- Sea Empress
- Accident date
- United Kingdom
- Accident area
- Milford Haven passage
- Spill area
- Cause of spill
- Product transported
- Light crude oil
- Quantity transported
- 130,824 tonnes
- Nature of pollutant
- Light crude oil
- Quantity spilled
- 73,000 tonnes
- Ship / structure type
- Oil tanker (Single hull)
- Built date
- Astilleros Cadix
- 274.3 m
- 43.24 m
- 15.8 m
- Sea Tankers, Cyprus
On the evening of 15 February 1996, a Liberian oil tanker, the Sea Empress, with a load of 130,824 tonnes of Forties crude (light crude from fields in the North Sea) en route for the Texaco refinery in Milford Haven, ran aground on the rocks at Saint Ann’s Head at the entrance to Milford Haven Bay (this location includes a number of refineries providing the UK with 25 % of its requirements in refined products).
This was the second grounding of a tanker in the space of 5 months after the Borga on 25 October 1995. Unlike the Borga, the Sea Empress had been built very recently (1993) but was only a single hull tanker. According to experts, the reason for this casualty lies in misjudgements of tidal currents and a communication breakdown between the pilot and the commanding officer.
Timeline of events between 15 February and 7 March 1996
After the alert, a contingency plan was implemented by the British Maritime and Coast Guard Agency (MCA). Meanwhile, the MPCU (Marine Pollution Control Unit) sent three DC-3s with dispersant spraying equipment and OSRL (Oil Spill Response Ltd) sent three trailers with shore response equipment, two storage barges, an Egmopol skimmer barge and a Hercules C130 fitted with an ADDS Pack for spraying dispersants. However, the prime objective was still to keep the vessel afloat and transfer the cargo as quickly as possible.
On the 16th, the Star Bergen (a 30,000 dwt tanker) made an initial attempt at transferring the cargo and was assisted in this by tugs from Liverpool and Ireland.
On the 17th, weather conditions worsened (40 knot winds) and the authorities decided to turn the vessel to face into the wind and the swell, with the assistance of seven tugs. Two towlines snapped in quick succession and the tanker ran aground yet again at 6:05 pm close to the previous location. The tanker had already lost a thousand tonnes of cargo since the 15th.
On the 18th, the Russian crew and the experts were air-lifted off the vessel by a Royal Air Force Sea King helicopter at 5:30 am due to the storm. Winds were westerly force 8 and wave height was 4 to 5 metres, which damaged the tanker. Later in the evening, the tanker was refloated with the assistance of three tugs, the Anglian Earl, the Anglian Duke and the De Yue, a Chinese high sea tug from Falmouth.
Overnight, the Anglian Duke and the Anglian Earl held the tanker fast. Seven thousand tonnes of crude had been spilled since 17 February.
On the 19th, the tanker ran aground again at 12:00 pm near Channel Rock. Six tugs managed to pull her off the rocks by the end of the afternoon, but she grounded again by the stern just outside the Channel near Saint Ann’s Head. At this juncture, her starboard wing and centre tanks were holed.
Of the 24 tanks on board only three were left intact. The pumping room was flooded but the engine room was dry thus affording the vessel full propulsion capability.
On the 20th, nine tugs attempted to refloat the tanker at high tide (the highest tide of the month) but failed in their attempt and the situation grew steadily worse. Twenty thousand tonnes of crude had been spilled since the 19th.
On the 21st, two more attempts were made at refloating the tanker, one at 07:30 am and another at 9 pm, with 12 tugs including a few sent from Holland by SMIT. The tanker was finally refloated at 10 pm, after inert gas had been pumped into her wing tanks. Although the inert gas injections enhanced the refloating operation, they also caused more serious spillages, bringing the total to about 70,000 tonnes. The tanker was towed overnight to Herbrandston Jetty, a disused oil wharf in the former Esso refinery in Milford Haven. After berthing, responders circled the tanker with floating containment booms.
Cargo transfer began on 23 February, once the hull had been thoroughly inspected, and ended on 4 March after four transfer operations involving the Star Bergen and the Onward Mariner, recovering 58,200 tonnes of crude oil in all. The tanker was towed to Belfast for repairs on 27 March.
Bulletin d'information du Cedre N°7 : "Pollution du Sea Empress au Pays de Galles"
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