No. 13 - Interpretations of MARPOL Annex IV
(For the complete regulation see Wet voorkoming verontreiniging door schepen and MARPOL Annex IV)
The Netherlands Shipping Inspectorate is responsible for the enforcement of the ‘Wet voorkoming verontreiniging door schepen’ and the belonging regulations.
This law refers dynamically to the MARPOL Convention 1973
Application
Annex IV contains regulations for the prevention of pollution by sewage from ships. The provisions of this Annex shall apply to the following ships engaged in international voyages:
- new ships of 400 gross tonnage and above; and
- new ships of less than 400 gross tonnage which are certified to carry more than 15 persons; and
- existing ships of 400 gross tonnage and above, after September 28th 2008
- existing ships of less than 400 gross tonnage which are certified to carry more than 15 persons, after September 28th 2008
Ships to which the annex applies are in possession of a certificate.
Interpretation unmanned pontoons more than 400 GT
The annex is not applicable for unmanned pontoons of more than 400 GT
Description
A new ship is a ship build on or after September 27th 2003.
Existing ships the keels of which are laid or which are of a similar stage of construction before October 2nd 1983 shall be equipped, as far as practicable, to discharge sewage in accordance with the requirements of regulation 11 of the Annex.
Sewage systems
Every ship, which is required to comply with this Annex, shall be equipped with one of the following sewage systems:
- a sewage treatment plant which shall be type approved by the organisation1;
- a approved sewage comminuting and disinfecting system, with sufficient storage capacity;
- a holding tank of sufficient capacity. The holding tank shall have means to indicate visually the amount of its contents;
- in all cases a standard discharge connection conform Annex IV Reg 10.
Interpretation visually indication the amount of its content
The use of a sounding rod is not allowed because of hygienic reasons.
Interpretation minimum contents of holding tank
Volume of sewage in litres per person per day
| | Without vacuum plant | With vacuum plant |
| | Black water | Grey and black water | Black water | Grey and black water |
| Passenger ships | 70 | 230 | 25 | 185 |
| Other ships | 70 | 180 | 25 | 135
|
The content of the sewage tank should be enough for three days as a minimum, unless there are circumstances justifying a smaller capacity
Discharge of sewage
The discharge of sewage into the sea is prohibited, except when:
- the ship has in operation an approved sewage treatment plant
- the ship is discharging comminuted and disinfected sewage at a distance of more than 3 nautical miles from the nearest land or sewage which is not comminuted and disinfected at a distance of more than 12 nautical miles from the nearest land
- the ship operates in the waters under the jurisdiction of a state in accordance with such less stringent requirements as may imposed by such state.
Discharge of sewage that has been stored in holding tanks shall not be discharged instantaneously but at a moderate rate when the ship is en route and proceeding at not less than 4 knots. The rate shall be approved by the administration according to IMO resolution MEPC.157(55).
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Note
This instruction (in the form of an interpretation) was already in use from the date of entry into force of MARPOL Annex IV. In this version there are two amendments.
- The standard discharge connection should always be present independent of the way of treatment or storage.
- For hygienic reasons, from the date of entry info force of this amendment a sounding rod is not allowed in order to determine the contents of the sewage tank.
This instruction enters into force from August 1st 2009
1 . Refer to the Recommendation on international effluent standards and guidelines for performance tests for sewage plants adopted by resolution MEPC.2(VI). For existing ships, national standards are acceptable.