CONSUMERS ENERGY CO

Incident Narrative

AT APPROXIMATELY 13:10 ON FRIDAY, MAY 15, 2015 A CONSUMERS ENERGY (CE) EMPLOYEE INSTALLING PIPELINE MARKERS AT THE CRANBERRY STORAGE FIELD OBSERVED BUBBLING FROM A STANDING WATER PUDDLE AND A FROST BALL IN AN AREA ABOVE LATERAL 60 WEST BETWEEN WELLS C270 AND C367. LATERAL 60 WEST IS A 6"" PIPELINE (APPROXIMATELY 1 1/2 MILES LONG) LOCATED IN CONSUMERS ENERGY'S CRANBERRY STORAGE FIELD, MARION, MICHIGAN (MISSAUKEE COUNTY). ADDITIONAL CE EMPLOYEES ARRIVED ON-SITE AT APPROXIMATELY 14:00 ON MAY 15, 2015 TO BEGIN IMPLEMENTING THE STANDARD PRECAUTIONARY LOCK OUT TAG OUT PROCESS, ISOLATING AND SHUTTING DOWN LATERAL 60 WEST AND BARRICADING THE LOCATION UNTIL FURTHER INVESTIGATION COULD BE PERFORMED. THE BLOW-DOWN PROCESS WAS COMPLETE AND THE LINE SHUT-DOWN AT APPROXIMATELY 14:30. ON MONDAY, MAY 18, 2015 A 11/2 FOOT SECTION OF THE PIPELINE WAS CUT OUT AND A PINHOLE LEAK DISCOVERED. THE LEAK WAS VISUALLY EXAMINED AND PRELIMINARY ANALYSIS IDENTIFIED CORROSION AS A POSSIBLE LEAK SOURCE. THE APPROXIMATE GAS LOSS OF 3.6 MMCF WAS ESTIMATED BASED ON INFORMATION OBTAINED FROM THE LEAK PATROL CONDUCTED ON MARCH 18, 2015. THERE WAS NO INDICATION OF ABNORMAL CONDITIONS AT THIS LOCATION AT THAT TIME. THE DAMAGED SECTION OF THE PIPELINE WAS TRANSPORTED TO THE CONSUMERS ENERGY TRAIL STREET LABORATORY FOR FURTHER EXAMINATION. THE LABORATORY ANALYSIS CONFIRMED THE LEAK WAS A RESULT OF A LOCALIZED CORROSION PIT ON THE PIPE ID WHICH DEVELOPED AN OVAL THROUGH WALL HOLE AT THE OD MEASURING APPROXIMATELY .375""X 0.25"". THE PRESENCE OF SIGNIFICANT CONCENTRATION OF SULFUR WITHIN THE PIT INDICATES MICROBIOLOGICAL INFLUENCE CORROSION (MIC) CAUSED BY SULFATE-REDUCING BACTERIA (SRB) MAY HAVE CAUSED OR CONTRIBUTED TO THE FAILURE. HOWEVER, IT COULD NOT BE DEMONSTRATED THAT THE DAMAGE MEETS THE THREE CRITERIA REQUIRED TO VALIDATE MIC. IN ADDITION TO COMPREHENSIVE METALLURGICAL TESTING, CONSUMERS ENERGY CONDUCTED A REVIEW OF THE 2005 TOOL DATA AND IDENTIFIED TWO DIG LOCATIONS AS VERIFICATION. THE LOCATIONS, DIG #1 JT 60 AND DIG #2 JT 117, WERE EXPOSED, EXAMINED AND ONE SECTION (DIG #2 JT 117) WAS REPLACED DUE TO THE PRESENCE OF MINOR CORROSION. ULTRASONIC THICKNESS (UT) SENSORS WERE ALSO INSTALLED AT THESE TWO LOCATION TO MONITOR INTERNAL CORROSION. REMEDIATION WORK WAS COMPLETED AND LATERAL 60 WEST WAS PLACED BACK INTO SERVICE ON OCTOBER 7, 2016. ON OCTOBER 24, 2015 AN ADDITIONAL LEAK WAS DISCOVERED ON LATERAL 60 WEST APPROXIMATELY 677 FEET NORTH OF THE LEAK IDENTIFIED IN MAY. AN INCIDENT REPORT-GAS TRANSMISSION AND GATHERING PIPELINE SYSTEMS (2015140-16931) WAS SUBMITTED TO PHMSA ON NOVEMBER 24, 2015. LABORATORY ANALYSIS CONFIRMED THE LEAK DISCOVERED IN OCTOBER WAS A RESULT OF A LOCALIZED CORROSION PIT ON THE PIPE ID. THE MIC TESTING PERFORMED ON SLUDGE EXTRACTED FROM THE PIPE INDICATES MICROBIOLOGICAL INFLUENCE CORROSION (MIC) MAY HAVE CAUSED OR CONTRIBUTED TO THE FAILURE.