MEPC 55/23 

 

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ANNEX 2 

RESOLUTION MEPC.150(55) 

Adopted on 13 October 2006 

GUIDELINES ON DESIGN AND CONSTRUCTION TO FACILITATE 

SEDIMENT CONTROL ON SHIPS (G12) 

THE MARINE ENVIRONMENT PROTECTION COMMITTEE, 

RECALLING Article 38(a) of the Convention on the International Maritime 

Organization concerning the functions of the Marine Environment Protection Committee 

conferred upon it by the international conventions for the prevention and control of marine 

pollution, 

RECALLING ALSO that the International Conference on Ballast Water Management for 

Ships held in February 2004 adopted the International Convention for the Control and 

Management of Ships’ Ballast Water and Sediments, 2004 (the Ballast Water Management 

Convention) together with four Conference resolutions, 

NOTING that Regulation A-2 of the Ballast Water Management Convention requires that 

discharge of ballast water shall only be conducted through Ballast Water Management in 

accordance with the provisions of the Annex to the Convention, 

NOTING FURTHER that Regulation B-5.2 of the Ballast Water Management 

Convention provides that, ships constructed in or after 2009 should, without compromising 

safety or operational efficiency, be designed and constructed with a view to minimize the uptake 

and undesirable entrapment of sediments, facilitate removal of sediments, and provide safe 

access to allow for sediment removal and sampling taking into account Guidelines developed by 

the Organization, 

NOTING ALSO that resolution 1 adopted by the International Conference on Ballast 

Water Management for Ships invited the Organization to develop these Guidelines as a matter of 

urgency, 

HAVING CONSIDERED, at its fifty-fifth session, the draft Guidelines on design and 

construction to facilitate sediment control on ships developed by the Ballast Water Working 

Group, and the recommendation made by the Sub-Committee on Bulk Liquids and Gases at its 

tenth session, 

1. ADOPTS the Guidelines on design and construction to facilitate sediment control on 

ships as set out in the Annex to this resolution; 

2. INVITES Governments to apply the Guidelines as soon as possible, or when the 

Convention becomes applicable to them; and 

3. AGREES to keep the Guidelines under review. 
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ANNEX 

GUIDELINES ON DESIGN AND CONSTRUCTION TO FACILITATE SEDIMENT 

CONTROL ON SHIPS (G12) 

1 PURPOSE 

1.1 Regulation B-5.2 of the Convention requires that ships described in Regulations B-3.3 

to B-3.5 should, without compromising safety or operational efficiency, be designed and 

constructed with a view to minimize the uptake and undesirable entrapment of sediments, 

facilitate removal of sediments and provide safe access to allow for sediment removal and 

sampling, taking into account these Guidelines. Ships described in Regulation B-3.1 of the 

Convention should, to the extent practicable, also comply with Regulation B-5.2 taking into 

account these Guidelines. 

1.2 The purpose of these Guidelines is to provide guidance to ship designers, ship builders, 

owners and operators in the development of ship structures and equipment to achieve the 

objectives of paragraph 1.1 and thereby, reduce the possibility of introducing harmful aquatic 

organisms and pathogens. 

1.3 There may be a conflict between preventing accumulation of sediments and preventing 

the discharge of harmful aquatic organisms and pathogens. 

2 INTRODUCTION 

2.1 Water taken up as ships’ ballast can contain solid alluvial matter that, once the water is 

becalmed in a ship’s ballast tank, will settle out onto the bottom of the tank and other internal 

structures. 

2.2 Aquatic organisms can also settle out of the ballast water and can continue to exist within 

the sediment. These organisms can survive for long periods after the water they were originally 

in has been discharged. They may thereby be transported from their natural habitat and 

discharged in another port or area where they may cause injury or damage to the environment, 

human health, property and resources. 

2.3 Regulation B-5.1 of the Convention requires that all ships remove and dispose of 

sediments from spaces designated to carry ballast water in accordance with the Ballast Water 

Management Plans. These Guidelines are to assist ship designers, ship builders, owners and 

operators to design ships to minimise the retention of sediment. Guidance on the management of 

sediment is contained in the Guidelines for Ballast Water Management and the Development of 

Ballast Water Management Plans (G4). 

3 DEFINITIONS 

3.1 For the purposes of these Guidelines, the definitions in the International Convention for 

the Control and Management of Ships’ Ballast Water and Sediments (the Convention) apply.
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3.2 Ballast Water Tank – for the purposes of these Guidelines a ballast water tank is any 

tank, hold or space used for the carriage of ballast water as defined in Article 1 of the 

Convention. 

4 DESIGN FOR REDUCING ACCUMULATION OF SEDIMENT 

4.1 Ballast water tanks and their internal structure should be designed to avoid the 

accumulation of sediment in a ballast tank. The following should, as far as is practicable, be 

taken into account when designing ballast tanks: 

.1 horizontal surfaces to be avoided wherever possible; 

.2 where longitudinals are fitted with face bar stiffeners, consideration should be 

given to fit the face bar stiffeners below the horizontal surfaces to aid drain off 

from the stiffeners; 

.3 arrange for induced flows of water, either by pump forces or gravitational forces, 

to wash along horizontal or near horizontal surfaces so that it re-suspends already 

settled sediment; 

.4 where horizontal stringers or webs are required, drainage holes to be as large as 

possible, especially if edge toe-stops are fitted where horizontal stringers are used 

as walkways, to encourage rapid flow of water off them as the water level in the 

tank falls; 

.5 internal girders, longitudinals, stiffeners, intercostals and floors, where fitted 

should incorporate extra drain holes which allow water to flow with minimal 

restriction during discharge and stripping operations; 

.6 where inner members butt against bulkheads, their installation should be such as 

to prevent the formation of stagnant pools or sediment traps; 

.7 scallops should be located at the joints of the inner bottom (tank top) longitudinals 

or intercostals and floors to allow for good airflow, and thus drying out of an 

empty tank. This will also allow air to escape to the air pipe during filling so that 

minimum air is trapped within the tank; 

.8 pipeline systems should be designed such that, when deballasting, disturbance of 

the water in the tank is as powerful as possible, so that the turbulence re-suspends 

sediment; and 

.9 flow patterns in ballast water tanks should be studied (for example by the use of 

Computational Fluid Dynamics (CFD)) and considered, so that internal structure 

can be designed to provide effective flushing. The amount of internal structure in 

double bottom tanks will reduce the scope for improving flow patterns. The 

hydrodynamic performance of the ballast tank is crucial to ensure sediment 

scouring. 
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4.2 Any designs depending upon water flow to re-suspend sediment should, as far as possible 

be independent of human intervention, in order that the work load of ships’ crews is minimal 

when operating the system. 

4.3 The benefits of design concepts for reducing sediment accumulation are that there is 

likely to be good sediment removal while deballasting, with minimum retention of sediment in 

the tanks, and therefore a reduction or no need for removal by other means. 

4.4 The design of all ships should provide safe access to allow for sediment removal and 

sampling. 

4.5 The design of ballast water tanks should facilitate installation of high sea suction points 

on each side of the tank. 

4.6 When practical, equipment to remove suspended matter at the point of uptake should be 

installed.

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