Dales Voe South is the strongest quay in the UK at 60 tonnes per square metre; and the deepest of its type in Scotland. It was the first of a series of planned developments to service the decommissioning industry in Shetland to compete with overseas facilities.
The project was conceived to provide a multi-purpose deep water facility to meet the needs of the offshore industries, including renewables and decommissioning. The investment by our client, Lerwick Port Authority, in this project has secured Shetland's position at the forefront of decommissioning works in the North Sea.
The project comprised the extension of the quay by 75 metres, provision of deck load-bearing capacity of 60 tonnes per square metre and a link span line load of 800 Tonne/m run of quay to enable a floating barge skid transfer of complete offshore topside modules up to 24,000 Tonne, with a minimum alongside 12.5 berth depth.
The new quayside was formed with 55,000m3 of reclamation using site-won aggregate, retained behind a tied combi-pile wall constructed with 42 1575mm diameter 24mm wall thickness, maximum 21m long tubular piles with intermediate double AZ26 sheet piles. The front face of the combi wall was restrained with 18 125mm tie-bars to a 425m3 reinforced concrete anchor beam, secured by 38 multi-strand tension anchors up to 2250kN capacity, and 114 No six metre long shear dowel bars.
The North and South combi walls were restrained by a further 19 tie-bars connected to a reinforced concrete transfer beam. Quay capacity and support of the cope on the leading edge is enhanced by 24 1575mm diameter tubular bearing piles. These bearing piles created a double pile front face to the jetty extension. Two return sheet pile walls were built, each approximately 12m long, comprising of AZ50 sheet piles 12m in length. Ancillary works included power, lighting, fuel and drainage.
The Principal Contractor was BAM Nuttall Ltd. The project was shortlisted for the Saltire Engineering Awards 2017.