Two-mile tunnel from Kensico Reservoir will be largest in Westchester since the 1940s

Work began this week on the largest water tunnel in Westchester County in 80 years, a $1.9 billion project linking the Kensico Reservoir to a treatment facility in Mount Pleasant.

The two-mile-long tunnel will join the complex maze of reservoirs, tunnels, aqueducts and water mains that delivers roughly a billion gallons of drinking water per day to 9 million people in New York City and southern Westchester County.

It will connect the Kensico Reservoir, whose 30-billion-gallon capacity makes it a critical piece in the city’s water supply network, with the Catskill-Delaware Ultraviolet (CDUV) Light Disinfection Facility in Eastview, the largest of its kind in the world.

“Creating additional redundancy in our vital water supply system is an essential investment for the long-term resilience of the remarkable feat of engineering that provides more than 9 million New Yorkers with a reliable supply of pristine tap water,” city Department of Environmental Protection Commissioner Rohit T. Aggarwala said.

10-year project will deliver upgrades

During the first phase of the 10-year project, two large shafts dug between 400 and 500 feet into the ground will be connected by a tunnel.

When finished the Kensico to Eastview tunnel, measuring 27 feet in diameter, will be able to deliver as much as 2.6 billion of gallons of water each day. It will give the city the flexibility to take other parts of the water supply system out of service for inspection and maintenance.

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In addition to the tunnel, a 100-year-old intake chamber at Kensico Reservoir will be enlarged to bring water into the new tunnel. And the shoreline around the chamber will be improved to prevent sediment from entering the tunnel.

The Kensico Resvoir, built in 1915, takes in water from the Catskills and is part of the largest unfiltered water supply in the U.S.

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Later this year, the city’ DEP will begin $1 billion in improvements to the Hillview Reservoir in Yonkers, which delivers water from the Catskill reservoirs to tunnels leading into New York City.

Thomas C. Zambito covers energy, transportation and economic growth for the USA Today Network’s New York State team. He’s won dozens of state and national writing awards from the Associated Press, Investigative Reporters and Editors, the Deadline Club and others during a decades-long career that’s included stops at the New York Daily News, The Star-Ledger of Newark and The Record of Hackensack. He can be reached at tzambito@lohud.com.

This article originally appeared on Rockland/Westchester Journal News: Two-mile tunnel from Kensico Reservoir will be largest in Westchester since the 1940s