Dredge drag headThe dredge drag head of a suction dredge barge on the Vistula River, Warsaw, PolandThe same dredge drag head and the suction pipe.
The dredge drag head is a steel structure that is connected to the dredger by a suction pipe. Supported by the gantries and by using hydraulic winches the dredge drag head and suction pipe are let down onto the sea bottom in order to suck a mixture of water and sand.
In order to dredge in waves, the suction pipe is suspended from special davits, which operate with heave compensation to ensure that the drag head nozzles stay in contact with the sea bed. The control of mixture of water and sand is done by a so-called dredge drag head visor. The visor controls the amount of water that enters along with the sand. In some cases this visor is hydraulically controlled.
To cut the sea bed, the dredge drag head is equipped with replaceable teeth and water jet nozzles. The nozzles are placed at the front of the dredge drag head and used to cut the sand at the sea bed vertically, while the replaceable teeth are placed at the back to cut horizontally.
A slurry pipeline is a specially engineered pipeline used to move ores, such as coal or iron, or mining waste, called tailings, over long distances. A mixture of the ore concentrate and water, called slurry, is pumped to its destination and the water is filtered out. Due to the abrasive properties of slurry, the pipelines can be lined with high-density polyethylene (HDPE), or manufactured completely from HDPE Pipe, although this requires a very thick pipe wall. Slurry pipelines are used as an alternative to railroad transportation when mines are located in remote, inaccessible areas.
Dredging is the operation of excavating material from a water environment for the purpose of improving existing water features; reshaping land and water features to alter drainage, navigability, and commercial use; construct dams, dikes, and other controls for streams and shorelines; and to recover valuable mineral deposits or marine life having commercial value. In all but a few situations the excavation is undertaken by a specialist floating plant, known as a dredger. Dredging is carried out in many different locations and for many different purposes, but the main objectives are usually to recover material of value or use, or to create a greater depth of water. All dredges can generally be classified as suction or mechanical.
A steam injector is typically used to deliver cold water to a boiler against its own pressure, using its own live or exhaust steam, replacing any mechanical pump. When first developed, its operation was intriguing because it seemed paradoxical, almost like perpetual motion, but it was later explained using thermodynamics. Other types of injector may use other pressurised motive fluids such as air.
This is a glossary of firefighting equipment.
An airlift is device based on a pipe, used in nautical archaeology to suck small objects, sand and mud from the sea bed and to transport the resulting debris upwards and away from its source. It is sometimes called a suction dredge. A water dredge or water eductor may be used for the same purpose.
An airlift pump is a pump that has low suction and moderate discharge of liquid and entrained solids. The pump injects compressed air at the bottom of the discharge pipe which is immersed in the liquid. The compressed air mixes with the liquid causing the air-water mixture to be less dense than the rest of the liquid around it and therefore is displaced upwards through the discharge pipe by the surrounding liquid of higher density. Solids may be entrained in the flow and if small enough to fit through the pipe, will be discharged with the rest of the flow at a shallower depth or above the surface. Airlift pumps are widely used in aquaculture to pump, circulate and aerate water in closed, recirculating systems and ponds. Other applications include dredging, underwater archaeology, salvage operations and collection of scientific specimens.
Rainbowing is the process in which a dredging ship propels sand that has been claimed from the ocean floor in a high arc to a particular location. This is used for multiple purposes, ranging from building up a beach to prevent erosion to constructing new islands. The name is derived from the appearance of the arc, which closely resembles a brown-colored rainbow.
The Underfall Yard is a historic boatyard on Spike Island serving Bristol Harbour, the harbour in the city of Bristol, England.
A fishing dredge, also known as a scallop dredge or oyster dredge, is a kind of dredge which is towed along the bottom of the sea by a fishing boat in order to collect a targeted edible bottom-dwelling species. The gear is used to fish for scallops, oysters and other species of clams, crabs, and sea cucumber. The dredge is then winched up into the boat and emptied. Dredges are also used in connection with the work of the naturalist in marine biology, notably on the Challenger Expedition.
Queen of the Netherlands is a Dutch Trailing suction hopper dredger ship constructed in 1998. After lengthening in 2009, she was the largest and most powerful dredger in the world. The vessel has been used in high-profile salvage and dredging operations including the investigation into the Swissair Flight 111 crash and in the Port Phillip Channel Deepening Project. It has been called "the world's largest floating vacuum cleaner".
Antioch Dunes National Wildlife Refuge is a sensitive sand dune habitat located near the city of Antioch, California on the south shore of the San Joaquin River-Stockton Deepwater Shipping Channel. It serves as a refuge for three endangered species of plants and insects, and is closed to the public except for tours and events supervised by Refuge staff. The Refuge was established in 1980. It is managed by the U.S. Fish and Wildlife Service.
A suction excavator or vacuum excavator is a construction vehicle that removes materials from a hole on land, or removes heavy debris on land.
The TSHD Shoalway is a trailing suction hopper dredger, owned and operated by Royal Boskalis Westminster, originally intended for the British market and built in 2010.
Dredging, Environmental and Marine Engineering NV (DEME) is an international group of specialised companies in the field of capital and maintenance dredging, land reclamation, port infrastructure development, offshore related services for the oil & gas industry, farshore windfarm installation, environmental remediation a.o. The group is based in Zwijndrecht, Belgium, and has current operations on the five continents. The roots of the group date back to the mid 19th century. DEME is committed to the practice of sustainable development. In 2009, the Flemish government agency Flanders Investment and Trade awarded the Export Lion 2009 to DEME for what was called its 'sustainable strategy of internationalization' and 'the many prestigious assignments carried out worldwide'. In a survey by temporary employment company Randstad Holding of 12,000 Belgians in early 2010 DEME was proclaimed one of the most attractive employers in Belgium.
A Slice of Reality is a work of modern art by Richard Wilson sitting by the Millennium Dome on the north-western bank of the Greenwich Peninsula. It consists of a 9-metre (30 ft) sliced vertical section through the former 800-ton 60-metre (200 ft) sand dredger Arco Trent and exposes portions of the former living quarters of the vessel to the elements.
A trailing suction hopper dredger is a ship that has a full sailing capacity used to maintain navigable waterways, deepening the maritime canals that are threatened to become silted, to construct new land elsewhere or to replace sand eroded by storms or wave action on the beaches. This is made possible by large powerful pumps and engines able to suck sand, clay, silt and gravel.
Dredge Turning Gland is a Trailing Suction Hopper Dredger component.
The dredge suction mouth is a Cutter Suction Dredger component positioned behind the cutter head of a CSD during extraction of non-cohesive material from the sea bottom.
The dredge valve is a component of a Cutter Suction Dredge or a Trailing Suction Hopper Dredger that is used control the flow of water and sand in the suction and discharge pipes of one of these types of dredgers.
The TSHD Sospan Dau is a Dutch trailing suction hopper dredger owned by Sosban BV. The vessel has worked on dredging projects, including offshore aggregates, port maintenance, land reclamation, coastal defense and beach replenishment. The name Sospan Dau is Welsh and originates from Sosban Fach and Llanelli's tin plating industry, Sospan being the Welsh for Saucepan and Dau being Welsh for Two as the ship is a successor to the original Sospan.
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