Builder

In brief

The builder is the giant site manager. He turns the plans into a real dam, sometimes high in the mountains, in narrow gorges or in the middle of a river. Hundreds of people work with him.

How does it work?

Building a large concrete dam takes a lot of patience. Here is an example of the steps (they change depending on the type of dam):

1. Divert the river. You cannot build with your feet in the water! The river is first sent through a tunnel dug into the mountain, while a small temporary wall (a cofferdam) keeps it away.
2. Dig down to solid rock. Just like the foundations of a house, you need a very hard base.
3. Pour the concrete, in big blocks. Inside, small pipes of cold water cool it, because concrete heats up as it sets and could crack.

Key facts

• Depending on the dam, a large site lasts from a few years to nearly ten years.
• Depending on the case, cable cars are set up on site to carry equipment, along with a concrete plant and machines that crush rock.

Words to know

• Cofferdam: a temporary wall that keeps water away during the work.
• Foundation: the part that sinks into the ground to hold the dam up.

Did you know? The Hoover Dam, in the United States, contains miles of cold-water pipes. Without them, the concrete would have taken more than 100 years to cool down and would have cracked!

Going further

The machines depend on the place and on the dam being built. In the high mountains, a cable car can carry workers and materials when no road reaches the site. For a large concrete dam, a concrete plant is often set up nearby to make huge amounts of it.