The London Array wind farm was constructed between 2010 and 2012 as part of the contract with London Array Limited, involving the installation of four export cables by VBMS.
The London Array wind farm is located approximately 20 km (12 miles) from the Kent and Essex coasts in the outer Thames Estuary. The wind farm consists of 175 turbines with a capacity of 630MW. The site is situated on and between two sandbanks, Long Sand and Kentish Knock, in water of up to 23 metres deep. It is bounded to the west by Black Deep, the main approach to the Port of London, and to the south by the approaches to Fisherman's Gat.
The power generated is exported from the offshore substations via four 150 kV cables (two per offshore substation) to a landfall point at Cleve Hill, Graveney, England. Once the marine cables reach the shore they pass under a sea defence and borrow pit using HDD conduits. The export cables cross the Kentish Flat and BritNed cables and the Princes Channel.
The cables were laid and buried by the Stemat Spirit using a plough. Among the challenges the project faced were the pull-in and installation operations in a shallow tidal section of the cable route, the crossings, and the installation into the wind farm. Over the first half of the route, "safe havens" were allocated to allow the Stemat Spirit to halt operations in the case of deteriorating weather conditions.
The scope of work relating to the export cable was as follows:
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