[Towertalk] Pouring base of tower

[Wes Cosand]

I am planning the installation of a self-supporting tower.  My contractor 
asked me a question to which I don't know the answer.  Is there any reason 
why he cannot pour the base in two pours as long as they are tied together 
by the rebar cage?  The plans call for the foundation to be 9 x 9 at the 
base and then 5 x 5 at the surface.  He would prefer to pour the 18" thick 
9 x 9 foot section before the 5 x 5 foot section.  Any reason why not?

Thanks

Wes, WZ7I