New York, NY – A federal investigation into the East Harlem explosion that killed eight people just over a year ago appears to focus on the connection of a natural gas line with a main running along Park Avenue, according to documents released Wednesday.
Investigators found that a T-shaped connector joining a plastic service line to a plastic main had separated at 1642 Park Ave., according to the documents from the National Transportation Safety Board, which is still investigating the blast that occurred on March 12, 2014. Service lines deliver gas to buildings.
An NTSB spokesman declined to comment on the documents, which included no conclusions from investigators.
The safety board hasn’t released its final report spelling out what it believes led to the gas leak and subsequent explosion, which leveled two five-story apartment buildings, killed eight residents and injured dozens of others.
Crews installed the 2-inch-diameter service line in December 2011. The service line had been connected to a main along Park Avenue between East 116th and East 117th Streets.
This is going to leak a lot of gas, Richard Kuprewicz, president of the pipeline-safety consulting firm Accufacts Inc. in Redmond, Wash., said of the separation after reviewing the documents. Plastic gas service lines should not be separating from gas mains, especially newer installations.
The documents indicate that the NTSB has been looking into how the service line and connector were installed and what might have caused them to separate.
One focus of the investigation centers on the contractor that installed the line for the utility Consolidated Edison Inc.
The contractor’s employee who installed the 69-foot segment of plastic main and plastic service line had 15 years of experience working with such pipes, the NTSB documents show.
But the worker’s three-year qualification allowing him to fuse pipes with ConEd had expired in November 2013, roughly four months before the explosion. He was, however, qualified to fuse pipes for National Grid, another large gas utility in New York City.
In an interview with federal investigators, a ConEd official said employees aren’t told when their qualification cards lapse and the official said the employee learned of his unqualified status after the accident, the documents said.
The contractor, Hallen Construction, and its attorney, Thomas J. Hall, didn’t respond to requests for comment Wednesday.
Between July 2009 and June 2014, 186 ConEd employees and 115 contractors had lapses in their operator qualifications at different times, according to ConEd records reviewed by the NTSB.
ConEd said it was prohibited from commenting until the NTSB concludes its investigation.
We look forward to the completion of the investigation, which will provide a full picture of what occurred, the utility said. In the meantime, we have been implementing many new initiatives to enhance public safety and increase public awareness.
Mr. Kuprewicz, the pipeline-safety consultant, said it was too soon to conclude the pipe was improperly installed. It doesn’t necessarily mean they did it wrong, he said.
The NTSB also has looked into a water main break at the blast site. It wasn’t initially clear whether the water main break preceded or was the result of the explosion.
City inspections of the water main system didn’t indicate any leaks as early as a week before the explosion, the NTSB documents show.
City transportation employees had identified and repaired a roadway depression in front of 1644 and 1646 Park Ave. on March 9, 2014, a few days before the explosion, the documents show.
Regulations also have been a focus for the NTSB.
The segment of 8-inch-diameter plastic main along Park Avenue wasn’t pneumatically pressure-tested when it was installed because it was less than 100 feet long, a decision in compliance with state pipeline regulations but contrary to federal regulation, NTSB documents show.
The new main was visually inspected and tested for leaks in a process involving a soap solution, NTSB documents show.