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Sediment Management in Ballast Water Management Plan on Ships

Sediment Management in Ballast Water Management Plan on Ships

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Water taken up as vessels’ ballast can contain solid alluvial matter that, once the water is becalmed in a vessel’s ballast tank, will settle out onto the bottom of the tank and other internal structures. Aquatic organisms can also settle out of the ballast water and can continue to exist within the sediment. These organisms can survive for long periods after the water they were originally in has been discharged. They may thereby be transported from their natural habitat and discharged in another port or area where they may cause injury or damage to the environment, human health, property and resources.

What are the sediment management requirements as per Ballast Water Management Plan on Ships?

  • All practical steps should be taken during ballast uptake to avoid sediment accumulation, it is however recognized that sediment will be taken on board and settle on tank surfaces.
  • The volume of the sediment should be monitored on a regular basis.
  • Sediment in ballast tanks should be removed in a timely basis and as found necessary. The frequency and timing of removal will depend on factors such as sediment build up, vessel’s trading pattern, availability of reception facilities, work load of the vessel’s personnel and safety considerations.
  • Removal of sediment from ballast tanks should preferably be undertaken under controlled conditions in port, at a repair facility or in dry dock. The removed sediment should preferably be disposed of in a sediment reception facility if available, reasonable and practicable. One should be aware that sediments lying undisturbed for some time may give off toxic gases and appropriate measures must be taken to protect the crew carrying out the job.
  • When sediment is removed from the vessel’s ballast tanks and is to be disposed of by that vessel at sea, such disposal should only take place in areas outside 200nm from land and in water depths of over 200m.
  • Part of the mud may be removed by water movement within a tank to bring sediments to suspension. In double bottom tanks this is achieved by filling clean water 0.5-1 meter sounding in mild weather conditions and keeping it for about 6 hours before pumping it out.
  • In addition, the Master may decide to store the sediments onboard the vessel when this will not hamper the security and operational maintenance of the vessel, her cargo and the crew. The sediments must then be disposed of as described in the above paragraph.
  • Special care is to be taken if ballast water has been carried in spaces designated for other purposes, such as fuel, oil, fresh water tanks etc. More stringent requirements for disposal of the sediments are to be considered depending upon the final mixture, e.g. if ballast water is carried in the fuel tanks.

Reference: Ballast Water Management Plan (BWMP)

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