Unwelcome guest in Grady the Groundhog- suggestions?

Question:So about 2 months ago the lady whose backyard faces mine comes over and asks me if I knew about the groundhog living under my patio deck. I didn't. She told me he chills regularly on the grass between our properties and has become such a fixture folks have named him Grady the Groundhog. Grady has made a humungous hole under my deck and has destroyed bags of mulch, my lawn mower tarp and generally made a huge mess. I had no idea because I'm never under there. Anyway I have tried it all - a humane trap our local politician lent me, this castor oil based solution my neighbor uses, even doublemint gum which my uncle swears by. Nothing seems to keep Grady away for long. I saw him for the first time the other day - he was sunning on my deck and he's a big sucker. I think none of these solutions worked because they're probably most effective in the early stages, not when the groundhog has been in residence for like months. Any serious suggestions welcome for getting Grady to move on.

Answers:
Build a dead fall trap. They are quiet and the neighbors will never know if you place it in the right spot. Just use a lot of weight. Nice thing is if it doesn't kill him and he crawls out where the "Grady lovers" see him, it will look like he got hit by a car - Follow the link on how to build one