The COMAH Competent Authority (comprising of the Health and Safety Executive, Environment Agency and the Scottish Environmental Protection 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 Great Britain 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.
HSE is already contacting the sites affected by this decision and will be clarifying guidance for dutyholders over the coming months.
The decision means that the same regulatory regime applies to storage in man-made (salt) caverns and natural strata.
The primary safety duties will be demonstrated through COMAH, but the Borehole Sites and Operations Regulations 1995 still apply and may require further consideration subject to the activity on the site.