What Is Dredging:
Dredging is the removal of bottom material from lakes, rivers, harbors,
and water treatment settling ponds. Dredging is done to remove
sediments and undisturbed bottom materials to increase water depth to
permit the passage of ships and barges, to increase the capacity of
water storage reservoirs, for recreation boating, to rebuild beaches,
and to remove sludge from water treatment ponds.
There are two basic types of dredging.
Dredging Specialists has completed close to 150 hydraulic dredging
projects in 22 states. Since 1979, all contract work has been done with
dredges we designed and built.
A hydraulic dredge consists of a floating barge. There is boom, called
a ladder that is lowered into the mud. The ladder has a device called a
cutterhead, on the end. The cutterhead rotates and excavates the
material. There is a large pump in the hull of the dredge. The
excavated material is sucked from inside the cutterhead through a pipe
to the dredge pump. The pump then pumps the slurry to a spoil area.
The pipeline contains about 20% mud and 80% additional water.
The spoil area has levees around it to contain the mud and water and
also provide the means for the mud to settle and the water to become
clear, so it can be returned to the lake. The spoil area should be 1.3
times the volume of material to be dredged, plus at least 1 foot of
freeboard. A weir must be installed in the spoil area to remove the
clear water so it can be returned to the lake. The clear water is
returned by pumping in a pipeline or by gravity in a ditch.
Hydraulic dredges come in many sizes and production capacities. They
weigh from 10 tons to 50 tons and more. To transport the dredge,
pipeline and support equipment, will require 3 to 10 truck loads. A
large crane is needed to assemble and launch the dredge. The pipeline
from the dredge to the spoil area must be assembled. The dredge and
pipeline must be disassembled and hauled from the site when the work is
completed. This is called mobilization and de-mobilization.
Mechanical dredging is generally done with a barge mounted crane using a
clam bucket or dragline bucket. A hydraulic excavator can also be
used. The material is excavated and placed in a barge. A boat,
[towboat / tugboat], moves the barge to the disposal area. On inland
lakes and rivers, the barge is generally moved to the shore and the mud
is unloaded with a crane using a clam bucket. The mud is placed in dump
trucks, and hauled to a disposal site.
On coastal dredging, the material is placed in a barge. The barge is
then towed to an approved area that is generally far out in the ocean
and the mud is bottom dumped from the barge. The barge can also be
unloaded by pumping, for beach repair or the mud can be pumped to a
The Dredging Specialists exclusive Drag Scraper Dredging System is
another form of mechanical dredging. Click on this link to learn more
How Dredging Work Is Priced:
Dredging work is priced by the cubic yard of material that is dredged.
To determine the cubic yards to be dredged, take the acres to be dredged
X 1,600 cubic yards per foot of material depth. Note: There are 43,560
square feet in one acre. Example: If you have a 10 acre lake and a 5
foot depth of material to be dredged. 10 X 5 X 1,600 = 80,000 cubic
yards. Another method is to take the
[length x width x depth of material to dredge] / 27 = cubic yards to be
Hydraulic Dredging Costs.
Cost to design and build the spoil area, and dredge the material: $4.00
to $8.00 per cubic yard.
Combined charge for mobilization and de-mobilization: $20,000 to
preliminary cost estimates, use the average of the above costs.
there are words herein that you do not understand, you can look them up
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Keep in mind that Dredging Specialists provides professional consulting
services based on over 30 years of hands on dredging experience.
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