The Catskill Aqueduct is a 92-mile conduit that carries drinking water from Ashokan Reservoir in Ulster County to Hillview Reservoir in Yonkers. The aqueduct conveys about 40 percent of New York City’s drinking water on an average day, and it can deliver up to 590 million gallons per day.

This project, one of a few of its kind, sets a precedent: it represents one of the largest aqueduct pressurization projects in the world for water supply. Pressurization would increase the hydraulic capacity of this aqueduct segment an additional 300 MGD and allow for reservoir bypass when needed, which provides advantages in system flexibility and operations.

The conceptual design was developed taking into consideration several rehabilitation options for each section of the aqueduct segment, while carefully balancing considerations of costs, schedule and allowable leakage goals.


Rehabilitation of Existing Structures Venturi Meter Chamber

A new ventilation system was installed for the Venturi Meter Chamber as part of CAT-342, the new system consisted of a roof mounted fresh air intake hood and exhaust fan.  The intake hood and exhaust fan was sized to maintain 3 air changes per hour (ACH).  The exhaust fan has two-speed operation and will be interlocked with a motorized damper in the fresh air intake hood.

Electrical system design included the upgrading of the electrical service, power distribution and lighting.


Catskill Connection Tunnel Chamber & Catskill Connection Tunnel

HVAC system design included heating system for Catskill Connection Tunnel (CTC) superstructure, air conditioning systems for electrical room, heating and ventilation system for upper operating level and utility building and automatic temperature control systems.

Electrical system design included 166 kVA stand-by emergency generator, power distribution, interior lighting, outdoor lighting and lighting protection systems.


NYC Department of Environmental Protection


Hazen & Sawyer


163 Miles


Mechanical Engineering
Electrical Engineering

Construction Cost

$700 Million

Completion Date



Mr. Richard Peters
Hazen & Sawyer
498 Seventh Avenue
New York, NY 10018
(212) 539-7141