Preparing for An IncidentMODULE 6

Emergency Scene Assessment•Four criteria used to Assess the Scene •Hazard – What hazards are present and to what degree?

•Damage – What damage or harm has already occurred to the exposures?

•Vulnerability – What exposures are most likely to be affected by impingement and how will they be harmed?

• Risk – What is the probability of harm to a specific exposure and to what degree?

Recognition of Hazards•Identifying the hazards based upon

•Observation

•Reported Information

•Can help you make appropriate decisions based upon• Capabilities

• Observations

Overall goal is safety of the Responders !

The D.E.C.I.D.E. Process•The DECIDE framework structures questions to be answered during an emergency:• The questions guide the search for data to support actions and estimate

outcomes.

• Helps you have a uniform process for

• Gathering information

• Making operational decisions

Container, Placards Shipping Papers

Identify the hazardous materials so that its properties and hazards can be determined

Estimate the exposures that can be saved and work to save these exposures

What actions/options that can change the sequence of events

Select the option within capabilities

Evaluation allows other options to be considered

Utilizes measurement of risk

Using DECIDE at Crude Oil Incidents•Using the concepts in the DECIDE process under "estimating likely harm without intervention", there are two types of violent tank car tank failures facing emergency response personnel•Runaway inear cracking with tearing

•Runaway linear cracking without tearing

Runaway Linear Cracking•With Tearing•Results in cracking that tears the tank into multiple pieces

•Results in the instantaneous release and dispersion of the contents •this breach/release is commonly known as a BLEVE and typically associated with pressure tank cars

Runaway Linear Cracking•Without Tearing•Cracking that stops before tearing the tank into multiple pieces

•Results in the rapid relief and dispersion of the built-up vapors in the tank and some of the product, leaving some product in the tank •This breach/release mechanism is known as an arrested

crack and is associated with nonpressure tank cars

Recent Experience•Recent incidents have occurred involving non-pressure tank cars that have resulted in runaway linear cracking with multiple tank pieces and the instantaneous release and dispersion of the contents

Types of Container Stresses•Thermal •Container is being heated internally or externally

•Mechanical•Container is being strained by internal or external forces

•Chemical •Container is undergoing corrosion because it is in contact with

a chemical

Types of Breaches•Disintegration •Total loss of container integrity.

•Runaway linear cracking •Results when tank is stressed and weakens due to metal

fatigue

•Punctures •Object pushes through the wall of the container

Types of Breaches•Closures open up •Engineered openings such as pressure relief devices can open

and/or valves and access points can be damaged, opened, or sheared off by external forces

•Splits and tears •Splits and tears occur when external forces rip or abrade the

container, resulting in loss of container material ultimately, container failure

Types of Releases•Detonation •type of combustion reaction that release tremendous amounts of heat and pressure from the near-instantaneous decomposition of unstable materials..

•Violent ruptures •a subsonic chemical reaction occurs which abruptly breaks the container.

Types of Releases•Rapid relief • internal pressure build-up with venting, either by a pressure

relief device or the unexpected opening of the container without total container failure.

•Spill or leaks • low pressure or atmospheric pressure release.

Types of Dispersion•Hemispherical •dome-shaped as in an explosion

•Spherical•with fireball rising after LPG tank rupture

•Plume

•with vapor cloud from point source

Types of Impingement•Usually described in terms of contact time or duration

•Short-term impingement • seconds to hours

•Medium-term impingement •days to months

•Long-term impingement •months to years

Risk Evaluation•Four criteria used to evaluate risk. •Hazard • What hazards are present and to what degree?

•Damage• What damage or harm has already occurred to the exposures?

•Vulnerability • What exposures are most likely to be affected by impingement and how will they be

harmed?

•Risk• What is the probability of harm to a specific exposure and to what degree?

Using the Information•The information developed will be used to develop the overall plan for the operational element of the response.

•The completion of the incident analysis and risk assessment is an on-going process

Always remember Responder Safety is First Priority !

Types of Dispersion•Circular• with gas cloud on a still day on level terrain

•Stream• with runoff downhill

•Irregular• with personal transport or runoff in sewers, etc.