Session A.10: Breakwaters (III)

Chris Patterson, Jacobs UK Ltd

You have discussed fairly wholesale repairs to the faces of the breakwater and also the refurbishment of the crest. Was there any more localised undercutting of the wall due to the river and tidal flows and if so, how was this undercutting repaired?

Reply by C Grogan

The presentation mentioned that approximately 60-70% of the south face of the breakwater had been subjected to undercutting due to erosion from fluvial flows. This constituted a significant proportion of the repair works required as would be expected.

The original approach taken to repair this type of defect was to place grout bags at the face of the structure by use of divers and then grout inject into the void behind. However, early on in the contract, the Principal Contractor and Diving team raised concerns about bag placement in the river currents and offered an alternative solution, they felt could be achieved within the same budget.