They can work in tight areas and are efficient when large barges are used for long-haul disposal to the placement location. Mechanical dredges are capable of removing hard-packed materials or debris. Mechanical dredging involves removing sediment with machinery, usually with a bucket type of mechanical dredges such as a dipper dredges or clam shell dredges. Sediment built up in the channels comes from multiple sources, including settling of upland soil suspended in the water, slumping of the sidewalls of the existing channel, resuspension from ships passing through the channel, and resuspension from wind and tide actions. Sarbanes Ecosystem Restoration Project at Poplar Island. Sediment dredged from Federal channels is currently being placed in facilities owned by MDOT MPA, such as the Masonville or Cox Creek DMCF or the Paul S. Smaller ones can dredge in less than 2 metres depth, whilst some of the biggest CSDs can reach depths of more than 35 metres.Large cargo ships require passage through shallow portions of the Chesapeake Bay to access the Port of Baltimore, so Federal shipping channels are dredged by CENAP.Ĭhannels are regularly maintained via dredging. The dredging depth depends on the size of the dredger. The working principle of the cutter suction dredger is that it disintegrates or breaks the cohesion of the soil to be dredged mechanically by this rotating cutter head, with a half dozen ‘toothed blades’, which vary in size and type depending on the material to be dredged.Ĭutter suction dredgers come in a variety of sizes and types with a total installed power ranging from 200 kW on the smallest dredgers to some 30,000 kW for the largest. The cutter head is a mechanical device, mounted in front of the suction head which rotates along the axis of the suction pipe. Regardless of size, all cutter suction dredgers are equipped with a rotating cutter head, which is able to cut hard soil or rock into fragments. Some cutters have a pontoon hull without the means of propulsion (non-propelled), and others, shaped like a ship, are self-propelled and seagoing. They have the ability to dredge nearly all kinds of soils – sand, clay, rock – and are used where the ground is too hard for trailing suction hopper dredgers. “Facts About Cutter Suction Dredgers” describes a type of hydraulic dredger that can dredge nearly all kinds of soils, especially hard ground and rock.Ĭutter suction dredgers (CSDs) are classified as hydraulic dredgers and are the most common vessels in the hydraulic/mechanical category.

How does hydraulic dredging work