WASHINGTON – As part of its ongoing investigation into a March 12 gas explosion that destroyed two buildings in the East Harlem section of New York City, the NTSB today released an investigative update. The NTSB sent a go-team to the accident, and still has investigators on-scene.
The 8-inch cast iron/plastic main on Park Avenue between 116th and 117th streets failed the pressure test at the normal operating pressure. Tracer gas pumped into the main and a leak survey identified a leak adjacent to 1646 Park Avenue, one of the collapsed buildings.
Two service line segments (one about 20-feet long, the other about 3-feet long) recovered in the basements of the destroyed buildings at 1646 and 1648 Park Avenue have been removed and tagged as NTSB evidence. Items will be shipped to the NTSB laboratory in Washington.
Pressure testing of the service lines to buildings on Park Avenue adjacent to the destroyed buildings continues with no significant findings to date. ConEdison and the city are working to restore gas service to the adjacent buildings.
Work planned for the remainder of the week:
As the Fire Department recovery work permits the leak location will be excavated to expose the gas main pipe. Pipe segments will be marked, cut, removed and tagged as NTSB evidence; then shipped to the NTSB lab in Washington for further examination and testing. Undamaged pipe segments will also be shipped to the lab for comparison examination.
The segment of the cracked water main pipe in front of 1644 Park Avenue will also be cut and removed for shipment to the NTSB lab.
The City utility department is planning to run a camera probe inside the water and sewer pipes on Park Avenue between 116th and 117th streets. The videos will be added to NTSB accident docket as part of the evidence collection.
The NTSB investigation team with assistance from the parties, including ConEdison and the City, continue collecting gas system and water system operation, maintenance, and repair records for the vicinity of the explosion.
The investigation is ongoing. Any future updates will be issued as events warrant. Follow the investigation on Twitter at @NTSB, on our website at ntsb.gov or by signing up to receive NTSB news releases at www.ntsb.gov/registration/registration.aspx