The excavation for curb shall be made to a depth of 12 inches below the intended surface.  Whenever loose, soft, spongy or loamy soil is found in the excavation, it shall be removed to such additional depth as may be directed by the City Engineer or his assistant, and shall be refilled with good material, and the whole subgrade well compacted by ramming.  All such excavations and refillings shall be included for the contract price for the curb.  After the grading and shaping is done, a foundation of mill-tailings or broken limestone six inches thick shall be placed on the subgrade, which shall be consolidated, by ramming, to an even surface, and shall be moistened just before the concrete is placed thereon.  The curb shall be six inches wide at the top and eight inches wide at the bottom, and shall be 24 inches deep; it shall be composed of a concrete core or backing, faced with one inch in thickness of facing or finishing mortar, as shown by drawing on file in the office of the City Engineer.  The core or backing shall be constructed of one part portland cement and three parts of mill-tailings or broken limestone, which shall be first well mixed dry and then sufficient water added and the mixing continued until a uniform composition, and the proper consistency, is produced. The concrete shall then be put in place and well compacted by ramming with a 20-pound rammer, until the moulds are full and curb is ready for surfacing.  The entire exposed surface of the curb shall be faced with mortar one inch in thickness, composed of equal parts of portland cement and clean river sand floated and troweled so as to give it a uniform surface, and the color throughout the work shall be carried uniformly and the whole curb com-pleted while in a soft and plastic state.  Sections in the curb shall not be less than six feet nor more than seven feet long.  The curb shall be constructed as shown on drawing in file in the office of the City Engineer.  The face corner of the curb shall be rounded to a radius of two inches.  At the street corner the curb shall be constructed on a curve of four feet radius, and at the intersections of the alley to a curve of two feet radius.
(`83 Code, § 14-210)  Penalty, see § 101.99