Environmental Engineering Reference
In-Depth Information
maintenance, and the DEP faces a growing list of problems: infirm dams and seeping
water tunnels, sewage overflows and industrial water pollution, pressure from develop-
ment and gas drilling in the watershed, tension between rural communities and the city
over control of water, competition with neighboring states for future drinking supplies,
and worries about the impact of climate change on water quality and quantity.
Aging infrastructure is a growing problem nationwide, but the decline has occurred
largely out of sight, both literally and figuratively. he American Society of Civil Engin-
eers (ASCE), the nation's oldest engineering society, has reported that much of the na-
tion's hydro-infrastructure is on the verge of failure. In its 2009 Report Card, ASCE gave
the nation's infrastructure a D, or “Poor,” grade, and waterworks earned some of the
worst grades of all: the nation's dams were given a D, while drinking water, wastewater
treatment plants, inland waterways, and levees all received grades of D-minus, meaning
they are dangerously compromised.
In New York, DEP engineers are especially concerned about the state of the city's two
main water arteries—City Water Tunnels No. 1 and No. 2.
Tunnel No. 1 was completed in 1917. It runs eighteen miles, from Hill-view Reser-
voir in Yonkers (now a large city in Westchester County, two miles north of Manhattan),
through the Bronx, across the Harlem River, down the west side of Manhattan, under
Central Park, over to the Lower East Side, and across the East River to downtown
Brooklyn, where it terminates at Schermerhorn Street and Third Avenue. Most of Tun-
nel No. 1 lies about 250 feet deep, and it carries 500 to 600 million gallons of water a
day. But it began to leak even before it was officially turned on. Since then, new types of
concrete and grout have been developed specifically to patch New York's water tunnels.
Tunnel No. 2, completed in 1936, carries 700 to 800 million gallons of water per day.
It begins at Hillview Reservoir and runs through the Bronx, before bending south un-
der the East River to Astoria, Queens, and running along the length of Brooklyn to New
York Bay, where it connects to the Richmond tunnel, a five-mile spur that carries water
to Staten Island. Tunnels No. 1 and 2 were connected at the Battery, on the southern
end of Manhattan, to form a continuous loop.
Both tunnels have been in continuous service since the day they opened, delivering
the vast majority of the 1.3 billion gallons consumed daily in the city. But the two origin-
al water tunnels have grown fragile and now leak a large amount of water. The city does
not provide total estimates for leaks, though it admitted that the Delaware Aqueduct
was leaking between 10 and 36 million gallons of water per day before repairs in 2008.
I have been told by a person close to the DEP that for years the city hardly bothered to
measure its water use and had no idea of how much water was being lost. In the early
2000s, the DEP improved its water metering, regularly checked its pipes with sonar, and
used temperature and pressure sensors to identify leaks. But it is virtually impossible to
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