Construction of 150kV Raasdorp-Rozenburg South
For the realization of a new 150 KV cableconnction between Raasdorp and Rozenburg Zuid, Visser&Smit Hanab (VSH) carried out a total of 44 directional drillings (HDDs) on behalf of TenneT TSO B.V. over a distance of approximately 11km. The connection is made up of 4 parallel circuits, 4 HDD’s at all 11 locations. An important point of attention within this project was the management of saline seepage water flows from deep sand layers, which in part of the rout have a higher elevations than ground level.
Our Approach
TenneT engaged BT Engineering (BTE) as an independent supervisor of the grouting work, in order to carefully manage risks related to seepage and groundwater contamination. Our role was both in technical substantive supervision as well as monitoring the quality of implementation on location.
Within this project, three different grout methods were applied:
· Refilling via filling tubes that are pulled in with casing tube
· Grout injection via the barrel during retraction
· Refilling with injection lances
Thanks to our in-depth knowledge of HDD-techniques, grout behaviors and groundwater mechanics, we could proactively advise about the risks, interfaces and measures. We also ensured an independent assessment that meets the requirements of the Rijnland Water Board.
The impact
· Risk management of seepage and pollution through early detection and monitoring of bottlenecks
· High implementation reliability thanks to independent supervision of critical grouting activities
· Effective collaboration with stakeholders, including contractors, water boards and clients
Key facts about the project
- Sector
- Cable and Pipelines
- Location
- Raasdorp-Rozenburg Zuid
- Contractor
- Tennet
- Duration
- 1,5 years (ongoing)
“Since multiple grouting methods were used in this project, in combination with different HDD’s, I found this to be an educational project. I was able to apply my knowledge and experience regarding the design and the risks during execution of the HDD’s and gain new insights into the field of seepage problems and the grouting of the boreholes. A strict planning within the company was essential for this project, so that there was always a colleague present during the execution. What made this extra challenging was the parallel execution of other similar projects, for which BT Geoconsult had to be available on-site. Due to this, effective and timely communication between myself and the other project leaders was crucial. Together with other parties, we contributed to the safe and sustainable realization of the 150 kV cable connection Raasdorp-Rozenburg Zuid. Thanks to the collaboration of all parties involved, we managed risks effectively and achieved a high-quality result.”
Why BTE?
BTE has extensive experience in management of complex HDD-project in areas with increased ground water risk. Our independence, in-depth technical knowledge and experience with clients such as TenneT and various water boards make us a reliable partner in supervision, testing and implementation. We provide timely signals, think ahead and take ownership of technical issues – so that our clients are completely unburdened.
Our committed team:
Daan Veldhuijzen van Zanten
Geotechnisch Engineer & Projectcoördinator
Niccolò Pesenti
Geotechnisch Engineer
Shayan Kalanaki
Geotechnisch & Leiding Adviseur