DEP Breaks Ground on Water Tunnel; Additional Phases Under Review

The New York City Department of Environmental Protection (DEP) broke ground last week on a two-mile tunnel in Mount Pleasant so the agency can have operational flexibility in bringing water to nine million people.

The $1.9 billion project, known as the Kensico-Eastview Connection, will feature a multi-phase decade-long construction period. The tunnel will extend from the Kensico Reservoir to the Catskill-Delaware Ultraviolet Light Disinfection Facility (CDUV) in Eastview. The new tunnel would enable the DEP to take other facilities out of service for periodic maintenance and inspection and not jeopardize service for the 8.6 million New York City residents and roughly 500,000 Westchester County customers.

“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 nine million New Yorkers with a reliable supply of pristine tap water,” DEP Commissioner Rohit T. Aggarwala said in a prepared statement. “This project will help us fulfill our commitment to providing consistent and reliable delivery of the highest-quality water to New York City and the growing population centers in Westchester County.”

The first phase of construction, which was approved by the Mount Pleasant Planning Board earlier this year, includes site preparation at the DEP campus adjacent that is adjacent to the reservoir.

According to the DEP, the tunnel will reach depths of between 400 and 500 feet and will be 27 feet in diameter.

Other elements of the project include new facilities and site work near the reservoir and the CDUV. A roughly 100-year-old intake chamber at Kensico Reservoir will be upgraded and enlarged to draw water into the new tunnel, the reservoir’s shoreline around that intake chamber will be improved to prevent sediment from escaping into the new tunnel, and the Kensico campus will receive utility, grading and drainage upgrades.

A new screen chamber to remove debris from the water will be constructed just north of DEP’s main campus at the reservoir, near Columbus Avenue in Valhalla. The chemical addition systems at Kensico Reservoir will also be upgraded to ensure for the continued proper treatment of drinking water.

DEP is scheduled to build a connection chamber at CDUV in Eastview to receive water from the new tunnel. Work at this site will also include several projects related to drainage, stormwater and utility improvements.

It is projected that the entire project will be completed by 2035.

On July 15, DEP representatives made a presentation before the Mount Pleasant Planning Board to discuss plans for the second phase of the work. DEP engineer Justin Rivellino said staggered phases will see the first phase completed in late 2026, with the next two phases finishing in 2030 and 2033, respectively.

The DEP will require permits or variances for steep slopes, the potential for about 100 feet of wetland buffer disturbance and for blasting to get the shafts into the ground at either end of the tunnel, he said. A variance from the Zoning Board of Appeals will be needed because the estimated height of the construction fence will exceed six feet.

Planning Board members had several concerns, ranging from the type of construction fence that is expected to be up for about 10 years to the removal of about 140 trees and the DEP’s replanting plan. Board Chair James Collins said he hopes the DEP is planning adequate mitigation where Mount Pleasant will benefit despite the hardship of a lengthy project.

“This town has endured a lot of hardship with a lot of difficulty, a lot of trucks going back and forth,” Collins said. “There has to be something that we can look into that makes this one palatable for the community.”

He suggested that the DEP should return for the public hearing on the next phase when it has firm answers regarding the type of construction fencing it plans to use and the replanting plans.

“You’re spending a billion dollars or more,” Collins noted. “How do we improve the environment as a result of this project?”

The chairman suggested that similar to the late June public information session, the DEP should schedule another forum to answer residents’ questions. Last month’s forum did a good job at assuaging some fears in the community, Collins said.

No date was set for the public hearing. However, it is projected to be soon, since the Rivellino said the DEP hopes to begin construction on the second phase by the end of the year.