In August 1991, a pipe on a newly installed waste oil heating system ruptured at a site in West Drayton, near Heathrow Airport. The installation, which was not complete at the time of the incident, was being carried out by Benninghoven UK for asphalt suppliers Bardon London.
About 30,000 litres of oil escaped overnight, overwhelming the site's oil interceptors and entering a local watercourse, the Bigley ditch, through surface water drains. The oil caused extensive pollution and coated ducks and wildfowl, many of which subsequently died.
The National Rivers Authority (NRA) charged both firms under section 85(1) of the Water Resources Act 1991 for causing polluting matter to enter controlled waters. Both pleaded not guilty at a hearing before Uxbridge magistrates in March.
The trial lasted six days as the companies called technical experts to testify on the characteristics and operation of waste oil heating systems. The salient points were that the system had a vibration problem which probably contributed to the failure and it was operated overnight by Bardon London against Benninghoven's instructions.
Both firms were found guilty. In allocating the fines the court appears to have apportioned two-thirds of the blame to the installer and one-third to the operator. Benninghoven was fined £16,000 with costs of £5,810, while Bardon London was fined £8,000 with cost of £2,905.