Solving the Challenges of the Santoña-Laredo General Interceptor Collector
The Santoña–Laredo General Interceptor Collector is a 1.5 km subsea tunnel currently under construction in northern Spain and part of the Santoña Marshlands Sanitation Project. It is constructed with a 4.30 m Mixshield TBM, assembled in the tight space of a 12 meter diameter shaft located in an urban area, using fibre reinforced concrete segments. The tunnel excavation passes through two different and consistent geological units withstanding pressures of up to 4 bars. Firstly, a karstified limestone formation in the first section and silty sands of fluvial, lacustrine or marine depositions with pockets of muddy silt in the rest of the alignment. This paper presents the solutions to the technical challenges of the project, the development of these solutions and how they were implemented in the project.