TM 5-818-8/AFJMAN 32-1030
At the lower portion of the silt fence, the geotex-
about 100 feet long and of any required width. An
tile is extended for burying anchorage.
end connector is provided at each end of the
b. Silt Curtains. A silt curtain is a floating
section for fastening sections together. Anchor
vertical barrier placed within a stream, lake, or
lines hold the curtain in a configuration that is
other body of water generally at runoff discharge
usually U-shaped, circular, or elliptical. The de-
points. It acts as a temporary dike to arrest and
sign criteria and properties required for silt fences
control turbidity. By interrupting the flow of wa-
also apply to silt curtains. Silt curtains should not
ter, it retains suspended particles; by reducing the
be used for:
velocity, it allows sedimentation. A silt curtain is
(1) Operations in open ocean.
composed of a sheet of geotextile maintained in a
(2) Operations in currents exceeding 1 knot.
vertical position by flotation segments at the top
(3) Areas frequently exposed to high winds
and a ballast chain along the bottom. A tension
and large breaking waves.
cable is often built into the curtain immediately
(4) Around hopper or cutterhead dredges
above or below the flotation segments to absorb
where frequent curtain movement would be neces-
stress imposed by currents and other hydrody-
namic forces. Silt curtain sections are usually
Figure 6-5. Use of Geotextiles near Small Hydraulic Structures.
SCOUR PROTECTION FOR BRIDGE PIER