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Sea Outfall Les Sables d...
Requirement
tunnelling project
 |
Employment | Sewage |
|---|---|---|
| Geology | Gneiss, rock, weathered rock, loam and sand | |
| Tunnel Length | 630 m | |
| Diameter | 1,810 mm |
Solution
machine data
| Machine Type | AVN | |
|---|---|---|
| Support Techniques | Pipe Jacking | |
| Cutterhead Power | 132 kW | |
| Torque | 474 kNm |
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 1½ kilometers out to sea via discharge pipes. Of these pipes, 623 meters are subterranean, 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 6th August 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 cutter rolls had to be replaced several times. However, with direct, walk-in access to the excavation chamber, the machine was ideally equipped for this.
