"MID-CONTINENT FRACTIONATION AND STORAGE, L.L.C."

Incident Narrative

"NARRATIVE DESCRIPTION OF THE ACCIDENT AT 07:55 HOURS ON THE MORNING OF DECEMBER 31, 2010 A THIRD-PARTY CUSTOMER (OPERATOR) WAS MOVING NATURAL GASOLINE THROUGH THEIR MANIFOLD PIPING. TYPICALLY, WHEN THIRD PARTY PRODUCT MOVEMENTS OCCUR, THE PRODUCT BEING MOVED IS EITHER DELIVERED OR RECEIVED FROM MID-CONTINENT FRACTIONATION AND STORAGE (WILLIAMS') CAVERNS; HOWEVER, DURING THIS MOVEMENT, THE THIRD PARTY OPERATOR REQUESTED WE CLOSE OUR METER RUN VALVES TO ALLOW THEM TO 'TIGHT LINE' PRODUCT THUS BYPASSING DELIVERY OR RECEIPTS FROM WILLIAMS'. DURING THESE 'TIGHT LINE' OCCURRENCES THE WILLIAMS CONTROLLER CLOSES A GENERAL TWIN VALVE EQUIPPED WITH A MOTOR OPERATED VALVE (MOV) LOCATED ON OUR METER RUN THAT ALLOWS THE WILLIAMS CONTROLLER TO REMOTELY OPEN OUR CAVERN SYSTEM THEREBY RELIEVING PRESSURE FOR THE THIRD PARTY OPERATOR IN THE EVENT OF A POSSIBLE OVERPRESSURE IN THEIR MANIFOLD. AT THE TIME OF THE OVERPRESSURE INCIDENT, THE WILLIAMS CONTROLLER RECEIVED A HIGH PRESSURE WARNING ALARM ASSOCIATED WITH THE CLOSED METER RUN. THE WILLIAMS CONTROLLER IMMEDIATELY SENT THE OPEN COMMAND TO THE MOV LOCATED ON THE METER RUN, HOWEVER THE PRESSURE CLIMBED RAPIDLY AND BEFORE THE VALVE COULD OPEN COMPLETELY, PRESSURE REACHED 840 PSIG RESULTING IN APPROXIMATELY 50 FEET OF METER RUN PIPING AND EQUIPMENT TO EXCEED 110 PERCENT OF MOP FOR PERIOD OF 45 SECONDS AND THE RELEASE OF 4.5 BARRELS OF PRODUCT VENTED TO ATMOSPHERE FROM THE THERMAL RELIEF LOCATED ON THE VALVE. REQUESTS FOR ADDITIONAL INFORMATION FROM THE THIRD PARTY OPERATOR HAVE BEEN MADE HOWEVER THE FINAL CAUSE OR CAUSES OF THE INCIDENT MAY NOT BE KNOWN UNTIL BOTH PARTIES COMPLETE THEIR RESPECTIVE INVESTIGATIONS. ALTHOUGH THE WILLIAMS OPERATING PROCEDURES WERE FOLLOWED BY THE WILLIAMS CONTROLLER AT THE TIME OF THE INCIDENT WE FULLY UNDERSTAND OUR RESPONSIBILITY TO INVESTIGATE THIS INCIDENT AND TO MAKE ALL NECESSARY IMPROVEMENTS, CORRECTIONS OR ADJUSTMENTS TO OUR PHYSICAL AND ADMINISTRATIVE ENGINEERING CONTROLS. ALTHOUGH THE INVESTIGATION IS ONGOING, WE HAVE CHANGED OUR OPERATING PROCEDURE IN ORDER TO PREVENT A SIMILAR OCCURRENCE AND TO ASSURE SAFE OPERATIONS OF OUR SYSTEM UNTIL THE SCHEDULED PHYSICAL IMPROVEMENTS ARE COMPLETED. THE OPERATING PROCEDURE NOW IN PLACE DIRECTS THE WILLIAMS CONTROLLER(S) TO CLOSE A MANUALLY OPERATED GENERAL TWIN SEAL VALVE THAT WILL ISOLATE THE THIRD PARTY OPERATORS SYSTEM FROM THE WILLIAMS SYSTEM DURING THESE 'TIGHT LINING' OPERATIONS. ADDITIONALLY, IMPLEMENTATION AND TRAINING ASSOCIATED WITH THE NEW OPERATING PROCEDURE IS CURRENTLY UNDERWAY. WILLIAMS OVERPRESSURED BY THIRD PARTY AT OUR METER RUN: WILLIAMS MIDSTREREAM HAS INSTALLED OPP (SDV) AT THE 3RD PARTY INTERFACE AND IS NOT RELYING ON 3RD PARTY OPP."