Update | E-Power Pipe in Oirschot
Last week we pulled back the final 2000-meter bundle of cables using the E-Power Pipe paving-bore method. With that, this project comes to an end for Denys and Kouwenberg Infra. It was a beautiful, challenging, educational, and above all successful journey, which we here recap in full below.
On October 7, 2020, Kouwenberg Infra and Denys joined forces to realize the first E-Power Pipe (EPP) project in the Netherlands. Not only was this a unique venture, but there had not yet been any deeper bore than 670 meters with this new system developed by Herrenknecht. For TenneT and NRG, however, we gladly accepted the challenge to realize a 550 mm bore of no less than 2000 meters using the EPP system! A project component of the realization of a 150 kV underground cable connection between the distribution stations in Tilburg Noord and Best.
Not only would the boring be our part, but pulling in the 431 mm diameter cable bundle over the same length would also be part of the works. In short, enough challenges to sink our teeth into.
The preliminary investigations had already been carried out by TenneT, but there was still plenty for us to prepare in order to ultimately realize a successful boring. For example, we wanted to ensure with all parties that the system would be capable of pumping 2000 meters of drill spoil. Therefore, a full-scale successful test was already conducted by Herrenknecht in (month/year), and the devised theory was proven plausible.
At the same time, the subsoil in which the bore would take place was examined to identify the most ideal stratum to bore into. In collaboration with Prysmiangroup, the minimum required cover was determined, with the requirement that the heat from the cables could be adequately dissipated into the surrounding ground. It was concluded that the cables had to be installed with a minimum ground cover of 2 meters. With that starting point, we continued the design process, the next step being to investigate the presence of tree roots; after all, the boring would take place in the middle of the Oirschotse Heide forest near Oirschot. Experts assessed whether there was a risk of hitting tree roots with the bore. Not pleasant for the machine and certainly not for the trees involved.
Now it was time to make the jigs. A compression jig made of sheet pile and a receiving jig using trench formwork. From the compression jig, all four bore lines could be drilled. The first up were the two 400-meter bores. The boring teams from Kouwenberg and Denys worked together very closely with the boring specialists from Herrenknecht. It was decided to bore in a continuous process. The first two bores were successfully completed within the specified parameters. Knowledge of the new-to-most of us machine had been gained, and the teams were in sync. A number of improvements were also made to the drilling process; time for the real work!
The challenge now was not only to bore 2000 meters with 2 meters of ground cover, but also to bore with a horizontal and vertical bow radius. From prior experience we knew it should work, but that was only theory. Fortunately, theory and practice went hand in hand here, and both bores were carried out in accordance with the specified requirements.
Thus a new trenchless technique was successfully implemented to lay pipelines at minimal disturbance to the surroundings and at shallow depths, while still keeping the pipelines accessible. A solid solution for the many kilometers of cable that still need to be installed in the context of the energy transition. Someone even spoke of a next challenge of 5000 meters. We are ready for it!
