Walney 1 - Cable Landfall

In 2010, DONG Walney (UK) Limited, a wholly owned subsidiary of DONG Energy A/S, was responsible for fabricating and constructing the Walney offshore wind farm, which has a capacity of approximately 183 MW. The wind farm is located in the Eastern Irish Sea, approx. 15 km west of Walney Island, Cumbria, UK.

Facts and figures

Export Cable
Landfall: 1300 m with 45° bend and cable crossing
Equipment
2x 40-ton winches, 200 special 1.5-ton cable rollers
Project categories

Phase 1 of the Walney Offshore Wind Farm involved the construction of 51 wind turbines - each with a capacity of 3.6 MW - and 1 offshore substation. The turbines are interconnected to an offshore substation by approx. 6.3 km of 33 kV inter-array cable systems. The offshore transformer platform (substation) is situated at the centre of the wind farm and will be connected to the 400/132 kV Heysham grid substation onshore. Approx. 45 km of 132 kV submarine armoured cable and 2.7 km of underground cable was required to connect these two substations.

VBMS was responsible for handling the work in the intertidal area of the southern side of the port of Heysham and also looked after the coordination and cable pull ashore.

The scope of work comprised the following:

 

  • Engineering of the landfall;
  • Coordination between offshore and onshore;
  • Preparation of the site and construction of site office compound;
  • Mobilisation of land-based equipment;
  • Pull-back of the plough towards the pre-installed duct;
  • Positioning of cable rollers on the beach;
  • Pull-in of  HV cable from Stemat Spirit into the joint bay;
  • Burial of HV cable between duct and grade-in of the plough to the required depth;
  • Demobilisation of equipment.

 

Complicating factors on the project included the long flat beach area with a tidal range of around 8 metres and the crossing of the Barrow export cable, which was already in use. The Barrow export cable is supported by a concrete tunnel installed underneath the cable, in which a PE duct of 560 metres is installed to the shore. Another challenge was the cable route, with an almost 90˚ curve in the intertidal area. 

The two VBMS-owned 40-ton pulling winches were used to pull in the HV cable to shore. Prior to the cable pulling, the VBMS-owned plough was pulled towards the end of the PE duct. During the cable pull, the friction of the cable was reduced using our specially designed heavy-duty cable rollers.

 

Although the schedule was tight, VBMS was able to pull the cable with a minimum of delays to the cable-laying vessel, Stemat Spirit.

 

Thanks to close co-operation between the inter-company parties (VBMS and VolkerInfra), the near-shore cable work has been completed to the satisfaction of all stakeholders.

Project location

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