Hi I’m Glyn Onione the Senior Technical Consultant for Aquatic Engineering in the UK.
I’m often asked by contractors what is the difference between a turbidity curtain, a silt curtain, a silt screen or a floating silt fence (and a lot of other variations)? Well the honest answer is absolutely nothing – they are all names for the same product really.
It largely depends where in the world you are working; here in the UK we have almost entirely adopted the description of Silt Curtains, or sometimes Floating Silt Curtains. This is the accepted name for a fabric curtain which has an integral floatation system in the top (above water), a geotextile curtain hanging down in the water column, usually to the lake or river bed, where an integral ballast chain or weight keeps it tight to the benthic zone (lowest level of a body of water such as an ocean or a lake, including the sediment surface and some sub-surface layers), thus not allowing silt to escape underneath it.
In the USA they are often called Turbidity Curtains or Turbidity Barriers – In America, they further classify them as Type I, Type II and Type III – this denotes the grade of silt curtain and the environments they can be deployed in. This classification was developed I believe by the United States Army Corp. Engineers (USACE). However it is rarely used in the UK and to be honest limiting to 3 classifications can be rather restrictive, especially here in the UK, where we have such extreme tidal ranges and flow variations.
A good silt curtain provider, like Aquatic Engineering will be looking at the best value product for their client which will successfully ‘keep silt in its place’!
Questions which need to be answered before a solution can be offered are such things as:
Is it still or flowing water? – Is it a salt or fresh water application? – How long does it need to be deployed for – days, weeks, months, years or indefinitely? – Is there boat access required?
The questions need to be pretty exhaustive otherwise an “off the shelf” silt curtain solution, regardless of its classification, could well be inappropriate, and more than likely very expensive. Which is why here at Aquatic Engineering we spend time learning our clients needs, making sure the best silt curtain solution or service is supplied.
The purpose of a silt curtain is to prevent the silt created during civil engineering works, dredging or bank reprofiling etc. from entering the external water column (beyond the silt curtain), but I will deal with that aspect later, along with other such commonly raised questions as: Do I need anchors? Can I install a silt curtain across a river? How deep can a silt curtain be? What other uses can silt curtains be put to and what is the difference between a silt curtain and a silt boom?
If you have any questions or would like to talk through your civil engineering projects please get in touch.
Glyn Onione, Senior Technical Consultant at Aquatic Engineering
Call 01983 616668 Keep up to date with our silt curtain installations here