Moving to solve a key problem in a resolute, and even economically stimulating way, New York City has announced a $2 billion plan to fix its Delaware Aqueduct, which carries more than 500 million gallons daily but loses up to 35 million gallons every day from severe cracks in two areas of Ulster and Orange counties.
The plan calls for creating a three-mile long water bypass under the Hudson River from Roseton, in the town of Newburgh that will run east 600 to 800 feet under the Hudson River to the town of Wappinger in Dutchess County. Additionally, the city will re-grout a much smaller problematic section of tunnel in Wawarsing that in the past has leaked tens of millions of gallons and inundated parts of the town.
The plan will put pressure on local officials who use water from the aqueduct to ensure they arrange a backup supply sufficient to meet their needs for a year or more starting in 2018, when the existing tunnel will be shut down and drained, to allow for interconnection with the new bypass and to allow engineers to enter a section of the tunnel in Wawarsing to make repairs.
New York City Environmental Protection Commissioner Cas Holloway said city engineers are confident that a bypass tunnel will eliminate the leaks, which he said have generally developed where the aqueduct passes through limestone rock formation that are weaker than other geologic formations. The section that is bypassed will be sealed and shut.
Construction of the bypass tunnel is to begin in 2013 and be completed by 2019 at a cost of about $1.2 billion. An additional $900 million will be spent on projects to supplement the city”™s water supply during part of the construction period, officials said. As many as 1,500 construction related jobs would be created by the work, Holloway said.
He said the city has no choice but to spend the funds.
“Ensuring the integrity of New York City’s vital infrastructure is fundamental to our long-term growth and prosperity,” he said.
The same is true for localities in this area, said Glenn Gidaly, a planner with the engineering firm Barton and Loguidice that works on water issues with several Hudson Valley municipalities. Those towns that tap into the aqueduct systems are already obligated to have “redundant supply,” but may have to increase the capacity of that alternate source to meet the needs of a shutdown. Options include interconnections with other municipalities, drilling new wells for meeting local supply or increasing the capacity of local reservoirs.
There are two city aqueduct systems, the Catskill system, completed in 1916 and the Delaware, completed in 1944 that together are considered among the finest water supply tunnels in the world providing more than a billion gallons daily to 8 million users in New York City, and an additional one million users in Westchester, Putnam, Orange and Ulster Counties.
The Delaware water supply system consists of four reservoirs the feed water to the 85-mile Delaware Aqueduct to convey drinking water into city water tunnels, mains and eventually taps. With a capacity of 900 million gallons of water a day, it carries about 500 million gallons daily.
The aqueduct is the world”™s longest continuous tunnel, yet took only five years to complete. It was designed to last a century but severe cracking and leaks developed in 1988. The aqueduct is a concrete-lined tunnel that varies in diameter from 13.5 to 19.5 feet and runs as deep as 1,500 feet beneath the ground. In most areas, it is lined only with unreinforced concrete. In areas where the rock is not as strong, a steel reinforcement liner was added to the concrete liner.
