COLUMBIA GAS TRANSMISSION CORP

Incident Narrative

HURRICANE SANDY SIGNIFICANTLY IMPACTED THE WEST VIRGINIA MOUNTAINS ON THE EVENING OF OCTOBER 29, WITH LESSENING IMPACTS FOLLOWING. DAMAGE FROM THIS HEAVY, EARLY SEASON SNOWSTORM IN THE WEST VIRGINIA MOUNTAINS INCLUDED LOSS OF POWER AND COMMUNICATIONS FOR MUCH OF THE REGION. AMONG THE FACILITIES AFFECTED IN THE REGION WAS THE FLAT TOP COMPRESSOR STATION. AT THE TIME THE STORM HIT, THE COMPRESSOR STATION WAS UNATTENDED. WHEN THE COMMUNICATION LOSS WAS RECOGNIZED ON THE MORNING OF OCTOBER 30, AN EMPLOYEE WAS DISPATCHED TO THE LOCATION TO INVESTIGATE. THE EMPLOYEE ARRIVED AT THE STATION AT APPROXIMATELY 9:30 A.M. NOT LONG AFTER ARRIVAL, HE HEARD GAS VENTING. THIS WAS NOT UNUSUAL, AS THE TURBINE UNIT IS DESIGNED TO BLOW DOWN IF IT GOES OFFLINE AS HAD APPARENTLY HAPPENED. A SHORT WHILE LATER, AS THE EMPLOYEE CONTINUED TO RESTORE STATION OPERATION, HE RECOGNIZED THAT GAS WAS STILL VENTING. THIS WAS UNUSUAL, AS THE BLOWDOWN PROCESS SHOULD HAVE BEEN COMPLETE BY THEN, EVEN IF IT HAD BEGUN JUST PRIOR TO THE EMPLOYEE'S ARRIVAL. AFTER CAREFULLY ASSESSING THE SITUATION, THE EMPLOYEE MANUALLY CLOSED THE BLOWDOWN VALVE. FURTHER INVESTIGATION REVEALED THAT A PARTIAL ESD HAD OCCURRED DURING THE COMMUNICATION LOSS / POWER LOSS EVENT, AND THE BLOW DOWN VALVE HAD REMAINED IN THE OPEN POSITION. CORRECTIVE ACTIONS TAKEN ON 10-30-2012 1. THE STATION COMPRESSED AIR SYSTEM WAS RECHARGED USING THE EMERGENCY GASOLINE POWERED AIR COMPRESSOR. 2. THE UNIT SUCTION VALVE WAS MANUALLY CLOSED TO STOP GAS FROM VENTING. 3. THE EMERGENCY BACKUP GENERATOR WAS STARTED AND AC POWER RESTORED. 4. THE 24 VOLT ESD SHUNT TRIP BREAKER WAS RESET AND 24 VOLT DC POWER RESTORED. 5. THE STATION WAS RETURNED TO NORMAL OPERATIONAL STATUS WITH AC POWER BEING SUPPLIED BY THE EMERGENCY BACKUP GENERATOR. COLUMBIA'S ENGINEERING SERVICES COMPLETED AN INVESTIGATION WITH A RECOMMENDATION TO UPGRADE THE SUCTION VALVE ACTUATOR FROM ELECTRIC TO FAIL CLOSED PNEUMATIC.