(Regs 13.2.1 and 13.6.1 of Annex II of MARPOL)
(1) Division 2 does not apply to the discharge of water containing a prescribed residue from a ship if:(a) the discharge of the water containing that residue occurs when the ship is proceeding en route at a speed of:(i) at least 7 knots, if the ship is self-propelled, or(ii) at least 4 knots, if the ship is not self-propelled, and(b) the discharge occurs below the ship’s waterline through the ship’s underwater discharge outlets at a rate not exceeding the maximum rate for which each underwater discharge outlet is designed, and(c) the discharge occurs when the ship is at least 12 nautical miles from the nearest land and is in water at least 25 metres deep.
(2) This section does not apply in relation to a mixture that contains a liquid substance that is neither:(a) a noxious liquid substance, nor(b) a liquid substance referred to in Regulation 6.1.3 of Annex II of MARPOL.
(3) In this section:
"inspector" includes a surveyor appointed or authorised by the Government of a country that is a party to MARPOL for the purpose of implementing Regulation 16 of Annex II of MARPOL.
"prescribed residue" means a residue remaining after:(a) the tank of a ship that held a noxious liquid substance categorised as Category X under Regulation 6 of Annex II of MARPOL, or a mixture containing such a substance, has been:(i) emptied to the maximum extent in accordance with procedures in the ship’s procedures and arrangements manual, and(ii) cleaned in accordance with regulations made for the purposes of section 42, and(b) the resulting residues in the tank have been discharged to a reception facility until the concentration of that substance in the effluent to that facility is, in the opinion of an inspector, at or below the residual concentration prescribed for that substance in Regulation 13.6.1 of Annex II of MARPOL and until the tank is empty, and(c) the residue remaining in the tank has been subsequently diluted with water.