Hoover Dan has been an oft-mentioned target for a terror attack, and for good reason. This dam being obliterated would not only make for shocking TV like the WTC attacks, but would seriously mess up the West Coast power supply.
Here’s my deal with this: the Hoover Dam is 700 FEET THICK AT THE BASE. There is enough concrete in it to build a sidewalk aorund the earth. When I saw the thing this summer, I was like . . there’s no way.
About the only thing I feel that would be strong enough to wipe a hole in this thing would be- God forbid- a nuke.
Yet, it was closed during WW2 and you cannot park certain types of vehicles there. Is it really THAT easy to blow up? Can anyone provide links “concrete” evidence of the danger?
Someone I know is getting ready to drive cross-country and was planning to take US 93 over the dam… until she heard that the road has been closed due to concerns over terrorism. (Not just the dam, mind you (i.e., tours of the inside), but the road that goes over it.) This really surprised me because of (1)the OP’s observation that the thing is so damned big (no pun intended), and (2) there’s no other river crossing for 50 miles downstream and (200?) miles upstream, and (3) Hi Opal.
Wow. My first Opal reference.
My WAGs on the OP: I don’t think a truck-bomb type arrangement could do much to the dam, but it may be that knocking out a small piece of it at the top could send water over the top, and then the water itself could exert a lot of force. Also, you could probably do a hell of a lot of damage to the power generating capacity without having to take out the whole dam. Even an explosion that did zero damage would probably force a shutdown for a short while while everything was checked and inspected, and that would have a major effect on the electricity supply. From a security perspective, it’s simpler to just keep people the hell away from the thing.
In WWII the British “dambusters” destroyed a bunch of German concrete dams with large bombs dropped in the water side that fell down to the base. Water in practically speaking incompressible (which is why a torpedo can blow a hole through over a foot of steel armor on a battleship) meaning that the concrete would have to give.
I don’t know how thick these German dams were at the base, and I find it hard to believe that anything could make it though 700 feel of concrete, but the energy has to go somewhere.
I don’t think the bombs hit the base of the dams. The bombs were specially designed spherical ‘bouncing bombs’ that were droppd at very low level by a special mechanism that cause them to ‘skip’ across the water like a stone before detonating against the top of the dam, doing enough damage that the water further damaged the dams.
They don’t have to break the dam, or even crack it, to seriously disrupt operations at one, and effectively shut it down for electrical generation for a while. I’m not going to give details.
I am certainly not the most knowledgeable person in regard to WWII, however, IIRC in the documentary The Valour and the Horror: Death by Moonlight the bouncing bombs were shown to have been almost a complete failure.
(Taking a short pause to find some cites.)
Well, this site has a collection of quotes about the dambuster mission.
It seems they did manage to breach the Moehne dam.
Yeah, I know, it’s a manual for a Coleco game. :eek:
But, anyway, most of the information I could check seems about accurate, and it lists the Moehne dam as having a thickness of 112 feet at the base. It took five hits to breach the dam, and those were fairly big bombs.
So considering that the Hoover dam is almost seven times thicker than the Moehne dam, I suppose it would take an extremely accurate and powerful blast to breach it.
Engineers and WWII buffs are welcome to prove me wrong on this though.
I forgot to think about the water breaching the top theory, actually that is how most dams burst . . water gets over the top, and quickly erodes the rest of the structure, so I imagine if one of these ass clowns managed to set off a powerful explosive, it would have to be with the goal of knocking a big ass hole in the top.
Problem with that is, the TOP of the dam is extremely thick as well, dammit, my browser is too slow today or I’d cite, but the top of the thing has GOT to be at least 150 feet thick, and well above the Lake Mead waterline.
I addition, there are release channels on both sides of the dam to let water through in case there is the danger of a breach. The people down stream just had better get the hell out of the way.
I guess you could attack it and try and disrupt the power supply without blowing the dam, but that would be more like part of a coordinated attack on the US done by another country as part of an invasion, terrorists prefer highly visible targets.
The only other danger I can think of is that dams have the potential of triggering earthquakes because of the weight they press down on the earth; but I’m not sure if that would come into play since if the thing were dismantled, it would RELEASE any weight pressing down.
Nonetheless, the thing is 700 foot high, and holds back Lake Mead. Still worth protecting.
Why do I have the feeling I’m going to be hearing a clicking noise on my phone very soon?
Actually, the bombs were cylindrical. Their skipping on the water allowed them to evade the torpedo nets. When the bomb hit the dam their rotation allowed them to roll down the interior face of the dam so that they exploded at or near the bottom of the dam.
Yes, Johnny, thank you , and I too am nominating you. They need to explode at the bottom in order to make the tremendous water pressue work for the bomb. An interesting thing is that even if the lake goes back only a foot, instead of 100 miles, the psi is the same. At several hundred feet deep, the psi helping the explosing is hundreds if not thousands of psi, and like I said earlier, water is poorly compressible. The further down you get, the less possibility that surface air, which is compressible, will ruin the explosive effect underwater. It should be remembered that none of the German dams were anywhere near as big as Hoover, nor the lakes as deep.
I used to joke about blowing up Hoover Dam when I was a teenager, and one day I actually found an engineers manual which gave the formula for breeching a dam using explosives. I didn’t have all the information I needed to make an exact calculation, but I was able to figure up a rough estimate of how much TNT one would need if they wanted to be sure the dam would be destroyed. It worked out to something like 186,000 lbs of TNT. :eek: That sucker ain’t going anywhere easily.
I used to joke about blowing up Hoover Dam when I was a teenager, and one day I actually found an engineers manual which gave the formula for breeching a dam using explosives. I didn’t have all the information I needed to make an exact calculation, but I was able to figure up a rough estimate of how much TNT one would need if they wanted to be sure the dam would be destroyed. It worked out to something like 186,000 lbs of TNT. :eek: That sucker ain’t going anywhere easily.
Looking at Hoover Dam itself I can see why you’d say it’s big.If,on the other hand you consider how big,and how much pressure is generated byLAKE MEAD!!! it starts to look very small indeed.
In a nutshell,that is the unsung miracle of dam design.(How to build the smallest dam possible and hold back the greatest amount of water)
That being said,the challenge of dam destruction becomes: How to destroy some element of the dam itself so as to allow the incredible water pressure from the reservoir to finish the job?
Dams are constructed in the same pattern as arches.That is,the dam is curved when viewed from above.The reservoir side of the dam is the top part of the arch,or convex section.It is on this side that the water "pushes"the dam.Since the curve of the dam is longer than a straight line drawn from one side of the river to the other it(the dam)resists the “push”.In order to fail,it would have to curve the other way and “spill out” the water.There is incredible pressure in the reservoir to do just this,only not enough.
Now imagine a large bomb destroying,or comprimising this long side of the arch.It would no longer have the same capacity to resist.
(sidebar) Ideal dam construction:
length of longside =sum of length of all the concrete A dam that will soon burst
length of long side=sum of length of all the concrete used in it’s construction plus some empty space caused by a bomb blast
(/sidebar)
At some level,it would fail,and the dam could be pushed so that the arch went the other way.You see the length of the long side remains constant and resists compression so long as all of the concrete remains in place.Take some of it away and the the quantity of material making up the long side is reduced.If the remaining parts were to be forced together by the incredible pressure(and they would)the process of collapsing the arch would begin.
I saw the movie twice and read the book twice. Both the book and the movie were released in the 50s and did not fully release all the information.
The bomb was about 5 tons. It was rotated in the belly of the Lancaster bomber which flew at about 240 mph at 60 ft. over the water. The bomb had to skip in order to jump over the torpedo net(s) in front of the dam. When the bomb hit the dam it sank against it and exploded about 3/4 of the way down.
Given that the bouncing mechanism was designed in order to place a bomb against the dam, it can avoided if there is a road on top of the dam and you can simply roll the bomb off the top. That is if you can fit a 5 ton bomb on your pick-up.
