DTE GAS COMPANY

Incident Narrative

DTE GAS CONTROL RECEIVED NOTIFICATION AT APPROXIMATELY 09:30, JULY 21, 2014 FROM GRAND RAPIDS FIELD TECHNICIANS THAT ROUTINE MAINTENANCE WORK WAS BEING PERFORMED AT THAT FACILITY DURING THAT DAY. NO ALARMS OR UNUSUAL ACTIVITY WERE NOTICED BY GAS CONTROL. AT APPROXIMATELY 16:55, AN ELECTRONIC FLOW COMPUTER AT GEORGETOWN REGULATING STATION BEGAN SENSING FALSE HIGH FLOW AND A FALSE HIGH INLET AND OUTLET PRESSURES. DURING NORMAL OPERATIONS, ODORANT IS AUTOMATICALLY INJECTED INTO THE GRAND RAPIDS DISTRIBUTION SYSTEM BASED UPON VOLUME DELIVERY SIGNALS FROM THE FLOW COMPUTER. THE FALSE HIGH FLOW SIGNALS FROM THE MALFUNCTIONING COMPUTER RESULTED IN OVER-INJECTION OF ODORANT (MERCAPTAN) INTO THE DISTRIBUTION SYSTEM CREATING AN OVER-ODORIZED CONDITION. DTE GAS CONTROL IMMEDIATELY BEGAN RECEIVING AN ALARM FOR HIGH INLET AND OUTLET PRESSURES. THE CONTROLLER PRESUMED THE ALARMS WERE ACTIVATED IN THE COURSE OF THE ROUTINE WORK BEING CONDUCTED BY GRAND RAPIDS FIELD TECHNICIANS. AT APPROXIMATELY 17:00, THE GRAND RAPIDS FIELD TECHNICIANS ONSITE COMPLETED THEIR WORK, WHICH WAS NOT RELATED TO ANY OF THE FLOW OR PRESSURE DEVICES AND LEFT THE SITE UNAWARE THAT AN ALARM HAD BEEN ACTIVATED AT GAS CONTROL. AT APPROXIMATELY 23:40, GAS CONTROL BECAME CONCERNED THEY HAD NOT RECEIVED ANY CONTACT FORM THE GRAND RAPIDS FIELD TECHNICIANS SINCE EARLY THAT MORNING AND CONTACTED AN OPERATIONS SUPERVISOR. A SECOND FIELD CREW WAS DEPLOYED TO GEORGETOWN STATION TO INVESTIGATE, ARRIVING AT 00:41 JULY 22, 2014. AT 00:49, THE FIELD CREW DETERMINED THE ODORANT INJECTION SYSTEM WAS OPERATING AT ABNORMALLY HIGH RATE AND PLACED THE SYSTEM INTO STANDBY MODE. THE FIELD CREW CONTACTED THE REGION CONTROLS TECHNICIAN WHO ALSO RESPONDED TO THE GEORGETOWN STATION. THE FLOW COMPUTER WAS RESET BY THE CONTROLS TECHNICIAN, THE ABNORMAL PRESSURE AND FLOW SIGNALS WERE CLEARED, AND THE COMPUTER RESUMED NORMAL OPERATION. AT 01:30, THE FIELD CREW REPORTED TO GAS CONTROL THAT THE ODOR INJECTION SYSTEM HAD BEEN OPERATING AT AN ABNORMALLY HIGH RATE OVER THE PAST SEVERAL HOURS. AT 05:45, GEORGETOWN GATE STATION WAS ISOLATED FROM THE SYSTEM IN AN EFFORT TO CONTAIN EXCESS ODORANT FROM GETTING INTO THE SYSTEM. BY 08:00, JULY 23 THE EVENT WAS OVER AND LEAK COMPLAINT VOLUME WAS BACK TO NORMAL. THE ABNORMAL HIGH ODORIZATION RATE RESULTED IN 610 LEAK COMPLAINTS THAT WERE RESPONDED TO AND INVESTIGATED BY GRAND RAPIDS FIELD PERSONNEL.