ORANGE & ROCKLAND UTILITY INC

Incident Narrative

CONTRACTOR RAINES & WELSH (R&W) WAS AWARDED THE CONTRACT TO UPGRADE THE LOW PRESSURE SYSTEM TO HIGH PRESSURE GAS MAINS AND SERVICES IN NYACK. THE WORK INCLUDED RETIRING AND IN SOME CASES REMOVING THE EXISTING LOW PRESSURE FACILITIES. R&W BEGAN WORK ON THE PROJECT IN SEPTEMBER 2011. ON THE DAY OF THE INCIDENT R&W WAS RETIRING A SECTION OF 12 INCH LOW PRESSURE STEEL GAS MAIN ON BROADWAY AT 1ST STREET IN WEST NYACK. THE 12 INCH MAIN RUNS NORTH AND SOUTH ON BROADWAY AND HAD A RADIAL 4 INCH LOW PRESSURE STEEL MAIN COMING OFF TO THE WEST ON 1ST ST. R&W EXCAVATED AND EXPOSED THE 12 INCH AND 4 INCH MAIN. THE BALLOON STOPPERS WERE INFLATED TO 4 PSI TESTED FOR LEAKAGE AND HELD PRESSURE FOR OVER ONE HOUR BEFORE BEING USED. THEY INSTALLED TWO TAPPING TEES AND FOUR LOW PRESSURE BALLOON STOPPERS INTO THE 12 INCH PIPE AT THE LOCATIONS SHOWN ON THE SKETCH. THE 4 INCH MAIN HAD PREVIOUSLY BEEN DEAD ENDED WITH A CAP FURTHER WEST ALONG 1ST STREET AND DID NOT REQUIRE ANY STOPPERS. R&W THEN PERFORMED A FLOW TEST TO CONFIRM THAT GAS WAS BEING SUPPLIED TO THE MAIN NORTH AND SOUTH OF THE ISOLATED SECTION. THE PRESSURE GAUGES ON THE BALLOON STOPPERS WERE CHECKED TO CONFIRM THAT THE STOPPERS WERE HOLDING AND THAT THE SECTION WAS EFFECTIVELY ISOLATED. R&W CUT THE 12 INCH PIPE ON THE NORTH END OF THE EXCAVATION WITH A REED 4 WHEEL PIPE CUTTER. THEY THEN MADE TWO CUTS WITH A DEMO SAW ON THE 4 INCH STEEL MAIN, REMOVING A 4 INCH RING. R&W USED AN ORBITAL CUTTER AND TORCH TO BEVEL CUT THE SOUTH SIDE OF THE 12 INCH MAIN. THE CREW MADE A SECOND CUT AND REMOVED ABOUT A 4 INCH RING AT THE SOUTHERLY END OF THE 12 INCH PIPE. WHEN THE RINGS WERE CUT R&W HAD SUFFICIENT CLEARANCE AND THE CUT OUT SECTION WAS REMOVED FROM THE EXCAVATION. R&W SET UP THE ORBITAL CUTTER TO BEVEL THE ROUGH CUT ON THE NORTH END OF THE 12 INCH MAIN. THE CONTRACTOR'S WELDER AND CREW FOREMAN WERE IN THE EXCAVATION AND BEGAN TO MAKE THE BEVEL CUT. AT 16:28, WHEN THEY HAD FLAME CUT APPROXIMATELY 8 INCHES OF THE CIRCUMFERENCE, THE NORTHERLY BALLOON STOPPERS FAILED AND THE LEAKING GAS IGNITED. BOTH MEN EXITED THE EXCAVATION AND WERE NOT INJURED BY THE IGNITION OR THE ENSUING GAS FED FIRE. THE THREE REGULATOR STATIONS SUPPLYING THE AFFECTED AREA WERE TURNED OFF AND THE RESIDUAL GAS BURNED OFF. APPROXIMATELY 385 GAS SERVICES WERE INTERRUPTED. OVERHEAD ELECTRIC FACILITIES IN THE AREA WERE DE-ENERGIZED INTERRUPTING APPROXIMATELY 650 SERVICES. ELECTRIC SERVICE WAS RESTORED AT APPROXIMATELY 20:40 THAT EVENING. GAS CONSTRUCTION INSTALLED COMPRESSION CAPS ON THE 12 INCH OPEN ENDS AND A WOODEN PLUG IN THE DEAD 4 INCH MAIN. O&R SERVICE MECHANICS ALONG WITH CECONY GDS CREWS WORKED AROUND-THE-CLOCK TO RESTORE GAS SERVICE TO THE AFFECTED CUSTOMERS. GAS SERVICE WAS FULLY RESTORED AT 18:00 ON 6/24/12