Sea Outfall Les Sables d'Olonne
France, Les Sables d'Olonne
Clean beach thanks to Utility Tunnelling

The French Atlantic beaches are amongst the most beautiful in Europe. In order for them to remain so, a new sewage treatment plant is being built in summer 2007 outside the gates of the coastal town of Les Sables d'Olonne, to treat the sewage from Sables and the neighbouring villages. The treated sewage is to be transported 1.5 kilometers out to sea via discharge pipes. Of these pipes, 623 meters are underground, while the remaining 950 meters are being laid along the seabed.

The work started in March 2006 using an AVN1500TB. The tunnel crew drove a reinforced concrete tube through hard gneiss and out into the Atlantic. On completion of its job on August 6, 2006, the machine was retrieved from the sea via a pontoon. Very solid, abrasive stone was a real test of strength, particularly for the cutting tools. During the course of drilling, the disc cutters had to be replaced several times. However, with direct access to the excavation chamber, the machine was ideally equipped for this.

Data Sheet

Country, Location

France, Les Sables d'Olonne






Gneiss, rock, weathered rock, loam, sand

Tunnelling length

630 m

Machine Data

1x AVN Machine:
Diameter: 1,810 mm
Lining method: Pipe jacking
Cutterhead power: 132 kW
Torque: 474 kNm

Your contact person Contact us

Steffen Dubé President and General Manager Herrenknecht Tunnelling Systems USA Inc.
Gerhard Goisser Commercial Manager Herrenknecht Tunnelling Systems USA, Inc.