"ENBRIDGE ENERGY, LIMITED PARTNERSHIP"

Incident Narrative

"ON NOVEMBER 18, 2024, AT 9:17 AM CST, A TECHNICIAN WAS DOING MAINTENANCE NEAR THE LINE 4 UNIT 2 VALVE (DN-4-UDV-21) AT DONALDSON STATION. DURING A WALK AROUND THEY DISCOVERED CRUDE OIL ON THE VALVE AND THE SURROUNDING GROUND. THE EDMONTON CONTROL CENTER WAS IMMEDIATELY NOTIFIED, AND THE UNIT WAS ISOLATED. THE SOURCE OF THE RELEASE WAS A LEAKING VALVE STEM SEAL THAT RELEASED APPROXIMATELY 1.25 GALLONS OF CRUDE OIL. THE NRC WAS NOTIFIED ON NOVEMBER 18, 2024, AT 10:16 AM CST (NRC #1416706). THE MINNESOTA DUTY OFFICER WAS ALSO NOTIFIED (#224022). OPERATIONS AND CONTRACTED LABOR RESPONDED TO THE SITE TO CLEAN UP ANY CONTAMINATED SOIL. OPERATIONS PERFORMED A STEM SEAL PACKING OPERATION AFTER THE VALVE WAS CLOSED WHICH STOPPED THE LEAKAGE. A 48-HOUR UPDATE TO THE NRC WAS MADE ON NOVEMBER 20, 2024, AT 10:01 AM CST (NRC #1416880). ALL CONTAMINATED SOIL HAS BEEN REMOVED FROM THE RELEASE SITE. THE REPAIR ASSEMBLY WAS INSTALLED ON DECEMBER 18, 2024. ENBRIDGE PERSONNEL COMPLETED THE STEM SEAL INVESTIGATION AND REPAIR WITH THE MANUFACTURER PRESENT. IT WAS DETERMINED THAT TWO CONTRIBUTING FACTORS CAUSED THE STEM SEAL FAILURE. THE FIRST OBSERVATION WAS DEBRIS BUILD-UP WITHIN THE STEM SEAL ASSEMBLY. THE OBSERVED DEBRIS COULD HAVE CONTRIBUTED TO THE DAMAGED STEM. THIS DEBRIS COULD HAVE BEEN LEFT IN THE ASSEMBLY DURING MANUFACTURING. THE SECOND OBSERVATION WAS THAT THE STEM WAS DAMAGED/GOUGED WHICH COULD HAVE ALSO OCCURRED DURING THE MANUFACTURING PROCESS. THE DAMAGED STEM CREATED A LEAK PATH FOR THE SEAL TO FAIL. THE ACTUAL VOLUME RELEASED AT DONALDSON STATION WAS 0.02 BARRELS (1.25 GALLONS) OF CRUDE OIL. THE PHMSA PORTAL DOES NOT RECOGNIZE VOLUMES LESS THAN 0.1 BARRELS THEREFORE THAT IS THE VOLUME ENTERED."