Colwyn Bay Flood Defence - Phase1 Whole Project Award

Project Team
Client: Conwy County Borough Council
Designer: Mott MacDonald
Contractor: VolkerStevin

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Project summary

The coastal defences along the Colwyn Bay frontage had several key issues to address through developments and improvements. As a result of regular over-topping of the defences, the defences themselves were being negatively impacted, as well as local infrastructure, and the local community through the regular closing of the coast road after storm damage. The ageing and deteriorating defences had an imminent risk of failure if they were left in situ.

Aerial view of Colwyn Bay and the developments to the Bay's frontage

Work on the defences was divided into phases - this assessment covers the phase 1 works at the eastern end of the bay, opposite Erias Park. Work included construction of a rock groyne, rock and pre-cast concrete step revetments, creation of a permanent beach, and an extension to the existing promenade in the area. The platform created by the promenade extension had concrete piles installed which were used for the construction of the new water sports building which has a viewing area on the roof, and links into the upgraded promenade with cycle lanes and landscaped areas.

Eventually the whole of the bay will be developed, with renewed sea defences and integrated environmental improvements along the promenade. There will also be environmental regeneration improvements to the promenade to offer a usable and safe and sustainable public realm space. This first phase of works is the platform for the whole project.

Challenges faced and Achievements

Material Use

The nature of the works mean that a lot of material has been brought on to site to build up the beach and rock groynes. In order to make this as sustainable as possible, comprehensive policies were written into the Environmental Statement which was produced in the early planning stages highlighting issues such as reusing existing boulders, prioritising local suppliers and transporting sand for the beach recharge to the site via the sea. During the design stage it was confirmed that all timber purchased by VolkerStevin (the contractor), their subcontractors, or their suppliers would be legal, sustainable, and FSC/PEFC certified. The Armourstone was sourced from local quarries, the class 6A, 6F1 and 6P material was sourced locally from Menmaenmawr, and the Hauraton Environkerb was constructed from recycled material as an alternative to the ACO Kerbdrain system. In addition, 100% of the existing structures on site were incorporated into the design.

Sand being laid to create beach profile

Ecology and Biodiversity

The new flood defence structures included in the design will encourage new marine habitats to develop over time. In addition, the new groyne structures and sand recharge will create a new ocean habitat - these have been witnessed in situ - photos are available on request. The sand may provide valuable new habitat for the BAP species, Mytilus edilus (Blue mussel).

Bioblocks are also incorporated into the groyne structure to encourage and monitor habitat growth. Photos of these are available on

To what extent did the use of CEEQUAL influence your project?

Sustainability has been integral to the whole Waterfront project and has been taken into account right from the start. Conwy County Borough Council stated that a ‘very high level of environmental performance was to be a key aspect of the Colwyn Bay Waterfront Development project’. The flood defence and infrastructure works aimed to achieve a CEEQUAL target of at least Very Good. A high level sustainability review was carried out to investigate potential risks and opportunities. A CEEQUAL pre-assessment was carried out which included verbal discussions with the client as to what issues were to be targeted and which were not likely to be achieved. When the designer and contractors were both appointed further CEEQUAL reviews were carried out to ensure that both were fully aware of the requirements of the assessment and the types of evidence that would be required. It was important that the team did not have to produce CEEQUAL specific information, rather the drawings and reports that were being produced as part of the project were suitable. By introducing CEEQUAL early in the project, the project has managed to achieve its target of Very Good.

New beach at Colwyn Bay

Beach and rock groyne