Reprinted with permission of Environmental Information Bulletin, August 1997, Industrial Relations Services, Eclipse Group Ltd.

The Environment Agency has belatedly recognised that communication and consultation are an essential element of its work, especially when it is dealing with complex and potentially controversial issues.

Learning Lessons from the Cement Kilns Saga


The Environment Agency (EA) has been strongly criticised by community and environmental groups and by the House of Commons Environment Select Committee over its approach to the burning of secondary liquid fuels, derived from waste solvents, in cement kilns. Yet reliable evidence from abroad, as well as the Agency's own data, indicate that this is the best practicable environmental option (BPEC) for these wastes, while the Environment Committee itself recognised that existing regulatory regimes and emission limits are adequate and that there have been economic benefits to the cement and solvent recovery industries from the burning of waste-derived fuels. This article outlines the history of secondary liquid fuels in cement manufacture and the scientific evidence on its environmental impacts. It also examines the Agency's response to the Environment Committee's criticisms.

Earlier This Year, the Environment Agency (EA) was slated by the House of Commons Environment Committee over its approach to the burning of what the Agency terms secondary fuels (SF) in cement kilns. The Committee said that poor procedures and clumsy handling on the part of the Agency and, formerly, Her Majesty"s Inspectorate of Pollution, were largely to blame for the poor public perception of the burning of SF in cement kilns.

The Committee criticised the EA for "many serious inadequacies" in monitoring and data analysis, inconsistent application of risk assessment methodology, inefficiency, and lack of foresight. It also accused Agency inspectors of “automatically believing" what the industry had told them.

The Agency has responded positively to the report' and has accepted many of its 26 recommendations through a 12 -point programme (see box) -It has also resolved to be more open and to improve its communications, especially with the public and local media. In issuing the response, Dr David Slater, director of environmental protection at the EA, said: "The actions which the Agency has identified will lead to stronger and more consistent regulation of the cement industry. We hope that this will help alleviate public concern over the industry - in particular the burning of waste fuels. The Agency is committed to strong regulation to ensure that both the environment and the public are protected. It will also ensure that the public is consulted on these issues and will consider concerns raised during this consultation."

The Government has contributed to the debate with the publication of its own response- to the Environment Committee's report, focusing on the report's criticisms of the Agency. The Government says that it "is deeply concerned that the Committee should have felt it necessary to make such criticisms". The Environment Minister, Michael Meacher, has sought, and obtained, Agency assurances that it is committed to controlling industrial pollution "in a manner which will command the full confidence of Parliament and the public".

Nevertheless, the Agency rejects some of the Environment Committee's criticisms, particularly over its data monitoring and analysis and the independence of its inspectors, and it defends the burning of SF in cement kilns as being no worse, environmentally, than burning coal alone. The Agency believes it has evidence to counter the strongest criticisms made by the Environment Committee, and it considers that in some instances facts have been misinterpreted and key issues have been misunderstood.

Two decades of evidence

About 20 years ago, cement manufacturers and waste producers in the US turned to SF to solve two problems: the waste industry needed an alternative to landfilling and incineration for the disposal of waste solvents, while the cement industry needed to reduce its energy costs.

Trials were begun to ensure that the environmental risks posed by burning a mixture of coal and SF in cement manufacture were no greater than burning coal on its own. The common practice was to mix a conventional fuel - such as coal - with around 30% to 40% of SF The results showed that burning SF did not increase emissions and, in many instances, reduced them, while the procedure offered the added benefit of reducing the environmental impacts associated with landfills and incinerators. Furthermore, it became apparent that the burning of SF stabilised the process of cement production.

In the early 1980s, amidst fears over dioxin emissions, environmental groups started campaigning against the use of SF, so the US Environmental Protection Agency (EPA) responded by doing more research on emissions and on the risks posed by cement kiln dust (CKD).

On the whole, the American data show that waste fuel burns cleaner than coal in cement kilns. "The data from the US certification of compliance tests conducted in 1992 on 34 kilns overwhelmingly demonstrates the effectiveness of cement kilns to safely destroy organic, combustible wastes and recover the energy in these wastes. Measured emissions are generally orders of magnitude below US EPA limits," says David Gossman of Gossman Consulting Inc (GCI), a specialist in the cement industry with extensive experience of alternative fuels.

The data for emissions of some trace metals and dioxins, both here and overseas, do not appear as clear cut. However, this is because the levels emitted are so small it is difficult to detect any statistically-significant differences.

According to the US Air & Waste Management Association's (A&WMA) Air pollution control manual, the use of SF as a fuel and a raw material in cement kilns is a reliable and proven technology, offering a cost-effective, safe and environmentally sound method of resource recovery for many types of hazardous and non-hazardous wastes. The manual states that cement kilns have several important features that contribute to the effective destruction of waste materials: high residence times; high temperatures; thermal stability; lots of turbulence; an alkaline environment as an acid buffer; and the useful property of cement clinker to bind and immobilise potential contaminants.

Benefits of SF for cement

There are lots of data to show that the use of SF can benefit cement manufacture. Secondary fuel combustion is easier to control than that of coal, which means that production is more stable. The environmental benefit of this is that it decreases the chances of so-called "trips", which occur when carbon monoxide accumulates in the kiln and, for safety reasons, the electrostatic precipitators are momentarily turned off. This results in a puff of untreated particulate emissions.

Another benefit is that chlorine in the SF can reduce the alkali content of cement clinker. "Alkalis can weaken a cement, so we need to add chlorine to the ingredients to mop it up. In fact, there is a regulation in the UK for cement works, which specifies a minimum amount of chlorine in the mixture. So if we did not have any chlorine in the SF, then we would need to add it," explains Richard Boarder, general manager at Castle Cement. Many manufacturers throughout the world used to add chlorine, in the form of calcium chloride, before they started using SF There is no evidence to show that there are environmental or safety risks posed by this practice.

Metals are mainly immobilised within the cement, although trace levels could be emitted from the kiln stacks. Chlorine in SF has been alleged to form dioxin, although there is no firm evidence to show that dioxin is created from SF during cement manufacture. According to David Gossman, "The US data show that while monitoring teams have measured trace emissions of dioxin from the stacks serving cement kilns -whether they burn coal alone, or add SF to it - the evidence suggests in some cases that the dioxin was present in the raw materials."

Secondary fuels in the UK

The history of SF in the UK echoes the American experience in many ways, especially in the driving forces and the actual data from emissions monitoring. Public perception, however, is important. One of the first plants in the UK to use SF was Castle Cement's Ribblesdale works at Clitheroe, which has a long history of environmental complaints, mainly due to incidents of premature plume grounding. This did not help the company when it announced its intention to use SF. The perception among a significant group of Clitheroe residents is that they are being poisoned by emissions from a clandestine hazardous waste incinerator.

With the benefit of hindsight, the Agency now agrees that it underestimated media interest in the issue and the need for greater openness and communication with local residents.

The EAs approach

When the Agency first received applications from cement manufacturers to burn SF, "it took a practical and realistic approach to the issues", says David Constans of GCI. "What the Agency did was ask if the emissions using SF were any worse than they would be from burning coal alone,"' adds David Gossman., "and they wanted to know about our experiences in the USA and elsewhere. Their view was quite simple. They took a practical, scientific approach, and wanted measurements of the emissions from plants burning both coal., and a mixture of coal and SF under realistic conditions." What the Agency conspicuously failed to do was communicate effectively with outside parties, leading to intense opposition to the burning of SF in cement kilns.

A pragmatic approach to BPEO

Although the Agency accepts the Environment Committee's criticisms of its public consultation and communication strategy, it takes issue with its conclusions in other areas. For example, the Committee suggested that the Agency had adjusted its BPEO methodology to favour SF when assessing integrated pollution control (IPC) applications and during SF trials. The Committee's report also states that the data upon which the Agency based its decisions were inadequate, and that its inspectors were credulous in their dealings with the cement industry. At a recent IBC conference on secondary liquid fuels", Don Munns, the Agency's national manager for IPC regulatory policy, firmly refuted the suggestion that the Agency had adjusted data to favour SF. He explained, "We have developed our BPEO methodology considerably since we assessed the first IPC application for SF, and the latest methodology takes into account the latest research in this area. In other words, we have improved the methods for calculating the BPEO, and it is simply good science to take into account the latest research. So the method itself has improved.

Waste or fuel?

The EA’s view is that, although it considers SF to be a waste, the actual definition is immaterial since its impacts are assessed on a purely scientific basis. In other words., if the emissions - and other environmental impacts - are equal to, or less than, the emissions from burning coal alone, then the classification itself decreases in importance. But the view of Friends of the Earth (FoE), and others., is that, if SF is classified as a waste, the Agency should require cement kilns to fit the same types of emission controls as specialist hazardous waste incinerators.

Don Munns responds, "We already do this using a pro rata system of applying, emissions limits. The recent guidance notes on cement manufacture and the EU Directive on waste incineration are quite clear about this. If a cement kiln burns 40% SF, then the emissions limits are adjusted on a 40% pro rata basis."

The incinerator industry advocates that an incinerator is the appropriate place to burn SF supporting its case by comparing emissions from specialist incinerators to those from cement kilns burning SF. Such comparisons are, however, spurious because the two types of plant are not burning the same substance. A more realistic comparison would look at the emissions produced by burning coal and coal plus SF in both an incinerator and a cement kiln. More importantly merchant incinerators are designed to produce low emissions because they are burning substances that are much more hazardous than SF.

Monitoring data

Another of the Committee's criticisms was that the Agency's data were insufficient to make a proper assessment of SF's environmental impacts, and that it had failed to apply a rigorous statistical approach to data analysis. In response, the Agency says that it commissioned extensive testing., and also required cement manufacturers to install continuous emissions monitoring for SO, NO, and particulates. And, last autumn, the Agency commissioned a study of air quality in and around Clitheroe***.

This study used state-of-the-art monitoring techniques, including a differential absorption LIDAR to monitor 3-D profiles of the plumes from Castle Cement's kilns. When these monitoring data were linked to complaints from local residents, the Agency was able to produce unequivocal evidence which showed that the complaints were not connected with the burning of SF. Nor was the premature plume-grounding problem connected to SF combustion.

In summary, the monitoring study showed that air quality in Clitheroc is good for most of the time, with many of the problems caused by traffic. The premature plume-grounding problem does cause localised increases in emissions of particulates and, possibly, S02. The Agency is now forcing Castle Cement to install control equipment to dramatically reduce these emissions.

The Environment Committee had also criticised the adequacy and statistical significance of the Agency's data. However, the emissions monitoring and sampling cited by the Committee were neither as simple nor as inadequate as its report suggests. For example, the emissions measured for determinants such as metals and dioxins were near to the detection limits of the monitoring techniques, so the results have a high variance. Whilst it might appear easy to overcome this by taking an enormous number of samples, comprehensive methodology trials carried out by the US EPA show that this does not necessarily decrease the variance to justify it. So the Agency - like other regulators - optimises monitoring by taking representative samples.

Partisan inspectors

One of the Environment Committee's most damning criticisms, for a regulator that is meant to be impartial, was that Agency inspectors were partisan in their dealings with the cement industry. FoE has also accused inspectors of being sympathetic to the industry. The EXs Dr Slater disagrees strongly with such suggestions and stresses that, while the Agency needs to maintain a dialogue with those it regulates, it is ready and willing to take firm action when needed.

Richard Boarder of Castle Cement also disagrees that the Agency is partisan, commenting, "we have seen a definite move from persuasion to prosecution." The Agency is prosecuting Castle Cement this summer over alleged breaches of its emissions limits at the Clitheroe plant, and recently issued an enforcement notice to another of Castle's plants in Wales. Nor did it cede to the company s request for a relaxation of its SF specification.

Blue Circle Cement would also dispute that the Agency is sympathetic, after the Agency recommended that the company should withdraw two applications to burn SF "We were not satisfied with the data and suggested that they reapply when they had more data to support their application," says Don Munns.

Independent US consultant, David Constans of GCI, which helped Rugby Cement with its IPC variation to burn SF says: "The regulatory personnel are experienced and professional. This is reflected in their understanding of the current and proposed activities and in the questions they ask." In his view, the Agency has approached the burning of waste materials in cement kilns from a very practical stance, as an activity that must be regulated and investigated.

David Gossman observes: "Those cement companies which have had the least amount of trouble are those that have spent the time and effort to educate their workers and the local people in what is being done. This requires a number of meetings and a lot of explanation, and includes setting up a group of local leaders, with which representatives of the cement company meet regularly to answer questions and to deal with rumours and misrepresentations. Note, however, that these meetings will often include complaints that have nothing to do with the use of the waste fuel but have to do with how the operation of the cement plant impacts the community. The plant must be prepared to address these concerns as well. It is helpful if the government environmental agency actively participates in these meetings. However, if the people perceive that the agency is in the least way favouring business, then this participation will be of negative value."

The EA has taken note.

* "The environmental impact of cement manufacture: third report of the House of Commons Environment Committee", HC 124-1, available from The Stationery Office, ISBN 0 10 215297 7, tel: 0171 873 9090, price £12.50. † Copies available from Jeff Hockley, Environment Agency, Steel House, 11 Tothill Street, London SW1H 9NF, free.

** "The Government response to the Environment Select Committee report on the environmental impacts of cement manufacture", ISBN 0 10 136922 0, Cm 3692, available from The Stationery Office, price £2.00 †† “Secondary liquid fuels in kilns", 24 June 1997, IBC UK Conferences Ltd, tel: 0171 637 4383.

*** "Air quality monitoring in the Clitheroe area of Lancashire", available from Steve Devitt, Environment Agency, Lutra House, Dodd Way, Walton Summit, Bamber Bridge, Preston PR5 8BX, free.

This article was written by Dr Richard Gould, an independent consultant and writer on environmental technology.

Actions which the EA Is taking In response to the Environment Committee report


Public consultation