In 40d, I thought I was the aquifer queen. After the first time I read about aquifers and embarked on one, I never stopped. I've built a good seven or eight fortresses on single, double, and triple aquifers, and one on a quadruple. I've used every method I've heard of to get through them except for ice: tunneling down the side of a volcano; finding a path through ore; adding magma; creating a plug with a cave-in or series of cave-ins; pumping with manpower; pumping with wind power. My favorite method is definitely the cave-in; it's nice and neat, works nearly anywhere, and takes little dwarven effort.
But in 0.31.03, I am really embarrassed to admit that I'm getting stumped by a really easy, single layer aquifer. It's in nearly the simplest situation imaginable: it exists in a layer of rock, below some layers of sand, on a flat, single-biome map. I had been running (or...trying to run) a test fort on this plain map to learn the new stuff, and proof out methods for building something grander later. Since I'd read some information that had sent up potential red flags about using cave-ins in the new version, and since I'll be darned if I can find magma or a volcano above the aquifer level--I decided I'd better proof the aquifer cave-in plug before planning to build anything seriously relying on it.
So I hollowed out the area around a large black sand block, and caved it into my channeled-out aquifer in its layer of rock, which works just fine in 40d and ends in a plug and cheering--but instead I ended up with apparent failure: The aquifer is still gushing out water as necessary to fill the channeled-out layer, and, disturbingly, the only evidence remaining of the cave-in (besides the hollow ceiling) is a pile of dusty sand on each should-be-sand tile at the bottom. The piles of dusty sand weren't there before.
(Here is a basic picture of what I did, which worked fine for me in 40d:
http://df.magmawiki.com/index.php/File:Aquifier_cavein_1level.jpg. However, the last two illustrations in the series aren't happening.)
Did my chunk of caved-in black sand become several piles of dusty sand when it hit bottom, and accomplish precisely nothing else? It does seem to be what would happen in real life when collapsing several cubic yards of sand into an underground lake, lol. I've searched this forum, the wiki, and the web for the problem I am having, and I've come up with nothing that seems useful or relevant. Have I run into a bug, or a feature, or have I missed an important new step for aquifer plugging in the new version? Am I disallowed from having my fun with sand now? ><