CONSOLIDATED EDISON CO OF NEW YORK

Incident Narrative

ON JUNE 28, 2012 WESTCHESTER GAS DISTRIBUTION SERVICES (GDS) WAS PERFORMING A FOLLOW UP LEAK INSPECTION AT THIS LOCATION AND DISCOVERED 17% IN A MANHOLE APPROXIMATELY 43' WEST OF 12"" TRANSMISSION PRESSURE V-25873 LOCATED AT TARRYTOWN ROAD AND YELLOWSTONE AVENUE IN GREENBURGH, WESTCHESTER COUNTY, NY. THE MANHOLE CONTAINED A 12"" ORIFICE METER AND ASSOCIATED FITTINGS. A 16"" HIGH PRESSURE MAIN IS LOCATED 6' NORTH OF THE TRANSMISSION MAIN, AND DIRT AND MATERIALS IN THE MANHOLE NEEDED TO BE REMOVED TO INVESTIGATE THE SOURCE OF THE LEAK. A CONTINGENCY CASE WAS INITIATED AND ISOLATION VALVES WERE IDENTIFIED AND STAFFED. THE MANHOLE WAS VENTED AND A VACUUM TRUCK WAS ASSIGNED TO REMOVE MATERIALS IN THE MANHOLE. THE SEGMENT OF MAIN WAS ISOLATED AFFECTING SUPPLY TO GR-519 AND GR-516. THE PRESSURE WAS REDUCED IN THE AFFECTED SEGMENT TO 60 PSI WITHOUT INCURRING ANY INTERRUPTIONS OR SYSTEM IMPACT. GDS MONITORED THE LOCATION OVERNIGHT AND NO READINGS WERE OBTAINED, AND NO ODOR WAS PRESENT. ON JUNE 29, 2012 OPERATIONAL PLANNING CONTINUED AND ADDITIONAL VALVE CLOSURES WERE SUCCESSFUL IN ISOLATING THE SEGMENT OF TRANSMISSION MAIN. PRESSURE CONTROL SUCCESSFULLY REDUCED PRESSURE TO 30 PSI, AND AT 12:06 (2) MINOR LEAKS WERE CONFIRMED ON THE TRANSMISSION MAIN IN THE MANHOLE ON ORIFICE METER FITTINGS. THE PRESSURE WAS FURTHER REDUCED TO APPROXIMATELY 8 PSI AND THEN AGAIN TO APPROXIMATELY 1 PSI. OPERATIONAL PROCEDURE MPC-12-21 WAS DEVELOPED AND A TOTAL OF 210' OF NEW TRANSMISSION MAIN AND A NEW 12"" ROV-59278 WERE INSTALLED. ON JULY 19, 2012 AT 03:48 THE TRANSMISSION SYSTEM WAS RETURNED TO NORMAL OPERATING CONDITIONS. THE NYS PSC AND US DOT WERE NOTIFIED. THIS WAS A SERIOUS LEVEL INCIDENT.