SABAL TRAIL TRANSMISSION, LLC (SPECTRA ENERGY PARTNERS, LP) — Gas transmission and gathering — incident on 2019-03-06

Gas transmission and gathering incident in DAVENPORT, OSCEOLA County, FL. Reported cause: EQUIPMENT FAILURE. Reported consequences: 0 fatalities, 0 injuries, 21700 NATURAL GAS released, $0 reported property damage. Operator-reported incident data submitted to PHMSA, generally within 30 days. Records may be supplemented or corrected and do not represent final agency causal findings.

Report number: 20190038.

Operator ID: 39167.

Reported incident date: 3/6/2019 2:05.

Location detail: 482.37

Cause detail: MALFUNCTION OF CONTROL/RELIEF EQUIPMENT

Cause detail: 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.

PHMSA trend classification: significant incident, not serious.

PHMSA standardized cause: EQUIPMENT FAILURE — MALFUNCTION OF CONTROL/RELIEF EQUIPMENT.

PHMSA indexed costs: $59,458 reported total cost, $61,642.808 in 1984 dollars, $75,688.005 in current-year dollars.

PHMSA trend flags, standardized causes, and indexed costs are analytical fields added to operator-reported incident data. They do not represent final agency causal findings.