PHILADELPHIA GAS WORKS

Incident Narrative

ON JANUARY 18TH, 2011 PGW RECEIVED A PHONE CALL AT 19:28 FROM THE PHILADELPHIA FIRE DEPARTMENT REPORTING A STRONG ODOR OF GAS IN THE INTERSECTION OF TORRESDALE (6900 BLOCK) AVENUE AND DISSTON (4600 BLOCK) STREET. PGW DISPATCHED FIRST RESPONDERS AT 19:29, WITH THE FIRST PGW EMPLOYEE ARRIVING ON LOCATION AT 19:38. UPON ARRIVAL, PGW PRELIMINARILY IDENTIFIED A SIGNIFICANT LEAK ON A DISTRIBUTION MAIN OPERATING AT 18 PSIG (10-35 PSIG MAOP). AT 20:00, PGW CALLED IN RESOURCES TO START AN EMERGENCY SHUT DOWN. ADDITIONAL RESOURCES CONTINUED TO ARRIVE AND STARTED LEAK MIGRATION AND HOUSE CHECKS ALONG THE 6900 BLOCK OF TORRESDALE. WITH THE ASSISTANCE OF THE PFD, PGW BEGAN FORCED ENTRY PROCEDURES AND EVACUATIONS OF RESIDENTS. PGW RECORDED ATMOSPHERIC READINGS IN SEVERAL HOUSES DURING THE HOUSE CHECKS. WHEN THE FIRST DISTRIBUTION CREW ARRIVED (20:10), PGW MADE BAR HOLES TO VENTILATE THE GAS AND LOCATE THE LEAK. AT 20:35, A PGW SUPERVISOR REPORTED AN EXPLOSION AND FIRE AT 6932 TORRESDALE AVENUE. AFTER CLOSURE OF THE ISOLATION VALVES THE GAS FIRE SUBSIDED. THE PFD EXTINGUISHED THE REMAINING FIRES. PGW ALSO GREASED OFF THE 6"" LP CI MAIN ON TORRESDALE CROSSING THE INTERSECTION OF DISSTON STREET. THE SOUTH END WAS GREASED OFF THRU THE SERVICE AT 6924 TORRESDALE; AND THE NORTH END WAS GREASED OFF THROUGH THE MAIN. FSD PULLED A HEAD OF SERVICE PLUG ON BUILDING 6926 TO CONFIRM THE LINE WAS DEACTIVATED. WITH THE 6"" MAIN (1/4 PSIG) MAIN DEACTIVATED AND THE 12"" (10-35 PSIG) MAIN DEACTIVATED, HOUSES VENTILATED, THE JOB WAS DECLARED 'MADE SAFE' AT 22:40. PGW MADE EXCAVATIONS TO PHYSICALLY CUT AND CAP THE 12"" MAIN AND 6' MAIN. THE 6"" MAIN WAS CUT AND CAPPED ON 1/19/11 AT 03:25. THE 12"" MAIN WAS CUT AND CAPPED ON AT 05:30. ON 01/19/11 PGW INSERTED A CAMERA INSIDE THE CUT & CAPPED 12"" CI MAIN FROM 25' EEC MARSDEN ST TO 35' WWC TORRESDALE AVENUE. THE MAIN WAS CLEAN, NO SIGNS OF PITTING AND THE MECHANICAL JOINTS WERE INTACT. WITH THE CAMERA THE BROKEN MAIN WAS LOCATED AT 29' 4"" WWC TORRESDALE AVENUE & 3'6"" NSC DISSTON STREET PGW EXCAVATED THE AREA WHERE THE BROKEN MAIN WAS LOCATED. THE GROUND WAS SOLID CLAY IN THE ROADWAY, NO SIGNS OF ANY VOIDS. THE BREAK WAS CIRCUMFERENTIAL AND APPEARED TO BE A COMPLETE BREAK, AND THE MAIN WAS STILL IN ALIGNMENT, NO INDICATION THAT THE MAIN HAD DROPPED. PGW EXCAVATED THE AREA WHERE THE BROKEN MAIN WAS LOCATED. THE GROUND WAS SOLID CLAY IN THE ROADWAY, NO SIGNS OF ANY VOIDS. THE BREAK WAS CIRCUMFERENTIAL AND APPEARED TO BE A COMPLETE BREAK, AND THE MAIN WAS STILL IN ALIGNMENT, NO INDICATION THAT THE MAIN HAD DROPPED. THE AREA EXCAVATED CONSISTED OF MACADAM WITH AN OVERLAY OF ASPHALT WITH A STONE BASE. THERE WAS NO CONCRETE BASE IN THE ROADWAY. THE DIRT WAS SOLID CLAY AND NO FROST WAS DETECTED IN THIS OPENING. THE SOIL AROUND THE PIPE WAS UNDISTURBED CLAY, VERY MOIST. THE GROUND WAS SOLID WITH NO SIGNS OF CAVITY, VOID OR UNDERMINING CONDITIONS OR DEPRESSIONS SUPPORTING THE PIPE. THE DIRT AROUND THE BREAK HAD EQUAL MOISTURE AS THE SURROUNDING SOIL. PGW EXCAVATED ALONG BOTH SIDES OF THE MAIN AND LEFT THE DIRT UNDER THE MAIN, NOT TO DISTURB IT. THERE WERE NO OBVIOUS SIGNS OF ANY GRAPHITIZATION, PITS, PLUGS, OR HOLES. THERE WERE NO OTHER TYPES OF FITTINGS IN THIS OPENING. THE EXCAVATION WAS PREPARED TO ALLOW A 6' SECTION TO BE REMOVED WITH THE BREAK IN THE MIDDLE. THE MAIN WAS HAND DUG AND SCALED. THE PIPE WAS SCALED ONLY IN THE AREAS OF THE CUT. THE REMAINDER OF THE REMOVED SECTION WAS ONLY CLEANED, NOT SCALED. A STAINLESS STEEL SLEEVE WAS INSTALLED ON THE BREAK AREA; IT WAS A COMPLETE CIRCUMFERENTIAL BREAK. THE MAIN WAS MARKED EAST, WEST AND TOP. PICTURES WERE TAKEN DURING THE REMOVAL. THE REMOVED MAIN IS SCHEDULED TO BE TRANSPORTED TO A LABORATORY FOR A COMPLETE METALLURGICAL EXAMINATION.