Rate this article:  

Loss Prevention Circular No. 06-01

Oily water separation and discharge: 

Risk of oil pollution versus vessel's safety



As part of our overall loss prevention activities, Gard Services regularly monitors port State detentions from the Paris Memorandum of Understanding (MoU), Tokyo MoU and United States Coast Guard (USCG).  In 2000, there was a total of 131 detentions of ships entered in the Gard P&I portfolio. Oily water separation and discharge related items were the single most frequent deficiency cited.  Similar results were also observed in the detention of vessels entered in the Gard Marine portfolio for 2000 (147 detentions and the second most cited deficiency).  We are not satisfied with these figures.  As a result, we believe it is necessary to revisit this issue for Gard Services Members and Clients.


The article "Discharge of oil prohibited", which appeared in Gard News issue No. 152 (December 1998/February 1999) (also reproduced as Gard Loss Prevention Circular 07-01) warned against the implications of pumping oil and oily bilge water overboard, and was followed by another article on the same topic in Gard News issue No. 155 (September 1999/November 1999), titled “Risk of oil pollution versus vessel’s safety”.  The present circular contains a summary of that second article, which we hope will assist Members and Clients in staying vigilant in light of the potential costs associated with an incident, fines, port State detentions and the safety implications related to oily water separation and discharge.


Environmental and safety matters


Oily water separator

During condition surveys of vessels, the Association normally notes that Masters and Chief Engineers enforce a strict policy regarding pumping of bilge water, in order to avoid any oil spill. Port State control officers inspect engine room pipelines and oily water separating equipment to ensure compliance with the MARPOL regulations. Fines and detentions are not popular. To guard against accidentally pumping overboard engine room bilge water which has not been cleaned, shipside valves are sometimes chained and padlocked or lines are even blind flanged, all in an effort to reduce the risk of an oil spill. At times, such remedies are requested by port State control officers, and are willingly installed by the ship's crew.

All efforts to avoid polluting the seas and coastal areas are appreciated, of course, but it should be noted that there is also an overriding issue involved: the safety of the vessel in an emergency situation. In case of water ingress and flooding of the engine room or the cargo holds, the vessel needs a fully working and readily operational bilge pumping system. Therefore, the overboard connections from the bilge pump should not be blocked by locked hand wheels, blank flanges or by removed spool pipes. It should be noted that SOLAS, Chapter II-1, Regulation 21, as well as relevant Class rules, require a vessel to be equipped with a bilge pumping system that should be operational under all practical conditions. In case of a sudden flooding of the engine room, the bilge pumping system must be able to be started without undue delay.


So is there a problem in complying with both MARPOL and SOLAS? Not really, if one keeps in mind that the MARPOL 73/78 regulations are meant for non-emergency operational situations. In Annex I of MARPOL 73/78, Regulation 9 deals with the control of oil discharge and Regulation 10 covers methods for prevention of oil pollution from ships within a special area, but Regulation 11 provides exceptions from both, in the case of an emergency. The exceptions under Regulation 11 are the following: "Regulation 9 and 10 shall not apply to:


Oily water separator

(a) the discharge into the sea of oil or oily mixture necessary for the purpose of securing the safety of a ship or saving life at sea; or

(b) the discharge into the sea of oil or oily mixture resulting from damage to a ship or its equipment:

(i) provided that all reasonable precautions have been taken after the occurrence of the damage or discovery of the discharge for the purpose of preventing or minimising the discharge; and

(ii) except if the owner or the master acted either with intent to cause damage, or recklessly and with knowledge that damage would probably result; or

(c) the discharge into the sea of substances containing oil, approved by the Administration, when being used for the purpose of combating specific pollution incidents in order to minimise the damage from pollution. Any such discharge shall be subject to the approval of any Government in whose jurisdiction it is contemplated the discharge will occur."


In view of Regulation 11, MARPOL and SOLAS are not in conflict with each other and it is important that all authorities inspecting a vessel for compliance with MARPOL understand this.


Overboard line for cleaned bilge water from the oily water separator. The hand wheel has been chain locked by the vessel's Chief Engineer at the request of port State control authorities. A seal has also been fitted to the chain.

Blocking the overboard pipe from the main bilge pumps should never be done, as this would seriously affect the safety of the vessel and would be in conflict with SOLAS and Class requirements. In the interest of the coastal States, at times port State control officers seem to pay more attention to the MARPOL regulations than to the corresponding SOLAS regulations. A conflict of interest may occur when the bilge pump of a vessel is also used for ballast water and in some cases even for emptying a sump tank. Oil remains in the pipeline may not be large in quantity, but will put harbour authorities on full alert if inadvertently pumped overboard with ballast water. In some such cases port State authorities have required blanks inserted in the pipeline or the locking of valve handles. This may secure against oil pollution, but as pointed out, may reduce the safety of the ship in an emergency situation.


Overboard valve for main bilge/ballast line. The hand wheel has been fitted with a chain and padlock at the request of the port authorities. This is not a good practice as the vessel's bilge pumping system is no longer readily operational.

On the other hand, there should be no excuse for pumping oil overboard through pumps serving a dual purpose. It should always be ensured that all pipelines, whether used for clean bilge or ballast water, are free from oil contamination prior to using the bilge/ballast pumps for direct overboard discharge. Such verification should be included in the operational procedures.


It should also always be clear to a vessel's crew that sludge tanks, waste oil tanks and oil drain tanks are not allowed to have any direct connection overboard (MARPOL 37/78 Annex I, Regulation 17(3)). and that the content of such tanks must be discharged to reception facilities ashore through the standard discharge connection required (MARPOL 37/78 Annex I, Regulation 19), if not disposed of in an incinerator on board. If required by harbour authorities, pipelines from such tanks may be closed off to prevent oil pollution, but not the overboard pipeline from the main bilge pump.


In case Members face conflicting requirements from various authorities concerning the issues addressed above, they should always consult the vessel's Class Society, which has approved the vessel's bilge pumping system and normally has also issued the International Oil Pollution Prevention Certificate. In any case, all changes to a vessel's bilge system should always be informed in advance to the vessel's Class Society, for proper approval.