Lake. The borrow pits are shown on Graphic 6.4 in Chapter 6: DCO Project description.

14.10.14 The waste generated from site wide activities will likely comprise a mixture of inert, non-hazardous and hazardous wastes. All excavated hazardous wastes are to be exported off-site using a third-party licenced waste facility under full duty of care compliance. Some wastes may be treated on site (see Section 14.10.24). Further assessment of the disposal of waste is presented in Chapter 20.

Cut and cover tunnels 14.10.15 The new cut and cover M25 tunnels will be constructed in Phase 1. The new

tunnel will require the diversion of the SSE pylons and substation and clearance of a number of facilities and infrastructure.

14.10.16 There is currently a proposal for a cut and cover tunnel for combined Automated People Mover (APM)/baggage/airside roads between the new northern and western aprons. The APM construction will progress in a single phase as part of the earthworks to release airfield works above ground.

Piling works 14.10.17 Piling is proposed to be undertaken through a number of landfills to allow

construction of the North West Runway and adjacent taxiways and reduce the volume of landfill material which requires excavation and management. In some areas, excavation of landfill material will be undertaken prior to the piling works to achieve the required airfield platform level and form a piling platform.

14.10.18 Piling works will comprise the use of driven, steel tubular piles with a total of approximately 47,300 piles required. The typical pile depth required is approximately 15m to 20m into the London Clay, noting that none of the piles will extend beyond the base of the London Clay.

Movement, stockpiling and treatment of excavated material 14.10.19 During the Site preparation works, a number of construction/haul roads will be

developed on site to facilitate the movement of vehicles carrying excavation and construction materials. The internal roads will vary in location, alignment and specification according to the construction needs and phasing.

14.10.20 Two strategic haul roads will be built to move materials between the southwest and north-eastern ends of the airfield construction, and to move both landfill material arising from the west of the Site for use in reinstatement of the Northern Strip borrow pit and engineering fill extracted from the Northern Strip borrow pit to the west of the M25 to infill Colnbrook West Lake and Orlitts Lake.



14.10.21 A temporary bailey bridge will be required for the haul road to cross the M25 and railway line which runs to the west of the M25. A temporary bridge will also be required to move material over the existing A4 from borrow pit BP04.

14.10.22 Where excavated material cannot be directly placed, it is assumed material will be stockpiled. A proportion of the stockpiled material will comprise of excavated landfill. Some of this material is expected to be suitable for mechanical processing to recover suitable fill materials for use in the earthworks with unsuitable material being re-landfilled.

14.10.23 Stockpiling of materials is proposed to be undertaken east of Harmondsworth and to the south of Holloway Lane (see Graphic 6.5 in Chapter 6).

14.10.24 A soil treatment centre will be located to the southeast of the principal east-west haul road to process excavated materials requiring treatment prior to reuse.

Diversion of watercourses and flood compensation

14.10.25 There are a number of rivers that will require realigning / diverting as part of the development works. The construction of the new channels / culverts on the main Airport will start early in Phase 1. Rivers diversions / realignments will be undertaken whilst maintaining the existing river corridors in their current states until the new diversions are complete.

14.10.26 It is noted that where new river alignments are constructed, these will be located in areas of former landfills and potentially contaminated ground. In these instances, the rivers will be hydraulically disconnected from the existing groundwater body (the Lower Thames Gravels) through the use of impermeable linings as part of the new channel construction.

14.10.27 New flood storage areas will be constructed in the areas immediately to the northwest and north of the Site. A number of these flood storage locations are located on former landfill sites and similar to the new river corridors will be hydraulically disconnected from the underlying aquifer using impermeable lining.

Non-potable water supply and thermal energy 14.10.28 As part of the non-potable water strategy, it is proposed to install additional

groundwater boreholes into the Chalk Aquifer from which water would be abstracted under Heathrow’s existing groundwater abstraction licence. Additional boreholes may also be installed into the Chalk Aquifer as part of the thermal energy strategy.

14.10.29 Whilst the exact location of boreholes required for these strategies have not been finalised, they would be installed using best practice techniques to minimise the risks of creating preferential pathways for vertical migration of existing



contamination in the shallow soils and River Terrace Deposit aquifer into the underlying Chalk Aquifer (for example the use of environmental seals and casing). In addition, the location of the boreholes would not be on land affected by contamination (such as landfills) and appropriate headworks would be installed at each location to prevent accidental spillages from entering the borehole. These measures would further reduce the risks to the Chalk Aquifer during drilling and subsequent operations.

Landscaping and parkland work 14.10.30 Landscaping is proposed across the Site and it is anticipated this will be

undertaken predominantly in areas that have undergone earthworks. It is proposed to re-use site won topsoil in re-soiling and landscaping works. Appropriate cover systems (if required) will be designed as part of the remediation strategy.

Operational Activities 14.10.31 The following key operational activities occur during Phase 1:

1. Occupation of new infrastructure buildings once completed

2. Expansion of existing operational Airport activities (such as refuelling and maintenance) in response to ATM increase

Effects upon human health receptors during construction activities

14.10.32 Construction workers engaged in the construction of the DCO Project will be subject to Construction (Design and Management) (CDM) Regulations and safe working practices as part of normal construction health and safety management under the Health and Safety at Work Act (1974) and regulations made under the Act. In addition, the draft CoCP further embeds the CDM Regulations and use of control measures such as PPE. As such the risks to construction workers during the construction activities is considered to be low and assessed as a neutral and therefore not significant effect.

14.10.33 Other human health receptors comprise: Heathrow colleagues, contractors and passengers in the operational Airport, recreational users of public open space, and residential receptors on the Site boundaries. The construction works may also result in the creation of new pathways for contaminants to migrate to adjacent sites and residential areas, for example via wind-borne dust and vapour during construction and earthworks.

14.10.34 Excavation of large areas to facilitate new infrastructure is proposed, including the excavation of existing landfills to facilitate the construction of the North West Runway. As a result of the extensive earthworks, materials (including landfill materials) will be moved and stockpiled prior to being treated, recycled, reused or



disposed of on-site. In addition, demolition/dismantling of existing buildings/infrastructure will be required to facilitate the construction works.

14.10.35 The embedded measures included in the draft CoCP are designed to reduce effects to human health receptors. These include a number of best practice measures to minimise the potential for migration of dusts, odours and vapours as well as ground gases, during construction activities including demolition of existing properties. Some of these are embedded at the design stage, for example keeping dust causing activities away from sensitive receptors and measures that will be undertaken during construction for example, the use of hoarding, dust suppression measures (dampening, covering, watering, seeding) and stockpiling located to consider the predominant wind direction.

14.10.36 Other measures include undertaking ground investigations and treatment and remediation of contaminated materials at a soil treatment site located centrally within the Site as well as landfilling inert and non-hazardous wastes within a new engineered and permitted facility in the Site itself rather than transporting off-site.

14.10.37 Further ground investigation is being undertaken to provide characterisation of the materials required to be excavated during the construction activities (including further assessment of the risks from asbestos in soils) and this information will be used to refine the earthworks approach with the aim of minimising the amount of potentially contaminated materials requiring excavation (and therefore reducing the potential for generation of dusts etc during construction) or identifying further control measures required as part of the DCO Project.

14.10.38 An assessment has been made of pollutant linkages during the construction works in this phase. This is detailed in Appendix 14.4. Overall it is considered that, with the controls listed in Section 14.5, land contamination risks associated with human health receptors are not likely to increase during construction works and therefore result in a neutral effect, although it is possible there may be some short term increase in vapour or gas release resulting in a short-term minor adverse effect on surrounding land users at discrete points during the construction works in this phase which is not considered to be significant.

Effects upon human health receptors during operational activities

14.10.39 Future site users comprise recreational users of public open space as well as existing Airport workers, maintenances staff and passengers. The proposed end-use of the DCO Project aligns most closely in CLR-11 with a predominantly light industrial or commercial end use with some soft landscaping proposed and these are considered to be the likely exposure scenarios appropriate to the type of development proposed to be carried forward.



14.10.40 Effects on these receptors would principally relate to existing landfill sites that may currently have inadequate capping which could lead to contaminant uptake, uncontrolled landfill gas emissions and vapour risks.

14.10.41 The DCO Project will incorporate embedded design measures, such as gas protection in new buildings, and additionally undertake soil or groundwater remediation where required, which would ensure that risks to future site users would be kept to an acceptable level.

14.10.42 Risks to site users within the operational Airport during this phase may reasonably be expected to have reduced due to the remediation of historic soil or groundwater contamination, by the removal of landfill wastes and incorporation of design measures into new infrastructure.

14.10.43 There are therefore likely to be some neutral to minor or moderate beneficial effects associated with a decrease in risk to on-site human health which would be apparent to users of the operational Airport towards the end of Phase 1 of the DCO Project. In particular, the moderate beneficial effects would relate to remediation or removal of existing landfill sites that may currently have inadequate capping and uncontrolled landfill gas emissions.

Effects upon on-site property receptors during construction and operational activities

14.10.44 Property receptors include built environment such as existing structures/buildings including their foundations and services such as water supply pipes. Effects on property receptors would largely relate to the migration of ground gases such as carbon dioxide and methane.

14.10.45 Many of the existing buildings and services located within the study area will be demolished or decommissioned as part of the DCO Project. New buildings will be designed to take into account prevailing ground conditions with suitable foundations designed to mitigate potential risks of ground instability (such as where infrastructure is built on former landfill sites) and geohazards (such a ground gases and existing contamination effects on concrete).

14.10.46 The construction design methodology for new infrastructure will also take into account the potential for effects on existing infrastructure (for example the effects of dewatering on the stability of existing foundations or embankments) and appropriate measures (such as cut-off trenches and shoring) will be implemented where required.

14.10.47 There is therefore judged to be a neutral effect on existing built environment during construction activities in this phase which is not significant.

14.10.48 Following completion of construction activities in Phase 1, risks to on-site property receptors may also be reasonably expected to have reduced due to the



remediation of historic soils or groundwater contamination by the removal of landfill wastes, dewatering activities and appropriate design measures. Reduction of such risks would lead to a neutral to minor beneficial effect on this receptor.

Effects upon controlled water receptors during construction activities 14.10.49 The construction activities have the potential to have an adverse effect on shallow

groundwater principally through the disturbance of soils resulting in the potential for mobilisation of contamination, and in particular excavation of landfill materials.

14.10.50 The detailed design of the new infrastructure will be completed following the ground investigation and appropriate construction techniques and controls implemented to mitigate the potential for mobilisation of contamination during soil excavation. The construction design seeks to minimise the amount of material requiring excavation and movement through the use of in situ piling techniques.

14.10.51 However, bulk excavation of landfill and other soils is necessarily required in order to create the formation level of new infrastructure such as the North West Runway and M25. Measures are therefore embedded into the draft CoCP including requirements to minimise the exposed excavation areas, managing stockpiles to control runoff, and covering stockpiles to prevent rainwater ingress and minimise generation of dust and odour. These measures are likely to reduce the potential for contaminant generation and mobilisation during construction resulting in only a minor adverse effect.

14.10.52 Many of the existing landfills beneath the Site are historic, unlined landfills resulting in historic waste materials currently being in continuity with shallow groundwater in the River Terrace Deposits and therefore acting as a potential source of contamination. The proposed earthworks strategy for the North West Runway and other major infrastructure such as flood storage areas, the M25 realignment and terminal/parkway buildings includes bulk excavation of a large proportion of this potential source material and placement into new lined landfills compliant with the current Landfill Directive (2001). This would result in a major beneficial effect on shallow groundwater quality in the Heathrow area as this source material (and its resulting leachate) would be removed from the environment.

14.10.53 In addition, dewatering of the River Terrace Deposit aquifer will be required to facilitate the construction works, in particular for basement excavations and cut-and-cover tunnels which will be constructed for the M25 and baggage tunnels. The resulting abstracted water will contain leachate and other contaminants which are already present in groundwater. Given that this abstracted water would be disposed of under consent from either the Environment Agency or local sewerage undertaker, thereby likely requiring some form of treatment, and not returned into



the aquifer untreated, this will result in a moderate to major beneficial effect on groundwater quality in the Heathrow area.

14.10.54 Furthermore, the construction of new river alignments which are hydraulically disconnected from the existing groundwater aquifer will provide a beneficial effect as the SPR-linkage for existing contamination in groundwater to enter the rivers will be removed.

14.10.55 As noted in Chapter 21 there is the potential for crayfish to burrow in the riverbanks including potentially the impermeable liners of diverted river channels where they flow over landfill. This could potentially cause the liner to be breached and create a pathway between the river and contaminated groundwater. Measures to prevent or reduce effects of burrowing will be identified and assessed as part of the ES.

14.10.56 Historic contamination has also been detected in shallow groundwater which may require remediation to be undertaken as part of the DCO Project. At this stage, the requirements for remediation have not been defined and will require further assessment as part of the ES. However, such remediation, if undertaken, would only ever provide a beneficial effect on the existing groundwater and surface water quality in the Heathrow area.

14.10.57 As noted, the creation of any new landfills would be managed under an environmental permit issued by the Environment Agency and the landfill design and construction would be compliant with the Landfill Directive (2001). As such, it is considered unlikely that the new landfills could act as a new source of contamination which may result in contamination of groundwater.

14.10.58 The design of the proposed North West Runway foundations includes for piling of sections of the runway which has the potential to introduce preferential pathways which would otherwise not be present and resulting contaminant migration into the underlying River Terrace Deposit aquifer. Principally this could occur where existing lined landfills containing landfill leachate are present beneath the runway piling areas – for existing unlined landfills, these pathways are already present.

14.10.59 Ground investigation is currently ongoing to understand the likely presence of landfill leachate in the areas where piling is required, and appropriate leachate management techniques will form part of the detailed construction design. However, the proposed driven piling technique and the thickness of London Clay above the Principal Chalk Aquifer in the locations where piling would take place would mitigate the potential for contaminant migration. On this basis the use of driven piling during construction is likely to have a minor adverse and therefore not significant effect.



14.10.60 The installation of groundwater boreholes into the Chalk Aquifer, either as part of the non-potable water or thermal energy strategies, has the potential to introduce a preferential pathway for migration of existing contamination in the overlying River Terrace Deposit aquifer and shallow soils. However, the use of best practice drilling techniques (in particular the use of environmental seals) and citing of boreholes away from land affected by contamination (such as landfill sites) means the risks to the Chalk Aquifer would be negligible to low.

14.10.61 In relation to pollution incidents during construction activities, such as accidental spillages and leaks from construction vehicles and refuelling activities, these will be controlled through the environmental measures incorporated into the draft CoCP. These measures include refuelling on hardstanding, suitably bunded areas for fuel storage, availability of spill kits and a protocol for promptly dealing with incidents. With these measures in place, the likely effects on groundwater during construction would be negligible.

Effects upon controlled water receptors during operational activities

14.10.62 During Phase 1, groundwater and surface water contamination could arise from operational activities, principally from ongoing vehicle and aircraft maintenance activities and from pollution incidents due to spillages during re-fuelling or de-icing. In addition, pollution incidents from residual contamination being present as a result of inappropriate reuse of contaminated fill materials and soils during the construction activities in this phase of the DCO Project cannot be discounted.

14.10.63 The environmental measures outlined in the draft CoCP include pollution control measures and good working practices such as spill response plans. These measures are also part of the existing Airport operations which include surface water runoff capture and discharge through the operational drainage system (for example Clockhouse Lane Pit, the Eastern Balancing Reservoir etc). Whilst the operational activities in this phase would see an increase in the quantum of re-fuelling, de-icing and maintenance works being undertaken, the change in risk profile in terms of magnitude and likelihood of a spill is not considered to be sufficient for the effects to be significant (receptor sensitivity remains high and magnitude increases from low to medium) noting also that a new drainage and discharge system will be introduced as part of the DCO Project. Further details of this system are included in Appendix 21.5: Drainage impact assessment.

14.10.64 Ground investigation works are ongoing to determine the nature of the soils which will be excavated as part of the works including landfill materials, general made ground/soils and sediments from the existing river channels. The draft CoCP outlines the measures for reuse of materials which include a detailed Materials Management Plan (MMP) incorporating reuse criteria to ensure that reused materials are suitable for use and will not present a risk to human health or the



environment. The MMP will be implemented by the main contractor(s) for the development with full documentation and verification required to ensure compliance with the MMP. On this basis, the likelihood of inappropriate reuse of materials during the construction activities which could subsequently affect receptors during operational activities is considered to be negligible.

14.10.65 There is also the potential for contamination to result from the operation of new fuel offloading and storage facilities which will be constructed in the north-western parts of the Site.

14.10.66 The environmental measures embedded into the design process for the new fuel offloading and storage facilities include design to Best Available Technique and secondary and tertiary containment measures in line with current best practice requirements. With these measures in place, it is expected that the effects on groundwater and surface water would be negligible to minor. The potential for larger spills, although not considered likely, are covered in Chapter 16.

Phase 2: c. late 2026-2035 - Land contamination

Activities 14.10.67 Construction activities continue through this phase of the DCO Project, but at a

reduced intensity and focused in specific areas of the Site. The North West Runway and associated taxiways and terminal infrastructure also become operational at the beginning of Phase 2.

14.10.68 The new landfill(s) created in Phase 1 will remain under an Environmental Permit issued by the Environment Agency and depending on the nature of the permit closure activities, operational management of the landfill gas and leachate systems may be ongoing.

Effects upon human health and controlled water receptors during construction and operational activities 14.10.69 Although the specific location of any potential effects resulting from construction

activities in Phase 2 will differ from those identified in Phase 1, the nature of the potential effects is generally expected to be similar to those identified in Phase 1.

14.10.70 Given the peak construction activities occur during Phase 1, the assessment of effects in Phase 1 is considered to be most representative of the likely significant effects of the DCO Project and the assessments for construction activities in Phase 2 are therefore not repeated here for this PEIR assessment.

14.10.71 Similarly, whilst the operational activities in Phase 2 would see an increase in the amount of re-fuelling, de-icing and maintenance works being undertaken, the change in risk profile in terms of magnitude and likelihood of a spill is not



considered to be significantly different from that identified in Phase 1 and the assessments for operational activities in Phase 2 are therefore not repeated here for this PEIR assessment.

14.10.72 As the details of Phase 2 are finalised for the submission in the ES, the assessment of the land contamination effects will be developed to consider the specific activities in this phase in more detail.

Phase 3: 2036-2050 - Land contamination

Activities 14.10.73 Construction activities continue through Phase 3 of the DCO Project, but at a

reduced intensity from Phase 2 and focused in specific areas of the Site.

14.10.74 At the beginning of Phase 3, the earthworks, remediation, landscaping and material stockpiling are anticipated to be fully complete and there will be little to no soil exposed which may present a wind-borne risk to site receptors.

14.10.75 Operational maintenance and fuelling activities will be at their peak as the number of ATM’s increases to capacity. These activities will be similar to those of the existing Airport operations and the new maintenance and fuelling operations brought online in Phases 1 and 2, albeit increased in quantity.

Effects upon human health and controlled water receptors during construction and operational activities 14.10.76 Although the specific location of any potential effects resulting from construction

activities in Phase 3 will differ from those identified in Phases 1 and 2, the nature of the potential effects is generally expected to be similar to those identified in Phase 1.

14.10.77 Given the peak construction activities occur during Phase 1, the assessment of effects in Phase 1 is considered to be most representative of the likely significant effects of the DCO Project and the assessments for construction activities in Phase 3 are therefore not repeated here for this PEIR assessment.

14.10.78 Similarly, whilst the operational activities in Phase 3 will be at their peak, the change in risk profile in terms of magnitude and likelihood of a spill is not considered to be significantly different from that identified in Phase 1 and the assessments for operational activities in Phase 3 are therefore not repeated here for this PEIR assessment.

14.10.79 As the details of Phase 3 are finalised for the submission in the ES, the assessment of the land contamination effects will be developed to consider the specific activities in this phase in more detail.



Phase 1: c. 2022-2026 - Agricultural land quality

Activities 14.10.80 No likely significant effects on agricultural land quality, soil or geodiversity will

occur due to operational activities. The likely significant effects only occur where land is either permanently or temporarily used for construction activities.

Effects on Best and Most Versatile agricultural land 14.10.81 Construction of the DCO Project will result in a maximum permanent loss of

approximately 1,068 ha of agricultural land. This is mapped as Grade 1 (659 ha), Grade 2 (106 ha), Grade 3 where there is no sub-division data available (144 ha), Grade 3a (49 ha), Grade 3b (79 ha) and Grade 4 (31 ha). The remaining land take is non-agricultural land or urban/industrial land totalling 2,166 ha.

14.10.82 Where the sub-division of Grade 3 land is unknown the land is treated, on a ‘worse case’ basis, as Grade 3a and hence BMV agricultural land. On this basis, the maximum amount of BMV agricultural land that would be lost is 958 ha (659 ha plus 106 ha, plus 144 ha and 49 ha). Using data for the Greater London Authority (GLA) area, this loss represents a maximum of 25.0% of the 3,825 ha of grades 1 and 2 BMV land within Greater London4 (that is to say, on a worse case basis, treating all grade 3 land within Greater London as 3b and therefore not BMV land so that the total quantum of BMV land is minimised and the percentage loss of BMV land through the DCO Project is maximised5).

14.10.83 Although not all the DCO Project falls within the GLA, it is considered to be the authority which has the most agricultural land being lost to the DCO Project and therefore the one which provides the best contextual data regarding the loss of BMV land.

14.10.84 Given the maximum possible loss of BMV at the authority level, this loss is assessed as being significant.

Effects on soils 14.10.85 Measures detailed in the draft CoCP and the draft MMP (which will be issued as

part of the application for development consent) will ensure that topsoil and subsoil will be retained or reused rather than be buried or sterilised by development. On this basis, there would be no/negligible loss of the valued topsoil and subsoil resource.

14.10.86 Measures detailed in the draft CoCP and draft MMP will ensure that the structure of soils will be maintained. The measures seek to prevent soil damage that may

4 Defra, (2005). Agricultural Land Classification (ALC) Statistics. Publisher unknown. 5 Great London Authority data does not distinguish land in grades 3a and 3b



occur due to inappropriate soil stripping, handling or storage, lack of soil aftercare or the use of heavy vehicles which can cause soil compaction or erosion. Furthermore, the environmental measures will, where appropriate, reinstate drainage to its previous condition. On this basis, it is therefore likely that the integrity of the soils will be maintained.

14.10.87 Given the loss of soils (topsoil and subsoil), if any, is negligible, and the structure and drainage of soils will remain unchanged, the effect on soils is therefore assessed as being not significant.

Effects on geodiversity 14.10.88 Given no valued geodiversity features have been identified within or adjacent to

the Site (i.e. there are no designated RIGS or LIGS present) that will be lost or damaged by the DCO Project, the effect on geodiversity is assessed as being not significant.

Phase 2: c. late 2026-2035 – Agricultural land quality 14.10.89 There are no effects on agricultural land quality, soils or geodiversity in this phase

of the DCO Project.

Phase 3: c. 2036-2050 – Agricultural land quality 14.10.90 There are no effects on agricultural land quality, soils or geodiversity in this phase

of the DCO Project.

Phase 1: c. 2022-2026 – Minerals safeguarding 14.10.91 The assessment of effects for minerals safeguarding has been undertaken using

the approach outlined in Appendix 14.2.

14.10.92 The detailed assessment of effects for each of the identified minerals safeguarding receptors is presented in Appendix 14.5 and summarised in this section.

Effects on permitted minerals sites (quarries)

Sipson Quarry (Sipson Farm) 14.10.93 Sipson Quarry was granted permission in 2017 to extract 100,000 tonnes of sand

and gravel by September 2019. No information is available on what has been extracted to date, and the site therefore has been identified as having a high sensitivity as a permitted site with substantial reserves. It is expected that the site will have completed working by September 2019, prior to the commencement of the DCO Project, and the 100,000 tonnes will have been exhausted. The DCO



Project will therefore have no effect on this receptor and is consequently assessed as being not significant.

Harlington Quarry 14.10.94 Harlington Quarry has a current planning permission with up to 350,000 tonnes of

sand and gravel remaining on the site. A high level of sensitivity is therefore identified. The planning permission will lapse in November 2019, and the DCO Project would see habitats developed on the land as mitigation for effects on European Protected species. As such it is likely that the sterilisation of the remaining resources would be permanent. This would be a high magnitude of change which would result in a major and therefore significant effect.

Poyle Quarry 14.10.95 Poyle Quarry has a valid planning permission for the extraction of 800,000 tonnes

of sand and gravel. The western end of Poyle Quarry is proposed to accommodate mitigation measures for European protected species. A high level of sensitivity if therefore identified. Unless the prior extraction of the reserves in this area is undertaken, the proposed works are likely to permanently sterilise the resource as the habitats provided would be difficult to remove in the future to allow extraction. Further assessment is required in terms of the phasing of works at Poyle Quarry, and the proposed timing of the mitigation works within the DCO Project to see if prior extraction is feasible. Until that is completed, a worst-case scenario is identified for this PEIR where minerals will be sterilised. This would be a high magnitude of change which would result in a major and therefore significant effect.

Horton Brook Quarry

14.10.96 Horton Brook Quarry was granted permission in 2008 and is estimated to have around 200,000 tonnes of sand and gravel remaining to be extracted. It has therefore been identified as having a high sensitivity. Extraction is due to be completed by 2023 and Heathrow works will commence in c. 2022, and could only affect the final year of extraction. It is not clear whether any Heathrow works will commence within the site area in this period but if they do, the nature of the works (watercourses and flood storage) should be able to be implemented around the minerals extraction. This would be a negligible magnitude of change which would result in a minor and not significant effect.

Homers Farm 14.10.97 Homers Farm was a preferred area for extraction in the adopted Surrey Minerals

Plan (Primary Aggregates DPD, Preferred Area G). As detailed in Section 14.3,



Homers Farm was granted permission in 2015 for the extraction of 750,000 tonnes with works to be completed by September 2020. It has therefore been identified as having a high sensitivity. Working is expected to be completed by 2020 and all reserves on the 8.17ha site will be exhausted, prior to the start of works on the DCO Project. The DCO Project will therefore have no effect on this receptor and is consequently assessed as being not significant.

Richings Park 14.10.98 Richings Park was granted permission in 2017 for the extraction of 2 million

tonnes of sand and gravel over a 5 year period. It has therefore been identified as having a high sensitivity. The proposed works would see drainage / flood attenuation provided along the route of a watercourse running along the western boundary of the site. It is expected that extraction works will have been completed prior to any Heathrow related development occurring, but if not, the proposed works should not lead to any sterilisation of minerals. This would be a negligible magnitude of change which would result in a minor and not significant effect.

Effects on Minerals Preferred Areas

Land North of Harmondsworth (A) 14.10.99 Land North of Harmondsworth (adjacent to Saxon Lake) is identified as a preferred

area in the London Borough of Hillingdon Local Plan Part 1 as a 17 hectare site with around 750,000 tonnes of sand and gravel resource. It is therefore identified as having high sensitivity. The land is proposed for watercourses and flood storage uses. These activities are likely to require some degree of prior extraction of sand and gravel, but it is currently unclear how this material would be used. A worst-case scenario is therefore considered for this PEIR where the sand and gravel would be sterilised. This would lead to a high magnitude of change and a major and therefore significant effect.

Land to the west of Harmondsworth Quarry 14.10.100 Land to the west of Harmondsworth Quarry is identified as a preferred area in the

London Borough of Hillingdon Local Plan Part 1 as a 45 hectare site with around 2.2 million tonnes of sand and gravel resource. It is therefore identified as having high sensitivity. The land is proposed for Airport operations, with substantial underground structures. watercourses and flood storage uses. Parts of the preferred area would also be utilised as borrow pits, but sand and gravel would be sterilised in other areas. A worst-case scenario is therefore considered for this PEIR where sand and gravel would be sterilised. This would lead to a high magnitude of change and a major and therefore significant effect.



King George VI Reservoir

14.10.101 King George VI Reservoir is identified in the Surrey Minerals Core Strategy as a 178 hectare site (Preferred Area H) with around 3.24 million tonnes of sand and gravel resource. It is therefore identified as having high sensitivity. The land is outside of the Site boundary, but close to a range of activities within the DCO Project. These include community facilities to the west which would have no impact on minerals extraction. To the north a range of built development is proposed, although between the reservoir and the DCO Project there is currently residential, industrial and waste management land uses. The reservoir also forms part of the Staines Moore Site of Special Scientific Interest (SSSI). It is therefore not considered that the DCO Project would lead to a substantially greater risk of indirect sterilisation than the current land uses in this area. A negligible magnitude of change has therefore been identified, which would lead to a minor effect on the mineral deposit itself which is not significant.

14.10.102 It is also noted that comments from Surrey County Council and Spelthorne Borough Council identify that the Hithermoor Quarry site to the northwest of the reservoir, which currently hosts an aggregate recycling facility and a soil remediation facility, is the preferred location for the processing of sand and gravel should extraction commence from the reservoir. The land at Hithermoor Quarry would be within the DCO Project boundaries and lost to development. If alternative processing facilities were not available, this could also sterilise the resources at the reservoir.

14.10.103 However, the Surrey Minerals Plan notes that an assessment of the effect of, amongst other things, conveying material to Hithermoor Quarry for processing and the Staines Moore SSSI is required before planning permission could be granted for extraction the reservoir. On this basis, the use of Hithermoor Quarry is not guaranteed should this preferred site be brought forward after the DCO Project has commenced and therefore the DCO Project would not necessarily sterilise the mineral resources at the reservoir through development on the Hithermoor Quarry site.

14.10.104 Further assessment of this issue will be undertaken for the ES, in conjunction with Chapter 18 and Chapter 20.

Effects on minerals safeguarded areas

Thorney Mill rail depot 14.10.105 Thorney Mill is a rail depot for aggregates and is safeguarded in the

Buckinghamshire Minerals and Waste Core Strategy DPD from development which would impede its use. It therefore has a high sensitivity. The rail depot is outside of the Site but adjacent to land proposed for flood storage uses. These are



unlikely to have any meaningful impact on the ability of the site to continue as an aggregates rail depot. A negligible magnitude of effect is therefore identified, which would lead to a minor and therefore not significant effect.

Buckinghamshire sand and gravel safeguarding area 14.10.106 The Buckinghamshire Minerals Core Strategy identifies a safeguarding area for all

sand and gravel deposits which extends up to the Buckinghamshire boundary in the north west of the DCO Project. This area has a high sensitivity. Land within the DCO Project and within the safeguarding area is proposed for flood storage uses. A borrow pit is proposed within one section of this land, and elsewhere these activities are likely to require some degree of prior extraction of sand and gravel. However, it is currently unclear how this material would be used. A worst case scenario is therefore considered for this PEIR where the sand and gravel would be sterilised. This would lead to a high magnitude of change and a major and therefore significant effect.

Surrey sand and gravel safeguarding areas 14.10.107 The Surrey Minerals Plan identifies safeguarding areas for all sand and gravel

deposits and these include land close to the northern boundary of Surrey some of which is within the DCO Project. These areas have a high sensitivity. Land within the DCO Project and within the safeguarding area is proposed for flood storage uses. This use is likely to require some degree of prior extraction of sand and gravel. However, it is currently unclear how this material would be used. A worst case scenario is therefore considered for this PEIR where the sand and gravel would be sterilised. This would lead to a high magnitude of change and a major and therefore significant effect.

Joint Central and Eastern Berkshire safeguarding area 14.10.108 A Safeguarding Area is proposed in the Joint Central and Eastern Berkshire

Consultation Draft of the Minerals Local Plan which covers all sand and gravel deposits in that area. Although at consultation stage and not yet adopted the proposed designation does indicate sand and gravel deposits are located in this area. These areas have therefore been given a high sensitivity. These areas extend up to the Windsor and Maidenhead boundary in the south west of the DCO Project. Land within the DCO Project and within the safeguarding area is proposed for flood storage uses. These uses are likely to require some degree of prior extraction of sand and gravel. However, it is currently unclear how this material would be used. A worst case scenario is therefore considered for this PEIR where the sand and gravel would be sterilised. This would lead to a high magnitude of change and a major and therefore significant effect.



Effects on sites identified as possible future minerals extraction areas

14.10.109 All of the sites in this section are located on the Site and have been identified as containing sand and gravel deposits which have not previously been worked but have the potential to be of interest for extraction in the future. Whilst none of the land is subject to any planning permission or designation supporting extraction, nor is it subject to a safeguarding policy, the sites have been assessed as a worst case taking into account the potential for future mineral resource requirements.

North of Skyport Drive 14.10.110 Land is identified north of Skyport Drive which is around 7.5 hectares in size and

could contain around 400,000 tonnes of sand and gravel. It is identified as having a low sensitivity. The land is proposed for Airport operations, with substantial underground structures. Part of the land would be used as a borrow pit but it is unclear what would happen with the remaining sand and gravel. A worst case scenario is therefore considered for this PEIR where the sand and gravel would be sterilised. This would be a high magnitude of change which would create a moderate and therefore significant effect.

Car park east of Cranford Lane 14.10.111 Land is identified east of Cranford Lane which is around 10 hectares in size and

could contain around 560,000 tonnes of sand and gravel. It is identified as having a low sensitivity. The land is currently used for car parking and also proposed for car parking. It is possible the existing hard surfacing could be removed and replaced, opening up the opportunity for sand and gravel extraction, but it is considered more likely that hard standing will remain in situ and the minerals deposit would remain sterilised. This would be a high magnitude of effect, which would create an overall moderate and therefore significant effect.

Cranford Park 14.10.112 Land is identified at Cranford Park which is around 27 hectares in size and could

contain around 1.1 million tonnes of sand and gravel. It is identified as having a low sensitivity. No development is proposed within the site. Neighbouring development would create mitigation habitat for European protected species and is likely to increase the sensitivity of the surrounding area from an ecological point of view, but not to a degree that should sterilise minerals extraction. This would lead to a low magnitude of change, which would create a minor effect which is not significant.



Sipson Lane West / Sipson Recreation Ground

14.10.113 Land is identified at Sipson Recreation Ground which is around 6 hectares in size and could contain around 300,000 tonnes of sand and gravel. It is identified as having a low sensitivity. No development is proposed within the site, but neighbouring development is proposed for Airport operations, with substantial underground structures. This is likely to lead to minerals extraction work being made unviable on the site which would lead to a high magnitude of change. This would create a moderate and therefore significant effect.

Ansell Garden Centre and land to south west 14.10.114 Land is identified around the Ansell Garden Centre which is around 6.7 hectares in

size and could contain around 300,000 tonnes of sand and gravel. It is identified as having a low sensitivity. The land is proposed for flood storage uses which are likely to require some degree of prior extraction of sand and gravel. However, it is currently unclear how this material would be used. A worst case scenario is therefore considered in this PEIR where the sand and gravel would be sterilised. This would lead to a high magnitude of change, which would create a moderate and therefore significant effect.

Land North of Harmondsworth (B) 14.10.115 Land is identified to the north of Harmondsworth, adjacent to Saxon Lake, some of

which is included as preferred area above (Land North of Harmondsworth (A)) and not considered again here. The remainder of the land is around 13 hectares in size and could contain around 1 million tonnes of sand and gravel. It is identified as having a low sensitivity. The land is proposed for flood storage uses which are likely to require some degree of prior extraction of sand and gravel. However, it is currently unclear how this material would be used. A worst case scenario is therefore considered in this PEIR where the sand and gravel would be sterilised. This would lead to a high magnitude of change, which would create a moderate and therefore significant effect.

Bedfont Court

14.10.116 Land is identified at Bedfont Court in a Compulsory Purchase Order application from 1996 for the development of an access road from the M25. This application identified that sand and gravel resources existed on the land. The access road has been constructed and there is potential for some of the land in question to be available for future extraction. No permission or policy designations however support this. It is identified as having a low sensitivity. This plot of land is expected to house major built development for Airport operations. Unless prior extraction is undertaken then the proposed development would see sand and gravel sterilised.



This would lead to a high magnitude of change, which would create a moderate and therefore significant effect

Phase 2: c. late 2026-2033 – Minerals safeguarding 14.10.117 Any effects identified in Phase 1 are expected to continue through Phase 2 and

the assessments are therefore not repeated here.

Phase 3: c. 2034-2050 – Minerals safeguarding 14.10.118 Any effects identified in Phases 1 and 2 are expected to continue through Phase 3

and the assessments are therefore not repeated here.

14.11 Preliminary assessment of significance

14.11.1 The significant effects remaining once all the environmental measures detailed in Section 14.5 have been taken into consideration are presented in Table 14.20.



Table 14.20: Summary of significance of positive and negative effects

Receptor and effect Sensitivity / importance or value

Assessment of Effects

Significance Summary rationale

Land Contamination

Phase 1, 2 and 3: Construction activities

Human health – recreational users of land or occupants of commercial and residential properties adjacent to contamination sources and construction activities via windblown dust migration.

Low to high Neutral Not significant

Draft CoCP and embedded design measures – construction works would require extensive dust control measures as part of construction best practice, for example, covering contaminated materials, damping down of excavations and stockpiles, wheel washes. Haul routes and disposal or treatment sites chosen to minimise effects on adjacent sensitive land users. Advance investigation to refine earthworks strategy and minimise volume materials requiring excavation.

Human health – recreational users of land, road users, or occupants of commercial and residential land adjacent to contamination sources and construction activities via vapour migration.

Low to high Minor adverse

Not significant

Draft CoCP and embedded design measures – advance investigation and remediation where necessary. Use of knock down spray and material management to reduce exposure times. Haul routes and disposal or treatment sites chosen to minimise effects on adjacent sensitive land users.

Human health – recreational users of land, road users, or occupants of commercial and residential land adjacent to contamination sources and construction activities via landfill gas migration

Low to high Minor adverse

Not significant

Draft CoCP and embedded design measures – advance investigation and remediation where necessary. Use of knock down spray and material management to reduce exposure times. Haul routes and disposal or treatment sites chosen to minimise effects on adjacent sensitive land users.






Property/built environment receptors – chemical attack on concrete or buried services by existing contamination and ground instability from new construction on existing infrastructure

Low Neutral Not significant

Draft CoCP measures – advance investigation and remediation where necessary Foundation design and construction methodology will account for geohazards and ground instability on new infrastructure and impact of construction on existing infrastructure

Construction workers – direct contact, ingestion and inhalation pathways resulting from construction activities on landfills or other potentially contaminated sites

Low to high Neutral Not significant

CDM Regulations and safe working practices as part of construction health and safety management under the Health and Safety at Work Act (1974) and regulations made under the Act. Control measures embedded through the draft CoCP.

Controlled waters (surface water and superficial deposits) – mobilisation of contamination during construction on landfills or other potential contaminated sites

High Moderate to Major beneficial

Significant (positive)

Draft CoCP construction control measures in place. Advance investigation and remediation where necessary. Earthworks and dewatering will remove significant contaminant mass from the environment. New rivers will be hydraulically disconnected from groundwater breaking SPR linkage.

Controlled waters (surface water and superficial deposits) – new contaminant sources from reinstatement of borrow pits as landfills

High Minor adverse

Not Significant

New landfills permitted by Environment Agency and designed to best practice in line with Landfill Directive.

Controlled waters (Chalk Aquifer) – migration of contamination through new preferential pathways introduced by piling through base London Clay

High to very high

Neutral Not Significant

North West Runway and infrastructure piling does not extend below base of London Clay which has large thickness as overlying protection. Construction methods design to reduce risks from piling.






Controlled waters (Chalk Aquifer) – migration of contamination through new preferential pathways introduced by installing non-potable water or thermal energy supply boreholes into the Chalk Aquifer

High to very high

Neutral to minor adverse

Not Significant

Use of best practice drilling techniques (in particular the use of environmental seals) and siting of boreholes away from land affected by contamination (such as landfill sites) reduces risks from creation of preferential pathways from borehole drilling.

Controlled waters (surface water and superficial deposits) – contamination from accidental spillages and leaks from fuel storage and maintenance of construction vehicles

High Neutral to minor adverse

Not Significant

Draft CoCP measures and best practice for construction operations require measures to control contaminative activities, for example refuelling on hardstanding and bunding for fuel storage.

Phase 1, 2 and 3: Operational activities

Human health – existing Airport workers and users in the newly completed infrastructure buildings via landfill gas or vapour migration.

Low to moderate

Neutral to moderate beneficial

Significant (positive)

Completed design measures – for example remediation of land affected by contamination, provision of cover systems or installation of gas and vapour protection measures.

Human health – recreational users of nearby land, road users, or occupants of commercial and residential land via landfill gas, vapour or dust migration

Low to high Neutral to minor beneficial

Not significant

Completed design measures – for example remediation of land affected by contamination, provision of cover systems or installation of gas protection measures (where appropriate).

Property/built environment receptors – chemical attack on concrete or buried services by existing contamination

Low to high Neutral to minor beneficial

Not significant

It is likely that many of the previously existing services and foundations will have been removed and replaced with those designed for the prevailing conditions either currently or following remediation.

Controlled waters (surface water and superficial deposits) –

High Neutral Not Significant

Ground investigation to inform design and reuse of materials. Draft CoCP measures require






migration of contamination or leachate from inappropriate reuse of soils or landfill materials during construction

MMP which includes suitable for reuse criteria to be adopted with recording and validation of construction works to reuse materials

Controlled waters (surface water and superficial deposits) – contamination from accidental spillages and leaks from fuel storage and maintenance of operational vehicles

High Neutral to minor adverse

Not Significant

Extension of existing operational control measures to control contaminative activities, for example refuelling on hardstanding and bunding for fuel storage. Embedded environmental measures mean new fuel offloading and storage facilities designed to best practice and with appropriate containment for fuel loss

Agricultural Land Quality

Phase 1: Construction activities

BMV agricultural land: Permanent loss of BMV agricultural land

High High Significant (negative)

The permanent loss of a maximum of 958 ha represents a maximum of 25.0% of BMV agricultural land in Greater London Authority.

Soils: Permanent loss of topsoil and subsoil

High None/negligible

Not significant

Measures detailed in the draft CoCP, MMP and Soil Resource Plan will prevent the loss of topsoil and subsoil

Soils: Damage to soil structure or function

High None/negligible

Not significant

Measures detailed in the draft CoCP, MMP and Soil Resource Plan will protect soil structure from damage and retain soil drainage.

Geodiversity: Permanent loss of or damage to existing geodiversity sites (RIGS/LIGS)

Low None Not significant

No national or locally valued geodiversity sites are present.

Phase 1: Operational activities

Not significant – No likely significant effects on agricultural land quality, soil or geodiversity will occur due to operational activities. The likely significant effects only occur where land is either permanently or temporarily used for construction activities

Phase 2 and 3: Construction and Operational activities






Not significant – There are no effects on agricultural land quality, soils or geodiversity in these phases of the DCO Project


Phase 1, 2 and 3: Construction activities

Permitted sites Sipson Quarry, Horton Brook Quarry, Homers Farm, Richings Park Harlington Quarry, Poyle Quarry

High High

No effect to negligible High

Not Significant Significant (negative)

Sites permitted for extraction and where extraction will be complete prior to the start of the DCO Project. Sites permitted for extraction and where extraction will either not be complete prior to the start of the DCO Project or it has been assumed in this PEIR as a worst case scenario that the minerals will be sterilised.

Preferred Areas Land North of Harmondsworth (A), Land to the west of Harmondsworth Quarry King George VI Reservoir

High High

High Negligible

Significant (negative) Not Significant

Preferred areas identified in local or county level minerals strategies which will be sterilised (or have been assumed in this PEIR as a worst case scenario will be sterilised) by the DCO Project Preferred area identified in county level minerals strategy which is not directly sterilised by the DCO Project.

Safeguarded Areas Thorney Mill Rail Depot Buckinghamshire Sand and Gravel Safeguarding Area, Surrey Sand and Gravel Safeguarding Area, Joint Central and Eastern Berkshire Safeguarding Area

High High

Negligible High

Not Significant Significant (negative)

Safeguarded rail depot which is not directly or indirectly affected by the DCO Project Safeguarded areas for all sand and gravel deposits at county level where borrow pits are proposed as part of the DCO Project and it has been assumed in this PEIR as a worst case scenario that minerals will be sterilised






Possible Future Extraction Areas North of Skyport Drive, Sipson Lane West / Sipson Recreation Ground, Car Park east of Cranford Lane, Ansell Garden Centre, land to south west, Land North of Harmondsworth (B) and Bedfont Court Cranford Park, Land to rear of Western International Market

Low Low

High Low

Significant (negative) Not Significant

Sites which have not previously been worked and have the potential to be of interest for extraction in the future. The DCO Project will sterilise the deposits or it has been assumed in this PEIR as a worst case scenario that the minerals will be sterilised. Sites which have not previously been worked and have the potential to be of interest for extraction in the future. The DCO project will not directly or indirectly sterilise the deposits.

Phase 1, 2 and 3: Operational activities

The likely significant mineral safeguarding effects in the operational phase have been assessed as part of the construction phase.



14.12 Assessment of cumulative effects

Introduction 14.12.1 The cumulative effects assessment (CEA) presented in this section reflects

Stage 3 in the CEA process set out in Section 5.8 of Chapter 5.

14.12.2 The assessment of cumulative land quality effects is based on professional judgement, taking into account the levels of significance identified in the primary or ‘stand-alone’ assessment, and identifying whether effects could be different when ‘other development’ are considered.

14.12.3 For land contamination, a CEA is only undertaken for human health and controlled waters receptors that are likely to experience effects during construction in the primary assessment. This is because UK legislation requires sites to suitable for the proposed use in which risks to human health and controlled waters from land contamination have been managed. Therefore, the extent to which human health and controlled waters receptors may be cumulatively affected by the DCO Project and these ‘other developments’ is limited to construction activities which could result in the mobilisation of contamination (for example through generation of dusts, spillages and leaks etc).

14.12.4 For agricultural land quality, a CEA is only undertaken for those receptors that are likely to experience effects greater than negligible in the primary assessment. This is because such effects are unlikely to result in any discernible positive or negative effects on a receptor and therefore they are extremely unlikely to result in a significant cumulative effect, even if multiple effects of a similar significance are considered. In addition, there are no effects on geodiversity sites which could be subject to cumulative effects from other developments.

14.12.5 For minerals safeguarding, a CEA is only undertaken for those receptors that are likely to experience effects greater than no effect in the primary assessment since any effect that receptor would experience would come wholly from the other developments identified.

14.12.6 The following sections present the assessment of the cumulative effects of the DCO Project and ‘other developments’ on land quality. Effects are described for each phase of the DCO Project where relevant.

14.12.7 The ‘other developments’ to be considered in the CEA for the PEIR are those listed on the ‘assessment list’ provided in Chapter 5, Section 5.8.

14.12.8 Only those developments in the ‘assessment list’ that fall within the CEA ZOIs for land contamination, agricultural land quality and minerals safeguarding have the potential to result in cumulative effects with the DCO Project. These three ZOIs (Land Contamination ZOI, Agriculture ZOI and Minerals ZOI) are shown in



Chapter 5, Figure 5.1, Volume 2. All developments on the ‘assessment list’ falling outside the three ZOIs are excluded from this assessment and are indicated in Table 14.22.

14.12.9 Additional land quality screening criteria have been employed to further screen developments in the ‘assessment list’. This has ensured that only developments of a scale and nature that could result in likely significant cumulative effects related to land quality are included in the CEA. The land quality screening criteria are set out in Table 14.21.

14.12.10 This screening stage will also be applied to the ES CEA, in order to screen the shortlist of developments and identify those that have the potential to result in likely significant cumulative effects and therefore require assessment in the land quality chapter.

Table 14.21: Land quality CEA screening criteria

Aspect CEA screening criteria Rationale

Land contamination

None proposed All development within the Land Contamination ZOI has the potential to introduce either additional contaminant sources or additional sensitive receptors requiring assessment.


Only include developments with a redline boundary greater than 20ha (or potentially greater than 20ha where the redline boundary area is not provided in a planning application form) Exclude developments within the existing Airport boundary

A redline boundary of 20ha has been selected based on professional judgement as to the scale of developments which could result in a significant cumulative loss of BMV land noting that this value is used in the Natural England (2018) guidance as a threshold for ‘smaller losses’ and above which more detailed advice is required. Developments within the existing Airport boundary are excluded on the basis that these do not result in the loss of any agricultural land.


Exclude permitted minerals extraction sites where there is no change in the extent of the development boundary

The permitted minerals extraction sites are safeguarding receptors in their own right and are not additional development sites where there is no change in the extent of extraction (for example planning applications to introduce new equipment or extend the permitted timescale of extraction).

14.12.11 Following application of the land quality CEA screening criteria, the following core and optional developments on the assessment list in Section 5.8 of Chapter 5 brought forward for assessment in the CEA are shown in Table 14.22.



Table 14.22: Developments brought forward for CEA

‘Assessment list’ developments from Chapter 5, Section 5.8

Land contamination



O109 Land at Harmondsworth, Holloway Close x2

O591 Rectory Lane, Cranford Lane x1

O595 Stanwell Recycling, Stanwell Quarry x2

O596 Stanwell Recycling, Stanwell Quarry x2

O601 Queen Mary Reservoir and Land West of Queen Mary Reservoir x1 x1

O608 Cemex Datchet Quarry, Land at Riding Court Farm

x1

O609 Land East of Horton Road x1

O615 Southall Gas Works x1 x1

O732 Queen Mary Reservoir and Land West of Queen Mary Reservoir

x1

O745 Land at Milton Park Farm x1 x1

O750 Land at Watersplash Farm x1 x1

O751 Slough Heat & Power Station x1 x1 x1

O810 M4 Junctions 3 to 12 Smart Motorway x2

O811 High Speed 2 (London - West Midlands) x1 x1 x1

O812 Western Rail Link to Heathrow

O813 Southampton to London Pipeline Project x1 x1

A2: T5+ (T5A) x2

A3: T5+ (T5B) x2

A4: T5+ (T5C) x2

A5: Perry Oaks Fuel Farm x2

Notes: 1 Development screened out as falls outside of the relevant Land Contamination ZOI, Agriculture ZOI or Minerals ZOI 2 Development screened out as falls within the relevant Land Contamination ZOI, Agriculture ZOI or Minerals ZOI, but does not meet land quality CEA screening criteria

Phase 1: c. 2022-2026 14.12.12 Table 14.23 sets out the assessment of cumulative effects on relevant receptors

identified in Section 14.4 during Phase 1.



Phase 2: c. late 2026-2033 14.12.13 For land contamination, given the peak construction activities for the DCO Project

occur during Phase 1, the assessment of cumulative effects in Phase 1 is considered to be most representative of the likely significant cumulative effects of the DCO Project and other developments are therefore not repeated here for this PEIR assessment.

14.12.14 There are no cumulative effects on agricultural land quality in this phase of the DCO Project as for this PEIR, all of the loss/change effects related to land take/land cover (such as topsoil stripping and loss of agricultural land) have been assumed to occur at a single point in time at the start of the Phase 1 of the DCO Project.

14.12.15 For minerals safeguarding, any cumulative effects identified in Phase 1 are expected to continue through Phase 2 and the assessments are therefore not repeated here.

Phase 3: c. 2034-2050 14.12.16 For land contamination, given the peak construction activities for the DCO Project

occur during Phase 1, the assessment of cumulative effects in Phase 1 is considered to be most representative of the likely significant cumulative effects of the DCO Project and other developments are therefore not repeated here for this PEIR assessment.

14.12.17 There are no cumulative effects on agricultural land quality in this phase of the DCO Project as for this PEIR, all of the loss/change effects related to land take/land cover (such as topsoil stripping and loss of agricultural land) have been assumed to occur at a single point in time at the start of the Phase 1 of the DCO Project.

14.12.18 For minerals safeguarding, any cumulative effects identified in Phases 1 and 2 are expected to continue through Phase 3 and the assessments are therefore not repeated here.



Table 14.23: Phase 1 CEA of DCO Project-wide effects, and DCO Project-wide effects with ‘other developments’ unrelated to the DCO Project

Receptor / effect

DCO Project effects

Assessment of cumulative effect (DCO Project effects together with ‘other developments’)

Land contamination

Human Health and Controlled Waters receptors: mobilisation of contamination during construction (for example through generation of dusts, spillages and leaks, earthworks on land affected by contamination etc)

Minor adverse (not significant) effects, neutral or significant (beneficial) effects

The developments taken forward for the land contamination CEA principally comprise extensions to existing minerals extraction sites which are being restored through backfilling with inert landfill materials and capping with clean soils (O109 and O591), ongoing material recycling facility operations (O595 and O596) or developments to the existing airfield operations including expansion of terminal buildings (A2 to A4) and expansion of the existing fuel farm (A5). All of these developments have an existing Environmental Permit issued by the Environment Agency which is designed to manage and reduce potential pollution, monitor compliance with permit conditions and promote environmental standard practice in operation of the activities covered by a permit. In addition, planning permission required to develop the sites will ensure that remediation is carried out, where required, to ensure the site is suitable for the proposed use and risks to human health and controlled waters have been managed. On this basis, it is considered that these developments do not have the potential to result in any cumulative effects and the effects on human health and controlled waters receptors remain as identified in the primary assessment.

1. O810 M4 Junctions 3 to 12 Smart Motorway 2. O812 Western Rail Link to Heathrow

These developments are DCO projects which include environmental measures to manage land contamination risks during construction and operation, including measures for remediation to be carried out, where required, to ensure the sites are suitable for the proposed use and risks to human health and controlled waters have been managed. Furthermore, the linear nature of the other development projects means that the areas of these developments that fall within the Land Contamination ZOI is limited. Therefore, the extent to which human health and controlled waters receptors may be cumulatively



Receptor / effect

DCO Project effects


affected by the DCO Project and these other developments is also limited when compared to the overall works required to enable these other developments. Taking these points into account, these other developments are unlikely to have the potential to result in any cumulative effects and the effects on human health and controlled waters receptors remain as identified in the primary assessment.


BMV agricultural land: Permanent loss of BMV agricultural land

Significant adverse effect as a result of the permanent loss of a maximum of 958ha of BMV agricultural land

The following developments also have the potential to affect BMV agricultural land: 1. O591 Rectory Lane Cranford Lane: There will be a loss of 41ha of BMV agricultural land at the start of construction. Together with the DCO Project, there will be a decrease in the amount of BMV land available for use in the local area. The cumulative effect of a loss of 999ha of BMV agricultural land, is significant adverse. 2. O745 Land at Milton Park Farm: There will be a loss of 45ha of BMV agricultural land at the start of construction. Together with the DCO Project, there will be a decrease in the amount of BMV land available for use in the local area. The cumulative effect of a loss of 1,003ha of BMV agricultural land, is significant adverse. 3. O811 High Speed 2 (London - West Midlands): The ES for the Colne Valley part of this development (which is within the Agriculture ZOI for the DCO Project) reports a loss of approximately 84ha of BMV agricultural land, which is considered a significant effect in the ES. Consequently, the cumulative effect with the DCO Project (a loss of 1,042ha) is also significant adverse. The following developments also have the potential to affect BMV agricultural land, however the total loss cannot be quantified: 1. O812 Western Rail Link to Heathrow 2. O813 Southampton to London Pipeline Project: Boorley Green to West London Terminal in Hounslow These two developments occur mainly below ground with some above ground land take associated with construction compounds or permanent infrastructure. It is assumed that temporary construction land take would be restored to its former condition as part of the environmental measures embedded within the DCO’s for these other developments. Therefore, only the permanent land take would contribute to



Receptor / effect

DCO Project effects


potentially significant cumulative effects. No details of the quantum of agricultural land lost to these developments is available at this stage and, if it becomes available, further information will be obtained and reported in the ES, to determine the potential cumulative effects. However, it is noted that in any event, the conclusions of the primary assessment (significant adverse effect) would remain unchanged. The other developments taken forward for assessment do not have the potential to result in any cumulative effects as they are sites which are either not on agricultural land or are already developed and therefore not used or available for agriculture. Although there are several developments that will/may, in the future, be restored to agriculture (for example O601, 608, 609, 732 and 750), a worse-case scenario is taken for the PEIR where future agricultural land restoration is not taken into consideration.


Land North of Harmonds-worth

A high sensitivity receptor, which would experience a high magnitude of effect, leading to a major and significant effect

The O810 M4 Smart Motorway works have the potential to affect the land north of Harmondsworth. However, the majority of the works will be within the existing motorway carriageway with limited land-take or effects on adjoining land. This should not create any substantial cumulative effects with the DCO Project. Cumulative effects are considered negligible, retaining a major and therefore significant effect from the primary assessment.

King George VI Reservoir

A high sensitivity receptor, which would experience a negligible magnitude of effect, leading to a minor and not significant effect

None of the developments taken forward for assessment have the potential to affect the King George VI Reservoir. Therefore, there are no cumulative effects on this receptor.



Receptor / effect

DCO Project effects


Surrey Sand and gravel safeguarding areas


The following developments have the potential to affect the Surrey sand and gravel safeguarding areas: O595: Stanwell Recycling O596: Stanwell Recycling

The proposed recycling of construction and demolition waste and soils is intended to provide sufficient materials to enable the completion of restoration works at a former quarry site. All extraction works have ceased at the former quarry and therefore no sand and gravel remains in-situ to be sterilised on this particular plot of land within the safeguarding area. These other developments located within the Minerals ZOI therefore do not have the potential to result in any cumulative effects and the effect remains as major and therefore significant.

Joint Central and Eastern Berkshire MLP S&G Safe-guarding Area


None of the developments taken forward for assessment have the potential to affect the Joint Central and Eastern Berkshire MLP Safeguarding Area. Therefore, there are no cumulative effects on this receptor.

Cranford Park A low sensitivity receptor, which would experience a low magnitude of effect, leading to a minor and not significant effect

The O810 M4 Smart Motorway works have the potential to affect Cranford Park as they are within 100m of the site. However, the M4 works are highly unlikely to result in any minerals sterilisation on the site, and it is therefore not anticipated that there will be any substantial cumulative effects. It is therefore considered that the cumulative development would result in a negligible magnitude of effect, retaining a minor and therefore not significant effect.

Sipson Lane West / Sipson Recreation Ground

A low sensitivity receptor, which would experience a high magnitude of effect, leading to a

None of the developments taken forward for assessment have the potential to affect the Sipson Lane receptors. Therefore, there are no cumulative effects on these receptors.



Receptor / effect

DCO Project effects


moderate and significant effect

Bedfont Court A low sensitivity receptor, which would experience a high magnitude of effect, leading to a moderate and significant effect

This plot of land is proposed to house major built development as part of the DCO Project. Unless prior extraction is undertaken then the DCO Project would see sand and gravel sterilised (noting that as a worst-case assumption, the assessment presented in this PEIR assumes the site will be sterilised). The proposed O812 Western Rail Link to Heathrow would see tunnels created under the Bedfont Court site with construction working areas above it. It is expected that construction of the Western Rail Link to Heathrow could also give rise to similar sterilisation effects as the DCO Project and would also lead to a high magnitude of effect. Unless a coordinated approach was taken to the two developments for the prior extraction and re-use of minerals, then it would be expected that minerals will be sterilised. It is therefore considered the cumulative effect would be high, which could give rise to a major cumulative effect which would be considered significant.



14.13 Consideration of additional environmental measures or compensation

14.13.1 No additional environmental measures are proposed to further reduce the land quality effects that are identified in this PEIR. This is because all relevant and implementable measures have been embedded into the DCO Project design and are assessed in this chapter.

14.13.2 This includes environmental measures associated with managing the risks from land contamination by embedding the CLR-11 process into the design of new development (and therefore ensuring sites are suitable for their proposed use), removal and reuse of topsoil and subsoil and prior extraction of sand and gravel mineral resources where practicable and feasible.

14.13.3 These measures are considered to be likely to be effective and deliverable, as well as address the likely significant effects of the DCO Project.

14.14 Next steps

Baseline data and assessment

Land contamination 14.14.1 Further work that will be undertaken to support the land contamination assessment

and presented within the ES is summarised as:

The desk study, which establishes the existing baseline conditions of the study area, will be finalised to take into account the final extent of the Site

Additional soil, groundwater, surface water and soil gas data will be obtained from the ongoing ground investigation and reported within a series of factual ground investigation and monitoring reports

Further holistic screening of the ground investigation data will be undertaken using the screening criteria presented in Appendix 14.1. In addition, a detailed asbestos assessment will be undertaken using the data obtained from the approach presented in Appendix 14.3. The outputs of the holistic screening and detailed assessments will be used to determine where further ground investigation or quantitative assessment may be required to determine whether there are potentially unacceptable risks to human health or controlled waters based on the site-specific end-use of sites within the DCO Project

Further assessment of the detailed construction and operational effects across Phases 1, 2 and 3 of the DCO Project



The CEA will be refined for the ES where additional information about the ‘other developments’ considered in this PEIR becomes available (for example if land contamination assessments are undertaken by the applicants of the ‘other developments’)

Where potentially unacceptable risks are identified, the requirement for additional environmental measures to those set out in Table 14.9 and Table 14.10 will be outlined. These may include additional environmental controls during construction (which would be documented in the draft CoCP) or a requirement for remediation to ensure sites are suitable for the proposed end-use (which would be documented in a remediation implementation plan in line with CLR-11)

A draft Materials Management Plan (MMP) will be prepared for engagement with stakeholders that outlines how excavated non-waste materials will be reused, where practicable and feasible, during the construction earthworks. The MMP will document the proposed chemical and geotechnical reuse screening criteria and material flows onsite, including how those material flows will be documented and verified. The draft MMP will be submitted as part of the application for development consent.

Agricultural land quality 14.14.2 The further work that will be undertaken to support the agricultural land quality

assessment and presented within the ES is summarised as:

The ongoing programme of detailed ALC field surveys for land currently in agricultural use and not covered by an existing detailed ALC field survey will continue in order to provide updated baseline data. Local plans will also be reviewed to identify any changes to RIGS/LIGS designations within the study area. The baseline description of agricultural land quality will then be updated accordingly for the ES

The CEA will be refined for the ES where additional information about the ‘other developments’ considered in this PEIR becomes available (for example if detailed ALC surveys are undertaken by the applicants of the ‘other developments’)

As the construction and operational activities are finalised, a greater understanding will be gained on how the agricultural land quality receptors will be affected, and whether the effects will be permanent or temporary. Together with updated baseline data and refinement of both the draft CoCP and other environmental measures, this will influence the evaluation of significance for agricultural land quality, soil and geodiversity receptors. The agricultural land quality assessment in the ES will be updated to account for these changes.




14.14.3 Further work that will be undertaken to support the minerals safeguarding assessment and presented within the ES is summarised as:

The current assessment in the PEIR makes an assumption that the effects on the receptors are likely to commence in Phase 1 and continue through Phase 2 and Phase 3. This is considered to be a robust approach for the PEIR as it provides a worst-case scenario assessment. As the details of Phases 1, 2 and 3 are finalised for the submission in the ES, the assessment of the minerals safeguarding receptors will be developed to consider the activities in the different phases in more detail

The PEIR includes an assessment of the direct and indirect effects on the sterilisation of minerals deposits from the DCO Project. However, there is also a consideration to be made about the direct effects on existing minerals business from displacement by the DCO Project (see Chapter 18). Consideration of direct and indirect effects (including sterilisation of minerals or the release of minerals from prior extraction works) on minerals businesses will be included in the assessment of effects presented in the socio-economics and employment and land quality chapters of the ES

The CEA will be refined for the ES where additional information about the ‘other developments’ considered in this PEIR becomes available (for example if additional minerals surveys or development plans are produced by the applicants of the ‘other developments’).

Scoping and engagement 14.14.4 Further engagement that will be undertaken to inform the land quality assessment

and presented within the ES is set out in Table 14.24.

Table 14.24: Areas of further engagement prior to ES

Consultee Areas of further engagement Environment Agency Draft Materials Management Plan including materials reuse criteria

Landfill permitting Land contamination screening of quantitative ground investigation data and remediation options, where required Management of asbestos in soils Agricultural land quality assessment Minerals assessment Environmental measures (including those incorporated in draft CoCP)

Heathrow Strategic Planning Group

Natural England Agricultural land quality assessment Environmental measures (including those incorporated in draft CoCP)

volume 1, chapter 14 - airport expansion consultation · 2020. 6. 19. · 14.2.1 this section...

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