COLUMBIA GULF TRANSMISSION, LLC

Incident Narrative

DURING NORMAL ROUNDS MADE BY A LANDOWNER IN THE RIGHT-OF-WAY (ROW) OF EAST LATERAL 300 (EL300) PIPELINE, OWNED AND OPERATED BY COLUMBIA GULF TRANSMISSION LLC (CGT), A TC ENERGY COMPANY (COMPANY), IN SOUTH LOUISIANA, A CONTINENTAL LAND AND FUR REPRESENTATIVE (LAND OWNER) NOTICED BUBBLES DEVELOPING RIGHT OFF THE CGT ROW. THE LAND OWNER INFORMED LOCAL CGT TEAM MEMBERS, PERFORMING MAINTENANCE ON NEARBY COMPANY ASSETS, AND THEY CONDUCTED A PRELIMINARY INVESTIGATION INTO THE AREA IN QUESTION. THE LEAK LOCATION WAS GRADED AS NON-HAZARDOUS TO ANYONE IN THE LOCAL VICINITY AS THIS IS LOCATED IN A REMOTE AREA. PLANS WERE MADE TO FURTHER INVESTIGATE THE FOLLOWING DAY. GAS SAMPLES WERE TAKEN TO DETERMINE IF THIS WAS MARSH GAS OR PIPELINE GAS. AFTER TWO SEPARATE GAS SAMPLES WERE PULLED AND BROUGHT IN TO A LOCAL LABORATORY, THE CGT INTEGRITY TEAM MADE A DETERMINATION BY COMPARING PIPELINE QUALITY GAS TO THE SAMPLES THAT THE CHARACTERISTICS OF THE GAS WERE SIMILAR ENOUGH TO MERIT NAMING THIS A LEAK ON THE EL 300 SYSTEM. THIS LEAK IS SUSPECTED TO BE ON AN ISOLATED 4-INCH TAP VALVE THAT USED TO BE A CABOT GAS FEED. INTEGRITY ENGINEERING ALONG WITH THE INVESTIGATING DIVE PARTY WILL WORK TO ANALYZE THE LEAK AND DEVELOP PLANS TO DETERMINE HOW TO ADDRESS AND MITIGATE. ON MARCH 26, 2021 AN ATTEMPT WAS MADE TO REPAIR THE LEAKING VALVE BY ENCAPSULATION; HOWEVER, THIS EFFORT WAS NOT SUCCESSFUL. ON MARCH 7, 2022 THE COMPANY MOBILIZED TO THE SITE OF THE LEAK TO BEGIN LOCATING THE TAP VALVE IDENTIFIED FOR CUTOFF AND REPAIR. THE REPAIR CONSISTED OF CUTTING THE DAMAGED VALVE ON THE FOUR INCH RISER OFF OF EL300 AND BLIND FLANGING THE RISER. AS OF APRIL 8, 2022, TC ENERGY HAS DEMOBILIZED FROM THE SITE OF THE LEAK LOCATED ON EAST LATERAL 300 LINE (EL300).