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Discussion Starter · #1 ·
So.. what exactly would happen to dams that form man-made lakes if the power went out via EMP or what have you? Would water just simply build up and flow over the top? Or would the flood gates open? (Forgive my ignorance as I have no idea how dams work).

I mean.. I assume there's a run-off thing on the side of most dams, and that nothing would really happen at all... but I'm curious since there are quite a few dams around here, and my BOL (even though I really plan on bugging IN unless it gets REALLY bad) is below 2 dams, and above a third.
 

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That's an interesting question and worthy of discussion. Thanks for posing it.

I'll be watching this thread.
 

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I can't speak for all areas and types to be sure, but most that I know of have spillways that can handle the appropriate amounts of water to avoid catastrophic failure. I am sure if they weren't being operated some would fail as to how many and over what time period:dunno:
Important to think about, especially if they might affect your area.
 

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It all depends if the gates automatically close or open when electricity fails.

Overflow or flood gates that aren't able to open might create a problem of excessive stress on the dams.
 

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Just walking at the edge of my grave
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I agree with cowboyhermit. Most/all have spillways that have nothing to do with any moving parts(like gates). If you have one upstream from your house the logical thing would be to go look at it and see where the water would go if it built way up.
 

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Much of the country is drier than normal. I wonder how many parts of the country would be wet enough for dams to be affected.
 

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This bears some investigation. My house is above the dam that would affect us. But with as many as we have around here it would royally screw things up. Most of the dams around here have manual flood gates. We had 7+ inches of rain above normal this January and after the main channel was lowered, all the reseviors were spilled to lower them to allow for more containment during the spring rains. I tend to think if they were not functional they lake would rise till it topped the dam. I would think long term the this would erode the concrete rather quickly, probably erode the anchor points on either side as well.
 

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Without continuous maintenance, they will eventually fail. The upkeep is critical. There is one on the Cumberland River in KY that is leaking around the edges NOW and they are working on a fix for it but without that work that dam will fail.
 

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This is an interesting question. I'm writing this from the control room of Ross Powerhouse were I began my career on Monday April 29, 1974. I've been in Hydro Operation for a while. The generating plants that were here in the 1960's and some in the early 70's would be recoverable after an EMP. Today's plants would be toast. For decades now, I've watched bad Engineering decisons wreck the reliability of generating plants. I've seen processor driven automated systems replace manual controls, the manual controls removed, then the only Engineer that understood the new system at all leave the utility to go to another state.

Generally, gates do not open automatically. And, given that emergency generators at the dams have electronic controls these days, getting power to open them would be a challenge after an EMP. It's theoretically possible to crank open the two 72" butterfly spill valves in the center of Ross Dam and the three 78" butterfly valves in the center of Diablo Dam, using hand wheels. But it would take a good crew a full day of constant cranking for some of them. For the spillgates you need power. For 16 of the 19 gates at Diablo you need to push a 5,300 lb. "mule" onto the dam, hook it up to power and use its hydraulic grapples to lift the gates. THe two 47 by 500 ft. gates at Gorge need power for a 15hp three phase motor, and even its lower outlets are gates that need power.

Most concrete masonry dams are well constructed and can withstand a certain amount of overtopping, but it won't do them any good or make recovery any easier.

As to the generating plants, if we have battery power or other stored energy (sometimes a pressure accumulator) to close the penstock valves, or opportunity to put gate locks in place, we can keep the generators from spinning up and damaging themselves as all power and pressure on the gate servos is lost. If the plant has a functioning water powered sump eductor and we turn it on, we should be able to keep the powerhouse from flooding as long as there is water in the power tunnel.

The dams themselves are built to last. Concrete is weird stuff, it never really stops curing, only slows down. At 50-80 years, good concrete is very good, indeed. At 150 years, it may actually be getting a bit brittle.

I don't see these plants as recoverable from EMP in less than... well years, if major equipment is damaged and more has to be ordered, built and transported. Working around delicate electronics to get something running could be done in weeks or months, but that requires some materials, too. And it requires a full time operating staff that no longer exists. The solid state exciters common on modern generators would not fare well in an EMP event. No excitation means that big alternator does not make much power.

With the generators down for the count, our biggest immediate challenge would be configuring the dams to not be overtopped and perhaps to function as some degree of flood control. Example: the water behind Ross is 82 feet below full right now, because the storage reservoir cycles seasonally. If we could get enough lower outlets opened, leaving space for the lakes to fill before getting close to the tops of the dams, we could still use the dams to even out some of the peaks during flood season. But as far as power, don't hold your breath.

Federal law requires us to have an "Emergency Action Plan" for the event of a dam breaking or threatening to break. It does not require us to have a plan that would work in an earthquake. We are not required to plan for an EMP event. If we have a solar event like the one in 1859, I'd say our society is back to about the year 1900.

I am my utility's most senior Hydroelectric Operator. I collect kerosene lamps. Think about it.:rolleyes:

In most of our critical infrastructure, not just the electrical industry, we see the skilled blue collar people who keep it working gettting older and older and finally retiring. Very few youngsters are coming up through the ranks. Recently, it gave me pleasure to see two bright young Apprentices "top out" and become Journeyman Electrician Constructors. But this was in a time and place where it should have been a dozen, not two. Physical assets are not being adequately maintained. "Managment" is more and more the political type who will postpone maintenance and upgrades to cut costs. The term "crumbling infrastructure" is accurate. But perhaps equally important is the loss of institutional knowledge and experience as the most experienced people are leaving, or in some cases being driven out, without adequately trained and experienced replacements coming aboard.

We live in a nation of MBA's who cannot wire a house, fall a tree, or even change a tire or drive a nail. Brace yourselves.
 

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HamiltonFelix said:
This is an interesting question. I'm writing this from the control room of Ross Powerhouse were I began my career on Monday April 29, 1974. I've been in Hydro Operation for a while. The generating plants that were here in the 1960's and some in the early 70's would be recoverable after an EMP. Today's plants would be toast. For decades now, I've watched bad Engineering decisons wreck the reliability of generating plants. I've seen processor driven automated systems replace manual controls, the manual controls removed, then the only Engineer that understood the new system at all leave the utility to go to another state.

Generally, gates do not open automatically. And, given that emergency generators at the dams have electronic controls these days, getting power to open them would be a challenge after an EMP. It's theoretically possible to crank open the two 72" butterfly spill valves in the center of Ross Dam and the three 78" butterfly valves in the center of Diablo Dam, using hand wheels. But it would take a good crew a full day of constant cranking for some of them. For the spillgates you need power. For 16 of the 19 gates at Diablo you need to push a 5,300 lb. "mule" onto the dam, hook it up to power and use its hydraulic grapples to lift the gates. THe two 47 by 500 ft. gates at Gorge need power for a 15hp three phase motor, and even its lower outlets are gates that need power.

Most concrete masonry dams are well constructed and can withstand a certain amount of overtopping, but it won't do them any good or make recovery any easier.

As to the generating plants, if we have battery power or other stored energy (sometimes a pressure accumulator) to close the penstock valves, or opportunity to put gate locks in place, we can keep the generators from spinning up and damaging themselves as all power and pressure on the gate servos is lost. If the plant has a functioning water powered sump eductor and we turn it on, we should be able to keep the powerhouse from flooding as long as there is water in the power tunnel.

The dams themselves are built to last. Concrete is weird stuff, it never really stops curing, only slows down. At 50-80 years, good concrete is very good, indeed. At 150 years, it may actually be getting a bit brittle.

I don't see these plants as recoverable from EMP in less than... well years, if major equipment is damaged and more has to be ordered, built and transported. Working around delicate electronics to get something running could be done in weeks or months, but that requires some materials, too. And it requires a full time operating staff that no longer exists. The solid state exciters common on modern generators would not fare well in an EMP event. No excitation means that big alternator does not make much power.

With the generators down for the count, our biggest immediate challenge would be configuring the dams to not be overtopped and perhaps to function as some degree of flood control. Example: the water behind Ross is 82 feet below full right now, because the storage reservoir cycles seasonally. If we could get enough lower outlets opened, leaving space for the lakes to fill before getting close to the tops of the dams, we could still use the dams to even out some of the peaks during flood season. But as far as power, don't hold your breath.

Federal law requires us to have an "Emergency Action Plan" for the event of a dam breaking or threatening to break. It does not require us to have a plan that would work in an earthquake. We are not required to plan for an EMP event. If we have a solar event like the one in 1859, I'd say our society is back to about the year 1900.

I am my utility's most senior Hydroelectric Operator. I collect kerosene lamps. Think about it.:rolleyes:

In most of our critical infrastructure, not just the electrical industry, we see the skilled blue collar people who keep it working gettting older and older and finally retiring. Very few youngsters are coming up through the ranks. Recently, it gave me pleasure to see two bright young Apprentices "top out" and become Journeyman Electrician Constructors. But this was in a time and place where it should have been a dozen, not two. Physical assets are not being adequately maintained. "Managment" is more and more the political type who will postpone maintenance and upgrades to cut costs. The term "crumbling infrastructure" is accurate. But perhaps equally important is the loss of institutional knowledge and experience as the most experienced people are leaving, or in some cases being driven out, without adequately trained and experienced replacements coming aboard.

We live in a nation of MBA's who cannot wire a house, fall a tree, or even change a tire or drive a nail. Brace yourselves.
I know exactly what you mean. Its hard to get electrician apprentices to stay the course. Ive been training these kids in residential and commercial for a few years now. Everytime they get to a certain level of training and responsibility, the boss doubles the load on them but wont pay them any extra. Hes making a stinkin killing and running off potentially great future tradesmen all in the name of short term profits. I tried to explain how this was to his detriment, but the discussion quickly devolved to him telling me to hit the gate if i didnt like it. Smh...
 

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Okay next question: would the turbines free spin so to speak, letting water continue to flow through them. The power not used could be shunt to ground or not made at all.
 

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Discussion Starter · #12 ·
This is an interesting question. I'm writing this from the control room of Ross Powerhouse were I began my career on Monday April 29, 1974. I've been in Hydro Operation for a while. The generating plants that were here in the 1960's and some in the early 70's would be recoverable after an EMP. Today's plants would be toast. For decades now, I've watched bad Engineering decisons wreck the reliability of generating plants. ***SNIP***

We live in a nation of MBA's who cannot wire a house, fall a tree, or even change a tire or drive a nail. Brace yourselves.
Thanks for your input! It is much appreciated! :beercheer:
 

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OOPS. Sorry for the typo. As you probably realized, the vertical lift gates at Gorge Dam are 47 ft. wide and 50 ft. high, not 500. :eek:

I often wonder how the electrical aspect of our sociey would have evolved if Nikola Tesla, Benjamin Garver Lamme and George Westinghouse had not given us the world we live in. (I know you're familiar with the intuitive genious Tesla and the business giant Westinghouse, but Lamme was the guy in between, the Chief Engineer who took Tesla's flashes of genius and turned them into working equipment.) If we hadn't gotten effective transformation and long distance transmission of power when we did, we might have evolved a more decentralized system, where we are not dependent on huge generating plants many miles away. It might not have been as cost effective as "the Grid," but it would have been more resilient and less vulnerable on a large scale.

I hear ya. Everywhere you look, you can find tales of employees being run out after they get some experience and a few raises. "Hey, if he really knows what he's doing but makes a good wage, we can get rid of him and pay two new guys what we pay him - and we can get him to train the new guys on his way out...." Employers all over are taking advantage of the bad economy, but often doing it in a way that will cut their own throats in time.

Back on the original topic: There are dams that have spillways designed to simply start flowing at a certain water level. But lots of dams are NOT designed that way. More typical is something like our dams, where you have spillgates and often smaller outlets located lower than the gates, but they need to be operated. And that dam is not designed to handle overtopping without damage.

In recent years, much as been done in the way of recalculating Possible Maximum Floods and finding methods to "harden" dams in the event of overtopping. But they weren't really designed for the water to just flow over them. Oh sure, you can design for "surcharge." The full elevation of Gorge Dam is 875 ft. above sea level; that's the top of the gates. But those gates are designed for 5 feet of surcharge. That is, you can let the lake "pile up" as high as 880 ft (but not more, because the roadway on the dam is at 880). Water flows over the top of the gates, but it's not a huge flow compared to opening the gates because it's not under much pressure.

BTW, if you're planning a micro hydro, it maybe be useful to you to know that with fresh water you get 0.434 psi for every foot of head. Take water from 100 feet above your site, and you have 43.4 psi at your site - until you start it flowing and have to deal with pressure losses due to friction in your supply line.

I really don't want to think about the headaches we'll face at our dams and powerhouses if we get hit with a violent EMP event. The solar event of 1859 had telegraphers thinking their equipment was possessed, and where they had instruments with rolls of paper and a pen to record dots and dashes it actually set the paper on fire. I can't even imagine the damage such an event would do to today's society.
 

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I too live in NC and affected by the dams....as you must know if you are from around here they don't control the dams real well just when we have too much rain in the Mts....so be prepared to RUN, or if you are on higher ground, still be prepared, they can hold alot of water and the water will rise quickly.
 

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What I find here in the Northwest is, the Corps of Engineers "takes over" in flood conditions, telling us how to operate. Much like the FEMA "day late & dollar short" policy, they generally don't act when they should, then overreact yoo late, and usually manage to make things worse. Although a vast pool of institutional knowledge has been driven out in recent years, we know more about the behavior of our rivers than theCorps, but we are powerless.

My suggestions are don't build in a flood plain and have alternatives to distributed electricity.
 

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" More typical is something like our dams, where you have spillgates and often smaller outlets located lower than the gates, but they need to be operated. "

I would think they would just always leave the openings near the top open. Just in case.
 

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You would think. But they aren't designed that way. "Full" will be the top of the gates. The reservoir is seldom run more than a few feet lower than that, usually not down near the gate sills - a typical taintor gate might be 20 feet tall (they can be much larger). The exception is a seasonal storage reservoir where the lake might drop many feet in winter, or maybe a pumped storage reservoir where it cycles daily but high flow flooding isn't an issue. The road on top of the dam is just a few feet above that "full" level.

You'd think an open spillway could be built with its sill at "full" elevation, "just in case." But not really. The flows in a Possible Maximum Flood would be very large, the dam's gates are designed with that as the maximum they can pass with all gates open. But that is with water level well above the sills of the spillways. A simple open spillway at "full" level would have to be too large and would still "pile up" water well above normal full level, and you can't have that. Instead, along much of the top of the dam you have a bunch of gates that can be opened when you see the flood building and realize you won't have room in your reservoir to hold it.
 

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Thanks HamiltonFelix! Why does something so simple have to be so complicated? It is too much for this simple farm boy.
 

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What a great thread. Thx for all the info. Everytime I think I know what to look for in a bol someone here gives another thing to consider.
 

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