Project outline

Ørsted awarded Murphy the onshore cable installation contract for Hornsea Project One, which is set to be the world’s largest offshore wind farm.

Hornsea Project One, located off the Yorkshire coast, will be capable of powering well over 1 million UK homes. Spanning 407sq km, with 174 wind turbines, it will be the first offshore wind farm in the world to exceed one gigawatt in capacity.

Our scope of works included laying over 342,000m of cable along a 38km route, onshore cabling of 220kV across three circuits. This encompassed 25 joint bays per ciruit and one transition joint bay location, as well as one substation connection. The substation works included a number of 220kV circuits along with the main National Grid connection between the two substations, with 2 Nº circuits at 400kV. Along the onshore route cable was laid in trenches of 1200mm width, with three direct buried cables and one 63mm diameter duct per circuit.

Project delivery/ innovation

• Our client on the project, Ørsted, fully supported our ambition to innovate and played a key role in the success of embedding the new activities. The innovations were framed around four key project areas: cable logistics, trench excavation, cable installation and bankfilling operations.
• In cable logistics, a reach stacker, bespoke drum lifting frame and a cable drum trailer were created to avoid using a crane and to take cable drums directly to the point of installation. These innovations reduced our crane requirements by 190 days and removing around 1,000 crane lifts.
• These cost-saving and productivity-boosting innovations continued in all areas. Through the innovation and process refinement, our teams excavated 1,500m of trench, installed cable surround, directly laid three 220kV cables and reinstated the trench within four days. For trench installations, our innovative processes minimised waste and improved production from 100m per day to 600m per day – a remarkable increase. Similarly, in cable installation our new triple cable rollers helped to increase quality and reduce the number of times cable was handled by 66% - which in itself ensured no damage on installation.