Oily bilge water discharge at anchor: a faulty 15 ppm alarm and a full holding tank
MT Naija Spirit is a 6,500 dwt product tanker anchored 8 nautical miles off Lagos, waiting for a berth. The bilge holding tank is nearly full after engine-room work. The chief engineer tells the junior engineer to use the oily water separator to discharge about 4 m³ of bilge water overboard before the NIMASA inspection team arrives. The 15 ppm bilge alarm has been faulty for three days, and the sample glass shows a cloudy discharge. The oil record book has no entry for the last four days. The chief says the vessel is outside port limits, the discharge is small, and the separator has been serviced, so it will be fine. The junior engineer is unsure and asks for your advice.
1. Is the proposed discharge permitted under MARPOL Annex I? Explain your reasoning.
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No. Under MARPOL Annex I, machinery-space bilge water outside a special area may be discharged only when the ship is underway, more than 12 nautical miles from the nearest land, the oil content is below 15 ppm, and the discharge goes through the required oily water separator and 15 ppm alarm. The vessel is at anchor 8 nautical miles off Lagos, so it fails both the distance and the underway requirement.
The faulty alarm and cloudy sample are separate failures. Even if the ship were beyond 12 nautical miles and underway, a defective 15 ppm alarm means the discharge cannot be controlled and verified. The absence of oil record book entries also indicates that the record is not being maintained. The chief engineer's argument that the discharge is small does not create an exemption. National requirements may be stricter, and NIMASA can detain or prosecute for an illegal discharge. The junior engineer should not operate the separator for overboard discharge in these circumstances.
2. What should the junior engineer do immediately, and how should the situation be escalated?
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The junior engineer should decline to make the discharge and should not open the overboard valve or run the separator to sea. The reason should be stated clearly: the ship is at anchor within 12 nautical miles, the 15 ppm alarm is defective, and the record is incomplete. The junior engineer should inform the chief engineer that they are not refusing maintenance but refusing an illegal discharge, and should request that the bilge water be retained on board.
If the chief persists, the junior engineer should inform the master and, if necessary, the company designated person ashore. The master has the authority and duty to stop an illegal operation. The bilge holding tank should be secured and monitored, and the separator should be isolated and tagged until repaired. The immediate practical solution is to retain the bilge water for shore reception or for a compliant discharge later, not to dilute or hide it. Retaliation should not deter the report; the safety management system should protect the person who raises the concern.
3. What records and corrective actions should follow?
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The oil record book should be completed truthfully for the retained bilge water and for any previous operations that were omitted, but entries must never be backdated or fabricated. The faulty 15 ppm alarm should be reported as a deficiency, repaired and tested, with the repair recorded in the maintenance system. The overboard valve should be secured and the separator clearly marked as unavailable until the alarm is proved working. If any discharge has already occurred, the master should report it under the company's environmental reporting procedure and consider notification to the flag State and port State as required.
Corrective action should include a review of why the chief engineer proposed the discharge, a crew briefing on MARPOL Annex I limits, and a check that enough bilge holding capacity is planned for port stays. The company should verify that the oil record book is audited regularly and that the designated person ashore is accessible. The aim is not only to fix the alarm but to remove the pressure that made an illegal shortcut seem normal.