During the high-profile winter storms of 2014 high seas and strong waves caused catastrophic damage to the seawall supporting the railway in Dawlish, Devon. This resulted in the seawall being breached, undermining the track and closing the mainline to Penzance for 2 months whilst emergency repair work was undertaken.

Following on from the temporary emergency repairs to re-open the line, CAN worked alongside AMCO to construct a new 340m long raised section of sea wall to provide additional protection to the area where the wall and track were breached. The reinforcement design called for a new extended height seawall, shaped to form a wave impact return wall and forming a new raised height pedestrian walkway along the top.

The new wall was formed from precast concrete units manufactured off site and brought in by sea, then lifted into place on the old seawall foundation from a jack up barge. To fix the individual units securely in place 40mm dowel bars were required, drilled down through the old foundation and underlying beach deposits into sound bedrock and grouted in position.

Utilising drilling expertise and experience in difficult access environments, CAN deployed a team of 40 personnel working around the clock between tides to maximise productivity. Drill rigs mounted on mini excavators gained access along the existing narrow lower sea wall, lifted onto the wall from the specially commissioned barges. Long reach excavators fitted with drill masts also operated from the beach, drilling vertically into the existing wall to install the anchors to which the new precast units were anchored.

Overall 350 anchors were installed to depths of 20m with up to 16m of casing. Following installation the anchors were pre-tensioned providing a solid footing to attach the L-shaped precast units. Once the units were lifted into place and tied together, the resultant void was mass filled with concrete to complete the wall construction.

Duration:        11 months

Client:             AMCO Giffen

Location:        Dawlish, Devon