Different excavation works have been performed by Scanmudring in tunnels filled with water:
- Dredging/removal of soil
- Demolition of grout blocks
- Removal of horizontal and vertical blinding layer
- Silt suction/removal
One reference is the 6,4 km expansion of the Berlin Underground which bumped into trouble when ground water started pouring in during tunnel excavation under the Minna-Cauer-Strasse. Work had to be stopped, and the project put on hold. That’s how Scanmudring ended up with our excavator in Berlin in 2017 and 2018. It’s a typical example of a task where a land based excavator can be converted to a useful subsea tool. Our operators went for training on land before project start.
The remote-controlled excavator was used to whirl the soil/grout with a drumcutter, as the tunnel was partly filled with grout that had to be milled and pumped out. Layer by layer was removed using various tools. The water in the tunnel was mixed with soil, and there was practically no visibility – a fact that made the task even more complex. To ensure safety and operational control, using sonar was essensial in this project.