Micro water supply drives for Strasbourg 24 May 2018

In Plobsheim near Strasbourg, France, a re-used 1.74m diameter AVN1200 slurry microtunnelling system has modernized the municipal drinking water system for client City of Strasbourg by installing a line from the existing water supply to a new reservoir to supply the Greater Strasbourg area.

Construction JV of Valentin and SMCE Réha completed four micro pipejacking drives using the 195 kNm maximum torque AVN1200 micro machine from Herrenknecht. In Plobsheim the sections were between 50m and 215m long with the longest section running through groundwater in a non-cohesive geology and crossing under a busy highway.

Breakthrough on target

The French JV opted for a slurry-supported AVN machine due to the water-bearing ground conditions in coarse gravel and sand, typical of the plains in the upper Rhine valley.

When crossing under the highway, pipe jacking operations had to be constant to avoid the minor heave or settlement that can occur on the surface if the TBM remains still for too long. In a two-shift operation, the drive under the highway was carried out continuously, and after less than a month the machine reached the reception shaft.

In all, 470m of tunnel was bored for the city of Strasbourg and the new reservoir was connected to the pipeline network to supply drinking water to inhabitants.

Valentin and SMCE Réha have worked closely with Herrenknecht in Europe for more than 20 years, operating multiple pipejacking machines.