CONSUMERS ENERGY CO

Incident Narrative

ON JANUARY 30, 2019 AT APPROXIMATELY 10:23 A.M., CONSUMERS ENERGY'S (CE) RAY COMPRESSOR STATION PLANT 3 DETECTED AN ABNORMAL OPERATING CONDITION IN THE DET-TRONICS CONTROL SYSTEM. AS PART OF THE EMERGENCY SAFETY FIRE-GATE PROCESS, THE PLANT RELEASED NATURAL GAS INTO THE ATMOSPHERE THROUGH PLANT 3 BLOWDOWN SILENCERS. THE NATURAL GAS RELEASED FROM THE FIRE-GATE EVENT MIGRATED IN A NORTHEAST DIRECTION OVER THE PLANT 2 PROCESSING EQUIPMENT AS A RESULT OF THE WIND CONDITIONS OCCURRING AT THE TIME OF THE EVENT. AT APPROXIMATELY 10:25 A.M., A GAS PLUME IGNITED FROM THE PLANT 3 BLOWDOWN SILENCERS (SUCTION AND DISCHARGE). THE PLANT 2 THERMAL OXIDIZER'S 1506 DEGREES F EXHAUST STREAM AUTO-IGNITED THE PLANT 3 FIRE-GATE GAS PLUME. PERSONNEL AT THE RAY PLANT MANUALLY FIRE-GATED PLANT 1 AND PLANT 2, AS PART OF OUR STANDARD SAFETY PROTOCOLS, AT 10:27:58 A.M. AND 10:28:22 A.M., RESPECTIVELY. AT 10:28:48 A.M., THERE WAS A SECOND IGNITION AT THE PLANT 2 VENT STACK, WHICH IS LOCATED NEXT TO PLANT 3'S BLOWDOWN SILENCERS AND IS THE LOCATION WHERE THE NATURAL GAS IS RELEASED FOR PLANT 2. THE ARMANDA TOWNSHIP FIRE DEPARTMENT WAS NOTIFIED AT 10:29 A.M. AND ARRIVED ONSITE AT 10:38. THE EMERGENCY RESPONDERS REMAINED AT THE SITE UNTIL ALL THE NATURAL GAS WAS VENTED FROM THE PIPING TO ADDRESS REMAINING FIRE AND HOTSPOTS. A ROOT CAUSE ANALYSIS (RCA) TEAM WAS ASSEMBLED AND MET ON SITE FEBRUARY 2, 2019 TO IDENTIFY THE IGNITION SOURCE INITIATING THE FIRE AT THE RAY COMPRESSOR STATION PLANT 3 BLOW DOWN SILENCERS AND DEFINE HOW TO CONTROL AND PREVENT RE-OCCURRENCE. (REFER TO MPSC STAFF' INVESTIGATION REPORT APPENDIX A) FURTHER INVESTIGATION INTO THE DET-TRONICS FAILURE LEADING TO THE FIREGATE ACTIVATION REVEALED THAT A GROUNDING FAULT WAS THE UNDERLYING CAUSE OF THE INITIAL FIREGATE EVENT. WHEN THE STATION'S [DOMESTIC WATER] WELL PUMP STARTED UP, ITS VARIABLE FREQUENCY DRIVE CAUSED A VOLTAGE SPIKE IN THE GROUNDING SYSTEM OF THE DET-TRONICS PANEL LOCATED IN THE HEADQUARTERS BUILDING. THESE HIGH VOLTAGES CAUSED ENHANCED DISCRETE INPUT/OUTPUT (EDIO) AND ANALOG INPUT MODULE (AIM) TO LOSE COMMUNICATION WITH THE DET-TRONICS PILOT AIR SYSTEM, A FAULT WHICH TRIGGERED THE INITIAL FIREGATE. TO ELIMINATE THE GROUNDING VOLTAGE INTO THE DET-TRONICS SYSTEM, THE WELL PUMP PRESSURE SWITCH AND PRESSURE TRANSMITTER WERE RELOCATED TO THE EAST SIDE OF THE PLANT 3 AUXILIARY BUILDING. THE RISK OF A COMMUNICATIONS BREAK-DOWN BETWEEN THE PILOT AIR SYSTEM AND ITS MODULES HAS BEEN MITIGATED BY RELOCATING THE MODULES FROM THE HEADQUARTERS BUILDING TO THE PLANT 3 AUXILIARY BUILDING. RESTORATION AND RECOVERY ACTIVITIES HAVE BEEN OUTLINED THE CONSUMERS ENERGY COMPANY'S RAY NATURAL GAS COMPRESSOR STATION STORAGE FIELD INJECTION TIMELINE AND FACILITY REPAIR UPDATE TIMELINE & FACILITY REPAIR UPDATE (REFER TO MPSC STAFF INVESTIGATION REPORT APPENDIX M) FOLLOWING RESTORATION ACTIONS, NORMAL OPERATIONS TO THE CONSUMERS ENERGY RAY COMPRESSOR STATION WAS RESUMED ON DECEMBER 30, 2019.