While performing the necessary work on private property referred to in Section 95.10 hereof, the authorized City representative or duly authorized employees of the City, the State Department of Natural Resources and the U.S. Environmental Protection Agency shall observe all safety rules applicable to the premises established by the owner or occupant which are not in conflict with their regulatory duties and the owner or occupant shall be held harmless for injury or death to City employees or other persons noted above and the City, State Department of Natural Resources and the U.S. Environmental Protection Agency shall indemnify the owner or occupant against loss or damage to its property by City employees or other persons noted above and against liability claims and demands for personal injury or property damage asserted against the owner or occupant and growing out of any gauging and sampling operation, except as such may be caused by negligence or failure of the owner or occupant to maintain safe conditions.