No person, firm, corporation or municipality making openings in the pavement shall be permitted to tunnel under any portion of the same. Should the sides or walls of an excavation cave in at any time during the progress of the work, leaving the foundation of the pavement surrounding the cut insufficient to fully support such pavement, all of the pavement so undermined by such cave in shall be broken down and the opening in the surface of the pavement increased until the extreme edge of the insufficient foundation is reached. Such additional repairs to the pavement thus caused shall be immediately covered by an additional permit and deposit made in the regular manner; provided that the permit fee charged in such case, and the additional deposit thus caused, shall be based on the scale of a continuous cut. (Ord. 861 §1, 1998)