I worked there for several years. When they use the term "part time" they are simply saying that your a non-union worker. Trust me you will get 40+ hours by working there. However your OT pay will only start after 40hrs (as in any other job). Dont ask me why they call it "part time" when your really not its just the term they have used since starting the union there.
However, once you go "fulltime" and become part of the union and on the seniority list, your pay goes up to 15.xx I think and your benefits are a hell of alot better. Mostly due to union contract stipulations and such. I will warn you, back in the day guys worked there for 2+ years before going 'fulltime', sometimes longer. I dont know what its like for part timer's there now though. I do know they're behind on work and need people like crazy.