ENBRIDGE ENERGY, LIMITED PARTNERSHIP

Incident Narrative

ON OCTOBER 23 A TECHNICIAN NOTICED WHAT APPEARED TO BE OIL ON THE GROUND NEAR THE LINE 6 UNIT 4 DISCHARGE VALVE AT THE SUPERIOR TERMINAL. AFTER FURTHER INVESTIGATION AND EXCAVATION OF THE AREA THAT DAY, IT APPEARED TO BE CONTAMINATED SOIL FROM A HISTORIC LEAK THAT OCCURRED IN JULY 2000 WHEN A SIGNIFICANT VOLUME OF CRUDE OIL WAS RELEASED IN THAT SAME AREA. CLEANUP OF THE CONTAMINATED SOIL COMMENCED. MULTIPLE FLANGES WERE EXCAVATED, THE LINE 6 UNIT 4 PUMP WAS LOCKED OUT, AND THE AREA CONTINUOUSLY MONITORED. ON NOVEMBER 6 AN ACTIVE LEAK WAS CONFIRMED BY PLM PERSONNEL TO BE COMING FROM THE FLANGE OFF THE L6 UNIT 4 DISCHARGE VALVE. THE LEAK WAS VERY INTERMITTENT AND WOULD COME AND GO WITH A SMALL DROP OF OIL. THE PIPELINE MAINTENANCE PERSONNEL REPLACED THE BOLTS AND RE-TORQUED THE FLANGE ON NOVEMBER 11 IN CONJUNCTION WITH A PREVIOUSLY UNRELATED SCHEDULED SHUTDOWN OF LINE 6. THE UNIT WAS PLACED BACK INTO SERVICE LATER THAT SAME DAY. THE CAUSE OF THE LEAK IS CURRENTLY UNDER INVESTIGATION. THERE WAS APPROXIMATELY 258 CUBIC YARDS OF CONTAMINATED SOIL REMOVED FROM THE SITE. THE INTERNAL INVESTIGATION REVEALED THE CAUSE OF THE LEAK WAS THAT THE FLANGE FASTENERS WERE NOT AT THE PROPER TORQUE VALUE. THE FINAL REPAIR WILL BE THE REPLACEMENT OF THE UNIT VALVE AND CHECK VALVE FLANGE GASKETS. THIS IS SCHEDULED TO BE COMPLETED FALL 2014.