The 1991 regulations prescribed both the processes and substances to which the two new systems apply. They also set deadlines for existing industrial processes to be brought under control.
The amending regulations came into force on 1 April, and apply throughout Britain. They are mostly intended to clarify errors and anomalies discovered in last year's rules.
The most significant change concerns the definition of combustion processes regulated by HM Inspectorate of Pollution under IPC.
Under the 1991 rules, a process fell within IPC if it comprised the burning of fuel in a boiler, furnace, gas turbine or compression ignition engine with a net rated thermal input of 50MW or more. In addition, however, where two or more boilers or furnaces with an aggregate capacity of 50MW or more were installed in such a way that their waste gases could be emitted through a common stack, they too were deemed to fall within IPC. The same aggregation rule applied separately to gas turbines and compression ignition engines.
Under the revised rules, however, it will no longer be necessary for the gases from two or more combustion plants on the same site to be capable of being discharged through a common stack for them all to come within IPC. From now, a site will qualify for IPC if it has boilers and furnaces with an aggregate net rated thermal input of 50MW or more, provided they are operated "by the same person at the same location." Only plants of less than 3MW are to be disregarded when the aggregate capacity of all boilers and furnaces on a site is calculated. Similar rules apply to gas turbines and compression ignition engines.
Operators of these installations have been given until 1 July 1992 to apply for an IPC authorisation.
Another amendment in the combustion plants sector has made it clear that reheat and heat treatment furnaces used for heating metals prior to further processing fall under local authority air pollution control. This was previously open to doubt because they fell in a list of processes "carried on primarily for the purpose of producing energy." A draft guidance note spelling out the controls which will apply to such furnaces has now been issued for consultation by the Department of the Environment.2 Operators will have only until the end of June to apply for authorisations.
In the waste disposal sector, the new regulations make it clear that incinerators burning animal remains are subject to control if they meet the qualifying 50 kilograms per hour design threshold. And the definition of "waste" has been amended to exclude "gas produced by biological degradation of waste", in turn excluding landfill gas flares from the local authority control system (ENDS Report 203, pp 20-1).
Other amendments affect the non-ferrous metal and wood processing sectors, waste oil recovery operations, the testing of aircraft and other engines, and uranium processes carried out at licensed nuclear installations.