Team Van Oord has completed a project to fill a 28-meter gap in the flood defenses in the West Sussex town of Littlehampton – in turn reducing the flood risk for 2,000 homes.
Working on behalf of the Environment Agency, the 20-week project included organizing the planning application and producing the detailed design, followed by installation of a sheet piled wall and concrete capping beam alongside the River Adur.
The installation of the sheet piles took place from a jack-up barge, supporting a 70t crawler crane. The barge arrived in a good weather window, having been transported from Tilbury. The barge was then towed into the harbor and loaded with equipment – before being towed along the river, floated through a pedestrian bridge and moved into position at the work site.
The 18m piles were selected to complement the existing adjacent piles and to provide a 50-year life span. Pile stability was enhanced by increasing the section size, rather than length – which would have meant driving into a band of hard material, with the risk of vibration damage to an adjacent 130 year old cob stone building.
“Our combination of construction and design expertise enabled us to produce a design which overcame complex ground conditions – including buried timber and a perched water table – while maintaining flood defense levels at all times,” Barry Holt, Team Van Oord Project Manager said. “Throughout the project, we worked with the harbor master and local businesses to ensure the river road remained open at all times to minimize disruption for local residents.”
The project was completed with a backfill between the new and old defenses of self-compacting granular fill. This filled the main voids and stabilized the ground immediately behind the new wall. The last gap in the wall was closed by installing new flood glass.