HOLLY ENERGY PARTNERS - OPERATING, L.P.

Incident Narrative

ON THE EARLY EVENING OF JULY 13, 2014 WE EXPERIENCED AN UNINTENTIONAL RELEASE OF APPROXIMATELY 500 BARRELS OF CRUDE OIL FROM TANK 73 IN THE CHEYENNE FRONTIER REFINERY. EARLIER IN THE AFTERNOON CHEYENNE HAD EXPERIENCED A SEVERE THUNDERSTORM THAT INCLUDED LARGE AMOUNTS OF RAIN AND HAIL. THE HAIL ACCUMULATED SO QUICKLY ON THE EXTERNAL FLOATING ROOF OF TANK 73 THAT THE ROOF DRAIN SUMP WAS FROZEN OVER RESULTING IN THE ROOF DRAIN BECOMING PLUGGED AND NOT ALLOWING ANY WATER TO DRAIN FROM THE ROOF. HAIL AND RAIN CONTINUED TO COLLECT ON THE ROOF ADDING EXCESS WEIGHT CAUSING THE ROOF TO BEGIN TO SINK. AS THE ROOF BEGAN TO SINK CRUDE OIL BEGAN MIGRATING ONTO THE ROOF THROUGH THE LEG PORTS ADDING MORE WEIGHT. ONCE THE CRUDE OIL CAME IN CONTACT WITH THE FROZEN HAIL IT BEGAN MELTING ALLOWING BOTH WATER AND CRUDE OIL TO DRAIN ONTO THE GROUND AROUND THE TANK RELEASING APPROXIMATELY 500 BARRELS OF CRUDE OIL. THE EMERGENCY RESPONSE TEAM WAS ABLE TO CLOSE THE DRAIN VALVE STOPPING THE FLOW ONTO THE GROUND, VACUUM TRUCKS WERE ONSITE, CONTINUED TO REMOVE THE WATER AND OIL FROM THE CONTAINMENT AREA UNTIL IT HAD BEEN COMPLETELY REMOVED. THE FOLLOWING MORNING ON JULY 14, 2014 A DECISION WAS MADE TO DRAIN THE BALANCE OF THE WATER AND OIL FROM THE TOP OF THE ROOF TO AVOID ANY FURTHER DAMAGE IN THE EVENT OF ANOTHER SIGNIFICANT RAIN WHICH WAS FORECASTED FOR LATER IN THE DAY. THE ROOF DRAIN WAS OPENED AND APPROXIMATELY 1,000 BBLS WAS DRAINED IN A CONTROLLED SETTING WITH VACUUM TRUCKS PRESENT FOR IMMEDIATE RECOVERY. DUE TO THE HEAVY RAINS PRIOR TO THE RELEASE THE GROUND IN THE SECONDARY CONTAINMENT AREA WAS SATURATED AND THE OIL FLOATED ON THE WATER UNTIL IT WAS REMOVED. THIS RESULTED IN VERY LITTLE GROUND CONTAMINATION FROM THE CRUDE OIL. AFTER THE ROOF WAS COMPLETELY DRAINED IT WAS CLEANED AND INSPECTED AND FOUND TO HAVE SUSTAINED NO DAMAGE AND IT WAS RETURNED TO SERVICE ON JULY 15, 2014 AND 100% OF THE RELEASE WAS CONTAINED IN THE SECONDARY CONTAINMENT AREA RESULTING IN NO HAZARDS TO HUMAN HEALTH OR THE ENVIRONMENT. ON JULY 16, 2014, PETER KATCHMAR WITH PHMSA WESTERN REGION CONDUCTED A FIELD VISIT AND REVIEWED THE DETAILS OF THE INCIDENT.