EL PASO NATURAL GAS CO — Gas transmission and gathering — incident on 2016-08-03

Gas transmission and gathering incident in WENDEN, LA PAZ County, AZ. Reported cause: EQUIPMENT FAILURE. Reported consequences: 0 fatalities, 0 injuries, 23540 NATURAL GAS released, $11,200 reported property damage. Operator-reported incident data submitted to PHMSA, generally within 30 days. Records may be supplemented or corrected and do not represent final agency causal findings.

Report number: 20160071.

Operator ID: 4280.

Reported incident date: 8/3/2016 22:15.

Location detail: MP 37+5084.14

Cause detail: COMPRESSOR OR COMPRESSOR-RELATED EQUIPMENT

Cause detail: 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.

PHMSA trend classification: significant incident, not serious.

PHMSA standardized cause: EQUIPMENT FAILURE — PUMP/COMPRESSOR OR PUMP/COMPRESSOR-RELATED EQUIPMENT.

PHMSA indexed costs: $80,591 reported total cost, $79,452.398 in 1984 dollars, $104,436.635 in current-year dollars.

PHMSA trend flags, standardized causes, and indexed costs are analytical fields added to operator-reported incident data. They do not represent final agency causal findings.