#8 | Installation on threshold – weir
How to quickly deflect a blade of water to carry out work?
Installation can be done from the bank or on a section of the threshold.
This installation is characterized by:
- a partial deviation of the stream
- a fairly low blade height
The height of the flexible cofferdam depends on the profile of the threshold, that is to say its crest width and the slope of the upstream facing.
Positioning of flexible cofferdams on the threshold
- The threshold surface is often extremely slippery. Before laying the cofferdam, gravel logs or large stones are placed on the threshold to increase the friction forces (at least 1 bag every 2m).
- If the current is really too strong, anchor points will be placed at the hinge to prevent the cofferdam from slipping.
- The leading edge of the cofferdam must in principle exceed the upstream facing of the threshold. We ballast the leading edge to prevent the current from lifting the canvas and then seeping under the cofferdam.