New York announces 2-mile water tunnel

18 July 2018

USA – The New York City Department of Environmental Protection (DEP) announced plans for USD 1.2bn tunnelling project in Westchester County on 12 July.

The Kensico-Eastview Connection (KEC) will be a 2-mile- (3.2km)-long tunnel between the Kensico Reservoir and the Catskill-Delaware Ultraviolet Light Disinfection Facility in Eastview. DEP said it expects the finished tunnel to measure approximately 27ft (8.2m) in diameter and run 400-500ft (122-152m) below ground. The tunnel will be large enough to carry a maximum of 2.6 billion gallons (9.84 billion litres) of water each day.

The new aqueduct will provide an additional conveyance between components of the water supply system, giving DEP the ability to take other facilities out of service for periodic maintenance and inspection.

“The Kensico-Eastview Connection is a critical investment in the long-term resiliency of New York City’s water supply system,” DEP commissioner Vincent Sapienza said. “By providing an additional connection between Kensico Reservoir and our treatment facilities to the south, this new tunnel will further guarantee the reliable delivery of water to New York City and population centers in Westchester County, including New Rochelle, White Plains and Yonkers.”

The KEC project will include construction of the new tunnel, facilities to draw water from Kensico Reservoir and move water into the ultraviolet plant, and other infrastructure work. In 2017, DEP collected soil and bedrock samples from the area to support the design of the project, which has already begun. Construction on the first portions of the KEC project are expected to start in approximately five years; work on the tunnel itself is expected to begin around 2025. DEP said it expects to finish the project around 2035.

In addition to the work at the Kensico Reservoir, DEP will also build a connection chamber at the ultraviolet plant to receive water from the new tunnel. The chamber will connect to a number of existing pipes at the ultraviolet facility that were installed at the time of its construction. Work at this site will also include a number of projects related to drainage, stormwater and utility improvements.

During the next several years, DEP said it will work toward completing the design of the tunnel and the facilities that will connect it to the reservoir and ultraviolet plant. It will also start the process of environmental review and obtaining dozens of permits from federal, state, county, city and local agencies.

Although the project is located in Westchester County, its work centers on the delivery and treatment of pristine drinking water that comes from six reservoirs in the Catskill Mountains. Kensico Reservoir was built in 1915 as part of New York City’s Catskill Water Supply System. Kensico was later modified in the 1940s to receive water from the City’s Delaware Water Supply System, also in the Catskills. Those two systems—collectively referred to as the Catskill-Delaware System—comprise the largest unfiltered water supply in the US.