Your Role in Fixing a Leak in the World’s Longest Tunnel

The site just off Route 9W in Newburgh is pretty nondescript. A guard booth and a couple boxy structures mark the entrance to a steep driveway that winds around a treeless hill. At the top is a large, dusty parking lot. At one side, next to a large pile of broken rock, there is a 30-foot-wide hole running hundreds of feet into the earth.

It’s part of a project to repair a 20-million-gallon-a-day leak in the world’s longest tunnel and protect the largest source of New York City’s drinking water.

The repair of the Delaware Aqueduct’s Rondout-West Branch tunnel is part of a program called Water for the Future, one of the most ambitious engineering projects in city history. It began only after years of prodding by water watchdogs and complaints from some watershed residents who blamed the leak for flooding homes and streets. It has forced the city’s Department of Environmental Protection (DEP) to figure out how to replace half the city’s water supply during a months-long stretch next decade when the repairs will require closing the tunnel.

The complexity of the leak repair and related projects—including one where two employees of a construction contractor died in an accident—are a testament to the marvel that is the city’s water system and the work that goes into maintaining it. They’re also a warning about the challenges New York City will confront in coming years to keep its world-class water system running.

Admitting a leak

It has been 57 years since anyone got a good look inside the Delaware Aqueduct, which starts at one end of the Rondout Reservoir in Ulster County and runs 45 miles to the West Branch Reservoir outside of Carmel, then turns south for the run down to the Kensico Reservoir in Valhalla. From the Kensico, its water moves to the ultraviolet disinfection plant in Eastview, onto the Hillview Reservoir in Yonkers and then into the tunnels that feed the city’s mains.

Opened in 1944, the aqueduct collects water from four reservoirs across 1,000 square miles and can carry up to 900 million gallons of water a day, but usually handles about two thirds of that, all powered by gravity on a course that goes as deep as 2,300 feet below the surface.

The last physical inspection was in 1958. But you don’t have to be inside a tunnel to know there’s something wrong with it. In 1988 and 1989, there was evidence that surface springs near the town of Warwarsing were coming from a breach in the pipe, according to a report by the state comptroller. By 1992 DEP confirmed that 15 to 20 million gallons a day were leaking. Nowadays, it’s estimated that 15 million gallons to 35 million gallons a day are lost. If you take the high estimate, that means the leak could fill the Central Park Reservoir in about a month.

The problem was foreshadowed decades earlier: The engineers who built the Aqueduct noted that in one section of the tunnel near Warwarsing, diggers had to fight back 9,000 gallons an hour of groundwater rushing in and has to use 20,000 bags of concrete to stabilize the section. That’s exactly where one of the Aqueduct’s trouble spots is today.

In more recent years, archives of upstate newspapers document the intense alarm and anger at the city—already resented for its large presence in the area—over the leak. Some of the upset remains. Warwarsing resident David Lorenzo has had basement flooding for years and wants to get out but can’t afford to. “They’ve offered me $137,000,” he says of a city-backed buyout program. “But I owe $138,000 on the house. I guess I’m what they call ‘underwater.'”

He gets the pun. At least 34 other homeowners have, however, sold out to that $7 million program funded by the city and state. Operated by Ulster County, it acquires and demolishes flood-affected houses. Another six properties were in the pipeline as of late April, according to a DEP spokesperson. DEP has also given $7 million to the town of Warwarsing to build a municipal water system and set aside $5.5 million for homeowners who want to fix their home rather than sell it.

WNYC Reports on Water for the Future

A 2012 report by the United States Geological Survey found that leakage from the aqueduct near Warwarsing was affecting groundwater aquifers more than a mile away. But it also determined that most of the flooding—blamed for inundating streets and basements and contaminating ells with E. Coli—could be blamed on unusually high levels of precipitation.

Some of DEP’s delay in addressing the leak can be blamed on how hard it is to even diagnose a problem like this. After all, this is not a leak under your sink, but one hundreds of feet below the earth. “It’s a difficult investigative process,” says Cooper Union professor Kevin Bone, author of Water-Works, The Architecture and Engineering of the New York City Water Supply. “To determine when and where there are problems takes time. ” DEP had to send camera-equipped, remote controlled underwater vehicles into the tunnel to map the cracks.

Still, even admirers of the agency believe it acted sluggishly. “It’s fair to say the city reacted slowly to the complaints from local residents that there was some connection between the waters that were percolating up in their community and the city’s underground aqueduct,” says Eric Goldstein, a senior attorney at the Natural Resources Defense Council.

Once the leak was diagnosed, it took DEP a while to figure out what to do about it. “The city really had a hard time grappling with, ‘How can we fix this problem without shutting the system down for years?'” says DEP spokesman Adam Bosch.

Working around it

There are actually two distinct sets of cracks in the Aqueduct. The one near Warwarsing is the smaller of the two. The other, larger leak is along the Hudson River near Newburgh. Each requires a different solution.

The tunnel can be shut down to permit grouting of the cracks near Warwarsing. But doing the same thing for the larger leak near Newburgh might have taken as long as four years—a very long time for the city to do without its best water.

Instead, the city is going to go around that leak, with a new, 2.3-mile bypass tunnel under the Hudson.

Right now at the site off Route 9W, DEP is blasting downward to reach the depth at which the new tunnel will start. Across the river in Wappinger Falls, another shaft is being hollowed out. Every three or four days, workers drill 140 holes into the rock, fill them with a combined 2,200 pounds of explosives and evacuate. A staggered series of blasts rips up another eight to 12 meters of rock. Every 50 or 100 feet contractors line the sides of the shafts with concrete, and then the blasts begin again, as the work crews head to depths of 700 and 900 feet below the surface.

The shafts are supposed to be done next year. Then a tunnel-boring machine, custom-made to withstand the pressure it might encounter under the river, will be lowered in pieces to the tunnel floor and assembled. It will drill the new tunnel under the Hudson at a pace of 50 to 70 a feet a day. The debris generated by the huge drill will be trucked out on railroad carts or pumped out as slurry to a station that will extract and clean the water, then release it to the Hudson.

When the drilling is done, the new tunnel will be lined, connections between it and the Aqueduct will be made by blasting, the shafts will be capped to maintain pressure in the system and the leaky part of the pipe will be plugged and decommissioned forever.

While 35 million gallons is a lot of water, the loss of water from the Delaware Aqueduct leaks is not terribly significant given the scale of the city’s water resources: It’s but 4 percent of the city’s daily volume. The real reason DEP must fix the leaks is that, left unaddressed, the ruptures could worsen and the tunnel collapse.

“Losing it on an emergency basis would be catastrophic for the city,” said DEP Commissioner Emily Lloyd at a hearing March.

The fact that the amount of water leaking has held steady is a good sign that the tunnel is not weakening significantly. DEP says there is “very little immediate risk of failure of the tunnel,” which is true—though the odds of a serious problem are higher than anyone would like. DEP documents indicate the probability of the tunnel failing in any given year is between 0.1 percent and 1 percent. That’s an order of magnitude higher than what the agency characterizes as the “preferred annualized risk range for the tunnel” of .01 percent or less.

DEP earlier this year hired an engineering firm to assess failure risks again, and the news out of that study may be good: Contract documents say more recent data suggests “the risk may be lower than previously projected.”

“The risk on the system is very, very, very low,” says Deputy Commissioner Paul Rush, who oversees the entire upstate system. “We do have a monitoring protocol in place to identify if there are any changes to indicate there could be a problem. There are steps that we can take to reduce risk further if there was an incident. So we do have a plan in place to deal with it.”

Either way, NRDC’s Goldstein, says the city is in better shape to deal with an emergency at the Aqueduct now than it was a few years back. “Since the leak has been known for two decades and has remained relatively constant,” he adds, “we as well as everyone else are hoping the city’s luck will hold out.”

Planning ahead

Right now, DEP’s estimate is that the shutdown to connect the bypass tunnel and fix the Warwarsing leak will last six to eight months, though Lloyd said at that public hearing in March, “I always like to be conservative and say, ‘Let’s plan for a year and a half.'”

Over the years, DEP has explored several options for making up the shortfall in water supply that will occur over that period. It considered connecting to New Jersey or bringing in Nassau county water supplies. As recently as May, the city thought about reopening a system of wells in Jamaica, Queens. It’s not clear why DEP moved away from that option, though there had been concerns that the Queens water was contaminated.

The city currently plans to use water from the Croton and Catskills systems and increased conservation to fill the gap. Croton water has typically made up 10 percent of the city’s supply, but with the Croton Filtration Plant online DEP says it could provide nearly 30 percent. To get even more out of the Croton system, the city is building pumps to run Croton water through the lower part of the Delaware Aqueduct, which is unaffected by the leak repairs.

DEP is also hoping to reduce city consumption by around 2.5 percent by 2020. It says it plans a “municipal water efficiency program aimed at reducing water use and consumption in city-owned properties,” as well as policies to encourage the adoption of low-flow toilets in residences, a voluntary saving program for business and better steps to detect waste. It’s also revising the city’s drought management plan, just in case.

New York City already uses about a third less water than it did in 1980. That could indicate that conserving another 25 million gallons a day will be easy. Or it could mean that New Yorkers have cut back as much as they are willing or able. Goldstein takes the former view. “There’s more untapped potential there and we think over the next several years as the city’s plans get sharpened and everyone gets out the calculator to make sure that we will have sufficient water during that period when Delaware is off line, conservation can play a bigger role,” he says.

The Catskills water comes with complexities. A thin layer of plant growth inside the Catskills Aqueduct has slowed the flow of water through that channel. DEP is working now to remove that layer and is considering add more chlorine to the Catskills water to prevent it from building up again. That could require DEP has to build a new dechlorination plant further downstream. While not as rickety as the Delaware Aqueduct, the Catskills Aqueduct also has leaks—nine that DEP knows of. The agency plans to repair some of them and, for the other says, may install a local dechlorination system to make sure the water bubbling up to the surface isn’t toxic to wildlife.

Chlorine won’t be the only issue. Right now, DEP sometimes avoids using Catskills water because of its turbidity, or cloudiness—a result of the geology of the surrounding hills. When Catskills water is too turbid, DEP shifts to other supplies, but that won’t be possible once the shutdown begins. “They’re not going to be able to pick and choose,” says William Wegner, the staff scientist at Riverkeeper. “If they need water, it’s coming down the aqueduct.” So the city will add to the water a chemical called aluminum sulfate, or alum, that helps particles settle to the bottom. DEP is studying whether the extra alum could have an environmental impact. In the past, the agency has faced criticism for using too much of it.

The city says it will be flexible about timing the Delaware shutdown. “DEP, through planning models and hydrological forecasting will select the most advantageous periods to begin construction once we are ready to proceed. So, if there is any perceived risk, we will defer the shutdown to the next year,” says agency spokesman Chris Gilbride in a statement. “Further, the project has plans in place to stop construction if necessary and refill the tunnel if there is any risk of a water shortage.” The environmental groups that have monitored the leak for 20 years, Riverkeeper and NRDC, say they share the city’s confidence. DEP plans to do the shutdown from the fall of 2022 into the spring of 2023, a time of year when demand is at its lowest.

“The people who rely on the city’s system will not be impacted, will be able to go about their daily lives, knowing that they have water every time they turn on the faucet,” Rush says.

Not all the worry about Water for the Future is about how the city will cope with Delaware water it’s not getting. There’s also the issue of the reservoirs in the Delaware watershed, which will have no place to send the water they are designed to discharge. DEP says it will conduct more releases down streams to keep Delaware reservoirs from overflowing, and it’s building special siphons to give water from the Rondout Reservoir some place to go. The agency also is helping make interim plans for towns near the watershed that rely on the Delaware Aqueduct for their supply.

All this comes as DEP deals with the day-to-day challenges of running the water system. In his office in Valhalla, Rush talked in May about handling a March that delivered 40 percent less precipitation that normal, worrying about what the emerald ash borer is doing to trees that help buffer the edges of city reservoirs and managing the impact of a couple recent forest fires. DEP’s responsibilities upstate include not just the reservoirs, valves and tunnels than handle the water, but 100 miles of highway and 56 bridges built near the watersheds that the agency must maintain.

“We’ve tried to get as much as we can out of our existing infrastructure,” he says of the upstate empire. What amazes him about the system is that “so much could go wrong but it seldom does.”

The next big project?

Redundancy is the driving principle for the DEP—a single pipe can fail, so you’ve got to have more than a single pipe. That’s what’s driving a project related to Water for the Future: Connecting the Catskills and Delaware Aqueducts at a point where they cross so that each system could supplant the other. That job won’t help the city during the Delaware shutdown but it could at some later date.

Unfortunately, the effort has already claimed two lives: In December 2013, two construction workers died when a wall fell on them at a mock-up of the project that a DEP contractor had built to practice work on the interconnection task. Families of the dead have sued the contractor, Halmar International, and the city. OSHA cited Halmar for two serious violations. The firm is still being paid by DEP for the interconnection project. In court papers, attorneys for the city have said the accident was not its fault.

DEP is pretty proud of its safety record at the shaft construction sites, where pens and safety goggles have to be connected to a visitor’s high-visibility vest to make sure they don’t become dangerous missiles when someone leans to look into the shaft where men are working far below. But while human costs will hopefully be avoided there, monetary costs won’t. The price-tag for Water for the Future is $1.2 billion.

Headlined by the ultraviolet disinfection facility, dam repairs and the Croton filtration plant, DEP has just wrapped up a decade in which it spent $21 billion on capital projects to fix aging assets and comply with federal mandates.

DEP’s current capital budget foresees a more modest $15 billion in spending from 2015 to 2025. But that figure doesn’t include several potential projects mentioned in documents the city prepares for water bond investors.

There are three Superfund sites in the city where DEP could be on the hook to help pay for multimillion remediation and cleaning up rivers and bays affected by sewer overflows could take billions more than DEP has budgeted for. The state and city are negotiating over regulations covering how stormwater is handled and how much chlorine our water treatment plants release—both of which could lead to upgrades with a total cost DEP declines to estimate. Capital work might be needed on the Shandaken Tunnel that runs between two Catskills watershed reservoirs, which is under state review. Sometime next year the city will learn from the EPA if it has to cover the Hillview Reservoir, at a cost of $1.6 billion, to protect it from bird excrement.

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And there’s always the chance, says Riverkeeper’s Wegner, that something unforeseen will surface—like it did when water began bubbling up from the Delaware Aqueduct two decades ago. “No infrastructure is built to last forever. It can’t be. These are made out of concrete and concrete just doesn’t last indefinitely,” he says. “Since some of this infrastructure is well over 100 years old, it’s time to start looking at areas that have a potential for failure. Because there’s a lot of infrastructure.”

Rush says DEP has challenged itself to look 50 years into the future to anticipate those issues. One benefit of the Delaware Aqueduct project is that it will give the agency the ability to shut down, inspect and maintain the tunnels that link the city to its water.

“The New York City water supply is a success story. It’s probably the best managed urban water supply on the planet,” says Bone. But the brilliant planning of yesteryear doesn’t justify complacency. “I think we have to always keep our guard up.”