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56-402: Dredging is the excavation of material from a water environment. Possible reasons for dredging include improving existing water features ; reshaping land and water features to alter drainage , navigability , and commercial use; constructing dams , dikes , and other controls for streams and shorelines; and recovering valuable mineral deposits or marine life having commercial value. In all but

112-401: 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. 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

168-867: A highway , clay might be excavated for use in brick -making, gravel to be used for making concrete , etc. In some cases, the borrow pits may become filled with ground water , forming recreational areas or sustainable wildlife habitats (one such example is the Merton Borrow Pit, near Oxford in central England , excavated to provide materials for the nearby M40 motorway ). In other cases, borrow pits may be used for landfill and waste disposal . Borrow pits are common archaeological features in Waikato , where sand and gravel were dug to mix with clay topsoils to improve their drainage and friability, to suit growth of kūmara and taro , brought by Māori from tropical islands. A regional variation of this

224-485: A capacity of 6,000 cubic metres per hour (59,000 cu ft/ks). An even larger dredger, retired in 1980, was the U.S. Army Corps of Engineers Essayons , which was 525.17 feet (160.07 m) long. The Mallard II , a clamshell dredger that maintains levees in San Francisco Bay , has operated continuously since being built in 1936. Dredgers are often equipped with dredge monitoring software to help

280-471: A construction company specialised in civil works and maritime construction. It was only in 1951 that the company entered into the dredging business. Recently it has forayed into offshore wind business and have been successful in securing major European wind energy projects. At the end of 2022, Jan De Nul had 7178 employees and a yearly turnover of 2.5 billion euro. Other major dredging companies are Dutch companies Royal Boskalis Westminster and Van Oord , and

336-438: 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. 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

392-566: A few situations the excavation is undertaken by a specialist floating plant , known as a dredger. Usually the main objectives of dredging is to recover material of value, or to create a greater depth of water. Dredging systems can either be shore-based, brought to a location based on barges , or built into purpose-built vessels. Dredging can have environmental impacts: it can disturb marine sediments , leading to both short- and long-term water pollution , damage or destroy seabed ecosystems , and can release legacy human-sourced toxins captured in

448-482: 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. 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

504-494: A process known as dewatering. Current dewatering techniques employ either centrifuges, geotube containers, large textile based filters or polymer flocculant /congealant based apparatus. 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. Similarly, many groups (most notable in east Asia) are performing research towards utilizing dewatered sediments for

560-410: A shipping channel through coral reefs . 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 . 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

616-557: A wild boar in the arms of one of the skeletons. As human technology advanced, digging began to be used for agriculture , mining , and in earthworks , and new techniques and technologies were developed to suit these purposes. In construction and civil engineering , a borrow pit , also known as a sand box, is an area where material (usually soil , gravel or sand ) has been dug for use at another location. Borrow pits can be found close to many major construction projects. For example, soil might be excavated to fill an embankment for

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672-755: A wooden handle. Because digging is a cutting process, particularly where the soil being dug contains plant roots , digging is aided by the shovel being sharpened. Historically, manual shoveling (often in combination with picking ) was the chief means of excavation in construction, mining , and quarrying , and digging projects employed large numbers of people. After the Industrial Revolution , mechanization via steam shovels and later hydraulic equipment ( excavators such as backhoes and loaders ) gradually replaced most manual shoveling; however, individual homeowners still often find reasons to engage in manual digging during smaller-scale projects around

728-582: Is a Belgian family-owned company, with the financial headquarters in Luxembourg , that provides services relating to the construction and maintenance of maritime infrastructure on an international basis. Its main focus is dredging (including other forms of marine engineering), which accounts for 85% of its turnover. Other areas include civil engineering and environmental technology. Founded in 1938, in Hofstade near Aalst, Belgium , Jan De Nul started as

784-524: 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 was the oldest operational steam vessel in Britain, was of this type. This is an early type of dredger which was formerly used in shallow water in the Netherlands. It

840-451: Is a measure of the material to be excavated (dug) with conventional excavation equipment such as a bulldozer with rippers , backhoe , scraper and other grading equipment. Materials that cannot be excavated with conventional excavation equipment are said to be non- rippable . Such material typically requires pre- blasting or use of percussion hammers or chisels to facilitate excavation. The excavatability or rippability of earth materials

896-421: Is evaluated typically by a geophysicist , engineering geologist , or geotechnical engineer . The rippability of an earth ( rock ) material is a measure of its ability to be excavated with conventional excavation equipment. A material may be classified as rippable, marginally rippable or non-rippable. The rippability of a material is often evaluated by an engineering geologist and/or geophysicist utilizing

952-827: Is forbidden unless authorized by a permit issued by the Army Corps of Engineers . Due to potential environmental impacts, dredging is often restricted to licensed areas, with vessel activity monitored closely using automatic GPS systems. 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 Notable dredging companies in North America Notable dredging companies in South Asia Digging Many kinds of animals engage in digging, either as part of burrowing behavior or to search for food or water under

1008-423: Is mainly used in harbours and other shallow water. 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. This

1064-477: Is termed " barrow pit " in the western United States (especially the Rocky Mountains). The localism—sometimes pronounced "borrer pit"—describes the ditch along a roadway. These ditches were excavated to provide the fill to level and crown the roadway and subsequently provided drainage for the road. An excavation lake (also a flooded gravel pit ) is an artificial lake , which usually has its origins in

1120-409: 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. As of 2024,

1176-485: The Leiv Eriksson are: 46,000 cubic metre hopper and a design dredging depth of 155 m. Next largest is HAM 318 ( Van Oord ) with its 37,293 cubic metre hopper and a maximum dredging depth of 101 m. 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

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1232-777: The Manifa Field Causeway and Island Project in Saudi Arabia, the Palm Jebel Ali artificial island in Dubai, and the adjacent Dubai Waterfront . The Takoradi Harbour expansion project in Ghana . In 2020-21 Jan De Nul Group installs a power inter-connector cable over a distance of 135 km and up to 1 km deep sea, connecting Crete island with mainland Greece. In April 2009, the Jan De Nul vessel "Pompei"

1288-481: The Nile were channelled and wharfs built at the time of the pyramids (4000 BC), there was extensive harbour building in the eastern Mediterranean from 1000 BC and the disturbed sediment layers gives evidence of dredging. At Marseille , dredging phases are recorded from the third century BC onwards, the most extensive during the first century AD. The remains of three dredging boats have been unearthed; they were abandoned at

1344-419: The seismic refraction equipment (see refraction ). Rippability studies can involve the performance of seismic refraction traverses, the drilling of borings with an air percussion drill rig, the excavation of test trenches with a bulldozer with rippers or backhoe, and by geologic mapping. Cave-in of an excavation is the detachment of the mass of soil in the side of the trench and its displacement into

1400-607: The Belgian DEME . Jan De Nul was voted the most attractive employer in Belgium in 2008 and 2009. Jan De Nul has a fleet of 75 vessels, including 14 cutter suction dredgers , 28 trailing suction hopper dredgers , 20 split barges , 6 backhoe dredgers , 1 oil recovery vessel, 5 rock installation vessels and one cable installation vessel under construction. This includes the Cristobal Colon , launched in 2008, and

1456-529: The beds of streams. During the renaissance Leonardo da Vinci drew a design for a drag dredger. Dredging machines have been used during the construction of the Suez Canal from the late 1800s to present day expansions and maintenance. The completion of the Panama Canal in 1914, the most expensive U.S. engineering project at the time, relied extensively on dredging. These operate by sucking through

1512-619: The bottom of the harbour during the first and second centuries AD. The Banu Musa brothers during the Muslim Golden Age in while working at the Bayt-Al-Hikmah (house of wisdom) in Baghdad, designed an original invention in their book named ‘ Book of Ingenious Devices ’, a grab machine that does not appear in any earlier Greek works. The grab they described was used to extract objects from underwater, and recover objects from

1568-497: The case of the lakes in the Attenborough Nature Reserve . Although humans are capable of digging in sand and soil using their bare hands, digging is often more easily accomplished with tools. The most basic tool for digging is the shovel . In neolithic times and earlier, a large animal's scapula (shoulder blade) was often used as a crude shovel. In modern times, shovels are typically made of metal, with

1624-601: The construction industry. Dredging is a four-part process: loosening the material, bringing the material to the surface (together extraction), transportation and disposal. The extract can be disposed of locally or transported by barge or in a liquid suspension in pipelines. Disposal can be to infill sites, or the material can be used constructively to replenish eroded sand that has been lost to coastal erosion , or constructively create sea-walls, building land or whole new landforms such as viable islands in coral atolls . Ancient authors refer to harbour dredging. The seven arms of

1680-454: The dead prevents diseases associated with the presence of corpses, and prevents scavengers and other predators from being attracted. The earliest undisputed human burial discovered so far dates back 100,000 years. Human skeletal remains stained with red ochre were discovered in the Skhul cave at Qafzeh , Israel. A variety of grave goods were present at the site, including the mandible of

1736-795: The dead. There are a wide variety of reasons for which humans dig holes , trenches , and other subsurface structures. It has long been observed that humans have a seemingly instinctive desire to dig holes in the ground, manifesting in childhood . Like other animals, humans dig in the ground to find food and water. Wood-lined water wells are known from the early Neolithic Linear Pottery culture , for example in Kückhoven (an outlying centre of Erkelenz ), dated 5090 BC and Eythra , dated 5200 BC in Schletz (an outlying centre of Asparn an der Zaya ) in Austria . Humans are unique among animals in

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1792-493: The dredge continues its work. 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. When contaminated (toxic) sediments are to be removed, or large volume inland disposal sites are unavailable, dredge slurries are reduced to dry solids via

1848-481: 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. 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

1904-425: The dredged materials, but some dredges empty their hoppers by splitting the two-halves of their hulls on large 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

1960-556: The environment, including the following: The nature of dredging operations and possible environmental impacts requires that the activity often be closely regulated and requires comprehensive regional environmental impact assessments alongside continuous monitoring. For example, in the U.S., the Clean Water Act requires that any discharge of dredged or fill materials into "waters of the United States," including wetlands,

2016-413: The excavation of gravel or sand for construction materials or in some other kind of surface mining . In many cases, the excavation holes are landscaped according to the land restoration required by law. Because the excavation reached a point below the water table , lakes form naturally. Less frequently, excavation lakes are intentionally made, especially as recreation areas . In Germany and Austria

2072-525: 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. Dredging can be destructive to the seabed and some scallop dredging has been replaced by collecting via scuba diving . As of June 2018, the largest dredger in Asia is MV  Tian Kun Hao , a 140-metre (460 ft) long dredger constructed in China, with

2128-400: The hole, which represents a hazard to the person inside. Cave-ins are considered the largest risk when working within trenches. Cave-ins can be caused by a combination of pressure on soil, vibration from equipment, and excessive loads. Several techniques are used to minimize the likelihood of cave-ins, including sloping, shoring and shielding . Jan De Nul Jan De Nul Group

2184-428: The home. Different methods of digging can also result in different excavation depth and force, potentially risking exposure or damage to subsurface pipelines and wiring. In the United States and Canada, homeowners and contractors are required to notify a utility-run call center before digging to ensure they do not strike buried utilities and infrastructure. The excavatability of an earth (rock and regolith ) material

2240-446: The hopper is filled with slurry , the dredger stops dredging and goes to a dump site and empties its hopper. 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

2296-401: The lakes are almost always used for fishing, since a fishery is created by law with every surface water. At some excavation lakes, beaches are added for swimming or other water sports , in particular boating, water skiing or windsurfing. To support these uses, large parking lots, changing areas, and eating areas are also set up. In some cases, the excavation lake serves as a nature reserve, as in

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2352-465: The material could well suit the building industry, or could be used for beach nourishment. Dredging can disturb aquatic ecosystems , often with adverse impacts. 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 . Dredging can have numerous significant impacts on

2408-399: 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. As of 2008 the largest trailing suction hopper dredgers in the world were Jan De Nul 's Cristobal Colon (launched 4 July 2008) and her sister ship Leiv Eriksson (launched 4 September 2009). Main design specifications for the Cristobal Colon and

2464-465: The most powerful cutter-suction dredger in the world is DEME 's Spartacus , which entered service in 2021. 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 1970s. These use the Venturi effect of a concentrated high-speed stream of water to pull

2520-425: The nearby water, together with bed material, into a pipe. 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 . It works by blowing air into the pipe, and that air, being lighter than water, rises inside the pipe, dragging water with it. Some bucket dredgers and grab dredgers are powerful enough to rip out coral to make

2576-900: The practice of burial of the dead . Intentional burial, particularly with grave goods , may be one of the earliest detectable forms of religious practice since, as Philip Lieberman suggests, it may signify a "concern for the dead that transcends daily life". Evidence suggests that the Neanderthals were the first human species to practice burial behavior and intentionally bury their dead, doing so in shallow graves along with stone tools and animal bones. Exemplary sites include Shanidar in Iraq, Kebara Cave in Israel and Krapina in Croatia. Some scholars, however, argue that these bodies may have been disposed of for secular reasons. Notably, burial of

2632-666: The production of concretes and construction block, although the high organic content (in many cases) of this material is a hindrance toward such ends. 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,

2688-479: 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. These dredgers use a chamber with inlets, out of which

2744-469: 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

2800-628: The sediment. These environmental impacts can reduce marine wildlife populations in some cases, contaminate sources of drinking water and interrupt economic activities such as fishing. Dredging is excavation carried out underwater or partially underwater, in shallow waters or ocean waters . It keeps waterways and ports navigable, and assists coastal protection, land reclamation and coastal redevelopment, by gathering up bottom sediments and transporting it elsewhere. Dredging can be done to recover materials of commercial value; these may be high value minerals or sediments such as sand and gravel that are used by

2856-490: The surface of the ground. Historically, humans have engaged in digging for both of these reasons, and for a variety of additional reasons, such as engaging in agriculture and gardening , searching for minerals , metals , and other raw materials such as during mining and quarrying , preparing for construction , making fortifications and irrigation , and also excavations in archaeology , searching for fossils and rocks in palaeontology and geology and burial of

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2912-425: 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. A snagboat is designed to remove big debris such as dead trees and parts of trees from North America waterways. 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

2968-704: The world are currently the Vitruvius, the Mimar Sinan, Postnik Yakovlev (Jan De Nul), the Samson (DEME), the Simson and the Goliath (Van Oord). 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

3024-547: The world's largest dredger with a capacity of 46,000 m³. It can dredge to a water depth of 155m. Joined by her near-sister ship Leiv Eiriksson in 2010, Jan De Nul has one of the world's largest, if not the largest, fleets of hopper dredgers. Major projects realised in part or whole by Jan De Nul include the Panama Canal expansion project , the Bridgetown Port enhancement project , the Port Botany expansion ,

3080-443: Was America's first steam-powered road vehicle. These are usually used to recover useful materials from the seabed. Many of them travel on continuous track . A unique variant is intended to walk on legs on the seabed. 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

3136-467: 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". 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

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