The latest tunnelling project under and around the River Seine, contributing towards making it swimmable again, is now complete.
Linking up to a major water collector and tunnelling 17 metres underground, phase one of the project consisted of a 981-metre-long AVN2500 microtunnel along the riverbank in Vigneux-sur-Seine. The now completed second phase, running an additional 1280 metres, passes under the Seine and follows the course of the river, before exiting in urban Athis-Mons.
Contrary to phase one, the vast majority of the phase two tunnel was installed using segment lining, given the length and curvature of the tunnel path.
Working alongside RAZEL-BEC, SADE and BESSAC, OPTIMUM accompanied the works contractors prior to and throughout both phases of the tunnelling operations. Faced with complex and heterogeneous geology (clayey marl, siliceous limestone), close monitoring of the tunnelling parameters, drilling fluids, cutting face pressure and tunnel frictions was essential to ensure appropriate tooling / fluid adaptations were made. OPTIMUM also carried out extensive impact modelling given the close proximity of existing pipeline networks. The reactivity of OPTIMUM’s specialist trenchless engineers in providing this analysis allowed profile modification decisions to be taken quickly, thus keeping downtime to a minimum.
Congratulations to the entire project team for their dedication in completing this ambitious project.
- Project owner : SIAAP, the greater Paris Sanitation Authority
- Construction contractors :RAZEL-BEC, SADE, BESSAC
