4 ms·

Wouldn't there still be a diversion tunnel or channel from when the dam was originally constructed? I wonder if those could be used to empty a reservoir. Or may

Wouldn't there still be a diversion tunnel or channel from when the dam was originally constructed? I wonder if those could be used to empty a reservoir. Or maybe the water pressure and flow rate of a full reservoir would be too high...

pengaru 3y ago
I don't think those are sealed upon completion in a gracefully reversible manner. My guess is dynamite blasting and dumping stone to collapse/fill it in until the water stops flowing. This short video[0] describes the process used for the Hoover Dam... sSounds like the blasted diversion tunnels were above the river level, then ad-hoc "cofferdams" were filled in both upstream and downstream of the construction site. So even if you reopened the diversion tunnels, it still wouldn't be down to the original level. It certainly doesn't seem like it'd be a controlled release of the water if you could manage to unseal them. There's no gate... [0] https://www.youtube.com/watch?v=n9Gy_1Ppw5U https://www.youtube.com/watch?v=n9Gy_1Ppw5U
- Arrath 3y ago
  > My guess is dynamite blasting Exactly right! I was involved in a 'lake tap' project in Oregon where the concrete plug in the diversion tunnel was mechanically demolished down to the minimum safe thickness, then we came in and finished it off with explosives. A gate structure was first built farther down the tunnel, to allow the operators to again close off the tunnel or chose a given flow level and let me tell you, having to sidle sideways through that partially open gate to go place explosives into the remnants of the tunnel plug was an interesting experience. Here is a presentation put together on the project: https://ndiastorage.blob.core.usgovcloudapi.net/ndia/2005/triservice/track1/schlenker.pdf https://ndiastorage.blob.core.usgovcloudapi.net/ndia/2005/tr...
  - pengaru 3y ago
    > Here is a presentation put together on the project: https://ndiastorage.blob.core.usgovcloudapi.net/ndia/2005/triservice/track1/schlenker.pdf https://ndiastorage.blob.core.usgovcloudapi.net/ndia/2005/tr... Dude, this has to be one of my favorite and most relevant HN responses ever. Thanks for digging up and sharing that link! "Water Hammer Equation" "Gate Openings 6'x2' (25% of blast area)" this is bonkers.
    - Arrath 3y ago
      My pleasure! Enjoy!
  - phyzome 3y ago
    That sounds intense. :-) And wow, I'd never thought about the effects of a dam on waterway temperature. :-O
- phyzome 3y ago
  Hah, I guess that makes sense.

pengaru 3y ago

I don't think those are sealed upon completion in a gracefully reversible manner. My guess is dynamite blasting and dumping stone to collapse/fill it in until the water stops flowing. This short video[0] describes the process used for the Hoover Dam... sSounds like the blasted diversion tunnels were above the river level, then ad-hoc "cofferdams" were filled in both upstream and downstream of the construction site. So even if you reopened the diversion tunnels, it still wouldn't be down to the original level. It certainly doesn't seem like it'd be a controlled release of the water if you could manage to unseal them. There's no gate... [0] https://www.youtube.com/watch?v=n9Gy_1Ppw5U https://www.youtube.com/watch?v=n9Gy_1Ppw5U

Arrath 3y ago
> My guess is dynamite blasting Exactly right! I was involved in a 'lake tap' project in Oregon where the concrete plug in the diversion tunnel was mechanically demolished down to the minimum safe thickness, then we came in and finished it off with explosives. A gate structure was first built farther down the tunnel, to allow the operators to again close off the tunnel or chose a given flow level and let me tell you, having to sidle sideways through that partially open gate to go place explosives into the remnants of the tunnel plug was an interesting experience. Here is a presentation put together on the project: https://ndiastorage.blob.core.usgovcloudapi.net/ndia/2005/triservice/track1/schlenker.pdf https://ndiastorage.blob.core.usgovcloudapi.net/ndia/2005/tr...
- pengaru 3y ago
  > Here is a presentation put together on the project: https://ndiastorage.blob.core.usgovcloudapi.net/ndia/2005/triservice/track1/schlenker.pdf https://ndiastorage.blob.core.usgovcloudapi.net/ndia/2005/tr... Dude, this has to be one of my favorite and most relevant HN responses ever. Thanks for digging up and sharing that link! "Water Hammer Equation" "Gate Openings 6'x2' (25% of blast area)" this is bonkers.
  - Arrath 3y ago
    My pleasure! Enjoy!
- phyzome 3y ago
  That sounds intense. :-) And wow, I'd never thought about the effects of a dam on waterway temperature. :-O
phyzome 3y ago
Hah, I guess that makes sense.