Salt Salt Salt. If you could get a good amount of salt on it and some sunshine, you could clear that. Any blade no matter which edge is on it, is going to have a hard time with that. Just be sure to let your customer know that they are going to have some extra expenses. Or even if you eat some of the price for the salt, and get it clear, they might be happy and keep your services. But if its not worth the effort, turn the other way. I ran into a driveway like this once. When I bid it, I just figured on using salt to get down to the surface, then they call and say, "We don't want salt on our drive, just so you know" I explained that it would take a warm day and some sunshine and they understood. I still have that account. And now I don't give them a chance to drive on it before it piles up.