CONSUMERS ENERGY CO

Incident Narrative

AT APPROXIMATELY 11:55 ON SATURDAY, OCTOBER 24, 2015 CONSUMERS ENERGY GAS CONTROL WAS NOTIFIED BY A LANDOWNER OF A POSSIBLE GAS LEAK AT THE CRANBERRY STORAGE FIELD. A GAS SYSTEM MECHANIC (GSM) WAS DISPATCH AND ARRIVED ON-SITE AT 12:23 AND IDENTIFIED BLOWING GAS ON LATERAL 60 WEST. THE LEAK LOCATION WAS APPROXIMATELY 1750 FEET NORTH OF WELL 367. LATERAL 60 WEST IS A 6 INCH PIPELINE (APPROXIMATELY 11/2 MILES LONG) LOCATED IN CONSUMERS ENERGY'S CRANBERRY STORAGE FIELD, MARION, MICHIGAN (MISSAUKEE COUNTY) THE GSM IMPLEMENTED THE STANDARD PRECAUTIONARY LOCK OUT TAG OUT PROCESS, ISOLATING AND SHUTTING DOWN LATERAL 60 WEST AND BARRICADED THE LOCATION UNTIL FURTHER INVESTIGATION COULD BE PERFORMED. THE PIPELINE WAS SHUT DOWN AT APPROXIMATELY 12:31. ON TUEDAY, NOVEMBER 3, 2015 A 4 FOOT SECTION OF PIPELINE WAS CUT OUT AND A OVAL HOLE APPROXIMATELY .25 X .50 WAS DISCOVERED. THE LEAK WAS VISUALLY EXAMINED AND PRELIMINARY ANALYSIS IDENTIFIED CORROSION AS A POSSIBLE LEAK SOURCE. THE GAS LOSS CALCULATION WAS DETERMINED BASED ON THE FOLLOWING INFORMATION: LATERAL 60 WEST WAS PLACED BACK INTO SERVICE ON OCTOBER 7, 2015. THE LEAK WAS IDENTIFIED AND THE PIPELINE WAS ISOLATED AND SHUT DOWN ON OCTOBER 24, 2015 APPROXIMATELY 36 MINUTES FOLLOWING NOTIFICATION. A VISUAL INSPECTION WAS PERFORMED BY OPERATIONS PERSONNEL WHEN THE PIPELINE WAS PLACED BACK INTO SERVICE, HOWEVER NO ADDITIONAL INSPECTIONS/PATROLS WERE CONDUCTED. BECAUSE NO ADDITIONAL LEAK INSPECTION WAS PERFORMED DURING THIS PERIOD, CONSUMERS ENERGY OPTED TO CALCULATE THE HOURS FROM THE DATE THE LINE WAS PLACED BACK IN SERVICE ON OCTOBER 7TH UNTIL THE LEAK WAS DISCOVERED AND THE LATERAL SHUT-DOWN RESULTING IN A GAS LOSS OF APPROXIMATELY 37MMCF. THE GAS LOSS CALCULATION BASED ON NOTIFICATION AND ISOLATION AND SHUT DOWN WOULD HAVE RESULTED IN A GAS LOSS CALCULATION OF LESS THAN 1MMCF. THE DAMAGED SECTION OF THE PIPELINE WAS TRANSPORTED TO THE CONSUMERS ENERGY TRAIL STREET LABORATORY FOR FURTHER EXAMINATION. LABORATORY ANALYSIS CONFIRMED THE LEAK WAS A RESULT OF A LOCALIZED CORROSION PIT ON THE PIPE ID. THE MIC TESTING PERFORMED ON SLUDGE EXTRACTED FROM THE PIPELINE INDICATES MICROBIOLOGICAL INFLUENCE CORROSION (MIC) MAY HAVE CAUSED OR CONTRIBUTED TO THE FAILURE. LATERAL 60 WEST REMAINS SHUT-IN AND SCHEDULED FOR REPLACEMENT BOTH LATERAL 60 EAST AND WEST WILL BE ELIMINATED AND REPLACED WITH ONE LATERAL IN SUMMER 2016.