As the excavation work progresses all streets and private properties shall be thoroughly cleaned of all rubbish, excess earth, rock and other debris resulting from such work. All clean up operations at the location of such excavation shall be accomplished at the expense of the permittee and shall be completed to the satisfaction of the City Engineer. From time to time as may be ordered by the City Engineer and in any event immediately after completion of said work, the permittee shall at his or its own expense clean up and remove all refuse and unused materials of any kind resulting from said work and upon failure to do so within 24 hours after having been notified to do so by the City Engineer, said work may be done by the City Engineer and the cost thereof charged to the permittee, and the permittee shall also be liable for the cost thereof under the surety bond provided hereunder.
('69 Code, § 18-51) Penalty, see § 10.99