In the UK, it is a legal requirement for all sites with the capacity to have a major incident to have in place a plan that outlines how the incident will be contained and controlled to minimise the impact. In this article, authored by Dr Andrea Longley, Associate from Finch Consulting, we outline relevant legislation, as well as draw attention to some of the approaches that are considered industry best practice using case studies to highlight potential risks.

Article 12 of the EU’s Seveso III Directive1 requires industrial sites with the potential to have a major accident due to holding over certain threshold quantities of hazardous substances, to draw up emergency plans. These plans should lay out how an operating site intends to contain and control any incidents to minimise the effects, and to limit damage to human health, the environment and property. They should also explain how necessary information will be communicated to the public and to the emergency services or authorities in the area as well as providing for the restoration and clean-up of the environment following a major accident. Annex IV of the Seveso III Directive lists information to be included in such plans.

The Seveso III Directive is implemented in Great Britain through the Control of Major Accident Hazards (COMAH) Regulations 20152 and other planning legislation. Similar legislation is also in place in other jurisdictions around the world.

The best-practice COMAH requirements can be adopted by non-COMAH establishments to provide suitable emergency response planning. The principals are the same, by using a ‘plan-do-check-act’ management system approach, sites can ensure their emergency response capabilities are adequate and effective.

Management systems

Internationally recognised Safety and Environmental Management System Standards3 use the Plan, Do, Check and Act management system cycle to drive continual performance improvement. An effective Emergency Response Management System can be considered to be a similar management system cycle.

Broken down into the management system elements, key components of emergency planning are as follows:

•  Identification of credible incident scenarios – detailing both initiating events and ultimate consequences with feedback and cross-check to the site process safety management system
•  Establishment of response objectives for each scenario (e.g., containment, ignition control, cooling, fire suppression, neutralisation, evacuation, first aid, environmental protection, personnel muster and shelter-in-place, road closures etc)
•  Identification of components required to achieve the response (roles, responsibilities, facilities, resources and procedures)
• Such facilities may include for example flammable and toxic gas detection systems, process alarms, shut-down systems, firefighting equipment; either fixed or mobile, provision of toxic refuges for personnel4, secondary containment bunds, tertiary fire water run off containment, remotely operated shut-off valves or shut-off valves which automatically close when subjected to a fire, emergency quench facilities for quickly stopping chemical reactions, emergency vent scrubbers, emergency pump-out facilities for relocating large hazardous inventories, wind direction indication, emergency decontamination safety showers and eye washes, radio communication facilities and site tannoy alarms
• Such resources may include for example water for firefighting, foam stocks for firefighting, neutralisation agents for chemicals, trained personnel (hazmat response team), leak patch kits, spill kits, respirator or breathing apparatus, diphoterine stocks and stocks of other personal protective equipment
•  Gap analysis of procedure, facility, competency and resource needs against existing availability to develop an improvement programme

•  Preparation of response activity pre-plans
•  Training of identified roles and responsibilities including external partners if necessary
•  Procedures and training for managing changing and unexpected situations
•  Communications and organisational procedures (e.g. internal response structure and off-site or external communications and interfaces for emergency services or mutual aid schemes where relevant)
•  Maintenance of equipment and facilities
•  Incident recognition and response mobilisation

•  Drill scheduling and debrief
•  Equipment monitoring and testing
•  Emergency incident response evaluation reviews
•  Emergency preparedness management evaluation reviews (including compliance and performance trends, debrief and response evaluation results and key performance indicators)

•  Implementation of improvement programme activities to close the gaps on identified needs
•  Corrective and preventive action management from drill debriefs and both incident response reviews and emergency preparedness management reviews (take lessons learned and embed them into revisions of procedures and improvement programmes)

Flammable hazard case study

The importance of good emergency preparedness and response was highlighted by the Buncefield incident5. In this incident, a gasoline storage tank was being filled from a pipeline at a fuel terminal. Despite having high level protection in place, to prevent overfilling of the tank, the systems failed, and gasoline overflowed from the top of the tank. A large low-lying cloud of flammable vapour accumulated and spread out around the tank until eventually it reached an ignition source, causing a powerful explosion. This resulted in a large fire which spread to other tanks in the facility and which took several days to extinguish. The blast effects were so severe that all buildings and equipment covered by the cloud were so badly damaged that they were unsalvageable and damage effects were seen to other properties up to approximately a kilometre from the source of the explosion. The major incident investigation board report6 highlighted several recommendations related to emergency planning. Since the incident that occurred was previously discounted as a major incident risk, it is not surprising that one of these recommendations was to ensure that operators provide for all emergency scenarios arising out of credible major hazard incidents including in this case, vapour cloud explosions and severe multi-tank fires. It is exactly these types of worst-case incidents that should be the focus of emergency planning activities for site operators.

If emergency planning is considered to be within the ‘Plan’ element of an emergency response management system, then it is identification of the potential credible risks that is the first step. If a site is not able to adequately identify its worst-case incident scenarios, then identifying the appropriate arrangements to both prevent them and deal with them if they do occur could be missed.

“worst-case incidents should be the focus of emergency planning activities”

For prevention, a thorough and mature Process Safety Management System7 should provide the means to demonstrate that risks are as low as reasonably practicable.

To mitigate against escalation of any event that has occurred, it is a combination of both emergency preparedness and emergency response activities which are required. In this instance, detection, alarms and shut-down, ignition control, secondary containment and passive fire protection would be examples of emergency preparedness while firefighting, search and rescue, communications and first aid activities would be considered under emergency response.

Due to the severity and longevity of the ensuing fire at Buncefield, the ability of site bunds to contain fuel and firewater was compromised due to the failure of sealant bonds between the concrete panels. The Process Safety Leadership Group report8 written after the Buncefield event, contains recommendations regarding fireproof construction of such bund expansion joints to avoid this bund failure mode and includes specific fire-resistance standards, which sites should implement where relevant to improve their emergency preparedness.

One of the difficulties in the emergency response activity was that there were insufficient stocks of fire-fighting foam and water for the emergency services to use. Sites should therefore familiarise themselves with techniques for calculating the required volumes of foam concentrate for flammable inventories or other materials such as neutralising agents for corrosive or toxic inventories and ensure that sufficient is available based on the specific hazard scenarios of their sites. Equally, since much larger volumes of water were used than was anticipated, tertiary containment was inadequate leading to pollution of local surface and groundwater. If sites are able to more accurately predict maximum volumes of firewater run-off, they will be better able to put adequate containment or treatment strategies in place.

Toxic hazard case study

In 2006, the US Chemical Safety and Hazard Investigation Board (CSB) issued a report9 into a toxic release incident. In this incident, 154 people required decontamination and treatment for chemical exposure. The incident which occurred in 2004 released highly toxic and flammable material after a runaway reaction caused the rupture of an overpressure protection device on the reaction vessel. One of the root causes identified that the company did not prepare or implement an adequate emergency response plan. Neither did they train or equip employees to conduct emergency mitigation actions.

The event continued for eight hours because neither the emergency services nor the employees had the required personal protective equipment to enter the area safely and stop the vapour release. There was no air monitoring capability installed to detect and warn of the presence of the toxic and flammable chemical in the event of a release.

Discussions prior to the incident with the local fire response service (FRS) included both flammable and toxic hazard considerations, but the FRS had indicated they were neither qualified nor equipped to respond to toxic releases and that the site should make arrangements to be self-sufficient in this regard. A familiarisation visit from the local FRS on the first arrival of the chemical of concern on the site did not take place as planned, since the site did not notify the FRS of its delivery as promised.

On initial release, the operators found themselves in the position where they had a fully charged reactor, no ability to increase the cooling rate, no emergency dilution, quench system or dump tank, and no reactor vent scrubber. The call to the emergency services described a ‘chemical spill’ rather than a toxic vapour release. As a result of this, the first responders drove though the dense vapour cloud as they approached the site and suffered immediate irritation to their eyes and nostrils. Subsequent responders were alerted and advised to take alternative approach routes and the police were alerted to begin evacuation of nearby residents, although they were required to do this without access to emergency sirens or a community wide emergency alert system and thus fell into respiratory distress themselves requiring hospital treatment.

Eventually, after the local medical centre declared a ‘code yellow’ event which activated the mass casualty plan, a decontamination station was set up outside the hospital. This consisted of disrobing and then rinsing the entire body in cool water sprays. Five people required further treatment for respiratory distress and were treated with oxygen and a bronchodilator which relaxes muscles in the airways to increase air flow to the lungs.

“good emergency response planning is a necessity, the consequences which materialised were entirely avoidable”

Due to the excessive firewater run-off occurring over such a long period of time and inadequate containment, contaminated water ran into the nearby surface waters which resulted in a significant aquatic kill as far as seven miles downstream.

This case study clearly shows the necessity for good emergency response planning as the ultimate consequences which materialised here were entirely avoidable.

Regulatory control

In March 2019, the UK’s Health and Safety Executive (HSE) published their Operational Delivery Guide on Emergency Planning10. This document, intended for HSE’s inspectors, establishes a framework for the inspection of emergency response arrangements. It focuses on consideration of whether the necessary consultation and planning has taken place between the operator, any Fire and Rescue Service (FRS) and any other identified mutual aid provider. The inspectors will check that response arrangement effectively dovetail between internal and offsite responders, the key here being good communications. To facilitate this, key elements of the response arrangements should be tested at least once every three years to establish how they will work in practice. It is suggested that the particular scenario tested should be changed in each test cycle and performance indicators used to monitor the adequacy of response elements.

Specifically relating to pre-incident plans, inspectors check that liaison information with any FRS covers:
•  Incident scenarios (not forgetting flood preparedness), significant hazards and anticipated consequences
•  Raising the alarm and supplying relevant information
•  Identification of FRS reliance, the adequacy of arrangements and identification of limitations
•  Testing and performance monitoring

The operational delivery guide includes an annex which lists expectations and suggested key questions. Sites can use these as self-assessment tools, asking themselves such questions as ‘Where sites are unmanned (e.g. out of hours), how does the emergency plan deal with this?’ or ‘Does the training programme include specific training for relevant pollution prevention activities?’ and ‘Are all communication links tested routinely to ensure that they will work in an emergency (eg radios etc during a power cut or other emergency situation)?’


Some good practice guidelines for emergency procedures which are designed to support front-line operators are presented in an LPB article11 published by the Institute of Chemical Engineers. It should be remembered that dedicated emergency response personnel undergo regular training in how to respond to incidents, but often it is process operators who are faced with the initial response to an incident. These operators therefore need clear, concise and well laid out procedures to follow. The LPB article recommends that all important steps are included, regardless of how obvious they may be to the author of the procedure. It is important to remember that emergency situations can be high stress situations meaning that important steps can be easily missed. Presenting procedures as checklists with spaces to sign off particular steps can be helpful. Procedures should have tiered response levels to deal with incident escalation. The worst-case scenario is thankfully not always needed and lower severity incident response activities are just as valid in some situations.

Diagnosis and decision-making support (such as flowcharts) can be helpful where direct instructions are not necessarily appropriate. Standard scripts on what to say when calling for external emergency assistance can also lead to improved outcomes.

Key Perfromance Indicators (KPIs)

During normal operation, drills and real incident response activities, performance measures can be recorded to indicate system health. The preference is to provide ‘dual assurance’ by having linked leading and lagging indicators. Leading indicators are metrics which show the health of the management system, such as the number of drills completed to plan or the percentage of training activities completed against the plan. Lagging indicators are metrics which show whether elements of the response plan have failed to function to the desired standard, for example where a plant deluge system failed to activate. Dual assurance metrics are where the leading and lagging metrics are linked to the same control barrier. In the example of a remotely operated shut-off valve, dual assurance metrics may be percent completion of stroke testing performed to plan and percent failure rate of stroke tests as leading and lagging metrics respectively.

Conclusions Proper consideration and implementation of emergency preparedness and response activities can avoid significant undesirable outcomes for people, plants and the environment in the event of an incident. Sites should ensure that adequate resource is provided to thoroughly address each element of the Plan-Do-Check-Act Management System Cycle for Emergency Preparedness and Response.

1   EU. DIRECTIVE 2012/18/EU OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL on the control of major-accident hazards involving dangerous substances. Seveso III Directive. [Online] July 4, 2012.
2   HSE. Guidance Document on the Control of Major Accident Hazards (COMAH) Regulations 2015. [Online] 2015. ISBN 978 0 7176 6605 8.
3   BSi. BS ISO 45001:2018 Occupational health and safety management systems, Requirements with guidance for use. 2018. Vol. ISBN 978 0 580 86393 6. ISO 45001.
4   Chemical Industries Association. Guidance for the location and design of occupied buildings on chemical manufacturing and similar major hazard sites. CIA. [Online] February 2020.
5   Buncefield: Lessons learned on emergency preparedness. Graham Atkinson, HSE, UK. 254, s.l. : Institution of Chemical Engineers, April 2017, Vol. Loss Prevention Bulletin.
6   Buncefield Major Incident Investigation Board. The Buncefield Incident – 11th December 2005 – The final Report of the Major Incident Investigation Board, vol.1. 2007. ISBN 978 07176 6270 8.
7   Energy Institute. High level framework for process safety management. [Online] First edition, 2010. ISBN 978 0 85293 584 2.
8   PSLG. Process Safety Leadership Group Final Report: Safety and environmental standards for fuel storage sites. s.l. : HSE, 2009. ISBN 978 0 7176 6386 6.
9   Chemical Safety and Hazard Investigation Board. MFG Chemical Inc Toxic Gas Release. CSB. [Online] November 2006.
10 HSE. COMAH CA Operational Delivery Guide: Inspection of COMAH Internal Emergency Planning at Upper and Lower Tier Establishments. [Online] March 2019.
11 Brazier, Andy. Emergency Procedures. Loss Prevention Bulletin. 2017, LPB254.