The Destruction of Building 7's Remains

Engineering is a science that melds theory and experience to create robust structures. Unintended structural failures are rare events that warrant the most careful scrutiny, since they test engineering theory.

That is why the NTSB carefully documents aircraft crash scenes, and preserves the aircraft remains, frequently creating partial reconstructions in hangers. If an investigation reveals a mechanical or design fault, the FAA usually mandates specific modifications of equipment or maintenance procedures system-wide, and future aircraft are designed to avoid the fault.

Unintended structural failures are less common in steel frame highrises than in aircraft. Being the only such building in history in which fire is blamed for total collapse, Building 7's remains warranted the most painstaking examination, documentation, and analysis.
Building 7's rubble pile was at least as important as any archeological dig. It contained all the clues to one of the largest structural failures in history. Without understanding the cause of the collapse, all skyscrapers become suspect, with profound implications for the safety of occupants and for the ethics of sending emergency personnel into burning buildings to save people and fight fires.

There was no legitimate reason not to dismantle the rubble pile carefully, documenting the position of each piece of steel and moving it to a warehouse for further study.
No one was thought buried in the pile, since, unlike the Twin Towers, Building 7 had been evacuated hours before the collapse.
The pile was so well confined to the building's footprint that the adjacent streets could have been cleared without disturbing it.

Yet, despite the paramount importance of the remains, they were hauled away and melted down as quickly as possible. The steel was sold to scrap metals vendors and most was soon on ships bound for China and India. Some of the smaller pieces and a few token large pieces of steel marked 'save' were allowed to be inspected at Fresh Kills landfill by FEMA's BPAT volunteers.

This illegal evidence destruction operation was conducted over the objections of attack victims' family members and respected public safety officials. Bill Manning, editor of the 125 year old Fire Engineering Magazine, wrote in an article condemning the operation: 1
Did they throw away the locked doors from the Triangle Shirtwaist fire? Did they throw away the gas can used at the happy land social club fire? ... That's what they're doing at the World Trade Center. The destruction and removal of evidence must stop immediately.
Dr. Frederick W. Mowrer, an associate professor in the Fire Protection Engineering Department at the University of Maryland, was quoted in the the New York Times as saying: 2
I find the speed with which potentially important evidence has been removed and recycled to be appalling.

Officials running the "cleanup operation" took pains to make sure the structural steel didn't end up anywhere but in blast furnaces. They installed GPS locater devices on each of the trucks hauling loads from Ground Zero at a cost of $1000 each. One driver who took an extended lunch break was dismissed. 3
References

1. Firefighter Mag Raps 9/11 Probe, New York Daily News, [cached]
2. The Towers, New York Times, 12/25/01
3. GPS ON THE JOB IN MASSIVE WORLD TRADE CENTER CLEAN-UP, securitysolutions.com, [cached]