mkl654321
mkl654321
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October 17th, 2010 at 8:37:57 AM permalink
Quote: Wizard

First, I question whether a conventional truck bomb could even take out the dam. As I recall when I did the tour years ago, they built the thing with much more concrete than required to hold back the water on the north side.

Second, even assuming they could destroy the dam, such a bomb should be able to take out not just an office building but half of Manhattan. I would think a terrorist would prefer that.

Third, the dam does not produce that much electricity. A single nuclear plant produces much more.



It would take much less explosive than you might think. The trick is to deliver the charge with enough forward velocity that it penetrates to the innards of the dam. It also would help for the weapon to be in the form of a "shaped charge", for better penetration. The target area should be the dam abutment, where the dam joins the rock wall. Those joints are filled with concrete grout, as the rock is rather porous. Take out either abutment and the dam, while remaining mostly intact, would swing outward like a giant door on a hinge--the effect would be the same as if it had totally failed. It would also probably be enough to simply destroy the spillways, especially during a rainy winter/spring.

The British developed dam-busting technology in 1943, when they successfully destroyed several dams in Germany's Ruhr district using special bombs delivered by Lancaster bombers. The weapons themselves were not that large; it was the point of impact that mattered. There is an excellent book about this called "The Dam Busters". Modern explosives could be delivered to a similar point on Hoover Dam via a number of methods, most obviously by boat.

The destruction of Hoover Dam would not in itself result in the loss of that much electricity, but the loss of Hoover plus all the downstream dams would.

I'll probably have the FBI knocking on my door later today.
The fact that a believer is happier than a skeptic is no more to the point than the fact that a drunken man is happier than a sober one. The happiness of credulity is a cheap and dangerous quality.---George Bernard Shaw
Wizard
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Wizard
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October 17th, 2010 at 9:01:55 AM permalink
Well, I don't know the topic of dam construction well enough to contradict your theory. However, your argument still doesn't pass my smell test. I've been Hoover Dam lots of times, and that thing is a massive wall of cement. I just can't picture it swaying like you described.

About the electrical output, the Palo Verde nuclear plant near Phoenix produces six times the power of Hoover dam, and that plant could have been built much bigger (source).' rel='nofollow' target='_blank'>http://www.heartland.org/publications/environment%20climate/article/25799/Mr_Obama_Tear_Down_This_Wall.html]source). The loss of electrical output would pale in comparison to the loss of water supply to Las Vegas and other cities that depend on it as their main water source.

About the FBI, I think it would be the Department of Homeland Security. Otherwise, the same thought crossed my mind too.
It's not whether you win or lose; it's whether or not you had a good bet.
JerryLogan
JerryLogan
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October 17th, 2010 at 9:47:18 AM permalink
Quote: mkl654321

It would take much less explosive than you might think. The trick is to deliver the charge with enough forward velocity that it penetrates to the innards of the dam. It also would help for the weapon to be in the form of a "shaped charge", for better penetration. The target area should be the dam abutment, where the dam joins the rock wall. Those joints are filled with concrete grout, as the rock is rather porous. Take out either abutment and the dam, while remaining mostly intact, would swing outward like a giant door on a hinge--the effect would be the same as if it had totally failed. It would also probably be enough to simply destroy the spillways, especially during a rainy winter/spring.

The British developed dam-busting technology in 1943, when they successfully destroyed several dams in Germany's Ruhr district using special bombs delivered by Lancaster bombers. The weapons themselves were not that large; it was the point of impact that mattered. There is an excellent book about this called "The Dam Busters". Modern explosives could be delivered to a similar point on Hoover Dam via a number of methods, most obviously by boat.

The destruction of Hoover Dam would not in itself result in the loss of that much electricity, but the loss of Hoover plus all the downstream dams would.

I'll probably have the FBI knocking on my door later today.



See what I mean about how this know-it-all makes it up on the go? This guy is a study in flowing illogic. It's already been written about, discussed on the news, and talked about by explosives experts how only a small yield tactical nuclear weapon would be the ONLY way to bring that dam down in the castatropic way mkl654321 purports. And there is no special "weak spot" anywhere on that dam. That's why places like Iran have built their nuclear facilities underground and layered them with yards and yards of cement.
PeteM
PeteM
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October 17th, 2010 at 10:07:24 AM permalink
I was waiting for someone to bring up the "Dambusters". The Brits used use a spinning drum of explosive that had to skip over the torpedo nets spread in front of the dams and then sink right next to the face of the dam before exploding, in order to take advantage of the tamping effect of the water to direct the force of the explosion towards the concrete. It's the tamping effect that's the key. Explosive force follows the line of least resistance, i.e. towards the open air. I suspect that if a fully fueled 747 managed to slide up the Black Canyon and impact on the face of the dam, the damage would be minimal. That's not a hollow(essentially) office building, it's many,many feet of solid concrete. I remember seeing a cross section of Hoover Dam when I visited. The front is fairly sheer, but water side of the wall is basicly a 45 degree slope. The structure is even more massive than it appears to be. Remember, it took the RAF multiple hits to take out the Ruhr dams.

As to shaped charges, a Hellfire or TOW missile blows a hole about the size of a 50 cent coin through its target, by way of example. That's the point of a SHAPED charge, it focuses all the explosive force on a very narrow area. Even if Achmed and his buddies managed to cobble to gether a VERY large shaped warhead they would still have to deliver it (not likely).

Stuff like penetrator bombs, Dibbers, bunker busters, etc. belong to the USAF and other national military entities. If we go to war with the Russians or the Chinese I'd start worrying.

Oh, and Jerry, the first time I tried to visit the dam the traffic was backed up to within a quarter mile of Boulder City, so yeah, delays do happen.
"Win with a smile, lose with grace."
mkl654321
mkl654321
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October 17th, 2010 at 10:14:10 AM permalink
Quote: Wizard

Well, I don't know the topic of dam construction well enough to contradict your theory. However, your argument still doesn't pass my smell test. I've been Hoover Dam lots of times, and that thing is a massive wall of cement. I just can't picture it swaying like you described.

About the electrical output, the Palo Verde nuclear plant near Phoenix produces six times the power of Hoover dam, and that plant could have been built much bigger (source).' rel='nofollow' target='_blank'>http://www.heartland.org/publications/environment%20climate/article/25799/Mr_Obama_Tear_Down_This_Wall.html]source). The loss of electrical output would pale in comparison to the loss of water supply to Las Vegas and other cities that depend on it as their main water source.

About the FBI, I think it would be the Department of Homeland Security. Otherwise, the same thought crossed my mind too.



The trick is, the dam itself wouldn't have to be destroyed--just one of its anchoring points. The immense hydraulic pressure behind the dam would do the rest. The dam is convex relative to the lake for that reason--to focus the hydrostatic pressure on the inner dam face, and not the abutments. But the whole setup is heavily dependent on how the dam is anchored to the canyon walls. Even a small rotational shift--caused by a manmade or natural event that moves either of the anchoring rock walls and/or the internal grouting--would result in a possibly catastrophic failure; the river would simply shoulder aside the dam. Hoover Dam looks impressive to us humans, but Lake Mead has millions of times the mass of the dam.

Teton Dam in Idaho failed due to the exact effects I just described. And that dam was built fifty years AFTER Hoover Dam.

The relative amount of electricity lost would be small, but downstream generating capacity would be lost as well, either from the failure of those dams as well, or a simple loss of storage. On a hot summer day, the Pacific Southwest often uses 100% of existing generating capacity; losing even, say, 5% of that capacity would result in rolling brownouts, at the very least. Not fun. Though I agree that the effect on California's water supply would be much more serious.
The fact that a believer is happier than a skeptic is no more to the point than the fact that a drunken man is happier than a sober one. The happiness of credulity is a cheap and dangerous quality.---George Bernard Shaw
mkl654321
mkl654321
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October 17th, 2010 at 10:23:33 AM permalink
Quote: PeteM

As to shaped charges, a Hellfire or TOW missile blows a hole about the size of a 50 cent coin through its target, by way of example. That's the point of a SHAPED charge, it focuses all the explosive force on a very narrow area. Even if Achmed and his buddies managed to cobble to gether a VERY large shaped warhead they would still have to deliver it (not likely).



See my other post. The dam itself would not have to be destroyed--just its abutments. As a practical matter, the release of all of Lake Mead's water in a matter of several hours would have just as catastrophic an effect as total failure/destruction of the dam.

I brought up the "dam buster" story to illustrate how low-tech targeted explosives can destroy a huge structure. Today's terrorists would have much more effective weaponry and delivery options than the RAF had in 1943. I agree that a simple, bash-away-at-the-face-of-the-dam approach would probably NOT work. However, that would not be the point that anyone with a knowledge of dam construction would attack.

Furthermore, a destruction of just the spillways and outlet works---a much easier task--would disable the dam's generating capacity, and during the rainy season, could provoke a crisis if the upstream dam's reserviors (Glen Canyon, etc.) were already full.
The fact that a believer is happier than a skeptic is no more to the point than the fact that a drunken man is happier than a sober one. The happiness of credulity is a cheap and dangerous quality.---George Bernard Shaw
Wizard
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October 17th, 2010 at 11:29:30 AM permalink
It sounds like PeteM knows a lot more on the topic of bombing dams than me, so I'll let him take over on that point.

About the water issue, California could get by without Colorado River water. I believe the major southern California cities gets most of their water from aquifers from northern California. Someone correct me if I'm wrong, but doesn't California use most of their Colorado River allotment on Salton Sea farming, which is not essential. Meanwhile, Vegas gets almost all its water from the Colorado River.
It's not whether you win or lose; it's whether or not you had a good bet.
pacomartin
pacomartin
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October 17th, 2010 at 11:36:44 AM permalink
A shape charge is your primary means of destroying a large submarine with a smaller delivery system
(like a small plane or a helicopter). It is difficult to deliver enough explosive to rupture a hull, so the shape
charge sends a small metal blob into a critical compartment at 22000 mph. It shreds the people and the
electronic equipment as it bounces around the compartment and then the rest of the crew is very worried
about damage containment as the water sprays through the small hole. Ideally they will surface which means
they will be easy to kill or forced to surrender.

I doubt that a shape charge could do much damage to a dam.

I also doubt that the dams were really in much danger of a terrorist attack that would kill massive numbers of people.
I think a terrorist attack on the Hoover dam would do much more psychological damage. Even if you blew up a gaurd shack
there would be experts on tv for years talking about the potential to take out the dam.

The thing that we were most afraid of was an attack on a passenger cruise ship. There are at least 20 cruise ships that
carry more than 3000 passengers, making a succesful attack as devestating as 9-11. Plus the fuel capacity blowing up
in a harbor could do damage to the pier and nearby buildings.

But, I agree that an attack on the Hoover Dam bypass bridge would have equally damaging psychological effect.
JerryLogan
JerryLogan
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October 17th, 2010 at 11:40:40 AM permalink
"It sounds like PeteM knows a lot more on the topic of bombing dams than me, so I'll let him take over on that point."

Yes, more than you, me, and everyone else combined....except, of course, for the anonymous one mkl, who can't live with himself unless he brings everyone else over to his side of the fence. But let's hope we never have to test these theories.

On the water and changing the subject a little, what's with the tremendous decline in depth of Lake Mead? Is that thing drying up or what? (I know, if mkl didn't have me on his blocked list I'd get the answer AND THEN SOME!)
pacomartin
pacomartin
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October 17th, 2010 at 11:43:21 AM permalink
Quote: JerryLogan

what's with the tremendous decline in depth of Lake Mead? Is that thing drying up or what?



There was an attention getting study done in early 2008 that said Lake Mead could be empty by 2021.

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