24.03.2025

In Le Havre (76), using the micro-tunnel boring machine "Aline", Eiffage Génie Civil is renewing the siphon crossing of the Îlet outfall

As part of an initiative to modernise and improve the reliability of the wastewater infrastructure of Le Havre Seine Métropole, our teams are currently working on a technical operation: the renewal of the siphon crossing of the Îlet outfall in Le Havre.

A 460-metre crossing beneath the Vétillart basin, between Quai de la Gironde and Chaussée des Gares Maritimes, will replace the current 110-year-old siphon.

To carry out this operation, which combines our expertise in civil engineering, networks, foundations, and underground works, our teams are using a micro-tunnel boring machine named Aline, in tribute to the former project design manager. Measuring 461 metres in length and 4.10 metres in external diameter, Aline will complete the tunnel in 42 days.

Key figures for the ongoing works:

  • South shaft: depth 29 m, diameter 9 m
  • North shaft: depth 26 m, diameter 12 m
  • Micro-tunnel boring machine ø 1200: 2 parallel drives of 20 m each using GRP pipes ø 1200
  • 1,150 m of GRP pipeline ø 1200
  • 2,880 m³ of diaphragm wall spoil excavated
  • 5,400 m³ of microtunnelling spoil excavated
  • 15,000 m³ of earthworks completed for the two shafts and their connections

Client: Le Havre Seine Métropole
Project management: Artelia
Consortium: Eiffage Génie Civil (lead), Eiffage Infra-Bau, GROUPE MAHÉ, CAPOCCI

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