COLUMBIA GAS TRANSMISSION, LLC

Incident Narrative

ON MARCH 10TH, 2018, AN UNINTENDED RELEASE OF NATURAL GAS (MATERIAL) EVENT INTO ATMOSPHERE WAS REPORTED TO THE NATIONAL RESPONSE CENTER (NRC). THIS EVENT TOOK PLACE AT EAGLE COMPRESSOR STATION (CS) FACILITY IN CHESTER COUNTY, PENNSYLVANIA. THIS CS IS CLASSIFIED AS TRANSMISSION WHERE IT IS OPERATED AND MAINTAINED BY COLUMBIA GAS TRANSMISSION, LLC (COLUMBIA). AT 19:25 E.S.T., EAGLE CS HAD ANEMERGENCY SHUTDOWN (ESD) WHICH WAS SUBJECT TO THE FAILURE OF ALL THE STATION FIRE VALVES TO CLOSE. ALL TIMES WERE RECORDED IN EASTERN STANDARD TIME. THE CAUSE OF THE CS ESD WAS THE RESULT OF A COOLING SYSTEM ISSUE ON UNIT 2 AT THE STATION. AT APPROXIMATELY AT 18:52 UNIT 2 HAD A HYDRAULIC PUMP COUPLING FAIL WHICH CAUSED THE ENGINE TO BEGIN TO OVERHEAT. AT APPROXIMATELY AT 19:11 THE UNIT HAD SHUT DOWN ON A HIGH COOLING WATER OUTLET TEMPERATURE WHEN ENGINE OUTLET TEMPERATURE REACHED 200 DEGREES F. THE TEMPERATURE ON THE UNIT CONTINUED TO INCREASE TO A MAXIMUM RECORDED TEMP OF 216 DEGREES F ON THE WATER OUTLET TRANSMITTER AND THE COOLANT EXPANDED AND OVERFLOWED FROM THE COOLING SYSTEM EXPANSION TANK ON TO THE COMPRESSOR BUILDING FLOOR INTO THE BASEMENT OF THE COMPRESSOR BUILDING NEAR UNIT 2. THE WATER/ALCOHOL COOLANT WHICH OVERFLOWED INTO THE BASEMENT WAS DETECTED AS A POTENTIAL FLAMMABLE GAS LEAK BY THE BASEMENT GAS DETECTION SYSTEM RIGHT BELOW UNIT NO. 2 AND THE GAS DETECTION SHUTDOWN ALL UNITS AT THE STATION. ONCE THE GAS DETECTION REACHED A LEVEL OF GREATER THAN 50% LOWER EXPLOSIVE LEVEL, THE GAS DETECTION INITIATED AN ESD OF THE STATION TO EVACUATE THE GAS FROM THE DETECTED RELEASE OF MATERIAL IN THE COMPRESSOR BUILDING. THERE WAS A REPORTABLE RELEASE OF MATERIAL FROM THE STATION AS A RESULT OF BLOWDOWN VALVES C54-66, AND C54-61 OPENING AND THE CORRESPONDING EMERGENCY VALVES FAILURE TO CLOSE IN ORDER TO ISOLATE STATION FROM THE PIPELINE. APPROXIMATELY 19:42., OPERATIONS PERSONNEL ARRIVED ON SITE, WHERE THE UNINTENDED RELEASE OF MATERIAL WAS ISOLATED AND THE AREA WAS SECURED SAFELY. A 48-HR UPDATE NOTICE WAS CALLED-IN TO THE NRC, WHERE THE UPDATE REPORT NO. WAS 1206574. IN ORDER TO PREVENT ANY FUTURE EVENTS FROM SIMILAR RECURRENCE, THE IDENTIFIED KEY RECOMMENDED CHANGES TO EAGLE CS FACILITY WERE: 1. UNIT COOLING SYSTEM HIGH TEMP ALARM/SHUTDOWN SETPOINTS LOWER TO AVOID ANOTHER UPSET OR BOIL-OVER CONDITION. THE OVERFLOWS FROM EXPANSION TANKS WERE PLUMBED TO 55 GALLON DRUMS OUTSIDE OF THE COMPRESSOR BUILDING. 2. DURING THE NEXT ANNUAL ESD SYSTEM TEST, THE ESD PNEUMATIC SYSTEM WILL BE PURGED WITH CLEAN DRY AIR. KEY COMPONENTS OF ESD PNEUMATIC PANEL TO BE INSPECTED, CHECKED FOR CONTAMINATION AND CLEANED THEN TESTED BEFORE RETURNING THEM INTO SERVICE. SIMILARLY, THE INDIVIDUAL EMERGENCY BLOWDOWN, ESD VERSA VALVES WILL BE CLEANED, INSPECTED, OR FULL FUNCTIONALITY BEFORE RETURNING THEM BACK INTO SERVICE. 3. THE ESD SYSTEM SOLENOID VALVE OPERATION DID NOT OPERATE AS DESIGNED WHICH WAS MOST LIKELY DUE TO MOISTURE/ICE IN THE VALVE. ADDITIONAL INSPECTIONS ARE RECOMMENDED TO BE IMPLEMENTED TO THE PNEUMATIC SYSTEM IN ORDER TO ENSURE FREE LINES OF MOISTURE.