ENBRIDGE ENERGY, LIMITED PARTNERSHIP

Incident Narrative

ON JUNE 2, 2024, AT 12:01 AM THE EDMONTON CONTROL CENTER RECEIVED A SEAL FAILURE ALARM FOR UNIT 1 AT DEER RIVER STATION. THE CONTROL CENTER NOTIFIED THE ON-CALL TECHNICIAN AT 12:04 AM TO TRAVEL TO THE STATION TO INVESTIGATE. SHORTLY AFTER AT 12:12 AM, THE CONTROL CENTER RECEIVED ADDITIONAL LEAK DETECTION ALARMS WITHIN THE PUMPHOUSE WHICH LED THEM TO SHUT DOWN LINE 4 AND ISOLATE THE ENTIRE LINE 4 DEER RIVER STATION. THE TECHNICIAN ARRIVED AT 1:15 AM AND DISCOVERED CRUDE OIL LEAKING FROM THE SEAL AREA OF UNIT 1 ONTO THE CONCRETE FLOOR OF THE PUMPHOUSE. AT THIS TIME THE MANAGER ON-CALL WAS NOTIFIED, AND CREWS WERE SENT OUT TO BEGIN CLEANUP. APPROXIMATELY 9.5 BARRELS OF CRUDE OIL WAS RELEASED WITH 7.5 BARRELS BEING RETURNED TO THE SYSTEM. THE MAJORITY OF CRUDE OIL REMAINED INSIDE THE PUMPHOUSE WITH APPROXIMATELY ONE GALLON THAT MIGRATED OUTSIDE. THE SOURCE OF THE RELEASE WAS IDENTIFIED AS A FAILED PUMP SEAL ON UNIT 1. CRUDE OIL WAS CLEANED UP AND CLEAN UP MATERIAL WAS PROPERLY DISPOSED. THE CAUSE OF THE RELEASE WAS DETERMINED TO BE DUE TO A SUBSTANTIAL CHECK VALVE SLAM EVENT WHICH CAUSED A WATER HAMMER EFFECT UPSTREAM OF 4-UCV-21, THE UNIT CHECK VALVE FOR DEER RIVER LINE 4 UNIT 2, ULTIMATELY LEADING TO THE FAILURE OF THE UNIT 1 MECHANICAL SEAL. THE SEAL WAS REPLACED, AND UNIT 1 WAS RETURNED TO SERVICE.