Rhodia's Staveley plant is authorised to make chlorine, predominantly for use in domestic bleach.
On 3 November 2003, a storage tank was being inspected. It had been emptied of liquid chlorine, valves connecting it to the system being opened. But when the vessel was reconnected, the valves were not closed and a "small" leak occurred.
Site supervisors investigated the incident, but failed to find its cause, and, as a result, another leak occurred in the afternoon. Up to half a tonne of liquid chlorine was lost.
Six workers were affected by the leak, but Rhodia did not put the site's emergency plan into operation for 35 minutes. It was ambulance staff who alerted other emergency services to the incident (ENDS Report 349, p 40 ).
Once the alarm was raised, local residents had to stay inside for over three hours until the all clear was given.
A joint investigation by the Environment Agency and the Health and Safety Executive found that Rhodia had not conducted a risk assessment for the maintenance work. There was also a "lack of detail" in "written procedures" given to staff.
Speaking after the case, Agency enforcement officer Paul Salter said "a distinct lack of training, experience and supervision" caused the incident. "This is just not good enough, and local people as well as staff deserve better."
The leak was the latest in a string of incidents at the plant in recent years.
In 2002, the company received an enforcement notice after releasing an unknown quantity of mercury into the river Rother (ENDS Report 330, p 14 ). In 2001, meanwhile, it was the subject of another investigation by the Agency and the HSE after an unknown amount of sulphur trioxide escaped from the works (ENDS Report 315, p 11 ).
In 1999, the company was fined £13,000 for offences linked to mercury discharges from the plant (ENDS Report 299, p 58 ). Finally, an acid gas release in 1996 led to a £50,000 fine (ENDS Report 258, p 46 ).
The company does not have a certified environmental management system at the works.
The latest case was heard by Chesterfield magistrates in December. At the hearing, Rhodia pleaded guilty to one charge of failing to ensure the safety of its employees and another of failing to ensure the safety of the public, both contrary to the Health and Safety at Work Act 1974.
The magistrates did not feel they could impose a sufficient penalty for the charges and sent the case to crown court.
Appearing before Derby crown court on 11 February, the company was fined £100,000 - split equally between the two charges - with £19,902 costs.
Rhodia also pleaded guilty to a charge of failing to ensure that suitably trained and supervised personnel carried out maintenance work, contrary to sections 6(1) and 23(1) of the Environmental Protection Act 1990. It was not fined for this offence.
In mitigation, the company said it has now carried out a risk assessment to ensure such incidents do not occur again.
"Rhodia accepts that incidents of this kind should not occur and very much regrets the disruption it caused and the concern and distress experienced by residents and visitors to Staveley at the time," it said in a statement.
Following Rhodia's recent decision to sell its Staveley activities, chlorine production will finish in March, but sulphuric acid production will continue for up to two years.