COLUMBIA GULF TRANSMISSION, LLC

Incident Narrative

COLUMBIA GULF TRANSMISSION, LLC OPERATES AND MAINTAINS CLEMENTSVILLE COMPRESSOR STATION LOCATED IN LIBERTY, KENTUCKY. ON THURSDAY JULY 14TH, 2022 THE MONITORING CENTER CALLED OUT STATION PERSONNEL TO INVESTIGATE THE SHUTDOWN OF 3 COMPRESSOR UNITS AT THE STATION AFTER GAS CONTROL HAD RECEIVED UNIT FAULT INDICATIONS. STATION PERSONNEL ARRIVED ON SITE AND DISCOVERED GAS BLOWING AT THE SIDE GATE OF THE STATION, THEY THEN CHECKED THE HMI CONTROL PANEL AND SAW THE 3 COMPRESSOR UNITS WERE STILL ONLINE AND RUNNING AND PROCEEDED TO SHUT THOSE UNITS DOWN. THE STATION PERSONNEL THEN WENT BACK TO THE HMI TO REVIEW ALARMS AND VALVE MOVEMENTS, AT THAT POINT THE BLOWDOWN HAD STOPPED. OTHER STATION TECHNICIANS WERE CALLED IN TO ASSIST AND AFTER TROUBLESHOOTING, DISCOVERED A SHORTED CLOSED LIMIT WIRE ON VALVE ACTUATOR 206-1PV. THE SHORTED WIRE TRIPPED A 24VDC BREAKER THAT FEEDS POWER TO DISCRETE I/O MODULES, WHICH ALSO CAUSED THE COMMS TO NOT FUNCTION. AFTER THE REPAIR OF THE SHORTED WIRE ROUTINE SAFETY CHECKS WERE COMPLETED WHICH INCLUDED A CHECK OF THE ESD SYSTEM TO ENSURE SAFETY AND RELIABILITY. ALL ALARMS WERE CLEARED AT THE CONTROL PANEL, FUNCTIONAL TESTS WERE COMPLETED WITH NO NEW ERRORS GENERATED TO ENSURE NORMAL OPERATION OF THE THREE UNITS. AN INVESTIGATION IS STILL UNDERWAY INTO THE CAUSE OF THE RELEASE. THE CALCULATED VOLUME OF GAS RELEASED WAS ESTIMATED TO BE 8,072.6 MCF THE CHRONOLOGY OF EVENTS ON JULY 14TH, 2022 ARE AS FOLLOWS (ALL TIMES WERE RECORDED IN LOCAL CENTRAL DAYLIGHT SAVING TIME): - 3:17 AM: A UNIT FAULT INDICATION WAS RECEIVED BY TC GAS CONTROL; - 3:50 AM: TC OPERATIONS PERSONNEL ARRIVED AT THE SITE AND LOCAL RESPONDERS WERE AT THE SITE; - 4:04 AM: TC REGULATORY COMPLIANCE MADE A REQUEST FOR VALVE SIZE, PRESSURE, AND TIME OF RELEASE; - 5:31 AM: TC MONITORING CENTER WAS NOTIFIED OF TOTAL GAS LOST, WHICH AT THE TIME, WAS CALCULATED TO BE 5792.8 MCF BY TC OPERATIONS MANAGER; - 5:35 AM: TC MONITORING CENTER NOTIFIED TC REGULATORY COMPLIANCE OF TOTAL GAS LOST; - 5:38 AM: NATIONAL RESPONSE CENTER WAS NOTIFIED OF THE INCIDENT; - 5:45 AM: PHMSA ACCIDENT INVESTIGATION DIVISION WAS NOTIFIED OF THE INCIDENT. THE DURATION OF THE GAS RELEASE WAS DETERMINED FROM OUR CONTROL SYSTEMS TO BE 29 MINUTES. INSPECTIONS REVEALED THAT THE MAIN BREAKER POWERING THE REMOTE I/O PANEL THAT CONTROLS VALVE 206-1BD WAS TRIPPED (CB244). FURTHER INVESTIGATION DISCOVERED DAMAGED AND SHORTED WIRING FEEDING VALVE 206-1PV WHICH WAS CONFIRMED TO BE THE CAUSE OF BREAKER CB244 FAULTING. NOTE REGARDING THE REVISED TIME IN QUESTION A4 ABOVE: IN RESPONSE TO THIS QUESTION THE TIME PROVIDED HERE IS AT THE DIRECTION OF PHMSA AID AND IS NOT AN ADMISSION; WE DID NOT HAVE SUFFICIENT INFORMATION TO DETERMINE WE HAD A REPORTABLE INCIDENT UNTIL 05:31.