CONSOLIDATED EDISON CO OF NEW YORK — Gas distribution — incident on 2009-04-24

Gas distribution incident in FLORAL PARK, QUEENS County, NY. Reported cause: 24. Reported consequences: 1 fatalities, 0 injuries, $500,000 reported property damage. Operator-reported incident data submitted to PHMSA, generally within 30 days. Records may be supplemented or corrected and do not represent final agency causal findings.

Report number: 20090102.

Operator ID: 2704.

Reported incident date: 4/24/2009.

Cause detail: MISCELLANEOUS

Cause detail: ON FRIDAY, APRIL 24, 2009, AT APPROXIMATELY 4:50 P.M., AN EXPLOSION OCCURRED IN A SINGLE FAMILY HOME AT 80-50 260TH STREET, BETWEEN 80TH AND 81ST AVENUES, IN FLORAL PARK, QUEENS. THERE WAS ONE FATALITY; ONE REPORTED INJURY TO A MEMBER OF THE PUBLIC; AND MINOR INJURIES TO NINE FIRE DEPARTMENT OF NEW YORK (FDNY) FIREFIGHTERS AS A RESULT OF THEIR RESCUE EFFORTS. AT 3:2 1 P.M., ON APRIL 24TH A CON EDISON CUSTOMER AT 80-46 260TH STREET REPORTED THAT HE WAS EXPERIENCING PARTIAL LIGHTS IN HIS HOME. AT 3:34 P.M., THE SAME CUSTOMER REPORTED A STRONG ODOR OF GAS OUTSIDE HIS RESIDENCE. A COMPANY MECHANIC WAS DISPATCHED TO THE LOCATION AT 3:56 P.M. AND ARRIVED THERE AT 4:05 P.M. HE THEN BEGAN TESTING THE STREET AREA AND MANHOLES. THE COMPANY MECHANIC FOUND HIGH LEVELS OF NATURAL GAS IN TWO SEWER MANHOLES IN THE VICINITY OF 80-50 260TH STREET, QUEENS; AND HE CALLED FOR ASSISTANCE. CON EDISON DISPATCHED BACKUP MECHANICS AND THEY ARRIVED AT THE SITE AT 4:42 P.M. AT APPROXIMATELY 4:50 P.M., AN EXPLOSION AND FIRE OCCURRED AT THE HOME LOCATED AT 80-50 260TH STREET, WHICH WAS ADJACENT TO 80-46 260 STREET. THE 2 INCH, HIGH-PRESSURE STEEL GAS MAIN, LOCATED ON THE EAST SIDE OF 260" STREET, BETWEEN 80 AVENUE AND 81 AVENUE, WAS ISOLATED BY GAS OPERATIONS AT 5:05 P.M. BY CLOSING FOUR (4) VALVES. THE GAS MAIN ON 259 STREET WAS SHUT DOWN AT THE REQUEST OF THE FDNY DUE TO A FIRE IN THE ADJACENT HOMES AND AT 80-49 259 STREET (THE HOME BEHIND 80-50 260M STREET). AT 5:41 P.M., THE FDNY EVACUATED A11 21 HOMES ON 260TH STREET FOR SAFETY. THE GAS MAIN ON 259TH STREET WAS SHUT DOWN BY GAS OPERATIONS AT 6: 10P.M. BY OPERATING TWO (2) VALVES. AS A RESULT OF THE GAS MAIN ISOLATIONS, FIFTY GAS CUSTOMERS WERE INTERRUPTED. AT 6: 17 P.M., ALL SEWER MANHOLES WERE FOUND TO BE GAS FREE. AT 7:25 P.M., ELECTRIC EMERGENCY CREWS COMPLETED THE ISOLATION OF THE ELECTRIC SUPPLY ON BOTH AFFECTED STREETS. ON SATURDAY, APRIL 25 &, AT 12:01 A.M., THE ELECTRIC SERVICE WAS RESTORED BY THE COMPANY TO ALL CUSTOMERS ON 259 STREET, AS WELL AS TO THE CUSTOMERS ON 260TH STREET, WHOSE HOMES HAD NOT SUSTAINED DAMAGE. THE ELECTRIC SERVICE REMAINED OFF TO THE HOMES AT 80-46, 80-50, AND 80-54 260 STREET. THE ATMOSPHERE IN ALL BUILDINGS ON 259 AND 260TH STREETS WAS RECHECKED BY THE COMPANY TO CONFIRM THAT THERE WAS NO GAS, AND AT 12: 18 A.M. THE EVACUATION WAS ENDED. THERE WAS NEWS MEDIA ON LOCATION. AS PART OF THE INCIDENT INVESTIGATION, THE COMPANY RETAINED THE SERVICES OF LUCIUS PITKIN, INC. (LPI), AN INDEPENDENT, FAILURE ANALYSIS ENGINEERING CONSULTANT. SECTIONS OF THE TWO (2) INCH, HIGH PRESSURE GAS MAIN, THE GAS SERVICE LINE SUPPLYING 80-50 260TH STREET, THE TWO (2) INCH STEEL ELECTRIC CONDUIT AND THE ELECTRIC SERVICE CABLES SUPPLYING 80-46, 80-50, AND 80-54 260TH STREET, WERE EVALUATED. LPI FOUND A DIME-SIZED HOLE AT THE 12 O'CLOCK POSITION ON THE TWO (2) INCH, HIGH-PRESSURE STEEL GAS MAIN. THE GAS MAIN WAS SITUATED APPROXIMATELY FOUR FEET WEST OF THE EAST CURB OF 260TH STREET AN APPROXIMATE DEPTH OF THREE (3) FEET. THE TWO (2) INCH, STEEL ELECTRIC CONDUIT AND THE GAS MAIN WERE FOUND IN CLOSE PROXIMITY WHEN THEY WERE EXCAVATED AND EXPOSED AFTER THE INCIDENT. THE HOLE IN THE GAS MAIN WAS LOCATED AT A POINT WHERE IT PASSED UNDER THE TWO (2) INCH, STEEL ELECTRIC CONDUIT HOUSING THE ELECTRIC SERVICE CABLES SUPPLYING 80-46, 80-50, AND 80-54 260TH STREET. THE STEEL ELECTRIC CONDUIT HAD A CORRESPONDING HOLE IN THE 6 O'CLOCK POSITION WHERE IT CROSSED THE STEEL GAS MAIN, THE ELECTRIC SERVICE CABLES FAILED IN AN AREA APPROXIMATELY 19 FEET WEST (TOWARDS 80-50 260THSTREET) FROM THE LOCATION WHERE THE ELECTRIC CONDUIT AND GAS MAIN CROSSED. THE GAS MAIN, INSTALLED IN 1950, WAS FOUND TO BE IN GOOD CONDITION WITH NO CORROSION, SUITABLE FOR HIGH PRESSURE GAS SERVICE. LPI HAS DETERMINED THAT A FAULT IN THE ELECTRIC SERVICE CABLES MOST LIKELY ORIGINATED IN AN AREA THAT WAS APPROXIMATELY 19 FEET FROM THE LOCATION WHERE THE GAS MAIN AND ELECTRIC CONDUIT PASSED IN CLOSE PROXIMITY. AT THE FAULT LOCATION, THE TWO (2) INCH, STEEL CONDUIT WAS BENT UPWARD AND A COUPLING BETWEEN TWO PIECES OF CONDUIT HAD BEEN COMPROMISED BY CORROSION AND CONDUIT DEFORMATION. THE ELECTRIC FAILURE CAUSED FAULT CURRENT TO FLOW INTO THE STEEL ELECTRIC CONDUIT, WHICH ARCED ONTO THE NEARBY TWO (2) INCH, HIGH-PRESSURE STEEL GAS MAIN. THE ARCING FROM THE CONDUIT TO THE GAS MAIN CREATED HOLES IN BOTH THE ELECTRIC CONDUIT AND THE GAS MAIN. THE ARCING ALSO CAUSED LOCALIZED DAMAGE TO THE INSULATION AND ONE CONDUCTOR OF THE ELECTRIC SERVICE CABLES. IN AREAS UNAFFECTED BY THE ORIGINAL FAULT OR THE ARCING, THE ELECTRIC SERVICE CABLES WERE IN ACCEPTABLE CONDITION, ADEQUATE FOR ELECTRIC SERVICE TO THE HOMES. ONCE THE ARC CREATED THE HOLE IN THE GAS MAIN, THE ESCAPING GAS TRAVELLED THROUGH PREFERENTIAL ROUTES IN THE SOIL AND SUBSURFACE FACILITIES, ULTIMATELY ACCUMULATING IN THE HOUSE. THE EXTERIOR OF THE ELECTRIC CONDUIT EXHIBITED DAMAGE THAT APPEARS TO HAVE RESULTED FROM PAST EXCAVATION ACTIVITIES. WE HAVE LEARNED THAT THE ELECTRIC AND GAS FACILITIES ON 260TH STREET WERE EXPOSED IN 1987 AS PART OF A CONSTRUCTION PROJECT TO INSTALL WATER AND SEWER MAINS BENEATH THE ELECTRIC AND GAS SERVICES. THE ELECTRIC AND GAS SERVICES, LOCATED AT AN APPROXIMATE DEPTH OF THREE (3) FEET, WERE EXPOSED A SECOND TIME IN 2000, WHEN THE ROADWAY ON 260TH STREET WAS EXCAVATED TO APPROXIMATELY A FIVE (5) FOOT DEPTH BY AN INDEPENDENT CONTRACTOR RECONSTRUCTING THE ROADWAY. THE DAMAGE TO THE ELECTRIC CONDUIT IN THE AREA OF THE ORIGINAL FAULT AND THE POSSIBLE MOVEMENT OF THE ELECTRIC CONDUIT AND GAS MAIN IN THE AREA OF CLOSE PROXIMITY WHERE THE ARCING OCCURRED MAY HAVE BEEN CAUSED WHEN THE EXCAVATION WORK WAS PERFORMED IN 1987 OR 2000.

PHMSA trend classification: significant incident, serious incident, not fire-first.

PHMSA standardized cause: ALL OTHER CAUSES — MISCELLANEOUS.

PHMSA indexed costs: $500,000 reported total cost, $275,961.438 in 1984 dollars, $679,608.09 in current-year dollars.

PHMSA trend flags, standardized causes, and indexed costs are analytical fields added to operator-reported incident data. They do not represent final agency causal findings.