COLUMBIA GAS TRANSMISSION, LLC

Incident Narrative

ON APRIL 17, 2023, LINE D-100 WAS SUBJECT TO AN UNINTENTIONAL RELEASE OF NATURAL GAS (MATERIAL) INTO ATMOSPHERE RESULTING IN MATERIAL LOSS EXCEEDING 3,000 MCF. LINE D- 100, A TRANSMISSION PIPELINE THAT IS THAT IS OPERATED AND MAINTAINED BY COLUMBIA GAS TRANSMISSION, LLC (COMPANY), A TC ENERGY ENTITY, LOCATED IN CRAWFORD COUNTY, OHIO. AT 17:40 EDT, A COMPANY PERSONNEL RECEIVED A NOTIFICATION FROM THE LANDOWNER REGARDING POTENTIAL RELEASE OF MATERIAL AND ARRIVED ON-SITE AT 18:15 EDT. AFTER FURTHER INVESTIGATION, THE REPORTED RELEASE WAS FOUND TO BE FROM A DAMAGED 20-IN PIPELINE BY A THIRD PARTY (LANDOWNER) WHILE TILING HIS LAND. THE PRELIMINARY MATERIAL LOSS CALCULATIONS WERE DETERMINED TO BE GREATER THAN 3,000 MCF, HENCE, THE EVENT WAS REPORTED TO THE NATIONAL RESPONSE CENTER (NRC). ALL EFFORTS WERE MADE BY COMPANY AND THE LOCAL DISTRIBUTION COMPANY PERSONNEL TO MAINTAIN MATERIAL FLOW TO THE LINE IN A SHORT TIMEFRAME. AT 22:10 EDT, LINE D-100 WAS ISOLATED, AND PURGING WAS COMPLETED AT 22:09 EDT. AFTER PERFORMING THE NECESSARY ENGINEERING ASSESSMENT TO THE DAMAGED LINE, A PRE-TESTED PIPE WAS INSTALLED AND THE SERVICE TO LINE D-100 WAS RE-ESTABLISHED ON APRIL 21, 2023, AT 17:35 EDT. THE INITIAL NRC REPORT NO. 1365025 AND THE NRC 48-HOUR REPORT NO.1365104 HAVE BEEN CALLED-IN ON APRIL 17 AND APRIL 18, 2023, RESPECTIVELY.