CONSUMERS ENERGY CO

Incident Narrative

ON THE MORNING OF MONDAY, FEBRUARY 16, 2015 AT APPROXIMATELY 7:05 A.M. A 6"" BLOWDOWN VALVE IN PLANT # 2 AT THE FREEDOM COMPRESSOR STATION UNEXPECTEDLY OPENED. BLOWDOWN VALVE # 612 WAS IN THE NORMAL OPERATING BLOCKED POSITION PRIOR TO THE EVENT WITH 680PSIG UPSTREAM AT THE TIME OF THE EVENT AND THE OUTLET OF THE VALVE AT ATMOSPHERIC PRESSURE. WITH THE ACTIVATION OF THE VALVE, GAS WAS VENTED OUT THE EAST VENT STACK (AT THE FENCE LINE). CMS EMPLOYEES AT THE STATION WERE ABLE TO VERIFY AND ISOLATE PLANT #2 BY UTILIZING VALVE #607 TO LIMIT SUCTION UP-STREAM OF THE SINGLE BLOWDOWN VALVE WHICH HAD OPENED. VALVE #612 WAS HYDRAULICALLY PUMPED CLOSED AT APPROXIMATELY 7:19 A.M. THE ESTIMATED GAS LOSS DURING THIS 14 MINUTE PERIOD IS APPROXIMATELY 5.8 MMCF. GAS CONTROL EMPLOYEES IDENTIFIED A CHANGE OF THE DESIRED RATE AND A PRESSURE CHANGE AND CONTACTED THE STATION CONTROL ROOM OPERATORS WITHIN MINUTES OF THE EVENT. VALVE # 612 CYCLED NORMALLY AND SIMILAR VALVES #611, # 613 AND # 614 HAD NO SIGNS OF ISSUES. PILOT PRESSURE WAS NOTICED NEAR 130PSIG AND STEADY AT 150PSIG AT THE TIME OF RESET WHICH WAS APPROXIMATELY 9:30 A.M. PRESSURE WAS BACK TO 180-190PSIG WITH SYSTEMS BACK IN SERVICE BY 10:00 A.M. NO ABNORMAL CONDITIONS WERE FOUND OTHER THAN LOW PILOT PRESSURE. THE PILOT AND POWER GAS REGULATOR PRESSURE SETTINGS WERE INCREASED BY A ONE-QUARTER TURN EACH RESULTING IN 190-195PSIG PILOT GAS PRESSURE AND 490-495PSIG POWER GAS PRESSURE.