SEDIMENT CONTROL PRACTICES
Under the sediment
control program, new development that requires that sediment control must install
one or combination of sediment control practices. These practices include stabilized
construction entrances, earth dikes, temporary swales, sediment traps, sediment basins,
silt fence, and super silt fence.
[Stabilized Construction Entrance] [Earth Dike] [Temporary Swale]
[Sediment Trap] [Sediment Basin] [Silt Fence] [Super Silt Fence]
Stabilized Construction Entrance
A stabilized construction entrance consists of a pad of two inch stone.
The size of the pad is typically six to eight inches thick, approximately 50 feet long,
and approximately 12 to 15 feet wide. This sediment control practice is placed at the
entrance and exit of a construction site to scrub the dirt or mud from the tires of
construction vehicles before leaving the construction site. This helps to reduce how much
mud is tracked onto the roadway.
Earth dike
An earth dike is a continuous mound or pile of dirt compacted and
stabilized with seed and mulch. This is used to divert or force sediment laden waters to a
desired location on the construction site, such as a sediment trap or sediment basin. This
may also be used to prevent clean water from off site entering the construction site. This
off site water could enter the construction site and add to the on-site much runoff that
must be controlled by the sediment control practices.
Temporary Swale
A temporary swale is a ditch stabilized with seed and mulch. This
practice functions similarly to an earth dike to divert runoff to a desired location on
the construction site.
 Sediment Trap
A sediment trap is an excavated area designed to store sediment runoff
and detain the drainage flowing into it. The sediment trap allows some sediment to
precipitate from the drainage before being discharged to receiving streams. Not all of the
sediment is filtered out of the discharge because of the nature of the soils. Clay soils
remain suspended much longer than sandy soils. Therefore, it is possible to see discharge
from a sediment trap that appears sediment laden.
Sediment Basin
A sediment basin is similar to a sediment trap but is designed to
handle a larger drainage area than a sediment trap. Often a stormwater best
management practice (BMP) is used as a sediment basin during the construction
phase. After the site is stabilized, the accumulated sediment is removed and the sediment
basin is converted to the BMP.
Silt Fence
Silt fence is a filtering device made from geotextile fabric stretched
between wooden stakes. Silt fence is installed perpendicular to the ground, with six
inches of the fabric embedded into the ground. This method is best used to filter runoff
in areas where the drainage is not concentrated.
Super Silt Fence
Super silt fence is a device very similar to silt fence except that the geotextile
fabric is placed against chain link fencing. Additionally, the wooden stakes are replaced
with six foot fence posts driven into the ground three feet deep. Super silt fence is
designed to handle runoff from larger drainage areas than silt fence. Super silt fence is
also used in areas where minor concentrations of water may occur.
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