COLUMBIA GAS TRANSMISSION, LLC

Incident Narrative

ON JULY 2, 2014, A MILLENNIUM COMPANY COMPRESSOR STATION (CS) LOCATED IN SULLIVAN COUNTY, NY WAS SUBJECT TO AN UN-INTENDED RELEASE OF NATURAL GAS (MATERIAL). THE CS IS HANCOCK, A TRANSMISSION FACILITY THAT IS OPERATED AND MAINTAINED BY COLUMBIA GAS TRANSMISSION, LLC. (COLUMBIA). IT WAS IDENTIFIED THAT THE CS EXPERIENCED AN EMERGENCY SHUTDOWN (ESD) AND BASED ON THE INVESTIGATIONS, THIS ESD WAS DUE TO LOW PNEUMATIC PRESSURE. EMERGENCY VALVES WERE FOUND PARTIALLY OPEN, LEADING TO AN UNINTENTIONAL RELEASE OF MATERIAL ADDING UP TO 8,038 MCF. THE ROOT CAUSE ANALYSIS INVESTIGATION REPORT IDENTIFIED THE PROBABLE CAUSE THAT TRIGGERED THE CHAIN OF EVENTS WHICH LED TO AN INCIDENT. RECOMMENDATIONS WERE INITIATED IN ORDER TO PREVENT THE SAME EVENTS FROM RE-OCCURRING IN THE FUTURE. THEY WERE; AN INTRODUCTION TO A LOW-LOW PNEUMATIC PRESSURE SWITCH (80 PSIG SET POINT) AND STATION PNEUMATIC PRESSURE TRANSMITTER HAS BEEN ADDED TO TRIGGER A STATION ESD ON THE LOSS OF STATION PNEUMATIC PRESSURE (IF THE PRESSURE DROPS BELOW 80 PSIG). THIS PROGRAMMING CHANGE WAS IMPLEMENTED ON JULY 2ND, 2014; A FEW HOURS AFTER THE INCIDENT TOOK PLACE. THEN, CONFIRMED PROPER OPERATION OF THE EMERGENCY BACK-UP GENERATOR TO SWITCH TO BACK-UP POWER ON LOSS OF COMMERCIAL POWER TO THE FACILITY. NOTE: INITIAL INCIDENT REPORT NO: 20140080-16463, SUBMITTED ON JULY 28, 2014