ENBRIDGE ENERGY, LIMITED PARTNERSHIP

Incident Narrative

ON AUGUST 2, 2021 AT APPROXIMATELY 3:05 PM CDT OPERATIONS PERSONNEL COMPLETING ROUTINE ROUNDS FOUND OIL ON THE GROUND IN MANIFOLD 202 AT GRIFFITH TERMINAL NEAR TRANSFER LINE 1. THE SECTION OF PIPE WAS ISOLATED AND CREWS WERE CALLED ON SITE TO BEGIN CLEAN UP AND EXCAVATION OF THE AFFECTED AREA. ONCE EXCAVATION WAS COMPLETE THE SOURCE OF THE LEAK WAS DETERMINED TO BE A FLANGED CONNECTION ON TRANSFER LINE 1. THE GASKET WAS REPLACED AND THE FLANGE WAS RETORQUED. DUE TO A RAIN EVENT DURING THE NIGHT, THE EXCAVATION AREA FILLED WITH WATER. AN ADDITIONAL CONTRACTING CREW NEEDED TO BE CALLED IN FOR DEWATERING PURPOSES THEREFORE INCREASING THE OPERATOR COST OF THE RELEASE. THE NRC WAS NOTIFIED ONCE IT WAS DETERMINED THAT COSTS WOULD EXCEED THE $50,000 REPORTING THRESHOLD DUE TO ADDITIONAL CLEAN UP. THE NRC WAS NOTIFIED ON AUGUST 3, 2021 AT 8:05 AM CDT (REPORT #1312603). A 48-HOUR UPDATE WAS MADE TO THE NRC ON AUGUST 4, 2021 AT 12:08 PM CDT (REPORT #1312766). THE BOLTS WERE REMOVED FROM THE FLANGE CONNECTION AND WERE SENT FOR A THIRD-PARTY ANALYSIS AND FIELD INVESTIGATION WAS COMPLETED. THE CAUSE OF THE RELEASE WAS DETERMINED TO BE DUE TO A RELAXED FLANGE. DUE TO THE AREA BEING EXCAVATED AND REPACKED SEVERAL TIMES OVER THE YEARS FOR OTHER WORK IN THE MANIFOLD AREA, THE FLANGE RELAXED OVER TIME. THIS CAUSED THE GASKET TO EVENTUALLY DEVELOP A WEEP WHICH LEAKED INTO THE SURROUNDING SOIL UNTIL IT WAS DISCOVERED BY OPERATIONS WHEN IT REACHED THE SURFACE. APPROXIMATELY 70 CUBIC YARDS OF CONTAMINATED SOIL WAS REMOVED FROM THE RELEASE SITE.