Environmental Engineering Reference
In-Depth Information
Crumbling infrastructure is, in fact, as much a domestic threat to America
as terrorism is. If ignored, either one could have catastrophic effects on
our civilization.
Much of the infrastructure we use today was proposed and built
during the administration of President Franklin Delano Roosevelt in the
1930s to reduce the 25 percent unemployment rate during the Great
Depression. His Works Progress Administration built 78,000 bridges and
viaducts and improved 46,000 more. It also constructed 572,000 miles
of rural roads and 67,000 miles of urban streets.
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These types of massive
public works programs have faded into history. Unless a dramatic catas-
trophe occurs, such as a major bridge collapse that causes the death of
many people, sewage backing up into people's homes, or an electrical
failure that results in a blackout of most of the Northeast, Americans
tend to ignore infrastructure and its need for continual maintenance,
repair, and upgrading.
Pipes for Water
The bulk of the water and sewer lines beneath American streets were
installed in three phases: at the end of the nineteenth century, in the
1920s, and just after World War II as adjustments to periods of popula-
tion growth in cities and expansion into suburbs. Hence, most of the
water mains in American cities are very old; many were built more than
one hundred years ago.
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Americans use 10 trillion gallons of water every year that reaches our
homes through 880,000 miles of water mains. Depending on the age of
the pipe, the pressure in the pipe, and other conditions, the pipes may
be made of concrete (12 percent), PVC plastic (39 percent), cast iron (48
percent), or clay (1 percent).
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Each of these materials may deteriorate
with age. Concrete is composed of calcium carbonate (artifi cial lime-
stone) that dissolves over the decades in contact with water, PVC plastic
may crush because of freezing and thawing of the soil around it or
because of a new building erected overhead, cast iron may rust, and clay
is not a durable material.
Because of their age, many of the water mains in American cities leak.
The largest single consumer of water in most cities is not a family or a
factory but leaky water pipes. Millions of gallons of water are lost every
day in every major city in the United States. There are 250,000 to
300,000 breaks in water mains each year—one break for about every 3
miles of pipe.
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Fifteen to 20 percent of drinking water in the United States
