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Grand Coulee Dam
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Vital Statistics:
Location: Grand Coulee, Washington, USA
Completion Date: 1942
Cost: $300 million
Reservoir Capacity: 421 billion cubic feet
Type: Gravity
Purpose: Flood control, hydroelectric power, irrigation
Reservoir: Franklin D. Roosevelt Lake
Materials: Concrete
Engineer(s): Bureau of Reclamation

The Grand Coulee Dam, located on the Columbia River in central Washington, is the largest single producer of electricity in the United States. Made from 12 million cubic yards of concrete, the Grand Coulee Dam is also one of the largest concrete structures in the world. But engineers were confronted with a unique problem when building such a massive concrete dam.

Grand Coulee Dam
Click photo
for larger image.

When concrete is made, it produces a chemical reaction that gives off heat. As concrete cools, it gradually shrinks. If the shrinkage is not controlled, cracks can form -- and cracks are disastrous in dams. The solution? Engineers pumped cold water through an intricate network of pipes in the concrete to help cool the concrete as it hardened. It's a good thing they did this, because it would have taken 200 years for the concrete to cool naturally, and many cracks would have formed!

The Grand Coulee Dam is the largest producer of hydroelectric power in the United States and the third largest hydroelectric facility in the world. With its 28 generators producing up to 23,860,944,469 kilowatt-hours annually, it is the primary source of electric power to states in the Northwest.

Here's how this dam stacks up against some of the biggest dams in the world.
(reservoir capacity, in cubic feet)

Chart showing the relative size of the biggest dams in the world Grand Coulee Dam
421 billion cubic feet

Fast Facts:
  • The base of the Grand Coulee Dam is almost four times as large as the base of the Great Pyramid of Giza.
  • If all of the pipes used to cool the cement in the Grand Coulee Dam were laid end to end, they would stretch from New York City to the Grand Canyon!
  • There is enough concrete in the Grand Coulee Dam to build a highway across the United States.

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