Similar to [http://dwarffortresswiki.org/index.php/User:Rhenaya/HowtoDualAquifer][/Rhenaya], but supported from above rather than below. Handy for soil aquifers, where you need to dig out before building a wall to seal them off.
Currently only works in principle, as dropping zlevels into aquifers changes the ground into the soil type and aquifer/not aquifer status of the dug out aquifer level squares (what?)
First dig out a large room and channel a large square into the aquifer level below. Channel the same square (but one tile larger on the surface, down until you are separated by only the floor/ceiling separating the surface from the crash room. Then build an up stairway, on both solid land and the center of the square and connect them with floors. A support on the solid land portion below the floor helps with cleanup after
>__________________________> +1 Z Level
_______ ______<___________ ________I______< Surface
_______^__________________^_______________ -1 Z Level
Tunnel
_________ _______________ ______________ underground floor
_________^_______________^______________ aquifer
have your miners channel out from the square two tiles 'radially' in on the surface, and breach all but one tile on the *inner* square. I also channel out the entire area of the aquifer square, for reasons I'll show later
> _________________________> +1 Z Level
_________ __ __<________ __ ________I______< Surface
_________ ______________ __ _______________ -1 Z Level
| | Tunnel
__________ V V ________________ underground floor
_________^~~~~~~~~~~~^______________ aquifer
Find your finest, bravest cheesemaker and give him a pick and have him bust that last unbreached floor square. The square of non-aquifer soil/rock falls down, sealing off the internal space you've dug, the Master Thresher follows, BUT since he falls in the water, I've not noticed the getting-blasted-across-the-screen-and-smeared-on-the-nearest-wall results of a non-aquatic cave-in. I've found that falling in water with no swimming is almost always fatal in adventurer mode, but the Urist McFishdissector has never not gotten out of the water (this is also why you channel out the interior, to give him some ramps) alive, and has never had any fall or cave in damage. Repeat with the next level. I haven't done the math on the number of levels you can possibly breach with a 3X3 embark, but any realistic aquifer you can get through pretty easy, and it's quick and tons of fun, of both types.
You basically need a square that is 3+4N X 3+4N for N levels you intend to breach. The inner 3X3 square for the support, and a 'circle' of channeling around it. The 'last' square you drop will be 5X5. Since you can't dig it without flooding, it leaves a 3X3 area for you to sink your center stairway into bedrock with. Once you have rock for mechanisms, link the support up, break down the outer stairway, and if the gobbos ever make it as far as that main bedrock stairway you have an instant apocalyptic lockdown lever!
Anyway, it's probably been done, or isn't done for some reason (aside from the bug which I *think* is only occasional and which I *think* Toady intends to fix, or at least that's what the wiki aquifer page tells me? Thoughts?
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Topic: New (to me) method of breaching aquifers (Read 1340 times)