PACIFIC GAS & ELECTRIC CO

Incident Narrative

ON JUNE 27, 2017 PG&E COMPLETED A SET POINT CHANGE ON A VALVE ON L400 NEAR MP 233.87. ON JULY 1, 2017, AT 0445 HRS, PG&E'S GAS CONTROL DETECTED RELIEF VALVE ACTIVATION AT BUCKEYE CREEK STATION (LINE 400, MP 233.87). THE RELIEF OPENED 3 TIMES WITH DURATIONS OF 3 MINUTES EACH DUE TO AN OSCILLATION OF A MAINLINE VALVE. THE SYSTEM DID NOT OVER PRESSURIZE. THE CONTROL ROOM ADJUSTED THE SET POINTS ON THE REGULATING VALVE AND MAINLINE VALVES REMOTELY AND THE SYSTEM RETURNED TO NORMAL OPERATIONS BY 1242 HOURS. THERE WAS NO CUSTOMER IMPACT. THERE WAS NO FIRE, POLICE OR MEDIA REPORTED. THERE WERE NO INJURIES, FATALITIES, OR IGNITION. ON 7/3/17 AT 1159 HOURS, IT WAS DETERMINED THAT THE UNINTENTIONAL RELEASE OF GAS EXCEEDED THE 3 MMCF CRITERIA. THE VOLUME ESTIMATE OF GAS UNINTENTIONALLY RELEASED IS 3.1 MMCF. COST OF GAS UNINTENTIONALLY RELEASED IS $9,300. THIS INCIDENT WAS REPORTED TO THE DOT AND CPUC DUE TO THE UNINTENTIONAL RELEASE OF GAS ESTIMATED TO BE GREATER THAN 3 MMCF. THE VOLUME ESTIMATE UPDATE WAS PROVIDED TO THE DOT (#1183141) ON 7/5/17. IT WAS LATER DETERMINED THAT THE SET POINT CHANGES MADE BY THE OPERATOR ON JUNE 27, 2017 SHOULD HAVE BEEN ON THE TRIMMER VALVE AND NOT THE MAIN LINE VALVE. THE GAS SYSTEM OPERATOR, ALONG WITH THE PG&E GAS TRANSMISSION CONTROL CENTER SYSTEM OPERATORS AND COORDINATORS, WERE RE-TRAINED IN SET POINT CHANGE OPERATION FOLLOWING THE INCORRECT OPERATION AT DUNNIGAN HILLS ON JULY 1, 2017.