First class sidewalks shall be constructed of artificial stone flagging in the manner hereinafter set forth: The sidewalk shall be properly graded and shaped to a depth of ten inches below the intended surface of the pavement, and whatever loose, soft, spongy or foamy soil is found in the subgrade shall be removed to such an additional depth as may be directed by the City Engineer, and shall be refilled with good material and the whole subgrade well compacted by ramming. All such excavations and refillings shall be included in the contract price for the sidewalk. All refuse material shall be removed from the line of work. After the grading is done, a foundation of cinders or mill-tailings, not less than six inches thick, shall be placed upon the subgrading, which shall be consolidated by ramming, to an even surface, and moistened just before the concrete is placed thereon. After the subfoundation has been finished, the artificial stone flagging shall be laid in good workmanlike manner, the same to consist of two parts: first, bottom course to be of 4½ inches in depth; second, a finishing or wearing course, to be one inch in depth. The bottom course shall be composed of mill-tailing or broken limestone, and the best portland cement and capable of withstanding a tensile strength of 400 pounds to a square inch of ten having been three hours in the air and seven days in water, and shall be mixed in the proportion of one part of cement to five parts of mill-tailings or broken limestone which shall consist of irregular sharp-edged, broken pieces, so broken that each piece will pass through a ¾-inch ring in all diameters, and which shall be free from dust and dirt. The mill-tailings or limestone shall be mixed dry, then sufficient clear water shall be slowly added by sprinkling while the material is constantly stirred and worked up, and the stirring and mixing shall be continued until the whole is thoroughly mixed. This mass shall be spread upon the subfoundation and shall be rammed until the interstices are thoroughly filled with cement. Particular care must be taken that the bottom course is well rammed and consolidated along the outer edges. The slab or flag divisions shall be formed by cutting the concrete entirely through on the required line as soon as laid; the space made by the cutting tool shall be immediately filled with dry sand and well rammed. After the bottom course is completed, the finishing or wearing course shall be added. This shall consist of a stiff mortar composed of equal parts of portland cement and river sand, free from loamy, earthy substance and to be laid to a depth of one-inch, and to be carefully smoothed and troweled to a perfectly smooth and even surface, which, after the first setting takes place, must not be disturbed by additional rubbing. The surface shall then be cut into flags, the marking to be directly over the joints in the concrete and cut through the wearing surface. When the pavement is completed, it must be covered for three days and kept moist by sprinkling.
(`83 Code, § 14-207) Penalty, see § 101.99