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November 11, 2009

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COMAH- The waiting game

COMAH-site operators who wait until the last minute to review their Safety Reports are missing out on the valuable information this exercise can provide, and could be putting their sites, their workers, and others at risk, warns Caroline Stoker.

Every company that owns and operates a top-tier major-hazard installation will — or should — be aware that, under regulation 8 of the Control of Major Accident Hazards Regulations 1999, they are required to review their Safety Reports “at least every five years”. The key word here is ‘review’; full re-submission of the Safety Report is neither obligatory nor, in many cases, necessary. What many companies fail to appreciate, however, is that reg.8 is much broader then the five-year review; it also requires operators to undertake a formal review of their Safety Report in the following instances:

  • in response to new facts, or to take account of new technical knowledge about safety;
  • whenever the operator makes a change to the safety management system that could have significant repercussions, with respect to the prevention of major accidents, or the limitation of the consequences of major accidents to people and the environment; and
  • in advance of any proposed modification to the establishment or an installation, the process carried out, or the nature or quantity of dangerous substances present, and where that modification could have significant repercussions, as above.

Consequently, the majority of companies wait until the five-year deadline approaches before dusting off their Safety Report and starting the review process — but this could be putting themselves and others at risk.

A change is as good as a risk

The fact is that whenever changes are made to plant, equipment, systems, or personnel, there is always the potential for new associated risk. Most companies understand and have management systems in place to capture the major changes, such as large capital projects, new raw materials, new product introductions, or changes to inventory levels, and hence update their COMAH Safety Reports accordingly. What is more difficult to grasp is that seemingly insignificant changes to plant, people, software, etc, which are not usually captured by the change-management system, can have significant consequences.

Take, for example, a large terminal complex, which submitted its COMAH Safety Report to the Competent Authority two years ago. Since then, very little has changed in terms of new equipment. However, following a failure, they replaced an actuated valve in a tank-feed pipeline with a ‘similar’ one, albeit a slightly different specification to the original. The new one is fail-open on loss of compressed air, whereas the original unit was fail-closed. At the same time, an experienced member of staff retired, and a new maintenance team was contracted.

On the face of it, these seem quite ordinary changes, and quite independent of each other. But look at it in another way: since the new valve is not exactly the same as the one it replaced, it might compromise the original design intent; the replacement for the retired employee may not be privy to the original design and the fact that the valve in question forms part of a Safety Instrumented System protecting against overfill; similarly, the new maintenance team may propagate this error by subsequently replacing other inlet valves to the new specification.

Over time, systems on which the company previously relied and for which it claimed credit in its original COMAH Safety Report no longer offer the same level of risk reduction, the ultimate consequence of which could be escalation of a minor event into a major accident.

Remember the repercussions

So, how do operators successfully identify minor changes, or series of changes, that may have ‘significant repercussions’? And just how significant is significant? The COMAH Competent Authority1 has given a degree of guidance by stating that “a change will have significant repercussions with respect to the prevention or control of major accidents if it changes the nature of the major-accident risks, so requiring changes in the measures taken to ensure that those risks remain as low as reasonably practicable (ALARP)”.

Whether a change has significant repercussions is largely dependent on the degree to which it:

  • introduces a new major accident hazard;
  • changes the risk from an existing hazard; or
  • affects control or mitigation measures (including off-site emergency plans).

Examples of these could be:

  • changes to the Safety Management System (SMS), such as amending the permit-to-work system;
  • replacement of staff with third-party contractors; 
  • de-manning and/or combining roles;
  • changes in procedures; or
  • plant modifications.

In terms of changes to the Safety Management System, a review should take place as soon as possible after the changes are made. Such changes could include substance changes in terms of type, classification or inventory; the removal or introduction of safety-critical plant; changes to storage facilities or occupied buildings; control-system changes; new suppliers; and so on. In the case of plant modifications, note that reg.8 states that the review must be carried out before the changes are made.

Other factors that could have significant repercussions and therefore need to be incorporated into an updated Safety Report are new facts or knowledge that have come to light since the submission of the last report — for example, key learnings from worldwide events like Buncefield and Texas City, or the reclassification of substances as hazardous, or non-hazardous.

But if no major changes have taken place, does the Safety Report still need to be reviewed? Yes! The original report still needs to be reviewed to ensure that all risks remain as low as reasonably practicable — although it is likely that, following consultation with the Competent Authority, it may not need to be resubmitted, or maybe only in part. Taking a more open and inclusive approach and inviting the Competent Authority to comment on your review process may seem like ‘asking for ‘trouble’ but remember: the fewer changes you make to the Safety Report and the less you resubmit, the quicker and cheaper the review. (It should also be remembered that if risks have been reduced since the original report, this must also be documented.)

Once you have conducted a new risk assessment of your plant and reviewed your existing Safety Report, you must ensure that the report you submit meets the current requirements/expectations of the Competent Authority. To this end, both the Health and Safety Executive and the Environment Agency have produced guidelines for submissions and these can be found on the respective authorities’ websites.


To ensure that your Safety Report remains both current and a ‘living’ document you should, rather than waiting five years, conduct annual or two-year reviews of the report; ensure your company has well-developed change-management procedures, which are robustly adhered to; aim for a culture in your company in which the question is “why isn’t this change subject to formal review” rather than “why is it?”; and finally (and possibly most crucially), don’t see COMAH as a box-ticking exercise — use the knowledge and expertise gained while developing the report to drive your business forward.     


1    The Competent Authority is the HSE and the Environment Agency (in Scotland, the Scottish Environment Protection Agency)

Caroline Stoker is head of regulatory compliance at HFL Risk Services. 

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