I don’t know specifically for design/tech, but for Acting & MT if you are waitlisted, it’s specific to the department and not the school as a whole. If that is the case for you, it’s always a good idea to contact the head of the department, not just an admissions person, and let them know they are your top choice and if you come off the waitlist you will accept an offer.
You might want to post on this thread that is specific to tech:
http://talk.collegeconfidential.com/theater-drama-majors/2005400-are-there-any-theatre-tech-people-here.html#latest
Hoping you come off of one of your waitlists!