NORTHWEST PIPELINE LLC

Incident Narrative

THURSDAY MARCH 28TH TWO WILLIAMS INTEGRITY SPECIALISTS DISCOVERED A GAS LEAK AROUND THE ALBERTSONS METER STATION LOOP LINE TAP VALVE. THIS OCCURRED JUST BEFORE 1400 MOUNTAIN TIME. DURING THIS CONVERSATION IT WAS COMMUNICATED THAT LEVELS GREATER THAN 10% LEL WERE BEING MEASURED ON THE COUNTY ROAD ADJACENT TO THE FACILITY. THE EMPLOYEES WERE DIRECTED TO SECURE THE ROAD AT A SAFE DISTANCE AND CONTINUE TO MONITOR LEL LEVELS. AT 1404 FROM THAT INITIAL PHONE CALL THE DISTRICT LEADERSHIP MADE NOTIFICATION TO GAS CONTROL AND INTERMOUNTAIN GAS (IMG) OUR LOCAL LDC. GAS CONTROL ALSO TOOK THE LEAD TO INTERFACE WITH THE SOC. DISTRICT LEADERSHIP DISPATCHED TO THE SITE TO ESTABLISH AN INCIDENT COMMAND IF NEEDED. SITE ASSESSMENTS DETERMINED THE LOOP LINE TAP VALVE WAS THE PROBABLE CAUSE. THIS IS A 4' WELD BY FLANGE VALVE BURIED BELOW GRADE AT OR ABOUT 6 FEET. WITH CLOSE COORDINATION AND COMMUNICATION WITH INTERMOUNTAIN GAS ON SITE, IT WAS DETERMINED NEITHER NWP NOR IMG COULD ISOLATE THE FACILITY WITH CURRENT SYSTEM DEMAND. THIS DECISION POINT OCCURRED LATE IN THE DAY WHICH DROVE FURTHER STEPS TO SECURE THE ROAD LONG TERM AND COMMUNICATE THE ACTIVITY TO LOCAL PROPERTY OWNERS. A 24 HOUR SCHEDULE WAS STAFFED FOR CONTINUES MONITORING AND ON SITE RESPONSE IF NEEDED, ALONG WITH DIRECT LINES OF COMMUNICATION WITH GAS CONTROL. FRIDAY MARCH 1ST WITH WORK PLANS AND SSMP'S IN PLACE EXCAVATION AND CONSTRUCTION COMMENCED WITH THE INSTALLATION OF A THREAD-O-RING FITTING TO FACILITATE A TEMPORARY BYPASS TO MAINTAIN SYSTEM THROUGHPUT FOR IMG. SATURDAY MARCH 2ND WITH THE SUPPORT OF POCATELLO DISTRICT, GAS CONTROL, OTS, AND MATERIALS MANAGEMENT A TEMPORARY BYPASS WAS FABRICATED AND TESTED. SUNDAY MARCH 3RD AT 1116 THE BYPASS WAS PLACED IN SERVICE WITH CONTINUOUS MONITORING BY BOTH NWP AND IMG OPERATIONS PERSONNEL. EXCAVATION THEN BEGAN ON THE LOOP LINE TO EXPOSE THE SUSPECTED LEAKING FITTING. IT WAS CONFIRMED THAT A BLOWN INSULATING GASKET WAS THE CAUSE. THE GASKET WAS REPLACED WITH A FLEXITALLIC GASKET IN PLACE OF THE INSULATING FLANGE GASKET. THE LINE WAS THEN CHECKED FOR LEAKS. AT 1930 ALBERTSONS METER STATION WAS RETURNED TO SERVICE, BYPASS LINE BLOWN DOWN AND SECURED.