1. The Construction of Hoover Dam
Technical problems and Solutions

2. Hoover Dam

3. Lake Mead

4. The Dam Located on the border between Arizona and Nevada
Blocks the Colorado River
Hoover Dam created Lake Mead behind it
Construction began 1931, initially on the four tunnels used to divert the river away from the building site

5. The Dam Construction of the actual dam began 1933
Nothing of this magnitude had ever been attempted before
As a result there were many problems with untested solutions

6. Site Preparation River water diverted
This was done using four tunnels, two either side of the canyon
In total the tunnels spanned a length of 16,000 feet (3 miles)
The tunnels were dug out using dynamite

7. Site Preparation Scaling the cliff walls and removing any loose rocks
This work was needed to ensure that when the dam was built it would stay firmly in place and not crumble away at the edges

8. ‘High Scalers’
The men who were given the job became known as ‘High Scalers’
The workmen were required to hang from ropes off the edge of the cliff and use jackhammers and dynamite to blast off loose rock
They weighed 44lbs

9. High Risk
Many men died from falling tools or slipping and falling off the cliff
As a result the men invented hardhats to stop them getting fractured sculls from falling objects
They did this by filling cloth hats with tar

10. Rescue
A spectaculuar example of the dangers involved is a story of a man who slipped and fell. 25 feet below another worker leapt off the cliff, holding onto his rope, and caught the man’s foot. Another worker pinned the man to the cliff until he could be rescued.

11. ‘High Scalers’

12. Construction Construction began in 1933
The first problem engineers faced was the sheer amount of concrete needed to build the dam
A site to make concrete was first built upstream and later one was built on the edge of the canyon

13. Problems
Another problem faced was the fact that concrete produces heat as it sets. Had the dam been created in one pour, the heat generated would have meant the dam would not have set for 125 years. This would have created cracking and erosion.

14. Another solution A solution was devised by engineers
The dam was to be built with a series of concrete pillars, trapezoidal in shape, joined with interlocking grooves
When set, the blocks were pressure grouted together

15. Blocks of concrete

16. Problems and Solutions
Pouring the concrete in separate blocks was only part of the solution to the concrete problem
The dam was in the middle of the desert and the heat was setting the concrete too fast

17. Pipes
To solve this problem, a system of pipes was woven throughout the concrete and filled with cold water. This slowed down the setting process
Later the pipes were removed and the holes filled with grout