Was this well-respected posek paskening l’halacha that it belonged to him? Isn’t he a Nogeia Badavar?
He might have made a Chazaka, but as every not-so-well known posek knows, Kol Chazaka Sheain Imo Teineh, Aino Chazaka. He would first have to had purchased the parking spot from the city or township, and then made his improvement.
He could however claim ownership to all of the hefker snow that he moved, with a kinyan hagbaha. Of course, he might not want to admit that, because he might be a mazik if he piled it up in front of someone else’s parking spot or driveway.