Designing Effective Barrier Installations

Floating turbidity barriers are effective in preventing silt and sediment migration into water courses. However certain rules must be followed in order to make the installation successful. Three of the most critical rules are:

1. The silt and sediment must be contained in the retention area long enough to allow it to settle.
2. The preceding rule implies that the silt and sediment particle sizes will actually settle in the time allotted by the construction conditions. This table shows the time required for particles of various sizes to settle one foot in calm water at 68 degrees F.
3. The current in the containment area must not be so great that the particles are allowed to migrate beyond the barrier before settlement can occur.

For small particle sizes, barriers should drop to 1 foot above the surface. For larger particles, many specifications only require 5’ deep barriers because sediment drops so quickly, and water speeds are significantly slower at deeper depths.