The fact is, the WTC disentegrated in midair and left next to no debris.
That sort of begs the question of why there was such an extensive cleanup.
• 24 local, state, and federal agencies participated, with as many as 1,000 workers a day
• 17,000 tons of material were processed daily...
... At the close of the Staten Island Landfill mission:
• 1,462,000 tons of debris had been received and processed
• 35,000 tons of steel had been removed (165,000 tons were removed directly at Ground Zero)
• 806,000 tons of debris had been screened, an average of 75 tons per hour
(Source: Multiple sites.
This link and
this one are the two specific sites holding the above information. The central link I got this all from is
Gravy's site's page on the cleanup)
That's just one of the two dump sites. Most of the steel was accounted for (35,000 tons arrived at the Fresh Kills site, and 165,000 were taken directly from Ground Zero; the estimates I see of the amount of steel used in the towers lay around 200,000 tons; some of that info comes from
here). The towers by themselves, minus contents, were roughly 500,000 tons apiece, from that link I've posted, so figure a rough million tons total from just the two main structures, minus contents. If you want to add WTC 7, please chime in; I don't have those figures at hand. Given their height was roughly half that of the towers, I might guess that we can conservatively say they were half the mass, but that figure's so fuzzy and has so much potential for error, I don't really want to use it save for the fact I need
some figure. It might be significantly more, given that it's a differently designed building; I just don't know. But just for argument's sake, let's say 250,000 tons.
I won't even attempt to give a figure for how much contents were there.
Anyway, given that one of the two dump/recycling sites alone dealt with 1,462,000 tons of debris, I'd say that most of it was there myself; that's already more than the mass of the main towers plus our very rough guestimate of the mass of WTC 7. Now granted, I have to admit that there's some leeway in the phrase "next to no...", but to be honest, I think that leeway's being much abused in the above statement.