I hate to say it but yes it can send runners deep underground and they can come up quite far from the original plant. Once established I think the Campsis radicans is next to impossible to eradicate. After a nuclear explosion there will still be cockroaches and trumpet vines! You can try cutting back any runners that pop up and treating the cut stem ends with a herbicide. I really don't think that boiling water will have much of an effect. I finally gave up on trying to get rid of the damn vine and now just work on containing it to the far back yard. Good luck.