EL PASO NATURAL GAS CO

Incident Narrative

ON JANUARY 3, 2019, A FIRE EYE ALARM AT DILKON COMPRESSOR STATION RESULTED IN A STATION ESD. A NORMAL ESD OPERATION AT THIS FACILITY WOULD NOT HAVE MET THE DOT/PHMSA REPORTABLE RELEASE VOLUME OF 3,000 MCF. AT THE TIME OF THE ESD NO UNITS AT THE STATION WERE RUNNING AND THE STATION VALVES WERE OPEN. DURING THE ESD OPERATION GAS VENTED THROUGH A 4"" BRANCH CONNECTION THROUGH A VENT VALVE. AS PART OF OUR INVESTIGATION IT WAS DETERMINED THAT THE ACTUATOR ON THE STATION DISCHARGE VALVE DID NOT CLOSE COMPLETELY DUE TO LOW POWER GAS PRESSURE. THE INCOMPLETE VALVE CLOSURE IS WHAT CAUSED THE GAS TO VENT FOR A LONGER PERIOD OF TIME AND EVENTUALLY SURPASSED THE REPORTABLE QUANTITY OF 3,000 MCF. AT 18:13 KM TECHNICIAN WAS DISPATCHED TO THE SITE BY GAS CONTROL AND ARRIVED AT 19:06 WHERE HE VISUALLY DISCOVERED THE GAS VENTING AND CONFIRMED A FALSE FIRE ALARM. THE EMPLOYEE THEN PROCEEDED TO MANUALLY CLOSE THE DISCHARGE VALVE AT 19:20. AN ERL CALL WAS HELD AT 19:50 WHERE THE GAS LOSS WAS ESTIMATED TO EXCEED THE REPORTING THRESHOLD. CODES AND COMPLIANCE REPORTED THIS EVENT PRIOR TO THE 1 HOUR DEADLINE FROM CONFIRMED DISCOVERY. TOTAL GAS LOSS VOLUME WAS UNKNOWN AT THE TIME INCIDENT WAS INITIALLY REPORTED TO NRC, OPERATIONS CALCULATED THE GAS LOSS AT 10,404 MCF FOR THE 48HR NRC UPDATE. AS PART OF OUR INVESTIGATION AFTER FURTHER REVIEW BY KINDER MORGAN MEASUREMENT SME'S THE TOTAL GAS LOSS WAS CALCULATED AT 7,663 MCF. THE POWER GAS FOR THIS ACTUATOR COMES FROM A BURIED PRESSURE BOTTLE FED BY THE SUCTION SIDE OF THE PLANT DOWNSTREAM OF THE STATION SUCTION VALVE. NORMALLY THIS BURIED BOTTLE HAS PLENTY OF PRESSURE TO CLOSE ALL REQUIRED VALVES, BUT IN THE EVENING HOURS OF JANUARY 3RD THE MAINLINE HAD LOWER THAN NORMAL OPERATING PRESSURE. WHEN THE STATION EXPERIENCED AN ESD THE PRESSURE IN THE BOTTLE WAS NOT SUFFICIENT TO CLOSE THE STATION DISCHARGE VALVE. ON JANUARY 4TH EMPLOYEES RETURNED THE STATION TO SERVICE AT 07:22, INCLUDING RESTORING PRESSURE TO THE UNDERGROUND ESD STORAGE BOTTLE BY 07:45, CLEARED THE ESD ALARMS, AND TESTED THE VALVE ACTUATOR WHICH WORKED AS DESIGNED AND HAD APPROPRIATED GAS PRESSURE TO OPERATE.