ENBRIDGE ENERGY, LIMITED PARTNERSHIP

Incident Narrative

ON JANUARY 8, 2010 AT 23:38 LOCAL TIME, THE ENBRIDGE CONTROL CENTRE NOTICED A SUDDEN DROP IN PRESSURE ON LINE 2 AND IMMEDIATELY SHUT THE PIPELINE DOWN. ENBRIDGE SUPERIOR REGION OPERATIONS AND CENTRAL REGION OPERATIONS (CANADA) WERE NOTIFIED AND DISPATCHED. UPON ARRIVAL, COMPANY PERSONNEL DISCOVERED A LEAK ESTIMATED AT APPROXIMATELY 3,000 BARRELS CONTAINED PRIMARILY TO THE COMPANY RIGHT-OF-WAY. ADDITIONAL COMPANY RESOURCES WERE IMMEDIATELY DISPATCHED TO CONTROL AND CLEAN-UP THE RELEASED OIL, INVESTIGATE THE CAUSE OF THE RELEASE AND TO REPAIR THE PIPELINE FOR RETUM TO SERVICE. THE NATIONAL RESPONSE CENTER AND NORTH DAKOTA STATE INCIDENT REPORTING HOTLINES WERE CONTACTED. THE PRELIMINARY CAUSE OF THE PIPELINE RUPTURE WAS A FAILURE IN A SECTION OF THE LONGITUDINAL SEAM OF THE PIPE. THE AFFECTED PIPE SEGMENT WAS REMOVED DURING THE REPAIR AND HAS BEEN SENT TO A THIRD-PARTY METALLURGICAL LAB FOR ANALYSIS. THE PIPELINE WAS REPAIRED AND WAS RESTARTED ON JANUARY 13, 2010 AT APPROXIMATELY 09:17 LOCAL TIME. SITE DEAN-UP (SOIL EXCAVATION) IS CURRENTLY STILL BEING COMPLETED; HOWEVER NO LONG TERM REMEDIATION ACTIVITIES ARE EXPECTED. A PHMSA REPRESENTATIVE WAS ONSITE DURING THE EMERGENCY RESPONSE AND REPAIR ACTIVITIES AND WAS INVOLVED WITH THE RETUM TO SERVICE PLAN. ENBRIDGE WILL BE WORKING WITHPHMSA DURING THE INVESTIGATION AND WILL BE SHARING THE RESULTS OF THE INVESTIGATION/FAILURE ANALYSIS. SUPPLEMENTAL/FINAL REPORT (UPDATE AS OF APRIL 1,, 2011) THE METALLURGICAL INVESTIGATION THAT WAS CONDUCTED CONCLUDED THAT THE FAILURE WAS THE RESULT OF A FATIGUE CRACK THAT INITIATED AT A LOCATION ALONG THE FLASH WELDED SEAM, FROM THE INSIDE PIPE DIAMETER. THE INVESTIGATION REVEALED NO PRE-EXISTING WELDING OR PIPE BODY DEFECTS, OR MATERIAL PROPERTY DEFICIENCIES THAT COULD HAVE CONTRIBUTED TO CRACK INITIATION, CRACK GROWTH, OR FINAL FAILURE. WELD MISALIGNMENT AND PEAKING WERE OBSERVED AT THE INITIATION LOCATION. THE CRACK GREW IN SERVICE UNDER CYCLIC LOADS UNTIL IT REACHED A CRITICAL SIZE AND RUPTURED. SITE CLEAN UP IS COMPLETED AND THE LEAK SITE HAS OFFICIALLY BEEN CLOSED BY THE ENVIRONMENTAL HEALTH SECTION OF THE NORTH DAKOTA DEPARTMENT OF HEALTH. APPROXIMATELY 4760 CUBIC YARDS OF CONTAMINATED SOIL WERE DISPOSED OF AT AN APPROVED LAND FILL.