CONSUMERS ENERGY CO

Incident Narrative

AT 07:32 AM ON SEPTEMBER 30, 2017 CONSUMERS ENERGY GAS CONTROL RECEIVED A HIGH-HIGH ALARM ON THE OUTLET PRESSURE AT LANSING CITY GATE, AIRPORT RD, LOCATED AT 13698 S. AIRPORT RD, LANSING MI (CLINTON COUNTY). THIS ALARM IS SET TO 400 PSI, WHICH IS THE MAOP OF OUTLET OF THE FACILITY. THE HIGHEST PRESSURE RECORDED WAS 500 PSIG, HOWEVER THAT IS THE UPPER LIMIT OF THE TRANSDUCER SO PRESSURE MAY HAVE BEEN HIGHER THAN 500 PSIG. CONSUMERS ENERGY PERSONNEL ARRIVED ONSIDE AT APPROXIMATELY 08:15. IT WAS FOUND THAT WITH THE RELEASE OF NATURAL GAS THROUGH THE RELIEF VALVE, AN OIL-LIKE SUBSTANCE WAS ALSO RELEASED. THIS SUBSTANCE AFFECTED 3 HOMES AND A FARMERS FIELD NEARBY. LAB ANALYSIS HAS DETERMINED THIS SUBSTANCE WAS COMPRISED OF MID-RANGE AND HEAVY HYDROCARBONS. THE FACILITY WAS OPERATING PROPERLY ON THE SECONDARY RUN WHEN PERSONNEL ARRIVED WITHIN NORMAL OPERATING PRESSURES. THE REGULATOR FAILURE WAS CAUSED BY AN INFLUX OF HYDROCARBONS AFFECTING THE FUNCTION OF THE REGULATORS. CONSUMERS ENERGY CREW REBUILT THE PRIMARY AND SECONDARY RUN REGULATORS AND PILOTS AT THE CITY GATE AND RE-TESTED THE RELIEF VALVE. ADDITIONAL PERSONNEL COMPLETED LEAK SURVEY AND FOUND NO LEAKS. PERSONNEL ALSO CHECKED SURROUNDING REGULATOR STATIONS AND ALL WERE FOUND TO BE OPERATING CORRECTLY. ALL WORK WAS COMPLETED BY 19:15 ON SEPTEMBER 30, 2017. CONSUMERS ENERGY HAS BEEN WORKING WITH A THIRD-PARTY CONTRACTOR FOR ENVIRONMENTAL CLEANUP. THE DEQ WAS NOTIFIED AT 13:00 ON SEPTEMBER 30, 2017. ENVIRONMENTAL CLEANUP HAS BEEN COMPLETED. AFTER LAB ANALYSIS AND INVESTIGATION, THE CAUSE/SOURCE OF THE HYDROCARBONS IS BELIEVED TO BE A RESULT OF FREE LIQUIDS FROM STORAGE FIELDS, AND LIQUIDS NOT RECOVERED IN PIGGING OPERATIONS. CONSUMERS ENERGY HAS PROVIDED THESE SOURCES AND AFFILIATED ACTION PLANS TO THE MPSC.