Combining expertise and capacity
- Client TenneT
- Location Groningen and Zeeland
- Status In Progress
More capacity for the transport of (sustainable) energy
TenneT is significantly expanding the capacity of the Dutch electricity grid with new 380kV high voltage connections in the provinces of Groningen and Zeeland. Strukton Civiel and Mobilis, together with their foundation partners, were awarded the contract for the enormous foundation structures on two of the sub-routes. Dealing with the strict planning schedule, vulnerable soil and committed plot owners all require a professional approach in a number of different areas.
The consortium was awarded the routes between Willem-Annapolder and Rilland in Zeeland and between Eemshaven and Bedum in Groningen, mainly thanks to its planning control and environmental management skills. After all, it is vitally important for TenneT to achieve the planned end date and maintain a good relationship with the surrounding area.
Jeroen Toet, Project Manager: ‘Together with TenneT, we’re treating the residents and their area with the respect they deserve.'
The great strength of the Strukton Civiel/Mobilis partnership with Terracon/Voorbij Funderingstechniek is the combined expertise and the capacity of the partners. In Groningen, the consortium is fortified by Koninklijke Oosterhof Holman. This is because the foundations there are enormous. Under each new Wintrack mast, there are two concrete foundations with a diameter of 8 to 16 metres and a sturdy anchor cage to absorb the forces on the mast. Each base is supported by 20 to 40 concrete foundation piles.
Vibro piles and Fundex bored piles were prescribed for the project, but the vulnerable soils in Groningen and Zeeland mean that adjustments sometimes need to be made. The consortium is reacting to this flexibly by using extra – and sometimes different – machines and drilling machines. There is a full-time planner keeping track of progress so that the necessary adjustments can be made straight away. This avoids any disruption to the tight schedule. Strukton Civiel and Mobilis are coordinating the installation of the masts and high voltage lines by secondary contractors and are responsible for the agricultural restoration of the soil.
Thanks to the consortium’s combined knowledge and capacity, the technical implementation is a routine task for them. However, the work in the field is a real challenge. Almost every foundation pair is located on the property of different owners, who are mainly farmers. Together with TenneT, the Strukton/Mobilis Area Manager will sit around the kitchen table with them all to discuss the work to be done on their land. Needless to say, the consortium has regional people on the team who are aware of all the local sensitivities and who speak the same language as the property owners. That is helping to create a feeling of trust.
As in every project of this scale, there are risks involved. In Groningen, there are is a risk of vibration and in Zeeland, there is a risk of salinisation. During the tender phase, local expertise was deployed for the drainage plans to make sure that the groundwater level always remains inside the margins. Agricultural specialists and ecologists from the region have been advising the consortium about the natural surroundings and about how to restore the land so that it can be used for the agricultural purpose for which it was intended.
‘We use technology under high voltage remaining flexible, proactive and environmentally aware.’
A project start-up was organised so that all the participants could get to know each other on a personal level. The connections made in this way are now bearing fruit. The client and the contractor are working together in an atmosphere of mutual trust and aiming for a common goal. This is one of the success factors of both projects.
Common goal: extra transport capacity
The consortium realises that TenneT is under pressure to put the new high voltage connection into operation as soon as possible. The extra transport capacity is urgently needed.
The new 380kV connection in Groningen will provide a greater transmission capacity from the large-scale generation location (Energyport) in Eemshaven to Groningen, the rest of the Netherlands and the international high voltage grid.
In Zeeland, there is more supply than demand for energy due to the many solar panel and wind farm initiatives. As a result, structural congestion is expected on the local (150 kV) electricity lines as well as the major (380 kV) electricity superhighway. The new 380kV connection between Borssele and Rilland will provide more capacity on the 380kV grid so that the surplus of electricity can be used properly.
TenneT is building a new 380kV high voltage line in Groningen between Eemshaven and Vierverlaten (west of the city of Groningen). A total of 40 kilometres of high voltage line with 121 Wintrack pylons are being built. The Strukton Civiel/Mobilis consortium is responsible for plot 2, which is located between Eemshaven and Bedum. This route is approximately 22 kilometres long, with 69 locations and 138 foundations. Partner Koninklijke Oosterhof Holman is helping the consortium with local knowledge during implementation.
Implementation started in April 2020 and the foundations will be ready by the end of 2021. The plot will be handed over at the end of 2022 after the pylons and high voltage lines have been installed by the secondary contractors and the soil has been restored for agricultural use.
The old 220kV line will be dismantled and the 100kV line between Vierverlaten and Brillerij, which TenneT will merge with the new high voltage line, will become redundant. As a result, 163 lattice masts are due to be demolished.
In Zeeland, TenneT is building a new 380kV high voltage line between Borssele and Rilland. The Strukton Civiel/Mobilis consortium is responsible for plot 2, which is located between Willem-Annapolder and Rilland. This route is approximately 24 kilometres long, with 52 locations and 104 foundations. The total line is 48 kilometres long.
Implementation started in November 2020 and the foundations will be ready by late 2021/early 2022. The plot will be completed in early 2023 after the installation of the pylons and high voltage lines by secondary contractors and the agricultural restoration of the grounds.
TenneT will combine the existing lines in the Zak van Zuid-Beveland and between Willem-Annapolder and Rilland with the new high voltage line, making 42 kilometres of the existing line redundant. As a result, 131 lattice masts will disappear from the Zeeland landscape.