Turbidity Curtains, sometimes called silt curtains, turbidity screens, turbidity barriers, or silt barriers are floating barriers used in marine construction, dredging projects, and similar applications to contain the dispersion of silt and sediment that is suspended during these commercial activities. Turbidity curtains are deployed to keep the project in compliance, to protect the environment, and aid in the proper operation of pumps and other equipment. Texas Boom Company’s Turbidity Curtains support compliance with the Clean Water Act and any state or local Department of Transportation (DOT) regulations. Turbidity Curtains can be deployed in parallel to increase the effectiveness of controlling the silt or runoff. Texas Boom offers a variety of fabric weights and skirt depths depending on project needs. Both permeable and impermeable skirts are available per your request. Type I, II, and III are recommended for slow, medium, and fast-moving waters, respectively.
Turbidity Curtains are constructed using floatation at the top to suspend the turbidity curtain in the water. Skirts are attached below the floatation and serve as the barrier to control the silt and sediment. Tension cables are used on heavier duty turbidity curtains to provide strength. Ballast chains provide strength as well as weight to keep the skirts oriented as close to vertical as conditions allow. The are several different configurations available based on how curtains will be connected end-to-end to provide longer spans, ranging from grommets only to universal aluminum connectors.
Type 1 turbidity curtains are suitable for use in protected waters where the effects of the wind, waves, and currents are minimal. Texas Boom manufactures Type 1 DOT compliant turbidity curtains.
Type 2 turbidity curtains are best used to contain silt and turbidity in moving water applications. Type 2 turbidity curtains are manufactured using high strength fabric with heavy-duty tension members. These Type II turbidity curtains are best used in dredging and marine construction areas that experience mild current, wind, and wave activity. Texas Boom manufactures Type 2 DOT compliant turbidity curtains.
Type 3 turbidity curtains are best used to contain silt and sediment in water applications with swifter moving water and greater wind exposure. Type III curtains are manufactured using high strength fabric with heavy-duty tension members. These Type 3 turbidity curtains are best used in dredging and marine construction areas that experience strong currents and tides, high winds, and greater wave activity. Texas Boom manufactures Type 3 DOT compliant turbidity curtains.
Turbidity Curtain Applications
- Bridge construction and repair
- Dam construction and repair
- Marina and harbor projects
- Bulkhead installation and repair
- Pile driving projects
- Erosion and runoff control
- Port and terminal projects
- Pipeline crossings
- Coastal and shoreline restoration and rehabilitation
- Intake construction and repair
- Discharge management
Turbidity Curtains are available with permeable and impermeable skirts.
Permeable skirts: Turbidity curtains with permeable skirts allow water to flow through the skirt while containing the silt or sediment suspended in the water. The permeable skirts are fabricated using geotextile fabric that serves as a filter. Permeable skirts are typically used in applications with fast water, waves, or other demanding conditions, or where there are specific environmental concerns.
Impermeable skirts: Turbidity curtains with impermeable skirts completely block the flow of water as it meets the skirt. The non-permeable skirts are fabricated using PVC fabric that does not allow water to flow through the skirt. These are more commonly deployed in applications with slower-moving or still waters and calmer weather conditions.
Furling Lines or Reefing Lines
Furling lines (also referred to as reefing lines) are an optional feature on turbidity curtains. These ropes run vertically spanning the height of the turbidity curtain on both sides at set intervals. The furling lines are attached at the top through tabs with grommets, at the bottom at the ballast chain through a grommet, and then looping back to the top on the reverse side of the skirt to another attachment tab. The furling lines can be used to adjust the depth that the skirt extends below the surface. They can also be used to slope the bottom of the turbidity curtain to mirror the contour of the bottom. Because the depth of the turbidity curtain can be adjusted, it allows the curtain to be used in multiple locations, at locations with varying depths, and at locations with significant tidal swings.
How to Use Turbidity Curtains
Turbidity curtains are most effective when the bottom of the skirt is suspended a foot above the bottom. This prevents the build-up of silt on the base of the skirt which over time can result in the freeboard of the turbidity curtain becoming submerged below the water surface. The bottom of a turbidity curtain dragging on the bottom can also generate additional silt. When the skirt drags on the bottom, it can also reduce the life of the turbidity curtain. Finally, by leaving a gap between the skirt and the bottom of the body of water, it allows for fish and other wildlife to freely bypass the turbidity curtain without harm.
When tides impact the depth of the water where the turbidity curtain is being used, the height of the curtain should be set at a point appropriate for the average depth at low tide. Turbidity curtains can also be fabricated with tapered bottoms to accommodate changing depths over the span where it is being used.
Turbidity curtains can be attached to fixed objects on land and/or using anchor systems. The exact configuration of the turbidity curtain deployment is dependent on the specifics of the project. TBC advisors are available to consult with you to determine your exact needs.
Turbidity Curtain installation instructions can be found here.