Hole Rescue

What the Pompano Fire deaprtment experienced is what I call a “Hole Rescue”.  It is a unique type of trench rescue.  This one happened to be in sand.  At hole rescues the victim and rescue entry team are in the collapse zone of all four (directions) walls.  This is almost never the case in a trench that has been cut to install utilities which usually has collapse potential from two walls.
In the next post (Hole Rescue #2) I have provided a few pictures and suggestions from one of the “hole rescues” that we have responded to.  Our hole was a little bigger and deeper (16′) than the one in Pompano but it was also in sandy soil.  It occurred a few blocks from the Saginaw River (Michigan) and was river bottom sandy soil that continued to slide as we worked.  If you have a copy of Buddy Martinette’s Trench Rescue: Awareness, Operations, Technician book you can find a “Voice of Experience” section on this rescue with more details.
The basic objectives for an awareness response are: Site control, scene management, activation of the response system, identify/mitigate hazards and perform non-entry rescues.  As a first responder (awareness level) organization it looks like the PBFD did a good job covering these objectives. As is usually the case, I assume that a non-entry rescue was not a possibility.
A concern that I have is taken from the picture of the lifeguards on an unprotected lip. The weight (surcharge) and vibration of the people working on the unprotected lip creates a high likeliness for cave in.  Had an additional cave-in occured it would have reflected poorly on the scene management/site control and could have caused additional injuries to rescuers and the initial victim.  Some of the later pictures show that the lip was protected with surfboard used as ground pads.  I hope that corrective step took place soon after arrival.  As far as problems with site control (zoning) I have found that 42″ steel pickets with barrier tape work well at a trench scene for developing a hot zone.  PD works well for traffic control and establishing a warm zone.
From a shoring design perspective the backboards that were installed by the lifeguards probably offered very little, if any, protection.  The lateral forces on each wall would be between 2,000 and 2,500 pounds.  I’m not sure what the thought was for placing the backboards in the way they are shown, however, it looks like they may have tried to push the boards into the trench floor and utilize a type of sheet piling technique.  When sheet piling is used in sand, a sheet has to be driven into the soil at least as deep as it sticks out.  For for the 8 ft. backboard they would have to be driven into the trench floor at least 4 ft.  When used in construction the sheeting material (usually steel) has to be stronger than the force it is going to resist.  In this case the backboard is probably rated for 300 pounds and the lateral force of the soil is over 2,000.  Best case scenario would be that the cave-in knocks the backboard over and creates a void (tee pee or lean-to) for the victim.  My guess is that the backboard would snap if a portion of the wall caved. I do understand that was all there was to work with at the time but working on an unprotected lip to install something of so little protective value just doesn’t compute in my risk/benefit analysis.  At trench rescues with high probability of secondary collapse we have developed a method that offers greater lip protection than traditional ground pads.  These “lip bridges” (one version seen in Hole Rescue #2 post) can be quickly installed during initial actions and left in place during the rescue operation.  The bridges elevate the working platforms above the lip and transfer the load (rescue personnel and equipment to more stable ground.  This doesn’t mean that we do not use traditional ground pads to protect a lip because we do.  Lip bridges simply offer a tactical option for certain conditions. Also seen in the (Hole Rescue #2) post is what we call “cross shoring” which is needed for hole rescues with four wall cave-in exposures.
It is always easy to “Monday Morning Quarteback” an incident.  This is not the intent of this post.  The intent is merely to offer alternative tactical options for similar rescue situations and to create discussion for the blog.   The Pompano Fire Department should be commended for their successful rescue.  Hopefully the department will continue to enhance both rescue training and equipment.

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