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First Responders at the Operational Level, in addition to carrying out the actions of the Awareness Level Responder, may take defensive actions from a safe distance which will control the release and keep it from spreading. These actions are intended to protect nearby persons, property, and the environment from the effects of the release. Generally, First Responders at the Operational Level are not trained to enter the Hot zone and should not do so unless they have had specific training in dealing with the material and situation present.
In situations where there is only a release and no fire, Operational Level personnel should consider diking or diverting liquid runoff to prevent contamination of sewers or waterways. This must be done well ahead of the runoff to prevent personnel exposure and should only be attempted if it can be done safely. For release of gases it may be possible to suppress vapor clouds with fog lines or other agents using unattended monitors. For large releases, particularly of toxic gases, consider the evacuation or sheltering in place of populations downhill or downwind of the release. Remember that wind direction may shift during an incident and on-site wind direction monitoring is essential. You may be able to shut off a release from a safe distance. Do this only if the material is identified and the shutoff is outside the Hot zone.
If a fire is present in addition to a release, the incident is considerably more complicated. All of the tasks discussed previously must be considered and a decision must be made whether to fight the fire, and if so how. It is generally best to let a gas-fed fire burn unless you can stop the flow of gas by closing a valve at some distant point outside of the Hot Zone. Keep in mind that after you close a distant valve there will still be some gas in the line(s). Use fog lines to keep the area cooled and let the fire burn itself out. There may be an incident where it is necessary to extinguish a gas-fed fire in order to get to a valve to shut off the flow. Large amounts of fog may be used to cool down the area. Dry chemical or carbon dioxide extinguishers may be used to extinguish the fire. Extinguishing the fire without stopping the flow of gas is dangerous. The gas and air may form an explosive mixture. If the surrounding area is still hot it may provide an ignition source and cause an explosion. The explosion may cause more injuries and more property damage than the original fire.
If the products of combustion are less of a hazard than the leaking chemical, the best course of action may be to protect exposures and let the chemical burn itself out. The location of the incident will influence your decision. If you are in a rural area that is sparsely populated, the decision to let a fire burn will be much easier than if you are in the central business district of a major city. There may be pressure on the Incident Commander (IC) to extinguish the fire in order to minimize inconvenience to the local population. You must weigh all of your options and choose the course that presents the least risk to your personnel and the general public. The potential for harm is always more important than convenience. In some circumstances, if the identity of the material(s) is not known it may be better to let the material burn and concentrate on protecting life and surrounding property.
Foam can be very effective at vapor suppression and extinguishing many flammable liquids. Some materials, such as alcohols and amines, are water soluble and break down ordinary foam. You will see a listing "consider the application of alcohol based foam" for materials that are water soluble. Alcohol based foam is designed for these materials. If alcohol based foam is not available, regular foam may be helpful but may be required in higher application rates. Check your foam supplier and the container label for the uses and limitations of the foam you have. Keep in mind that 6% foam is 94% water. The use of foam on materials that are water reactive may not be desirable. The reaction may be so great that it will outweigh the benefits of using foam. If you are going to attack a fire with foam BE SURE you have enough foam at the scene before you begin your attack. If you start without enough agent to finish the job, the fire will rekindle and destroy the foam blanket you have applied and you will lose any advantage you may have gained.
Carbon dioxide (CO2) and dry chemical are effective on many products. The limiting factor is the method of application. Generally, these agents come in handheld extinguishers requiring you to get within a few feet of the fire. With most hazardous materials, that is too close for personnel at the Operational Level. Handheld equipment is meant for first aid fire fighting and is designed for use on small fires. Some facilities have special extinguishers on wheels or vehicles containing dry chemical or CO2. Many large fire departments also have this equipment. If you have these kinds of resources you may be better able to fight larger fires. CO2 and Halon gases, are more effective at fighting fires in confined spaces - but they also present a significant asphyxiation risk to responders under these circumstances. Fires involving combustible metals usually require dry powder (not the same as dry chemical) extinguishers. If water is the correct agent to use, it is usually applied in the form of fog and applied in large volumes. Solid streams will cause powders and other materials to be spread about in an uncontrolled manner. Solid streams directed into burning liquids will splash the burning materials and may spread the fire. If you are operating at a fixed facilities, you should know in advance how much water you have available for fire fighting. At a transportation incident you may not have the volumes of water needed to safely attack a fire. "Back Off and Protect the Exposures" may be your best option. You don't attack a tank (military version) with a 22 caliber handgun. "If you don't have the water don't go to war."
Fog streams from unattended monitors or even large volume handlines that are tied off, can be effective in knocking down or suppressing vapors. Be aware that the mist that is falling back to the ground is now contaminated and must be managed. This may be done by diking or damming well ahead of the material runoff. Care must be taken to keep personnel out of danger from contamination or contact with the material. Pits may be dug to contain the runoff. With some chemicals, diluting the runoff water in the pit may reduce the hazard to a more manageable level.There may be times when it is desirable to knock down the vapors from a product that is water reactive. Under these circumstances, care must be taken to not let the water fall back onto the material. Set up your monitors well ahead of the material and be aware of changes in the wind direction or speed.
Many liquid containers, when heated, may explode or BLEVE. In a BLEVE large pieces of the tank may rocket great distances. The directions in which these pieces will travel is unpredictable and depends on the section of the tank that ruptures and on the tank supports. Tanks involved in a fire should be approached with great caution because of the risk of explosion or BLEVE.
Information about all of these concerns is provided in the material specific sections of this guide. The First Responder Strategy Using the NFPA 704 Placard can be used as a guide to fighting fires if only the NFPA 704 designations are known. Remember that this table only applies to materials designated with NFPA reactivity (yellow box) 0 or 1. For more reactive materials, maintain a purely defensive posture toward the fire.
Material Safety Data Sheets (MSDS), if they are available, are one of the best sources of information about materials. As part of your planning process get the MSDSs for major products in your jurisdiction. If you are dealing with a fixed facility, check with the Facility Emergency Coordinator (FEC). This person is required by SARA Title III to be the individual who has worked with the Local Emergency Planning Committee (LEPC) in the development of the community response plan as it relates to that facility. Make this person part of your Unified Command Staff. The FEC knows that facility and the materials involved better than you do. Listen to the advice you get, but keep in mind that the objectives of plant personnel may sometimes be different than yours. They may think first of the plant, while you must think first of the community. When there is a difference, you must make the decision keeping the good of the community in mind.
Some hard decisions are going to have to be made when it comes to rescuing victims in the Hot zone - decisions that in most cases can only be made by the IC at the time of the incident. The authors have attempted to offer some guidance, but the final decision will be yours. In the Awareness and Operational Level Training Response section of the chemical specific pages you may see the statement "Do not attempt rescue". This statement is used when the hazards to the would-be rescuer are so great that serious injury or death may result. Remember that under most conditions, if you are not trained at the Technician Level you cannot legally go into the Hot zone. In many cases normal fire fighting gear doesn't provide the protection you need to safely handle people in the area of contamination. In some situations it is possible that you might be able to rescue someone without putting yourself in danger. Danger is a relative term and the IC must determine the degree of danger present. In addition, the IC must then decide the level of danger that is acceptable for the rescue personnel. We do not trade rescue personnel for victims. Injury to emergency service personnel to effect a rescue is not acceptable in any community.