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58-655: The Yuba Goldfields , also known as the Hammonton dredge field, is the largest gold dredge field in California. Located along the Yuba River approximately 6–12 miles (10–20 km) upstream of the town of Marysville , in Yuba County , the Hammonton dredge field was actively dredged for gold from 1904 to 1968. In total, more than one billion cubic yards (760 × 10 ^  m) of river sediment and lesser hydraulic mining debris

116-402: 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

174-482: 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

232-439: 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

290-567: 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

348-478: 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

406-573: A mining company extracting gravel from the goldfields. The remainder of the land is split between small private owners, the Bureau of Land Management , and the United States Army Corps of Engineers . The BLM land is free for the public to use for recreational purposes, but much of it is actually unreachable. Some of it can be accessed via boats on the river, but other access roads have been closed off by Western Aggregate. The parcel of land owned by

464-496: 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

522-513: A public road, and one mining company owner was arrested for threatening protestors with a handgun during the years-long dispute. In the Central Valley , the Yuba is one of two rivers where Chinook salmon spawn, and the only one that supports steelhead trout runs . Salmon die when they reach fresh water, and their carcasses pile up in the goldfields, where turkey vultures hope to scavenge. There

580-411: 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

638-407: A surface area of 815 acres (3.30 km ; 330 ha). The lake is unique in that it offers boat-in camping only. The 70,000-acre-foot (86,000,000 m ) Englebright Reservoir provides water-based recreational benefits to the region and provides 45,000 acre-feet (56,000,000 m ) of stored water-right capacity, which is released each year through dam operations to benefit fish downstream. Water

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696-517: Is a 280 ft (85 m) high variable radius concrete arch dam on the Yuba River in the Sacramento River Basin, located in Yuba and Nevada counties of California, United States. It was put into service in 1941 by the United States Army Corps of Engineers . The dam was constructed in 1941 for the primary purpose of trapping sediment derived from anticipated hydraulic mining operations in

754-515: 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

812-482: Is also diverted for regional domestic and agricultural uses. Hydroelectric generation from water stored behind Englebright produces about 294 million kilowatt hours of energy each year, or enough for the annual energy needs for 50,000 homes. A new flow bypass system was installed in 2006 by the Yuba County Water Agency and Mitchell Engineering so that river flow requirements can be met during shut-downs of

870-485: Is currently a movement to establish a nature reserve on the lower Yuba River, which would include portions of the Yuba Goldfields. However, sorting out the land issue could take years. Creating a reserve would also require a large amount of money, but the aggregate could cover much if not all of that. As of September 2016, discussions were still ongoing, with the latest proposal being a habitat restoration project led by

928-727: 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 Englebright Dam Englebright Dam

986-424: 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

1044-463: Is used primarily for recreation and hydropower. Englebright Lake is nestled in the scenic Sierra foothills east of Marysville. Constructed for the storage of hydraulic gold mining debris, Englebright Dam is a concrete arch structure. It spans 1,142 feet (348 m) across and is 260 feet (79 m) high. The dam is in the steep Yuba River gorge known as the Narrows, holding back a 9-mile-long (14 km) lake with

1102-410: 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,

1160-479: 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

1218-477: 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

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1276-759: The United States Fish and Wildlife Service . [REDACTED]  This article incorporates public domain material from websites or documents of the National Aeronautics and Space Administration . Dredge mining 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

1334-749: The Army Corps is technically public land, but it is also inaccessible and it is closed for recreation. Western Aggregate owns mining rights over much (but not all) of that property as a result of a purchase from a gold mining company in 1987 by its parent company Centex Construction, based in Texas. The Goldfields is the largest aggregate mine in the State of California, as well as one of only two dredge gold-mining operations in North America (as of 1989). The titles themselves are also under much dispute because mining has so shifted

1392-582: The Yuba River watershed. Hydraulic mining in the Sierra Nevada was halted in 1884 but resumed on a limited basis until the 1930s during the great depression under the California Debris Commission . Although no hydraulic mining in the upper Yuba River watershed resumed after the construction of the dam, the historical mine sites continued to contribute sediment to the river. Today, Englebright Lake

1450-520: 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

1508-600: 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

1566-605: 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

1624-435: The deposition of 10 to 40 feet (3 to 10 m) of hydraulic mining debris (slickens) in the area of the Hammonton dredge field, these slickens were considered uneconomical at the time (because they had already been processed for gold once), and the primary target of gold dredging was the native river sediments (alluvium) of the Yuba River. To that point, a vast majority of the more than one billion cubic yards of material dredged

1682-492: 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

1740-482: 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

1798-425: 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

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1856-543: 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,

1914-519: 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

1972-420: The goldfields, although the mining industry disputes this figure. The environmental damage caused by the dredgers is enormous. The top 150 feet (46 m) of many square miles was turned upside-down. The soil and the rocks were separated with the rocks stacked on top of the soil. The goldfields are the subject of an ongoing dispute as to land title and access. Much of the land is owned by Western Aggregate,

2030-488: The goldfields. The first Yuba-area miners panned for gold in stream beds in the valley, but within a decade large-scale industrial processes replaced solitary prospectors. Mining companies moved from the valley floor into the Sierra Nevada foothills, where miners blasted gravel hillsides with high-pressure jets of water—a process called hydraulic mining . After the miners extracted gold in long wooden sluices , they dumped

2088-447: 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

2146-545: The impurities having been filtered by the gravel. The Debris Commission also built both the Englebright Dam to the east and the Daguerre Point Dam west of the goldfields to trap debris caused by hydraulic mining. In the twentieth century, a series of mining companies reprocessed the tailings, extracting gold that was increasingly difficult to separate from the gravel. Even though the ore had already been processed, it

2204-491: The landscape of gravel as well as the river itself that it has become unclear as to what the property boundaries are. In response to the blocking of Hammonton Road, a county road, into the Yuba Goldfields, the Yuba Goldfields Access Coalition was formed in 1996 by local historian Chuck Smith and neighboring landowner William Calvert. Smith, along with Goldfields residents and 80 members of the community, spent

2262-469: 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

2320-460: 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

2378-532: The most active dredge fields in the state, with 14 gold dredges operating by 1908. Dredging to clear the active channel of the Yuba River was done periodically, but a vast majority of dredging was done away from the active channel, with the purpose of recovering gold from the river sediments. This off-channel gold dredging accounts for the vast majority of land dredged, and is what created the linear gravel piles, called tailing windrows, now visible in aerial photos. And while historic upstream hydraulic mining did result in

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2436-462: 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

2494-426: 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

2552-534: The next 10 years fighting for public access, arguing that the road had been public since 1850, when it was used by gold miners. Dozens of members of the coalition were arrested for trespassing on the public road, although none was convicted. In 2000, Yuba County Superior Court Judge Dave Wasilenko ruled that Hammonton Road was a public road, a decision ultimately upheld by the California Supreme Court in 2002. Two mining company owners were arrested for blocking

2610-667: 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,

2668-534: The remaining sediment slurry back into the mountain valleys. Rivers and streams carried the flood of sediment —called slickens —down to the Sacramento Valley . Anywhere between 326,000,000 cubic feet (9,200,000 m) to 685,000,000 cu ft (19,400,000 m) of debris was deposited in the Yuba River. The mine waste carried by the Yuba River ended up raising the riverbed (by up to 100 feet (30 m) in some cases), causing floods that buried farms east of

2726-490: The river systems. In 1893, the California Debris Commission began to dredge the Yuba River near Marysville to mitigate the environmental damage from hydraulic mining, and piled the gravel along the river's banks. Later, in 1904, W.B. Hammon introduced the first bucket-line gold dredge to the area, and before the end of 1904, two such gold dredges were operating. This Hammonton dredge field rapidly became one of

2784-476: 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

2842-461: 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

2900-628: 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

2958-470: The town of Marysville with gravel, mud, as well as mercury and arsenic (byproducts of the mining process). As the Yuba River is a tributary of the Sacramento River , much of that debris then found its way to the San Francisco Bay . In Sacramento , the I Street Bridge had to be raised 20 feet (6.1 m). Lawsuits by farmers curtailed hydraulic mining in 1883, but the slickens remained behind in

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3016-427: 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

3074-681: 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

3132-446: 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

3190-464: 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

3248-516: Was dredged to produce an estimated 5.14 million ounces (146 × 10 ^  g) of gold. The goldfields are noted for their otherworldly appearance (a result of gold dredging operations), filled with roughly linear mounds of gravels (called dredge tailing windrows), ravines, streams and turquoise-colored pools of water. From the air, the goldfields are said to resemble intestines . Wild turkeys, deer, ducks, Beavers, herons , bald eagles , Northern river otters and even mountain lions now live in

3306-407: Was native alluvium, not hydraulic mining debris. This dredge field is the largest in the state, both in terms of volume of material dredged, and amount of gold recovered (5.14 million ounces, estimated). The dredgers also created over 200 ponds, which are fed by a network of underground rivers, which in turn were formed due to the porosity of the ground. The water in these ponds is usually clear blue,

3364-441: Was the principal source of gold in California for some time. Two mining towns, Hammonton and Marigold, were founded to house the gold miners and their families, but have been largely abandoned since 1957. By the 1970s, it was economically impossible to retrieve any more gold, and the debris became a source of aggregate , an essential ingredient of concrete . It has been estimated that up to $ 15 billion worth of aggregate lies within

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