SOUTHWEST GAS CORP

Incident Narrative

PL 2014-0244 SOUTHWEST GAS CORPORATION (SWG) RESPONDED TO A REPORTED FIRE AT 1914 EAST PALOMINO DRIVE IN GILBERT CALLED IN BY THE GILBERT FIRE DEPARTMENT AT 18:20. UPON ARRIVAL SERVICE TECHNICIAN WAS ADVISED THAT AN EXPLOSION HAD OCCURRED AND ONE PERSON WAS TRANSPORTED TO THE HOSPITAL WITH BURNS. SWG CREWS RESPONDED AND CONTROLLED THE FLOW OF GAS BY SQUEEZING A 2-INCH PE MAIN. NOTIFICATION WAS MADE TO PHMSA VIA THE NATIONAL RESPONSE CENTER (NRC) REPORT NUMBER 1073454 AT 19:35 OF THE IN-PATIENT HOSPITALIZATION. THERE WERE NO FATALITIES AS A RESULT OF THE INCIDENT. FURTHER INVESTIGATION INTO THE INCIDENT FOUND THE LEAK TO HAVE OCCURRED ON A 1"" PE SERVICE STUB. THE CAUSE OF THE LEAK ON THE 1"" PE LINE REMAINS UNDER INVESTIGATION. A SUPPLEMENTAL REPORT WILL BE SUBMITTED UPON COMPLETION OF THE INVESTIGATION BY SWG. NOTE: FOR PART A, #10, THE ESTIMATED VOLUME OF GAS RELEASED THAT IS IDENTIFIED REPRESENTS AN ESTIMATE THAT PRESUMES A CRACK THAT IS LEAKING AT 57 PSI, BEGINNING AT THE TIME OF THE INTIAL REPORT OF THE INCIDENT AND ENDING AT THE TIME THE PIPELINE WAS SHUT DOWN. HOWEVER, THE ACTUAL AMOUNT OF GAS LOSS IS UNKNOWN BECAUSE THE TIME THE GAS PIPELINE BEGAN LEAKING IS UNKNOWN. SUPPLEMENTAL REPORT: LABORATORY ANALYSIS SHOWS THAT THE LEAKS WERE PRESENT DUE TO THERMAL OXIDATION OF THE PIPES AT 1914 AND 1924 E. PALOMINO. THE THERMAL OXIDATION OF THE PIPES RESULTED IN AXIAL SLIT-CRACKS ON THE PIPES AT BOTH LOCATIONS. SECTION G5 IS REVISED TO REFLECT THIS FACT.