"I keep a notebook in the truck and have documented all his errors over the last few months.."

 Isn't that kinda like closing the barn door after the horse is out?  So, you've been documenting what he's been doing wrong.  WHY aren't you sitting down with him weekly to review his job performance - at least during a probationary period.  If he is not measuring up, you should be communicating that to him all along.

Maybe you've been doing that, but I don't see it mentioned in your posts here.