Dredger

A dredger is equipment used underwater to excavate sediment from the bottom of a body of water and dispose of that material in a different location. Dredging is necessary for various reasons, but principal ones include the creation or deepening of existing harbours or waterways; preparation of an area of water for the construction of bridges, piers or docks; for land reclamation; or for the collection of materials for use in the construction industry. There are two main types of dredgers, classified by the methods used to move material loosened from the water bed to the surface. These are mechanical dredgers and hydraulic dredgers. The mechanical dredger works off the shoreline or a barge and uses a form of a bucket to excavate and lift the material to the surface, placing it either onto the barge or on the bank immediately next to the body of water. Hydraulic dredgers act like a vacuum, pumping sediment through a pipeline to an off-site location and can be used over a greater distance. Dredging can have a detrimental effect on the aquatic ecosystems within a body of water and so carrying out any underwater excavation with due regard for environmental impacts is a priority.