907.04 DRIVING OF PIPES IN LIEU OF EXCAVATION; TUNNELING.

   The Director of Public Works may require the driving of pipes in cases where and to the extent that soil conditions and other circumstances render such driving practicable, in lieu of excavation. Tunneling shall not be permitted in any case unless the Director of Public Works deems it more suitable than driven pipe or open cut, and unless the applicant gives security satisfactory to the Director of Law to save the City harmless from any future settling or injury of the surface or of the pavement. (1931 Code §27.3122)