NYC DEP Announces Start of Tunneling for Delaware Aqueduct Repair

On Sept. 8, the New York City Department of Environmental Protection (DEP) was joined by federal, state and local representatives, honored guests, and dozens of construction workers to mark the start of tunneling for the Delaware Aqueduct Bypass Tunnel – the largest repair project in the 175-year history of New York City’s drinking water supply. The $1 billion project will repair two areas of leakage within the 85-mile Delaware Aqueduct, the longest tunnel in the world. The primary leak will be eliminated through the construction of a 2.5-mile bypass tunnel, which will be drilled 600 ft below the Hudson River from Newburgh to Wappinger.

The tunnel will be driven by one of the world’s most advanced tunnel boring machines. The machine – which measures more than 470 ft long and weights upwards of 2.7 million pounds – was also dedicated today in honor of Nora Stanton Blatch Deforest Barney, a noted suffragist and the first woman in the United States to earn a college degree in civil engineering. Nora, who worked as a draftsman on the City’s first reservoir and aqueduct in the Catskill Mountains, was also the first female member of the American Society of Civil Engineers.

“The start of tunneling to repair the Delaware Aqueduct is a major milestone in the history of New York City’s water supply system,” DEP Acting Commissioner Vincent Sapienza said. “While the City has added new facilities to its water supply over the past century, repairs approaching this magnitude have been few and far between. The effort to fix the Delaware Aqueduct is by far the most complex DEP has undertaken, and it highlights the absolute need to keep our public works in a state of good repair.”

The next phase of construction for the bypass tunnel will begin next week when construction workers in Newburgh begin to lower the $30 million tunnel boring machine (TBM) into a subsurface chamber that is located 845 ft below the ground. The machine is currently being stored in 22 pieces. It will take workers approximately 4 months to assemble the TBM.

The TBM, built by The Robbins Company, is an integral part of DEP’s program to fix two leaks in the Delaware Aqueduct. The largest of the two leaks is located along the western bank of the Hudson River in Newburgh. The TBM will be used to build a 14-ft diameter bypass tunnel alongside this section of the aqueduct. The 2.5-mile bypass will be constructed 600 ft below the Hudson River, from Newburgh to Wappinger. Once finished, it will be connected to structurally sound portions of the existing Delaware Aqueduct to convey water around the leaking section. The leaking stretch will be plugged and permanently taken out of service. The contractor is Kiewit/Shea.

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The new tunnel will be driven by the TBM and more than 100 workers at the site. The TBM’s cutterhead is 21.6 ft in diameter. The TBM was built to withstand 30 bar of pressure – believed to be the most of any TBM ever manufactured. The machine needs to withstand that much pressure because workers encountered huge inflows of water under immense head pressure when the aqueduct was first built more than 70 years ago.

The TBM is also equipped with dewatering equipment to pump 2,500 gallons per minute away from the tunnel as the machine pushes forward. In addition, the machine is outfitted with equipment to install and grout the concrete lining of the tunnel, and to convey pulverized rock to a system of railroad cars that will follow the TBM as it works. The railroad cars will regularly travel back and forth between the TBM and the bottom of Shaft 5B in Newburgh, delivering workers, equipment and rock between the two locations. Once the TBM begins its work, DEP expects it will drive about 50 ft of tunnel per day. Work on the tunnel will continue 24 hours a day, five days a week. Tunneling is expected to take 20 months. Over the past several months, workers have already blasted 130 lf of starter tunnel in the direction that the TBM will work.

The finished bypass tunnel will be reinforced by 9,200 lf of steel and a second layer of concrete after the TBM is finished driving its path beneath the river. Once those are in place, DEP will shut down the Delaware Aqueduct to connect the bypass tunnel to the existing aqueduct. The approximately 6-month shutdown is planned for October 2022. The project is expected to be finished in 2023.

TBM Named in Honor of Nora

DEP was also joined by descendants of Nora Stanton Blatch Deforest Barney, the groundbreaking engineer for whom the TBM was named. DEP announced in March that it would name the machine after Nora, who became the first woman in the United States to earn an engineering degree when she graduated from Cornell University in 1905. That year, she also became the first woman to gain membership in the American Society of Civil Engineers, as a junior member. After she graduated from Cornell, Nora worked as an engineer and draftsman for the American Bridge Company, Radley Steel Construction Company, and the New York Public Service Commission. Later in life she became a developer and architect on Long Island and in Greenwich, Connecticut.

“It is an honor for our grandmother, Nora, to lend her name to this unique tunnel boring machine,” said Coline Jenkins, the granddaughter of Nora. “Both Nora and NORA are ground breakers, here to overcome obstacles and create a stronger society for millions of citizens.”

From 1906–1908, Nora worked as a draftsman for the New York City Board of Water Supply as it developed the first parts of the Catskill Water Supply System. She was paid $1,200 per year for her work—the highest salary of any draftsman on the project. All the others fulfilling that job were men. Little exact information is known about Nora’s work on water supply infrastructure in the Catskills. But a 1908 story from The New York Times said she had “done much difficult work on dams and weirs” for the project—an explanation that would suggest she drafted some of the infrastructure for Ashokan Reservoir and the headworks of the Catskill Aqueduct.

Nora was also noted for her work in the women’s rights movement. Her involvement was something of an heirloom passed down by her grandmother and mother. Her grandmother, Elizabeth Cady Stanton, authored the “Declaration of Sentiments” that was presented at the Seneca Falls Convention of 1848, marking the start of an organized push for women’s rights and women’s suffrage in the United States. Nora’s mother, Harriot Stanton Blatch, was also a noted suffragist who injected new energy by broadening the movement to include working-class women in New York City, and by organizing parades up Fifth Avenue, protests at Carnegie Hall, and lobbying efforts at the State Capitol in Albany. Nora continued in that tradition. She founded a suffrage club at Cornell, became president of the Women’s Political Union in 1915, and led the charge for an Equal Rights Amendment to the U.S. Constitution that would have guaranteed women equal rights in the workplace. The amendment was not ratified, but it has been debated in Congress almost every year since it was introduced, including as recently as 2015.

Nora Stanton Blatch Deforest Barney died in 1971 at the age of 87.

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