Chatoyer Environmental has manufactured over 150,000m of silt curtain since 2009. These floating turbidity curtains have been deployed in various projects around Australia, New Zealand and in Papua New Guinea, New Calendonia, Fiji and Vanuatu.
Chatoyer Silt Curtain Designs
Our popular designs are categorised into types we refer to as a Class, each based on functionality that generally suits common applications and operating sea states. The range of curtains is made in 20m lengths. Multiple lengths are connected to span the required length. Floating silt curtain can be customised to suit specific project requirements such as project longevity, operating sea states and government regulations to name a few. For permanent or heavy-duty turbidity curtains, upgrades of materials, components and external floats are available.
Little to no tidal, wave and/or wind forces.
Example: lagoon, pond, stream
Moderate wind and/or water forces.
Example: river, calm harbour
Strong wind and water forces.
Example: open ocean, harbour, river mouth
How Are the Curtains Supplied?
Chatoyer Environmental supplies silt curtains with the skirt furled and multiple sections connected up to a length of 100 metres per pallet. This enables immediate deployment of the silt curtain on site.
When projects require a large length of silt curtain resulting in numerous pallets, each pallet will be clearly identified and numbered. Pallet sections will be joined in consecutive fashion and pallets should be laid down as near as possible to the deployment zone.
How Deep Should the Silt Curtain Be?
Since the purpose of a silt curtain 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 silt 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 silt curtain 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 the 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 silt curtain
- The mooring and square metre area of the silt 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 silt curtain is a crucial factor in determining the efficiency of the silt curtain. It is integral to the silt curtain 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.
How Do I Install the Silt Curtain?
One of the critical reasons for a silt curtain failure is that the installation was not completed correctly or with enough diligence. This can then be further impacted by a lack of maintenance program. We strongly recommend that a professional service is employed to install your system. A failure of the Silt Screen can be avoided if care is taken at the front end.
To assist with installation, ensure a large enough area is available to work with the silt curtain prior to deployment. Access to the waterways should be understood and coordinated in advance of the installation. The anchoring system needs to be installed in the waterway prior to deploying the silt curtain. Once the desired length of silt curtain is connected, the furled curtains can be towed to the desired deployment location at a maximum speed of two to three knots. Ensure the curtain remains furled and is secured to the anchoring system. After the furled curtain has been anchored, the curtain should be checked to confirm the skirt is not twisted around the flotation chamber. Once the furled and untwisted curtain is anchored in the right location, remove the ties furling the curtain and allow the silt curtain system to drop into place.
How Do I Remove a Silt Curtain?
To recover the silt curtain, disconnect the silt curtain from the anchoring points and furl the curtain skirt. Then remove the mooring systems. Tow the system back to the launching site for removal from the waterway and responsible disposal.
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.