CONSUMERS ENERGY CO

Incident Narrative

AT APPROXIMATELY 9:20 AM ON APRIL 27, 2014, OILY LIQUIDS CAUSED THE PRIMARY WORKER AND MONITOR REGULATORS AT WEST WAYNE CITY GATE (29380 W. 13 MILE ROAD; FARMINGTON HILLS, MI) TO FAIL. LIQUIDS WERE FOUND IN THE REGULATORS, PILOTS, AND PILOT FILTERS OF THE PRIMARY REGULATOR RUN, AS WELL AS IN AND AROUND THE CITY GATE HEATER. A WORN DIAPHRAGM WAS ALSO OBSERVED ON THE PRIMARY WORKER REGULATOR. THE DOUBLE REGULATOR FAILURE RESULTED IN AN OVERPRESSURE OF THE 340 PSIG MAOP DOWNSTREAM SYSTEM. THE OVERPRESSURE EVENT WAS ORIGINALLY IDENTIFIED VIA SCADA ALARMS BY CONSUMERS ENERGY'S GAS CONTROL AT APPROXIMATELY 9:24 AM, WHEN AN OUTLET PRESSURE OF 426 PSIG WAS MEASURED. FIELD PERSONNEL WERE DISPATCHED TO WEST WAYNE CITY GATE AT 9:25 AM. PERSONNEL ARRIVED AT 10:15 AM, AND THE DOWNSTREAM SYSTEM PRESSURE WAS REDUCED TO BELOW 340 PSIG AT 10:27 AM. THE MAX PRESSURE REACHED DURING THE OVERPRESSURE EVENT WAS 455 PSIG (134% MAOP) AT APPROXIMATELY 9:48 AM. FURTHER DOWNSTREAM OF WEST WAYNE CITY GATE, A SLUG OF LIQUIDS ALSO CAUSED A DOUBLE REGULATOR FAILURE AT A WORKER-MONITOR HIGH PRESSURE DISTRIBUTION REG STATION AT 12 MILE AND FRANKLIN ROADS, CAUSING THE MAOP OF THE MEDIUM PRESSURE SYSTEM (60 PSIG MAOP) DOWNSTREAM OF THAT FACILITY TO BE EXCEEDED AS WELL. PRESSURES ON THIS SYSTEM REACHED 104 PSIG (173% MAOP) ACCORDING TO PRESSURE RECORDING CHARTS AT 12 MILE AND FRANKLIN. THIS RESULTED IN A VENTING RELIEF VALVE AT ANOTHER NEARBY REGULATOR STAND (LOCATED AT 29257 CHATEAU COURT, FARMINGTON HILLS AND FEEDING THE SAME 60 PSIG MAOP SYSTEM) DUE TO BACKPRESSURE. THE BLOWING RELIEF WAS DISCOVERED AT 6:10 PM ON APRIL 27, AND VENTED FOR APPROXIMATELY 90 MINUTES. IN SUMMARY, THREE DOWNSTREAM SYSTEMS WERE IMPACTED BY THE OVERPRESSURE EVENT: - APPROXIMATELY 5.25 MILES OF 10"" STEEL PIPING (340 PSIG MAOP) OPERATING AT > 20% SMYS (AND THEREFORE CLASSIFIED AS TRANSMISSION PIPE, THOUGH OPERATED BY GAS DISTRIBUTION) RUNNING SOUTH OF WEST WAYNE CITY GATE ALONG MIDDLEBELT ROAD TO 8 MILE ROAD - APPROXIMATELY 1.25 MILES OF 8"" STEEL HIGH PRESSURE DISTRIBUTION PIPING (340 PSIG MAOP) RUNNING EAST OF WEST WAYNE CITY GATE ALONG 13 MILE ROAD AND THEN SOUTHEAST ALONG NORTHWESTERN HIGHWAY, TO REGULATOR STATION AT 12 MILE & FRANKLIN ROADS - APPROXIMATELY 87 MILES OF STEEL AND PLASTIC MEDIUM PRESSURE MAIN AS WELL AS 2,944 SERVICES (60 PSIG MAOP) IN FARMINGTON AND SOUTHFIELD TOWNSHIPS, DOWNSTREAM OF THE REGULATOR STATION AT 12 MILE & FRANKLIN ROADS MOBILE AND WALKING LEAK SURVEY WAS PERFORMED ON THE OVERPRESSURED FACILITIES BETWEEN APRIL 28TH AND APRIL 30TH. ADDITIONALLY, OVER 20 GALLONS OF LIQUIDS WERE COLLECTED FROM SURROUNDING DRIP SITES, WITH THE MAJORITY COLLECTED AT THE REGULATOR STATION AT 12 MILE & FRANKLIN. FOLLOW-UP LABORATORY ANALYSIS REVEALED THAT THE COMPOSITION OF LIQUIDS COLLECTED AT WEST WAYNE CITY GATE AND 12 MILE & FRANKLIN WAS CONSISTENT WITH COMPRESSOR ENGINE OIL UTILIZED AT CONSUMERS ENERGY COMPRESSOR STATIONS. AN PROGRAM OF ACCELERATED INSTALLATION OF FILTERS/SEPARATORS AT CONSUMERS ENERGY CITY GATE AND REGULATOR STATION FACILITIES IS CURRENTLY UNDERWAY TO HELP PREVENT RECURRENCE OF SIMILAR DAMAGE BY DEBRIS/LIQUIDS TO REGULATORS AND OVERPRESSURE PROTECTION DEVICES.