After contractor NRG’s electric drill arrived at the ‘Een Zee van Staal’ sculpture park work site this week, the first underground directional drilling towards the work site at Tata Steel will start today. Over the next two weeks, contractor NRG will make the first two (of six) boreholes to connect the wind farm Hollandse Kust (west Beta) by TenneT.

Both boreholes have a length of 1,200 metres, according to contractor NRG’s project manager Johannes Becker. “We start with a so-called pilot borehole with a diameter of 35 centimetres from one working area to the other. Then we enlarge that borehole with a ‘reamer’ to a diameter of 95 centimetres. For the third and final step, we pull a strand of four plastic casing tubes into the borehole.”

Casing tubes

Four casing tubes are drawn per hole in the four boreholes, which are made behind the dunes near Velsen towards the transformer station in Wijk aan Zee. These will eventually house the electricity cables. Of the two sea cables that come ashore via the beach, the three cores (or phases) are split at the work site in the Sculpture Park.

Becker: “Then each sea cable continues on land as three separate electricity cables and a fibre-optic connection.”

Through bike container

These casing tubes have now been welded and laid out. For this reason, our contractor NRG has already started clearing the two welding locations along Nieuwe Zeeweg and Drijverweg.

Becker: “The moment we start pulling in the casing pipes, we will place a cyclist container on the cycle path near Reyndersweg so that walkers and cyclists are not inconvenienced.”


Now that the two withdrawal pits on the raised work site on Velsen Beach have also been realised, the temporary sand castle is ready to be used for the planned drilling under the dunes. These are needed for the landfall of the sea cables that will soon be connected to the land cables underground behind the dunes.

Two times three drillings

A total of two times three underground borings of about one kilometre in length will be carried out. The first two drillings run from the beach under the dunes to the Sculpture Park. From there, the underground connection follows to the Tata Steel site. The last series of boreholes comes out at the transformer station in Wijk aan Zee.

Image source: Courtesy of TenneT

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