By Fred LaFemina
Published Monday, March 31, 2008
| From the April 2008 Issue of FireRescue
Some of the most challenging incident scenes for first responders involve tunnels. A report of a smoke condition, unknown odors or possible flooding will necessitate a speedy fire service response. Even a simple vehicle fire can create a situation in which many helpless civilians are trapped.
To complicate matters, first responders must consider terrorism when dealing with tunnel incidents. A bombing or chemical release in a confined space can cause widespread injury or death. Sabotage of the ventilation system, a dismantling of the auxiliary extinguishment systems or just tunnel congestion with disabled vehicles could present major problems. Further, some vehicles may carry hazardous materials and/or explosives, whether in line with Department of Transportation (DOT) guidelines or not. These are just a few of the tunnel emergencies I will address here, focusing mainly on the threat of a chemical release.
Tunnel Rescue Basics
Tunnels are arch-shaped, with the force of the load above spreading down the sides of the arch. At the bottom of the arch, abutments prevent it from moving outward. Tubes are cylindrical in shape and can be built of brick, concrete or tubular cast iron. Tunnels are often placed through bedrock or composites of clay and sand. Underwater tunnels may be placed directly in the silt on the bottom of the body of water.
Tunnels usually contain wide openings that allow one or two lanes for vehicles or tracks for railcars. Access to the tunnel can be attained through both openings, as well as emergency exits and crossovers (passageways between tunnels). These areas will allow first responders to transport equipment to the scene and remove victims for treatment and/or transport to hospitals.
A fire in a below-grade tunnel can produce heavy smoke and high-heat conditions. Most firefighters experience some level of discomfort when descending into below-grade or unfamiliar areas. Plus, you may need to travel a sizeable distance to reach the incident location. It is therefore critical to develop an air management plan before entering the area.
Some important questions an incident commander (IC) must consider when conducting a risk-vs.-benefit analysis: Do the department-issued SCBAs provide enough air to operate safely at one of these incidents? How far into the smoke will you allow your units to progress before you call them back? What if the ladder company conducting recon informs you they have traversed approximately 400 feet into the tunnel and have not yet reached the area of the incident? Are you confident in your members’ abilities and training? Are you confident in their equipment?
Strong leaders will recognize potential problems and not commit their forces if operations cannot be safely carried out. You may need to call in special resources—resources that were not initially available at the scene. The bottom line: You must ensure that there are enough personnel on the scene and ready to operate while instituting all safety protocols and providing for the safety of all operating members. The safety of the firefighters is your No. 1 priority.
Conduct a Size-Up
While responding to the scene of a tunnel incident, start gathering information from dispatcher reports, initial reports from units on the scene and any information that might be available from pre-fire plans. Based on what you learn, you may need to call for additional resources. Hopefully, your team has spent time drilling at the incident site and will have some understanding of the tunnel’s construction and layout.
Determine what type of incident you’re responding to. Is it a fire, terrorist-related event, an accidental hazmat release, a flooding condition? If it’s a flood, did weather or a breach in a tunnel wall lead to the emergency? Even if the incident involves a simple fender bender, play out in your mind the potential scenarios that could occur in the tunnel.
In the event of a chemical attack or an accidental hazmat release, gather as much information as possible to begin developing a strategy to mitigate the incident. Set priority objectives, such as ensuring the safety of the fire and emergency workers, and rescue and removal of persons in distress. Have units use detection devices to identify the material. Guidebooks about hazardous cargos should be carried on all apparatus to assist in this effort. Identifying the material is vital to the progress of the operation, for one, so rescuers will know what type of personal protective equipment (PPE) is needed in the tunnel. Note: We must always use properly trained personnel with the proper equipment. If this equipment is not available, you must wait for these resources prior to committing the troops.
Other units can be used to search for victims and to determine the priority of patient removal. This may require special equipment and a large number of personnel. Additionally, prior to committing to a suspected hazmat incident, you must establish a decontamination area for both civilians and emergency personnel. The medical branch should identify a triage area, considering the potential for cross-contamination and the possible need to de-con patients prior to their transport to local hospitals. Note: The extent and type of decontamination required at an operation will be dictated by the type of hazardous material or toxin released.
When operating at a terrorist-related event, all personnel must be aware that they’re working at a crime scene. Without compromising rescue and removal of victims, personnel should try to preserve the scene; this will greatly assist law enforcement in their investigation.
First-responding units should note victims evacuating in their size-up, especially if they are evacuating from a below-grade area. Do not commit fire personnel to the tunnel if there are visible unresponsive persons. Further, if personnel enter the tunnel and encounter unresponsive persons, they should immediately leave the area and proceed to a decontamination area to prevent cross-contamination. If the decon area is not yet established, these members should remain isolated. The only members who can operate under the above conditions are those with specialized training and the proper PPE and detection devices.
Command Posts & Staging Areas
Stage units upwind and away from any potential source of contamination, including the entrance and exit to the area. Identify grating coverings at street level; you may need to secure them to prevent the released material from escaping from the below-grade area.
As the IC, you should establish a command post and implement the incident command system as soon as possible. This will allow for increased control and coordination of the incident. Use a minimum number of personnel initially to perform a recon and size-up of the area. Additionally, always be aware of the potential for a secondary device until it has been determined that the incident is not terrorist-related. Request that law enforcement personnel conduct a search for secondary devices and provide security to the command post.
When dealing with a release of a product or a hazardous material, you must establish and control certain zones. The exclusion zone is the innermost area at the scene and is considered contaminated. All personnel entering this zone must have the proper PPE and training. A contamination reduction zone, the second-innermost area, is established to prevent or reduce the amount of contaminants to which personnel or equipment have been exposed. All decontamination should occur in this zone. The support zone is the outermost area. No contaminated personnel, equipment or apparatus are permitted in this zone.
Other areas you may need to establish: staging areas, forward staging areas and forward command posts. A staging area for units awaiting assignment should be established away from the scene; this will better allow you to control the incoming resources. A forward staging area may be established so personnel with advanced training are closer to the scene for rapid deployment. Finally, you may want to establish a forward command post that’s staffed by personnel with area expertise, allowing them to be closer to the scene of operations and concentrate solely on the task at hand.
Other considerations for these types of events include ventilation systems, communications, collapse potential and waterborne operations.
Depending on the type of incident, ventilation systems in tunnels can greatly assist or hinder an operation. If you’re dealing with a vehicle fire or a smoke condition from a known source, you may want to use the ventilation systems to remove smoke and contaminants. Remember: You must know the direction of supply and exhaust for these systems, especially if self-evacuation is occurring. You don’t want civilians evacuating in the direction of exhaust, as this may inhibit them from reaching the point of exit. Personnel entering the tunnel from a direction opposite the direction of exhaust may be able to operate in clean air until arrival at the point of operations. On the other hand, if there is a hazardous substance present, you may want to shut down the ventilation system to prevent the spread of the product.
Communications may be severely hampered at tunnel incidents, especially if located below grade. As such, there should always be at least two methods of communications within the tunnel. You can try to use portable radios, sound-powered phones, hard-wire communications or cell phones; however, some (and maybe all) of these devices may not operate properly or effectively.
Some tunnels have installed repeater systems that greatly enhance radio communications. You may need to set up a radio relay system by placing members at set intervals from the operation all the way to grade level to provide effective communications. The problem with this method: You have fewer personnel to operate, because once members are dedicated to the communications link, they remain in this function throughout the operation. Another issue: If dealing with an improvised explosive device (IED), portable radio and cell phone communication may need to be suspended until the device has been disarmed or removed. (For more on IEDs, see the sidebar Improvised Explosive Devices above.)
If you’re responding to a bombing in an underground tunnel, the results will likely be catastrophic. There is potential for collapse or flooding with a large number of people trapped or missing. As such, specially trained personnel may need to respond to provide water-rescue operations or shoring for collapsed sections of the tunnel.
The number of issues that could arise at tunnel incidents is endless. I used to think that some potential problems were so far-fetched, that is, until terrorists destroyed the World Trade Center and hit the Pentagon with commercial jetliners. With this in mind, always prepare for the worst and give at least some thought to the possibility of seemingly far-fetched scenarios.
FDNY just conducted an underground tunnel drill in the city to test our preparedness and identify any areas of weakness. The operation was a huge success and enabled our forces to identify areas for improvement. Be proactive and identify these areas in your jurisdiction, and prepare plans to deal with the different types of incidents you may encounter. Last but not least, remember that the safety of the operating personnel is always your No. 1 priority.
Improvised Explosive Devices ...
- Can be any type of material and initiator
- Are homemade devices designed to cause death
- May have explosives or chemicals (or both)
- Are produced in various sizes
- Can use military or commercial explosives
- Can be improvised by the builder and difficult to detect
- Come in three types: package, vehicle-borne and suicide bomb
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