CIRCULAR LETTER
MSC/Circ.1021/MEPC/Circ.389
DESIGN SUGGESTIONS FOR BALLAST WATER AND SEDIMENT MANAGEMENT OPTIONS IN NEW
SHIPS
(adopted
on 7 March 2002)
1.
Ballast water carried in ships to maintain safety and stability has been
recognized as one of the major pathways for the transfer of harmful aquatic
organisms and pathogens around the world. This threat to the aquatic
environment has been acknowledged by the Convention on Biological Diversity,
1992, in Article 196 of the United Nations Convention on the Law of the Sea,
1982, and by other relevant international agreements.
2.
A draft international convention for the control and management of ship's
ballast water and sediments as well as associated guidelines for its
implementation is being developed for consideration and adoption by a
diplomatic conference in 2003. This is based on resolution A.868(20) concerning
the Guidelines for the control and management of ship's ballast water to
minimize the transfer of harmful aquatic organisms and pathogens.
3.
The paramount importance of the safety of a ship is acknowledged when
developing ballast water management measures to prevent, reduce and eliminate
the transfer of harmful aquatic organisms and pathogens.
4.
It was agreed that it is essential to continue the development of safer and
more effective Ballast Water Management options that will result in continued
reduction and eventual elimination of the transfer of harmful aquatic organisms
and pathogens.
5.
The Maritime Safety Committee at its seventy-fourth session (May 2001) and the
Marine Environment Protection Committee at its forty-seventh session (March
2002) emphasized the need for ballast water and sediment management options to
be taken into account when designing and building new ships, while noting that
the future convention might require the development of ballast water management
plans both for new and existing ships and approved the Guidance on the need for
ballast water and sediment management options to be taken into account when
designing and building new ships, as set out in Annex hereto.
6.
Member Governments are invited to apply the annexed Guidance until the
International Convention for the Control and Management of Ships' Ballast Water
and Sediments is adopted and enters into force, to bring the Guidance to the
attention of ship-builders, ship-owners, shipmasters and other parties
concerned. Member Governments are also invited to inform the Organization on
any experience gained in the implementation of this Guidance.
ANNEX.
DESIGN SUGGESTIONS FOR BALLAST WATER AND SEDIMENT MANAGEMENT OPTIONS IN NEW
SHIPS
1.1
Ballast water carried in ships to maintain safety and stability at sea has been
recognized as one of the major pathways for the transfer of harmful aquatic
organisms and pathogens around the world. Although ballast water has been
carried around the world for many years, interest in ballast water as a global
environmental problem has only attracted significant interest in recent years
with the documented establishment of a number of aquatic pest species. The
significance of the problem has been influenced greatly by the expansion in
worldwide shipping and reduced voyage times with some 12 billion tonnes of
ballast water now carried around the world annually. Scientific research
indicates that several thousand species are transported in the ballast water of
ships each day.
1.2.
Therefore, the need is emphasized for ballast water and sediment management
options to be taken into account when designing and building new ships and, in
this regard the shipping industry should be contacted for design
considerations. A range of suggested design considerations for new ships are
given in the guidance.
2. CONSIDERATIONS AT THE DESIGN PHASE OF NEW
SHIPS.
Ballast water management equipment.
2.1
Ballast water management and the processes chosen to achieve it should be
considered as a basic component of the ship's design.
2.2
Design and installation of the ballast water pumping and piping system should
ensure that the ease of operation and maintenance is maximized.
2.3
Ballast tank design should facilitate all aspects of ballast water management.
2.4
Installation of recording equipment should be considered for all ballast water
operations and treatment actions. It should be possible for these records to be
readily available to appropriate authorities that may request copies.
2.5
Remote data management should be considered.
2.6
Mechanisms should be designed into the equipment for ready analysis of system
performance.
2.7
A Ballast Water Management Plan should be created for the ship as the methods
used are established; in particular it should give guidance on safe and
effective operation of the various ballast water management and treatment
options that are considered appropriate for the ship.
2.8
The Ballast Water Management Plan should address training of the crew in the
ballast water management processes described therein.
2.9
Ballast water system designs should take special account of the increased need
for content sampling, with an aim to enhance the quality and ease of sampling
of ballast water and sediments, without the need to enter potentially dangerous
spaces or to partially fill ballast tanks.
Examples
of procedures and equipment are as follows:
.1 fitting of tanker
hatches, wherever possible, as an alternative to manholes to allow more ready
access to tanks;
.2 ensuring the area
immediately below any tank opening is kept free (to the extent possible) of
obstructions that may impede the lowering of sampling equipment;
.3 installation of sampling
pipes within air/breather pipes as an alternative to accessing tanks by
manholes or tanker hatches. Sampling pipes should be terminated at a convenient
location on the top or side of the air pipe, so that a sampling pump may be
easily fitted to the outlet;
.4 installation of stand
alone sampling pipes that directly penetrate into the ballast tanks with the
ends of sampling pipes located within tanks to ensure representative ballast
water samples are taken;
.5 fitting of a quick
release coupling on sampling pipes to permit the extraction of samples without
removing the manhole cover or opening the tanker hatch;
.6 providing safe access to
tanks (especially where access is not normally required);
.7 sounding pipe designs
should also be enhanced to facilitate taking representative samples;
.8 provision for in-line
sampling from either the ballast pump or some other point of the ballast
pipework, to permit sampling either during ballasting or deballasting operations;
and
.9 given the potential for
variability of flow within the ballast water pipework attention should be given
to ensuring uniform sampling, e.g., through use of a static mixer directly
ahead of the sampling pipe.
Ballast water exchange at sea.
2.10
Where Ballast Water Exchange at sea is the chosen method, the overall design
strength and stability of the ship should be sufficient to permit its execution
on all ballast voyages and in all except severe weather conditions. For the
guidance of the master, the maximum sea state and swell conditions identified
by the builder, if any, in which ballast water exchange can safely be carried
out should be recorded in the Ballast Water Management Plan.
2.11
The design of the ship should make it easy to achieve exchange at sea, by
reducing the demands upon other crew resources. In particular it should
endeavour to minimize:
.1 the number of operational
steps;
.2 the time taken, and
.3 the number of partially
loaded tanks and the duration of their partial loading, needed to complete a
ballast water exchange sequence.
2.12
The design of the ship should include consideration of the consequences of
ballast water exchange at sea including: stability, hull girder strength, shear
forces, resonance, sloshing, stemming, propeller immersion, limitations brought
about by insufficient strength in various parts of the ship when the tanks are
sequentially emptied and appropriate strengthening incorporated to allow this
operation to be conducted safely.
2.13
Where the sequential method of exchange is to be used, particular attention
should be given to the ballast tank layout, total ballast capacity, individual
tank configuration and hull girder strength. If the Plan requires
simultaneously emptying and refilling closely matched diagonal tanks then
consequential torsional stresses should be considered. Still water bending
moments, shear forces and stability should remain at or within safe limits.
2.14
Where the flow-through method of exchange is to be used adequate provision should
be made to avoid the risk of over pressurization of ballast tanks or ballast
piping. Enhancements in this regard may include the installation of additional
air pipes, installation of tanker hatches (as an alternative to deck manholes),
internal overflow pipes (to avoid water flowing over the deck) and
interconnecting ballast trunks between tanks where applicable and possible.
2.15
Where the dilution method of exchange is to be used adequate provision should
be made for appropriate piping arrangements to facilitate the loading of
ballast water and, simultaneously, the unloading of the ballast water at the
same flow rate. The hydrodynamic performance of the ballast tank is crucial to
ensure full water exchange and sediment scouring.
Ballast Water Treatment Systems.
2.16
Where a ballast water management system other than ballast water exchange is to
be used, equipment chosen should provide for complete treatment of all ballast
water including storm ballast water. A number of alternative treatment options
are under development for managing ballast water. Due consideration should be
given before selecting any system to the equipment and space requirements,
effectiveness in inactivating or removing aquatic organisms and pathogens,
environmental soundness, and to operational, maintenance and manpower
requirements. Adequate provisions should also be made for additional power
requirements.
2.17
Minimizing or removal of the risk to crewmembers whilst involving in the
ballast water operation should also be considered. This should include, but not
be limited to, exposure to machinery, entering enclosed spaces or working
excessive hours and training.
2.18
Where a treatment method using heat is to be used, the design should analyse
additional power demands and insulation requirements.
2.19
Where heat treatment of the ballast water using waste heat from the main engine
is contemplated, appropriate piping and pump arrangements should be installed
to facilitate the sequential flushing of the ballast water. If ballast water is
intended to remain at an elevated temperature for several hours to inactivate
harmful aquatic organisms and pathogens contained in sediments, attention
should be given to the consequences.
2.20
Where chemical and biocide treatments are envisaged the safety and
environmental aspects of stowage, storage and application of such substances
should be considered, in particular:
.1 the allocation of
appropriate storage areas (either on deck or adjacent to the ballast
pump/pipework area in the engine room or in a designated room), preparation
spaces and appropriate pipework fittings to allow the chemical/biocide to be
added by an appropriate metering and mixing system to the ballast water line;
and
.2 the Ballast Water
Management Plan should contain advice to ships' personnel on the safe handling
of toxic or corrosive chemicals carried on board for the purpose of dosing or
otherwise treating ballast water, taking into account any instructions issued
by the treatment system manufacturer.
2.21
Where filtration systems are envisaged adequate provision should be made for
their installation, maintenance and repair, including provision of adequate
replacement filters. Filtration systems should be sized so that they can be
operated at a reasonable capacity for ballast water use. Provision should be
made for the environmentally sound disposal of filter backwash.
2.22
Where cyclone type systems are envisaged adequate, provision should be made for
their installation, maintenance and repair. Cyclone type systems should be
sized so that they can be operated at a reasonable capacity for ballast water
use. Provision should be made for disposal of cyclone concentrates as for
filtration systems.
2.23
Installation of ultra-violet irradiation systems should pay due attention to
the need for some form of pre-filtration of the ballast water prior to
treatment.
2.24
Other potential treatment systems, e.g., ozonization, oxygen deprivation,
electroionization, will have specific installation, operation, maintenance and
repair parameters that will need to be addressed.
2.25
Any ballast water treatment system should incorporate adequate monitoring
systems to ensure its effective operation.
2.26
Where use of alternative water supplies other than seawater is considered then
appropriate deck and associated pipework to permit the loading of such water to
the ballast tanks should be taken into account.
Shore based or mobile treatment facilities.
2.27
Where consideration is given to ballast water loading or discharge using shore
based or mobile treatment facilities, installation of appropriate
infrastructure, such as booster pumps and associated pipe work on deck should
be taken into account with a view to practical and safe operations.
3. DESIGN CONSIDERATIONS TO ENHANCE
MANAGEMENT, CONTROL AND OPERATIONAL STRATEGIES.
3.1
Taking into account the need for the design of sea chests to minimize skin
friction of the ship's hull, generating laminar flow of water over the hull
form and facilitating good flow of water into the ship's seawater suction
pipes:
.1 consideration should be
given to the design of the sea chest grate openings as a primary filter of
larger marine organisms;
.2 securing arrangements
should minimize the potential for the sea grate to fall off during service,
e.g., by hinging the grate on the forward side;
.3 installation of systems
to allow for the cleaning and treatment of the sea chest following ballasting,
e.g., by installing a steam and air connection or piping from Butterworth tank
washing systems (used for cargo tank washing); and
.4 shutting of isolation sea
suction valves to prevent the