Hard Engineering Case Study West Bay, Dorset Hard Engineering Case Study

West Bay, Bridport West Bay is located 2 miles south of Bridport, West Dorset. Midsized town with a population of around 13,000 people. The river Brit enters the sea through the Bay. The Bay itself is surrounded by an Area of Outstanding Natural Beauty, and the cliffs on either side of West Bay are Sites of Special Scientific Interest as are the meadows just behind the harbour. Bridport has a caravan holiday park, several small hotels and pubs, a few shops and other businesses. There are two main residential areas of houses and bungalows, behind the West Cliff and along West Bay Road, as well as a few blocks of flats, old people’s homes and old fishermen’s cottages. The heart of the town is a conservation area. It is an area which has been targeted for regeneration and improvement schemes to enhance its character. Tourism is a major source of income.

Problems The coast of West Dorset is a great example of an exposed and rapidly eroding coastline. Cliff failure and recession at West Bay are due to mass movement, such as slipping, slumping (in the clays) and rock falls (of sandstone) caused by both coastal and non-marine weathering and erosion processes. It presents a huge challenge to the authorities to protect West Bay from flooding and coastal erosion. The town’s response to this was to construct the West Bay Coastal Defence and Harbour Improvements Scheme, which started in 2002 and was completed by September 2004 at a cost of around £18 million. This choice was made above such things as a ‘managed retreat’ due to the value of property and tourism of the area.

East Cliff and Beach East Cliff Nearly vertical and made out sandstone East Cliff and Beach East Cliff Nearly vertical and made out sandstone. Under the effects of sea erosion processes such as wave pounding, hydraulic action, abrasion and attrition. The base of the East Cliff is naturally protected by its deep shingle beach, and the man-made shingle ridge, built up by the Environment Agency for flood prevention in 1982. East Beach East Beach - the beach is regarded as the western end of Chesil beach and is designated as a Site of Special Scientific Interest. It consists of orangey shingle with some underlying sand and pebbles.

West Cliff Almost entirely composed of soft middle Jurassic rocks West Cliff Almost entirely composed of soft middle Jurassic rocks. There has been a record of intermittent slipping, probably due to the flow of ground water within the fault zone in the Frome clay. This has lead to a series of attempts to stabilise the cliff over the years. It is protected primarily by a large sea wall.

Development   Main features of the development project: Old west pier replaced by a new 230m pier with rock armour on the seaward face. Construction of a slipway area and 10m wide slipway, using material from the old demolished pier. Construction of a timber walkway with rock armour. Strengthening of the existing east pier, with a new rock armour extension. Construction of rock armour on the west beach, to protect the existing sea wall in front of the west cliff. Construction of a rock armour groyne. Beach replenishment to west beach.

Rock armour (primary and secondary) 98,500 Fill material to rock structures 1,500 Fill material to structures 20,000 Aggregate for use in precast concrete products 160 Beach replenishment in materials 28,000 Aggregate for use in ready mixed concrete 250 Surfacing materials 250 Masonry 30 Steel sheet piling 3,000 _______ Total 151,690 tonnes

West Bay in 2008 post-development, looking north west West Bay in 2002 pre-development, looking north west

Economics Development cost around £18 million in total. Allowed new real estate development, such as the new ‘ellipse’ apartment development complex. Average price of around £350,000. Created a higher level of tourism, meaning more revenue for local stores and services. Provided a more effective area for the local fishing industry. Social The rock armour can be an eye soar, however fits in the new modern look of the bay (ellipse etc). Physical  New rock armour groynes and pier have helped to cut out high levels of LSD. Rock armour at the base of the west cliffs has helped to reduce the chance of undercutting in storm surges, by absorbing the kinetic energy of the waves.

‘Ellipse’ building development