You don't need a jackhammer. You can use a hammer drill, with a 1/2" socket wrench extension, plugged into an expendable 1" socket. Put the extension into the chuck of the drill, and put the socket over the end of the ground rod. Set the drill motor to "hammer only" and voila.
When the rod is almost at the correct depth, fasten the ground wire and clamp to the rod, then pound it the rest of the way, so that the clamp is below grade. This protects it from dog pee, lawn mowers and vandals.
