A428 Black Cat to Caxton Gibbet improvements TR010044 Volume 6 Volume 6.3 Environmental Statement Appendix 6.7: Archaeological Evaluation Trenching Phase 2 Planning Act 2008 Regulation 5(2)(a) Infrastructure Planning (Applications: Prescribed Forms and Procedure) Regulations 2009 26 February 2021 A428 Black Cat to Caxton Gibbet improvements Environmental Statement – Appendix 6.7: Archaeological Evaluation Trenching Phase 2 Infrastructure Planning Planning Act 2008 The Infrastructure Planning (Applications: Prescribed Forms and Procedure) Regulations 2009 A428 Black Cat to Caxton Gibbet improvements Development Consent Order 202[ ] Appendix 6.7: Archaeological Evaluation Trenching Phase 2 Regulation Reference: APFP Regulation 5(2)(a) Planning Inspectorate Scheme TR 010044 Reference Application Document Reference TR010044/APP/6.3 Author A428 Black Cat to Caxton Gibbet Project Team, Highways England Version Date Status of Version Rev 1 26 February 2021 DCO Application Planning Inspectorate Scheme Ref: TR010044 Application Document Ref: TR010044/APP/6.3 Written Scheme of Investigation for archaeological trial trench evaluation along the proposed route of the A428 Black Cat to Caxton Gibbet Improvement Scheme Phase 2 April 2020 Authors: Adam Douthwaite and Gary Brogan Illustrator: Olly Dindol MOLA Northampton 2020 MOLA Project Manager: Gary Brogan Kent House NGR: TL 515468 255438 to TL 529651 260657 30 Billing Road Accession Number: BEDFM.2019.41/ECB6150 Northampton NN1 5DQ 01604 809 800 www.mola.org.uk [email protected] Written Scheme of Investigation for archaeological trial trench evaluation along the proposed route of the A428 Black Cat to Caxton Gibbet Improvement Scheme Phase 2 April 2020 Quality control and sign off: Issue Date Checked by: Verified by: Approved by: Reason for Issue: No. approved: 1 22/04/2020 Gary Brogan Rob Atkins Gary Brogan Draft for AECOM review 2 23/04/2020 Gary Brogan Rob Atkins Gary Brogan Incorporates AECOM comments Authors: Adam Douthwaite and Gary Brogan Illustrator: Olly Dindol MOLA Northampton 2020 MOLA Kent House 30 Billing Road Northampton NN1 5DQ 01604 809 800 www.mola.org.uk MOLA Northampton is a company limited by guarantee registered in England and Wales with company registration number 8727508 and charity registration number 1155198. Registered office: Mortimer Wheeler House, 46 Eagle Wharf Road, London N1 7ED. Written Scheme of Investigation for archaeological trial trench evaluation along the proposed route of the A428 Black Cat to Caxton Gibbet Improvement Scheme: Phase 2 SITE NAME: A428 Black Cat to Caxton Gibbet Improvement Scheme NATIONAL GRID REF: TL 515468 255438 (Black Cat) to TL 529651 260657 (Caxton Gibbet) CLIENTS: Skanska on behalf of Highways England DATE: April 2020 EVENT/ACCESSION NUMBER: BEDFM 2019.41 (BEDFORD BOROUGH and CENTRAL BEDFORDSHIRE) ECB6150 (CAMBS) CONTRACTOR: MOLA Kent House 30 Billing Road Northampton NN1 5PN MOLA Page 1 of 61 A428 BLACK CAT TO CAXTON GIBBET IMPROVEMENT SCHEME 1 INTRODUCTION Project Background 1.1 Highways England plans to improve the A428 trunk road between The Black Cat roundabout in Bedfordshire and Caxton Gibbet, in Cambridgeshire. These works are known as the A428 Black Cat to Caxton Gibbet Improvement Scheme. In support of these proposals a staged programme of archaeological investigations has been commissioned. 1.2 An overarching programme for the archaeological works is set out by the Design Consultant in the A428 Black Cat to Caxton Gibbet Scope of Works (AECOM 2020a) which follows works detailed in the Design Brief for Archaeological Evaluation (Cambridgeshire County Council 2019). The stages of investigations are set out in these documents. • A desk-based assessment as part of the Environmental Impact Assessment. This has been carried out by AECOM, the Design Consultants (AECOM 2020b). • A geophysical survey of the proposed route. This has been undertaken by MOLA Headland Infrastructure in 2019 to 2020 and was carried out in three phases (MHI 2020a and b). • Trial Trench evaluation across the proposed route and associated works, such as temporary and permanent works, including (but not exclusively) borrow pits, soil storage areas, compounds and flood alleviation works. 1.3 This Written Scheme of Investigation (WSI) describes the works associated with Phase 2 of the trial trench evaluation and will test anomalies and target blank areas of land within the scheme footprint that were subject to Phase 2 of the geophysical survey (Fig 1; Figs 8-12). The WSI has also been produced in accordance with current best archaeological practice as defined in the Chartered Institute for Archaeology’s Code of Conduct (CIfA 2019) and Standards and Guidance documents (CIfA 2014a, b and c) and conforms to Management of Research Projects in the Historic Environment (MoRPHE) (HE 2015a). 1.4 MOLA (Museum of London Archaeology) has been commissioned by the Main Contractor, Skanska, on behalf of Highways England, as Archaeological Contractors to carry out the Phase 2 archaeological trial trenching. MOLA undertook the Phase 1 trial trench evaluation between January and April 2020. MOLA will, if required, sub-contract part of the archaeological work to the Cambridge Archaeological Unit (CAU) who will provide archaeological labour during the fieldwork and some specialist support during the post- excavation phase (see 7.8). 1.5 The scheme red line boundary as illustrated (Figs 1-12) is out of date and does not reflect recent changes. Reason for Trial Trenching 1.6 The Proposed Scheme is a Nationally Significant Infrastructure Project (NSIP). Due to the high archaeological potential of the landscape, information on the potential impact of the Proposed Scheme on the archaeological remains is required to be submitted to the Planning Inspectorate to inform the Development Consent Order (DCO) application process, in line with the policies set out in Highways England’s Design Manual for Road and Bridges (DRMB) (Highways England 2019a). The results of the archaeological evaluation works are required to be completed in advance of the Development Consent Order (DCO) confirmation, in order to confirm the scope of archaeological mitigation excavations that will be required prior to release of archaeological priority areas for construction. MOLA Page 2 of 61 A428 BLACK CAT TO CAXTON GIBBET IMPROVEMENT SCHEME 1.7 The results of the archaeological evaluation works are required to be completed in advance of the DCO being made, in order to confirm the scope of archaeological mitigation excavations that will be required prior to release of archaeological priority areas for construction. The archaeological evaluation works are programmed to be undertaken in three phases; however, the extent of information available at DCO application submission will be dependent on land access availability and crop cycles. Wherever possible, the results of the evaluation trenching will be used to inform the Environmental Impact Assessment process, so that likely significant effects can be identified and mitigation measures agreed. Should the assessment be limited by incomplete or unavailable data, other information sources (e.g. results of other evaluation methods and research presented in the desk-based assessment) will be used to undertake and report a ‘worst case’ assessment on archaeology. Where the results of the evaluation trenching are only available post submission of the DCO application, these results and any required updates to the impact assessment will be submitted to the DCO Examination as further information. 1.8 This information will also be shared with Cambridge County Council, Central Bedfordshire and Bedford Borough Councils to allow their archaeological specialists to comment and submit representations to the DCO examination to inform the decision making process. In order to provide this information an archaeological evaluation of the route is necessary. 2 BACKGROUND Location (Fig 1) 2.1 The proposed development is a 17km road improvement scheme, 12km of which is located in Cambridgeshire and 5km in Bedfordshire (partly in both Central Bedfordshire and Bedford Borough), and it will create a new duel carriageway from the A1/A421 Black Cat Junction to the A428/A1198 Caxton Gibbet Junction. 2.2 The proposed alignment runs west to east, crossing the River Great Ouse, Barford Road and the East Coast Main Line (ECML) railway, where it turns to the north-east. The route crosses Potton Road and the B1046 to the east of Little Barford Power Station and St Neots, before connecting with the existing A428 at the B1428 Cambridge Road junction. From here it is aligned approximately west to east and situated to the north of, and roughly parallel to, the existing A428. It passes to the north of the villages of Croxton and Eltisley, finally terminating to the east of the existing Caxton Gibbet Roundabout on the existing A428. Topography (Fig 2) 2.3 The scheme footprint passes through a number of distinct topographical areas. At the western end of the route is dominated by the Great Ouse valley, and the confluences of the River Great Ouse, the River Ivel, the Begwary Brook, and the Stone Brook. Here the route is at the lowest point at approximately 20m above Ordnance Datum (aOD). To the north-east, the route climbs a ridge of higher ground, located at c50m aOD, before dropping into the valley of the Abbotsley/Hen and Wintringham Brooks, which are further tributaries of the River Great Ouse that confluence in the centre of St Neots. To the east of Wintringham Brook the route follows a ridge of high ground, at approximately 60-65m aOD where it passes to the north of the villages of Croxton and Eltisley. These watercourses have directly influenced the siting of settlement activity throughout all periods, including late Saxon villages and medieval moated manors on the periphery of St Neots. MOLA Page 4 of 61 A428 BLACK CAT TO CAXTON GIBBET IMPROVEMENT SCHEME Geology (Fig 3) 2.4 The solid geology of the western and central sections of the scheme, where it crosses the River Great Ouse and climbs the eastern valley side, is mudstone of the Jurassic Age (Kellaways and Oxford Clay formations).