Silt fence controls sediment temporarily on construction sites in improving the condition of water that ultimately will drain to waterways as runoff. Silt fence also keeps silt buildup from entering streams changing the natural waterway flow which can cause further erosion and related problems. It is made of synthetic or geotextile fabric mounted on stakes. Silt fence is commonly installed around the perimeter of a construction site or construction activity. Also the Environmental Protection Agency likes to see silt fence installed in areas of ground disturbance where silt-laden water could drain downward or towards ditches, ponds, swales, rivers, etc.
The only way a silt fence will be an effective barrier is if it is trenched in below grade several inches and backfilled against. Also the fence must be maintained throughout the course of the work to be effective, providing repairs to rips and otherwise vulnerable areas that could allow silt passage.