How do you deal with major risks at a facility with dangerous substances?

31.03.2020 / Gunilla Christiansen and Finn Pedersen

Major accidents involving dangerous substances pose a substantial threat to human life and the environment. While use of these materials is unavoidable in some industries, it is crucial to have stringent measures in place to mitigate potential risks, or in the worst case, to minimise the consequences of major accidents. Here are a few tips from our dedicated specialists on the most rational ways to deal with it:

If your facility has developed to be covered by EU’s Seveso III Directive on Control of major accident hazards (in UK the COMAH regulations, in Denmark "risikobekendtgørelserne"), then your dedicated Safety Report must be accepted by the competent authorities. Regulations vary a little between the EU member states.

The Safety Report is a controlling document for the facility from cradle to grave, that must be updated on a regular basis. Company dedication, i.e. ownership of policies and procedures for operation, maintenance and emergencies, is a must to ensure commitment to the accepted safety level at all times. We recommend the following steps:

  1. Prepare and describe as much as you can yourself of the Safety Report, such as the Safety Management System you have in place, the action plan for risk-reducing measures, the Emergency Management Plan, the Security Plan if required, and the Major Accident Prevention Policy for your company. The Safety Management System may often be established as an extension to your existing Quality and Environmental Management System.
  2. Participate as much as possible in the preparation process of the Safety Report with your own specialists and operational staff.
  3. Learn the process from the guidance documents provided by your Authority, e.g. HSE in the UK and DEPA in Denmark.
  4. Take ownership of all required follow-up activities.

By doing so, you will experience a smooth and quick handling by the competent authorities, resulting in an acceptance of the Safety Report. And specialists with relevant experience like COWI can guide you and assist wherever necessary in the process.

The process to prepare a Safety Report for a company that handles dangerous substances, comprises several activities that require specialist knowledge and experience.

  • Notification and Safety report
  • Hazard identification, e.g. HAZID or HAZOP studies
  • Analyses of the potential consequences, with calculations of release rates, gas dispersion, fire, explosion or toxic effects
  • Risk analysis, likelihood or frequencies of scenarios, failure probabilities, human and organizational factors
  • Risk evaluation, individual risk and society risk compared to risk acceptance criteria for location based iso-risk and FN-curves
  • Risk reduction by component, design or process changes, substitution, redundancy or emergency planning
  • Safety barrier diagrams based on event sequences leading to major accidents and evaluation of barriers
  • Vulnerability assessment to mitigate terror-type activities, and Security Plan, if required
  • Major Accident Prevention Policy
  • Safety Management System.


If dangerous materials are involved when planning a new facility, not only are environmental impact assessments and full operational risk assessments normally required, but depending on the amount of dangerous substances involved, a preliminary Safety Report must also be prepared and accepted by the authorities. It is well known, that the cheapest solution (most safety for the same costs) is achieved, if risk-reducing measures are built into the concept from the start.

While it's impossible to finalise a safety management system before you have a design and an organisation in place, the concept design phase is the ideal time to start identifying hazards, to complete preliminary consequence calculations, and anticipate what risk reducing measures can be taken right from the very start to prevent major accidents from happening. Then of course, this must be continually updated when the design is matured and taken into operation.

If the risks are not dealt with, the consequences for people and the environment can be serious.

Making accidents extremely unlikely to happen

In simple terms, the safety report must show that adequate safety and reliability measures are in place at all installations, storage facilities, equipment or infrastructure which are linked to major accident hazards within the facility.

The safety report must identify how dangerous materials could be released in the event of an accident. For example, could release of toxic or flammable materials cause toxic fumes/smoke, heat radiation or fragments from an explosion to reach a local hospital, school, residential area, or other neighbours if there was an accident at the facility? And if so, what is the likelihood of this happening? What is the risk to the employees at the plant?

Risk is a combination of likelihood and consequence, so if there may be a serious consequence – for example a high death toll, then the likelihood of the accident occurring must be very low.

Three steps of dealing with major risks

  1. Start by considering whether there is a way to avoid having the dangerous material on site at all or to substitute the material with another and less dangerous one. Or maybe the volume of that dangerous material can be reduced.
  2. If this is unavoidable, then the highest risks should be eliminated. For example, can you segregate the dangerous materials so an incident involving one part of the plant do not escalate to another part, even in the case of a fire? What if an office or workshop is situated close to a potential accident area - can it be moved so that employees are not at immediate risk?
  3. Where the risk can't be eliminated, then measures must be taken against it having very serious consequences or high likelihood. This might be as simple as putting up a fire wall to protect vulnerable objects from flames/heat radiation or setting up elevations in the terrain to contain spillages to force any fire away from vulnerable objects in the surroundings should an accident occur, but most often distance is required, or measures to drain away spillage of flammable material to prevent a tank explosion because of flames in the tank bund.


Safety reports are not just for the design of new facilities. The European Commission's Seveso Directive applies to more than 12,000 industrial establishments in the EU where dangerous substances are handled or stored in large quantities – for example in the oil and gas, the chemical and the petrochemical industry, chemicals or fuel wholesale and storage sites including LPG and LNG facilities, facilities with ammonia-based cooling/refrigeration systems, and ammunition or firework storages.


Safety reports never stands still, and we all continue to learn from accidents, and develop our risk assessment and safety management expertise to lessen the threat of major accidents involving dangerous substances for generations to come.


Get in contact

Gunilla Kay Christiansen
Leading Project Manager
Risk Analysis, Denmark

Tel: +45 30297433


I believe that proper knowledge sharing between different disciplines can identify and subsequently prevent most accidents. My role is to see things from another angle than the design team and ask questions that will facilitate a thinking process among the people who know the plant, the operations or the new design in detail. Major accidents are fortunately rare, and some people may say that they will not happen. But if they do, the consequences may be extensive. As a technical safety engineer, I will lead the process to identify potential major hazards and their causes and help to find ways to prevent them from happening or reduce their consequences or likelihood. My background is chemical engineering and I have worked many years in oil and gas companies with the design, operation and optimisation of process plants. I have investigated near misses, which easily could have resulted in major accidents.

Get in contact

Finn Pedersen
Leading Project Manager
Risk Analysis, Denmark

Tel: +45 2179 8740


I graduated from the DTU as a chemical engineer with special competences and skills in process engineering. A major part of my professional career was in large chemical process industries such as oil refineries and fertiliser plants, working with process design, operation, maintenance, logistics and QHSE both as a specialist and as a manager. Since that I have been with COWI and worked professionally with health, safety and environmental risks for Danish and international industries; often on risk tasks related to the EU Seveso directive on the prevention of major accidents involving dangerous substances. This work includes disciplines such as hazard identification (HAZOP/HAZID), process safety design, risk assessment, safety reports and support to obtain risk acceptance from the many authorities involved.