Building in the Aftermath From Ground Zero
Monday, January 28, 2002 - 6:30 - 8:00 pm
The National Building Museum
401 F Street. NW Washington, DC 20001
Text (except quotations, which are in Italics) Copyright © 2002 Azar Attura
"The collapse of the World Trade Center and the need to safely and expeditiously clear the site has challenged engineers and contractors as never before. Key figures working at Ground Zero will consider the problems they have encountered. Panelists include Daniel A. Cuoco, P.E., president and managing principal of LZA Technology, a division of the Thornton-Tomasetti Group; George J. Tamaro, P.E., partner, Mueser Rutledge Consulting Engineers; and Ralph Johnson, senior vice president, Turner Construction Company. Charles H. Thornton, P.E., chairman and managing principal of Thornton-Tomasetti Group, will moderate the discussion. The exhibition Twin Towers Remembered will be open for viewing. This event is cosponsored by the Associated General Contractors of America and the American Council of Engineering Companies."
I believe that for a great deal of people, rather than being a sensationalistic voyage of the curious, visiting Ground Zero comes from a need to connect with the tragedy and those who lost their lives at the World Trade Center. As a New Yorker who has visited New York three times from September to December 2001, but who has yet to visit ground Zero, this was to be a rite of passage for me -- a way to see the damage through the eyes of those who have dealt with it every day since September 11. As one of the panelists said - "It is hard to comprehend the magnitude of the damage until you have seen it up close." How right he was.
The presentation was on a much larger scale and scope than had I expected. It was educational, saddening, mind-boggling, sobering, and punctuated here and there with much-needed comic relief, from these professionals who, with their crews of skilled workers (working 24/7 without the benefit of any insurance) are trying to clear the site amidst all kinds of serious hazards, while keeping the safety of their employees and the sanctity of the site in mind.
These panelists enhanced their lectures with slides which conveyed the sheer magnitude of the damage as well as the Herculean effort involved and demanded in clearing the site. Let me give you some examples:
The complete site (and several blocks beyond) where the WTC stood had been reclaimed, over the centuries, from the Hudson River -- this was NOT the famed "Bedrock" upon which much of New York City had been built. There were many challenges to contend with, above and beyond the "ordinary" job of clearing the wreckage and debris, such as:
1) The "Slurry Wall" which keeps the Hudson from flooding the WTC site and lower Manhattan. Huge beams had to be driven into these walls at a 45 degree angle (some of the walls were in surprisingly good condition -- others were in grave danger of falling), in order to keep the walls from collapsing.
2) The PATH Commuter Train Tube, which was flooded with Hudson water and sewage. The flooding situation was so serious it threatened to eventually put parts of Newark under water. The tubes had to be undercut, shored up, capped, and drained.
3) The ground itself, at Ground Zero. Much of the massive courtyard between the 5 (or was it 6?) collapsed buildings was originally constructed by being shored up with beams - i.e., it was hollow underneath. In order to facilitate removal of the buildings' debris (one of which was a façade which fell from the 80th floor, and embedded itself 40 feet deep into the ground), huge cranes (200, 800 and 1000 Ton cranes with jaws from 3 feet wide to 5 feet wide) had to be placed at or very close to these sites. It was determined that cranes below a specific tonnage could be placed 30 feet away from this unstable ground, and larger cranes had to be placed at least 60 feet away. In order to place these cranes at these locations, huge steel I-beams had to be procured. This was not an easy task, but as one engineer wryly noted - "We suddenly realized - What are we taking off these buildings?? Huge I-Beams! So we placed these on the ground and were able to accommodate the cranes. Even so, huge cracks started to appear in the ground, which necessitated moving some of these cranes. We also noted that the Verizon guys had been there earlier and placed some communications spikes in the ground, some of which were right in the cracks, so we jokingly told them that they had cracked the ground!" This same engineer had the presence of mind, on September 11, to remember that not only had his company been part of the construction (1968-1973) of the WTC, but he also had the original photos, blueprints and drawings which he knew would be vital for the process of clearing and restoring the site. In the midst of all the terror and uncertainty of that day, he kept his wits about him and gathered a small library of highly useful information which is now being used to help determine approximate locations of rooms, corridors columns, and stairways, as well as specific areas of construction in that huge mass of twisted rubble.
4) The unexplainable: The huge glass Palm Court (a semicircular greenhouse with a very high ceiling) was about 60% destroyed. It could not be demolished however, because of a huge pile of debris (I think it was the Marriott hotel) which had fallen next to it and was, in defiance of all the laws of engineering, literally keeping the Palm Court standing. The Palm Court would have to be meticulously shored up before the debris could be removed. As one panelist noted "The fire Department was the boss there -- because they had lost so many, and since they were the ones who were in charge of retrieving their lost ones -- when they said 'This debris (holding up the Palm Court) has got to go in TWO days -- we had to go out there and shore up the Palm Court in two days, with steel beams -- and we did!"
5) The unpredictable. In order to assess the damage and to determine what to shore up and where, "the skinniest workers had to crawl through the wreckage with a flashlight, a camera and their own 'certified personal rescue personnel', to take photos of the damage. Since the wreckage was constantly shifting, this was highly dangerous, which was one reason why we couldn't get any Insurance Company to insure our workers." Showing us a photo of a column in a garage surrounded by a collapsed ceiling (next to an undamaged car!), he continued "We'd be here one day, and the next day when we came back, this ceiling would be a pile of dust right where the worker had stood the previous day!"
6) The Subway under the WTC -- a photo of an abandoned subway train -- undamaged -- and 20 feet further down the station, a sickening jumble of collapsed ceilings, protruding columns, and twisted pipes in a huge mass where the tunnel should have been. Surprisingly, this particular station is scheduled to re-open before the end of the year.
7) The "Before" and "After" photos -- a civilized city section of glass and steel, cars, street signs, reduced to piles of unrecognizable rubble and destruction.
8) The total acreage of the damage - a horrendous vast panorama of grey ash and building rubble, dwarfing the workers and machinery there to clear everything out. The eye could not take all of it in at once.
I believe that this 2 1/2 hour presentation gave a bit of closure to those of us who wanted to, but were unable to visit the WTC site. It also gave all of us there at the Building Museum, I am sure, a greater respect for the talents as well as the sheer tenacity and fearlessness of the human spirit and its ability to persist and win against great odds.
In conjunction with this presentation at the Building Museum, there is an exhibit of photographs, (a labor of love) of the WTC from 1968 to September 13, 2001, all taken by the same photographer, Camillo Jose Vergara. I highly recommend it. There is also a companion book by the same photographer.
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"Building in the Aftermath
From Ground Zero
Monday, January 28
6:30 - 8:00 pm
The collapse of the World Trade Center has challenged engineers and contractors as never before. Key figures working at Ground Zero will consider the problems they have encountered. Panelists include Daniel A. Cuoco, P.E., president and managing principal of LZA Technology, a division of the Thornton-Tomasetti Group; George J. Tamaro, P.E., partner, Mueser Rutledge Consulting Engineers; and Ralph Johnson, senior vice president, Turner Construction Company. Charles H. Thornton, P.E., chairman and managing principal of Thornton-Tomasetti Group, will moderate the discussion. The exhibition Twin Towers Remembered will be open for viewing. This event is cosponsored by the Associated General Contractors of America and the American Council of Engineering Companies. $12 Museum members; $16 nonmembers; $9 students. Registration required."
