FLATIRON DISTRICT, Manhattan (WABC) --
"We have a massive aging infrastructure problem that we have to deal with," said Bill Stephan, PhD, JD, PE, founding principal of Metropolitan Engineering Consulting and Forensics.
According to Con Edison, New York City is home to the country's largest steam power system.
More than 100 miles of underground piping carry steam from five plants to more than 1,600 customers in buildings around Manhattan where the steam is used for heating, cooling, and sterilization, according to the utility company.
Tobias said leaks are increasingly common in the city's nearly 150-year old system and explosions occur due to catastrophic failures caused by a variety of factors.
While steam pipe explosions are not common, blasts have happened more than a handful of times in New York City since 1987.
On July 18, 2007; just over 11 years ago, a deadly steam pipe explosion at East 41st Street and Lexington Avenue occurred in part due to a phenomenon known as a "water hammer," according to an incident investigation.
A water hammer occurs when cool water comes in contact with the exterior of a steam pipe, cooling the pipe and causing steam inside the pipe to turn to water. The mixture of steam and water inside the pipe causes pressure to build which can lead to an explosion.
Debris from maintenance work had also clogged devices intended to release pressure on the pipe in the 2007 blast, according to the investigation.
Stephan speculated a water hammer could also be a factor in the blast Thursday at 5th Avenue and East 21st Street.
7 On Your Side Investigates found an open permit for work on a water main near the intersection set to begin next week, but the city's Emergency Management Commissioner expressed doubt the incidents were connected.
"They were going to work on the water main which is across the avenue from where that steam pipe was," said Commissioner Joseph Esposito. "So that permit and that work appears, right now, to have nothing to do with the steam pipe rupture."
While investigators try to determine what did cause the rupture, Tobias warned the city's system is becoming increasingly vulnerable to this type of failure.
"The pipes are getting older. They are getting more corroded, and the wall thickness of these pipes is decreasing which makes them more vulnerable to these leaks and more vulnerable to these catastrophic failures. The recent massive storm events we had in our area have expedited the breakdown of the infrastructure system, as the storms wash away the subbase that supports the piping, etc. Superstorm Sandy did a real number on our infrastructure," Stephan said.
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AGING INFRASTRUCTURE
FLATIRON DISTRICT, Manhattan (WABC) --
A large steam pipe exploded in Lower Manhattan Thursday morning, causing extensive damage to the street and positive asbestos tests that shut down streets and forced evacuations.
The 20-inch steam pipe installed beneath Fifth Avenue near 21st Street in 1932 ruptured at 6:39 a.m., and Mayor Bill de Blasio said it will be several days before things return to normal in this part of the Flatiron District.
The blast sent a column of scalding vapor spewing hundreds of feet into the air and left a large crater in the street. Amazingly, only five people suffered minor injuries and were treated at the scene.
Authorities evacuated 49 buildings on Fifth Avenue between 20th Street and 22nd Street as a precaution. About 500 people have been displaced.
The cause of the explosion is not known, de Blasio said, and Governor Andrew Cuomo directed the state Department of Public Service to conduct a full investigation and determine whether any utility activities contributed to it.
Environmental tests confirmed the presence of asbestos after the rupture, which was expected given the age of the pipe.
"We are very concerned about the material that was part of the steam line," de Blasio said. "There was asbestos in the steam line casing."
The mayor said the air is safe, but the buildings and streets are a worry.
"There is no meaningful presence of asbestos in the air," he said. "The concern is the debris on the street and on building facades.
All the buildings, both residential and commercial, will need to be checked for asbestos before they can reopen. Impacted buildings will need to be decontaminated, which could take several days, and that means residents will not be able to get back into the homes.
"For people who live and work in these buildings, we are going to do our best to help them get back in as soon as possible," de Blasio said. "Most likely scenario is a couple days. Perhaps some buildings farther from the site might be opened up as soon as this evening, but that is only a possibility. More likely is it will take two days or more to really clear the buildings and be confident people can go back in."
The work will require that section of Fifth Avenue to be shut down for days.
The line that exploded is part of a network of more than 100 miles of pipe that provides steam to 1,600 customers.
But that network is 150 years old, and leaks and explosions are becoming more common in recent years.
Anyone who was in the area at the time of the rupture and the subsequent raining down of debris is advised to bag their clothing and shower.
"We're (decontaminating) anyone who was in the area," Office of Emergency Management Commissioner Joe Esposito said.
Health officials said there is a very low risk to one-time exposure, but if asbestos got onto your clothing, you need to get rid of it.
"People removing the clothing, bag it up, bring it to a Con Ed site, which has been established at 22nd and Broadway," de Blasio said. "We want that clothing turned in. If there is evidence of material on the clothing, looks like the debris and dust is still visible on the clothing, we want that clothing turned in. We want anyone who thinks they are exposed, get out of that clothing, shower, clean, put on new clothing. That's out of an abundance of caution. Again, we believe that temporary brief exposure is generally not a problem. But we want to treat this with a lot of caution."
Con Edison personnel were stationed at 19th Street and Broadway and at 22nd Street and Broadway until 9 p.m. to accept the clothing. They also have claim forms available for people to submit to receive compensation for their clothes.
More personnel will also be in the Clinton School, 10 East 15th Street, until 10 p.m. to provide claim forms. The claim forms are also available at ConEd.com.
A decontamination center for first responders was set up at 22nd Street and Broadway. Video from the site showed firefighters removing their gear, and piles of clear plastic bags filled with firefighting equipment nearby.
With streets being closed in the area, subway and bus service was impacted.
Subway service resumed at 23rd Street, but commuters should allow additional travel time if using R and W service at 23rd Street Station. Several staircases remain closed.
Several buses were also being detoured, including M1, M2, M3, M55, M23-SBS, X1, X10, X17, X27, X28.
For updates, visit MTA.info.