Common property in the planned unit development (PUD). Common property in a PUD is a parcel or parcels of land, together with the improvements thereon, the use and enjoyment of which is shared by the owners and occupants of the individual building sites. When common property exists, the ownership of such common property may be either public or private. When common property exists in private ownership, satisfactory arrangements must be made for the improvement, operation and maintenance of such common property and facilities, including private streets, drives, service and parking areas and recreational and open space areas.