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another with a little more info...about retired engineers.....

Bea concluded there were problems with the spillway at the design phase, which continued on through construction phase, and continued undetected through decades of maintenance and operation.

Part of his conclusions came from three retired DWR staff who he has promised not to name, he told the committee members.

When he looked through inspection reports he saw “cracks that have been painted over,” and broken anchors at the spillway gates, Bea said.

DWR has said the green spots on the dam are naturally occurring. Yet, Bea said there should be more investigation. “In my view, nothing like that is taken as natural until proven natural.”

http://www.orovillemr.com/general-news/20170511/oroville-spillway-another-round-of-questions-for-water-leaders-working-on-repairs

If the Oroville Dam wet “green spot” is caused by lake water flowing through a leak or crack, that flow rate of water and/or particles through the dam must be a function of the driving head, measured by the lake elevation.

The observed phenomena:
1) greening or browning of various vegetative patches within the green spot area, and
2) creation of a high density of long vertical channels weeping out below the green spot area
must both be a function of this lake elevation generated flow.

The highest lake level in recent record was during the spring and summer of 2011, when the lake was within a few feet of topping out for months on end. The only time the green spot flow rate would have ever been higher is for just a few days in Feb 2017. The aggregate volume of green spot flow would have been greater in 2011 than (so far) in 2017.

It appears from the photographic evidence readily available so far that this year’s green spot has been greener than any year within recent photographic record, including 2011, when the aggregate flow to the green spot should been higher. However, DSOD reported wet moisture in February and May of 2011, and there is an unconfirmed report for October.

IMHO, if more evidence comes out that the green spot remained green or wet through the late 2011 summer , then that would be almost conclusive evidence that the water originates from the lake. However, if the green spot dries up as the lake rises this June, then this indicates the green spot is not sourced from reservoir water.

Hi janetjanet998, thanks for the links & info. Along this subject, Scott Cahill has said that "insiders" have come forward, which Scott is keeping their names confidential, on information that is not public. The interesting tidbit that Scott revealed (via the someone in the "know" regarding slab repairs) was how big the voids became under the "failed" spillway location. I was shocked (sort of). I heard depths of up to 6 feet in one of the largest voids. 4 foot was mentioned somewhere else on the spillway (any info lurkers - go check out the early Scott Cahill youtubes - its in there in one of them)

These news links you reference - I believe these are tied to yesterday's State legislative hearing on the dam. Seems DWR was hammered at the hearing.

Another new SacBee article reveals that DWR & California may not be federally compensated if this spillway failure was from improper maintenance. Only if the event is considered to be a natural disaster is the key consideration to federal assistance funding. There must be intense pressure on DWR given how events are progressing (i.e. people coming forward, more info & reports not looking so good, new subjects being discussed - like the leak, etc).

Prof Bea brought up the Anchor tendons that had failed at the Oroville flood control Radial Trunnion Gates. Speaking of which. I've been sidetracked on the anchor tendon postings. Here's one for you. It gives some engineering insight into how "numbers" can be shuffled in a pinch.

Failure analysis of failed tendons (steel bars stretched to near 160,000 psi tensile load) found that a cut or crack of 1/8 inch was the critical failure size.

So early on a number of 1/32 inch was chosen as "considered significant". Yet the 1/32 number reveals it was sort of a "let's choose something that is a round number of 4 times less than the failure size". Actually, the surface area (ignoring the "v" width) of an ultrasonically tested anchor rod crack is 783% decrease in area from 1/8" to 1/32". That was in 1999/2000. Fast forward to 2012 and magically the new number to be concerned about is 1/16 inch....but hang on....DWR renamed the crack of "considered significant" at 1/32 inch to a "minor flaw" at 1/16 inch.

There is more to this story... but you get the picture. (btw- for engineering lurkers... even the 1/16 inch swizzle didn't help them as 12 anchor tendons have cracks above 1/16 inch & even one close to 1/8 inch from back in the original 2000 test report data findings - yet DWR has done nothing to replace these identified cracked tendons).

Engineering swizzle games? Don't worry about the math, just peruse the marked up comments.

So a natural disaster cause is being used to attempt to make this Fed dollar eligible. Then, when the spillways are repaired they will go back to the Feds and say we discovered the Gates are bad. After that is paid for the monitoring will show settlement is going to allow a dam blow-out at the Christy Jones Memorial Lawn and Undermined Area and Fed dollars will be needed again.

All because California government and voters won’t do their jobs. I am sick of paying for this crap.