Weir, Mont Saint Michel, France



The old weir at the river Couesnon is replaced by a new special weir, in order to avoid the sand silting of the bay. The principle is simple: at the ebb-tide the weir is opened, the dammed up water shoots into the bay and flushes the alluvial deposits with it.


Société mixte Baie du Mont-Saint-Michel


Construction period:    
2006 - 2012


Main contractor:
QUILLE (Bouygues)


Supplier/sub contractor:


Scope of supply:
54 pcs. thread bars SAS 835/1035 Ø 75 mm, l = 4,15 m,
54 pcs. thread bars SAS 835/1035 Ø 75 mm, l = 4,48 m,
with accessories


During flood-tide the weir is closed and the river Couesnon is dammed up. The pressure force of the dammed up water is held by the new special weir. Therefore the watergates of the weir are pre-stressed to the              concrete pylons with two groups of ground anchors of SAS 835/1035 Ø 75 mm tendons. The SAS thread bars are pre-stressed to a working load of 2,250 kN.