Sediment control practices
Under the Sediment Control Program, new developments that require sediment control must have one or combination of sediment control practices. These practices include stabilized construction entrances, earth dikes, temporary swales, sediment traps, sediment basins, silt fences and super silt fences.
Stabilized construction entranceA stabilized construction entrance consists of a pad of 2-inch stone. The size of the pad is typically 6 to 8 inches thick, approximately 50 feet long, and 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 reduce how much mud is tracked onto the roadway.
Earth dikeAn 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 entering the construction site. This off-site water could enter the construction site and add to the on-site runoff that must be controlled by the sediment control practices.
Temporary swaleA 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 trapA 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.
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.
A super silt fence is a device very similar to a silt fence except that the geotextile fabric is placed against chain link fencing. Additionally, the wooden stakes are replaced with 6-foot fence posts driven into the ground 3 feet deep. A super silt fence is designed to handle runoff from larger drainage areas than a silt fence. A super silt fence is also used in areas where minor concentrations of water may occur.