World Trade Center Building 7, which collapsed late in the afternoon of 9/11, had contained two independently supplied and operated fuel systems for emergency power. The fuel had been in several storage tanks low down in the building. In March and April, two 11,700-gallon tanks that had been located under the building’s first floor loading dock and operated by Silverstein Properties are removed from the collapse site. They show no evidence of fuel leakage. FEMA says that approximately 20,000 gallons of fuel are subsequently recovered from them, which is about 85 percent of their total capacity. In early May, two 6,000-gallon tanks that had been owned by Salomon Smith Barney and were also located below the loading dock are recovered. These were always kept full for emergencies and would have been full on 9/11. Yet now they are damaged and appear to be empty. According to the National Institute of Standards and Technology (NIST), “Some fuel contamination was found in the gravel below the tanks and sand below the slab on which the tanks were mounted, but no contamination was found in the organic marine silt/clay layer underneath.” Shyam Sunder, lead investigator of NIST’s WTC investigation, will state that this “suggests that this fuel… could have been consumed in the building.” This finding “allows for the possibility, though not conclusively, that the fuel may have contributed to a fire on Floor 5” of WTC 7. [Federal Emergency Management Agency, 5/1/2002, pp. 5-15; Associated Press, 6/6/2002; Newsday, 6/6/2002; National Institute of Standards and Technology, 4/5/2005 ; New York City Council, 9/8/2006
] Some people have speculated that the diesel fuel stored in WTC 7 may have played a role in its collapse (see March 2, 2002). However, FEMA says, “Although the total diesel fuel on the premises contained massive potential energy, the best hypothesis has only a low probability of occurrence.” WTC 7 housed another 6,000-gallon tank between its second and third floors, which was meant to fuel generators that would supply backup power to the mayor’s 23rd-floor emergency command center (see June 8, 1999). Currently, no data are available on the condition of this tank. [Federal Emergency Management Agency, 5/1/2002, pp. 5-16 and 5-31]