No! We Are Not Cursing
BOOJUM! remains as SFW as ever, if you can keep up with our mental contortions. I am referring to the physical structure used to retain water and direct it's flow accordingly, and since the dam in question is in Australia, it's going to be hot by default.
Okay, Your Humble Scribe hit this particular subject matter after reading a good few warnings on a Youtube Reddit channel about "What simple thing is incredibly dangerous?" and an engineer replied "Spillways". Art!
Spillways are large engineered structures intended to mediate the flow of water, and our Engineering Cassandra noted that they are tempting to drunks and children to slide down and into the pool at the bottom. The catch here is that if you get into that pool, you will never get out, because the incoming water forms an endless loops as tons of water circle round and round. Even being in a canoe may not save you. Art!
This is a particular type of spillway, known as a 'glory hole', at the Geehi Dam in New South Wales, Australia. The idea is that if the water level gets too high, it will fall into the spillway and prevent the dam from being over-topped, as it comes out at the bottom of the dam and into the river. That inverted bell is just over a hundred feet across. This design was selected as the site was comparatively narrow and a conventional parallel spillway was impractical.
I couldn't find any good pictures of the completed dam taken from downstream, until I came across an old Australian Screen film that showed the whole process of constructing the dam. Art!
The finished product
That white cloud is water being released under pressure as a test, reaching almost as high as the dam itself - 300 feet. You can see the spillway at mid-starboard. This kind of test would be rare, since the purpose of the dam is to supply water for hydroelectric plant to generate electricity.
Of course, it wouldn't be BOOJUM! if we didn't dig a little deeper, would it? Because how, exactly, do you construct a dam like this?
Step 1 is Location. You need to select a river site where the 'shoulders' or abutments are symmetrical and are of suitable rock without faults or flaws. Art!
The dam's site, with all timber and brush removed, so actually well into the project.
Step 2 = Materials. You see, for this embankment dam, the external cladding will be of semi-porous rock but the central core must be composed of non-porous material. You can't have the dam leaking like a soggy set of kitchen towels. Art!
CAUTION! Not for human consumption
These are clays located from sites nearby the dam itself, which is a good idea, since it cuts down on transport costs.
Step 3: People. There are going to be a lot of people working on this project for several years, so having them commute in is wildly inefficient, given that this site is up in the Snowy Mountains. So a couple of small townships were built to accommodate workers and families. Art!
Step 5 is diverting the Geehi River. Pretty obviously you can't have the river running over the dam you're trying to construct, so a diversionary tunnel is dug to temporarily carry it past the building site. Art!
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| River diverted |
Step 6 is building the dam and spillway, which required enormous amounts of reinforcing steel, concrete and wooden forms. Art!
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| Nearly done! |
At this point the diversionary tunnel was shut down and the reservoir began to fill. As mentioned above, in 1967 a test release from the emergency valve was tested, by which the Geehi Dam was supplying water to the Murray power stations. Art!
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| Geehi Dam smack in the middle |
Well, there you have it, how to build a dam. It's very straightforward in detail, except every detail is very complicated.
"Sarpeidon"
Another of those words that pop up in my head from time to time, and this one might have come up before.
I know, I know, it sounds like an ancient Persian Emperor, 'Sarpeidon, son of Cambyses II, ruler of the Medes and Persians" who probably gets a disapproving mention in Herodotus. Art!
Scary hairy
Sadly for all you classical scholars out there, it's nothing of the sort, and in fact couldn't be more distant from the truth. It's the name of a planet in the "Starry Trex" (sp?) series in the episode "All Our Yesterdays". The inhabitants, to escape an imminent supernova, have used time travel to escape into the past. Art!
Uh-oh. I feel an Art crush coming on.
Featuring the very easy-on-the-eyes Mariette Hartley, and NO! you slobbering perverts don't get to see her in her fur bikini.
"The Sea Of Sand"
O my goodness, revolution is afoot on Wastelandworld, all thanks to the Doctor's slyly effective leverage of political awareness.
‘I look around and see a dying
world. We should be trying to revive it,
not trying to destroy other worlds.
Besides, Thedoctor prophet said the aristocrats helped despoil this world,
an age ago.’ This last sentence was said
with a sly glance at the Doctor.
‘Really,
I’m not a prophet!’ protested the latter, now feeling a little concerned at his
reputation’s rapid spread. He tried to
fade into the background rather more, trying to listen to what the Farmers were
planning.
Imgelissa,
nominally the leader of the Farmers, gestured to his followers to gather round
for a quick discussion.
The
rebellion had spread up and down the coast with surprising speed, moving from
scattered attacks on isolated Overseers and Warriors to large-scale assaults on
the various building complexes. Lord
Sur’s castle had been attacked, occupied and plundered, the underground cells
discovered and checked (all empty). The
Warrior garrison fought briefly and fled, pursued by angry insults and thrown
stones.
Part
of the reason for the rapid spread of actual revolt, as opposed to covert
discontent and mutterings, was the excessive demand for algae requirement, and
the attempted Evisceration of dozens of Farmers to “encourage” their fellows.
This idea has definitely arrived on time.
Beware - The GARAGE DOOR SPRING!!
One of the take-aways from that Youtube Reddit posting of what looks simple yet is deadly, was how dangerous the springs used to open and close garage doors are. Art!
One poster recounted how a building inspector was talking him through various ways to cut down on condensation in the crawl-space, or where insulation would reduce heating bills. When it came to the garage, the inspector pointed to the door springs and warned, very intently DO NOT TOUCH!
These things store an enormous amount of energy. If they are mis-handled or break, they can easily cause traumatic amputation of a limb, or death if they impact the victim's head. Art!
Torsion spring versus canteloupe
(Courtesy Garage Door Genius)GDG again
Those things spin at hundreds of RPM, and would easily remove fingers.
BOOJUM! - terrifying you with one fact at a time*.
Finally -
For the first time in who-knows-how-many years, Your Humble Scribe ventured into Oldham Library, and got my library card renewed, hurrah! I cannot use the public PCs, mind, because my personal number doesn't work - Conrad suspects a new card is needed. Still, I can get books out, because I did so with a couple. It's all self-service now, no need for staff.
Sadly no Korean or Ukrainian recipe books, so I got one on Japanese recipes, because the ingredients are quite dual-serve. Art!
* Okay, okay, it was two facts today.
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