A joint submission, showcasing two projects to improve sea defences on the south coast of Kent, was recently named a finalist in the International Excellence category of the Flood & Coast Excellence Awards 2021.
The Hythe Ranges Sea Defences project and the Lydd Ranges Emergency Works were carried out by Van Oord, supported by their subsidiary partner Mackley and on behalf of the Environment Agency.
Storms in winter 2019/20 severely depleted the coastline in front of the Ministry of Defence (MoD) firing ranges at Lydd, and immediate emergency works were required to stabilize them. A major capital scheme to improve the protection from coastal flooding at Lydd was planned for 2021/22.
At the same time, a £25 million scheme to refurbish the beaches at Hythe, located some 25km away and with similar characteristics and environmental requirements, was also about to get underway.
The Environment Agency and Van Oord came together to solve the challenges posed by the requirement for immediate intervention at Lydd, limited access due to the MoD using the firing range, and how to meet the very difficult and tight specification for beach material that complied with the strict, legally protected requirements for the internationally designated nature conservation site.
A specialist dredging team was employed from the Netherlands, who developed new world class technical excellence in screening capability to provide a very low level of fines in the dredged shingle nourishment material. The complex specification is required to ensure that the coastal processes that underpin the nature conservation site are maintained.
The joint submission aimed to recognise the exceptional team working to the benefit of all, including the Environment Agency, the MoD (main landowner beneficiary of both schemes) and the wider community.
Following a rigorous judging process, the submission was selected as a finalist in the International Excellence category of the Flood & Coast Excellence Awards 2021. These prestigious awards recognise the important work that has contributed to managing flood and coastal risk, building local flood resilience and taking action on climate change.
More about the schemes
Lydd Emergency Works
Storms Ciara and Dennis in January 2020 caused significant damage to 1km of coastal defences at Jury’s Gap in Kent, to the extent where a “moderate” storm could cause catastrophic flooding.
Following prompt incident response from the Environment Agency’s Operations and Asset Performance Teams, a project was established to bring the defences up to the pre-storm condition by October 2020.
A budget of £11 million was allocated to build two emergency groynes, place rock on the foreshore, and recharge the beach with graded shingle until a capital scheme could be developed for 2021/22.
The emergency works at Lydd were designed to form part of the planned capital scheme, which is now underway.
Hythe Ranges Sea Defences
Hythe Ranges are critical infrastructure for firearms training and national security by the MoD. Next to the firing range is the Dymchurch Grand Redoubt (a scheduled ancient monument) and a mixture of residential, habitat and other land uses, which contribute to the local economy. Half of the beach is also a Special Protected Area (SPA) site for wading birds.
Prior to the scheme the Hythe defences comprised a seawall at the Redoubt, an embankment, timber groyne field, shingle beach and rock armour, which were given the overall condition grade of “poor; defects that would significantly reduce performance of asset”.
The concrete sea wall and revetment at the Redoubt were frequently damaged by storms. Failure risked rapid erosion and breach of the defences, resulting in flooding of the low-lying hinterland, where many homes and businesses were also located.
The Environment Agency worked in partnership with Defra, local authorities and MoD to develop the scheme and secure funding. 25% of costs were obtained through partnership funding from the MoD, the main landowner and immediate beneficiary.
The concept was to reduce erosion and breach risk due to wave overtopping by designing a combination of “hard” defences (groynes/revetment) and “soft” defence (beach nourishment) to slow down the long-term loss of sediment.
This combined approach has less adverse impact on the natural processes and movement of material down drift, as unlike a hard defence the beach gradually dissipates wave energy rather than reflecting it back.
A new groyne field and rock revetment were required to complete the works at a cost of £25 million.
04 August 2021