Silt Curtains

SILT CURTAIN APPLICATIONS

Silt Curtains are generally required by marine service companies, construction companies, erosion and sediment control contractors, consultants, councils and state road authorities for the following types of projects:

• Tailings Dams
• Water Quality Improvement (in dams, basins, creeks and rivers)
• Dredging
• Bridge Construction
• Piling
• Foreshore Maintenance Works
• Reclamation
• Rockwall Building
• Protecting Inlets (especially during maintenance work)
• Pier, Jetty and Wharf Maintenance and Construction
• Containment of Ash and Fire Debris
• High Efficiency Sediment Basin
• Sediment Ponds
• Port Development

HOW TO CHOOSE YOUR SILT CURTAIN

Below is a guide we use in consultation with clients illustrating our suggested options per waterway and the fundamentals of each design class.

Class 1

Low-Risk Applications
Little to no tidal, wave and/or wind forces.

Example: lagoon, pond, stream

Class 2

Medium-Risk Applications
Moderate wind and/or water forces.

Example: river, calm harbour

Class 3

High-Risk Applications
Strong wind and water forces.

Example: open ocean, harbour, river mouth

HOW DEEP SHOULD THE CURTAIN BE?

Since the purpose of a floating silt fence is to disrupt the water flow and allow the suspended sediment to settle, your curtain should be deep enough to facilitate the following:

• Provide sufficient disruption to the water flow (current)
• Remain clear from the sea bed at low tide
• Where required, adhere to EPA or other environmental requirements

Allow a minimum half metre gap between the curtain and the sea bed at low tide. Silt curtains are intended to promote the settling of sediment by driving particles closer to the sea bed. Water will always find the path of least resistance, therefore the water will pass between the lower edge of the curtain and the sea bed. Sediment must be forced deep enough to improve settlement. The gap between the curtain and sea bed provides a significantly more effective pressure release than the porosity of geotextile.

The deeper the curtain, the greater the hydraulic loading which can cause the curtain to flare, resulting in additional horizontal loads. Further, if the curtain penetration is too great, the water that passes beneath the skirt will be squeezed through a small gap resulting in possible further erosion of the sea bed and a resuspension of particulate into the upper water column further downstream.

HOW DO I ENSURE SILT CURTAIN EFFECTIVENESS?

Silt curtain effectiveness is considered as the degree of turbidity reduction achieved within the controlled area relative to the turbidity levels outside of the area. Factors which affect this effectiveness are:

• The quantity and type of material in suspension
• The characteristics, design and construction of the turbidity boom
• The mooring and square metre area of the curtain deployed
• Deployment location and positioning
• The hydrodynamic conditions experienced such as tidal movement, wind velocity and wave height

The silt curtain is not designed to dam the turbid water. Instead, it provides a control for the dispersion of the sediment laden water and allows this suspended silt to settle. It is widely accepted that the interaction between the water column and curtain is a crucial factor in determining the efficiency of the silt curtain. It is integral to the design that the hydrodynamic loads are understood. These loads are the forces applied to the moorings and silt curtain resulting from currents, winds and waves. These forces can affect the buoyancy and ballast ratio, optimal skirt depth and choice of moorings and anchors.

ARE SILT CURTAINS REUSABLE?

Silt curtains can be cleaned and properly stored for reuse. If the curtain has been inspected, is in good condition and deemed suitable for reuse, it can be cleaned down with a high-pressure washer to remove biofouling, silt and sediment from the geotextile.

Once thoroughly dry, the curtain can be repacked on a pallet and stored. If serviced and stored properly, a high-quality silt curtain system can be reused numerous times.

GET EXPERT ADVICE FROM OUR TEAM

Our team will provide free consultations and help spec curtains if required. We offer:

• A range of material and component options
• Handles and hardware built-in to assist with rapid deployment
• Skirt depths in half metre increments up to 20m deep
• Curtains pre-connected and ready to deploy (if requested)
• Complete design, supply and install consultations