Plumbers Job on a Giants Scale: Fixing New Yorks Drinking Straw
All tunnels leak, but this one is a sieve. For most of the last two decades, the Rondout-West Branch tunnel — 45 miles long, 13.5 feet wide, up to 1,200 feet below ground and responsible for ferrying half of New York City’s water supply from reservoirs in the Catskill Mountains — has been leaking some 20 million gallons a day. Except recently, when on some days it has lost up to 36 million gallons.
After tiptoeing around the problem for many years, and amid mounting complaints of flooded homes in the Ulster County hamlet of Wawarsing, the city’s Department of Environmental Protection has embarked on a five-year, $240 million project to prepare to fix the tunnel — which includes figuring out how to keep water flowing through New Yorkers’ faucets during the repairs. The most immediate tasks are to fix a valve at the bottom of a 700-foot shaft in Dutchess County so pumps will eventually be able to drain the tunnel, and to ensure that the tunnel does not crack or collapse while it is empty.
For this, the city has enlisted six deep-sea divers who are living for more than a month in a sealed 24-foot tubular pressurized tank complete with showers, a television and a Nerf basketball hoop, breathing air that is 97.5 percent helium and 2.5 percent oxygen, so their high-pitched squeals are all but unintelligible. They leave the tank only to transfer to a diving bell that is lowered 70 stories into the earth, where they work 12-hour shifts, with each man taking a four-hour turn hacking away at concrete to expose the valve.
The other day, one of the divers, A. W. McAfee, moved about as gracefully as anyone could in that much water, slowly fixing a monkey wrench onto a screw wedged in a block of concrete, then taking a mallet to whack it free. As Mr. McAfee did this again and again, a camera on his helmet broadcast his slow ballet and heavy breathing in near-darkness to a video feed far above in a brick building, where his bosses sat, riveted, searching for clues.
“We’re trying to piece it together to figure out the state of the tunnel,” said Jim Mueller, a deputy commissioner at the D.E.P. “This is all due diligence to stay of out of a crisis.”
Among other things, the divers have pulled out a 4,000-pound pipe elbow made of manganese bronze that was installed in 1939, finding it in “remarkably good shape,” said Nick M. Cholewka, a construction manager with the department. “If it was pulled out and all corroded, we’d be worried and we’d have to pull out more.”
New York has one of the world’s most complex water systems. Eight million residents in the city, and another one million upriver, daily consume 1.2 billion gallons that flow through a network of reservoirs and aqueducts stretching from the Delaware River watershed to the Connecticut border almost 100 miles to the southeast. The Croton system in Westchester County, which began providing water in 1842, meets about 10 percent of the city’s needs. The Catskill system, built in the first quarter of the 20th century, provides 40 percent.
The remaining 600 million gallons a day also come from the Catskill Mountains, through the Delaware Aqueduct system, which was finished in the 1960s and includes the troubled Rondout-West Branch tunnel, completed in 1944 and promised to last at least a century.
The city learned of the extensive leaks 20 years ago, but did little to fix them until 2004, when the D.E.P. hired consultants to investigate the extent of the problem. In an audit issued in 2007, the state comptroller accused city officials of foot-dragging, saying they “did not adequately monitor the extent and nature of the leaks” and had “not established an adequate plan to protect the public in the event of a sudden or imminent substantial loss of water from the Delaware Aqueduct system.”
In the last year, as Wawarsing homeowners reported mold, wells contaminated with E. coli and basements that flooded even on dry days, the city stepped up its efforts. A few in Wawarsing, a town of 13,000 that is a two-hour drive north of Manhattan, noticed cracks in foundations and sinkholes in their backyards, which they roped off to keep children away.
“No one wants to move,” said Laura Smith, a Wawarsing resident who helped form an advocacy group for the neighborhood, “but no one wants to sit here in the floods.”
At the request of the D.E.P., the United States Geological Survey is trying to determine how much of Wawarsing’s well water comes from the tunnel, but in the meantime, New York City has been providing the town’s residents with bottled water, and plans to soon send pumps and ultraviolet lights to filter the wells. Ms. Smith and others said that since last month, when the D.E.P. turned off the flow through the tunnel for the diving project, flooding has ebbed.
Yet Steven W. Lawitts, the acting commissioner of the department, said the earliest the city might empty the tunnel was 2011, because of all the preparatory work required. As the divers study the underwater pumps, city officials are investigating where, how and whether to build a bypass tunnel, and are building a filtration system to allow more water to be pumped from the Croton system.
Albert Appleton, a department commissioner in the 1990s, says the city should build another tunnel across the Hudson River connecting the four Delaware system reservoirs to the Catskill reservoirs. This tunnel, he said, would be more expensive than a smaller bypass, but would give the city more flexibility by connecting two giant water systems.
Such a tunnel would be the latest in a long list of additions to New York’s waterworks. Except during World War II and the fiscal crisis of the 1970s, “we’ve been building structures that deliver water to New York City continuously for 175 years,” said Kevin Bone, an architect who edited “Water-Works,” a 2006 book on the city’s water supply.
In the 1820s, New Yorkers used an average of 12 gallons of water a day, he said. Individual water use peaked in the 1980s, at more than 200 gallons. Through conservation, technology like low-flush toilets and repairs to the city’s leaky pipes, consumption is now about 150 gallons a day per person, said Mr. Bone, who expects it will fall further.
“We’ve always been playing catch-up until the last 20 years, when we realized the only way to get more out of the water system is to use less,” he said. “There’s no more water out there for us.”
But building water tunnels can take decades: One known as New York City Water Tunnel No. 3 was started nearly 40 years ago and will not be completed until 2015.
Just setting up the 14 tractor-trailers’ worth of gear to run the $22 million diving operation at Shaft No. 6 in Dutchess County took a month. To help the divers see better in the shaft, 1,000 gallons of sediment-filled water is pumped out every minute. Other machines filter the helium mixture that the divers breathe. Two boilers heat water that is pumped through the divers’ suits to keep them warm.
Three divers at a time climb into the steel bell, an orb that is lowered down the shaft for 20 minutes to reach the pumping equipment in the tunnel. The bell is tethered to a bundle of cables carrying air, communication lines, electricity and water. Each diver works for four hours and rests underwater for eight before returning to the tank at the surface, where 32 more employees of Global Diving and Salvage, the Seattle company running the project, pass meals, clothes and books through an air lock.
In the saturation control room, Patrick Boyd, a life-support technician, monitors the divers’ air on a panel of screens, one of which reads 2.26 percent, for the amount of oxygen. While underwater, divers often get more oxygen in their mixture to keep them alert. John Lapeyrouse, a dive supervisor who is one of the few who can understand the helium-riddled voices, one of the side effects of what is called “saturation diving,” talked to Mr. McAfee as he worked the other day.
In a tent nearby were washers, dryers and a full kitchen. The divers can request whatever food they like, including steak and fresh salads. But the air pressure in the tank dulls the taste buds, so they use a lot of Tabasco, salsa and jalapenos; bread goes flat, more pita than challah. Once the operation is complete, the divers must remain in the tank for a week to gradually wean themselves off helium.
“They lose a lot of weight because they’re burning so many calories,” said Robert Onesti, who is running the project for Global Diving. “It’s not for everybody. It’s heavy construction work, and it’s deep.”