I already know what secret lies in the foundation of that site... a humongous septic tank.
I know this because they accidentally busted it open while digging up the foundation. The whole block smelled like rancid ass for over a month as a result.
When I say "every balloon", I mean "every balloon that is sized 16 inches and up". Small balloons don't count.
And the only people who buy 16+ inchers are either professional party decorators or looners.