What is Dredging and Why is it Done?

What is Dredging and Why is it Done?

In a nutshell, using a dredge for dredging is the act of displacing, or moving, sediment, and solid particles from one point to another within a body of water. It is routinely necessary to clean our busier harbors and channels as sedimentation can gradually fill these underwater areas over time. Dredging is most often involved in maintaining or increasing the depth of various navigation channels to ensure the safe passage of boats and ships.

Another important aspect of dredging is that it’s also performed for environmental cleanup jobs to help reduce the exposure of humans, fish, and other wildlife and to prevent the contamination from spreading further to other areas of the water. Environmental dredging is often necessary for cities and large industrial areas because sediments around these areas are often contaminated.

How is Dredging done?

Dredging typically involves moving course materials such as sand and gravel. While there are many possible ways to transport this sort of material from one place to another, assuming the right conditions are present, a hydraulic transport dredge is generally the most efficient as in the lowest cost per ton of material moved.

Dredging is used widely across the world for various applications including but not limited to:

• Beach restoration
• Coastal protection
• Fly Ash/Tailings/Waste removal
• Lake dredging
• Land Reclamation and Island Creation

Dredging can be only possible under some required conditions. The conditions required for efficient dredging are as follows:

Water must be present to serve as the transport medium. Usually, the dredge will float along a body of water with the pump dragging along the bottom of the seabed, excavating material is it moves across the surface. The head of the dredge pump is often fitted with cutterheads or water jets to help loosen and break up the sediment which then mixes with the water into a slurry form, which is ideal for pumping over distances.

Dredging also is only able to pump particles that can easily fit through the pump. Trying to pump larger stones and other debris has the potential to clog the pump systems which then requires maintenance. Generally, a dredging system can pass particles equal in size to one half the inside diameter of the discharge pipe. Anything large, and it could cause damage to the pump impeller or other parts of the system, requiring downtime and more cost.

Free-caving solids are typically the most desirable to a dredge operator. Free-caving solids can be described as looking like a bowl of sugar when a spoonful is removed is the ideal material for dredging. However, finding material naturally in this state is rare. What is typically found are large embankments of material that break off in relatively small chunks that slide down the embankment. However, some material can be present that can add difficulty in breaking up sediments such as clay layers, cementation, or thin layers of rock. These types of deposits are commonly dredged and mined, however, an aware operator will remain on alert to move the ladder out of the way whenever a cave-in is forthcoming. Occasionally, the dredge ladder may be stuck by quick-moving cave-in material.

Maximum transport distance depends on the installation of the pipeline and several variables like diameter and distance of the pipes, density of the material to be pumped, the average size of the solids, and vertical distance of the discharge point above the water level. When the capability of one pump is exceeded, the option of a booster pump can be added to extend the pumping range. The cost and operating expenses of additional boosters should be compared against the cost of moving the discharge point closer to the dredge.

Common Dredging Applications for Mini Dredge and Small Pontoon Dredgers

• Clean up docks and marinas from the foul-smelling green or black sludge that can accumulate in bodies of water.
• Golf course maintenance and restoration by ensuring the bodies of water look pristine and clear of unsightly debris or material.
• Pond dredging helps to ensure that your pond is clean and presentable.
• Maneuver within narrow canals to widen the channel or remove sediment from the bottom.

Dredging Hard to Reach Areas

Standard ladder dredges are large machines and can have difficulties navigating narrow or shallow channels of water to dredge. To dredge hard to reach places, a different approach must be utilized. One option is to dredge from the shoreline using a suction pump, or a diver operated dredge. Another solution is by using a smaller dredge or Mini-Dredge which can be a cost-effective solution for dredging small, narrow areas that a standard ladder dredge would never be able to get to. Another advantage is the mini-dredge is easy to operate and can be operated by a single operator.

The mini dredge comes equipped with a high powered slurry pump, which is a slurry pump that is built for reliability capable of pumping high-percent solid slurries, ensuring efficient workflow during the dredging project. Our pumps can pass objects over 9 inches in diameter without clogging or requiring expensive maintenance.

Depending on your power source, the dredge can be fixed with different accessories and pump sizes to ensure your project runs as efficiently as possible.