SABAL TRAIL TRANSMISSION, LLC (SPECTRA ENERGY PARTNERS, LP)

Incident Narrative

ORIGINAL REPORT: 48 HR NRC REPORT 1239356 AT APPROXIMATELY 5:00 AM EST ON MARCH 6, 2019, AN ENBRIDGE TECHNICIAN DISCOVERED A NATURAL GAS RELEASE THROUGH A VENT VALVE ON UNIT 1 AT THE REUNION COMPRESSOR STATION ON THE SABAL TRAIL TRANSMISSION (STT) SYSTEM IN OSCEOLA COUNTY, FL. THE NATURAL GAS RELEASED OCCURRED DURING COMPRESSOR STATION UNIT OPERATIONS SWITCHOVER FROM UNIT 1 TO UNIT 2. AT APPROXIMATELY 2:05 AM EST, ENBRIDGE GAS CONTROL ISSUED A CALL ATTENDANT AND DISPATCHED AN ENBRIDGE TECHNICIAN HAVING DIFFICULTIES SWITCHING FROM UNIT 1 TO UNIT 2. AN ENBRIDGE TECHNICIAN ARRIVED ON SITE AT APPROXIMATELY 3:00 AM EST AND CLEARED ALARM ON UNIT 1. AT APPROXIMATELY, 5:00 AM EST THE ENBRIDGE TECHNICIAN DETERMINED THAT A SUCTION VALVE ON UNIT 1 HAD MALFUNCTIONED AND DID NOT COMPLETELY CLOSE RESULTING IN NATURAL GAS BEING VENTED TO THE STATION SOURCE CONTROL. THE ENBRIDGE TECHNICIAN SUBSEQUENTLY ISOLATED A MANUAL BLOCK VALVE DOWNSTREAM OF VENT VALVE TO STOP THE RELEASE OF NATURAL GAS TO ATMOSPHERE BAT 5:30AM EST. ENBRIDGE WAS UNABLE TO DETERMINE THE ESTIMATED GAS LOSS UNTIL APPROXIMATELY 9:00 AM EST. THE APPARENT CAUSE OF THE NATURAL GAS RELEASE IS STILL UNDER INVESTIGATION. SUPPLEMENTAL REPORT: THE CAUSE OF THE NATURAL GAS RELEASE WAS A MALFUNCTION OF THE UNIT 1 SUCTION VALVE DUE TO A FAULTY LIMIT SWITCH.