Rapidan Dam "Imminent Failure" 24 June 2024 MN
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- Опубликовано: 23 июн 2024
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I'll remove it and am sorry. It was a reference to Bevis and Buthead
Geologist here - If you look at the area between the dam and the new spillway, you will see some very resistant rocks sticking out of the water. The apparent layering appearance of the rock is consistent with the typical bedrock in that area which is a limestone/dolomite. This type of rock is also just visible on the other bank of the river. It is very resistant to erosion. To the outside of the new spillway, you see a soil profile what is the alluvium in the ancestral river valley. In the new spillway, there are several distinct benches over which the water flows, also consistent with the likely local limestone/dolomite bedrock. The dam was (if correctly designed) keyed into this bedrock and uses it for its underlying support. The alluvial soils eroded easily, but the bedrock appears to be holding, based on review of this and other footage from much earlier today. What this boils down to is that this dam may not (hopefully will not) fail catastrophically because of erosion from the water and loss of foundational support.
It’s not an emergency spillway. 2 feet would put the homes under water. They are already underwater
@@BearBear1959 Yeah, generally you never find a substation built in the middle of a spillway.
@@BearBear1959it is now.
Wanna bet?
The bedrock there isn’t dolomite. The engineering feasibility report on repairs to the dam lists it as Jordan sandstone.
I am always impressed at how long those early 1900s constructions have lasted. Thanks for an excellent report, Mr. Brown.
They are older
Cause the engineers had passion and weren't nearly as limited on funds or labor cost. Money went a lot further back then.
Because what was not overbuilt failed a long time ago.
Actually, many of them did fail. The St. Francis Dam collapse in the 1920's was (pardon the pun) a watershed moment for dam construction. This is why the Hoover Dam and the Tennessee Valley Authority dams of the 1930's were built so strong.
There is so much sediment behind this damn.
The timber gates were removed and replaced with concrete bulkheads in 2017, sealing those spillway bays.
The space on the side is not the emergency spillway. It’s just the ground that the dam is built into.
The bedrock is a very erosion-prone type of sandstone.
The dam has nearly failed in the past. In 2002, the dam needed emergency repairs when it was discovered that the apron at the bottom of the dam had eroded and the dam had been undermined. The apron has needed repairs several times since then, and Blue Earth County has been in the process of determining whether to repair or remove the dam since 2021.
The powerhouse was already a total loss after flooding from an ice dam in 2020.
Former power dam worker here, ah ok on the powerhouse being destroyed before. I saw the water coming out in the top of it and I thought, oh boy that looks like a real mess in there.
Thank you for the information. I hope everyone in the downstream communities were able to evacuate.
Thank you for the additional information.
@@hermancm Looking at the 10:38 image, it appears that the water coming out from the top of the powerhouse may just be roof drains. If the interior were filled to that height, I would expect the windows lower down to have blown out (if not the entire wall).
@@hermancmYeah, it was really tragic what happened. They had a flood in 2019 where debris damaged the tainter gates. So they kept them open to avoid the risk of them failing in 2020. But with the gates open all the way, the reservoir got really cold but never iced over, so they got a giant ice dam downstream from the plant. That ice dam rose the tailwater up by 20-30 feet. The turbines, the switchgear, and the control panels were all underwater. And they weren’t even that old. The whole plant had been redone in the 1980s.
It didn’t look like an emergency spillway.
To what I’ve seen so far.
But, like you said, it is now.
Looks like the wooden gates were the spillway. The new one seems to flow pretty well however.
More like it becomes and emergency when it is a spillway
I live near this area in Southern MN and fish near the dam on a regular basis. There is no emergency spillway, this is just mother nature taking it's course.
It is the emergency spillway. My brother's firm, Barr Engineering, has been responsible for making various feasibility studies for the last 20 years. My brother spoke with the lead engineer yesterday and said the left side was the spillway location. It may not have looked like a spillway, but this was the design.
@@mikeSL246 Makes no sense to put the substation and power lines in the spillway though.
Juan, your extensive knowledge of non-aviation topics is admirable! As a civil engineer, your explanation is spot on!
Juan understands flow theory be it air or water. 😀
Definitely JB deserves either the Pulitzer or the Murrow, or both.
We have had some huge amounts of rainfall here in MN for about the last 6-8 weeks!
I can appreciate your coverage-- --probably the last state you ever expected to be covering a dam issue!
Thanks Juan!
Hello from Australia. I love the rain but also know what it's like when we get too much of a good thing!
Thank you. I was wondering what caused the debris to collect so quickly.
@@occamsrazorblades The river banks in this area are loose soils with lots of deciduous trees. The river banks erode very easily bringing trees into the waterway. Lots of trees build up against bridges and dams in the area.
Considering the 35W bridge in 2007 I don't think Minnesota would be the last state you'd expect to see an infrastructure issue.
Juan covered the dams in Michigan that gave way. Midland area
That was not an emergency spillway, there was a power sub station there before it was washed away.
It look like one now....
It was an emergency spillway.
@@WilliamWagner-hq9ut no
@@WilliamWagner-hq9ut And they put the sub station there!?
@@WilliamWagner-hq9ut not a spill way I live here
Good job Juan. At one point in my career as an engineer, I worked for the State Dam Safety Program here in N.C. Dams that are this high and which impound this much water can be considered high hazard depending upon the threat to life and property downstream. High hazard dams typically are required to have a breach analysis to model the flooding impacts downstream. As a dam regulated by FERC, I would suspect that is the case here. And as someone already commented, a breach analysis would result in a fairly accurate determination of the river stage and flood wave elevations downstream.
Loved your work on the Oraville dam failure. I used to watch your channel every day from the initial failure through the rebuild. I worked for Keiwit as a carpenter on the big dig in Boston. They were a great contractor to work for, everything first class.
Juan, I live a couple miles from the dam. The area where the water broke through was not intended as an emergency spillway as you had been questioning in your video.
Been following this all morning. Been following you since Oroville and learned a lot about aviation. Thank you. Mike in SF.
Thank you for the detailed, but understandable explanation. I was in Mankato pitching sandbags to build an emergency dike during the 1965 flood. I pray this situation does not get as bad as that.
I'm downstream right now near Blakely, the river just went over the 1965 high-water mark!😮
@1:30 current measured discharge at the USGS station immediately downstream of the dam is 34300 CFS
average is about 1000 cfs, so yeah 34 times average is bad. most extreme i found over here in switzerland: Sense 300 CFS average, max flood in 1990: 17260 CFS (about 57 average).
The highest flow rate recorded at the Rapidan Dam was back in 1965, at 43000 CFS.
@@vne5195 Which, for perspective, is less than one tenth of the NORMAL June flow of the Columbia River at Richland (pre-dam), or one-eighteenth of the record flows (1894 and 1948).
I live in Mankato. It's been raining on & off here since 4 PM. A lot of roads & bridges are closed in lower areas of Mankato & North Mankato across the river. Getting around is a nightmare, but so far the towns seem fine. Just praying it stays that way.
169 to St Peter has stayed open?
@@joeskis Dont think it is. I commented 2 days ago.
One local report says power generation ceased several years ago due to damage from high water events.
Stopped in 1965.
@@solskengroupllp2758 then it should be removed. Otherwise it is just a hazard as it is now.
The Rapidan Dam is a concrete gravity dam located on the Blue Earth River in Rapidan Township, near Rapidan, Minnesota in the United States. The dam was constructed for hydroelectric power generation from 1908 to 1966. The dam and reservoir are owned by Blue Earth County, and the power plant and dam was operated by Eagle Creek Renewable Energy under an agreement with the county. Power was no longer generated at the dam due to damage from flooding in 2019 and 202
0.
I was waiting for the “I’m your dam tour guide” line, didn’t get it.
👍
Nobody gets the reference anymore
It's not a dam tour! It's a dam emergency!
DAM
Ah yes, I used that line for years. Boulder Dam. Not Hoover. Tanner Gray Line, and LTR bus drivers were a bunch of comedians. I had the only “casino” bus in Nevada where you could use the restroom, press the red button and get a royal flush.
Apparently power was not being generated since damage in 2020. But there was a substation supplying power to 600 that was lost in this event. There was a study done recently to see if the dam might be removed due to cost to properly repair it. Looks like Mother Nature made the call. Thanks Juan.
@blancolirio, Juan, I live downstream of this dam and have driven over it a few times. The home that is close to being lost is the home of the owners of the Dam Store/Cafe. I have followed you since the Oroville Dam incident when I still lived in San Diego. This situation is heartbreaking and very scary as the Minnesota River here in Mankato is currently at 28.9 feet and hasnt crested yet. The failure of the Rapidan dam would cause the Minnesota river to rise 2 feet endangering many homes, busineses and at least one senior citizen home downstream...
Wow, sounds more serious than originally reported. Prayers to everyone in the area for no further issues.
The USGS gauge just below the dam is flowing at ~33k cu ft / sec. Look for "Blue Earth River Near Rapidan, MN - 05320000". Historically it usually runs below 10k cu ft / sec. The highest recorded in the last 81 years was 18.1k in 2018. I haven't seen any estimate of how long it will take for the impounded area to drain at the current flow rate.
@OfficialBlancolirioxc - I'll be your huckleberry!!! I value your consel as well and would like to talk off this media too, but first I would like to talk to you about your car's extended warranty.
The peak flow rate at the Rapidan Dam was 45000 CFS, recorded in 1965. The dam was extensively damaged and required a decade to repair.
Finished in 19010? That's a long time.
Yup...in the future
Ah the 20th millennia. Smack dab in the middle of the Dark Age of Technology!
Takes a long time to build a wall, you know.
@@prussiaaero1802 if you use hand tools, and were in the stone-age, yea. but today, at most, days, not months
19 O 10, that was funny
Been following you since Oroville Dam Incident, this one is only 2.5 hours from where I live. The world seems to get smaller and smaller everyday. Never expected a blancolirio video about something happening in my neck of the woods, but here we are! Great coverage as always! Thanks Juan!
I don't believe there was an emergency spillway; instead there was originally a reservoir upstream, but over a century it has filled with silt so now it has very little capacity.
That was not a spillway. In fact the substation was just to the left side. That has all washed downstream. Including several buildings. As of later this afternoon it has washed out some of the foundation from under the house that's off to the west.
JUAN, that was DAM good coverage of the dam situation!
Got any damn bait for this dam tour 😂
@@hittinitsidways I've been waiting for this reference, lol.
Some dam good coverage of the Ramidan Dam situation!
kind of in disbelief to see you cover this story from just a few miles down the road from me - been watching your channel for GA aviation stories for a LONG time now and to see you cover this is pretty surreal.
Thank you for a thorough explanation of the whole dam situation.
You d&m right.
It appears that a major contributing cause of lateral bypass of the dam is the dense accumulation of flood-generated driftwood jammed against the concrete sill atop the dam. It's blocking much of the flow that should ideally overtop the spillway gates unimpeded, & help prevent the water level from rising high enough to circumvent the structure. If that concrete top plate were not there, or of sufficient height, the rising water would simply lift the driftwood until it just washed over the dam, & allow maximum overflow to occur. Not accounting for the inflow of driftwood into the system is one of those engineering oversights that can lead to a situation of this type, & when it happens, it's already too late.
I was there on Sunday. Went to the Dam Store. The store is OK, but there is a crazy amount of water going over the dam.
How is it in Mankato?
Was it a couple feet over the dam ?
Store got washed away a few hours ago.
No the store is still there repeat the store has not been washed away The house closer to the dam not very far from where the transformers were last I seen was probably going to be washed away but it has to go a long ways to get to the damn store@@gtaxmods
Hahaha
Satellite photos suggest that the impoundment lake is heavily silted near the dam and this may be why the dam has flooded quite easily and why dam failure may not pose much risk; there's actually very little water behind the dam except for what's built up behind the plugged gates.
Exactly. It is holding back very little water. Mostly a mud flat.
Would you folk like to be standing downstream if the dam fails? That should test your 'its not a danger' theories... @@allisshop8092
@@allisshop8092 Ick, it means that if the dam fails, 2 feet of very muddy water is going to flow downstream. Had a work colleague, her home was flooded after a heavy rain. When she got home and saw all the mud she had to clean out she cried.
Was waiting for this one!! I’m in MN!!
There have been so many strong rain storms that trees are falling all over into creeks, trails, ponds, rivers and streams. Last summer the weather was so dry that the trees were greatly impacted and are in poor shape.
And just a few weeks ago almost the whole state of MN was in drought conditions.
I live 20 miles from there and had no clue that it even existed. As far as rivers go, it's not much to speak of. Fifteen or so miles south from there is Blue Earth, MN, home of the "Green Giant" statue.
When I was a little boy back in the 70's, I was scared of the commercial with the Green Giant, lol.... I was like 5 or 6 when I saw that commercial for the first time. My brothers and sisters told me that he was the same giant in Jack and the Beanstalk book.
As a native Minnesotan, I am familiar with springtime floods (I was there in ‘65), but these floods in summer are a whole new phenomenon…
SOAR. CLOUD SEEDING. SERVICE IS doing this .look it up.
They're actually pretty regular. It's the incessant rain that saturated the ground, so there's nowhere else for the water flow except the streams and rivers. It's ironic, because there was no spring flooding this year, due to little snow and the ground hardly freezing all winter. The Mississippi is also in minor flood stage nearby, with major flood stage predicted, but nowhere near the spring flooding of last year. I was just in Winona this afternoon, and you can tell the river's high, but very little's really affected.
I just saw a drone video from less than an hour ago. The white house near the "emergency spillway" has all but fallen into the river. The power house is being totally flooded.
House is still there as of Tuesday morning. Erosion seems to have halted or slowed greatly; my guess is that with a bit of foundation restoration, the house will be fine.
We Minnesotans apologize profusely for having a river that flows to the north. We know how disconcerting this is, and we are trying to reverse the direction of the river. But these things take time.
I was puzzled by that. I know the Nile flows south to north, but Juan tells us that TWO rivers in Minnesota do so. Good luck on the flow reversal project from Liz and Ginger (pic left) in Australia.
The Red River of the North flows north. It is the border between North Dakota and N W Minnesota. It flows N to Winnipeg Manitoba and ends in the Hudson bay. The area sees a lot of spring flooding because the area is so flat. Fargo ND is currently building a major diversion channel around the city, simulator to what Winnipeg did decades ago.
Call in Post 10 to unclog that.
Yes! Maybe he can get some whirlpools spinning.
If it fails the water level will only rise by two feet, but what about the initial wave?
And the debris and mud which will wash down in the initial flash flood. Can't be something anyone can be too complacent about.
@@jonathanrichards593 Yeah, a sudden failure causing a big wave pushing all that debris downstream could certainly cause some unexpected consequences, especially if a bunch of big trees get jammed under a bridge and form a new impromptu 'dam' that causes localized flooding. Please everyone downstream stay safe and pay attention as conditions develop.
If and when the main dam fails - the concrete isn't just going to shatter or magically dissolve. The whole structure is going to separate from its foundational pilings and gradually overturn - head over footings and would essentially act as a giant drum-gate. It's just not analogous to the failure of an earthen dam - which tend to fail suddenly and catastrophically. The worst of the rapid, unexpected surge has already been experienced. Additionally, anyone that has ever been to the Twin Cities know how DEEP the rivers have eroded through that terrain. The bluffs are very commonly 100 ft + higher than the river. During spring snow-melt - these rivers ROUTINELY seen high water-levels and higher discharge-rates than what is even being experienced currently. It's still not an ideal situation and disconcerting that they didn't realize and communicate the existence of a major problem until WELL AFTER the problem existed - but there's going to be no devestating wall of water as if the Chickamauga Dam were to fail (which it someday will) and sent a 35 foot tall wall of water into downtown Chattanooga at 65 MPH
“Nineteen oh ten”.I love it.
Damn it Jim, I mean Juan, she's taking all she's got.
😂🤣
“Into the tele-transporter everyone! We’ve got to get outta this place!“
“Aye! Aye! Captain!” 🛸
Captain, the power 🔋 is offline and we won't make it to Wal-Mart for regeneration, or even the NEXT-GENERATION 😮...
DAM, DAM.
"beam me up Scotty, this planet sucks". 😊
The "Trouble with Tribbles" was more fun than this mess🖖🖖😮🗣
I live in Butte county - 2 miles south of dam @ 900' elev.
Saw this news and immediately thought Lake Oroville 2017 spillway failure.
Lake O dam is 10x taller.
114 year old dam? Hollow construction? Wooden structures?
Infrastructure failure.
It looks like the dam itself is holding up well, but is blocked by debris and so the water found another path.
@@Sally-up8xe we can only hope. Lake Oroville Dam held up, but the whole spillway, eroded. It was scarier than the fires.... I still get the heebies thinking about that week.
So much stress for those people.
Thank you. I came across your page during the Oroville situation. I cannot believe the two feet water level. I believe it will be much more.
I live near this area in Southern MN and fish near the dam on a regular basis. There is no emergency spillway, this is just mother nature taking it's course.
An emergency spillway would not travel through a transformer substation, however. The emergency spillway, if there is one is quite small and appears to travel between the powerhouse and the transformer substation. Needless to say, the flood water has overshot its designed overflow path.
Went to flight school down in Mankato some years ago. Visited the Dam and pie store quite often. Interesting and crazy to see this on your channel :)
Juan is back into the subject that launched his channel, remember Oroville?
That's how I found him, actually.
Pepperidge Farms remembers
The Oroville spillway failure certainly rapidly increased his viewership but he had a nice channel before with his motorcycle and aircraft content. You're right that his coverage of Oroville problem without the pearl clutching was the best!
Thanks JuanB. for the Sane report and Amazing Pictures. hope Grand-Daddy-Dam will stand strong.
My family is from Mankato...they are all eagerly watching the developments. Thank you for the thorough explanation.
Thank the Lord we have Juan to keep us up to date with all these goings on in the US of A.
@OfficialBlancoliriodrf - I'll be your huckleberry! I value your consel as well and would like to talk off this media too, but first I would like to talk to you about your car's extended warranty.
Water flow is currently 34,000 cu ft/sec. Normal flow is 600-800 cu ft/sec. I believe the white house pictured on the west side of the dam is hanging over the abyss today.
The peak flow rate at the Rapidan Dam was 45000 cu ft / sec, recorded in 1965. The dam was extensively damaged and required a decade to repair.
Thanks for the up date on my part of the world. All your videos are interesting, well done, and educational. This one brings back a lot of good memories. I live in Sioux Falls SD and drove this route to St Paul for my BA in the 1960's and in the 1870's commuted 3 days a week to U of MN at Mankato again on the old two lane road past this dam. You also go through near by LeSeur Mn home of the Jolley Green Giant vegetable growing and canning. They built I90 and I35 about 1980. It is longer but no little town every 10-15 miles and tractors and school buses so it takes less time and is an easier drive, I still go up through Pipestone and the river valley to Mankato were it becomes 4 lanes every once in a while because it is a beautiful drive. I do no know how much rainfall they had. i am 170 miles SW but we had a large area with 10 inches or more or rain in three days. Then it rains an inch or 2 every other day. Dozens of small roads and parts of the interstate flooded as well. One of the nicer things said about SD is "If you do not like the weather, wait a little while and it will change"
I live in Mankato, downstream of the dam. So far, we have seen a few (annoying) road closures near the river, but no major issues otherwise. The Minnesota River is as high as I have ever seen it, but to my amazement, they thought of this very issue twenty years ago. They built a very high concrete wall to contain a flood event of just this magnitude. They predict a peak flood level to be well within these tolerances tomorrow.
Always bad when your city makes the Blancolirio channel. Thanks Juan, for the accurate info.
Thank you for doing the video on this damn I can tell you that the left part of the damn that the water is currently going down has already reached bedrock so that area is all a limestone Shelf. As you see the stacked up rocks in the middle there that is actually the original Limestone wall and that continues all the way down to the base of the dam. The reason the water did not go around the right side of the dam is because that Limestone Bluff is higher on that side so basically that is built into the hillside carved in to the hillside where the Limestone has never been touched and on the left side where you see the stack of rocks that is where the Transformer station was that was on the damn there was also a substation that was in the water area that has washed away. I spent most of the afternoon out there filming today and not much more of the bank has given away towards the house due to the fact the water that is coming around the damn is already only washed down to the Limestone ledge so it just took the silt away on top everything else underneath is Rock I do not believe the house is going to fall in anytime soon because the level of limestone is already been reached and the water is not any higher into the hillside where the loam exists. So wear them limestone rocks are stacked the damn is actually being held in place by that original limestone so even though the water is going outside that area the damn is not going to fall apart unless it cracks in the middle and the amount of water that is coming still through the damn and going around the damn is actually saving the dam. So those stacked up rocks like I said that is original stone that is actually making a gusset holding that hole end of the dam in place. I believe it was 2010 or maybe it was a year 2000 were they repaired the whole damn and they pumped in truckloads and truckloads and truckloads into areas lower than the damn to help support it as for the amount of water behind the damn there is probably only about a depth of 12 ft because it is full of sediment they were going to dredge this out a few years ago when the water was barely trickling through there but it would have been millions and millions of dollars so they were on the table of either just taking the damn out or spending the money to dig the material out.
I'd feel a lot more confident if an Army Corps of Engineers rep said even if the dam failed completely, it would only rise 2 feet than someone from a local sheriffs department.
An engineer almost certainly did come up with that estimate. Dams this size require an Inundation Study (where you try to estimate impacts from a dam failure under various conditions) and an Emergency Action Plan.
That dam is owned by Blue Earth County, so the Army Corps of Engineers isn't involved directly, though of course they have jurisdiction over navigable waterways.
In the update briefing today, a county engineer said the Army Corps of Engineers was onsite today and yesterday, along with other federal and state agencies.
My partner was working in Mankato for about half of last year; downtown isn't at too much risk due to high floodwalls and berms, but there are some lower areas along the highways north of town that might flood out. That said, there are also about 60 square miles of wetlands there that could help moderate the downstream impact.
Not sure about that part of SW Minnesota but here in NW Iowa, and SE South Dakota 18" (half a meter) of rain fell last week in a 3 day span causing massive flooding here in the tri-state (NW IA, SE SD, NE NE) area.
Well done Yuan.
Nicely explained without actually being there yourself to look at the overall situation.
The Assesment Team of Engineers gathered there would have the clearest knowledge of the Dam itself & the ongoing Projections as to what needs to happen.
Respectfully ...
That home owner is probably sweating bullets right now.
about to be underwater on their mortgage
Other videos show the ground under that house has eroded and it will fall in soon. The homeowners have evacuated.
It's already toast (in live time) - missing part of it's basement, waiting to fall the rest of the way in... 😢
@@SennenTafkaenice
Dark but nice 🤣
I believe that house is owned by the people who own the little cafe that’s known for its homemade pies. Wonderful people. 💕. I’ve ate there a couple times, visiting from SoCal.
I was an intern with the Blue Earch County Sherrif in 1980, I remember this was an old structure back then. I know it barley made electricty at the time and there was talk of removing it back then. I guess it never happened. Loved the area and Manakato State Universtiy as it was called back then. Go Mavricks!
I guess my question is, why isn't there a debris fence or structure located behind the spillways? Many dams have that protecting their spillways for this exact reason. I understand that the dam is over 100 years old, but this isn't the first time flood debris has made its way down a river and plugged up a dams' spillways.
Thanks for update on the dam current situation.
If the two timber gates were in working order and the debris properly removed by regular maintenance there wouldn't be a problem. Good old fashioned human negligence is the cause of the overflow. A dam works like a toilet, when both get a log jam, both will overflow without maintenance.
The debris accumulated in the last several days.
The debris come from upstream.
Hey Juan, thanks for covering us way out here in the Upper Midwest! I'm a California boy who relocated to Wisconsin and watch your channel religiously. Keep up the great work!
I live in St Paul, and when i heard about this, i was wondering if you were going to be doing a video on this. I am so happy to see you do so. Thanks for the hit.
Poor people’s house is hanging over the edge and they’ve lost about two acres
And all those trees (that looked quite nice in the 'before' pictures). Can easily truck in fill and topsoil, but big trees are not so easy.
Great reporting Juan. I hadn't heard of this until i got your utube notification.
Can't speak to the specifics here, but it kinda SEEMS there was not an emergency spillway. With a dam this old, maybe not. And dealing with a sudden surge of deadwood during a flood can be highly problematic if not impossible.
That's why we do Inundation Studies to see what dam failure impacts would roughly be under various conditions, but it's not an exact science. We also prepare Emergency Action Plans to have a procedural checklist for different situations (you might be familiar with such things... 😉)
I wondered if we were going to get footage of you flying over the situation! Love your channel.
Wild to see a local attraction being talked about on one of my favorite aviation youtubers.
A few points:
1. The dam has no slipway, until now.
2. What failed was the debris catchers on the road bridge and the logs and such jammed the gateways. The highest flow was 40k and the current flow is 34.5k which is at the design limit. But with the debris the water couldn't flow correctly. My guess is because of all the water we had last week (6" on 21st alone) and being the weekend no one saw the debris till too late.
3. In 2020 there were public comments on what to do with the dam: remove it at $86 mil or repair at $16 mil. There was no decision acted on.
Oh my, Nor Cal understands how it goes with emergency spillways. 😱
THat poor house is toast. Thanks Juan!
Excellent dam video Juan.
I live in Newfoundland (eastern Canada), and there's a dam of this exact same type, built at around the same time period, but three times this size, merely a couple of miles upstream from where I live. Can't help but have a nervous feeling seeing this.
Press conference just concluded. According tho the County Engineer, even if the dam failed "tipped over or something" the surge at Mankato would be 1 to 2 tenths of a foot....and I have been corrected that the bedrock is the Jordan Sandstone. While not as erosion resistant as limestone/dolomite, it is pretty good and magnitudes better than the glacial till and topsoil in the area.
Basic question. Was there any attempt to clear debris from the movable gates or destroy the timber gates?
Those were my thoughts.
Why not blow the wooden gates - especially as it appears the dam is no longer generating electricity.
I live in MN and have family in Mankato, so I've been following this closely. They haven't made an attempt to remove the debris because the land next to the river is too unstable to get equipment close enough.
@@jenniferneve2723 So the dam’s load limit is too low for a backhoe? Figures.
@@jenniferneve2723 Perfect application for a remote operated excavator with a long reach boom
I've heard that the wooden gates were removed and replaced with concrete plugs in 2017. Also, explosions do funny things in solids and liquids. Just blasting willy nilly could cause the dam to collapse because the energy went into areas you didn't expect or plan for.
The real elephant in the middle of the room: age of these dams in America. We need infrastructure upgrades & maintenance.
Oroville was a clear example of poor infrastructure maintenance planning on 65 year old concrete.
Thanks for the report and thanks to Still Aerial Photography for the fantastic drone shots.
From what I heard it was build in 1910? If so then it will survive. I tend to agree with geologist here, looks like the foundation is holding. If this was built in 2024 with the modern engineers it woudl be long washed away. Just wonder why they don't have a way for someone to get in and clear the blockage. I guess nobody willing to risk it. We are expecting more rain tonight, so hope it holds up.
That wasn’t an intentional spillway, I don’t think there was an emergency spillway. There was some infrastructure there, and I believe the house has now also washed out.
There is a dam just above the town i live in above the dam it's self is a trash rack so floating debris cannot make it into the dams gates sound's like there has been a failure to safeguard to prevent this from happening including maintenance of cleaning of fallen trees from waterways above the dam these thing are necessary and should be required for all dams
Thank you for the coverage of this dam situation. I grew up near the Twin Cities.
18 Inches of Rain in 3 days tends to do this.
Jaun, this river joins the Minneasota river, and than joins the Mississippi by the MSP airport, this water flows down to Lock And Dam 2 in Hastings MN, I am not sure if I am reading the charts correctly, But to looks like it's at "full" level, as well all the other Dams down river, to the Gulf Of Mexico. Is this going to be dire?
Hello from the Great State of Alabama.
Great video as usually.
I watch the Aviation vids mostly.
Photos indicate that the current bypass was *not* intended as an emergency spillway as it's where an electrical substation sat. I do not see *any* sort of emergency spillway and other commenters claim that the 2 timber gates were recently sealed, reducing the overflow capacity below design levels.
The blocking of the timber gates seems rather dumb at first glance, but there may be reasoning that we are unaware of. I hope it's not just a matter of "well, we haven't used them in decades so we don't need 'em" as that's precisely the sort of short-term thinking that gets us into trouble ;).
The rock at the end of the dam seems quite strong and the water is presently going around the likely sump area quite nicely, so it's unclear whether the dam will actually fail or not. If the water recedes, I suspect that the dam will not fail, but plenty of damage has occurred, regardless.
You can look at the back of the pre-flood dam fairly well from the Glacier Rd bridge in Google street view, but a lot of that has been destroyed.
Back in the old days this was just a limestone waterfall until they decided to put the damn in there is a book of information at the Rapidan Dam store that has pictures from when it was being built and all through the process and the years that they have ran the damn store very nice family that can tell you everything you need to know about that area it was a great catfish and walleye fishing hole
@paulbraam332 - Intersting, thanks for sharing that!
Dam good report!! Thanks Mr Brown
Juan, that is the best damn dam coverage I've seen of this matter. The major news networks should hire you, or just pay you for your video. Thank you.
Thanks for the update Juan.
Opposite side of the "emergency spillway" (East side, I believe) you can see the erosion caused by the spillway.
The Dam Store is saved by an additional 20 feet of elevation where it stands.
Dams are far more tricky to engineer than we thought 100 years ago. In many cases they make floods worse or can fail in rather bad ways if not maintained. I'm amazed that this thing lasted over 100 years.
Like the Johnstown dam back in the 1880s
It only takes a little thinking and a line of boomsticks (long logs chained together end to end) anchored to either shore which will deflect to the side or capture large debris depending on the layout.
1:05 "19 08 - 19 0 10"
Excellent readback 😂
I can't help but ask myself why there is not an excavator up on that dam removing the debris from the gates?
Me too...Wuzzup sheriff?
The Sheriff reported that by the time they discovered the debris blockage it wasn’t safe to put an excavator on the dam.
The dam itself may not fail. Then again, it might. The dam is 114 years old. It was already damaged and due for demolition and possibly replacement even before the floods. Are you willing to bet your life that it won’t fail catastrophically? Because anyone who drives an excavator onto that dam has a death wish.
You are 100 percent correct. It doesn’t appear it would take all the water at this point but before it went over the side if it was clean it would have had a chance at least. Huge mistake not keeping the spillway clean. I have irrigation district experience and that’s a complete lack of management I can’t believe that
@@adamblank713 the sudden heavy rains floated the debris from upstream. That is not within their control.
Apparently there was a small electrical substation on the west side of the generator house. That substation was destroyed by the new flow path. It was noted that the powerhouse supplied around 600 residences and efforts were being made to feed them with an alternative power source.
I live in Washington State and a classmate for Northwest History class drew Grand Coulee Dam for his project; he titled it “Grand Coulee: The Biggest Damn Project in the World!” He intentionally misspelled it on his poster but it drew a laugh from the class & the teacher.
Folks downstream on the Missouri River are keeping an 👀 on the river
Actually, on the Minnesota River. 😂
Juan's Bart Simpson moment at the end 😊
Hi Jaun, thanks for the coverage and your insights. I live about 30 minutes north of Mankato in the Minnesota River town of Belle Plaine. The tributary rivers covered in this piece depict a disaster in the making. Many of the North/South Minnesota River crossings are flooded at this point creating travel backups region wide. Many small towns on the Mighty Minnesota are in danger in spite of recent flood abatement projects to relieve such catastrophes. Areas of Henderson, Jordan, Carver, Chaska, Shakopee and Savage could be severely damaged by the recent excessive rain volume, this dam breach and more heavy rain in the forecast. I've lived in this little river town for 23 years and this could be the worst I've seen in that time. I hope/pray I'm wrong, but its not looking good for our side, as they say.
James Thurber wrote about his experiences of some Ohio River floods. There was a panic when it was falsely reported that a dam had broken. It developed that even if it had, the floodwaters would have gotten only a little higher, a few inches I think.
Dam it Jim ! I'm an aviator not an engineer.
@OfficialBlancolirioxc - I'll be your huckleberry!!! I value your consel as well and would like to talk off this media too, but first I would like to talk to you about your car's extended warranty.