MARCH 18, 2015
Federal investigators studying the deadly gas explosion that
leveled two buildings in East Harlem a year ago are focusing on the plastic pipes
that Consolidated Edison installed beneath Park Avenue three years before the
blast, documents released on Wednesday revealed.
The National Transportation Safety Board posted more than
3,000 pages of documents related to the investigation on its website. The
safety board’s conclusions about what caused the explosion, which left eight
people dead and many others injured, are expected in a final report in a few
months.
The block of Park Avenue where the explosion occurred had
been served for more than 120 years by an eight-inch gas main made of cast
iron. But Con Edison replaced a 69-foot section of that main with a plastic
pipe in 2011. The utility connected that new section to 1642 Park Avenue, one
of the buildings destroyed, with a smaller plastic pipe.
One of the documents released said investigators had
injected traceable gas into the main to locate any leaks. They found high
concentrations of the gas had escaped into the ground in front of 1642 Park at
a point where the main was new plastic, not part of the old iron pipe,
according to the document.
They also found that the smaller plastic pipe, known as a
service line, had separated from the plastic main. State regulators found last
year that Con Edison’s foreman on the installation of the plastic pipes thought
that he was up-to-date on his qualifications to do that work, one report said.
“But he was not,” it added.
The foreman told investigators that the section of
replacement pipe had not been “pneumatically pressure-tested” for leaks when it
was installed, contrary to federal regulations. He explained that New York
State waives that rule for lengths of pipe under 100 feet. Instead, the pipe
was inspected visually and checked for leaks with a soap solution.
The documents gave no indication that the decision not to
test the pipe under high pressure was a factor in the explosion.
After the blast, state regulators found that about 70
percent of Con Ed’s pipe fitters had not kept their qualifications current. The
company agreed to retrain all of the workers involved in the installation and
maintenance of its network of gas mains, which serve 1.1 million customers.
The NTSB documents provide the first look at the underground
pipes at the center of the investigation into last year's deadly building
explosion in East Harlem.
One picture shows a space between the connector that links
the gas main in the street and the line that delivered gas to a nearby
building. Another shows a separate crack in that connector itself.
The explosion leveled 1644 and 1646 Park Avenue last year,
killing eight people and injuring nearly 50 others.
Investigators also revealed that city transportation crews
conducted road work in front of the buildings just days before the blast after
finding a depression in the street.
There are also new details on the critical minutes before
the explosion. Documents show that a neighbor called Con Ed at 9:06 a.m. to
report a gas odor, but the customer service rep's computer froze. The
information was finally entered at 9:13, and a Con Ed mechanic was dispatched
at 9:15, but he was four miles away and didn't arrive until 9:39, nine minutes
after the blast.
Another issue: at 9:19, a Con Ed staffer contacted the fire
department to check out the gas odor but got confused about the address and
promised to call back. The FDNY, though, was not called until after the blast
at 9:30. Firefighters arrived at the scene three minutes later
On Wednesday, Con Edison responded to the opening of the
safety board’s docket with a statement that said the company was prohibited
from commenting on the board’s review until it concludes.
“We look forward to the completion of the investigation,
which will provide a full picture of what happened,” the statement said.
In the meantime, the company said, it has taken steps to
make its gas-distribution system safer, including significantly increasing the
frequency of its patrols for gas leaks. Con Ed says it now surveys its 4,300
miles of gas mains once a month, on average, instead of once a year, as state
and federal codes require.
Con Ed always uses low cost contractors to save money. It is not surprising that they use
contractors who do not have the proper qualifications or who would take short
cuts with safety and material and installation.
Many of the underground transformers have been installed in the 1960s
and they operate well-past their useful life.
This is one of the reasons we have been seeing increased number of
underground fires and explosions.
Superstorm Sandy delivered a terrible blow to this infrastructure, as it
eroded some of the subbase, causing the pipes to bent or settle and separate or break. The breaks we have seen happen at the rigid plastic pipes, like the ones shown above at the Harlem site. Proper prep of the pipe subbase is crucial.