More fun with water:
My main goal with my fort was to get military training down, and waste management/aquifers down.
Boy have I learned stuff.
I built a mass pit disposal with 3x2 hatches, 3 urist deep. Next time I'll make the fortification/shooting gallery type with an atom smasher in it.
I built a water system (my first working water wheel + pumpstack + aqueduct) to flood it from the top down and pump it from the bottom back up and into the top of the aquifer.
I built an atom smasher in it after I read the wiki on them. Only problem is that I built it so it was underneath two of the hatches, so anything dropped from them would land on top of the bridge and levitate there, even when it was down.
I also started a huge item dump and after while there were too many dwarfs in there and I needed to dump the hatches, so I did. Like 20 dwarfs somehow ended up in there stacked on just a couple squares. The pit has two z worth of 7/7 water in it, and at this point the pump stack isn't returning the water, to the aquifer, it's just moving it to the top of the pump stack. So dwarfs fall in, they let go of their babys to tread water and get onto the closed off stair scaffolds. I have to simultaneously clear the floor from the top of the scaffold and design a maintenance passage for the other side of the pump stack, a flood gate to control if it's filling the aquifer or not, and pump the water out... When the floor tile is taken out the dwarves finally get out and all the ones that can still walk bolt for the food and ale.
Two or three lost babies, I don't think there were any other serious injuries.
and there's a dwarf stuck on top of the atom smasher bridge for almost two months with a broken everything. I had to dig out a new scaffold to get him off of the corner of the bridge. It took a week for someone to finally decide to pull him to the hospital after I go the path to him made.
So: Use an atom smasher, but only make it 1 Z deep and keep the door away from the edge of the pit.
Water is always good for FUN.