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NYC 9/11 Public Portal Document

Water System Tunnels and Aqueducts The Delaware Aqueduct: The Delaware Aqueduct similarly transmits water by gravity from Rondout Reservoir to West Branch Reservoir. in the Croton System, and from West Branch Reservoir to Kensico Reservoir and to Hillview Reservoir. The Delaware Aqueduct is a circular, cement-lined, pressurized, bedrock tunnel 85 miles long located 300 to 1.000 feet underground, passing beneath the Hudson River at a depth of ahnut 600 feet below sea level. Water in this aqueduct is directed by uptake and downtake shafts to the Kensico and West Branch Reservoirs. The Delaware Aqueduct has a diameter of 13.5 feet to 19.5 feet. The capacity of the section from Rondout Reservoir to West Branch Reservoir is about 890 mgd and delivers water from Rondout, Neversink, Pepacton and Cannonsville Reservoirs. the at both the Kensico and Hillview Interconnection with the Catskill System is possible Reservoirs. The delivery capacity of the Delaware Aqueduct from to Kensico Reservoirs is about 1,045 mgd and West Branch about 1,450 mgd from Kensico to the Hillview Reservoirs. DEP is currently conducting a program of reviewing and assessing the condition of the Branch Tunnel, which comprises a portion of the Delaware Rondout-West Aqueduct. The Rondout-West Branch Tunnel carries water 45 miles from the Delaware System under the Hudson River and into West Branch capacity of 900 mgd and normally contributes 50% of New Reservoir. It has a York City's water supply. A portion of the crosses a fractured rock formation which is potentially tunnel subject to greater stress than the deep rock in the City. In addition, the Rondout-West tunnels located Branch Tunnel is unique in that it attains the highest Water Supply System and thus requires more pressures in the maintenance than other tunnels in the System.rs a result tests, visual observations and other analyses, it has of flow been determined that a quantity of water is being the tunnel and surfacing in the form of springs or lost from seeps in this area. DEP has retained a professional firm to evaluate soil and rock conditions engineering along the Roundout-West Branch TunnV, to locate and cause and extent of any loss, and to propose any investigate the remedies that might be necessary. The tunnel was that it can be- shut down and de-watered if designed so necessary. The last such shut-down occurred in such shut -down, it will be necessary for the City 1957. During any to increase reliance on its other water supplies, more stringent measures to encourage conservation and to take and reduce demand. In general, the Delaware System continues to demonstrate a high degree of reliability after 55 years continuous service. Nevertheless, DEP considers it of prudent to conduct regular tunnel and aqueduct and surveys to detect any problems that might inspections arise so that corrective actions can be taken if needed.

NYC-WTC 000137716