CONSOLIDATED EDISON CO OF NEW YORK

Incident Narrative

ON NOVEMBER 5, 2012 WESTCHESTER GAS OPERATIONS PERFORMED A 30-DAY LEAK FOLLOW-UP INSPECTION AT 100 FISHER AVENUE, WHITE PLAINS, NEW YORK AND DETECTED 24% IN THE VALVE BOX 24"" 230 PSI TRANSMISSION MAIN VALVE 25971. WESTCHESTER GAS OPERATIONS, GAS ENGINEERING AND GAS CONTROL WERE NOTIFIED. GAS CONSTRUCTION RESPONDED AND INVESTIGATED OVER THE MAIN AND DETECTED 41% OVER THE TRANSMISSION MAIN 4' WEST OF THE VALVE BOX. THE READINGS VENTED TO 5%-10% RANGE AND NO MIGRATION BEYOND THE STREET WAS DETECTED. ALL SUBSURFACE STRUCTURES AND BUILDINGS INVESTIGATED WERE FOUND GAS FREE. CONTINGENCY W12-151, CASE 38B AND 38C WERE PLACED IN EFFECT. GAS ENGINEERING RESPONDED TO LOCATION WITH WESTCHESTER GAS TO DETERMINE A COURSE OF ACTION. AN OPERATIONAL PLAN WAS DEVELOPED AND AROUND-THE-CLOCK OPERATIONS BEGAN FOR THE REPLACEMENT OF APPROX. 320' OF TRANSMISSION MAIN FROM WEST OF V-25971 EAST TO THE INLET OF TRANSMISSION-MEDIUM PRESSURE REGULATOR STATION GR-512. TWO REMOTE OPERATED VALVES (ROVS) WERE OPERATED BY GAS CONTROL TO ENSURE THERE WAS NO IMPACT TO THE GAS SYSTEM. ADDITIONALLY, (5) 24"" COMPRESSION COUPLING WERE IDENTIFIED, EXCAVATED AND PREPARED FOR THE WELDED REPAIR SLEEVE INSTALLATION AS A PREEMPTIVE MEASURE. ON NOVEMBER 10, 2012 AT 10:44 A VISIBLE LEAK ON A 24"" COMPRESSION COUPLING LOCATED 124' WEST OF V-25971 WAS REPORTED. GAS CONTROL WAS NOTIFIED AND AT 10:59 ORDERED CONTINGENCY V-32715 CLOSED. AT 11:15 THE VALVE WAS REPORTED TO BE IN THE FULLY CLOSED POSITION. THE PRESSURE IN THE AFFECTED SEGMENT OF MAIN AT TIME OF DISCOVERY OF THE LEAK WAS 233 PSI. THE SEGMENT OF MAIN WAS ISOLATED AND THERE WAS NO GAS SYSTEM IMPACT AS A RESULT OF THE ISOLATION. AROUND-THE-CLOCK OPERATIONS CONTINUED UNTIL THE WELDED SLEEVE WAS INSTALLED OVER THE LEAKING COUPLING TO SECURE THE LEAK ON NOVEMBER 12, 2012 AT 15:43. ON 11-20-12 AT 06:21 OPERATIONS ASSOCIATED WITH REPLACEMENT PROCEDURE MPC-12-46 COMMENCED. ON NOVEMBER 21, 2012 AT 07:43 OPERATIONS WERE COMPLETED AND V-32715 WAS OPENED AND PRESSURE WAS RAISED INCREMENTALLY. AT 08:17 THE VALVE WAS REPORTED FULLY OPENED AND PRESSURE IN THE AFFECTED SEGMENT WAS RETURNED TO 230 PSI. LEAK SURVEY CHECKED DURING INCREMENTAL PRESSURE INCREASES DURING THE RESTORATION PROCESS AND NO LEAKS WERE FOUND. GAS CONTROL REPORTED AT 08:37 THE SYSTEM WAS RETURNED TO NORMAL OPERATING CONDITIONS. THE US DOT AND NYS PSC WERE NOTIFIED.