CONSUMERS ENERGY CO — Gas transmission and gathering — incident on 2015-05-04

Gas transmission and gathering incident in CHELSEA, WASHTENAW County, MI. Reported cause: MATERIAL FAILURE OF PIPE OR WELD. Reported consequences: 0 fatalities, 0 injuries, 48000 NATURAL GAS released, $5,000,000 reported property damage. Operator-reported incident data submitted to PHMSA, generally within 30 days. Records may be supplemented or corrected and do not represent final agency causal findings.

Report number: 20150075.

Operator ID: 2748.

Reported incident date: 5/4/2015 22:35.

Location detail: 738+90

Cause detail: ENVIRONMENTAL CRACKING-RELATED

Cause detail: AT APPROXIMATELY 22:35 HOURS ON MONDAY, MAY 4, 2015, CONSUMERS ENERGY'S GAS CONTROL PERSONNEL RECEIVED AN ALARM FROM A SCADA POINT AT STOCKBRIDGE CITY GATE IDENTIFYING A PRESSURE DROP OF APPROXIMATELY 200 PSIG AS A RESULT OF A RUPTURE OF LINE 100A. LINE 100A IS A 20" INTRASTATE TRANSMISSION PIPELINE STRETCHING APPROXIMATELY 60 MILES FROM FREEDOM COMPRESSOR STATION IN MANCHESTER, MICHIGAN (WASHTENAW COUNTY) TO OVID SUBSTATION IN OVID, MICHIGAN (CLINTON COUNTY). CONSUMERS ENERGY EMPLOYEES ARRIVED ON SITE AT APPROXIMATELY 00:26 HOURS ON MAY 5, 2015 AND ISOLATED A 12 MILE SEGMENT OF LINE 100A UTILIZING EMERGENCY VALVES LOCATED AT THE CHELSEA INTERCHANGE NEAR CHELSEA, MICHIGAN (WASHTENAW COUNTY) AS WELL AS STOCKBRIDGE CITY GATE IN STOCKBRIDGE, MICHIGAN (INGHAM COUNTY). GAS WAS SHUT OFF TO THE RUPTURED SEGMENT OF PIPELINE AT APPROXIMATELY 00:33. EMPLOYEES ARRIVING ON SITE TO ISOLATE THE AFFECTED SEGMENT CONFIRMED THE LOCATION OF THE PIPELINE RUPTURE NEAR SOUTH LAKE DRIVE AND ROEPKE ROAD IN CHELSEA AT APPROXIMATELY 01:09. LOCAL POLICE AND FIRE PERSONNEL WERE ALSO ON SITE RESPONDING. NO INJURIES, FATALITIES, OR IGNITION OCCURRED AS A RESULT OF THE RELEASE. 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. PRELIMINARY RESULTS INDICATE THE PRESENCE OF STRESS CORROSION CRACKING (SCC). THE POTENTIAL FOR ADDITIONAL SCC CONDITIONS ON LINE 100A HAS RESULTED IN CONSUMERS ENERGY TAKING A REDUCTION IN PRESSURE FOR LINE 100A OF MORE THAN 20% OF THE OPERATING PRESSURE AT THE TIME OF CONDITION DETERMINATION. THIS REDUCTION WAS MADE FOR THE ENTIRETY OF LINE 100A BETWEEN FREEDOM AND OVID, AND WAS COMPLETED ON JUNE 2, 2015 PENDING ADDITIONAL INTEGRITY MANAGEMENT TESTING AND REMEDIATION. REMEDIATION ACTIVITIES AND HYDROSTATIC TESTING WERE PERFORMED IN ACCORDANCE WITH APPLICABLE REGULATIONS AND LIVE GAS WAS RETURNED TO THE RELEVANT PORTIONS OF LINE 100A, FREEDOM COMPRESSOR STATION TO OVID VALVE SITE ON JANUARY 16, 2016.

PHMSA trend classification: significant incident, not serious.

PHMSA standardized cause: MATERIAL FAILURE OF PIPE OR WELD — ENVIRONMENTAL CRACKING-RELATED.

PHMSA indexed costs: $5,439,148 reported total cost, $2,881,025.788 in 1984 dollars, $6,685,083.757 in current-year dollars.

PHMSA trend flags, standardized causes, and indexed costs are analytical fields added to operator-reported incident data. They do not represent final agency causal findings.