[TheDude]

How long will man-made dams last without upkeep? How 'bout some examples of the consequences if certain ones gave way?

I grew downstream from Heppner, Oregon, which suffered a terrible flash flood in 1903 which killed about 225 people. In the 80's the Army Corp of Engineers built a roller-compacted concrete dam, which us rubes immediately had our doubts about - should you be able to see the waterline through a dam? Should plants be merrily growing on the dry side of the thing? I heard a story about someone overhearing a ACE employee saying that "We'll get the next one right." An earlier dam in southern Oregon had given out, if I recall correct.
About 12 years ago in a community college's A/V department I noticed a pair of videotapes labeled "Willow Creek Dam." A scientist was wandering around in the galley inside the dam, pulling chunks of concrete out with disturbing ease. My family moved away in the mid-80s but I always wonder if the dam'll hold up.

[green_achers]

Catastrophic failure like you're talking about is rare, but it happens. When it does, it's a failure of engineering, not "shelf life." No dam AFAIK is designed to fail. What they do is fill with sediment.

[Loki]

Good question, but there isn't a single answer. The Teton Dam in Idaho broke before the reservoir was even filled up, killing 14 people. The Edwards Dam in Maine was almost 130 years old when they removed it for fish habitat restoration--I don't think there was anything wrong with it structurally. I came across a small dam built by the CCC in the 1930s in southern Arizona that was completely silted up, so it was basically useless after a few decades. I've heard Bonneville Dam had a projected 100-year lifespan, but I strongly suspect that was merely for accounting purposes. I wrote the Corps about this but they never responded. The chief engineer for the massive Nagarjunasagar Dam in India claims that it will have "at least" a 1000-year lifespan, which strikes me as more than a bit optimistic.

So the answer is 5 minutes (Teton) to 1000 years (Nagarjunasagar).

[gg3]

RCC is in my estimation still an experimental technique. It was adopted as a cost-saving measure, as an intermediate grade of construction between earthen dams and poured concrete.

As for the silting problem, couldn't that be controlled by simply dredging the stuff out every so often?

[MD]

$this->bbcode_second_pass_quote('TheDude', 'H')ow 'bout some examples of the consequences if certain ones gave way?

[Tanada]

$this->bbcode_second_pass_quote('gg3', '
')As for the silting problem, couldn't that be controlled by simply dredging the stuff out every so often?

[green_achers]

$this->bbcode_second_pass_quote('Tanada', '')$this->bbcode_second_pass_quote('gg3', '
')As for the silting problem, couldn't that be controlled by simply dredging the stuff out every so often?

[Tanada]

$this->bbcode_second_pass_quote('green_achers', '')$this->bbcode_second_pass_quote('Tanada', '')$this->bbcode_second_pass_quote('gg3', '
')As for the silting problem, couldn't that be controlled by simply dredging the stuff out every so often?

[Keith_McClary]

$this->bbcode_second_pass_quote('TheDude', 'H')ow long will man-made dams last without upkeep? How 'bout some examples of the consequences if certain ones gave way?

[PrestonSturges]

At least close to the dam, you could set up a siphon tube suck up the muck as if you were cleaning your aquarium, discharging the water to a settling pond downstream. This would pick up silt and leave gravel.

[PrestonSturges]

Some low head dams last over a century despite being hammered by massive floods. Those are mostly for navigation but some of them also generate hydropower.

The Conawingo Dam on the Susquehanna River has been around since 1928. I has never been overtopped, but Hurricane Agnes came very very close.

[Lore]

Here I looked it up for you.

$this->bbcode_second_pass_quote('', 'S')helf life is generally 7-10 days, but can be longer for hard shell clams and oysters. Because soft shelled clams cannot close their shells they can have a shorter shelf life than hard shell clams and oysters. Keep shellfish alive until ready to prepare.

[hvacman]

Whats the shelf life of THIS dam?

https://en.wikipedia.org/wiki/Shasta_Dam

Shasta dam - my backyard hydro system:) 602 feet tall, 543 feet thick of solid reinforced concrete at the base. 30 feet wide at the top. 15 million tons of concrete. I don't think a Lancaster could do much to the basic structure - maybe just take out the hydro plant or the drum gate at the top.