All parking and loading spaces and the passageways and driveways appurtenant thereto shall be paved with an asphaltic or concrete surface. Parking lots in residential zones that contain less than 10 spaces may, at the discretion of the Planning Board, be surfaced with a permeable material, such as crushed rock, so long as a concrete, paver, or asphalt apron is used at the point where the driveway or passageway meets the street.