Direct observations from the scene of a hazmat incident will enable the full extent of hazards to be recognised and quantified. Such observations for example, eyewitness reports, visual assessment of the size of spill, reports of odours downwind etc are equally important to other information sources to ensure an appropriate risk assessment of the incident. There are also times when marking, placarding and signs are not present, or are incorrect, damaged or obscured, such as during a fire or where hazardous materials are badly controlled or even used illicitly.
In such cases, incident observations will increase in their level of importance. Information and direct observations from site personnel, eyewitnesses (members of the public) and/or information from other responders can be very valuable in determining the objectives, hazards and controls.
To support the tactical options available to incident commanders there are a number of knowledge based considerations that are important to hazmat risk assessment:
- Remember that hazardous materials may not be visible and may not have an odour. If possible and safe to do so without additional personal protection equipment (PPE), approach the incident from higher ground, especially if hazardous liquids are known to be present
- When approaching the vicinity of the incident use senses to assess 'incident indicators' to assist in estimating the extent of the hazard zone
- Gas and vapour clouds or plumes
- Visible smoke and other signs of fire
- Liquid spills, wet areas, patches, puddles, pools and streams or flowing liquids
- Unexplained noise (for example explosions, venting cylinders, site specific audible warnings), which may indicate a more cautious approach and larger hazard zone
- Distinct odours (for example bleach, garlic, rotten cabbage, bad eggs)
- Damaged containers and packages
- Biological indicators such as dead birds, animals, fish, insects, trees and vegetation
- Use 'incident indicators' to make a rough estimate of the quantity of hazardous materials involved.
- Be able to distinguish between the quantity involved (i.e. released or spilled) and the quantity in the container or the maximum contents of the container.
- Assess the scene, consider using equipment such as: Thermal imaging equipment, Binoculars, Monitoring devices
- Locate where the release is coming from
- Understand the potential for contamination from the incident source to move
- Gather information about the emergency or accident from eye witnesses
- Gather information from people responsible for the product causing the release – if possible, for example, site personnel or driver
- Gain specific knowledge about the event, substance, site, process, treatment of casualties and containment system
- Gain information from casualties and other 'involved people' who may physically mark the hazard zone or may be able to describe it based on their experience
- Liaise with other people or agencies to gain specific knowledge about the event, substance, site, process, treatment of casualties or containment system
- Gather information on any relevant history of problems, failures, releases, similar events, etc.
- Identify site containment information, for example, drainage, sewerage, bunding separators and drain closure valves
- Identify the hazards, taking the following into account:
- Casualty numbers (ambulant and non-ambulant)
- Severity and type of signs and symptoms
- The location of the incident – is it likely to be terrorism or a hazardous material incident?
- Environment – building, open space, underground
- Presence of perpetrators
This assessment will enable the incident commander to consider what additional fire and rescue service resources are needed based on the information already gathered and the actions known to be required, consider:
- Numbers of casualties/rescues
- Number of firefighters required
- Number and level of command roles required
- The need for hazardous materials specialists and advice
- Additional PPE requirements
- Type and amount of decontamination equipment and competent staff
- Scene safety and safety officers
- Cordoning and possible evacuation