Watertight retaining wall in Trondheim, NO | 2025

Project Overview 

The project involved the construction of a permanent retaining wall for the new Department of Materials Science and Engineering building at the NTNU campus in Trondheim, Norway. The design, led by Ramboll, had to address classic inner-city challenges, including limited space, noise restrictions, and complex soil conditions consisting of soft clay and quick clay.

Technical Solution 

While originally designed with drilled pipes, the solution was switched to AZ 36-700N steel sheet piles (lengths 13.0–21.5 m) for better cost-efficiency and superior watertightness. Due to the weak soil, the wall was secured using rock bolts anchored into the underlying bedrock. To protect against thermal transfer and potential frost heave, the completed wall was covered in a specialized textile.

Sustainability & Innovation

The Trondheim P2 project served as one of the first major applications for Seline®, an environmentally friendly sealant developed by ArcelorMittal.

• Composition: Made from renewable balsam resin (gum rosin) harvested from pine trees.
• Safety: Certified as ecotoxicologically harmless and free from substances requiring REACH listing.
• Testing: To evaluate long-term performance, the wall utilized Seline on one half and the traditional Beltan® Plus on the other, allowing for a side-by-side comparison.

Results 

The installation was highly efficient, with a performance of 8–9 double piles per day. The end result achieved a high degree of watertightness with no substantial leakages, proving that bio-based materials can meet the rigorous demands of permanent urban infrastructure.