CONSUMERS ENERGY CO

Incident Narrative

ON AUGUST 24, 2017 AT APPROXIMATELY 13:27 THE CONSUMERS ENERGY ST. CLAIR COMPRESSOR STATION PLANT 3 BLOW-DOWN SILENCER IGNITED. THE ST. CLAIR COMPRESSOR STATION IS LOCATED IN IRA TOWNSHIP (ST. CLAIR COUNTY) MICHIGAN. SHORTLY AFTER THE IGNITION, THE STATION WAS FIRE GATED. THE SITE WAS EVACUATED AND ALL SITE PERSONNEL WERE ACCOUNTED FOR.THERE WERE NO INJURIES THAT OCCURRED AS A RESULT OF THE IGNITION. AN INTERNAL TEAM WAS ASSEMBLED TO COMPLETE A ROOT CAUSE INVESTIGATION. THE INVESTIGATION BEGAN ON AUGUST 25, 2017 AND INCLUDED DEVELOPMENT OF THE SEQUENCE OF EVENTS, REVIEW OF THE SCENE, AND CONTRACTING WITH EXPONENT (THIRD PARTY CONSULTANT) TO COMPLETE AN EVALUATION OF VARIOUS IGNITION SCENARIOS. THE INVESTIGATION WAS COMPLETED AND THE CAUSE OF IGNITION WAS DUE TO ELECTROSTATIC DISCHARGE FROM ENTRAINED WATER DROPLETS IN THE GAS MIXTURE. SHORT TERM ACTIONS TO PREVENT RE-OCCURRENCE INCLUDE DRAINING WATER FROM ALL STATION BLOW DOWN SILENCERS WEEKLY. LONG TERM ACTIONS TO PREVENT RE-OCCURRENCE ARE BEING EVALUATED. FOLLOWING THE INCIDENT INVESTIGATION AND REMEDIAL ACTIVITIES, PLANT 1 WAS PLACED BACK INTO SERVICE AND NORMAL OPERATION RESUMED ON OCTOBER 13, 2018. ADDITIONAL ASSESSMENT OF THE SILENCERS AND THE VENT PIPING TO THE SILENCERS FOR PLANTS 3 AND 4, WHICH WERE UNDERGOING START-UP AND TESTING ACTIVITIES AT THE TIME THE INCIDENT OCCURRED, WERE COMPLETED TO CONFIRM THE INTEGRITY OF THE EQUIPMENT BEFORE INTRODUCING GAS INTO THE SYSTEM. ALL CORRECTIVE ACTIVITIES WERE COMPLETED AND PLANTS 3 AND 4 WERE PLACED IN-SERVICE IN APRIL 2018.