Walipini keeps flooding

Glad to find out that so many other people are working on walipinis.
Here in Minneapolis I've been working on one for several months that a great group of people got together and built this summer at a local church.
Ours is getting into pretty good shape now, but I'm having issues with water and with mold risk.
I'm trying to find a hand pump to pump out the water as it collects in the cold sink. For now I'm just bailing it out with buckets.
I found a hand-crank EZ pump on youtube that looks like it works, but people who bought it from Lehman's old-fashioned parts store have had issues with it and say it won't prime.
http://www.ebay.com/itm/Crank-EZ-Pump-Hy-Capacity-PN-8301252-/251699842901?hash=item3a9a7acf55:g:pE0AAOSwGWNUU-LI

I'm also concerned that with all the moisture the walipini will develop mold problems.
I just put in an ammo box stove - I wanted a rocket but some guy in my neighborhood had this one so I'm using it - to add heat during the cold Minneapolis winter - worked pretty well and is definitely helping with the moisture.
I'm trying to route the heat through the dirt walls to harvest some more of the heat into the wall - the ground is frozen but thawed when i put the smoke duct on top of it, so I'll try to bury it deeper and keep more of the heat.

Greg, do you have access to electricity? If so try one of these sump pumps.

http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2047675.m570.l1311.R1.TR1.TRC0.A0.H0.Xelectric+sump+pump.TRS0&_nkw=electric+sump+pump&_sacat=0

Hey Miles -
Thanks for your reply.
I may have to run an extension cord from the pastor's house out back to the walipini if I can't figure out another method, but I would very much like to get something going that doesn't need to send electricity back there.
I'm also hoping that I don't have to spend much money on a problem that may evaporate once the place gets dried out. It didn't flood in the summer, and we've had a very strange wet and warm early winter here in Minneapolis, so it may not happen again next year.
But I'd like to have a hand pump that I can use to pump water to irrigate and make compost tea also.
I'm looking at bilge pumps and old=fashioned pitcher pumps, but they may not handle water with sediment in it very well.
With freezing temps now, I'm getting a lot less water as I bail it out with buckets, and hopefully soon it will dry entirely.
I'm sure it will flood again in the spring though, and I'd like to be able to push out a lot of water at once.

So, Miles and other posters - my uncle lent me a little sump pump to deal with the flooding issue for now, it's a very imperfect system but I hope that it will keep it dry until the earth freezes enough to slow the water coming downward - in the summer the water table was seven feet below ground, so we built the floor 5 feet below ground, but the cold sink keeps flooding in this wet, warm early winter.
My thoughts are now moving to next summer and a way to heat the mass of the back wall. Ideally, I'd like to include an in-ground rocket stove that has a large open chamber as a pizza oven. I drew this extremely primitive diagram in PowerPoint. Do you think it's possible?

And now I'm thinking that to increase the burn efficiency of the wood, a chimney and baffle might make the stove that much more efficient. I drew a mockup here.
Although I haven't built a large rocket stove before, I've got to think that sending all the flame right from the burn chamber into a 3-inch chimney would direct all of the heat there at once, and thus lead to a secondary burn right there out of the burn chamber, without necessitating the chimney within the pizza oven, therefore giving more baking space and meaning less metalwork for me.

Any updates on how this went here?

If built as described, it probably didn't work very well. A 4" (never mind the 3" section) J-tube system is much too small to work reliably or give much heat. 6" is the minimum recommended for a J-tube, and it should stay that diameter all the way through (aside from expansion at certain points for easier flow or to heat an oven).

But a 6" system similar to this would be a good thing as long as it was built to specs.