Shoreham Adur tidal wall, UK

One such area is Shoreham-by-Sea on the Adur estuary in West Sussex. Existing tidal flood defences didn't offer sufficient protection against forecast future storm events, placing more than 2,300 households and 150 commercial properties at significant risk of flooding.

Opportunity

To reduce flood risks to the town, the Environment Agency sought to improve more than 7km of tidal defences along the east and west banks of the River Adur. We delivered the detailed design of the £45M scheme, known as the Shoreham Adur Tidal Walls (SATW). The scheme separated the repairs and upgrades into 10 reaches covering 7.2km of river frontage, and included various defence structures, such as sheet pile walls, reinforced concrete walls, and flood embankments, glass walls and gates.

Solution

Our environmental impact assessment (EIA) ensured the effects of construction work on the environment were minimal. We also used the EIA to identify opportunities to improve the area. Our town planners worked closely with ecologists to protect the habitats of local wildlife, including the high number of protected reptiles prevalent on the banks of the Adur, designated a site of special scientific interest (SSSI).

There are several heritage sites in the Shoreham area, and as often flood defences are large engineered structures, the character, attractiveness and distinctiveness of the town had to be considered. Landscape architects and engineers were an integral part of our team, ensuring the SATW is in-keeping with the existing aesthetics of the area, such as using flint and brick cladding and other local building materials.

In collaboration with the client during the planning phase, we regularly met officers at Adur and Worthing Council and local residents to discuss our plans and took every opportunity to engage the community. We attended public events and held our own public exhibitions as well as meeting with smaller resident groups to address specific concerns.

Outcome

The scheme boundary covers the Adur Estuary Site of Special Scientific Interest (SSSI) and a Royal Society for the Protection of Birds (RSPB) sanctuary, and our green engineering solutions maintain the ecological value of the estuary. Although disruption of the existing saltmarsh and mudflat habitats was unavoidable, we managed to offset the impact by moving the Adur embankment away from its current location near Shoreham Airport (now known as Brighton City Airport) to create new saltmarsh environments.

We worked with archaeologists and Historic England to safeguard pillboxes forming the best-preserved WWII defence line in West Sussex, supplementing their setting where possible. The SATW works also allowed enhancements to be made to the car park and visitor facilities at Shoreham Fort, a local scheduled monument.

Shoreham-by-Sea is home to about 40 houseboats, adding to the character of the town, and it was important to balance the environmental aims of Adur and Worthing Council with access to these unique homes. Our new access route to the boats did not impact the environment and was regarded by both parties as an acceptable compromise.

Aware of the sensitivities regarding the scheme and the difficulty of effectively communicating how the infrastructure and environmental elements interact, we made our detailed engineering plans available to all interested stakeholders. These illustrated how the SATW would be constructed and the impact on the local area.

The success of the project was recognised at the 2020 Royal Institute of Chartered Surveyors (RICS) Social Impact Awards where the SATW was awarded Infrastructure Project of the Year, and at the 2019 British Construction Industry Awards where it won Climate Resilience Project of the Year.