COLUMBIA GULF TRANSMISSION, LLC

Incident Narrative

ON DECEMBER 9TH, 2017, ALEXANDRIA COMPRESSOR STATION (CS) WAS SUBJECT TO AN UNINTENTIONAL RELEASE OF NATURAL GAS (MATERIAL) RESULTING IN MATERIAL LOSS EXCEEDING 3,000 MCF. ALEXANDRIA IS A TRANSMISSION CS THAT IS MAINTAINED BY COLUMBIA GULF TRANSMISSION, LLC (TRANSCANADA) AND IS LOCATED IN RAPIDES PARISH, NEAR THE TOWN OF HOLLOWAY, LOUISIANA. AT APPROXIMATELY 20:44 CST TRANSCANADA'S GAS CONTROL PERSONNEL NOTED VIA A SCADA ALARM OF A POTENTIAL PRESSURE DROP ON THE TURBINE PIPING ASSOCIATED WITH THE SUCTION SIDE OF LINE 200 AND 300 OF ALEXANDRIA'S CS. OPERATIONS PERSONNEL WERE IMMEDIATELY DISPATCHED TO INVESTIGATE THE EVENT. AT 21:03 CST, OPERATIONS PERSONNEL ARRIVED ON SITE WHERE THE UNINTENDED RELEASE OF MATERIAL WAS IDENTIFIED AND ISOLATED AT APPROXIMATELY 21:05 CST. ONCE OPERATIONS PERSONNEL ISOLATED THE LEAK AND MADE THE AREA SAFE, GAS CONTROL WAS NOTIFIED TO FOLLOW-UP ON THE NECESSARY FOLLOW-UP ACTIONS AND REQUIRED INVESTIGATIONS. THE PRELIMINARY MATERIAL LOSS CALCULATIONS WERE DETERMINED TO BE GREATER THAN 3,000 MCF, HENCE, THE EVENT WAS REPORTED TO THE NATIONAL RESPONSE CENTER AS AN INCIDENT. FURTHER INVESTIGATION DETERMINED THE PROBABLE CAUSE OF THE EVENT THAT LED TO A REPORTABLE INCIDENT INCLUDED CORRODED WIRES ON A VERSA VALVE SOLENOID CONNECTION IN CONJUNCTION WITH THE ASSOCIATED PLC LOGIC, IN WHICH WERE REMEDIATED BEFORE THE VALVE WAS RETURNED TO OPERATION. A 48-HR. UPDATE NOTICE WAS CALLED-IN TO THE NRC WHERE THE UPDATE REPORT NO. WAS 1199309.