ENABLE GAS TRANSMISSION, LLC

Incident Narrative

DURING THE 06:00 SHIFT CHANGE ON 11/22/17, ENABLE GAS TRANSMISSION SYSTEM CONTROL BECAME AWARE OF AN UNUSUAL SITUATION WITH LINE OM-1. SYSTEM CONTROL DID NOT RECEIVE ANY ALERTS, SAFETY RELATED ALARMS, OR RATE OF CHANGE ALARMS TO NOTIFY THEM OF THE SITUATION BUT DID NOTICE AN INCREASE IN FLOW RATE INTO LINE OM-1 AND A DECREASE IN DISCHARGE PRESSURE AT DUNN STATION. SYSTEM CONTROL IMMEDIATELY DISPATCHED FIELD TECHNICIANS TO SURVEY LINE OM-1 TO INVESTIGATE THE SITUATION. AT APPROXIMATELY 06:44, A 911 OPERATOR CONTACTED SYSTEM CONTROL TO REPORT A LOUD NOISE, AND POSSIBLE GAS LEAK, NEAR HWY 90 NEAR NOEL, MISSOURI. AT 07:21, AN ENABLE FIELD TECHNICIAN DISCOVERED A BLOWDOWN VALVE RELEASING NATURAL GAS TO ATMOSPHERE AT THE JANE COMPRESSOR STATION. AFTER THE STATION WAS SECURED, SCADA DATA WAS CHECKED AND BY 08:01 THE ISSUE HAD BEEN CORRECTED. UPON INVESTIGATION, A VERSA VALVE ACTUATOR FOR THE BLOWDOWN VALVE FAILED OPEN DUE TO A LEAK IN THE PILOT TUBING. THE LOOSE FITTING WAS TIGHTENED ELIMINATING THE LEAK. THE REMAINING VALVE FITTINGS WERE CHECKED AT THE STATION FOR TIGHTNESS. ON THE MORNING OF 11/22/17 ENABLE MIDSTREAM REPORTED A POTENTIAL RELEASE TO THE NRC (NRC #1197895 07:13), AND FOLLOWED UP LATER WITH A LOCATION AND QUANTITY CHANGE (NRC# 1197919 12:17). THE 48 HOUR FOLLOW UP CALL WAS PLACED ON 11/24/17 (NRC# 1197992 07:10).