Langstone Detailed Design

Updated August 2022

In April 2021, the Project Team appointed the specialist support of professional services to deliver the development of the project through the next phase of detailed design.

We have been working to bring in the specialist services of a Design Consultant, Heritage and Archaeological Support, Early Contractor Involvement, and a Cost Consultant.

Following competitive procurement undertaken on behalf of Havant Borough Council, the following companies have been successful in their appointment to the following roles.

  • Detailed Design Consultant and Landscape Architect – AECOM
  • Heritage and Archaeological Support – Wessex Archaeology
  • Cost Consultant – Faithful & Gould
  • Early Contractor Involvement – Mackley

What is Detailed Design?

The options appraisal culminated in an outline design proposal for the most achievable solution, also known as the ‘leading options’. The detailed design phase progresses these leading options to a higher level of design detail needed to finalise proposals prior to construction (see Figure 1).

The detailed design is presented at three key milestones:

  • 50% Completion
  • 80% Completion
  • 100% Completion
Figure 1 Timeline Figure 1 Timeline
Figure 1 Timeline

There are several key areas which are refined in an iterative process throughout detailed design as it progresses between 0 and 100% completion:

Design and Buildability

The Design Consultant will complete the structural, geometric and interface designs as well as prepare the necessary design drawings. As well as using their own experience, they will collaborate on the design with a Contractor, who has experience in the successful delivery of similar coastal schemes to ensure the design considers its buildability in its unique setting. These will be used to provide detail for the planning approval and consenting process, and also in Construction.

Materials, Appearance and Finish

Further work will be undertaken at this stage of design to establish the necessary materials required for construction, and to develop visualisations of the final appearance and finish. We will seek wherever possible to work together with the community, through representative groups (including the Langstone Stakeholder Working Group), and our stakeholders for the selection of the materials and finishes.

It is very important that the appropriate materials and finishes are chosen so that they are acceptable to the regulators and valued by the local community. There will be opportunities for feedback on the proposals and we welcome comments from residents and stakeholders. Generally, this is finalised towards the latter stages of detailed design.


Detailed design will enable us to refine our cost estimation for building and operating the scheme. To ensure affordability, an independent Cost Consultant will work with Coastal Partners and AECOM throughout the design stage. Affordability elements of the scheme will include:

  • Increase cost certainty on the whole life costs of the Langstone FCERM Scheme
  • Investigate and draw upon partnership funding contributions to close a funding shortfall for delivery
  • Refine the financial business case to be made to draw down funding administered by the Environment Agency

This element links closely with the other design elements, and will be most certain towards the latter stages of detailed design. For further information on costs and funding please visit the Funding Webpage.

Operation of Active Flood Assets

The new flood defence scheme at Langstone proposes the introduction of some active flood defence assets, such as flood gates. These are required to be closed when high water levels are anticipated.

Working in partnership with the community and HBC, AECOM will develop a robust operation procedure.

An important part of this procedure will be to collaborate with any Community Flood Plan and local flood resilience activities. This element will be considered during the latter stages of detailed design once the designs have been developed and refined.

Environmental Impact Assessment

To support the detailed design, we will undertake research to build the evidence base for the Environment Impact Assessment (EIA). EIA is a tool used to identify the environmental, social and economic impacts of a project prior to decision-making for approval of the required licences and consents.

We have produced an EIA Screening and Scoping report setting out what we believe to be necessary for inclusion in the EIA, and this has been submitted to our regulators for their opinion.

We are anticipating that an EIA will be required and that the following assessments will need to be included as a minimum:

  • Marine and Terrestrial Ecological Surveys and assessments
  • Bird Surveys and assessment
  • Habitat survey and assessment
  • Heritage Statement
  • Landscape and Visual Impact Assessment

Approvals, Licensing and Consents

In preparation for construction, the following applications will be submitted for licences and consents:

Approval, Licenses and Consents
Planning Permission and discharge planning consents
Listed building consents
Marine License 
Harbour Works Licenses 
Land Drainage Act Notices
Flood Risk Action Plan (FRAP)

Progress to Date

50% Design NOW COMPLETE (July 2022)

AECOM commenced the detailed design stage in April 2021, and have since been working towards the development of the design to 50% refinement.

Preparation for this stage involved a number of activities which are summarised in Figure 2 and explained further below.

Figure 2 - Design Figure 2 - Design
Figure 2 - Design

Data Review

AECOM drew together the available data sources collated during the Option Appraisal and Outline Design stage to clarify understanding and identify any data gaps.

Community Engagement

Community Working Day (July 2021)

During the design process, we were able to offer the opportunity for the community to meet with the team in Langstone over two evenings and explore the developing designs for all frontages.

An Event Summary Document was prepared to provide the following:

  • The objectives of the Community Participation Evenings
  • The agenda
  • Summary of each evening
  • Next steps
  • Questions and Answers

Access the Event Summary Document.

Engagement with Frontline Residents and Landowners (Ongoing)

Meetings have been held with those who are directly impacted by the scheme proposals. These discussions have helped to shape the design requirements.

Where access has been required for investigations, this has been sought directly with landowners.


Design Refinement

The engagement events invited feedback from the Community which had several key influences on the direction of design for a number of frontages as shown in Figure 3.

Figure 3 Engagement Influences Figure 3 Engagement Influences
Figure 3 Engagement Influences

AECOM focused on design refinement for all frontages, incorporating these key influences on design. The refined leading options are summarised in this leaflet.

Structural Investigation (Completed Autumn 2021)

During earlier consultations we received feedback regarding the inclusion of some existing structures (walls) in the design. Following this, the design consultant undertook targeted structural investigation of the existing walls to establish their condition and potential to be incorporated into the scheme and sea defences.

Structural investigations as part of this phase of the project were undertaken in the following areas:

  • The walls between the Ship and Langstone High Street.
  • The quay wall in front of the Royal Oak and adjacent properties.
  • Private defences at Mill Lane and Harbourside.

These investigations were undertaken in a phased approach to limit risk and intrusion into private property. The scope and extent of each phase was tailored and refined based on the results of the previous stage and did not require intrusive investigations.

The results of the structural investigation confirmed that we cannot rely on the existing walls and other structures as these would not provide the necessary standard of protection. Therefore, they cannot form part of the design of the new structures.

Ground Investigation (Completed Autumn 2021)

Further Ground Investigation was required to support the detailed design and construction stages of the Scheme. This built upon a review of available information and aimed to complete our understanding of ground conditions over the whole scheme alignment.

The work involved undertaking in-situ testing and collecting samples for laboratory analysis.

For more information on the works, please refer to the information leaflet.

The GI works were minimal in terms of extent and duration and were carefully planned in terms of access, timings, and environmental considerations. Works were undertaken outside of the overwintering bird period and ecological and archaeological watching briefs were present throughout. All the necessary licences and consents were obtained to undertake these works and access was negotiated where required.

Langstone Ancient Wade Way Langstone Ancient Wade Way

Ecological Surveys and Studies

Coastal Partners are passionate about the environment. Undertaking coastal projects can provide opportunity to enhance the environmental biodiversity where appropriate. Ecological surveying will contribute towards our understanding of the habitats, landscape and heritage of the area. Coastal Partner’s Environmental Team have undertaken several different surveys and studies as part of this stage.

The following surveys have been recently completed:

  • Breeding and Overwintering bird surveys
  • Bat and Badger survey
  • Reptile Survey
  • Botanical Survey
  • Habitat Suitability Index assessment for Great Crested Newt
  • Tree survey and Arboricultural Impact Assessment
  • Phase 2 Intertidal Survey

Utilities Data

The structural investigations also provided better understanding of the location of utilities. These have been confirmed through meetings with utility asset owners to understand how the design can incorporate utilities provision and avoid disruption of these services.

The 5th Langstone Stakeholder Working Group

Further information is on the Langstone Stakeholder Working Group webpage.

Artistic Illustrations

The designer (AECOM) has prepared new artistic impressions to convey the latest design. These were first presented at the 5th Langstone Stakeholder Working Group in July 2022.

These show the main features of the proposals for each frontage, but some elements are yet to be decided such as appearance, construction materials and finishes.

What happens next?

Working towards the 80% design milestone

AECOM will continue to refine the design ‘picture’ further, incorporating advice from the Early Contractor Involvement, Cost Consultant and Heritage Consultant, and feedback from Stakeholders. The 80% design milestone looks to present a clearer picture of the appearance, construction materials and finishes.

The outcomes of this stage will be presented at the 6th Langstone Stakeholder Working Group, and at a public exhibition later in 2023. Further detail to follow.

The 80% design milestone sits within the detailed design phase of the project as shown in Figure 4.

Figure 4 Timeline Figure 4 Timeline
Figure 4 Timeline