CONSOLIDATED EDISON CO OF NEW YORK

Incident Narrative

ON TUESDAY MAY 22, 2012 GAS READINGS WERE RECEIVED IN THE VICINITY OF 24"" TRANSMISSION V-25962 LOCATED AT W 5 ST AND MUNDY LANE IN MT. VERNON (WL12004097). THE READINGS WERE RECEIVED DURING REPAIR OPERATIONS OF THE GEARING ASSOCIATED WITH THIS VALVE. IT WAS SUSPECTED A 1949 4"" LP STEEL DISTRIBUTION MAIN LOCATED 3' SOUTH OF THE TRANSMISSION MAIN WAS THE SOURCE OF THE READINGS. TRANSMISSION CONTINGENCY CASES 16-C, 16-D WERE IDENTIFIED AND AROUND-THE-CLOCK OPERATIONS CONTINUED TO PREPARE THE DISTRIBUTION MAIN FOR INSERTION TO ELIMINATE THE TRANSMISSION MAIN AS THE SOURCE OF THE LEAK. ON WEDNESDAY MAY 23, 2012, THE DISTRIBUTION MAIN WAS ISOLATED AND THE READINGS DID NOT DISSIPATE. THE CHEMICAL TESTING LAB RESPONDED AND THEIR ANALYSIS CONFIRMED THE PRESENCE OF NATURAL GAS. AN OPERATIONAL PLAN WAS DEVELOPED IDENTIFYING THE STEPS TO BE TAKEN TO ISOLATE THE SECTION OF TRANSMISSION MAIN INVOLVED AND REDUCE PRESSURE TO HIGH PRESSURE IN ORDER TO EXCAVATE AND FURTHER IDENTIFY THE SOURCE OF THE LEAK. OPERATIONS WERE DELAYED DUE TO A SECOND, UNRELATED LEAK ALONG THE ROUTE OF THE 24"" TRANSMISSION MAIN IN SCARSDALE, N.Y. WHICH WAS IMMEDIATELY STAFFED AND WORKED AROUND-THE-CLOCK IN ORDER TO ELIMINATE THE POSSIBILITY OF MULTIPLE SECTIONS OF THE TRANSMISSION SYSTEM BEING ISOLATED AT THE SAME TIME. THE SECOND LEAK WAS CONFIRMED ON THE DISTRIBUTION SYSTEM AT 18:00 AND THE OPERATIONAL PLAN ASSOCIATED WITH V-25962 REMAINED IN EFFECT. ON THURSDAY MAY 24, 2012 AT 07:17 ISOLATION OF THE AFFECTED SECTION OF TRANSMISSION MAIN WAS ACHIEVED AND PRESSURE REDUCED FROM 230 PSI TO 67 PSI PER PROCEDURE. AROUND-THE-CLOCK OPERATIONS CONTINUED AND EXCAVATION ACTIVITIES BEGAN FOR REPLACEMENT OF APPROXIMATELY 38' OF TRANSMISSION MAIN. ON SUNDAY MAY 27, 2012, AT 07:22 THE INSTALLATION OF 38' 2"" OF 24"" PIPE AND ALL WELDING WAS COMPLETED, TESTING PASSED AND PRESSURE RESTORATION BEGAN PER PROCEDURE. LEAK SURVEY MONITORED THE AFFECTED SECTION DURING RESTORATION ACTIVITIES AND NO LEAKS WERE FOUND AT 10:45 THE SECTION OF MAIN WAS FULLY ENERGIZED AND NORMAL SYSTEM CONDITIONS RESUMED (226 PSI). THERE WERE NO INJURIES, EVACUATIONS OR MEDIA ATTENTION ASSOCIATED WITH THIS INCIDENT. THE NYS PSC AND US DOT WERE NOTIFIED AND THE PSC RESPONDED TO LOCATION SEVERAL TIMES DURING THIS PROJECT. THIS WAS A SERIOUS LEVEL INCIDENT.