Framework for Dredged Material Management
2.3 Transportation of Dredged Material
Transportation methods generally used to move dredged material include the
following: pipelines, barges or scows, and hopper dredges. Pipeline transport is the
method most commonly associated with cutterhead, dustpan, and other hydraulic
dredges. Dredged material may be directly transported by hydraulic dredges through
pipelines for distances of up to several miles, depending on a number of conditions.
Longer pipeline pumping distances are feasible with the addition of booster pumps, but
the cost of transport greatly increases. Barges and scows, used in conjunction with
mechanical dredges, have been one of the most widely used methods of transporting large
quantities of dredged material over long distances. Hopper dredges are capable of
transporting the material for long distances in a self-contained hopper. Hopper dredges
normally discharge the material from the bottom of the vessel by opening the hopper
doors; however, some hopper dredges are equipped to pump out the material from the
hopper much like a hydraulic pipeline dredge.
2.4 Placement or Disposal Operations
Selection of proper dredging and transport equipment and techniques must be
compatible with disposal site and management requirements. Three major alternatives are
Each of the major alternatives involves its own set of unique considerations, and selection
of a management alternative should be made based on environmental, technical, and
2.4.1 Description of Open-Water Disposal
Open-water disposal is the placement of dredged material in rivers, lakes,
estuaries, or oceans via pipeline or release from hopper dredges or barges. Such disposal
may also involve appropriate management actions or controls such as capping. The
potential for environmental impacts is affected by the physical behavior of the open-
water discharge. Physical behavior is dependent on the type of dredging and disposal
operation used, the nature of the material (physical characteristics), and the
hydrodynamics of the disposal site.
Dredged material can be placed in open-water sites using direct pipeline
discharge, direct mechanical placement, or release from hopper dredges or scows. A
conceptual illustration of open-water disposal using the most common placement
techniques is shown in Figure 2-2.