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Water system due for upgrade

By Roger Witherspoon



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The Journal News (Westerchester County, NY)


The Journal News

December 21, 2003 Sunday


Delaware Aqueduct leaks prompt state to study alternatives


The Department of Environmental Protection has begun a $50 million, 10-year effort

to increase water storage capacity and conservation programs for the massive

system that serves more than 9 million people in Westchester and Putnam counties

and New York City.


The project was spurred by the deteriorating condition of the Delaware Aqueduct, the

largest of three major underground water tunnels bringing fresh water from the

three watersheds serving the New York City water system. Of the 1.4 billion gallons

of water used daily, the Delaware provides 50 percent to 70 percent from reservoirs

about 100 miles north of Putnam. The remainder is provided by the Catskill

watershed upstate and the smaller Croton watershed in Westchester and Putnam.


Yet the Delaware Aqueduct is leaking up to 1.2 billion gallons per month, more than

the combined daily water usage of 13 central and southern Westchester

communities.


In June, engineers from the Woods Hole Oceanographic Institution in Massachusetts

lowered a $2.4 million autonomous sub down a 1,000-foot access shaft into the

aqueduct at Wawarsing, letting it float through the West Branch Reservoir and taking

36,000 digital photographs of the water tunnel to try to pinpoint the leaks.


"There is not a single catastrophic failure point or hole in the tunnel," DEP

Commissioner Christopher Ward said. "But it did find a whole long range of spider-

pattern cracks and liner cracks stretching about 3,200 feet. There is no single failure.

It looks like the lines of the face of an aged person, and perhaps this is just what a

tunnel this old looks like."


A departmental study of the water system estimates that with existing conservation

and alternative methods of obtaining drinking water, primarily from the Hudson

River, a shutdown of the Delaware Aqueduct could trigger a shortage of more than

400 million gallons of water daily. Meeting that need would be difficult, DEP officials

said, if the cracked section of the Delaware water tunnel either collapsed or was

closed for replacement or repairs.


The Woods Hole analysis found cracks ranging from one-tenth of an inch to 2 inches

wide in the tunnel's steel and concrete lining. Most are on the western side of the

Hudson River, but the deterioration continues under the riverbed. Tests of the rock

structure immediately surrounding the tunnel on the western side found most of it to

be intact.


"The notion of tunnel pressure blowing out a large portion of the wall is considered

geologically impossible," Ward said. But the aqueduct's wall will not last indefinitely,

he added. The DEP is gearing toward the possible need to shut down the aqueduct's

Rondout-West Branch section in 2012 and replace it with a tunnel bypass from the

West Branch Reservoir in Kent, under the Hudson River to the Roseton area in

Orange County.


"Building a tunnel bypass would be such an expensive undertaking," Ward said. "It

would cost $4 billion to $5 billion easily. It is definitely something we have to

consider, but I'm just sort of choking on having to say it, given the price."

To get a better idea of how badly the tunnel has deteriorated, the department plans

to develop a remote-controlled submarine with a 13-mile tether to perform close-up

studies of the cracked wall.


"Nobody has ever built a tether that has to be as long as this tether," Ward said.

"People have asked why we didn't do this sooner, and the answer was the

technology just wasn't there. But I'm told such technology now exists, and we hope

to have it fabricated in about a year."


The tethered sub would be able to hover next to the cracks, despite the fast-moving

water, and provide more detailed photographic and sonar information about the

breaks in the wall and, possibly, the health of the rock behind it. Ward said the new

submarine could cost about $4 million.


Ward's statements that the Delaware Aqueduct cannot be depended on to meet

long-term regional needs mark a departure from the DEP's position during the

administration of former Mayor Rudolph Giuliani that the leaks posed no long-term

risk.


"We certainly commend Commissioner Ward for recognizing the seriousness of the

infrastructure repair issues and committing the resources to developing solutions,"

said Mark Yaggi of the environmental group Riverkeeper, which frequently clashed

with the DEP in court over its watershed policies. "No one will know if or when the

Delaware Aqueduct may collapse. The only thing we know for sure is that it isn't

going to fix itself, and a collapse will be catastrophic. These steps are reassuring in

terms of securing the city's long-term drinking water needs."


Every component in the city's water system, which used hollowed-out tree trunks for

pipes until the mid-1800s, has to remain in perfect condition during the years it

takes for repairs, or the region would face even more serious water problems.


Yet, according to DEP documents, "many of these components are approaching 100

years of service without proper inspection, rehabilitation, or repair."


"The existing water supply system cannot meet system demands for the time during

which the tunnel must be taken out of service for its repair," the documents said.


To meet those needs, Ward has ordered two "dependability studies" of conservation

measures that may be taken to improve the region's water capacity. The $50 million

cost would be included in the department's capital budgets.


The issues to be studied range from giving residents rebates to purchase water-

efficient home appliances to finding ways to capture excess water.


"Right now we are losing about 10 billion gallons of water daily out of the reservoirs

because there is so much overcapacity," Ward said. "We could manage that water

better. If we could capture it in times of plenty, we could let it out when times are

lean."


During last year's drought, Ward said, residents saved 50 million to 100 million

gallons of water daily with voluntary conservation. Conservation of as little as 5

percent, he said, represents a water savings of more than 50 million gallons a day.


"When you talk of dependability, you have to look at everywhere the water might

be," Ward said. "We are trying to think more regionally than we have before."


Reach Roger Witherspoon at rwithers@thejournalnews.com or 914-696-8566.


Proposed conservation measures


* Pump up to 50 million gallons of water daily into Lloyd's Aquifer, which extends

from Long Island Sound to central New Jersey's Pine Barrens. Because of heavy rains

during the past year, the watershed's 18 reservoirs and three lakes are all

overflowing.


* An $8 million study will determine if deep wells can be sunk throughout Brooklyn,

Queens and Staten Island to tap into the aquifer and pump excess water into it. In

five years, there would be enough water stored to allow New York City to draw 200

million gallons daily for two years, if needed. The state Department of Environmental

Conservation has banned use of the aquifer for the past 18 years, and the city would

need permission to use it.


* A bypass tunnel and possible routes to take water from the Rondout Reservoir to

the West Branch Reservoir.


* Raise the height of two dams in the reservoir system, including the Croton Dam,

by 3 to 5 feet.


* Rebates to residents who purchase water-efficient dishwashers and washing

machines.


* Build desalinization plants on Long Island and along the Hudson River to convert

seawater to drinking water. The Hudson is a saltwater tidal estuary that runs more

than 150 miles from Manhattan to Troy.


* Convert the Chelsea pumping station in Manhattan into a water filtration plant that

could take water from the Hudson and add it to the Delaware Aqueduct's system.

The station would have to be capable of removing chemical contaminants such as

polychlorinated biphenyls, or PCBs, from the Hudson as well as zebra mussels and

other invasive organisms.


* Connect to water systems in Connecticut and New Jersey to augment shortfalls in

the New York City system.

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