Regulation 11 Category B and C residual mixtures—discharge
The discharge into the sea of a Category B residual mixture or a Category C residual mixture is prohibited except where all the following conditions are complied with:
all relevant requirements of regulations 7 to 10 have been complied with;
the concentration of the substance in, and the rate of discharge of, the effluent is in accordance with the procedures and arrangements specified in respect of substances of the category in question in the ship’s Procedures and Arrangements Manual;
the ship is proceeding at a speed of at least 7 knots in the case of a self-propelled ship or at least 4 knots in the case of a ship which is not self-propelled;
the discharge is made below the water line;
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; and
if the ship is in a Special Area and the substance in question is a Category B substance, the tank from which the discharge is made has been pre-washed (whether or not such pre-wash was required by regulation 9) in accordance with the procedure specified in the ship’s Procedures and Arrangements Manual for the substance in question and the resulting tank washings have been discharged to a reception facility; or
if the ship is in a Special Area and the substance is a Category C substance the maximum quantity of the substance discharged from any one tank and its associated piping system does not exceed the maximum quantity approved in the ship’s Procedures and Arrangements Manual for discharge of Category C substances in a Special Area.
Where a tank which contained a Category B or Category C residual mixture has been emptied by a discharge made in accordance with paragraph (1), water thereafter added to that tank may be discharged notwithstanding that the ship is not proceeding as required by sub-paragraph (1)(c), provided that all the other requirements of that paragraph are complied with.