Control of Major Accident Hazards

The Seveso II Directive on the control of major accident hazards involving dangerous substances requires that operators of prescribed major hazard sites 'take all measures necessary to prevent major accidents and to limit their consequences for man and the environment'. The Directive is implemented in Northern Ireland by the Control of Major Accident Hazards Regulations (Northern Ireland) 2000.

Threshold quantities above which the Regulations apply are listed for a range of named dangerous substances and also for some classes of substances including 'toxic', 'explosive', 'flammable' and 'dangerous for the environment'. The Regulations are enforced by a Competent Authority comprising the Health and Safety Executive for Northern Ireland (HSENI) and us.
We are responsible for assessing measures to protect the environment under the Regulations. This includes examining operators' safety reports and carrying out inspections on establishments covered by the regulations.

Storage of gas in natural strata – application of the Control of Major Accident Hazards Regulations (COMAH)

The on-shore storage of natural gas in underground natural strata is now subject to COMAH.

The COMAH Competent Authority (comprising of the Health and Safety Executive (Northern Ireland) and the Northern Ireland Environment Agency) has recently concluded that the on-shore storage of natural gas in underground natural strata, such as depleted reservoirs, is subject to the Control of Major Accident Hazards Regulations 1999 (COMAH). This decision was effected from 26 February 2009.

The decision follows an announcement by the European Commission in October 2008 that it expects Member States to apply the Seveso II Directive (96/83/EC) to such storage sites to ensure that equivalent regulatory requirements apply across the European Union. The Directive is implemented in Northern Ireland through the COMAH Regulations.

Underground storage sites will come within the scope of COMAH if the quantity of natural gas stored meets or exceeds the thresholds in Schedule 1, Part 2 of the Regulations i.e. 50 tonnes (lower tier) and 200 tonnes (top tier). In practice, all sites are likely to be top tier sites.

The decision means that the same regulatory regime applies to storage in man-made (salt) caverns and natural strata.

Further information on COMAH and the Seveso II Directive are available on HSE’s website.