“The Challenge of Trench Rescue: “”Few Situations More Dangerous”””

The Challenge of Trench Rescue: “Few Situations More Dangerous”

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Pneumatic and timber shoring installed to prevent trench walls from collapsing.The fan (upper right-hand corner) is used to remove hazardous fumes from the trench.

There are few situations more dangerous than when emergency service personnel must attempt to rescue someone from an unsupported trench. Yet there are few situations for which fire, rescue and emergency medical service personnel are generally less prepared!

There are a number of reasons for this lack of preparedness. First there is a feeling among fire and rescue personnel that such accidents just don’t happen—that utility contractors are too well supervised by OSHA and other safety overseers to risk being heavily fined for allowing their employees to work in an unsafe area. This is not the case at all.

The number of safety inspectors is low and many contractors would rather risk an inspector showing up on a job site than take the time and effort to sheet and shore a trench that may be open for only a short time. And sheeting and shoring cost money, of course.

Potential for disaster

Another reason for the lack of preparedness among rescue personnel is complacency characterized by these too-familiar words: “It can’t happen here.” It’s true that trench accidents do not occur with the frequency of vehicle or industrial accidents, but they do happen, and they happen everywhere. There is probably not one fire protection district in this country in which the ground is not opened during any given work day, weather conditions permitting. Utility contractors dig trenches for new electric feeder, sewer, gas and water lines.

And wherever the ground has been opened and the walls of the trench have been left unprotected, there is the potential for disaster.

Still another reason for unpreparedness arises from the feeling that exists among many fire fighters and rescuers that trench rescue is not the job of the fire department or rescue squad. A statement like this causes one to wonder just whose job trench rescue is. The Red Cross? The Salvation Army? Or perhaps the contractor who is responsible for the incident? No, it is clearly a fire department responsibility.

Solving the equipment dilemma

The apparent need for expensive equipment is cited as another reason for not being prepared to effect a rescue from a trench. It’s true that proper sheeting and shoring devices are required to make a trench rescue operation safe, but it’s not true that a fire department or rescue squad has to procure and store such equipment to be prepared for this specialized operation.

Conventional sheeting and shoring devices can be found in the equipment stores of utility contractors, plumbing contractors, water departments and municipal, county and state highway garages. And, of course, building supply dealers have sheets of plywood, timbers and lumber that can be used as makeshift sheeting and shoring when conventional materials are not available.

A fire chief or rescue officer needs only to locate this equipment and develop an agreement with a key person so the equipment can be made available on short notice.

Knowledge needed

All of these reasons for the lack of preparedness notwithstanding, perhaps the most common is the lack of knowledge among emergency service personnel about the danger of an unprotected trench. It’s not unlikely for untrained rescuers to jump into an open trench 5, 10,15 or even 20 feet deep and start to dig out a buried workman by hand. The feeling often exists that if one cave-in has occurred, another is unlikely.

Ladder wales bridge the gap of a collapsed area and spread loading horizontally. They are secured at the ends with shoring

—all photos courtesy Rescue Training Associates.

A specialized trench rescue vehicle allows sheeting, shoring and other materials to be stored and transported for rapid use. The equipment could also be used at a building collapse.

Yet a secondary cave-in of the trench lip or slough-in of the trench wall is not only likely, but is also highly probable when the ground is unstable and the weights of emergency service personnel, bystanders, construction workers and even rescue vehicles accumulate on the ground around the trench.

Ignorance also exists as to what forces are required to kill in an open trench. It does not take a great deal of compressing force to squeeze the life from a person. An individual lying on the floor of a trench with only 1 foot of dirt covering him must endure from 500 to 600 pounds concentrated on the surface of his chest or back. The resulting force will prevent the chest movements that are necessary for breathing, even if the person’s head is in an air pocket and dirt is not closing his mouth and nose.

Think of the weight and compressing force imposed by several feet of dirt.

In response to the need for emergency service personnel to be trained for this highly specialized rescue operation— especially in areas where there is a great deal of underground utility construction underway or planned—Rescue Training Associates has developed a unique trench rescue training program. The architect of the course is RTA partner Jim Garsan, who has combined more than 30 years’ heavy construction experience with an extensive fire service and fire training background.

Trench rescue training

Any basic trench rescue training course should be designed to prepare emergency service personnel for the task of making trenches safe with sheeting and whatever shoring devices are available locally, whether they are timbers or mechanical, hydraulic or pneumatic shores. Rescuers should learn to perform operations in sequence during 10 distinct phases of activity: preparation, response, assessment, hazard control, support, gaining access, emergency care, disentanglement, removal and transfer, and termination.

It would be hard to conduct trench rescue training without a drillground prepared to resemble an actual construction site. Ideally, a trench would be dug 40 feet long by 4 feet wide by 8 feet deep. The spoil pile, batter boards, various tools, and even lengths of pipe and machine tracks would be situated where they would normally be found on a pipe-laying job site. These elements add realism to the scene, to be sure. However, the rescuers also learn to recognize them as clues as to where a workman might be buried following a cave-in.

Making trench safe

After the orientation period, the instructors should demonstrate (and teams of rescuers practice) the technique for making a trench safe with plywood sheets and timbers. While some team members make the area around the trench safe by moving debris and positioning ground pads, other team members cui shores to the proper size and make the wedges and scabs that are required to hold the shores in place against the sheets. Then the team members work together to install the sheeting and shoring.

Safety must be kept uppermost in everyone’s mind. Accordingly, the team members should learn to install the first pair of sheets and shores from ground level instead of from an unprotected area in the trench. Moreover, they should learn to install succeeding pairs of sheets and shores only while working in the newly protected areas. Another important point to be made about the techniques of sheeting and shoring is that they exceed the requirements established by OSHA and Cal/OSHA.

Well-trained rescuers are able to make a 12-foot section of trench safe with pneumatic jack shoring in less than 12 minutes.

Since not all trench accidents are alike, rescuers should learn how to make a trench safe when a portion of the spoil pile slides in, when one or both of the trench lips has caved in, and when a section of wall has sloughed in.

Digging

When the trench has been made safe with sheeting and shoring, rescuers start to dig. So personnel can gain an appreciation for how much dirt might have to be lifted from the floor of the trench in a real rescue operation, each bucketful can be weighed before it is dumped. In a typical training session, over 2500 pounds of earth would be moved before uncovering the manikin. Once uncovered, the manikin is secured in a basket stretcher. Then it is threaded through the shoring and hauled to the surface. This makes a very realistic training exercise.

To paraphrase an old saying, the proof of rescue training is in the saving. Shortly after a trench rescue class was conducted in Georgia, the Cobb County Fire Department elected to equip a mobile unit with sheeting and pneumatic shoring and other materials important to a trench rescue operation. While a group of Cobb County officers were being trained in the use of the equipment one day, a call for trench collapse came in. The officers in training rushed to the scene with the equipment in a pickup truck (the new unit was not yet in service), made the trench safe, and effected the rescue of a very grateful workman.

In Pittsburgh, Pa., the city EMS division is assembling a trench rescue unit for operations that will most likely be required while construction of more than 40 miles of subway is underway. The specially designed trailer will contain special high-strength sheeting, pneumatic shoring, hand and powered tools, and other support items necessary to make it a completely self-contained unit. In both Cobb County and Pittsburgh the trench rescue units will also respond to structure collapse and transportation accident situations where heavy-duty support devices are needed.

While trench accidents are not daily events, they will continue to happen as long as people are willing to work in an unsafe environment for the sake of economy and expediency. Fire fighters and rescuers can’t prevent trench accidents, but they can surely train for them just as they do for a variety of other entrapment situations.

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