Silt has a mineral origin of quartz and feldspar of a size between sand and clay. It may occur as a soil or as a sediment mixed in suspension with water in a body of water. Silt buildup creates navigation issues for large ships entering or departing ports and must be extracted to keep channels open and deep to avoid grounding of the vessel. A good example of silt extraction is in Charleston Harbor, Charleston SC where container ships and cruise ships transit. In the past, submarines also used a submarine base on the Cooper River to transit to the harbor and then to the ocean. Build up of silt was an ongoing issue. Hydraulic pumps can be used to dredge the silt and pump it onto river banks. Flotation devices can also be used to create barriers so that the silt is pumped from the body of water and deposited behind the barriers.

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