Category: Archive

Tunnel vision

February 16, 2011

By Staff Reporter

By Stephen McKinley

After the collapse of the World Trade Center towers on Sept. 11, the frenetic work of rescuers and recovery teams at Ground Zero was matched across the Hudson River in New Jersey, where a team of engineers assessed the alarming possibility of a major flooding catastrophe.

Because of the nature of the damage to the Twin Towers’ foundations in Manhattan, it was feared that the PATH train tunnels beneath the center could flood, allowing broken water mains to pour into stations in New Jersey.

Additionally, experts were worried that the complex on the Manhattan side could be so damaged that the Hudson River could breach the western foundations, causing much more extensive flooding on the New Jersey underground rail system, parts of which stand at a lower elevation than Manhattan.

Central to the task of saving the tunnels was Cork immigrant John

Corkery, a Cork Institute of Technology graduate engineer, and member of the Irish Business Organization of New York, whose company, Pumping Services Inc., specializes in the task of providing emergency pumping systems.

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Water accumulation was a central concern when the World Trade Center was built in the 1960s and ’70s. In fact, its waterproof foundations were considered an engineering miracle. To create the 16-acre site, the Port Authority condemned 164 buildings — 14 blocks of lower Manhattan — before sinking three-foot-thick foundation walls almost 100 feet through layers of silt, quicksand and clay, locking them into the bedrock known as Manhattan schist.

Because the western edge of the site ran so close to the Hudson, foundations had to be built within a huge four-sided waterproof box. This carefully designed box became known as “the bathtub.”

The luxury of years of careful planning was denied Corkery and his team in the days after the disaster. As Corkery put it, “The circumstances of the emergency made it impossible to plan at all.”

Millions of gallons of water were gathering hourly in the bathtub, and across in New Jersey, Corkery was considering some sobering statistics.

“One passenger platform in New Jersey is 24 feet lower than the basement of the WTC. Water levels began to rise at an alarming rate and within a day of the disaster, the rail in New Jersey was under water. Water could rage through the station and on into the underground railway system of New Jersey and beyond.”

At an emergency meeting on Monday, Sept. 17, the team agreed that the primary concern was to pump out the train tunnels enough so that they could then be plugged with strong, but temporary, concrete bulkheads. Pumping pipes would still have to run through the plug to allow dewatering to continue.

Three 12-inch, diesel driven, self-priming pumps, powered by 300 horsepower engines were shipped to the site. But to provide the team with the necessary tools to do the job, much more was needed. Corkery gave a list: “Over the next 24 hours and beyond, all sorts of equipment arrived on site, including pipes, hoses, wood, steel, fasteners, protection equipment, fuel, divers, diving equipment, gaskets, cable, strapping equipment, rollers, flotation equipment, caps, plugs, miles of rope, inflatable boats, pumps, rail cars, chain saws, bars, clamps, hard hats, glasses, gas monitors, fuel, extension cords, air hoses, air-operated pumps, fans, generators, screws . . . ”

Working against the clock, divers, including another Irish man, Peter Fitzpatrick, took the pumping pipes down into the tunnels. Corkery said he was overwhelmed by the dedication and heroism of the teams of workers.

“I noticed one of the construction workers screwing pipe together with her bare hands.,” he said. “Others were lifting heavy pieces of equipment far beyond their normal capacity in today’s modern construction world. This job was far from normal. This was basic blood, sweat and tears. But we were finally ready to start up the pumps. Peter Fitzpatrick is one of the bravest guys I have ever met.”

Over the already-deafening noise of extractor fans and all kinds of

equipment, the Corkery team heard a new sound — “we watched as those mighty ‘Made in America’ pumps powered up. We could tell that these brand new pumps were powerful by the sound,” said Corkery. “It was solid, stable, and convincing.”

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