Dredging is underwater excavation. It can be used for a wide range of applications, and is done through several methods. Familiarity with common terminology related to dredging can make it easier to understand the process and applications.
Waterway - Any body of water which can be navigated by boat. Some are naturally existing, and other prospective waterways must be constructed by dredging.
Land Reclamation - The creation of new land with material from dredging. It may be used for recreational land, waste management, or flood and erosion control.
Beach Nourishment - Use of dredged sand to rebuild a beach. Popular beaches which have been subject to erosion are often rebuilt in this way. Erosion may have been caused by heavy use or weather patterns.
Seabed Mining - Mining in offshore locations for precious metals. Once a prospective seabed has been located, dredging can be used to access these resources.
Containment Remediation - Use of dredging as a strategy for cleaning up areas affected by chemical spills or other environmental crises in lakes, ponds or rivers.
Suction Dredging - A common type of dredging in which sediment is excavated by sucking it through a tube. It can then be deposited elsewhere.
Cutter Suction - A type of dredging in which harder surfaces can be cut prior to suction. This is suitable for rockier areas.
Bucket Dredging - A mechanical means of offshore excavation. These may be suitable for constructing deeper passages through coral or other more durable materials.
Snagboat - A type of equipment that removes very large debris from smaller bodies of water such as rivers, lakes, or ponds.
Dredging allows an engineer to excavate sediment from the bottom of a lake, ocean, pond, river or sea. One reason you might need this industry is to make room for boats and other water crafts to navigate shallow lakes or rivers. Offshore bridges, ports and piers cannot be built until sediment is removed for construction. The process also helps restore sand to beaches affected by erosion. Garbage is removed from water sources using this equipment. Certain gems and metals are harvested using these industry techniques. Some species of seafood are harvested using dredgers.
Methods for removing the sediment vary. Suction tubes work like vacuums sucking up the sediment into storage vessels. Sediment is drawn into the tubes where it drains into hoppers. Eventually, the hoppers are emptied on land. Suction tubes may have augers or cutting devices on them to help break up packed sediment. Injection pumps spray liquid into the sediment, where it is disturbed and becomes part of the current and settles elsewhere. Grabbers attach to a crane. The hydraulic arm is lowered into the sea or ocean where it scoops up material. Bed levelers are similar to bulldozers pushing and moving the sediment to other locations, usually for maintenance of a previously cleared area.
The earliest dredgers were simple flat bottomed boats with spikes. As the boat flowed along, the spikes scraped at the sediment and the ocean tide carried the excavated material away.
Done improperly, the technique damages the fragile offshore ecosystems. Plants and wildlife may die as a result of a construction project. A company using any dredger must follow guidelines set forth in the Clean Water Act. Contractors must also have the proper paperwork. Protect the environment by making sure to choose a licensed dredging company.