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Are silt curtains effective?
Published on 30 Sep ‘24
Are Silt Curtains Effective? A Look at Their Role in Sediment Control
Silt curtain effectiveness

When properly specified, installed and maintained, silt curtains are highly effective. They are one of the best solutions for controlling dispersed suspended sediments in marine environments. However, their effectiveness depends on the right design, the right product and the right implementation.

The image below highlights a successful silt curtain deployment. In this case, dredging operations required the use of settlement ponds for dredged slurry, with silt curtains serving as the final line of defense. This project is a good example of how a correctly specified and installed marine protection barrier can make a significant environmental impact.

THE IMPORTANCE OF CORRECT SPECIFICATION AND INSTALLATION

Ecobarrier Silt Curtains

In this project, a double-layer silt curtain system (as indicated by the arrow in the picture) acts as a critical barrier between the outflow from the settlement ponds and the open ocean. At the time of capture, the outflow contained highly turbid water, flowing from the settlement area into an enclosed section where the silt curtains serve as the final line of defense.

This double-layer system was originally installed in mid-2017 as a secondary precaution. It became the primary protective measure after the failure of two previous installations — one in the settlement area and one in the ocean.

These earlier barriers were unsuitable for the project’s environmental conditions and purpose. In contrast, the “back-up” silt curtains were correctly specified for the challenging conditions. They have now proven to be the most effective defense, even under intense pressure.

KEY FACTORS FOR MAXIMIZING SILT CURTAIN EFFECTIVENESS

So, what ensures the success of silt curtains? The effectiveness of silt curtains largely depends on several critical factors:

The Right Design – Designing silt curtains properly is crucial for success, yet it is often overlooked. Selecting a product or solution without the right design significantly reduces the chances of success. We identify the problem, collaborate on the best solution, and analyze data using specialized software (like Marineforce for silt curtains) to determine the required material properties for optimal performance.

The Right Product – The software outputs help us select the right product by ensuring it meets design parameters and is manufactured with the appropriate materials and methods. We also consider end-of-life planning, installation and maintenance. Choosing the wrong product can complicate the implementation phase.

The Right Implementation – Improper installation can strain barriers, even if the design and product are correct. Our products are designed for specialized handling, with loads concentrated appropriately. This phase also includes on-site maintenance and repair. Proactive maintenance identifies small issues early, extending material lifespan and reducing waste at the project’s end.

For more in-depth advice on these elements, check out our related blogposts:

How to select the right silt curtain: A critical decision for your project
Silt curtain specifications and types: What you need to know
What are best practices for silt curtain installation?

MAINTENANCE: THE OFTEN-OVERLOOKED SUCCESS FACTOR

Maintenance is perhaps the most under-appreciated factor influencing the long-term success of silt curtains. In the above case study, consistent maintenance played an important role in maintaining the integrity of the silt curtains over 18 months, even in adverse weather.

During storms or rough conditions, even a properly designed and installed barrier can have wear and tear. Plans need to be in place for how to rectify any incidental damage. A proper maintenance program may include provisions for on-site repairs. This can involve rotating panels in and out of service, with damaged panels being removed and new ones installed while repairs are carried out.

Maintenance should also include inspection of anchoring systems. This ensures that there are no failures of anchor systems that could cause damage to the silt curtain if the anchor line breaks.

Repairing damaged silt curtains in situ is challenging. If one panel or anchor point is compromised, it can lead to additional strain on the remaining components, increasing the risk of widespread failure.

Preventative measures are always more effective than trying to repair damage after the fact. To ensure the ongoing effectiveness of your silt curtain installation, we recommend:

Weekly visual inspections: This should include checks for signs of wear on panel connections, worn anchor lines or any degradation that could compromise performance.

Post-storm inspections: After severe weather, it is essential to immediately inspect the curtain for any damage caused by anchor drag or vessel impacts.

Preventative maintenance: Tightening anchor ropes and checking connections during inspections can prevent minor issues from escalating into larger problems.

THE BOTTOM LINE

Correctly specified, installed and well-maintained silt curtains effectively control suspended sediments, preventing them from spreading into surrounding marine environments. By limiting sediment dispersion, these marine barriers play a key role in reducing the environmental impact of dredging and construction operations. Regular inspections and proper maintenance are essential to ensure that the silt curtain continues to perform at its best throughout the project.

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