I don't think that the walls can be high enough. Gravity is the same at "ground level", but the mass of the air (because of the short walls) is missing to get the right groung level pressure.
Or maybe not, and the scale of the station in the film is enough to build 30 km high walls? I admit I only saw the trailers, and the station didn't seem that huge.
EDITED: tons of typos and stuff