ENBRIDGE ENERGY, LIMITED PARTNERSHIP

Incident Narrative

ON APRIL 4, 2019 AT APPROXIMATELY 10:00 AM CDT CRUDE OIL WAS DISCOVERED IN AN EXCAVATION NEAR VALVE 221-V-2406 WITHIN THE SUPERIOR TERMINAL (THIS EXCAVATION WAS UNRELATED TO THIS INCIDENT). THE LOCATION OF THE DISCOVERED PRODUCT WAS IN AN AREA OF A HISTORICAL RELEASE SITE, THEREFORE OPERATIONS PERSONNEL MONITORED THE AREA AND INSTALLED THREE POTHOLES IN AN EFFORT TO DETERMINE IF THE CRUDE OIL WAS FROM A CURRENT OR HISTORICAL RELEASE. ON APRIL 6, 2019 AN OIL/WATER MIXTURE WAS DISCOVERED IN THE POTHOLES, THE CONTROL CENTER WAS CONTACTED AND THE AREA OF CONCERN WAS ISOLATED AND PIPELINE MAINTENANCE PERSONNEL BEGAN EXCAVATING TO INVESTIGATE THE SOURCE OF THE RELEASE. WHILE ONSITE TO OBSERVE A DELIVERY INTO TANK 24 ON APRIL 13, 2019 AT APPROXIMATELY 12:15 PM CDT, FIELD PERSONNEL OBSERVED A PINHOLE LEAK AT THE 6:00 POSITION OF THE GIRTH WELD ON A 45 DEGREE ELBOW THAT WAS ON THE SHORT PIECE OF 24"" PIPING THAT CONNECTED LINE 6 WITH THE TANK 24 HEADER LINE. THE NRC WAS NOTIFIED ON APRIL 13, 2019 AT 1:11 PM CDT (REPORT #1242662). THE 48-HOUR NRC NOTIFICATION WAS MADE ON APRIL 15, 2019 AT 9:16 AM CDT (REPORT #1242765). AFTER FURTHER INVESTIGATION IT WAS DETERMINED THAT INTERNAL CORROSION CAUSED THE PINHOLE WHICH LED TO THE RELEASE OF TWO BARRELS OF CRUDE OIL. A LEAK CLAMP WAS INSTALLED OVER THE FAILURE. TANK 24 IS CURRENTLY OUT OF SERVICE FOR AN API 653 INSPECTION. THIS SHORT PIECE OF DEAD LEG PIPING WILL BE REMOVED FROM THE SYSTEM PRIOR TO TANK 24 GOING BACK INTO SERVICE. APPROXIMATELY 350 CUBIC YARDS OF CONTAMINATED SOIL WILL BE DISPOSED OF AT AN APPROVED LANDFILL.