Silt curtains - a review of their role in dredging projects

As environmental mitigation associated with dredging and marine construction activities becomes ever more a focus of attention, the use of silt curtains to contain fine material locally to the dredging operation has increased. A silt curtain is typically simple in design, comprising of a geo-textile sheet attached to floats that are weighed down to the sea floor and anchored in place. The expected result is to prevent the transport of sediment out of the work site and into the surrounding environment. However, few documents exist that consolidate the current understanding of the use of curtains and the controlling factors associated with the deployment of them, including consideration of their purpose, design, development and limitations.

A cynic’s view is that silt curtains are often installed to comply with regulatory constraints and may offer limited practical value, especially when they are left unmaintained. Poor understanding of silt curtain design and limitations often means they are installed in unsuitable environments, resulting in unsatisfactory performance. Critically, once a curtain is installed; without good management and regular maintenance, the geo-textile will often perish leading to a significant reduction in its effectiveness. Different installation methods exist along with multiple configurations; consideration of the environmental conditions should be made prior to the design and installation of a silt curtain. This paper will consider a range of parameters that affect the effectiveness of silt curtains.