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(5) Ventilation procedures approved by the Administration may be used to 
remove cargo residues from a tank. Such procedures shall be based upon stand- 
ards developed by the Organization. If subsequent washing of the tank is neces- 
sary, the discharge into the sea of the resulting tank washings shall be made in 
aecordance with paragraph (1), (2), (3) or (4) of this Regulation, whichever is 
applicable. 
(6) The discharge into the sea of substances which have not been categorized, 
provisionally assessed, or evaluated as referred to in Regulation 4(1) of this 
Annex, or of ballast water, tank washings, or other residues or mixtures contain- 
ing such substances shall be prohibited. 
CATEGORIES A, B AND C SUBSTANCES WITHIN SPECIAL AREAS 
Subject to the provisions of Regulation 6 of this Annex— 
(7) The discharge into the sea of substances in Category A as defined in 
Regulation 3(1) (a) 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. If tanks containing such substances or mixtures 
are to be washed the resulting residues shall be discharged to a reception facility 
which the States bordering the special area shall provide in accordance with 
Regulation 7 of this Annex, until the concentration of the substance in the effluent 
to such facility is at or below the residual concentration prescribed for that sub- 
stance in column IV 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 total volume 
of the tank, it may be discharged into the sea when all the following conditions 
are also satisfied : A 
(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 ; 
(0) the discharge is made below the waterline, taking into account the lo- 
cation 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 the 25 metres. 
(8) The discharge into the sea of substances in Category B as defined in Regu- 
lation 3(1)(b) of this Annex or of those provisionally assessed as such, or bal- 
stances shall be prohibited except when all the following conditions are satisfied : 
last water, tank washings, or other residues or mixtures containing such sub- 
stances shall be prohibited except when all the following conditions are satisfied : 
(a) the tank has been washed after unloading with a volume of water of 
not less than 0.5 per cent of the total volume of the tank, and the resulting 
residues have been discharged to a reception facility until the tank is empty : 
(0) the ship is proceeding on 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 ; 
(c) the procedures and arrangements for discharge and washings 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 concen- 
tration of the substance in the wake astern of the ship does not exceed 1-part 
per million; 
(d) the discharge is made below the waterline, taking into account the 
location of the seawater 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. 
(9) (he discharge into the sea of substances in Category C as defined in Regu- 
lation 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 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 approved by the 
Administration. Such procedures and arrangements shall be based upon 
standards developed by the Organization and shall ensure that the concentra- 
