PACIFIC GAS & ELECTRIC CO

Incident Narrative

ON AUGUST 31, 2011, AT 1228 HOURS, PG&E WAS NOTIFIED BY THE LOCAL FIRE DEPARTMENT OF A FIRE AT 20299 NORTHWEST SQUARE IN CUPERTINO. AROUND THIS SAME TIME, A PG&E GAS SERVICE REPRESENTATIVE (GSR) OBSERVED SMOKE WHILE DRIVING NEARBY AND WENT TO THE SCENE. THE GSR OBSERVED A HOUSE STRUCTURE ON FIRE AS WELL AS FLAMES IN THE LANDSCAPE AREA IN FRONT OF THE HOUSE. THE HOMEOWNER INDICATED SHE NOTICED THE SMELL OF GAS AT APPROXIMATELY 0800 HOURS THAT MORNING BUT DID NOT THINK MUCH ABOUT IT AND LEFT HER RESIDENCE AT APPROXIMATELY 1130 HOURS. THE HOMEOWNER DID NOT NOTIFY PG&E OF THE OBSERVED SMELL OF GAS. A GAS CONSTRUCTION CREW ARRIVED AT APPROXIMATELY 1251 HOURS, AND THE FLOW OF GAS WAS STOPPED BY EXCAVATING AND SQUEEZING THE PLASTIC MAIN AT THREE LOCATIONS. GAS SERVICE WAS INTERRUPTED TO SEVEN CUSTOMERS. SERVICE TO ONE AFFECTED RESIDENCE WAS RESTORED WHEN STRUCTURE REPAIRS WERE COMPLETED. SERVICE TO THE REMAINING SIX CUSTOMERS WERE RESTORED BY 1400 HOURS ON SEPTEMBER 1, 2011. EXCAVATION OF THE PLASTIC GAS DISTRIBUTION MAIN REVEALED A CRACK IN A 2-INCH ALDYL A PLASTIC TEE, WHICH WAS THE SOURCE OF THE GAS LEAK. THE TEE FAILED AS A RESULT OF STRESS RISERS FORMED IN THE TEE MATERIAL FROM THE STEPWISE INCREASE IN WALL THICKNESS WHERE THE COUPLING AND SERVICE PIPE FIRST BOND. THE FRACTURE PROPOGATED BY SLOW CRACK GROWTH DRIVEN BY THE SYSTEM PRESSURE. GAS FROM THE LEAKING TEE MIGRATED UNDERGROUND TO THE GARAGE OF THE RESIDENCE AND CAUGHT FIRE FROM THE PILOT LIGHT OF THE FURNACE IN THE GARAGE. PG&E CONDUCTED LEAK SURVEYS AT THE 422 TOWNHOUSE COMPLEX WHERE 20299 NORTHWEST SQUARE IS LOCATED IN APRIL AND MAY OF 2011. A REVIEW OF THE LEAK SURVEY RECORDS DID NOT REVEAL ANY ISSUES AT THIS RESIDENCE, ALTHOUGH THERE WERE LEAKS DETECTED IN OTHER AREAS OF THE COMPLEX. LEAK SURVEYS WERE CONDUCTED FOLLOWING THE INCIDENT, AND SIX LEAKS WERE IDENTIFIED AND REPAIRED THROUGHOUT THE COMPLEX. THERE WERE NO INJURIES OR FATALITIES. HOWEVER, DAMAGE TO THE HOUSE STRUCTURE EXCEEDS $50,000, MAKING THIS INCIDENT REPORTABLE. IN ADDITION, MAJOR BAY AREA TV MEDIA WAS ON THE SCENE.