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From what I gathered the main spillway is quite damaged with a ~ 200' x 30' eroded hole in the center, potentially eroding into the supporting hill. It was a pr

From what I gathered the main spillway is quite damaged with a ~ 200' x 30' eroded hole in the center, potentially eroding into the supporting hill. It was a problem even before they doubled the outflow to 100,000cfs yesterday which I believe is still the current flow. They want to get the lake down 50' to shutoff the spillway and assess repairs, but even at the current (high) release rate it appears they can only lower max ~8'/day, which is a problem because heavy rains return on Wednesday. Let alone the emergency spillway, the main one's at risk too.

throwawaydbfif 10y ago
I get the feeling the dam is likely doomed and they're trying to drain the lake as much as possible to decrease the force of a break
- tajen 10y ago
  Indeed, 13 times more dams than France (who prides itself for 12% hydroelectricity), while USA is only 5 times bigger in population. China has the most number of large dams in the world: More than twice the USA, for 4x population. http://www.icold-cigb.org/article/GB/world_register/general_synthesis/number-of-dams-by-country-members http://www.icold-cigb.org/article/GB/world_register/general_...
  - Bombthecat 10y ago
    That's... Quite impressive...
- tbabb 10y ago
  The spillway is kind of "around the corner" from the main dam, so I would guess the latter is probably not "doomed," at least at this point. A realistic disaster scenario would be if the erosion retreats all the way back to the main spillway gates, or if it undermines the emergency spillway. The berm there would then fail, which holds back maybe 15 or 20 feet of lake altitude. A volume of water equal to that depth times the surface area of the lake would then exit over the hillside, completely uncontrolled. That would be more than enough to cause a serious downstream disaster. The water flows would be very high (~a million CFS? total guess) which would cause even more severe erosion on that hillside. At that point the main dam might be at risk if the erosion traveled far enough laterally.

throwawaydbfif 10y ago

I get the feeling the dam is likely doomed and they're trying to drain the lake as much as possible to decrease the force of a break

tajen 10y ago
Indeed, 13 times more dams than France (who prides itself for 12% hydroelectricity), while USA is only 5 times bigger in population. China has the most number of large dams in the world: More than twice the USA, for 4x population. http://www.icold-cigb.org/article/GB/world_register/general_synthesis/number-of-dams-by-country-members http://www.icold-cigb.org/article/GB/world_register/general_...
- Bombthecat 10y ago
  That's... Quite impressive...
tbabb 10y ago
The spillway is kind of "around the corner" from the main dam, so I would guess the latter is probably not "doomed," at least at this point. A realistic disaster scenario would be if the erosion retreats all the way back to the main spillway gates, or if it undermines the emergency spillway. The berm there would then fail, which holds back maybe 15 or 20 feet of lake altitude. A volume of water equal to that depth times the surface area of the lake would then exit over the hillside, completely uncontrolled. That would be more than enough to cause a serious downstream disaster. The water flows would be very high (~a million CFS? total guess) which would cause even more severe erosion on that hillside. At that point the main dam might be at risk if the erosion traveled far enough laterally.