The trencher will be used for the connection of the Hollandse Kust Zuid (HKZ) offshore wind farm, to be built 22 km off the coast of the province of Zuid-Holland.
In 2018, TenneT awarded the Van Oord-Hellenic Cables consortium the contract to build the connection between the two offshore platforms (HKZ Alpha and Beta) with the Maasvlakte high voltage substation and the Randstad 380 kV South ring. For the first 10 km of the offshore route the cables will have to be buried more than 5 metres in order to be able to cross the busy Rotterdam Maasmond shipping lane.
Deep Dig-It Trencher
The Deep Dig-It Trencher is designed and built by Van Oord and can bury cables more than 5 metres below the seabed, a requirement that will be seen more and more in offshore wind. The trencher is remotely controlled (also called Tracked Remotely Operated Vehicle). It creates a deep trench for the cables, while simultaneously inserting the cables and then closing the trench again.
The trencher weighs 125.000 kilos, is more than 17 metres long, over 8 metres high, and 11 metres wide. Van Oord reports that it is the largest and most powerful machine in its class. The installed power matches the equivalent of two Leopard tanks (2,500 HP), making it possible to bury cables into very hard soils.
The consortium is expected to start the actual installation of the sea cables in July. The Deep Dig-It will be controlled from Van Oord’s offshore installation vessel MPI Adventure, which is equipped with a crane that launches and recovers the Deep Dig-It into the sea. HKZ Alpha (700MW) will be ready in 2021 and Beta (700MW) in 2022.