ENBRIDGE ENERGY, LIMITED PARTNERSHIP

Incident Narrative

AT APPROXIMATELY 7:45 AM ON JULY 27, 2015, A LINE 2 INTEGRITY DIG CREW, UPON ARRIVAL TO THE REMOTE VALVE SITE AT MP 1021.68, NOTICED THAT A SMALL AMOUNT OF CRUDE OIL HAD LEAKED FROM A 12"" OUT OF SERVICE CROSSOVER/LOOP VALVE WHICH WAS TIED INTO LINE 2. THE EDMONTON CONTROL CENTER WAS CONTACTED AND LINE 2 WAS SHUT DOWN. OPERATION CREWS WERE DISPATCHED TO THE SITE TO DETERMINE THE SOURCE OF THE LEAK. UPON ARRIVAL, IT WAS DISCOVERED THAT APPROXIMATELY ONE CUP OF OIL HAD LEAKED FROM THE VALVE BONNET. REGION MANAGEMENT MADE THE DECISION TO ISOLATE THE CROSSOVER VALVE VIA STOPPLE INSTALLATION AND REMOVE IT FROM THE SYSTEM. THE NATIONAL RESPONSE CENTER NOTIFICATION WAS MADE ONCE THE FINAL REPAIR PLAN WAS DETERMINED AND THE COSTS ASSOCIATED WITH THAT PLAN WERE ESTIMATED TO EXCEED $50,000. AFTER FURTHER INVESTIGATION, IT WAS DETERMINED THAT THE VALVE WAS EXPOSED TO AMBIENT TEMPERATURE, CAUSING THERMAL PRESSURE BUILDUP WITHIN THE BODY OF THE VALVE. THE VALVE DID NOT CONTAIN A PRESSURE RELIEF SYSTEM, THEREFORE THE THERMAL PRESSURE BUILDUP CAUSED THE VALVE BODY TO LEAK AT THE BONNET, RELEASING A SMALL AMOUNT OF PRODUCT. FUTURE LINE 2 HYDROTEST PREPARATION DIGS INVOLVING VALVES WITHOUT A PRESSURE RELIEF SYSTEM WILL BE SHADED EITHER BY A TENT OVER THE VALVE OR WRAPPING WITH AN INSULATING MATERIAL. THE SMALL AMOUNT OF CONTAMINATED SOIL WILL BE MANAGED ONSITE AT THE ENBRIDGE CLEARBROOK MINNESOTA TERMINAL.