COLUMBIA GAS TRANSMISSION, LLC

Incident Narrative

ON APRIL 14, 2016, WHILE A CONTRACTOR WAS PREPARING A STOPPLE FOR REMOVAL AFTER SUCCESSFULLY COMPLETING AN IN-LINE INSPECTION (ILI) RUN, THE STOPPLE PLUG FAILED LEADING TO AN UNINTENDED RELEASE OF NATURAL GAS (MATERIAL) INTO ATMOSPHERE. THE MATERIAL RELEASE WAS RECORDED AT 13:32 EASTERN STANDARD TIME (EST) ON LINE KA-1-N NEAR THE TOWN OF RICHMOND, MADISON COUNTY, KENTUCKY. LINE KA-1-N IS A 12 INCH TRANSMISSION PIPELINE THAT IS OWNED, OPERATED AND MAINTAINED BY COLUMBIA GAS TRANSMISSION, LLC (COLUMBIA). LINE KA-1-N CRITICAL VALVES WERE MANUALLY OPERATED BY COLUMBIA OPERATIONS PERSONNEL TO ISOLATE THE AFFECTED SEGMENT TO ENSURE THAT THE AREA WAS SAFE. AFTER THE VERTICAL VALVES WERE FULLY CLOSED, THE MATERIAL STOPPED VENTING INTO ATMOSPHERE. AS A PRECAUTIONARY MEASURE, A NEARBY SHOP AND A BANK WERE TEMPORARILY EVACUATED. THE OCCUPANTS WERE CLEARED TO RETURN TO THEIR BUSINESSES AFTER THE AREA WAS MADE SAFE. AFTER IDENTIFYING THE PROBABLE CAUSE OF THIS UNINTENDED RELEASE (THE STOPPLE PLUG), THE STOPPLE WAS CUT AND REMOVED BY THE CONTRACTOR FOR FURTHER INVESTIGATIONS. THEREAFTER, A PRE-TESTED SECTION OF PIPE WAS INSTALLED, WELDED AND NON-DESTRUCTIVELY TESTED, AFTER WHICH THE LINE WAS RETURNED BACK INTO SERVICE ON APRIL 15, 2016, AT 03:00. COLUMBIA AND THE CONTRACTOR CONDUCTED INDEPENDENT INVESTIGATION TO IDENTIFY THE ROOT CAUSE BEHIND THE STOPPLE PLUG FAILURE. THE INVESTIGATION CONCLUDED THAT THE CAUSE WAS DUE TO EQUIPMENT FAILURE.