TALLGRASS PONY EXPRESS PIPELINE, LLC

Incident Narrative

PRIOR TO THE OVERFILL EVENT AT CUSHING STATION THE TALLGRASS OPERATING CONTROL CENTER (OCC) HAD BEEN MAKING A DELIVERY TO SEPARATE STATIONS DURING WHICH A SPLIT FLOW OPERATION WAS IN PLACE FOR PONCA CITY CUSTOMER TO RECEIVE A CERTAIN RATE AND CUSHING STATION WOULD RECEIVE THE REMAINING BALANCE OF TOTAL FLOW COMING FROM STERLING. AS FLOW WAS TRANSFERRED FROM THE PONCA CITY STATION TO CUSHING STATION, AFTER DELIVERY WAS MADE AT PONCA CITY, THE IMPOSED FLOW LIMIT AT CUSHING STATION WAS NOT IMMEDIATELY CLEARED BY THE OPERATOR CAUSING PRESSURE TO RISE UNEXPECTEDLY. THE UNEXPECTED PRESSURE RISE DUE TO THE INCREASED FLOW ACTUATED THE THERMAL RELIEF VALVES AT THE STATION AND OIL FLOWED TO THE SUMP TANK AS DESIGNED. THE LEVEL TRANSMITTER OF THE CUSHING STATION SUMP TANK HAD BEEN DISCONNECTED DUE TO NUISANCE ALARMS THEREFORE THE OCC COULD NOT SEE THE LIQUID LEVEL IN THE TANK INCREASING RESULTING IN IT OVERFILLING. THE OVERFILLED TANK WAS PROMPTLY IDENTIFIED BY ON SITE PERSONNEL WHO NOTICED OIL ON THE GROUND. SUPPLEMENTAL REPORT SUBMITTED IN ORDER TO CLARIFY THAT THE ACCIDENT WAS DUE TO A FAILURE TO FOLLOW PROCEDURE. THIS HAS BEEN ADDRESSED IN PART G7.