Field Trip: Hoover Dam

For the first time in a while, my wife and I had the same spring break at our two different school districts. We took advantage and headed west to the warmer climes of Las Vegas. Yes, we headed through a number of casinos (sight-seeing, no gambling for either of us) and the Neon Museum (which is spectacular but could use more money for rebuilding the old signs), but the highlight of the trip - from a material science perspective, anyway - was our visit to and tour of Hoover Dam.

The tour started with a video on the history of the Dam. The video took about fifteen minutes. For our tour we had about twenty minutes between the end of the video and our muster time for the tour itself. That left us enough time to see some of the exhibit hall.

We took the packed elevator down to the first stop, shown above. The outer, fifty-foot diameter, concrete tunnel is one of the original diversion tunnels the took the flow of the Colorado River and allowed for the building of the Dam in 1931. The inner, thirty-foot diameter tunnel is the Nevada-side outflow from the spillway. It's been since 1999 that the water was high enough to use the spillway, sadly. Lake Mead is currently at 41% capacity, enough for a year but just barely.

The inner tunnel is made of  'three-inch-thick boiler steel' according to our tour guide.

The next stop of the tour was the pump house which contains eight generators. (The Arizona side has nine generators just like these.) Sadly I didn't get the various quoted statistics about the generators - how many stories tall each is, how many tons each shaft is, how many thousand gallons go through each generator at full capacity per minute. In effect, they all said that the generators are massive.

Generator N6 (the sixth generator on the Nevada side of the Dam) was out of commission and partially dismantled. This let us see the gigantic copper coils that ring the outside of the generators.

Our next part of the journey took us through one of only two areas in the Dam (the final stop being the other) that were finished and fancy for the visitors. The tunnel had terrazzo (a composite) floors that contained stones from all forty-eight states at the time.

The next tunnel was much more unfinished, showing the bare concrete of the Dam. The concrete still showed the wood grains of the forms used to shape it eighty years ago.

With a quick right turn from the main tunnel (seen above) into a shorter (5' 9" in the center) tunnel, we headed to a vantage point  to look out from the front of the Dam.

The photo below is way out of order, taken from the top of the Dam at the very end, after the tour officially ended. It is, however, a great chance for me to show just where the above tunnel comes out. The tunnel ends in a vent on the face of the Dam. It's a vent used to get fresh air into the Dam tunnels and to allow fools like us to look out safely.

The final part of the tour in the Dam itself was the most fascinating from a material science perspective. Our tour guide showed us the markings on the bare concrete walls marking the lines between each 50'x50' block of concrete. This mark shows the line 50' from the start of block O, the fifteenth block from the Arizona side of the Dam.

It's also where the engineers put bolts to check the settling of the different blocks. Just below are the bolts between block P and block O as well as a metal bar used for calibration. The bar is attached only to block P and shows that the O block has settled by about an inch more than has the P block.

The Q block has settled a little more than has the P block, as well.

The last part of the tour took us to the top of the final elevator journey where the elevator had copper doors; the lobby had green and black, art deco inlaid floors and walls; and the doors out of the lobby were a gorgeous, brilliant, original brass. As our tour guide told us, the lobby (and the tile tunnel earlier) was made so fancy because the Dam builders knew we were coming, that people would be visiting the Dam for hundreds of years.

He'd earlier pointed out that people have been studying the concrete of the Dam for eighty years, that the concrete poured there was still state of the art technology decades later. He told us that the builders of the Three Gorges Dam in China had spent a decade studying inside the Hoover Dam before they began construction of their Dam.

That's the visitor center on the right and the 'new' bridge on the left.

Lake Mead there, behind the Dam is fascinating, as well, but that's not a material science study. I'll leave that for the geologists and hydrologists and climatologists. That's a different blog.

If you're interested in visiting Hoover Dam, some tips...

• Check all the details on the Bureau of Reclamation's website
• Tickets for the Dam tour (which includes the pump house tour) are $30 per person, and that includes the normally $10 entry fee to the Dam.
• Tickets for the pump house tour are $15, and that, too, covers the entry fee to the Dam. The pump house tour is really brief, though. Splurge for the Dam tour. It's way better.
• Parking at the Dam is $10 per car, but at least it's in a nicely covered and shaded parking garage.
• Traffic from the highway backs up really badly because every car has to stop at a security checkpoint before heading toward the Dam. When we got to the Dam at 8:30, this wasn't a problem at all. We had to wait one for one car ahead of us. When we left at 1pm, however, the line was at least fifty cars long.
• It is possible to just drive across the Dam, but it won't be fast - because of security and because people are constantly stopping or slowing their car to take photos from the window. There is a 'new' highway bridge just south of the Dam that has sped up general travel from NV to AZ.
• The visitor center opes at 9am. Pump house tickets can be purchased in advance, but Dam tour tickets can only be purchased the day of and in person at the visitor center. The first tickets sold are for the 9:30 tour, and only twenty people can go on each tour. Tours run every half hour.
• We got into line at the visitor center at about 8:45 and got on the 10am tour. There were probably twenty or twenty-five people in line ahead of us, but at least the entire line was formed in the shade of three large canvas sun shades and a walls of the visitor center entrance.
• The tour does require people to fit into a very tight elevator. Anyone with any claustrophobia should be very leery of going on either tour.
• The Dam tour does end on the top of the dam about a third of the way across from NV to AZ. It's a little walk back to the parking area but not a bad one.