Guidance on Significant Modifications

What is a Significant Modification?

‘Significant modification’ describes modifications encompassed by Regulations 12 and 24 of the COMAH Regulations. It covers modifications, potentially having significant consequences for major-accident hazards, to:

• Installations
• Establishment
• Storage facilities
• Processes
• The nature or physical form or quantity of dangerous substances
• Tier status

In such circumstances the operator must review, and if necessary update, the:

• Notification
• MAPP
• Safety management system
• Safety report

and the competent authority must be notified in advance.

Guidance Document

The purpose of the guidance is to steer operators of COMAH establishments through the significant modification assessment, submission and evaluation processes. It will help them determine if contemplated changes fall into the significant modification category and if so, the information that should be prepared and sent to the CCA in advance of the modification schedule.

The guidance also sets outs how the CCA will assess significant modifications, through a number of worked examples.

Guidance on Significant Modifications under the COMAH Regulations