Plume grounding saga continues at Castle Cement's Ribblesdale works

Long-running problems with odour and plume grounding from Castle Cement's Ribblesdale works appear to be continuing, despite a prosecution of the company for breach of its integrated pollution control (IPC) authorisation. The saga raises questions over the Environment Agency's regulatory approach and its ability to force the upgrading or closure of ageing plant.

Castle Cement's works at Ribblesdale in Lancashire has been a thorn in environmental regulators' side since 1992 when the company first pioneered the use of chemical waste as an alternative fuel. The use of these fuels attracted strong criticisms from parts of the local community - and drew attention to the grounding of plumes from the site's kilns.

In 1997, the House of Commons Environment Committee accused the Agency of "lax regulation" of the site (ENDS Report 266, pp 30-32 ). Just before the report was published, the Agency inserted a tough condition into Castle's IPC authorisation stipulating that "there shall be no persistent haze or odour which cause offence present at ground level outside of the site boundary." The move was seen as an attempt to draw the sting from the Committee's report.

In 1998, Castle fitted a scrubber to its dry kiln, the most modern of three kilns on the site, to reduce emissions of sulphur dioxide, thought to be the main cause of the odour problem. The scrubber reduced the number of public complaints - but failed to solve the problem caused by the site's two older wet kilns (ENDS Report 287, pp 10-11 ).

The Agency's failure to tackle emissions from the wet kilns left it highly exposed. In 1997, a high-ranking official at the Environment Department wrote to the regulator saying that Ministers "felt it was essential that the Agency take a tough enforcement line, using this condition, if there was not a dramatic improvement in the pollution performance of the plant following the installation of the scrubber."

In 2000, the Agency took Castle to court for breaching the authorisation condition forbidding haze and odour. Local residents complained of being exposed to "sulphurous" fumes "like burning paint". The company was fined £45,000 and ordered to pay costs of £76,600 (ENDS Report 306, p 48 ).

Incidents of plume grounding and public complaints about haze and odour have continued. In 2003 - six years after the Agency imposed its condition - the regulator received 176 complaints, 105 concerning haze or odour. Despite this, the Agency has taken no enforcement action against Castle since the prosecution.

In April 2003, the Agency issued a new integrated pollution prevention and control (IPPC) permit for the site - and weakened the persistent haze and odour condition. Castle must ensure that emissions are "free from offensive odour and persistent haze" - but "shall not be taken to have breached this condition if [it] has used best available techniques (BAT) to prevent, or where that is not practicable, to reduce, such emissions."

John Isherwood, the inspector for the Ribblesdale works, said the Agency had doubts over the enforceability of the previous condition. He maintained that the condition "remains as robust as it was before."

Mr Isherwood said that the Agency accepted the company's BAT argument that the old kilns could not achieve strict emission limits without significant investment. Castle intends to close the kilns by the end of 2005, subject to a new kiln coming on stream at its Padeswood site in North Wales.

Mr Isherwood said that the Agency has had "considerable success in driving complaints down". Castle is required to conduct regular monitoring for potential haze and odour and either reduce the kilns' output, or shut them down, if necessary. Such action occurred on 31 occasions in 2003 and twice so far this year.

The Agency's approach to the closure of the old kilns raises some important questions. It appears that the regulator allowed the old kilns to continue without abatement - and the plume grounding problem to continue - because Castle initially said it would mothball them in 2001. However, the company has kept the kilns in operation because of delays to its Padeswood plant caused by a public inquiry.

The Agency has also reduced the number of complaints dramatically by refusing to respond to calls from Mary Horner, a local resident and campaigner. The Agency says Mrs Horner has been responsible for over half of all complaints.

"As a publicly-funded organisation, we cannot continue to devote so much time and resources on a single complainant," the Agency said. "Responding to repeated complaints from a single individual, when we have already investigated thoroughly and have no new evidence to consider, cannot be considered the best use of taxpayers' money."

In a statement, Castle's general manager at Ribblesdale Gareth Price, said: "Ribblesdale carries out off-site observations on plume dispersion from its kilns twice a day. If the plume is seen not to be grounding but it is considered that it may be likely to ground at some later time, then extra monitoring is carried out...If observation suggests that plume grounding is likely, then the Environment Agency is immediately informed and Castle Cement takes all necessary action.

"Complaints have reduced steadily since 2001 when off-site observations were started," Mr Price went on. "The plume-related complaints have reduced from 260 in 2001 to 162 in 2003 and in the year to date, the company has received 26."

The two old wet kilns have burned Cemfuel, a fuel derived from chemical waste, almost continuously since 1992. The more modern dry kiln also burns Cemfuel and has recently been permitted to burn chipped tyres. In addition, Castle has applied to burn meat and bone meal waste in the dry kiln, potentially increasing the amount of energy derived from waste fuel up to some 90%.