For the expansion of the HV network between nearby Schiphol Airport, casing pipes are being installed to pull through 150 kV cables by our colleagues from Volker Energy Solutions. The length of the route is almost 12 km and most of the casing pipes are laid by means of horizontal directional drilling. The project contains 48 drillings spread over 17 different locations. Multiple boreholes are made at all locations. Four casing pipes with a diameter of 200 mm will be installed in each drilling. The first drillings started in mid-October 2022 and the last drilling is planned just before the summer holidays.
This is a special project for the Drilling Department in several aspects. For example, the longest drilling of the project is realized by our 450t drilling rig. You will not find a larger drilling rig in Europe that has little trouble with the bundle for this project with a total circumference of 70 cm.
In addition to the 450t drilling machine, the 60t rig, the 27t rig and the 17t rig are also working on the project. All drillings can be made with our own rigs. In this way we can show the customer a nice, constant level of quality that we are proud of.
The tension water in the subsurface is taken into account in almost all drilling activities within the project. Tension water is groundwater that is under pressure at a depth of about 12 m under a sealing clay layer. If the drill pierces this clay layer, it creates a leak in the sealing layer that allows the water to flow to the surface. This should of course be avoided. In collaboration with Deltares and Het Hoogheemraadschap Rijnland (licensing authority), a new method has been developed to restore the sealing clay layer during and after our drilling activities.
The casing pipes that we install are also special pipes. These are resistant to a high temperature. Due to the heavy load on the power grid, the temperature of the power cables is expected to be extremely high for a longer period of time. Because the temperature influences the residual life of the casing pipe, the client opted for a casing pipe that can withstand a high temperature, so that the power cable can still be replaced after a longer period of time. This project is an exciting and technically challenging project that suits V&SH like a glove.