Environmental Dredging Overview
What is Environmental Dredging?
Environmental dredging is the process of removing, treating, and displacing contaminated underwater sediment. The sand and silt that gradually travels downstream are filled with pollutants from cities or industrial areas. Environmental dredging is important in the protection and restoration of marine wildlife in cases of environmental damage.
Dredging increases the depth of the water so large barges and ships can get through. It also prevents the spread of contaminants to other bodies of water.
If you have had issues with pollution or sediment build-up in your lake or pond, it may be time to dredge.
The port authorities or officials from the government supervise environmental dredging for safety reasons. You must have a permit from the U.S. Corp of Engineers before any dredging is started.
What Problems It Solves:
Aside from protecting and restoring marine wildlife, environmental dredging can also get rid of any build-up in your body of water that may be making it more difficult for large barges or ships to get through.
Advantages & Disadvantages of Environmental Dredging
Advantages:
There are many advantages to environmental dredging, such as:
- Enables the construction of structures including Marianas, dams, and dykes
- Can reduce flood risk
- Restores water quality by moving contaminated sediment
Disadvantages:
While there are many good things about environmental dredging, there are some downsides, which include:
- Can remove essential minerals that significantly damage an ecosystem
- Can alter the soil composition, which can change the turbidness of the water. This can lead to a broader spread of contaminants
- Substances previously located on the removed soil will float freely and negatively impact the uncontaminated soil and water
Environmental Dredging Process
Process
When planning to start dredging, there are a few things you should take into consideration.
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- Get a permit: Before dredging occurs in any substantial body of water within the U.S., you must have a permit from the Corp of Engineers.
- Perform a pre-dredge hydrographic survey: Hire an experienced hydrographic surveyor for this step. This will tell you both the water depth and the type of soil thickness, which will help you determine the cost later on.
- Contract or DIY: Decide if you want to hire a contractor or if you want to dredge yourself. If you plan to dredge more than half of the year, it may be more cost-effective to purchase a dredge and hire a trained team. However, if you plan to dredge any less frequently than that, it’s best to leave it to the professionals.
- Do your research: If you’ve chosen to hire a contractor, look for a company with quality and experience. Make sure they have a solid safety record and have accident prevention methods in place. You should also check to see if they are adequately insured and have environmental precautions if anything goes wrong.
- Schedule the project: If you’re doing it yourself, you can get started as soon as you have the proper equipment and staff available. Otherwise, communicate with your contractor and decide what type of dredging needs to be done to determine when they can do it.
- Start dredging: Depending on the size of the project, dredging can take anywhere from a week to a month.
Materials
So now that you know the different types of environmental dredging and the basic process, you may be wondering what you need to get started.
You’ll need:
- A dredger (mechanical or hydraulic).
- An auxiliary component, such as a pipeline, for transporting the dredged material.
- A trained team or contractor.
Alternative Solutions to Environmental Dredging
If none of this sounds appealing to you, you may need to consider different options. Fortunately, there are other ways to contain or manage contaminated underwater sediment. These include:
- Biological Dredging: This is performed by using a high number of beneficial microbes to extract the organic material from the bottom of a body of water. This process requires no heavy equipment or permits.
- Capping: This is when clean material is placed over contaminated sediments. It prevents groundwater from becoming contaminated as well.
Of course, each alternative has its advantages and disadvantages.
| Service vs Service | Advantages | Disadvantages |
|---|---|---|
| Environmental Dredging vs Biological Dredging | Environmental dredging, compared to biological dredging:
| Environmental dredging, compared to biological dredging:
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| Environmental Dredging vs Capping | Environmental dredging, compared to capping:
| Environmental dredging, compared to capping:
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Costs of Environmental Dredging
The cost of environmental dredging is measured by the cubic yard and the thickness of the sediment. The removal is usually $4-$10, depending on the contractor.
In addition to the cost of dredging the contaminated soil, there is a price for removing the sediment from the site. The farther away you want to take the silt, the more it is going to cost. The weight and thickness of the product you remove will influence the price.
There is also the cost of mobilization and demobilization, which is bringing the equipment to and from the site. Because the hardware needed for this project is so large and heavy, this is one of the more expensive parts of the dredging process. Mobilization and demobilization costs anywhere between $20,000-$50,000.
If you are not hiring a contractor, costs will also include the dredging equipment, which is priced between $30,00 to $50,000. You will also need to factor in wages for staff to man the dredge and insurance to cover any accidents that may take place.
If you are hiring a contractor, take your time shopping around your area to find who offers the highest quality at the lowest price. The best way to get a good bid from a dredger is to know exactly what you need. You can accomplish this by hiring a hydrographic surveyor.
Frequently Asked Questions
If there is a high presence of rocks and gravel in your body of water, you will probably need to use a mechanical dredge. If you only have sand and silt, a hydraulic dredge should work for you.
Permits can take anywhere from a few weeks to six months to obtain, depending on the size of the project.
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