Tough Guy® Floating Turbidity Barrier Type 1.DOT

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What Is Turbidity?

Broadening or deepening an area and depositing of the dredged material in open water will generate turbidity by suspending fine-grained particles of the material in the water columns. Water columns are ways to measure pressure and they run from the surface of the water to the bottom. The effects of various levels of turbidity, whether direct or indirect, have not been measured, but the effects of discoloration of the water and lack of clarity can be unpleasant.Turbidity can be limited under certain circumstances by using the right turbidity curtain. These curtains, or silt curtains, are vertical barriers designed to hold the turbid water created by the dredging process. The curtain is manufactured for a variety of depths.

Basically, turbidity curtains offer a barrier that extends from the surface of the water to several feet below the surface to prevent the turbid water from reaching the water's surface and spreading by dispersion or by the flow of the current.  In the case of shallow water, the barrier will extend from the surface to the bottom bed. The effectiveness of the curtain is determined by the level of turbidity reduction outside versus inside the curtain's enclosure.

Turbidity curtains are used on a wide variety of engineering and construction projects. These curtains are also used for more than dredging such as being placed across ditches and spillways and on marine construction undertakings including outfalls, pile driving, highways, and for bridges crossing a lake, as baffling with several tires across the mouth of a canal to enclose discharge from a confined disposal area. They are also used to combat the flow inside the disposal area. During the dredging and open water disposal operations, these curtains are distributed to surround the discharge mark or to form a barrier downstream of the turbid area.

Occasionally, debris including concrete, dust, foreign soil, metals, and oils will find their way into the water when construction materials are carried out nearby.

Turbidity curtains and silt curtains are powerful enough to retain debris out of the water completely or include it in places where performance is being completed in the water itself. Turbidity curtains float on the surface of the water and create a barrier to control how far debris or silts can spread. These barriers can be customized in length so they can encompass a large or modest area including a shoreline. The curtains are laid out in order to float on the water. As debris is brought up from the floor of the water, or if the debris comes into the water from land, the curtains will catch it and prevent it from spreading.

One of the biggest reasons for using turbidity curtains or silt curtains is protecting organic water resources. There's a lot of silt and sediment on the floor of a body of water but they are not all-natural to the organic area. Water is good for removing pollutants and debris from the air but many particles settle on the bottom of the water and are components of the sediment layer. To make sure that protected layers are not stirred up during operations, it's our responsibility to get help from appropriate turbidity curtains or silt curtains because water is not able to do it alone.

Project Configurations

Type II -

The configuration should be used in areas where the currents are slow or moderate. This would be 2 knots or 3.5 feet per second. The wind and waves can affect the curtain.

Type III -

This configuration should be used in areas with the potential of currents up to 3 knots or 5 feet per second and in areas where wind and waves are present.

Turbidity curtains should extend the entire depth of the waterway whenever the area is not subject to tidal activities or significant wind or wave forces. In tidal or wind and wave activities, the curtain should never be long enough to touch the bottom.

A one-foot gap should be in place between the ballast and the bottom of the skirt which would be during low water. Movement of the lower skirt over the bottom caused by tidal reverses or wind wave activities in the flotation system could fan and stir up settled sediments.

In tidal or wind and wave situations, it's not practical to extend a turbidity curtain depth lower than 10 to 12 feet below the surface, even in deep water. Curtains installed deeper than that will suffer from large loads and stress on the curtain material as well as the mooring system. Also, a curtain installed in this manner can billow up toward the surface under the pressure of the moving water. This will result in an affected depth that is significantly less than the skirt depth.

The turbidity curtains should be placed parallel to the direction of the water's flow.