The incident occurred just a week after the EA had released data in its 1998 report showing that oil is now the most frequent cause of pollution in England and Wales, having overtaken sewage as the most frequent cause. A large oil spill from a storage tank costs around £30,000 to clean-up, compared with £500 for a bunded tank.
The EA has now estimated that around 7,500l of oil was released at Cardiff, and is making enquiries in the area focusing on businesses known to have oil storage tanks.