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5.41 OVERFLOWS AND SPILLS

Even of no oil enters the sea, a cargo tank or contaminated ballast tank overflow should be considered a reportable incident under the owner's loss control programme. Only be evaluation of all incidents will the necessary lessons be learned by management and crew and the necessary changes in procedures made to reduce the potential for future incidents. An overflow which does not escape over the side of the ship may not be a spill reportable to the authorities, but in many cases it is only through good fortune that it does not result in pollution. If the lessons of overflow incidents are not used to change procedures, then costly spills will inevitably occur in the future.
The crew will not report non-polluting overflows if disciplinary action is taken each time such a report is made. The crew can only be encouraged to report incidents if the owners use the information constructively, including involving the crew in the discussions of how similar incidents are to be prevented.

Case study
A tanker of 135,000 DWT was leaving Mizushima, Japan after discharging a cargo of Indonesian light crude, when oil was observed coming up from the vessel's port quarter. A quick check carried out by the ship's crew found no obvious cause for the discharge and the vessel proceeded on her departure for Singapore. Meanwhile, analysis was conducted by the Japanese Marine Safety Agency (MSA) and indicated that the oil had come from the vessel. The tanker was intercepted before clearing Japanese waters and was charged with contravening pollution laws. Neither the subsequent MSA investigation, nor one undertaken on behalf of the owner at Singapore, could provide a satisfactory explanation of how the discharge might have occurred.
Nevertheless, based on the MSA findings, large monetary claims were presented against the tanker's owners for cleaning up the estimated two to three tonnes of Rabi crude which contaminated the seaweed cultivation areas of nine local fishery cooperatives.

Case analysis
Continuous monitoring of the berth area must be part of the tanker's deck watch routines while in port. Special vigilance is required when starting the cargo discharge operation and after changing the setting of any of the sea valves, or sea block valves in the pumproom. Keeping a close watch over the berth water near the pumproom is particularly important when starting the ballast operation and each time a cargo pump is started.

5.41.1 Notice of berth contamination
The ship's officers and deck crew must also be vigilant for the presence of oil in the berth from other sources. The berth should be carefully examined when the ship first arrives to see that it is clear of oil from previous transfers. A good lookout should be maintained upstream, or up-tide while discharging, to detect the approach of any oil from other sources. If oil contamination is noted, it must be immediately reported to a terminal representative and to the harbour authorities (via the agent or directly by VHF radio), indicating in the report that the oil is not from the reporting ship. If a substantial oil spill enters the berth, the ship should make an effort to collect and retain in refrigerated storage, samples of the slick for later analysis. The physical evidence of samples will permit the owner and P&I Club to prove that it did not originate from the vessel. There have been cases where tankers where accused of an oil spill which was later proven (through analysis of samples collected by the tanker), to be passenger ship fuel. In another incident, a tanker found itself surrounded by oil which had overflown the terminal's waste oil treatment unit because of heavy rains.

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