Rapidan Dam in Mankato, Minnesota is in imminent danger of failing

7,313 Views | 63 Replies | Last: 4 mo ago by sam callahan
Burnsey
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Rapier108 said:

Looks like this is a run of the river type dam; there is no lake impounded behind it.

Basically what happened is the flooding jammed up a lot of debris at the dam, and the water what water does, found another path. In this case around the sides of the dam and quickly eroded the soil.

In this case, it isn't failing due to poor maintenance, but rather an event it wasn't intended to encounter.
Oh. I see. So nobody thought that one day the river might flood. I guess nobody is at fault then.
Al Bula
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Rapidan?! More like Rapidam! Amirite?!
BigRobSA
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Burnsey said:

Rapier108 said:

Looks like this is a run of the river type dam; there is no lake impounded behind it.

Basically what happened is the flooding jammed up a lot of debris at the dam, and the water what water does, found another path. In this case around the sides of the dam and quickly eroded the soil.

In this case, it isn't failing due to poor maintenance, but rather an event it wasn't intended to encounter.
Oh. I see. So nobody thought that one day the river might flood. I guess nobody is at fault then.


I don't read what Rapier said as an absolvement, per se', but as a volumetric qualifier. At 42X flow, it was overwhelmed. It would have been OK up to 41X. (Numbers pulled out of my ass, but you get the picture..)
BigRobSA
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Al Bula said:

Rapidan?! More like Rapidam! Amirite?!
#TooSoon


mjschiller
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Trumps fault
Marvin J. Schiller
ts5641
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Nanomachines son said:

The infrastructure bill sent most of the money to diversity programs, which is our strength, and not to actual repairs or upgrades of existing infrastructure because diversity is our strength, which is the most important part.
Infrastructure bills never actually go to infrastructure.
LMCane
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Detmersdislocatedshoulder said:

can some remind me again what we got for the 30 plus trillion of debt we have piled up over the last 20 years. sure as **** isn't infrastructure

democrat union members have a nice second home on the beach
BourbonAg
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Why was my post deleted?
doubledog
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Minnesota : Land of 10,000 lakes (-1).

Let's get some of the protestors from Minneapolis/St. Paul to stand in front of the flood waters. No harm in trying.
schmellba99
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It saddens me to see some of the sheer dumbassery posted by people that should not be commenting on anything related to civil projects.

Please, for the love of A&M - quit posting. You are making my degree less valuable.
Hoyt Ag
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ts5641 said:

Nanomachines son said:

The infrastructure bill sent most of the money to diversity programs, which is our strength, and not to actual repairs or upgrades of existing infrastructure because diversity is our strength, which is the most important part.
Infrastructure bills never actually go to infrastructure.
Same for Inflation Reduction Act.
CDUB98
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schmellba99 said:

It saddens me to see some of the sheer dumbassery posted by people that should not be commenting on anything related to civil projects.

Please, for the love of A&M - quit posting. You are making my degree less valuable.
Well, you really do a good job of that all on your own.
torrid
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Rapier108 said:

BigRobSA said:

Rapier108 said:


In this case, it isn't failing due to poor maintenance, but rather an event it wasn't intended to encounter.
Ummmmm, a river-based dam wasn't intended to encounter debris from rising waters?

Sounds like something a river-based dam would actually be designed specifically for. And a contingency available for this exact issue.
The spillway was blocked by debris.

The dam likely was never designed to handle a flow rate 42 times higher than normal with the spillway being clogged up.
Does it even have a spillway? I mean it does now, but what about before?
CDUB98
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It wasn't a true dam in that sense. It was more of a water holdup to force water into the generation house/turbines.

The rest of the water just overflowed in the spaces between the road and the top of the damn. It was always free flowing.
Hoyt Ag
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CDUB98 said:

schmellba99 said:

It saddens me to see some of the sheer dumbassery posted by people that should not be commenting on anything related to civil projects.

Please, for the love of A&M - quit posting. You are making my degree less valuable.
Well, you really do a good job of that all on your own.
Pot meet Kettle.
CDUB98
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Hoyt Ag said:

CDUB98 said:

schmellba99 said:

It saddens me to see some of the sheer dumbassery posted by people that should not be commenting on anything related to civil projects.

Please, for the love of A&M - quit posting. You are making my degree less valuable.
Well, you really do a good job of that all on your own.
Pot meet Kettle.
I know where you live.
BourbonAg
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BourbonAg said:

Why was my post deleted?
schmellba99
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CDUB98 said:

schmellba99 said:

It saddens me to see some of the sheer dumbassery posted by people that should not be commenting on anything related to civil projects.

Please, for the love of A&M - quit posting. You are making my degree less valuable.
Well, you really do a good job of that all on your own.
Well.....YOUR MOM!
schmellba99
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torrid said:

Rapier108 said:

BigRobSA said:

Rapier108 said:


In this case, it isn't failing due to poor maintenance, but rather an event it wasn't intended to encounter.
Ummmmm, a river-based dam wasn't intended to encounter debris from rising waters?

Sounds like something a river-based dam would actually be designed specifically for. And a contingency available for this exact issue.
The spillway was blocked by debris.

The dam likely was never designed to handle a flow rate 42 times higher than normal with the spillway being clogged up.
Does it even have a spillway? I mean it does now, but what about before?
Looks like it has a spillway at the top of the dam under the driving surface, which is what is clogged up by the debris. No spillway on the sides like you often see at reservoirs.
Ag with kids
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schmellba99 said:

CDUB98 said:

schmellba99 said:

It saddens me to see some of the sheer dumbassery posted by people that should not be commenting on anything related to civil projects.

Please, for the love of A&M - quit posting. You are making my degree less valuable.
Well, you really do a good job of that all on your own.
Well.....YOUR MOM!
This post is useless w/o pics.
schmellba99
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Ag with kids said:

schmellba99 said:

CDUB98 said:

schmellba99 said:

It saddens me to see some of the sheer dumbassery posted by people that should not be commenting on anything related to civil projects.

Please, for the love of A&M - quit posting. You are making my degree less valuable.
Well, you really do a good job of that all on your own.
Well.....YOUR MOM!
This post is useless w/o pics.
Texags doesnt like pics of a certain nature to be posted. So sorry.
ABATTBQ11
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bobbranco said:

Hyperbole from the Kaintuck befuddles the waffle flight.


It's not hyperbole if it's just stupid
bobbranco
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ABATTBQ11 said:

bobbranco said:

Hyperbole from the Kaintuck befuddles the waffle flight.


It's not hyperbole if it's just stupid
Stupid and hyperbole are complimentary. Sorry.
ABATTBQ11
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Similar thing happened with the Canyon Lake dam in 2002.

Quote:

In a matter of hours in July 2002, flooding rains unearthed eons of history beneath a swath of Hill Country landscape near New Braunfels. Nearly three feet of rainfall in one week pushed water over the emergency spillway of Canyon Lake for the first time since its 1964 creation, reaching a peak rate of roughly 67,000 cubic feet per second. By contrast, tubers on the Guadalupe River typically enjoy 350 cubic feet per second, and the Canyon Dam floodgates top out at 5,000 when wide open.


"It took three years to fill the original lake," says Cinde Thomas-Jimenez, environmental education administrator for the Guadalupe-Blanco River Authority. "Water going over the spillway during the flood could have filled the lake one-and-a-half times."


https://texashighways.com/travel/the-fruits-of-a-flood-canyon-lake-gorge/
B-1 83
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schmellba99 said:

torrid said:

Rapier108 said:

BigRobSA said:

Rapier108 said:


In this case, it isn't failing due to poor maintenance, but rather an event it wasn't intended to encounter.
Ummmmm, a river-based dam wasn't intended to encounter debris from rising waters?

Sounds like something a river-based dam would actually be designed specifically for. And a contingency available for this exact issue.
The spillway was blocked by debris.

The dam likely was never designed to handle a flow rate 42 times higher than normal with the spillway being clogged up.
Does it even have a spillway? I mean it does now, but what about before?
Looks like it has a spillway at the top of the dam under the driving surface, which is what is clogged up by the debris. No spillway on the sides like you often see at reservoirs.
And clearing flash flood debris from that while the flash flood is still going on might be a wee bit difficult. With a 100 year old dam, I have to wonder what changes have occurred in the watershed during that time as far as land use/cover. It could sure impact the original designed runoff curve (assuming they did that back then).
Being in TexAgs jail changes a man……..no, not really
torrid
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Update on the dam situation:



The river appears to have completely bypassed the damn to the west, so whether it collapses or not it a moot point. The river has carved into the land close to the supports for the bridge upstream, so that highway is completely closed.

There was a cafe located right by the dam that seemed to have good pies. I think the family that ran it lived in a house that collapsed into the river yesterday. A couple of days ago, the cafe showed up online as "temporarily closed". Now all of its social media seems to have been scrubbed. Too bad for the family that lost both its home and its livelihood.
torrid
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Further update - County officials purchased the family store and demolished it, preventing it from falling in the river and causing more damage downstream.

https://apnews.com/article/rapidan-dam-store-flooding-minnesota-weather-aaae621d345ac4d946950f3b704b3f0f
one safe place
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That would be the fastest action taken by any county in the history of mankind.
sam callahan
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Quote:

That would be the fastest action taken by any county in the history of mankind.


While part of me wants to praise them for fast action, the realist side of me expects the owners brother in law is county judge.
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