Strengthening coastal defences with asphalt revetments

Overview
Canvey Island is one of the most flood-exposed communities in the UK, with most of the island lying below sea level. The defences, first constructed in the 1930s, were increasingly vulnerable to overtopping and erosion, threatening thousands of residential properties. The Environment Agency launched a £20m programme with Jacobs and Balfour Beatty to extend the life of the existing revetment and secure protection for decades ahead.

Challenge
The existing coastal infrastructure was more than 80 years old, deteriorating under constant wave attack, and no longer met modern flood defence standards. Failure could put over 15,000 residential properties at risk, with 6,000 of these directly exposed. The solution had to be engineered to minimise disruption, extend the life of the structure, and meet today’s resilience and sustainability expectations.

Solution
Hesselberg Hydro’s approach centred on cleaning and exposing the existing revetment, filling voids, and re-profiling with Lean Sand Asphalt (LSA). A new toe was excavated into the foreshore, with asphalt delivered directly to the crest and placed using long-reach excavators, including a 110T unit with a 30m reach. The crest was reinstated and regraded to restore protection. Strategic layering of Open Stone Asphalt (OSA) and LSA provided both structural resilience and hydraulic performance. All works were supported by site-based quality control and coordination with EA and Jacobs’ design team.

Result
The Canvey project, due for completion in 2025, is delivering a long-term upgrade to the island’s sea defences while minimising carbon impact. By combining OSA and LSA, the revetment has been engineered to withstand ongoing tidal pressure, reducing future maintenance needs and safeguarding thousands of homes. Mid-project performance has already shown the effectiveness of asphalt systems in delivering resilience quickly and reliably at scale.