It is unlawful to make any such excavation or tunnel in any way contrary to or at variance with the terms of the permit therefor. Proper bracing shall be maintained to prevent the collapse of adjoining ground; and in excavations, the excavation shall not have anywhere below the surface any portion which extends beyond the opening at the surface.

    No injury shall be done to any pipes, cables or conduits in the making of such excavations or tunnel; and notice shall be given to the persons maintaining any such pipes, cables or conduits or to the city department or officer charged with the care thereof, which are or may be endangered or affected by the making of any such excavation or tunnel before such pipes, cables or conduits shall be disturbed.

    No unnecessary damage or injury shall be done to any tree or shrub or the roots thereof. (Prior code § 33-3-8)