The first spill occurred while oily ballast water was being transferred from a ship into oil separators on shore. Due to a combination of a leaking pipe and the failure of an automatic valve in a separator, 600 gallons of crude oil were discharged into the Thames estuary. The oil affected three-quarters of a mile of Holehaven Creek, oiled 70 birds and caused a large fish kill.
About 1,000 gallons of light crude were spilled four weeks later while a tanker was being unloaded. The operation had to be interrupted due to the tide, and when it resumed an employee opened the wrong valve, allowing oil from a storage tank to escape into the estuary, where it oiled 60 birds.
The third spill occurred when a leak in a heat exchanger allowed raffinate, a waxy oil by-product, into the cooling water system. An oil/water separator then became clogged, allowing several gallons of raffinate to escape and coat the eastern shore of Holehaven Creek. The cause was traced to a drain plug which should have been made of stainless steel, but corroded within six months because it was made of the wrong material.
At a hearing before Grays Magistrates in March, Mobil pleaded guilty to three charges of polluting controlled waters. It was fined £15,000 for each of the first two incidents, and £10,000 for the third. It was also ordered to pay costs of £520.