Permeable Silt Curtain vs. Impermeable Silt Curtain

The question is often asked:  Should I use a permeable or non-permeable silt curtain?  We hope to shed some light on the topic to help our customers understand the difference between these two types of turbidity curtains.  For reference, these are also referred to as turbidity barriers, silt barriers, silt curtain, sediment filter barrier, floating silt fence, floating curtains, and floating sediment fence.

Permeable Turbidity Curtains

Permeable silt curtains utilize a geotextile fabric to form the skirt.  This type fabric allows for water to flow through the silt curtain through tiny openings in the fabric, serving as a filter.  These openings are large enough to allow the water to pass while being small enough to trap any silt or sediment that may be present.  This can be important for particular applications, as well as aiding the longevity of the silt curtain.  By allowing water to pass through the silt curtain, the pressure exerted on the skirt is reduced.  This helps both with the ability to anchor the silt curtain into postion, as well as the extended usable life of the silt barrier.  These permeable turbidity curtains are typically deployed in waters with stronger currents and areas subject to larger waves.  

Impermeable Turbidty Curtains

Impermeable silt curtains are made using a solid PVC fabric to construct the skirt that hangs below the freeboard float.  This solid silt skirt impedes the flow of water and any silt or sediment that may be suspended in the water.  These non-permeable silt curtains are typically deployed where the water currents are light and wave conditions minimal.  There may be specific factors with a given application that require the use of a non-permeable skirt to accomplish the intended purpose.

Other factors to consider when purchasing a turbidity curtain are the depth of the water and the contour of the bottom where it will be deployed, the water and weather conditions, and how the curtain will be anchored.  All turbidity curtains are recommended to be suspended at least one foot above the bottom of the body of water.  By keeping the curtain off the bottom, it helps reduce creating additional silt, as well as avoiding any issues with the entire silt curtain being dragged under by snags or build up of sediment on the bottom of the curtain.  Turbidity curtains are typically produced in 50 foot or 100 foot lengths (custom lengths available), and sections can be connected end to end to form longer lengths.  

Both type curtains are effective in controlling turbidty by impeding the movement of the silt or sediment suspended in the water.  Not sure which is best for your application?  Contact Texas Boom Company for expert advice and a prompt free quote.