Trench Rescue

BY DREW SMITH

On September 27, 2006, at 1628 hours, the Niles (IL) Fire Department (NFD) received a call concerning a worker entrapped in a trench collapse and requested the response of the Mutual Aid Box Alarm System (MABAS) Division 3 Technical Rescue Team (TRT).

A single-story, 20- × 25-foot house was being extensively rehabbed and expanded. At the time of the collapse, the roof and the interior walls, floors, and ceilings had been removed. The rear (side C) exterior wall had also been removed, leaving the side B wall above the victim unsupported except by the A/B corner. The earth alongside side B had been excavated down to the foundation’s footing. A worker was operating in the unprotected trench, rolling a tar-like waterproofing onto the foundation wall when the trench collapsed. The hole was about seven to eight feet deep before the collapse and less than five feet deep after the collapse. Whether or not this incident met the Occupational Safety and Health Administration (OSHA) definition of a trench (a hole deeper than it is wide), it definitely was an unsafe condition for firefighters.

The initial alarm assignment was a standard structure fire response of two engines, one ladder truck, one ambulance, and a command officer. Engine 5 was the first unit on the scene, at 1632 hours; the Battalion 4 district chief arrived at 1635 hours and established command.

PREPARING THE SCENE

On arrival, Engine 5 staged three houses away to leave the front of the building open for additional resources. The Engine 5 officer sized up the incident and used plywood from the construction site to lay ground pads. The victim was entrapped facing the wall (on which he had just rolled tar waterproofing) and up against it, buried up to the small of his back in clay soil. Many of the TRT members and first-due firefighters working at the site also became covered in tar. Since the victim spoke only Spanish, a TRT member served as translator between the victim, the TRT, and paramedics.

Additional plywood was placed between the victim and the trench wall, and 4 × 4 cribbing blocks were used to create temporary shores. A ladder was also placed into the trench next to the victim. Battalion 4 requested the full TRT response at 1643 hours.


(1) The victim (circled). (Photos by Tim Olk.)

Thirty TRT members from the 18 departments of MABAS Division 3 responded along with Rescue 3, the TRT vehicle. Three heavy rescues also responded for support: Morton Grove Squad 4, Northbrook Squad 12, and Park Ridge Squad 35. Arriving well ahead of Rescue 3, the Squad 4 lieutenant (a long-time member of the TRT and a member of the Illinois Urban Search and Rescue Task Force 1) placed struts from his squad using plywood, and digging from ladders was begun. Some areas of the trench walls were benched (because of the collapse and digging), making those areas safe without shores.

On arrival, I assumed the rescue branch leader role. I observed the work of Squad 4 and the first-due firefighters and reviewed our TRT’s trench collapse checklist as I prepared for the arrival of the TRT members and the TRT vehicle Rescue 3. Plan A was to continue the initial shoring and digging. When the additional TRT members arrived on-scene, the initial firefighters would be rotated out. A cut station for cutting lumber was set up, and additional shores were placed.


(2) The trapped victim (with blanket around his shoulders) holds on to the shores. With shoring in place, rescuers dig by hand while paramedics attend to the victim, who is pressed with his face against the fresh tar-like waterproofing. Note the unsupported gas meter in the foreground.

Three TRT groups worked on shoring and digging—the original group over the victim area and one additional group on each side of the first group. The work area was tight, only about 14 feet wide from house to house. Of that, four feet was the trench. The trench was 20 feet long. Spoil piles were at each end. This made it possible to work only one side of the trench, placing all the rescuers in this tight area.

Shoring the masonry wall above the victim was a concern. A raker shore would have been the only way to stabilize the wall. However, because of the open trench, it would have been time-consuming and would have delayed the shoring and digging of the trench by more than one hour. Since the wall appeared stable and lacked any signs of distress, firefighters with experience in construction checked it periodically.


(3) The overall scene with the aerial tip. The distance between the trench and exposure 2 is less than 15 feet. The contractor placed the spoil pile against exposure 2, further impeding access. Note the wall of side B is completely unsupported, because a contractor removed the roof, interior walls, and ceiling. You can see the aerial high point with haul system.

Safety officers were placed at both ends of the trench to keep extra staffing out. A TRT safety officer monitored TRT operations in and around the trench. The natural gas meter for the building was on the exposed foundation wall at the A/B corner. About six to eight feet of gas main was found to be exposed and unsupported. The gas utility was summoned; the meter valve was checked to ensure it was closed.

As the victim was unearthed, it was noted that his legs were folded backward and he was in a kneeling position. Once his legs were exposed, the digging became tedious and time-consuming. Shoring was checked, and additional shoring had to be added as the depth of the dig increased. A sewer vacuum truck was requested to assist with soil removal. The TRT had trained on using such a device in trench collapses. However, in this case, the truck’s boom could not reach the victim.

Several firefighters and TRT personnel suggested breaching the concrete foundation from the basement side. This idea was not pursued, since the continued stability of the masonry wall above the victim was a concern. It was also unknown what effect soil pressure would have on the wall or the victim. If a large piece of concrete were removed, would the foundation wall or masonry wall collapse? Would the victim be pushed through the hole? The TRT leadership did not know and could not afford to find out. Because of the tight work area, the trench could not be widened for sloping or benching. The driveway of Exposure 2 was paved, and a large amount of the soil the workers had excavated was on it. Plan B wound up being making sure Plan A was safe and working.

VICTIM-REMOVAL PLAN

The TRT group designed a victim-removal plan involving positioning Truck 2’s aerial ladder over the victim and rigging a high-point anchored haul system. Before rigging began, the group had the ladder positioned and extended over the hole to ensure its reach. Once it was established that the ladder would reach, it was swung back to the street and lowered to grade, and the tip of the fly was rigged with a two-point anchor and a 4:1 haul system. Once rigged, the ladder was placed back over the victim, and the 4:1 haul system was staged to the side of the trench. The haul crew stood by. Safety checks included ensuring that the aerial was deenergized once in place, that the aerial operator remained at the turntable and took direction only from the TRT haul group leader, and that the anchor rigged was on the main beams and not the sacrificial section of the fly (the last three or so rungs, which are bolted on).

The TRT haul group was also informed that only the victim, a single-person load, would be hauled to ensure the tip was not overloaded. The original removal plan was to haul the victim straight up. Ultimately, the victim could not be raised using the haul system because of his position. The rigging was begun before the victim’s legs were exposed. The TRT could not get its rescue extrication vest around the victim. He would have to be rolled to the right. The TRT would wind up using brute force to lift and roll him and then pass him on a backboard out of the hole.

At one point in the operation, one of the victim’s coworkers started up the backhoe and was going to do something with it. The safety officer promptly stopped the worker and had him removed from the area without incident.

Although the operation began at about 1630 hours and it was sunny and 70°F, it ended in darkness two hours later with the temperature approaching 50°F. This had been anticipated; lights were set up early. The TRT used its confined space blower with heater to warm the victim as he grew increasingly anxious and cold because of the wet clay.

The incident commander had established an EMS group. An advanced life support ambulance was ready to transport the victim, and the paramedics were in contact with medical control. The victim received oxygen and two large-bore IVs, and a paramedic monitored him throughout the operation. Although the local trauma center wanted the patient’s EKG to be monitored, this was not possible because of the confined area.

LESSONS LEARNED

A number of things went well at this incident. Responders’ skills were polished, and teamwork was very evident. The TRT had drilled together that morning.

  • Many TRT members came up with similar ideas and passed them along to their group leaders, who communicated them to the rescue branch leader.
  • There were delays in moving equipment from the TRT vehicle to the team at the collapse site. Most non-TRT firefighters did not know where equipment on the TRT vehicle was stored or that certain tools necessarily required other components to be useful. For example, a strut needs ends, a hose with a control valve, and a compressed air supply. We are developing a plan to correct this situation.
  • The sewer vacuum truck’s reach was limited, since most municipal vacuum trucks are used on paved roads, usually directly adjacent to the manhole or catch basin.
  • Monitor the victim’s coworkers. You never know when one of them will try something, as above where a coworker, unhappy with the slow progress of rescue, attempted to use the backhoe.
  • TRT personal protective equipment (PPE) is a must. All firefighters and TRT members wore appropriate PPE for the incident’s conditions. Several of the first-arriving firefighters wearing regular structural turnouts and TRT members wearing coveralls became covered in the tar. However, there was no fire hazard. Keep in mind what gear is appropriate under the incident’s conditions and requirements. Remember, heat stress and fatigue may occur sooner to members when digging in structural firefighting PPE instead of TRT PPE.
  • Anticipate a changing environment. Darkness and colder weather set in as the incident came to a close. Both rescuers and the victim would have been affected by the conditions had this operation gone on for several hours.

The operation took two hours and one minute from when the first engine arrived until the TRT passed the victim to the Niles Fire Department paramedics in the warm zone.

This incident was clearly within the scope of operational-level personnel (as defined by National Fire Protection Association 1670, Standard on Operations and Training for Technical Search and Rescue Incidents), since the collapse involved a straight trench less than eight feet deep.

DREW SMITH, a 29-year veteran of the fire service, is deputy chief of the Prospect Heights (IL) Fire District. He has developed recruit, company, tower ladder, and aerial ladder training programs. He is chairman of the Illinois Technical Rescue Team Steering Committee and director of the regional MABAS Division 3 Technical Rescue Team and serves on the state fire marshal’s training committee. He has presented several programs at FDIC.

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