NORTHWEST PIPELINE LLC — Gas transmission and gathering — incident on 2017-03-31

Gas transmission and gathering incident in KEMMERER, LINCOLN County, WY. Reported cause: EQUIPMENT FAILURE. Reported consequences: 0 fatalities, 0 injuries, 6394 NATURAL GAS released, $262,150 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: 20170034.

Operator ID: 13845.

Reported incident date: 3/31/2017 2:59.

Location detail: 51.17

Cause detail: NON-THREADED CONNECTION FAILURE

Cause detail: GAS CONTROL CALLED KEMMERER/MOXA DISTRICT TEAM LEAD AT 0835 ON MARCH 31, 2017 TO INFORM THAT THERE WAS A HIGH BOARD TEMPERATURE OF THE ROC CONTROLLER AT THE N2 SITE. THE GAS CONTROLLER FURTHER INFORMED THE TEAM LEAD THAT THE DOWNSTREAM PRESSURE TRANSMITTER WAS READING A -250 VALUE. THE TEAM LEAD IMMEDIATELY INSTRUCTED A TECHNICIAN TO GO TO THE N2 SITE TO INVESTIGATE THE ISSUE. ONCE THE TECHNICIAN ARRIVED CLOSE ENOUGH (APPROXIMATELY 1 MILE AWAY) TO SEE THE N2 SITE AT 0927 ON MARCH 31, 2017 THE TECHNICIAN NOTICED THAT ONE OF THE STRUCTURES AT THE N2 SITE WAS ON FIRE. THE TECHNICIAN IMMEDIATELY CALLED THE TEAM LEAD TO INFORM OF THE ISSUE. THE TEAM LEAD CALLED THE KEMMERER/MOXA DISTRICT MANAGER TO INFORM HIM OF THE FINDINGS. THE TEAM LEAD FURTHER INFORMED THE DISTRICT MANAGER THAT THE DISTRICT IS IN THE PROCESS OF ISOLATING THE SECTIONS OF THE PIPELINE TO ISOLATE THE GAS LEAK AND FIRE. FURTHER DISCUSSION WAS MADE IN REFERENCE THAT NOBODY WAS GOING TO GO DOWN TO THE N2 SITE UNTIL IT WAS MADE SAFE. THE DISTRICT UTILIZED MANUAL AND AUTOMATED VALVES UPSTREAM AND DOWNSTREAM OF THE N2 SITE TO ISOLATE THE N2 SITE. THE TEAM LEAD INSTRUCTED DISTRICT TECHNICIANS WHICH VALVE SITE TO REPORT TO AND THAT THEY NEEDED TO STAY TOGETHER AS TWO MAN TEAMS. WITH THE HELP OF GAS CONTROL THE DISTRICT WAS ABLE TO ISOLATE AND BLOWDOWN THE 1400 MAINLINE FROM MUDDY CREEK C/S TO MAINLINE BLOCK VALVE 6-4. ALSO IN CONJUNCTION WITH THE MAINLINE BEING BLOWN DOWN THE DISTRICT WAS ABLE TO ISOLATE MAINLINE BLOCK VALVE 98-3 ON THE EAST PAINTER LATERAL. ISOLATION WAS COMPLETE AT 1030 ON MARCH 31, 2017. THE SITE WAS CONFIRMED SAFE TO ENTER AT 1700 ON MARCH 31, 2017. AT THE TIME OF THE INCIDENT WILLIAMS RECOMMENDED THAT NO ONE BE EVACUATED. LATER IT WAS FOUND THAT LOCAL ENFORCEMENT HAD NOTIFIED RESIDENTS ON WAGONWHEEL ROAD AND REQUESTED THEY EVACUATE THE AREA. IT WAS CONFIRMED THAT 3 INDIVIDUALS DID LEAVE THEIR HOME AND WENT INTO TOWN FOR A FEW HOURS. SITE INVESTIGATION REVEALED AN INITIAL FAILURE OF ONE OF THE GASKETS ON ONE OF THE 6" CONTROL VALVES IN THE ANALYZER BUILDING AS THE LEADING CAUSE OF THE GAS RELEASE. BASED ON AVAILABLE EVIDENCE, THE SOURCE OF IGNITION IS INCONCLUSIVE. THE FAILED GASKET WAS NOT A MATERIAL ORIGINALLY SPECIFIED IN THE SITE DESIGN. NOR WAS IT A SUITABLE SUBSTITUTE.

PHMSA trend classification: significant incident, not serious.

PHMSA standardized cause: EQUIPMENT FAILURE — NON-THREADED CONNECTION FAILURE.

PHMSA indexed costs: $306,853 reported total cost, $168,286.145 in 1984 dollars, $367,884.887 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.