Settling dam and fine material filter (particles suspended in water)

Settling and filtration dam

The flexible Cofferdam creates a settling basin
– It can be set up regardless of the profile of the river, without anchoring
– It remains stable in the event of overflow and creates an artificial threshold that limits the flow speed and promotes settling upstream

The structure of the cofferdam allows the straw bales to be wedged between the partitions

Release holes allow filtration to be forced through the straw bales

Water-Gate© dams with release holes | WT Series

Straw: an ecological filtering agent

  • Water loaded with fine materials can suffocate wildlife and destroy habitats if released as is.
  • The opening of the release holes allows the flow to be forced through the straw bales. Straw bales promote settling and filtration of sediment.
  • The sediments trapped by the straw bale gradually migrate within it and clog the bale after more than a week compared to a few hours for geotextiles.
  • Environmental benefits: preservation of sensitive endemic species and limitation of clogging of the riverbed.
  • Recommended dimensions:
    Small boots 30cm x 40cm x 80cm or straw in mesh bags


  • Quick and reliable installation regardless of the profile of the river and even in semi-deep water (up to 150cm)
  • Allows 100% of the loaded water to be captured
  • Possibility of completely blocking the flow in the event of high turbidity / Settling mode
  • Control of the upstream level thanks to the release holes
  • In the event of overflow, the flow is distributed over the entire length. The dam functions as a weir, which limits the flow speed and promotes settling
  • Stays in place even in a flood event
  • Possibility of cascading several dams (if sufficient slope)
  • Allows to easily change the straw bales in case of clogging without compromising the effectiveness of the dam and without releasing fines

Continuous Filtration | Open position

Massive sediment input | Closed position

Absorbent Oil Booms Option

In order to trap the supernatant pollutants (hydrocarbons, oil leaks on construction machinery), it is possible to attach floating absorbent booms at the level of the ridge edge, which will accompany the variations in height of the barrier throughout the duration of the construction site.



No mobile flood protection system is totally watertight. We provide pumping solutions to collect water that has seeped through and discharge it beyond the dam: self-priming motor pumps or submersible pumps coupled with generators.

MegaSecur has developed a tailor-made spillway for lightweight discharge (DN 450). With no pump, it is environmentally friendly and features a flexible pipeline for downstream discharge. Several spillways can be positioned side-by-side if necessary.

Perfectly adapted to the complementary ballasting of the Water-Gate © barriers: 15 KG / linear meter. Robust and easy to handle (three handles), they are easy to load and unload in water: polyethylene mesh.

The Water-Gate© filtration dam combines the advantages of flexible cofferdams and natural straw. It allows the water to be decanted and filtered according to its turbidity.