Dragado

"Dredge" vuelve a dirigir aquí. Para otros usos, consulte Dragado (desambiguación) .

"Dragas" vuelve a dirigir aquí. Para el municipio alemán, consulte Dreggers .

"Dragger" vuelve a dirigir aquí. Para el barco de pesca, consulte arrastrero de pesca .

Excavation of sediment, usually under water

Una draga de agarre

El dragado es la excavación de material de un entorno acuático. Las posibles razones para el dragado incluyen la mejora de las características del agua existentes; remodelar las características de la tierra y el agua para alterar el drenaje , la navegabilidad y el uso comercial; la construcción de presas , diques y otros controles para arroyos y costas; y recuperar valiosos depósitos minerales o vida marina con valor comercial. En casi todas las situaciones, la excavación la lleva a cabo una planta flotante especializada , conocida como draga.

El dragado se lleva a cabo en muchos lugares diferentes y con muchos propósitos diferentes, pero los principales objetivos suelen ser recuperar material de valor o uso, o crear una mayor profundidad de agua. ^{[1] Las} dragas se han clasificado como de succión o mecánicas. ^[1]

El dragado tiene impactos ambientales significativos: puede perturbar los sedimentos marinos, lo que lleva a la contaminación del agua a corto y largo plazo , destruye importantes ecosistemas del lecho marino y puede liberar toxinas de origen humano capturadas en el sedimento.

Descripción

El dragado es una excavación que se lleva a cabo bajo el agua o parcialmente bajo el agua, en aguas poco profundas o en aguas oceánicas . Mantiene navegables las vías fluviales y los puertos, y ayuda a la protección costera, la recuperación de tierras y la remodelación costera, al recolectar sedimentos del fondo y transportarlos a otros lugares. Se puede realizar un dragado para recuperar materiales de valor comercial; estos pueden ser minerales o sedimentos de alto valor, como arena y grava, que se utilizan en la industria de la construcción. ^[2]

El dragado es un proceso de cuatro partes: aflojar el material, llevar el material a la superficie (extracción conjunta), transporte y eliminación. ^[1]

El extracto puede eliminarse localmente o transportarse en barcaza o en suspensión líquida en tuberías. La eliminación puede ser para rellenar sitios, o el material se puede usar de manera constructiva para reponer la arena erosionada que se ha perdido por la erosión costera , o crear de manera constructiva diques, terrenos de construcción ^[1] o accidentes geográficos completamente nuevos como islas viables en atolones de coral . ^[3]

Historia

Los autores antiguos se refieren al dragado de puertos. Los siete brazos del Nilo fueron canalizados y los muelles construidos en la época de las pirámides (4000 a. C.), hubo una extensa construcción de puertos en el Mediterráneo oriental desde el 1000 a. C. y las capas de sedimentos alteradas dan evidencia de dragado. En Marsella, las fases de dragado se registran a partir del siglo III a.C., las más extensas durante el siglo I d.C. Se han desenterrado los restos de tres barcos de dragado; fueron abandonados en el fondo del puerto durante los siglos I y II d.C. ^[4]

Durante el renacimiento, Leonardo da Vinci dibujó un diseño para una draga de arrastre.

Las máquinas de dragado se han utilizado durante la construcción del Canal de Suez desde finales del siglo XIX hasta las ampliaciones y el mantenimiento de la actualidad. ^[5] La finalización del Canal de Panamá en 1914, el proyecto de ingeniería estadounidense más caro en ese momento, se basó en gran medida en el dragado. ^[6]

Reconstrucción del lodo de Leonardo da Vinci ( Manuscrito E, folio 75 v. )

Reconstrucción del arrastre de barro

Propósitos

• Dragado de capital : dragado realizado para crear un nuevo puerto , atracadero o vía fluvial , o para profundizar las instalaciones existentes con el fin de permitir el acceso de buques más grandes. Debido a que las obras capitales generalmente involucran material duro o trabajos de gran volumen, el trabajo generalmente se realiza utilizando una draga de succión con cortador o una draga de tolva de succión de arrastre grande; pero para trabajos en roca, se puede utilizar perforación y voladura junto con excavación mecánica.
• Recuperación de tierras : dragado para extraer arena, arcilla o roca del lecho marino y usarlo para construir nuevas tierras en otros lugares. Por lo general, esto se realiza mediante una draga de succión con cortador o una draga de tolva de succión de arrastre. El material también se puede utilizar para el control de inundaciones o erosión .
• Mantenimiento : dragado para profundizar o mantener las vías navegables o canales que están amenazados de sedimentar con el paso del tiempo, debido a la arena y el lodo sedimentado , posiblemente haciéndolos demasiado poco profundos para la navegación. Esto a menudo se lleva a cabo con una draga de tolva de succión en marcha. La mayor parte del dragado tiene este propósito y también se puede realizar para mantener la capacidad de retención de embalses o lagos.
• Materiales de recolección : dragado de sedimentos en busca de elementos como oro , diamantes u otras sustancias traza valiosas. Los aficionados examinan su material dragado para seleccionar elementos de valor potencial, similar al pasatiempo de la detección de metales .
• El dragado de pesca es una técnica para capturar ciertas especies de almejas y cangrejos comestibles. En Luisiana y otros estados de Estados Unidos, con estuarios de agua salada que pueden albergar criaderos de ostras en el fondo, las ostras se crían y cosechan. Una pala de metal rectangular pesada se remolca a la popa de un barco en movimiento con una brida de cadena unida a un cable. Esto se arrastra por el fondo recogiendo ostras. Se sube periódicamente a bordo con un cabrestante y la captura se clasifica y embolsa para su envío. ^[7]
• Preparatorio : trabajos de dragado y excavación para futuros puentes , muelles o muelles o muelles , esto suele ser para construir los cimientos .
• Materiales de construcción ganadores : dragado de arena y grava de áreas con licencia costa afuera para uso en la industria de la construcción, principalmente para uso en concreto. Esta industria muy especializada se centra en el noroeste de Europa, utiliza dragas de tolva de succión en marcha especializadas que descargan automáticamente la carga seca en tierra. Los lechos de ríos antiguos terrestres también se pueden procesar de esta manera.
• Remediación de contaminantes : para recuperar áreas afectadas por derrames químicos, oleadas de aguas pluviales (con escorrentía urbana) y otras contaminaciones del suelo, incluido el limo de lodos de aguas residuales y de materia en descomposición, como plantas marchitas. La eliminación se convierte en un factor proporcionalmente importante en estas operaciones.
• Prevención de inundaciones : el dragado aumenta la profundidad del canal y, por lo tanto, aumenta la capacidad de un canal para transportar agua.

Otro

• Nutrición de la playa : se trata de extraer arena en alta mar y colocarla en una playa para reemplazar la arena erosionada por las tormentas o la acción de las olas. Esto potencia la función recreativa y protectora de la playa, que también se ve erosionada por la actividad humana. Por lo general, esto se realiza mediante una draga de succión con cortador o una draga de tolva de succión de arrastre. ^{[ cita requerida ]}
• Extracción de turba : dragado polos o dragar lances se utilizaron en la parte posterior de pequeñas embarcaciones de dragado manualmente los lechos de turba - Moor cursos de agua. La turba extraída se utilizó como combustible. Esta tradición es ahora más o menos obsoleta. Las herramientas ahora han cambiado significativamente. ^{[ cita requerida ]}
• Eliminación de basura y escombros : a menudo se realiza en combinación con el dragado de mantenimiento, este proceso elimina la materia no natural del fondo de los ríos, canales y puertos.Las agencias de aplicación de la ley a veces necesitan usar un 'arrastre' para recuperar evidencia o cadáveres debajo del agua.
• Anti-eutrofización : una especie de remediación de contaminantes, el dragado es una opción costosa para la remediación de masas de agua eutrofizadas (o desoxigenadas); una de las causas es como se mencionó anteriormente, los lodos de depuradora . Sin embargo, como los niveles de fósforo artificialmente elevados en el sedimento agravan el proceso de eutrofización, la remoción controlada de sedimentos es ocasionalmente la única opción para la recuperación de aguas tranquilas. ^{[ cita requerida ]}
• Minería de los fondos marinos : es un posible uso futuro, recuperandonódulos de minerales metálicos naturalesde las vaguadas más profundas del mar. ^[7]

Tipos

Dragas de succión

The dredge drag head of a suction dredge barge on the Vistula River, Warsaw, Poland

The Geopotes 14 lifting its boom on a canal in The Netherlands. (gēopotēs is Greek for "that which drinks earth")

For suction-type excavation out of water, see Suction excavator.

These operate by sucking through a long tube like some vacuum cleaners but on a larger scale.

A plain suction dredger has no tool at the end of the suction pipe to disturb the material.

Trailing suction

A trailing suction hopper dredger (TSHD) trails its suction pipe when working. The pipe, which is fitted with a dredge drag head, loads the dredge spoil into one or more hoppers in the vessel. When the hoppers are full, the TSHD sails to a disposal area and either dumps the material through doors in the hull or pumps the material out of the hoppers. Some dredges also self-offload using drag buckets and conveyors.^{[citation needed]}

As of 2008^[update] the largest trailing suction hopper dredgers in the world were Jan De Nul's Cristobal Colon (launched 4 July 2008^[8]) and her sister ship Leiv Eriksson (launched 4 September 2009^[9]). Main design specs for the Cristobal Colon and the Leiv Eriksson are: 46,000 cubic metre hopper and a design dredging depth of 155 m.^[10] Next largest is HAM 318 (Van Oord) with its 37,293 cubic metre hopper and a maximum dredging depth of 101 m.

Cutter-suction

A cutter-suction dredger's (CSD) suction tube has a cutting mechanism at the suction inlet. The cutting mechanism loosens the bed material and transports it to the suction mouth. The dredged material is usually sucked up by a wear-resistant centrifugal pump and discharged either through a pipe line or to a barge. Cutter-suction dredgers are most often used in geological areas consisting of hard surface materials (for example gravel deposits or surface bedrock) where a standard suction dredger would be ineffective. They can, if sufficiently powerful, be used instead of underwater blasting.^[11]

As of 2018, the most powerful cutter-suction dredger in the world is DEME's Spartacus, which is scheduled to enter service in 2019.^[12]

Auger suction

The auger dredge system functions like a cutter suction dredger, but the cutting tool is a rotating Archimedean screw set at right angles to the suction pipe. Mud Cat invented the auger dredge in the 1970's.^[13]

Jet-lift

These use the Venturi effect of a concentrated high-speed stream of water to pull the nearby water, together with bed material, into a pipe.

Air-lift

An airlift is a type of small suction dredge. It is sometimes used like other dredges. At other times, an airlift is handheld underwater by a diver.^[14] It works by blowing air into the pipe, and that air, being lighter than water, rises inside the pipe, dragging water with it.

Mechanical dredgers

Bucket dredging

Some bucket dredgers and grab dredgers are powerful enough to rip out coral to make a shipping channel through coral reefs.^[15]

Old Dutch bucket dredging vessel "Hollandsch Diep 4"

Bucket dredgers

A bucket dredger is equipped with a bucket dredge, which is a device that picks up sediment by mechanical means, often with many circulating buckets attached to a wheel or chain.^[15]

Grab dredgers

Grab (clamshell) dredging in process in Port Canaveral, Florida

A grab dredger picks up seabed material with a clam shell bucket, which hangs from an onboard crane or a crane barge, or is carried by a hydraulic arm, or is mounted like on a dragline. This technique is often used in excavation of bay mud. Most of these dredges are crane barges with spuds, steel piles that can be lowered and raised to position the dredge.^[15]

Backhoe/dipper dredgers

A backhoe/dipper dredger has a backhoe like on some excavators. A crude but usable backhoe dredger can be made by mounting a land-type backhoe excavator on a pontoon. The six largest backhoe dredgers in the world are currently the Vitruvius, the Mimar Sinan, Postnik Yakovlev (Jan De Nul), the Samson (DEME), the Simson and the Goliath (Van Oord).^{[citation needed]} They featured barge-mounted excavators. Small backhoe dredgers can be track-mounted and work from the bank of ditches. A backhoe dredger is equipped with a half-open shell. The shell is filled moving towards the machine. Usually dredged material is loaded in barges. This machine is mainly used in harbours and other shallow water.^[15]

Excavator dredge attachments

The excavator dredge attachment uses the characteristics of cutter-suction dredgers, consisting of cutter heads and a suction pump for transferring material. These hydraulic attachments mount onto the boom arm of an excavator allowing an operator to maneuver the attachment along the shoreline and in shallow water for dredging.^[16]

Bed leveler

Steam dredger Bertha, built 1844, on a demonstration run in 1982

This is a bar or blade which is pulled over the seabed behind any suitable ship or boat. It has an effect similar to that of a bulldozer on land. The chain-operated steam dredger Bertha, built in 1844 to a design by Brunel and as of 2009^[update] was the oldest operational steam vessel in Britain, was of this type.^[17]

Krabbelaar

This is an early type of dredger which was formerly used in shallow water in the Netherlands. It was a flat-bottomed boat with spikes sticking out of its bottom. As tide current pulled the boat, the spikes scraped seabed material loose, and the tide current washed the material away, hopefully to deeper water. Krabbelaar is the Dutch word for "scratcher".

Water injection

A water injection dredger uses a small jet to inject water under low pressure (to prevent the sediment from exploding into the surrounding waters) into the seabed to bring the sediment in suspension, which then becomes a turbidity current, which flows away down slope, is moved by a second burst of water from the WID or is carried away in natural currents. Water injection results in a lot of sediment in the water which makes measurement with most hydrographic equipment (for instance: singlebeam echosounders) difficult.

Pneumatic

These dredgers use a chamber with inlets, out of which the water is pumped with the inlets closed. It is usually suspended from a crane on land or from a small pontoon or barge. Its effectiveness depends on depth pressure.^{[citation needed]}

Snagboat

Main article: Snagboat

A snagboat is designed to remove big debris such as dead trees and parts of trees from North America waterways.^{[citation needed]}

Amphibious

Some of these are any of the above types of dredger, which can operate normally, or by extending legs, also known as spuds, so it stands on the seabed with its hull out of the water. Some forms can go on land.

Some of these are land-type backhoe excavators whose wheels are on long hinged legs so it can drive into shallow water and keep its cab out of water. Some of these may not have a floatable hull and, if so, cannot work in deep water. Oliver Evans (1755–1819) in 1804 invented the Oruktor Amphibolos, an amphibious dredger which was America's first steam-powered road vehicle.^[18]

Submersible

These are usually used to recover useful materials from the seabed. Many of them travel on continuous track. A unique variant^[19] is intended to walk on legs on the seabed.^[20]

Fishing

Main article: Fishing dredge

Dredge haul including live clams and empty shells

Fishing dredges are used to collect various species of clams, scallops, oysters or mussels from the seabed. Some dredges are also designed to catch crabs, sea urchins, sea cucumbers, and conch. These dredges have the form of a scoop made of chain mesh, and are towed by a fishing boat. Clam-specific dredges can utilize hydraulic injection to target deeper into the sand.^[21] Dredging can be destructive to the seabed and some scallop dredging has been replaced by collecting via scuba diving.^[22]

Notable individual dredgers

A large Asian dredger

As of June 2018, the largest dredger in Asia is "MV Tian Kun Hao", a 140 metres long dredger constructed in China, with a capacity of 6,000 cubic meters per hour.^[23]

Dredge monitoring software

Dredgers are often equipped with dredge monitoring software to help the dredge operator position the dredger and monitor the current dredge level. The monitoring software often uses Real Time Kinematic satellite navigation to accurately record where the machine has been operating and to what depth the machine has dredged to.^{[citation needed]}

Transportation and disposal of materials

In a "hopper dredger", the dredged materials end up in a large onboard hold called a "hopper." A suction hopper dredger is usually used for maintenance dredging. A hopper dredge usually has doors in its bottom to empty the dredged materials, but some dredges empty their hoppers by splitting the two-halves of their hulls on giant hydraulic hinges. Either way, as the vessel dredges, excess water in the dredged materials is spilled off as the heavier solids settle to the bottom of the hopper. This excess water is returned to the sea to reduce weight and increase the amount of solid material (or slurry) that can be carried in one load. When the hopper is filled with slurry, the dredger stops dredging and goes to a dump site and empties its hopper.^{[citation needed]}

Some hopper dredges are designed so they can also be emptied from above using pumps if dump sites are unavailable or if the dredge material is contaminated. Sometimes the slurry of dredgings and water is pumped straight into pipes which deposit it on nearby land. These pipes are also commonly known as dredge hoses, too. There are a few different types of dredge hoses that differ in terms of working pressure, float-ability, armored or not etc. Suction hoses, discharge armored hoses and self-floating hoses are some of the popular types engineered for transporting and discharging dredge materials.^[24] Some even had the pipes or hoses customised to exact dredging needs etc. Other times, it is pumped into barges (also called scows), which deposit it elsewhere while the dredge continues its work.^{[citation needed]}

A number of vessels, notably in the UK and NW Europe de-water the hopper to dry the cargo to enable it to be discharged onto a quayside 'dry'. This is achieved principally using self discharge bucket wheel, drag scraper or excavator via conveyor systems.^{[citation needed]}

When contaminated (toxic) sediments are to be removed, or large volume inland disposal sites are unavailable, dredge slurries are reduced to dry solids via a process known as dewatering. Current dewatering techniques employ either centrifuges, Geotube containers, large textile based filters or polymer flocculant/congealant based apparatus.^{[citation needed]}

In many projects, slurry dewatering is performed in large inland settling pits, although this is becoming less and less common as mechanical dewatering techniques continue to improve.^{[citation needed]}

Similarly, many groups (most notable in east Asia) are performing research towards utilizing dewatered sediments for the production of concretes and construction block, although the high organic content (in many cases) of this material is a hindrance toward such ends.^{[citation needed]}

The proper management of contaminated sediments is a modern-day issue of significant concern. Because of a variety of maintenance activities, thousands of tonnes of contaminated sediment are dredged worldwide from commercial ports and other aquatic areas at high level of industrialization. Dredged material can be reused after appropriate decontamination. A variety of processes has been proposed and tested at different scales of application (technologies for environmental remediation). Once decontaminated, the material could well suit the building industry, or could be used for beach nourishment.^[25]

Environmental impacts

Dredging can create disturbance to aquatic ecosystems, often with adverse impacts.^[26][27] In addition, dredge spoils may contain toxic chemicals that may have an adverse effect on the disposal area; furthermore, the process of dredging often dislodges chemicals residing in benthic substrates and injects them into the water column.^{[citation needed]}

The activity of dredging can create the following principal impacts to the environment:

• Release of toxic chemicals (including heavy metals and PCB) from bottom sediments into the water column.^[28]
• Collection of heavy metals lead left by fishing, bullets, 98% mercury reclaimed [natural occurring and left over from gold rush era].^[29]
• Short term increases in turbidity, which can affect aquatic species metabolism and interfere with spawning.^[26] Suction dredging activity is allowed only during non-spawning time frames set by fish and game (in-water work periods).^[30]
• Secondary impacts to marsh productivity from sedimentation.^[31]
• Tertiary impacts to avifauna which may prey upon contaminated aquatic organisms.^[31]
• Secondary impacts to aquatic and benthic organisms' metabolism and mortality^[32]
• Possible contamination of dredge spoils sites^[28][33]
• Changes to the topography by the creation of "spoil islands" from the accumulated spoil.^[34]
• Releases toxic compound Tributyltin, a popular biocide used in anti-fouling paint banned in 2008, back into the water.^[35]

The nature of dredging operations and possible environmental impacts cause the industry to be closely regulated and a requirement for comprehensive regional environmental impact assessments with continuous monitoring.^[31] The U.S. Clean Water Act requires that any discharge of dredged or fill materials into "waters of the United States," including wetlands, is forbidden unless authorized by a permit issued by the Army Corps of Engineers.^[36] As a result of the potential impacts to the environment, dredging is restricted to licensed areas only with vessel activity monitored closely using automatic GPS systems.^[31]

Major dredging companies

According to a Rabobank outlook report in 2013, the largest dredging companies in the world are in order of size, based on dredging sales in 2012 ^[2]

• China Harbour Engineering (China)
• Jan De Nul (Belgium)
• DEME (Belgium)
• Royal Boskalis Westminster (Netherlands)
• Van Oord Dredging and Marine Contractors (Netherlands)
• National Marine Dredging Company (United Arab Emirates)
• Great Lakes Dredge & Dock Company (United States)

Notable dredging companies in North America:

• Manson Construction Co. (United States)

Images

• Grab (clamshell) dredge Njord of the Manson Construction Co. fleet in the Port of Oakland, California

• The excavator of a Yukon dredge.

• April Hamer at Lakes Entrance, Victoria Australia

• The Orisant a trailing suction dredger in the port of IJmuiden, Netherlands

• Grab dredging in Victoria Harbour, Hong Kong

• Alexander von Humboldt of the Jan De Nul fleet

• Sand mining

• HR Morris of the Manson Construction Co. fleet, a Cutter Suction Pipeline Dredge, working on Mission Bay, San Diego, California

• Dredge ship with barges on Neva bay in Saint Petersburg, Russia

• Top view of a suction dredger on the Nandu River, Hainan, China

• Cutterhead of dredge Bill Holman, Louisville, Kentucky, USA, Ohio River mile 607, July 2002

• Xcentric Ripper XR120 is a large jackup leg backhoe dredger

See also

• Dredge ball joint, connection between 2 pipes that are used to transport mixture of water and sand from a dredger to the discharging area
• Dredge drag head
• Navigability
• Peace in Africa (ship), a diamond-mining dredger
• Queen of the Netherlands (ship), a big dredger
• River engineering for inland dredging and other river management systems
• WT Preston, a snagboat

References

1. "EuDA - About dredging - Dredging". www.european-dredging.eu. Retrieved 3 July 2018.
2. "Dredging: Profit margins expected to remain fairly healthy until 2018" (PDF). 2013. Retrieved 26 March 2018.
3. "What is China's 'magic island-making' ship?". BBC News. 6 November 2017. Retrieved 4 July 2018.
4. Morhange, Christophe; Marriner, Nick; Carayon, Nicolas. "The eco-history of ancient Mediterranean harbours" (PDF). Retrieved 1 July 2018.
5. "New Suez Canal: A Dredging Triumph". The Maritime Executive. Retrieved 21 September 2019.
6. "Dredging Up the Past: The Panama Canal". U.S. Aqua Services. Retrieved 21 September 2019.
7. "EuDA - About dredging - Dredging - Reasons for Dredging". www.european-dredging.eu. Retrieved 3 July 2018.
8. "Jan de Nul's mega trailer Cristóbal Colón launched - Dredging News Online". Sandandgravel.com. 7 July 2008. Retrieved 14 June 2013.
9. "Keel-laying ceremony for Jan de Nul's Leiv Eiriksson held - Dredging News Online". Sandandgravel.com. 1 September 2008. Retrieved 14 June 2013.
10. "Jan De Nul Group". Jandenul.com. 7 June 2013. Retrieved 14 June 2013.
11. "DEME orders world's most powerful cutter suction dredge". Marine Log. 1 March 2017. Retrieved 13 November 2018.
12. "Keel laying signals start of world's most powerful CSD". Baird Maritime. 21 December 2017. Retrieved 13 November 2018.
13. http://www.mudcatdredge.com/our-history/
14. Robbins, R (2006). "USAP Surface-Supplied Diving". In Lang, MA; Smith, NE (eds.). Proceedings of Advanced Scientific Diving Workshop. Washington, DC: Smithsonian Institution. Retrieved 5 April 2013.
15. "Mechanical Dredger". www.european-dredging.eu. Retrieved 4 July 2018.
16. "Excavator Dredge Pumps". DAE Pumps. Retrieved 25 September 2020.
17. "Bertha". World of Boats. Eyemouth, Scotland: Eyemouth Marine Centre. Archived from the original on 4 June 2011. Retrieved 27 December 2009.
18. Evans, Harold; Buckland, Gail; Lefer, David (2006). They Made America: From the Steam Engine to the Search Engine: Two Centuries of Innovators. Boston, MA: Back Bay Books. ISBN 0-316-01385-4.
19. "National Institute of Oceanography, India". Archived from the original on 12 January 2009. Retrieved 14 June 2013.
20. "Concept of a mathematical model for prediction of major design parameters of a submersible dredger/miner" by Sritama Sarkar, Neil Bose, Mridul Sarkar, and Dan Walker, in "3rd Indian National Conference on Harbour and Ocean Engineering, National Institute of Oceanography", Dona Paula, Goa 403 004 India, 7–9 December 2004
21. Kristjan F. Olgeirsson (19 May 2015). "Fishing Gear 101: Dredges – The Bottom Scrapers". The Safina Center. Retrieved 21 September 2019.^{[clarification needed]}
22. Walker, Margaret (1991). "What price Tasmanian scallops? A report of morbidity and mortality associated with the scallop diving season in Tasmania 1990". South Pacific Underwater Medicine Society Journal. 21 (1). Retrieved 16 July 2013.
23. "Asia's largest dredging vessel completes first sea trial". Xinhua. 12 June 2018. Retrieved 13 June 2018.
24. "Dredging & Discharge: Dredge Hoses". Max Groups Marine. Retrieved 8 January 2019.
25. Fonti, V. "To remediate or to not remediate?". Atlas of Science.
26. Brodie, Jon. "Dredging set to swamp decades of Great Barrier Reef protection". The Conversation. Retrieved 21 September 2019.
27. Newell, R.C.; Seiderer, L.J.; Hitchcock, D.R. (1998). "The impact of dredging works in coastal waters: A review of the sensitivity to disturbance and subsequent recovery of biological resources on the sea bed" (PDF). Oceanography and Marine Biology: An Annual Review. 36: 127–178.
28. Bridges, T S., Gustavson, K. E., Schroeder, P., Ells, S. J., & Hayes, D. (2010). Dredging processes and remedy effectiveness: Relationship to the 4 Rs of environmental dredging. Integrated Environmental Assessment and Management, 6 (4), 619-630.
29. Walsh, Melissa. "Restoring Howards Bay: Legacy lead and other contaminants are targets of dredging and capping". Great Lakes Now. Retrieved 22 September 2019.
30. "Timing of dredging and disposal as a means of minimising maintenance dredging impacts". www.ukmarinesac.org.uk. Retrieved 22 September 2019.
31. "Monitoring Turbidity at Dredging Sites". Environmental Measurement Systems. Retrieved 22 September 2019.
32. Milman, Oliver (11 December 2013). "The facts about dredging". The Guardian. ISSN 0261-3077. Retrieved 21 September 2019.
33. Moore, Tony (7 January 2014). "Inquiry to probe Gladstone Harbour's leaking bund wall". Brisbane Times. Retrieved 22 September 2019.
34. "About the Spoil Island Project". Spoil Island Project. Retrieved 22 September 2019.
35. US EPA, OECA (15 December 2015). "Case Summary: Cleanup Settlement Addresses Contaminated Sediment Removal in Blair Waterway, Washington State". US EPA. Retrieved 22 September 2019.
36. Clean Water Act, 33 U.S.C. § 1311, 33 U.S.C. § 1362, 33 U.S.C. § 1344^{[citation needed]}

External links

Wikimedia Commons has media related to Dredging.

• Directory of Dredgers (a close to exhaustive private collection of dredger photographs)
• Dredging and Spoil Disposal Policy (from the Australian Government)
• The Art of Dredging (Knowledge sharing)
• International Association of Dredging Companies Knowledge centre
• World of Boats (EISCA) Collection ~ Isambard Kingdom Brunel's Bertha