Mackley 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 as part of Team Van Oord and on behalf of the Environment Agency, the £680k, 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.
Investigations showed the existing river wall to be in a very poor condition, while the works would have to be carried out in a tricky location with restricted access.
“To overcome these constraints, the new stretch of river defense was placed in front of the existing defenses, further into the river. This had the benefit of shoring up the existing defenses and meant that piling was through new river bed ground. It also limited disturbance to the local community, thereby helping to gain planning approval,” Mackley said in their release.
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 project was completed with a backfill between the new and old defenses of self-compacting granular fill.