![]() ![]() ![]() Trailing suction hopper dredger (TSHD): A trailing suction hopper dredger is a suction pipe which work and load the dredge material into one or more hopper in the vessel the hopper are full TSHD sail to a disposal area and either dumps the materials out of the hopper, some dredger also sect of load using drag bucket and conveyors, the largest trailing suction hopper dredger in the world currently.Snag boat dredger: A snag boat dredger is been designed to remove big debris from rivers and canals.Air lift: Lift is a type of small suction dredgers which is use under by divers work by blowing air into the pipe and that air being lighter that water rises inside the pipe dredging water with it.Clam shell or grab dredger: A clam shell dredger pick up seabed material with a clam shell bucket which hangs from an on bond, crane or a crane barge, this technique is often used in excavation of bay mud, most of these dredges are crane barges with spuds.During the 1980s Auger dredger were primarily used for sludge removal application from waste water treatment plant but today auger dredger are used for wider variety of application including river maintenance and sand mining. The first widely used auger dredger were designed by mud eat dredging in the 1980 s which was run by national car rentals but is now a division of Ellicott dredges. Auger suction: Auger suction is a process that functions like a cutter, suction dredging but the cutting tools is a rotating Archimedean screw set, at right angles to the suction pipe.Bucket dredging: A bucket dredger is equipped device that pick up sediment by mechanical means often with many circulating attached to a wheel or chain.Gerel (1998) stated that the activities of dredging can released heavy metals from machine which can affect nearby building and aquatic lives.Īccording to Robbins (2006), there are different types of dredging equipments which are as follows. clean water restricted only licensed practitioners to participate on dredging activities but because of corruption and bribery it has been neglected, especially our Country Nigeria the establishment of environmental impact assessment (E.I.A) is no longer effective. The United State clean water act further stated that any discharge of dredging or fill material into water of the United State including wet land is forbidding unless authorized by a permit issued by the Army Corps of Engineer because of the potential impact to the environment. The World Health Organization (WHO, 2001) on a research carried out reviewed that, most of the dredging activities carried out in developing countries are close to residential premises which have resulted to collapse of structure cracking of building walls and also claimed lives and properties. According to him, dredging can also produce materials for land reclamation or other purposes (usually construction of roads and bridges) and has created disturbances in water bodies, health and environment and aquatic ecosystem often with the adverse to impact.Īccording to Davidson (2008) all methods of dredging release suspended sediments into water column during the excavation and during the flow of sediment from dredgers to barges increased suspended sediments can affect filter feeding organisms such as shell fish through clogging their breathing organs, similarly young fishes can be damaged if suspended sediment become trapped in their gills and increased fatality of young fish have been observed in heavily turbid water while adult fish are likely to move away from or avoid areas of high suspended solid such as dredging site. The process of dredging creates spoils (excess materials) which are carried away from the dredging area. Where these activities are being carryout, it is used as a means to replenish sand on some places where sand has been lost due to coastal erosion. Most dredging activities according to Robin (2006) are done to maintain or make deeper navigational channels anchorages or berthing areas of the safe passage of boats and ships unknowingly that its activities have significant implications on aquatic lives and the environment. ![]()
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