#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.

Flexible Water-Gate © cofferdams. Diagram of an installation on a river threshold | Spillway. Case # 7

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.
Positioning of a flexible cofferdam on a sill with a wide crest. Ballasting of the leading edge and sandbag under the cofferdam to reinforce the friction forces.
Ballasting the leading edge of a WA-6050 cofferdam. Doubs threshold in Dole du Jura.
Water-Gate © WA-6050 cofferdam, the end of which dies on a flat, low-slope threshold.
How to dry up a river threshold in 3 minutes! Model WL-06 with integrated ballast.