U.S. Aqua Services

What Is Dredging

Briefly put, dredging an important process of scooping up sediment from a water source and depositing it elsewhere. It can be done in a variety of means, and under a myriad of circumstances. While some machines utilize hydraulic suction cutters others might make use of mechanical large scoops or shovels.

For the most part, this is done to make a waterway more navigable or useful. Dredging projects can be carried out nearly anywhere that has a body of water, from small ponds to major oceans.

Why is Dredging Done?

There are two primary reasons why dredging is done.

The first is an attempt to make ports more manageable to navigate. Sediment often builds up at the bottom of channels due to water moving downstream, carrying sand and mud along with it. When too much of this matter builds up, it makes it difficult for ships and vessels to move. When dredged, the sediment that was building up is transported to another area. Usually, the sediment is transported to an approved area, so as not to disrupt the ecosystem. Additionally, it could also be placed in an area where the soil is devoid of minerals and nutrients.

Dredging is also done as an effort to remove sewage and garbage from certain areas, specifically those that have become waste spots for companies or cities. Our dredging company does work in removing solid waste from the beds of oceans, lakes, and other bodies of water. Water pollution is harmful to delicate ecosystems, and simply removing the solid waste left behind can do a lot in repairing the waters and preventing the contaminants from spreading.

Where is Dredging Done?

Dredging can be done in just about any sizable body of water. Dredging companies may dredge lakes, ponds, oceans, and inland dredging across the world. Usually, these companies work towards ports, marinas, and areas close to the land, as those are normally the most accessible areas that need the most work done.

Dredging is normally done in somewhat shallow bodies of water. Unfortunately, neither U.S. Aqua Services nor anybody else in the world at this moment has the ability to reach the bottom of the Marianas Trench.

How is Dredging Done?

Dredging seems like a complicated process. Scooping anything off the bottom of a murky body of water is difficult.

Because of this, dredging companies use boat-like machines with an attached device similar to a skimmer, and essentially “skims” the bed of the water. Often, the skimmer will have an attachment called a cutter head used to loosen materials at the bottom, making them easier to scoop or suck up.

What Is Dredging Used For

Due to changing weather patterns and environments, as well as expanding global commerce, there has been an increasing need for dredging equipment and dredging companies.

These companies are involved in dozens of different projects around the world, but for the most part, they are used to keep a few vital industries running.

Open Waterways

Waterborne transportation of goods and people is still the preferred method of shipment for businesses and countries around the world. But there are few ports and harbors in the world that are naturally large enough to manage the ever-increasing size of shipping freighters and boats.

To ensure that these ships can safely navigate these waterways, dredging equipment is brought in to make these ports and harbors deeper and wider. But these projects have to be done routinely to ensure that the edges and beaches of the harbor or port do not erode and fill in these waterways again.

Increasing Populations

The world’s population continues to increase at a rapid pace. As these populations grow and shift, more and more people are locating themselves near a coastline or waterway of some kind. In fact, it’s estimated that about half of the world’s population lives within 125 miles of a coast.

These populations are impacted by the changing climate and the rising oceans. With the increased risk of flooding and other environmental disasters, dredging equipment can be used to mitigate the effects of these events. In many cases, coastal cities are relying on dredging equipment to help reclaim beaches, allowing more homes to be built near the water’s edge.

Access To Resources

While often connected with the process of simply removing material, more and more dredging companies are taking part in projects that are focused on extracting resources to be used in other projects. The silts, sands, and gravel at the bottoms of waterways are incredibly valuable in a wide variety of industries.

For example, only the sand found along beaches of rivers, and oceans can be used to create the concrete needed for new buildings. Similarly, the gravel found along waterways are used in projects ranging from garden landscaping to constructing roads and highways around the world.

In many cases, the only machine capable of collecting these materials, and in the massive quantities that the global market requires, is a dredge.

Environmental Remediation

As human populations developed different technologies and manufacturing techniques, they relied on their water sources to power, or clean many of these innovations. The result was not always a positive one for that waterway. Rivers and lakes were filled with noxious chemical byproducts that dramatically impacted the ecosystem of that water source.

Dredgers have increasingly been utilized in environmental remediation projects that target patches and segments of poisoned river banks, lakeshores, and more. Using a variety of specialized equipment and suction cutter dredgers, companies can precisely remove these harmful materials without disturbing the rest of the waterway.

In other projects, the materials that are dredged from rivers are being used to create new streams, channels, and islands that are beneficial to the native fish and bird populations that live there.

Types of Dredging Projects

A few of the most common dredging projects include:

1- Port And Harbor Construction

2- Maintaining A Port Or Estuary

3- Land Reclamation

4- Environmental Remediation Dredging

5- Coastal Protection

6- Offshore Trenching

7- Dredging For Sand And Gravel

8- Construction Of Lakes And Reservoirs

9- Damn Dredging

Types of dredgers

The dredging industry is constantly innovating technological solutions, while also creating new machines that make projects easier and kinder to the environment. Below is a list of the most common types of dredgers and how they are unique from one another.

1- Suction Dredger

2- Cutter Suction Dredgers

3- Excavator Dredgers

4- Bucket Ladder Dredgers

5- Clamshell Dredgers

6- Remote Dredging (Autonomous Dredgers)

7- Sand Dredger

Dredging Equipment

Submersible dredge pump 

A submersible dredge pump is a type of dredging equipment that is used to remove silt and other sediments from the bottom of a river or water source.

This type of dredger uses a series of pumps to suck up the sediment and deposit it into a holding tank or onto a conveyor belt that moves it to its final destination.

Submersible dredge pumps are commonly used in environmental clean-up projects or to restore rivers and wetlands.

Dredging Dewatering

Dredge dewatering is the process of removing water from dredged material. Dewatering can be done through a variety of methods, such as centrifuges, filter presses, and belt presses.

Dewatering is an important step in the dredging process because it allows for the removal of excess water that would otherwise add weight and volume to the dredged material. 


The necessity of dredging

Helps To Protect Against The Effects Of Coastal Erosion

Like we talked about in our last post, coastal erosion is a process that breaks down the coastline. When something like a hurricane, cyclone, or tropical storm makes its way inland, it displaces the sand and sediment around the beach and deposits it elsewhere, usually in awkward places like sandbars located fairly far away from the coast.

As the water line creeps closer to the towns and inhabited areas, the risk of problematic flooding and damaging storms affecting the area begins to rise as well. The distance that the beaches create between the water and the towns serves as a protective barrier. If this distance doesn’t exist, the towns and infrastructure become more vulnerable.

Inland dredging combats against coastal erosion by depositing sand and sediment in places where erosion is most substantial. This effectively adds to the land and helps buffer against the effects of strong storms and flooding. When ocean dredging, it’s considered best practice to deposit sediment that is safe and uncontaminated so as not to disrupt the environment in that area. 

Habitat Restoration

Similar to coastal erosion, strong storms could also disrupt marine and beach habitats which often exist in the surrounding sand or gravel. When the habitats are disrupted, the wildlife is forced to relocate. This can cause issues in surrounding towns and can also put the wildlife at risk.

Inland dredging serves as a way to safely maintain the environments where the plant and animal life inhabits. Again, it’s especially crucial to only use dredged material that is safe and free of contaminants.

Dredging companies, when doing their job properly, pick up materials from specific areas and transport it to places that have been affected by storms and strong waves. Basically, it recreates the sand and dunes that have been eroded or destroyed.

Making Marinas Possible To Navigate

One of the most prominent ways to import and export products is via ships and boats. When these vessels make their way inland, they dock at marinas.

Because marinas are so close to land, they’re not nearly as deep as other parts of the ocean located farther off the coast. Sometimes, the sediment at the bottom of marinas begins to concentrate in certain areas, making it difficult for ships and boats to navigate without getting stuck.

That’s where dredging comes in.

Dredging companies either scoop or suck up the sediment and transfer it elsewhere. When doing this, it’s very important to not transfer materials such as garbage or contaminants, so as not to harm other environments.

Recycles Contaminants

At this point, you’re probably wondering what dredging companies do with the material that is contaminated. One of the best uses for contaminated sediment is to actually turn it into useful objects.

Something that we regularly see is using the material to construct concrete and gravel. Not only is this a safe alternative to depositing the material in other areas, but it also takes out the polluted sediment from the marina.

There are quite a few reasons why it’s necessary to dredge, as long as it’s being done safely. Following protocols and never skimping on proper safety steps is important, especially when dealing with precious and fragile wildlife.


The Basics Of Mechanical And Hydraulic Dredging

The dredging industry is constantly innovating and creating new machines that make projects easier and kinder to the environment.

In some instances, dredging machines are designed to comply with the strict requirements and thrive in the harsh environments of specific industries, such as the oil and gas industry.

There are two major dredging methods: mechanical dredging and hydraulic dredging.  Within each method, there is a variety of equipment, both old and new.

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.

Mechanical dredging necessitates the use of heavy equipment to dig up the bottom of a water source, and move it. This equipment can be moved to the job site by a barge, or the body of water can be drained, allowing the equipment to move to the site on its own. Some specialized mechanical dredging equipment can drill or dig up the dirt.

While mechanical dredging is the most commonly rented form of dredging machinery, that does not mean it is always the most effective. Because this form of dredging requires a bucket or digger to impact and shovel away the sediment, there is a higher chance of contaminated materials within the sediment to be dispersed into the water surrounding it. The contaminated soil can fall out of, or through the bucket, and spread further into the water.

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. 

Grab Dredging 

Grab or clamshell dredgers are typically utilized for deep depth dredging, as they can reach extremely deep depths.

While their mobility varies based on the model, the general function of a grab dredge is to lower a large, single bucket to the bed of a water body.

Upon reaching the bed of the water body, the bucket would close (like a clamshell, hence its name) and scoop up the material that was then placed onto a barge to be sifted and sorted. 

Backhoe Dredging 

Backhoe dredging, as the name implies, works like a backhoe. After being anchored in the dredging area, a massive backhoe bucket lowers to the water bed excavation site, scoops materials into a bucket, raises them to the surface, and empties the extracted materials onto a barge to be sifted and sorted. 

Hydraulic Dredging

Hydraulic dredging focuses on pumping dredged materials from the excavation site to a processing site where the materials are sifted and sorted.

This form of dredge relies on creating a slurry, or a liquidized mixture of rock, dirt, gravel, etc. that is then sucked to a sorting area. 

Hydraulic dredgers act as a giant, underwater vacuum cleaners to clean and remove sediments. By sucking up a combination of sediment and water, hydraulic dredgers create what is called a “slurry.” This slurry is moved from the surface and then onto the surface via a pipeline or tube.

This is widely considered the most effective method of dredging when the environment and the ecosystem of the dredging site is of major concern. It is preferred because it prevents most of the contaminated sediments from being dispersed or released into the nearby water source. While this is a major advantage to hydraulic dredgers, they do have their limitations. Because of their design, hydraulic dredgers are excellent for moving loose soils, sands. Silt, gravel, or rocks can cause undue wear and tear on the hydraulic system.

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. 

Most commonly, suction dredges are compact setups, as small teams of gold prospectors use them for personal prospecting and gold extraction.

Cutter Suction Dredging

These dredges are very similar to your basic suction dredges, with the exception that they also contain a rotating cutter head that serves to break up rock and other materials to then be sucked, or pumped to the sorting and sifting stage. These dredges can dredge a variety of materials and are often stationary. 

Additionally, cutter suction dredges are huge, as they’re most commonly used for large-scale dredging projects like deepening harbors. 

Trailing Suction Hopper Dredging 

This type of dredging involves a ship equipped with two fabricated suction pipes on either side of the hull. These pipes drag along the bed of the body of water that is being dredged, and sucks loose materials into the ship’s hold. Once the ship is full, it takes the dredged materials to an offloading site before continuing the dredge. 

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. 

Barge Unloading Dredgers

Similar to reclamation dredges, a barge unloading dredger is used to unload a barge full of dredged materials. The major difference is that these dredges first use jetting to liquidize the dredge into a slurry before pumping it to another site. 

Hydraulic vs Mechanical Dredgers

Which Is Best?

Both forms of dredgers have their benefits. While hydraulic dredgers are precise and fast, they aren’t able to take on heavier materials. Mechanical dredgers are cumbersome and imprecise, but they can move fast quantities of heavy materials with minimal effort. One might be better suited to your dredging job than the other, but often using a combination of the two leads to the best outcomes and maximize ROI. 

Dredgers are ideal for a variety of projects because of their ability to move and remove materials like trash, gravel, and sediment. Dredging can help keep waterways, like rivers and streams clean and help restore their beaches and land from the effects of erosion. Additionally, they can be used to maintain the stability of harbors, ports and marinas.


The Benefits Of Dredging Your Pond

Having a pond on your property is a distinct luxury. It offers you a small escape to a more natural space. The appearance of the pond alone can provide your property with a more serene feeling. It can also lead to some strange smells and become an unsightly addition to your home.

Part of having a pond is taking care of it, and for many, that includes regular dredging of your pond. While we typically work on larger scale projects, as a leading dredging company, we recognize that dredges play a role in projects of all sizes. 

Dredging Sustains The Natural Lifecycle Of The Pond

Man-made ponds have a limited lifespan if they are not cared for. That’s because the pond attracts birds, insects, reptiles, and other creatures to it. As they all make their homes in and around the pond, the pond itself begins to accumulate detritus like loose grasses, sticks, and algae. Eventually, all of these things settle to the bottom of the pond, transforming a pristine water source into a glorified mud puddle.

Your pond becomes a swamp, then a marsh, and then dries up and becomes another part of the dry land surrounding it. This is simply how ponds form and disappear, and is a natural process. But if you put in a pond for aesthetic reasons, this natural process might not be a part of your long-term plans.

Dredging up the muck from the bottom of the pond keeps it from becoming a swampy mess, meaning that you can enjoy the natural beauty of your pond for years.

Dredging Your Pond Can Help Improve Your Property Values

Ponds are an attractive and desirable water feature for any home or property. Many potential home or property buyers are interested in having a pond on their land, be it for aesthetic or recreational purposes.

A well-maintained pond has been shown to increase the property value of a plot of land or home, as well as the values of the properties surrounding it. Conversely, poorly maintained ponds are considered an eyesore, and may actually turn away potential buyers.

Dredging your pond is an investment in the value of your home and land.

The Dredged Materials Can Be Used Elsewhere

Dredging your pond isn’t just good for the natural life cycle and health of the pond itself, but also for the trees and vegetation that surrounds it.

Many people repurpose the nutrient-rich materials dredged from the bottom of their ponds as fertilizer. The muck is spread across fields, placed at the base of trees, and in flower beds and bushes. There, the soil helps to nourish the plants, helping them grow taller and lusher.

Dredging Keeps Your Pond Water Cleaner

Water quality is a key concern for a healthy pond. Dredging helps to promote the proliferation of beneficial bacteria that can help break down the organic waste that collects at the pond’s bottom.

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