When the Sea Empress ran aground off Milford Haven at 2007 hours on 15 February 1996, it caused the third largest oil spill in UK coastal waters. The 72,000 tonnes of crude discharged over the next six days placed the incident among the 20 largest spills ever, and required a massive clean-up operation over several weeks.
A conference in Cardiff next week aims to assess the environmental damage caused by the incident, the efficacy of the clean-up operation and what may be learned for dealing with such incidents in future.
The Marine Pollution Control Unit was set up in 1978 to take charge of operations to deal with pollution at sea and coordinate onshore clean-up operations with local authorities. It is responsible for putting the Government’s National Contingency Plan for such accidents into action within minutes. Where the shoreline is polluted, the unit will set up a Joint Response Centre with local authorities to direct onshore operations.
With an incident of the size of the Sea Empress, the task was formidable. At its peak, it involved 19 aircraft, 56 vessels – including two oil-recovery vessels from France and one from the Netherlands – and more than 1,000 people.
‘This workforce had to be put together in hours almost, certainly days,’ says Chris Harris, chief executive of the Coastguard Agency, who was the overall commander of the operation. ‘It was a major collaboration between Government, local authorities and the private sector.’
The main point of debate in the post mortem of the operation was whether the MPCU should have exercised its powers of intervention under the Merchant Shipping Act of 1995 to take direct operational control of the salvage operation. It was the failure of the earlier attempts to secure the vessel and salvage its cargo that was responsible for the severity of the spill.
The initial grounding of the tanker released between 2,000 and 6,000 tonnes of crude. Harbour tugs refloated the damaged vessel and held it anchored in the channel approaching the port. Worsening weather foiled a plan to bring a second tanker alongside to transfer the cargo. Three salvage tugs tried to turn the Sea Empress around to face the storm but the winds and the tide proved too much. The tugs’ cables broke on 17 February and the tanker drifted on to rocks off St Ann’s Head, where it disgorged oil before each low water up to 20 February.
Harris is not sure that the MPCU being in direct control would have led to a different outcome, but he does think it is vital to learn all there is to know about tidal behaviour before attempting such operations. ‘When you’ve got a ship in that predicament, you need to make sure that the local knowledge is brought to bear.’
There were also some lessons to be gleaned from the use of chemical dispersants, which break the oil into small droplets which are eventually degraded by the naturally occurring bacteria in the water. Some environmentalists fear the dispersants may themselves damage the environment, but they remain the MPCU’s first line of defence on the basis that dispersion at sea reduces the threat of pollution to marine life, amenity beaches and other coastal interests.
The aerial spaying of 446 tonnes of seven different chemicals and natural dispersion got rid of about half the 72,000 tonnes spilt and meant that only about 10% washed up on the coastline. ‘What we can say is the spraying of dispersant at sea did hugely reduce the amount of oil that came ashore,’ says Harris.
In contrast to the speed with which the MPCU wheeled into action, the setting up of the body to assess the environmental impact of the spill was slow. As with the Braer incident off the Shetland Islands a year earlier, it took two months to establish the Sea Empress Environmental Evaluation Committtee to coordinate and integrate a programme of studies, about 80 in total.
Ron Edwards, the retired Cardiff University professor who is chairman of the committee, feels strongly that one important lesson to be learned is the need for the environmental assessment operation to move into action with comparable speed to the emergency response. In stark contrast to the National Contingency Plan, ‘there is no clear drill and no clear techniques’.
He says this seriously impedes the task of assessing impact on the environment: ‘It’s the weeks immediately after the spill that are so crucial.’ He firmly believes an equivalent body to the MPCU should be set up for the task. ‘This must be the responsibility of one agency.’
Edwards says the main conclusion about the environmental impact of the spill is that natural factors combined to limit the damage: the unusual direction of the wind (blowing offshore into the Irish Sea), the light composition of the crude oil cargo (which meant that 40% of the spill evaporated), and the time of year (most fish species were not in the area or not feeding, while birds such as puffins and auks had not yet arrived). ‘We were damned lucky.’
Edwards says the other issues that need addressing for future incidents include arrangements for disposing of oily wastes. There were several thousand tonnes of such material and the nearest landfill was 160km away. Temporary storage facilities are also required, but there are no regulations enabling these to be set up rapidly in an emergency.