Maintenance dredging is the routine
periodic removal of material in approach channels
to port and harbour basins to maintain widths and
depths in previously dredged areas to ensure the
safe access for vessels. Maintenance dredgings are
generally composed of sands and silts that have
been recently deposited by siltation and must be
removed in order to keep a channel or berth open
for navigation at the defined design profile.
Maintenance dredging may vary from
an almost continuous activity throughout the year
to an infrequent activity occurring only once every
few years. For the purpose of disposal licensing
a general rule of thumb is applied, that if a period
of over five years has lapsed between a new and
previous dredge, the material will be treated as
capital dredgings for disposal purposes due to its
characteristics. However, this will be considered
on a case-by-case basis.
In ports and harbours dredging may be required
to deal with unforeseen circumstances, such as the
movement of a sandbank across an entrance channel
to a port which must be removed as a matter of emergency.
From a disposal viewpoint this is considered as
Definitions are based on those provided by the
following dredging specialists and organisations:
- Bray, Bates & Land 1997.
- Institute of Civil Engineers 1995.
- ABP Research, R462 1994.
- IADC & CEDA 1996.
- Bowles, MAFF personal communication 1999.