EL PASO NATURAL GAS CO

Incident Narrative

ON AUGUST 3, 2016 AT APPROXIMATELY 10:15 P.M. LOCAL TIME (MT), EL PASO NATURAL GAS (EPNG) GAS-CONTROL NOTIFIED A PHOENIX BASED EPNG TECHNICIAN THAT THERE WAS A COMPRESSOR UNIT SHUTDOWN AT THE ALAMO LAKE STATION. AFTER CONFIRMING THE SHUTDOWN REMOTELY, THE TECHNICIAN DROVE TO THE SITE AND FOUND THAT THE COMPRESSOR UNITS WERE NOT RUNNING, THE STATION SUCTION VALVE WAS OPEN AND THE SUCTION-VENT-VALVE WAS OPEN AND VENTING GAS. THE STATION DISCHARGE AND VENT VALVES WERE CLOSED. THE TECHNICIAN CLOSED THE STATION SUCTION VALVES, STOPPING THE VENTING OF GAS, AND PROCEEDED TO CHECK THE STATUS OF THE COMPRESSOR STATION. AFTER REVIEWING THE STATUS, THE COMPRESSORS WERE RESTARTED AND THE TECHNICIAN REMAINED AT THE STATION FOR A COUPLE MORE HOURS TO MONITOR THE STATION. THE QUANTITY OF GAS LOSS WAS NOT DETERMINED BY THE TECHNICIAN DURING THE AUGUST 3, 2016 EVENT. ON AUGUST 4, 2016 AN INVESTIGATION OF THE CAUSE OF THE STATION SHUTDOWN FOUND THAT THERE WERE TWO EQUIPMENT ISSUES. THE STATION'S SUCTION-VENT-VALVE HAD A SHORTED CLOSE-SOLENOID AND THE MOMENTARY-CLOSE PUSH-BUTTON THAT OPENS THE STATION SUCTION VALVE WAS STUCK CLOSED. BOTH OF THESE COMPONENTS WERE REPAIRED AND THE COMPRESSOR UNITS AT THE STATION RETURNED TO SERVICE. ON AUGUST 10, 2016, DURING THE EVALUATION OF GAS LOSS EVENTS IN THE AREA, EPNG PHOENIX AREA OPERATIONS MANAGEMENT BECAME AWARE THAT THE QUANTITY OF GAS RELEASED FOR THIS EVENT MET THE REPORTING CRITERIA FOR AN INCIDENT, UNINTENTIONAL GAS LOSS GREATER THAN 3000MCF, UNDER 49 CFR 191.5 AT WHICH TIME THE NRC WAS NOTIFIED IMMEDIATELY. IMMEDIATELY AFTER THE NRC REPORT WAS SUBMITTED, EPNG ALSO NOTIFIED THE PHMSA WESTERN REGION AND THE ARIZONA CORPORATION COMMISSION PIPELINE SAFETY DIVISION. FURTHER INVESTIGATION DETERMINED THAT THE CAUSE OF THE UNINTENTIONAL GAS RELEASE WAS AT LEAST TWO LOW-RESISTANCE TO GROUND FAULTS ON THE STATIONS 135 VDC CONTROL SYSTEM. BASED ON THIS FINDING, THE FIELD WIRING FOR BOTH THE STATION'S HIGH DISCHARGE PRESSURE SWITCH CIRCUIT AND THE STATION'S DISCHARGE LOADING VALVE CIRCUIT WILL BE REPLACED AS SOON AS POSSIBLE AND THE REMAINDER OF THE STATION'S DC SYSTEM WILL BE EVALUATED FOR ADDITIONAL LOW-RESISTANCE GROUND AND/OR DETERIORATION. UPDATE: COST TO HYDRO-VAC AND INSTALL A NEW CONDUIT LINE = $11,200.