256
R.H. Charlier and Chr. P. De Meyer
~.1. Conditions
As the pumping distance range of self-unloading trailing suction hopper
dredgers is rather limited, the distance between the mooring point and the
beach area should not exceed this maximum range. This can be a restriction
for the hopper capacity of the vessel as large trailing suction hopper
dredgers require greater water-depth.
The local circumstances should also permit an easy displacement of the
mooring point.
or.2. Equipment and execution
The type of mooring point selected and the pipeline connection with the
beach depend on the local wave, tide, current and weather conditions. Under
calm conditions, it will be possible to use a riser pontoon anchored, or fixed
with spuds, on the seaward size of a submerged pipeline. This can be
connected to the hopper dredger by means of a flexible floating pipeline and
a quick coupling over the bow. When rough weather conditions can be
expected, it is not advisable to use these types of pontoons and link to a selffloating flexible pipeline is necessary'.
This can then be picked up by the trailing suction hopper dredger under
rough weather conditions and connected directly to the submerged pipeline.
A greater water depth is required at the mooring point under such
circumstances, and the trailing suction hopper dredger must be able to
swing around the mooring point to find a good head-on position. When
large quantities are required over a long stretch of beach, two or more
submerged pipelines should be installed to avoid long pumping distances
and to introduce an escape possibility to safeguard a continuous operation.
For rapid or emergency beach nourishment schemes, pumping through a
nozzle on the bow of a trailing suction hopper dredger may be the solution.
This very expensive method will only be used to replenish areas difficult to
be reached by pipelines.
Conditions
When the borrow area is situated in a sheltered area, a cutter suction
dredger or a stationary" suction dredger can be used. The dimensions of the
borrow area should be large enough. This method is commonly used.
Fine materials from the borrow site end up in the reclamation area.
R.H. Charlier and Chr. P. De Meyer
~.1. Conditions
As the pumping distance range of self-unloading trailing suction hopper
dredgers is rather limited, the distance between the mooring point and the
beach area should not exceed this maximum range. This can be a restriction
for the hopper capacity of the vessel as large trailing suction hopper
dredgers require greater water-depth.
The local circumstances should also permit an easy displacement of the
mooring point.
or.2. Equipment and execution
The type of mooring point selected and the pipeline connection with the
beach depend on the local wave, tide, current and weather conditions. Under
calm conditions, it will be possible to use a riser pontoon anchored, or fixed
with spuds, on the seaward size of a submerged pipeline. This can be
connected to the hopper dredger by means of a flexible floating pipeline and
a quick coupling over the bow. When rough weather conditions can be
expected, it is not advisable to use these types of pontoons and link to a selffloating flexible pipeline is necessary'.
This can then be picked up by the trailing suction hopper dredger under
rough weather conditions and connected directly to the submerged pipeline.
A greater water depth is required at the mooring point under such
circumstances, and the trailing suction hopper dredger must be able to
swing around the mooring point to find a good head-on position. When
large quantities are required over a long stretch of beach, two or more
submerged pipelines should be installed to avoid long pumping distances
and to introduce an escape possibility to safeguard a continuous operation.
For rapid or emergency beach nourishment schemes, pumping through a
nozzle on the bow of a trailing suction hopper dredger may be the solution.
This very expensive method will only be used to replenish areas difficult to
be reached by pipelines.
Conditions
When the borrow area is situated in a sheltered area, a cutter suction
dredger or a stationary" suction dredger can be used. The dimensions of the
borrow area should be large enough. This method is commonly used.
Fine materials from the borrow site end up in the reclamation area.