Crews clean after an underground explosion sent chunks of concrete into the air and nearby windows. (William Farrington)
The mid-day explosion along the Second Avenue Subway zone might have been caused by two serious errors by the contractor, the MTA said today.
Officials said that the blast appeared to be the result of too much explosives in one area.
In addition, the deck that was placed above the explosive site was not properly anchored into the area, according to the preliminary investigation.
“It appears that there were two factors at play,” said MTA spokesman Kevin Ortiz.
“The force of the blast was concentrated in one area. And the deck above was not able to withstand that force because it was not anchored in.”
A source had told The Post that workers placed a protective over the wrong hole before blasting, though MTA spokesman Adam Lisberg today denied that account.
He said its unclear why the explosives were overloaded into one area beneath an improperly secured deck.
“We don’t know why it happened. We don’t know if it was human error, we don’t know if it was mechanical error. We are trying to find out more about that,” Lisberg said.
Witnesses described a shock wave at around 12:45 p.m. Tuesday that knocked people off their feet and created a 30-foot mushroom cloud of smoke and rubble on East 72nd Street and Second Avenue.
The flying rocks sent pedestrians scrambling for safety and shattered an art gallery’s windows, breaking a few vases inside.
“It’s like the blitz in London in World War II!” said Carole Cusa, who lives directly across the street and was thrown from a kitchen chair in her fifth-floor apartment.
“I thought I was going to die,” said fruit vendor MD Islam, who described a scene of blinding dust and mass panic.
The agency was hardly sympathetic in an e-mail to long-suffering residents near the project site.
“Today, an underground blast at the northwest corner of 72nd Street and Second Avenue caused debris to breach the cover at the surface,” wrote Michael Horodniceanu, president of MTA Capital Construction.
“No injuries were reported and only minor cosmetic property damage was reported.”
Mark Foley, who lives on 72nd, scoffed: That’s “like saying a tiny piece of metal breached [your] skin when you’ve been shot through the head by a bullet.”
MTA Chairman Joseph Lhota said, “While I am thankful that no one was injured today, I fully understand why neighbors of the construction site are upset.”
He called the blast “unacceptable” and ordered all work to stop.
Inside the Kolb Art Gallery at 260 E. 72nd St., worker Marsha Kaufman was knocked to the ground as the store filled with dust. It was later vacated.
“Huge plumes of smoke and rock came shooting out of the hole across the street,” she said. “When they hit the windows, we all froze.”
Yesterday’s blast was not the first time that the contractor SSK — a joint venture of Schiavone, J.F. Shea and Kiewit — has run into problems at the $4.4 billion project.
The federal Occupational Safety and Health Administration cited the company in March for having excessive levels of silica, a deadly carcinogen, at the site. OSHA fined SSK $8,500 for the violations. SSK has appealed.
The company is also on the city’s “caution list,” which is meant to warn agencies of potential problems with a form. It wasn’t clear why SSK landed on the list.
Meanwhile, a smaller but similar incident at the southeast corner of 72nd Street a few weeks ago is still under investigation.