West Bay harbour is being rebuilt to stop it from crumbling into the sea.
Ruby Kitching reports from Dorset.
West Bay harbour in West Dorset was in a sorry state when the last century closed.
Three hundred years of battering from waves off the English Channel had taken their toll, with much of the town's protective shingle beach stripped away and its 18th century breakwater piers patched so many times that they were considered beyond repair.
Vicious storms in 1995 were the final crunch, prompting West Dorset District Council (WDDC) to take on the challenge of completely rebuilding the harbour and sea defences. The harbour is now a frenzy of construction activity, with a new pier nearing completion as the old west pier is dismantled. West Port harbour's east pier is being strengthened.
Contractor Costain and consultant Gifford are working on the £16.8M design and build contract to redevelop West Bay and enhance its sea defences.
The scheme was drawn up by WDDC with consultant Posford Haskoning.
West Bay harbour's original twin piers date back to 1740. Both had been strengthened using sheet piles, but further work was called for. With each repair job the navigation channel between the piers became fractionally smaller, finally leaving no margin for further strengthening work.
Reconstruction of the west pier will increase the width of the navigable channel, at the same time delivering increased harbour capacity. The 240m long pier is being built using a cellular construction method so it can be built in stages. Each cell is 28m wide by 29m long, and is made up of sheet piled walls driven into a clay stratum 6m below the seabed.
Divers have placed tie rods between the sheet piles to resist loads imposed by gravel infill.
Cells take 15 days to complete, says Costain project manager Phil Risbridger, but there are rarely 15 consecutive days of good weather in West Dorset.
'We've got very harsh environmental conditions here, ' confirms Gifford principal engineer Nick Clarke.
Offshore construction can only take place between April and October when there is least chance of adverse weather stopping work.
Shoreside construction has taken place over winter months.
Granite and rock armour for two new groynes and for the outer faces of each pier is being delivered to site by barge.
Rebuilding West Bay harbour began in April 2002, but by autumn the construction programme was thrown into doubt. Investigations revealed that sheet piles installed around the east pier were much shorter than originally thought.
It appeared the east pier could become unstable if it was exposed to wave forces while the west pier, which shields it from the heaviest seas, was being demolished and rebuilt.'A lot of effort had gone into the details of the west pier because it was going to be constructed first, and we just assumed that the east pier would remain standing, ' says Clarke.
The solution was to build the new west pier while strengthening the east pier and only then demolish the old west pier.
The whole scheme is designed for a 1 in 200 year storm and has a 50 year design life.
West Bay harbour is due for completion in December.