All sidewalks must be laid on even grades, and made to join snugly with one another and with the street crossings, and shall be upon the established grades. No new sidewalks shall be constructed except under the grade to be given by the Director of Public Service and Safety or his agent. All sidewalks must be accepted by the Director of Public Service and Safety, and be put down under his supervision. Whenever any sidewalk is repaired, it shall be done to conform with the then existing grade and sidewalk. (1979 Code 93.30)