|(a) Upon being contacted by the notification system, an operator shall provide a positive response within the time frames specified in Texas Utilities Code, Chapter 251, by either: (1) marking the operator's underground pipelines in accordance with the requirements of Texas Utilities Code, Chapter 251, and this chapter; or (2) notifying the excavator that the operator has no underground pipelines in the vicinity of the proposed excavation area. The operator shall provide this "all clear" or "no conflict" notice using the method or methods that the excavator specified in accordance with §18.3 of this title, relating to Excavator Notice to Notification Center. (b) Both the excavator and the operator shall make a record of the positive response regarding each line locate ticket received. (c) An excavator that gives a second notice to the notification center pursuant to §18.4(e) of this title, relating to Excavator Obligation to Avoid Damage to Underground Pipelines, because an operator failed to provide a positive response to an excavator shall report that fact to the Commission through TDRF as set forth in §18.11 of this title, relating to Reporting Requirements. An excavator shall also report an operator's failure to provide a positive response to a second call to the Commission through TDRF as specified in §18.11. (d) An operator that receives a notice of damage to its underground pipeline through a notification center pursuant to §18.11(b) of this title, relating to reporting requirements, shall respond within four hours.