Every silt curtain installation is unique, and therefore, the installation tips below are general recommendations only. Actual conditions might vary, depending on many factors. Each installation should be planned according to the site conditions and silt curtain model.
Optimal Silt Curtain Installation
Silt curtains should be located parallel to the direction of flow of a moving body of water; not across the main flow of a significant body of moving water. A minimum 0.5m gap should exist between the weighted, lower end of the skirt and the bottom at Low Altitude Tide (LAT), allowing the water to flow under the curtain, which would:
• Reduce the forces on curtains and anchors.
• Reduce the risk of curtain failures. In exposed waters with strong tides, the depth of curtain will be much less than the water depth to minimize forces on curtain. The water should flow under the curtain, as it will not flow through the curtain.
Silt curtains are designed as a containment barrier to allow sedimentation inside the containment area. The settlement time would vary in different conditions. In calm waters, the silt would settle in 24-48 hours. But in rough waters, this time would go up considerably. In rough waters, the objective of the silt curtain is to reduce the spread area as full containment is not possible. These silts should be controlled to settle from the upper 2-3m water column, which will drastically reduce the spread area.
Anchoring is a very important consideration, as if done incorrectly, it can reduce effectiveness of the entire structure. Silt curtains are typically attached to floats that are weighed down to the sea floor and anchored in place. Anchors are designed using a painter-line system to ensure current or wave force on the anchoring is displaced by the tripping line, limiting the force placed on the curtain.
For installation, the anchors should be placed to form a right-angle triangle at High Altitude Tide (HAT). Therefore take the water depth at HAT and the rope length at each location to work out the distance to place the anchor away from the silt curtain. Adjustments will always need to be made on-site during the installation however. It is also recommended to monitor the silt curtains and anchoring for 24 hours following installation to ensure adequate functioning. See image above.
Other Silt Curtain Installation Tips
• Installation location should be at least 50m from the toe of any reclamation works to reduce risk of damage to curtain and to allow an adequate settlement area.
• Base of curtains skirt should be kept clear of any rock breakwater and out of the shallow water where significant breaking waves may be present.
Please download our Guideline – Optimal Installation for further information.
Our contracting arm, Ecocoast, can carry out the complete installation, or provide installation supervision, if required. We can also provide you with silt curtain installation manuals for step-by-step installation instructions. Call us at +971 4 885 3944 or fill in the contact form.