PACIFIC GAS & ELECTRIC CO

Incident Narrative

ON JANUARY 6, 2023, AT 09:50, PG&E INCIDENT ON-CALL PERSONNEL CONFIRMED EXTENT OF CONDITION OF AN UNINTENTIONAL RELEASE OF GAS DUE TO A COMPLETELY SEVERED PIPE. ON JANUARY 5, AT APPROXIMATELY 06:22, A 4"" STEEL MAIN NEAR OUR FACILITIES IN SAN PABLO BROKE AS A RESULT OF NATURAL FORCE DAMAGE, EARTH MOVEMENT DUE TO HEAVY RAIN, RESULTING IN A GAS LEAK. PG&E CREWS CONDUCTED REPAIRS. THIS SECTION OF MAIN CROSSES THE HAYWARD FAULT LINE, AND GEOSCIENCES EXAMINED THE AREA. AFTER THEIR INSPECTION IT WAS DETERMINED THAT CREEP HAS LOADED THE PIPE SINCE IT WAS INSTALLED. BASED ON A NEARBY USGS MONITORING STATION, THE AREA WHERE THE FAILURE OCCURRED CREEPS AT A RATE OF ABOUT 5 MM/YEAR. THE PIPE RUPTURED AT A PARTIAL PENETRATION GIRTH WELD. THE ORIENTATION OF THE PIPE RELATIVE TO THE FAULT AND THE SENSE OF MOVEMENT ON THE FAULT CAUSES THE PIPE TO BE LOADED IN EXTENSION, WHICH IS CONSISTENT WITH THE SEPARATION OF THE PIPE THAT WAS OBSERVED AT THE BREAK. GIVEN THAT NO OTHER BREAKS OCCURRED WHERE DISTRIBUTION MAINS IN THE AREA INTERSECT THE HAYWARD FAULT, PG&E CONCLUDES THAT THE BREAK WAS DUE TO A COMBINATION OF HEAVY RAIN FALL AND LONG-TERM CREEP LOADING. A DETAILED ASSESSMENT OF HISTORICAL LEAKS IN THE AREA DID NOT SHOW A CORRELATION BETWEEN LEAKS IN THE AREA AND THE HAYWARD FAULT. NO MEDIA WAS REPORTED ONSITE. THE FIRE DEPARTMENT AND POLICE WERE ONSITE. NO FATALITIES OR INJURIES WERE REPORTED. THREE HOMES WERE EVACUATED, AND GAS SERVICE WAS INTERRUPTED FOR EIGHT CUSTOMERS AS PART OF THE ISOLATION STRATEGY. THIS INCIDENT WAS REPORTED TO DOT (NRC #1356987/ 1357066) AND CPUC ONCE IT WAS CONFIRMED THAT THE UNINTENDED GAS LOSS WAS OVER 3 MILLION CUBIC FEET.