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Back in my grade-school days, I seem to recall a book or a movie series or maybe a TV series called “They Said it Couldn’t Be Done“. It was about an entire series of structures that were deemed impossible to build, but were completed anyway, due to incredible feats of engineering, planning, and the work of human hands.
One of them was the Hoover Dam. Construction of this massive Lake Mead-maker, at the time the world’s largest concrete structure, began in 1931. But discussions, planning, and preparation started years before, in the early 1920s. The project was prompted by the need for better irrigation in the arid climate of the southwestern United States, as well as electricity for the growing population and flood control for the mighty Colorado River.
Of course, building a dam isn’t just a matter of dropping a pre-fab structure into place…there are procedures. The first step was to redirect the Colorado River, which was probably as difficult as it sounds. Engineers moved upstream and blasted four diversion tunnels through solid canyon rock (two on each side of the river). The tunnels bypassed the dam site and came out of the canyon downstream.
After the water was re-routed, the mud, silt, and debris in the river bed (and on the sides of the canyon) had be removed down to solid bedrock. Once all the digging was done (two years into the project), the concrete pouring began. Enough concrete was poured into the dam to build a two-lane road from San Francisco to New York, and just dumping it into a dam-shaped mold would have prevented proper curing. So it was poured in 6-inch layers, with cooling rods running between to more quickly set the concrete.
I’m reminded of Waylon Jennings’ verse in Highwayman (a favorite song of mine). He sings:
I was a dam builder across the river deep and wide
Where steel and water did collide
A place called Boulder on the wild Colorado
I slipped and fell into the wet concrete below
They buried me in that great tomb that knows no sound
But i am still around, I’ll always be around and around…
Of course, with only 6″ of concrete going into the dam at a time, Jennings’ character (or any of the others rumored to have fallen) would have to be whisper-thin to have been buried alive.
Still, more than 100 people died during the Dam’s construction, and roughly none of them are still entombed in the structure. Completed on March 1, 1936, Hoover Dam (originally called Boulder Dam) fulfills its intended purposes, offering flood control and providing power, mostly to California and Nevada.
At 726′ tall, it’s the 2nd tallest dam in the States. It is 660′ thick at the bottom, 45′ thick at the top, and contains more than 4,000,000 cubic feet of concrete. It provides more than 4,000,000,000 KWh of electricity to more than a million people.
And it contains no Highwaymen.
On a more personal note, today marks the 1st anniversary of Today’s History Lesson. The first year saw 277 posts over 366 days. I hope you’ve learned a little something…I know I’ve learned a ton. Nearly all of the 2009 calendar is already full, so if you’re still interested in reading, I’ve got more to write.
Thanks for reading!
Recommended Reading: The Hoover Dam Website – One of the best dam sites on the Internet.
Today's History Lesson 