BY CARY DARNELL
The prevalence of construction makes the potential for cave-ins high. Responders called to help with rescue or recovery in these incidents are at risk for injury and death. Trench rescue may not happen often, but when it does occur, you should be adequately prepared so that you can effect rescue or recovery safely and efficiently.
When we are called to a structure fire, whether in an occupied dwelling, a vacant building, or an office that is not supposed to be occupied at night, we have to search to make sure no one is in the structures. But, our main job is extinguishment. In a trench incident, on the other hand, we know while en route that someone is trapped, or we would not have been called. We tend to think such an emergency won’t occur in our community.
When responding to the site of a trench entrapment and seeing the worker down with dirt piled on him, there might be a tendency to think, “I want to be the one to rescue this worker; I’ll just jump down there and pull him out. What can happen? The collapse has already occurred.” But, following that impulse may be the last thing you will ever do. Just because one collapse has occurred does not mean there cannot be additional collapses.
What if no collapse has occurred? Should you jump into the trench to find out what’s wrong with the victim? What if 200 rattlesnakes are down there? What if the atmosphere is deficient in oxygen? What if a nitrogen line ruptured and there is no oxygen in the trench?
Many incidents involving trenches occur because of inadequate planning. For the construction company, correcting mistakes means the job will take longer to complete, adding to the job’s cost. In most cases, the contractor bid on these jobs. The company will not make money if it goes over budget. Therefore, the tendency for contractors is to rush to get done fast, cutting corners in the process. When an emergency occurs, we are called.
 A wood-cutting area. Note the saws, cribbing, and planks. A first responder can cut the wood. |
We will be seeing a lot of trench work in our jurisdictions. One study I saw recently noted that many underground pipelines are eroding and will have to be replaced. We, therefore, have to be aware of the hazards this type of response presents.
TRAINING
Knowing how to make the trench safe to enter gives rescuers and victims a better chance of coming out unscathed. Rescuer safety is the number one consideration. Only personnel with advanced training and knowledge should be assigned as rescuers. The three levels of certification are awareness, operations, and technician.
Awareness level training may consist of two to eight hours of classroom instruction. All responders to rescue incidents must be trained at least to this level to be on the scene. They are not considered rescuers and should not enter the trench; they work in a nonentry capacity. A first responder trained to the awareness level-or attendant-must
- be familiar with and understand trench rescue operations and goals;
- maintain safety during rescue and training;
- demonstrate proficiency in constructing from outside the trench mechanical systems the entry team may need;
- select the personal protective equipment that will provide the adequate level of protection for the team; and
- know how to work as a team, monitor the working area, and implement the incident command system.
(Many cities and towns join together to form confined space, haz-mat, and trench teams. Some areas have countywide teams-the county purchases the equipment, and the teams from within the county train together to form a countywide unit.)
 First responders can also help locate the supply trailer and assist in setting up near the equipment area. Lay down tarps on which to place the equipment. |
Operations-level certification training may consist of eight hours of classroom instruction and eight hours of hands-on training. This responder can effectively support and participate in a rescue under the supervision of personnel trained to the technician level.
Technician-level certification may consist of eight hours of classroom instruction and 16 hours of hands-on training. These responders can recognize the hazards on the scene, including those posed by the equipment in use, and coordinate, perform, and supervise the incident. This level involves search, rescue, and recovery.
 A side wall shear. The first thing to look for in or near the trench when performing the initial size-up is the victim or his equipment: a hard hat, a shovel, a lunch bucket, or boots. |
Rescuers must have a mastery of rescue tools (they should be familiar with and have trained with new tools before the tools are placed on the rig). They should be knowledgeable in the following areas: soil composition2, the goals and objectives of a trench rescue, the phenomenon of a cave-in, confined space operations, monitoring, and ventilation.
 A worker on a ladder sets up the second shore. When shoring, work from the top of the trench to the bottom. Tighten shores with wedges. |
Many fire training academies have permanent trench simulators with 20-, 24-, and 30-inch tunnels built into the trenches for use in confined space training. A trench simulator is a good confined space training ground, since a trench is a confined space and presents the same hazards: limited or restricted means for entering and exiting, oxygen deficiency, flammability hazards, and toxic atmospheres. There may also be an engulfment hazard in the case of a secondary collapse.
The simulators I have seen have a concrete-filled bottom and side walls. There is usually a lip surrounding the outside of the trench and sometimes even 10 inches above ground level. Part of the training involves setting up ground pads, either 3/8-inch 2 2 foot 2 8 foot plywood or 2-inch 2 12-inch 2 8-foot planks. With the lip that high, it’s hard to train properly.
I have also noticed that when they dig out the trench during training, the dirt pile is right next to the trench. The Occupational Safety and Health Administration (OSHA) says it must be at least two feet away from the trench. Also, most of the simulators are on hills, making it difficult to get the amount of dirt needed to the top for burying the “victim.”
Another disadvantage of the poured concrete floor and walls is that students cannot experience a wall cave-in, which is usually what happens to the trench in an incident. When burying the “victim” for training, you can only bury him on top. In a real trench emergency, the dirt has to be removed from the trench before beginning the search for the victim. It is a long, exhausting process. An entrenching tool (E-tool) is used to fill five-gallon buckets with the dirt. Rescuers outside the trench raise and empty the buckets and then lower them, repeating the process. The crews in these simulated trenches know there will be no collapse because of the concrete walls and floor. As soon as they dig out the small quantity of dirt, the victim is found.
On the other side of the coin, simulators are good for training new team members who may be a little nervous about a wall collapsing. But there is no more realistic training than that involving a dug-in-the-ground trench that is eight feet deep by 31/2 feet wide by 12 to 16 feet long.
BASIC TRENCH RESCUE RESPONSE
OSHA issued the first excavation and trenching standard, 29 CFR 1926.650, 551, and 652, in 1971.1 Since its inception, OSHA has amended the standard several times to increase worker protection. Nothing in the standard, however, says anything about common sense. OSHA defines a trench as a narrow excavation below the surface of the ground that does not exceed 15 feet and is deeper than it is wide. Based on the fire department responses I have made, most trenches are about 31/2 feet wide and six to 10 feet deep.
OSHA requires that a competent individual inspect trench work on a daily basis, including monitoring the trench for oxygen, flammables, and toxicity. To control costs, the inspector assigned by the construction company may not be on-site or may be responsible for other jobs on-site as well.
OSHA also says workers should be protected by shielding, but this directive is not always followed. The common attitude encountered on the job site is, “My operator has dug hundreds of trenches without collapse, and I won’t need shielding.” Well, these workers have just been lucky.
On a job site, the areas in which pipe has been installed should be backfilled and compacted after the work has been done. Sometimes, however, workers are careless, and the backfilling is not always done.
ON-SCENE PROTOCOL
Being aware of the hazards when arriving on the scene of a trench rescue is important. Even if you are not trained in trench rescue, you can do many things before the trained rescue team arrives. Keep in mind that safety is the number one consideration: Never put yourself where you may become a victim.
Rescue operations depend on making the site as safe as possible. As already noted, a trench rescue is a confined space operation. Monitor the atmosphere in all parts of the trench continuously before entering. Monitor in the following order: oxygen content, flammability, and toxicity.
Be aware of the types of equipment the rescue team carries with it and what will have to be brought on-scene. Call for reinforcements early.
Request a medical unit early in the operation. Sometimes, those in command forget to do this. Not only the victim (if alive) should be monitored. Rescuers’ vital signs should also be checked before entering and when exiting the trench.
 A speed shore is put in place. |
Set up ground pads and ladders on each side of the trench.
Do not monitor the trench until the proper equipment is on-scene and the trench has been shored. Then, monitor for oxygen, flammability, and toxicity, in that order. If the atmosphere is oxygen-deficient, the rescue crew will have to don SCBA or supplied air respirators before entering the trench. If air is needed, it’s a good idea to have a cascade system on-scene because bottles may have to be changed often if the atmosphere is toxic. As mentioned, keep in mind that OSHA requires that all materials and equipment be at least two feet from the trench’s edges. Keep all emergency vehicles away from the trench area, and monitor the trench whenever anyone is working in or around the site.
Even when training, monitoring equipment should be set up and operating in the trench before personnel are in the area.
SIZE-UP
After you have put the ground pads down, start the laddering and monitoring, and begin gathering the wood you will need. When building wood shores, start from the top, and work to the bottom. During your size-up, look for the worker or his equipment, and determine from his coworkers the area in which he was last working. Do not let anyone enter the trench.
 Make sure the victim is properly strapped into the stokes basket. If the confined space is small, the patient may have to be removed on a stretcher. |
The rescuer should be wearing a harness that is tied to a rope. Never lower the rescuer below waist level when starting the building process.
SHORING
When shoring a trench less than six feet wide in Type A soil, use 4-inch 2 4-inch struts. If the trench is more than six feet wide, use 4-inch 2 6-inch struts. For Types B and C soils, use 4-inch 2 6- inch struts throughout the trench. Place the top strut 24 inches below ground level. You may need wedges to tighten the strut. Once the top strut is tight, the rescuer moves down the ladder and installs the second wood strut no more than 48 inches lower than the top strut and no less than 24 inches from the bottom of the trench.
If shoring an L-shaped corner or a T-three-way trench, do all two or three sides together. Scabs are used to keep struts, being wood, rams, or other hydraulic equipment, from moving once set up. Nail them into the walls. This does not mean you can walk on the struts. Usually, two rows of strutting are adequate for an eight-foot-deep trench. Anything deeper needs at least a third row.
Hydraulic or air speed shores expedite the process. Proper training is important. These tools are very expensive; some fire departments do not have a budget to purchase them. One very good hydraulic set consists of jacks and rams that extend with the push of a button. Make sure that these rams are level during use. They can be heavy, so tie ropes on the ends and lower from the top of the trench. Speed shores can help expedite shoring. They are lightweight and adjustable in length and can be lowered by ropes and pumped into place.
PATIENT PACKAGING
Once the victim is dug out after maybe tons of dirt have been removed with an E-tool, a pry bar (where the dirt is hardened and must be chipped at; sledgehammers may be needed if boulders are present), or the bare hands, remove the victim with a packaging device. A stokes basket or a stretcher (if the area is too small for a stokes) may be used. One good way to raise the victim is by angling a ladder into the trench. Tie a rope to the stokes, and use webbing to strap the victim into the basket. Have the crew on top of the trench raise the stokes to ground level.
GOALS AND OBJECTIVES
Obviously, the objective of training in a full-blown trench rescue scenario is to use the skills and training you have mastered to make the evolution (and any trench rescue emergency to which you might respond in the future) successful and safe. Remember to restock your unit before putting it back in service.
Remember that medical personnel must monitor rescuers’ as well as victims’ conditions, especially when the incident is lengthy.
Understanding the difference between a first responder’s role and that of an advanced operational rescuer’s job at a trench incident and having both teams work together will ensure a well-coordinated operation.
You may never be called to respond to a trench rescue emergency; however, if you do not understand what’s involved and do not train for it, things will go wrong if one should occur.
Endnotes
1. See also National Fire Protection Association (NFPA) 1006, Standard for Rescue Technician Professional Qualifications-2000, and NFPA 1670, Standard for Operations and Training for Technical Rescue Incidents-1999.
2. Soils are categorized by the Occupational Safety and Health Administration and the National Fire Protection Association according to their properties and performance characteristics:
Type A refers to cohesive soils that have a comprehensive strength of 1.5 tons or greater per square foot. Examples include clay, sandy clay, and clay loam.
Type B soils are cohesive soils with a comprehensive strength greater than 0.5 but less than 1.5 tons per square foot. They include gravel, silt, silt loam, and light clay loam.
Type C soils are cohesive soils with a comprehensive strength of 0.5 or less tons per square foot. They include granular soils, gravel, sand, and submerged soil from which water is freely flowing.
CARY DARNELL is a 17-year veteran of the Gary (IN) Fire Department, where he is a lieutenant on Squad 2. He is an NFPA-certified fire officer 2, an instructor 3, a hazardous materials technician, an EMT, and a rescue scuba diver. He is confined space coordinator for E.R.M. Inc., Alsip, Illinois, where he teaches hazardous materials, confined space, and other fire-related courses to fire departments and industry emergency response teams. He was a lead instructor for the FDIC Hands-on-Training program.
