Unified Soil Classification System group symbol. For example, GW-GM corresponds to "well-graded gravel "with silt"." If the soil has more than 15% by weight retained on a #4 sieve (R > 15%), there is a significant amount of gravel, and the suffix "with gravel" may be added to the group name, but the group symbol does not change. For example, SP-SM could refer to "poorly graded SAND with silt" or "poorly graded SAND with silt and gravel." Unified Soil Classification System The Unified Soil Classification System (USCS) is a soil classification system used in engineering and geology to describe the texture and grain size
Silt fence given silt fence after a storm event, and not turbidity, etc. as sediment-retention is the end goal, and not a water-quality measurement used in erosion control, for instance. Silt fences may perform poorly for a variety of reasons, including improper location (e.g. placing fence where it will not pond runoff water), improper installation (e.g. failure to adequately embed and backfill the lower edge of fabric in the soil) and lack of maintenance—fabric falling off of the posts, or posts knocked down. A silt fence top-full of sediment may need maintenance/replacement, but it is a huge success. The fabric may become