August 21, 2008: NIST Rules out Diesel Tanks in Collapse of WTC 7

The National Institute of Standards and Technology (NIST) publicly rejects the theory that diesel fuel tanks installed in World Trade Center Building 7 played any role in the 47-story tower’s collapse, late in the afternoon of 9/11. This is clearly set out in a question-and-answer factsheet published on this day, together with an announcement of NIST’s draft report on the building’s collapse (see August 21, 2008 and August 21, 2008). The factsheet asks, “Did fuel oil systems in WTC 7 contribute to its collapse?” The answer is “No…. The worst-case scenarios associated with fires… could not have been sustained long enough, could not have generated sufficient heat to weaken critical interior columns, and/or would have produced large amounts of visible smoke from the lower floors, which were not observed.” [National Institute of Standards and Technology, 8/21/2008; New York Times, 8/21/2008] These findings are echoed in the draft version of its final report on the collapse. [National Institute of Standards and Technology, 8/2008, pp. xxxii ] WTC 7 had three emergency power systems, all of which ran on diesel fuel. The systems contained two 12,000 gallon fuel tanks and two 6,000 gallon tanks located beneath the building’s loading docks, and another 6,000 gallon tank on its first floor. There were also 275 gallon tanks on the fifth, seventh, and eighth floors, and a 50 gallon tank on the ninth floor. [National Institute of Standards and Technology, 8/21/2008] It has previously been suggested that diesel stored in these tanks might have contributed to fires that led to WTC 7’s collapse (see March 2, 2002). [New York Times, 3/2/2002] This possibility was proposed in the final report of the Federal Emergency Management Agency (FEMA) investigation of the WTC collapses, published in May 2002 (see May 1, 2002). [Federal Emergency Management Agency, 5/1/2002, pp. 5-28 – 5-29] But in his summary of the findings of NIST’s three-year study of WTC 7, lead investigator Shyam Sunder says the building’s collapse was “not due to fires from the substantial amount of diesel fuel stored in the building.” [National Institute of Standards and Technology, 8/21/2008]