Hi, I am trying to figure out what these pipes mean in the rough in for our basement. The 3 inch is obviously for the water closet, and the others I'm not sure. Any help? The 2 inch pipe on the left will be in the wall and 16 inches from wall behind shelves. Is the pipe coming up in the middle the vent/lav drain? I don't hear water coming down this when any of the other bathrooms are in use.