CONSUMERS ENERGY CO

Incident Narrative

ON NOVEMBER 20, 2017 AT 2150 HOURS, A BURIED 22-INCH-DIAMETER INTRASTATE NATURAL GAS TRANSMISSION PIPELINE (LINE 600), OWNED AND OPERATED BY CONSUMERS ENERGY RUPTURED IN ORION CHARTER TOWNSHIP (OAKLAND COUNTY) BETWEEN BALDWIN AND JOSLYN ROADS. LINE 600 STRETCHES APPROXIMATELY 34 MILES FROM THE CLARKSTON JUNCTION INTERCHANGE IN CLARKSTON, MI (OAKLAND COUNTY) TO THE UTICA CITY GATE, UTICA, MI (MACOMB COUNTY). CONSUMERS ENERGY EMPLOYEES ARRIVED ONSITE AT APPROXIMATELY 2243 HOURS AND BEGAN THE PROCESS OF ISOLATING THE 6.5 MILE SEGMENT OF LINE 600 UTILIZING EMERGENCY VALVES LOCATED AT ORION CITY GATE, ORION CHARTER TOWNSHIP, MI AND DIXIE-WATERFORD CITY GATE, CLARKSTON, MI. THE SEGMENT WAS FULLY ISOLATED AND CLOSED AT APPROXIMATELY 2307 HOURS. THE ESCAPING HIGH-PRESSURE NATURAL GAS IGNITED. FIRE DAMAGE EXTENDED ALONG THE PIPELINE RIGHT-OF-WAY AND DAMAGED SEVERAL TRACTOR TRAILERS PARKED AT THE REAR OF THE PROPERTY AT 693 BROWN ROAD. LOCAL POLICE AND FIRE PERSONNEL RESPONDED. THERE WERE NO FATALITIES OR INJURIES AS A RESULT OF THE RUPTURE. THE DAMAGED PIPELINE AND ASSOCIATED FRAGMENTS WERE SECURED AND TRANSPORTED TO CONSUMERS ENERGY'S TRAIL STREET LABORATORY FOR METALLURGICAL TESTING AND DETERMINATION OF A FAILURE MODE. A PRELIMINARY CAUSE OF FAILURE HAS BEEN IDENTIFIED AS OVERLOAD FAILURE DUE TO FILL MATERIAL PLACE OVER THE PIPELINE. AN INTERNAL TEAM WAS ASSEMBLED IMMEDIATELY FOLLOWING THE INCIDENT TO COMPLETE A ROOT CAUSE INVESTIGATION. THE INVESTIGATION INCLUDED DEVELOPING A SEQUENCE OF EVENTS, AND A REVIEW OF THE SCENE AND PERTINENT FACTS NEEDED TO IDENTIFY A ROOT CAUSE(S). COUNTERMEASURES WILL ALSO BE DEVELOPED TO PREVENT RE-OCCURRENCE. THE RUPTURED SEGMENT OF LINE 600 WILL NOT BE RETURNED TO SERVICE UNTIL THE INVESTIGATION AND APPROPRIATE REMEDIATION ACTIONS HAVE BEEN COMPLETED. CONSUMERS ENERGY LABORATORY SERVICES CONCLUDED THE RUPTURE ON CONSUMERS ENERGY LINE 600 WAS THE RESULT OF A TENSILE OVERLOAD THROUGH THE 22"" OD X 0.281 WALL PIPE ADJACENT TO THE EAST END GIRTH WELD WHERE AN 11.8' SECTION OF 22"" OD X 0.375 WALL PIPE WAS INSTALLED DURING REMEDIATION WORK IN 2009. THE INSTANTANEOUS NATURE OF OVERLOAD FAILURE AND THE TIME DURATION FROM WHEN THE PIPE WAS INSTALLED UNTIL THE FAILURE OCCURRED SUGGESTS LOADING CONDITIONS CHANGED OVER TIME; HOWEVER, THE EXACT CAUSE FOR THIS FAILURE COULD NOT BE DETERMINE FROM METALLOGRAPHIC ANALYSIS. CORROSION WAS NOT FOUND TO BE A CONTRIBUTING FACTOR IN THE FAILURE. THE RCA TEAM SIMILARLY DETERMINED THE ROOT CAUSE OF THE PIPELINE FAILURE TO BE OVERLOAD AS A RESULT OF APPROXIMATELY 21' OF FILL MATERIAL ON TOP OF THE GAS PIPELINE WHICH LACKED SUPPORT DUE TO THE PRESENCE OF HIGHLY COMPRESSIBLE SOILS BELOW THE PIPELINE. THE WELD ID OFFSET (HI-LO) WHICH EXCEEDED CODE ALLOWABLE 0.155"" VERSUS 3/32"" (.09375) AT THE 2009 REMEDIATION TIE-IN TO EXISTING PIPE WAS DETERMINE TO BE A CONTRIBUTING FACTOR BUT NOT A SECONDARY ROOT CAUSE. THE RCA TEAM ALSO IDENTIFIED HUMAN AND SYSTEMIC ROOT COMPONENTS THAT MAY HAVE CONTRIBUTED TO THE FAILURE. CORRECTIVE ACTIONS TO MINIMIZE THE POTENTIAL FOR REOCCURRENCE HAVE BEEN IMPLEMENTED. CONSUMERS ENERGY REPLACED APPROXIMATELY 1,200 FEET OF LINE 600 NORTH OF BROWN RD. AND WEST OF JOSLYN RD. IN LAKE ORION, MI. THE ENTIRE DISTANCE WAS REPLACED USING HORIZONTAL DIRECTIONAL DRILLING METHODS (HDD). THE HDD METHOD WAS SELECTED IN ORDER TO ACHIEVE DEPTHS BELOW THE COMPRESSIBLE ORGANIC SOIL LAYERS THAT CONTRIBUTED TO THE FAILURE OF THE PIPELINE. ALL REMEDIATION ACTIVITIES AND HYDROSTATIC TESTING WERE PERFORMED IN ACCORDANCE WITH APPLICABLE REGULATIONS AND THE RUPTURE SEGMENT OF THE PIPELINE WAS RETURNED TO NORMAL OPERATIONS ON FRIDAY, MARCH 23, 2018.