Far, Far Below Ground, Directing Water to New York City’s Taps
NEWBURGH, N.Y. — City government often looks small. Petty, even. The parking ticket. The real estate tax bill. Sanitary inspection grades. Window-guard surveys. The fruitless call to 311 at 2 a.m. to complain about jackhammers outside.
From here, however, government doesn’t look petty at all — here being the bottom of a 350-foot-deep, 35-foot-diameter shaft through a 460-million-year-old shale formation in Orange County, 70 miles north of City Hall. It is an uninviting spot critical to satisfying one of New York’s City’s basic needs.
Miners in fluorescent yellow coats and full-brimmed hard hats await our departure from the Stygian cylinder so they can get back to the earsplitting excavation of a hole that will reach 900 feet into the earth, as deep as the Citigroup Center is tall. Rain cascades down the open shaft on this particular day and groundwater weeps through the layers of dark gray shale at the bottom of the pit, which has yet to be lined with concrete.
Across the Hudson River, in Wappinger, N.Y., miners are excavating a companion shaft. The two projects are to be finished next year, setting the stage for the real work, beginning in 2016: digging a two-and-a-half-mile tunnel from one shaft to the other.
http://tapatalk.imageshack.com/v2/14...bcbfdf0f78.jpg
Video | Fixing a Leak Underneath the Hudson New York City’s “Water for the Future” project is bypassing a leaky aqueduct underneath the Hudson River.
The tunnel will parallel and eventually bypass a long-troubled section of the Delaware Aqueduct, through which New York City receives about half of its 1.1-billion-gallon-a-day water supply. This part of the aqueduct has been leaking up to 35 million gallons of water a day for decades. Officials believe it is irreparable.
If all goes according to plan, the city’s Department of Environmental Protection will shut down the Delaware Aqueduct in October 2022. After the water has drained out, workers will connect each end of the new bypass tunnel to the older aqueduct, plug up the damaged portion permanently and make repairs elsewhere while they have the chance. Five to eight months later, they will reopen the aqueduct.
The Delaware Aqueduct bypass is an approximately $1 billion project that few New Yorkers will ever see, though it affects every New Yorker’s life. City government is still capable of thinking big when it has to — and in the case of the water supply, it must.
From late 2022 through early 2023, the city will compensate for the dry Delaware spigot by relying more on the Catskill and Croton watersheds. The Croton system, by far the oldest of the three, has been shut since 2008, while the city constructs a filtration plant in the Bronx. That should be finished next year.
http://tapatalk.imageshack.com/v2/14...eee53563c8.jpg
The city will also reactivate a groundwater system in southeastern Queens and institute conservation measures, like installing low-flow fixtures in public schools and housing developments.
“The idea of replacing 50 percent of the water supply for a long period of time was really daunting,” said Emily Lloyd, the commissioner of the environmental agency.
“You wanted to make sure you were designing a solution that was not too big,” she said, “but that was big enough to solve the problem.”
The bypass plan was devised in 2010 to overcome leaking that has been evident since the 1980s in a 45-mile tunnel between the Rondout Reservoir in the Catskill Mountains and the West Branch Reservoir in Putnam County.
http://tapatalk.imageshack.com/v2/14...27b119d677.jpg
Part of the Delaware Aqueduct has been leaking up to 35 million gallons of water a day for decades. Sean McAndrew, an engineer leading the project, said the new infrastructure would keep the water where it belonged.
ÁNGEL FRANCO / THE NEW YORK TIMES
In service since 1948, the Rondout-West Branch tunnel is the first leg of an 85-mile-long conduit that daily brings more than 600 million gallons of water, by gravity alone, from the Delaware River watershed in the Catskills to the Hillview Reservoir in Yonkers.
Water has flowed through the tunnel continuously since 1958, the last time it was drained for inspection — by a Jeep. To find the source of the leaks without emptying the tunnel, the city sent a robotic submarine developed by the Woods Hole Oceanographic Institution through the tunnel in 2003. Its five digital cameras took 160,000 pictures.
The bad news was that it found cracks in the concrete tunnel through a limestone formation just west of the Hudson. “The good news was that we didn’t have a gaping hole,” said Paul V. Rush, an engineer and the deputy commissioner of the city’s environmental protection department in charge of the Bureau of Water Supply.
Engineers in the 1940s knew they were boring through an unstable area of limestone. So they reinforced the concrete tunnel with 1,100 feet of steel interliner. Bureau lore has it that as little steel was used as possible, since the tunnel was being built during World War II, when every ounce of steel was needed for the war effort.
In any case, the interliner proved way too short, said Sean McAndrew, an engineer who is leading the agency’s repair project.
By contrast, the new bypass tunnel, 13 ½ feet in diameter, will have a steel interliner for 9,000 feet, or nearly two miles, bridging the limestone zone under the Hudson between two far more stable formations of Normanskill shale on either side.
“We’ll keep all that water in the tunnel,” Mr. McAndrew promised. “Where it belongs.”
http://mobile.nytimes.com/2014/11/20...html?referrer=
Sent from my iPhone using Tapatalk
