COLUMBIA GULF TRANSMISSION, LLC

Incident Narrative

ON THE EVENING OF WEDNESDAY FEBRUARY 16TH, 2022 A PIPELINE RELIEF VALVE, ON COLUMBIA GULF TRANSMISSION'S EAST LATERAL 200 (EL200) LINE, AT VALVE SETTING VS-1204, FAILED TO THE OPEN POSITION RELEASING (AT THE TIME) AN UNKNOWN VOLUME OF NATURAL GAS. THE VALVE SETTING IS LOCATED NEAR 2037 DURPHY ROAD, IN ABBEVILLE LOUISIANA. THE ODOR OF GAS WAS REPORTED BY A PRIVATE CITIZEN; LOCAL EMERGENCY SERVICES WERE DISPATCHED AND CLOSED THE NEARBY ROAD. THE CAUSE OF THE RELIEF VALVE MALFUNCTION IS UNDER INVESTIGATION; HOWEVER, THE MAOP WAS NOT EXCEEDED AS INDICATED BY SCADA TRANSMITTER DATA. THE PRESSURE AT THE TIME OF THE EVENT WAS CHECKED ON SCADA. A LOSS OF COMMUNICATIONS WITH SCADA TRANSMITTER WAS NOTED BY THE GAS CONTROLLER, THEN UPON RESTORING COMMUNICATIONS, A DROP IN PIPELINE PRESSURE WAS OBSERVED. AT 4:19 PM CENTRAL TIME, WHEN TRANSMITTER COMMS WAS LOST, THE PRESSURE ON EL200 WAS 825 PSIG; THE PRESSURE WHEN COMMS RESUMED AT 4:54 PM CENTRAL WAS 816 PSIG. EL200 FROM RAYNE COMPRESSOR STATION TO VS-1204 HAS AN MAOP OF 973 PSIG. HOWEVER, EL200 IS CURRENTLY IN COMMON WITH EAST LATERAL 300 LINE, RESULTING IN AN OVERRIDE MAOP OF 839 PSIG FOR THE LIMITING COMPONENT IN THIS MODE OF OPERATION. EL200 RELIEF VALVE WAS FOUND VENTING INTO ATMOSPHERE AND WAS MANUALLY SECURED. THE CALCULATED AMOUNT OF RELEASED MATERIAL INTO ATMOSPHERE WAS 16,935 MCF, HENCE MEETING THE REPORTING THRESHOLD. MONITORING CENTER'S PERSONNEL CALLED LOUISIANA STATE POLICE TO REPORT THE RELEASE OF MATERIAL INTO ATMOSPHERE. THE EAST LATERAL, ESPECIALLY AT MLV 1204, IS PROVIDING PRESSURE CONTROL USING RELIEF VALVES. THIS CONFIGURATION DOES NOT ALLOW A CONTROLLED PRESSURE REDUCTION, BUT INSTEAD AN IMMEDIATE PRESSURE REDUCTION BY A GAS RELEASE. THIS CONFIGURATION ALSO DOES NOT ALLOW FOR A SET POINT ABOVE THE LOWEST MAOP OF THE LINE WHERE IT IS INSTALLED OR ADJACENT 'COMMON' LINE.