Santoña - Laredo Subfluvial Water Tunnel, Spain

Project Name:   Santoña – Laredo Subfluvial Water Tunnel, Spain

Location: Northern Spain

Application: Precast Segmental Tunnel Lining

In order to protect significant ecological marshlands from urban sprawl a new wastewater pipeline is being constructed in northern Spain. The objective of the project is to collect and transport wastewater from multiple municipalities to existing treatment facilities for environmentally friendly processing and disposal.

Incorporated in the infrastructure project is a 1.5 km, 4.3 m diameter TBM driven tunnel.
The 1.5 km long segmentally lined tunnel is driven by a 4.3 m diameter TBM. The EPB machine used for construction has a maximum thrust of 16,725 kN. The universal rings have a 5 + 1 segmentation and a length of 1.2 m Internal diameter of the lining is 3.5 m with a thickness of 250 mm.
Additional to macro synthetic fibre, 16 kg/m3 of steel bar, as additional bursting reinforcement, is placed at the jacking face and the radial joints of the segments. The steam cured segments have a characteristic compressive strength of 45 MPa.


  • Eliminated the risk of corrosion
  • Removed more than 80% of the steel reinforcement
  • Reduced total segment production time by 50%
  • Reduced overall lining cost by approximately 40%

Author:  Geoff Sedgman:

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