On May 16, operator Andrew Reisinger drives staff into a shuttle along a small metres of a railway line in a 2.5 – meter bypass tunnel is dug for the Delaware Aqueduct, in Marlboro, N. Y.
New York City is located in the middle of a plumbing repair of monumental proportions.
Hard-hat workers toiling deep beneath the ground 55 stories below the Hudson River, to eliminate the gushing leak in the ageing of the tunnel that delivers half of the water supply to the city over 85 miles of Catskill Mountain reservoirs. With the help of a cylindrical space-rocket-size borer, they are carving through solid rock to create a 2.5-meter bypass tunnel around the worst of the leaks.
When they are finished with the $1 billion tunnel in 2022, the entire Delaware Aqueduct will be shut down for months to prepare for the change. And if they do well, the New Yorkers turning their faucets will never even notice.
“It really is the largest and most complex water tunnel repair of the city of New York has ever done,” said Vincent Sapienza, commissioner of the city Department of Environmental Protection. “There is a lot of moving parts that we have been wrestling with now for a number of years.”
The Delaware Aqueduct to the city what the aorta is to our circulatory system: a necessary channel to keep everything running. It was drilled and sanded out mainly during the second world War, and contributes about 600 million liters per day, fully by the gravity of four Catskill region reservoirs to a holding reservoir just north of the city line.
Together with the additional Catskill Aqueduct, the two help with the connecting of a complex system that serves 9.6 million people in New York City and the state of municipalities. Engineers and politicians to compare with the network of 19 reservoirs, three lakes and the connecting tunnels to the great aqueducts of ancient Rome.
But the Delaware Aqueduct is with his age on a weak point where it crosses by means of limestone under the Hudson River near Newburgh, New York. Limestone is less massive and is more “give” than the neighboring slate, so crews are protected in that the length of the concrete tunnel with a steel case. But for an unknown reason — lack of understanding, lack of steel during the war — they did not extend through the entire limestone formation.
Leakage is formed in that gap, with a number of the rippling water in the river.
Approximately 18 million liters of 3 percent of the aqueduct’s flow, or enough to fill 27 Olympic swimming pools — has escaped from the pipeline every day. The loss is too great to ignore, but the tunnel is also of vital importance to just drain for a multi-year repair. City officials eventually settled on the parallel bypass tunnel, which provides for a shutdown measured in months instead of years.
“We could not fathom exit of the tunnel,” said Paul Rush, deputy commissioner of the environmental department.
The workers started with the digging of two large openings on either side of the river in 2013, and the actual tunneling started last summer.
A long, cylindrical machine the nickname “Nora” is pressed into the rock face using a circular 21.6-foot diameter “cutter” embedded with 41 spinning, steel blades. The tunnel boring machine, the kind used worldwide for major water and transportation projects, with the name for a civil engineer Nora Stanton Blatch Deforest Barney. The pulverized rock from the back through the conveyor to be loaded onto rail cars and pulled top.
Dozens of workers are deep at the same time. They work in Nora’s controls, bolt together pieces of the ever-extending concrete tunnel, work rail cars, and tend to push material up and down the 900 meters of the shaft.
It is a construction site in a cave and a wet. The miners are constantly sloshing through puddles of groundwater seeps.
The draining of the aqueduct in 2022 will give crews time to redirect the water under the Hudson, and seal other leaks of approximately 25 km along the aqueduct. These losses in Wawarsing, New York, are much smaller, but also they could contribute to a local pest of flooded cellars and damp lawns that resulted in the government to buy homes.
The cutting off the half of the water supply for up to eight months sounds like a recipe for disaster, but the environmental agency has been preparing for years. The efforts, such as installing low-flow toilets, have contributed to the decrease consumption of water, rates, even as the city grew.
The city relies on water from reservoirs in a suburb of Westchester County and the Catskill Aqueduct, which must have a higher capacity than. That aqueduct will be closed for several 10-week steps, so that the crew can scrub from micro-organisms that have created a layer of “biofilm,” which inhibits the flow through the century-old tunnel.
By 2023, the water will flow through a bypass built to last. A layer of the steel will be fitted inside this tunnel, and then another layer of concrete added for a final 14-foot-diameter tunnel, the road through the limestone formation.
Said Rush: “We are not going to come down soon.”