The 3.2km-long tunnel from Kensico to Eastview and facilities upgrade will improve the operation flexibility of drinking water supply for more than 9 million people in the City and southern Westchester County. It is New York City’s largest water tunnelling project in Westchester County since the 1940s.

The new tunnel between Kensico Reservoir and the Catskill-Delaware Ultraviolet Light Disinfection Facility in Eastview will provide additional infrastructure, giving the Department of Environmental Protection (DEP) the ability to take other facilities out of service for periodic maintenance and inspection.

“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,” said DEP commissioner Rohit T Aggarwala said. “This project will help us fulfil our commitment to providing consistent and reliable delivery of the highest-quality water to New York City and the growing population centres in Westchester County.”

The first phase of construction includes site preparation at the DEP campus adjacent to Kensico Reservoir, followed by excavation of two large shafts 122-153m deep, building the 8.3m diameter tunnel between the two shafts, and new facilities and upgrades at the Kensico campus. These include upgrading and enlarging a century-old intake chamber at Kensico Reservoir to draw water into the new tunnel, and improving the reservoir’s shoreline around the chamber to prevent sediment escaping into the new tunnel.

DEP will also build a connection chamber at CDUV in Eastview to receive water from the new tunnel.

The new tunnel, which will have the capacity to carry 2.6 billion gallons of water a day, will be operational by 2035.

Kensico Reservoir is located north of White Plains and is a vital component of New York City’s Catskill-Delaware Water Supply System. It stores approximately 30 billion gallons of water at full capacity. DEP draws about 1 billion gallons of drinking water from Kensico Reservoir each day to meet the demand of 8.6 million residents in the five boroughs of New York City and approximately 500,000 residents of Westchester County.