CONSUMERS ENERGY CO

Incident Narrative

ON MARCH 16, 2022 AT APPROXIMATELY 09:20 HOURS A BURIED 24-INCH DIAMETER NATURAL GAS TRANSMISSION PIPELINE SEGMENT (LINE 400-1) OWNED AND OPERATED BY CONSUMERS ENERGY RUPTURED IN TYRONE TOWNSHIP (LIVINGSTON COUNTY) BETWEEN OLD HIGHWAY 23 AND LINDEN ROAD. LINE 400 WAS INSTALLED IN 1952 AND IS APPROXIMATELY 35.1 MILES FROM FENTON INTERCHANGE IN FENTON, MICHIGAN TO LAINGSBURG INTERCHANGE IN LAINGSBURG, MICHIGAN. INVESTIGATION AND ROOT CAUSE SUMMARY AFTER THE ONSITE INCIDENT INVESTIGATION CONCLUDED, THE PIPELINE FRAGMENTS WERE TRANSPORTED TO THE CONSUMERS ENERGY LABORATORY FOR A METALLURGICAL ANALYSIS. ADDITIONALLY, A THOROUGH PIPELINE HISTORY REVIEW, INCLUDING PREVIOUS INLINE INSPECTION RESULTS, WAS PERFORMED ALONG WITH A FINITE ELEMENT ANALYSIS (FEA) AND INDUSTRY BENCHMARKING THROUGH THE AMERICAN GAS ASSOCIATION (AGA). THE COMPREHENSIVE INVESTIGATION DETERMINED CONSUMERS ENERGY'S LINE 400 PIPELINE WAS A RESULT OF AN OVERSTRESS CONDITION OF THE 24-INCH PIPELINE DURING THE CIRCUMFERENTIAL MAGNETIC FLUX LEAKAGE (CMFL) INSPECTION. A DYNAMIC OVERSTRESS OF THE LINE 400 PIPELINE OCCURRED DURING THE CMFL INLINE INSPECTION DUE TO THE COMBINATION OF STRESS ON THE LINE WHICH RESULTED IN THE INITIATION OF A LEAK AND A SUBSEQUENT RUPTURE. CONSUMERS ENERGY'S MANAGEMENTS SYSTEM AND CONTROLS FOR INLINE INSPECTION OPERATIONS DID NOT REQUIRE A HAZARD ANALYSIS TO EVALUATE THE COMBINE EFFECTS OF PIPELINE MATERIAL PROPERTIES, PIPELINE TEMPERATURE AND PRESSURE, AND THE WEIGHT, VELOCITY, AND DESIGN OF THE INSPECTION TOOL. THE ABSENCE OF CONTROLS LED TO THE PRESENCE OF MULTIPLE ADVERSE CONDITIONS TO PIPELINE INTEGRITY WHICH CAUSED THE NATURAL GAS RELEASE AND SUBSEQUENT PIPELINE RUPTURE THAT IMPACTED PIPELINE OPERATIONS, INTEGRITY INSPECTIONS AND RESULTED IN SIGNIFICANT REMEDIATION COSTS. INLINE INSPECTION OPERATIONS WERE TEMPORARILY DISCONTINUED ON MARCH 16, 2022, BECAUSE OF THIS EVENT AND DID NOT RESUME UNTIL SEPTEMBER 14, 2022, WHEN THE DIRECT AND ROOT CAUSES WERE IDENTIFIED AND ""SAFE PIGGING OPERATIONS"" COUNTERMEASURES WERE IMPLEMENTED. THE RESULTS OF OUR RCA INVESTIGATION, NEW SAFETY PROTOCOLS AND STANDARD WORK HAVE BEEN DEVELOPED AND PRESENTED TO THE MICHIGAN PUBLIC SERVICE COMMISSION. A COMMUNICATION PLAN IS BEING DEVELOPED TO SHARE CHANGES TO OUR INLINE INSPECTION PROGRAM AND LESSON LEARNED.