A public utility receiving notice pursuant to § 16-349 shall inform the person, public agency or public utility proposing to excavate, discharge explosives or demolish of the approximate location of its underground facilities in the area in such manner as will enable such person, public agency or public utility to establish the actual location of the underground facilities, and shall provide such other assistance in establishing the actual location of the underground facilities as the authority may require by regulations adopted pursuant to § 16-357. Such person, public agency or public utility shall designate the area of the proposed excavation, demolition or discharge of explosives as the authority may prescribe by regulations adopted pursuant to § 16-357. The public utility receiving notice shall mark the approximate location of its underground facilities in such manner and using such methods, including color coding, as the authority may prescribe by regulations adopted pursuant to § 16-357. If the actual location of the underground facilities cannot be established, the person, public agency or public utility shall so notify the public utility whose facilities may be affected, which shall provide such further assistance as may be needed to determine the actual location of the underground facilities in advance of the proposed excavation, discharge of explosives or demolition.