Yes, there is (was) storm drainage within the structure. Not 100% sure I'm remembering right, but I think there was capped connections in the mechanical room for a future ice rink.
the diesel gen plus its plenums take up a lot of that space. the mechanical floor has a couple air handling units, 4 boilers (which if i remember right, either all four or two of them serve the hotel portion), plus a bunch of pumps and tanks.
going by some old drawings i have the very top (smaller room) is the diesel gen room, below that is a full mechanical floor. is that the floor you were talking about?
it is for the Sisters of St. Joseph of Toronto, 2 O'Connor Drive project. 4 storeys, construction to be complete by november 2012, Shim-Sutcliffe Architechs