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The Basics of Mechanical and Hydraulic Dredging

The Basics of Mechanical and Hydraulic Dredging

As most of us know, the act of dredging is when a dredge removes materials from the bed of a body of water and moves them to another place. That being said, did you know that there are two major dredging methods? If not, they are mechanical dredging and hydraulic dredging, and within each, there is a variety of equipment, both old and new. 

In this blog, we’re going to explore the two major dredging types, as well as explain a few different equipment types utilized in each. 

  1. Mechanical Dredging 
    1. Bucket Dredging 
    2. Grab Dredging 
    3. Backhoe Dredging 
  2. Hydraulic Dredging
    1. Suction Dredging 
    2. Cutter Suction Dredging
    3. Trailing Suction Hopper Dredging 
    4. Reclamation Dredges 
    5. Barge Unloading Dredgers

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Mechanical Dredging 

In essence, mechanical dredging is the act of using a dredge that digs materials from an extraction site. Most often, there is a stationary, bucket-oriented machine that scoops the desired materials before transporting them to the sorting area.

Below, we will briefly discuss some of the mechanical methods that are and have been used for dredging.  

a. Bucket Dredging 

Bucket dredging is one of the original methods of dredging, where a stationary barge equipped with a boom of large, consecutive buckets rotates, scooping material from the dredge site.

After extracting the material, the buckets drop their loads into a sifter that sorts the smaller, desired material (usually gold) from large materials which are moved out of the back of the dredger’s hull. This would continue until the material in the dredging area was exhausted. At that point, the barge would be moved forward via winching to continue the dredging project

b. Grab Dredging 

In the realm of deep-depth dredging, grab or clamshell dredgers stand out for their proficiency. Designed to delve into great depths, these dredgers operate by deploying a sizable bucket, akin to a clamshell, to the bottom of a water body. Once it touches the seabed, the bucket snaps shut, capturing the underwater material. This scooped material is then transported to a barge for meticulous sifting and sorting. The mobility of these dredgers may vary depending on the model, but their essential function remains impressively consistent.

c. Backhoe Dredging 

Backhoe dredging operates in a manner similar to its namesake, the backhoe. Once anchored at the dredging site, this method employs a large backhoe bucket that descends to the excavation site at the water bed. It then digs and scoops up the underwater materials, elevating them back to the surface. Subsequently, the extracted contents are deposited onto a barge for detailed sifting and sorting.

Hydraulic Dredging

Hydraulic dredging is centered around the concept of transferring dredged materials from the dig site to a processing location for sifting and sorting. It involves creating a slurry—a fluid mixture comprising elements like rock, dirt, and gravel—which is then transported to a sorting facility.

Continue reading to explore various methods employed in hydraulic dredging. 

a. Suction Dredging 

Essentially an elevated Shop-Vac, a suction dredge operates like a high-powered vacuum that works underwater. This is made possible due to high-powered water pumps located on the dredge barge, which are gasoline powered.

Nowadays, suction dredging is most often used for gold extraction, as it effectively gathers and separates the gold from water and gravel. When materials are sucked into the dredge, a sluice retains any gold that has been extracted while expelling the gravel and water back to where it came. 

b. Cutter Suction Dredging

Cutter suction dredges share similarities with standard suction dredges but have a notable addition: a rotating cutter head. This cutter head is adept at breaking up rock and other dense materials, which are then suctioned or pumped out for sorting and sifting. These dredges, capable of handling a diverse range of materials, are typically stationary.

Additionally, due to their substantial size, cutter suction dredges are primarily employed in large-scale dredging operations, such as harbor deepening projects.

c. Trailing Suction Hopper Dredging 

In this dredging method, a specially equipped vessel features two suction pipes, one on each side of its hull. These pipes trail along the seabed of the targeted water body, vacuuming loose materials into the ship’s storage hold. After filling up, the vessel transports the dredged materials to a designated offloading site, then returns to continue the dredging process.

d. Reclamation Dredges 

These dredges are used to empty trailing suction hopper dredges. Very simply, they use a suction pipe that is placed in the dredging ship to remove, or reclaim, the dredged materials. These pipes move the materials from the ship onto the shore to be processed and dealt with. 

e. Barge Unloading Dredgers

Barge unloading dredgers operate similarly to reclamation dredges, with their primary function being to unload dredged materials from barges. However, a key distinction is their use of jetting technology to transform the dredged material into a slurry. This liquidized material is then pumped to a different location for further processing.

U.S. Aqua Services Dredging Services and Equipment Rentals

Between mechanical and hydraulic dredges, there is a wide variety and a vast history. Although it’s amazing to recognize the advancements in technology that are available, the sheer amount of information regarding dredging and its methods can be overwhelming.

At U.S. Aqua Services, we’re here to help. We are experts on dredging methods and equipment, which means that regardless of the job, we have the equipment and the know how to ensure that your dredging project is completed effectively and safely. 

We hope this blog taught you something new, and if you’re interested in learning more about dredging, or are in need of dredging equipment rentals and services, contact us today! 

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About U.S. Aqua Services

U.S. Aqua Services was created to support the dredging process in advancing commerce and responding to its many challenges. To accomplish this, our dredging company assembled an exceptional group of experienced individuals and a diverse inventory of dredge equipment and excavator dredge pumps.

We offer dredging equipment rental services so you can have access to the latest and greatest in dredging technology without having to pay to maintain it, transport, and store it, along with dewatering services.

With an emphasis on mobility, dependability, durability, diversity, efficiency, and safety, our dredging rental company can ensure that our different types of dredging systems are easy to move through any terrain and can work in the most rugged and remote environments. Our multi-function hydraulic systems are built with jetting and mechanical options that can efficiently move loose sediment or stiff layers of clay.

US Aqua services also and maintains a ready fleet of amphibious equipment capable of completing dredging projects in some of the harshest and most remote environments. U.S Aqua is also the dealer for Louisiana of the amphibious vehicle Fat Truck. No matter the size or scope of the job or the remoteness of your work location, you can rely on Fat Truck’s industrial off-road utility vehicles to get the job done right.

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