ALGONQUIN GAS TRANSMISSION, L.L.C. (SPECTRA ENERGY PARTNERS, LP)

Incident Narrative

ORIGINAL REPORT: 48 HR NRC REPORT 1233090 AT APPROXIMATELY 9:38 AM EST ON DECEMBER 13, 2018, A GAS UTILITY COMPANY NOTIFIED ENBRIDGE OF A POSSIBLE NATURAL GAS RELEASE DISCOVERED DURING A LEAK SURVEY IN CLOSE PROXIMITY TO ALGONQUIN GAS TRANSMISSION'S (AGT) NATURAL GAS PIPELINE AT SOUTHINGTON, CONNECTICUT. ENBRIDGE PERSONNEL WERE IMMEDIATELY DISPATCHED TO THE SITE AT ABOUT 10:30 AM EST. AGT'S INITIAL LEAK SURVEYS WAS INCONCLUSIVE BECAUSE OF THE LOW GAS LEVELS. AGT PERFORMED FURTHER TESTS WITH AN ETHANE GAS DETECTOR AND CONCLUSIVELY DETERMINED THE ORIGIN OF THE GAS RELEASE WAS FROM AGT'S PIPELINE FACILITIES AT ABOUT 2:00 PM EST. AGT PROACTIVELY MADE THE NRC CALL AT 2:36 PM EST AFTER DETERMINING THE COST OF EXCAVATION ACTIVITIES TO REPAIR THE LEAK WOULD EXCEED THE $50,000. AGT MADE EMERGENCY ONE CALL TICKETS AND REQUESTS FROM THE CITY OF SOUTHINGTON WERE PUT IN FOR EXCAVATION ACTIVITIES. AGT MOBILIZED CONTRACTORS TO BEGIN EXCAVATION ACTIVITIES AT THE SITE ON DECEMBER 14 AT ABOUT 8:00 AM. AGT UPON EXCAVATION, ENBRIDGE DETERMINED THAT THE APPARENT CAUSE OF THE LEAK WAS FROM A 1INCH THREADED NIPPLE. THE PIPE WAS REPLACED ON JANUARY 9-10, 2019. THE CAUSE OF THE RELEASE IS UNDER INVESTIGATION. SUPPLEMENTAL REPORT: THE APPARENT CAUSE IS THE 1 INCH THREADED NIPPLE WAS NOT PROPERLY TORQUED INTO THE THREAD-O-LET, RESULTING IN THE NATURAL GAS LEAK.