Filter Fabric

There are two types of geotextile filter fabrics: needle punched nonwoven and woven monofilament. The most commonly used are needle punched nonwovens. These popular fabrics are used in applications such as wrapping a perforated pipe or the gravel in French drain. A typical silt fence consists of a piece of synthetic filter fabric (also called a geotextile) stretched between a series of wooden or metal fence stakes along a horizontal contour level. There are also nonwovens robust enough for heavy duty filtration applications such as placement under rip-rap for shoreline erosion control. The nonwoven filter fabrics are more robust in handling as compared to their woven counterparts, and therefore were often preferred in large-scale erosion protection projects

In cases where fine grain sands (beach sands) are present, a woven monofilament is required. Monofilaments prevent the clogging that can occur when fine particles migrate into the matrix of a needle punched nonwoven and get stuck.