NEW YORK (CBSNewYork) -- Con Edison crews discovered an alarming natural gas concentration near the scene of the deadly East Harlem building explosion this week, a National Transportation Safety Board member said Friday.
Board member Robert Sumwalt also revealed that the gas main buried under Park Avenue near the scene at 116th Street dated back 127 years to 1887.
As CBS 2's Don Champion reported, investigators and Con Edison crews were still looking Friday night for the apparent leak.
Sumwalt said a review of records indicated – as earlier reports did -- that Con Ed received a call about a gas smell at 9:13 a.m. Wednesday and an emergency responder was dispatched two minutes later. The responder arrived at 9:40 a.m., by which time the explosion had already destroyed the two five-story buildings on Park Avenue off 116th Street.
Later on Wednesday, Con Edison took a "bar test," in which the drilled holes 18 to 24 inches into the ground and sent a bar down into each to probe for natural gas, Sumwalt said.
"In at least five holes, they found the presence of natural gas in the ground, and the gas concentration was up to 20 percent in at least five locations. It ranged from about 5 percent 20 percent," Sumwalt said. "After that, Con Ed then excavated three locations in the vicinity of the explosion to isolate and shut off the gas flow."
NTSB: Abnormal Concentration Of Natural Gas Found Near East Harlem Blast Scene
If everything had been running as normal, there test should not have detected any natural gas at all, Sumwalt said.
"Normally, the soil in New York City 18 to 24 inches down into the ground has zero concentration of natural gas, so the fact that at least five of the holes ranged between at least 5 and 20 percent, that tells us that it's a pretty good concentration of natural gas in there," Sumwalt said. "That further leads up to the hypothesis that this may be a natural gas leak."
Sumwalt also said the 8-inch cast iron service pipe under Park Avenue had been installed in 1887 – 11 years before the five boroughs of New York City united.
Sumwalt said while it will be investigated, the age of the pipe would not necessarily be connected to any problems.
"Pipeline operators are required by federal law to have an integrity management system to be able to manage their risk; understand what's in the grid, so if a pipe is properly managed and the risk assessment is properly done, the age should not be a factor," he said.
The FDNY still has not deemed it safe for the NTSB to conduct pressure tests for further investigation, and such tests are not expected for 24 to 48 hours, Sumwalt said.
In addition to reviews of documents and interviews with first responders and Con Ed workers, Sumwalt also asked first-hand witnesses to contact the agency by e-mail at email@example.com.
Officials on Friday were also probing reports from local residents that repeated complaints of gas leaks were ignored, but so far there's no indication of an early warning that could have prevented the disaster.
Firefighters Continue Search At East Harlem Blast Site
"We preliminarily reviewed our calls, 911 and 311, back to 2010," Police Commissioner William Bratton said Thursday. "We have no record of gas leaks relative to that area."
The FDNY also said a check of its records found no instances in the past month of reported gas odors or leaks from tenants of the two buildings that collapsed.
A Con Ed mobile gas detection unit had cleared the block as recently as two weeks ago.
Earlier Friday, FDNY Commissioner Sal Cassano said all those reported missing in the explosion have been accounted for, but stressed the rescue operation would continue in case there are still victims trapped in the rubble.
The fire commissioner said crews managed to remove a rear wall in the damaged structure, so that within a day they should finally be able to get to the base of the building, and then pinpoint the cause of the blast.
"We have not gotten into the basement yet. That's why as soon as we get all the debris out, we're going to send our marshals down, and we'll examine any possible why a) there was a gas leak – if it was -- and why it ignited," Cassano said.
Firefighters Continue Search, Debris Removal At East Harlem Blast Site
Cassano said about 60 to 70 percent of the debris has been removed and was being sent to Randalls Island for further investigation. He said crews hope to have all the debris cleared by mid-day Saturday.
Community Steps In To Help The Displaced
Meanwhile Friday, Mayor Bill de Blasio came to the Salvation Army Center on 125th Street where those displaced by the explosion were forced to take shelter. He brought words of comfort to those in distress.
"We made clear to them that we will stand by them every step of the way; that we will not let them fall. They've been through the unspeakable, and obviously we've met people who have lost family members and neighbors, all in an instant, with no warning," de Blasio said. "It's our obligation in the city of New York – I know all New Yorkers feel this way – to stand by them."
The Red Cross on Friday night was preparing to close its shelter for explosion survivors at the 125th Street Salvation Army shelter.
But de Blasio announced Friday that more than 100 people displaced by the blast will be given temporary and long-term housing.
"We don't want any parent lying awake tonight questioning where their children will sleep tomorrow," he said.
The Real Estate Board of New York is making 34 apartments available to the people in desperate need.
"There's some almost a block or two away, there's some down 91st Street. Some actually go as low as the 60s and First Avenue, and others go up to 132nd Street, so it's a variety of diff locations," said Steve Spinola of the real estate board.
The New York State Association of Affordable Housing will assist with securing both temporary and long-term apartments. A total of 91 area apartments had to be evacuated from buildings around the explosion site.
Also, the East Harlem Merchants Association has organized a food and clothing drive on 108th Street off Second Avenue for the victims, at the Poet's Den Gallery and Theater run by Ralph Benavides, WCBS 880's Marla Diamond reported.
East Harlem Merchants Step In To Help After Blast
"In a tragedy like this, the community comes together and we just try to help," he said. "A lot of the other merchants have called me and said, 'Can we do something? Can we put something together? Can we do a luncheon?"
And as fire crews continued to dig at the explosion scene, they got an unexpected visitor. Former President Bill Clinton came to the site, which is just blocks from his Harlem office.
No One Else Believed To Be Missing
The blast killed eight people and left more than 60 others injured.
Exclusive video obtained by CBS 2 showed the precise moment of the blast. A security camera showed windows shattering and debris flying from buildings across the street, followed by a vast plume of black smoke as the two affected buildings collapsed.
Police had said earlier that at least one person was still unaccounted for, but Cassano said Friday that no one else was believed to be missing.
"But we're still going to treat the sight like there may have been somebody in there that was missing," Cassano said.
More than 150 firefighters have been using sound devices and telescopic cameras to peer through the rubble, holding out hope that someone may still be trapped.
The debris is initially examined on the sidewalk in front of the explosion site then trucked to a parking lot on Randall's Island for a forensic investigation, WCBS 880's Rich Lamb reported.
The sudden explosion rocked the East Harlem neighborhood just after 9:30 a.m. Wednesday, bringing down two, five-story buildings that housed a church, a piano store and more than a dozen apartments.
The blast hurled bricks, glass and other debris across the neighborhood and onto nearby Metro-North tracks and sent flames and thick smoke billowing into the air.
Vehicles pulled from the beneath wreckage include a mangled sport-utility vehicle with a car seat in the back that was pinned beneath rocks and concrete. Another car and an ambulette appeared to have been crushed by falling debris.
Investigators Trying To Pinpoint Source Of Gas Leak
Thursday night, neighbors and relatives of the victims held candles and vowed to keep the memory of their loved ones alive.
Among the dead, 44-year-old public safety officer Griselde Camacho; 67-year-old Carmen Tanco, who worked in a dentist's office; 43-year-old musician Andreas Panagopoulos; 21-year-old Rosaura Hernandez Barrios and her mother, 44-year-old Rosaura Barrios.
Also killed was 44-year-old George Amadeo and 22-year-old Alexis Salas, a newlywed and expectant father.
Police said the eighth victim pulled from the rubble Thursday was an adult female.
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