Working with AMCO Giffen over 11 months at Dawlish, Devon
Following the 2014 storm damage at Dawlish, CAN supported the construction of a new section of seawall to help protect the railway from future coastal erosion. Working alongside the main contractor, the team delivered specialist drilling and anchoring works in a demanding tidal environment.
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, 40 mm 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.
