Village of Sleepy Hollow Water Tank & Transmission Line

Mount Pleasant, NY

AI, through close coordination with the Village of Sleepy Hollow, the Town of Mount Pleasant, the State of New York, and the National Historic Trust (NHT) designed and managed the construction of a 1.6 million gallon water storage tank and 3,500 ft. of 16-in. diameter water transmission main. The construction of the Sleepy Hollow Water Tank was a federally funded, locally administered public works project built on private land that is owned and maintained by the NHT within the Rockefeller Estate.

The project also included the installation of two (2) automated control valves and chambers, connected to existing SCADA systems, and designed to alternate water use between this new tank and an existing tank.

The 140-ft. diameter pre-stressed concrete tank was constructed inside of a 180-ft. diameter easement and within 500 ft. of the Rockefeller Estate’s historic Carriage House. Approximately 20,000 cy. of rock was blasted and some reused on the site to create a low, decorative stonewall which also concealed the tank from view. A 55,000 sf. block wall was also constructed around the curved perimeter of the rock cut as part of this project. Finally, 200 native species trees were replanted to replicate the surrounding old-growth forest.

A major constraint of the project was space and the footprint of the construction easements that the NHT permitted. All work was completed within the tight constraints with no adverse impact to the historic grounds’ facilities or operations. A design goal for the project was for the tank to be hidden from view; therefore the tank is virtually buried with only its top slab exposed.

The project was essential to the Village of Sleepy Hollow in order to meet and exceed its daily water storage requirement. It has also allowed the Village to exceed its current population by twenty percent. This will enable ongoing and future private local development.


  • Client: ConnDOT
  • Duration: 2002 - Present
  • Project Scope:
    • 1.6 M-Gallon Water Tank & Transmission Line Design
    • Construction Management