Repost from page 1450. There may be new people looking at this thread.

If you never watched this, its is crucial to see. Real numbers from an MIT hack into the DWR spillway page. Good footage too.

( Paveway 1V):
Harmonic tremors are an earthquake thing. Harmonic vibrations, especially low-frequency ones on a structure being hammered by nearly 100,000 CFS of fast-moving, flowing water are also... undesirable. Marty D'Angelo covered the issue in a few of his videos:

[link to www.youtube.com (secure)]


The frequency of these vibrations are below the hearing threshold and measured by sensors in the spillway. I've never heard them in Marty's videos (because: crappy speakers) but I do remember people described the new spillway test flow sounding like a chugging (like a train), meaning the spillway or the rock underneath was heaving enough to change the sound of the water gushing down the spillway. Seems sketchy for a brand new spillway.


I think Marty got in trouble for getting that sensor data (because: DWR secrets). So, the main spillway may rip itself apart if it has to run full-bore for a day or two. Or it may be fine. DWR doesn't seem worried about it, so I guess we're good.

Plenty of other 'Dam problems' pre- and post-new-spillway snark from Marty on his YouTube channel. He hasn't posted in a while, AFIK.