Where is a blood alcohol level usually done? at a hospital?

Where labs are: A blood alcohol level is just a lab test done on blood that is drawn, so wherever phlebotomy (professional blood drawing) is done the labwork can be arranged. This would include a doctor's office or clinic, lab, er, instant care, hospital, etc. Blood alcohol is usually checked in cases of car accidents, industrial accidents and where there is a question of impairment.

Any lab: So yes, hospitals do blood alcohol levels, but a walk in clinic can do them as well.