COLONIAL PIPELINE CO

Incident Narrative

AT APPROXIMATELY 14:05, THE CONTROL CENTER RECEIVED A POWER FAILURE ALARM FROM VANCE STATION AND AT 14:06 RECEIVED A POWER FAILURE ALARM FROM PELHAM STATION. IN RESPONSE TO THE PRESSURE TRANSIENTS ON THE LINE, THE CONTROLLER BEGAN THE PROCESS OF SHUTTING DOWN. THE RELIEF SYSTEM ACTIVATED AT VANCE STATION AT 14:05 WHEN THE POWER FAILURE OCCURRED. AT 14:07, THE CONTROL CENTER RECEIVED A HIGH TANK ALARM AND AT 14:11 THE MAX TANK ALARM WAS RECEIVED. AT APPROXIMATELY 1412, TECHNICIANS WORKING AT VANCE STATION OBSERVED PRODUCT FLOWING FROM THE ROOF VENTS ON RELIEF TANK 5076. THEY IMMEDIATELY NOTIFIED THE CONTROL CENTER. AT 14:13, THE LINE PRESSURE WAS REDUCED ENOUGH TO ALLOW THE RELIEF ISOLATION VALVE TO BE CLOSED. THE OM, DO AND DEM WERE THEN NOTIFIED. AT 15:15, ADEM WAS NOTIFIED (RPT#17986) AND AT 15:40 THE NRC WAS NOTIFIED (RPT#1263763). CLEAN UP EFFORTS BEGAN IMMEDIATELY AND IS ONGOING. IT IS ESTIMATED THAT 277 BARRELS OF PRODUCT WAS RELEASED AND TO DATE APPROXIMATELY 210 BARRELS HAVE BEEN RECOVERED. THE INCIDENT ANALYSIS HAS IDENTIFIED THE RELEASE WAS CAUSED BY A LINE PRESSURE SURGE THAT RESULTED IN RELIEF THAT EXCEEDED THE CAPACITY OF THE RELIEF TANK. THE ELECTRICAL FAILURE CAUSED THE ""TIME OVER CURRENT"" PROTECTIVE RELAY TRIP. THE CONTROL VALVE AT PELHAM DID NOT OPEN AFTER SUCTION PRESSURE CONDITIONS WERE MET. EVIDENCE SUGGESTS THE CALCULATIONS USED TO DETERMINE THE SET POINTS FOR THE T35 PROTECTIVE RELAYS, INCLUDING THIS ONE AT PELHAM, WERE NOT CORRECT. COMPANY STANDARDS, PROCESSES, AND TRAINING HAVE BEEN REVIEWED AND UPDATED. UPDATE: DURING THE RESPONSE AND REMEDIAL EFFORT 9,563 GALLONS OF FREE PRODUCT WAS RECOVERED. ADDITIONALLY 4 GALLONS WERE CALCULATED TO BE CONTAINED IN THE 514 TONS OF EXCAVATED SOIL. TOTAL RECOVERY VOLUME IS 9567 GALLONS OR 228 BBLS. 10/23/2024 - UPDATED BY PHMSA PER OPERATOR APPROVAL.