Catastrophic failure of the Mississinewa Dam

[Nick Harby]

Several months ago the Mississinewa Dam was found to have structural
problems.

http://155.80.93.250/ed/damsafe/mississinewa/faq.htm
http://www.icivilengineer.com/News/news.php?id=4734

There is right now serious flooding throughout the Wabash River basin.

http://water.usgs.gov/cgi-bin/daily_flow?in

Before the flooding started, Mississinewa Lake water levels were kept at
717 feet, 20 feet lower than the normal level of 737 feet, to prevent
further damage to the dam.

http://www.crh.noaa.gov/data/IND/RVAIND

Today the water is at 748 feet, 31 feet higher than the previous safe
level. This could not be avoided. The dam is discharging at about 6000
cubic feet per second. This is the maximum possible outflow until the
lake fills up completely and runs over the spillway.

http://www.lrl.usace.army.mil/wc/reports/ceorlresfct.txt
http://www.lrl.usace.army.mil/wc/reports/lkreport.html
http://waterdata.usgs.gov/in/nwis/uv?03327000

Mississinewa River flow at Marion (upstream from the lake) has been
around 16000 cubic feet per second, so there must be more than that
going into the lake.

http://waterdata.usgs.gov/in/nwis/uv?03326500
http://www.crh.noaa.gov/cgi-bin/ahps.cgi?iwx&mroi3

Since flooding started I figure the lake has been filling up at the rate
of about one acre-foot every four seconds. The total capacity of the
lake is 368,385 acre-feet.

http://www.lrl.usace.army.mil/wc/lake-area-capacity2.html

Could this dam fail? Someone please tell me why there is nothing to
worry about. This website describes the Teton Dam failure of 1976.
Teton Dam was also earthen, holding back a similar sized lake (300,000
acre-feet).

http://www.geol.ucsb.edu/faculty/sylvester/Teton%20Dam/welcome_dam.html

If the Mississinewa Dam would fail, there is nowhere for this water to
go. Wabash River levels are already at some of their highest in
recorded history.

http://www.crh.noaa.gov/cgi-bin/ahps.cgi?ind&lafi3

This is what I could find in the media about this. They don't seem
overly concerned about it. It seems to me that even a very low risk
would deserve consideration, as failure of this dam would be
catastrophic, considering the amount of water in it right now.

http://www.theheraldbulletin.com/cgi-bin/LiveIQue.acgi$rec=8070?hb_story

http://www.indystar.com/print/articles/8/056551-7538-093.html

[Ian St. John]

Post by Nick Harby
Several months ago the Mississinewa Dam was found to have structural
problems.

A good picture of the lake and dam is at:
http://www.lrl.usace.army.mil/miss/

It also has links to pictures of the work being done and the progress.

Looks like work has progressed a fair bit, so risk is probably minimal if
the lake level does not stay high too long.

[Brian S Enyart]

Post by Nick Harby
Today the water is at 748 feet, 31 feet higher than the previous safe
level. This could not be avoided. The dam is discharging at about 6000
cubic feet per second. This is the maximum possible outflow until the
lake fills up completely and runs over the spillway.

Where did you find info about the 6000 cubic feet per second?

As of July 11, the water is at 752.6, 4.1 ft higher than the day before.
The spillway on the dam is at 779 feet. I don't think the dam is going
to exceed the spillway any time soon.

Post by Nick Harby
Mississinewa River flow at Marion (upstream from the lake) has been
around 16000 cubic feet per second, so there must be more than that
going into the lake.

This is going down rapidly, and is forecast at under 5000 cubic feet
by late tomorrow (the 12th), falling to near 2500 within 2 days.

Post by Nick Harby
Since flooding started I figure the lake has been filling up at the rate
of about one acre-foot every four seconds. The total capacity of the
lake is 368,385 acre-feet.

10000 cubic feet per second into the lake doesn't sound too out of line.
But, even at that rate, the water won't hit the spillway for several
days, and since the rate into the lake is falling rapidly, I don't see
it as a problem.

This does, however, put excess stress upon the dam. Nothing you've
linked implies that the dam cannot handle those stresses temporarily
(for the few weeks until water levels reach normal again).

Short of continuing rainfall (and very little is forecast for the next
week), this levels will roll off within the next day or two.

Post by Nick Harby
This is what I could find in the media about this. They don't seem
overly concerned about it. It seems to me that even a very low risk
would deserve consideration, as failure of this dam would be
catastrophic, considering the amount of water in it right now.

I'm a little surprised that the media hasn't picked up on it, at least
to come out and say "The dam is fine". Perhaps the media is just short
on members with enough geological background to even understand the
issues.

[Keith W]

Post by Brian S Enyart
I'm a little surprised that the media hasn't picked up on it, at least
to come out and say "The dam is fine". Perhaps the media is just short
on members with enough geological background to even understand the
issues.
--
Brian Enyart
http://home.insightbb.com/~bsenyart

Do you mean to say that your media does actually report *good* news? I
thought that the whole purpose of it was to report doom, gloom and exposes!
Anything less is irrelevant to their readers. 8-)

Keith

[Nick Harby]

Post by Brian S Enyart

Post by Nick Harby
Today the water is at 748 feet, 31 feet higher than the previous safe
level. This could not be avoided. The dam is discharging at about 6000
cubic feet per second. This is the maximum possible outflow until the
lake fills up completely and runs over the spillway.

Where did you find info about the 6000 cubic feet per second?

On this website look up "6 AM Outflow" for Mississinewa. As of 16 July, it is
6335. That is 6335 cubic feet per second.

http://www.lrl.usace.army.mil/wc/reports/lkreport.html

On this website "Q" means water released from the dam. For Mississinewa that
is 6.3 thousand cubic feet per second.

http://www.lrl.usace.army.mil/wc/reports/ceorlresfct.txt

This website shows the height of the river just coming out of the dam. It has
been pretty much at 9 feet since flooding started. Before July 5 it was
pretty much at 2 to 3 feet.

http://waterdata.usgs.gov/in/nwis/uv?03327000

As of 16 July the lake level is at 748 feet. They have been letting water out
of this lake as fast as they can for about ten or eleven days now. The lake
is still 31 feet higher than it was before.

Post by Brian S Enyart
As of July 11, the water is at 752.6, 4.1 ft higher than the day before.
The spillway on the dam is at 779 feet. I don't think the dam is going
to exceed the spillway any time soon.

You are right. Obviously the maximum stress on the dam is when the spillway
is exceeded. But who knows, any high water levels might damage this dam
further.

Post by Brian S Enyart

Post by Nick Harby
Mississinewa River flow at Marion (upstream from the lake) has been
around 16000 cubic feet per second, so there must be more than that
going into the lake.

This is going down rapidly, and is forecast at under 5000 cubic feet
by late tomorrow (the 12th), falling to near 2500 within 2 days.

Post by Nick Harby
Since flooding started I figure the lake has been filling up at the rate
of about one acre-foot every four seconds. The total capacity of the
lake is 368,385 acre-feet.

10000 cubic feet per second into the lake doesn't sound too out of line.
But, even at that rate, the water won't hit the spillway for several
days, and since the rate into the lake is falling rapidly, I don't see
it as a problem.
This does, however, put excess stress upon the dam. Nothing you've
linked implies that the dam cannot handle those stresses temporarily
(for the few weeks until water levels reach normal again).

Just the fact that the problem with the dam was serious enough that they
pretty much had the lake drained before 6000+ cubic ft/sec started going in.

Post by Brian S Enyart
Short of continuing rainfall (and very little is forecast for the next
week), this levels will roll off within the next day or two.

Post by Nick Harby
This is what I could find in the media about this. They don't seem
overly concerned about it. It seems to me that even a very low risk
would deserve consideration, as failure of this dam would be
catastrophic, considering the amount of water in it right now.

I'm a little surprised that the media hasn't picked up on it, at least
to come out and say "The dam is fine". Perhaps the media is just short
on members with enough geological background to even understand the
issues.
--
Brian Enyart
http://home.insightbb.com/~bsenyart