NUSTAR TERMINALS OPERATIONS PARTNERSHIP L. P.

Incident Narrative

"ON DECEMBER 16, 2010, CONTRACT TANK CLEANING PERSONNEL ENTERED TANK 15021 WHICH HAD BEEN TAKEN OUT OF SERVICE FOR CLEANING AND A SCHEDULED 653 INTERNAL INSPECTION. WHILE CLEANING THE TANK, THE CONTRACTORS DISCOVERED PRODUCT RE-ENTERING THE TANK'S SUMP THROUGH A PINHOLE IN THE BOTTOM FLOOR OF THE TANK SUMP. THE PINHOLE WAS CUTOUT TO ALLOW FOR MORE PRODUCT TO DRAIN BACK INTO THE TANK FROM THE SURROUNDING SOIL, WHERE IS WAS RECOVERED. AS OF JANUARY 13, 2011, APPROXIMATELY 1146 GALLONS OF PRODUCT HAS BEEN RECOVERED. NO PRODUCT IS BELIEVED TO HAVE ESCAPED THE TANK FARM'S SECONDARY CONTAINMENT DUE TO CONSTRUCTION OF AN IMPERVIOUS CLAY LINER WITHIN THE TANK DIKES, IN ACCORDANCE WITH THE FACILITY'S NEW JERSEY DISCHARGE PREVENTION, CONTAINMENT, AND COUNTERMEASURES PLAN (NJ DPCC). METALLURGICAL ANALYSIS CONCLUDED THAT THROUGH-WALL CORROSION OCCURRED FROM THE PRODUCT SIDE OF THE SUMP PLATE. THE CORROSION MECHANISM IS CONSISTENT WITH GALVANIC CORROSION THAT WAS ACCELERATED BY IMPACT FROM GAUGING AND PRODUCT SAMPLING EQUIPMENT. THE GAUGING AND/OR PRODUCT SAMPLING EQUIPMENT ARE BELIEVED TO HAVE INITIALLY DAMAGED THE TANK INTERNAL COATING, RESULTING IN CORROSION INITIATION. ENTRAINED WATER WITHIN THE REFINED PETROLEUM PRODUCTS IS BELIEVED TO BE RESPONSIBLE FOR THE CORROSIVE ENVIRONMENT WITHIN THE SUMP. CORROSION PRODUCTS THAT FORMED ON THE EXPOSED STEEL WERE DAMAGED BY THE GAUGING/SAMPLING EQUIPMENT, EXPOSING FRESH STEEL AND RESULTING IN ACCELERATION OF THE CORROSION. MICROBIOLOGICALLY INFLUENCED CORROSION (MIC) IS NOT BELIEVED TO HAVE BEEN RESPONSIBLE FOR THE THROUGH-WALL CORROSION."