COLLAPSE ON DEMOLITION SITE BURIES WORKER

BY DAVID TOBIN

On June 18, 2003, at 1048 hours, the Grand Rapids (MI) Fire Department dispatched a full assignment to 201 Monroe NW on the report of a partial collapse at a construction/demolition site. The dispatch indicated that one of the construction workers was trapped. The worker was seen on an escalator at the time a corner of the auditorium’s seating platform fell onto the stairwell, which collapsed and buried the victim.

Two major projects were underway on the site at the time of the incident: the construction of a one-million-square-foot exhibition hall and the demolition of a 5,000-seat auditorium. Both were connected by a convention center. Part of the auditorium under demolition sat over a portion of the convention center. Unfortunately, that was the part that collapsed, burying the escalator and the missing worker.

INITIAL ACTIONS

Rescuers approached the scene from a room adjacent to the top of the escalator. They were confronted with a wall of debris that completely filled both escalators and towered well over their heads (photo 1). They confirmed that an accountability check of the 400-plus-person construction crew had been conducted and that only one worker was missing. He was last seen on the top steps of the now-buried escalator.

Although the first-arriving companies had little or no collapse rescue training, their emergency response experience was evident in the way they performed initially. They confirmed that the utilities were secured, conducted a site assessment, began selected debris removal, and started a surface search as “a collapse rescue.” They also established command and had the foresight to immediately call for the department’s heavy collapse rescue trailer.


(1) Rescuers were confronted with a wall of debris that completely filled both escalators and towered well over their heads. [Photos by Julianne Chan, Grand Rapids (MI) Police Department, unless otherwise noted.]
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The collapsed debris was confined to an area approximately 12 feet wide and 30 feet long (or the length and width of the two side-by-side escalators). It started on the landing at the top of the escalator and filled most of both escalators to the lower level. Debris was hanging, on three sides, over the escalator corridor.

Rescue technicians from the cities of Kentwood, Wyoming, and Grand Rapids, Michigan, were notified and scheduled for response. Special equipment was requested from the neighboring Walker Fire Department. Ambulances and the Grand Rapids Fire Department’s emergency medical services coordinator were dispatched as the medical sector. The incident management system was implemented, and technical operations began.

TECHNICAL OPERATIONS

Scene control was difficult from the start. The incident commander (IC) and I, who served as the operations officer, allowed the construction workers to remain on the scene. This decision was based on the following considerations:

  • The construction crew worked in this environment on a daily basis.
  • The workers had skills useful in collapse stabilization.
  • The workers had a well-supplied tool and supply cache.
  • The construction crew’s knowledgeable foremen were willing to assist in any way necessary.

Although allowing them to remain on the scene created a “scene control challenge,” their assistance proved to be invaluable throughout the incident.

Rescue operations were established near the top of the escalator at the A side of the incident. This was the only safe approach to the collapse site that would also provide access to the last known location of the missing worker. Any other route to the scene would involve rescuers having to traverse over unstable debris that would expose them to unacceptable hazards.

A surface search was conducted from both the A and C sides while a reconnaissance of the entire site was initiated. The A-side search was conducted from the landing at the top of the escalator; the C-side search was conducted from the bottom of the escalator.

Rescuers searching on the C side were careful to stay off the debris pile that filled the escalator from the basement to the first floor (photo 2). Any disturbance of the debris was likely to cause a secondary collapse that could fatally injure rescuers and the victim. Rescuers, however, were able to climb up the sides of the escalators from the basement and search without disturbing the debris. Unfortunately, neither the search camera, designed to search voids, nor the thermal imaging camera proved successful in locating the worker. A hail search, a systematic procedure of calling and listening for the victim, was also tried, but to no avail.

I assigned a crew with collapse rescue training to continue the tasks of selected debris removal, search, and hazard abatement from the A side. I then turned my attention to the reconnaissance of the entire site.


(2) Rescuers searching on the C side were careful to stay off the debris pile that filled the escalator from the basement to the first floor.
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(3) The cantilevered seating platform was hanging over the buried escalator shaft. The 7,000-lb. concrete slab can be seen in the background. (Photo by author.)
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(4) Multiple pieces of concrete were suspended on thin wire over the top landing of the escalator.
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RECONNAISSANCE

Rescue technicians returned from their reconnaissance of the site and briefed me. The reconnaissance indicated there were major hazards directly over the area where the worker was last seen. I decided to conduct a secondary reconnaissance with the rescue technician in charge of the initial reconnaissance, the site construction foreman, and a structural engineer. This secondary survey was used to develop the incident action plan.

The results of the reconnaissance were as follows:

  • Hazard 1: a fractured horizontal beam that was above the B side of the escalator shaft. The beam ran parallel to the now-buried escalators.
  • Hazard 2: a 7,000-pound piece of concrete hanging by small-gauge wires approximately 30 feet above the top of the escalator (above the A side). The structural engineer felt that this slab could fall at any time and should be the top priority for stabilization.
  • Hazard 3: a cantilevered seating platform hanging over the B side of the incident (photo 3) and sitting directly above the fractured horizontal beam (hazard 1). The column supporting the damaged side of the platform was in danger of kicking out and causing a secondary collapse.
  • Hazard 4: multiple (10) pieces of concrete suspended on thin wire over the top landing of the escalator (A side). These chunks of concrete ranged in weight from 30 to 150 pounds (photo 4).
  • Hazard 5: the C side “lower” or the area at the bottom of the escalator. Both escalators were filled with debris. On evaluation it was decided that moving any of the debris from the bottom would cause the entire pile to shift, reducing the victim’s survivability profile and endangering firefighters.
  • Hazard 6: a debris pile hanging in the corner above the B/C side. Evaluation indicated that this pile was fairly stable and that operations could be conducted below as long as monitoring by a dedicated safety person was in place.
  • Hazard 7: a debris pile above the C side. Two large pieces of concrete needed securing; the rest of the pile warranted only observation while rescuers worked below.
  • Directly across from the A side (on the C side) was the bottom landing of the now collapsed stairway. This platform was accessible and deemed a safe work area. Utilities were shut off before the demolition began.

PLAN DEVELOPMENT

Information gathered during the reconnaissance was used to create an incident action plan. Because of the presence of unacceptable hazards, the operation would be twofold. The first strategic goal would be the mitigation of unacceptable hazards or defensive operations. After the first goal was achieved, rescue crews would transition to offensive operations and selected debris removal-rescue/recovery.

SUSTAINED ACTIONS

Tactical Operations

Tactical operations were divided into three phases:

  • The stabilization of major overhead hazards—those with the potential to fatally injure everyone working in the rescue area. These hazards would be addressed while limited operations continued on the A side.
  • The stabilization of general overhead hazards—those with the potential to fatally injure individuals working in the rescue area.
  • Select debris removal-rescue/recovery, after phases one and two were completed, when operations would transition from defensive to offensive.

Phase 1: Stabilization of Major Overhead Hazards

Three major overhead hazards were identified: the fractured horizontal beam above the B side of the escalator shaft, which ran parallel to the buried escalators; the 7,000-pound piece of concrete, hanging by small-gauge wires approximately 30 feet above the A side; and the cantilevered seating platform hanging over the B side of the incident and directly above the fractured horizontal beam (hazard 1). The three mitigation operations were conducted simultaneously.

While operations continued on the A side (hazard 1), a second crew, accompanied by a construction foreman, was sent to stabilize the 7,000-pound piece of concrete hanging approximately 30 feet above the A side (hazard 2). At the same time, a rescue technician, a construction foreman, and construction workers were sent to stabilize the cantilevered seating platform hanging over the A/B side (hazard 3).

As crew leaders developed plans, the plans were conveyed to operations and approved.

Hazard 1 operation.

Once sufficient debris was removed, the crew erected a two-post vertical shore to support the fractured horizontal beam. That operation was routine; however, the crew had to support the sole plate (bottom of the shore) with a platform constructed from 6-foot-long 4-inch 2 4-inch pieces of lumber. Because much of the area below the top escalator platform had no support, it would never have supported the intended load. Therefore, the constructed platform was used to transfer the load to the solid concrete on the sides of the escalator landing.

Once the beam was shored, selected debris removal continued on the A side. Most of the debris was moved by hand with assistance from the construction crew. There was also a cutting operation with the oxyacetylene torch and a small shoring operation.

Hazard 2 operation.

The plan was to use an existing truss to support the 7,000-pound slab of concrete. Once the structural engineer agreed that the truss could be used, the operation began. One rescuer was sent to the truss to make the connection that would hold the concrete slab in place. The only access point to the truss was a catwalk approximately 150 feet north of the desired connection point (right above the concrete slab). To safely reach that point, the rescuer had to set his own fall protection as he made his way through the steel. Once the rescuer reached the area directly above the concrete slab, he placed an anchor (a 3/4-inch wire rope sling), capturing the bottom chord of the truss and the diagonal web member. He then used a tagline to haul a chain-fall into the steel. The chain-fall was then connected to the wire rope sling anchor attachment.

At the same time, a second rescuer was lowered (two-line technique) to the concrete slab. With assistance from a technician working below the adjacent seating platform, the rescuer attached a cable to the slab. The cable was hauled up by support staff and connected to the chain-fall now hanging from the truss. The chain-fall was tightened and the slab was secured. Meanwhile, the rescuer secured smaller pieces of concrete that could slide off the larger slab. Rope and anchor straps were used to complete that evolution.

Hazard 3 operation.

The reconnaissance conducted previously revealed the presence of a structural concrete column under the cantilevered seating platform. That column had to be stabilized to secure the seating platform and to minimize the possibility of a secondary collapse.

The column was stabilized with cables. One end of a cable was secured to the column’s upper portion while the other end of the cable was anchored to a vertical structural I-beam. The construction crew opened a wall to expose the I-beam. After both connections were made, the cable was tensioned using a chain-fall.

The stability of the column was then reevaluated; it was decided that a second cable would be attached to the lower portion of the column to prevent it from “kicking out.” This evolution was the same as the first, except that a come-a-long instead of a chain-fall was between the column and the structural I-beam used to tension the cable.

Phase 2: Stabilization of General Overhead Hazards

Most general overhead hazards were removed by hand or anchored in place (photo 5). However, the 10 pieces of concrete suspended on thin wire over the top landing of the escalator (A side) had to be removed before the selected debris removal-rescue/recovery (phase 3) could begin.

The concrete was too high and too heavy to be removed from below. Cutting the wires and letting the concrete pieces drop on the debris pile were not options, since rescuers were still operating in the rescue mode.

The concrete pieces had to be removed by rope. A rescuer was lowered from an opening in the D-side wall approximately 50 feet above the concrete pieces. Two other ropes were lowered to assist him: The first had a pair of bolt cutters tied to it and the second a carabiner and a long nylon anchor strap.

The rescuer was lowered to a position even with the hanging pieces of concrete. He chose a piece of concrete, wrapped it with the anchor strap, and attached the carabiner and rope to the anchor strap. Crews assisting from above tensioned the rope now attached to the piece of concrete. The rescuer cut the wire holding the piece of concrete with bolt cutters. The crew assisting from above lowered that piece of concrete to the ground.

This process was repeated until all of the concrete pieces were removed. Now that the general overhead hazards were stabilized, offensive operations could begin.

Phase 3: Select Debris Removal-Rescue/Recovery

A state police search dog was allowed on the debris pile. The dog immediately focused on the area where the worker was last seen. At that time debris removal began from the A and C sides. For the most part, the debris was moved in five-gallon pails. However, some large slabs had to be moved. One slab was broken into smaller pieces with a breaker as others were dragged from the site (photo 6).

At approximately 2228 hours, the worker’s body was recovered. It was found where he had last been seen (photo 7). The coroner’s report determined that the worker had died of asphyxiation within five minutes of the collapse.


(5) Most general hazards were removed by hand or anchored in place. (Photo by author.)
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(6, 7) The remaining large slabs of limestone were either broken and removed or dragged whole from the site. At approximately 2228 hours, the worker’s body was recovered from the location where he had last been seen, on the top step of the escalator. [Photos by Gretchen Ross, Grand Rapids (MI) Police Department.]
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(7)
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TERMINATION

An accountability of rescuers was conducted as equipment was gathered, inventoried, and restocked. Operations were halted; site security was turned over to local police. Two post-incident analyses were held the following week—one for the Grand Rapids Fire Department and the other for all responding agencies.

LESSONS LEARNED AND REINFORCED

As with all emergency response incidents, the opportunities for learning were significant. Many areas where improvement could be made were identified post-incident along with positive findings.

  • From the time of the initial response, scene control was challenging to say the least. There were times when unauthorized individuals were in hazardous areas. Earlier assignment of a scene control officer would have been beneficial.

The decision to let the construction workers remain on the site compounded this problem. However, considering the valuable contributions the crew made in labor, expertise, and equipment, they were considered an instrumental part of the operation. The command staff agreed that under similar circumstances they would be allowed to remain on-scene.

  • The command post was located right next to operations on the A side of the incident. It was agreed that command should have been located in an area away from operations.
  • As operations officer, I did not have an assistant. An assistant (or two) would have helped me in communications, documentation, and scene control.
  • One of the rescue crews was operating with a group leader who was not an officer. Group discipline became as issue as fatigue set in and tempers shortened. Assigning an officer to all rescue groups is a must.
  • The construction crew’s contributions were invaluable, from the manual moving of debris to the technical expertise in constructing hazard-stabilizing systems.
  • Having a structural engineer assist in the identification and abatement of hazards greatly helped me. With a structural engineer at my side, I was able to conduct a risk/benefit analysis and have great confidence in the decisions made as a result of that analysis.
  • Because of recent regional training conducted by the West Michigan Technical Rescue Team and statewide training developed and conducted by Michigan Urban Search and Rescue (MUSAR), rescue technicians from different departments were able to function as one cohesive unit.
  • Rescuers were able to incorporate skills learned in multiple technical rescue disciplines without missing a beat. Disciplines combined and applied during the incident included confined space rescue, rope rescue, and building collapse rescue. Again, training provided by MUSAR made this possible.
  • Multidiscipline skills will be incorporated in future regional training.

In retrospect, most involved in the incident agreed that the incident went well. The reconnaissance and the risk benefit analysis provided the basis for making sound decisions. Even though the environment was extremely hazardous, rescuers sustained no injuries.

DAVID TOBIN is a lieutenant in the Grand Rapids (MI) Fire Department, where he has served for 19 years. He is a Michigan Urban Search and Rescue collapse rescue, rope rescue, and confined space rescue instructor and a rescue instructor at Michigan State University. He was the operations officer at the Monroe NW collapse incident.

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