ENBRIDGE ENERGY, LIMITED PARTNERSHIP

Incident Narrative

AT APPROXIMATELY 4:55 PM ON JULY 28, 2015, A CONTRACTOR EMPLOYEE PERFORMING ROUNDS AT THE GRIFFITH TERMINAL DISCOVERED A RELEASE FROM THE MANIFOLD-SIDE FLANGE OF THE TANK VALVE 301-V-7921 DURING A SCHEDULED STATION OUTAGE FOR VARIOUS VALVE STEM SEAL REPLACEMENTS. THE INITIAL VOLUME OUT WAS ESTIMATED TO BE APPROXIMATELY 21 GALLONS BASED ON IMMEDIATE VISUAL ASSESSMENT. THE PRODUCT REMAINED COMPLETELY WITHIN THE AREA OF THE TANK VALVES. PLM ARRIVED ON SITE AND CLEANED UP THE IMPACTED SOIL. AFTER ADDITIONAL MEASUREMENTS WERE TAKEN BY THE GRIFFITH PLM, THE VOLUME WAS UPDATED TO 39 GALLONS. APPROXIMATELY 10 CUBIC YARDS OF CONTAMINATED SOIL WAS DISPOSED OF AT AN APPROVED SITE. THE INVESTIGATION YIELDED THAT A CONTRACT EMPLOYEE FROM FUTURE ENVIRONMENTAL WAS ASSIGNED THE DUTY OF MONITORING PRESSURE ON ISOLATED PIPING SECTIONS DURING THE STATION OUTAGE. THE CONTRACT EMPLOYEE MONITORED EACH LOCATION EVERY HALF HOUR, BUT FAILED TO OPEN A 2"" VALVE ON THE MANIFOLD HEADERS THAT WOULD EXPOSE THE PRESSURE GAUGES TO AMBIENT CONDITIONS. THE CONTRACT EMPLOYEE DID NOT UNDERSTAND THAT HE NEEDED TO OPEN THE 2"" VALVES BELOW THE PRESSURE GAUGES. THE HIGH TEMPERATURES DURING THE AFTERNOON CAUSED A THERMAL PRESSURE BUILDUP IN THE TANK 79 MANIFOLD PIPING WHICH RESULTED IN A FAILED FLANGED CONNECTION (GASKET) BETWEEN THE MANIFOLD PIPE AND THE TANK VALVE. THE TERMINAL STAFF SUSPENDED THE OUTAGE WORK, REVERSED THE LOCKOUT/TAG OUT, AND RELIEVED PRESSURE AT EACH OF THE SECTIONS OF PIPING THAT WERE IMPACTED. FOLLOWING THIS ACTION, THE REMAINING STEM SEAL REPLACEMENT PROJECT WAS RESCHEDULED FOR A LATER DATE AND THE STATION RETURNED TO SERVICE.