Hazmat Size-Up: A New Model for Rapid Decision-Making

Cranston Fire Department Rescue 2
Photo by Richard Beaulieu

By Richard C. Beaulieu

As first responders in a modern technological, era made possible by the endless creation of chemical compounds, we can often be placed in extraordinary conditions in a surprisingly short amount of time. In contrast to structure fires, we are taught in hazmat response that everything slows down; we do not rush into hazardous materials incidents hastily but rather methodically with a well-thought-out incident action plan (IAP). Most of the time this is true and the response models we teach to new technicians reflects this methodology. Whether we are following Ludwig Benner’s D.E.C.I.D.E method or following the APIE method, we take all of the available data and plug it into a response formula that will naturally flow from the moment we are dispatched to the stabilization of the incident. Hazmat incidents may have predictable outcomes, especially for those who are well trained and experienced in hazmat response. Most departments however, especially smaller ones, are only familiar with dealing with everyday Level I incidents such as fuel spills, natural gas leaks, and carbon monoxide alarms. What happens when these same responders are now faced with an anhydrous ammonia leak at a facility, a train derailment involving chlorine, or a transportation accident where an intermodal of hydrogen chloride is threatening motorists? What happens when a box alarm at a chemical facility is determined to be a vat on fire and the activation of the sprinkler system has now caused a chemical reaction? This results in several companies of firefighters exposed to corrosive gas and in need of rapid decontamination and medical treatment. This happened in Cranston, Rhode Island, in January of 2018, with the added obstacles of below-freezing temperatures and snow flurries.


Hazmat: Initial Actions and Chemical Assessment

Hazmat Survival Tips: Hazardous Materials Incident Size-Up

Three-Point Hazmat Size-Up

Training Minutes: UAVs for Hazmat

The time between the determination that an incident requires a formally trained hazmat team response and their actual arrival on scene could result in devastating consequences for the first-due responders and the public. If companies are not prepared to size up the scene and take the appropriate actions, a bad outcome is likely. Some departments are well equipped and have their own hazmat teams whereas others must call and wait for a regional team to respond. That could take hours. In Cranston, we are fortunate that once first-arriving companies determine that a hazmat team is needed, our on-duty hazmat personnel and our hazmat truck are mobilized. We have well-trained and competent responders immediately available to help our incident commander with decision making. This is not the reality for many departments and despite the old attitude of hazmat being a slow process, sometimes it requires the same rapid response and the same rapid deployment of assets as a structure fire does. The problem is mindset. Major hazmat incidents for most of the country are scarcer than structure fires. Despite the decline in fires, the response to a fire and what will be done upon arrival is still second nature to firefighters. On the other hand, hazmat response often presents a mental roadblock for the first-arriving companies and first-arriving commanders. That roadblock is a rapid size-up model similar to ones taught in the fire academy such as REVAS. Hazmat lacks a formal rapid size-up model that allows for quick decision making, especially when life needs to be saved without hesitation. Incident commanders and company officers need to start organizing information immediately upon being dispatched to a hazmat incident.


DRECC is a model that anybody dispatched to a hazmat incident can use to begin to formulate what needs to be done first and what questions need to be asked next upon arrival and as more information is gained. This size-up model is the first step before any formal hazmat team response and will allow first-arriving companies to quickly assess the current situation and drive their initial actions.

DRECC stands for:


            Rescue, public protective actions (PPA), emergency decon




DRECC size-up is effective at assisting with rapid decision making when we need to do something immediately. Take the following example: “Engine 1 and Rescue 1 respond to ABC Plating Co. for a report of a car into the building, time out is 1415.” From the dispatch alone you know where the incident is, whether the building is occupied, the potential exposures, the population of the area, and the geography of the area just by knowing your jurisdiction and that people are potentially injured. Fire alarm notifies Engine 1 that a backup call from the facility manager determined that the car struck the facility’s outdoor anhydrous ammonia tank; there is a liquid leak and the driver is not responsive; and the manager is activating his company’s evacuation and accountability plan. With this additional information, we now know a person needs to be rapidly rescued, the company workers are safe, and that we are dealing with an outdoor incident involving ammonia with a breached tank or its piping with a liquid leak. With all of this information, Engine 1 arrives on the scene, dons full firefighting protective gear with self-contained breathing apparatus (SCBA), deploys a hoseline with a fog pattern to disperse the ammonia and push it away from the vehicle, and rapidly removes the person from the area. The victim is quickly decontaminated with water and the personnel on Rescue 1 are treating him medically. Engine 1 is now protecting the nearest residences in place with their hoseline from a safe uphill and upwind position. Engine 1 was able to use DRECC effectively to rapidly deploy their strategy and tactics because they were familiar with the properties of ammonia from walk-through training at ABC Plating.

Being familiar with the chemicals in your response district will allow for DRECC size-up to be even more useful. Chemical reactions, unknowns, and limited information will make that initial response more challenging, but becoming an expert of your response district will help reduce these challenges. The APIE method is one of the most popular response models for hazmat and using the DRECC size-up model will directly flow into the Analysis stage once the start of an operation that requires immediate actions to be taken slows down. The ammonia scenario will now transition into a Level II hazmat response with the APIE response model to protect the public, contain the leak, and assess any environmental impact. If the dispatch was already hazmat in nature and the company is calling for an ammonia leak, DRECC is still applied as companies are responding. The difference is that this time, with no immediate rescue to perform, PPA are performed while a formal hazmat team sets up, APIE is used, an IAP is drafted, and the incident is stabilized. Once dispatched to a hazmat incident, DRECC size-up allows for information to be rapidly organized, life safety considered first, and then how the chemical, its container, and the environment it is in will act during the release. With limited information from the dispatch itself, the rest of the questions can be answered quickly upon arrival and visualizing the scene and initial actions can begin to happen while command is waiting for a hazmat team to arrive and perform a more formal analysis and plan.


Regardless of the amount of information contained in the dispatch to a hazmat incident, key information is immediately gained. The address or area itself answers several questions and the better our preincident surveys are, the better prepared we can be to respond to an emergency. It is imperative to perform walk-throughs of any companies in your response district that use or store chemicals and to have easy access to their chemical inventory list and contact information for their management, foreman, chemists, or other experts in their process. It is a great start to know what a facility has, but often an incident occurs as a result of their process and this is where contact with their experts is crucial. An address or area immediately tells us the geography or topography of an area. Is the area urban or rural, what are the exposures present and the potentially affected population? Are there residential homes, schools, daycares, occupied businesses, high rises, prisons, places of assembly or recreation, nursing homes, and shopping centers? Or is there open land with peaks and valleys and the occasional residence or business?

The number of structures in urban areas will affect wind conditions and how a chemical moves through the area. People inside these buildings may become exposed and require decon or treatment before there was time to deploy protective actions. Once the leak is contained, the outside may be free of the chemical but now the buildings in its path have concentrations that need to be ventilated before the public can return. The time of the dispatch tells us the amount of expected traffic; business hours put more people on the road and in the city in general, and companies are occupied as well, sometimes around the clock, depending on their function. The dispatch can tell us if there are people injured or exposed, potential signs and symptoms reported, if they need to be rescued and decontaminated or require protective actions. The question of whether a hazardous material should even be in this location must be considered, especially with good preplanning of your response district. Clandestine laboratories or terrorist activities may cause people to have signs and symptoms in places where such indicators would not make sense for such a location. With all the knowledge gained by the dispatch, the initial actions upon arrival will become clearer to the first-arriving companies.

Rescue, PPA, and Emergency Decon

After considering all the information acquired from the dispatch and making a rapid identification of the chemical upon arrival, life safety may require firefighters to take immediate action. Whether the dispatch identifies it or the on-scene size-up identifies it, people may need to be rapidly rescued with structural firefighting gear, SCBA, and vapor dispersion. This is the high-risk/high-reward aspect of our ongoing risk assessment. If a highly toxic or corrosive substance is confined indoors, we must consider that victims are not viable and we are not properly protected to make a rescue. When this same scenario exists outdoors and the person is deemed viable, a rapid rescue must take place. If a large amount of a release is threatening the public, a decision for PPA must happen quickly. A flammable substance threatening the public is cause for evacuations of the immediate area before the leak can be contained. Larger-scale evacuations may be coordinated afterwards if necessary. Evacuations are necessary when dealing with flammables because it would be impossible to have the public control the ignition sources in their homes effectively.

The public may need to be sheltered in place from toxic materials. People can be instructed to close their windows, shut down their HVAC, and go to higher or lower floors of their home or business, depending on the vapor density of the chemical (if it is a known substance). A combination of the two may take place where the immediate area shelters in place while a larger area evacuates, or vice versa. A school threatened by the release of a gas may be defended in place by hoselines dispersing the material. Any victims exposed who require immediate medical attention must go through emergency decontamination before being treated medically. Hospitals will need notification of the amount of people needing treatment, their decontamination status, and the severity of their condition. These decisions could have to be made immediately by the first-arriving companies well before any hazmat team responds to a scene; a DRECC size-up helps officers and commanders to get into this mindset. Outside of the immediate area of a release, PPA are extremely difficult to accomplish. Multiple simultaneous means of achieving this goal must be used, including radio, local TV, PA systems from vehicles especially from the police, emergency broadcast systems that deliver the message across all forms of technology, social media, and reverse 911. Communities should organize drills between local government, the fire and police departments, and the public to educate and prepare everybody for the possibility of public protective actions during a release. Many facilities using chemicals are placed in the middle of neighborhoods or close to public places because no regulations existed to zone them away from these spaces when they were originally established.


The weather directly affects a chemical after it has been released from its container. Whether an incident occurs outdoors or is confined inside changes things as well. The current weather conditions will affect a material’s chemical and physical properties. The state of matter of a substance out of its container is subject to temperature. Many products that responders deal with often such as propane, ammonia, chlorine, or hydrogen sulfide will be found as a gas when out of its container almost anywhere in the country any time of the year. However, a gas such as hydrogen cyanide can be a gas during the summer and a liquid during the winter when out of its container exposed to current temperatures. If the product is released from its container and is found to be water reactive and the breach occurred outdoors on a rainy day, we are now dealing with a chemical reaction and the creation of new compounds. The same incident on a clear, sunny day could be of little to no risk with a very easy clean-up. It is important to note the level of humidity. High humidity could react with substances that are water reactive or keep a water-reactive gas that usually would go up and away closer to the ground. Outside temperature changes how flash point and fire point of a substance are considered for potential ignition of the material. If there is a gasoline spill almost anywhere in the country any day of the year, then controlling ignition sources and vapor suppression will be priorities because the flash point of gasoline is -45°F, but the same incident involving diesel fuel has different considerations. On a hot summer day here in New England with a flash point of 125°F, diesel fuel becomes of greater concern than the same spill on a 10°F day.

Vapor pressure is affected as well by outside temperature. If a 55-gallon drum of acetone with a vapor pressure of 180 mmHg at 68°F spills outside on a summer day, the substance would evaporate so quickly the facility would likely not even call to report an emergency. If the same incident occurs indoors confined to a small room and the air temperature inside the facility is cool, evaporation slows down and the substance is now more persistent than on the hot day, prompting the facility to call for help. The most significant danger of an incident occurring indoors is the product concentrating faster than it is dispersing or being ventilated. This allows the concentration to get to immediately dangerous to life and health (IDLH) status and possibly allows it to get into its flammable/explosive range. An outdoor leak of anhydrous ammonia with it being lighter than air and having a LEL of 15 percent (150,000 ppm) would make it unlikely to explode; the same leak indoors could be allowed to concentrate, making it severely toxic and corrosive as well as potentially explosive. These are the reasons why the environment a chemical is released into must be considered in our rapid size-up.

The safety of responders and the public is also dependent on weather conditions. Firefighters and civilians may have to undergo decontamination in freezing temperatures, rain or snow conditions, or extreme heat. Responders may need to use the buildings in the area of the incident to stage people or buses may have to be called in from the school department or a local bus company to provide heated or cooled spaces for people. Other challenges include privacy and something to cover people with after decontamination. When formal hazmat and decontamination teams arrive, they often have plenty of equipment for warmed water, temperature-controlled spaces, privacy and paper clothes to wear, but in the beginning of an incident when these assets are not available, responders will have to think creatively.


If we know what the chemical is, we are 90-percent of the way home in hazmat response. Knowing what we’re dealing with allows us to know how it will behave based on current and future weather conditions, what will happen if it is confined, whether it is prone to chemical reactions, and, most importantly, how is the substance going to hurt people or the environment. Identification also allows us to know we need to detect it and protect ourselves from it to stabilize the incident. Sometimes there is no way of knowing exactly what the substance is; there may be no access to chemical inventory lists or shipping papers, poor labeling/placarding, illegal activity, too much damage to the container, or chemical reactions. All that is left to us are the clues presented on scene. Some to consider:

  • Where is the incident?
  • What types of chemicals should be here if it is a facility?
  • Should a chemical even be in this location?
  • If the substance is visible, how much product is there?
  • What state of matter is observed?
  • Is there any color to the substance?
  • Is there boiling or spattering of the material?
  • Is it hugging the ground, going up and away, or doing both?
  • Is it persistent or is it quickly moving beyond the origin of the incident?
  • Is it flowing towards storm drains or bodies of water?

If the material is solid or liquid, note its color and if anything is reacting with it. Use a laser temperature gun from a safe distance to see if it could be reacting with the moisture in the air—if possible and you are properly protected, this will be easier outdoors than indoors. Does a liquid appear thick and viscous like molasses or is it loose like water? Are there visible vapors observed over the liquid indicating high volatility or fuming? If a gas is observed, is it moving toward an exposure? Does something need to be done right away? Many gases are colorless as well as being toxic, flammable, corrosive, or asphyxiating, and the only evidence of their presence is the reported symptoms of those exposed, where the incident is occurring, and what should be present there for hazardous materials, if anything.

Any evidence of a chemical reaction must be taken seriously because now new compounds are being formed. If the material or container is hot, actively boiling/spattering, paint is peeling off its container or it’s bubbling up, vegetation is discoloring or dying in the area, or there is violent fire, chemical reactions are taking place. This information needs to be recorded from a safe distance for the hazmat team. The hazmat team will use metering and detection equipment to at least try to classify the material, but observation during size-up is a valuable tool to help start the process. If a hazmat team in your jurisdiction is more than an hour away, the incident will be much different than what was initially observed by the time they arrive and begin their analysis.


The container of a substance tells the amount of material, from a simple drum up to a massive railcar and any markings present help identify the chemical. Some responders may be familiar with what should and should not be stored in a given container. A 55-gallon drum should not have a pressurized material in it, but bulging is evidence of a chemical reaction that is creating pressure and will lead to container failure. Observing the shape of the container will reveal state of matter or states of matter within and whether the container is pressurized. The Emergency Response Guidebook (ERG) is helpful in conjunction with DRECC size-up, especially for identifying markings, placards, and containers. Simple company-level drills can be done at the kitchen table on days of poor weather to improve efficiency with the ERG.

Large amounts of material change the amount of risk responders initially face and any container that is pressurized or undergoing a reaction also increases risk. The size, extent, and state of matter should be noted when assessing a leaking container. Many common gases encountered by responders that are liquefied exist as a liquid and gas in the container under pressure; these substances are extremely cold upon release to atmospheric pressure. Always observe and assess from a safe distance during size-up, using binoculars if available. Note the damage a container has sustained and if it is the container itself that has breached or if it is a valve or piping that is leaking. Assess for any chemical reactions taking place, especially if the product has not yet breached. Be on high alert for boiling-liquid, expanding-vapor explosion (BLEVE) when there are activated relief devices, direct flame impingement, pinging, banging or hissing sounds, or bulging, or if a thermal imaging camera indicates a very hot substance inside of the tank compared to the outside air. BLEVE can occur for reasons other than direct flame impingement, such as chemical reactions (these reactions create heat and pressure that can overwhelm the design of the tank), explosion in the vapor space, and overheating or overfilling of the container.


Hazardous materials incidents require a thorough yet rapid size-up from the beginning of the response at dispatch to the initial observations made once the first-due companies arrive on the scene. The safety of responders and the public is enhanced greatly when the DRECC size-up model is used in conjunction with preincident planning, walk-throughs, ongoing hazmat response training, practical drills, and training personnel to the technician level, if possible. This is especially important for jurisdictions that must wait for a regional hazmat team to respond. Time is of the essence at the beginning of some of these incidents, and rapid size-up and quick yet safely deployed actions will save lives, protect the public, and lead to an efficient stabilization of a hazardous materials release.

Richard C. Beaulieu is a lieutenant on Rescue 2 for the Cranston (RI) Fire Department. He is a 14-year veteran of the fire service and has been serving Cranston since 2008. He has a bachelor’s degree in Fire Science from Providence College, is a cardiac-level EMT and has been a hazmat technician since 2006. He is a NFPA 1041-certified instructor and coordinates the hazmat technician training for the Cranston Fire Department’s recruit training academy.

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