BY CHRISTOPHER BRENNAN
A contentious aspect of hazardous materials response is determining hot zone boundaries. In setting up a hot zone, the incident commander (IC) chooses the size of the area from which to exclude people until the hazard is mitigated. This may require that roads be shut down, resulting in traffic delays, or may cause a company to stop operations. An IC can have a great impact on the community based on the size of the hot zone he establishes and what he does to control that zone.
The Illinois Fire Service Institute teaches the steps Isolate, Identify, Notify, Mitigate, and Terminate as broad categories of what must be accomplished at a haz-mat incident. Setting hot zone boundaries is a part of “Isolation.” An incident commander must consider many factors when determining the boundaries of the hot zone. This method of establishing a hot zone is geared toward responders at the operations level. A Technician-level team may change the hot zone, and the area may continue to evolve during the incident.
THE SCIENCE OF SETTING UP HOT ZONES
The science of setting up a hot zone boundary is based on research materials and knowledge of the physical and chemical properties of the material: What is the product going to do? Where does it want to go? How is it going to hurt me? An IC’s first step in answering these questions is to determine what the product is. This process may be as simple as asking a truck driver or facility manager or obtaining the appropriate material safety data sheet (MSDS). If the product name and quantity can be determined, published isolation distances can be used. If there is no immediate definition of the product or products, you need to analyze the properties of the unknown product to determine the course of action needed to mitigate the hazard.
The reality of haz-mat response is that many incidents involve “unknowns.” This happens for a variety of reasons: fly dumping at illegal sites, a spilled product on the street with no offending vehicle on the scene, or compromised storage containers left in abandoned buildings, for example. No matter what the reason, the IC is responsible for determining how to handle the product safely and mitigate the hazard.
 The recon team investigates to determine the hot zone boundaries. (Photos by Beth Hoefferle.) |
null
In developing a plan to deal with unknowns, the IC should first determine the physical state of the product. A solid may pose several hazards, but it is not going to get up and walk away. Therefore, this product may be isolated with little effort. Simply covering the material with plastic sheeting may mitigate the hazard.
 The pike pole is left at the initial point of the alarm’s “hit” as a visible indicator of the hot zone boundary. To keep the pole upright, you can insert it into a traffic cone. |
null
Liquids are more difficult to control: They want to flow and follow the contours of the earth. Isolating a liquid product is likely to require damming, diking, diverting, and retention. Setting up these systems requires lots of personnel, materials, and time.
Products in a gaseous state are the most difficult to control. Gases expand to fill any available space. Depending on the gas, it may be lighter or heaver than air. Gases also pose a substantial risk to the respiratory system, which should be of great concern to the IC.
Determining the physical state of the product gives an idea of where to place the initial hot zone. When assessing unknowns, research materials such as the Emergency Response Guidebook (ERG) published by the U.S. Department of Transportation, can point us in the right direction. The ERG recommends isolation distances of a minimum of 330 feet for a small release and 660 feet for a large release of an unknown spill or leak.1 This distance is used to provide a minimum safe operating area. The IC may feel a greater distance is needed because of environmental conditions, a reasonable suspicion that radioactive materials are involved, or other factors that dictate a more cautious, defensive strategy be used.
After determining the product’s physical state, you can begin to assess its other properties. This is done by a reconnaissance of the incident site: upwind, downwind, and crosswind of the release. Operations-level responders in bunker gear with SCBA can perform hot zone reconnaissance, provided they have the appropriate monitoring equipment. Reconnaissance is typically implemented from a defensive posture.
null
Air monitoring plays a critical role in determining the size and location of hazard control zones. If the scenario involves an unknown, recon teams should be equipped to monitor for radioactive materials, corrosives, flammability, oxygen concentration, and toxicity, in that order. First responders, typically limited to having a multigas meter (e.g., combined combustible gas indicator, oxygen meter, and typically carbon monoxide or hydrogen sulfide) should monitor around the site.
Hazardous materials response teams (HMRTs) will have additional air-monitoring capabilities, such as colorimetric tubes and papers. Using a two-person team, you can perform all of these functions at the same time. One team member should be equipped with a radiological meter and the other with a pH stick (a pike pole with wet and dry pH paper taped to the blunt end); a key for reading the paper is attached where the operator can see it. This configuration allows you to monitor for most potential hazards.
The recon team should monitor around the site. If there is a “hit” on one of the monitors, indicating the presence of product, the team will stick the end of the pole into the ground or a traffic cone if on pavement, to mark the boundary of the hot zone at the point where product is first detected. This initial area is likely to be smaller than the ERG’s specified 330 to 660 feet. However, teams should be prepared to retreat if the area is found to be larger.
Multiple teams can be used. They would converge from different directions to establish a reasonable “footprint” of the hot zone. Teams that begin from downwind positions should start their approach using SCBA from at least the minimum protective action distances recommended in the ERG or MSDS.
Responder safety is paramount during the hot zone recon operation; basic precautions should be taken. At a minimum, emergency decon should be established, and members conducting the recon should undergo medical surveillance before entry. This evaluation can be as simple as noting pulse, blood pressure, and respiration levels. A backup team should be in place; teams should have at least two members. The recon teams need a method of communicating with Command by radio or hand signals. All monitors should have extension tubes. The pH stick should be kept out in front of the team, to prevent the team from becoming contaminated. All recon team members should know how to use the particular monitoring instruments and what the alarm points are for each monitor.
Remember that hazard control zones are dynamic. For example, HMRT personnel with air-monitoring capabilities above that normally found at the engine company level will typically verify the initial monitoring results and may change the size and location of the initial hazard-control zones.
THE ART OF SETTING HOT ZONES
The IC and the haz-mat sector officer must know what a product will do and how to make that product behave as they want. For example, the county fire department and haz-mat team are dispatched to a leaking, one-ton chlorine cylinder at a local water treatment facility. On arrival, they find a chlorine alarm and a visible cloud emanating from the building. Wind conditions are causing the cloud to begin drifting near a local subdivision. It would be impractical to evacuate the subdivision in this situation. Evacuations take considerable time, and the risk of injury to unprotected emergency responders and civilians is increased when residents are brought out of their homes into a potentially contaminated environment. To keep the chlorine cloud from reaching the subdivision, you can set up remote fog streams using aerial devices or unmanned monitors to knock the chlorine cloud onto the ground using vapor dispersion. The chlorine will turn into liquid hydrochloric acid and damage the ground on which it lands. However, subdivision residents’ lives and property will be spared. You will have controlled the size of the hot zone and will have made the product do what you wanted it to. After the incident is mitigated, cleanup contractors can dig up any contaminated earth if the local environmental officials so direct.
Another example would be the release of a toxic chemical inside a building. The entire building does not automatically need to be isolated for 330 or more feet. It may be possible to contain that product to the room or floor of origin. If you are responding to a facility with complicated processes or expensive production methods, you may not be able to reasonably shut down an entire plant. You may, however, be able to use building systems such as HVAC, retention systems, or even fire sprinklers to contain the material to a small geographic location within the building, thereby allowing the company to stay in operation and not lose even more money. Building management/maintenance personnel and process engineers will be able to help you determine how to best accomplish this. Although we would do anything reasonably necessary to ensure the safety of our responders and the public (including shutting down entire companies, airports, highways, or any other areas), we must be aware of the economic and political ramifications of such decisions, to best serve our customers’ interests.
By using creative problem solving and carefully studying research materials, an IC can greatly affect the overall impact of a hazardous-materials incident. There is, of course, no single “right way” to manage every incident; but by considering the safety of responders, the public, and the environment, you likely will come up with a safe and workable plan. Remember that regardless of the scientific and common-sense steps an IC takes to set hot zones, the mitigation of a hazard needs to be conducted by appropriately trained and equipped responders acting within the scope of applicable laws and standards. Just because we can reduce the area of hazard does not mean that an Operations-level responder can perform a plugging operation on a leaking drum. Response teams should use training opportunities to practice the tasks discussed here. Only through training can you develop the comfort, capability, and confidence to perform well.
Reference
1. 2000 NA-ERG Guide 111, 186.
CHRISTOPHER BRENNAN is a firefighter with the Darien-Woodridge (IL) Fire Protection District and a field staff member of the Illinois Fire Service Institute.
