Draining N.Y. Tunnels Flooded by Sandy to Take Many Days
Five underground walls of water containing hundreds of millions of gallons stand between New Yorkers and their lifeblood of full subway service.
It’s going to take hundreds of pumps, including ones powerful enough to drain an Olympic-sized swimming pool in less than 15 minutes; the U.S. Army Corps of Engineers’ National Unwatering SWAT Team; and at least several more days to get the job done.
“We don’t dewater tunnels very often,” said Pete Snow, lead trainer for White Plains, New York-based Xylem Inc. (XYL), which positioned 200 pumps in the area before Atlantic superstorm Sandy. “These kinds of disasters are always a first run. We don’t get a dress rehearsal.”
Five subway tubes, two Amtrak tunnels and three of the city’s primary roadways remain under water after the largest- ever Atlantic tropical system slammed into the U.S. East Coast.
A 2011 New York state study estimated it would take three days to drain the Hugh L. Carey Tunnel between Brooklyn and the Battery in Lower Manhattan if it was flooded in a major storm. It’s already been four days. The tunnel is filled floor to ceiling for more than a mile -- an estimated 86 million gallons (326 million liters) of water -- in its two tubes
Subway tunnels under the East River would take between five to seven days, more if multiple tunnels were flooded, according to the study.
The Corps’ water-removal team, headquartered in Rock Island, Illinois, has been in New York since Oct. 30, using 12 eight-inch pumps and 13 six-inch pumps shipped from New Orleans. The team consists of 10 to 12 civilians with expertise in civil, electrical, mechanical and hydraulic engineering, contracting, and emergency management, supplemented by people from throughout the Corps, according to an agency fact sheet.
Ken Wells, a spokesman for the Corps of Engineers, didn’t provide comment. The Corps “is meeting with other private pump suppliers to determine the availability and capacity of pumps that could be delivered to the New York area,” it said on its website.
Once bigger pumps arrive, it won’t take much time to drain the tunnels, Joseph Lhota, head of the Metropolitan Transportation Authority, said at a tour of the Carey tunnel yesterday. Until then, the job is going slowly, he said.
The bigger the portable pumps, the better, said Duane Gapinski, Corps of Engineers program manager for HDR Engineering Inc. in Omaha, Nebraska. Gapinski, as an Army colonel, led water removal work in New Orleans following Hurricane Katrina in 2005.
The pipes attached to those diesel-powered pumps measure as much as 42 inches in diameter. While the largest pumps can pump out 100 cubic feet (3 cubic meters) a second, enough to drain an Olympic-sized swimming pool in less than 15 minutes, it will take hundreds of them to dry out New York and “it’s not like there are a gazillion of them out there,” Gapinski said.
While the pumps can be transported on flatbed trucks, they must be removed from vehicles by crane, and multiple trucks are needed to transport the pipe that goes with them.
“It’s going to be pretty daunting to move that water out of there just given the dimensions,” Gapinski said. “Given how much water and where it is, it’s going to be quite the challenge.”
“Relatively speaking, they don’t move a lot of water,” he said in an interview.
Smaller pumps are easier to move, though they drain water at a fraction of the speed of the largest machines. Portable pumps used in New Orleans after Katrina moved such small volumes of water that they weren’t very valuable, Fred Young, the civilian who headed the Army Corps of Engineers’ task force to dry out that city.
“If you have areas that are inundated and you are using small pumps, it’s going to take a long time,” Young said.
As urgently as New Yorkers want their public transportation running again, rushing is dangerous, said John Kenny Jr., who oversaw the removal of water from 61 miles of inundated subterranean passages and basements beneath downtown Chicago in 1992.
Chicago took two weeks to pump out the water and another nine months of additional work including the installation of metal doors to enable sealing off 11 sections of tunnel.
Stopping to assess progress prevents accidental damage and allows workers to contend with inevitable surprises, like the boiler that came loose from its moorings and was found floating in the basement of Chicago City Hall, Kenny said in a telephone interview.
“You’ve got to be really careful,” said Kenny, president of Kenny Construction Co., based in Northbrook, Illinois.
Xylem, a water technology company spun off from ITT Corp. (ITT) last year, has 100 additional pumps on the way to New York, Tom Glover, a company spokesman, said. Its crews are at the World Trade Center and Goldman Sachs Group Inc. (GS) buildings in Manhattan.
Each flooded tunnel and other locations will require an individual plan rather than following the same formula for each, said Snow, the Xylem trainer.
Xylem will use submersible and ground-mounted pumps, both with cast-iron frames, to clear out water deposited by Sandy’s storm surge. For rapid deployment, 12-inch pumps are better than 24-inch models because they’re easier to move, Snow said.
The water will be sucked into pipes made of hard rubber on the suction end and galvanized steel piping on the discharge end, Snow said. They’ll bring water up from the bottom of a tunnel to ground level, where it can be filtered through the storm-water runoff system, he said.
A 12-inch pump is about eight feet wide and 14 feet long, Snow said. The pumps are powered by Deere & Co. (DE) or Caterpillar Inc. (CAT) diesel engines and need refueling about once a day when used continuously, giving them an advantage over pumps that depend on a generator or plug-in electricity source, he said.
New York officials knew pumps in the subway system wouldn’t work after a major flood, according to a 2011 report for the state on the effects of a large storm on the New York transportation grid.
The subway system had only three mobile pumps mounted to trains for the entire system, according to the report, “Responding to Climate Change in New York State,” published by the New York State Energy Research and Development Authority.
Each subway tunnel would require four pumps that could remove 1,000 to 1,500 gallons per minute, the report estimated. At that rate, about 7.2 million gallons (27 million liters) per day, per tunnel could be drained, the report said. It wasn’t realistic to expect all tunnels to be pumped at the same time, it said.
Young, who has left the Army Corps, said it will be critical to involve local engineers with direct knowledge of the subway system’s underground maze. Knowing the lowest spots in the system and areas that can most easily be reached by pumping equipment will be important to the effort, he said.
It’s impossible to know how how long it will take to remove all the water, Snow said.
“It’s a moving target, it’s constantly evolving, the scope of it is being defined as we speak,” Snow said. “But we’re confident that we have the equipment, the expertise and the resources to make an impact on this situation immediately.”
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