It shall be the duty of any person owning, maintaining or operating any gas pipes or gas mains beneath the surface of any public street to prevent leaks in such pipes or mains and to repair the same immediately. In the event that any person refuses or neglects to repair such leaks, it shall be lawful for the city to make or cause to be made the necessary repairs thereto, and the cost and expense of making the repairs shall be paid to the city by the person owning, maintaining or operating the gas pipes or gas mains. (Ord. No. 339, § 6.)