When the purposes for which such excavations or alterations have been accomplished by the person obtaining the permit therefor, all such excavations made or trenches or ditches dug or other alterations made shall be filled up, firmly tamped and the surface of any street, avenue or alley affected placed in a durable, smooth and serviceable condition and in as good a condition as it was before such work was done, under the supervision of the city. (1988 Code § 14-203)