Grading shall include all excavation, embankment and fill necessary to produce the surface on which the lowest layer of improvement or structure is placed. Such grading shall be constructed to the lines and grades approved by the city engineer or other designated city official for all surface improvements in the subdivision including streets, alleys, sidewalks, curbs and gutters, building pads, and surface drainage facilities. All building pads shall be graded to provide eighteen inches minimum from finished floor of building to finished gutter flow line. (Ord. 617 §2 (Exh. A), 2011; Ord. 474, 2002).