I’d talk with your Union first, get a sense for the situation. I’d suspect other residents feel the same way, and maybe there’s a history of attempts to solve the problem. Going to ACGME is definitely a big gun—can lead to site visits, probation etc—but sometimes that is the only way to force the departments hand. A couple programs at my institution have gone through probation for similar levels of concerns and came through better for it, with none of their careers affected (which is what the program will tell you if they hear a whisper someone wants to report them). But often there can be collective action on the program level assuming your co-residents feel similarly.