I am remodeling a bathroom. When the old drywall was removed I discovered 2 holes in the 3" copper vent stack behind the toilet. The small hole is approx. 1/8" diameter and the other approx. 1/2" diameter. The surface around the holes also seems to be deteriorating. My question: Should I replace a section of the tubing or is there a suitable patching method that can fix this problem? Or, are there other options to consider?