BP Oil appeared at Luton magistrates court on 16 February and was fined £8,000 with £3,536 costs after earlier pleading guilty to causing polluting matter to enter groundwater, contrary to section 85(1) of the Water Resources Act 1991.
The pollution was discovered in 2006 while BP was carrying out a ground condition survey in preparation to end its lease of the Kingfisher service station in Leagrave, near Luton.
Samples showed the land had been contaminated by hydrocarbons. An investigation revealed a small leak in an underground petrol storage tank, which was installed in 1987 and had a single skin. Industry practice is now to fit double-skinned designs.
BP stopped using the tank, but did not report the pollution to the Agency until November 2006 - three months after it was discovered. This was despite the site being located above a major chalk aquifer used for water supply and designated as a category three groundwater source protection zone.
The Agency has concluded there is no threat to drinking water supplies. The nearest drinking water borehole, owned by Three Valleys Water, is two kilometres away.
Agency groundwater sampling found the carcinogen benzene - a constituent of petrol - at levels thousands of times above the UK drinking water standard.
BP told the Agency it did not know when the leak started or how much fuel had been lost. It did not routinely pressure test the tanks and relied on stock monitoring by a specialist company to detect leaks.
But stock monitoring is not accurate enough to detect leaks of less than nine litres per day. The Leagrave leak was estimated to be just six litres per day.
The Agency said it was disappointed BP did not have more effective safeguards to prevent leaks given the location’s sensitivity.
BP is remediating the site under a programme agreed with the Agency at a cost of £320,000. The substantial clean-up costs appear to have influenced the fine’s size.
Nevertheless, it is small compared to those for similar offences. In 2002, BP was fined £60,000 for a leak in Luton (ENDS Report 333, p 54 ). TotalFinaElf was also fined £54,000 for leaks from a site in Hampshire (ENDS Report 328, pp 59-60 ).
Although the Agency often complains penalties are insufficient to deter large companies from polluting, it declined to criticise the outcome of this case.