Blasting Through Solid Rock to Safeguard New York’s Reputation for the Best Pizza and Bagels
Hundreds of feet below the bottom of the Hudson River, at a spot a half day’s sail north from the Battery Park City esplanade, sandhogs (as workers who excavate tunnels are known) are busy blasting and boring a new tunnel to keep the finest fresh water in the world flowing into New York City.
This project is digging a 2.5-mile-long tube 600 feet below the floor of the Hudson, between Newburgh and Wappinger, to serve as a bypass that runs parallel to an existing tunnel — the Delaware Aqueduct — that carries about half of New York’s drinking water from reservoirs in the Catskill Mountains, using only gravity. Built in the 1940s, the Delaware Aqueduct (at 85 miles from end to end, the longest tunnel anywhere in the world) had developed several major leaks by the 1990s, one of them directly below the Hudson River. It is now estimated to lose about 35 million gallons per day — equivalent to more than 50 Olympic-sized swimming pools every 24 hours, which comes to more than 400 gallons per second.
In the 1980s, the City began planning a workaround. Actual construction didn’t start until 2013, and was largely completed earlier this year, marking the first tunnel built under the Hudson River since 1957, when the south tube of the Lincoln Tunnel was finished. What remains is to connect the ends of the new tunnel (known to engineers as the Rondout-West Branch Bypass) to the existing Delaware Aqueduct, then reroute water flow into the new tube, after which the leaking portion of the original structure will be sealed off and abandoned.
Announcing the start of this final phase of work on September 30, Mayor Eric Adams said, “New York City’s tap water is the envy of the world — it’s why we have the best pizza and bagels in the country.” This was a reference to the widespread belief that the unique mineral content of New York drinking water is the accidental elixir that makes it so difficult to produce comparable dough in other regions of the country, needed for the City’s signature culinary items.
Work is now underway to shut down the Delaware Aqueduct temporarily, to allow sandhogs safe access to blast into its walls and create connections at either end of the new bypass tunnel, which is 16 feet in diameter. This phase is anticipated to continue for roughly eight months, during which time reservoirs on the east bank of the Hudson Valley will take up the slack, supplying the City’s full load of 1.1 billion gallons of drinking water each day.
Water that comes out of taps in Lower Manhattan originates largely in the Delaware Aqueduct, but starts the final leg of its journey at the Hillview Reservoir, in Yonkers. There, it enters Water Tunnel No. 3 (a separate project that began construction in 1970, and entered service in phases, starting in 1998), which proceeds through the Bronx, under the Harlem River and across Central Park, before snaking down the west side of Manhattan to a point around 500 feet below Canal Street, where vertical shafts connect it to the local network of water mains, closer to the surface. (Lower Manhattan access points to this tunnel — square concrete blocks in the photograph above — can be seen in a fenced-off, vacant lot at the northeast corner of West Houston and Hudson Streets.)
This tube, 12 feet in diameter, is still under construction, and is not expected to be fully built out until the early 2030s, when it will connect to remote parts of Brooklyn and Queens, before doubling back to the Bronx and Westchester, creating a second connection to the Hillview Reservoir.