Long drive in rocky geology beneath a river and along the cantonal road
As part of a comprehensive infrastructure project, the client planned to replace the approximately 40-year-old GRP wastewater pipeline to the wastewater treatment plant (WWTP). The aim was to replace the existing underground pipeline with a new, more sustainable system that is significantly more robust against environmental influences and ensures higher operational reliability. The new solution provides for the installation of the wastewater pipeline in a walkable, closed channel. This ensures that, in the event of an incident, no wastewater can seep into the soil or groundwater, and the medium remains entirely within a closed system.
Project Goal
The aim of the project was the construction of a modern, closed wastewater system to replace the existing GRP pipeline. This new system was intended not only to provide increased operational reliability but also to meet the highest requirements for environmental and groundwater protection. Integrating the pipeline into a walkable channel ensures a sustainable and maintenance-friendly solution for long-term safe operation.
How we executed it
The implementation was carried out using guided pipe jacking with a launch shaft in an ascending position (gradient 6.6%) along the cantonal road to the target shaft. Shortly before the end of the project, a river was crossed. The alignment covered a section length of 862 m with horizontal radii of 250 m and 1,200 m; the vertical radius was infinite. The pipes used had an internal diameter of DN 2,000 mm and an external diameter of DA 2,500 mm. For force transmission, the hydraulic joint type JC260 was used. This not only enabled the use of maximum pipe lengths at the maximum permissible jacking force but also reduced the required number of intermediate jacking stations. Lower bedding forces also had a positive effect on friction behavior. A central element was the MSS monitoring system, which made it possible to precisely locate friction points along the route. This allowed the jacking force to be efficiently reduced through targeted lubrication.
Results
The project was successfully completed. The new closed and walkable wastewater pipeline meets all requirements for environmental protection and technical safety. The river was crossed without interference with the watercourse, and the tunneling work was carried out precisely and efficiently. By using the JC260 joint and the MSS monitoring system, maximum tunneling performance was achieved and friction forces minimized. A total of 214 pipe connections were injected with the JCGrout system to permanently seal the joints and significantly extend the service life of the facility. The result is a future-proof pipeline system with high operational and environmental safety.
