It’s Curtains for Silt

Bubble Tubing® is proven effective in stopping up to 90% of sediment dispersal in laboratory conditions

Working on or near water stirs up the silt from the bank or beds of watercourses like rivers, lakes or canals. Silt can be carried in the water column for some distance before being re-deposited as sediment and can cause negative environmental impacts downstream, resulting in silt pollution.

Silt is difficult to stop; there are few interventions that can stop the downstream spread of silt especially in waters deeper than 30-40cm but our recent research in collaboration with Swansea University has proven that Bubble Tubing® can provide a solution.

Introducing Bubble Tubing®

frog environmental were inspired by Bubble Tubing® which creates a wall of bubbles to see if it could provide an effective barrier to silt. Bubble Tubing® is a weighted tube that can be sunk and arranged as desired on the bed of watercourses. When filled with compressed air, bubbles emerge from micropunctures along the tube and rise to the surface, creating a wall of bubbles.

frog environmental conducted in-field trials with Natural Resources Wales (NRW) for a range of freshwater environmental protections using two lines of Bubble Tubing® to stop and control silt. Qualitative and observational evidence demonstrated the bubble curtains were effective and these are now used in many sites across South Wales.

To reinforce these findings, frog environmental entered into a research partnership with Swansea University to establish a SEACAMS2 funded project to conduct laboratory trials[1]. This looked at the effectiveness of Bubble Tubing® in preventing silt pollution.

The results are in

The project was very encouraging and results confirmed the qualitative and observational evidence.

Bubble Tubing® was used to create walls of microbubbles (a bubble curtain). Sediments of various grain-sizes were tested – 250-500 microns (medium), 125-250 microns (fine) and 63-125 microns (very fine).

It proved that a single line of Bubble Tubing alone can stop half of all silt from dispersing in the watercourse. Additional lines of tubing further reduced the silt levels traveling downstream.

Overall the study showed that 3 lines of Bubble Tubing® can trap up to 90% of silt which then settles out as sediment. This leaves only 10% of the finer sediments in suspension.

frog environmental’s Director Leela O’Dea was delighted with the results.

“These results show that Bubble Tubing® is highly effective in stopping and trapping silt. Silt and sediment management is critical for regulators like NRW who work to protect aquatic systems. It is also of concern to construction companies wanting to develop alongside watercourses.

frog environmental are experts in limiting the run-off and dispersal of sediments, helping to protect aquatic systems and limit the damaging effects of water-side developments. 

As ecological engineers we look forward to seeing how Bubble Tubing® can be used to protect more of our freshwater bodies. We now know it can be applied in seawaters too which will help mitigate silt and sound pollution from future aquatic projects all around the world.”

Bubble curtain applications

Bubble curtains can be used in the field to:

  • help manage environmental risk
  • prevent pollution from dredging operations, river crossing and realignment programmes, bank protection and flood defence works
  • protect abstractions, and
  • prevent the deposition of sediments in low flow areas such as lock entrances, marinas and temporary work sites.

frog environmental supplies bubble curtain units. Please contact us for a discussion on how these could meet your concerns.

Air Bubble Curtains are also known under several other names: Air barrier, air curtain, bubble barrier, bubble curtain, pneumatic barrier, pneumatic boom, barrier of air bubbles, curtain of air bubbles, air bubble curtains, bubble wall, bubble screen.

[1]Callaway R., Davies R., Mendzil A. (2018) Micro bubble curtains: impact on sediment dispersal. Technical Report of the SEACAMS2 project (SC2-R&D-SU03) with Frog Environmental Ltd. Swansea University. 21 pp.

 

Key Stats

  • 1 line of Bubble Tubing can impede up to 50% of sediment dispersal
  • 3 lines of Bubble Tubing can impede up to 90% of sediment dispersal

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