A417 Missing Link TR010056

6.4 Environmental Statement Appendix 13.1 Water Legislative and Policy Framework

Planning Act 2008

APFP Regulation 5(2)(a) Infrastructure Planning (Applications: Prescribed Forms and Procedure) Regulations 2009

Volume 6

May 2021 A417 Missing Link | HE551505 Highways

Infrastructure Planning

Planning Act 2008

The Infrastructure Planning (Applications: Prescribed Forms and Procedure) Regulations 2009

Regulation 5(h)

A417 Missing Link

Development Consent Order 202[x]

6.4 Environmental Statement Appendix 13.1 Water Legislative and Policy Framework

Regulation Number: 5(2)(a) Planning Inspectorate TR010056 Scheme Reference Application Document Reference 6.4 Author: A417 Missing Link

Version Date Status of Version C01 May 2021 Application Submission A417 Missing Link | HE551505

Table of Contents Pages 1 Water legislation and policy framework i 1.1 Legislation i 1.2 National policy iii 1.3 Regional policy iv 1.4 Local policy, strategy and evidence iv 1.5 Guidance and standards vi References vii A417 Missing Link | HE551505 Highways England

1 Water legislation and policy framework

1.1 Legislation

The Environmental Permitting (England and Wales) (Amendment) (EU Exit) Regulations 20191 1.1.1 These came into force in accordance with the European Union (Withdrawal) Act 2018 on 31 December 2020, to ensure that The Environmental Permitting Regulations 2016 for England and Wales can continue to function. The Environmental Permitting Regulations 2016 are summarised in section 1.1.5.

The Environment (Amendment etc.) (EU Exit) Regulations 20192 1.1.2 These came into force in accordance with the European Union (Withdrawal) Act 2018 on 31 December 2020. Part 2 amends the following primary legislation of relevance to the water environment:  The Environmental Protection Act 1990 (summary provided in section 1.1.3)  The Environment Act 1995 (summary provided in section 1.1.4)

Environmental Protection Act 19903 1.1.3 The Environmental Protection Act 1990 makes provision to control pollution arising from industrial and other processes for waste management and is amended by The Environment (Amendment etc.) (EU Exit) Regulations 2019.

Environment Act 19954 1.1.4 The Environment Act 1995 sets new standards for environmental management, such as requiring national strategies for air quality and waste. It also deals with the establishment of the EA. It is amended by The Environment (Amendment etc.) (EU Exit) Regulations 2019.

The Environmental Permitting Regulations 20165 1.1.5 The Environmental Permitting (England and Wales) Regulations 2016 were amended in order to extend the requirement for an environmental permit to flood risk activities, in addition to polluting activities included under the previous regulations. The permitting requirements for flood risk activities allow the EA (as regulator for England) to concentrate on higher risk activities. The 2010 regulations revoked the 2009 Groundwater Regulations, which originally implemented the Groundwater Directive. It is amended by The Environmental Permitting (England and Wales) (Amendment) (EU Exit) Regulations 2019.

Water Resources Act 19916 1.1.6 In England and Wales, The Water Resources Act 1991 established the Environment Agency’s powers and duties for the protection of water resources, flood defence, fisheries, recreation, conservation and navigation. The Environment Agency is a key statutory consultee responsible for ensuring that a scheme does not adversely affect flood risk, water quality or the local water environment.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000036 | C01, A3 | 11/03/21 APPENDIX PAGE i A417 Missing Link | HE551505 Highways England

The Water Environment (Water Framework Directive) (England and Wales) Regulations 2017 (WFD)7 1.1.7 The Water Environment (Water Framework Directive) (England and Wales) Regulations 2017 aim to provide an integrated framework for the protection and restoration of the water environment through the delivery of actions set out in 11 River Basin Management Plans (RBMPs). Each River Basin District (RBD) comprises smaller management units known as water bodies, including all river, lake, groundwater, coastal and transitional waters located within that RBD.

Land Drainage Act 19918 1.1.8 The Land Drainage Act 1991 requires that a watercourse be maintained by its owner. The Act provides functions to internal drainage boards and local authorities to manage watercourses and provide consenting powers for proposed works to watercourses associated with development.

Water Act 20149 1.1.9 The Water Act 2014 amends the Water Resources Act 1991 and the Water Industry Act 1991 to make provision with respect to compensation under section 61 of the Water Resources Act 1991.

Water Resources (Abstraction and Impounding) Regulations 200610 1.1.10 The Water Resources (Abstraction and Impounding) Regulations 2006 contain provisions relating to the licensing of abstraction and impounding of water in England and Wales in the light of amendments made by the Water Act 2003 to the Water Resources Act 1991. The 2006 regulations have been updated by the Water Abstraction and Impounding (Exemptions) Regulations 2017.

The Water Abstraction and Impounding (Exemptions) Regulations 201711 1.1.11 The Water Abstraction and Impounding (Exemptions) Regulations 2017 contain circumstances where water abstractions and impounding works are exempt from licensing requirements.

Flood Risk Regulations 200912 1.1.12 The Flood Risk Regulations 2009 transpose the EC Floods Directive (2008/60/EC) on the assessment and management of flood risk into domestic law in England and Wales and implement its provisions. The regulations designate a Local Lead Flood Authority (LLFA) and impose duties on the EA and LLFAs to prepare a number of documents including:  preliminary flood risk assessments  flood risk and flood hazard maps  flood risk management plans

The Water Supply (Water Quality) Regulations 201813 1.1.13 The Water Supply (Water Quality) Regulations 2018 provide the framework for drinking water quality in England in respect of public supplies provided by water companies and licensed water suppliers. The Drinking Water Inspectorate, acting on behalf of the Secretary of State, enforces the legislation.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000036 | C01, A3 | 11/03/21 APPENDIX PAGE ii A417 Missing Link | HE551505 Highways England

Flood and Water Management Act 201014 1.1.14 The Flood and Water Management Act 2010 gives the EA a strategic overview of the management of flood and coastal erosion risk in England. In accordance with the Government’s Response to the Pitt Review, it also gives upper tier local authorities in England responsibility for preparing and putting in place strategies for managing flood risk from groundwater, surface water and ordinary watercourses in their areas.

The Environmental Damage (Prevention and Remediation) (England) Regulations 201515 1.1.15 These regulations are based on the ‘polluter pays’ principle and impose obligations on operators of economic activities requiring them to prevent, limit or remediate environmental damage. They apply to damage to protected species, natural habitats, sites of Special Scientific Interest (SSSI), water and land and implement directive 2004/35/EC, on environmental liability.

The Water Framework Directive (Standards and Classification) Directions (England and Wales) 201516 1.1.16 The WFD Directions present the updated environmental standards to be used in the second cycle of the WFD (2000/60/EC) river basin management planning process in England and Wales. Environmental standards help assess risks to ecological quality of the water environment.

The Groundwater (Water Framework Directive) (England) Direction 201617 1.1.17 The direction sets out instructions to the EA on obligations to protect groundwater, including requirements to monitor and set thresholds for pollutants, add new pollutants to the monitoring list and change the information reported to the European Commission.

The Conservation of Habitats and Species Regulations 2017 (the ‘Habitat Regulations 2017’)18 1.1.18 The Habitat Regulations 2017 ensure the conservation of a range of rare or threatened species.

1.2 National policy

National Policy Statement for National Networks (NPSNN)19 1.2.1 The NPSNN sets out the need and governmental policies for nationally significant rail and road projects for England. Sections 5.90 to 5.115 set out how flood risk impacts should be considered, whilst sections 5.219 to 5.231 cover the assessment of impacts to water quality and resources.

The National Planning Policy Framework 2019 (NPPF)20 1.2.2 The NPPF provides a framework within which local people and their accountable councils can produce their own distinctive local and neighbourhood plans. Section 14, titled “Meeting the challenge of climate change, flooding and coastal change” relates to flooding. The policy states that development should be directed away from areas at highest risk of flooding (both existing and predicted), however,

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000036 | C01, A3 | 11/03/21 APPENDIX PAGE iii A417 Missing Link | HE551505 Highways England

where necessary, the development must be safe, for the lifetime of the development, without increasing flood risk elsewhere.

Planning Practice Guidance (PPG)21 1.2.3 PPG details how to take account of and address the risks associated with flooding within the planning process. It also details how planning can ensure water quality.

1.3 Regional policy

Cycle 2 RBMPs 2015-2021 1.3.1 The proposed scheme spans the boundary between two RBDs, the Severn22, and the Thames23. These plans provide a framework for protecting and enhancing the benefits provided by the water environment. They also inform decisions on land use planning. Cycle 3 RBMPs are currently being prepared for introduction in 2021.

Flood Risk Management Plans (FRMPs) 2015-2021 1.3.2 The proposed scheme spans the boundary between two RBDs, the Severn24 and the Thames25. The FRMPs set out how organisations, stakeholders and communities will work together to manage flood risk.

1.4 Local policy, strategy and evidence

Gloucestershire Local Flood Risk Management Strategy 201426 1.4.1 Gloucestershire Local Flood Risk Management Strategy 2014 sets out how Gloucestershire County Council and its partner authorities intend to work together to manage flood risk. This strategy is supported by a live action plan which is reported on annually. This Local Flood Risk Management Strategy has been adopted to guide the development of policy and programmes across Gloucestershire County Council’s operations and in its work with other organisations, communities and stakeholders.

Level 1 Strategic Flood Risk Assessment (SFRA) for City Council 200827 1.4.2 A tool for planning authorities to identify and evaluate flood risk in their area with the aim of directing development to the areas of lowest risk of flooding.

Gloucestershire SuDS Design and Maintenance Guide 201528 1.4.3 The guide sets out Gloucestershire LLFA’s approach to sustainable drainage and aims to aid developers incorporate Sustainable Drainage Systems (SuDS) into their plans. Gloucestershire County Council takes a proactive approach to encourage the use of SuDS for the management of surface water.

Gloucestershire County Council: Flood Risk Assessment Guidance Note (March 2015)29 1.4.4 The guidance note is for Local Planning Authorities on Development and Flood Risk. The note details the main flood risk that should be considered and how climate change should be accounted for. The approach to management of surface water is detailed including description of how SuDS can manage surface

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000036 | C01, A3 | 11/03/21 APPENDIX PAGE iv A417 Missing Link | HE551505 Highways England

water run-off. Further considerations detailed include disposal to public sewer, designing for exceedance and developments that are part of a larger proposal.

Cotswold District Local Plan (2011-2031)30 1.4.5 The local plan sets out a number of policies with respect to the built, natural and historic environment, placing emphasis on promotion the protection, conservation and enhancement of the natural environment. Policy EN1 seeks to improve “water quality where feasible”. Policy EN4 directly links with the AONB Management Plan (2013-2018) and highlights the special qualities of the Cotswolds including river valleys forming headwaters of the Thames. 1.4.6 Development will not be permitted if it results in unacceptable risk to the natural environment including pollution of surface, or groundwater sources (Policy EN15). This policy also places requirements on the landowner/developer to undertake necessary remedial works on affected sites. 1.4.7 Policy EN14 – Managing Flood Risk: The policy states that development must avoid areas at risk of flooding in accordance with a risk-based sequential approach that takes account of all flooding sources. Minimising flood risk and providing resilience will be achieved by applying the sequential test, outlined in the section entitled ‘Flood Risk and Coastal Change’ of the Planning Practice Guidance; or requiring a SFRA. In addition, the design of development should account for flood risk management and climate change with SuDS. Developers could be required to fund flood management and/or mitigation measures and maintenance. 1.4.8 Policy INF8 – Water Management Infrastructure: The policy states that proposals should consider the impact on off-site water and wastewater infrastructure and make improvements where required. Additionally, proposals should not result in the deterioration of water quality and demand management measures should be implemented. SuDS should be incorporated where appropriate and pollution of groundwater sources should be avoided. The policy specifies further requirements for proposals in Source Protection Zone (SPZ) 1.

Gloucester, and , Joint Core Strategy 2011-203131 1.4.9 The Joint Core Strategy (JCS) is a partnership between Gloucester City Council, Cheltenham Borough Council, and Tewkesbury Borough Council. It presents a joint and coordinated strategic development plan up for 2011 to 2031 for the three authorities. It was adopted in December 2017. The plan strives for conservation, management and enhancement of the natural environment, and to maximise the opportunities to use land to manage flood water. Policy SD14: Health and Environmental Quality states that a new development must not result in unacceptable levels of water pollution with respect to national and EU limit values. 1.4.10 Policy INF2 - Flood Risk Management states development must accord with the sequential approach and increase risk of safety to occupier, community or wider environment. For strategic sites, the cumulative impact of development on flood risk in relation to existing settlements, communities and allocated sites must be assessed and mitigated. The policy sets out the requirements to reduce the risk of flooding and provide resilience to flooding while accounting for climate change.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000036 | C01, A3 | 11/03/21 APPENDIX PAGE v A417 Missing Link | HE551505 Highways England

Tewkesbury Borough Plan 2011-2031, Draft policies and site options for public consultation (Feb 2015)32 1.4.11 Consultation of the proposed draft policies closed in October 2018, however no final document has been published. The Tewkesbury Borough Plan, section K Landscape, Biodiversity and Nature, Policy ENV3 is aligned with the NPPF and the JCS with respect to protection of designated sites. 1.4.12 Section J – Flooding states that development proposals will be relying on NPPF Framework paragraphs 100, 101, 102, 103 and 104. The Joint Core Strategy – Policy INF3 should also be adhered to.

Cotswolds Area of Outstanding Natural Beauty (AONB) Management Plan 2018-202333 1.4.13 Sets out the vision, outcomes and policies for the management of the Cotswolds AONB in order to conserve and enhance the natural beauty of the Cotswolds AONB and increase the understanding and enjoyment of the special qualities of the AONB. 1.4.14 Policy CC6 – Water states water resources should be carefully managed and conserved to: improve water quality, ensure adequate aquifer recharge, ensure adequate river flows, and contribute to natural flood management systems and including sustainable drainage.

Tewkesbury Borough Council Flood and Water Management Supplementary Planning Document 201934 1.4.15 The document provides guidance for new developments to manage water environment and flood risk, including key objectives and a description of the documents required to accompany planning applications.

1.5 Guidance and standards 1.5.1 The assessment methodology is based upon LA 104 Environmental assessment and monitoring (LA 104)35 and LA 113 Road drainage and the water environment (LA 113)36. 1.5.2 Due reference has been made to GOV.UK guidance for preventing pollution37, working on or near water38 and for managing water on land39. 1.5.3 CIRIA guidance used for the assessment includes:  Control of Water Pollution from Construction Sites – Guide to Good Practice (SP156)  Control of Water Pollution from Construction Sites – Guidance for Consultants and Contractors (C532)  Control of Water Pollution from Linear Construction Projects – Technical Guidance (C648)  Control of Water Pollution from Linear Construction Projects – Site guide (C649)  Environmental good practice on site (C692)  Groundwater control: design and practice (second edition) (C750)  The SuDS Manual (C753)  Guidance on the construction of SuDS (C768)

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000036 | C01, A3 | 11/03/21 APPENDIX PAGE vi A417 Missing Link | HE551505 Highways England

References

1 UK Government (2019). Environmental Permitting (England and Wales) (Amendment) (EU Exit) Regulations 2019 [Online]. Available at: https://www.legislation.gov.uk/uksi/2019/39/contents/made (Accessed: 10/03/2021) 2 UK Government (2019). The Environment (Amendment etc.) (EU Exit) Regulations 2019 [Online]. Available at: https://www.legislation.gov.uk/ukdsi/2019/9780111176276/contents. (Accessed: 10/03/2021) 3 UK Government (1990). Environmental Protection Act 1990 [Online]. Available at: https://www.legislation.gov.uk/ukpga/1990/43/contents. (Accessed: 10/03/2021) 4 UK Government (1995). Environment Act 1995 [Online]. Available at: https://www.legislation.gov.uk/ukpga/1995/25/contents. (Accessed: 10/03/2021). 5 UK Government (2016). The Environmental Permitting (England and Wales) Regulations 2016 [Online]. Available at: https://www.legislation.gov.uk/uksi/2016/1154/contents/made. (Accessed: 10/03/2021) 6 UK Government (1991). Water Resources Act 1991 [Online]. Available at: https://www.legislation.gov.uk/ukpga/1991/57/contents. (Accessed: 10/03/2021). 7 UK Government (2017). The Water Environment (Water Framework Directive) (England and Wales) Regulations 2017 [Online]. Available at: https://www.legislation.gov.uk/uksi/2017/407/contents/made (Accessed: 10/03/2021) 8 UK Government (1991). Land Drainage Act 1991 [Online]. Available at: https://www.legislation.gov.uk/ukpga/1991/59/contents (Accessed: 10/03/2021). 9 UK Government (2014). Water Act 2014 [Online]. Available at: https://www.legislation.gov.uk/ukpga/2014/21/contents/enacted. (Accessed: 10/03/2021). 10 UK Government (2006). Water Resources (Abstraction and Impounding) Regulations 2006 [Online]. Available at: https://www.legislation.gov.uk/uksi/2017/1044/contents/made. (Accessed: 10/03/2021). 11 UK Government (2017) The Water Abstraction and Impounding (Exemptions) Regulations 2017 [Online]. Available at: https://www.legislation.gov.uk/uksi/2017/1044/contents/made. (Accessed: 10/03/2021). 12 UK Government (2009). The Flood Risk Regulations 2009 [Online]. Available at: https://www.legislation.gov.uk/uksi/2009/3042/contents/made. (Accessed: 10/03/2021). 13 UK Government (2018). The Water Supply (Water Quality) Regulations 2018 [Online]. Available at: https://www.legislation.gov.uk/wsi/2018/647/contents/made. (Accessed: 10/03/2021) 14 UK Government (2010). Flood and Water Management Act 2010 [Online]. Available at: https://www.legislation.gov.uk/ukpga/2010/29/contents. (Accessed: 10/03/2021). 15 UK Government (2015). The Environmental Damage (Prevention and Remediation) (England) Regulations 2015 [Online]. Available at: https://www.legislation.gov.uk/uksi/2015/810/contents. (Accessed: 10/03/2021) 16 UK Government (2015). The Water Framework Directive (Standards and Classification) Directions (England and Wales) 2015 [Online]. Available at: https://www.legislation.gov.uk/uksi/2015/1623/pdfs/uksiod_20151623_en_auto.pdf. (Accessed: 10/03/2021). 17 UK Government (2016). The Groundwater (Water Framework Directive) (England) Direction 2016 [Online]. Available at: https://www.gov.uk/government/publications/the-groundwater-water-framework-directive- england-direction-2016. (Accessed: 10/03/2021). 18 UK Government (2017). The Conservation of Habitats and Species Regulations 2017 [Online]. Available at: https://www.legislation.gov.uk/uksi/2017/1012/contents/made. (Accessed: 10/03/2021). 19 Department for Transport (2014). National Policy Statement for National Networks [Online]. Available at: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/387222/n psnn-print.pdf. (Accessed: 10/03/2021). 20 Ministry of Housing, Communities and Local Government (2019). The National Planning Policy Framework 2019 [Online]. Available at: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/810197/N PPF_Feb_2019_revised.pdf. (Accessed: 10/03/2021). 21 Ministry of Housing, Communities and Local Government (2018). Planning practice guidance [Online]. Available at: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/810197/N PPF_Feb_2019_revised.pdf 22 Environment Agency (2016). Part 1: Severn river basin district river basin management plan [Online]. Available at: https://www.gov.uk/government/publications/severn-river-basin-district-river-basin- management-plan. (Accessed: 10/03/2021). 23 Environment Agency (2015). Part 1: Thames river basin district river basin management plan [Online]. Available at: https://www.gov.uk/government/publications/thames-river-basin-district-river-basin- management-plan. (Accessed: 10/03/2021).

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000036 | C01, A3 | 11/03/21 APPENDIX PAGE vii A417 Missing Link | HE551505 Highways England

24 Environment Agency (2016). Severn river basin district flood risk management plan [Online]. Available at: https://www.gov.uk/government/publications/severn-river-basin-district-flood-risk-management-plan. (Accessed: 10/03/2021). 25 Environment Agency (2016). Thames river basin district flood risk management plan [Online]. Available at: https://www.gov.uk/government/publications/thames-river-basin-district-flood-risk-management-plan. (Accessed: 10/03/2021). 26 Gloucestershire County Council (2014). Gloucestershire County Council's Local Flood Risk Management Strategy [Online]. Available at: https://www.gloucestershire.gov.uk/your-community/emergencies-and-your- safety/flooding-and-drainage/gloucestershire-county-councils-local-flood-risk-management-strategy-lfrms/. (Accessed: 10/03/2021) 27 Gloucestershire County Council (2008). Gloucester City Council Strategic Flood Risk Assessment for Local Development Framework Level 1 [Online]. Available at: https://www.gloucestershire.gov.uk/media/6815/gloucester_city_council_level_1_sfra_final-28382.pdf. (Accessed: 10/03/2021) 28 Gloucestershire County Council (2015). Gloucestershire SuDS Design and Maintenance Guide [Online]. Available at: https://www.gloucestershire.gov.uk/media/6846/gloucestershire_suds_design_and_maintenance_guide_- dec_2015-compressed-63334.pdf. (Accessed: 10/03/2021) 29 Gloucestershire County Council (2015). Gloucestershire County Council: Guidance to Local Planning Authorities on Development and Flood Risk [Online]. Available at: https://www.gloucestershire.gov.uk/media/6756/fra_guidance_-_march_2015-63335.pdf. (Accessed: 10/03/2021). 30 Cotswold District Council (2018). Cotswold District Local Plan 2011 to 2031 [Online]. Available at: https://www.cotswold.gov.uk/planning-and-building/planning-policy/local-plan-2011-to-2031/. (Accessed: 10/03/2021) 31 Gloucester, Cheltenham and Tewkesbury Council (2017). Joint Core Strategy 2011-2031 [Online]. Available at: https://www.jointcorestrategy.org/ (Accessed: 10/03/2021). 32 Tewkesbury Borough Council (2015). Draft policies and site options for public consultation [Online]. Available at: https://tewkesburyborough- my.sharepoint.com/personal/website_tewkesburyborough_onmicrosoft_com/_layouts/15/onedrive.aspx?id= %2Fpersonal%2Fwebsite%5Ftewkesburyborough%5Fonmicrosoft%5Fcom%2FDocuments%2FTewkesbury %20Borough%20Council%20%28TBC%29%2FPlanning%20policy%2FLocal%20plan%2FTewkesbury%20B orough%20Plan%202011%20to%202031%2FDraft%20policies%20and%20site%20options%20consultation %20%28February%202015%29%2FDraft%20policies%20and%20site%20options%20for%20public%20cons ultation%2Epdf&parent=%2Fpersonal%2Fwebsite%5Ftewkesburyborough%5Fonmicrosoft%5Fcom%2FDoc uments%2FTewkesbury%20Borough%20Council%20%28TBC%29%2FPlanning%20policy%2FLocal%20pla n%2FTewkesbury%20Borough%20Plan%202011%20to%202031%2FDraft%20policies%20and%20site%20 options%20consultation%20%28February%202015%29&originalPath=aHR0cHM6Ly90ZXdrZXNidXJ5Ym9y b3VnaC1teS5zaGFyZXBvaW50LmNvbS86YjovZy9wZXJzb25hbC93ZWJzaXRlX3Rld2tlc2J1cnlib3JvdWdoX 29ubWljcm9zb2Z0X2NvbS9FUXdHMGVUVDVzMUh1NmxfQzI0T2tzd0JOMVoyYThpN1RWSmcwQVYtNzkx U1Z3P3J0aW1lPU1wLVNWZWZqMkVn. (Accessed: 10/03/2021) 33 Cotswold National Landscape (n.d.). Cotswolds Area of Outstanding Natural Beauty (AONB) Management Plan 2018-2023 [Online]. Available at: https://www.cotswoldsaonb.org.uk/wp- content/uploads/2018/12/Management-Plan-2018-23.pdf. (Accessed: 10/03/2021). 34 Tewkesbury Borough Council (2017). Flood and Water Management Supplementary Planning Document [Online]. Available at: https://minutes.tewkesbury.gov.uk/documents/s31489/CONSULTATION%20DRAFT%20Flood%20and%20 Water%20Management%20SPD%20-%202017%20FINAL.pdf. (Accessed: 10/03/2021). 35 DMRB (2020). LA 104 - Environmental assessment and monitoring [Online]. Available at: https://www.standardsforhighways.co.uk/prod/attachments/0f6e0b6a-d08e-4673-8691- cab564d4a60a?inline=true. (Accessed: 10/03/2021). 36 DMRB (2020). LA 113 Road drainage and the water environment [Online]. Available at: https://www.standardsforhighways.co.uk/prod/attachments/d6388f5f-2694-4986-ac46- b17b62c21727?inline=true. (Accessed: 10/03/2021). 37 Environment Agency (2021). Pollution prevention for businesses [Online]. Available at: https://www.gov.uk/guidance/pollution-prevention-for-businesses (Accessed: 11/02/2021). 38 Environment Agency (2021). Check if you need permission to do work on a river, flood defence or sea defence [Online]. Available at: https://www.gov.uk/permission-work-on-river-flood-sea-defence (Accessed: 11/02/2021). 39 Environment Agency (2015). Manage water on land: guidance for land managers [Online]. Available at: https://www.gov.uk/guidance/manage-water-on-land-guidance-for-land-managers (Accessed: 11/02/2021).

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000036 | C01, A3 | 11/03/21 APPENDIX PAGE viii A417 Missing Link TR010056

6.4 Environmental Statement Appendix 13.2 WFD Compliance Assessment

Planning Act 2008

APFP Regulation 5(2)(a) Infrastructure Planning (Applications: Prescribed Forms and Procedure) Regulations 2009

Volume 6

May 2021 A417 Missing Link | HE551505 Highways England

Infrastructure Planning

Planning Act 2008

The Infrastructure Planning (Applications: Prescribed Forms and Procedure) Regulations 2009

Regulation 5(h)

A417 Missing Link

Development Consent Order 202[x]

6.4 Environmental Statement Appendix 13.2 WFD Compliance Assessment

Regulation Number: 5(2)(a) Planning Inspectorate TR010056 Scheme Reference Application Document Reference 6.4 Author: A417 Missing Link

Version Date Status of Version C01 May 2021 Application Submission A417 Missing Link | HE551505 Highways England

Table of Contents Pages 1 Introduction i 1.1 Background i 1.2 Purpose i 2 Methodology i 2.1 Guidance i 2.2 Stage 1: screening ii 2.3 Stage 2: scoping ii 2.4 Stage 3: impact assessment ii 3 Screening iv 3.1 Scheme components iv 3.2 Construction activities vi 3.3 Operational activities viii 3.4 Zone of influence ix 4 Scoping x 5 Baseline x 5.1 WFD surface waterbodies x 5.2 WFD groundwater bodies xii 5.3 Hydrogeology xiii 5.4 Hydromorphology xiii 5.6 Aquatic ecology xiii 5.7 Protected areas and designations xiii 5.8 Summary xv 6 Impact assessment xviii 6.1 Detailed assessment appendices xviii 6.2 Construction activities xviii 6.3 Operational activities xix 7 Identification and evaluation of measures xxii 8 Conclusions xxiii References xxiv

Table of Tables Table 3-1 Design features of relevance to the water environment v Table 3-2 Screening of construction activities for risks to WFD quality elements vi Table 3-3 Screening of operational activities for risks to WFD quality elements viii Table 5-1 Summary of WFD surface waterbodies in the study area xvi Table 5-2 Summary of WFD groundwater bodies in the study area xvii A417 Missing Link | HE551505 Highways England

1 Introduction

1.1 Background 1.1.1 The Water Environment (Water Framework Directive) (WFD) (England and Wales) Regulations 2017 are described in ES Appendix 13.1 Water Legislative and Policy Framework (Document Reference 6.4). The regulations set out a number of key objectives including:  preventing deterioration of the WFD status of waters  protecting, enhancing and restoring all bodies of surface water and groundwater  progressively reducing discharges of priority substances and ceasing, or phasing discharges, of priority hazardous substances for surface waters  ensuring progressive reduction of groundwater pollution  mitigating the effects of floods and droughts  ensuring sufficient supply of water 1.1.2 Regulation 5(2) (l) (iii) of the Infrastructure Planning (Applications: Prescribed Forms and Procedure) Regulations 2009 (as amended) requires Nationally Significant Infrastructure Projects to provide an assessment of effects upon water bodies in a River Basin Management Plan (RBMP) alongside their application.

1.2 Purpose 1.2.1 The purpose of this report is to:  identify water bodies in a RBMP that are of relevance to the scheme  assess the potential for effects highlight any mitigation measures required to ensure compliance 2 Methodology

2.1 Guidance 2.1.1 This report has followed guidance1,2 produced by The Planning Inspectorate (PINS), the Environment Agency (EA) and the Department for Environment, Food and Rural Affairs (DEFRA) to:  document the baseline condition of the water environment that may be impacted by the proposed works and identify potential receptors.  screen the proposed activities for impact pathways to WFD quality elements.  scope out potential risks to WFD quality elements from the activities screened into the assessment.  carry out a detailed assessment where activities have been identified as posing a risk to the current status or future potential of WFD quality elements. 2.1.2 Unlike in estuarine or coastal environments, there is no specific or prescribed format or process to follow for fluvial or groundwater WFD compliance assessments. This absence of prescribed approach promotes flexibility to applicants and enables them to undertake a proportionate approach. 2.1.3 The WFD assessment comprises the following stages:  Stage 1: Screening

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000033 | C01, A3 | 11/03/21 APPENDIX PAGE i A417 Missing Link | HE551505 Highways England

 Stage 2: Scoping  Stage 3: Impact assessment  Stage 4: Identification and evaluation of measures (if required)  Stage 5: Article 4.7 considerations (if required) 2.1.4 The approach adopted is intended to ensure there is no deterioration of a waterbody regardless of its WFD baseline classification.

2.2 Stage 1: screening 2.2.1 Initial screening identifies relevant water bodies in the study area. Water bodies are selected for inclusion in the early stages of the compliance assessment with reference to the River Basin Management Plans (RBMP). 2.2.2 This stage has considered whether the scheme has impact pathways to WFD waterbodies. Where impact pathways have been considered possible, the proposed zone of influence has been established based on the scheme baseline.

Scheme baseline 2.2.3 Scheme components and activities that have the potential to permanently affect surface water and/or groundwater bodies, and that therefore have the potential to impact on WFD status, have been identified. This has included the identification of all relevant embedded mitigation measures within the scheme construction strategy and design. 2.2.4 Potential impacts may result from the activities required to construct the scheme (e.g. temporary dewatering), or as a result of the scheme’s design (e.g. watercourse crossings / realignments) and operation (e.g. road drainage). 2.2.5 The components of a road scheme are typically repeatable along its length and have therefore been categorised into generic component types (e.g. culverts, outfalls, cuttings, watercourse realignments) with regards to their likely impacts on surface waterbodies and/or groundwater bodies.

2.3 Stage 2: scoping 2.3.1 Scoping comprises a more detailed assessment to identify risks from the scheme to receptors (within the zone of influence) based on the relevant waterbodies and their quality elements. The aim of this assessment is to identify whether there is potential for deterioration in water body status or failure to comply with WFD objectives for any of the water bodies identified in Stage 1, and establish if further detailed assessment is required. At this stage, the scope of further assessment work at Stage 3 should be defined and agreed with the Environment Agency.

2.4 Stage 3: impact assessment 2.4.1 Stage 3 (impact assessment) is a detailed assessment of waterbodies and activities carried forward from the screening stage. It includes identification of waterbodies, description of the proposed development, methods used to determine impacts, risk of deterioration, and mitigation required. 2.4.2 The objective of the impact assessment is to establish the nature and anticipated magnitude of the effects of relevant scheme components on the WFD quality elements of the surface water and groundwater bodies affected by the scheme.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000033 | C01, A3 | 11/03/21 APPENDIX PAGE ii A417 Missing Link | HE551505 Highways England

These effects are to be considered in terms of the potential for deterioration of current status and/or the prevention of status objectives. 2.4.3 The EA provides guidance on the definition of no deterioration3. Necessary measures must be taken to prevent deterioration from one waterbody status class to a lower one. Furthermore, according to a recent EU Court of Justice ruling4, within-class deterioration should also be considered as an overall deterioration of the waterbody status. 2.4.4 The approach to the impact assessment suggested by the PINS guidance1 has been used. The approach includes the following steps:  A description of the scheme and the aspects of the development considered within the scope of the WFD assessment.  Identification of waterbodies that are potentially affected (directly or indirectly) or could be at risk as a result of the scheme (the zone of influence).  Collation of the baseline characteristics of the waterbodies concerned.  Description of the methods used to determine and quantify the scale of WFD impacts (described in each topic specific appendix).  An assessment of the risk of deterioration, as an Article 4.7 derogation may be required where is a there is a risk the scheme will prevent the achievement of good status or result in deterioration in status (further details in Annex A, section 3.6).  An explanation of any mitigation required and how its delivery is secured.  An explanation of any enhancements and/or positive contributions to the RBMP objectives proposed and how their delivery would be secured.

Waterbody baseline 2.4.5 This has been established by identifying the WFD surface water and groundwater bodies potentially affected by the scheme and identifying their baseline condition, using a combination of desktop assessment and, where possible, field surveys. 2.4.6 The desktop assessment has collated and reviewed the waterbody status and status objectives information for the relevant WFD waterbodies based on EA data (2016 Cycle 2 Waterbody Status Classification data). This data is considered to provide the current best estimate of status and the formal baseline against which the EA will assess compliance with the ‘no deterioration’ objective in 2017. 2.4.7 The following datasets have also been used to further establish the nature and existing condition of those watercourses located within WFD waterbodies that are affected by the scheme:  Observations from site walkovers  Observations from water features survey (March 2018 to April 2019) within ES Appendix 13.11 Water Features Survey (Document Reference 6.4)  EA Catchment Data Explorer, including relevant information from the Severn and Thames River Basin Management Plans 20155  EA Water Quality Archive6  Natural England MAGIC7  Ordnance Survey (OS) mapping (including topography)  British Geological Survey (BGS) mapping8  A417 Missing Link Preliminary Groundwater Report 20199

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000033 | C01, A3 | 11/03/21 APPENDIX PAGE iii A417 Missing Link | HE551505 Highways England

 ES Appendix 8.22 Aquatic Invertebrate Survey Report (Document Reference 6.4)  ES Appendix 8.23 Fish Habitat Assessment Report (Document Reference 6.4)  ES Appendix 8.24 Assessment of Tufaceous Vegetation (Document Reference 6.4)  ES Appendix 13.4 Water Quality Assessment (Document Reference 6.4)  ES Appendix 13.5 Hydromorphological assessment (Document Reference 6.4)  ES Appendix 13.6 Spillage risk assessment (Document Reference 6.4)  ES Appendix 13.7 Hydrogeological Impact Assessment (Document Reference 6.4)  ES Appendix 13.10 Drainage Strategy Report (Document Reference 6.4)  ES Appendix 13.12 Water Environment Monitoring Data (Document Reference 6.4) 2.4.8 Potential groundwater dependent terrestrial ecosystems (GWDTEs) will be identified from statutory environmental designations in the study area and spring features will be identified from issues labelled on the OS maps. Licensed and unlicensed groundwater abstraction details will be sought from the EA or the relevant local authority. 2.4.9 The geomorphology baseline conditions were identified during a site walkover and details are outlined in ES Appendix 13.5 Hydromorphology Assessment (Document Reference 6.4). A visual inspection during a site visit is an appropriate method for undertaking a geomorphology survey to inform this level of assessment. 2.4.10 To establish a baseline condition, aquatic invertebrate surveys and fish habitat mapping has been conducted for watercourses that are considered to potentially be modified by the scheme. 2.4.11 Groundwater monitoring is ongoing across the scheme and has informed current reporting. Details are presented in ES Appendix 13.7 Hydrogeological Impact Assessment (Document Reference 6.4). 3 Screening

3.1 Scheme components 3.1.1 This report has considered all ‘scheme components’ that have the potential to permanently affect surface waterbodies and groundwater bodies, and therefore have the potential to impact on WFD status. All scheme components have been assessed individually before the combined effect on quality element status is considered. 3.1.2 Linear infrastructure projects, such as roads, typically have generic scheme components that are repeated across the length of the scheme. A total of six such scheme components have been identified that may directly or indirectly affect surface waterbodies along the scheme alignment. These include:  culverts (detailed in Table 3-1)  watercourse realignments (detailed in Table 3-1)  road drainage basins (detailed in Table 3-1)  road drainage outfalls (detailed in Table 3-1)

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000033 | C01, A3 | 11/03/21 APPENDIX PAGE iv A417 Missing Link | HE551505 Highways England

 embankments  cuttings Table 3-1 Design features of relevance to the water environment

Watercourse Approximate WFD Waterbodies (SW: Description chainage (m) surface water, GW: groundwater) Tributary of 0+100 SW: Horsbere Bk – source to Piped outfall to stream culvert Norman’s Brook conf with R Severn GW: Severn Vale – Secondary Combined Tributary of 0+500 SW: Horsbere Bk – source to Piped outfall to stream culvert Norman’s Brook conf with R Severn via Dog Lane GW: Severn Vale – Secondary Combined and Severn Vale and Severn Vale – Jurassic Limestone Cotswold Edge South Tributary of 0+550 SW: Horsbere Bk – source to Replacement and realignment Norman’s Brook conf with R Severn of stream culvert GW: Severn Vale – Secondary Combined N/a 1+300 to 2+055 SW: Horsbere Bk – source to Cold Slad Link Retaining conf with R Severn Wall/Realignment/loss of watercourse GW: Severn Vale – Jurassic Limestone Cotswold Edge South Tributary of 1+550 SW: River Churn Stepped basins between A417 Norman’s Brook GW: Severn Vale – Jurassic and private access with outfall Limestone Cotswold Edge to stream South N/a 1+650 to 2+900 SW: River Churn Cutting GW: Severn Vale – Jurassic Limestone Cotswold Edge South Jurassic N/a 2+100 to 2+300 SW: River Churn Stepped basins GW: Burford Jurassic Dry valley – flowing 2+150 SW: River Churn Drainage basins with overflow to unnamed tributary GW: Burford Jurassic to dry valley of River Churn 1 Unnamed land 3+100 SW: River Churn Land drainage culvert drainage ditch GW: Burford Jurassic N/a 3+200 SW: River Churn Drainage basin GW: Burford Jurassic N/a 3+200 SW: River Churn B4070 Cutting GW: Burford Jurassic N/a 3+200 to 4+700 SW: River Churn Stockton to Nettleton Cuttings River Frome GW: Burford Jurassic

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000033 | C01, A3 | 11/03/21 APPENDIX PAGE v A417 Missing Link | HE551505 Highways England

Watercourse Approximate WFD Waterbodies (SW: Description chainage (m) surface water, GW: groundwater) Dry valley – flowing 3+900 SW: River Churn Drainage basin with overflow to unnamed tributary GW: Burford Jurassic to dry valley of River Churn 2 Dry valley – flowing 4+600 SW: River Frome Drainage basin with overflow to unnamed tributary GW: Severn Vale – Jurassic to dry valley via culvert under of River Frome Limestone Cotswold Edge farm access South Unnamed land 4+750 SW: River Frome Land drainage culvert drainage ditch GW: Severn Vale – Jurassic Limestone Cotswold Edge South N/a 5+250 SW: River Frome Cowley Junction East Cutting GW: Severn Vale – Jurassic Limestone Cotswold Edge South Unnamed land 5+300 SW: River Frome Land drainage culvert drainage ditch GW: Severn Vale – Jurassic Limestone Cotswold Edge South Tributary of the River 5+500 SW: River Frome Re-use of replacement of Frome GW: Severn Vale – Jurassic existing outfall Limestone Cotswold Edge South

3.2 Construction activities Table 3-2 Screening of construction activities for risks to WFD quality elements

Proposed activity Screen Justification in/out Temporary In The construction of cuttings has the potential to temporarily lower dewatering to groundwater levels which may impact on nearby receptors that are enable construction reliant upon groundwater. (e.g. for cuttings) The activity therefore has the potential to impact upon WFD quality elements and all WFD water and groundwater bodies have been screened into assessment for this activity. Temporary loss of a In The widening of the A417 up Crickley Hill and the new access to Grove section of the Farm are anticipated to require the watercourse to be re-routed between tributary of Ch 0+500m and Ch 1+600m during construction of these scheme Norman’s Brook to elements. enable Following construction, the watercourse will flow along a new alignment embankment around the southern edge of the earth bunding. The impact of this widening permanent modification is considered under Operational Activities (Table 3-3). The loss of approximately 1.1km of watercourse may result in impacts to WFD quality elements of the Norman’s Brook - source to confluence Hatherley Brook waterbody. This activity is screened into the assessment.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000033 | C01, A3 | 11/03/21 APPENDIX PAGE vi A417 Missing Link | HE551505 Highways England

Proposed activity Screen Justification in/out Works in or near to Out In-channel works would be undertaken to install new culverts, drainage watercourses (e.g. outfalls and to realign Crickley Stream. construction of The temporary nature of these works and the construction mitigations culverts and described in ES Appendix 2.1 Environmental Management Plan (EMP) drainage outfalls) (Document Reference 6.4) minimises the potential for permanent impacts upon WFD quality elements. All WFD waterbodies have been screened out of the assessment for this activity. Temporary Out Measures considered to be standard industry practice will be adopted discharge of site during construction to ensure that runoff discharged from the site is of runoff to surface acceptable quality and is discharged in a manner that does not impact waters and upon geomorphology or hydrology of local watercourse. Above standard groundwaters construction practices to be implemented are detailed in ES Appendix 2.1 EMP (Document Reference 6.4). With these measures in place no permanent impacts on the current status or status objectives of WFD quality elements are expected as a result of this activity. All WFD waterbodies have been screened out of the assessment for this activity. Sediment Out Construction activities increase the risk of pollutants entering the wider mobilisation from water environment from spillages from vehicles/plant, concrete wash- site run-off waters and sediment mobilisation. These risks would be present over the length of the construction sequence, with high-risk periods during topsoil stripping and works in or near to watercourses. The risk of sediment mobilisation remains until vegetation is established (at least one growing season). ES Appendix 2.1 EMP (Document Reference 6.4) details how water and sediment would be managed across the scheme and include provisions to minimise the likelihood of runoff, provide containment of spillage and capture or treat wastewaters where necessary. These mitigation measures are intended to prevent permanent impacts upon WFD surface water or groundwater quality elements as a result of this activity. All WFD waterbodies have been screened out of the assessment for this activity. Accidental spillage Out Measures considered to be standard practice, which are detailed in ES of pollutants (e.g. Appendix 2.1 EMP (Document Reference 6.4), will be adopted during fuel leakage from construction to ensure that if an accidental spillage occurs it will be storage or plant) contained and disposed of appropriately. With these measures in place no permanent impacts on the current status or status objectives of WFD quality elements are expected as a result of this activity. All the WFD waterbodies have been screened out of the assessment for this activity.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000033 | C01, A3 | 11/03/21 APPENDIX PAGE vii A417 Missing Link | HE551505 Highways England

3.3 Operational activities Table 3-3 Screening of operational activities for risks to WFD quality elements

Proposed activity Screen Explanation in/out Permanent In The cuttings included in the scheme design (listed in Table 3-1) may changes to cause local changes to groundwater levels. groundwater levels The significant areas of cuttings for the scheme extend across all WFD or flows as a result groundwaters bodies including ‘Severn Vale – Secondary Combined’, of new cuttings, ‘Severn Vale – Jurassic Limestone Cotswold Edge South’ and Burford embankments or Jurassic. road drainage There is a potential for this activity to result in impacts to WFD quality elements. All WFD groundwater bodies have been screened into assessment for this activity. Permanent In The new cuttings included in the scheme design (listed in Table 3-1) changes to surface may cause local changes to groundwater drainage which is likely to water flow regimes result in changes to the flow regimes of minor watercourses in the as a result of new scheme study area. cuttings, The significant areas of cuttings for the scheme are in ‘River Frome – embankments or source to Ebley Mill’, and ‘River Churn – source to Perrots Brook’ and road drainage ‘Norman’s Brook – source to confluence Hatherley Brook’ catchment. There is a potential for this activity to result in impacts to WFD quality elements. ‘River Frome – source to Ebley Mill’, ‘River Churn – source to Perrots Brook’ and ‘Norman’s Brook – source to confluence Hatherley Brook’ WFD waterbodies have been screened into assessment for this activity. The ‘Horsbere Bk – source to confluence with the ’ WFD waterbody is screened out of assessment for this activity. Discharge of In Runoff from the carriageway will pass through the road drainage system routine runoff to prior to its discharge to local watercourses and land ditches at greenfield surface waters or runoff rates. groundwater from There is potential for this runoff to degrade water quality in waters that the road drainage receive runoff from the scheme. system There is potential for this runoff to impact water quality in the following waterbodies, which are all screened into the assessment: Surface waters: - ‘River Frome – source to Ebley Mill’, - ‘River Churn – source to Perrots Brook’ and - ‘Norman’s Brook – source to confluence Hatherley Brook’ Groundwaters: - ‘Severn Vale – Secondary Combined’, - ‘Severn Vale – Jurassic Limestone Cotswold Edge South’ - ‘Burford Jurassic’ Accidental spillage In The road drainage system would provide a level of buffering and an of pollutants (e.g. opportunity for containment between impermeable areas (where a fuel spills) spillage is most likely to occur) and the wider water environment. Despite this there is potential for accidental spillage to result in a degradation in the quality of waters receiving runoff from the Scheme. There is potential for spillage to impact water quality in the following waterbodies, which are all screened into the assessment: Surface waters: - ‘River Frome – source to Ebley Mill’, - ‘River Churn – source to Perrots Brook’ and - ‘Norman’s Brook – source to confluence Hatherley Brook’ Groundwaters:

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000033 | C01, A3 | 11/03/21 APPENDIX PAGE viii A417 Missing Link | HE551505 Highways England

Proposed activity Screen Explanation in/out - ‘Severn Vale – Secondary Combined’, - ‘Severn Vale – Jurassic Limestone Cotswold Edge South’ ‘Burford Jurassic’ New in-channel In The new in-channel structures would consist of new culverts and structures (e.g. drainage outfalls as listed in Table 3-1. culverts or drainage New structures within a watercourse can alter local channel cross outfalls) section and induce local bank or bed erosion, as well as reduce the available natural habitat area. There is potential for impacts to hydromorphology and subsequent effects upon biological quality elements in the following waterbodies, which are all screened into the assessment: Surface waters: - ‘River Frome – source to Ebley Mill’, - ‘River Churn – source to Perrots Brook’ and - ‘Norman’s Brook – source to confluence Hatherley Brook’ Realignment of In The realignment of the tributary of Norman’s Brook (within the ‘Norman’s tributary of Brook – source to confluence Hatherley Brook’ WFD waterbody as Norman’s Brook identified by the tracer test) has the potential to impact sediment regime, channel morphology and natural fluvial processes. The realignment has result in a change to sediment supply, rate of sediment transfer downstream and depositional zones. The new channel could also lack morphological diversity. Natural fluvial processes could be impacted causing an increase in erosion and/or deposition which can have feedback effects including reduction in channel stability. There is a potential for this activity to impact WFD quality elements and therefore the tributary of Norman’s Brook within the WFD waterbody ‘Norman’s Brook – source to confluence Hatherley Brook’ has been screened into assessment for this activity.

3.4 Zone of influence 3.4.1 The screening of the scheme components has noted activities that have the potential to impact upon quality elements of WFD surface water and groundwater bodies. The following WFD waterbodies are deemed to be within the potential zone of influence of the scheme: Surface waterbodies (ES Figure 13.3 WFD Surface Waterbodies (Document Reference 6.3)):  Horsbere Brook – source to confluence with the River Severn  Norman’s Brook – source to confluence Hatherley Brook  River Churn – source to Perrots Brook  River Frome – source to Ebley Mill Groundwater bodies (ES Figure 13.4 WFD Groundwater Bodies (Document Reference 6.3)):  Severn Vale – Secondary Combined  Severn Vale – Jurassic Limestone Cotswold Edge South  Burford Jurassic

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000033 | C01, A3 | 11/03/21 APPENDIX PAGE ix A417 Missing Link | HE551505 Highways England

4 Scoping 4.1.1 The scope of the detailed assessment is based upon the activities identified as potentially posing a risk to WFD quality elements in the screening assessment. The study area extends to the waterbodies within the zone of influence. 4.1.2 An EIA scoping opinion was provided by PINS (ES Appendix 4.1 The Planning Inspectorate Scoping Opinion (Document Reference 6.4)) which included a response relating to WFD assessment from the EA. This response has been considered in this assessment. 4.1.3 The EA was consulted on the scope of the monitoring being undertaken, as well as key effects of the scheme and mitigation. The record of consultation with the EA is recorded in the respective Statement of Common Ground, see Statement of Commonality (Document Reference 7.3). 5 Baseline

5.1 WFD surface waterbodies 5.1.1 The Cotswold Escarpment forms a surface water divide between the River Severn catchment and the catchment (to the east and south-east of the divide). To the west of the divide, the land within the scheme drains to the River Severn and its tributaries, including Norman’s Brook, Horsbere Brook and the River Frome. To the east and south-east, the land within the scheme drains to the River Churn, a tributary of the Thames. 5.1.2 Horsbere Brook, Norman’s Brook, the River Frome and the River Churn are ordinary watercourses within the study area. 5.1.3 The scheme is predominantly situated in the wider Severn River Basin District (RBD), with a small area to the east located with the Thames RBD. 5.1.4 The following WFD waterbodies shown in Table 5-1 are relevant to the scheme or hydrologically connected. 5.1.5 The status, failing elements and designations of these watercourses are summarised in Table 5-1.

Horsbere Brook - source to confluence with the River Severn10 5.1.6 Horsbere Brook (GB109054032760) is classified as a ‘river’ located within the Severn RBD. This river is formally designated as a ‘heavily modified waterbody’ (HMWB). 5.1.7 The waterbody achieved ‘Moderate’ overall waterbody status in 2019 and has no future objective. 5.1.8 The waterbody received an ‘Moderate’ overall status due to ‘Moderate’ ecological status as a result of ‘Poor’ biological quality elements, specifically fish, and a ‘Fail’ chemical status as a result of Priority hazardous substances, specifically Polybrominated diphenyl ethers and mercury and its compounds. 5.1.9 The reasons for not achieving ‘Good’ status are a result of physical modifications including barriers causing ecological discontinuity.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000033 | C01, A3 | 11/03/21 APPENDIX PAGE x A417 Missing Link | HE551505 Highways England

5.1.10 The EA Catchment Data Explorer depicts the ‘Horsbere Brook source to confluence with the River Severn’ catchment boundary as extending to the north of the A417. The EA also depicts the catchment as encompassing a tributary of Horsbere Brook that borders a stretch of the scheme to the north. However, tracer testing has indicated that the tributary flows to the north and extends out of the ‘Horsbere Brook source to confluence with the River Severn’ catchment, as shown in ES Figure 13.1 Surface Water Features (Document Reference 6.3). Therefore, this tributary should be considered part of the Norman’s Brook source to confluence Hatherley Brook catchment. The Horsbere Brook catchment would only be connected to the scheme during period of extreme flow, when flow in the tributary of Norman’s Brook exceeds the capacity of the culvert beneath the A417 and backs up to a level where it flows via overland flow westwards along the southern edge of the A417 into Horsbere Brook.

Norman’s Brook – source to confluence Hatherley Brook11 5.1.11 Norman’s Brook (GB109054032780) is formally designated as a ‘river’ located within the Severn RBD. Norman’s Brook has not been designated as an artificial or heavily modified river. 5.1.12 The waterbody achieved ‘Moderate’ overall waterbody status in 2019 and has no future objective. 5.1.13 The waterbody received an overall ‘Moderate’ status due to ‘Moderate’ ecological status as a result of ‘Moderate’ biological quality elements and physico-chemical quality elements, specifically due to ‘Moderate’ results for macrophytes and phytobenthos combined and ‘Poor’ phosphate results, respectively. It also achieved a ‘Fail’ chemical status as a result of Priority hazardous substances, specifically Polybrominated diphenyl ethers and mercury and its compounds. 5.1.14 The reasons for not achieving ‘Good’ status have been attributed to diffuse and point pollution related to poor livestock management and sewage discharge, respectively. 5.1.15 As detailed above, a tributary of Norman’s Brook is located within the site boundary and adjacent to the scheme, the watercourse flows along the northern section of the scheme. This tributary is incorrectly shown as being part of the Horsbere Brook catchment on EA Catchment Data Explorer mapping. A second tributary is located to the north of the Crickley Hill and Barrow Wake SSSI, approximately 650m from the scheme, as shown in ES Figure 13.1 Surface Water Features (Document Reference 6.3) and ES Figure 13.3 WFD Surface Waterbodies (Document Reference 6.3). 5.1.16 The tributary of Norman’s Brook is a distinguishable feature and is a continuously flowing watercourse fed by land drainage systems and springs on the south and east of Grove Farm and the A417 highway drainage system to the north. Between its source and Crickley Hill stream culvert the existing watercourse has an irregular and steep course interrupted by short culverts and other features such as informal dams, weirs and cascades. 5.1.17 The watercourse enters a culvert just east of the Crickley Hill Farm. This culvert crosses diagonally under the existing A417 Mainline and then continues along Dog Lane and Bentham Lane before discharging to an open ditch just north of Bentham County Club on the western side of Bentham Lane. The total length of the existing culverts is over 1000 metres including Crickley Hill stream culvert.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000033 | C01, A3 | 11/03/21 APPENDIX PAGE xi A417 Missing Link | HE551505 Highways England

River Churn - source to Perrots Brook12 5.1.18 The River Churn (GB106039029810) is classified as a ‘river’ and is located within the Thames Severn RBD. The River Churn has not been designated as an artificial or heavily modified river. 5.1.19 The waterbody achieved ‘Moderate’ overall waterbody status in 2019 and has an objective of ‘Good’ by 2027. 5.1.20 The waterbody received an overall ‘Moderate’ status due to ‘Moderate’ ecological status as a result of ‘Moderate’ biological quality elements, specifically due to macrophytes and phytobenthos combined and fish and a ‘Fail’ chemical status as a result of Priority hazardous substances, specifically Polybrominated diphenyl ethers and mercury and its compounds.. 5.1.21 The reasons for not achieving ‘Good’ status in relation to macrophytes and phytobenthos combined have been attributed to suspect data and groundwater abstractions. Reasons for not achieving ‘Good’ status in relation to fish have been attributed to poor livestock management. 5.1.22 The nearest tributary of the River Churn to the scheme is located approximately 50m from the scheme, as shown in ES Figure 13.1 Surface Water Features (Document Reference 6.3) and ES Figure 13.3 WFD Surface Waterbodies (Document Reference 6.3).

River Frome – source to Ebley Mill13 5.1.23 The River Frome (GB109054032470) is formally designated as ‘river’ and is located within the Severn RBD. The River Frome has not been designated as an artificial or heavily modified river. 5.1.24 The waterbody achieved ‘Moderate’ overall waterbody status in 2019 and has no future objective set. The ‘Moderate’ status is as a result of ‘Moderate’ biological quality elements, specifically due to fish, and a ‘Fail’ chemical status as a result of Priority hazardous substances, specifically Polybrominated diphenyl ethers and mercury and its compounds. 5.1.25 The nearest tributary of the River Frome is located approximately 260m from the scheme, as shown in ES Figure 13.1 Surface Water Features (Document Reference 6.3) and ES Figure 13.3 WFD Surface Waterbodies (Document Reference 6.3).

5.2 WFD groundwater bodies 5.2.1 The scheme is located across three WFD groundwater bodies: Severn Vale – Secondary Combine; Severn Vale – Jurassic Limestone Cotswold Edge South; and Burford Jurassic.

Severn Vale – Secondary Combined14 5.2.2 The Severn Vale – Secondary Combined groundwater body (GB40902G204900) has a groundwater area of 120,678 Ha. The groundwater area extends across Wales and England from the east of up to Great Malvern, encompassing Gloucester and most of Cheltenham. The groundwater body is located to the far most western extent of the scheme, as shown in ES Figure 13.4 WFD Groundwater Bodies (Document Reference 6.3).

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000033 | C01, A3 | 11/03/21 APPENDIX PAGE xii A417 Missing Link | HE551505 Highways England

5.2.3 The groundwater body received a ‘Good’ status in 2019 and has no future objective set.

Severn Vale – Jurassic Limestone Cotswold Edge South15 5.2.4 Severn Vale - Jurassic Limestone Cotswold Edge South groundwater body (GB40901G305700) has a groundwater area of 23,910Ha. The groundwater area extends up through Nailsworth, and Whiteway. The groundwater body is located to the east of the Severn Vale – Secondary Combined groundwater body, as shown in ES Figure 13.4 WFD Groundwater Bodies (Document Reference 6.3). 5.2.5 The groundwater body received a ‘Good’ status in 2019 and has no future objective set.

Burford Jurassic16 5.2.6 Burford Jurassic groundwater body (GB40601G600400) has a groundwater area of 90,062 Ha. The groundwater area extends from up through the Cotswolds to Snowshill. The groundwater body is located to the far most eastern extent of the scheme and to the east of the Severn Vale – Jurassic Limestone Cotswold Edge South groundwater body, as shown in ES Figure 13.4 WFD Groundwater Bodies (Document Reference 6.3). 5.2.7 The groundwater body received a ‘Poor’ status in 2019 and has an objective of ‘Good’ by 2027.

5.3 Hydrogeology 5.3.1 The hydrogeological baseline is described in ES Appendix 13.7 Hydrogeological Impact Assessment (Document Reference 6.4).

5.4 Hydromorphology 5.5 The hydromorphological baseline is described in ES Appendix 13.5 Hydromorphology Assessment (Document Reference 6.4).

5.6 Aquatic ecology 5.6.1 The aquatic invertebrate baseline is described in ES Appendix 8.22 Aquatic Invertebrate Survey Report (Document Reference 6.4). 5.6.2 The fish habitat baseline is described in ES Appendix 8.23 River Habitat Survey and Fish Habitat Assessment Report (Document Reference 6.4). 5.6.3 Tufa deposits supporting Annex 1 species have been identified along the tributary of Norman’s Brook between Ch 1+000m and Ch 1+150m. An assessment of the vegetation has been conducted and is presented in ES Appendix 8.24 Assessment of tufaceous vegetation (Document Reference 6.4).

5.7 Protected areas and designations 5.7.1 Under the WFD, ‘Protected Areas’ are defined as areas requiring special protection because of their sensitivity to pollution or due to their particular economic, social or environmental importance. These areas are waterbodies or parts of them:

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000033 | C01, A3 | 11/03/21 APPENDIX PAGE xiii A417 Missing Link | HE551505 Highways England

 used for the abstraction of water intended for human consumption (Drinking Water Protected Area (DrWPA);  supporting economically significant shellfish or freshwater fish stocks (Freshwater Fish Water; Shellfish Water);  where a large number of people are expected to bathe (Bathing Water);  supporting habitats or species of international biodiversity conservation importance (such as a Special Area of Conservation (SAC) or Special Protection Area (SPA)); and/or  sensitive to nutrient enrichment (such as a Nitrate Vulnerable Zone (NVZ) or Urban Waste Water Treatment Directive (UWWTD) sensitive zone). 5.7.2 The specific environmental designations, measures and actions for these protected areas have been established under previous European Directives, which set out the requirements to ensure the protection of the area’s water environment or protection of wildlife that is directly dependant on that water environment. Where a WFD waterbody falls within or forms all or part of one of these designated predicted areas, the waterbody is subject to additional environmental objectives (and associated monitoring regimes, risk assessments, and regulations) in accordance with the relevant, previous Directive(s).

DrWPA 5.7.3 The nearest DrWPA is the Shropshire, Herefordshire, Worcestershire and Gloucestershire (GB70910509) which is located approximately 9.2km from the scheme.

SAC 5.7.4 The Cotswold Beechwoods SAC is located 270m west and downslope of the B4070, includes areas of vegetation dependent on high groundwater levels that are associated with some nationally rare invertebrate species. These protected areas extend from the south-east of to High Brotheridge, and includes springs supplying Horsbere Brook. 5.7.5 The Severn Estuary SAC is located 9km west of the scheme and is hydrologically connected to the scheme via Norman’s Brook and Horsebere Brook and the River Frome.

SPA 5.7.6 There are no SPAs that are hydrologically connected to the scheme.

NVZ 5.7.7 The eastern extent of the scheme is located within ‘Hatherley Bk – conf Norman’s Bk to conf R Severn’ Surface Water NVZ under the 2017 designation.

UWWTD 5.7.8 The scheme is not located within an UWWTD sensitive area.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000033 | C01, A3 | 11/03/21 APPENDIX PAGE xiv A417 Missing Link | HE551505 Highways England

Aquifers

Aquifer designation - bedrock 5.7.9 The majority of the scheme is located upon a Principal Aquifer, except the north western part of the scheme. The aquifer designations are shown on ES Figure 13.6 Aquifer Designations (Document Reference 6.3). 5.7.10 More comprehensive details on hydrogeology are included in ES Figure 13.4 WFD Groundwater Bodies (Document Reference 6.3).

Aquifer designation – superficial deposits 5.7.11 The north western extent of the scheme is located within the Secondary Aquifer. There are no other superficial deposits located along the scheme extent. The aquifer designations are shown on ES Figure 13.6 Aquifer Designations (Document Reference 6.3). 5.7.12 More comprehensive details on hydrogeology are included in ES Figure 13.4 WFD Groundwater Bodies (Document Reference 6.3).

5.8 Summary 5.8.1 The WFD surface waterbodies and groundwater bodies that are hydrologically connected to the scheme are shown in Table 5-1 and Table 5-2 of this report, respectively.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000033 | C01, A3 | 11/03/21 APPENDIX PAGE xv A417 Missing Link | HE551505 Highways England

Table 5-1 Summary of WFD surface waterbodies in the study area

WFD waterbody Horsbere Brook – source Norman’s Brook – source River Churn – source to River Frome – source to to confluence with the to confluence Hatherley Perrots Brook Ebley Mill River Severn Brook ID GB109054032760 GB109054032780 GB106039029810 GB109054032470 Type of Waterbody River River River River Area (km2) 13.04 3.91 16.94 27.73 HMWB/AWB Heavily Modified Not designated as Not designated as Not designated as HMWB/AWB HMWB/AWB HMWB/AWB Overall Status Moderate Poor Moderate Moderate Objective No objective No objective Good by 2027 No objective Chemical Status Fail Fail Fail Fail Ecological Status Moderate Moderate Moderate Good Driver of failure to achieve ‘good’ Fish Macrophytes and Macrophytes and Fish status Phytobenthos Phytobenthos Fish Reasons for not achieving ‘good’ Physical modification of Poor livestock management Poor livestock management N/A status barriers causing ecological (diffuse pollution) (diffuse pollution) discontinuity Sewage discharge (point Groundwater abstraction source)

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000033 | C01, A3 | 11/03/21 APPENDIX PAGE xvi A417 Missing Link | HE551505 Highways England

Table 5-2 Summary of WFD groundwater bodies in the study area

WFD groundwater body Severn Vale – secondary Severn Vale – Jurassic Burford Jurassic combined Limestone Cotswold Edge South

ID GB40902G204900 GB40901G305700 GB40601G600400 Type of Waterbody Groundwater Groundwater Groundwater Area (km2) 1,206.78 239.10 900.62 Overall Status Good Good Poor Objective No objective set No objective set Good by 2027 Chemical Status Good Good Poor Quantitative Status Good Good Good Driver of failure to achieve ‘good’ status N/A N/A Chemical DrWPA General chemical test

Reasons for not achieving ‘good’ status N/A N/A Poor nutrient management (diffuse source) Private sewage treatment (point source)

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000033 | C01, A3 | 11/03/21 APPENDIX PAGE xvii A417 Missing Link | HE551505 Highways England

6 Impact assessment

6.1 Detailed assessment appendices 6.1.1 Potential impacts upon surface water and groundwater WFD quality elements have been identified in the screening assessment undertaken in Section 3. 6.1.2 The assessment of construction and operational effects has been informed by the findings of the following detailed assessments:  ES Appendix 8.22 Aquatic Invertebrate Survey Report (Document Reference 6.4)  ES Appendix 8.23 Fish Habitat Assessment Report (Document Reference 6.4)  ES Appendix 8.24 Assessment of Tufaceous Vegetation (Document Reference 6.4)  ES Appendix 13.4 Water Quality Assessment (Document Reference 6.4)  ES Appendix 13.5 Hydromorphological Assessment (Document Reference 6.4)  ES Appendix 13.6 Spillage Risk Assessment (Document Reference 6.4)  ES Appendix 13.7 Hydrogeological Impact Assessment (Document Reference 6.4)  ES Appendix 13.10 Drainage Strategy Report (Document Reference 6.4)

6.2 Construction activities

Temporary dewatering to enable construction 6.2.1 The screening identified the potential for impacts on WFD quality elements of surface water and groundwater bodies resulting from temporary dewatering to enable construction, particularly at cutting locations. 6.2.2 Where the hydrogeological impact assessment has indicated that temporary dewatering would be required, groundwater intercepted as part of the works would be retained within the catchment of the respective receiving water. 6.2.3 The initial hydrogeological impact assessment has identified that impacts relating to temporary dewatering would be localised to each cutting and hence not anticipated to have a significant impact on the quality elements of any WFD surface water or groundwater bodies. 6.2.4 No impacts upon GWDTEs are anticipated as a result of the temporary dewatering.

Temporary loss of a section of the tributary of Normans Brook 6.2.5 The screening identified the potential for impacts on WFD quality elements of the Normans Brook - source to confluence Hatherley Brook river waterbody resulting from temporary loss of the uppermost 1.1km of the tributary of Normans Brook. This section of watercourse would be realigned to enable widening of the A417 embankment. 6.2.6 A temporary impact upon all quality elements of the watercourse would result from this activity. However, the impact would be limited to this 1.1km section of watercourse. The duration of the impact would be for the length of the construction programme.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000033 | C01, A3 | 11/03/21 APPENDIX PAGE xviii A417 Missing Link | HE551505 Highways England

6.2.7 The fish habitat assessment within ES Appendix 8.23 River habitat survey and Fish habitat assessment (Document Reference 6.4), of the section of watercourse that would be impacted, concluded that whilst habitat for mixed juvenile fish (salmonid fry and parr) and salmonid spawning habitat was recorded, it is considered highly unlikely that this reach provides habitat for salmonids due to the high number of impassable weirs. 6.2.8 To ensure that effects upon WFD quality elements are localised and temporary, the detailed design of the realigned watercourse would provide aquatic habitat features of an equivalent or greater value to that of the existing watercourse. 6.2.9 Given the mitigation proposed and the short section of watercourse potentially effected, this activity is not anticipated to result in any significant effects upon the quality elements of the Normans Brook – source to confluence Hatherley Brook waterbody.

6.3 Operational activities

Permanent changes to groundwater flow regimes as a result of new cuttings, embankments or road drainage 6.3.1 The potential for changes to groundwater levels and flows has been assessed in ES Appendix 13.7 Hydrogeological Impact Assessment (Document Reference 6.4). 6.3.2 The proposed cuttings are expected to encounter groundwater. The permanent drainage would result in minor, localised changes to groundwater levels and flows. There are no recorded licensed abstractions within 1km of the scheme. 6.3.3 Analysis of the extent of anticipated drawdown indicates that localised changes in groundwater level are unlikely to impact upon any groundwater quality elements. Additionally, the drainage design would retain collected groundwater within the respective receiving water. 6.3.4 Therefore, this activity is not anticipated to result in any significant effects upon the quality elements of WFD groundwater bodies. 6.3.5 No impacts upon GWDTEs are anticipated as a result of this activity.

Permanent changes to surface water flow regimes as a result of new cuttings, embankments or road drainage 6.3.6 The potential for changes to surface water flows as a result of changes in groundwater level or flow changes has been considered in ES Appendix 13.7 Hydrogeological Impact Assessment (Document Reference 6.4). 6.3.7 Analysis has shown that localised changes in groundwater level or flow resulting from drainage for ground stabilisation along the tributary of Normans Brook would result in change in surface water flow in the realigned stream. The existing inputs from various springs between Ch 0+500m and Ch 1+600m would be collected by this drainage and directed back into the stream further downslope. 6.3.8 This would cause a reduction in baseflow for a short section of the realigned stream with the potential for subsequent impacts on ecological quality elements in this localised reach.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000033 | C01, A3 | 11/03/21 APPENDIX PAGE xix A417 Missing Link | HE551505 Highways England

6.3.9 To mitigate for this impact, the detailed design of the realigned stream will account for the anticipated changes to flow regime to ensure that the channel form is optimised to maximise habitat potential. 6.3.10 Given the mitigation proposed and the short section of watercourse potentially effected, this activity is not anticipated to result in any significant effects upon the quality elements of the ‘Normans Brook – source to confluence Hatherley Brook’ waterbody.

Discharge of routine run-off to surface water from the road drainage 6.3.11 Impacts of routine run-off on surface waters has been assessed through a HEWRAT assessment undertaken in ES Appendix 13.4 Water Quality Assessment (Document Reference 6.4). 6.3.12 The assessment identified that all road drainage areas require some form of pollutant treatment to reduce loadings to receiving waters to an acceptable level. All networks on the scheme include a basin (pond) along with at least one other measure as a treatment train. Catchments 6, 7 and 8 require an additional pollution control measure to meet the required removal percentage. This additional treatment will be in the form of a forebay within the basins to effectively remove pollutants. The forebay design will be developed at the detailed design stage. 6.3.13 The exact type and configuration of the basins will depend heavily on the specific ground conditions (suitability for infiltration) at each location and the preferred maintenance regime of the adopting body (Highways England or Gloucestershire County Council). 6.3.14 This surface water quality assessment is based on a precautionary assumption that no infiltration will take place within the drainage systems and at the basins. Infiltration testing has been undertaken following ground investigations. During detailed design, there will be opportunities to introduce infiltration techniques and optimise the basin designs. Infiltration will also significantly improve the pollutant removal performance of the highway drainage systems. 6.3.15 Given the mitigation proposed, this activity is not anticipated to result in any significant effects upon the quality elements of any surface waterbodies that would receive discharge from the road drainage system.

Discharge of routine run-off to groundwater from the road drainage 6.3.16 Impacts of routine run-off on groundwater has been assessed in ES Appendix 13.4 Water Quality Assessment (Document Reference 6.4). 6.3.17 The assessment identified that all road drainage areas pose a medium risk of impact to groundwater. DMRB LA 113 states that where a medium risk of impact is indicated, detailed assessment should be undertaken by a competent expert. 6.3.18 This assessment would be undertaken upon completion of the ground investigation at the detailed design stage (following DCO). Where required, mitigation measures would be incorporated into the detailed design to reduce the risk to an acceptable level. 6.3.19 Following the additional assessment to be undertaken at detailed design and subsequent mitigation measures if required, this activity is not anticipated to result

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000033 | C01, A3 | 11/03/21 APPENDIX PAGE xx A417 Missing Link | HE551505 Highways England

in any significant effects upon the quality elements of any groundwater bodies that would receive discharge from the road drainage system. 6.3.20 No impacts upon GWDTEs are anticipated as a result of this activity.

Accidental spillage of pollutants 6.3.21 Impacts resulting from accidental spills have been assessed in ES Appendix 13.6 Spillage Risk Assessment (Document Reference 6.4). 6.3.22 The assessment identified that, without consideration of the drainage scheme, there would be no discharge with a serious spillage risk more frequent than 1% and 0.5% annual exceedance probability (AEP) (1 in 100 year and 1 in 200-year return period) thresholds. The spillage risk is therefore acceptable, and no mitigation is required. 6.3.23 This activity is not anticipated to result in any significant effects upon the quality elements of any WFD waterbodies.

New culverts to maintain land drainage pathways 6.3.24 Impacts resulting from new culverts have been assessed in ES Appendix 13.5 Hydromorphology Assessment (Document Reference 6.4). 6.3.25 Three land drainage culverts are proposed as part of the scheme. These structures would all be maintaining flow pathways at headwaters during periods of overland flow and would not span permanent watercourses. Despite this, culverts have the potential to reduce habitat availability and connectivity and alter sediment transport through scour or deposition. 6.3.26 To mitigate the potential impact of culverts, the detailed design would follow CD 529 Design of outfall and culvert details17. 6.3.27 Given the mitigation proposed, this activity is not anticipated to result in any significant effects upon the quality elements of any of the WFD surface waterbodies where culverts are proposed as part of the scheme.

New outfalls from the road drainage system 6.3.28 Impacts resulting from new culverts have been assessed in ES Appendix 13.5 Hydromorphology Assessment (Document Reference 6.4). 6.3.29 Twelve road drainage outfalls are proposed as part of the scheme. Outfalls have the potential to alter local channel cross section and induce local bank or bed erosion, as well as reduce the available natural bank habitat area. 6.3.30 To mitigate the potential impact of outfalls, the detailed design would follow CD 529 Design of outfall and culvert details. 6.3.31 Given the mitigation proposed, this activity is not anticipated to result in any significant effects upon the quality elements of any of the WFD surface waterbodies where outfalls are proposed as part of the scheme.

Realignment of the tributary of Normans Brook 6.3.32 Impacts resulting from realignment of the tributary of Normans Brook have been assessed in ES Appendix 13.5 Hydromorphology Assessment (Document

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000033 | C01, A3 | 11/03/21 APPENDIX PAGE xxi A417 Missing Link | HE551505 Highways England

Reference 6.4). Further information of the design of the realignment is presented in ES Appendix 13.10 Drainage Report (Document Reference 6.4) 6.3.33 The widening of the A417 and its embankment through Crickley Hill requires the watercourse to be realigned southwards along the toe of the widened embankment. The uppermost 320m of the watercourse would be culverted to accommodate a new access road and road drainage basin. 6.3.34 As the widened road embankment would take up a greater proportion of the valley, the bed of the realigned watercourse would be perched approximately 2m above the existing riverbed level. 6.3.35 The realignment of the watercourse would impact upon hydromorphological supporting elements, with subsequent effects upon biological quality elements (e.g. fish invertebrates, macrophytes), of the Normans Brook – source to confluence Hatherley Brook waterbody. 6.3.36 The following design principles would be implemented during the detailed design of the scheme to mitigate the effects of the realignment upon WFD quality elements:  the detailed design of the realigned watercourse would provide naturalistic features of an equivalent or greater value to that of the existing watercourse  the channel design would incorporate bioengineering techniques over traditional hard engineering where feasible  the flow regime of the realigned watercourse would be as similar as the existing flow regime as practicable  the detailed design should be overseen by an experienced fluvial geomorphologist 6.3.37 Tufa habitat surveys have been carried out to establish whether the deposits that would be lost support protected habitats or species. Potential tufa spring mitigation sites have been identified (ES Appendix 8.25 Tufa-forming springs: selection of potential compensation sites (Document Reference 6.4)) and will be developed further during detailed design. 6.3.38 Given the mitigation proposed, this activity is not anticipated to result in any significant effects upon the quality elements of any of the WFD surface waterbodies where outfalls are proposed as part of the scheme. 7 Identification and evaluation of measures

RMBP objectives 7.1.1 The study area is located across the Severn and Thames RBDs and therefore the objectives from both the Severn RBMP and Thames RBMP are relevant to the scheme. 7.1.2 The river basin districts seek to comply with the objectives of the WFD. Common measures, and standards to help achieve the WFD objectives detailed within the Severn and Thames RBMPs are listed. 7.1.3 To prevent deterioration of the status of surface waters and groundwater, measures to support include:  controlling new physical modifications  managing pollution from wastewater

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000033 | C01, A3 | 11/03/21 APPENDIX PAGE xxii A417 Missing Link | HE551505 Highways England

 managing pollution from towns, cities and transport  changes to natural flow and levels of water  managing invasive non-native species  managing pollution from rural areas  managing pollution from mine waters 8 Conclusions 8.1.1 It is considered that the activities related to the scheme will not cause deterioration in the status of any WFD waterbodies or prevent them from achieving either ‘Good Ecological Status’ or ‘Good Ecological Potential’ by 2021 or 2027, provided that the mitigations measured described in Section 6 are implemented. The delivery of this mitigation is secured by its inclusion within the EMP (ES Appendix 2.1 EMP (Document Reference 6.4)). 8.1.2 This assessment has been based on currently available WFD baseline data and design information for the scheme. The assessment is considered a ‘live’ document and should be reviewed and updated at detailed design and construction, particularly if:  the EA update or provide additional WFD baseline data for the relevant waterbodies; and/or  significant changes to the nature, alignment, scale or construction methods of the scheme are made. 8.1.3 Any future updates to the assessment should be shared and agreed with the EA as the regulatory authority in England.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000033 | C01, A3 | 11/03/21 APPENDIX PAGE xxiii A417 Missing Link | HE551505 Highways England

References

1 The Planning Inspectorate (2017) Advice Note 18: The Water Framework Directive [Online]. Available at: (June 2017). Available at: https://infrastructure.planninginspectorate.gov.uk/wp- content/uploads/2017/06/advice_note_18.pdf (Accessed 15/01/2021). 2 EA & DEFRA (2009). WFD Expert Assessment of Flood Management Impacts. Joint EA & DEFRA Flood and Coastal Erosion Risk Management R&D Programme. R&D Technical Report FD2609/TR. 3 UK Technical Advisory Group (2006). Prevent Deterioration of Status [Online]. Available at: https://www.wfduk.org/sites/default/files/Media/Setting%20objectives%20in%20the%20water%20environmen t/Prevent%20deterioration%20of%20status_Draft_010506.pdf. (Accessed 15/01/2021). 4 Court of Justice of European Union (2015). The obligations laid down by the Water Framework Directive concerning enhancement and prevention of deterioration apply to individual projects such as the deepening of a navigable river, Press Release No 74/15 [Online]. Available at: https://curia.europa.eu/jcms/upload/docs/application/pdf/2015-07/cp150074en.pdf (Accessed 15/01/2021). 5 Environment Agency (2020). Catchment Data Explorer [Online]. Available at: http://environment.data.gov.uk/catchment-planning/ (Accessed 15/01/2021). 6 Environment Agency (2019). Water Quality Archive [Online]. Available at: https://environment.data.gov.uk/water-quality/view/ (Accessed 15/01/2021). 7 DEFRA (2019). MAGIC, Interactive mapping at your fingertips [Online]. Available at: http://www.magic.gov.uk/ (Accessed 15/01/2021). 8 British Geological Society (2021). Geology of Britain viewer [Online]. Available at: http://mapapps.bgs.ac.uk/geologyofbritain/home.html (Accessed 15/01/2021). 9 Mott MacDonald Sweco Joint Venture (2019). Preliminary Groundwater Report, Doc No. HE551505- MMSJV-HGT-000-RP-CE-00004 10 Environment Agency (2021). Catchment Data Explorer, Horsbere Bk - source to conf R Severn Overview [Online]. Available at: https://environment.data.gov.uk/catchment- planning/WaterBody/GB109054032760 (Accessed 15/01/2021). 11 Environment Agency (2021). Catchment Data Explorer [Online]. Available at: https://environment.data.gov.uk/catchment-planning/WaterBody/GB109054032780 (Accessed 15/01/2021). 12 Environment Agency (2021). Catchment Data Explorer, Normans Bk - source to conf Hatherley Bk Overview [Online]. Available at: https://environment.data.gov.uk/catchment- planning/WaterBody/GB106039029810 (Accessed 15/01/2021). 13 Environment Agency (2021). Catchment Data Explorer, Frome - source to Ebley Mill Overview [Online]. Available at: https://environment.data.gov.uk/catchment-planning/WaterBody/GB109054032470 (Accessed 15/01/2021). 14 Environment Agency (2019). Catchment Data Explorer, Severn Vale - Secondary Combined Overview [Online]. Available at: https://environment.data.gov.uk/catchment-planning/WaterBody/GB40902G204900 (Accessed 15/01/2021). 15 Environment Agency (2019). Catchment Data Explorer, Severn Vale - Jurassic Limestone Cotswold Edge South Overview [Online]. Available at: https://environment.data.gov.uk/catchment- planning/WaterBody/GB40901G305700 ( Accessed 15/01/2021). 16 Environment Agency (2019). Catchment Data Explorer, Burford Jurassic Overview [Online]. Available at: https://environment.data.gov.uk/catchment-planning/WaterBody/GB40601G600400 (Accessed 15/01/2021). 17 Highways England (2020). Design Manual for Roads and Bridges, CD 529, Design of outfall and culvert details (Rev 1).

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000033 | C01, A3 | 11/03/21 APPENDIX PAGE xxiv A417 Missing Link TR010056

6.4 Environmental Statement Appendix 13.3 Flood Risk Assessment

Planning Act 2008

APFP Regulation 5(2)(a) Infrastructure Planning (Applications: Prescribed Forms and Procedure) Regulations 2009

Volume 6

May 2021 A417 Missing Link | HE551505 Highways England

Infrastructure Planning

Planning Act 2008

The Infrastructure Planning (Applications: Prescribed Forms and Procedure) Regulations 2009

Regulation 5(h)

A417 Missing Link

Development Consent Order 202[x]

6.4 Environmental Statement Appendix 13.3 Flood Risk Assessment

Regulation Number: 5(2)(a) Planning Inspectorate TR010056 Scheme Reference Application Document Reference 6.4 Author: A417 Missing Link

Version Date Status of Version C01 May 2021 Application Submission A417 Missing Link | HE551505 Highways England

Table of Contents Pages 1 Introduction i 1.1 Purpose of this document i 1.2 Flood risk assessment methodology i 2 Flooding legislation and policy framework ii 2.1 Legislation ii 2.2 National policy ii 3 Consultation v 3.1 Introduction v 3.2 Environment Agency v 3.3 Lead local flood authority vii 3.4 Water companies vii 4 Baseline conditions vii 4.1 Sources of information vii 4.2 Site description viii 4.3 Topography viii 4.4 Fluvial flood risk viii 4.5 Surface water (pluvial flood risk) ix 4.6 Groundwater flood risk x 4.7 Artificial drainage systems xi 4.8 Infrastructure flooding xii 4.9 Historic flooding xii 5 Sequential and exception test xii 5.1 Sequential test xii 5.2 Exception test xii 6 Flood risk assessment xiii 6.1 Flooding sources xiii 6.2 Fluvial flood risk xiii 6.3 Surface water (pluvial) flood risk xiv 6.4 Groundwater flood risk xvi 6.5 Artificial drainage systems xvii 7 Flood risk mitigation xvii 7.2 Fluvial flood risk xviii 7.3 Surface water flood risk xviii 7.4 Artificial drainage flood risk xix 7.5 Groundwater flood risk xx 8 Conclusions and recommendations xxi

Report Template – Version 3 A417 Missing Link | HE551505 Highways England

8.2 Summary of flood risk xxi 8.3 Flood mitigation xxii References xxiv

Table of Photographs Photograph 6-1 Manhole located along Dog Lane which lifts under high flow conditions xv

Table of Tables Table 2-1 Flood zoning system used across England as defined in NPPF iv Table 2-2 Flood risk vulnerability and compatibility iv Table 4-1 Main sources of information used in preparing this document viii Table 6-1 Flows for the tributary of Norman’s Brook for a range of return periods xvi

Report Template – Version 3 A417 Missing Link | HE551505 Highways England

1 Introduction 1.1 Purpose of this document 1.1.1 This Flood Risk Assessment (FRA) is required to identify the sources of flood risk to and from the scheme. The scheme is described in Environmental Statement (ES) Chapter 2 The project (Document Ref 6.2). 1.1.2 A FRA is required in England for any development or change of use in Flood Zones 2 or 31, as identified from the Environment Agency (EA) flood maps2, any development more than 1 hectare (ha) in size in Flood Zone 13 or any development which may be susceptible to flooding from sources other than rivers and the sea. 1.1.3 A review of the online EA flood maps2 indicates that the site is within Flood Zone 1; however, as the overall development is greater than 1 ha a FRA is required in accordance with the current legislation. 1.1.4 Elements of the scheme which could potentially impact on flood risk include:  The widening of the A417 up Crickley Hill and the adjacent earth bunding provided along the southern side of the alignment which introduces earthworks into the bottom of the existing valley on the southern toe which covers the existing watercourse. This necessitates a realignment of the stream on the south side of the new A417 embankment between Grove Farm and the existing culvert near Crickley Hill Farm (Flyup 417 Bike Park).  The wider A417 up Crickley Hill also requires the existing culvert beneath the A417 to be replaced and extended under the raised and widened road and earth bunding.  The scheme includes a large cutting through the limestone escarpment and a significant increase in paved areas. The size of the cuttings will result in some redistribution of existing catchments within the drainage system. These elements of the scheme could have an impact on flood risk from groundwater, artificial drainage and surface water sources. 1.2 Flood risk assessment methodology 1.2.1 This report has been prepared with reference to the National Policy Statement for National Networks (NPSNN), which sets out policies to guide how DCO applications will be decided and how the effects of national networks infrastructure should be considered. This report also considers the National Planning Policy Framework (NPPF)4, the NPPF Technical Guidance5 and follows the methodology prescribed in CIRIA document C624: Development and Flood Risk, Guidance for the Construction Industry6. 1.2.2 The assessment process has proceeded as follows:  policy context: a review of relevant national, regional and local policies  site and development description: establishment of the nature of the existing site and of the scheme, so that relevant details can be described  baseline: identification of all existing potential sources of flood risk  risk assessment: assessment of the risks associated with relevant flood sources, mechanisms and impacts, so that the need for mitigation can be identified  mitigation: identification of any flood risk management measures required

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000034 | C01, A3 | 11/03/21 APPENDIX PAGE i A417 Missing Link | HE551505 Highways England

 conclusions: based on our assessment, whether flood risk to the development and surrounding areas will or will not increase over its lifetime 1.2.3 This FRA has been prepared using surveys and readily available information and has been informed by hydraulic modelling. 2 Flooding legislation and policy framework

2.1 Legislation

Flood Risk Regulations 2009 2.1.1 The Flood Risk Regulations 2009 require the assessment and management of flood risk in England and Wales. The regulations designate a Local Lead Flood Authority (LLFA) and impose duties on the EA and LLFAs to prepare a number of documents including:  preliminary flood risk assessments  flood risk and flood hazard maps  flood risk management plans

Flood and Water Management Act 2010 2.1.2 The Flood and Water Management Act gives the EA a strategic overview of the management of flood and coastal erosion risk in England. In accordance with the Government’s Response to the Pitt Review7, it also gives upper tier local authorities in England responsibility for preparing and putting in place strategies for managing flood risk from groundwater, surface water and ordinary watercourses in their areas. 2.1.3 It provides for better, more comprehensive management of flood risk for people, homes and businesses, helps safeguard community groups from unaffordable rises in surface water drainage charges and protects water supplies to the consumer.

2.2 National policy

National Policy Statement for National Networks (NPSNN) 2.2.1 NPSNN paragraph reference 5.90 to 5.115 sets out how flood risk impacts should be considered. A NPSNN compliant FRA should include the following:  Consideration of the risks of all forms of flooding arising from the project (including adjacent parts of the United Kingdom), in addition to the risks of flooding to the project, and demonstrate how these risks will be managed and, where relevant, mitigated, so that the development remains safe throughout its lifetime8.  The impacts of climate change should be taken into account, clearly stating the development lifetime over which the assessment has been made.  Consideration of the vulnerability of those using the infrastructure including arrangements for safe access and exit.  Inclusion of an assessment of the remaining (known as ‘residual’) risk after risk reduction measures have been taken into account and demonstrate that this is acceptable for the project.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000034 | C01, A3 | 11/03/21 APPENDIX PAGE ii A417 Missing Link | HE551505 Highways England

 Consideration of whether there is a need to remain operational during a worst- case flood event of the development’s lifetime.  Evidence for the Secretary of State to apply the Sequential Test and Exception Test, as appropriate.

National Planning Policy Framework (NPPF) 2.2.2 The Department for Communities and Local Government (DCLG) published the NPPF on the 27 March 2012. This was a wholesale reform of the planning system and replaced all existing Planning Policy Guidance (PPGs) and Statements (PPSs) to make the planning system less complex and more accessible. It transfers more responsibility onto individual planning authorities and states that there should normally be a practice in favour of ‘sustainable development’. The NPPF has subsequently been updated by the Ministry of Housing, Communities and Local Government (MHCLG) in July 2018 and again in February 2019. 2.2.3 The aim of the NPPF, particularly relating to flooding9, is to ensure that flood risk is considered at all stages in the planning process, to avoid inappropriate development in areas at risk of flooding and to direct development away from areas at highest risk. It does this by formulating a risk-based approach towards flooding to be adopted at all levels of planning. 2.2.4 The NPPF requires that the “Sequential Test” is applied during the planning process. The Sequential Test aims to ensure that preference for developable land is given to land that has the lowest risk of flooding, based on the data available. The starting point for the ‘Sequential Test’ is the system of ‘Flood Zoning’. This is a system that assesses the risk posed by rivers and in coastal areas estuaries and the sea. This information is collected and made available by the EA and the Local Planning Authority (LPA). 2.2.5 The Sequential Test requires that development should only be considered within Flood Zone 2 if there are no appropriate development sites in Flood Zone 1. Development in Flood Zone 3 should only be considered if development is not possible in Flood Zone 2; assuming development in Flood Zone 1 has also been ruled out. 2.2.6 The Flood Zoning system adopted in England is described in Table 2-1, as defined in NPPF technical guidance3.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000034 | C01, A3 | 11/03/21 APPENDIX PAGE iii A417 Missing Link | HE551505 Highways England

Table 2-1 Flood zoning system used across England as defined in NPPF

Flood zone Definition Zone 1 This zone comprises land assessed as having a less than 1 in 1,000 annual low probability probability of river or sea flooding in any year (<0.1% Annual Exceedance Probability (AEP)). Zone 2 This zone comprises land assessed as having between a 1 in 100 and 1 in 1,000 medium annual probability of river flooding (1% - 0.1% AEP) or between a 1 in 200 and 1 probability in 1,000 annual probability of sea flooding (0.5% - 0.1% AEP) in any year. Zone 3a This zone comprises land assessed as having a 1 in 100 or greater annual high Probability probability of river flooding (>1% AEP) or a 1 in 200 or greater annual probability of flooding from the sea (>0.5% AEP) in any year. Zone 3b This zone comprises land where water has to flow or be stored in times of flood. Functional Strategic flood risk assessments (SFRAs) should identify this flood zone as land Floodplain which would flood with an annual probability of 1 in 20 (5% AEP) or greater in any year or is designed to flood in an extreme (0.1% AEP) flood, or at another probability to be agreed between the LPA and the EA, including water conveyance routes. 2.2.7 The application of the Sequential Test relies on Regional Planning Bodies (RPBs) Regional Flood Risk Appraisals (RFRAs) which informs the Regional Spatial Strategies (RSS) and the LPA’s Strategic Flood Risk Assessments (SFRAs) which informs the Local Development Framework (LDF) by identifying areas suitable for development. Therefore, the Sequential Test must be undertaken at an early stage of the development process (in some cases before land is purchased) and should involve close consultation with the LPA. 2.2.8 The NPPF encourages those involved in development to consider the flood vulnerability of the scheme to the impact of flooding. The vulnerability of different types of development is listed in the NPPF. This is relevant for considering what type of development is appropriate for a site (based on its Flood Zone) and how a development site should be laid out if there are different Flood Zones encountered within a wider site. The compatibility of a development in terms of its vulnerability and Flood Zoning is also described in the NPPF; as shown in Table 2-2. This illustrates how higher vulnerability land uses should be directed to lower flood risk locations sites and vice versa. Table 2-2 Flood risk vulnerability and compatibility

Essential Water Highly More Less Flood zone infrastructure compatible vulnerable vulnerable vulnerable Flood Zone 1      Flood Zone 2   Exception test   Flood Zone 3a Exception test   Exception test  Flood Zone 3b Exception test “Functional     Floodplain”

Key:  Development is appropriate,  Development should not be permitted, ‘Exception Test’ will be required. 2.2.9 Should the sequential approach show it is not possible for the development to be located in zones of lower flood risk it may be possible to, using the ‘Exception Test’ demonstrate that development is still feasible by the management of flood risk. The ‘Exception Test’ within NPPF requires the demonstration that both:

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000034 | C01, A3 | 11/03/21 APPENDIX PAGE iv A417 Missing Link | HE551505 Highways England

 the development provides wider sustainability benefits that outweigh the flood risk.  an FRA must be able to demonstrate that the proposed development is safe considering its expected lifetime and the vulnerability of the proposed land uses without increasing flood risk elsewhere and where possible reducing overall flood risk. 2.2.10 In April 2015 changes to the NPPF saw the Lead Local Flood Authority (LLFA) made a statutory planning consultee for development and flood risk issues except those concerning Main Rivers. Responsibility for the latter still resides with the EA. Furthermore, the LPA, through the planning system, were given the role of ensuring sustainable drainage is incorporated into schemes.

Strategic flood risk assessment 2.2.11 The Level 1 Strategic Flood Risk Assessment (SFRA)9 contains an assessment of all forms of flood risk: fluvial, tidal, surface water, groundwater, sewers and impounded water bodies within Gloucestershire. The SFRA informs decision making processes in terms of new and existing developments and identifies the level required for site specific FRAs. The document also highlights sites at significant risk of flooding and guides developments to areas that lie within Flood Zone 1. Areas with a high likelihood of flooding from a combination of sources have been assessed further in the Level 2 SFRA10 but as the scheme lies within Flood Zone 1 it is not included.

Joint Core Strategy 2011-2031 2.2.12 The Joint Core Strategy11 is a partnership between Gloucester City Council (GCC), Cheltenham Borough Council (CBC) and Tewkesbury Borough Council (TBC) and is a strategic document that sets out how the area will develop between 2011 and 2031 and was adopted in December 2017. The relevant policies within the strategy include: INF1 – Transport Network and INF2 – Flood Risk Management. INF1 mentions the A417 as part of the strategic road network that Highways England (HE) is responsible for maintaining and improving. In INF2 the councils align themselves with the NPPF and commit to incorporating SuDS where possible. 3 Consultation 3.1 Introduction 3.1.1 There are several key local stakeholders and/or approving authorities associated with the development of the scheme, including the Environment Agency (EA), the LLFA (in this case GCC), water companies and Internal Drainage Boards (IDB), where applicable. The project teams have been in discussion with stakeholders since 2003. 3.1.2 Consultation with the EA and GCC is recorded in the respective Statement of Common Ground, see Statement of Commonality (Document Reference 7.3). A summary of the stakeholder consultations undertaken is presented in the following sections. 3.2 Environment Agency 3.2.1 The EA have wide ranging powers for Main Rivers and groundwater bodies under the Water Resources Act (1991)12 and the Environment Act (1995)13. Under the

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000034 | C01, A3 | 11/03/21 APPENDIX PAGE v A417 Missing Link | HE551505 Highways England

Flood and Water Management Act (2010)14 they have a responsibility to produce a national strategy towards managing flood risk and are a statutory planning consultee for development and flood risk issues. 3.2.2 As a statutory consultee on flood risk matters the EA routinely inspect and assess development proposals. They can impose design criteria and requirements upon the design to ensure that the development itself is not at an unsatisfactory risk of flooding from any source, nor that the development will cause an increase in flood risk elsewhere. 3.2.3 The EA is responsible for managing the risk of flooding from main rivers, reservoirs, estuaries and the sea. They have been involved in various discussions with HE with regards to previous design phases and consultation will continue as the scheme progresses. 3.2.4 Initial feedback from the EA includes the following points:  Data are available online for generating flood maps for planning15, including fluvial and surface water flood extents, reservoir breach risks, flood warning areas (flood warnings are provided for Horsbere Brook which is to the west of the study area) and historic flood extents. These data sets have all been reviewed in the preparation of this FRA.  Data from the EA’s online flood mapping2 indicates that the scheme lies completely within Flood Zone 1 which corresponds to a less than 1 in 1,000 annual probability of river or sea flooding in any year. This is confirmed by the GCC online public flood maps16.  The EA have listed their key concerns in terms of flood risk for the development17. These include risks to the watercourse adjacent to Crickley Hill and concerns around the current drainage system.  The EA have confirmed that modelling a 70% fluvial allowance for climate change must be applied to fluvial flows if fluvial modelling is undertaken in accordance with the new FRA guidance18.  For drainage design, a peak rainfall climate change allowance of 40% is to be applied. This was suggested by the EA and agreed on with GCC19. 3.2.5 Further feedback was provided by the EA in response to the ‘A417 Missing Link Environmental Impact Assessment (EIA) Scoping Report’. Appendix 4.2 Responses to Scoping Opinion (Document Reference 6.4) documents the EA’s response and Highways England’s actions. Points of relevance included:  The EA reiterated their concerns associated with flood risk and encouraged the planned site investigations to determine reliable baseline conditions.  The EA stated it may be necessary to model Ordinary Watercourses where their catchment is below 3km² as these have not been included on the Flood Map for Planning2. This is only necessary for watercourses in close proximity to the scheme; a tributary of Norman’s Brook adjacent to Crickley Hill. 3.2.6 The EA have been contacted regarding the FRA to request Product 420 data for the development area. As the scheme is located in Flood Zone 1, there were no recorded flood outlines and therefore a Product 4 response was not provided. 3.2.7 The information provided by the EA has been used to assess the baseline conditions and identify key flood risks.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000034 | C01, A3 | 11/03/21 APPENDIX PAGE vi A417 Missing Link | HE551505 Highways England

3.3 Lead local flood authority 3.3.1 The LLFA is responsible for developing, maintaining, applying and monitoring a flood risk management strategy for Gloucestershire. For this project this LLFA is GCC, and will be referred to as GCC for the remainder of this document. GCC has made a number of strategic documents available via their website, including:  a Level 1 and Level 2 SFRA published in September 20089,10, which assess all sources of flood risk within its geographic area of responsibility and aligns future development plans with low flood risk areas;  a Preliminary Flood Risk Assessment (PFRA) published in November 201121, which compiles datasets containing historical flooding events from Ordinary Watercourses, surface water, sewers and groundwater; and  a Local Flood Risk Management Strategy (LFRMS) published in summer 201422, which outlines the Council’s role and implementation strategy. This strategy document has been produced in consultation with local partners and focuses on local sources of flooding from surface runoff, groundwater and Ordinary Watercourses. 3.3.2 GCC have been consulted with regards to the assessment of flood risk. A detailed record of consultation is documented in the respective Statement of Common Ground, see Statement of Commonality (Document Reference 7.3). Water company 3.4 Water companies 3.4.1 Severn Trent Water Ltd. (STW) and Thames Water Utilities Ltd. (TWU) are the potable water suppliers and sewerage undertakers with powers under The Water Industry Act 199123. 3.4.2 Under the Flood and Water Management Act, Water and Sewerage Companies are responsible for managing the risks of flooding from surface water and foul or combined sewer systems providing drainage from buildings and yards. 3.4.3 Consultation with STW has identified some of their assets which are being impacted by the scheme. These will result in STW assets being relocated, replaced or upgraded to maintain supply. 3.4.4 There were no TWU utilities identified as being impacted as a result of the scheme. 4 Baseline conditions 4.1 Sources of information 4.1.1 This assessment is based on the sources of information presented in Table 4-1 and initial consultation with key stakeholders (section 3). Whilst some of these documents have been written from a regional perspective, they are able to offer an indication of the wider flood risks that could be of concern to the scheme.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000034 | C01, A3 | 11/03/21 APPENDIX PAGE vii A417 Missing Link | HE551505 Highways England

Table 4-1 Main sources of information used in preparing this document

Source/report title Author Year Level 1 SFRA GCC 2008 Level 2 SFRA Gloucester, Cheltenham and 2011 Tewkesbury Joint Core Strategy PFRA GCC 2011 LFRMS GCC 2014 Level 1 FRA Highways England 2019 Scoping Opinion PINS 2019 EA Consultation Minutes Correspondence between 2018-19 Highways England and EA A417 Missing Link Ground Investigation, Geotechnical Engineering Ltd 2019 Factual Report on Ground Investigation Government Open Data24 Data.gov.uk Accessed 2019 ES Appendix 13.7: Hydrogeological Highways England 2021 Impact Assessment (Document Reference 6.4) Highways Agency Drainage Data Highways England Accessed 2019-2020 Management System (HADDMS) Received drainage records and Several: WSP Civils Ltd, RMS 1993-2002 maintenance information from RMS Ltd. (Gloucester) Ltd, Frank Graham (received May 2020) (DBFO) Consulting Engineers Topographical Survey Conducted by Malcolm Hughes 2019 on behalf of HE 4.2 Site description 4.2.1 The existing A417 is a strategic route between Gloucester and and is located in the Cotswolds AONB, further details are included ES Chapter 2 The project (Document Reference 6.2). 4.3 Topography 4.3.1 Topographical data has been obtained from the Ordnance Survey Open Data25, topographical surveys, Open Government LiDAR and Geostore datasets. The development is located within the Cotswolds AONB and therefore the topography varies significantly across in the area due to the presence of several hills and valleys. The northwest-southeast trending Cotswold escarpment dominates the regional landscape, formed by the Jurassic limestones of the Inferior Oolite Group overlying the weaker, more easily eroded mudstones of the Lias Group. The scheme includes an asymmetrical valley adjacent to Crickley Hill, where the northern slopes are steeper than the southern slopes. The existing A417 runs along the axis of this valley. As detailed in ES Chapter 13 Road drainage and the water environment (Document Reference 6.2), above the escarpment the landscape comprises an extensive plateau that follows the dip of the underlying limestone (2-5° to the east or southeast). 4.4 Fluvial flood risk 4.4.1 Flooding from rivers, streams and other natural inland watercourses is usually caused by prolonged or intense rainfall generating high rates of surface water runoff throughout the catchment. This overwhelms the capacity of the fluvial

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000034 | C01, A3 | 11/03/21 APPENDIX PAGE viii A417 Missing Link | HE551505 Highways England

system as a flood flow and as a result, spills into available floodplain storage areas. 4.4.2 From a review of the main documents presented in Table 4-1 and the water features survey completed between April 2018 and March 2019 (ES Appendix 13.11 Water features survey (Document Reference 6.4)), the general surface water features and catchments of interest have been summarised as follows:  The scheme is located between the River Severn catchment and the River Thames catchment. To the west of the divide, the land drains to the River Severn and its tributaries, including Norman’s Brook (via the tributary of Norman’s Brook), Horsbere Brook and the River Frome. To the east and south-east, the land drains to the River Churn, a tributary of the Thames, via unnamed tributaries.  A tributary of Norman’s Brook lies within the study area, running parallel to and crossing under the existing A417 on Crickley Hill. This will be realigned as part of the scheme. A tracer test was conducted using tracer dye on 6 March 2019 to confirm the tributary is hydraulically connected to Norman’s Brook and not Horsbere Brook as indicated in WFD waterbody delineation and online mapping. However, should the tributary of Norman’s Brook culvert beneath the A417 become blocked, flow could cross the catchment boundary and flow towards Horsbere Brook26. A number of springs and areas of marshy ground have been identified on the slopes below the escarpment which drain into this watercourse. As the watercourse is not a Main River, flood management responsibilities lie with GCC and not the EA.  The watercourses and springs identified are small, ephemeral and have catchment areas less than 3km², and have not been included in the EA fluvial flood modelling. Therefore, even though the EA fluvial flood map2 does not show flood extents in this area, there is still a potential flood risk.  The water features survey (ES Appendix 13.11 Water features survey (Document Reference 6.4)) conducted identified a number of ponds within close proximity, within 35m, to the scheme. 4.5 Surface water (pluvial flood risk) 4.5.1 A potential source of flooding is posed by rainwater that flows across the ground and inundates property or infrastructure before it can reach artificial or natural drainage features. This is a function of ground topography, the nature of the ground surface (permeability, vegetation etc.) and intensity of rainfall. 4.5.2 According to the EA’s online Risk of Flooding from Surface Water (RoFSW) maps2 there is some risk to the scheme in terms of surface water flooding from the tributary of Norman’s Brook, which is the scheme’s most prominent surface water feature. Ponding is also identified at the disused Crickley Hill Farm access bridge; considered to be due to insufficient culvert capacity27. 4.5.3 The RoFSW maps2 indicate a risk of surface water flooding between the Air Balloon roundabout and Cowley roundabout near Shab Hill; which drains towards the River Churn. Surface water flooding is also shown around Watercombe Farm, Castle Hill Cottage and Stockwell Farms, which drains towards the River Frome. These surface water flow paths correspond to headwaters of the tributaries to the River Churn. 4.5.4 The PFRA21 indicates that there are no properties vulnerable to surface water flooding during an extreme rainfall event within the area of the scheme.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000034 | C01, A3 | 11/03/21 APPENDIX PAGE ix A417 Missing Link | HE551505 Highways England

Hydraulic Modelling 4.5.5 A pair of integrated catchment models have been created in MicroDrainage to represent the existing baseline and the scheme to allow for comparison. These models consider both overland flows and those routed through drainage systems. 4.5.6 The principle features included in the baseline 1D model are the main tributary of Norman’s Brook watercourse including culverts, highway and land drainage networks on A417 Crickley Hill and soakaways at A417 Birdlip Hill. The tributary of Norman’s Brook culvert, which runs under the A417, has been represented using the best available data; a combination of as-built drawings, surveys and site visits. From the water feature survey (ES Appendix 13.11 Water features survey (Document Reference 6.4)) it has been determined that the existing watercourse features irregular meanders, a cascade, small ponds and several culverts. The watercourse has been represented in the model as a 600mm deep trapezoidal open channel, with the soffit set at existing ground level. The irregular nature of the channel is accounted for by utilising a high Manning’s co-efficient. 4.5.7 As the catchment of the tributary of Norman’s Brook is less than 3km2 it has not been modelled by the EA to inform the fluvial flood maps2. The baseline catchment model therefore provides an updated overview of flooding of the area surrounding Crickley Hill. 4.5.8 The baseline flood outputs from the MicroDrainage model show similar surface water flood extents to the RoFSW maps2. The integrated model identifies the main flood routes west along Dog Lane and south west across the neighbouring field which corresponds with historical flooding evidence. This area of flooding is linked to the catchment draining through tributary of Norman’s Brook culvert which passes under the existing A417 and along Dog Lane. Further details are provided in section 6.3 and the mapped flood extent is shown in ES Figure 13.20 Crickley Hill Surface Water Flooding - Baseline (Document Reference 6.3). 4.6 Groundwater flood risk 4.6.1 Flooding can occur in locations where groundwater is present at shallow depths. Prolonged periods of rainfall can result in elevated groundwater levels that can lead to the groundwater level reaching the surface as flooding. This can pose a flood risk to developments, particularly basements and cellars. In addition, the emergence of groundwater will prevent infiltration occurring and so will promote the occurrence of overland flow. Groundwater may also exfiltrate to existing surface water drainage systems of poor integrity, reducing their ability to accommodate surface water runoff. 4.6.2 Several watercourses in the study area, such as the tributary of Norman’s Brook, are fed by springs meaning they are ephemeral and do not always have flow in their upper reaches. As a result, these surface watercourses are dependent on groundwater and sensitive to changes in groundwater levels and flows. 4.6.3 The British Geological Survey (BGS) Groundwater Susceptibility dataset indicates there is the potential for groundwater flooding to occur at the surface to the west of Crickley Hill. At Nettleton, in the River Frome headwater valley, there is a potential for groundwater flooding to occur at the surface or below ground. Along Crickley Hill and up to the Severn/Thames catchment divide, and in the southern extent of study area there is a limited potential for groundwater flooding to occur. 4.6.4 The geological characteristics of the study area are detailed in ES Chapter 9 Geology and soils (Document Reference 6.2).

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000034 | C01, A3 | 11/03/21 APPENDIX PAGE x A417 Missing Link | HE551505 Highways England

4.6.5 The hydrogeological characteristics of the study area and groundwater monitoring data is presented in ES Appendix 13.7 Hydrogeological Impact Assessment (Document Reference 6.4). 4.6.6 The ground investigation data has been considered in the development of the groundwater conceptual models. These models primarily focus on the assessment of groundwater quality but also help inform the groundwater flow paths present. The conceptual models are described in detail in ES Appendix 13.7 Hydrogeological Impact Assessment (Document Reference 6.4). 4.6.7 The SFRA9 does not identify the scheme to be at risk from groundwater flooding. 4.7 Artificial drainage systems 4.7.1 Artificial drainage systems designed to manage surface water runoff can pose a flood risk if the system is overwhelmed. This may occur if the amount of surface water runoff exceeds the system capacity or if the system becomes blocked or surcharged by the receiving watercourse. Artificial drainage systems designed to manage foul water (and combined effluent) can pose a flood risk and public health risk if the system is overwhelmed. This may occur if the amount of foul water allowed to discharge exceeds the system capacity. 4.7.2 Existing artificial drainage systems (foul, combined and surface) could pose a flood risk to the site in the event of failure. This would result in water (possibly contaminated) exploiting the overland flow routes. 4.7.3 For the scheme, the Highways Agency Drainage Data Management System (HADDMS) was used to understand current drainage. This database does not indicate conclusively what is connected and where the surface water discharges. The information available indicates that the drainage for this section of the road has been developed extensively over the time along with highway improvements resulting in several different approaches. These consist of gullies, concrete surface water channels, filter drains, carrier drains, ditches and soakaways. The network also appears to operate under free-flow conditions, with unconstrained discharges and limited attenuation. 4.7.4 The HADMMS database does not identify any flooding hotspots within the scheme area. 4.7.5 The topographic survey identified surface drainage elements such as gullies and manhole covers but did not include the survey of any below ground buried structures and services. The culverted section of the tributary of Norman’s Brook was initially omitted which was required to better understand artificial drainage flood risk. Given the importance of this culvert to the scheme, a topographic survey was commissioned to identify the route, size and levels of the culverted section of the watercourse located along the southern toe of Crickley Hill. The findings of this survey were reported in January 2020 but again did not provide complete line and levels for the culvert. Through several site-visits and as-built records, sufficient information of the culvert has since been obtained to allow it to be adequately represented in the hydraulic modelling undertaken for this scheme. 4.7.6 Based on available records it is considered that the existing A417 between Parsons Pitch and the current Air Balloon roundabout drains predominantly to groundwater via soakaways. Elsewhere the existing A417 within the study area drains to watercourses.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000034 | C01, A3 | 11/03/21 APPENDIX PAGE xi A417 Missing Link | HE551505 Highways England

4.7.7 The tributary of Norman’s Brook runs adjacent to the existing A417 between Crickley Hill Farm and Air Balloon roundabout and it is assumed that the runoff from the adjacent highway is discharged to this watercourse before passing beneath the A417 in culvert. This assumption was confirmed by the records received by the DBFO28. 4.8 Infrastructure flooding 4.8.1 Where infrastructure exists that retains, transmits or controls the flow of water, flooding may result if there is a structural, hydraulic, geotechnical, mechanical or operational failure. This may be infrastructure that has been specifically designed and implemented as a water controlling structure, such as a water main or a dam. It may also be a structure such as a road or rail embankment. No such infrastructure was identified. 4.9 Historic flooding 4.9.1 Historic flooding is often a good indicator for future flooding. According to the EA’s Historic Flood Map there are no recorded incidents of fluvial flooding within the site however this dataset is not definitive and may not capture the whole extents of all historic flooding. The PFRA does not mention flooding in the specific area of the site, but there have been significant flood events in the past associated with high levels of rainfall such as summer 2007 where culverted watercourses and drainage systems were overwhelmed21. 4.9.2 Historical evidence of flooding along Dog Lane revealed that the culverted length of the tributary of Norman’s Brook which passes beneath Dog Lane, regularly exceeds capacity and lifts the manhole cover off in front of the property associated with Witcombe Supplies. Surface water flooding from heavy rainfall events frequently flows down Dog Lane, before bearing left along Bentham Lane towards Little Witcombe. This takes water from the Norman’s Brook catchment across to the Horsbere Brook catchment. 4.9.3 Evidence around the A417 Flyup highlighted the issue of the tributary of Norman’s Brook culvert becoming blocked, with flow passing out of bank and flowing alongside the existing A417 to the south and flowing onto Bentham Lane towards Little Witcombe and the Horsbere Brook catchment. 5 Sequential and exception test 5.1 Sequential test 5.1.1 Data from the EA’s online flood mapping2 indicates that the scheme lies within Flood Zone 1 but as the site is greater than 1ha in area a Sequential Test is still required. The development can be classed as ‘essential infrastructure’9 due to the necessity of the development to improve regional transport routes. 5.1.2 This FRA details the flood risk associated with the proposed A417 Missing Link scheme outlined in Chapter 2 The Project (Document Ref 6.2). 5.1.3 As the development is classed as ‘essential infrastructure’ and is in Flood Zone 1, it passes the Sequential Test in accordance with Table 3 in the NPPF Technical Guidance5. 5.2 Exception test 5.2.1 The Exception Test, as set out in the NPPF and outlined in Section 3.2 is a method used to demonstrate and help ensure that flood risk to people and

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000034 | C01, A3 | 11/03/21 APPENDIX PAGE xii A417 Missing Link | HE551505 Highways England

property will be managed satisfactorily, while allowing necessary development to go ahead in situations where suitable sites at lower risk of flooding are not available. It is comprised of two parts:  demonstration that the site will provide wider sustainability benefits to the community that outweigh flood risks; and  that it will be safe for its lifetime, without increasing flood risk elsewhere and where possible reduce flood risk overall. 5.2.2 As the scheme lies within Flood Zone 1 and is classified as ‘essential infrastructure’ an Exception Test is not required in accordance with Table 3 in the NPPF Technical Guidance5 . 6 Flood risk assessment 6.1 Flooding sources 6.1.1 In line with best practice this section of the FRA considers flood risk from a range of possible sources. Based on a review of relevant policies, the nature of the development and the baseline information in Section 4 the following sources of flooding have been considered in detail:  Fluvial: floodwater originating from watercourse when the amount of water exceeds the channel capacity of that watercourse.  Surface Water: flooding caused by intense rainfall exceeding the available infiltration and/or drainage network capacity.  Groundwater: flooding caused when groundwater levels rise above ground level following prolonged rainfall, obstructions to groundwater flow or rebound of previously depressed groundwater levels.  Artificial Drainage Systems: flooding originating from surface water, foul or combined drainage systems, typically caused by limited capacity or blockages. 6.2 Fluvial flood risk 6.2.1 As the site is within Flood Zone 1, there is a limited risk of fluvial flooding. There is only one significant Ordinary Watercourse within the scheme footprint (the tributary of Norman’s Brook located along the southern toe of Crickley Hill) and no specific recorded events of historic flooding. The lack of fluvial flood extents shown on EA flood mapping2 is due to the watercourses in the study area being too small to be modelled by the EA. 6.2.2 The tributary of Norman’s Brook which flows adjacent to the existing A417 approximately midway between the Brockworth bypass and Air Balloon roundabout needs to be realigned as part of the scheme. This is due to the widening of the highway to the south of the existing alignment where the tributary is located. The watercourse lies in a valley and existing constrictions and topography provide online attenuation. 6.2.3 A change in the flow pathway may impact on properties and aquatic environments close to flood zones. In particular, culverting or the realignment of the tributary of Norman’s Brook may result in flooding further upstream and downstream without appropriate mitigation to attenuate flows. 6.2.4 Within the current design of the scheme, the channel will be realigned further up the valley side. It is anticipated that as the design becomes more detailed, the specific design details of the realigned channel, including its precise location, will

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000034 | C01, A3 | 11/03/21 APPENDIX PAGE xiii A417 Missing Link | HE551505 Highways England

be informed by detailed hydraulic modelling to ensure that flood risk to the site and elsewhere is not increased, and where possible reduced. 6.2.5 This assessment indicates there is low risk of fluvial flooding to, or from the site. 6.3 Surface water (pluvial) flood risk 6.3.1 The additional lanes associated with the scheme could result in increased rates and volumes of surface water runoff, resulting from an increase in impermeable area or changes to the existing drainage regime. The scheme also results in a greater catchment area draining to the watercourse adjacent to Crickley Hill arising from the significant cutting between Shab Hill and the Air Balloon roundabout. This could lead to a potential increase in surface water flood risk. For this assessment the scheme has been considered in two sections; Cowley to the Air Balloon roundabout and Air Balloon roundabout to Brockworth bypass. 6.3.2 An assessment of the surface water flood risk has been undertaken based on the EA’s RoFSW map data set2, analysing the topography of the site and from a site walkover. This was further supported by hydraulic modelling (detailed in Sections 4.5 and 6.3) of the Crickley Hill section to improve the understanding of flood risk from the tributary of Norman’s Brook. This baseline understanding has been used to inform the scheme’s drainage design and surface water management. 6.3.3 There is a very low to low risk of flooding from surface water along the section of the existing A417 highway that lies between the Cowley and Air Balloon roundabouts. 6.3.4 Surface water flooding has been identified to the east of the scheme at Stockwell Farm Barn, between Cowley roundabout and Shab Hill. This forms a flow path which becomes the headwaters of the River Frome. A second surface water flow path is shown passing through Shab Hill Farm which forms the headwaters of the River Churn. 6.3.5 These surface water flow paths are not associated with a permanent watercourse but most likely arises due to the topography and the presence of a dry valley. This assessment indicates here is a medium risk of surface water flooding to, or from the scheme at this location. 6.3.6 Along the section between Air Balloon roundabout and the Brockworth bypass there is a high surface water flood risk following the channel of the tributary of Norman’s Brook. The EA RoFSW maps2 indicate that the surface water flow path passes up onto, then along the A417; it is not clear whether the EA modelling has taken account of the culvert beneath the A417. The site visit indicated that the A417 is raised slightly above the natural ground levels, so would likely intercept flow, and divert at least some of it south towards Bentham Lane should the culvert capacity be reached or become blocked. This is corroborated against historical evidence of flooding in the area. 6.3.7 As discussed previously, the scheme encroaches on the land where this watercourse flows, and provides attenuation, necessitating the realignment of the channel. 6.3.8 A site visit identified that the channel and car park area, upstream of NGR SO922157 backs up due to the limited capacity of the culvert. This has resulted in significant ponding and subsequent attenuation of flows and resulted in the car park being under approximately 300mm of water. Photographs and video footage (taken on 9 January 2020) also show water flowing from the site and following the

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000034 | C01, A3 | 11/03/21 APPENDIX PAGE xiv A417 Missing Link | HE551505 Highways England

access track, located to the south of the existing A417, and joining with flood waters along Bentham Lane, heading towards Witcombe. 6.3.9 Evidence of historical flooding obtained on a site visit near Holly Brae Farm (Witcombe Supplies), north of the existing A417 and adjacent to Dog Lane, highlighted the fact that the culverted tributary of Norman’s Brook often exceeds the culvert capacity and forces the manhole off in front of the property (Photograph 6-1). The resulting surface water then flows along Dog Lane and down Bentham Lane towards Witcombe and the Horsbere Brook catchment, rather than continuing to the Norman’s Brook catchment.

Photograph 6-1 Manhole located along Dog Lane which lifts under high flow conditions Hydraulic Modelling 6.3.10 It is recognised that the impacts of the scheme on the catchment of the tributary of Norman’s Brook are more complex than in other areas. To improve the understanding of flood risk around Crickley Hill and allow impacts from the scheme to be assessed, integrated catchment models have been built using MicroDrainage hydraulic analysis software along with the FloodFlow module combining overland flows, watercourses, and highway collection systems. 6.3.11 The models allow the impact of the scheme to be compared against the baseline scenario taking in to account overland flows (2D) and through buried (and open) drainage systems (1D). The model has been verified against peak flows estimated using the Revitalised Flood Hydrograph (ReFH2) Rainfall-Runoff software. Given the size of the catchment an uplift of 40% to account for climate change was applied to the 100-year rainfall event in accordance with national planning guidance. 6.3.12 The catchment models give an improved understanding of baseline flood risk. As discussed in Section 4.5, the baseline maps demonstrate similar flood extents to the RoFSW maps2 with the exception of additional flooding visible on Dog Lane. This additional flooding is a result of the more accurate representation of the tributary of Norman’s Brook culvert and corroborates recorded evidence of flow paths in this area. 6.3.13 A hydraulic capacity assessment of the culvert running alongside Dog Lane was undertaken which found that the flooding threshold at Dog Lane corresponds approximately to the peak flow for a storm event between the 1-year and 5-year return period. In events up to the 1 in 100-year event, the upstream culvert beneath the A417 has sufficient capacity to convey the peak flows but will result in significant flooding along Dog Lane. It was also found that the 1 in 100-year

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000034 | C01, A3 | 11/03/21 APPENDIX PAGE xv A417 Missing Link | HE551505 Highways England

+CC (40%) event is likely to result in surcharge and flooding at the culvert headwall. 6.3.14 The scheme model incorporates new highway drainage networks, attenuation basins and land drainage ditches which constitute the drainage strategy in this location (details provided in ES Appendix 13.10 Drainage Report (Document Reference 6.4)). The topographical data is formed of a composite surface comprising the wider existing topographic survey merged with the new highway design surfaces generated from CAD earthworks and 3D road alignment models. 6.3.15 The key assumption in the proposed design is that the hydraulic performance and characteristics of the realigned watercourse will replicate the existing. 6.3.16 The initial outputs from the integrated model for the scheme indicate that the peak flows arriving at the top of the culvert lie within the envelope of the baseline hydrograph as shown in Table 6-1. This addresses GCC’s request that the scheme will not increase flood risk at this location. The mapped flood extent is provided in ES Figure 13.21 Crickley Hill surface water flooding – scheme (Document Reference 6.3). Table 6-1 Flows for the tributary of Norman’s Brook for a range of return periods

Return Period Peak Flow (l/s) (345-minute winter storm) Existing Proposed 1 in 100-year + climate change 1,365 1,315 1 in 100-year 1,100 881 1 in 50-year 1,008 771 1 in 30-year 806 619 1 in 5-year 564 387 1 in 1-year 233 187 6.3.17 The trend visible in the 1 in 100-year plus climate change allowance (40%) (Table 6-1) is maintained through other return periods and shows a reduction in both peak flow and discharge volume. 6.3.18 This assessment indicates there is a medium risk of surface water flooding to, and from the scheme along Crickley Hill. 6.3.19 The next iteration of the MicroDrainage model at detailed design will look at incorporating any further changes to the drainage design and to extend analysis to other key points of interest along the route as the scheme design develops. 6.4 Groundwater flood risk 6.4.1 The assessment of groundwater flood risk has been informed by the groundwater conceptual model and ongoing monitoring which are detailed in ES Appendix 13.7 Hydrogeological Impact Assessment (Document Reference 6.4). 6.4.2 Within and nearby to the scheme there are several springs which could be impacted. This could have an adverse effect and cause a risk to the scheme or divert flood risk elsewhere 6.4.3 As detailed in section 13.8 of ES Chapter 13 Road drainage and the water environment (Document Reference 6.2), changes in flow paths could result from the introduction of below ground structures, excavations or embankments within the aquifers which may reduce flow to groundwater receptors, resulting in the

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000034 | C01, A3 | 11/03/21 APPENDIX PAGE xvi A417 Missing Link | HE551505 Highways England

partial or total loss of springs and depletion of existing watercourses and conversely, the creation of new springs and/or localised groundwater flooding due to groundwater mounding up-gradient of the structure. 6.4.4 High rates of infiltration to groundwater during excessive rainfall events may result in the reactivation of springs or increased stream flow. This could lead to excess flow in cuttings, and the drainage system being overwhelmed. 6.4.5 Cuttings and deep piled foundations associated with scheme structures may cause local changes to groundwater flow and could induce groundwater flooding. These impacts are however likely to be localised. 6.4.6 This assessment indicates there is medium to high risk of ground water flooding to, and from the scheme. Groundwater monitoring is being undertaken as part of the ground investigations. The results of these investigations and the groundwater conceptual model will inform the need for any mitigation to be incorporated during detailed design. 6.5 Artificial drainage systems 6.5.1 The current drainage system allows free discharge and has limited attenuation and it is presumed that the surface water runoff from the existing A417 upstream of the tributary of Norman’s Brook culvert discharges into the tributary of Norman’s Brook. With the proposed widening of the A417 and subsequent additional impermeable area, an appropriate drainage network is required to manage runoff. Unattenuated discharge into the tributary of Norman’s Brook would increase the existing level of flood risk, both to receptors along Dog Lane and Witcombe, via Bentham Lane. 6.5.2 Surface water from land south-west of the scheme’s cutting between the Air Balloon roundabout and Shab Hill junction currently flows to the River Churn catchment via dry valleys at Leckhampton Hill and Ullenwood, which converge at the National Star College golf course. As a result of the scheme there would be a net increase of up to 23 ha in the catchment area to the tributary of Norman’s Brook and a corresponding reduction in the catchment area to the River Churn. This would return the catchments to a situation closer to the natural delineation that existed before the A417 Birdlip Bypass scheme was constructed (1987). 6.5.3 The mitigation for the artificial drainage flood risk is described in detail in ES Appendix 13.10 Drainage Report (Document Reference 6.4). 6.5.4 This assessment indicates that given the proposed drainage strategy there is a low risk of artificial drainage flooding to, or from the site. 7 Flood risk mitigation 7.1.1 The scheme has been designed and configured in a manner that takes flood risk into consideration. The following section outlines mitigation measures for dealing with the risk identified in this assessment. 7.1.2 The mitigation is documented in Table 3-2: Register of environmental actions and commitments (REAC) in ES Appendix 2.1 Environmental Management Plan (EMP) (Document Reference 6.4). 7.1.3 Given the outcomes of the FRA (section 6) the mitigation will focus on the following:  fluvial flood risk

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000034 | C01, A3 | 11/03/21 APPENDIX PAGE xvii A417 Missing Link | HE551505 Highways England

 surface water flood risk  groundwater flood risk  artificial drainage flood risk 7.2 Fluvial flood risk 7.2.1 The only watercourse that is directly impacted by the scheme is the tributary of Norman’s Brook that flows along the southern toe of Crickley Hill. No fluvial flood risk has been modelled for this watercourse; given the small catchment size. Flooding of this watercourse is linked to intense rainfall events and therefore covered in the surface water flood risk (section 7.3). 7.2.2 The channel realignment would be designed to ensure that flood risk is not increased as a result of the scheme. Flood mitigation methods associated with the realignment of the tributary of Norman’s Brook include maintaining the character and geomorphology of the existing stream through reintroducing cascades and meanders and identifying possible sections of the culverted watercourse that could be de-culverted and naturalised. 7.2.3 The design of the features will be developed at detailed design. The channel design will be informed by the ecological surveys (ES Appendix 8.23 River Habitat Survey and Fish Habitat Assessment (Document Reference 6.4)) and hydromorphology surveys (ES Appendix 13.5 Hydromorphological Assessment (Document Reference 6.4)), along with flow monitoring (ES Appendix 13.12 Water Environment Monitoring Data (Document Reference 6.4)). A 5-metre-wide earthworks platform along the southern edge of the widened road embankment has been developed, within which there will be a smaller channel to convey typical flows in the watercourse. 7.3 Surface water flood risk 7.3.1 In accordance with the National Standards for Sustainable Drainage29, a surface water drainage design incorporating the use of Sustainable Drainage Systems (SuDS), where possible, is required to accompany an FRA and planning application. The hierarchy of surface water management practices is as follows, from most preferred to least preferred:  store rainwater for later use (e.g. rainwater harvesting)  discharge to ground (infiltration)  discharge to a surface waterbody  discharge to a surface water sewer, highway drain or other drainage system  discharge to a combined sewer 7.3.2 With regards to surface water management, GCC stipulates in its SFRA10 that:  developments should not increase the peak discharge/volume from any existing Greenfield site  Attenuation should be provided to a 1 in 100-year standard taking into account the impact of climate change  space should be set aside to incorporate SuDS 7.3.3 GCC standing advice30 states that for developments which were previously developed the peak runoff rate from the development to any drain, sewer or surface water body up to the 1 in 100 year rainfall event + 40% for climate change should reduce the surface water discharge by 40% of that existing or be as close as is reasonably practicable to the greenfield runoff rate from the development for

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000034 | C01, A3 | 11/03/21 APPENDIX PAGE xviii A417 Missing Link | HE551505 Highways England

the same rainfall event, but in any event should never exceed the rate of discharge from the development prior to redevelopment for that event 7.3.4 For the scheme the surface water management will be partly incorporated within the drainage design. 7.3.5 The section of the scheme between Cowley and the Air Balloon roundabout that crosses surface water flow paths will incorporate appropriately sized culverts, or equivalent structure, to allow the free passage of water beneath the scheme. The hydrological estimates associated with the structure design will be made using industry standard methodologies. 7.3.6 The hydraulic modelling results indicate that the scheme will not increase flood risk at the top of the tributary of Norman’s Brook culvert as the peak flows lie within the envelope of the baseline hydrograph. There are opportunities to reduce the peak flows further by providing attenuation within the upstream catchment such as debris dams and other Natural Flood Management (NFM) measures within the watercourse channel, storage within the perimeter ditch network and source control in the highway drainage system. 7.3.7 The model has scope to be expanded in area to assess the flood risk associated with other points of interest along the route. 7.4 Artificial drainage flood risk 7.4.1 The drainage design will ensure adequate protection for the scheme, and neighbouring receptors, against flooding. 7.4.2 GCC require adherence to the SuDS hierarchy; meaning that the drainage strategy should, where possible, mimic the natural hydrology of the site. In this respect soakaways would be the preferred surface water disposal technique, rather than opting to connect to a watercourse or sewer. The drainage for the scheme will be designed in accordance with the Design Manual for Roads and Bridges (DMRB). 7.4.3 The local roads will also incorporate GCC drainage requirements. As the adopting highway authority, if GCC requires variation to DMRB design, standards and specification then these will take precedence. 7.4.4 The following parameters have been used for highway drainage:  The highway drainage will be sized to convey a 1 in 1-year return period event including a 20% uplift for climate change without surcharging in accordance with DMRB.  The design will ensure that there is no surface water flooding on the highway for a 1 in 5-year event with an allowance for climate change.  The highway drainage system is assessed for events up to a 1 in 100-year return period event with a 40% climate change uplift and attenuation basins are sized for a +40% climate change uplift. 7.4.5 Where reconfiguration of the existing local roads will require new drainage to connect into existing networks, the proposals will provide a like for like or reduction of impermeable area. Where there is a net increase in paved area attenuation will be provided. 7.4.6 The strategy splits the scheme into several drainage catchments, each of which has a proposed drainage solution. The following lists provisions within the overall drainage strategy:

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000034 | C01, A3 | 11/03/21 APPENDIX PAGE xix A417 Missing Link | HE551505 Highways England

 A range of collection systems, including gullies, concrete or grass surface water channels and filter drains to collect surface water flows from the existing A417 carriageway.  Perimeter ditches, swales, or field drains to intercept overland runoff where external catchments drain towards the scheme.  Filter drains or fin drains will be provided in all mainline super-elevated central reserves and alongside low side carriageway verges to ensure adequate drainage of the road pavement and foundations.  Filter drains at toes of new earthworks and existing slopes to intercept run-off from earthwork slopes and ensure stability of cuttings and embankments.  Several locations have been identified for basins to attenuate discharge, all of which will have flow control devices on the outfall. There are currently 12 drainage basin sites planned but these are being refined as the drainage design develops.  Whilst soakaways are to be implemented wherever possible, their use will be limited to specific sites where they will be effective. Their use may also be restricted in locations where it is necessary to avoid undermining earthworks or existing sensitive slopes. 7.4.7 The drainage strategy will adhere to the SuDS hierarchy, but where infiltration is not possible, the surface runoff will be attenuated to Greenfield Runoff Rates (GFRR). 7.4.8 Further details of artificial drainage can be found in ES Appendix 13.10 Drainage Report (Document Reference 6.4). 7.5 Groundwater flood risk 7.5.1 The potential impacts from scheme upon groundwater resources and groundwater dependent features including local springs and dry valleys are assessed in ES Chapter 13 Road drainage and the water environment (Document Reference 6.2) and ES Appendix 13.7 Hydrogeological Impact Assessment (Document Reference 6.4) and mitigation outlined. 7.5.2 Cuttings and retaining structures within cuts are planned to have suitable drainage measures 1m below the adjacent finished road level. 7.5.3 The drainage design will be configured to manage inflows so that intercepted groundwater flows will remain within the catchment of the respective receiving waterbody, where possible. The intercepted groundwater will be carried from the horizontal drains to a surface water discharge point, within the same receiving water that the groundwater would naturally have discharged to. 7.5.4 The groundwater captured within the Air Balloon cutting drainage network will be carried downstream of the cutting and will feed back into the realigned tributary of Norman’s Brook.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000034 | C01, A3 | 11/03/21 APPENDIX PAGE xx A417 Missing Link | HE551505 Highways England

8 Conclusions and recommendations 8.1.1 The scheme is located between Gloucester and Swindon and involves upgrading the existing single carriageway to a dual carriageway; to match the rest of the route. The scheme lies within the Cotswolds AONB and the topography varies significantly across the site. 8.1.2 This FRA has been completed based on information available online, data provided as part of the consultation exercise and from site investigations and MicroDrainage modelling. 8.1.3 The scheme intercepts surface water features such as watercourses and ponds, many of which are spring fed. 8.1.4 Consultation has been carried out with the EA and GCC. 8.1.5 Groundwater monitoring and modelling is presented in the ES Appendix 13.7 Hydrogeological Impact Assessment (Document Reference 6.4). The groundwater model which has been developed provides initial indications about the impact of the scheme on groundwater. 8.1.6 The EA previously confirmed that a 70% uplift be applied to the 100-year fluvial flows and a 40% uplift applied to the peak rainfall totals for smaller catchments (<5km²) to account for climate change. Given the size of the tributary of Norman’s Brook catchment and that modelling has been based on a direct rainfall approach to evaluate surface water flooding, a 40% uplift to account for climate change was adopted. 8.1.7 A hydraulic model has been constructed for the Crickley Hill area to inform understanding of both baseline and proposed surface water flooding and to ensure flows are not being increased as a result of the scheme. A more detailed representation of the existing and proposed channels of the tributary of Norman’s Brook will be included in the model at detailed design. 8.2 Summary of flood risk 8.2.1 Fluvial flood risk: The entirety of the scheme lies within Flood Zone 1 and therefore is at very low risk of fluvial flooding. The tributary of Norman’s Brook will be realigned as part of the scheme. 8.2.2 Surface water flood risk: The majority of the scheme is at a very low risk of flooding from surface water but there are a few areas of high surface water flood risk shown on the EA flood maps2 and the integrated hydraulic model. 8.2.3 Between the Cowley and Air Balloon roundabouts, the scheme crosses a surface water flow path near Shab Hill Farm. Suitably sized structures will be included in the design to ensure free passage of surface water flows. 8.2.4 The tributary of Norman’s Brook flowing down Crickley Hill presents a significant surface water flood risk which might be exacerbated by the realignment of this channel and increase in drainage area as part of the scheme. The baseline modelling has improved the understanding of the current surface water flood risk. 8.2.5 The scheme around Crickley Hill has also been modelled and initial results indicate that with the proposed drainage strategy the scheme will not increase flood risk here or further downstream. However, there is still a residual risk should the tributary of Norman’s Brook culvert reach capacity or become blocked.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000034 | C01, A3 | 11/03/21 APPENDIX PAGE xxi A417 Missing Link | HE551505 Highways England

8.2.6 Based on the current understanding of the surface water flood risk for the scheme, the risk is considered to be medium. 8.2.7 Groundwater flood risk: There are several springs and watercourses that are groundwater fed within the scheme footprint. The hydraulic link between groundwater levels and the surface water features is being determined by the ongoing ground investigation monitoring, which is assessed as part of the ES Chapter 13 Road drainage and the water environment (Document Reference 6.2) and detailed in ES Appendix 13.7 Hydrogeological Impact Assessment (Document Reference 6.4). Due to the potential impact on groundwater from elements of the scheme such as cuttings and buried structures, the groundwater flood risk at this stage is considered to be medium. 8.2.8 Artificial drainage flood risk: The existing network appears to operate under free-flow conditions with unconstrained discharges and negligible attenuation. The scheme will increase the drainage catchment areas and surface runoff rates from the increased impermeable area but has been accounted for within the scheme’s drainage strategy (ES Appendix 13.10 Drainage Report (Document Reference 6.4. The flood risk associated with artificial drainage is considered low. 8.3 Flood mitigation 8.3.1 The mitigation outlined in this section is documented in Table 3-2: Register of environmental actions and commitments (REAC) in ES Appendix 2.1 EMP (Document Ref 6.4). 8.3.2 Fluvial flood risk: Fluvial flood risk has not been identified. 8.3.3 The realignment of the tributary of Norman’s Brook would be designed to cater for the ecological requirements of aquatic species present in the tributary of Norman’s Brook. The barriers (man-made weirs) currently present within the tributary of Norman’s Brook would not be recreated in the new channel, which would be characterised by step-pool habitat, typical of higher gradient headwater streams. The new channel would improve connectivity of habitat for aquatic species. 8.3.4 Surface water flood risk: Surface water management will be partly incorporated within the scheme’s drainage design. The hydraulic model will be used to inform the detailed design to ensure any residual surface water flood risk is mitigated. 8.3.5 Where the scheme passes over surface water flood flow paths, culverts will be designed to accommodate flow. The hydrology for the catchment draining to this point will be estimated using modelling or industry standard methods and used to size the structures to reduce ponding or flood risk. 8.3.6 Attenuation methods will also be implemented if necessary, as further mitigation and to reduce peak flows entering the drainage network such as at the tributary of Norman’s Brook culvert. 8.3.7 Mitigation has been considered for construction of the scheme as well as specifically for the realignment of the tributary of Norman’s Brook. The general measures include the implementation of a temporary surface water management system early on in the construction sequencing and ensuring site compounds and all plant and material used to be stored outside of the floodplain. Specifically, for the tributary of Norman’s Brook, it will be ensured that the temporary works will have suitable provisions to pass high flows, and the water within the catchment

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000034 | C01, A3 | 11/03/21 APPENDIX PAGE xxii A417 Missing Link | HE551505 Highways England

area will be monitored. Full details of the flood risk mitigation for the construction process is provided in ES Appendix 2.1 EMP (Document Ref 6.4). 8.3.8 Opportunities for SuDS considering both flood attenuation and water quality are identified where possible along the scheme. 8.3.9 Groundwater flood risk: The drainage design includes aspects of groundwater flood risk management such as managing inflows so that the intercepted groundwater flows would remain within the catchment of the respective receiving waterbody. 8.3.10 Artificial drainage flood risk: The drainage design for the scheme incorporates gullies, concrete surface water channels, filter drains, carrier drains, ditches, attenuation basins and soakaways. Highway runoff will not be allowed to discharge freely, instead attenuation basins and swales are being incorporated into the drainage design to manage this.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000034 | C01, A3 | 11/03/21 APPENDIX PAGE xxiii A417 Missing Link | HE551505 Highways England

References

1 Flood Zone 2 comprises land assessed as having between a 1 in 100 (1%) and 1 in 1,000 (0.1%) annual probability of river flooding; Flood Zone 3 comprises land assessed as having a 1 in 100 (1%) or greater annual probability of river flooding 2 Environment Agency (2019). Online Flood Risk Mapping. https://flood-warning- information.service.gov.uk/long-term-flood-risk/map 3 Land having a less than 1 in 1,000 annual probability of river or sea flooding. (Shown as ‘clear’ on the Flood Map – all land outside Zones 2 and 3) 4 Ministry of Housing, Communities & Local Government (MHCLG) (2019) Revised National Planning Policy Framework (NPPF). https://www.gov.uk/government/collections/revised-national- planning-policy-framework 5 DCLG (2012). NPPF Technical Guidance. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/ 6000/2115548.pdf 6 CIRIA (2004). C624 – Development and Flood Risk. https://www.ciria.org/ItemDetail?iProductCode=C624&Category=BOOK 7 Pitt (2010) Learning Lessons from the 2007 floods. Available Online: https://webarchive.nationalarchives.gov.uk/20100702215619/http://archive.cabinetoffice.gov.uk/pitt review/thepittreview/final_report.html 8 Department for Transport (2014) National Policy Statement for National Networks. Available online: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/ 387222/npsnn-print.pdf 9 Halcrow Group Ltd on behalf of Gloucestershire County Council (2008) Strategic Flood Risk Assessment Level 1. Available at: https://www.gloucestershire.gov.uk/media/6830/gloucestershire_level_1_sfra_exec_summary_final -28389.pdf 10 Gloucester, Cheltenham and Tewkesbury Councils (2012) Level 2 SFRA for local development framework. Available at: https://www.cheltenham.gov.uk/download/downloads/id/3077/sfra_level_2_- _executive_summary.pdf 11 Gloucester, Cheltenham and Tewkesbury Councils (2017) Joint Core Strategy 2011-2031 12 Her Majesty’s Stationary Office (HMSO) (1991). Water Resources Act. 13 Her Majesty’s Stationary Office (HMSO) (1995). Environment Act. 14 Her Majesty’s Stationary Office (HMSO) (2010). Flood and Water Management Act. 15 Environment Agency (Website): https://flood-map-for-planning.service.gov.uk/ 16 Gloucestershire County Council (website) https://www.gloucestershire.gov.uk/planning-and- environment/flood-risk-management/flood-planning-information/flood-zones-in-gloucestershire/ 17 Correspondence between HE and The Environment Agency (17.05.2019) 18 Correspondence between HE and the Environment Agency (31.08.2017) 19 Correspondence between HE and the Environment Agency (08.03.2019) 20 Freely available data published by central government, local authorities and public bodies https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications 21 Gloucestershire County Council (2011) Preliminary Flood Risk Assessment. Available at: https://www.gloucestershire.gov.uk/media/5737/1_gcc_pfra_-_report_-rev_4-_november_2011- 49979.pdf 22Gloucestershire County Council (2014) Local Flood Risk Management Strategy. Available at: https://www.gloucestershire.gov.uk/media/2189/1_glos_local_strategy_summer_2014_- main_document-61257.pdf 23 HMSO (1991). Water Industry Act. https://www.legislation.gov.uk/ukpga/1991/56/contents 24 Freely available data published by central government, local authorities and public bodies. https://data.gov.uk/

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000034 | C01, A3 | 11/03/21 APPENDIX PAGE xxiv A417 Missing Link | HE551505 Highways England

25 OS Open Data: https://www.ordnancesurvey.co.uk/business-and-government/products/terrain- 50.html 26 Mott Macdonald Sweco (2019) A417 Tracer Test. Document ref: HE551505-MMSJV-EWE-000- RP-LX- 00003 27 Highways England (2019) Level 1 FRA 28 Records received from RMS Ltd (1993-2002) featuring historic drainage information and as-built drawings 29 Freely available data published by central government, local authorities and public bodies https://www.susdrain.org/delivering-suds/using-suds/legislation-and-regulation/national-standards- for-sustainable-drainage.html 30 GCC (2015) Standing Advice and Development Guidance https://www.gloucestershire.gov.uk/media/16743/standing-advice-march-2015.pdf

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000034 | C01, A3 | 11/03/21 APPENDIX PAGE xxv A417 Missing Link TR010056

6.4 Environmental Statement Appendix 13.4 Water Quality Assessment

Planning Act 2008

APFP Regulation 5(2)(a) Infrastructure Planning (Applications: Prescribed Forms and Procedure) Regulations 2009

Volume 6

May 2021 A417 Missing Link | HE551505 Highways England

Infrastructure Planning

Planning Act 2008

The Infrastructure Planning (Applications: Prescribed Forms and Procedure) Regulations 2009

Regulation 5(h)

A417 Missing Link

Development Consent Order 202[x]

6.4 Environmental Statement Appendix 13.4 Water Quality Assessment

Regulation Number: 5(2)(a) Planning Inspectorate TR010056 Scheme Reference Application Document Reference 6.4 Author: A417 Missing Link

Version Date Status of Version C01 May 2021 Application Submission Environmental Statement | HE551505 Highways England

Table of Contents Pages 1 Introduction i 2 Assessment of pollution impacts from routine runoff on surface waters i 2.1 Introduction i 2.2 Methodology i 2.3 Results – without mitigation iii 2.4 Mitigation iv 2.5 Results – with mitigation iv 3 Assessment of pollution impacts from routine runoff on groundwater v 3.1 Introduction v 3.2 Methodology v 3.3 Results vi 3.4 Mitigation vi

Table of Tables Table 2-1 Inputs used for the surface water quality assessment ii Table 2-2 Input data for HEWRAT assessments iii Table 2-3 Summary of routine runoff assessments iii Table 2-4 Indicative treatment efficiencies (from CG 501, Table 8.6.4N3) iv Table 2-5 Summary of proposed pollutant treatment iv Table 3-6 Overall risk scores vi Environmental Statement | HE551505 Highways England

1 Introduction

1.1 Purpose of this Document 1.1.1 This document summarises the assessment of potential impacts to surface water and groundwater quality as a result of the scheme. These assessments have been undertaken in accordance with Design Manual for Roads and Bridges (DMRB) LA 113 Road Drainage and the Water Environment. 2 Assessment of pollution impacts from routine runoff on surface waters

2.1 Introduction 2.1.1 The assessment of potential effects from routine runoff on surface water quality has been undertaken using the Highways England Water Risk Assessment Tool (HEWRAT), as prescribed in DMRB LA 113. 2.1.2 The Environment Agency (EA) has approved the method of assessment used by HEWRAT and has agreed that the outputs from the tool can be used to undertake an assessment of the potential impacts on surface water quality.

2.2 Methodology 2.2.1 HEWRAT adopts the following tiered approach:  Step 1: Runoff quality. This predicts concentrations of pollutants in untreated and undiluted highway runoff prior to any treatment and dilution in a water body.  Step 2: In-river impacts. This predicts concentrations of pollutants after mixing within the receiving water body. At this stage, the ability of the receiving watercourse to disperse sediments is considered and, if sediment is predicted to accumulate, the potential extent of sediment coverage (i.e. the deposition index, DI) is also considered. Step 2 also incorporates two 'tiers' of assessment for sediment accumulation, based on different levels of input parameters. If one or more risks are defined as unacceptable at Tier 1, i.e. ‘fail’, then a more detailed Tier 2 assessment is undertaken, requiring values for further parameters relating to the physical dimensions of the receiving watercourse.  Step 3: In-river impacts with mitigation. Steps 1 and 2 assume that the road drainage system incorporates no mitigation measures to reduce the risk. Step 3 includes mitigation in the form of Sustainable Drainage Systems (SuDS), taking into account the risk reduction associated with any existing measures or any proposed new measures.

Cumulative assessment within HEWRAT 2.2.2 The cumulative impacts of the scheme were calculated following DMRB LA 113. The combined effect of two outfalls into the same watercourse within the same reach (distance between two outfalls into the same watercourse) are assessed by combining the contributing impermeable areas to the affected drainage basins. 2.2.3 For solutes, cumulative effects have been considered where proposed outfalls are within 1km of each other (stream length) and discharge into the same

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000006 | C01, A3 | 11/03/21 APPENDIX PAGE i Environmental Statement | HE551505 Highways England

watercourse. For sediment, cumulative impacts have been considered where proposed outfalls are less than 100m apart. 2.2.4 Outfalls from basins 6, 7, 8 and 9 are within 1km of stream length and are therefore combined for cumulative assessment of solutes.

Environmental quality assessments within HEWRAT 2.2.5 A long-term impact assessment of surface water runoff from the highway has been undertaken by comparing the annual average concentrations of copper and zinc predicted in the HEWRAT results with the Environmental Quality Standards (EQSs) stated in the WFD (Standards and Classifications) Directions 2015. 2.2.6 The study area for the HEWRAT assessment encompasses all the watercourses that would receive road runoff from the proposed development, as outlined in ES Chapter 13 Road drainage and water environment (Document Reference 6.2) and displayed on ES Figure 13.1 Surface water features (Document Reference 6.3).

Input parameters 2.2.7 The parameters, methods of derivation and sources of information used in the assessment are listed in Table 2-1. Table 2-1 Inputs used for the surface water quality assessment

Parameter Information Source(s) Two-way annual Figures provided from the traffic model. The two-way Annual Average Daily average daily Traffic flow (AADT) for the A417 mainline ranges from 50,000-60,000 at the traffic flow (AADT) design year (2039). This falls within the 50,000-100,000 AADT range of the HEWRAT assessment. Climatic Selected within HEWRAT. The scheme is within the ‘warm and wet’ region and conditions with a standard average annual rainfall of 850mm ().

Q95 (the water Catchment descriptors obtained from the FEH Web Service and Q95 flow exceeded subsequently derived using the FEH LowFlows tool, the standard method for 95% of the time) estimating Q95 in the absence of monitoring data. The estimated values have of the receiving been ground-truthed via site walkover. All receiving watercourses are watercourse. headwater streams with low estimated Q95 values, ranging from <0.001 to 0.002 m3/s. Base flow index Obtained from the FEH Web Service for each catchment. This is a measure of (BFI) the proportion of the flow in the watercourse that derives from groundwater. Drainage areas Impermeable area (e.g. highway) and permeable area (e.g. cutting/slope drainage) to each outfall has been calculated from the design models of the scheme. Water hardness Water hardness has been estimated using the Drinking Water Inspectorate Map for England and Wales. All watercourses have been deemed to have a medium water hardness, i.e. 50-200 CaCO3/l. Physical attributes Watercourse dimensions and Manning’s n have been estimated based on the of the receiving ES Appendix 13.10 Water Features Survey (Document Reference 6.4) and site watercourse walkover. Watercourse long slope has been estimated based on available topographic survey.

2.2.8 Table 2-2 lists the receiving watercourse, Q95 and drainage areas for each outfall on the new section of A417 and side roads.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000006 | C01, A3 | 11/03/21 APPENDIX PAGE ii Environmental Statement | HE551505 Highways England

Table 2-2 Input data for HEWRAT assessments

Outfall Receiving watercourse Q95 (m3/s) Impermeable Permeable BFI area (ha) area (ha) 2 Tributary of Normans Brook 0.001 5.38 1.25 0.635 3c Tributary of Normans Brook 0.001 1.97 0.77 0.635 3a Tributary of River Churn 1 0.001 3.77 2.01 0.635 5a, 5b, 5c Tributary of River Churn 1 0.001 2.22 1.48 0.635 6 Tributary of River Churn 2 0.001 2.09 1.17 0.746 7b Tributary of River Churn 2 0.002 2.13 2.17 0.746 8 Tributary of River Churn 2 0.002 0.88 0.27 0.746 9 Tributary of River Churn 2 0.001 1.89 2.01 0.746 10 Tributary of River Frome 1 0.002 2.52 3.26 0.746 11a, 11b, 11c Tributary of River Frome 2 0.002 5.75 7.34 0.746 2.2.9 The proposed discharge locations were screened against the location of protected areas (e.g. Sites of Special Scientific Interest (SSSI), Special Areas of Conservation (SAC)). Outfall locations less than 1km upstream of a protected site require more stringent pollutant thresholds to be applied. Only Outfall 10, which is approximately 300m upslope of Bushley Muzzard SSSI meets this criterion.

2.3 Results – without mitigation 2.3.1 All outfalls failed the Step 1 assessment. 2.3.2 All outfalls failed the Step 2 soluble pollutant assessment, but all pass the sediment assessment. Mitigation (treatment) is therefore required within the drainage design to reduce the soluble pollutant load. The detailed results of the Step 2 assessment are shown in Table 2-3. Table 2-3 Summary of routine runoff assessments

Basin Step 2 HEWRAT result Outfall Copper - Acute Copper - Zinc - Acute Zinc - Sediment EQS EQS 2 Fail Fail Fail Fail Pass at Tier 2

3c Fail Fail Fail Fail Pass at Tier 2 3a Fail Fail Fail Fail Pass at Tier 2 5a, 5b, 5c Combined with Basin 3a for cumulative sediment and soluble pollutant assessment.

6 Fail Fail Fail Fail Pass at Tier 2 7b Pass at Tier 2

8 Pass at Tier 2 Combined with outfall 6 in cumulative assessment for soluble 9 pollutants. Pass at Tier 2

10 Fail Fail Fail Fail Pass at Tier 2

11a, 11b, 11c Fail Fail Fail Fail Pass at Tier 2

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000006 | C01, A3 | 11/03/21 APPENDIX PAGE iii Environmental Statement | HE551505 Highways England

2.4 Mitigation 2.4.1 A sensitivity test was undertaken using the HEWRAT model to identify the percentage mitigation required for each outfall to pass (Table 2-5). Treatment trains have been developed for the drainage systems to each outfall to ensure that the required treatment levels met. 2.4.2 The level of pollutant removal have been determined from the values listed in CG501 Design of highway drainage systems (Table 2-4). Table 2-4 Indicative treatment efficiencies (from CG 501, Table 8.6.4N3)

Name of measure Indicative treatment efficiencies Suspended Solids (% Dissolved Copper (% Dissolved Zinc (% removal) removal) removal) Filter Drains 60 0 45 Ditch 25 15 15 Swale/grassed SWC 80 50 50 Drainage basin (wet) 60 40 30 Infiltration basin (soakaway) 100 100 100

Table 2-5 Summary of proposed pollutant treatment

Basin Percent of Proposed treatment methods Comment Outfall treatment required (soluble) 2 60 Swale, Filter Drain, drainage basin Sufficient pollution removal 3c 35 Swale, Filter Drain, drainage basin, Sufficient pollution removal Ditch 3a 60 Swale, Filter Drain, drainage basin, Sufficient pollution removal Ditch 5a, 5b, Filter Drain, drainage basin, Ditch Sufficient pollution removal 5c 6 45 Filter Drain, drainage basin, Ditch Additional measures required in forebay for copper removal 7b Filter Drain, drainage basin, Ditch Additional measures required in forebay for copper removal 8 Drainage basin, Ditch Additional measures required in forebay for copper and zinc removal 9 Swale, Filter Drain, drainage basin, Sufficient pollution removal Ditch 10 50 Swale, Filter Drain, drainage basin, Sufficient pollution removal Ditch 11a, 40 Swale, Filter Drain, drainage basin, Sufficient pollution removal 11b, 11c Ditch

2.5 Results – with mitigation 2.5.1 All networks on the scheme include a basin along with at least one other measure as a treatment train. Catchments with high “% Treatment Required” and no swale

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000006 | C01, A3 | 11/03/21 APPENDIX PAGE iv Environmental Statement | HE551505 Highways England

/ grassed SWC such as catchments 6, 7b/c and 8 require an additional pollution control measure to meet the required removal percentage. This additional treatment would be in the form of a forebay within the drainage basins to effectively remove pollutants. The forebay design would be developed at the detailed design stage. 2.5.2 Once this additional treatment is incorporated into the drainage design, all outfalls pass the assessment of pollution impacts from routine runoff on surface waters. 2.5.3 The exact type and configuration of the drainage basins would depend heavily on the specific ground conditions (suitability for infiltration) at each location and the preferred maintenance regime of the adopting body (HE or GCC). 2.5.4 This surface water quality assessment is based on a precautionary assumption that no infiltration would take place within the drainage systems and at the drainage basins. When the ground investigation is complete, there would be opportunities to introduce infiltration techniques and optimise the drainage basin designs. Infiltration would also significantly improve the pollutant removal performance of the highway drainage systems. 3 Assessment of pollution impacts from routine runoff on groundwater

3.1 Introduction 3.1.1 Given the relatively low flows of the watercourses receiving flow from the road drainage and the suitability of ground conditions for infiltration across much of the scheme, it is prudent to carry out an assessment of pollution impacts from routine runoff to groundwater. This assessment has also been undertaken using HEWRAT, following the guidance in DMRB LA 113. 3.1.2 This risk assessment procedure is based on the study of the source-pathway- receptor (S-P-R) pollutant linkage principal, whereby the:  source comprises the road drainage water with any pollutants contained therein, as it enters any unlined ditch, watercourse or soakaway discharge system, that has the potential to transmit water through the ground to groundwater  pathway represents the processes, which may modify the pollutants during transmission through the discharge system and soil and subsoil until the actual ‘point of entry’ to groundwater (this includes the unsaturated zone)  receptor is groundwater 3.1.3 For there to be a risk of impact to the receiving environment, all elements of the S-P-R model must be present to for there to be a pollutant linkage.

3.2 Methodology 3.2.1 The drainage solution for the scheme includes drainage basins, all of which discharge to surface watercourses but may also infiltrate to groundwater pending completion of the ground investigation. The drainage basins are situated at various points along the scheme and for the purposes of the assessment, are assumed to act as soakaways. 3.2.2 The assessment determines an overall risk score by incorporating the key factors affecting the level of risk posed by the source of pollutants, the persistence and movement of pollutants within the pathway to groundwater and linkages between

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000006 | C01, A3 | 11/03/21 APPENDIX PAGE v Environmental Statement | HE551505 Highways England

them. In this way, the matrix provides a means of ranking specific road drainage discharge sites in terms of their potential risks to groundwater.

3.3 Results 3.3.1 Table 3-6 summarises the results of the groundwater assessment. The risk scores range from 170 to 220, within the 150 – 250 suggested action class range, which indicates there is a medium risk of impact. Table 3-6 Overall risk scores

Weighting Property or Site data Risk score Component factor parameter score 10 Traffic flow >50,000 to <100,000 Medium 20 10 Rainfall depth (annual 850mm (Bristol) Medium 20 averages) SOURCE 10 Drainage area ratio <50 Low 10

15 Infiltration method Region Medium 30

20 Unsaturated Zone Ranges from <5m to >15m. Low, medium 20, Based on groundwater or high 40, monitoring data. 60 20 Flow Type Intergranular, mixed and Low, medium 20, fracture flow present at or high 40, different locations along 60 scheme. 5 Unsaturated zone Ranges from <1% to >15% Low, medium 5, PATHWAY clay content along scheme. or high 10, 15 5 Organic carbon Typically <1% but Medium or 10, occasionally 1-15% high 15 5 Unsaturated zone soil <5 or 5-8 Medium or 10, pH high 15

Overall Risk Score Medium risk Min = 170 Max = 220

3.4 Mitigation 3.4.1 DMRB LA 113 states that where a medium risk of impact is indicated, a detailed assessment is required to be undertaken by a competent expert. 3.4.2 The detailed assessment would be undertaken at the detailed design stage. This would be supported by further site-specific tests, such as infiltration rate through the ground. Ground conditions specific to the drainage basin locations would also be ascertained through further ground investigation. Baseline groundwater level and quality monitoring would be ongoing and would also inform the assessments. 3.4.3 The specific mitigation measures required in the design of drainage systems and drainage basins would therefore be refined at detailed design. This could include measures to separate carriageway drainage systems from groundwater, the lining

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000006 | C01, A3 | 11/03/21 APPENDIX PAGE vi Environmental Statement | HE551505 Highways England

of drainage basins, and limitations on the disposal of surface water though infiltration. 3.4.4 Where required, the detailed assessment would incorporate mitigation measures to reduce the risk to a suitable level. 3.4.5 Details of mitigation are reported in ES Chapter 13 Road drainage and water environment (Document Reference 6.2) and Annex G Ground and surface water management plan of ES Appendix 2.1 Environmental Management Plan (EMP) (Document Reference 6.4).

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000006 | C01, A3 | 11/03/21 APPENDIX PAGE vii A417 Missing Link TR010056

6.4 Environmental Statement Appendix 13.5 Hydromorphology Assessment

Planning Act 2008

APFP Regulation 5(2)(a) Infrastructure Planning (Applications: Prescribed Forms and Procedure) Regulations 2009

Volume 6

May 2021 A417 Missing Link | HE551505 Highways England

Infrastructure Planning

Planning Act 2008

The Infrastructure Planning (Applications: Prescribed Forms and Procedure) Regulations 2009

Regulation 5(h)

A417 Missing Link

Development Consent Order 202[x]

6.4 Environmental Statement Appendix 13.5 Hydromorphology Assessment

Regulation Number: 5(2)(a) Planning Inspectorate TR010056 Scheme Reference Application Document Reference 6.4 Author: A417 Missing Link

Version Date Status of Version C01 May 2021 Application Submission A417 Missing Link | HE551505 Highways England

Table of Contents Pages 1 Introduction i 1.1 Purpose i 2 Methodology i 2.1 Study area i 2.2 Desk study i 2.3 Site survey ii 2.4 Impact Assessment ii 3 Baseline hydromorphology iii 3.1 Introduction iii 3.2 Tributary of Norman’s Brook iii 3.3 Tributary of River Churn 1 vi 3.4 Tributary of River Churn 2 viii 3.5 River Frome ix 4 Impact assessment x 4.1 Construction activities x 5 Summary xiii References xv

Table of Photographs Photograph 3-1 Representative photo of characteristics of tributary of Norman’s Brook iv Photograph 3-2 Tufa cascades along the tributary of Norman’s Brook v Photograph 3-3 Existing culvert entrance under A417 - tributary of Norman’s Brook vi Photograph 3-4 Representative photo of characteristics of tributary of River Churn 1 vii Photograph 3-5 Representative photo of characteristics of tributary of River Churn 2 viii Photograph 3-6 Representative photo of characteristics of tributary of River Frome at Nettleton ix A417 Missing Link | HE551505 Highways England

1 Introduction

1.1 Purpose 1.1.1 This document describes the hydromorphological baseline for the proposed scheme and outlines the likely potential impacts upon hydromorphology. This informs ES Chapter 13 Road drainage and water environment (Document Reference 6.2) and ES Appendix 13.2 WFD compliance (Document Reference 6.4). 2 Methodology

2.1 Study area 2.1.1 For direct effects on surface waters, the study area includes the geographical extent of the full scope of the works and all surface water features within 1km, where features have hydrological connectivity to the scheme. 2.1.2 For groundwater, the study area includes the geographical extent of the full scope of the works and groundwater features within the schemes study area (defined in ES Chapter 13 Road drainage and the water environment (Document Reference 6.2). 2.1.3 The following surface watercourses, shown on ES Figure 13.1 (Document Reference 6.3), have been deemed to be within the study area of the assessment:  Norman’s Brook– source to confluence Hatherley Brook (No. GB109054032780) waterbody. A tracer test was undertaken in March 2019 finding that the watercourse flowing alongside the A417 at Crickley Hill was a tributary of Norman’s Brook, rather than Horsbere Brook;  River Churn – source to Perrots Brook (No. GB106039029810) waterbody (Unnamed tributaries of River Churn 1 and 2); and  River Frome – source to Ebley Mill (No. GB109054032470) waterbody.

2.2 Desk study 2.2.1 A desk study to collate and review available hydromorphology information has been conducted for watercourses that may be impacted by the scheme. 2.2.2 The desktop assessment has collated and reviewed the status and objectives information for hydromorphological quality elements of the relevant Water Framework Directive (WFD) waterbodies based on Environment Agency (EA) data (2016 Cycle 2 Waterbody Status Classification data). 2.2.3 The following sources have also been used to further establish the existing conditions of the hydromorphology of watercourses within the study area:  EA Catchment Data Explorer, including relevant information from the Severn and Thames River Basin Management Plans 20151  Ordnance Survey (OS) mapping (including topography)  Preliminary Groundwater Report 20192  ES Appendix 13.7 Hydrogeological Impact Assessment (Document Reference 6.4)  ES Appendix 13.11 Water Features Survey (Document Reference 6.4)

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000008 | C01, A3 | 11/03/21 APPENDIX PAGE i A417 Missing Link | HE551505 Highways England

 ES Appendix 13.12 Water Environment Monitoring Data (Document Reference 6.4)

2.3 Site survey 2.3.1 A walkover survey of the watercourses potentially impacted by the scheme was undertaken by a geomorphologist on the 28 and 29 October 2019. The survey collected information on the form of the channels, the flow types and the characteristics of the riparian zone for up to 1km from the scheme boundary. The surveys were undertaken following a weekend of heavy rainfall and flows were high. 2.3.2 Spot flow gauging was undertaken at 47 locations during four monitoring periods between April 2018 and March 2019. This has provided an initial characterisation of the range of flows within the watercourses of interest. This data is presented in ES Appendix 13.11 Water Features Survey (Document Reference 6.4). 2.3.3 Additional flow gauging was undertaken at six surface water and seven spring locations between July 2020 and December 2020. For surface waters, these were a mixture of continuous (gauged) sites and spot (monthly) measurements. All spring locations were spot measurements. Details on this are presented in ES Chapter 13 Road drainage and the water environment (Document Reference 6.2) and results presented in ES Appendix 13.12 Water Environment Monitoring Data (Document Reference 6.4).

2.4 Impact Assessment 2.4.1 Potential impacts upon hydromorphology have been assessed at a catchment level. The assessment has considered potential impacts upon the following:  flow processes  sediment movement  boundary conditions (channel bed and banks)  riparian zones  floodplains  downstream and catchment-channel connectivity  the general form and function of the channel and near-channel zones  the setting of the watercourse within the wider catchment 2.4.2 Where significant potential impacts have been identified, mitigation measures are proposed. Mitigation takes the form of requirements in the ES Appendix 2.1 Environmental Management Plan (EMP) (Document Reference 6.4) to minimise the effect of the construction activities or requirements to incorporate into the detailed design of the scheme.

Construction impacts 2.4.3 LA 113 Road drainage and the water environment (LA 113) recommends that construction impacts are considered using the source – pathway – receptor approach and defers specific guidance of highway construction impacts to CIRIA 648 Control of Water Pollution from Linear Construction Projects. 2.4.4 The potential impacts of construction on hydromorphology have been assessed based on the planned construction methods and sequencing. Where construction methods are not available, standard construction practices have been assumed.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000008 | C01, A3 | 11/03/21 APPENDIX PAGE ii A417 Missing Link | HE551505 Highways England

2.4.5 Where measures to reduce construction impacts are considered standard practice they have been included in ES Appendix 2.1 EMP (Document Reference 6.4). It has been assumed that they will be carried out in respect of the impact assessment presented in this chapter. Measures beyond standard practice are typically considered to be mitigation and have been identified as such in this assessment.

Operational impacts 2.4.6 A qualitative assessment of possible impacts on the hydromorphology of watercourses has been undertaken based on a geomorphologist’s understanding of the potential for impacts to the flow dynamics and sediment transport processes and the subsequent effects that this might have on the ecological potential of the water feature (where relevant). 2.4.7 The assessment has been made using professional judgement and experience and is focussed on locations where the route physically interacts with watercourses (for example proposed culverts or realignments) or where discharges from the road drainage system may occur. 3 Baseline hydromorphology

3.1 Introduction 3.1.1 The Cotswold escarpment forms a surface water divide between the River Severn catchment and the River Thames catchment (to the east and south-east of the divide). To the west of the divide, the land drains to the River Severn and its tributaries, including Norman’s Brook, Horsbere Brook and the River Frome. To the east and south-east, the land drains to the River Churn, a tributary of the Thames. 3.1.2 Norman’s Brook, the River Frome and the River Churn are classed by the EA as ordinary watercourses within the study area.

3.2 Tributary of Norman’s Brook 3.2.1 The tributary of Norman’s Brook flows westwards along the southern edge of the existing A417 embankment at Crickley Hill. The watercourse emerges from a pipe to the north of Crickley Hill Tractors, at approximately National Grid Reference (NGR) SO 93057 15871, and flows down the relatively steep, wooded valley. 3.2.2 The watercourse is fed by several springs that emerge at various elevations from the complex geology in this area. Many of these features are ephemeral. 3.2.3 Spot flow gauging undertaken between April 2018 and March 2019 along the watercourse recorded flows up to 0.013m3/s, with evidence of flow losses (assumed to the underlying aquifer), principally around Ch 0+900m (ES Appendix 13.11 Water Features Survey (Document Reference 6.4). 3.2.4 Spot gauging has also been undertaken between July – December 2020, with flows ranging from 0.001 to 0.062m3/s (Location SW2 in ES Appendix 13.12 Water Environment Monitoring Data (Document Reference 6.4)). 3.2.5 The watercourse is approximately 1m wide and is characterised by run and cascade flow types. The dominant bed material is fine gravel, with coarse gravel, cobbles, sand and clay also present. The banks are densely wooded and composed of cohesive material with limited evidence of erosion, principally by geotechnical failure.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000008 | C01, A3 | 11/03/21 APPENDIX PAGE iii A417 Missing Link | HE551505 Highways England

3.2.6 A representative photo of the watercourse is shown in Photograph 3-1.

Photograph 3-1 Representative photo of characteristics of tributary of Norman’s Brook 3.2.7 The watercourse enters a buried culvert via a 2.5m high concrete weir at Ch 1+200m, before re-emerging 50m downstream. 3.2.8 Tufa deposits have been identified in this section of the tributary of Norman’s Brook in ES Appendix 8.24 Assessment of tufaceous material (Document Reference 6.4). Tufa is formed when carbonate is precipitated out of alkaline water. Carbonate deposits are apparent over existing concrete weir structures at this location (Photograph 3-2), where precipitation is induced by the increased air- water interaction created by the turbulent flow. There are seven cascades in total, each around 2.5m wide.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000008 | C01, A3 | 11/03/21 APPENDIX PAGE iv A417 Missing Link | HE551505 Highways England

Photograph 3-2 Tufa cascades along the tributary of Norman’s Brook 3.2.9 Further information on the hydrogeological setting for the carbonate deposits is presented in ES Appendix 13.7 Hydrogeological Impact Assessment (Document 6.4). 3.2.10 The watercourse is culverted from Ch 0+700m to 0+800m. 3.2.11 The watercourse enters existing Crickley Hill stream culvert beneath the A417 at Ch 0+600m (Photograph 3-3). Due to uncertainties about the flow direction of the culvert, a tracer test has been carried out to establish where the watercourse emerges3. This has found that it emerges along Bentham Lane (NGR: SO 91337 16344) and flows north-westwards into Norman’s Brook, rather than Horsbere Brook as shown on WFD mapping.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000008 | C01, A3 | 11/03/21 APPENDIX PAGE v A417 Missing Link | HE551505 Highways England

Photograph 3-3 Existing culvert entrance under A417 - tributary of Norman’s Brook 3.2.12 The watercourse is therefore assumed to be part of the Norman’s Brook - source to confluence Hatherley Brook (GB109054032780) waterbody. The waterbody has an overall status of ‘Moderate’ and a hydromorphological supporting elements status of ‘Supports Good’.

3.3 Tributary of River Churn 1 3.3.1 The unnamed tributary of the River Churn 1 flows eastwards away from the scheme. The watercourse is first recorded where it crosses beneath the A436 to the south-east of Ullenwood Manor Golf Course. 3.3.2 The road drainage discharged into this catchment would only flow directly into the watercourse during periods when the catchment was saturated and overland flow processes were active. 3.3.3 The watercourse has been straightened and flows through rough pasture and woodland, with some evidence of poaching (Photograph 3-4). The watercourse if approximately 2m wide with flow types of runs and glides and a gravel bed.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000008 | C01, A3 | 11/03/21 APPENDIX PAGE vi A417 Missing Link | HE551505 Highways England

Photograph 3-4 Representative photo of characteristics of tributary of River Churn 1 3.3.4 Spot flow gauging of the watercourse was undertaken four times from April 2018 to March 2019 at NGR SO 94711 16460. Flows were too low to be recorded in April 2018, July 2018 and February 2018 but were recorded as 0.04m3/s in March 20193. Spot gauging was also undertaken between August – December 2020, with flows ranging from 0.005 to 0.054m3/s (Location SW5 in ES Appendix 13.12 Water Environment Monitoring Data (Document Reference 6.4)). 3.3.5 The watercourse is within the River Churn - source to Perrots Brook (GB106039029810) waterbody. It has an overall status of ‘Moderate’ and a hydromorphological supporting elements status of ‘Supports Good’.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000008 | C01, A3 | 11/03/21 APPENDIX PAGE vii A417 Missing Link | HE551505 Highways England

3.4 Tributary of River Churn 2 3.4.1 The unnamed tributary of the River Churn 2 is a dry valley feature which is crossed by the scheme at the head of the valley between Ch 3+100m and 3+300m. A watercourse is not present in the valley bottom until approximately 1.2km downstream of the scheme at NGR SO 95380 15473. 3.4.2 The dry valley may experience episodical surface water flows during periods of high groundwater levels but is otherwise a relict landscape feature formed by past periglacial processes. 3.4.3 The watercourse is ponded and flows eastwards through along a dense wooded field boundary towards the River Churn (Photograph 3-5).

Photograph 3-5 Representative photo of characteristics of tributary of River Churn 2 3.4.4 Spot flow gauging of the watercourse was undertaken four times from April 2018 to March 2019 at NGR SO964155. Flows ranged from dry (July 2018) to 0.07m3/s (April 2018)3. Spot gauging was also undertaken between October – December 2020, with flows ranging from 0.002 to 0.018m3/s (Location SW6 in ES Appendix 13.12 Water Environment Monitoring Data (Document Reference 6.4)). 3.4.5 The watercourse is within the River Churn - source to Perrots Brook (GB106039029810) waterbody. It has an overall status of ‘Moderate’ and a hydromorphological supporting elements status of ‘Supports Good’.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000008 | C01, A3 | 11/03/21 APPENDIX PAGE viii A417 Missing Link | HE551505 Highways England

3.5 River Frome 3.5.1 The River Frome and its unnamed tributaries emerge to the south of the eastern end of the scheme, near Nettleton. The catchment is fed by a series of springs that emerge at the boundary of the Great Oolite limestones over Fuller’s Earth mudstone. 3.5.2 The watercourses in this catchment are not directly modified by the scheme but would receive discharges from the road drainage network. 3.5.3 Spot gauging has been undertaken between July – December 2020, with flows ranging from 0.001 to 0.166m3/s (Locations SW3 & SW4 in ES Appendix 13.12 Water Environment Monitoring Data (Document Reference 6.4)). 3.5.4 The tributary which flows southwards from Nettleton is within a piped culvert from the existing A417 until it emerges, as shown on OS mapping. The watercourse has been overdeepened and has approximately 1.5m high banks (Photograph 3-6).

Photograph 3-6 Representative photo of characteristics of tributary of River Frome at Nettleton 3.5.5 The Nettleton tributary joins the main arm of the River Frome at the southern end of Bushley Muzzard SSSI. A 1m high concrete weir forms a densely vegetated ponded area at this location. 3.5.6 Downstream of this the watercourse flows through woodland and has a relatively natural form, made up of runs with small cascade sections, typically formed by

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000008 | C01, A3 | 11/03/21 APPENDIX PAGE ix A417 Missing Link | HE551505 Highways England

outcrops of clay hardpan material. The riverbed level appears to be controlled by the erosion resistant clay with sections dominated by fine gravel. 3.5.7 Another small tributary enters in this section which would receive flow from the road drainage system. 3.5.8 Approximately 700m downstream of the scheme area, the watercourse has been impounded to form a series of ponds through Brimpsfield Park. The impounding structures are large concrete weirs which appear to restrict coarse sediment transport downstream. 4 Impact assessment

4.1 Construction activities 4.1.1 The construction of the scheme requires works in proximity of the watercourses in the study area. These works include:  Installation of culverts to maintain surface water flow routes.  Installation of outfalls from the road drainage system.  General earthworks required to construct the scheme, including the widening of the highway and inclusion of earth bunding from Ch 0+500m to Ch 1+700m, which includes the realignment and partial loss of the tributary of Normans Brook. 4.1.2 The full assessment of likely significant effects is report in ES Chapter 13 Road drainage and the water environment (Document Reference 6.2). The assessment below defines the magnitude of impact for each construction activity. 4.1.3 There is a risk of sediment runoff entering any of the watercourses in the study area during construction, with potential long-term effects upon channel morphology and substrate. This risk would be managed through Annex G Ground and surface water management plan (GSWMP) of ES Appendix 2.1 EMP (Document Reference 6.4). 4.1.4 Following the implementation of the measures outlined in Annex G GSWMP of ES Appendix 2.1 EMP (Document Reference 6.4), the magnitude of impact upon hydromorphology from sediment runoff is negligible.

Culverts 4.1.5 New culverts are proposed within the scheme to enable the highway to cross existing watercourses (Table 4-1). None of these watercourses are designated as main rivers. In addition to these culverts, there will be other smaller culverts conveying flows from the cut-off ditches under tracks, public rights of way and private accesses. 4.1.6 The culverts at Shab Hill and Stockwell are to provide an overland flow pathway beneath the scheme along dry valleys. The potential for impact to hydromorphology is therefore limited and with implementation of the culvert design principles in DMRB CD 5294, the magnitude of impact upon hydromorphology is negligible.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000008 | C01, A3 | 11/03/21 APPENDIX PAGE x A417 Missing Link | HE551505 Highways England

Table 4-1 New culverts proposed as part of the scheme

Chainage (m) Embedded design/ Watercourse Size Potential effect / Name mitigation 0+530 Tributary of 0.6m diameter Local shading of Designed to DMRB CD Culvert near Norman’s Brook (as existing). watercourse. 529 Design of outfall and Crickley Hill 190m length Local conversion of culvert details. Farm (Fly Up (~55m existing) natural channel to Designed to CIRIA C786 Bike Park) – culvert. Culvert, screen and replacement Scour at inlet/outlet if operation manual of existing poorly designed. guidance. culvert Barrier to sediment 1+450 Tributary of 1.2m diameter. transport. Grove Farm Norman’s Brook 320m length. Culvert 3+200 Dry valley to 1.2m to account Scour at inlet/outlet if Shab Hill Tributary of River for dry valley. poorly designed. Culvert Churn 2 4+775 Dry valley to 1.2m to account Stockwell Tributary of River for dry valley. Culvert Churn 2

Outfalls 4.1.7 New outfalls would be installed or existing outfalls re-used to discharge treated carriageway runoff and cutting drainage to surface watercourses, where infiltration is not possible. Three outfalls would discharge to the tributary of Normans Brook, two to tributary of River Churn 1, five to tributary of River Churn 2 and two to the River Frome. The scheme drainage networks have been designed to maintain flows within their existing catchments where practicable to maintain the current surface water hydrology. 4.1.8 New outfall structures within a watercourse can alter local channel cross section and induce local bank or bed erosion, as well as reduce the available natural bank habitat area. 4.1.9 The potential for outfalls to impact upon hydromorphology is assessed in Table 4-2. This has established that the outfalls are either replacements of existing structures or are located on dry valleys at the head of watercourses and therefore, following the implementation of the standards in DMRB CD 529 Design of outfall and culvert details, the magnitude of impact upon hydromorphology is negligible.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000008 | C01, A3 | 11/03/21 APPENDIX PAGE xi A417 Missing Link | HE551505 Highways England

Table 4-2 New outfalls proposed as part of the scheme

Embedded design/ Outfall Number Watercourse Potential effect mitigation 2 Trib of Norman’s Brook 3c 3a Dry valley leading to 5a, 5b, 5c (combined) Trib of River Churn 1 New outfall – potential for 6 hydromorphological Designed to DMRB CD 7b Dry valley leading to change 529 standards 8 Trib of River Churn 2 9 Dry valley leading to 10 Trib of River Frome 1 Dry valley leading to Existing outfall – limited 11a, 11b, 11c Trib of River From 2 potential for change

Realignment of tributary of Normans Brook 4.1.10 The widening of the A417 and the provision of earth bunding and planting along the southern side of the alignment (to screen the road from the surrounding area) results in the need to realign the tributary of Norman’s Brook. The watercourse would be re-routed between Ch 0+500m and Ch 1+700m. 4.1.11 The scheme involves the:  Realignment of approximately 850m of the watercourse to accommodate the wider road and subsequent larger embankment.  Culverting of the top 320m of the watercourse to accommodate highways drainage basin 3c and alleviate ground stability concerns (Grove Farm Culvert in Table 4-1).  Replacement and lengthening of the existing Crickley Hill stream culvert beneath the A417 (culvert near Crickley Hill Farm (Fly Up Bike Park) in Table 4-1). 4.1.12 Following construction, the watercourse will flow along a new alignment around the southern edge of the earth bunding. 4.1.13 The temporary loss of approximately 1.1km of watercourse would impact upon hydromorphology. However, this impact would be localised to the watercourse upstream of the existing A417 culvert. 4.1.14 Mitigation of this effect is unlikely to be feasible given the constraints on the construction area. Opportunities for enhancement of the realigned channel will be sought to offset the impact and provide net benefit. 4.1.15 As the widened road and earth bunding would take up a greater proportion of the valley, the bed of the realigned watercourse would be perched above the existing riverbed level. ES Appendix 13.10 Drainage Report (Document Reference 6.4) describes this in further detail. 4.1.16 The springs that enter the existing watercourse around Ch 1+000 are below the proposed elevation of the realigned watercourse and would no longer augment flow in the tributary of Norman’s Brook at this location. The embankment drainage

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000008 | C01, A3 | 11/03/21 APPENDIX PAGE xii A417 Missing Link | HE551505 Highways England

design would allow this water to move through the earthworks and likely enter the watercourse at a similar elevation to present. 4.1.17 The spring supplying the head of the tributary of Norman’s Brook at Ch 1+600 would be retained, along with supply from the road drainage system (Catchment 3c), which would receive water from a larger catchment area than at present as the top section of the tributary of Norman’s Brook, which is currently drained towards the River Churn, would be re-directed to its natural catchment. 4.1.18 The water balance of the tributary of Norman’s Brook is therefore anticipated to result in little change in flow in the upper portion of the watercourse, a potential reduction in typical flow downstream of the current spring at Ch 1+000 and no change in flow downstream of the Crickley Hill stream culvert. Further details are provided in ES Appendix 13.10 Drainage Report (Document Reference 6.4). 4.1.19 The realignment of the watercourse and raising of the bed level would impact upon flows within the watercourse by limiting the ability of the realigned watercourse to receive water from existing springs due to its raised bed level.

Essential mitigation 4.1.20 The following design principles are incorporated in Annex G Ground and Surface Water Management Plan of ES Appendix 2.1 EMP (Document Reference 6.4) and reported in ES Chapter 13 Road drainage and water environment. These would be implemented during the detailed design of the scheme to mitigate the effects of the realignment upon hydromorphology:  The detailed design of the realigned watercourse would provide naturalistic features of an equivalent or greater value to that of the existing watercourse. The scheme would aim to replicate the character and geomorphology of a typical upland stream, and there would be space within the 5m wide platform to accommodate features such as step pools, cascades, informal steps and irregular meanders.  The realigned stream would minimise the introduction of new culverted sections, wherever possible.  The flow regime of the realigned watercourse would be as similar as the existing flow regime as practicable.  The detailed design should be overseen by an experienced fluvial geomorphologist. 4.1.21 Following the implementation of these mitigation measures, the magnitude of impact upon hydromorphology is considered to be negligible. 5 Summary 5.1.1 The assessment has documented the baseline hydromorphology of watercourses within the study area. 5.1.2 Potential effects upon hydromorphology have been identified and assessed. Mitigation measures have been proposed where a potential effect has been identified and an assessment of residual risk undertaken. 5.1.3 Potential adverse effects upon hydromorphology from sediment runoff during construction would be mitigated by the measures included in ES Appendix 2.1 EMP (Document Reference 6.4). 5.1.4 There would be an adverse effect upon hydromorphology as a result of the temporary loss of 1.1km of the tributary of Normans Brook. This impact would be

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000008 | C01, A3 | 11/03/21 APPENDIX PAGE xiii A417 Missing Link | HE551505 Highways England

present during the construction period and would be localised to the section of watercourse from the spring at the head of the watercourse to the Crickley Hill stream culvert beneath the A417 to the (a distance of 1.1km). 5.1.5 Mitigation of this effect is unlikely to be feasible given the constraints on the construction area. Opportunities for enhancement of the realigned channel would be explored at detailed design to offset the impact and provide net benefit. 5.1.6 Potential adverse effects upon hydromorphology from new culverts and outfalls would be suitably mitigated by following the guidance in DMRB CD 529 Design of outfall and culvert details4 during detailed design. 5.1.7 The potential for adverse effect upon the hydromorphology of the tributary of Normans Brook as a result of the loss of up to 320m of open watercourse and the realignment of a further 850m of watercourse would be mitigated. Following the implementation of mitigation measures, the magnitude of impact upon hydromorphology is negligible. 5.1.8 The full assessment of likely significant effects is report in ES Chapter 13 Road drainage and the water environment (Document Reference 6.2).

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000008 | C01, A3 | 11/03/21 APPENDIX PAGE xiv A417 Missing Link | HE551505 Highways England

References

1 Environment Agency (2020). Catchment Data Explorer [Online]. Available at: http://environment.data.gov.uk/catchment-planning/ (Accessed 15/01/2021). 2 Mott MacDonald Sweco JV (2019). Preliminary Groundwater Report, Doc No. HE551505-MMSJV-HGT- 000-RP-CE-00004 3 Mott MacDonald Sweco JV (2019). A417 “Missing Link” Road Scheme, A417 Tracer Test 4 Highways England (2020). Design Manual for Roads and Bridges, CD 529, Design of outfall and culvert details (Rev 1).

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000008 | C01, A3 | 11/03/21 APPENDIX PAGE xv A417 Missing Link TR010056

6.4 Environmental Statement Appendix 13.6 Spillage Risk Assessment

Planning Act 2008

APFP Regulation 5(2)(a) Infrastructure Planning (Applications: Prescribed Forms and Procedure) Regulations 2009

Volume 6

May 2021 A417 Missing Link | HE551505 Highways England

Infrastructure Planning

Planning Act 2008

The Infrastructure Planning (Applications: Prescribed Forms and Procedure) Regulations 2009

Regulation 5(h)

A417 Missing Link

Development Consent Order 202[x]

6.4 Environmental Statement Appendix 13.6 Spillage Risk Assessment

Regulation Number: 5(2)(a) Planning Inspectorate TR010056 Scheme Reference Application Document Reference 6.4 Author: A417 Missing Link

Version Date Status of Version C01 May 2021 Application Submission A417 Missing Link | HE551505 Highways England

Table of Contents Pages 1 Introduction i 1.1 Purpose of this document i 2 Appendix D assessment of accidental spillage i 2.1 Method i 2.2 Results i

Table of Tables Table 2-1 Spillage risk assessment results ii Table 2-2 Spillage risk assessment summary values ii A417 Missing Link | HE551505 Highways England

1 Introduction

1.1 Purpose of this document 1.1.1 This document is to report on the risk (likelihood and consequence) to the water environment from accidents and spillages on the highway, and to determine the acceptability of this. 2 Appendix D assessment of accidental spillage

2.1 Method 2.1.1 Assessment of accidental spillages of polluting substances from roads has been carried out using Appendix D as prescribed in the Design Manual for Roads and Bridges (DMRB) LA 113 Road drainage and the water environment (LA 113) to ensure provision of appropriate drainage design measures where the risk of a serious pollution incident is more frequent than the 1% annual exceedance probability (AEP) (or more frequent than 1 in 100-year return period). 2.1.2 Assessments have been undertaken for each road drainage area (sub-catchment scale). 2.1.3 The results of the assessment are reported as ‘pass’ or ‘fail’. The risk of an acute pollution incident due to accidental spillage or vehicle fire is considered proportionate to the risk of a heavy goods vehicle (HGV) road traffic collision. Thus, the percentage of HGV’s on a given road is the main parameter used in assessment of the risk of serious pollution accidents. 2.1.4 Other parameters considered include the type and length of road, two-way annual average daily traffic (AADT) flow and emergency services response time depending on whether a site is in an urban, rural or remote setting. If the accidental spillage is less than or equal to 1% AEP (or 0.5% AEP for sensitive watercourses), the risk is considered acceptable. 2.1.5 Vehicle numbers from the design year 2039 AADT flows have been used to account for future growth.

2.2 Results 2.2.1 Detailed results of the spillage risk assessment the summary values are presented in Table 2-1 and Table 2-2, respectively. The accidental spillage risk assessment results show that, without consideration of the drainage scheme, there would be no discharge with a serious spillage risk more frequent than the 1% and 0.5% AEP (1 in 100-year and 1 in 200-year return period) thresholds. 2.2.2 The level of risk to the water environment is therefore acceptable in accordance with LA 113.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000007 | C01, A3 | 11/03/21 APPENDIX PAGE i A417 Missing Link | HE551505 Highways England

Table 2-1 Spillage risk assessment results

Probability Spillage Probability Road factor of Catchment Road 2-way factor of pollution Length Junction type %HGV accidental Risk? ID reference AADT (ppsl incident (m) spillage (%)) (Pinc (%)) (Pspl (%))

2 A417 1700 No junction 57206 7.94% 0.29 0.00082 0.00037 No

3c A417 400 No junction 57206 7.94% 0.29 0.00019 0.00009 No

3a A417 950 No junction 57206 7.94% 0.29 0.00046 0.00021 No

A436 (north) 5a, 5b, 5c & New AB 880 Roundabout 12162 4.93% 3.09 0.00060 0.00027 No Roundabout

6,8 A417 450 Slip road 57206 7.94 0.83 0.00062 0.00028 No

A436 7b 960 Roundabout 12162 4.93% 3.09 0.00065 0.00029 No Junction

9 A417 500 No junction 52626 6.87% 0.29 0.00019 0.00009 No

0.00011 – 10 A417 610 No junction 52626 6.87% 0.29 0.00023 protected No area 11a, 11b, A417 1150 Roundabout (precautionary as on side road) 52626 6.96% 3.09 0.00756 0.00340 No 11c

Table 2-2 Spillage risk assessment summary values

Acceptable Do individual outfall risks need to Highest individual risk Can the highest individual risk be risk (normally 1%, or 1-in-100 year) be identified? reduced? 1.00% No 0.00340 No

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000007 | C01, A3 | 11/03/21 APPENDIX PAGE ii A417 Missing Link TR010056

6.4 Environmental Statement Appendix 13.7 Hydrogeological Impact Assessment

Planning Act 2008

APFP Regulation 5(2)(a) Infrastructure Planning (Applications: Prescribed Forms and Procedure) Regulations 2009

Volume 6

May 2021 A417 Missing Link | HE551505 Highways England

Infrastructure Planning

Planning Act 2008

The Infrastructure Planning (Applications: Prescribed Forms and Procedure) Regulations 2009

Regulation 5(h)

A417 Missing Link

Development Consent Order 202[x]

6.4 Environmental Statement Appendix 13.7 Hydrogeological Impact Assessment

Regulation Number: 5(2)(a) Planning Inspectorate TR010056 Scheme Reference Application Document Reference 6.4 Author: A417 Missing Link

Version Date Status of Version

C01 May 2021 Application Submission A417 Missing Link | HE551505 Highways England

Table of Contents

Pages

1 Introduction i 2 Methodology i 2.1 Overview i 2.2 Ground investigations i 2.3 Baseline conditions scope ii 2.4 Designations and directives ii 3 Baseline iv 3.1 Regional geology iv 3.2 Regional hydrogeology ix 3.3 Local geology xvi 4 Groundwater monitoring programme xvii 4.1 Monitoring xvii 4.2 Aquifer testing xviii 4.3 Quality assurance xix 5 Groundwater level monitoring results xix 5.1 Superficial Aquifer - Mass movement deposits, Crickley Hill xix 5.2 Great Oolite Group - Limestones xxii 5.3 Great Oolite Group – Fuller’s Earth Formation xxiv 5.4 Inferior Oolite Group xxv 5.5 Lias Group – Bridport Sand Formation xxix 5.6 Lias Group – undifferentiated mudstones xxx 5.7 Hydraulic gradient and groundwater flow xxxi 5.8 Hydraulic relationships between aquifer units xxxii 6 Groundwater quality xxxiii 7 Aquifer testing xxxiii 8 Groundwater conceptual model xxxiv 8.1 Overview xxxiv 8.2 Ch 0+000 to Ch 1+700, Crickley Hill xxxix 8.3 Ch 1+700 to Ch 2+800, Air Balloon xl 8.4 Ch 2+800 to Ch 3+500, Shab Hill junction xli 8.5 Ch 3+500 to Ch 5+760, Shab Hill junction to Cowley junction xlii 8.6 Hydraulic parameters xliii 9 Groundwater related features xliv 9.1 Groundwater aquifers xliv 9.2 Abstractions xliv 9.4 Surface water bodies xlv

A417 Missing Link | HE551505 Highways England

9.5 Springs xlv 9.6 Superficial carbonate precipitates xlvi 9.7 Dry valleys xlvii 10 Potential impacts to groundwater features xlviii 10.1 Overview xlviii 10.2 Methodology xlviii 10.3 Detailed assessment l 10.4 Summary of impacts lv 11 Conclusions lvii Appendix A Standpipe installations lviii Appendix B Groundwater monitoring results lxii Appendix C Water quality results xcii References c

Table of Figures Figure 1 Idealised conceptual model of the hydrogeological processes in the mid- Cotswold area vi Figure 2 Schematic illustration of cambering, valley bulging and landslides (modified from Farrant et al., 2014) ix Figure 3 Conceptual model of redox conditions within the Cotswolds xiii Figure B-1 Mass movement deposits groundwater monitoring – CH0+500 to CH1+000, lower Crickley Hill lxiii Figure B-2 Mass movement deposits groundwater monitoring – CH1+000 to CH1+400 (northern side of A417), mid Crickley Hill lxiv Figure B-3 Mass movement deposits groundwater monitoring – CH1+000 to CH1+400 (northern side of A417), mid Crickley Hill lxv Figure B-4 Mass movement deposits groundwater monitoring – CH1+000 to CH1+400 (southern side of A417), mid Crickley Hill lxvi Figure B-5 Mass movement deposits groundwater monitoring – CH1+000 to CH1+400 (southern side of A417), mid Crickley Hill lxvii Figure B-6 Mass movement deposits groundwater monitoring – CH1+400 to CH1+700 (southern side of A417), upper Crickley Hill lxviii Figure B-7 Mass movement deposits groundwater monitoring - CH1+400 to CH1+700 (northern side of A417) - upper Crickley Hill lxix Figure B-8 Great Oolite limestone groundwater monitoring – CH3+000 to CH3+500, Shab Hill junction lxx Figure B-9 Great Oolite limestone groundwater monitoring – CH3+000 to CH3+500, Shab Hill junction lxxi Figure B-10 Great Oolite limestone groundwater monitoring – CH3+500 to CH5+000, Shab Hill junction to Cowley junction lxxii Figure B-11 Great Oolite limestone groundwater monitoring – Bushley Muzzard SSSI lxxiii Figure B-12 Fuller’s Earth Formation groundwater monitoring, CH3+500 to CH5+000, Shab Hill junction to Cowley junction lxxiv Figure B-13 Fuller’s Earth Formation groundwater monitoring, CH3+500 to CH5+000, Shab Hill junction to Cowley junction lxxv

A417 Missing Link | HE551505 Highways England

Figure B-14 Fuller’s Earth Formation groundwater monitoring, Ermin Way lxxvi Figure B-15 Inferior Oolite Group groundwater monitoring – Ch 1+700 to Ch 2+250, Air Balloon lxxvii Figure B-16 Inferior Oolite Group groundwater monitoring – Ch 2+250 to Ch 2+750, Air Balloon lxxviii Figure B-17 Inferior Oolite Group groundwater monitoring – Barrow Wake lxxix Figure B-18 Inferior Oolite Group groundwater monitoring – Barrow Wake lxxx Figure B-19 Inferior Oolite Group groundwater monitoring – B4070 realignment lxxxi Figure B-20 Inferior Oolite Group groundwater monitoring – Shab Hill junction lxxxii Figure B-21 Inferior Oolite Group groundwater monitoring – Shab Hill junction lxxxiii Figure B-22 Inferior Oolite Group groundwater monitoring – Shab Hill junction to Cowley junction lxxxiv Figure B-23 Lias Group, Bridport Sand Formation groundwater monitoring – Air Balloon lxxxv Figure B-24 Lias Group, Bridport Sand Formation groundwater monitoring – Barrow Wake lxxxvi Figure B-25 Lias Group groundwater monitoring – CH1+000 to CH1+400 (northern side of A417) – mid Crickley Hill lxxxvii Figure B-26 Lias Group groundwater monitoring – CH1+000 to CH1+400 (northern side of A417) – mid Crickley Hill lxxxviii Figure B-27 Lias Group groundwater monitoring – CH1+000 to CH1+400 (southern side of A417) – mid Crickley Hill lxxxix Figure B-28 Lias Group groundwater monitoring – Air Balloon xc Figure B-29 Lias Group groundwater monitoring – CH1+000 to CH1+400 (southern side of A417) – Upper Crickley Hill xci Figure C-1 Mass movement deposits groundwater quality xciii Figure C-2 Mass movement deposits/Lias Group mudstone groundwater quality xciv Figure C-3 Great Oolite limestone groundwater quality xcv Figure C-4 Fuller’s Earth Formation groundwater quality xcvi Figure C-5 Inferior Oolite Group groundwater quality xcvii Figure C-6 Bridport Sand Formation groundwater quality xcviii Figure C-7 Lias Group mudstones groundwater quality xcix

Table of Tables Table 2.1 CAMS water resource availability summary ii Table 2.2 Summary of WFD groundwater bodies iv Table 3.1 Consented groundwater discharge licences within 1km of the scheme xv Table 5.1 Summary of groundwater monitoring in superficial mass movement deposits at Crickley Hill xix Table 5.2 Summary of groundwater monitoring in Great Oolite Group limestones xxii Table 5.3 Summary of groundwater monitoring in Fuller’s Earth Formation xxiv Table 5.4 Summary of groundwater monitoring in Inferior Oolite Group xxv Table 5.5 Summary of groundwater monitoring in Lias Group – Bridport Sand Formation xxix Table 5.6 Summary of groundwater monitoring in Lias Group undifferentiated mudstones xxx Table 7.1 Summary of field testing results xxxiii Table 7.2 Summary of published hydraulic conductivities for bedrock in the Cotswolds xxxiv

A417 Missing Link | HE551505 Highways England

Table 8.1 Summary of hydrogeological units xxxvii Table 8.2 Ch 0+000 to Ch 0+500 Crickley Hill approach conceptual model elements xxxix Table 8.3 Ch 0+500 to Ch 1+700 Crickley Hill escarpment conceptual model elements xxxix Table 8.4 Ch 1+700 to Ch 2+800 Air Balloon conceptual model elements xli Table 8.5 Ch 2+800 to Ch 3+500 Shab Hill junction conceptual model elements xli Table 8.6 CH3+500 to CH5+760 conceptual model elements xlii Table 8.7 Proposed hydraulic parameters xliv Table 10.1 Summary of potential impacts to springs li Table 10.2 Cutting from Ch 1+700 to Ch 2+800 detailed assessment summary lii Table 10.3 B4070 link road cutting detailed assessment summary liii Table 10.4 Shab Hill junction to Cowley junction cuttings detailed assessment summary liv Table 10.5 Cowley junction east cutting detailed assessment summary lv Table 10.6 Summary of potential impacts to springs lv Table A.1 Summary of groundwater monitoring installations lix

A417 Missing Link | HE551505 Highways England 1 Introduction 1.1 Purpose of this document 1.1.1 The purpose of this document is to present the hydrogeological impact assessment (HIA) for the scheme supporting the Environmental Statement (ES). This HIA presents the baseline conditions of groundwater features and assesses potential impacts to groundwater flows, levels and quality from the scheme. 2 Methodology

2.1 Overview 2.1.1 The Cotswold region is an area of valued geological and environmental interest and importance. To understand the environmental risks of the scheme in the context of groundwater, a desktop study and review of ground investigation data was completed to understand the groundwater regime and the potential impact of the design elements. 2.1.2 The geological setting and ground conditions along the scheme are presented in ES Chapter 9 Geology and soils (Document Reference 6.2). 2.2 Ground investigations 2.2.1 Details of the completed intrusive ground investigations are presented in ES Chapter 9 Geology and soils (Document Reference 6.2). The following sections focus on the hydrogeological aspects of these investigations.

Phase 1 ground investigation 2.2.2 The Phase 1 ground investigation was completed between January and February 20191. The scope of works included eight boreholes with standpipe installations in each and water level loggers were installed within four of these. The boreholes were positioned in four locations, including National Star College (DS/RC 408 and OH 407), Air Balloon public house (DS/RC 406 and OH 405), Barrow Wake (DS/RC 419 and DS/RC 404) and Ermin Way (Roman Road) (DS/RC 415 and OH 406). A summary of the monitoring installations is presented in Appendix A of this document. 2.2.3 Groundwater monitoring of the eight Phase 1 boreholes commenced in February 2019 and is currently on-going with a scheduled completion in August 2021. The locations are scheduled to provide continuous logging data and dip meter measurements on a monthly basis. It was not possible to take dip meter measurements between June 2019 and August 2019.

Phase 2A ground investigation 2.2.4 The Phase 2A ground investigation included the installation of 52 groundwater monitoring boreholes, where the proposed in-situ testing and monitoring of these boreholes included:  38 locations with monthly dip measurements  14 locations with water level loggers for continuous groundwater level monitoring and monthly dip measurements  7 variable head tests 2.2.5 The field works of the Phase 2A ground investigation was completed in October 2020. Groundwater level monitoring is still on-going with a scheduled completion

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE i A417 Missing Link | HE551505 Highways England

in August 2021. The monitoring installation coverage to date is concentrated in land parcels where access has been granted. 2.2.6 Monitoring of the Phase 2A boreholes constructed early in the ground investigation programmed commenced at the end of May 2019 and is currently ongoing. Currently the available groundwater monitoring data comprises dip meter and water level loggers. 2.2.7 A total of 60 monitoring locations from Phase 1 and Phase 2A are included in this HIA to support the ES. 2.3 Baseline conditions scope 2.3.1 The locations of groundwater monitoring installations used to inform this baseline conditions review are presented in ES Figure 13.9 Groundwater monitoring locations (Document Reference 6.3). Monitoring data received up until the 31 October 2020 has been considered in this assessment. The factual data is presented in ES Appendix 9.3 Ground investigation factual report (Document Reference 6.4). 2.3.2 Barometric loggers have been installed in the headworks of select borehole locations during the Phase 1 and Phase 2A. These locations include: DS/RC 408 at Air Balloon, CP 223 on Crickley Hill and DS/RC 220 between Shab Hill junction and Cowley junction. 2.3.3 Daily rainfall data has been acquired for the Ebsworth rainfall gauge (461800) from the Environment Agency (EA). The gauge is located approximately 5.4 km south-west of the scheme. 2.4 Designations and directives Catchment Abstraction Management Strategy (CAMS) 2.4.1 The scheme is located within three CAMS areas as designated by the EA. These are listed below and presented in ES Figure 13.8 Catchment abstraction management strategy areas (Document Refence 6.3):  The Severn Corridor2 – up to approximately Ch 2+100, west of the groundwater divide.  The Cotswolds3 – between approximately Ch 2+100 and Ch 3+800, east of the groundwater divide.  The Severn Vale4 – from approximately Ch 3+800, west of the groundwater divide. 2.4.2 The availability of water for abstraction within the catchments is presented in Table 2.1. Generally, there is water available in the Severn Corridor catchment but limited to no water available within the Cotswolds and Severn Vale catchments. Table 2.1 CAMS water resource availability summary

Flow type Severn corridor Cotswolds Severn Vale Q95 (lowest) Limited water available Water not available Limited water available Q70 Water available Water not available Limited water available Q50 Water available Water not available Limited water available Q30 (highest) Water available Restricted water Limited water available available

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE ii A417 Missing Link | HE551505 Highways England

EA designations 2.4.3 Aquifers within the study area that have been designated by the EA are listed in the following paragraphs and are presented in ES Figure 13.6 Aquifer designations (Document Refence 6.3). 2.4.4 The Cheltenham Sand and Gravel and alluvial deposits are designated by the EA as Secondary A aquifers. This designation indicates that the aquifers are ‘permeable layers capable of supporting water supplies at a local rather than a strategic scale, and in some cases forming an important source of base flow to rivers’5. 2.4.5 The Great Oolite Group (excluding the Fuller’s Earth Formation) and Inferior Oolite Group are designated as Principal aquifers, described as “permeable layers capable of supporting water supplies at a local rather than strategic scale, and in some cases forming an important source of base flow to rivers”6. 2.4.6 The Fuller’s Earth Formation is classified by the EA as an Unproductive aquifer associated with “low permeability [and] negligible significance for water supply or river base flow”7. 2.4.7 In the study area, the BGS present the stratigraphy encompassing the upper parts of the Lias Group and the lower parts of the Inferior Oolite Formation as the ‘Lias Group and Inferior Oolite (undifferentiated)’. Owing to this stratigraphy being combined, the Lias Group and Inferior Oolite (undifferentiated)’ is designated by the EA as a Principal aquifer. Based on descriptions of the Lias Group8, the Bridport Sand Formation is considered a minor aquifer. However, the site-specific information in this report is based upon ground investigation data from this scheme, thereby this provides a higher resolution to the EA mapping in the site area. As such the properties of the aquifers in this area are based on site specific information. 2.4.8 In the study area, the Charmouth Mudstone Formation is classified by the EA as a Secondary (undifferentiated) aquifer, described as “both minor and non-aquifer in different locations due to the variable characteristics of the rock types”9. Water Framework Directive (WFD) 2.4.9 The scheme is located over two river basin districts: the Severn to the west and the Thames to the east. The topographical catchment boundary along the Upper Cotswolds Plateau generally correlates to the groundwater divide between the Severn and Thames catchments10. These river basin districts are divided into three WFD groundwater bodies, where two are within the Severn Vale catchment and one is within the Thames catchment11. A summary of the WFD groundwater bodies is presented in Table 2.2 and ES Figure 13.4 WFD groundwater bodies (Document Refence 6.3). 2.4.10 The superficial deposit aquifers are not specifically designated as WFD groundwater bodies. However, it is anticipated they are hydraulically connected to the relevant underlying designated WFD groundwater bodies presented in Table 2.2. 2.4.11 The Severn Vale catchment is divided into the Severn Vale - Jurassic Limestone Cotswold Edge South (ID GB40901G305700) and the Severn Vale - Secondary Combined (ID GB40902G204900) groundwater bodies. These groundwater bodies locally drain towards the west into the River Frome and Norman’s Brook, and their tributaries.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE iii A417 Missing Link | HE551505 Highways England

2.4.12 The Severn Vale - Jurassic Limestone Cotswold Edge South groundwater body generally correlates to areas of the Great Oolite Group, Inferior Oolite Group and Upper Lias Group, west of the groundwater divide. 2.4.13 The Severn Vale - Secondary Combined groundwater body includes areas underlain by the Charmouth Mudstone Formation at the base of the Lias Group at the western end of the scheme. 2.4.14 The Thames catchment includes the Burford Jurassic WFD groundwater body (ID GB40601G600400). The Burford Jurassic groundwater body generally correlates to the Great Oolite Group and the Inferior Oolite Group limestones that drain towards the south-east where the Inferior Oolite is confined by the Fuller’s Earth Formation. The aquifers locally feed into the River Churn and its tributaries in the south-east. 2.4.15 The overall 2019 status of both the Jurassic Limestone Cotswolds Edge South and Secondary Combined groundwater bodies is ‘good’, however the Burford Jurassic is poor. Table 2.2 Summary of WFD groundwater bodies12

Burford Jurassic Severn Vale – Jurassic Severn Vale – limestone Cotswolds secondary combined edge south Groundwater body ID GB40601G600400 GB40901G305700 GB40902G204900 Operational catchment Burford Jurassic Severn Vale – Jurassic Severn Vale – Limestone Cotswolds Secondary Combined Edge South Management catchment Thames GW Severn England GW Severn England GW River basin district Thames Severn Severn Current overall status Poor (2019) Good (2019) Good (2019) Current quantitative Good (2019) Good (2019) Good (2019) status Current chemical status Poor (2019) – poor Good (2019) Good (2019) nutrient management (diffuse sources) and private sewage treatments (point sources) Quantitative objective Good by 2027 Good by 2015 Good by 2015 Chemical objective Good by 2027 Good by 2015 Good by 2015 Protected area Drinking water protected Drinking water protected Drinking water protected area and nitrates area and nitrates area and nitrates directive. directive. directive.

3 Baseline

3.1 Regional geology Superficial deposits 3.1.1 Superficial deposits are located on Crickley Hill (west of the Cotswold Escarpment crest), in the Churn Valley (near Shab Hill Farm) and in the Frome Valley (near Stockwell-Nettleton) (ES Figure 9.3 Geological map (Document Reference 6.3)).

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE iv A417 Missing Link | HE551505 Highways England

Detailed descriptions of the superficial deposits are presented in ES Chapter 9 Geology and soils (Document Reference 6.2). 3.1.2 The superficial deposits comprise of13,14:  Mass movement deposits – landslide deposits, cohesive material derived from limestone and mudstone parent materials.  Alluvial deposits - clay, silt, sand and gravel  Cheltenham sand and gravel - sand, quartzose, fine to medium grained, generally unbedded, with seams of poorly sorted predominantly limestone gravel, especially in the lower part 3.1.3 For the purposes of this scheme ‘mass movement deposits’ and ‘head’ are being used as a general terms for transported slope material derived from the underlying bedrock and transported to its current position as a result of a range of slope processes, including landslides, hillwash, and soil creep. 3.1.4 Mass movement deposits underlie the scheme on Crickley hill where the underlying Lias Group mudstones is the parent material reworked by slope processes. 3.1.5 Head deposits includes superficial deposits overlying the Great Oolite Group and the Inferior Oolite Group. Head deposits underlie the scheme within the valley at Shab Hill junction, which feeds into the River Churn. These deposits are also present in the valleys that feed into the River Frome, west of the scheme’s southern end. 3.1.6 Alluvial deposits are present west of the scheme’s southern end, in the Frome Valley. 3.1.7 Cheltenham Sand and Gravel underlie the western end of the scheme and extend towards the north west. Bedrock geology 3.1.8 The scheme is underlain by three bedrock geological groups (Figure 1), where the Fuller’s Earth Formation is laterally continuous in the A417 study area15. The bedrock geology underlying the scheme is presented in ES Figure 9.3 Geological map (Document Reference 6.2) and detailed descriptions of the bedrock units are presented in ES Appendix 9.2 Preliminary ground investigation report (Document Reference 6.4). Structurally these bedrock units generally dip between 2º and 5º towards the east and south-east. The bedrock groups include, from youngest to oldest:  Great Oolite Group – Jurassic aged limestones and basal mudstone  Inferior Oolite Group – Jurassic aged limestones  Lias Group – Triassic aged mudstones with limestone and sandstone beds

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE v A417 Missing Link | HE551505 Highways England

Figure 1 Idealised conceptual model of the hydrogeological processes in the mid-Cotswold area16

Great Oolite Group 3.1.9 The Great Oolite Group includes the White Limestone Formation, the Hampen Formation and the Fuller’s Earth Formation. It underlies the scheme to the south of Shab Hill fault (ES Figure 9.3 Geological map (Document Reference 6.2)). 3.1.10 The White Limestone Formation, being the highest geological unit in the area, is only present on some hill tops. Where present, it has been eroded down to a thickness of less than 6 m. It is generally described as a weak to medium strong highly fractured bioclastic and ooidal limestone. The fractures are often stained and have a calcite precipitate. 3.1.11 The Hampen Formation generally comprises a weak bioclastic and ooidal limestone with frequent calcite veining (up to 3 mm) and closely spaced fractures. The fractures are generally undulating, rough, clean from infill and often stained orangish brown. The Hampen Formation is thickest in the downthrown fault block to the west of Shab Hill junction, where it has been encountered at depths up to 15 mbgl. 3.1.12 The Fuller’s Earth Formation is a grey/brown mudstone with limestone beds (up to about 2m thick) at the base of the Great Oolite Group that is up to approximately 20 m thick in the site area. It generally has closely spaced undulating sub-horizontal fractures that are rarely infilled. The Fuller’s Earth Formation is laterally persistent in the study area and is at ground surface south of Stockwell fault.

Inferior Oolite Group 3.1.13 The Inferior Oolite Group includes the Salperton Limestone Formation, the Aston Limestone Formation and the Birdlip Limestone Formation. The Inferior Oolite Group underlies the scheme from the crest of the Cotswold Escarpment to the northern side of the Shab Hill fault (ES Figure 9.3 Geological map (Document Reference 6.2)).

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE vi A417 Missing Link | HE551505 Highways England

3.1.14 It is anticipated that the entire sequence of the Inferior Oolite Group would be encountered moving from the Cotswold Escarpment to the Shab Hill junction. The Salperton Formation (the uppermost formation) comprises a weak to moderately strong bioclastic to ooidal limestone with closely to medium spaced fractures. Fractures have been described as sub horizontal to around 20°, undulating, rough and stained. 3.1.15 The Aston Formation (underlying the Salperton Formation) comprises a moderately strong bioclastic to ooidal limestone with closely to medium spaced fractures. Fractures have been described as sub horizontal to around 40°, undulating, rough, stained and some are infilled with clay. 3.1.16 The Birdlip Limestone Formation (the lowermost formation), comprises a weak to moderately strong, predominantly bioclastic limestone. A range of fracture spacing has been recorded within the Birdlip Limestone but predominantly range from 50 mm to 200 mm. Fractures have been described as sub horizontal to 30° and sub vertical, undulating, rough and stained and some are clay infilled. The Inferior Oolite Group is underlain by the Lias Group mudstones and the surface boundary between these units is near the crest of the Cotswolds escarpment.

Lias Group 3.1.17 The Lias Group in the Cotswolds area comprises the Worcester Basin Formations. The Worcester Basin includes the Bridport Sand Formation, the Whitby Mudstone Formation, the Marlstone Rock Formation, the Dyrham Formation and the Charmouth Mudstone Formation. The Whitby Mudstone Formation, Dyrham Formation and Charmouth Mudstone Formation are the thicker formations within the Lias Group. Largely comprising mudstone and silty mudstone the formations are relatively impermeable. 3.1.18 The Bridport Sand Formation is typically described as an extremely weak siltstone and is often weathered to a very stiff sandy silt. In some locations the Bridport Sand Formation comprises beds of extremely weak fine sandstone, which during drilling was recovered as a slightly sandy clayey sandstone gravel. The fractures in the Bridport Sand Formation are very closely to medium spaced (20 – 600mm) and are rarely infilled. 3.1.19 The Whitby Mudstone Formation has been identified predominantly in the lower Crickley Hill valley, but it was also encountered in some holes as far northeast as the Air Balloon Roundabout. It is typically described as a firm to very stiff fissured dark brownish grey clay. It locally contains gravel and cobbles and is occasionally slightly sandy. The gravel is subangular to sub-rounded limestone, mudstone, siltstone and sandstone. The cobble is typically limestone. There are occasional bands of extremely weak to weak laminated grey mudstone or medium strong limestone. Fractures within the mudstone are closely to widely spaced planar smooth. 3.1.20 The Marlstone Rock Formation was encountered across the study area and was typically encountered as medium strong to strong limestone with rare to frequent shell fragments. Fractures are generally closely spaced, sub horizontal, undulating and smooth to rough with occasional orange staining. 3.1.21 The composition of the Dyrham Formation is varied. It is typically encountered as bands of either a weak light grey limestone, a very stiff thinly laminated sandy silty clay, a very stiff silt or an extremely weak mudstone.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE vii A417 Missing Link | HE551505 Highways England

3.1.22 The Charmouth Mudstone Formation presents as a stiff to very stiff mottled grey silty clay or an extremely weak to very weak laminated dark grey mudstone with very close to closely spaced undulating smooth fractures, locally stained orange. 3.1.23 The Lias Group is mostly overlain by other geological units in the area, however it does influence the geological and hydrogeological processes within the region. On the western side of the Cotswold escarpment the Lias Group is covered by a mantle of mass movement deposits and at the western end of the scheme by localised Cheltenham Sand and Gravel (ES Figure 9.3 Geological map (Document Reference 6.2)). To the east of the escarpment, the Lias Group is overlain by Inferior Oolite limestone. Structural geology 3.1.24 The published geological faults in the region that the scheme is likely to intersect are the Shab Hill fault, the Shab Hill Barn fault and Stockwell fault. The faults typically strike north-west to south-east and are presented on ES Figure 9.3 Geological map (Document Reference 6.2). 3.1.25 The position of published faults has been revised following review of the geomorphological, ground investigation and surface geophysics information (ES Appendix 9.2 Preliminary ground investigation report (Document Reference 6.4). This review also identified two additional faults underlying the scheme:  The Churn Valley fault at Shab Hill Junction, striking north-west to south-east between the Shab Hill fault and the Shab Hill Barn fault.  The Cally Hill fault, located at Ch 4+000 and striking north-east to south-west. 3.1.26 The revised positions of the faults have been adopted for the ES and are presented on ES Figure 9.3 Geological map (Document Reference 6.2). 3.1.27 The geological setting in conjunction with Quaternary glacial and interglacial processes has facilitated a number of processes, which create the geomorphological setting of the Cotswold region. The Cotswold escarpment is a pronounced feature in the region, which formed from mechanical stress relief in the rock mass during the Quaternary. 3.1.28 It is likely that cambering, valley-bulging, and both rotational and translational landslides occurred during the transitional periods in the Quaternary, facilitated by lateral stress relief during valley erosion and reduced effective stresses caused by increased pore water pressure initiated by the melting of ground-ice, as illustrated in Figure 2. Evidence of mass movement, such as landslides, cambering, gulls, and solifluction (soil creep due to freeze-thaw activity) are present along the Cotswold Escarpment at Crickley Hill. These deposits are collectively referred to as mass movement deposits. 3.1.29 Gulls and cambering within limestone formations have the potential to be further solutionally enlarged and where this has occurred they are included as karst features. Karst features, where present, are discussed in Section 3.2 Regional Hydrogeology. 3.1.30 Gulls mostly occur at the Cotswold escarpment edge. Further away from the Cotswold escarpment the only karst features recorded include the dry valley at Shab Hill and voids within the Inferior Oolite Group. Self & Boycott (2004) identified in the Stroud area that the tributaries of the River Frome have incised deeply through the Great Oolite Group limestones and into the Fuller’s Earth Formation but no gull caves are known17. Similar conditions were found in the Great Oolite Group at the southern end of the scheme.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE viii A417 Missing Link | HE551505 Highways England

Figure 2 Schematic illustration of cambering, valley bulging and landslides (modified from Farrant et al., 2014) 18

3.2 Regional hydrogeology 3.2.1 The hydrogeology of the Cotswold region is influenced by the complex relationship between aquifers, aquitards, periglacial geomorphology and surface water – groundwater interactions. An idealised model of the regional hydrogeological processes is presented in Figure 1. In the scheme area, ‘head’ deposits cover the Lias Group formations and the Fuller’s Earth Formation is laterally continuous. Superficial deposits 3.2.2 The superficial deposits comprise alluvial deposits, mass movement deposits, head deposits and the Cheltenham Sand and Gravel in discrete areas beneath and around the scheme. The alluvial, mass movement and head deposits are largely clay dominated with isolated lenses of sand and gravel. The mass movement deposits also include toppled limestone blocks and material from the underlying Lias Group. Groundwater flow through the superficial deposits will be locally variable and limited to more permeable zones. The mass movement and head deposits are not an EA designated aquifers, however groundwater within these deposits support groundwater-surface water interactions, including springs and seepages. Where springs are point flow groundwater emergences and seepages as diffuse groundwater emergences. 3.2.3 Groundwater flow through the superficial deposit aquifer is dominated by intergranular flow where the permeability will support it. Coarse grained units within the clay dominated deposits are likely to facilitate local zones of groundwater flow and will create zones of perched groundwater. These more permeable zones promote localised shallow groundwater flow which emerge as springs and seepages within the superficial deposits in the Crickley Hill area, which support flow in the tributary of Norman’s Brook. 3.2.4 The superficial deposits are unconfined however within the clay dominated material localised confinement of water bearing, coarse grained units are likely. Groundwater levels are likely to be locally variable and shallow in the superficial deposit aquifer. 3.2.5 On the northern side of the A417 between approximately CH1+600 to CH1+700, historic counterfort drains are present within the mass movement deposits (Appendix A, Preliminary ground investigation report (ES Appendix 9.2 (Document Reference 6.4)). Based on the location of these drainage measures they are anticipated to locally control groundwater levels within the mass

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE ix A417 Missing Link | HE551505 Highways England

movement deposits by capturing flow that they intersect. On this basis groundwater levels in the mass movement deposits are artificially lowered at this location. Great Oolite Group - limestone formations 3.2.6 The Great Oolite Group comprises of a sequence of limestone that locally is interbedded with mudstone. The Great Oolite Group forms the upper stratigraphy of the Cotswold plateau and often forms isolated outliers on hill tops. Owing to the Great Oolite Group forming the top of high ground it is unconfined but mudstone interbeds within the group locally confine limestone units. The limestone formations are underlain by the Fuller’s Earth Formation, which is the lowest formation of the Great Oolite Group. 3.2.7 As detailed in section 3.1.10, the limestone units of the Great Oolite Group are thickest between the Shab Hill and Shab Hill Barn faults. At this location the limestones are dominant and generally not interbedded with mudstones. The base of the Great Oolite Group limestone formations at Shab Hill junction extends to 15 m below ground level. To the south of the Shab Hill Barn fault, limestone of the Great Oolite Group is present but has significantly increased interbedding with mudstone. 3.2.8 The underlying Fuller’s Earth Formation forms a basal barrier to downward flow. Where mudstone is present in the limestone formations this will locally perch groundwater levels in the limestone units. 3.2.9 Groundwater flow in the Great Oolite Group limestone is largely dominated by secondary porosity with localised tertiary enhancement by karst processes. As such, the Great Oolite Group limestone formations can have a local high rate of transmissivity but otherwise has low primary matrix porosity storage capacity. Secondary porosity features include joints and bedding planes within the rock mass. Karst features identified in the Great Oolite Group include a dry valley at Shab Hill, a small number of shallow voids (<0.6m) are identified in the scheme GI program and several springs and seepages, which occur at the escarpment margins near the base of the Great Oolite Group and feed an unnamed tributary to the Churn and an unnamed tributary to the Frome. 3.2.10 The ground investigation drilling logs and downhole calliper identified shallow near surface voids (c.40cm in dimension) in borehole OH 413 at Shab Hill junction. Fractures with open fractures (with staining from groundwater flow) are identified in boreholes OH 411 and DS/RC/OH 400. 3.2.11 Between the Shab Hill Barn fault and Stockwell fault the Great Oolite Group dominantly comprises of mudstone units with minor limestone units. As a result, the effective horizontal hydraulic conductivity of the transition zone will only occur in limestone units where present and the vertical conductivity of the transition zone will be limited by the hydraulic conductivity of mudstone units. 3.2.12 Limestones that are locally confined by mudstone will have limited recharge, which will largely only occur where leakage via fracturing provides a pathway through overlying interbedded mudstone. Limestone units that are near surface and not confined will be directly recharged by rainfall. Great Oolite Group – Fuller’s Earth Formation 3.2.13 The Fuller’s Earth Formation is a grey mudstone with thin limestone beds, which is the basal formation of the Great Oolite Group. In the study area the Fuller’s

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE x A417 Missing Link | HE551505 Highways England

Earth Formation aquitard is laterally continuous below the Great Oolite Group limestones and above the Inferior Oolite Group. 3.2.14 South of the Stockwell fault and underlying Cowley junction, mudstone units become more dominant with fewer limestone units. The mudstone units will likely form a barrier to groundwater flow there may be localised confined groundwater flow associated with the minor limestone units. Inferior Oolite Group 3.2.15 The Inferior Oolite Group forms the crest of the Cotswold escarpment and extends south-east from the escarpment (ES Figure 9.3 Geological map (Document Reference 6.2)). This limestone aquifer is largely unconfined, however in the southern portion of the scheme it is partially confined by the Fuller’s Earth Formation mudstone aquitard. 3.2.16 Groundwater flow through the limestones is dominated by secondary (fracture) porosity pathways and tertiary (karstic) porosity features, so the aquifer may locally have a high fracture or karstic permeability even though the primary matrix porosity characteristically provides low storage capacity. Karst features identified in the Inferior Oolite Group include four limestone springs (springs 16, 17, 18 and 19) at Crickley Hill and a dry valley at Barrow Wake (G3). 3.2.17 Evidence from the ground investigation, including downhole geophysics and geological logging, indicates that voids are common within the Inferior Oolite Group. Voids identified by down the hole calliper and camera range from 10mm to 140mm in dimension, varying in shape from rounded to irregular and predominantly iron stained with occasional sandy clay infill. Voids were logged at varying depths but were predominantly present logged towards the base. 3.2.18 Stress relief along fractures, joints and bedding planes that occur in conjunction with cambering processes will be higher closer to the margins of the Cotswold escarpment. It is possible that these features may be locally enhanced by karst processes. 3.2.19 Is it likely that fissures and gulls along the escarpment form part of the flow paths for groundwater to feed springs and seepages identified in the Inferior Oolite Group. In cases where the base of the Inferior Oolite Group is covered by mass movement deposits then groundwater from the Inferior Oolite Group may drain into the superficial deposits where they are sufficiently permeable. Based on the interface between bedrock geology and superficial geology then this will only occur in the upper most superficial deposits in those locations where the mass movement deposits cover the Inferior Oolite Group. 3.2.20 A potential gull feature is observed in the downhole calliper and camera record within the Bridport Sand/Lias for borehole (DS/RC 301), which lies close to the escarpment edge. Lias Group 3.2.21 The Whitby Mudstone Formation, Dyrham Formation and Charmouth Mudstone Formation are the thicker formations within the Lias Group and are the prime influence for the group’s hydraulic properties. Largely comprising mudstone and silty mudstone the formations have relatively low permeabilities and function as aquitards.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE xi A417 Missing Link | HE551505 Highways England

3.2.22 The Bridport Sand Formation and Marlstone Rock Formation are relatively thinner geological units that have greater permeability and can influence more localised groundwater flow. 3.2.23 The Bridport Sand Formation, at the top of the Lias Group, can locally be hydraulically connected with the base of the Inferior Oolite Group where fracturing or more permeable lithological units are present. Groundwater flow through the Bridport Sand Formation is occurs due to secondary porosity features including bedding planes and joints to the local connectivity between Inferior Oolite Group and Lias Group Bridport Sand Formation these are considered as the same aquifer across the study area. As such, springs and seepages in the Bridport Sand Formation may be fed in part from the Inferior Oolite Group. 3.2.24 The Marlstone Rock Formation can be greatly affected by cambering19. The cambering processes will be more pronounced closer to the edge of the escarpment. Relatively higher hydraulic conductivity within the Marlstone Rock Formation, relative to the overlying Whitby Mudstone Formation, may promote a local flow zone. Groundwater quality 3.2.25 Limestone aquifers are particularly vulnerable to contamination, which may originate from point or diffuse sources. In accordance with the Nitrate Pollution Prevention Regulations 2015, the EA have identified areas at risk of agricultural nitrate pollution and have designated these as nitrate vulnerable zones (NVZ)20. Waters are defined within the Nitrate Pollution Prevention Regulations 2015 as polluted if they contain or could contain, if preventative action is not taken, nitrate concentrations greater than 50mg/l21. 3.2.26 The EA has designated the Upper Cotswold Plateau, limestone at the crest of the Cotswold escarpment and the northern side of Crickley Hill (approximately 220m north of the scheme at Crickley Hill) as an NVZ22. 3.2.27 Bicarbonate rich groundwater is expected to be the dominant water type in the region given the presence of limestone23. The quality testing completed for the scheme is discussed in section 6. The geochemistry of waters in carbonate aquifers is particularly affected by residence times and mixing with recharge, older formation water and/or anthropogenic influences. Water types can typically be categorised by source, age and geological conditions including aquifer confinement. A schematic showing the conceptualisation of the Cotswold Plateau is shown in Figure 3, and described in the following paragraphs. Note, unlike the conceptual model presented in Figure 3 the Fuller’s Earth Formation is laterally continuous in the study area. 3.2.28 Groundwater close to recharge areas are typically oxidising and strongly pH - 24 buffered with calcium and bicarbonate (HCO3 ) as dominant dissolved ions . Recharge areas are particularly susceptible to high nitrate concentrations from agricultural pollution. This is anticipated to be most reflective of unconfined waters the scheme may encounter. 3.2.29 Regionally, as groundwater becomes more confined, down gradient of recharge areas, ion-exchange processes occur, with sodium and bicarbonate being the dominant ions in the groundwater25. The process of ion exchange causes dissolved calcium ions in the groundwater to attach or ‘adsorp’ onto the rock surface and, in exchange, sodium ions come off the rock surface and into the groundwater.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE xii A417 Missing Link | HE551505 Highways England

3.2.30 In more confined groundwaters, dissolved oxygen is reduced or absent, with conditions becoming more reducing, which is evidenced by redox-sensitive elements26. Lower nitrate levels can suggest that denitrification may be occurring27, however this could also be affected by mixing with old formation waters deep within the aquifer that have low nitrate levels when entering the aquifer. 3.2.31 Mixing with older formation water deeper within the confined aquifer results in a sodium-chloride type groundwater. Isotope analysis suggests a residence time in the order of thousands of years for these waters28. 3.2.32 Neumman et. al. (2003) concluded no significant differences in the chemistry of the Great and Inferior Oolite groundwaters can be observed29.

Figure 3 Conceptual model of redox conditions within the Cotswolds30 Recharge 3.2.33 The mean annual estimated recharge for the Cotswold area is 370mm per annum31. The amount of recharge can be wide ranging, as Morgan-Jones and Eggboro (1981) noted in the hydraulic years of 1975 and 1976 where recharge was 100mm and 630mm respectively. 3.2.34 The superficial deposit aquifers are recharged by a variety of mechanisms including rainfall infiltration, run off from low permeability mudstones and groundwater draining from limestone aquifers higher in the landscape. It is possible that limestone inclusions within mudstone formations and the Marlstone Rock Formation could also be locally, hydraulically linked to the superficial deposit aquifer. In the Churn and Frome valleys, the superficial deposits may be leaking into the underlying Inferior Oolite Group. 3.2.35 The Great Oolite Group limestone is recharged directly by rainfall. The underlying Fuller’s Earth Formation perches the groundwater within the Great Oolite Group limestones and limits the connection with the underlying Inferior Oolite Group except where a fault is present. Springs and seepages emerging from the base of the Great Oolite limestones at the boundary with the Fuller’s Earth Formation boundary have the potential to recharge the Inferior Oolite limestones downgradient.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE xiii A417 Missing Link | HE551505 Highways England

3.2.36 Recharge of the Inferior Oolite limestone in the scheme area is from rainfall where exposed. Maurice et. al. (2008) suggest leakage via the Fuller’s Earth Formation due to faulting, which locally connects the Great Oolite Group and the Inferior Oolite Group32. However, this may only occur during the wetter months of the year when drainage from the unconfined Great Oolite aquifer reduces the elevation of the water table such that the saturated zone of the aquifer thins to an extent that transmissivity is greatly reduced33. 3.2.37 The future baseline conditions from the UK Climate Projections 2018 (UKCP18) indicates that the study area may undergo climatic changes including higher temperatures, increase in heat waves, reduced precipitation in summer and increased precipitation in winter. 3.2.38 The future baseline conditions are likely to reduce the amount of recharge to the groundwater aquifers which may have impacts upon groundwater dependent features near the scheme and cause some perennial features to become seasonal. Abstractions, springs, seepages, groundwater fed watercourses, areas of flooded ground and Bushley Muzzard SSSI are likely to be particularly sensitive to these impacts. Groundwater quality is also likely to be affected by a reduction in the flushing of aquifers, which may increase the residence time of groundwater within them. Abstractions 3.2.39 The Baunton public water supply abstraction (approximately 12km south-east of the scheme) and associated source protection zone (SPZ) is located within the Thames groundwater catchment. The Baunton abstraction takes groundwater from the Inferior Oolite aquifer and its associated SPZ3 (corresponding to the total catchment area) is intersected by part of the scheme between Shab Hill junction and Cowley junction. 3.2.40 Land east of Cowley junction, and extending south along the scheme, is located within SPZ3. The southern end of the scheme is approximately 2.8km from SPZ2 and 3.4km from SPZ1 in the south-east (ES Figure 13.5 Hydrogeological study area and features (Document reference 6.3)). 3.2.41 There are no further recorded licensed abstractions known within 1km of the scheme. 3.2.42 The water feature survey identified 16 potentially unlicensed abstractions, boreholes and wells near the scheme (refer to Appendix 13.11 Water features survey (Document Reference 6.4)). Many of these features were either not in use or details on their usage and groundwater source were not able to be obtained. The locations of these are presented on ES Figure 13.5 Hydrogeological study area and features (Document reference 6.3). Consented discharge 3.2.43 To date there have been nine consented discharges of treated sewage or unspecified combined sewage and trade effluent to land and underground strata recorded within 1km of the scheme34. Of these, three discharge licenses are still active and are located at Air Balloon public house, Crickley Hill and the Birdlip wastewater treatment works approximately 1km west of the scheme. The consented discharge locations are presented on ES Figure 13.5 Hydrogeological study area and features (Document reference 6.3). 3.2.44 These consented groundwater discharges are existing potential point sources of pollution to the underlying aquifers.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE xiv A417 Missing Link | HE551505 Highways England

Table 3.1 Consented groundwater discharge licences within 1km of the scheme

Site Name Site type Receiving License Effluent description water status Sewage discharges – final / Air balloon public Food and beverage To ground Revoked treated effluent - not water house services company Underground Air balloon public Wastewater treatment Sewage & trade combined - strata Active house works (not water company) unspecified (soakaway) Air balloon public Food and beverage Underground Sewage & trade combined - Revoked house services strata unspecified Underground Air balloon public Wastewater treatment Sewage & trade combined - strata Revoked house works (not water company) unspecified (soakaway) Wastewater / sewage Groundwater Sewage discharges – final / Birdlip wastewater treatment works (water into infiltration Active treated effluent - water treatment works company) system company Sewage discharges – final / Domestic property (single) Underground Crickley cottages Active treated effluent - not water (incl. farmhouse) strata company Sewage discharges – final / Domestic property (single) Hardings barn Inferior oolite Revoked treated effluent - not water (incl. farmhouse) company Sewage discharges – final / Hardings barn Domestic property (single) Inferior oolite Revoked treated effluent - not water company Dentist / hospital / nursing Sewage discharges – final / Ullenwood manor home (medical) / human Land Revoked treated effluent - not water health company Surface water 3.2.45 Details on surface water features and hydromorphological characteristics of the scheme are presented in ES Chapter 13 Road drainage and water environment (Document Reference 6.2). The scheme is located within two surface water catchments: the Severn River catchment (21,000km2) and the Thames River catchment (16,200km2). The Severn River discharges in the Bristol Channel and the Thames discharges into the North Sea. Surface water resources near scheme are managed by the Severn River Basin District River Basin Management Plan35 and the Thames River Basin District River Basin Management Plans36. 3.2.46 In the scheme area, the Severn and Thames catchment divide is set back from the Cotswold escarpment where the Severn catchment is located to the west and the Thames catchment is to the east. As a result, the scheme interacts with the headwaters of these respective surface water subcatchments, in the form of localised tributaries. The Severn River Catchment includes the Norman’s Brook and Horsebere Brook subcatchments, whilst the Thames River catchment includes the River Churn and River Frome subcatchments. 3.2.47 The tributary of Norman’s Brook is located on the southern side of the A417 along the Cotswold escarpment. The brook is groundwater dependent (gaining) along much of its reach. The tributary headwater, near the crest of the escarpment, is reliant on discharge from the upper Inferior Oolite Group aquifer. Further downstream the tributary becomes more reliant on groundwater discharge from the mass movement deposits springs and seepages.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE xv A417 Missing Link | HE551505 Highways England

3.2.48 The surface water catchments and watercourses are presented on ES Figure 13.5 Hydrogeological study area and features (Document reference 6.3). 3.3 Local geology 3.3.1 The review of the local geology is based on published geology and past ground investigation information and preliminary interpretation of available Phase 2A borehole records. Visual representation of the conceptual models as described in the following sections is shown on ES Figure 13.10 Groundwater conceptual model (Document Reference 6.3). The locations of the cross sections are shown on ES Figure 13.17 Groundwater conceptual model locations (Document Reference 6.3). Further details of the geological conditions are presented in the Preliminary ground investigation report (ES Appendix 9.2 (Document Reference 6.4)). The geological information provided in this section is used as a basis for the local hydrogeology, which is presented in Sections 4 to 9. Ch 0+000 to 0+500, Crickley Hill approach 3.3.2 Along the scheme alignment, the existing ground profile at the Crickley Hill approach gently rises from approximately 96mAOD to 114mAOD. The ground conditions comprise Cheltenham Sand and Gravel, thickening towards the west, underlain by Charmouth Mudstone Formation bedrock. Ch 0+500 to 1+700, Crickley Hill escarpment 3.3.3 The existing ground profile along the scheme alignment at Crickley Hill rises from approximately 114mAOD to 212mAOD, generally following the low point in the embayment adjacent to the tributary of Norman’s Brook. 3.3.4 The ground conditions on the escarpment are dominated by cohesive mass movement deposits. The mass movement deposits are thinner at the crest of the escarpment and thicken towards the scheme. However due to the variety of landslipping processes occurring across the escarpment, the thickness of mass movement deposits is variable. 3.3.5 Overlying the mass movement deposits are areas of localised made ground at Crickley Hill tractors and some localised alluvium is expected along the tributary of Norman’s Brook. 3.3.6 The mantle of mass movement deposits over the escarpment is underlain by the Lias Group. The top of the Lias Group in this area dips towards the tributary of Norman’s Brook. Norman’s Brook is fed by multiple springs and seepages from permeable units within the dominantly cohesive mass movement deposits. At the headwater of the tributary of Norman’s Brook are seasonal limestone springs, which are located at the contact between the Bridport Sand Formation and the Inferior Oolite Group. Ch 1+700 to Ch 3+000, cutting 3.3.7 Within the cutting from Ch 1+700 to Ch 3+000 cutting section, the existing ground cuts into the crest of the Inferior Oolite Group limestone, rising from approximately 212mAOD to 228mAOD between Ch 1+700 and Ch 1+900. From Ch 1+900 the existing ground level becomes less steep on the Upper Cotswold Plateau, which includes rolling hills up to 274mAOD. 3.3.8 The ground conditions include small localised areas of made ground, underlain by Inferior Oolite Group limestone up to approximately 35m depth. The Inferior Oolite Group limestone is underlain by the Bridport Sand Formation.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE xvi A417 Missing Link | HE551505 Highways England

3.3.9 The Shab Hill Barn fault intersects the scheme at Ch 1+925, striking in a north- west to south-east direction. Four limestone springs (springs 16,17, 18 and 19 in the water features survey) are located along the Shab Hill Barn fault near the contact between Inferior Oolite Group limestone and the underlying Lias Group Bridport Sand. Ch 3+000 to Ch 3+500, Shab Hill junction 3.3.10 The Shab Hill junction area is within the Upper Cotswold Plateau area, with low gradient rolling hills between approximately 274mAOD to 280mAOD. The plateau is intersected by a steep sided dry valley at Ch 3+140, which travels in a generally easterly direction. The steep valley sides (up to 12 degrees) are up to approximately 30m high at the eastern side of the proposed Shab Hill junction and the valley continues to deepen towards the headwaters of the River Churn. 3.3.11 The scheme is intersected by the Shab Hill fault at Ch 2+950 and the Shab Hill Barn fault at Ch 3+500, both striking in a north-west to south-east direction. A third fault, the Churn Valley fault, has been interpreted to lie between these faults, striking in a similar direction at Ch 3+200. 3.3.12 North of the Shab Hill fault the scheme is underlain by Inferior Oolite Group. Between the Shab Hill fault and Shab Hill Barn fault the scheme is underlain by the Great Oolite Group comprising the Great Oolite Group limestone formations and the Fuller’s Earth Formation, which is underlain by the Inferior Oolite Group. Ch 3+500 to Ch 5+760, Shab Hill junction to Cowley junction 3.3.13 In the Stockwell-Nettleton area, the scheme roughly follows the ridgeline of the Upper Cotswold Plateau. The existing topography features rolling hills running in a relatively north-south direction and ranging in elevation from 260mAOD to 286mAOD. 3.3.14 The scheme is underlain by the Great Oolite Group comprising the Great Oolite limestone and the Fuller’s Earth Formation. The Great Oolite Group is underlain by Inferior Oolite Limestone over Lias Group. 3.3.15 The Stockwell fault intersects the scheme at Ch 4+800 and strikes in a north-west to south-east direction. A second fault, the Calley Hill fault, has been interpreted between the Shab Hill Barn fault and Stockwell fault, intersecting the scheme at Ch 4+000 and striking north-east to south-west. 4 Groundwater monitoring programme

4.1 Monitoring 4.1.1 Groundwater monitoring is being undertaken as part of the Phase 2A investigations. Refer to ES Chapter 9 Geology and soils (Document Reference 6.2) for details of the completed intrusive investigations. In summary this provides for:  Weekly monitoring required for duration of Phase 2A fieldwork period.  Monthly monitoring required for 12 months post Phase 2A field work period.  Installation of data loggers in selected installations (set to take readings at 15mins intervals) with monthly downloads and dip meter verification at Diver data logger locations required for 12 months post Phase 2A field work period.  The Contractor may be asked to extend both the monthly monitoring of standpipes and the monthly data logger reading interval beyond the 12 month post fieldwork period, or to amend the frequencies.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE xvii A417 Missing Link | HE551505 Highways England

4.1.2 The groundwater monitoring boreholes have been selected at locations where specific design elements are proposed or where water receptors have been identified. Together, these locations provide a spatial network of groundwater monitoring across the study area so that hydraulic gradients and directions of flow can be identified. Water quality testing was also completed at selected locations and is discussed further in Section 6. The location of all groundwater monitoring locations is presented in ES Figure 13.9 Groundwater monitoring locations (Document Reference 6.3). 4.1.3 The design of each monitoring installation is presented in Appendix A of this document. 4.1.4 Monitoring data comprises manual dips and logger data, presented in ES Appendix 9.3 Ground investigation factual report (Document Reference 6.4). The hydrographs for each monitoring well are presented in Appendix B of this document and discussed in section 5. Logger data provides a high frequency of data recording that allows correlation with rainfall/recharge events and provides a reflection of groundwater responses. 4.1.5 Spring and surface water monitoring commenced in August 2020 at the tributary of Norman’s Brook, the unnamed tributary to River Churn and the unnamed tributary to River Frome, which are the three groundwater fed subcatchments that drain from the study area. The monitoring in each subcatchment comprises of a fixed logging station, which also has manual measurements for QA and calibration purposes. Each tributary has a second surface water monitoring location which is a manual monitoring location. Each tributary also has manual measurements at selected springs (ES Figure 13.15 Water environment monitoring locations (Document Reference 6.3)). 4.1.6 At the tributary of Norman’s Brook the dataset for the recording station SW2 is supplemented by a downstream manual monitoring station SW1 and at upstream springs GW1 (81), GW2 (81), GW3 (G231) and GW4 (confluence of 66 and 67) where manual measurement is taken (water feature survey ID given in brackets). 4.1.7 At the unnamed tributary of the River Frome the dataset is supplemented by an upstream manual monitoring station (SW3) and upstream springs GW5 (G25) and GW6 (111) where manual measurements are taken. 4.1.8 At the unnamed tributary of the River Churn the dataset is supplemented by an upstream manual monitoring station (SW5) and springs GW7 (downstream of G99) and GW8 (G4) where manual measurements are taken. 4.1.9 The logging surface water monitoring stations provide a record of the stream flows which provide the cumulative groundwater discharges and baseflow contribution for each subcatchment. Further details about the surface water monitoring programme are presented in ES Chapter 13 Road Drainage and Water Environment (Document Reference 6.3). 4.2 Aquifer testing 4.2.1 Water quality samples have been collected as part of this programme and the results of these are presented in Appendix C of this document and discussed in section 6. 4.2.2 Hydraulic testing results from the monitoring wells are included in ES Appendix 9.3 Ground investigation factual report (Document Reference 6.4) and are discussed in section 7.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE xviii A417 Missing Link | HE551505 Highways England 4.3 Quality assurance 4.3.1 Review and validation of the monitoring data has been completed in consultation with the monitoring contractor. Auto-sampling events are presented on the hydrographs included in Appendix B of this document and are labelled on the contractor’s hydrographs provided in ES Appendix 9.3 Ground investigation factual report (Document Reference 6.4). 4.3.2 One hydrograph shows an uncharacteristic response to recharge, CP 223. An unexplained recharge response was recorded between February 2020 to April 2020, where the recorded groundwater level is increasing over this time as rainfall rates are decreasing. The logger and manual dips recorded over this time and until October 2020 are consistent, indicating the measurements are accurate. However, the response is considered unusual and may be due to unique conditions at this location. 4.3.3 Manual dips recorded at or below the response zone base have been excluded from the summaries provided in Section 5 and hydrographs in Appendix B. 5 Groundwater level monitoring results

5.1 Superficial Aquifer - Mass movement deposits, Crickley Hill

Overview 5.1.1 The locations of groundwater monitoring wells are shown in ES Figure 13.9 Groundwater monitoring locations (Document Reference 6.3). A summary of the response zone strata is presented in Appendix A and the range of observed groundwater levels is presented in Table 5.1. 5.1.2 The hydrographs for groundwater monitoring within the mass movement deposits of Crickley Hill are presented in Appendix B, Figure B-1 to Figure B-7. Within the Crickley Hill area there are a total of 16 groundwater monitoring locations within the mass movement deposits. Monitoring at these locations has progressively started since the 17 May 2019. The distribution of monitoring locations includes:  Four between Ch 0+500 and Ch 1+000 in the lower slopes of Crickley Hill  Nine between Ch 1+000 and Ch 1+400 in the mid slopes of Crickley Hill  Two between Ch 1+400 and Ch 1+700 in the upper slopes of Crickley Hill Table 5.1 Summary of groundwater monitoring in superficial mass movement deposits at Crickley Hill

Location Formation No. GWL range (average) GWL range (average) Observed dips (mbgl) (mAOD) range (m) Ch 0+500 to Ch 1+000 (southern side of A417) – Lower Crickley Hill CP 102 Mass movement Data 0.15 - 2.19 125.36 - 127.40 2.04 deposits - silty logger (1.20) (126.35) clay CP 104A Mass movement Data 8.52 - 10.76 137.24 - 139.48 2.24 deposits - sand logger (10.06) (137.94) CP 200 Mass movement Data 2.49 - 3.16 126.54 - 127.21 0.67 deposits - sand logger (2.90) (126.8) and gravel CP 202 Mass movement Data -0.24 - 0.97 134.73 - 135.94 1.22 deposits - clay logger] (0.37) (135.33)

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE xix A417 Missing Link | HE551505 Highways England

Location Formation No. GWL range (average) GWL range (average) Observed dips (mbgl) (mAOD) range (m) Ch 1+000 to Ch 1+400 (northern side of A417) – Mid Crickley Hill CP 210 (s) Mass movement 38 1.78 [1] 172.52 [1] - deposits – silty clay CP 211 Mass movement 37 Dry Dry - deposits - gravel CP 215 (s) Mass movement 42 1.51 - 2.10 183.95 - 184.54 0.59 deposits - clay (1.81) (184.24) DS/RC 205 Mass movement 39 7.05 - 8.90 158.25 - 160.10 1.85 deposits - (8.33) (158.82) gravelly clay Ch 1+000 to Ch 1+400 (southern side of A417) - Mid Crickley Hill CP 105 Mass movement 48 1.97 - 5.05 164.85 - 167.93 3.08 deposits - silt (3.65) (166.25) and gravel CP 206 Mass movement Data 1.76 - 5.74 157.11 - 161.09 3.97 deposits - clay logger (3.97) (158.88) CP 216 Mass movement Data 0.21 - 1.89 [1] 171.61 - 173.29 [1] 1.69 deposits - logger (1.22) (172.28) gravelly silty clay CP 204 (s) Mass movement 20 7.80 - 9.80 [1] 169.10 - 171.10 [1] 2.00 deposits - clay (8.74) (170.16) CP 212 (s) Mass movement Data 7.39 - 8.80 182.80 - 184.21 1.40 deposits - gravel logger (8.39) (183.21) and clay Ch 1+400 to Ch 1+700 (southern side of A417) - Upper Crickley Hill DS/RC/OH 107 Mass movement 41 1.95 - 2.77 189.13 - 189.95 0.82 deposits - sands (2.07) (189.83) and gravels Ch 1+400 to Ch 1+700 (northern side of A417) - Upper Crickley Hill DS/RC 229 Mass movement 23 5.20 - 5.94 194.51 - 195.25 0.74 deposits – silt (5.63) (194.82) Note: 1. Groundwater level falls below response zone base

Ch 0+500 to Ch 1+000 – Lower Crickley Hill 5.1.3 The groundwater monitoring locations in the lower slopes of Crickley Hill are located on the southern side of the A417 next to tributary of Norman’s Brook. The hydrographs for these locations are presented on Figure B-1 (Appendix B). Within this domain, relatively shallow (< 3.2 mbgl) groundwater levels were recorded in CP 102, CP 200 and CP 202. Deeper groundwater levels were recorded in CP 104A (average 10 mbgl). 5.1.4 The shallow wells CP 102, CP 200 and CP 202 are located within silty and clayey mass movement deposits. The hydrographs show a gradual seasonal response at each location. CP 102 is responsive to larger rainfall events, whilst CP 200 and CP 202 show minimal response to rainfall. 5.1.5 CP 104A monitors the groundwater level within a confined or semi-confined sand layer. The groundwater response at CP 104A also shows a seasonal response (up to 3m), indicating that the sand layer is connected to recharge.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE xx A417 Missing Link | HE551505 Highways England

Ch 1+000 to Ch 1+400 (northern side of A417) – Mid Crickley Hill 5.1.6 In the mid-slope region of Crickley Hill between Ch 1+000 and Ch 1+400, there are four groundwater monitoring locations. The hydrographs for these locations are presented on Figure B-2 and Figure B-3 (Appendix B). Relatively shallow groundwater levels (< 2.1 mbgl) were recorded in CP 215(s), whilst other shallower response zones in CP 210(s) (2.5 to 5.5 mbgl) and CP 211 (1.1 to 3.3 mbgl) are mostly dry. Deeper groundwater levels were recorded in DS/RC 205 up to 8.9 mbgl. 5.1.7 CP 210(s) and CP211 are both monitoring within shallow, coarse-grained mass movement deposits. The monitoring to date indicates these deposits are mostly unsaturated. This may be limited by the frequency of recordings and the rate groundwater levels may respond to rainfall. 5.1.8 CP 215 (s) is monitoring within a bed of clay dominated mass movement deposits. The location shows a slight response to rainfall, however there is no distinct seasonality to this location. 5.1.9 DS/RC 205 is monitoring within gravelly clay mass movement deposits at depth. A seasonal variation (up to 1.9m) was observed at this location and water levels are responsive to larger rainfall events during wetter months.

Ch 1+000 to Ch 1+400 (southern side of A417) - Mid Crickley Hill 5.1.10 Between Ch 1+000 and Ch 1+400 on the southern side of the A417, there are five groundwater monitoring locations. The hydrographs for these locations are presented on Figure B-4 and Figure B-5 (Appendix B). Similar to other areas of Crickley Hill, relatively shallow groundwater levels were recorded (0.2 to 5.3 mbgl) near Norman’s Brook. Deeper groundwater levels, between 7.3 and 11.6 mbgl, were recorded at CP 212(s) which is located approximately halfway up the southern escarpment slope. 5.1.11 CP 105, CP 206 and CP 216 are located on the southern side of Norman’s Brook. CP 105 is monitoring within silt and gravel deposits and CP 206 is monitoring within clay. CP105 and CP206 show a similarly large seasonal variation (between 3.1 m and 4 m) in groundwater levels. Both locations are highly responsive to rainfall, particularly over wetter months, indicating they receive direct recharge. The response zone for CP 216 is within gravelly silty clay material and shows comparatively smaller seasonal variation and responsiveness to rainfall. 5.1.12 CP 204(s) is located mid-way up the Crickley Hill escarpment and has response zone within clay. Manual dips taken at this location have been largely dry, apart from July 2020. The variation in readings suggests the location may respond rapidly to rainfall events. 5.1.13 CP 212(s) is monitoring within gravel and clay mass movement deposits. The monitoring results show seasonal variation in water levels which is responsive to rainfall over winter months. Over drier, summer months the groundwater level is relatively consistent at approximately 183 mAOD within the gravels.

Ch 1+400 to Ch 1+700 (southern side of A417) - Upper Crickley Hill 5.1.14 Within the upper slopes of Crickley Hill on the southern side of A417 there is one monitoring location within the mass movement deposits, DS/RC/OH 107, which is monitoring within sands and gravels. The hydrograph for this location is presented on Figure B-6 (Appendix B). No seasonal variation or responsiveness to rainfall

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE xxi A417 Missing Link | HE551505 Highways England

was observed at this location, indicating the location doesn’t receive direct recharge.

Ch 1+400 to Ch 1+700 (northern side of A417) - Upper Crickley Hill 5.1.15 Within the upper slopes of Crickley Hill on the northern side of A417 there is one monitoring location within silt mass movement deposits, DS/RC 229. The hydrograph for this location is presented on Figure B-7 (Appendix B). Monitoring at this location commenced in March 2020, the monitoring suggests there is a seasonal variation at this location, however responsiveness to rainfall was not observed. 5.2 Great Oolite Group - Limestones

Overview 5.2.1 The locations of groundwater monitoring wells are shown in ES Figure 13.9 Groundwater monitoring locations (Document Reference 6.3). A summary of the response zone strata is presented in Appendix A and the range of observed groundwater levels is presented in Table 5.2. 5.2.2 The hydrographs for groundwater monitoring within the Group Oolite Group limestones are presented in Appendix B, Figure B-8 to Figure B-11. Across the scheme there are 7 monitoring locations within the Great Oolite Group limestones. Monitoring at these locations has progressively started since the 3rd October 2019. The distribution of monitoring locations includes:  three between Ch 3+000 and Ch 3+500 at Shab Hill junction  three between Ch 3+500 and Ch 5+000 between Shab Hill junction and Cowley junction  one near the Bushley Muzzard SSSI 5.2.3 A summary of the response zone strata is presented in Appendix A and the range of observed groundwater levels is presented in Table 10. Table 5.2 Summary of groundwater monitoring in Great Oolite Group limestones

Location Formation No. GWL range (average) GWL range (average) Observed dips (mbgl) (mAOD) range (m) Ch 3+000 to Ch 3+500 - Shab Hill junction OH 413 Great Oolite 42 Dry [1] Dry [1] - (Limestone) DS/RC 311 Great Oolite 22 39.04 - 39.40 [1] 215.80 - 216.16 [1] 0.36 (Limestone) (39.30) (215.90) DS/RC 312 Great Oolite 18 12.71 - 12.96 269.19 - 269.44 0.25 (Limestone) (12.87) (269.28) Ch 3+500 to Ch 5+000 - Shab Hill junction to Cowley junction DS/RC 218 Great Oolite 42 1.50 - 8.91 276.74 - 284.15 7.41 (Interbedded (6.14) (279.51) limestone, mudstone and siltstone) DS/RC 317 Great Oolite Data 0.56 - 3.92 270.98 - 274.34 3.36 (Limestone) logger (3.11) (271.79)

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE xxii A417 Missing Link | HE551505 Highways England

Location Formation No. GWL range (average) GWL range (average) Observed dips (mbgl) (mAOD) range (m) DS/RC 401 Great Oolite 31 5.80 - 8.05 [1] 265.05 - 267.30 [1] 2.58 (Interbedded (7.27) (266.44) limestone and mudstone) Bushley Muzzard SSSI DS/RC 420 Great Oolite N/A[1] 1.54 - 3.50 [1] 274.09 - 275.56 [1] 1.47 (Interbedded (2.20) (275.01) limestone, mudstone and sandstone) Note: 1. Groundwater level falls below response zone base

Ch 3+000 to Ch 3+500 - Shab Hill junction 5.2.4 Three monitoring locations are located at Shab Hill junction within the Great Oolite Group limestones, OH 413, DS/RC 311 and DS/RC 312. The response zones for OH 413 and DS/RC 312 extend to the base of the limestones, whilst DS/RC 311 terminates above the base of the limestones. The hydrographs for these locations are presented on Figure B-8 and Figure B-9 (Appendix B). 5.2.5 The monitoring results indicate the aquifer has a deep unsaturated zone. The water levels in DS/RC 312 are consistently between 1.6 and 1.8m above the base of the aquifer. This observation is in line with the expectation that the Great Oolite Group at Shab Hill junction is a well drained limestone, unlike the section south to Cowley junction which is largely mudstone. 5.2.6 DS/RC 311 shows a seasonal response where relatively steady water levels were recorded between April 2020 to June 2020, then the location was dry up until October 2020. Groundwater levels at this location do not show responsiveness to rainfall and may be controlled by the adjacent fault acting as a groundwater flow path.

Ch 3+500 to Ch 5+000 - Shab Hill junction to Cowley junction 5.2.7 Between Ch 3+500 and Ch 5+000 there are 3 monitoring locations: DS/RC 218, DS/RC 317 and DS/RC 401. These installations are monitoring within the transition zone of the Great Oolite Group which includes mudstones with interbedded limestone. The hydrographs for these locations are presented in Figure B-10 (Appendix B). 5.2.8 A large seasonal variation was observed in DS/RC 218. Over the wetter, winter months the location was responsive to rainfall indicating the location receives direct recharge most likely by fracture flow. Over summer month the recorded groundwater level was consistently within the deepest limestone bed in the formation and not responsive to rainfall. 5.2.9 Groundwater levels within DS/RC 317 were also responsive to rainfall events over wetter, winter months, but unresponsive over summer months. DS/RC 401 showed a seasonal response in groundwater levels and minor response to rainfall, indicating the location is more likely to receive indirect recharge.

Bushley Muzzard SSSI 5.2.10 DS/RC 420 is located north-west of the Bushley Muzzard SSSI and is monitoring within shallow, interbedded limestones and mudstones above the Fuller’s Earth

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE xxiii A417 Missing Link | HE551505 Highways England

Formation. The hydrograph for this location is presented on Figure B-11 (Appendix B). A seasonal response was observed where groundwater levels were responsive to rainfall events over winter months. Over summer months the aquifer is largely unsaturated and isn’t responsive to rainfall events. 5.3 Great Oolite Group – Fuller’s Earth Formation

Overview 5.3.1 There are three groundwater monitoring locations within the Fuller’s Earth Formation. The maps showing the locations of these wells are presented in ES Figure 13.9 Groundwater monitoring locations (Document Reference 6.3) and the hydrographs for these groundwater monitoring locations are presented in Appendix B, Figure B-12 to Figure B-14. Monitoring at the location commenced on the 4th February 2019. The groundwater monitoring network for the Fuller’s Earth Formation may be divided into the following specific areas:  two between Ch 3+500 and Ch 5+000 between Shab Hill junction and Cowley junction  one at Ermin Way, west of the Bushley Muzzard SSSI 5.3.2 Table 5.3 provides a summary of the range of groundwater levels recorded, the number of manual measurements and whether a water level data logger was used. A summary of the response zone interval is presented in Appendix A, Table A.1. 5.3.3 The following sections provide a description of the groundwater level data recorded for each area and provides an interpretation of these fluctuations based on seasonal recharge and responses to rainfall events. Table 5.3 Summary of groundwater monitoring in Fuller’s Earth Formation

Location Formation No. GWL range GWL range Observed range dips (average) (mbgl) (average) (mAOD) (m) Ch 3+500 to Ch 5+000 - Shab Hill junction to Cowley junction DS/RC 220 Fuller's Earth Data 1.27 - 3.70 275.15 - 277.58 2.43 Formation logger (2.19) (276.66) (transition) DS/RC 403 Fuller's Earth 25 3.40 - 5.36 242.29 - 244.25 1.96 Formation (4.57) (243.08) (transition) Ermin Way OH 416 Fuller's Earth Data 1.48 - 3.55 283.3 - 285.37 2.07 Formation logger (2.31) (284.54) (weathered)

Ch 3+500 to Ch 5+000 - Shab Hill junction to Cowley junction 5.3.4 The response zones in DS/RC 220 and DS/RC 403 are within the Fuller’s Earth Formation transition zone, mostly comprising mudstones with occasional limestone beds. The hydrographs for these locations are presented on Figure B-12 and Figure B-13 (Appendix B). 5.3.5 A seasonal response was observed at DS/RC 220 where groundwater levels were also responsive to larger rainfall events, indicating the location likely receives indirect recharge. Over the summer period the groundwater levels showed little to no response to rainfall events. Monitoring at DS/RC 403

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE xxiv A417 Missing Link | HE551505 Highways England

commenced in March 2020 and shows little response to rainfall events over the following months, indicating the location also likely receives indirect recharge.

Ermin Way 5.3.6 One groundwater monitoring borehole (OH 416) is located adjacent to Ermin Way (Roman Road). The hydrograph for this location is presented on Figure B-14 (Appendix B). The location shows a seasonal response, where groundwater levels are higher over winter months and only show minor, rapid fluctuations in levels over this period due to rainfall. Over summer months the location is responsive to rainfall events, where these fluctuations are small and rapid, indicating the location receives direct recharge. 5.4 Inferior Oolite Group

Overview 5.4.1 There are a total of 23 groundwater monitoring locations within the Inferior Oolite Group limestones. The maps showing the locations of these wells are presented in ES Figure 13.9 Groundwater monitoring locations (Document Reference 6.3) and the hydrographs for these groundwater monitoring locations are presented in Appendix B, Figure B-15 to Figure B-22. Monitoring at these locations has progressively started since the 5 February 2019. The groundwater monitoring network for the Inferior Oolite Group may be divided into the following specific areas:  ten between Ch 1+700 and Ch 2+250 at Air Balloon  one between Ch 2+250 and Ch 2+270 at Air Balloon  two near Barrow Wake  one near the proposed B4070  five between Ch 3+000 and Ch 3+500 at Shab Hill junction  two between Ch 3+500 and Ch 4+575 between Shab Hill junction and Cowley junction  one at Ermin Way 5.4.2 Table 5.4 provides a summary the range of groundwater levels recorded, the number of manual measurements and whether a water level data logger was used. A summary of the response zone interval is presented in Appendix A, Table A.1. 5.4.3 The following sections provide a description of the groundwater level data recorded for each area and provides an interpretation of these fluctuations based on seasonal recharge and responses to rainfall events. Table 5.4 Summary of groundwater monitoring in Inferior Oolite Group

Location Formation No. GWL range GWL range Observed dips (average) (mbgl) (average) (mAOD) range (m) Ch 1+700 to Ch 2+250 - cutting DS/RC 109 Inferior Oolite 33 Dry Dry - (Limestone) DS/RC 301 Inferior Oolite 33 26.13 - 28.72 [1] 205.48 - 208.07 [1] 2.59 (Limestone, Bridport (26.87) (207.33) Sand) DS/RC 302 Inferior Oolite 28 23.95 - 25.80 [1] 208.70 - 210.55 [1] 1.85 (Limestone) (25.20) (209.30)

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE xxv A417 Missing Link | HE551505 Highways England

Location Formation No. GWL range GWL range Observed dips (average) (mbgl) (average) (mAOD) range (m) DS/RC 319 Inferior Oolite 30 19.31 - 20.00 [1] 211.85 - 212.29 [1] 1.09 (Limestone) (19.74) (212.16) DS/RC 325 Inferior Oolite 25 21.81 - 24.36 208.89 - 211.44 2.55 (Limestone) (23.07) (210.18) DS/RC 406 Inferior Oolite (Birdlip Data 27.77 - 31.98 206.67 - 210.88 4.20 Limestone) logger (31.03) (207.62) DS/RC 418 Inferior Oolite 27 55.96 - 57.48 [1] 214.77 - 216.29 [1] 1.52 (Limestone) (56.55) (215.70) DS/RC/OH 110 Inferior Oolite 27 29.52 - 33.50 [1] 206.50 - 210.48 [1] 3.98 (Limestone) (31.14) (208.86) OH 405 Inferior Oolite 43 Dry Dry - (Limestone) OH 407 Inferior Oolite 37 Dry Dry - (Limestone) Ch 2+250 to Ch 2+750 - cutting DS/RC/OH 308 Inferior Oolite 25 54.25 - 57.45 [1] 213.9 - 217.10 [1] 3.20 (Limestone) (55.85) (215.5) Barrow Wake DS/RC 404 Inferior Oolite (Birdlip 45 33.28 - 33.45 [1] 235.55 - 235.72 [1] 0.17 Limestone) (33.4) (235.6) DS/RC/OH 414 Inferior Oolite 40 55.03 - 58.94 [1] 215.66 - 219.57 [1] 3.91 (Limestone) (57.46) (217.14) B4070 realignment DS/RC 314 Inferior Oolite 43 14.85 - 14.97 [1] 278.15 - 278.25 [1] 0.12 (Limestone) (14.90) (278.20) Ch 3+000 to Ch 3+500 - Shab Hill junction DS/RC 310 Inferior Oolite 20 Dry Dry - (Limestone) DS/RC 315 Inferior Oolite 25 42.75 - 48.70 198.20 - 204.15 5.95 (Limestone) (45.11) (201.79) DS/RC 315A Inferior Oolite 15 46.55 - 51.24 [1] 195.76 - 200.45 [1] 4.69 (Limestone) (50.2) (196.8) DS/RC/OH 412 Inferior Oolite 39 28.20 - 28.95 [1] 221.35 - 222.10 [1] 0.75 (Limestone) (28.81) (221.49) OH 411 Inferior Oolite 13 79.75 - 83.98 [1] 196.52 - 200.75 [1] 4.23 (Limestone) (82.18) (198.32) Ch 3+500 to Ch 4+575 - Shab Hill junction to Cowley junction DS/RC/OH 400 Inferior Oolite 35 70.72 - 71.89 [1] 196.06 - 197.23 [1] 1.17 (Limestone) (71.33) (196.62) OH 417 Inferior Oolite 41 68.00 - 70.80 [1] 204.85 - 207.65 [1] 2.80 (Limestone) (69.79) (205.86) Ermin Way DS/RC 415 Inferior Oolite 43 Dry Dry - (Salperton, Aston and Birdlip Limestone Formations) Note: 2. Groundwater level falls below response zone base

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE xxvi A417 Missing Link | HE551505 Highways England

Cutting Ch1+700 to Ch2+250 5.4.4 A total of 12 groundwater monitoring boreholes are located at Air Balloon. Most of the monitoring response zones extend to the base of the Inferior Oolite Group except for DS/RC 325, DS/RC 408, OH 405 and OH 407, which terminate above the base. The hydrographs for these locations are presented on Figure B-15 (Appendix B). Monitoring shows that there is a deep unsaturated zone in this area, where water levels are up to 6m above the aquifer base. 5.4.5 Four locations were consistently dipped ‘dry’ over the monitoring period, including DS/RC 109, OH 405 and OH 407. DS/RC 109 is located near the crest of the Cotswold escarpment and includes voids near the base of the response zone, which in combination results in ‘dry’ readings. Groundwater flow is likely to be ‘flashy’ at this location, meaning the groundwater levels change rapidly as flow travels through the aquifer. 5.4.6 A seasonal response was observed in the remaining monitoring locations. DS/RC 301, DS/RC 319 and DS/RC 418 recorded steady groundwater levels over the winter period indicating they are unlikely to receive direct recharge. DS/RC 302, DS/RC 319 and DS/RC 406 showed flashy responses over the wetter, winter period where the amplitude and response pattern is similar across the locations indicating they may be connected by a flow path that receives direct recharge. 5.4.7 Over drier summer months, groundwater levels were only recorded in DS/RC 325, DS/RC 406, DS/RC 408 and DS/RC/OH 110, located on the eastern side of the Shab Hill fault where the top of the underlying Lias Group is lower than surrounding areas.

Cutting Ch 2+250 to Ch 2+800 5.4.8 Within the eastern extent of the cutting there is one monitoring locations available, DS/RC/OH 308. The hydrograph for this location is presented on Figure B-16 (Appendix B). The location is mostly dry throughout the year with seasonal, flashy readings recorded during wetter winter months. It is likely this location receives direct recharge and remains largely dry as the top of the Lias Group is higher in this location compared to the western end of the proposed cutting between Ch 1+700 and Ch 2+250 allowing the water to drain away.

Barrow Wake 5.4.9 Two groundwater monitoring boreholes, DS/RC 404 and DS/RC/OH 414, are located adjacent to the proposed B4070 realignment. The hydrographs for these locations are presented on Figure B-17 and Figure B-18 (Appendix B). Seasonal groundwater levels were recorded in each monitoring location. At DS/RC 404, located near the crest of the Cotswold escarpment, the location is mostly dry with similar groundwater levels recorded over the winter months at approximately 235.6 mAOD (1.5m above the aquifer base). It’s likely this location receives indirect recharge from the groundwater flowing through the aquifer to the escarpment where it drains. 5.4.10 DS/RC/OH 414 is set further back from the escarpment and adjacent to the Shab Hill Barn fault. Similar to other monitoring locations in the Inferior Oolite Group, there is a deep unsaturated zone and water levels are up to 5.4m above the aquifer base. Over the wetter, winter months DS/RC/OH 414 recorded very rapid and flashy water levels in response to rainfall events indicating the location receives direct recharge.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE xxvii A417 Missing Link | HE551505 Highways England

B4070 realignment 5.4.11 One groundwater monitoring borehole, DS/RC 314, is located adjacent to the proposed B4070 realignment and the base of the aquifer is at an unknown depth below the response zone. The hydrograph for this location is presented on Figure B-19 (Appendix B). Water levels recorded are very close to the base of the response zone and may be indicative of water pooling in the borehole end cap.

Ch 3+000 to Ch 3+500 - Shab Hill junction 5.4.12 Five groundwater monitoring boreholes, DS/RC 310, DS/RC 315, DS/RC 315A, DS/RC/OH 412 and OH 411, are located at Shab Hill junction. The hydrographs for these locations are presented on Figure B-20 and Figure B-21 (Appendix B). The monitoring response zones extend to the base of the aquifer with the exception of DS/RC 310 and DS/RC 412. In this area the Inferior Oolite Group is overlain by the Great Oolite Group and superficial head deposits. 5.4.13 A seasonal response was observed in DS/RC 315 and DS/RC 315A, where the results showed a deep, unsaturated zone and groundwater levels up to 10.7 m above the base of the aquifer. Over the wetter, winter months the location had a delayed response to rainfall events and over the summer months the water levels were not responsive to rainfall events and some dry readings were recorded. The location likely receives indirect recharge from the overlying head deposits. 5.4.14 DS/RC/OH 412 shows the water level lies near the base of the aquifer unit and doesn’t respond to rainfall events. Water levels in this location are consistent with a 70° incipient fracture logged at 28.8mbgl, which is likely to be a flow path. 5.4.15 Monitoring at OH 411 commenced in June 2020 and data received up until October 2020 suggests this location has a seasonal groundwater response.

Ch 3+500 to Ch 4+575 - Shab Hill junction to Cowley junction 5.4.16 Two groundwater monitoring boreholes, OH 417 and DS/RC/OH 400, are located adjacent to the proposed cuttings between Shab Hill junction and Cowley junction. The hydrographs for these locations are presented on Figure B-22 (Appendix B). In this area the Inferior Oolite Group is at surface along the valley sides and overlain by the Great Oolite Group along the ridgeline. 5.4.17 The groundwater monitoring record for these boreholes indicates there is a deep, unsaturated zone and water levels are near the base of the aquifer. Water levels are seasonal and ‘dry’ readings were recorded later in the summer months. The water levels were not responsive to rainfall indicating recharge in the area is from indirect sources like leakage from the overlying Great Oolite Group and interflows from where the aquifer is recharged directly.

Ermin Way 5.4.18 One monitoring location, DS/RC 415, is monitoring within the Inferior Oolite Group at Ermin Way (Roman Road), north-west of Bushley Muzzard SSSI. The base of the response zone (49mbgl) is above the base of the aquifer, which was not proved during the ground investigation. Monitoring at this location commence in February 2019 and has consistently dipped dry since indicating there is a deep, unsaturated zone and water levels are likely near the base of the aquifer.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE xxviii A417 Missing Link | HE551505 Highways England 5.5 Lias Group – Bridport Sand Formation

Overview 5.5.1 There is a total of two groundwater monitoring locations within the Bridport Sand Formation. The maps showing the locations of these wells are presented in ES Figure 13.9 Groundwater monitoring locations (Document Reference 6.3) and the hydrographs for these groundwater monitoring locations are presented in Appendix B, Figure B-25 and Figure B-29. Monitoring at these locations has progressively started since the January 2019. The groundwater monitoring network for the Lias Group within Crickley Hill may be divided into the following specific areas:  one at Air Balloon  one at Barrow Wake 5.5.2 Table 5.5 provides a summary the range of groundwater levels recorded, the number of manual measurements and whether a water level data logger was used. A summary of the response zone interval is presented in Appendix A, Table A.1. 5.5.3 The sections below provide a description of the groundwater level data recorded for each area and provides an interpretation of these fluctuations based on seasonal recharge and responses to rainfall events. Table 5.5 Summary of groundwater monitoring in Lias Group – Bridport Sand Formation

Location Formation No. GWL range GWL range Observed range dips (average) (mbgl) (average) (mAOD) (m) Air Balloon DS/RC 408 Lias Group Data 21.23 - 22.77 209.73 - 211.27 1.54 (Bridport Sand) logger (21.82) (210.68) Barrow Wake DS/RC 419 Lias Group Data 35.61 - 39.93 228.97 - 233.29 4.32 (Bridport Sand) logger (38.00) (230.90) Note: 1. Continuous monitoring data available

Air Balloon 5.5.4 One groundwater monitoring well (DS/RC 408) is located within the proposed Air Balloon cutting. The hydrograph for this location is presented on Figure B-23 (Appendix B). In this area the Bridport Sand Formation is overlain by the Inferior Oolite Group. A seasonal response was recorded at this location where groundwater levels were not responsive to rainfall events. The location likely receives recharge from the overlying Inferior Oolite Group.

Barrow Wake 5.5.5 One groundwater monitoring well (DS/RC 419) is located near Barrow Wake. The hydrograph for this location is presented on Figure B-24 (Appendix B). In this area the Bridport Sand Formation has a thin, fractured mudstone bed (0.95 m thick) at the top of the formation which is overlain by the Inferior Oolite Group. A seasonal response was recorded at this location and groundwater levels are responsive to rainfall events, indicating the location has a strong hydraulic connection to the overlying Inferior Oolite Group.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE xxix A417 Missing Link | HE551505 Highways England 5.6 Lias Group – undifferentiated mudstones

Overview 5.6.1 There is a total of eight groundwater monitoring locations within the Lias Group undifferentiated mudstones. The maps showing the locations of these wells are presented in ES Figure 13.9 Groundwater monitoring locations (Document Reference 6.3) and the hydrographs for these groundwater monitoring locations are presented in Appendix B, Figure B-25 to Figure B-28. Monitoring at these locations has progressively started since May 2019. The groundwater monitoring network for the Lias Group within Crickley Hill may be divided into the following specific areas:  Six between Ch 1+000 and Ch 1+400 in the mid-slopes of Crickley Hill  One at Air Balloon  One in the upper slopes of Crickley Hill 5.6.2 Table 5.6 provides a summary the range of groundwater levels recorded, the number of manual measurements and whether a water level data logger was used. A summary of the response zone interval is presented in Appendix A, Table A.1. 5.6.3 The sections below provide a description of the groundwater level data recorded for each area and provides an interpretation of these fluctuations based on seasonal recharge and responses to rainfall events. Table 5.6 Summary of groundwater monitoring in Lias Group undifferentiated mudstones

Location Formation No. GWL range GWL range Observed dips (average) (mbgl) (average) (mAOD) range (m) Ch 1+000 to Ch 1+400 (northern side of A417) – Mid Crickley Hill CP 210 (d) Lias Group (weathered, 38 13.72 - 16.40 157.90 - 160.58 2.68 mudstone) (15.33) (158.97) CP 215 (d) Lias Group (weathered 47 12.85 - 15.38 170.67 - 173.20 2.53 CLAY) (14.08) (171.97) Ch 1+000 to Ch 1+400 (southern side of A417) – Mid Crickley Hill CP 106 Lias Group (mudstone) 35 14.98 - 16.39 169.86 - 171.27 1.41 (15.84) (170.41) CP 204 (d) Lias Group (weathered 17 10.06 - 12.70 166.20 - 168.84 2.64 clay) (11.88) (167.02) CP 212 (d) Lias Group (mudstone) Data 17.76 - 19.59 172.01 - 173.84 1.83 logger (18.52) (173.08) CP 223 Lias Group (mudstone/ Data 19.58 - 22.27 157.46 - 162.44 4.98 sandstone) logger (21.42) (158.33) Ch 1+400 to Ch 1+700 (southern side of A417) - upper Crickley Hill DS/RC 108 Lias Group (weathered 48 1.76 - 3.79 189.81 - 191.84 2.03 sandy silty CLAY, (2.48) (191.12) weathered limestone) Air Balloon DS/RC/OH 304 Lias Group (mudstone) 26 21.50 - 24.64 207.16 - 210.30 3.14 (23.32) (208.48)

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE xxx A417 Missing Link | HE551505 Highways England

Location Formation No. GWL range GWL range Observed dips (average) (mbgl) (average) (mAOD) range (m) Southern Crest of Crickley Hill DS/RC 224 Lias Group (mudstone/ Data 19.87 - 35.73 [1] 191.12 - 206.98 [1] 15.86 limestone) logger (22.44) (204.41) Note: 2. Groundwater level falls below response zone base

Ch 1+000 to Ch1+400 (northern side of A417) – Mid Crickley Hill 5.6.4 Two groundwater monitoring boreholes, CP 210(d) and CP 215(d), are located on the northern side of the A417, in the mid-slopes of Crickley Hill. The hydrographs for these locations are presented on Figure B-25 and Figure B-26 (Appendix B). In this area the Lias Group is overlain by superficial mass movement deposits. 5.6.5 A seasonal response was observed in both monitoring location. Over the winter months, a delayed response to rainfall was recorded indicated the locations receive indirect recharge. Over the drier, summer months the groundwater levels were only responsive to large rainfall events.

Ch 1+000 to Ch 1+400 (southern side of A417) – Mid Crickley Hill 5.6.6 Three groundwater monitoring boreholes, CP 204(d), CP 212(d) and CP 223, are located on the northern side of the A417, in the mid-slopes of Crickley Hill. The hydrographs for these locations are presented on Figure B-27 (Appendix B). In this area the Lias Group is overlain by superficial mass movement deposits. 5.6.7 A seasonal response was observed at the monitoring boreholes. Logger data at CP 204(d), CP 212(d) and CP 223 showed small, rapid fluctuations to rainfall inputs.

Air Balloon 5.6.8 One groundwater monitoring location within the Lias Group is present at Air Balloon, DS/RC/OH 304. The hydrograph for this location is presented on Figure B-28 (Appendix B). Monitoring commenced at this location in March 2020, which indicate the location is likely to have seasonal groundwater levels that aren’t responsive to rainfall events. This shows the location receives indirect recharge from the overlying Inferior Oolite Group.

Southern Crest of Crickley Hill 5.6.9 One groundwater monitoring borehole, DS/RC 224, is located near the southern crest of the Cotswold escarpment. The hydrograph for this location is presented on Figure B-29 (Appendix B). In this area the Lias Group is overlain by superficial mass movement deposits. 5.6.10 The groundwater monitoring record for this borehole has been affected by a slow response in water levels following installation and sampling events. The water table responds to rainfall events, however seasonal variation is masked by the changes in water level due to sampling. 5.7 Hydraulic gradient and groundwater flow

Crickley Hill 5.7.1 Within the Crickley Hill area, groundwater flow paths in the mass movement deposits and Lias Group typically follow the topographical slopes and generally

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE xxxi A417 Missing Link | HE551505 Highways England

flow towards surface water features such as the tributary of Norman’s Brook and the unnamed tributaries that flow into this watercourse. To the south of the Norman’s Brook tributary the hydraulic gradient is generally towards the north and north west. Conversely, to the north of the Norman’s Brook tributary the hydraulic gradient is to the south and south west.

Air Balloon 5.7.2 The Cotswold escarpment forms a groundwater divide between the River Severn catchment and the River Thames catchment (to the west and south-east of the divide respectively). This divide is set back from the escarpment crest and is likely to cause divergent flow to the west and east within the Inferior Oolite aquifer near Air Balloon. At present there is a lack of groundwater monitoring data to confirm where this divergence is occurring. 5.7.3 Based on the monitoring data available, groundwater within the Inferior Oolite Group generally drains towards the Cotswold escarpment crest. The Existing A417 cutting through Air Balloon creates a local drainage point in the aquifer.

Shab Hill junction 5.7.4 Groundwater flow within the Great Oolite Group and Inferior Oolite Group in the Shab Hill junction area is likely to be heavily influenced by the three faults interpreted across the area. Generally, groundwater flow from the junction is likely to be towards the east into the Churn headwaters. The groundwater divide is likely to be west of Shab Hill Junction, where groundwater flows towards the Cotswold escarpment.

Shab Hill junction to Cowley junction 5.7.5 South of Shab Hill junction, towards Cowley junction, the groundwater divide in the overlying Great Oolite Group likely runs along the ridgeline. As a result, divergent flows to the south-west and south-east are likely in the Great Oolite limestone aquifer in this area. Incised valleys in this area are likely to induce locally steeper groundwater gradients within the Great Oolite Group. In the underlying Inferior Oolite Group groundwater flows are towards the south east. 5.8 Hydraulic relationships between aquifer units 5.8.1 Faults are providing some groundwater flow pathways between the same bedrock aquifers in the region. In Air Balloon similar responses in groundwater levels were recorded either side of the Shab Hill fault, indicating a strong hydraulic connection. This may be a localised area of connectivity across the fault as the fault conditions are likely to vary vertically and along the length. 5.8.2 Additionally, the throw induced by the faults vertically offsets the geological formations either side of the fault. It is anticipated that in the Great Oolite limestone aquifer, the Stockwell fault, Churn Valley fault, Cally Hill fault and Shab Hill Barn fault may facilitate downward leakage into the underlying Inferior Oolite aquifer. As previously discussed, this leakage may be more prominent during wetter periods when there is sufficient saturated zone within the Great Oolite limestone aquifer37. 5.8.3 The Bridport Sand Formation at the top of the Lias Group is assumed to be hydraulically connected to the base of the Inferior Oolite Group aquifer and is recharged via these limestones.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE xxxii A417 Missing Link | HE551505 Highways England

5.8.4 It is possible that thin but potentially laterally extensive beds of limestone within mudstone formations and the Marlstone Rock Formation could also be locally, hydraulically linked to the superficial deposit aquifer. In the Churn and Frome valleys, the superficial deposits may be slowly leaking into the underlying Inferior Oolite limestones at a relatively constant rate. 6 Groundwater quality

6.1.1 During the Phase 1 ground investigation, groundwater samples were taken from the Birdlip Limestone of the Inferior Oolite aquifer (DS/RC 406) and Bridport Sand Formation (DS/RC 419) on the 14th February 2019. Sampling from Phase 2A boreholes has progressively been completed since the 11th November 2019. A summary of the groundwater quality testing results is presented in Appendix C. 6.1.2 The composition of water samples from each geological formation is relatively similar where bicarbonate waters are the most common. Calcium is the dominant cation however some samples had higher concentrations of potassium and sodium. Samples with higher potassium and sodium concentrations were from the mass movement deposits, Inferior Oolite Group and Lias Group mudstone. 6.1.3 Water samples were typically fresh (<1,560 μS/cm), however some slightly saline to moderately saline waters were sampled from Lias Group mudstones and mass movement deposit samples. The highest EC reading was 5,600 μS/cm in DS/RC 224, located at the crest of the Crickley Hill escarpment where the Inferior Oolite Group and Lias Group mudstone are included in the response zone. 6.1.4 Exceedance of UK Drinking Water Standards occurred in the following samples:

2-  Sulphate as SO4 – 392mg/l in CP 104 (mass movement deposits)  Nitrite as NO2 – 1,600μg/l in DS/RC 110 (Inferior Oolite Group), 6,300 to 12,000μg/l in DS/RC 224, 750μg/l in CP 206 (mass movement deposits), 650μg/l in DS/RC 403 (Fuller’s Earth Formation)  Manganese – 27 exceedances primarily from mass movement deposits and Inferior Oolite group samples, where the maximum recorded concentration was 1,300μg/l in CP 206  Sodium – 240mg/l in DS/RC 110 (Inferior Oolite Group), 260 to 270mg/l in DS/RC 224 (Lias Group mudstone and Inferior Oolite Group)  Arsenic – 10.2μg/l in CP 200 (mass movement deposits) 7 Aquifer testing

7.1.1 Aquifer testing was conducted during the Phase 1 and Phase 2A ground investigations to estimate the hydraulic conductivity (K) of selected bedrock formations. A combination of constant head and rising head tests were used depending upon saturated aquifer thickness38. A summary of the testing results is presented in Table 7.1 and test reports are included in ES Appendix 9.3 Ground investigation factual report (Document Reference 6.4). Table 7.1 Summary of field testing results39

Location Test interval Test lithology K (m/s) OH 416 3.0 – 5.0mbgl Weathered Fuller’s Earth 2x10-7 283.85 – 281.85mAOD Formation – Great Oolite Group DS/RC 220 3.0 – 13.0mbgl Fuller’s Earth Formation – Great 1.3 x10-7 275.85 - 265.85mAOD Oolite Group

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE xxxiii A417 Missing Link | HE551505 Highways England

Location Test interval Test lithology K (m/s) DS/RC 404 23.0 – 34.0mbgl Birdlip Limestone Formation - 4.6x10-5 to 7.2x10-5 246.0 – 235.0mAOD Inferior Oolite Group DS/RC 406 20.5 – 35.0mbgl Birdlip Limestone Formation - 2x10-6 218.15 – 203.65mAOD Inferior Oolite Group OH 405 11.0 – 18.0mbgl Inferior Oolite Group 5.7x10-5 228.5 – 221.5mAOD OH 407 6.0 – 15.5mbgl Inferior Oolite Group 4.2x10-5 to 7.0x10-5 225.75 – 216.25mAOD DS/RC 419 36.0 – 42.0mbgl Bridport Sand Formation – Lias 3.2x10-6 232.9 – 226.9mAOD Group DS/RC 408 20.0 – 24.0mbgl Bridport Sand Formation – Lias 1.1x10-5 212.5 – 208.5mAOD Group 7.1.2 A summary published hydraulic conductivity of the bedrock formations in the Cotswold area is presented in Table 7.2. Table 7.2 Summary of published hydraulic conductivities for bedrock in the Cotswolds

Parameter K range (m/s) K suggested mean (m/s) Bridport Sand Formation 8x10-8 – 4x10-6 - Lias Group 1x10-11 – 4x10-6 - Inferior Oolite Group 3x10-11 – 5.8x10-3 1.1x10-9 and 5.8x10-9 Fuller’s Earth Formation 6.9x10-6 2.3x10-7 Great Oolite Group limestone 2.2x10-11 – 2.2x10-5 1.1x10-9 7.1.3 The aquifer properties presented in Table 10 and Table 11 provide an overview of those K values recorded in the study area and the regional context. These data are used in developing the Hydrogeological conceptual model in Section 8 and Potential impacts to groundwater features in Section 10. The limestone formations of the Inferior Oolite Group and the Great Oolite Group have the potential for karst processes to locally increase permeability. The K values presented do not include karst, which has the potential for conduit flow which is of a significantly higher scale. Where karst has the potential to be encountered as part of the proposed road development then this is dealt with specifically on a location by location basis. 8 Groundwater conceptual model

8.1 Overview 8.1.1 Three aquifers and two aquitards have been considered in the development of the groundwater conceptual models. The aquifers include the superficial deposits, the limestones of the Great Oolite Group and the Inferior Oolite Group. The Fuller’s Earth Formation and Lias Group mudstones are low permeability strata that form barriers to flow causing perched groundwater in overlying aquifers. These barriers can influence flow direction but also create ponding where structural controls are present. The groundwater characteristics of the aquifer units are presented below, whilst a summary of the hydrogeological units are presented in Table 8.1. The local groundwater regimes for each section of the proposed road development are presented in Section 8.2.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE xxxiv A417 Missing Link | HE551505 Highways England

Superficial deposits 8.1.2 The superficial deposits comprise mass movement deposits and head deposits which form areas in the lower ground on the western and eastern approaches to the scheme. The mass movement and head deposits are dominantly clay but include sand and gravel lenses, which are locally recharged and often associated with springs and seepages. A number of the springs and seepages are tufa forming. Due to the localised nature of the water occurrence in the mass movement and head deposits it is not possible to develop groundwater contours.

Inferior Oolite Group 8.1.3 Groundwater contours have been developed for the Inferior Oolite Group and Great Oolite Group based on seasonal minimum and seasonal maximum groundwater levels. These contours are presented in (all Document Reference 6.3):  ES Figure 13.11 Groundwater contours – Inferior Oolite Group, seasonal minimum levels.  ES Figure 13.12 Groundwater contours – Inferior Oolite Group, seasonal maximum levels.  ES Figure 13.13 Groundwater contours – Great Oolite Group, seasonal minimum levels.  ES Figure 13.14 Groundwater contours – Great Oolite Group, seasonal maximum levels. 8.1.4 The seasonal minimum groundwater levels within the Inferior Oolite Group are presented in ES Figure 13.11 Groundwater contours – Inferior Oolite Group, seasonal minimum levels (Document Reference 6.3). The minimum groundwater levels were recorded over summer months and these show that wide areas of the aquifer are fully drained extensive periods of time. Summer groundwater levels were only recorded at Air Balloon, east of the Shab Hill fault, where the top of the Lias Group is down faulted into a graben structure. In this area the Inferior Oolite Group is lower in elevation and bound by the Lias Group, which causes groundwater levels in the Inferior Oolite Group to pond. 8.1.5 The seasonal maximum groundwater levels of the Inferior Oolite Group area presented in ES Figure 13.12 Groundwater contours – Inferior Oolite Group, seasonal maximum levels (Document Reference 6.3). The maximum groundwater levels were recorded over winter months. Within the Air Balloon area groundwater flow is towards the Existing A417 cutting. Between the Shab Hill junction and Cowley junction, south of the Shab Hill Barn fault groundwater flow is towards the south east. 8.1.6 From the monitoring results it is clear that the Air Balloon area is on the western side of the groundwater divide and the Shab Hill junction to Cowley junction area is on the eastern side of the groundwater divide. The monitoring data indicate that the groundwater divide is likely to vary seasonally.

Great Oolite Group 8.1.7 The Great Oolite Group is crossed by the scheme from Shab Hill junction southwards. In this area the groundwater levels are strongly controlled by faulting with groundwater being isolated to fault blocks and the faults themselves allowing leakage to the Inferior Oolite Group underlying the Fuller’s Earth Formation.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE xxxv A417 Missing Link | HE551505 Highways England

8.1.8 The seasonal minimum groundwater levels within the Great Oolite Group are presented in ES Figure 13.13 Groundwater contours – Great Oolite Group, seasonal minimum levels (Document Reference 6.3). During the summer months groundwater levels were only recorded on the northern side of the Stockwell fault. On the southern side of the Stockwell fault the aquifer is dry. Summer groundwater levels on the northern side of the fault indicate a southward groundwater flow to the fault. 8.1.9 The seasonal maximum levels presented on ES Figure 13.14 Groundwater contours – Great Oolite Group, seasonal maximum levels (Document Reference 6.3) show groundwater flow is largely to the south and south-west and groundwater levels were recorded within the Great Oolite Group underlying Cowley junction as well.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE xxxvi A417 Missing Link | HE551505 Highways England

Table 8.1 Summary of hydrogeological units

Age Group Formation EA designation Description Thickness Hydrogeological properties Quaternary - Cheltenham Secondary A Fine to medium 0m to 2m  Groundwater flow through relatively high permeability, Sand and Gravel aquifer grained sand, intergranular matrix. seams of limestone  Directly recharged. gravel Superficial Alluvium – Largely cohesive 0m to 23m  Variable hydraulic conductivity. Groundwater flow deposits Secondary A material with non- through intergranular matrix. (alluvium, mass aquifer cohesive lenses  Directly recharged. movement Mass movement  Seasonal groundwater levels. deposits and deposits and  head deposits) head deposits – Localised springs/seepages were more permeable no aquifer zones are present such as sand and gravel lenses or designation toppled limestone blocks.  Springs/seepages may be tufa forming if the permeable zones occur in limestone dominant material. Middle Great White Limestone Principal aquifer Limestone aquifer 10m to  Highly fractured. Potential for karst enhancement in Jurassic Oolite Formation with clay beds 20m limestone between Shab Hill Barn fault and Shab Hill Group Hampen Sandy and ooidal fault. Formation limestone aquifer  Iron staining and calcite precipitate on fractures. (168 - with clay and marl  Deep unsaturated zone. 165Ma) beds  Seasonal groundwater levels where aquifer is largely dry during summer months. Througham Interbedded 0m to 10m  Large anisotropy in hydraulic conductivity. Formation calcareous  Where non-limestones dominate such as in the area sandstone, variably south of the Shab Hill Barn fault then unlikely to develop oolitic limestone and karst calcareous  Seasonal groundwater levels. mudstone and siltstone Fuller’s Earth Unproductive Mudstone aquitard 0m to 15m  Sub-horizontal fracturing. Formation aquifer with limestone beds  Relatively low permeability.  Forms an underlying barrier to groundwater flow in the Great Oolite limestones.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE xxxvii A417 Missing Link | HE551505 Highways England

Age Group Formation EA designation Description Thickness Hydrogeological properties Inferior Salperton Principal aquifer Shelly, ooidal 0m to 40m  Fractured with camber developed gulls near the Oolite Limestone limestone aquifer escarpment margins. Group Aston Limestone Shelly, sandy  Potential for karst enhancement. limestone aquifer  Frequent, iron stained voids towards base of aquifer. (175 - Birdlip Limestone Ooidal, sometimes  Deep unsaturated zone. 168Ma) sandy limestone  Seasonal groundwater levels, where aquifer is largely aquifer with sandy dry during summer. clay layers  Directly recharged where outcropping but often capped by Fuller’s Earth Formation which prevents recharge.  Possible indirect recharge by leakage from overlying Great Oolite Group where faulting allows.  Springs occur in the Inferior Oolite Group near Air Balloon associated with the Shab Hill Barn fault. Lower Lias Bridport Sand Principal aquifer Sandy mudstone 0m to 10m  Discontinuous presence within the study area. Jurassic Group Formation (see paragraph and fine grained  Hydraulic connection with base of Inferior Oolite Group. 2.4.7) sandstone – minor  Fracture dominated flow. aquifer (200 -  Seasonal groundwater table. 175Ma)  Indirectly recharged. Whitby Mudstone Mudstone aquitard 12m to  Relatively low permeability. 40 Formation with limestone beds 98m  Potential to form a spring line with overlying Inferior (WMF) at base Oolite Group and Bridport Sand.  Fissured clays in weathered zone. Marlstone Rock Ferruginous, ooidal 0m to 5m41  Fracture dominated flow. Formation (within limestone and  Recharged via leakage from overlying formations. the WMF) sandstone – minor aquifer Dyrham Silty mudstone and 15m to  Relatively impermeable. Formation siltstone aquitard 54m42 Charmouth Secondary Mudstone aquitard 120m to  Relatively impermeable. 43 Mudstone Aquifer with thin beds and 284m  Localised zones of iron staining on fractures. Formation (Undifferentiated) nodules of limestone

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01 | 19/05/21 APPENDIX PAGE xxxviii A417 Missing Link | HE551505 Highways England

8.2 Ch 0+000 to Ch 1+700, Crickley Hill 8.2.1 A summary of the groundwater conceptual model elements within Ch 0+000 and Ch 1+700 are presented in Table 8.2 and Table 8.3. Representative cross sections have been developed for the following chainage are presented in Section A-A’, Section B-B’ and Section C-C’ of ES Figure 13.10 Groundwater conceptual model (Document Reference 6.3). The locations of the cross sections are shown on ES Figure 13.17 Groundwater conceptual model locations (Document Reference 6.3). Table 8.2 Ch 0+000 to Ch 0+500 Crickley Hill approach conceptual model elements

Model element Description Surface topography Low gradient slope towards the west, between approximately 96mAOD and 114mAOD WFD groundwater catchment Severn Vale – Secondary combined Main groundwater bodies Superficial: Localised Cheltenham Sand and Gravel underlie the Existing A417 and are connected to mass movement deposits (up- gradient) between Ch 0+350 and Ch 0+500 Bedrock: Lias Group mudstones aquitard (Charmouth Mudstone Formation and Dyrham Formation) Groundwater flow direction Regional: west, north-west through superficial deposits Localised: towards the tributary of Norman’s Brook Approximate groundwater level at Unknown, to be confirmed from on-going ground investigations scheme Approximate maximum Ground surface. Mapped potential for groundwater flooding to occur groundwater level at surface. Approximate groundwater level Unknown, to be confirmed from on-going ground investigations variation Surface water bodies Tributary of Norman’s Brook runs approximately parallel to the southern side of the Existing A417 between Ch 0+250 to Ch +500 and. The tributary is culverted under the Existing A417 around Ch 0+500, where it flows in a south to north direction and joins Norman’s Brook. Springs There are no springs/seepages in the sand and gravel deposits. Whilst springs/seepages are associated with permeable zones in the mass movement deposits none have been identified in this chainage domain. Recharge Rainfall and superficial deposits upgradient Drainage Road drainage along Existing A417 Table 8.3 Ch 0+500 to Ch 1+700 Crickley Hill escarpment conceptual model elements

Model element Description Surface topography Escarpment slope with areas of hummocky ground, between approximately 114mAOD to 270mAOD. Locally the escarpment creates an embayment that the Existing A417 runs up. The slopes either side of the Existing A417 dip to the south-west (northern side) and the north-west (southern side). WFD groundwater catchment West of Ch 0+850: Severn Vale – Secondary combined

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE xxxix A417 Missing Link | HE551505 Highways England

Model element Description East of Ch 0+850: Severn Vale – Jurassic limestone Cotswold south edge Main groundwater bodies Superficial: Mass movement deposits and localised alluvium associated with the tributary of Norman’s Brook Bedrock: Lias Group mudstones aquitard below superficial deposits (Dyrham Formation and Whitby Mudstone Formation) with a band of Marlstone Rock Formation at approximately 160- 165mAOD and localised Bridport Sand Formation at approximately 212mAOD. Inferior Oolite limestone aquifer exposed at escarpment crest. Groundwater flow direction Regional: West, north-west through superficial deposits Localised: Towards the tributary of Norman’s Brook, generally following the topographical slope Regional faults Shab Hill Barn fault at approximately Ch 1+600 Approximate groundwater level Typically, between 2m and 3.3m below ground level, with some at scheme groundwater levels up to 11m below ground level Approximate maximum Ground surface, due to prevalence of springs/seepages groundwater level Approximate groundwater level Seasonal variations between 0.6m and 4.0m and responsive to variation rainfall inputs Surface water bodies Tributary of Norman’s Brook runs approximately parallel to the southern side of the Existing A417 Springs Springs occur in more permeable units of the cohesive dominated mass movement deposits, such as sand or gravel and remnants of limestone rock topples. Mass movement deposit springs in the valley floor will be perennial whilst those higher in valley sides are more likely to be seasonal. A collection of springs (springs 16, 17, 18 and 19) occur near the base of the Inferior Oolite limestone where the Shab Hill Barn fault cross cuts the escarpment. These limestone springs are seasonal and based on the groundwater levels recorded locally will have a flashy response to storm events. A modified spring, S01 lies on the northern side of the Existing A417 as part of a drainage trench that cuts into the Bridport Sand Formation. This cut and the modified spring will locally manage groundwater by lowering the water table to the base of the trench. Recharge Rainfall and groundwater draining from Inferior Oolite limestone and Bridport Sand Formation upgradient Drainage Road drainage along Existing A417, which may locally lower groundwater levels

8.3 Ch 1+700 to Ch 2+800, Air Balloon 8.3.1 A summary of the conceptual groundwater model elements within Ch 1+700 and Ch 2+800 is presented in Table 3-22. Representative cross sections have been developed for the following chainage are presented in Section D-D’ and Section E-E’ of ES Figure 13.10 Groundwater conceptual model (Document Reference 6.3). The locations of the cross sections are shown on ES Figure 13.17 Groundwater conceptual model locations (Document Reference 6.3).

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE xl A417 Missing Link | HE551505 Highways England

Table 8.4 Ch 1+700 to Ch 2+800 Air Balloon conceptual model elements

Model element Description Surface topography Moderate slopes (210mAOD to 270mAOD) dipping south-east and north-west towards the current A417 west of Air Balloon roundabout and crest of embayment. From approximately Ch 2+500 the slope gradient decreases and the ground level is approximately 274mAOD. WFD groundwater catchment West of Ch 1+950: Severn Vale – Jurassic limestone Cotswold south edge East of Ch 1+950: Burford Jurassic A groundwater divide exists close to these catchment boundaries Main groundwater bodies Superficial: None Bedrock: Inferior Oolite limestones over Bridport Sand Formation Groundwater flow direction Regional: West within Severn Vale catchment and East within the Burford Jurassic Locally: towards the escarpment edge and towards the Existing A417 cuttings where winter groundwater levels are likely intercepted by the existing road drainage network Approximate groundwater level at Deep unsaturated zone to 210mAOD scheme Approximate maximum 212.3mAOD groundwater level Approximate groundwater level Seasonal groundwater levels (up to 4.2m), largely dry over summer variation months Regional faults Shab Hill fault at approximately Ch 1+925 Surface water bodies Pond 50m northwest of Air Balloon roundabout Springs A collection of limestone springs (springs 16, 17, 18 and 19) occur near the base of the Inferior Oolite limestone where the Shab Hill Barn fault cross cuts the escarpment. These limestone springs are seasonal and based on the groundwater levels recorded locally will have a flashy response to storm events. A modified spring, S01 lies on the northern side of the Existing A417 as part of a drainage trench that cuts into the Bridport Sand Formation. This cut and the modified spring will locally manage groundwater by lowering the water table to the base of the trench. Recharge Rainfall

8.4 Ch 2+800 to Ch 3+500, Shab Hill junction 8.4.1 A summary of the conceptual groundwater model elements within Ch 2+800 and Ch 3+500 is presented in Table 3-23. Representative cross sections have been developed for the following chainage are presented in Section F-F’ and Section G-G’ of ES Figure 13.10 Groundwater conceptual model (Document Reference 6.3). The locations of the cross sections are shown on ES Figure 13.17 Groundwater conceptual model locations (Document Reference 6.3). Table 8.5 Ch 2+800 to Ch 3+500 Shab Hill junction conceptual model elements

Model element Description Surface topography Low gradient slopes between 272mAOD and 280mAOD. A dry valley starts on the western side of the proposed Shab Hill junction and extends and incises to the east, toward the River Churn.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE xli A417 Missing Link | HE551505 Highways England

Model element Description WFD groundwater catchment Burford Jurassic Main groundwater bodies Superficial: head deposits. Bedrock: Great Oolite limestones over Fuller’s Earth Formation, underlain by Inferior Oolite limestone. Groundwater flow direction Regional: South east Locally: draining towards faults and over Fuller’s Earth Formation Approximate groundwater level at 269mAOD at western side of junction and 215.9mAOD in dry scheme valley, within Great Oolite limestone 200mAOD within underlying Inferior Oolite limestone. Approximate maximum Up to 269.4mAOD in Great Oolite limestone groundwater level 222mAOD within underlying Inferior Oolite limestone Approximate groundwater level Deep unsaturated zones in both the Great Oolite Group limestone variation and the Inferior Oolite Group limestone. Regional faults Shab Hill fault at approximately Ch 3+000 Churn Valley fault at Ch 3+200 Shab Hill Barn fault at approximately CH3+450 Surface water bodies Unnamed tributary to River Churn lies to the east of Shab Hill junction Springs Springs/seepages occur east of Shab Hill junction at the base of the Great Oolite Group limestone formations where the underlying Fuller’s Earth Formation forms a barrier to flow and perches groundwater. Recharge Great Oolite Group limestone formations are directly recharged by rainfall. Recharge to the underlying Inferior Oolite limestone is prevented by Fuller’s Earth Formation cap but may be locally recharged where faulting permits.

8.5 Ch 3+500 to Ch 5+760, Shab Hill junction to Cowley junction 8.5.1 A summary of the conceptual groundwater model elements within Ch 3+500 and Ch 5+760 is presented in Table 3-24. Representative cross sections have been developed for the following chainage are presented in Section H-H’ and Section I- I’ of ES Figure 13.10 Groundwater conceptual model (Document Reference 6.3). The locations of the cross sections are shown on ES Figure 13.17 Groundwater conceptual model locations (Document Reference 6.3). Table 8.6 CH3+500 to CH5+760 conceptual model elements

Model element Description Surface topography The scheme roughly follows the ridgeline of rolling, low gradient hills between approximately 260mAOD and 282mAOD. Incised valleys associated with water courses are located to the east and west of the scheme. WFD groundwater catchment The scheme runs approximately along the groundwater divide. East of the scheme: generally, Burford Jurassic West of the scheme: generally, Severn Vale – Jurassic limestone Cotswold edge north Main groundwater bodies Superficial: no aquifer Bedrock: Great Oolite Group over Fuller’s Earth Formation, underlain by Inferior Oolite Group. Great Oolite Group is dominantly mudstone with minor limestone units.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE xlii A417 Missing Link | HE551505 Highways England

Model element Description Groundwater flow direction Regional: West within Severn Vale catchment and East within the Burford Jurassic catchment Approximate groundwater level at From Ch 3+600 to Ch 5+000, decreasing from 279.5mAOD to scheme 267.3mAOD in Great Oolite Group. 200mAOD in underlying Inferior Oolite Group, with deep unsaturated zone Approximate maximum From Ch 3+600 to Ch 4+500, decreasing from 284.5mAOD to groundwater level 273.1mAOD in Great Oolite limestone 207.7mAOD in underlying Inferior Oolite limestone Approximate groundwater level Seasonal groundwater levels, responsive to rainfall, with 2.6 to variation 7.4m variation in Great Oolite Group Seasonal groundwater levels (up to 2.8m), largely dry during summer months in underlying Inferior Oolite Group Regional faults Shab Hill Barn fault at approximately Ch 3+450 Cally Hill fault at approximately Ch 4+000 Stockwell Farm fault at approximately Ch 4+800 Surface water bodies Unnamed tributaries to the River Frome are located on the western side of the scheme and flow towards the south. Tributaries of the River Churn are located on the eastern side of the scheme and flow towards the east Springs Springs/seepages occur in thin superficial deposit, which overlies the Great Oolite Group. The springs are seasonal, with multiple small springs west of Cowley junction. These comprise of:  West springs/seepages on the western side of the unnamed tributary to the River Frome, which include tufa springs at Bushley Muzzard SSSI.  East springs/seepages on the eastern side of the unnamed tributary to the River Frome Recharge Great Oolite limestone is recharged by rainfall. Inferior Oolite limestone is indirectly recharged by leakage from overlying superficial deposits and Great Oolite Group, fault flow paths and interflow from where the aquifer is at ground surface and directly recharged. Groundwater dependent Bushley Muzzard is located on the western side of the unnamed terrestrial ecosystems tributary of the River Frome, which lies west of the scheme southern end. Source protection zone Source protection zone 3 for the Baunton abstraction is located on the eastern side of the scheme and intersects the mainline between Ch 4+400 and Ch 5+000. The Baunton abstraction is taking water from the Inferior Oolite Group, which is hydraulically disconnected from the scheme in this area.

8.6 Hydraulic parameters 8.6.1 The proposed hydraulic parameters are based on a combination of field tests and published data is presented in Table 8.7. Notably for the limestone aquifers, particularly the Inferior Oolite Group, the saturated zone is very thin (and locally absent), hydraulic testing is limited. Additionally, the K range presented in Table 8.7 for the Inferior Oolite Group are representative for fracture flow. Where there is the potential for karst conduit, this has been accounted for in the impact assessment.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE xliii A417 Missing Link | HE551505 Highways England

Table 8.7 Proposed hydraulic parameters

Unit Description K, minimum (m/s) K, maximum (m/s) Engineered fill Granular, gravelly sand 5.0x10-5 5.0x10-4 Alluvium Clay, sandy clay 1.0x10-8 1.0x10-6 Mass movement and head Clay, sand/gravel lenses 1.0x10-8 1.0x10-4 deposits Cheltenham Sand and Gravel Sand and gravel 1.0x10-4 1.0x10-2 Great Oolite Group Fractured limestone 2.0x10-6 2.0x10-4 Fractured mudstone 2.0x10-8 2.0x10-7 Inferior Oolite Group Fractured limestone 1.0x10-6 1.0x10-4 Massive limestone 3.0x10-11 3.0x10-9 Lias Group Bridport Sand Formation 1.0x10-7 1.0x10-5 Mudstone 1.0x10-11 1.0x10-7

9 Groundwater related features

9.1 Groundwater aquifers 9.1.1 The main aquifers likely to be impacted by the scheme include the superficial deposit Secondary A aquifers, and the Great Oolite and Inferior Oolite Principal aquifers. 9.2 Abstractions 9.2.1 The SPZ3 associated with the Baunton abstraction, abstracting water from the Inferior Oolite aquifer, intersects part of the scheme near Stockwell. The proposed works in these areas are primarily within the Great Oolite aquifer. Where there are works proposed within SPZ3 and within the mapped area of the Inferior Oolite aquifer, the proposed works comprise above ground elements. 9.2.2 Due to the Fuller’s Earth aquitard separating the Great Oolite limestone aquifer and the Inferior Oolite aquifer, it is unlikely that changes in groundwater flow and levels from the proposed cuttings in this area will have a significant impact upon the abstraction. Additionally, the impact of above ground elements within the SPZ3 and underlain by the mapped area of Inferior Oolite aquifer are likely to be negligible. 9.2.3 Two unlicensed abstractions identified during the water feature survey are used for drinking water supply. The first unlicensed abstraction is a piped spring for shared between a private dwelling and Crickley Hill Tractors both at Grove Farm, which is likely to be sourced from the Inferior Oolite Group. The second unlicensed abstraction is a spring at Bushley Muzzard SSSI to supply Watercombe Farm, which is likely to be sourced from the Great Oolite Group. 9.3 Environmentally sensitive sites 9.3.1 Two SSSI are located near the scheme: the Crickley Hill and Barrow Wake SSSI and Bushley Muzzard SSSI. These are represented on ES Figure 13.5 Hydrogeological study area and features (Document Reference 6.3).

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE xliv A417 Missing Link | HE551505 Highways England

9.3.2 The Crickley Hill and Barrow Wake SSSI is designated for its calcareous grassland, broadleaved woodland and nationally important rock exposures44. Based on nearby groundwater monitoring data there is deep unsaturated zone below the SSSI. The ecological surveys completed for the scheme did not identify the presence of groundwater dependent habitats. 4546 9.3.3 Bushley Muzzard SSSI is species-rich wet grassland supplied by localised springs and seepages47. It has been identified as supporting a groundwater dependent habitat. The SSSI is located on the western side of the valley forming the River Frome headwaters. Underlying the SSSI is the Great Oolite Group and Fuller’s Earth Formation, where groundwater levels within the Great Oolite Group aquifer are seasonal and directly recharged by rainfall. Springs are present at the geological contact, which contribute to the marshland conditions of the SSSI. These springs support fen-meadow (M22) vegetation, which may be sensitive changes in local groundwater condition48. The spring catchments are on the opposite side of the valley to the scheme, which is located on the eastern side of the valley. 9.4 Surface water bodies 9.4.1 The Cotswold escarpment forms a surface water divide between the River Severn catchment and the River Thames catchment (to the east and south-east of the divide). To the west of the divide, the land within the scheme drains to the River Severn and its tributaries, including Norman’s Brook, Horsbere Brook and the River Frome (ES Figure 13.5 Hydrogeological study area and features (Document Reference 6.3)). To the east and south-east, the land within the scheme drains to the River Churn, a tributary of the Thames. 9.4.2 Several watercourses in the study area, such as Norman’s Brook, are fed by springs. Some of these streams have losing and gaining reaches meaning that stream flow can be seasonal. As a result, these surface water courses are dependent on groundwater and sensitive to changes in groundwater levels and flows. 9.5 Springs 9.5.1 Groundwater springs are ubiquitous within the Cotswolds escarpment region (ES Figure 13.5 Hydrogeological study area and features (Document Reference 6.3)). Springs in the study area feed the tributary of Norman’s Brook headwaters, an unnamed tributary of the River Frome and an unnamed tributary of the River Churn. These springs are associated with either superficial deposits or limestone formations of the Inferior Oolite Group and the Great Oolite Group. Springs recorded in the study area are presented on ES Figure 13.9 Groundwater monitoring locations (Document Reference 6.3). 9.5.2 Many of the springs (both superficial and limestone) are seasonal features that dry out in response to lower groundwater levels within the respective source aquifer or are linked to storm events. 9.5.3 Mapped limestone springs in the region correlate to bedrock formations and boundaries or structural features including:  The Great Oolite limestones and the Fuller’s Earth Formation  The Inferior Oolite Group (in spatially limited connection with Bridport Sand) and Lias Group mudstone

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE xlv A417 Missing Link | HE551505 Highways England

 Shab Hill Barn fault  Cally Hill fault 9.5.4 Limestone springs 16, 17, 18 and 19 at Crickley Hill form the headwaters to the tributary of Norman’s Brook and are located at the base of the Inferior Oolite Group/top of Bridport Sand Formation, which is locally overlain by thin mass movement deposits. The groundwater levels in the area (borehole DS/RC301) generally have a flashy response, which is a reflection of them being rapid pathway in the aquifer from storm events providing rapid recharge and through put followed by quick draining and returning to low or even dry conditions. The limestone springs close to the edge of the escarpment, are often linked to fissures, faults or gull features. 9.5.5 Spring and seepages emerging from superficial deposits, such as those that feed Norman’s Brook at a lower elevation than limestone springs 16, 17, 18 and 19, include a combination of seasonal and perennial springs. In the case of the superficial springs that feed Norman’s Brook these are fed from permeable units within the cohesive dominated mass movement deposits. Whereas the cohesive deposits are derived from failure and weathering of the Lias Group the permeable units derive from topple failures and weathering of the Inferior Oolite Group. As such the permeable units are a source for CaCO3, which will harden the recharge waters and result in springs with relatively high CaCO3 concentrations. Where the emergent conditions are suitable tufa may precipitate, which is presented in more detail in Section 9.6 below. 9.5.6 Springs that feed the unnamed tributary to the Frome and unnamed tributary to the River Churn are both those derived from limestone bedrock and superficial deposits. Springs are characterised as being from superficial deposits where the drift is considered think enough. Otherwise these are characterised as limestone springs emerging from a thin veneer of drift. 9.5.7 The seasonality of springs is determined from the record of water features survey and interpretation of site photographs/aerial photographs. 9.6 Superficial carbonate precipitates 9.6.1 Superficial carbonate precipitates are terrestrial deposits49 which form a variety of environments and are commonly found in areas with limestone bedrock. Common names for terrestrial carbonate deposits, ‘tufa’ and ‘travertine’, are often used interchangeably within karst literature. The naming convention adopted by Ford & Williams (2007) has been applied to this assessment where:  Tufa refers to grainy deposits accreting to algal filaments, plant stem and roots at springs, along riverbanks, lake edges, etc50. 9.6.2 Based on the definition of tufa in Ford & Williams (2007), the sites identified in the Water Feature Survey are considered potential tufa formations until additional geomorphology and ecology surveys can be completed. 9.6.3 Carbonate deposits typically forms due to the precipitation of calcium carbonate, when carbon dioxide degasses from supersaturated carbonate waters: ퟐ+ ퟑ― 푪풂 + ퟐ푯푪푶 ⟺푪풂푪푶ퟑ + 푪푶ퟐ + 푯ퟐ푶 9.6.4 Several factors can influence the rate of carbon dioxide degassing and accretion of calcite precipitate, which includes but is not limited to temperature change and

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE xlvi A417 Missing Link | HE551505 Highways England

groundwater flow rates. Microbial activity can also increase the reaction rate and promote the formation of precipitate. 9.6.5 The classification of these deposits is based on three main criteria: geochemical – precipitation processes and carbon dioxide geochemistry; fabric; and morphology51. Tufa formations are of importance due to the potential of protected flora growing at the formation location. 9.6.6 The identified tufa deposits have been surveyed by a specialist ecologist with respect to tufa habitats. The report is presented in ES Appendix 8.24 Assessment of tufaceous vegetation (Document Reference 6.4). 9.6.7 The tufa deposits identified in the Biodiversity Chapter include those identified along the tributary of Norman’s Brook during the Water Feature Survey (ES Figure 13.5 Hydrogeological study area and features (Document Reference 6.3) and ES Appendix 13.11 Water feature survey). Based on the geological setting it is anticipated that tufa is precipitating from groundwater seeping from mass movement deposits, which includes limestone parent material. The high permeability units of the mass movement deposits allow significant contact of groundwater with the limestone rock fragments, which allows the groundwater to become hard relatively quickly. Recharge, such as rainfall precipitation, which is slightly acidic and can dissolve calcium carbonate and other ions is often referred to as ‘attacking’52. 9.7 Dry valleys 9.7.1 Dry valleys in limestone terrains are glaciofluvial karst features. Such valleys originally formed by periglacial streams that incised into the limestone bedrock, often creating steep sided gorges and ravines. Subsequently, the streams drained elsewhere, often being lost to ground as losing streams53. Dry valleys are relic topographical features, but seasonal streams may flow episodically54,55. 9.7.2 Two dry valleys are recorded in the water feature survey, one at Shab Hill junction (G183 and G184) and one at Barrow Wake dry valley (G3) where the revised position of the Shab Hill Barn fault is located (ES Figure 13.5 Hydrogeological study area and features (Document Reference 6.3). 9.7.3 At Shab Hill the head of dry valley begins approximately 240m south west of Shab Hill junction. This stretch of the valley is approximately 60m wide and up to 12m deep and a seepage (G146) has been mapped on the left-hand valley side. From Shab Hill junction the dry valley runs in an east-south-east direction where the valley sides gradually become less steep and the valley becomes wider towards the tributary of the River Churn. Two seepages and one groundwater spring (G180, G145 and G181 respectively) have been mapped on the northern valley side of the valley in this section. 9.7.4 There is a dry valley mapped at Barrow Wake (G3), which extends to the north west from the crest of the escarpment towards Crickley Hill Tractors. The dry valley is approximately 150m in length and approximately 150m wide. The dry valley coincides with the revised position of the Shab Hill Barn fault with a cluster of springs at the base of the dry valley (springs 16, 17, 18 and 19), which form the headwaters to the tributary of Norman’s Brook. The dry valley is likely to have been guided in its development due to the Shab Hill Barn fault and the resultant valley has formed due to a combination of these geomorphological features. During the Water Features Survey, flow gauging in the upper reach of Norman’s

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE xlvii A417 Missing Link | HE551505 Highways England

Brook identified that the spring fed watercourse had flows during April 2018 and March 2019 but dry in July 2018 and February 2019. 10 Potential impacts to groundwater features

10.1 Overview 10.1.1 This section assesses potential impacts to groundwater features from interaction with design elements of the scheme. The HIA focuses cuttings, ground stabilisation measures and embankments for both flow and drawdown impacts. The methodology of the assessment is provided below and is followed by a detailed assessment for each design element. 10.2 Methodology Flow impacts 10.2.1 Groundwater flow impacts have been assessed qualitatively, particularly with cuttings, ground stabilisation and embankments. The cutting depth have been considered relative to the highest groundwater levels recorded or where conceptually the structure is likely to intercept groundwater. The horizontal extent of structures including pile spacing has been considered in the context of the aquifer extent and nearby groundwater features. Drawdown impacts 10.2.2 Quantitative dewatering calculations have been completed for below ground works likely to intercept groundwater to determine the magnitude of drawdown effects and predict flow rates either during construction or operational phases of the scheme. Drawdown levels are based on the maximum measured groundwater level for the period of monitoring up to October 2020. The winter of 2019 and 2020 is reported by the Met office to be the 5th wettest on record, with February 2020 being the wettest February on record, with up to three times the expected average. On this basis the winter of 2019/20 includes one of the wettest winters on record and groundwater responses are expected to include high peak winter events. 10.2.3 Initially the design elements were qualitatively assessed using maximum groundwater monitoring levels and conceptual models to determine if the excavation is likely to encounter groundwater. The qualitative assessment compared the lowest relevant element level and the highest groundwater level, both in mAOD. If the groundwater level is below the lowest design element level, it is assumed that dewatering is not required and therefore a quantitative assessment has not been completed. 10.2.4 Potential drawdowns in bulk permeability are assessed using the Sichardt equation. However, for each cutting in limestone there is a further assessment for the situation that karst is encountered.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE xlviii A417 Missing Link | HE551505 Highways England

10.2.5 The Sichardt equation assumes the aquifer is unconfined, infinite horizontal extent, constant thickness, homogenous and isotropic with respect to hydrogeological parameters.

푅0 = 퐶(퐻 ― ℎ) 퐾 Where:

R0 = Radius of influence (m) C = Empirical correlation factor (taken as 2000 as design elements are linear) H = Piezometric level in the aquifer (mAOD) i.e. maximum groundwater level anticipated h = Target drawdown level (mAOD) i.e. 1m below the cutting, or lowest design element level K = Hydraulic conductivity (m/s) 10.2.6 The inflow rates have been calculated using the Mansur & Kaufman56 formulae for one-sided and two-sided trenches depending on the cut geometry and groundwater flow direction. A one-sided trench analysis has been completed where only one side of the road is in cut or where substantial flows are not anticipated into one side of the cut, for example, where one side of the cut is close to a hydraulic boundary such as the Fuller’s Earth Formation. Otherwise a two-sided trench analysis has been completed.

(퐻 ― ℎ )(퐾 ― 퐿) 푄 = 0.73 + 0.27 푤 (퐻2 ― ℎ 2) One-sided trench inflow 퐻 2푅0 푤

(퐻 ― ℎ )(퐾 ― 퐿) 푄 = 0.73 + 0.27 푤 (퐻2 ― ℎ 2) Two-sided trench inflow 퐻 푅0 푤 Where: Q = Flow rate (m3/day)

hw = Height of drawdown level above the base of the aquifer L = Length of the element (m) i.e. cutting length like to intersect groundwater 10.2.7 The equations above represent steady-state conditions and are likely to represent the groundwater conditions to a point where the groundwater level stabilises due to passive dewatering at the cutting location. 10.2.8 A conservative approach has been taken to the drawdown assessment where the drawdown has been calculated using a combination of:  Maximum cutting height within the aquifer.  Maximum groundwater elevation.  Drawdown required is to 1m below the finished road level or the base of the aquifer, whichever is higher.  The highest bulk hydraulic conductivity value for the strata or where formations are horizontally interbedded the effective horizontal hydraulic conductivity (determined by the weighted arithmetic mean).

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE xlix A417 Missing Link | HE551505 Highways England

10.3 Detailed assessment 10.3.1 Detailed assessments have been undertaken to assess the potential quantitative impacts from proposed cuttings in accordance with the methodology presented in Section 10.2. 10.3.2 Conservative hydraulic conductivity values to provide a conservative estimate of the drawdown radius of influence (reference Table 8.7). The radius of influence represents a ‘reasonable worst-case’ and is based on conservative inputs derived from available field or desk study data and published research literature relevant to the study area 10.3.3 Cuttings are assumed to be open and passive drainage is installed 1m below the finished road level at the toe of the cutting. Ground stabilisation measures 10.3.4 ES Chapter 2 The project (Document Reference 6.2) describes the ground stabilisation measures considered to be required to manage the risk of slope movement and instability. The proposed slope drainage would comprise shallow inclined perforated drainage pipes which would be installed by drilling into the slope from the highway verge, with any groundwater flows channelled into drainage. 10.3.5 Refer to ES Figure 13.17 Groundwater conceptual model locations (Document Reference 6.3) for the general arrangement at the location and sections C-C’ and D-D’ in ES Figure 13.10 Groundwater conceptual model (Document Reference 6.3) for the hydrogeological conceptualisation. 10.3.6 As the shallow inclined perforated drains would be installed into cohesive dominated superficial deposits, the induced drawdown is likely to be localised and limited in extent to the zone of the horizontal drains. However, those drains that intercept sand and gravel or areas where toppled limestone blocks are present would drain groundwater from these isolated pockets. Two springs are identified in the water features survey in the area of the land drains, these are G206 and 83. 10.3.7 All intercepted groundwater would be carried from the horizontal drains to a surface water discharge point, within the same receiving water that the groundwater would naturally have discharged to (see ES Appendix 13.10 Drainage (both Document Reference 6.4) respectively). Dewatering and discharge arrangements would need to be made with the EA prior to construction. Embankments 10.3.8 Where the placement of embankments is over or adjacent to spring/seepage locations there is potential that the drainage measure to carry the flows to receiving waters may change the characteristics of the groundwater emergence. This is particularly relevant for tufa springs where tufa deposition is related to the physio-chemical properties of the groundwater at the point of emergence. However, it is noted that although the characteristics of the spring will be modified, the characteristics of recharge and storage of groundwater as flows through the superficial deposits will not be modified by the embankments and on this basis the impact will be to spring characteristics such as hydraulic gradient, width and depth rather than water quality and overall flow rate.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE l A417 Missing Link | HE551505 Highways England

10.3.9 The list of springs and seepage locations that have the potential to be impacted by embankment placement are presented in Table 10.1. Table 10.1 Summary of potential impacts to springs

Feature type Quantity Feature ID Potential Impact CH 0+900 to CH1+500 – Crickley Hill Seepage from superficial deposits Embankment placement contributing to the tributary of Norman’s 3 80, G20, G151 over spring Brook Modified spring from superficial deposits Embankment placement contributing to the tributary of Norman’s 2 61, G17 over spring Brook Tufa spring from superficial deposits Embankment placement contributing to the tributary of Norman’s 3 69, 81, G231 over spring Brook Perennial spring from superficial Embankment placement deposits contributing to the tributary of 3 78, 72, G2 over spring Norman’s Brook Seasonal spring from superficial Embankment placement 1 G152 deposits contributing to Norman’s Brook over spring CH3+100 – Shab Hill junction Seepage from superficial deposits Embankment placement overlying the Great Oolite Group that over spring 1 G146 feed headwater of unnamed tributary of the River Churn CH4+000 – Cuttings between Shab Hill junction and Cowley junction Seepage from superficial deposits Embankment placement feeding headwater unnamed tributary of 1 G174 over spring the River Churn (East) Cutting from Ch 1+700 to Ch 2+800 10.3.10 Refer to ES Figure 13.17 Groundwater conceptual model locations (Document Reference 6.3) for the general arrangement at the location and sections C-C’ and D-D’ in ES Figure 13.10 Groundwater conceptual model (Document Reference 6.3) for the hydrogeological conceptualisations. The cutting will be excavated into the Inferior Oolite Group. Springs 16,17, 18 and 19) are located 100m south of and 10m lower than the cutting. 10.3.11 Based on the groundwater level data available, the maximum winter groundwater level would not intercept the cut face but may rise above the drainage trench invert level at the most western end of the cutting only. Drawdown from the road drainage trench invert is within the Inferior Oolite Group and is limited to the west by the Lias Group geological boundary. In the case that karst conduits are intercepted by the drainage trench then these have the potential to intersect peak groundwater table during the winter high and in these cases this water would be intercepted by the drainage system. Due to the potential high connectivity of karst pathways in the Inferior Oolite Group if karst was encountered then this has the potential of lowering the seasonal peak groundwater table and spring flows but will not impact on groundwater levels and spring flows at any other time of the year.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE li A417 Missing Link | HE551505 Highways England

10.3.12 In the non-karst scenario, based on a maximum hydraulic conductivity of 2x10- 4 m/s and using the recorded winter peak groundwater levels, the maximum radius of influence calculated from the cutting is 32 m, which will not impact on springs 16, 17, 18 and 19. This is based on a conservative vertical drawdown of 1.2 m in the cutting. The drawdown from the cutting are shown in ES Figure 13.16 Groundwater impact assessment (Document Reference 6.3). 10.3.13 The baseline assessment identifies that groundwater intersected by the drainage trench is part of the Severn Vale groundwater catchment that drains westward supporting base flow in the tributary of Norman’s Brook. Groundwater captured within the drainage trench will be carried downstream of the cutting and will feed back into the realigned tributary of Norman’s Brook. There would be no net loss of groundwater to the tributary of Norman’s Brook as groundwater intercepted by the cutting would be routed back to it. 10.3.14 Dewatering and discharge arrangements would need to be made with the EA prior to construction. 10.3.15 A summary of the non-karst detailed assessment is presented in Table 10.2. Table 10.2 Cutting from Ch 1+700 to Ch 2+800 detailed assessment summary

Section chainage 1+700 Ground conditions Inferior Oolite limestone Drawdown required (m) 5 Hydraulic conductivity (m/s) 2x10-4 Radius of influence (m) 32 Design element length within water bearing unit (m) 50 Maximum inflow (m3/day) 127 B4070 link road cutting 10.3.16 Refer to ES Figure 13.17 Groundwater conceptual model locations (Document Reference 6.3) for the general arrangement at the location and section G-G’ in ES Figure 13.10 Groundwater conceptual model (Document Reference 6.3) for the hydrogeological conceptualisation. The cutting has a maximum depth of 7 mbgl and cuts through the base of the Great Oolite Group and into the underlying Fuller’s Earth Formation. The Fuller’s Earth Formation is a hydraulic barrier to groundwater flow and the extent of drawdown would be slight where the cutting intersects this formation. However, drawdown would occur where the cutting intersects the Great Oolite Group limestone formations. East of the B4070 link road cutting lies the Shab Hill dry valley feature, which during peak winter storm events has been noted to develop flow. 10.3.17 The cutting is located along the ridgeline of the Cotswold plateau and within the headwater of the catchment. Based on the groundwater level data available, the maximum winter groundwater level would not intercept the cut face but may rise into the drainage trench invert level. In the case that karst conduits are intercepted by the drainage trench then these have the potential to intersect peak groundwater table during the winter high and in these cases this water would be intercepted by the drainage system. Due to the potential high connectivity of karst pathways in the Great Oolite Group at Shab Hill, if karst was encountered then this has the potential of lowering the seasonal peak groundwater table and potentially reducing emergent groundwater flows in the dry valley (spring G146)

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lii A417 Missing Link | HE551505 Highways England

but will not impact on groundwater levels nor groundwater emergences at any other time of the year. 10.3.18 In the non-karst scenario, the estimated radius of influence encroaches onto the Shab Hill dry valley feature. On this basis there is a potential for a seasonal impact to groundwater emergences in the dry valley (spring G146) from the cutting due to a small reduction in the catchment size. 10.3.19 Based on a maximum hydraulic conductivity of 2x10-4m/s and the winter peak groundwater levels, the maximum radius of influence calculated from the cutting is 18m. The calculated radius of influence is shown in ES Figure 13.16 Groundwater impact assessment (Document Reference 6.3). 10.3.20 All intercepted groundwater would be carried from the cutting to a surface water discharge point, within the same receiving water that the groundwater would naturally have discharged to (see ES Appendix 13.10 Drainage (both Document Reference 6.4)). Dewatering and discharge arrangements would need to be made with the EA prior to construction. 10.3.21 A summary of the detailed assessment is presented in Table 10.3. Table 10.3 B4070 link road cutting detailed assessment summary

Section chainage 3+040 Ground conditions Great Oolite limestone Fuller’s Earth Formation Drawdown required (m) 0.65 Hydraulic conductivity (m/s) 2x10-4 Radius of influence (m) 18 Design element length within water bearing unit (m) 100 Maximum inflow (m3/day) 542 Shab Hill junction to Cowley junction cuttings 10.3.22 Refer to ES Figure 13.17 Groundwater conceptual model locations (Document Reference 6.3) for the general arrangement at the location and sections H-H’ and I-I’ in ES Figure 13.10 Groundwater conceptual model (Document Reference 6.3) for the hydrogeological conceptualisations. The cuttings are in the Great Oolite Group and Fuller’s Earth Formation. 10.3.23 The cuttings are located along the ridgeline of the Cotswold plateau and within the headwater of the catchment. The recorded seasonal fluctuation of the groundwater table indicates that the cutting would be dry in the summer, however will intercept the winter groundwater table. The drawdown from the cutting is within the transition of Great Oolite Group limestones in the Fuller’s Earth Formation. The ground conditions comprise interbedded mudstone with limestone units, where the mudstone layers become thicker with depth. 10.3.24 Based on the geological assessment that the transition lithology in this section of the scheme is mudstone dominant with minor limestone the risk of karst is significantly reduced and on that basis the drawdown calculation are assessed for the non-karst scenario only. 10.3.25 Based on a maximum hydraulic conductivity of 4.3x10-5 m/s and the peak winter groundwater levels, the maximum lateral radius of influence calculated from the

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE liii A417 Missing Link | HE551505 Highways England

deepest cutting is 81 m. The calculated radius of influence is shown in ES Figure 13.16 Groundwater impact assessment (Document Reference 6.3). 10.3.26 The calculated radius of influence for the cuttings does not extend as far as any groundwater features but has the potential to reduce the catchment area of spring on the Eastern side of the unnamed tributary to the River Frome. Those springs that lie on the western side of the unnamed tributary to the River Frome, which include Bushley Muzzard SSSI lies in a separate groundwater subcatchment that is isolated from the scheme by the valley of the tributary. 10.3.27 All intercepted groundwater will be carried from the cutting to a surface water discharge point, within the same receiving water that the groundwater would naturally have discharged to (see ES Appendix 13.10 Drainage (Document Reference 6.4)). Dewatering and discharge arrangements would need to be made with the EA prior to construction. 10.3.28 A summary of the detailed assessment is presented in Table 10.4. Table 10.4 Shab Hill junction to Cowley junction cuttings detailed assessment summary

Section chainage 3+740 4+200 5+000 Ground conditions Great Oolite Group interbedded mudstones and limestones Fuller’s Earth Formation Drawdown required (m) 6.2 8.6 1.4 Hydraulic conductivity (m/s) 1.2x10-4 8.4x10-5 7.4x10-5 Radius of influence (m) 81 40 26 Design element length within water bearing unit (m) 210 360 560 Maximum inflow (m3/day) 310 1340 780 Cowley junction east cutting 10.3.29 The cutting is in the transition of the Great Oolite Group limestone formations and Fuller Earth Formation. The Fuller’s Earth Formation is a hydraulic barrier to groundwater flow and limits the extent of drawdown. However, drawdown would occur where groundwater levels within Great Oolite Group are intercepted. As with the previous section, the Great Oolite Group formations at this location are dominantly mudstone with minor limestone units. 10.3.30 The cutting is located along the ridgeline of the Cotswold plateau and within the catchment headwaters. The recorded seasonal fluctuation of the groundwater table indicates that the cutting would be dry in the summer, however, would likely intercept the winter groundwater table. The drawdown from the cutting is within the basal unit of the Great Oolite Group, which comprises limestones interbeds transitioning into Fuller’s Earth Formation with minor limestone units. 10.3.31 Based on the geological assessment that the transition lithology in this section of the proposed road development is mudstone dominant with minor limestone the risk of karst is significantly reduced and on that basis the drawdown calculation are assessed for the non-karst scenario only. 10.3.32 Based on a maximum hydraulic conductivity of 7.4x10-5 m/s and peak winter groundwater levels, the maximum lateral radius of influence is 16m, which is calculated from the deepest part of the cutting. The calculated radius of influence

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE liv A417 Missing Link | HE551505 Highways England

for the cuttings does not intercept and groundwater dependent features but has potential to reduce the winter flows in springs on the western margin of the outlier due to slight reduction in catchment extent. The calculated radius of influence is shown in ES Figure 13.16 Groundwater impact assessment (Document Reference 6.3). 10.3.33 All intercepted groundwater would be carried from the cutting to a surface water discharge point, within the same receiving water that the groundwater would naturally have discharged to (see ES Appendix 13.10 Drainage (both Document Reference 6.4). Dewatering and discharge arrangements would need to be made with the EA prior to construction. 10.3.34 A summary of the detailed assessment is presented in Table 10.5. Table 10.5 Cowley junction east cutting detailed assessment summary

Section chainage 0+00 Ground conditions Great Oolite interbedded mudstones and limestones Fuller’s Earth Formation Drawdown required (m) 0.9 Hydraulic conductivity (m/s) 7.4x10-5 Radius of influence (m) 16 Design element length within 120 water bearing unit (m) Maximum inflow (m3/day) 225

10.4 Summary of impacts 10.4.1 The detailed assessment of design elements of the proposed road development is assessed in Section 10.3. These are summarised as localised drawdown impacts related to drainage measures and cuttings in bedrock that intersect the groundwater table with potential impacts to springs/seepages and impacts from embankment placement over springs. Both types of impacts are summarised in Table 10.6. Table 10.6 Summary of potential impacts to springs

Feature type Quantity Feature ID Potential Impact Ch 0+900 to Ch 1+500 – Crickley Hill Seepage from superficial deposits Embankment placement contributing to the tributary of Norman’s 3 80, G20, G151 over spring Brook Modified spring from superficial deposits Embankment placement contributing to the tributary of Norman’s 2 61, G17 over spring Brook Tufa spring from superficial deposits Embankment placement contributing to the tributary of Norman’s 3 69, 81, G231 over spring Brook Perennial spring from superficial Embankment placement deposits contributing to the tributary of 3 78, 72, G2 over spring Norman’s Brook Seasonal spring from superficial Embankment placement 1 G152 deposits contributing to Norman’s Brook over spring

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lv A417 Missing Link | HE551505 Highways England

Feature type Quantity Feature ID Potential Impact Spring/seepage from superficial Drawdown from ground 2 G206 and 83 deposits contributing to Norman’s Brook stabilisation Ch 1+700 to Ch 3+000 cutting Seasonal limestone springs emerging Reduction in peak winter from the Inferior Oolite Group/Bridport flow if cutting intersects 4 16, 17, 18 and 19 Sand Formation that feed the headwater karst in drainage invert of the tributary of Norman’s Brook Ch 3+100 – Shab Hill junction Seepage from superficial deposits Embankment placement overlying the Great Oolite Group that over spring and potential 1 G146 feed headwater of unnamed tributary of reduction in peak winter the River Churn spring flow Ch 4+000 – Cuttings between Shab Hill junction and Cowley junction Seepage from superficial deposits Embankment placement feeding headwater unnamed tributary of 1 G174 over spring the River Churn (East) Seepage from superficial deposits G150, G147, G173, Reduction in peak winter feeding headwater unnamed tributary of 7 G100, G221, G219 spring/seepage flow the River Frome (East) and G220 Combined effects 10.4.2 The potential impacts outlined above for cuttings occur within three aquifer types and within three subcatchments. 10.4.3 Those cutting impacts identified at CH1+700 to CH3+000 – cutting are specific to the Inferior Oolite Group which feeds headwaters to Norman’s Brook. 10.4.4 Those cutting impacts identified at CH3+100 – Shab Hill junction are specific to the Great Oolite Group which feeds headwaters to an unnamed tributary of the River Churn. 10.4.5 Those cutting impacts identified at CH4+000 – Cuttings between Shab Hill junction and Cowley junction are specific to the Great Oolite Group which feeds headwaters to an unnamed tributary of the River Frome. 10.4.6 Based on the above, there is no cumulative impact between the three cuttings identified either to aquifer units or receiving surface waters. 10.4.7 The tributary of Norman’s Brook has potential impacts from groundwater interception at CH1+700 to CH3+000 and interception of groundwater in superficial deposits from ground stabilisation measures. As the potential impacts are from separate aquifer units these will not have cumulative impacts on either groundwater body. Both design elements do however discharge to the tributary of Norman’s Brook. As all groundwater will still be received by the natural receiving water there will be no net change in the total water quantities. Where groundwater interception occurs then the top of the groundwater table may be intercepted and seasonally decant into drainage inverts and cuttings. This has the potential to shorten the pathway from ground to stream, which may allow a component of groundwater to enter the tributary more rapidly.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lvi A417 Missing Link | HE551505 Highways England

11 Conclusions

11.1.1 The purpose of this HIA is to present the current information available to inform the baseline conditions of the site and assess how the scheme is likely to impact the groundwater regime with respect to levels, flow and quality. The assessment has focussed on groundwater features including: superficial aquifers, bedrock aquifers, groundwater abstractions, groundwater discharges, environmentally sensitive sites, surface watercourses, springs/seepages, terrestrial carbonate deposits (tufa) and karst dry valleys. Potential groundwater impacts from design elements of the scheme are summarised below. 11.1.2 Based on the detailed assessment, the proposed horizontal drains along Crickley Hill would cause localised lowering in the mass movement deposits. As the mass movement deposits are cohesive dominated, the drawdown extent would be limited to the immediate locale of the drains. However, in the case that high permeability zones, such as sand and gravel or zones of granular material associated with toppled limestone blocks, occur within the extent of drawdown then these would also be drained. 11.1.3 Based on the detailed assessment of the B4070 link road cutting, the drawdown extent has the potential to impact on groundwater levels below a dry valley. Based on this assessment during peak groundwater heads there is a potential that groundwater emergence in the floor of the dry valley would be reduced during the winter. 11.1.4 Cuttings along the scheme have the potential to intersect groundwater. The drawdown assessment has been undertaken using high permeability values and peak groundwater level conditions and as such as considered conservative. Based on the seasonal fluctuation of groundwater levels recorded along the scheme drawdowns are seasonal, occurring during the winter. Based on the monitoring data, summer groundwater levels will not be impacted but when groundwater levels rise to their highest groundwater levels during the winter then the top of the groundwater may be intercepted by drainage inverts and cuttings. The drainage design is managed so that all intercepted groundwater remains within the catchment of the respective receiving water.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lvii A417 Missing Link | HE551505 Highways England

Appendix A Standpipe installations

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lviii A417 Missing Link | HE551505 Highways England

Table A.1 Summary of groundwater monitoring installations

Location Ground Easting Northing Top of Depth of Response zone Response zone investigation hole hole (mbgl) (mAOD) (mAOD) (mbgl)

CP 102 Phase 2A 392080.9 215724.9 127.55 20.00 3.0 - 5.5 124.55 - 122.05 CP 104A Phase 2A 392525.2 215641.5 148.00 16.76 14.7 - 15.8 133.3 - 132.2 CP 105 Phase 2A 392765 215682 169.90 30.00 3.0 - 9.5 166.9 - 160.4 CP 106 Phase 2A 392949 215756 186.25 35.50 19.0 – 30.0 167.25 - 156.25 CP 200 Phase 2A 392242.9 215743.3 129.70 14.50 8.5 - 12 121.2 - 117.7 CP 202 Phase 2A 392408.8 215671.5 135.70 20.00 3.7 - 5.7 132.0 – 130.0 CP 204 (d) Phase 2A 392647.4 215541.1 178.90 25.00 12.5 - 13.9 166.4 – 165.0 CP 204 (s) Phase 2A 392647.4 215541.1 178.90 25.00 8.5 - 9.9 170.4 – 169.0 CP 206 Phase 2A 392655 215664 162.85 19.70 10.0 – 16.0 152.85 - 146.85 CP 210 (d) Phase 2A 392672.4 215777.0 174.30 25.00 13.0 – 17.0 161.3 - 157.3 CP 210 (s) Phase 2A 392672.4 215777.0 174.30 25.00 2.5 - 5.5 171.8 - 168.8 CP 211 Phase 2A 392674.1 215809.4 183.45 35.00 1.1 - 3.3 182.35 - 180.15 CP 212 (d) Phase 2A 392814 215558 191.60 24.50 18.5 - 24.5 173.1 - 167.1 CP 212 (s) Phase 2A 392814 215558 191.60 24.50 8.0 - 13.9 183.6 - 177.7 CP 215 (d) Phase 2A 392806.0 215804.5 186.05 25.00 14.5 - 15.5 171.55 - 170.55 CP 215 (s) Phase 2A 392806.0 215804.5 186.05 25.00 2.0 – 3.0 184.05 - 183.05 CP 216 Phase 2A 392833 215701 173.50 25.60 2.0 – 7.0 171.5 - 166.5 CP 223 Phase 2A 392596 215474 179.75 25.50 19 - 22.6 160.75 - 157.15 DS/RC 109 Phase 2A 393208 215995.1 233.00 105.00 2.5 - 20 230.5 – 213.0 DS/RC 205 Phase 2A 392612.4 215766.3 167.15 30.00 9.5 - 11.7 157.65 - 155.45 DS/RC 218 Phase 2A 394126 214739 285.65 25.00 2.0 – 15.0 283.65 - 270.65 DS/RC 220 Phase 2A 394379 214500.9 278.85 31.30 3.0 – 13.0 275.85 - 265.85 DS/RC 229 Phase 2A 392895.9 215874.1 200.45 25.00 4.5 – 8.0 195.95 - 192.45 DS/RC 301 Phase 2A 393184.6 215961.8 234.20 105.05 7.4 - 28.5 226.8 - 205.7

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lix A417 Missing Link | HE551505 Highways England

Location Ground Easting Northing Top of Depth of Response zone Response zone investigation hole hole (mbgl) (mAOD) (mAOD) (mbgl)

DS/RC 302 Phase 2A 393329 216018 234.50 35.20 15.0 – 26.0 219.5 - 208.5 DS/RC 310 Phase 2A 394101.2 215210.8 250.90 30.20 2.0 – 30.0 248.9 - 220.9 DS/RC 311 Phase 2A 394015.5 215259 255.20 40.00 11.5 – 40.0 243.7 - 215.2 DS/RC 312 Phase 2A 393779.7 215300.8 282.15 25.10 1.0 – 14.0 281.15 - 268.15 DS/RC 314 Phase 2A 393256 215193.1 293.10 15.00 2.0 – 15.0 291.1 - 278.1 DS/RC 315 Phase 2A 394194 215201.1 246.90 90.65 4.4 - 52.7 242.5 - 194.2 DS/RC 315A Phase 2A 394194 215200 247.00 54.50 4.4 - 52.9 242.6 - 194.1 DS/RC 317 Phase 2A 394717.9 214126.8 274.90 30.00 1.0 - 3.8 273.9 - 271.1 DS/RC 319 Phase 2A 393406.8 216148.4 231.60 65.20 2.9 - 20 228.7 - 211.6 DS/RC 325 Phase 2A 393329.2 216103.9 233.25 40.60 3.8 - 25.1 229.45 - 208.15 DS/RC 401 Phase 2A 394825.4 213679.2 273.10 20.00 4.8 - 8.2 268.3 - 264.9 DS/RC 403 Phase 2A 394937.6 213164.4 247.65 20.00 4.0 - 20.6 243.65 - 227.05 DS/RC 404 Phase 1 393207 215566 269.00 100.50 23.0 - 33.5 246 - 235.5 DS/RC 406 Phase 1 393384 216009 238.65 60.00 20.5 - 34 218.15 - 204.65 DS/RC 408 Phase 1 393605 216240 232.50 75.20 20.0 - 23.5 212.5 - 209 DS/RC 415 Phase 1 393527 213994 287.20 51.00 25.5 – 49.0 261.7 - 238.2 DS/RC 418 Phase 2A 393131.8 216418.8 272.25 61.50 27.0 – 58.0 245.25 - 214.25 DS/RC 419 Phase 1 393213 215564 268.90 60.20 36.0 - 41.5 232.9 - 227.4 DS/RC 420 Phase 2A 393950 213950 277.10 30.00 0.8 - 3.2 276.3 - 273.9 DS/RC/OH 110 Phase 2A 393441 216054 240.00 60.20 23.0 – 34.5 217.0 – 205.5 DS/RC/OH 304 Phase 2A 393248.8 216080.1 231.85 60.20 26.1 - 53.7 205.75 - 178.15 DS/RC/OH 308 Phase 2A 393999.2 215766.9 271.35 70.40 1.5 - 58.5 269.85 - 212.85 DS/RC/OH 400 Phase 2A 394666.1 213848.1 267.95 90.30 13.3 - 76 254.65 - 191.95 DS/RC/OH 412 Phase 2A 394240.9 215146.1 250.30 30.00 13.2 - 29.5 237.1 - 220.8 DS/RC/OH 414 Phase 2A 393481.8 215560.7 274.60 90.00 28.3 - 59.3 246.3 - 215.3 DS/RC/OH 107 Phase 2A 393057 215838 191.90 30.20 2.0 - 5.5 189.9 - 186.4

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lx A417 Missing Link | HE551505 Highways England

Location Ground Easting Northing Top of Depth of Response zone Response zone investigation hole hole (mbgl) (mAOD) (mAOD) (mbgl)

DS/RC 108 Phase 2A 393083 215863 193.60 49.50 8.0 – 16.0 185.6 - 177.6 DS/RC 224 Phase 2A 392857 215346 226.85 80.50 49.0 – 70.0 177.85 - 156.85 OH 405 Phase 1 393388 215997 239.50 40.00 11.0 – 17.0 228.5 - 222.5 OH 407 Phase 1 393596 216246 231.75 55.55 6.0 – 15.0 225.75 - 216.75 OH 411 Phase 2A 393819 215306 280.50 100.95 22 - 85.7 258.5 - 194.8 OH 413 Phase 2A 394312.1 214960.1 270.65 100.00 2.7 - 15.7 267.95 - 254.95 OH 416 Phase 1 393538 213990 286.85 5.00 3.0 - 4.5 283.85 - 282.35 OH 417 Phase 2A 394178 214888.9 275.65 90.00 5.5 - 70.9 270.15 - 204.75 OH 416 Phase 1 393538 213990 286.85 5.00 3.0 - 4.5 283.85 - 282.35 OH 417 Phase 2A 394178 214888.9 275.65 90.00 5.5 - 70.9 270.15 - 204.75

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lxi A417 Missing Link | HE551505 Highways England

Appendix B Groundwater monitoring results

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lxii A417 Missing Link | HE551505 Highways England

Figure B-1 Mass movement deposits groundwater monitoring – CH0+500 to CH1+000, lower Crickley Hill

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lxiii A417 Missing Link | HE551505 Highways England

Figure B-2 Mass movement deposits groundwater monitoring – CH1+000 to CH1+400 (northern side of A417), mid Crickley Hill

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lxiv A417 Missing Link | HE551505 Highways England

Figure B-3 Mass movement deposits groundwater monitoring – CH1+000 to CH1+400 (northern side of A417), mid Crickley Hill

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lxv A417 Missing Link | HE551505 Highways England

Figure B-4 Mass movement deposits groundwater monitoring – CH1+000 to CH1+400 (southern side of A417), mid Crickley Hill

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lxvi A417 Missing Link | HE551505 Highways England

Figure B-5 Mass movement deposits groundwater monitoring – CH1+000 to CH1+400 (southern side of A417), mid Crickley Hill

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lxvii A417 Missing Link | HE551505 Highways England

Figure B-6 Mass movement deposits groundwater monitoring – CH1+400 to CH1+700 (southern side of A417), upper Crickley Hill

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lxviii A417 Missing Link | HE551505 Highways England

Figure B-7 Mass movement deposits groundwater monitoring - CH1+400 to CH1+700 (northern side of A417) - upper Crickley Hill

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lxix A417 Missing Link | HE551505 Highways England

Figure B-8 Great Oolite limestone groundwater monitoring – CH3+000 to CH3+500, Shab Hill junction

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lxx A417 Missing Link | HE551505 Highways England

Figure B-9 Great Oolite limestone groundwater monitoring – CH3+000 to CH3+500, Shab Hill junction

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lxxi A417 Missing Link | HE551505 Highways England

Figure B-10 Great Oolite limestone groundwater monitoring – CH3+500 to CH5+000, Shab Hill junction to Cowley junction

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lxxii A417 Missing Link | HE551505 Highways England

Figure B-11 Great Oolite limestone groundwater monitoring – Bushley Muzzard SSSI

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lxxiii A417 Missing Link | HE551505 Highways England

Figure B-12 Fuller’s Earth Formation groundwater monitoring, CH3+500 to CH5+000, Shab Hill junction to Cowley junction

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lxxiv A417 Missing Link | HE551505 Highways England

Figure B-13 Fuller’s Earth Formation groundwater monitoring, CH3+500 to CH5+000, Shab Hill junction to Cowley junction

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lxxv A417 Missing Link | HE551505 Highways England

Figure B-14 Fuller’s Earth Formation groundwater monitoring, Ermin Way

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lxxvi A417 Missing Link | HE551505 Highways England

Figure B-15 Inferior Oolite Group groundwater monitoring – Ch 1+700 to Ch 2+250, Air Balloon

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lxxvii A417 Missing Link | HE551505 Highways England

Figure B-16 Inferior Oolite Group groundwater monitoring – Ch 2+250 to Ch 2+750, Air Balloon

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lxxviii A417 Missing Link | HE551505 Highways England

Figure B-17 Inferior Oolite Group groundwater monitoring – Barrow Wake

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lxxix A417 Missing Link | HE551505 Highways England

Figure B-18 Inferior Oolite Group groundwater monitoring – Barrow Wake

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lxxx A417 Missing Link | HE551505 Highways England

Figure B-19 Inferior Oolite Group groundwater monitoring – B4070 realignment

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lxxxi A417 Missing Link | HE551505 Highways England

Figure B-20 Inferior Oolite Group groundwater monitoring – Shab Hill junction

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lxxxii A417 Missing Link | HE551505 Highways England

Figure B-21 Inferior Oolite Group groundwater monitoring – Shab Hill junction

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lxxxiii A417 Missing Link | HE551505 Highways England

Figure B-22 Inferior Oolite Group groundwater monitoring – Shab Hill junction to Cowley junction

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lxxxiv A417 Missing Link | HE551505 Highways England

Figure B-23 Lias Group, Bridport Sand Formation groundwater monitoring – Air Balloon

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lxxxv A417 Missing Link | HE551505 Highways England

Figure B-24 Lias Group, Bridport Sand Formation groundwater monitoring – Barrow Wake

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lxxxvi A417 Missing Link | HE551505 Highways England

Figure B-25 Lias Group groundwater monitoring – CH1+000 to CH1+400 (northern side of A417) – mid Crickley Hill

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lxxxvii A417 Missing Link | HE551505 Highways England

Figure B-26 Lias Group groundwater monitoring – CH1+000 to CH1+400 (northern side of A417) – mid Crickley Hill

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lxxxviii A417 Missing Link | HE551505 Highways England

Figure B-27 Lias Group groundwater monitoring – CH1+000 to CH1+400 (southern side of A417) – mid Crickley Hill

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE lxxxix A417 Missing Link | HE551505 Highways England

Figure B-28 Lias Group groundwater monitoring – Air Balloon

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE xc A417 Missing Link | HE551505 Highways England

Figure B-29 Lias Group groundwater monitoring – CH1+000 to CH1+400 (southern side of A417) – Upper Crickley Hill

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE xci A417 Missing Link | HE551505 Highways England

Appendix C Water quality results

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE xcii A417 Missing Link | HE551505 Highways England

Figure C-1 Mass movement deposits groundwater quality

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE xciii A417 Missing Link | HE551505 Highways England

Figure C-2 Mass movement deposits/Lias Group mudstone groundwater quality

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE xciv A417 Missing Link | HE551505 Highways England

Figure C-3 Great Oolite limestone groundwater quality

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE xcv A417 Missing Link | HE551505 Highways England

Figure C-4 Fuller’s Earth Formation groundwater quality

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE xcvi A417 Missing Link | HE551505 Highways England

Figure C-5 Inferior Oolite Group groundwater quality

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE xcvii A417 Missing Link | HE551505 Highways England

Figure C-6 Bridport Sand Formation groundwater quality

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE xcviii A417 Missing Link | HE551505 Highways England

Figure C-7 Lias Group mudstones groundwater quality

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE xcix A417 Missing Link | HE551505 Highways England

References

1 Geotechnical Engineering Ltd (2019). HE551505 A417 Missing Link Ground Investigation, Factual Report on Ground Investigation 2 Environment Agency (2013). Severn Corridor Abstraction Licensing Strategy, Reference No. LIT7848, [Online]. Available at: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/291406/LI T_7848_c0b50e.pdf (Accessed 11/02/2020) 3 Environment Agency (2019). Cotswolds Abstraction Licensing Strategy, [Online]. Available at: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/796112/C otswolds-Abstraction-Licensing-Strategy.pdf (Accessed 11/02/2020) 4 Environment Agency (2013). Severn Vale Abstraction Licensing Strategy, Reference No. LIT3254, [Online]. Available at: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/291759/LI T_3254_9f2621.pdf (Accessed 11/02/2020) 5 Environment Agency (2017). Aquifers [Online]. Available at: http://apps.environment- agency.gov.uk/wiyby/117020.aspx (Accessed 11/02/2020) 6 Environment Agency (2019). Aquifer Designation Map (Bedrock Geology) [Online]. Available at: https://magic.defra.gov.uk/magicmap.aspx (Accessed 11/02/2020) 7 Environment Agency (2019). Aquifer Designation Map (Bedrock Geology). [Online] Available at: https://magic.defra.gov.uk/magicmap.aspx (Accessed 11/02/2020) 8 Jones, H K, Morris, B L, Cheney, C S, Brewerton, L J, Merrin, P D, Lewis, M A, MacDonald, A M, Coleby, L M, Talbot, J C, McKenzie, A A, Bird, M J, Cunningham, J, and Robinson, V K (2000). The physical properties of minor aquifers in England and Wales. British Geological Survey Technical Report, WD/00/4. 234pp. Environment Agency R and D Publication 68. 9 Environment Agency (2019). Aquifer Designation Map (Bedrock Geology). [Online] Available at: https://magic.defra.gov.uk/magicmap.aspx (Accessed 11/02/2020) 10 Maurice L., Barron A. J. M., Lewis M. A. and Robins N. S. (2008). The geology and hydrogeology of the Jurassic limestones in the Stroud-Cirencester area with particular reference to the position of the groundwater divide, British Geological Survey Commissioned Report, CR/08/146. 11 Environment Agency (2019). Catchment Data Explorer [Online]. Available at: https://environment.data.gov.uk/catchment-planning/ (Accessed 11/01/2021) 12 Environment Agency (2019). Catchment Data Explorer [Online]. Available at: https://environment.data.gov.uk/catchment-planning/ (Accessed 11/01/2021) 13 British Geological Survey (2019). Superficial Geology 1:50,000 scale map [Online]. Available at: https://www.bgs.ac.uk/products/digitalmaps/digmapgb_50.html (Accessed 11/02/2020) 14 British Geological Survey (2019). Mass Movement Deposits 1:50,000 scale map [Online]. Available at: https://www.bgs.ac.uk/products/digitalmaps/digmapgb_50.html (Accessed 11/02/2020) 15 British Geological Survey (2019). Bedrock Geology 1:50,000 scale map [Online]. Available at: https://www.bgs.ac.uk/products/digitalmaps/digmapgb_50.html (Accessed 11/02/2020) 16 Paul, J.D. (2014). The relationship between spring discharge, drainage and periglacial geomorphology of the Frome valley, central Cotswolds, UK, Proceedings of the Geologists’ Association, Vol. 125, pp. 182-194 17 Self, C.A. and Boycott, A. (2004). Landslip Caves of the Middle Cotswolds, Proceedings of the University of Bristol Spelæological Society, Vol. 23, Issue 2, pp 97-117 18 Farrant, A.R., Noble, S.R., Barron, A.J.M., Self, C.A., Grebby, S.R. (2014). Speleothem U-series constraints on scarp retreat rates and landscape evolution: an example from the Severn Valley and Cotswold Hills gull-caves, UK. 19 Jones, H.K., Morris, B.L., Cheney, C.S., Brewerton, L.J., Merrin, P.D., Lewis, M.A., MacDonald, A.M., Coleby, L.M., Talbot, J.C., McKenzie, A.A., Bird, M.J., Cunningham, J. and Robinson, V.K. (2000). The physical properties of minor aquifers in England and Wales. British Geological Survey Technical Report, WD/00/4. 234pp. Environment Agency R and D Publication 68. 20 Environment Agency (2017). Nitrate Vulnerable Zones (NVZ) 2017 – Combined (Final Designations), [Online] Available at: https://magic.defra.gov.uk/magicmap.aspx (Accessed 11/02/2020)

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE c A417 Missing Link | HE551505 Highways England

21 Environment Agency (2017). Nitrate Vulnerable Zones (NVZ) 2017 – Combined (Final Designations), [Online] Available at: https://magic.defra.gov.uk/magicmap.aspx (Accessed 11/02/2020) 22Environment Agency (2017). Nitrate Vulnerable Zones (NVZ) 2017 – Combined (Final Designations), [Online] Available at: https://magic.defra.gov.uk/magicmap.aspx (Accessed 11/02/2020) 23 Morgan-Jones, J. and Eggboro, M.D., 1981, The hydrogeochemistry of the Jurassic limestones in Gloucestershire, England, Quarterly Journal of Engineering Geology, Vol. 14, pp. 25-39 24 Neumann, I., Brown, S., Smedley, P. and Besien, T (2003). Baseline Report Series: 7. The Great and Inferior Oolite of the Cotswolds District, British Geological Survey Commissioned Report No. CR/03/202c 25 Neumann, I., Brown, S., Smedley, P. and Besien, T (2003). Baseline Report Series: 7. The Great and Inferior Oolite of the Cotswolds District, British Geological Survey Commissioned Report No. CR/03/202c 26 Neumann, I., Brown, S., Smedley, P. and Besien, T (2003). Baseline Report Series: 7. The Great and Inferior Oolite of the Cotswolds District, British Geological Survey Commissioned Report No. CR/03/202c 27 Environment Agency (2019). Catchment Data Explorer [Online]. Available at: https://environment.data.gov.uk/catchment-planning/ (Accessed 11/02/2020) 28 Neumann, I., Brown, S., Smedley, P. and Besien, T (2003). Baseline Report Series: 7. The Great and Inferior Oolite of the Cotswolds District, British Geological Survey Commissioned Report No. CR/03/202c 29 Neumann, I., Brown, S., Smedley, P. and Besien, T (2003). Baseline Report Series: 7. The Great and Inferior Oolite of the Cotswolds District, British Geological Survey Commissioned Report No. CR/03/202c 30 Neumann, I., Brown, S., Smedley, P. and Besien, T (2003). Baseline Report Series: 7. The Great and Inferior Oolite of the Cotswolds District, British Geological Survey Commissioned Report No. CR/03/202c 31 Morgan-Jones, J. and Eggboro, M.D. (1981). The hydrogeochemistry of the Jurassic limestones in Gloucestershire, England, Quarterly Journal of Engineering Geology, Vol. 14, pp. 25-39 32 Maurice L., Barron A. J. M., Lewis M. A. and Robins N. S. (2008). The geology and hydrogeology of the Jurassic limestones in the Stroud-Cirencester area with particular reference to the position of the groundwater divide, British Geological Survey Commissioned Report, CR/08/146. 33 Maurice L., Barron A. J. M., Lewis M. A. and Robins N. S. (2008). The geology and hydrogeology of the Jurassic limestones in the Stroud-Cirencester area with particular reference to the position of the groundwater divide, British Geological Survey Commissioned Report, CR/08/146. 34 Environment Agency (2019). Consented Discharges to Controlled Waters with Conditions [Online]. Available at: https://data.gov.uk/dataset/b3df52da-3e27-4343-9ec3-e630a9cbb52c/consented-discharges-to- controlled-waters-with-conditions (Accessed 11/02/2020) 35 Environment Agency (2015). Part 1: Severn River Basin District River Basin Management Plan, policy paper 36 Environment Agency (2015). Part 1: Thames River Basin District River Basin Management Plan, policy paper 37 Maurice L., Barron A.J.M., Lewis M.A. and Robins N.S. (2008). The geology and hydrogeology of the Jurassic limestones in the Stroud-Cirencester area with particular reference to the position of the groundwater divide, British Geological Survey Commissioned Report, CR/08/146. 38 Mott MacDonald Sweco Joint Venture (2019). Preliminary Groundwater Report, Doc No. HE551505- MMSJV-HGT-000-RP-CE-00004 39 Mott MacDonald Sweco Joint Venture (2019). Preliminary Groundwater Report, Doc No. HE551505- MMSJV-HGT-000-RP-CE-00004 40 Sumbler, M.G., Barron, A.J.M. & Morigi, A.N. 2000. Geology of the Cirencester district. Memoir for 1:50,000 Geological Sheet 235 (England and Wales). British Geological Survey, London. 41 Sumbler, M.G., Barron, A.J.M. & Morigi, A.N. 2000. Geology of the Cirencester district. Memoir for 1:50,000 Geological Sheet 235 (England and Wales). British Geological Survey, London. 42 Sumbler, M.G., Barron, A.J.M. & Morigi, A.N. 2000. Geology of the Cirencester district. Memoir for 1:50,000 Geological Sheet 235 (England and Wales). British Geological Survey, London. 43 Sumbler, M.G., Barron, A.J.M. & Morigi, A.N. 2000. Geology of the Cirencester district. Memoir for 1:50,000 Geological Sheet 235 (England and Wales). British Geological Survey, London. 44 Natural England, 2019, Crickley Hill and Barrow Wake SSSI Citation [Online] https://designatedsites.naturalengland.org.uk/PDFsForWeb/Citation/1001395.pdf [Accessed 2019] 45 MMSJV, A417 Missing Link, NVC Woodland Survey Report 2019

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE ci A417 Missing Link | HE551505 Highways England

46 Vegetation Survey & Assessment Ltd, A417 Missing Link at Air Balloon Cross, Botanical Assessment, [September 2019] 47 Natural England, 2019, Bushley Muzzard, Brimpsfield SSSI Citation [Online] https://designatedsites.naturalengland.org.uk/PDFsForWeb/Citation/1003794.pdf [Accessed 2019] 48 Vegetation Survey & Assessment Ltd, A417 Missing Link at Air Balloon Cross, Botanical Assessment, [September 2019] 49 Ford, D, & Williams, P., 2007, Karst hydrogeology and geomorphology, John Wiley & Sons, Ltd, Chichester. 50 Ford, D, & Williams, P., 2007, Karst hydrogeology and geomorphology, John Wiley & Sons, Ltd, Chichester. 51 Farr, G., Graham, J. & Stratford, C., 2014, Survey characterisation and condition assessment of Palustriella dominated springs H7220 Petrifying springs with tufa formation (Cratoneurion). Centre for Ecology and Hydrology and the British Geological Survey (NERC) 52 Farr, G., Graham, J. & Stratford, C., 2014, Survey characterisation and condition assessment of Palustriella dominated springs H7220 Petrifying springs with tufa formation (Cratoneurion). Centre for Ecology and Hydrology and the British Geological Survey (NERC) 53 Paul, J.D., 2014. The relationship between spring discharge, drainage and periglacial geomorphology of the Frome valley, central Cotswolds, UK, Proceedings of the Geologists’ Association, Vol. 125, pp. 182-194 54 Paul, J.D., 2014. The relationship between spring discharge, drainage and periglacial geomorphology of the Frome valley, central Cotswolds, UK, Proceedings of the Geologists’ Association, Vol. 125, pp. 182-194 55 Neumann, I, Brown, S., Smedley, P. & Besien, T, 2003. Baseline Report Series: 7. The Great and Inferior Oolite of the Cotswolds District, British Geological Survey Commissioned Report No. CR/03/202c 56 Mansur, C.I. & Kaufman, R.R., 1962, Dewatering, published in Foundation Engineering, McGraw-Hill, New York, pp. 241-350.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000004 | C01, A3 | 19/05/21 APPENDIX PAGE cii A417 Missing Link TR010056

6.4 Environmental Statement Appendix 13.8 GWDTEs Assessment

Planning Act 2008

APFP Regulation 5(2)(a) Infrastructure Planning (Applications: Prescribed Forms and Procedure) Regulations 2009

Volume 6

May 2021 A417 Missing Link | HE551505 Highways England

Infrastructure Planning

Planning Act 2008

The Infrastructure Planning (Applications: Prescribed Forms and Procedure) Regulations 2009

Regulation 5(h)

A417 Missing Link

Development Consent Order 202[x]

6.4 Environmental Statement Appendix 13.8 GWDTEs Assessment

Regulation Number: 5(2)(a) Planning Inspectorate TR010056 Scheme Reference Application Document Reference 6.4 Author: A417 Missing Link

Version Date Status of Version C01 May 2021 Application Submission A417 Missing Link | HE551505 Highways England

Table of Contents Pages 1 Introduction i 2 Methodology i 3 Baseline i 4 Step 1 - Identify potential linkages ii 5 Summary ii References iii A417 Missing Link | HE551505 Highways England

1 Introduction 1.1.1 A groundwater dependant terrestrial ecosystem (GWDTE) is defined as1: “A terrestrial ecosystem of importance at Member State level that is directly dependent on the water level in or flow of water from a groundwater body (that is, in or from the saturated zone). Such an ecosystem may also be dependent on the concentrations of substances (and potential pollutants) within that groundwater body, but there must be a direct hydraulic connection with the groundwater body.” 1.1.2 This document describes the assessment of risk to GWDTEs resulting from the construction and operation of the scheme. 2 Methodology

Groundwater dependent terrestrial ecosystems assessment 2.1.1 An assessment of GWDTEs has been carried out in line with the guidance provided in Appendix B of DMRB LA 113. 2.1.2 The methodology has a stepped, risk-based approach which depends upon establishing linkages between potential impacts from the road development on the hydrological and hydrogeological regime and a GWDTE:  Step 1 - Identify potential linkages  Step 2 - Assess GWDTE importance (if required)  Step 3 - Assess potential impacts (if required)

Baseline 2.1.3 GWDTEs were identified using the Phase 1 and National Vegetation Classification (NVC) surveys conducted for the scheme and provided in ES Appendix 8.3 NVC Woodland Survey Report (Document Reference 6.4) and the habitat communities at protected sites within the scheme’s study area. The habitat communities present were compared with the communities listed in Annex 1 of the UKTAG report1, identifying that have a potential to be groundwater dependant. 2.1.4 The hydrogeological conceptual model developed for the scheme is presented in ES Appendix 13.7 Hydrogeological impact assessment (Document Reference 6.4) and was used to identify potential linkages. 3 Baseline

Identified GWDTEs and potential GWDTEs 3.1.1 NVC surveys indicated that Bushley Muzzard Site of Special Scientific Interest (SSSI) supports NVC community M22 (Juncus subnodulosus – Cirsium palustre fen meadow), which has a potential to be moderately dependent on groundwater. 3.1.2 No potentially groundwater dependent NVC communities were noted at Crickley Hill SSSI. Crickley Hill and Barrow Wake SSSI is designated for calcareous grassland habitats, broadleaved woodland (including beech woodland) and nationally important rock exposures2. It is located adjacent to the existing A417 on Crickley Hill and at Barrow Wake. Springs supplying the tributary of Norman’s Brook are outside the protected area downgradient and south of Barrow Wake. The National Vegetation Classification (NVC) code for beech trees (Fagus

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000035 | C01, A3 | 11/03/21 APPENDIX PAGE i A417 Missing Link | HE551505 Highways England

sylvatica) is ‘W12’, which is not classified as being groundwater-dependant according to relevant guidance3. The ecological surveys completed for the scheme did not identify the presence of potentially-groundwater-dependent habitats4. 3.1.3 Cotswold Commons and Beechwoods SSSI and Cotswold Beechwoods Special Area of Conservation (SAC), located to the west and downslope of the B4070. As mentioned above the beech woodland is not classified as a groundwater- dependent habitat, however these designated sites include areas of vegetation dependent on springs and seepage from high groundwater levels. These areas of vegetation are associated with some nationally rare invertebrate species. These protected areas extend from the south-east of Birdlip to High Brotheridge and include springs supplying the Horsbere Brook. 3.1.4 Witcombe Reservoirs, at the foot of the escarpment, is primarily supplied by spring-fed watercourses. It discharges to the Horsbere Brook. There are a number of small ponds in the area that may be partially groundwater-dependent or fed by springs. 4 Step 1 - Identify potential linkages 4.1.1 The hydrogeological conceptual model presented in ES Appendix 13.7 Hydrogeological impact assessment (Document Reference 6.4) identified that the drawdown in groundwater levels associated with cuttings along the scheme, in particular the Stockwell-Nettleton Bottom cutting, does not extend to Bushley Muzzard SSSI or any other above-mentioned groundwater fed systems. 4.1.2 The calculated drawdown encroaches on the Crickley Hill and Borrow Wake SSSI area. However, no groundwater dependent species have been identified in that area and therefore this will not pose a risk to this protected area. In addition, based on groundwater monitoring data from near Crickley Hill and Barrow Wake SSSI, the groundwater is at least 20 metres below ground level (mbgl) and is anticipated to result in a relatively deep unsaturated zone below the SSSI. Consequently, an interaction between groundwater and root systems of beech trees is unlikely. The beech woodlands are therefore considered to be fed by near-surface flow and precipitation. 4.1.3 The conceptual model demonstrates there is no linkage between the potential impacts from the road to groundwater levels and the GWDTE. 5 Summary 5.1.1 It is considered that the scheme does not pose a risk to the identified or potential GWDTEs and no further assessment is required.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000035 | C01, A3 | 11/03/21 APPENDIX PAGE ii A417 Missing Link | HE551505 Highways England

References

1 UK Technical Advisory Group (2004). Guidance on the identification and risk assessment of groundwater dependant terrestrial ecosystems (Working Draft Rev. 5) [Online]. Available at: https://www.wfduk.org/sites/default/files/Media/Characterisation%20of%20the%20water%20environme nt/Risk%20assessment%20of%20terrestrial%20ecosystems%20groundwater_Draft_210104.pdf (Accessed 25/01/21). 2 Natural England (2021). Crickley Hill and Barrow Wake SSSI Citation [Online]. Available at: https://designatedsites.naturalengland.org.uk/PDFsForWeb/Citation/1001395.pdf (Accessed 25/01/2021). 3 UK Technical Advisory Group (2004). Guidance on the identification and risk assessment of groundwater dependant terrestrial ecosystems (Working Draft Rev. 5) [Online]. Available at: https://www.wfduk.org/sites/default/files/Media/Characterisation%20of%20the%20water%20environme nt/Risk%20assessment%20of%20terrestrial%20ecosystems%20groundwater_Draft_210104.pdf (Accessed 25/01/2021). 4 Vegetation Survey & Assessment Ltd (2019). A417 Missing Link at Air Balloon Cross, Botanical Assessment

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000035 | C01, A3 | 11/03/21 APPENDIX PAGE iii A417 Missing Link TR010056

6.4 Environmental Statement Appendix 13.9 Non-Significant Effects

Planning Act 2008

APFP Regulation 5(2)(a) Infrastructure Planning (Applications: Prescribed Forms and Procedure) Regulations 2009

Volume 6

May 2021 A417 Missing Link | HE551505 Highways England

Infrastructure Planning

Planning Act 2008

The Infrastructure Planning (Applications: Prescribed Forms and Procedure) Regulations 2009

Regulation 5(h)

A417 Missing Link

Development Consent Order 202[x]

6.4 Environmental Statement Appendix 13.9 Non -Significant Effects

Regulation Number: 5(2)(a) Planning Inspectorate TR010056 Scheme Reference Application Document Reference 6.4 Author: A417 Missing Link

Version Date Status of Version C01 May 2021 Application Submission A417 Missing Link | HE551505 Highways England

Table of Contents Pages 1 Non-Significant Effects Summary i 1.1 Summary of non-significant effects – Surface water – Construction i 1.2 Summary of non-significant effects – Groundwater – Construction ii 1.3 Summary of non-significant effects – Surface Water – Operation xii 1.4 Summary of non-significant effects – Groundwater – Operation xiv A417 Missing Link | HE551505 Highways England

1 Non-Significant Effects Summary

1.1 Summary of non-significant effects – Surface water – Construction

Potential impact Receptor Value Design and mitigation measures Magnitude of Significance of impact effect Alteration to baseflows Tributary of Norman’s Brook High Mitigation listed in Annex G of ES Appendix Negligible Slight adverse as a result of 2.1 EMP (Document Reference 6.4) will Unnamed tributaries of River Medium Slight adverse embankments during maintain existing flow regime Churn construction impacting surface water quantity Unnamed tributary of River High Slight adverse Frome Alteration to baseflows Tributary of Norman’s Brook High Cutting or structure drainage maintains flow Negligible Slight adverse as a result of cuttings directions and existing catchment areas Unnamed tributaries of River Medium Slight adverse and structures during wherever possible. Churn construction impacting Detailed assessment of groundwater-surface surface water quantity Unnamed tributary of River High water interaction during detailed design. Slight adverse Frome Adherence to Annex G of ES Appendix 2.1 Unnamed tributary of Horsbere Medium EMP (Document Reference 6.4). Slight adverse Brook Pollution incident as a Tributary of Norman’s Brook High Annex G of ES Appendix 2.1 EMP (Document Negligible Slight adverse result of construction Reference 6.4) includes best practice Unnamed tributaries of River Medium Slight adverse impacting surface water measures for the storage of hazardous Churn quality substances, the siting of higher risk activities Unnamed tributary of River High (e.g. vehicle washdown areas) and the Slight adverse Frome maintenance of plant Unnamed tributary of Horsbere Medium Slight adverse Brook Flood risk to the site Existing A417 road Very High Annex G of ES Appendix 2.1 EMP (Document No change Neutral during construction Reference 6.4)

Flood risk from the site Residential properties High Surface water generated across the site would No change Neutral during construction surrounding the scheme extent be managed by construction drainage

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000037 | C01, A3 | 15/03/21 APPENDIX PAGE i A417 Missing Link | HE551505 Highways England

Potential impact Receptor Value Design and mitigation measures Magnitude of Significance of impact effect Colleges, High Schools and High (including suitably sized temporary settlement Primary Schools surrounding and attenuation basins, drainage ditches and scheme extent culverts). This will be installed early in the construction period as per Annex G of ES Land used for agriculture Medium Appendix 2.1 EMP (Document Reference 6.4), surrounding the scheme extent which would manage surface and groundwater flooding to ensure that flood risk does not increase as a result of the scheme.

1.2 Summary of non-significant effects – Groundwater – Construction

Potential impact Receptor Value Design and mitigation Magnitude Significance of effect measures of impact Accidental spillage during Superficial deposits - High Annex G of the EMP (Appendix Negligible Slight adverse construction Secondary A aquifer 2.1) includes best practice measures for the storage of Lias Group - Secondary Medium Slight adverse hazardous substances, the siting (undifferentiated) aquifer of higher risk activities (e.g. Inferior Oolite - Principal High vehicle washdown areas) and Slight adverse aquifer the maintenance of plant Great Oolite - Principal High Slight adverse aquifer Pollution incident as a result of Superficial deposits - High Mitigation listed in Annex G of Negligible Slight adverse construction Secondary A aquifer ES Appendix 2.1 EMP (Document Reference 6.4) Lias Group - Secondary Medium Slight adverse (undifferentiated) aquifer Inferior Oolite - Principal High Slight adverse aquifer Great Oolite - Principal High Slight adverse aquifer

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000037 | C01, A3 | 15/03/21 APPENDIX PAGE ii A417 Missing Link | HE551505 Highways England

Potential impact Receptor Value Design and mitigation Magnitude Significance of effect measures of impact Alluvium - Secondary A Medium Slight adverse aquifer Cheltenham Sand and Gravel - Secondary A Medium Slight adverse aquifer Great Oolite limestone - High Slight adverse Principal aquifer Inferior Oolite - Principal High Slight adverse aquifer Lias Group - Secondary Medium Slight adverse (undifferentiated) aquifer Temporary works associated Well No. G199, historic with construction of cuttings, Low Neutral embankments and drainage disused well Mitigation listed in Annex G of basins have the potential to Dry valley (G3) (new fault) High ES Appendix 2.1 EMP Negligible Slight adverse affect groundwater quality, (Document Reference 6.4) although this is likely to be very Shab Hill dry valley localised and temporary. Medium Slight adverse (G146, G183) Springs and seepages in tributary of River Churn headwaters (G4, G97- Medium Slight adverse G99, G145, G146, G174, G148, G179, G180, G181) Springs and seepages in tributary of River Frome headwaters (east) (G143, High Slight adverse G150, G147, G173, G100, G219, G223, G222)

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000037 | C01, A3 | 15/03/21 APPENDIX PAGE iii A417 Missing Link | HE551505 Highways England

Potential impact Receptor Value Design and mitigation Magnitude Significance of effect measures of impact Temporary construction works for the Cotswolds Way crossing piled foundations have the potential to affect groundwater Inferior Oolite - Principal High Negligible Slight adverse quality, particularly if fissures, aquifer gulls or karst are encountered during construction and pile grout has the potential to Adherence to ES Appendix 2.1 escape through these flow EMP (Document Reference 6.4), paths. voids treatment protocol and Gloucester Way crossing, FWRA Cowley and Stockwell overbridges pile foundations Baunton public water High Negligible Slight adverse have also the potential to affect supply, SPZ3 groundwater quality within the Inferior Oolite during construction, however this will be localised and temporary. Construction of widening the existing A417 has the potential to cause minor drawdown within Cheltenham Sand and the aquifer, however the Gravel - Secondary A Medium None Negligible Slight adverse widening is at grade with the aquifer existing A417 so the drawdown impacts are anticipated to be negligible Construction works will only extend into the superficial deposits overlying the low water Lias Group - Secondary Medium None No change Neutral bearing Lias Group, which will (undifferentiated) aquifer protect the Lias Group in terms of both groundwater flow

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000037 | C01, A3 | 15/03/21 APPENDIX PAGE iv A417 Missing Link | HE551505 Highways England

Potential impact Receptor Value Design and mitigation Magnitude Significance of effect measures of impact Springs in the upper escarpment are likely fed from shallow groundwater flows originating from the upper Inferior Oolite aquifer. Drainage introduced as part of Springs in tributary of stabilisation measures at Norman's Brook - upper Temporary drainage design to Crickley Hill is designed to Crickley Hill escarpment High maintain water balance within Negligible Slight adverse drawdown the water level in springs and seepages specific sub-catchment cohesive superficial deposits. If (G206 and 83) these drains intersect permeable deposits they have the potential to intercept groundwater flow that contributes to springs. Construction of cutting between Ch. 1+700 and 3+000 is likely to have an impact on groundwater flow paths, particularly near the Adherence to ES Appendix 2.1 Inferior Oolite - Principal Crickley Hill escarpment where High EMP (Document Reference 6.4), Negligible Slight adverse aquifer it may intercept fissures and and voids treatment protocol gulls that transport groundwater to groundwater dependent features at Crickley Hill. Springs are likely to be fed by groundwater flowing through the fault, which is receiving groundwater from the Inferior Adherence to ES Appendix 2.1 Oolite aquifer, upgradient of EMP (Document Reference 6.4) Springs in tributary to cutting Ch. 1+700 to 3+000. The Temporary drainage design to Norman's Brook - fault High Negligible Slight adverse springs are outside radius of maintain water balance within springs (16, 17, 18, 19) influence boundary of this specific sub-catchment and cutting, however there may be voids treatment protocol reduction in peak winter flow if cutting intersects karst in drainage invert

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000037 | C01, A3 | 15/03/21 APPENDIX PAGE v A417 Missing Link | HE551505 Highways England

Potential impact Receptor Value Design and mitigation Magnitude Significance of effect measures of impact

Well No. 83, potentially Well located in an area not fed by perched anticipated to be impacted by groundwater/spring flow cutting Ch. 1+700 to 3+000 Low None No change Neutral from Inferior Oolite (outside scheme footprint of limestone. The purpose of calculated drawdown). the well is unknown. Construction of cutting Ch. 1+700 to 3+000 is unlikely to Well No. G199, historic have an impact on groundwater Low None No change Neutral disused well flow and levels at Well G199 location. Construction of the cutting Ch. 1+700 to 3+000 likely to intercept groundwater that is Springs and seepages in within the Severn Vale tributary of River Churn Medium None No change Neutral groundwater catchment and headwaters (G99, G97) does not contribute to groundwater spring flow. Construction of cutting Ch. 1+700 to 3+000 is unlikely to have an impact on groundwater flow and levels at the dry valley. The dry valley is anticipated to be up-gradient of the cutting Dry valley (G3) (new fault) High None No change Neutral with respect to local groundwater flow paths. The dry valley is beyond the maximum drawdown radius of influence, induced by the cutting.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000037 | C01, A3 | 15/03/21 APPENDIX PAGE vi A417 Missing Link | HE551505 Highways England

Potential impact Receptor Value Design and mitigation Magnitude Significance of effect measures of impact Excavation and dewatering impacts due to the Shab Hill junction on/off ramp cuttings on Inferior Oolite - Principal groundwater levels are unlikely High None No change Neutral aquifer to have an impact as the cutting level is above the maximum anticipated groundwater level. The cuttings assessment shows that this feature is outside of the Temporary drainage design to potential dewatering zone of Shab Hill dry valley Medium maintain water balance within Negligible Slight adverse influence, however there may (G146) specific sub-catchment be potential reduction in peak winter spring flow The public water supply is abstracting water from the Inferior Oolite aquifer, which is overlain by the Fuller's Earth Formation aquitard and Great Oolite limestone in the Baunton public water Stockwell-Nettleton area. The High None No change Neutral supply, SPZ3 cuttings Ch. 3+200 and 5+000 will be founded within the Great Oolite Group and hydraulically disconnected from the Inferior Oolite so potential impacts to flow are negligible. Ch. 3+200 to 5+000 cuttings will Great Oolite limestone - High Temporary drainage design to Negligible Slight adverse result in removal of Great Oolite Principal aquifer maintain water balance within aquifer within the Severn Vale specific sub-catchment catchment which will cause a reduction in the resource extent.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000037 | C01, A3 | 15/03/21 APPENDIX PAGE vii A417 Missing Link | HE551505 Highways England

Potential impact Receptor Value Design and mitigation Magnitude Significance of effect measures of impact Excavation and dewatering of cuttings between Ch. 3+200 and 5+000 will result in removal of Great Oolite aquifer within the Severn Vale catchment which will cause a reduction in the Temporary drainage design to resource extent and recharge Alluvium - Secondary A Medium maintain water balance within Negligible Slight adverse area that feeds into the alluvium aquifer specific sub-catchment aquifer. Potential drawdown impacts from Ch. 3+200 to 5+000 cuttings are assessed as negligible as the alluvium is beyond the maximum calculated radius of influence Temporary drainage design to Springs and seepages in maintain water balance within tributary of River Churn Medium specific sub-catchment Negligible Slight adverse Construction of cuttings Ch. headwaters (G174, G4, 3+200 to 5+000 will be within G5, G6, G77) the Great Oolite limestone. Groundwater that would run-off Temporary drainage design to from the Great Oolite, over the maintain water balance within Fuller's Earth Formation and Springs and seepages in specific sub-catchment into the headwaters will be tributary of River Frome intercepted by the drainage headwaters (east) (G143, High Negligible Slight adverse design. G150, G147, G173, G100, G219, G223, G222)

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000037 | C01, A3 | 15/03/21 APPENDIX PAGE viii A417 Missing Link | HE551505 Highways England

Potential impact Receptor Value Design and mitigation Magnitude Significance of effect measures of impact Construction of cuttings Ch. Temporary drainage design to 3+200 to 5+000 will be within maintain water balance within the Great Oolite limestone. The specific sub-catchment Springs and seepages in cuttings assessment (HIA) tributary of River Frome shows that these springs are headwaters (east) (G150, High Negligible Slight adverse outside of the potential G147, G173, G100, G219, dewatering zone of influence, G220, G221) however there may be potential reduction in peak winter spring flow. Drawdown in groundwater Bushley Muzzard SSSI High Not required No change Neutral levels associated with scheme’s and other springs and cuttings Ch. 3+200 to 5+000 seepages in tributary of impacting Groundwater River Frome headwaters Dependent Terrestrial (west) Ecosystem These springs in the direct path Temporary drainage design to Springs in tributary of of the scheme alignment. They maintain water balance within Norman's Brook springs will be lost during construction in specific sub-catchment and seepages (61, 69, 72, High Negligible Slight adverse addition to the tributary of 78, 80, G2, G17, G20, Norman's Brook that they feed G151) into. The construction of widening the Temporary drainage design to existing A417 will result in the maintain water balance within loss of this feature, which is a specific sub-catchment Seepage G138 Low Negligible Neutral localised feature not supporting any groundwater dependent habitats.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000037 | C01, A3 | 15/03/21 APPENDIX PAGE ix A417 Missing Link | HE551505 Highways England

Potential impact Receptor Value Design and mitigation Magnitude Significance of effect measures of impact These springs in the direct path Temporary drainage design to of the scheme alignment. maintain water balance within Construction of the Shab Hill specific sub-catchment junction embankment will include a drainage blanket Shab Hill dry valley Medium Negligible Slight adverse foundation that will allow for (G146, G183) groundwater flow across the dry valley. Impacts on flow across the valley are likely to be negligible. This spring is in the footprint of Springs in tributary of Medium Temporary drainage design to Negligible Slight adverse an embankment and will be River Churn headwaters maintain water balance within buried during construction. (G174) specific sub-catchment Construction of Cotswolds Way crossing piled foundation is likely to have an impact on groundwater flow paths, Adherence to ES Appendix 2.1 particularly near the Crickley Hill Inferior Oolite - Principal EMP (Document Reference 6.4), High Negligible Slight adverse escarpment where it may aquifer FWRA and voids treatment intercept fissures and gulls that protocol transport groundwater to groundwater dependent features at Crickley Hill. Construction of the Cowley and Stockwell overbridges pile foundation is likely to intercept the Inferior Oolite limestone underlying the Great Oolite Inferior Oolite - Principal limestone and Fuller's Earth High FWRA Negligible Slight adverse aquifer Formation. Construction is likely to be above the maximum groundwater level so impacts on groundwater flow and level are likely to be negligible.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000037 | C01, A3 | 15/03/21 APPENDIX PAGE x A417 Missing Link | HE551505 Highways England

Potential impact Receptor Value Design and mitigation Magnitude Significance of effect measures of impact

Construction of the Cowley and Springs and seepages in Adherence to ES Appendix 2.1 Stockwell overbridge pile tributary of River Churn Medium EMP (Document Reference 6.4) Negligible Slight adverse foundation may impact headwaters (G174, G4, and FWRA. groundwater flow and level in G5, G6, G77) the Great Oolite limestones. However, the impact is likely to be very local. As the Springs and seepages in foundations piles are likely to be tributary of River Frome Adherence to ES Appendix 2.1 constructed in groups with gaps headwaters (east) (G143, High EMP (Document Reference 6.4) Negligible Slight adverse in between individual piles, G150, G147, G173, G100, and FWRA impact on groundwater flow is G219, G223, G222) likely to be negligible. The Bushley Muzzard SSSI is fed by groundwater springs at the Great Oolite limestone and Fuller's Earth formation, which feed into the headwaters of the Bushley Muzzard SSSI River Frome tributary (west). and associated springs Underlying Head Deposits may (G102, G25) also feeding High None No impact Neutral allow for some perching of to tributary of River Frome shallow groundwater. The SSSI headwaters (west) is unlikely to be directly hydraulically connected to the proposed works on the opposite side of the River Frome headwater valley (east).

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000037 | C01, A3 | 15/03/21 APPENDIX PAGE xi A417 Missing Link | HE551505 Highways England

1.3 Summary of non-significant effects – Surface Water – Operation

Magnitude of Significance of Potential impact Receptor Value Design and mitigation measures impact effect Alteration to baseflow of Tributary of Norman’s High Mitigation listed in Annex G of ES Appendix 2.1 Negligible Slight adverse springs as a result of Brook EMP (Document Reference 6.4) will maintain embankments during existing flow regime Unnamed tributaries of Medium Slight adverse operation impacting surface River Churn water quantity Unnamed tributary of High Slight adverse River Frome Alteration to baseflows as a Tributary of Norman’s High Cutting or structure drainage maintains flow Negligible Slight adverse result of cuttings and Brook directions and existing catchment areas wherever structures during operation possible. Unnamed tributaries of Medium Slight adverse impacting surface water Detailed assessment of groundwater-surface water River Churn quantity interaction during detailed design. Unnamed tributary of High Adherence to Annex G of ES Appendix 2.1 EMP Slight adverse River Frome (Document Reference 6.4) Unnamed tributary of Medium Slight adverse Horsbere Brook Sediment and dissolved Tributary of Norman’s High Mitigation will be required at detailed design stage Negligible Slight adverse metals discharging into Brook for outfalls to ensure appropriate treatment levels surface watercourses via are met. Unnamed tributaries of Medium Slight adverse outfalls impacting surface River Churn water quality Unnamed tributary of High Slight adverse River Frome Unnamed tributary of Medium Slight adverse Horsbere Brook

Introduction of new culverts Tributary of Norman’s High CD 529 Design of outfall and culvert details Negligible Slight adverse and outfalls on hydrology Brook standard and CIRIA C786 Culvert, Screen and impacting hydromorphology Operation Manual guidance adhered to Unnamed tributaries of Medium Slight adverse River Churn

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000037 | C01, A3 | 15/03/21 APPENDIX PAGE xii A417 Missing Link | HE551505 Highways England

Magnitude of Significance of Potential impact Receptor Value Design and mitigation measures impact effect Unnamed tributary of High Slight adverse River Frome Unnamed tributary of Medium Slight adverse Horsbere Brook Accidental spillage during Tributary of Norman’s High Not required Negligible Slight adverse operation impacting water Brook quality Unnamed tributaries of Medium Slight adverse River Churn Unnamed tributary of High Slight adverse River Frome Unnamed tributary of Medium Slight adverse Horsbere Brook Flood risk to the site during Scheme Very High Draining and crossing will be designed to the No change Neutral operation standard level of protection as the design progresses and residual risk is understood

Flood risk from the site during Residential properties High It is assumed that the scheme will be designed to No change Neutral operation surrounding the not cause any detriment to fluvial, surface or scheme extent groundwater flood risk. Colleges, High High Schools and Primary Schools surrounding scheme extent Land used for Medium agriculture surrounding the scheme extent

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000037 | C01, A3 | 15/03/21 APPENDIX PAGE xiii A417 Missing Link | HE551505 Highways England

1.4 Summary of non-significant effects – Groundwater – Operation

Potential impact Receptor Value Design and mitigation Magnitude of Significance of measures impact effect Superficial deposits - High Slight adverse Secondary A aquifer Lias Group - Secondary Medium Slight adverse (undifferentiated) Accidental spillage during operation aquifer Not required Negligible Inferior Oolite - High Slight adverse Principal aquifer Great Oolite - Principal High Slight adverse aquifer The permanent construction and Cheltenham Sand and Medium Drainage basin design with No change Neutral operation of drainage basins Gravel - Secondary A in-built treatment measures aquifer to mitigate potential Great Oolite limestone - High impacts to groundwater Principal aquifer quality.

Inferior Oolite - High Principal aquifer

Shab Hill dry valley Medium (G146) Springs in tributary of River Churn Medium headwaters Highway drainage has the potential to cause minor drawdown within the aquifer, Cheltenham Sand and however the widening is at grade with the Gravel - Secondary A Medium None Negligible Slight adverse existing A417 so the drawdown impacts aquifer are anticipated to be negligible

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000037 | C01, A3 | 15/03/21 APPENDIX PAGE xiv A417 Missing Link | HE551505 Highways England

Potential impact Receptor Value Design and mitigation Magnitude of Significance of measures impact effect

Highway drainage within the superficial Lias Group - Secondary deposits overlying the low water bearing (undifferentiated) Medium None No change Neutral Lias Group, which will protect the Lias aquifer Group in terms of both groundwater flow Springs in the upper escarpment are likely fed from shallow groundwater flows originating from the upper Inferior Oolite Drainage strategy intent is Springs in tributary of aquifer. Drainage introduced as part of to convey groundwater Norman's Brook - upper stabilisation measures at Crickley Hill is captured in the drainage Crickley Hill designed to permanently drawdown the High back to surface water Negligible Slight adverse escarpment springs water level in cohesive superficial catchment resulting in and seepages (G206 deposits. If these drains intersect minimal net loss to the and 83) permeable deposits they have the water balance. potential to intercept groundwater flow that contributes to springs. Cutting between Ch. 1+700 and 3+000 is likely to have an impact on groundwater flow paths, particularly near the Crickley Inferior Oolite - Hill escarpment where it may intercept High Voids treatment protocol Negligible Slight adverse Principal aquifer fissures and gulls that transport groundwater to groundwater dependent features at Crickley Hill. Springs are likely to be fed by groundwater flowing through the fault, which is receiving groundwater from the Inferior Oolite aquifer, upgradient of Springs in tributary to cutting Ch. 1+700 to 3+000. The springs Norman's Brook - fault High None Negligible Slight adverse are outside radius of influence boundary springs (16, 17, 18, 19) of highway drainage, however there may be reduction in peak winter flow if highway drainage intersects karst.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000037 | C01, A3 | 15/03/21 APPENDIX PAGE xv A417 Missing Link | HE551505 Highways England

Potential impact Receptor Value Design and mitigation Magnitude of Significance of measures impact effect Well No. 83, potentially Well located in an area not anticipated to fed by perched be impacted by cutting Ch. 1+700 to groundwater/spring flow Low None No change Neutral 3+000 (outside scheme footprint of from Inferior Oolite calculated drawdown). limestone. The purpose of the well is unknown. Highway drainage within cutting Ch. 1+700 to 3+000 is unlikely to have an Well No. G199, historic Low None No change Neutral impact on groundwater flow and levels at disused well Well G199 location. Highway drainage of cutting Ch. 1+700 to Springs and seepages 3+000 likely to intercept groundwater that in tributary of River is within the Severn Vale groundwater Medium None No change Neutral Churn headwaters catchment and does not contribute to (G99, G97) groundwater spring flow. Highway drainage of cutting Ch. 1+700 to 3+000 is unlikely to have an impact on groundwater flow and levels at the dry valley. The dry valley is anticipated to be Dry valley (G3) (new High None No change Neutral up-gradient of the cutting with respect to fault) local groundwater flow paths. The dry valley is beyond the maximum drawdown radius of drainage influence. Highway drainage at the Shab Hill junction on/off ramp cuttings on groundwater levels are unlikely to have Inferior Oolite - High None No change Neutral an impact as the cutting level is above Principal aquifer the maximum anticipated groundwater level.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000037 | C01, A3 | 15/03/21 APPENDIX PAGE xvi A417 Missing Link | HE551505 Highways England

Potential impact Receptor Value Design and mitigation Magnitude of Significance of measures impact effect Drainage strategy intent is to return groundwater The assessment shows that this feature captured in the cutting is outside of the potential zone of Shab Hill dry valley drainage back to the same influence of highway drainage, however Medium Negligible Slight adverse (G146) aquifer and groundwater there may be potential reduction in peak catchment resulting in winter spring flow minimal net loss to the water balance. The public water supply is abstracting water from the Inferior Oolite aquifer, which is overlain by the Fuller's Earth Formation aquitard and Great Oolite limestone in the Stockwell-Nettleton area. Baunton public water High None No change Neutral The cuttings Ch. 3+200 and 5+000 will supply, SPZ3 be founded within the Great Oolite Group and hydraulically disconnected from the Inferior Oolite so potential impacts to flow are negligible. Ch. 3+200 to 5+000 cuttings will result in Great Oolite limestone - High Drainage strategy intent is Negligible Slight adverse removal of Great Oolite aquifer within the Principal aquifer to return groundwater Severn Vale catchment which will cause captured in the cutting a reduction in the resource extent. drainage back to the same aquifer and groundwater catchment resulting in minimal net loss to the water balance. Permanent highway drainage of cuttings Drainage strategy intent is between Ch. 3+200 and 5+000 will result to return groundwater potential drawdown in Great and will captured in the cutting cause a reduction in the resource extent Alluvium - Secondary A drainage back to the same Medium Negligible Slight adverse and recharge area that feeds into the aquifer aquifer and groundwater alluvium aquifer. The alluvium is beyond catchment resulting in the maximum calculated radius of minimal net loss to the influence. water balance.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000037 | C01, A3 | 15/03/21 APPENDIX PAGE xvii A417 Missing Link | HE551505 Highways England

Potential impact Receptor Value Design and mitigation Magnitude of Significance of measures impact effect Springs and seepages in tributary of River Drainage strategy intent is Churn headwaters Medium Negligible Slight adverse Highway drainage of cuttings Ch. 3+200 to return groundwater (G174, G4, G5, G6, to 5+000 will be within the Great Oolite captured in the cutting G77) limestone. Groundwater that would run- drainage back to the same Springs and seepages off from the Great Oolite, over the Fuller's aquifer and groundwater in tributary of River Earth Formation and into the headwaters catchment resulting in Frome headwaters will be intercepted by that drainage. High minimal net loss to the Negligible Slight adverse (east) (G143, G150, water balance. G147, G173, G100, G219, G223, G222) Drainage strategy intent is Highway drainage of cuttings Ch. 3+200 Springs and seepages to return groundwater to 5+000 will be within the Great Oolite in tributary of River captured in the cutting limestone. The assessment shows that Frome headwaters drainage back to the same these springs are outside of the potential High Negligible Slight adverse (east) (G150, G147, aquifer and groundwater zone of influence, however there may be G173, G100, G219, catchment resulting in potential reduction in peak winter spring G220, G221) minimal net loss to the flow. water balance. Bushley Muzzard SSSI High Not required No change Neutral Drawdown in groundwater levels and other springs and associated with highway drainage at Ch. seepages in tributary of 3+200 to 5+000 impacting Groundwater River Frome Dependent Terrestrial Ecosystem headwaters (west) Springs in tributary of Norman's Brook springs These springs will be buried beneath the and seepages (61, 69, High Design of embankment and Negligible Slight adverse embankment. 72, 78, 80, G2, G17, tributary realignment will G20, G151) include a drainage blanket and redirection of the This seepage is in the footprint of the springs to the realigned scheme and will be buried. It is a Seepage G138 Low tributary Negligible Neutral localised feature not supporting any groundwater dependent habitats.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000037 | C01, A3 | 15/03/21 APPENDIX PAGE xviii A417 Missing Link | HE551505 Highways England

Potential impact Receptor Value Design and mitigation Magnitude of Significance of measures impact effect

Design of embankment will These springs in the scheme footprint Shab Hill dry valley include a drainage blanket Medium Negligible Slight adverse and will be buried. (G146, G183) and redirection of the springs to the dry valley This spring is in the footprint of an Springs in tributary of Medium Drainage design will return Negligible Slight adverse embankment and will be buried. River Churn intercepted groundwater to headwaters (G174) the same groundwater catchment resulting in no net loss from the groundwater body and spring flow. Potential alteration of shallow groundwater flow pathways may occur around new overbridge foundations. Due to the location and minor extent of the Great Oolite limestone - foundations within the much larger area High None Negligible Slight adverse Principal aquifer of aquifer and close proximity to the anticipated groundwater divide location, the impact on groundwater flow pathways will be minor. Piled foundation for Cotswolds Way crossing is likely to have an impact on groundwater flow paths, particularly near Inferior Oolite - FWRA and voids treatment the Crickley Hill escarpment where it may High Negligible Slight adverse Principal aquifer protocol intercept fissures and gulls that transport groundwater to groundwater dependent features at Crickley Hill. Pile foundation for Cowley and Stockwell overbridges is likely to intercept the Inferior Oolite limestone underlying the Great Oolite limestone and Fuller's Earth Inferior Oolite - High FWRA Negligible Slight adverse Formation. Piles are likely to be above Principal aquifer the maximum groundwater level so impacts on groundwater flow and level are likely to be negligible.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000037 | C01, A3 | 15/03/21 APPENDIX PAGE xix A417 Missing Link | HE551505 Highways England

Potential impact Receptor Value Design and mitigation Magnitude of Significance of measures impact effect Springs and seepages Construction of the Cowley and Stockwell in tributary of River overbridge pile foundation may impact Churn headwaters Medium Negligible Slight adverse groundwater flow and level in the Great (G174, G4, G5, G6, The design intention is to Oolite limestones. However, the impact is G77) have gaps between the likely to be very local. As the foundations Springs and seepages piles to minimise the impact piles are likely to be constructed in in tributary of River of groundwater mounding. groups with gaps in between individual Frome headwaters FWRA High Negligible Slight adverse piles, impact on groundwater flow is likely (east) (G143, G150, to be negligible. G147, G173, G100, G219, G223, G222) The Bushley Muzzard SSSI is fed by groundwater springs at the Great Oolite limestone and Fuller's Earth formation, Bushley Muzzard SSSI which feed into the headwaters of the and associated springs River Frome tributary (west). Underlying (G102, G25) also Head Deposits may allow for some High None No impact Neutral feeding to tributary of perching of shallow groundwater. The River Frome SSSI is unlikely to be directly headwaters (west) hydraulically connected to the scheme on the opposite side of the River Frome headwater valley (east).

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000037 | C01, A3 | 15/03/21 APPENDIX PAGE xx A417 Missing Link TR010056

6.4 Environmental Statement Appendix 13.10 Drainage Report

Planning Act 2008

APFP Regulation 5(2)(a) Infrastructure Planning (Applications: Prescribed Forms and Procedure) Regulations 2009

Volume 6

May 2021 A417 Missing Link | HE551505 Highways England

Infrastructure Planning

Planning Act 2008

The Infrastructure Planning (Applications: Prescribed Forms and Procedure) Regulations 2009

Regulation 5(h)

A417 Missing Link

Development Consent Order 202[x]

6.4 Environmental Statement Appendix 13.10 Drainage Report

Regulation Number: 5(2)(a) Planning Inspectorate TR010056 Scheme Reference Application Document Reference 6.4 Author: A417 Missing Link

Version Date Status of Version C01 May 2021 Application Submission Environmental Statement | HE551505 Highways England

Table of contents Pages 1 Introduction i 1.1 Purpose of this document i 2 Site description ii 2.1 Existing watercourses ii 2.2 Topography ii 2.3 Geology and soils ii 3 Existing drainage iii 3.1 Data sources iii 3.2 Existing highway drainage iii 3.3 Tributary of Norman’s Brook iv 3.4 Surface water flood risk v 4 Scheme drainage design vi 4.1 Proposed drainage infrastructure vi 4.2 Design criteria vi 4.3 Highway drainage collection – A417 and slip lanes (Highways England) viii 4.4 Highway drainage collection – Local roads (GCC) viii 4.5 Groundwater ix 4.6 Drainage basins x 4.7 Cross drainage & watercourses x 4.8 Earthworks drainage xi 4.9 Land drainage xii 4.10 Impacts on catchments xii 4.11 Changes to existing A417 xiv 4.12 Exceedance routes xv 5 Tributary of Norman's Brook xvi 5.1 Realignment of the tributary of Norman’s Brook xvi 5.2 Culvert near Crickley Hill Farm. xvii 6 Water quality xix 7 Access and maintenance xxi References xxii Annexes i Annex A Highway Drainage Records ii Annex B Existing Highway Drainage iii Annex C Scheme Highway Drainage iv Environmental Statement | HE551505 Highways England

Table of Figures Figure 4-1 Impact on existing catchments xiv Figure 5-1 Tributary of Norman’s Brook - cross section xvi

Table of Tables Table 4-1 Principal culverts xi Table 4-2 Impact on existing catchments xiii Table 5-1 Thresholds - culvert near Crickley Hill Farm xvii Environmental Statement | HE551505 Highways England

1 Introduction

1.1 Purpose of this document 1.1.1 A drainage strategy and preliminary drainage design have been developed to support the Environmental Statement (ES) for the A417 Missing Link (referred to herein as ‘the scheme’). 1.1.2 This report describes the baseline environment, the existing drainage and the proposed drainage design principles and parameters for the scheme. The Annex G Ground and surface water management plan of the Environmental Management Plan (EMP) in Appendix 2.1 Environmental Management Plan (Document Reference 6.4) includes details of measures to protect the water environment during construction of the scheme and thus construction issues are not considered in this report. 2 Site description

2.1 Existing watercourses 2.1.1 The scheme interacts with ordinary watercourses in four river catchments:  River Churn  River Frome  Norman’s Brook (see Section 3.3)  Horsbere Brook 2.1.2 There are no main rivers affected by the scheme. 2.1.3 The River Churn is part of the River Thames catchment, the other watercourses are within the River Severn catchment.

2.2 Topography 2.2.1 The site can be split in to two topographic areas. The central and east sections of the project are located on the rolling high wold (predominantly limestone) interspersed with steep valleys. 2.2.2 To the east the ground drops away steeply towards the flat Severn Vale forming an escarpment with characteristic limestone outcrops. Crickley Hill is the part of this ridge traversed by the existing A417.

2.3 Geology and soils 2.3.1 The bedrock underlying the region is generally comprised of Oolitic Limestone. 2.3.2 Superficial deposits are located in discrete areas relative to the scheme including, the Cotswold escarpment (west of the escarpment crest), the Churn Valley (near Shab Hill Farm) and the Frome Valley (near Stockwell-Nettleton). These comprise mass movement deposits, alluvial deposits and Cheltenham sand and gravel. 2.3.3 The existing A417 crosses the top of the Cotswold escarpment where the Inferior Oolite Group outcrops and descends to the Vale of Gloucester within the outcrop of the Lower Lias. To the south-east of the scheme (Parsons pitch to Cowley

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000042 | C01, A3 | 11/03/21 Appendix Page i Environmental Statement | HE551505 Highways England

roundabout) landslip material is encountered in the valleys and bottoms, together with some deposits of Fullers Earth. 2.3.4 Previous studies indicate that almost all of the A417 route below the escarpment (Brockworth bypass to Air Balloon roundabout) is within land-slipped material (colluvium). Over this section the Upper and Middle Lias Formations, together with the upper horizons of the Lower Lias, are mantled by the colluvial deposits. 2.3.5 In many places the slopes below the escarpment exhibit evidence of past ground movements with features such as soil lobes, back scars and springs dominating. Many areas are hummocky in appearance indicating the possible existence of secondary land-slipping masking the deeper-seated historic failures. 2.3.6 Available data indicates that the soil types across the scheme are lime-rich loamy soils. 2.3.7 A complete description of the geological and topological context is provided in ES Appendix 13.7 Hydrogeological Impact Assessment (Document Reference 6.4). 3 Existing drainage

3.1 Data sources 3.1.1 The understanding of existing drainage systems has been developed from the following sources:  Highways Agency Drainage Data Management System (HADDMS) database and as-built drawings (see Annex A Highway Drainage Records).  Drainage maintenance record drawings from Area 31 Design Build Finance Operator (DBFO), 2020 (see Annex A Highway Drainage Records)  OS mapping  Topographic survey (Malcolm Hughes/Highways England), 2019  Planning applications for developments in the project area (13-00764, 15- 00751, 16_00123)  Preceding Highways England drainage reports and studies, including:  A417 Cowley to Brockworth Bypass Improvement, Drainage Strategy Report, WSP, Jan 20051  A417 Missing Link, Drainage Strategy Report, MMSJV, PCF Stage 2, March 20192  A417 Normans Brook Tracer Test (HE551505-MMSJV-EWE-000-RP-LX- 00003), 22 March 20193  ES Appendix 13.11 Water Features Survey (Document Reference 6.4) 3.1.2 In addition, site visits and informal surveys have been undertaken:  Supplementary topographic (culvert) survey by Highways England, Dec 2019  Site visits and informal surveys: 6 August 2019, 14 January 2020, 16 February 2020 and 10 March 2020

3.2 Existing highway drainage 3.2.1 The existing highway systems, outfalls and catchments are summarised in Annex B Existing Highway Drainage and ES Figure 13.18 Existing Drainage Plan (Document Reference 6.3). Relevant record drawings from HADDMS and the DBFO are in Annex A Highway Drainage Records

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000042 | C01, A3 | 11/03/21 Appendix Page ii Environmental Statement | HE551505 Highways England

3.2.2 The topographic survey identifies above ground surface drainage elements (gullies, manhole covers etc) and hydraulic structures (weirs, headwalls etc), but does not include the survey of any below ground buried drainage and services. 3.2.3 Records are available for the existing highway drainage for most of the relevant sections of the existing A417. Note that, with the exception of the Brockworth Bypass section, this data does not contain any level information (invert and cover levels) for the buried drainage systems, nor details of soakaways, and only limited pipe size data. 3.2.4 Based on available records it is thought that the existing A417 between Parsons Pitch and the current Air Balloon roundabout drains predominantly to groundwater via soakaways. 3.2.5 The as built records suggest that the section of the existing A417 south of Cowley/Nettleton Roundabout may include infiltration features, although there is insufficient evidence to confirm this conclusively. 3.2.6 Record drawings received from the DBFO and site visits confirm the presence of soakaways at the Ullenwood Cricket Club and the existing junction of the A436/Leckhampton Hill. These soakaways serve that junction and the Air Balloon roundabout, plus the bottom section of the existing A417 Birdlip Hill, north of Four Winds. 3.2.7 Record drawings from the DBFO also confirm that the existing A417 Crickley Hill is collected by kerb and gulley systems that outfall to the tributary of Norman’s Brook between Grove Farm and Crickley Hill Farm. 3.2.8 Away from the existing A417 and junctions, existing minor rural roads appear to be predominantly served by informal drainage systems discharging into field ditches and adjacent agricultural land. 3.2.9 Asset data provided by Highways England has indicated the presence of, isolation valves, petrol interceptors and a lagoon serving the existing A417 near Nettleton roundabout (existing catchment E9). 3.2.10 Based on available information there are no other pollution treatment or control measures provided on the sections of the existing A417 affected by the scheme.

3.3 Tributary of Norman’s Brook 3.3.1 The tributary of Norman’s Brook (Crickley Hill stream) is the principal watercourse receiving flows from the western part of the scheme area. 3.3.2 The tributary runs from east to west and connects to the Norman’s Brook main channel west of the A46 Shurdington Road. 3.3.3 The stream is a distinguishable feature and is continuously flowing, fed by land drainage systems and springs on the south and east of Grove Farm and the A417 highway drainage system to the north. 3.3.4 Between its source and the existing A417 culvert near Crickley Hill Farm the tributary of Norman’s Brook has an irregular and steep course interrupted by short culverts and other features such as informal dams and a cascade. 3.3.5 A number of public data sources including the Digital River Network and the EA Water Framework Directive (WFD) catchment explorer still report that the watercourse connects to the Horsbere Brook catchment.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000042 | C01, A3 | 11/03/21 Appendix Page iii Environmental Statement | HE551505 Highways England

3.3.6 However, a tracer test3 confirmed that the watercourse is in fact a tributary of Norman’s Brook and crosses under the existing A417 Mainline via a culvert located near Crickley Hill Farm. 3.3.7 The watercourse enters the culvert just east of Crickley Hill Farm. The available information indicates that this culvert cranks north west, crossing diagonally under the existing A417, and then continues west along Dog Lane and Bentham Lane before discharging to an open ditch just north of Bentham County Club on the western side of Bentham Lane. The total length of culvert, including the section under the existing A417, is approximately 1.04km. 3.3.8 Information about the line, level and conduit size is not complete, particularly in the lower sections west of Holly Brae, but information from surveys, as built records and site visits has enabled an adequate understanding of the existing culvert to inform the preliminary design. 3.3.9 The total level drop over its length is approximately 30m with an overall average gradient of 3%. 3.3.10 The available data indicates that the upper reaches are a 600mm diameter pipe. Where the culvert crosses diagonally under the existing A417 the gradient is approximately 3%, but the sections immediately upstream and downstream have a gradient of approximately 5%. 3.3.11 Between Holly Brae and the Bentham Road/Dog Lane junction the culvert flattens to around 1% and the diameter reduces to only 450mm. 3.3.12 The section downstream of Holly Brae is constructed in a mixture of materials Estimated gradients downstream of the Bentham Road/Dog Lane junction are approximately 2.5% overall. 3.3.13 The upper end of the culvert near Crickley Hill Farm is served by a well-designed, modern headwall and trash screen. At the headwall there is a section of 1m diameter pipe, which tapers to 600mm a short distance inside the culvert.

3.4 Surface water flood risk 3.4.1 The Risk of Flooding from Surface Water Flood Maps4 give an indication of principal overland flow paths and areas of low ground at risk of surface water flooding. 3.4.2 These do not necessarily take account of buried drainage infrastructure such as culverts, soakaways and highway drainage systems. 4 Scheme drainage design

4.1 Proposed drainage infrastructure 4.1.1 The scheme highway drainage basins, outfalls, culverts and perimeter drainage features are shown on General arrangement and section plans (Document Reference 2.6) and described in ES Chapter 2 The project (Document Reference 6.2). 4.1.2 Proposed highway catchments, asset ownership and preliminary surface water management storage provisions are summarised in Annex C Scheme Highway Drainage and ES Figure 3.19 Scheme Highway Drainage - Plan (Document Reference 6.3).

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000042 | C01, A3 | 11/03/21 Appendix Page iv Environmental Statement | HE551505 Highways England

4.2 Design criteria

Highway drainage – general 4.2.1 The scheme mainline and junction slip road drainage would be adopted and maintained by Highways England. All other highway drainage would be adopted by Gloucestershire County Council (GCC). 4.2.2 The highway drainage systems have been designed in accordance with Design Manual for Roads and Bridges5 (DMRB) CG 501 Design of highway drainage systems and DMRB LA 113 Road drainage and the water environment (LA 113). For local roads the drainage design has incorporated GCC’s requirements. 4.2.3 Wherever possible, separate drainage networks and attenuation/infiltration basins will be provided for each adopting authority. 4.2.4 Reconfiguration of the existing local roads will require new drainage to connect into existing networks at some locations. The proposals will provide a like for like or reduction of impermeable area into the existing networks, and the design assumes that the existing networks have sufficient capacity to convey the flows from the new drainage. 4.2.5 If there is a net increase in paved area contributing to an existing system attenuation is provided. 4.2.6 The highway drainage pipes will be sized to convey a 1 in 1-year return period event including climate change without surcharging. 4.2.7 The design will ensure that there is no surface water flooding on the highway for a 1 in 5-year return period event including climate change. 4.2.8 For Highways England roads, the design will ensure no surcharge of the road foundation (formation level, or sub-formation level where capping is present) in the 1 in 5-year return period event including climate change.

Climate change 4.2.9 The design life of drainage assets would be 60 years and assets that qualify as Structures would be 120 years. Based on the predicted opening date of no later than 2025, the scheme assets will reach the end of their design life in 2085 and 2125, respectively. 4.2.10 The catchments affected by the scheme, including both highway drainage systems and external land drainage, are less than 5 km2 so peak rainfall intensity (direct rainfall) allowances apply6 4.2.11 Therefore, the upper end and central increases that apply are 40% and 20% respectively. 4.2.12 The highway drainage carriageway collection networks are sized and tested for the return periods in section 5 of DMRB CG 501 Design of highway drainage systems, with a 20% allowance for climate change (DMRB CG 501 Design of highway drainage systems, section 4). 4.2.13 The highway drainage systems overall are designed to manage a 1 in 100-year return period event plus 40% climate change within the site (DMRB CG 501 Design of highway drainage systems, clause 5.3 & section 4).

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000042 | C01, A3 | 11/03/21 Appendix Page v Environmental Statement | HE551505 Highways England

Surface water management 4.2.14 Surface water management proposals have been developed in accordance with the policy requirements of the Lead Local Flood Authority (LLFA) which is Gloucestershire County Council (GCC)7, and national policy guidance8. 4.2.15 The design will ensure that the post development run off will be managed within the site up to 1 in 100-year event with a 40% allowance for climate change. 4.2.16 GCC, national policy guidance and DMRB CG 501 Design of highway drainage systems all require that destinations for discharge from road drainage systems are selected according to the following hierarchy:  Groundwater  Surface watercourse  Surface water sewer 4.2.17 Where infiltration is not possible, the runoff to surface waters will be attenuated to Green Field Runoff Rates (GFRR) and volumes. 4.2.18 The greenfield run off rates have been calculated using the Institute of Hydrology 124 method (IH124) with adaptations in the Interim Code of Practice (ICoP) for Sustainable Drainage Systems for catchments less than 50ha9. 4.2.19 A minimum control flow rate of 5l/s is applied to ensure ease of maintenance and reduce risk of blockage. 4.2.20 Where the proposed catchment includes reconfiguration of existing carriageways, or removal of existing pavements, the allowable run-off rates for the developed site may be increased versus the GFRR to take account of the previously developed paved areas. 4.2.21 GCC standing advice7 states: “For developments which were previously developed, the peak runoff rate from the development to any drain, sewer or surface water body up to the 1 in 100 year rainfall event + 40% for climate change should reduce the surface water discharge by 40% of that existing or be as close as is reasonably practicable to the greenfield runoff rate from the development for the same rainfall event, but in any event should never exceed the rate of discharge from the development prior to redevelopment for that event”.

4.3 Highway drainage collection – A417 and slip lanes (Highways England) 4.3.1 Pavement edge and central reserve drainage solutions for the A417 mainline and for slip lanes at junctions would be selected in line with the recommended solutions flow charts in DMRB CG 501 Design of highway drainage systems (Table 3.5.1 and 3.5.2). The mainline carriageway generally is not kerbed. Likely solutions are outlined below. 4.3.2 In cuttings, the preferred verge design would be combined grass lined surface water channels and/or filter drains. 4.3.3 In sections with steep longitudinal gradients the grassed surface water channels may need to be either replaced with concrete or employ special details to counter erosion issues.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000042 | C01, A3 | 11/03/21 Appendix Page vi Environmental Statement | HE551505 Highways England

4.3.4 Where practicable, and it is economic do so, systems draining paved road surfaces would be kept separate from those intercepting groundwater and run-off from earthworks slopes. 4.3.5 This approach is necessarily adopted in wide verges in cuttings where rock trap walls are present, and carriageway drainage has been placed in front of the walls to minimise maintenance activities in proximity to potential falling rocks. 4.3.6 On embankments, the preferred verge design would be surface water channels. 4.3.7 Over the edge details may be an alternative for mainline embankments, subject to earthwork stability checks, and if it is considered allowable not to direct flows to a single outfall location to facilitate spillage containment. 4.3.8 Where kerbs are required, the surface water runoff would be drained via gully outlets or combined kerb and drainage units to carrier pipes. 4.3.9 The preferred central reserve detail for super elevated carriageways would be concrete surface water channel. 4.3.10 Where there are widened central reserves which are unpaved, there may be opportunities to employ filter strips and grass or hybrid grass/concrete surface water channels. 4.3.11 The design of the A417 mainline would include filter drains or narrow filter drains in the verges and in the central reserves of super elevated carriageways, to ensure performance and longevity of the road pavement and pavement foundations. 4.3.12 In cuttings filter carrier drains would also intercept slope drainage and serve a function lowering groundwater to ensure stability of the adjacent cutting.

4.4 Highway drainage collection – Local roads (GCC)

General 4.4.1 For local roads that would be adopted by GCC the highway drainage in cuttings would typically comprise combined filter drains and grassed surface water channels. On shallow embankments the default would be over the edge drainage with swales or ditches. 4.4.2 The default approach for rural roads would be for there to be no kerbs. Where there are footways, in the vicinity of junctions and roundabouts, or if spillage containment is required, conventional gullies or combined kerb and drainage systems would typically be employed. 4.4.3 The outline proposals for certain roads are outlined below and would be refined at detailed design.

Cold Slad Lane 4.4.4 A filter carrier drain (FCD) would drain and stabilise the slopes on the north side and would intercept flows from slope drainage measures. 4.4.5 The paved areas would be served by a grassed surface water channels (GSWC) or swales, providing local attenuation and storage (source control)

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000042 | C01, A3 | 11/03/21 Appendix Page vii Environmental Statement | HE551505 Highways England

A436 link road 4.4.6 On the low side of carriageway, a grassed surface water channel or swale would intercept highway runoff. 4.4.7 On the east side where a rock trap wall is employed, there would be separate drainage systems that drain the carriageway and rock slopes.

Roundabouts and junctions 4.4.8 The roundabouts and junctions at Shab Hill, Ullenwood and Cowley would be predominantly served by kerb and gullies.

B4070 4.4.9 The B4070 east of Barrow Wake would be wholly in cutting, so filter carrier drains and grassed surface water channels would be required to intercept runoff from the road and cutting slopes. Over the edge solutions, swales and informal dispersal would be proposed along the existing reused section of carriageway between Birdlip and at Barrow Wake, but this would be dependent on GCC and may require agreements with adjacent landowners. This section of road is currently served by kerb and gullies. 4.4.10 The existing section of highway under the Barrow Wake underbridge is served by soakaways with an overflow to the Barrow Wake car park. The scheme would include a storage tank to manage flows from the increase in paved areas, but it is anticipated that this could be wholly or partly substituted with soakaway solutions, once ground characteristics are confirmed.

4.5 Groundwater 4.5.1 In areas where the interception of groundwater impacts on springs or excessive groundwater is encountered, there would be separate systems put in place to maintain the springs and manage groundwater under the road infrastructure. 4.5.2 This would be the case where new highway embankments submerge watercourse and flow paths at valley bottoms, such as the tributary of Norman’s Brook and the dry valley under Shab Hill junction.

4.6 Drainage basins 4.6.1 Where highway drainage discharges into suitable adjacent watercourses or dry valleys, run-off would be attenuated according to the principles outlined in section 4.2. 4.6.2 Discharge rates would be controlled by a flow device immediately downstream of each basin, with an overflow weir to convey the 100-year return period plus 40% climate change flow. 4.6.3 The details of flow controls will be developed at detailed design. 4.6.4 The proposed outfalls, green field run-off rates and estimated basin volumes are shown in Annex C, and ES Figure 3.19 Scheme Highway Drainage - Plan (Document Reference 6.3). 4.6.5 The volumes have been calculated on the precautionary assumption of no infiltration, but there would be an opportunity optimise basin sizes taking into

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000042 | C01, A3 | 11/03/21 Appendix Page viii Environmental Statement | HE551505 Highways England

account infiltration when further ground investigation (GI) data is available during the detailed design. 4.6.6 The volumes would be subject to change as the level of detail in the design develops and input parameters (infiltration rates, ground conditions) are validated by surveys and site tests. 4.6.7 Attenuation basins/infiltration basins would typically have a maximum storage depth of 1.5m with 0.3m freeboard to the top of the basin. Side slopes would be 1H:3V for maintenance with a localised ramp at 1H:5V for access and to allow mammal escape. The design will be in accordance with the requirements of DMRB CD 532 Vegetated drainage systems for highway runoff. 4.6.8 Detailed groundwater quality assessments will be undertaken at detailed design. Once completed, there is a possibility that attenuation/infiltration basins and highway drainage systems in some locations could require lining or other mitigations to prevent pollution of vulnerable groundwaters.

4.7 Cross drainage & watercourses 4.7.1 The scheme crosses several watercourses and dry valleys. Flows in these watercourses/dry valleys would be maintained within their catchment through culverts, wherever possible. 4.7.2 Dry valleys are natural features which may give rise to surface water flows in certain circumstances (e.g. during periods of exceptional rainfall and in the event of melting snow). 4.7.3 The scheme does not cross any EA designated main rivers. 4.7.4 Culverts would be designed in accordance with DMRB CD 529 Design of outfall and culvert details10, and the requirements of the LLFA (GCC). 4.7.5 The proposed cross drainage culverts would be, as a minimum, sized to convey the 1 in 50-year event plus a 40% allowance for climate change. The 50 year design return period is appropriate for culverts which are servicing agricultural land of high value or isolated properties (CIRIA C78610, chapter 10.1.2). 4.7.6 A sensitivity check has also been undertaken for the 1 in 100yr+40% cc event to ensure the safe management of exceedance flows and surface water flooding. 4.7.7 Allowance would be included in the cross sections for embedment and freeboard (CIRIA C78610). 4.7.8 Peak design flows have been estimated using the IH124 (Institute of Hydrology Report 124) and FEH (Flood Estimation Handbook) methods for rural catchments. For the Crickley Hill stream catchment this has been further validated with the RefH2 (Revitalised Flood Hydrograph) method and software. 4.7.9 The minimum diameter of culverts over 12m in length would be 1.2m in accordance with DMRB CD 529 Design of outfall and culvert details. 4.7.10 In addition to the main crossings and culverts there would be numerous minor culverts intercepting field drainage and conveying flows from cut-off ditches under tracks, public rights of way (PROW), field entrances and private accesses 4.7.11 Minor culverts under 12m in length may be smaller than 1.2m diameter and would be subject to an absolute minimum of 450mm diam.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000042 | C01, A3 | 11/03/21 Appendix Page ix Environmental Statement | HE551505 Highways England

4.7.12 Residual risks associated with the existing culvert near Crickley Hill Farm in exceedance and blockage events are discussed in section 5.2. 4.7.13 Table 4-1 summarises the principal proposed cross drainage culverts under the scheme mainline, and culverts conveying watercourses or dry valleys: Table 4-1 Principal culverts

Approximate Location Type Catchment 1 in Length Indicative chainage area (Ha) 100yr+cc (m) Size height flow (m3/s) /diameter (m) Existing culvert near Watercourse 173* 1.34* 300 1.35 0+530 Crickley Hill Farm (extension)* 1+450 Grove Farm culvert Watercourse 68 0.86 195 1.2 3+200 Shab Hill culvert Dry Valley 83 1.02 290 1.2 Dry 13 0.16 160 1.2 4+775 Stockwell culvert valley/land drainage Dry 8 0.10 320 1.2 Cowley Junction 5+220 valley/land culvert drainage * Note: the catchment area and peak flow of the existing culvert near Crickley Hill Farm is reported at a point on the north side of the A417 at Dog Lane.

4.8 Earthworks drainage 4.8.1 The design would include filter drains or other features at the toes of new cuttings and embankments to lower groundwater, intercept surface water run-off and ensure stability of the earthworks. 4.8.2 Similar provisions would also made for existing slopes, where necessary, to ensure the stability of the slopes and to intercept new geotechnical drainage features (counterfort drains etc).

4.9 Land drainage 4.9.1 Where adjacent land falls towards the new road cuttings and embankments the design would include perimeter ditches to intercept overland flows and field drainage systems, and to convey these flows to the nearest cross drainage culvert or watercourse. The design drawings indicate ditches, but the perimeter drainage may take the form of swales or filter drains, depending on local drainage flows, landscape context and the intended land use. 4.9.2 Perimeter drainage would be sized for 1 in 100-year storm plus 40% climate change (DMRB CD 522 Drainage of runoff from natural catchments, Cl 5.1). 4.9.3 Perimeter ditches provided at the top of cuttings to intercept overland flow may require lining where the adjacent slope is sensitive to concentrated ingress of water. 4.9.4 Perimeter drainage would be offset by a suitable distance to ensure stability of the adjacent earthwork.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000042 | C01, A3 | 11/03/21 Appendix Page x Environmental Statement | HE551505 Highways England

4.9.5 Ditches with steep longitudinal gradients would include rock dams and or linings to reduce flow velocities, manage erosion and fulfil surface water management objectives. 4.9.6 Where the perimeter ditch traverses the escarpment near Grove Farm and the existing A417 Birdlip Hill cutting near Emma’s Grove, cascades would be provided to manage velocities and dissipate kinetic energy. 4.9.7 If the natural topography falls away from the road corridor, cut off ditches would not generally be provided at the toe of earthworks, other than if required to mitigate local flooding risk, or for slope stability reasons.

4.10 Impacts on catchments 4.10.1 Although the design attempts, wherever possible, to maintain existing catchments and not interfere with existing flow paths, due to the presence of significant new earthworks cuttings, some redistribution of catchments would be unavoidable. 4.10.2 Surface water from land south-west of the scheme’s cutting between the Air Balloon roundabout and Shab Hill junction currently flows to the River Churn catchment via dry valleys at Leckhampton Hill and Ullenwood, which converge at the National Star College (NSC) golf course. 4.10.3 As a result of the scheme there would be a net increase of up to 23 ha in the catchment area to the tributary of Norman’s Brook and a corresponding reduction in the catchment area to the River Churn. 4.10.4 This includes 16ha of hillside at Emma’s Grove which based on most sources is part of the tributary of Norman’s Brook catchment – see ES Figure 13.3 WFD Surface Waterbodies (Document Reference 6.3). However, hydraulic analysis of overland flow paths has indicated that run-off from this area is intercepted by the existing A417 Birdlip Hill cutting and is collected in the highway drainage systems. 4.10.5 These systems rely partially upon infiltration, but flow to a terminal soakaway at the Cricket Club north of the existing Air Balloon roundabout. Analysis of flow paths indicates that in exceedance events the overland flow routes are also north west to the soakaway and hence towards Leckhampton Hill and the National Star College golf course. 4.10.6 The scheme would return the catchments to a situation closer to the natural delineation that existed before the A417 Birdlip Bypass scheme was constructed (1987), and closer to existing catchment mapping as shown on ES Figure 13.3 WFD Surface Waterbodies (Document Reference 6.3). 4.10.7 The impacts of the scheme on flows arriving at the tributary of Norman’s Brook would be mitigated by:  The removal of paved areas within the catchment along the old A417 Birdlip Hill cutting between the Air Balloon and Barrow Wake.  The introduction of natural flood management measures (infiltration and storage) within the old A417 Birdlip Hill cutting.  The provision of attenuation storage within the perimeter land drainage ditches along the south side of the Crickley Hill cutting.  The removal of paved areas from the former A417 Crickley Hill between Bentham Lane and the Air Balloon roundabout, and their replacement with new highway drainage systems attenuated to greenfield run off rates.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000042 | C01, A3 | 11/03/21 Appendix Page xi Environmental Statement | HE551505 Highways England

Table 4-2 Impact on existing catchments

River Churn River Churn (a) Air Balloon/ Tributary of Leckhampton Hill (b) Ullenwood Norman’s Brook sub-catchment sub-catchment

Unnamed Unnamed Tributary of Norman’s Brook downstream of Point on catchment watercourse watercourse the scheme’s basin NSC Golf Course NSC Golf Course no 3c at Grove Farm Existing catchment area 108 ha 49 ha 61ha (baseline) Post development 94 ha 39 ha 84ha catchment area Catchment redistribution -13.6 ha -9.7 ha +23 ha vs baseline Catchment redistribution vs pre 1987 (A417 Birdlip -7ha +7ha Bypass scheme)

Figure 4-1 Impact on existing catchments

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000042 | C01, A3 | 11/03/21 Appendix Page xii Environmental Statement | HE551505 Highways England

4.11 Changes to existing A417 4.11.1 The existing A417 highway drainage outfalls between Witcombe Court underbridge and the Air Balloon roundabout would be removed by the scheme. 4.11.2 Between the Air Balloon roundabout and the Cowley Lane junction near Stockwell, the existing A417 highway pavement would be largely removed and the land reinstated as a green corridor/ walking cycling and horse-riding (WHCR) route. 4.11.3 Between Cowley Lane junction near Stockwell and Cowley junction, the highway would be retained but transferred from Highways England to GCC. 4.11.4 The majority of these carriageways currently discharge highway run-off to watercourses or groundwaters with no treatment or spillage control. 4.11.5 Between Air Balloon and Stockwell there would be benefits to water quality due to the complete removal of highway run-off. 4.11.6 Between Stockwell and Cowley junction there would be benefits due to the reduced traffic and pollution loads.

4.12 Exceedance routes11 4.12.1 In the extreme rainfall events when the capacity of drainage systems is exceeded (typically 1 in 5 year events for piped highway drainage systems) the design would ensure that flow paths to the basins are maintained, up to the 1 in 100year event plus climate change. 4.12.2 In most locations the proposed ground morphology ensures that exceedance flows would be directed to the basins. However, in some locations additional measures would be required. 4.12.3 For the networks associated with basins 9,10 and 11, overflow flood culverts would be provided through the landscape bunds to create an exceedance event flow route. 4.12.4 At basin 2 the terminal pipe from the highway drainage network to the basin would be sized to convey the 1 in 100-year event plus climate change flow. 4.12.5 See Section 5 for details of the management of exceedance routes at the existing culvert near Crickley Hill Farm.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000042 | C01, A3 | 11/03/21 Appendix Page xiii Environmental Statement | HE551505 Highways England

5 Tributary of Norman's Brook

5.1 Realignment of the tributary of Norman’s Brook 5.1.1 The widening of the A417 embankment west of the escarpment would introduce an earthwork into the bottom of the existing valley at Crickley Hill, which would submerge the existing stream. This would require a realignment of the stream on the south side of the new A417 embankment between Grove Farm and the existing culvert near Crickley Hill Farm. 5.1.2 The scheme would also require the existing culvert near Crickley Hill Farm to be replaced and extended under the raised and widened A417 embankment.

Figure 5-1 Tributary of Norman’s Brook - cross section 5.1.3 The watercourse realignment would comprise a 5m wide earthwork platform, within which there will be a smaller irregular, meandering channel to convey the habitual flows in the watercourse. 5.1.4 The platform would be a minimum depth of 2.5m below the A417 mainline verge level to minimise ingress from the watercourse into the highways drainage system, although the road embankment would be up to 10m high in this area. On the southern side the platform would be a minimum depth of 0.6m below the existing ground, to provide capacity when the flow surcharges out of channel during extreme rainfall events. 5.1.5 The channel within the platform has been simplistically represented as 0.6m deep with a 1 in 1 side slope and a 0.6m base. The location and form of the central channel in the earthworks model is indicative, and this would be meandered and naturalised within the 5m wide platform. 5.1.6 The 5m wide platform (flood channel) would be designed to contain the 1 in 100yr plus climate change flow. 5.1.7 The resultant vertical alignment of the stream would be irregular but the overall gradient between Grove Farm and the culvert headwall at Crickley Hill Farm would be approximately 7%, which is similar to the existing. 5.1.8 The scheme would aim to replicate the character and geomorphology of a typical upland stream, and there would be space within the 5m wide platform to accommodate natural flood management and features such as step pools, cascades, informal steps and irregular meanders.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000042 | C01, A3 | 11/03/21 Appendix Page xiv Environmental Statement | HE551505 Highways England

5.1.9 Where these features or structures have a function to manage flood risk and run- off from the reconfigured upstream catchments, they may be designated by the LLFA (GCC) under the FWMA (Flood and Water Management Act). 5.1.10 The realigned stream would minimise the introduction of new culverted sections, wherever possible. 5.1.11 The environmental impacts on the watercourse are assessed and reported in ES Chapter 13 Road drainage and the water environment (Document Reference 6.2) and ES Appendix 13.5 Hydromorphology Assessment (Document Reference 6.4).

5.2 Culvert near Crickley Hill Farm. 5.2.1 Hydraulic analysis of the existing culvert near Crickley Hill Farm has provided estimates of the peak flow thresholds for various events: Table 5-1 Thresholds - culvert near Crickley Hill Farm

Event Flow Correlation to Storm Return Period (345 (l/s) min Winter Storm) Peak flow at upstream headwall* First flooding at Dog Lane (Holly Brae) 370 1 in 1yr peak flow approx. 233 l/s 1 in 5yr peak flow approx. 564 l/s First flooding at MH south side of A417 1280 1 in 100yr peak flow approx. 1100 l/s Surcharge at culvert headwall 1330 1 in 100yr+cc peak flow approx. 1365 l/s (near Crickley Hill Farm) *These peak flow values don’t take account of flows entering the culvert on the north side of the A417 from Dog Lane. 5.2.2 The existing culvert can convey in bore a flow corresponding to a storm with a return period of approximately one to two years. Beyond this threshold the watercourse floods out of the manholes in Dog Lane on the north side of the A417, near Holly Brae. 5.2.3 The exceedance flow route in these events is west along Dog Lane and then south along Bentham Lane/Cirencester Road under the A417 at Witcombe Court underbridge and towards Little Witcombe. Flood flows may also cut the corner south west through the field west of Holly Brae. 5.2.4 It is estimated that the 1 in 100yr return period event can be conveyed through the upper sections of the culvert between Crickley Hill Farm and Dog Lane. 5.2.5 At rainfall events beyond the 1 in 100yr return period when the capacity in the upper section is exceeded, or if the culvert headwall becomes blocked, flooding can occur at the headwall and manholes on the southern side of the existing A417. 5.2.6 The overland flow routes for these exceedance events are west along the concrete access track serving the Crickley Hill Farm along the south side of the existing A417 and then to Cirencester Road. 5.2.7 Modelling indicates ambiguity about these flow paths, and it is possible that a proportion of this overland flow on the south side of the existing A417 may bifurcate south towards Green Lane.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000042 | C01, A3 | 11/03/21 Appendix Page xv Environmental Statement | HE551505 Highways England

5.2.8 To meet current design standards the design would replace the existing 600mm diameter pipe with a new culvert which is 1.35m minimum diameter/height. 5.2.9 To maintain the existing balance of flood risk on either side of the A417, the scheme would include overflows at the culvert headwall and manholes on the south side of the A417. 5.2.10 The weirs and overflows would be designed to ensure that the modified culvert replicates the hydraulic performance of the existing culvert. There is a degree of residual risk associated with the modelling due to the incomplete information about the existing culvert and the existing highway drainage systems in the upstream catchments. 6 Water quality 6.1.1 Assessments of the scheme road drainage have been undertaken in accordance with DMRB LA 113 and the Highways England Water Risk Assessment Tool (HEWRAT). 6.1.2 Reference is made to the Memorandum of Understanding between the Environment Agency and the Highways Agency Annex 1 - Water Environment, March 201112 and the England National Application Annex to DMRB LA 113, E/1.3: “NOTE: The Environment Agency has approved the method of assessment used by HEWRAT and has agreed that the outputs from the tool can be used when undertaking an assessment of potential impacts of surface water quality” 6.1.3 Each highway drainage catchment and outfall has been assessed using the HEWRAT methodology in DMRB LA 113, to ensure water quality characteristics and spillage risk are within acceptable limits, taking in to account the sensitivity and (WFD) status of the receiving groundwaters and watercourses. This has resulted in additional treatment measures being included in the highway drainage design. 6.1.4 The highway drainage design would include measures to manage the quality of run-off to surface and ground water bodies, including swales, grass channels, treatment strips, filter drains, soakaways, infiltration basins and settlement basins.

Water quality assessment 6.1.5 ES Appendix 13.4 Water Quality Assessment (Document Reference 6.4) reports the assessment of pollution impacts from routine run-off on surface water and groundwater.

Surface water quality assessment 6.1.6 All outfalls passed the surface water sediment assessment, but a number failed the Step 2 soluble pollutant assessment. 6.1.7 DMRB CG 501 Design of highway drainage systems outlines indicative treatment efficiencies of different pollution removal techniques, and this concludes that a treatment train of two or more pollution removal measures is adequate to meet the requirements of the HEWRAT assessment in most locations.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000042 | C01, A3 | 11/03/21 Appendix Page xvi Environmental Statement | HE551505 Highways England

6.1.8 All networks on the scheme include at least two levels of treatment comprising a basin (pond) along with at least one other measure. The assessment indicates that an additional level of treatment is required for the networks connecting to basins 2, 3a and 3c. 6.1.9 Additional mitigation (treatment) is therefore included within the drainage design to reduce the soluble pollutant load, and for this stage this would be provided in the form of a forebay within the basins. 6.1.10 The exact type and configuration of the basins would depend heavily on the specific ground conditions (suitability for infiltration) at each location and the preferred maintenance regime of the adopting body (Highways England or GCC). 6.1.11 This surface water quality assessment is based on a precautionary assumption that no infiltration would take place within the drainage systems and at the basins. When ground investigation data is available and the detailed groundwater quality assessments are completed at detailed design, there would be opportunities to introduce infiltration techniques and optimise the basin designs. Infiltration would also significantly improve the pollutant removal performance of the highway drainage systems. 6.1.12 The new highway drainage outfalls would not be provided with Oil Interceptors. This is consistent with both DMRB (CG 501 Design of highway drainage systems clause 8.7) for Highways England roads, and GCC’s preferred maintenance practices for local roads.

Groundwater quality assessment 6.1.13 A simple assessment has been undertaken following the procedures set out in Appendix C of DMRB LA 113. This is reported in ES Appendix 13.4 Water Quality Assessment (Document Reference 6.4), which identifies that there would be a medium risk of impact and that a detailed assessment should be undertaken. 6.1.14 The monitoring and baseline data required to inform a detailed groundwater assessment has not been undertaken. The site-specific information required to complete these assessments, such as local infiltration rate through the ground and ground conditions specific to the basin locations, would be undertaken to inform the detailed design. Baseline groundwater level and quality monitoring will continue and would inform these assessments. 6.1.15 The specific mitigation measures required in the design of drainage systems and basins would therefore be refined at detailed design. This could include measures to separate carriageway drainage systems from groundwater, the lining of basins, and limitations on the disposal of surface water through infiltration. 6.1.16 The western boundary of the scheme overlaps with a Source Protection Zone 3 (SPZ 3), but this does not place any limitations on the drainage design.

Accidental spillage 6.1.17 Accidental spillages risk is assessed in accordance with Appendix D of DMRB LA 113 and reported in ES Appendix 13.6 Spillage Risk Assessment (Document Reference 6.4). This concludes that the risk is acceptable without mitigation measures. Notwithstanding the results of the assessment, in accordance with good practice, it is proposed that carriageway outfalls from the A417 mainline, slip lanes (Highways

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000042 | C01, A3 | 11/03/21 Appendix Page xvii Environmental Statement | HE551505 Highways England

England) and junctions with the A417 (GCC) would be served by shut-off valves. This may also be extended to selected local roads with high traffic flows (such as the A436), if it is required by GCC. It is noted that isolation valves depend on dedicated points of discharge and this is less practicable for over the edge and SuDS solutions, that rely on diffused disposal of run-off. 7 Access and maintenance 7.1.1 The proposed A417 mainline and junction slip road drainage would be adopted and maintained by Highways England. All other highway drainage would be adopted by GCC. 7.1.2 Vehicular maintenance access would be provided to the Highways England and GCC basins. 7.1.3 Wherever possible, for the Highways England basins, this would be via local roads and the use of third-party tracks, rather than from the A417 mainline carriageway. 7.1.4 New tracks would typically be 2-3m wide (including room for turning where necessary) and constructed from unbound material. 7.1.5 GCC maintained basins and outfalls may be accessed either via dedicated accesses or laybys off the adjacent public highway. 7.1.6 GCC have published a SuDS Design & Maintenance Guide13 which outlines maintenance regimes for sustainable drainage assets including basins and ponds.

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000042 | C01, A3 | 11/03/21 Appendix Page xviii Environmental Statement | HE551505 Highways England

References

1 A417 Cowley to Brockworth Bypass Improvement, Drainage Strategy Report, WSP for Highways England, Jan 2005 2 A417 Missing Link Drainage Strategy Report, MMSJV for Highway England, PCF Stage 2, March 2019 3 A417 Normans Brook Tracer Test (HE551505-MMSJV-EWE-000-RP-LX-00003), MMSJV for Highways England, PCF Stage 2, 22 March 2019 4 Environment Agency, Risk of Surface Water Flooding Maps: https://flood-warning- information.service.gov.uk/long-term-flood-risk/map 5 DMRB – Design Manual for Roads and Bridges, Highways England https://www.standardsforhighways.co.uk/dmrb/ 6 UK Government, Flood risk assessments: climate change allowances, March 2020: https://www.gov.uk/guidance/flood-risk-assessments-climate-change-allowances 7 Gloucestershire County Council (Lead Local Flood Authority): Standing Advice and Development Guidance, March 2015; and FRA Guidance for Surface Water in all developments, March 2015: https://www.gloucestershire.gov.uk/planning-and- environment/flood-risk-management/surface-water-drainage-and-major-planning- applications/ 8 UK Government, Non-statutory technical standards for sustainable drainage systems, March 2015, Defra: https://www.gov.uk/government/publications/sustainable-drainage- systems-non-statutory-technical-standards 9 CIRIA Report C753, 2015 - SuDS Manual 10 CIRIA Report C786, 2020 – Culvert, Screen and Outfall Manual 11 CIRIA Report C635, 2006 - Designing for Exceedance in Urban Drainage 12 Memorandum of Understanding between the Environment Agency and the Highways Agency - Annex 1 Water Environment: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_ data/file/341286/MoU_HA_and_EA_ANNEX_1_Water_latest_version_March_2011.pdf 13 Gloucestershire County Council SuDS Design & Maintenance Guide, Nov 2015: https://www.gloucestershire.gov.uk/planning-and-environment/flood-risk- management/surface-water-drainage-and-major-planning-applications/

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000042 | C01, A3 | 11/03/21 Appendix Page xix Environmental Statement | HE551505 Highways England

Annexes

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000042 | C01, A3 | 11/03/21 APPENDIX PAGE i Environmental Statement | HE551505 Highways England Annex A Highway Drainage Records

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000042 | C01, A3 | 11/03/21 APPENDIX PAGE ii

RMS (Gloucester) Ltd. RMS (Gloucester) Ltd. RMS (Gloucester) Ltd. RMS (Gloucester) Ltd. Environmental Statement | HE551505 Highways England Annex B Existing Highway Drainage

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000042 | C01, A3 | 11/03/21 APPENDIX PAGE iii ANNEX B: EXISTING HIGHWAY DRAINAGE - CATCHMENTS

REFER TO ES FIGURE 13.18 EXISTING HIGHWAY DRAINAGE - PLAN (DOCUMENT REFERENCE 6.4)

Impermeable Area Catchment Road Name Highway Authority Impermeable Area (Ha) Type of Outfall Pollution Controls Attenuation Measures Details of Outfall Watercourse / catchment (m2)

Piped outfall to ditch at Old Coach Road Norman's Brook Tributary E1-West A417 HE 15,158 1.516 Watercourse Catchpits, gullies None identified Highway drainage intercepts land drainage on North side of A417 (Bentham) (Stream at Crickley Hill)

A417 drainage connects to E1-West network via 450mm diam. pipe on North side of Norman's Brook Tributary E1-East A417 HE 10,192 1.019 Watercourse Catchpits, gullies None identified Witcombe Court Underbridge (Stream at Crickley Hill)

West: Piped connection to culverted watercourse (Crickley Hill Stream) Norman's Brook Tributary E2 A417 HE 12,825 1.283 Watercourse Gullies, (catchpits?) None identified East: Piped outfalls to Crickley Hill Stream (3-4 no) . (Stream at Crickley Hill) Highway drainage intercepts land drainage on North side of A417 (Crickley Hill)

Piped outfall to Crickley Hill Stream in vicinity of Grove Farm. Norman's Brook Tributary E3 A417 HE 5,826 0.583 Watercourse Gullies, (catchpits?) None identified Highway drainage intercepts land drainage on North side of A417 (Crickley Hill) (Stream at Crickley Hill)

Soakaways. E4-A (Nth) section: 2 soakaways. Overflow route is to E4-B River Churn E4-A Nth A417 HE 5,485 0.549 Soakaways Catchpits, gullies, filter drains (Soakaways) Highway drainage intercepts land drainage on East side of A417 Birdlip Hill (Emmas (via Ullenwood, Coberley) Grove)

E4-A (Sth) section served by a network of 10 soakaways at embankment near Four Winds farm. Norman's Brook Tributary E4-A Sth A417 HE 6,752 0.675 Soakaways Catchpits, gullies, filter drains (Soakaways) Primary overflow route west to watercourse at Four Winds (connects to Crickley Hill Stream (Stream at Crickley Hill) via Grove Farm), but possible overflow route north to E4-A (Nth)

A417/A436 Air Balloon Overflow/outfall to Soakaway at Ullenwood CC. E4-B HE 2,814 0.281 Soakaways Catchpits, gullies, filter drains (Soakaways) N/A Roundabout (No connection to E3)

Soakaways with E5-A417 A417 HE 3,001 0.300 Catchpits, gullies, filter drains (Soakaways) Overflow connections to E5-BW (Barrow Wake) N/A overflow to E5-BW

Outfall/overflow to watercourse at Four Winds (connects to Crickley Hill Stream via Grove Norman's Brook Tributary E5-BW Barrow Wake GCC 7,760 0.776 Watercourse Gullies (Soakaways) Farm) (Stream at Crickley Hill)

Catchpits, gullies, filter drains, Ditches and soakaway E6 A417 HE 11,433 1.143 Soakaways Ditch connects to pond/soakaway in copse. Exceedence overflow route is to Coldwell Bottom N/A ditches pond

Soakaway to overflow Catchpits, gullies, filter drains, Ditches and soakaway No positive connection to watercourse. Likely exceedence overflow route is to dry valley to E7 A417 HE 4,020 0.402 N/A to dry valley ditches overflowing to dry valley west (Parsons Pitch)

Soakaway, with Section north of Stockwell Lane is partially served by soakaways. (approx 50%). 375mm E8-West A417 HE 3,500 0.350 Catchpits, gullies, filter drains (50% Soakaways) River Frome overflow to E8-West diam overflow connection to E8-East

Gullies, (catchpits?), filter E8-East A417 HE 10,769 1.077 Watercourse None identified Piped connections to culvert at Nettleton Bottom River Frome drains

Catchpits (mainline), Gullies(roundabout), Lagoon, Combined A417, local roads and land drainage network outfalls via (HE) PI & lagoon E9-Nth (HE) A417 HE 11,077 1.108 Watercourse Lagoon River Frome Petrol Interceptor, shut off Highway drainage intercepts land drainage on East side of A417 valve

Cowley Junction (local Combined A417, local roads and land drainage network outfalls via (HE) PI & lagoon. E9 (GCC) GCC 6,612 0.661 Watercourse Catchpits, Gullies, Lagoon Lagoon River Frome roads) Highway drainage intercepts land drainage on East side of A417

Catchpits (mainline), Lagoon, E9-Sth (HE) A417 HE 11,288 1.129 Watercourse Petrol Interceptor, shut off Lagoon Combined A417, local roads and land drainage network outfalls via (HE) PI & lagoon River Frome valve

TOTAL (A417)* 87,695 8.769

TOTAL (GCC) 14,372 1.437 soakaway 3.801 43% *A417 only, Cowley UB to Witcombe Court UB) watercourse 4.968 57%

Paved areas (E2, E3) may be taken in to account for A417 ML storage calculations 1.865 (stream at Crickley Hill) Paved areas (E9-Nth) may be taken in to account for A417 ML storage calculations 1.108 (River Frome) Paved areas -' like for like' area may be applied in A417 Missing Link calculations 1.019 Environmental Statement | HE551505 Highways England Annex C Scheme Highway Drainage

HE551505-ARP-EWE-X_XX_XXXX_X-RP-LE-000042 | C01, A3 | 11/03/21 APPENDIX PAGE iv ANNEX C: SCHEME HIGHWAY DRAINAGE - CATCHMENTS

REFER TO ES FIGURE 13.19 SCHEME HIGHWAY DRAINAGE - PLAN (DOCUMENT REFERENCE 6.4)

Proposed Area (m2) Storage Requirement (m3) Catchment ID Road/Catchment Adopting Paved Earth- Total Area PIMP (%) Catchment Comments Attenuation/Storage Receiving watercourse Highway works Cutting/ Attenuation Long Term Storage Qbar (l/s) Authority (inc basins) Embankment Storage Storage Volume (ICoP)

Area west of Witcombe Court UB - receives the attenuated discharge from Catchment 2. Crickley Hill Stream 1 A417 (west of Witcombe Court UB) HE 14,005 11,457 25,462 55 At grade Existing outfall, Old Coach Road. n/a. Existing ---- (Tributary of Norman's Brook) Outfall also intercepts 8.8ha (88,000m2) rural catchment on north side of A417 Connection to existing catchment E1-West/P1 Existing Highway Network E1, Old Coach Road, Embankment 4.22 2 A417 (Witcombe Court UB to Grove Farm) HE 53,825 12,499 66,325 81 Basin sized to attenuate Q100+40%cc event. Flow limit based on Existing Catchment E1-East (1.2ha). Basin No 2 Crickley Hill Stream 7951 1760 9711 & Cutting (N/A) Lower bound limit the greater of 5l/s or 2l/s/ha (Tributary of Norman's Brook)

Crickley Hill Stream 3W A417 (Grove Farm to Air Balloon) HE 19,683 7,664 27,347 72 Cutting Basin next to Grove Farm with access via underpass Basin No 3c 9.6 2505 676 3181 (Tributary of Norman's Brook)

Basin south west of new Ullenwood junction roundabout. Outfall/overflow under roundabout to dry valley near Dry Valley (National Star College, Town End 3E A417 (Air Balloon to Shab Hill) HE 37701 20,051 57,752 65 Cutting Basin No 3a 20.3 4906 1191 6097 Leckhampton Hill and basin 5 Coberley, River Churn)

6 A417 (Shab Hill Nth, inc nb slip road) HE 20,858 11,727 32,585 64 Embankment Basin inside slip lane loop on west side. Connection to culvert under junction. Basin No 6 Dry Valley /Ditch (Coldwell Bottom, River Churn) 11.8 2944 748 3692

8 A417 (Shab Hill Sth, inc sb slip road) HE 8,800 2,665 11,465 77 Embankment Basin inside slip lane loop on east side. Connection to culvert under junction Basin No 8 Dry Valley /Ditch (Coldwell Bottom, River Churn) 4.0 941 142 1191

9 A417 (Shab Hill to Cowley Lane OB) HE 18,935 20,144 39,078 48 Cutting Connection to ditch. Overflow flood culvert through landscape bund. Basin No 9 Dry Valley /Ditch (Coldwell Bottom, River Churn) 13.8 2962 583 3545

10 A417 (Cowley Lane OB to Stockwell Acc OB) HE 25,167 32,559 57,727 44 Cutting Ditch or pipe to Nettleton Bottom (culvert under existing A417). Overflow flood culvert through landscape bund. Basin No 10 Dry Valley (Nettleton Bottom, River Froome) 20.3 4217 762 4979

See GCC catchments 13a & 13b 11 A417 Mainline (Stockwell Acc OB to Cowley Junction) HE 29,947 35,894 65,841 45 Cutting Basin group 11 River Froome 23.1 4874 911 5785 New outfall to re-use route/upgrade existing outfall south of Brimpsfield Lane Slip lane connects to existing highway drainage at junction. Road area equivalent to existing 13b Cowley junction (east - slip lane) HE 3,894 312 4,206 93 Cutting Existing lagoon River Froome ---- Re-use existing outfall & lagoon (Inc PI). Adjacent WCHR/access would be GCC maintained Catchment south of Cowley UB is unaltered. Total area equal to or less than existing. Re-use existing outfall & lagoon 12 A417 (sth of Cowley Junction) HE 27,539 37,457 64,996 42 Embankment Existing lagoon River Froome ---- (Inc PI). Area would include some local GCC roads (4472m2)

m2 218,810 143,515 362,325 m2 TOTAL (HE) (exc 1 & 12) Ha 21.88 14.35 36.23 Ha

Proposed Area (m2) Storage Requirement (m3) Catchment ID Road/Catchment Adopting Paved Earth- Total Area PIMP (%) Catchment Comments Attenuation/Storage Receiving watercourse Highway works Cutting/ Attenuation Long Term Storage Qbar (l/s) Authority (inc basins) Embankment Storage Storage Volume (ICoP)

Repurposed lane 1 of existing A417. Consider equivalent paved area At grade Proximity to A417. Source control/linear attenuation within road corridor. Connection to Crickley Hill Stream under A417 Linear attenuation Crickley Hill Stream 4b WCHR route (Dog Lane to Cold Slad Lane) N/A 3,622 5,055 8,677 42 3.1 508 79 587 (existing) near bat underpass and to existing culvert at Dog Lane (Crickley Hil Stream). Run-off from hill side intercepted /source control (Tributary of Norman's Brook) separately from road drainage where practical.

Repurposed lane 1 of existing A417. Consider equivalent paved area At grade Linear attenuation Crickley Hill Stream 4a Cold Slad Lane GCC 4,263 2,451 6,714 63 Proximity to A417. Source control/linear attenuation within road corridor. Connection to Grove Farm culvert (Crickley Hill 2.4 442 103 545 (existing) /source control (Tributary of Norman's Brook) Stream) via Grove Farm underpass. Run-off from hill side intercepted separately from road drainage where practical.

Infiltration opportunities at roundabout & basins Cutting/ Dry Valley (National Star College, Town End 5 A436 (north) & New AB Roundabout GCC 22,224 14,793 37,017 60 Basin north east of Ullenwood junction with overflow towards golf course/dry valley between Leckhampton Road and Basin group 5 13.0 3076 748 3824 at grade Coberley, River Churn) A436.

Access Road (Cuckoopen Farm Nth) Cutting/ Dry Valley /Ditch (Ullenwood, National Star 7c GCC 1,728 300 2,029 85 Access road is unclassified highway. Storage in ditches and swales in verges Swales/source control 0.7 86 0 86 Unclassified road to be adopted by GCC Embankment College, River Churn)

A436 (south), B4071 east, Shab Hill rdbts Cutting/ 7b GCC 21,253 21,732 42,985 49 Accesses on B4071 are unclassified highways. Basin inside sthbd slip loop. Connection to flood culvert under junction Basin No 7b Dry Valley /Ditch (Coldwell Bottom, River Churn) 15.1 3245 634 3879 PMAs/unclassified roads, inc Cuckopen Farm (Sth) Embankment

Tank/soakaway under Barrow Wake Car Park. May be substituted with geocellular tank. Existing soakaways may be Crickley Hill Stream (Tributary of Norman's Brook) 7a B4071 west (Barrow Wake) GCC 7,515 6,036 13,552 55 At grade utilised and/or upgraded. Condition & efficacy of existing drainage uncertain. Existing car park & highway currently Tank/soakaway 4.8 980 152 1132 via Grove Farm drains informally to adjacent GWT land with overflow to Grove Farm (Crickley Hill Stream) Crickley Hill Stream (Tributary of Norman's Brook) Cutting/ Re-use and adapt existing highway drainage systems. Possibly drains informally to adjacent land and/or infiltrates to 14 B4071 (existing) GCC 6,144 227 6,372 96 Swales/existing via existing (informal) outfalls to surrounding fields ---- Embankment ground. (est).

Slip lanes and rdbt connect to HE catchment 12. GCC road/rdbt area equivalent area to existing 13a Cowley Junction (west) GCC 4,805 437 5,242 92 At grade Existing lagoon River Froome - --- Re-use existing outfall & lagoon (Inc PI).

TOTAL (GCC) m2 24,922 45,749 107,538 m2 (exc 4b & 14) Ha 2.49 4.57 10.75 Ha

NOTES 1 Parameters used: Qbar (l/s/ha): 3.52 l/s/ha Qbar rural (Ethwks Cv=0.40, R=0.3, M5-60=20, SAAR=872, SPR=0.37) 2 Minimum flow thresholds: 5l/s and 2l/s/ha

Page 1 HE551505-ARP-HDG-X_XX_XXXX_X-CA-D-000002.xlsx