Concrete sidewalks shall be constructed in connection with street improvements in a subdivision. Sidewalks shall be four inches thick, except that a six-inch thickness shall be required for the sidewalk area extending the width of any driveway. Sidewalks shall be graded to the satisfaction of the Village Engineer and shall be five feet in width. However, Council may, by a two-thirds vote, waive any of the foregoing requirements of this section when it determines that such requirements are undesirable due to the layout, terrain or lot sizes.