577 



assessed as such or ballast water, tank washings, or other residues or 

 mixtures containing such substances shall be prohibited. If tanks con- 

 taining such substances or mixtures are to be washed, the resulting 

 residues shall be discharged to a reception facility until the concen- 

 tration of the substance in the effluent to such facility is at or below 

 the residual concentration prescribed for that substance in column III 

 of Appendix II to this Annex and until the tank is empty. Provided 

 that the residue then remaining in the tank is subsequently diluted 

 by the addition of a volume of water of not less than 5 per cent of 

 the volume of the tank, it may be discharged into the sea when all 

 the following conditions are also satisfied : 



(a) the ship is proceeding en route at a speed of at least 7 

 knots in the case of self-propelled ships or at least 4 knots in the 

 case of ships which are not self-propelled ; 



(b) the discharge is made below the waterline, taking into ac- 

 count the location of the seawater intakes ; and 



(c) the discharge is made at a distance of not less than 12' 

 nautical miles from the nearest land and in a depth of water of 

 not less than 25 metres. 



(2) The discharge into the sea of substances in Category B as de- 

 fined in Eegulation 3(1) (b) of this Annex or of those provisionally 

 assessed as such, or ballast water, tank washings, or other residues or 

 mixtures containing such substances shall be prohibited except when 

 all the following conditions are satisfied : 



(a) the ship is proceeding en route at a speed of at least 7 knots 

 in the case of self-propelled ships or at least 4 knots in the case 

 of ships which are not self-propelled ; 



(b) the procedures and arrangements for discharge are ap- 

 proved by the Administration. Such procedures and arrangements; 

 shall be based upon standards developed by the Organization and 

 shall ensure that the concentration and rate of discharge of the 

 effluent is such that the concentration of the substance in the wake 

 astern of the ship does not exceed 1 part per million ; 



(c) the maximum quantity of cargo discharged from each tank 

 and its associated piping system does not exceed the maximum 

 quantity approved in accordance with the procedures referred to- 

 in sub-paragraph (b) of this paragraph, which shall in no case 

 exceed the greater of 1 cubic metre of 1/3,000 of the tank capacity 

 in cubic metres ; 



(d) the discharge is made below the waterline, taking into- 

 account the location of the sea water intakes ; and 



(e) the discharge is made at a distance of not less than 12 

 nautical miles from the nearest land and in a depth of water of 

 not less than 25 metres. 



(3) The discharge into the sea of substances in Category C as de- 

 fined in Regulation 3(1) (c) of this Annex or of those provisionally 

 assessed as such, or ballast water, tank washings, or other residues or 

 mixtures containing such substances shall be prohibited except when 

 all the following conditions are satisfied : 



_ (a) the ship is proceeding en route at a speed of at least 7 knots 

 m the case of self-propelled ships or at least 4 knots in the case 

 of ships -v^hich are not self-propelled ; 



