The function of the ground is not to clear faults, it is to create a local ground reference so the case of your drill is at the same potential as the concrete slab you are sitting on. In that regard, the ufer is your best bet. Earth ends up being a significant return path for neutral current tho, in spite of the theory and 250.6. Wye distribution pretty much assures it. Even with delta distribution, you will still be sharing the earth with the neutral. You want a local ground reference.
