What's been goin' on at my house lately? I'm glad you asked... This here picture below is what I've been dealing with lately.
They had to drill a new hole under my sink because the original pipe went down from the sink backward into the wall and then made a 90 turn right to meet up with where you can see the old pipe in the picture above. So now we have a pipe that runs straight down from the sink as you also can see above. We had to hook into the old pipe because we couldn't find the air vent, so we just ass-u-me-d it ran up from the old pipe.
Also as a bonus you get to see how very creapy gross my basement is (we call this area our "Dead Body Room"). This room is the old coal storage room. Can I just ask how smart it really was to put the sink plumbing right next to the coal shoot?