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]
This image reveals the drain system design. Two longitudinal drain pipes are captured showing the downslope rise of the longitudinal pipes AND the outward spacing of the higher pipe. This outward spacing "jog" is important as it allows clearance for the vertical access cleanout pipes. Without this "jog" outward the overlapping downslope longitudinal pipe would block the vertical pipes that are needed for inspection and cleanout (maintenance - if needed) to each underslab drain pipe.
Each longitudinal drain pipe is connected to a given set of underslab drains (not revealed in this image). If a person was clever they could estimate the number of drains connected together based on this photo and then reverse engineer the slope of the spillway. These drains are angled downhill such that water "self flows" all of the way to the end point. Each longitudinal drain section "end" will be at a spillway sidewall opening to allow the water to trickle or flow back into the main spillway chute. Note that the pipes may not look angled properly, but the camera image has an optical effect demonstrated by the image's artificial curvature of the leveling concrete edge (see edge just above center workers' helmets).
It is likely that the first drain outlet will be connected to the original spillway section that will remain for 2017/2018. I would anticipate that the designers would want to keep these drains isolated from the new spillway drains as a problem could occur from the old spillway section "pre-charging" the new spillway drains from any potential "excessive flows". (excessive flows from the know design issues of the highly cracked slabs, clay seam underslab voiding channels [further erosion] facilitating "piping", and old style contraction joint "seams" without "waterstops" to block water penetration).
Another revelation to this design is that it evidences that they likely plan on placing back fill material behind the new sidewalls. This back fill material provides protection for the piping, insulation to cold temperatures, and would provide important structural support to the vertical sidewalls.
Underslab Upper Spillway drain pipe dumps into a longitudinal drain pipe. Longitudinal drain connects to a given number of nearby slab drains, then angles outward, downslope and then into upper spillway sidewall to dump back into the spillway chute.
A mix of information. This image shows the small concrete blocks that are wired to the reinforcement bar. These blocks keep the sidewall wood forms aligned to the pre-aligned structure that the internal I-Beams are set to - plus the thickness of the outside secured rebar.
Workers are pouring concrete in one of the sidewall forms using a concrete pumping truck. The green colored boom from the truck is above the sidewall. Concrete is pumped throughout the boom structure via the white pipe and into the flexible black hose.
A large crane is in the middle of the action on top of the leveling structural concrete. A fun question: How does the crane get out? (when it's done)
Early Morning Sun - Sidewall Concrete pour - Concrete sidewall alignment spacer blocks - How will the crane get out?
Nice image
“How will the crane get out?”
The same way you get a car into the Dean’s office.
there is a wall section left out in the bottom right that with some arrangements of cribbing they can get to...
Easy.
You just get a much bigger crane and lift it out!
(kidding)
Haven't heard:
(1) Let it wash away in a spillway flow
(2) Dig a hole and bury it
(3) Somehow lift itself out
(4) Use anti-grav pods
(5) Use a cloaking device
(6) Use invisible paint
I like the anti-grav pods. But if we had that tech we wouldn’t need cranes.
Take it apart and lift the pieces with another crane.
I thought that was one(and probably the) answer. That will be a 10 on the pucker factor with the grade involved.
There's an aggregate side access road in the upper right of the photo next to the white coated concrete sidewall. This is the way out. The lower right section in the photo does not have an access road but a steep embankment (you can see the dried tree branches in the photo), so this would not be the way out.
When they fill in the leveling concrete on both sides of the "stay forms" of the drain section, the crane will have a flat surface to drive across. Cribbing will be laid ahead across the drain channel(s) and the flat concrete to protect the leveling concrete from the tracks as is currently set upon.
You can see that the crane is already straddling a drain section (left side image - tracks).
Notice they have drilled and placed the anchor bolts to left of the crane. They haven't placed anchor bolts to the exit path of the crane (to the right). This reveals the "exit" direction.
With one crane centered in the spillway, they save having to use two cranes on the sides. You can see one of the side cranes in the left of the photo. This side crane wouldn't have the heavy lift, and possibly reach, to work the other side of the spillway.
Logistics.
But I like the "Dean's office" answer the best.
Good planning and logistics. Many underestimate what a non-trivial task it is just setting up and relocating equipment of the size being used on the site.
Notice the tree trunk and rootball at the bottom center of the picture.
Aside: Right now, next to my property, they are doing logging operations. The outfit is using a tracked excavator type of base unit "feller buncher" monster that grabs a tree, cuts it with a large radial saw at the base, then lays it down. They need the mass and size on the machine as they are laying down 200+ foot tall fir trees. The operator angles the drop through other standing trees so the standing trees' branches slow the fall. This limits base log breakage from uneven ground impact.
You can almost feel the "thumps" from the impact. The work area is only about 200 yards from my house. Work starts at about 4 am each day to work in cooler temps during forest fire designated conditions.
The Spillway trees seem small compared to the big firs and large cedar trees in the PNW. Of course, nothing beats the Sequoias in Northern CA.
Side commentary: I have a sequoia tree I planted on the corner of my property about 30 years ago. It was a live Christmas tree which we planted there after the holidays. The tree is very happy as it resides in a proliferous natural spring. The tree has all but sucked the year-round spring into oblivion, but it has grown into a sizable & tall beast.
I'm used to the pleasant smell of fir tree and pine tree pitch in eastern Oregon & Washington. But, I found out that sequoias have their own version of an aromatic scent. Reminds me of fragrant potpourri. Much different than the eastern OR/WA pitch aroma.
Morning for black java, hot and cup in hand
Over 100,000 cubic yards of RCC placed in filling the deep chasm carved from the blowout erosion. They say that this is close to 1/3 of the amount required to make it the rest of the height to finish meeting up with the upper spillway section in the last week in October.
The morning is coffee time, before the swarming again of activity.
"hurry up sunrise "
I can’t remember how to post pictures from the DWR page.
(tried and failed)
Please post:
KJ_oroville_0009_09_20_17.jpg
which is currently #10 of #1509.
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There is still an incredible amount of void to be filled.
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https://pixel-ca-dwr.photoshelter.com/galleries/C0000OxvlgXg3yfg/G00003YCcmDTx48Y/Oroville-Spillway-Incident-Recovery
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Thanks!
On last day of summer, California is hit by unusual snow and hail storms
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http://www.freerepublic.com/focus/f-news/3587909/posts
This should serve a stark warning to DWR - and the public - at Oroville dam. An exact failure mode is occurring in Puerto Rico Dam that Oroville Spillway Gates already have the symptoms for.
As of tonight, a Puerto Rico dam is facing imminent collapse. Mass evacuations are underway. A large crack developed. The "failure mode" of the dam is from "jammed gates" where they cannot release water. The dam will then experience an overspill which is feared to result in a full "breach".
Oroville's Main Spillway Gates have experienced "jamming" to where full reconstruction of the side seals were warranted. Don't think this couldn't happen to Oroville as the side seal problems and alignment issues depending on the balanced strength of the Gates' anchor tendons. Just a 0.017 inch shift in either trunnion pin (strain) will cause the 0.040 inch side gap spacing to disappear. Bronze guide shoes could then assert higher forces on the slide plates. If these forces get too high, the gates jam and become stuck.
This Failure Mode at Puerto Rico (large crack) is amazingly similar to conditions at Oroville in that two large cracks are already in the massive concrete Piers (Gates 1 and 8). The cracks, one is 16+ feet, are evidenced from a design defect (design mistake) causing differential settlement of the spillway bridge abutment with respect to the two headworks structures. DWR has done nothing to fix these cracks. All they have done is continued to cover them with orange paint so they can watch to see how much they've grown from year to year.
DWR decided not to fix the anchor tendons and the cracks in the headworks. If the gates jam and fail, like what is happening in Puerto Rico, the Emergency spillway is going to be forced to be operated (no choice). There is not enough armoring on the Emergency spillway to handle flows more than 13,000 cfs for 2017/2018. This is a gamble that the Main Spillway Headworks and Gates will not fail. Well, here you have a real life example of a "jammed gates" failure mode underway.
Puerto Rico's dam (just over 120+ feet and 2 sq miles of reservoir area) is very small compared to Oroville dam (770 ft tall and much greater square miles in reservoir area). The high risk stakes are much greater at Oroville.
If the Emergency Spillway has to take a much larger flow, the secant wall will not protect the 64ft high concrete Weir section next to the Main Spillway Headworks. If this section "topples", the Headworks would see a deepening "V" breach. This could escalate to a full loss of head control, the potential destruction of the upper spillway at the headworks, and worst case, erosion/breach migration to the main earth dam.
=== Article clip (emphasis mine)
70,000 in Puerto Rico urged to evacuate immediately as dam is in imminent danger of failure
September 22, 2017 at 10:21 pm
SAN JUAN, PUERTO RICO Tens of thousands of residents in northwestern Puerto Rico were ordered to evacuate Friday amid fears that a dam holding back a large inland lake was in imminent danger of failing because of damage from Hurricane Marias floodwaters.
Officials worried that as many as 70,000 people could be in the path of a massive amount of rushing water in the event the Guajataca Dam releases into the Guajataca River, which flows north through low-lying coastal communities and empties into the ocean.
The dam suffered a fissure, Puerto Rico Gov. Ricardo Rosselló said in a news conference Friday afternoon. Residents in the municipalities of Quebradillas, Isabela and part of San Sebastian could be affected if the dam collapses, he said, and it could be a catastrophic event.
To those citizens . . . who are listening: Please evacuate, Rosselló said as buses were dispatched to ferry residents out of harms way. We want your life to be protected. . . . Please, if youre listening, the time to evacuate is now.
Abner Gomez, executive director of Puerto Ricos emergency management agency, said in an interview late Friday that the dams gates suffered mechanical damage during the storm, making it impossible for them to open and let out normal water currents. Officials worry that could cause the dam to spill over.
Gomez said that under current conditions, with water rising after the hurricane, there is no way to fix it right now. Additional water flowing into the lake could create sudden dangers, so emergency evacuation was the only option, he said. If the dam spills over or fails structurally, he said, thousands of people could die.
=== end clip more at link
70,000 in Puerto Rico urged to evacuate immediately as dam is in imminent danger of failure
The "fissure" or "crack" has not been identified where it is located. Guajataca Dam is an "earthen dam" like Oroville dam. Reports indicated that flooding has increased from this dam failure condition but it is not clear if the increased flow is from this "crack" or "fissure".
Engineers have stated that the cause of the mechanical gate failure (i.e. cannot open) is from structural conditions related to the hurricane storming.
Photos reveal that "back cutting" erosion into the earthen dam is occurring in a damaged area of a formed spillway. Other engineering reports noted that there was a crack in the northern part of the dam. However the back cutting erosion is about mid-way in the dam (centered slightly north).
More information will likely be coming in the news.
Back Cutting erosion eating away at the base of the dam. Section of the Spillway and dissipation riprap junction destroyed.
Guajataca Dam, Puerto Rico - Built in 1929 by the US Army Corps of Engineers. ~1,000 feet long, 120 feet high, and a 2 square mile reservoir area.
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