TEXAS EASTERN TRANSMISSION, LP (SPECTRA ENERGY PARTNERS, LP)

Incident Narrative

ON JUNE 17, 2022, AT APPROXIMATELY 2:14 A.M. CDT THE LAHASKA REGULATING STATION (MR 78127) BEGAN DRIFTING OPEN. THIS EVENTUALLY RESULTED IN THE PRESSURE EXCEEDING THE DOWNSTREAM MAOP. AT 5:01 A.M. CDT RELIEF VALVES BEGAN OPENING APPROXIMATELY 6 MILES DOWNSTREAM AT THE LAMBERTVILLE COMPRESSOR STATION (CS). THE VOLUME RELEASED EXCEEDED THE 3 MMCF PHMSA REPORTING THRESHOLD. THE UPSTREAM EAGLE CS SERVES TWO PARALLEL LINES, LINE 1 (20-INCH) AND LINE 2 (36 & 20-INCH). THE MAOP OF LINE 1 IS 656 P.S.I.G. AND LINE 2 IS 1000 P.S.I.G. AT THE DISCHARGE OF EAGLE CS. APPROXIMATELY 6 MILES UPSTREAM OF THE LAMBERTVILLE CS THE MAOP OF LINE 2 IS LOWERED TO 656 P.S.I.G. AT MR 78127. THE CONTROL VALVES AT MR 78127 HAD BEEN SHUT-OFF ON THE PREVIOUS MONDAY, JUNE 13, 2022 FOR PLANNED MAINTENANCE WORK. PRELIMINARY INVESTIGATION INDICATES THE CONTROL SUPPLY GAS WAS SHUT OFF DURING THE MAINTENANCE WORK ON THURSDAY JUNE 16, 2022 AND SUPPLY GAS GRADUALLY BLED-OFF OVERNIGHT WHICH ALLOWED THE CONTROL VALVES TO DRIFT OPEN. PRESSURES ON LINE 2 DOWNSTREAM OF MR 78127 REACHED 731 P.S.I.G. OR 111% OF THE 656 P.S.I.G. MAOP (66.7% SMYS) AT LAMBERTVILLE COMPRESSOR STATION. PRESSURES ON SEGMENT OF LINE 1 ALSO EXCEEDED MAOP, BUT LESS THAN ALLOWABLE BUILDUP. THE EFFECTED SEGMENTS WERE LEAK SURVEYED WITH LEAK DETECTION EQUIPMENT. IN ADDITION, A REVIEW OF ILI DATA CONFIRMED THERE WERE NO ACTIONABLE ANOMALIES AT THE ELEVATED PRESSURES IN THE AFFECTED SEGMENTS. THE EVENT REMAINS UNDER INVESTIGATION. OCTOBER 11, 2022 PART E11 REGARDING THE INVESTIGATION INTO THE CONTROL ROOMS ACTIONS WAS UPDATED. PART G APPARENT CAUSE WAS UPDATED PART H - THE INVESTIGATION CONCLUDED THAT CONTROL GAS VALVES WERE LEFT IN THE WRONG POSITION DURING MAINTENANCE ACTIVITY. PROCEDURES WILL BE UPDATED, AND TRAINING WILL BE PROVIDED TO PREVENT RECURRENCE.