On the Scene
An NFPA investigator recalls his work at Ground Zero
Immediately following the 9/11 attacks, the Federal Emergency Management Agency assembled a Building Performance Assessment Team (BPAT) to analyze six key areas surrounding the events and circumstances that led to the collapse of the two towers and other buildings on fire at the World Trade Center (WTC). The 26-member team was made up of fire protection and structural engineering experts, and included members of the National Institute of Standards and Technology (NIST). Bob Duval, NFPA regional director and senior fire investigator, joined the BPAT team at the WTC site just weeks after the attacks. NFPA Journal talked to Duval about his experience with the investigation.
What did you witness at Ground Zero?
We went down there two weeks after 9/11. They gave us hardhats and windbreakers with "BPAT" stenciled on the back. Once we were on the site, they broke us up into teams. The site at that point looked like a gigantic construction site. They broke it up into quadrants, and there were these tremendous construction cranes and all this construction equipment moving debris. If you didn’t know what had taken place there, you would think they demolished a building and were cleaning it up. But then you start to look, and there were these groups of fire and police people, and they were digging and searching for bodies. We saw some body recoveries. If they found a firefighter, they would put the remains in a body bag, give it an honor guard, and place it in an ambulance.
We did walk by what was apparently evidence. We’d see a wheel from an airplane or a piece of one of the buildings stuck into the wall of another building.
What did your days consist of?
We’d head there in the morning and spend time on site. Each team took a certain area. My team spent some time in the low-rise buildings, which were five to 10 stories high, burnt out, and partially collapsed. Engineers were looking at damage done from fire, how steel and protection on steel held up after fire, what portions of buildings collapsed and why, what portions of the building didn’t collapse and why. For example, we climbed up the stairwell of Five World Trade Center, and in the stairwell, with the doors closed, it looked like any other building. There were signs tacked on walls, sheets of paper in sheet protectors tacked on walls. Once we open the door to one of the floors, everything was burnt out. That floor had burned for more than eight hours without having any water being applied to it.
Were you examining material from Tower 1 and 2?
We went out to some of the landfills where the steel was being collected. The steel was all catalogued when it was installed in the buildings through a serial number system. Engineers had that information and knew exactly which part of the building the steel was from. They were looking for steel from where the planes impacted. It was hit or miss — you’d crawl over a pile looking for it, and you’d yell out, "I got one here from Tower 2." Someone would scurry over and take measurements.
What were you analyzing?
We wanted to see the damage done to the steel. We were looking to find steel from certain parts of the building to see how it was damaged, if it melted, how the fastening systems held up, and if the fireproofing was still intact. Those two towers were so unique the way they were constructed. The outer walls of the building were part of the structural strength of building. The structural engineers used the example of a straw. If you put pressure on top of a thick straw, it’s not going to do anything. But if you kink the straw with your thumb and index finger and put pressure on top of it, it bends. So the structural integrity of that building was a combination of the floors, outer walls, and core of the building. You damage the outer walls of the building, you take away its strength.
What happened after the investigation?
We pieced together a report. If any of NFPA’s codes were going to be cited or if they needed something from an NFPA code, I was the conduit for NFPA staff members. The report, World Trade Center Building Performance Study, was published by FEMA in 2002. [Read the report at fema.gov.]
What was an interesting find from the report?
The biggest one was that we nailed down how Building 7 collapsed. That’s the one the conspiracy theorists claim was brought down by the government. The structure caught fire in the afternoon of 9/11, and fell eight hours after the attacks. Its collapse was a combination of building construction, the damage done, and where the fires impacted that building.
Did this study have any impact on NIST’s landmark study into the World Trade Center attacks?
Our study was the preliminary groundwork for the more detailed NIST study. NFPA was a peer reviewer for NIST’s study.
Does your involvement with this investigation still affect you 10 years later?
The fact that I was at Ground Zero weeks after 9/11 is something I’ll never forget. I’m proud to say that I was there and able to contribute somehow. Ten years later, the report still stands by itself, even though many people have forgotten about it since the NIST report was so voluminous.
— Interview conducted by Fred Durso, Jr.
In this Section:
|A Decade of Difference
A look at how 9/11 shaped the development of some of NFPA’s most important codes and standards - and how that process continues.
|Are Emergency Responders Safer?
A decade after a watershed moment for firefighter safety, NFPA’s Third Needs Assessment of the U.S. Fire Service report identifies areas of ongoing concern.
|On the Scene
An NFPA investigator recalls his work at Ground Zero.