Check out # 2,215 .
Thanks, Maggie.
Posted on 02/12/2017 4:26:47 PM PST by janetjanet998
Edited on 02/12/2017 9:33:58 PM PST by Admin Moderator. [history]
The Oroville Dam is the highest in the nation.
The possibility of clogging on the intake screens is pretty high after all that turbulent spilling. They should have a means to clean out the intake screen area. Hopefully in just a couple of hours.
Spend 80 years building a very expensive system of Dams, reservoirs and recharging wells since 1870 or so, after the great valley flood of 1860.
In the 1970s, spend obscene amounts through bond issues to remove dozens of dams, reservoirs, and abandon to neglect the recharging well system, in the northern half of the state...
10 to 15 years later, Spend massive amounts of money through more bond issues, to please the doped up greenies, drugged-up hippies, friends of bugs, bunnies and sardines, and and "sports" fishermen, added to massive transfer of water to Southern California, where the clueless and wasteful voters and water users are. More than half of the massive bond issues for Purposes other than local citizens' and agricultural needs.
Zero % for adequate maintenance and additions to the infrastructure serving the human needs of the local population.
California, the Nation's breeding grounds for Monumental stupidity and waste.
well now they are saying they are going to clear more debris before they start the power plant again..this is a change since yesterday
the local sheriff said he might lift the evacuation warning Monday if the full 14,000 cfs from all six turbines is flowing.
obviously he was told the plan was to have all 6 up by Monday or soon after
read between the lines:
the water level is rising again because of the outflow from the plants...not enough debris has been removed yet to prevent backup
After a successful restart of the Hyatt Power Plant on Friday, a temporary shutdown began around 10 am today so that the water channel can be deepened for the plant to reach its full capacity. The shutdown is expected to last approximately 1-2 days. The reoperation of the power plant gives the Department of Water Resources (DWR) an important, additional way to release water from the reservoir.
“We will dig deeper so we can fully ramp the plant up,” said DWR Acting Director Bill Croyle.
Initial flow from the plant on Friday was 1,750 cubic feet per second (cfs) and increased to 2550 cfs. Once fully operational, the plant can release up to 14,000 cfs, which is important for managing reservoir inflows and outflows through the spring runoff season.
DWR engineers have determined that further deepening of the channel will help the power plant reach full capacity and that it will take approximately 1-2 days, at which time the plant will be restarted.
DWR halted flows down the damaged flood control spillway last Monday so crews could remove debris at the base of the spillway. Debris removal lowered the water level in the channel at the base of the spillway, making it possible for the plant to resume operation Friday. Crews working night and day have removed 216,000 cubic yards of the estimated 1.7 million cubic yards of debris.
Lake Oroville is not expected to rise above 860 feet elevation while flows are halted. That lake level would be 41 feet below the level of the emergency spillway. The current lake level is 850 feet elevation. Inflows are roughly 10,000 cfs.
DWR does not expect the wet weekend weather to halt additional debris removal or create a lake elevation concern. DWR will continue to monitor the weather forecast.
Hyatt Powerplant was successfully re-operated with one turbine generator unit running at full capacity since 2 pm, March 3, 2017. This test provided vital feedback for construction crews working on the channel excavation and the planning efforts for short and long term reservoir management.
How soon until snow packs melting's a big problem?
Check out # 2,215 .
Thanks, Maggie.
Thanks for the update, Janjet. :)
it all depends on the weather
last year at this time the lake was 780 feet and it topped off at 890...
its 851 right now with record snowpack upstream
they better hope for a dry cool spring
In my opinion the best the power plant can do at 14,000cfs is keep the lake at its current level with out anymore rain and a long cool spring and summer
its obvious they are going to have to use the main spillway again the question is when
the dry spell is over... no precipitation the last 12 days,,and inflow is still 10K without snowmelt
...I don’t see any huge storms more like moderate/typical storms every so often the next 10-14 days starting ...well right now
I’m concerned about the stability of the upper spillway. The photo in 2175 shows water springing from beneath the slabs upstream from the blow out. While back erosion from the blow out seems to have stabilized, new problems are appearing upstream from there. If the spillway begins to break apart near these springs it will have to be shut down PDQ. It takes time to shut down, which will be a constraint on how much flow they can risk (too long a shut down period could be a big prob.). I hope there is a slow snow melt.
Wow. Freaking idiots in the Dept of Water. They should have known what would happen.
What you might be seeing are the sandbags strewn across the spillway near the top to direct the flow down one side only.
They probably did, but their options were/are limited. Normally, they would reduce outflows gradually, but when they dropped down to around 30,000, the water falling off the end of the spillway was starting to erode and undermine new ground under the spillway and threatened losing another section of spillway as well as possibly one of the electric transmission towers nearby.
Kind of a "damned if you do, damned if you don't" situation.
Almost directly opposite, on the right, is an irregularity. If that is sandbags it's unusual placement, isolated as it is. Also, it appears to be part of a "herringbone crack"
These two are the areas I'm concerned about.
Oh, I see - yeah, there’s a little trickle from a couple of weep holes on the left. I thought you were referring to the rows of sandbags way up near the top of the spillway, directing water to the right. I’m not in a good position to describe the details of what you’re noticing.
I don’t know either. Any deterioration of the upper spillway is well... alarming.
The part I’m most concerned about is the very end of the upper spillway. At flows lower than about 45,000 fps, it seemed that it was washing the earth under the end, and could result in tearing out yet another section of concrete slab. My thought would be to shore that up and put some hardened rock/concrete under that lip to allow lower flowing without significant erosion.
They could have alerted land owners what was going on/going to happen. That is not a normal event, so few would have foreseen it, but water experts should have know.
Too bad.
I’ve been following this since the beginning so I know about the spillway damage etc, all due to the dept of water and CA gov idiocy. Human caused disaster.
Bookmarking...
The "angled cracks" in the spillway concrete slabs and the "jetting" of water out of the sidewall drains should have set off alarms years ago regarding the integrity of the Oroville Main Spillway.
Why? Both of these signs indicate a serious known failure mode in spillways from Stagnation Pressure (via cracks/voids/water). Two prominent examples are Big Sandy Dam, Wyoming, 1983, (spillway chute failure) - Dickinson Dam, North Dakota, 1954 (spillway chute failure).
Excessive water beneath the concrete slabs causes a very powerful effect dubbed "hydraulic jacking" from under the slab (think of a hydraulic car jack). Called in engineering terms: "Stagnation Pressure" & "Stagnation Pressure Failure".
How does the water get under the slabs? The most potent source is from pressurized water from the top of the spillway being forced below through cracks & non-sealed seams in the concrete chute. The more cracks, the more water, the more water, the greater ability of this water to "wash or erode away material" under the slab. Erosion leads to "voids". Voids + "hydraulic jacking" lead to greater stresses on the slab.
How do you protect from "Stagnation Pressure Failure"? Drain pipes are placed under the concrete slabs to collect & drain any leakage, thus preventing a pressurized water layer under the slab. A well sealed & healthy spillway would have very little waterflow out of the drains. The Oroville Main Spillway slab design is less than modern standards. (1) Modern slab designs have rebar in the top layer and the bottom layer. Oroville's slab design only had a top layer of rebar. (2) Modern slab designs retain the full thickness of the slab by placing drain pipe & pervious material below the slab. Oroville's slab design created a 40% reduction in thinning of the slab from the placement of intervals of drain pipes & gravel - forming a inverted "V" of non-concrete. (3) Aggravating the Oroville design was the lack of a lower layer of rebar in the slab. Thus (1)(2)(3) should have set off alarms when high waterflow was "jetting" out of the drains.
A Reclamation Dam was found to have dangerous voids & erosion under the spillway concrete (see picture below). Voids are easily identifiable using Ground Penetrating Radar (GPR) from the top surface of the slab. In the case of this dam, the engineers/maintenance authorities ended up fixing this by a complete replacement of the spillway chute and the spillway foundation.
Oroville's Main Spillway was simply an "accident waiting to happen".
History of posts, discussion, & reference photos:
Pre-failure Herringbone crack patterns in Main Spillway (drain pipes)
HerringBone Drain Pipe - Fracture pattern in Main Spillway
Construction modifications of Main Spillway Drain System
Years of Warning at Blowout Area? Missing drain water/slabs being repeatedly repaired at leakage
Alarms Raised Years Ago About Risks of Oroville Dam's Spillways
Oroville's slab design only had a top layer of rebar. Oroville's slab design created a 40% reduction in thinning of the slab from the placement of intervals of drain pipes & gravel - forming a inverted "V" of non-concrete. Aggravating the Oroville design was the lack of a lower layer of rebar in the slab.
Modern slab designs have rebar in the top layer and the bottom layer. Modern slab designs retain the full thickness of the slab by placing drain pipe & pervious material below the slab.
A Reclamation Dam was found to have dangerous voids & erosion under the spillway concrete (see picture below). Voids are easily identifiable using Ground Penetrating Radar (GPR) from the top surface of the slab. In the case of this dam, the engineers/maintenance authorities ended up fixing this by a complete replacement of the spillway chute and the spillway foundation.
Oroville Main Spillway drains showing a high volume of waterflow under the concrete slabs - observable by the "jetting" of water from the drain outlets in the sidewalls.
3/4 to 2 inches of precip fell in the drainage basin the past 24 hours
look like another 1 inch or so the next 24 hours but much of that should be snow..
there will be isolated thunderstorms today in the foothills..hopefully not over the basin
big warm up by thursday may cause some snow melting
longs range models now show a very active wet pattern 8-14 days out
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