Yup, that is my fear!! So, yes the prep sink is in an island. Not 100% sure but I believe the vent stack comes up the exterior wall on the main sink side.
Here are pics of the layout, if it helps
IMG_8452 by Hamberg posted Mar 5, 2020 at 8:24 AM
IMG_8451 by Hamberg posted Mar 5, 2020 at...