SOUTHERN NATURAL GAS CO — Gas transmission and gathering — incident on 2016-10-25

Gas transmission and gathering incident in Not Within a Municipality, CLARKE County, MS. Reported cause: EQUIPMENT FAILURE. Reported consequences: 0 fatalities, 0 injuries, 12781 NATURAL GAS released, $3,110 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: 20160091.

Operator ID: 18516.

Reported incident date: 10/25/2016 3:50.

Location detail: MILEPOST 67.2

Cause detail: MALFUNCTION OF CONTROL/RELIEF EQUIPMENT

Cause detail: 10/25/2016; 3:50 AM, EMPLOYEE WHO LIVES NEAR THE COMPRESSOR STATION, AWAKENED BY A NOISE, CALLED GAS CONTROL; EMPLOYEE LEARNS THERE IS AN ESD ALARM AND THE COMPRESSOR STATION IS RUNNING; EMPLOYEE LEAVES HOME TO CHECK THE COMPRESSOR STATION; WHILE IN ROUTE EMPLOYEE CALLS OTHER EMPLOYEES TO COME ASSIST AS NEEDED; EMPLOYEE ARRIVES AT COMPRESSOR STATION AT 3:58 AM AND FINDS ENGINES RUNNING AND THREE STATION YARD BLOW-OFFS VENTING; 4:03 AM GAS CONTROL CONFIRMS OTHER EMPLOYEES ARE IN ROUTE; 4:05 AM ANOTHER EMPLOYEE ARRIVES AT COMPRESSOR STATION; 4:06 AM EMPLOYEES BEGIN TAKING COMPRESSOR ENGINES OFF-LINE; 4:07 AM AS THE FIRST ENGINE WAS BEING TAKEN OFF-LINE, ALL REMAINING ENGINES WERE IMMEDIATELY SHUT DOWN BY THE STATION CONTROL SYSTEM; WITH ALL ENGINES SHUT DOWN, EMPLOYEES BEGIN TO ADJUST VALVES AS NEEDED TO BYPASS STATION; IN DOING SO EMPLOYEES NOTICE TWO 8-INCH STATION YARD BLOW-OFFS HAD STOPPED VENTING; EMPLOYEES FOUND MAIN LINE VALVES IN THE STATION YARD HAD PROPERLY OPENED FOR STATION BYPASS DURING THE EVENT AND NEEDED NO INTERVENTION; 4:25 AM EMPLOYEES CLOSED STATION VALVES WHICH CEASED THE GAS SUPPLY TO A 4-INCH STATION YARD BLOW-OFF; AT THIS TIME, EMPLOYEES THOUGHT THE GAS RELEASE WAS BELOW 3,000 MCF; AS PERSONNEL BECAME AVAILABLE TO CONSULT, MANAGERS DISCUSSED THE EVENT AND DETERMINED THE GAS RELEASE COULD BE A REPORTABLE VOLUME AND BEGAN CONTACTING OTHERS FOR INFORMATION AND REPORTING PURPOSES; 6:29 AM NRC TELEPHONE NOTIFICATION; DURING AND AFTER THE EVENT, CLARKE COUNTY, MISSISSIPPI EMA EMPLOYEES CONTACTED SNG EMPLOYEES CONCERNING THE EVENT AS THEY HAD RECENT TRAINING WITH A SNG EMPLOYEE; THE COMPRESSOR STATION RETURNED TO SERVICE 10/25/2016, 6:30 AM; INVESTIGATION LED TO THE INSTALLATION OF REBUILD KITS IN THE PILOT VALVE AND MANUAL SELECTOR BLOCK OF A CONTROL VALVE OPERATOR AS A SMALL LEAK IN EITHER COMPONENT WOULD HAVE CAUSED THE EVENT; REPAIR ALSO INCLUDED REPLACEMENT OF SAID VALVE OPERATOR'S ESD SWITCH.

PHMSA trend classification: not significant, not serious.

PHMSA standardized cause: EQUIPMENT FAILURE — MALFUNCTION OF CONTROL/RELIEF EQUIPMENT.

PHMSA indexed costs: $40,735 reported total cost, $40,925.749 in 1984 dollars, $52,898.62 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.