VolkerInfra, in joint venture with sister companies Visser & Smit Marine Contracting and Visser & Smit Hanab, was contracted by DONG Energy to deliver the Westermost Rough Horizontal Directional Drilling Landfall Project at Tunstall, Holderness, in the East Riding of Yorkshire. The project involved the installation of a 1,015m long, 710mm diameter high density polyethylene duct for the onshore/offshore export cable connection to the Westermost Rough Wind Farm.
The first phase of the project involved completing the Horizontal Directional Drilling (HDD) 250m back from the cliff face to a dredge pit 750m offshore. A 12.2 inch pilot hole was initially drilled and sunsequesntly enlarged to 36 iches in diameter by forward reaming. Deliveries were planned well in advance, in conjunction with the local rural community and adhered to a strict traffic management plan due to the remote location of the site.
The second phase of the works involved excavating the reception pit within the intertidal zone to accommodate the cable installation plough and adhere to the client’s requirements for the cable to achieve a minimum of 2m cover to the cable.
The third phase of the works involved the pull back of the pipe duct. The 1km pipe string was floated from its storage location in the Humber to the worksite where additional buoyancy was installed into the pipe to aid pullback. The towing head was then connected to the barge and the pipe was pulled over the pipe highway ready for connection to the drill string from the HDD.
The fourth and final phase of the works was the grouting of the duct following the installation of electrical cables to reduce the potential for cable failure from over heating.