Whenever it is necessary to break through existing pavement for the purpose of constructing service facilities, and where trenches are to be four feet or over in depth, the pavement and the base shall be removed to at least six inches beyond the outer limits of the subgrade that is to be disturbed in order to prevent settlement, and a six-inch shoulder of undisturbed material shall be provided on each side of the excavated trench. The face of the remaining pavement shall be approximately vertical. A power-driven concrete saw shall be used to cut a kerf sufficient to permit complete breakage of pavement or base without ragged edges. Asphalt paving shall be scored or otherwise cut. No pile driver may be used in breaking up the pavement. [Ord. 1021 § 19.10, 1961; Code 1970 § 12.24.310; Code 1954 § 4-5.124.]