Silt fences should be inspected routinely to make sure they are performing as intended
Large runoff events and construction equipment often can damage your silt fence installations.
The ASTM silt fence specification (ASTM 2003) recommends removing sediment deposits from behind the fence when they reach half the height of the fence or installing a second fence.
However, there are several problems associated with cleaning out silt fences. Once the fabric is clogged with sediment, it can no longer drain slowly and function as originally designed. The result is normally a low volume sediment basin because the cleaning process doesn't unclog the fabric. The soil is normally very wet behind a silt fence, inhibiting the use of equipment needed to move it. A back hoe is commonly used, but, if the sediment is removed, what is to be done with it during construction?
Sometimes the best solution is just to install a new fence above or below the existing silt fence. This allows you to leave the sediment in place where it is stable and let the new silt fence collect additional sediment. Depending on the installation, small construction sites might not have sufficient space for another silt fence.
Regardless of the situation, plan ahead so that you can avoid potential problems and keep the fence working as it should. It is very important to allow adequate access when installing silt fence so inspections and maintenance can be performed on a routine basis.