EL PASO NATURAL GAS CO

Incident Narrative

ON AUGUST 4, 2016 AT APPROXIMATELY 8:30AM LOCAL TIME (MT), EL PASO NATURAL GAS (EPNG) PHOENIX BASED EPNG OPERATIONS SUPERVISOR RECEIVED A TEXT MESSAGE FROM THE STATIONS CONTROL SYSTEM OF A UNIT-SHUTDOWN ALARM AT THE ALAMO LAKE STATION. HE CONTACTED A WENDEN, AZ BASED TECHNICIAN TO CHECK ON THE ALARM. THE TECHNICIAN WAS ALREADY EN ROUTE TO THE ALAMO LAKE STATION TO CONDUCT ROUTINE MAINTENANCES AND WAS INSTRUCTED TO EVALUATE THE SITUATION AND RESTART THE COMPRESSORS. HE ARRIVED AT APPROXIMATELY 9:20AM MT AND FOUND THE COMPRESSORS OFF-LINE WITH BOTH THE SUCTION AND DISCHARGE VENT VALVES OPEN. THE TECHNICIAN CLOSED THE VALVES AND PROCEEDED TO INVESTIGATE THE CAUSE OF THE STATION SHUTDOWN. 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. THE QUANTITY OF GAS LOSS WAS NOT DETERMINED BY THE TECHNICIAN DURING THE AUGUST 4, 2016 EVENT. 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. COST FOR THE INSTALLATION WILL BE REFLECTED ON PHMSA REPORT NO: 20160071 (THIS INCIDENT, 20160070, AND 20160071 OCCURRED ON THE SAME FACILITY).