CONSUMERS ENERGY CO

Incident Narrative

ON APRIL 4, 2023, AT APPROXIMATELY 15:21 HOURS, CONSUMERS ENERGY RECEIVED NOTIFICATION OF A POSSIBLE NATURAL GAS LEAK ON THE PIPELINE THAT CROSSES THE THORNAPPLE RIVER NEAR 7307 THORNAPPLE LAKE ROAD NASHVILLE, (BARRY COUNTY) MICHIGAN. A GAS SERVICE WORKER (GSW) WAS DISPATCHED AND ARRIVED ONSITE AT APPROXIMATELY 15:24 HOURS. THE GSW CONFIRMED A LEAK INDICATION AT THE THORNAPPLE RIVER CROSSING ON A 6-INCH HIGH-PRESSURE, STEEL, SINGLE-FEED PIPELINE SERVING OVER FOUR THOUSAND DOWNSTREAM CUSTOMERS. A GAS DISTRIBUTION SUPERVISOR WAS NOTIFIED AND ARRIVED ONSITE TO ASSIST WITH THE RESPONSE. DUE TO EXTREME FLOODING CONDITIONS AND MINIMAL REMAINING DAYLIGHT, AN INITIAL RESPONSE PLAN WAS IMPLEMENTED TO CONTINUOUSLY MONITOR THE LEAK LOCATION. A CONTINGENCY PLAN ALSO WAS PREPARED FOR IMMEDIATE CONTAINMENT USING EMERGENCY VALVES TO ISOLATE THE AFFECTED SEGMENT SHOULD THE CONDITION WORSEN DURING THE NIGHT. GAS OPERATIONS AND GAS ENGINEERING ALSO EVALUATED AND ASSESSED THE SITUATION IN DEVELOPING A LONG-TERM REMEDIATION PLAN. THE FOLLOWING DAY, AN INCIDENT COMMAND STRUCTURE (ICS) WAS ACTIVATED BECAUSE OF THE POTENTIAL IMPACT TO CUSTOMERS IN HASTINGS, MI. THE REMEDIATION PLAN WAS FINALIZED, AND IMPLEMENTATION WAS ALREADY UNDERWAY WHEN OPERATIONS PERSONNEL DISCOVERED THE LEAK WAS WORSENING AND DUE TO AN ANTICIPATED TEMPERATURE DECREASE SERVICE LOSS FOR CUSTOMERS WAS LIKELY TO OCCUR. CONSEQUENTLY, ADDITIONAL COMMUNICATION WAS UNDERTAKEN WITH KEY STAKEHOLDERS AND CUSTOMERS NOTIFYING THEM OF THE POTENTIAL INTERRUPTION IN NATURAL GAS SERVICE. A HIGH-PRESSURE BYPASS WAS INSTALLED TO ALLOW FOR FASTER RESTORATION OF NATURAL GAS SERVICE TO IMPACTED CUSTOMERS ONCE THE RELEASE WAS CONTAINED. ON APRIL 6, 2023, GAS WAS SHUT-OFF AT THE LEAK LOCATION BY INSTALLING PRESSURE CONTROL FITTINGS AT THE EAST AND WEST SIDES OF THE LOCATION. CONCURRENT TO THE PRESSURE CONTROL WORK, MULTIPLE GSW'S WERE TURNING OFF AFFECTED CUSTOMERS' SERVICE-LINE VALVE PRIOR TO ADMITTING GAS BACK INTO THE SYSTEM. THE BYPASS WAS ACTIVATED AT APPROXIMATELY 07:21 HOURS. PURGING FROM AIR TO GAS OF THE PIPELINE WAS PERFORMED IN STAGES PRIOR TO TURNING SERVICE-LINE VALVES AND RELIGHTING CUSTOMERS. CONSTRUCTION FOR PERMANENT PIPELINE REPLACEMENT WAS ALSO UNDER WAY DURING THIS TIME. CUSTOMER RESTORATION STARTED ON APRIL 7, 2023, AND AS OF THIS REPORT'S DATE, SERVICE HAS BEEN RESTORED TO ALL IMPACTED CUSTOMERS OR THEY RECEIVED NOTIFICATION REQUESTING ACCESS TO THEIR PROPERTIES FOR SERVICE RESTORATION. WEEKLY RESTORATION STATUSES ARE PROVIDED TO THE MICHIGAN PUBLIC SERVICE COMMISSION STAFF. THE PERMANENT PIPELINE REPLACEMENT REQUIRED INSTALLATION OF APPROXIMATELY ONE THOUSAND FEET OF 6-INCH HIGH-PRESSURE STEEL PIPELINE. THE PIPELINE REPLACEMENT WAS COMPLETED, AND NORMAL OPERATIONS RESUMED ON APRIL 11, 2023, AT APPROXIMATELY 19:50 HOURS. THE ROOT CAUSE INVESTIGATION IDENTIFIED THE FAILURE OF THE PIPELINE CROSSING THE THORNAPPLE RIVER WAS A RESULT OF OVERSTRESS INDUCED BY EXTERNAL FORCES DURING THE FLOODING EVENT. THE COMBINATION OF ACCELERATED WATER FLOW AND DEBRIS IN THE WATERWAY EXERTED SIGNIFICANT PRESSURE ON THE UNSECURED PIPELINE, LEADING TO AN INITIAL FRACTURE THAT ULTIMATELY RESULTED IN COMPLETE SEPARATION.