Yeah, formatting a drive is a HUGE admin right. Probably one of the most serious. So from a philosophical standpoint, it's one of the last things you want to be able to grant a domain user.
Depeding on the person, generally people that need that kind of power are given local admin rights but standard domain user rights.
If it's just for fomratting drives you might think about using a laptop that is off your internal netowrk and give local admin rights to that, then restoring the HD image after he's done if you are really tight on security.