MID - VALLEY PIPELINE CO

Incident Narrative

ON 5/29/19 AT APPROXIMATELY 10:35 AM, OPERATIONS EMPLOYEE WAS OPENING THE EXTERNAL FLOATING ROOF DRAINS ON TANKS AT LIMA STATION TO DRAIN STANDING WATER ON THE TANK ROOFS. AFTER THE DRAINING OF TANK 112 ROOF BEGAN IT WAS IDENTIFIED THAT THE WATER DRAINING FROM THE ROOF CONTAINED A SHEEN. UPON IDENTIFICATION THE DRAIN WAS CLOSED. NOTIFICATIONS WERE MADE TO MANAGEMENT AND CLEANUP BEGAN. ESTIMATED 8 GALLONS WAS RELEASED AND MIXED WITH WATER FROM THE ROOF DRAIN. ALL FREE PRODUCT WAS RECOVERED AND CONTAMINATED SOIL WAS REMOVED FOR REMEDIATION ON SITE. IT WAS DETERMINED THAT A SMALL AMOUNT RESIDUAL PRODUCT MIXED WITH THE WATER ON THE ROOF AND WAS RELEASED WHEN THE ROOF DRAIN WAS OPENED. SOURCE OF RESIDUAL PRODUCT ON ROOF WAS FROM WARMING TEMPERATURES THAT ALLOW PARAFFIN BUILDUP ON TANK WALLS TO LIQUIFY. THIS PARAFFIN SOLIDIFIES IN THE WINTER MONTHS ON THE TANK WALLS. TANK ROOF WAS SUBSEQUENTLY INSPECTED BY CONTRACT API 653 INSPECTOR AND NO ISSUES WERE IDENTIFIED WITH THE SEAL OR PONTOONS. TO PREVENT RECURRENCE ROOF WILL BE INSPECTED PRIOR TO OPENING OF ROOF DRAINS.