SHANGANAGH S.T.W. LONG SEA OUTFALLS
This marine contract was carried out by Irishenco and Volker Stevin in joint venture and essentially involved the launching on rollers into a predredged trench of a 1.7km long, 1,200mm diameter steel sea outfall pipeline through a 60m long sheetpiled cofferdam. The cofferdam was constructed through a cliff 18m deep along the shoreline.
The pipeline was assembled in 144m long strings and a 150mm thick concrete weight coating was applied prior to launching. The pipe string was pulled over a period of nine days by a pulling barge with 250 tonnes capstan winches. The thirty two outlet diffusers were maintained in a vertical position during the pulling operation by means of inflated buoyancy bags.
The precast diffuser domes, each weighing approximately 3 tonnes, were placed from a crane barge by a team of divers.
The inter-tidal beach zone of the pipeline was given an additional concrete surround for protection, and the cliff was reinstated using a combination of concrete and large boulders as a revetment.
A storm water outfall pipeline 100m long and 1600mm diameter was also assembled and weight coated on the beach. It was then floated and towed by tugs to a pre-dredged trench where it was placed by controlled methods of sinking
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CLIENT
Dublin County Council
LOCATION
Shanganagh, Co. Dublin
VALUE
€5.07 million
PRINCIPAL ENGINEER
John Taylor & Sons, London
CONTRACT PERIOD
1983
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