Volume 8 – Mechanical and Electrical Services - Malaysia Geoportal

Chapter 8 DREDGER
f) Suctions and Discharge system
i) Dredge pump
ii) Suction dredge pump
iii) Gland pump
iv) Flushing pump
v) Floating pipelines
8.5 DISPOSAL OF MATERIALS
In a "hopper dredger", the dredgings end up in a big onboard hold called a "hopper", which has doors
in its bottom. The excess water in the dredgings is spilled off by sedimentation: as the mud and sand
settle to the bottom of the hopper, the water is siphoned from the top and returned to the sea to
reduce weight and increase the amount of dredgings that can be carried in one load. When the hopper
is full, the dredger stops dredging and sails to a dump site and opens the bottom hopper doors,
dumping the slurry out. Or the hopper can be emptied from above.
Sometimes with a suction dredger the slurry of dredgings and water is pumped straight into pipes which
deposit it on nearby land by pipes; or in barges (also called scows) which deposit it in the deep sea or
on land.
Dredged materials will be disposed of at either one of the following locations:
a) At a temporary basin with adequate storage capacity outside the limits of the existing approach
channel.
b) At a temporary stockpile within 1 nautical mile outside of the end of the existing approach channel.
c) At the contractual spoil disposal area
d) At an alternative spoil disposal area
March 2009 8-9