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September 9th, 2022

Launch of the microtunnel-boring machine on the Austerlitz tank project

The Impluvium consortium (comprising Urbaine de Travaux (the lead company), Sade Travaux Spéciaux, Bessac, Sefi-Intrafor et Soletanche Bachy) is currently building an underground tunnel to connect the future 50,000m3 Austerlitz storage tank to the two stormwater drains located on either side of the Seine.

An exceptional tunnel project in the heart of Paris

The project involves building a 620m-long section, with a 3000mm external and 2500mm internal diameter, using the microtunnel jacking technique.

The teams from Bessac and the Impluvium consortium working on this project are keen to demonstrate their expertise and to meet the worksite’s various technical objectives:

  • Crossing underneath the Seine at a depth of over 25m, with high hydrostatic pressure;
  • 24hr-a-day tunnelling beneath line RER C, the piers of the elevated metro line 5 and metro line 10;A
  • tight curve with use of hydraulic jack control joints;
  • Excavation through multiple geological layers with various soil types (pyritic clay, coarse limestone and sand).
  • Lancement du micro tunnelier sur le chantier d'eau et assainissement à Paris
  • microtunnelier
  • descente du microtunnelier

A project focused on the environment

To prevent pollution of the Seine during periods of heavy rain and storms, this collector redirects excess wastewater from the Paris sewers to the future Austerlitz storage tank also under construction. This will therefore facilitate opening of the Seine to swimming ahead of the 2024 Olympic Games to be held in Paris. The benefits for fish biodiversity with the appearance of new fish species thanks to the improvement of water quality are also very significant.


Christening of the microtunnel-boring machine and start of the excavation

Beginning of July, the christening ceremony for the “Sequana” microtunnel-boring machine was held in the presence of the Mayor of Paris, Anne Hidalgo, and the consortium teams. 

The microtunnel-boring machine then disappeared underground to begin digging the underground gallery, with installation of the first reinforced concrete jacking pipes behind the micro-tunnelling machine.

The microtunnel-boring machine passed without a hitch under the piles of the Line 5 aerial metro and is now heading towards the Valhubert intermediate well. To allow passage under the underground lines of metro 10 and RER C, from 12/09, the digging is planned to be continued 24/7 until the arrival at the exit shaft to take into account the obligations of the SNCF.

We will be back again in october to report on the arrival and recovery of the microtunnel-boring machine in the Tournaire exit shaft. 

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