Focus on tighter particulate controls in LAPC minerals guidance

Final drafts of eleven revised guidance notes for minerals processes regulated under the local air pollution control (LAPC) regime were issued for consultation by the Department for Environment, Food and Rural Affairs in September.1 Their main impact will be to require tighter controls on particulate emissions - with the roadstone coating sector facing the highest upgrading bill of up to £45 million.

The consultation is the first in a programme to update guidance notes covering some 80 sectors which were originally issued in 1991-92 as the LAPC regime was brought into force under the Environmental Protection Act 1990.

The 17,000 or so processes regulated under LAPC will soon be shifted over to the successor LAPPC regime introduced by the Pollution Prevention and Control Act 1999, with minerals processes among the first to make the move next April. The changeover will be mainly a paper exercise, although permit reviews under the new system will normally be every six years instead of four.

The process of revising the guidance notes is some way behind the schedule announced by the Government at the end of 1999 (ENDS Report 299, p 42 ). The transfer of the Environment Department's Local Authority Unit to the Environment Agency appears to have contributed to the delay.

Under the original schedule, the final consultation on the minerals guidance notes was due in June 2000, so for that sector the process is 15 months late. DEFRA and the Agency recently bit the bullet and agreed a revised schedule for the remaining sectors (see table).

The longest postponement affects the coatings and solvents sectors. Final drafts of the guidance for these industries are not due for submission to DEFRA by the Agency until the end of next year - 21 months later than originally intended.

The eleven draft minerals notes are in a revised format which includes process descriptions and a summary of the main changes. They also contain regulatory impact assessments - although these vary in quality from comprehensive to very thin.

All the notes give a gentle push to operators to seek certification to the environmental management standards ISO14001 or EMAS. They suggest that it is "desirable" for companies to have "some form of structured environmental management approach", whether by obtaining certification or setting up a tailor-made environmental management system.

Regulators are advised to "use their discretion" in agreeing the "appropriate level of environmental management" with companies, but are also warned that it is "outside the legal scope" of LAPC permits to require an environmental management system "for purposes other than LAPC/LAPPC compliance."

The main thrust of the guidance is for stricter controls on particulates, reflecting the current concern about their effects on health and the need to comply with the current statutory air quality objectives for PM10 by 2004, and with the tighter standards proposed for later in the decade (see pp 34-35 ).

Under the existing guidance, most minerals processes have been operating to a particulate limit of 100mg/m3. This will be tightened up to varying degrees.

Most of the drafts would require dust filters on new silos to be designed to meet an "easily achievable" limit of 10mg/m3, with immediate effect. New silos would also have to be fitted with automatic protection systems to prevent overfilling.

Another standard requirement in most of the drafts is a design criterion of 50mg/m3 for dust arrestment plant with an exhaust flow of more than 100m3 per minute, with upgrading of most existing plant required by January 2003. Cement processes would have a year longer to comply, while the requirement would apply only to new plant in the coal and coke sector.

A third common requirement is an emission limit of 50mg/m3 for sources with exhaust flows of over 300m3/min. Upgrading of existing processes would generally have to be completed between 2003 and 2005. A longer deadline of 2012 has been pencilled in for lime and plaster processes, but it will be reviewed within two years for the lime sector with a view to setting a shorter phase-in period in the light of research on improved abatement technology.

There are other variations on the theme. For the quarry processes sector, for instance, the draft guidance says that a tightening of the new 50mg/m3 design standard for plant with an exhaust flow of over 100m3/min to 25mg/m3 is anticipated in a future revision of the guidance.

In the roadstone coating sector, a 25mg/m3 limit for particulates will apply immediately to new plant and replacement abatement plant. However, it is proposed that the sector should have until 2012 to upgrade existing plant to a limit of 50mg/m3. The same timetable will apply to mineral drying and cooling processes.

Special considerations apply to two sectors with more complex processes. For vermiculite and perlite processes, the draft guidance proposes a reduction in the current particulate limit of 150mg/m3 for exfoliators and expanders to 50mg/m3 by January 2005 - two years later than proposed in an earlier draft (ENDS Report 309, pp 40-41 ).

However, the industry is holding out for a limit of 100mg/m3. Its plant typically emits

40-50mg/m3, and with such a large margin against the current standard operators have generally been allowed to monitor their emissions just once every two years.

Bringing the limit down to 50mg/m3 would require a significant increase in monitoring frequency, with costs also rising because a new monitoring method is being proposed. Overall, costs may rise from £600 every two years to several thousand pounds per year, with stack alterations needed to accommodate the new monitoring method adding up to £10,000.

The industry wants the proposed 50mg/m3 standard to apply only to new or replacement plant. However, DEFRA points out that plant in the sector has a typical life of 20-40 years, and operations complying with the current limit have been "known to give rise to an accumulation of visible dust in the neighbourhood."

The china and ball clay industry has been more successful in resisting the earlier proposal to cut the particulate limit for most of its main processes from 100 to 25mg/m3. The revised target is 50mg/m3, with upgrading of most processes required by January 2007.

Cost considerations swung the argument. Bag filters would have been necessary on china clay driers to meet a limit of 25mg/m3, at a capital cost of £14 million and annual operating costs of £1 million. Additional drying capacity costing £10 million would also have been needed.

An environmental trade-off was also involved. The difference between a standard of 50 and one of 25mg/m3 is an annual emission of 250 tonnes of kaolin dust. But the extra energy consumption involved in meeting the lower standard would have resulted in additional carbon dioxide emissions of 20,000 tonnes per year. The industry is expected to use state-of-the-art wet scrubbing technology to meet the compromise standard.

Other particulate control measures are being added in selected sectors. The cement, coal and coke, quarry and mobile rock processing sectors will be required to ensure that no visible dust emissions cross the site boundary.

Additional dust monitoring, mostly using low-tech methods, will be required in the coal and coke handling sector following an official study which found that dust emissions from such sites can contribute to periodic exceedences of the air quality objective for PM10. 2Another measure intended to bring greater discipline to control of dust emissions is a requirement for recording of continuous monitoring data on sources with exhaust flows of over 300m3/min in the cement, clay and refractory goods, quarrying and vermiculite and perlite sectors. The necessary kit will cost around £3,000 per source.

The cement handling sector will bear the brunt of new controls on road tankers. Overpressurisation of silos from venting of tanker air through them is estimated to account for 60% of dust emissions from this source. The draft guidance would require some 800 tankers to be fitted with onboard relief valves and filtration systems, at a cost of £400-£1,000 apiece. The industry would have four years to comply.

Finally, sheeting of rail vehicles used by quarry processes will be required after an upgrading period of two years.

The benefits of all these proposals have been quantified in detail for just two sectors. In the roadstone coating industry, annual particulate emissions are expected to be cut from 3,965 tonnes at present to 2,070 tonnes by 2012. And a reduction of 800 tonnes is projected for the mineral drying and cooling sector over the same period.

Most of the dust from these sources is mainly PM10 and the overall reduction will be just less than 1% of national emissions.

The financial impact of the new guidance will be heaviest in the roadstone coating sector, which estimates that upgrading to the new standard will cost £40-£45 million. Upgrading mineral drying and cooling processes is projected to cost £4 million.

These two sectors are also facing a proposal which did not appear in earlier drafts. Waste or recovered oil is commonly used as a fuel in their furnaces, and the draft guidance includes a limit of 1ng/m3 on dioxin emissions for these sources. Annual testing will be required for compliance purposes.

There are few other changes to existing controls on other pollutants. Halving the fluoride limit of 10mg/m3 for the clay and refractory goods sector was considered but rejected. Process modifications have enabled many manufacturers to comply with the existing limit without add-on abatement equipment (ENDS Report 289, p 13 ). But a further reduction would require limestone scrubbers and their attendant waste and extra energy consumption.

In contrast, the fluoride emission limit for calciners in the china and ball clay sector is to be halved to 5mg/m3, and a new limit of 10mg/m3 for chloride from scrubbers added. A generous ten-year upgrading deadline is proposed, but this will be reviewed within two years in the light of research into abatement technologies.

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