fort-peck-dam-montana
NATURAL THREATS

Chain Reaction Dam Burst to Split Heartland USA?

fort-peck-dam-montana

Is the Missouri River, the longest in the United States at 2,321 miles long, about to suffer a chain reaction failure beginning at the monolithic Fort Peck Dam in Montana, which itself is 21,026 feet long, 250 feet tall, and the largest earth-filled dam in the world?



The massive reservoir behind the world’s largest earth dam, Fort Peck Lake, is 134 miles long with 1,520 miles of shoreline, and reportedly holds enough water to equal the totality of the annual river run off – or one full year’s worth of the Missouri River’s flow.

According to Jody Farhat, chief of water management for the corps’ northwestern division, the six major Missouri River dams in the states of Montana (Fort Peck – the highest dam), North and South Dakota and Nebraska all will release record flows to make room for the incoming mountain runoff.

“We had a very heavy plains snowpack, and as that melted it used a fair amount of the storage that we had in our reservoirs.”

Farhat said this spring’s flood will be the most severe the region has seen since the Missouri River Mainstem Reservoir System was completed in the 1960s. (In other words, the dams have never been tested to this degree before.)

“We’re not going to get to peak releases until early July,” Farhat said. “This flood event is going to go on from now until early August.”



The safety of the Fort Peck Dam recently was called into question by a columnist for a St. Louis website. Bernard Shanks, who is writing a book on the hazards of Missouri River dams, posted a column June 7 claiming that there is a possibility of failure at the Fort Peck Dam that could lead to a domino-like collapse of all five downstream dams in the Missouri River Mainstem Reservoir System.

“It probably would wreck every bridge, highway, pipeline and power line, and split the heartland of the nation, leaving a gap 1,500-miles wide,” Shanks wrote. “Countless sewage treatment plants, toxic waste sites and even Superfund sites would be flushed downstream. The death toll and blow to our economy would be ghastly.”

Shanks based his doomsday scenario on the fact that Fort Peck Dam is North America’s largest hydraulic-fill earthen dam. Such dams are prone to “liquefaction,” meaning they can become water-logged and disintegrate if exposed to extreme pressure or seismic activity. For that reason, California replaced most of that state’s hydraulic-fill dams.



Map of the 6 major dams of the Missouri River built by the Corps of Engineers for flood control
missouri-river-basin-dams-and-elevations



For those that live along the Missouri River, it may be a good time to run the evacuation scenario through your mind once or twice…



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12 Comments

  1. There are natural disasters on all sides of us every day now. I just wish that more people got to hear about them! so many are not even aware of all that is happening, the bad floods in China that have killed so many and destroyed crops, the weather probs in Russia, again destroyed crops, look at the fire’s they had last year! and there are a lot more country’s around the world, including yours, that are having homes destroyed, land and crops all gone and yet,its just kept quiet or played down! but then, how many would just take the veiw that it wont affect them if they knew? why should it, its not in our country and yet in the end and to late, most will realize that it does affect them big time. What would they do if a super volcano blew its top? even if one of the many smaller active volcanos around the world were to go,given the right cercumstances,it could effect the whole planet! it makes me so cross that so many will not know untill its to late, they wont have even been given the chance to make their own minds up! should i stay? should i get prepared? how do i prepare? i understand that many would panic if they knew of the many inpending disasters, but even so they have a right to know! a choice as to wether they want to prepare! when TSHTF, and it will, how can ‘the powers that be’ justify their actions!their silence! how will they justify their self for the many lives that will be lost just because people never had the chance to prepare!etc. The ‘value’ that is put on a ‘life’ from high up the ‘power chain’ seem’s to be -0! You can bet that they are prepared, have a place to go, have food and water, but, one or more of the ‘situations’ will, in the end effect them, there will be no place to hide away from it. Ken, i thank you with all my heart for this site, without it and the helpful solid information from others, i would not have known in more detail what is going down, nor would i have had the chance to prepare for my family,i would have been stumped as to even start to prepare, being prepared is not just about stocking up food and water etc, it involves much more. Thank you everyone. Just noticed a very odd thing, i have a group of trees at the top of my garden and, for the 1st time in 9 years all the leaves are dying, in June?? they havent been out that long really. I live way out in the country, its not been cold of late, we have had rain on and of for a fair few weeks, not had any ‘glaring burning sun’ to speak of soooo ? how odd.
    Stay safe, stay prepared guys, Scotland out. :)

  2. This person is obviously not familiar with dam breach failure development. A common misconception with dam breach development is that the embankment just suddenly vanishes in a torrent of water. This is never the case with large earthen embankment dams- in fact, their volume of water takes many hours or even days to fully empty from the reservoir. This is due the nature of dam breach development and resulting backwater.

    When a dam breach occurs, the embankment begins to erode as the water either overtops or seeps through an opening. The gradual removal of material increases flow rates through the breach which, in turn removes increasing amounts of material accelerating the breach. The water surface elevation rises downstream as the flow rate increases. As the breach reaches full development (widest and deepest possible breach), the backwater from the downstream flow reduces the elevation drop of the water through the breach opening- thereby reducing velocity and energy available to erode the embankment. The breach typically does not go deeper than the depth of the water backing up to the reservoir as the velocity below this point is negligable. The discharge from the breach reaches a steady flow rate that continues for many hours.

    The flood wave travels quite fast, but still takes considerable time to travel downstream. For instance, assuming that Oahe Dam fails (causing the dams to fail sequentially downstream), the discharge should take around 60 hours to reach Omaha, Nebraska (from USACE dam breach study of the Missouri River mainsteam dams). Plenty of time to evacuate! :) Each of the mainstem dams were studied as part of the dam safety requirements to quantify the breach discharge and downstream inundation area. In other words, the USACE knows the extents of the flood due to a breach, and how long it would take to reach each area downstream.

    Remember though that these dams are designed to handle the Probable Maximum Flood (PMF). This ongoing event is nowhere near the PMF in either volume or peak discharge. This design event was the reason for specifying gates capable of handling 500,000 cfs. Furthermore, all of these dams have seen water surface levels near, or above the levels these levels in previous years- and have yet to fail.

    On top of that, the gates at each of these reservoirs are BARELY open right now. The gates can discharge nearer to 500,000 cfs if necessary. The USACE is playing it as safe as possible with the dams upstream, while taking into account downstream flooding. They are maintaining the discharge near to the 100-year flow rate downstream to prevent levee failures. If the volume of runoff reaching any of these dams is deemed a risk to the structure, the flood gates would be opened to avert a dam breach- this of course would cause most levees downstream to overtop and potentially fail.

    The liquifaction argument is an interesting one- but irrelevant due to toe drains that lower the water elevation through the embankment. All dams leak. The goal of an engineer is to design mitigation methods to control this seepage to prevent failure. In earthen dams these mitigation techniques are typically toes drains- basically sand pits at the downstream toe of the embankment that prevents water from seeping through the backside of the levee by allowing it to drain. Soil cannot reach a saturation point capable of liquifying if the sand drain is functioning. The soil on the downstream side of the dam is essentially dry because of these anti-seepage measures. The anti-seepage measures are not to prevent liquifaction- they are actually there to prevent fine material from being carried away by the seepage. If the velocity of seepage is kept low, there is little risk of a seepage (piping) failure because no material is carried away by the seepage.

    A failure is possible, and would be unimagineably damaging to the region. However, it is very unlikely given what is known about the snow pack and expected runoff rates. Additionally, if a breach is imminent, the regions downstream would have sufficient time to evacuate prior to the flood wave arrival. This event wouldnt be on the top of my list for worries right now given the state of the world- I think there are plenty of other events that would be much more damaging to out way of life.

    1. Yes, ‘Bernard Shanks’ has lots of critics, which I noticed while searching on the subject matter. I concur with your descriptive scenario regarding a earthen-dam breach. I happen to live not too far downstream from one here in CA and had done some research on it, in the event of a strong earthquake. Fortunately it has been recently ‘reinforced’ ;)

      “Furthermore, all of these dams have seen water surface levels near, or above the levels these levels in previous years- and have yet to fail.” Some of the reports I’ve read recently were suggesting that these dams have not seen levels this high since their completion, so it is encouraging to read your statement that this may not be the case.

    2. Really? When the Teton Dam, a newly-constructed, earth-filled dam built in a heavily-cavitated area in Montana, collapsed in May,1976 almost immediately after reaching full pool, the reservoir behind it emptied in HOURS, destroying several towns downstream, and killing 14 people. The death toll was only so low because an evacuation order was given 3 hours before the dam breached. The dam had just begun to leak, and a wet spot that appeared on the downstream face of the structure in the morning of that day, became a hole the size of a swimming pool in an hour. Then, in a couple of hours more, the dam just went. A tourist with a film camera filmed the entire astonishing event, and the footage is online. Within 6 hours, 80 million gallons of water headed out of the reservoir to towns downriver. Officials feared that a couple of old dams down river might not hold, but, thankfully, the heavily cavitated land absorbed much of the water, so the flood was much smaller by the time it reached the American Falls dam, which held. While the 300′ high Teton was an average-sized dam that was nowhere near the size of the Fort Peck, it is fallacious to say that the latter could not breach just as quickly, with even more catastrophic results.

      1. Laura, It sure makes one think!.. the Dam @ Oroville just rebuilt..had a spillway problem that almost cost the Dam and electricity generation system.. there was still a lot of damage downstream and many evacuations. I would not want to be immediately downstream from one. My reasoning is ..there is not visualization of the inside of the Dam face.. by the time leakage is to the outside there is no way to know if it is a ground water in the dam issue or a major intrusion from the body of water… The area I grew up in, had flood control dams built by works projects in the 40’s thru the 50’s..all around. most houses were 2 top of hills. and FEW WERE in the valleys… that is where the rail road runs, still today.Should there be a large earthquake…the railroad will be washed out from a possibility of 5-6 lakes in at least 2 locations.Major highway east-west will not survive it either… something to consider. Where will the water go and how fast it will empty.

      2. The Grand Teton Dam was in Idaho. It was an anomaly, and far different than Fort Peck. Due to the sheer volume of fill material in the Fort Peck Dam, it would take much longer to completely fail. I’m not saying it never will, but the probability is pretty low, and it would likely be a slow failure.

  3. Oh, here you guys are…I knew you’d be following this.
    Ken, I hope all is well with you and your wife.

    I don’t know enough about river flooding yet, so I am listening.

    The water seems to be giving some nuclear plants a little bath.

    1. @Ingot, Thanks for the mention… yes, she is finally home after more than 3 weeks at hospital – recovery process now, but all is progressing in a positive way. It’s so much better being home!

  4. Has our national IQ sunk so low that there are no scientists,engineers,or clever inventors that could come up with a better way to deal with this wet nightmare, than by bucketing water out of the lakes behind the dams,or wait with a six pack and a rubber raft for the ride of a century?

  5. I have been following this over several days and feel that this is a concern not just for this year but for the future as well. Anonymous obviously responds on general knowledge but not specific. Several factors have been underplayed.

    1. On September 22, 1938 the dam failed during construction and 8 people died. I have seen some pictures and seen the extent of the damage. The lake was already very high against the dam. Was that damage properly repaired down to the footings of the dam or just covered up? Since dam was completed in 1940 I doubt it was properly repaired.

    2. The Dam has been in operation for over 70 years. Dams do slowly degenerate over time and 70 years is a long time. 70 years of levels rising and falling, 70 years of Hot and cold weather. One picture on a historical site for Fort Peck showed a thermometer reading -60F. Basically 70 years of wear and tear. What was the expected life of an undamaged earthen dam compared to one that had partially failed during construction.

    3. According to http://www.swc.nd.gov/4dlink9/4dcgi/GetSubContentPDF/PB-2385/623NR-RIVERWATCH6-11.pdf the lake level on the 23rd June was 2251.7 ft msl. This is 1.7ft over the height of the Top of Spillway Gates (closed) of 2250 ft ms. Even if the Corps had not opened the gates it would be spilling over the top of all the gates by 1.7ft anyway. It would have been overflowing by 2.2ft a few days earlier when the peak level was recorded as 2252.2 ft msl. The only reason it wasn’t was that the gates had been opened.

    4. The longer the water remains at abnormally high levels the greater the chance of failure due to increased pressure on the dam and to increased seepage. http://www.michigan.gov/documents/deq/deq-p2ca-embankmentdaminspection_281088_7.pdf is an interesting read.

    Additional information not specifically for Fort Peck Dam but relates:

    http://www.infrastructurereportcard.org/fact-sheet/dams

    The other categories — aviation, dams, hazardous waste, schools and transit — each received a D. http://articles.cnn.com/2009-01-28/us/infrastructure.report.card_1_drinking-water-infrastructure-aging?_s=PM:US

    America’s failing Infrastructure – CBS News Video http://www.cbsnews.com/video/watch/?id=6834070n

  6. Hey “Ingot”, This is the last post I could find for you. I think there was one after the start of the Calhoun troubles? How are you and yours? Don’t stay in CO. for too long it’s hot on too many levels. ( Radiation ) hope you are well, hope you get this note. Sorry I’m underground and have no way to communicate other than Ken and Laura’s one and only system. I see you have been around for quite some time. Looking forward to hearing ( Between the lines… ) how things are going. Best of all with this economy and the changes upon us… Survive… And live life to the fullest… As to Fort Peck I’d rather be upstream given your information Ken…

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