Gifford is acting as the contractor's desiger for the project.

Over the centuries - a harbour at West Bay was first mentioned in documents in the 1390s - storm-driven southwesterly rollers have repeatedly smashed the piers at West Bay and created flooding in the village. The problem is exacerbated when storm 'run-off' increases the flow in the River Brit, which runs into the harbour.

Even when such drastic events don't occur, southwesterly or southerly winds frequently send 4m high waves up through the entrance channel, effectively rendering the port unusable for around 160 days per annum. As Phil Risbridger, Costain's project manager explained, when a southwesterly is blowing, there is nothing between West Bay harbour and Venezuela, and waves enjoy a 6,500km run-up before they hit the old harbour.

It is as part of a flood defence project that Costain's major reconstruction of the harbour is taking place. The Department for the Environment, Food and Rural Affairs is funding almost half of the £16.5 million target cost of the project under its flood defence, coastal protection and fishing harbour budgets, with the Environment Agency providing a further 13 per cent and West Dorset District Council the remainder.

The contract includes construction of a new, 230m West Arm, or pier, that angles out from the beach immediately west of the current harbour, which will shield the harbour entrance from the prevailing winds. It will be heavily protected by rock armour.

The existing, Grade II listed East Pier is being renovated and strengthened, whilst the existing West Pier will be demolished.

The effect will be to create a new outer harbour and a safer port usable all year. In addition, some 25,000 tonnes of shingle has been used to replenish the village's West Beach immediately to the west of the harbour, preventing it being over-topped in storms. This beach is, in turn, protected by a new rock groyne further to the west, while new rock armour toe protection has been installed to protect the existing West Cliff sea wall.

'The local council took the design quite a long way down the road before we got involved, ' Risbridger explained. 'An awful lot of physical testing was done to determine it.'

To provide protection from storms, the project requires around 120,000 tonnes of rock armour. Although Portland stone is quarried nearby, it lacks the necessary density and durability for the 50 year design life of the project, so granite is therefore being shipped across the Channel from St Malo.

The vessel doing the runs anchors around a mile offshore and transfers its 1,800-tonne loads to smaller, shallow-draft vessels that can get right into the beach and deposit their loads precisely where required.

The most obvious part of the project is the new West Arm, which is built to a tried-and-tested design, consisting of 15 cells of conventional design - two lines of sheet piles tied together top and bottom, filled in and topped with concrete. A cell can be created in around 15 days. The East Pier, meanwhile, is being repaired and refurbished, with a new, outer layer of sheet piling for protection, and with the new West Arm in place, work is now underway to demolish the old West Pier, which will be reduced to a stub with a roundhead tip.

A new slipway in the new outer harbour will replace the old, tide-dependent slip, with material from the demolished West Pier being used in its construction.