The house did not fall so I would say with a real engineer telling me how to place the rebar I can dig down about 21 below the dining room floor, there is a 4 foot crawlspace, 5 to 6 feet of sand then about 20 feet of clay sitting on top of the water table.
Two stories would be possible but I am thinking it would be better to have one floor with 12 foot ceilings with everything gently sloping to the drain in the center and I could have an easy 1200 square feet of tornadoes proof shelter, enough for the entire street according to FEMA. It's not likely that I'll build the big bunker since I'm pretty close to being tapped out, need a few more surgeries, and it's not likely I'll ever get hired to do anything since without a short term memory I spend a lot of time walking around trying to remember what it is I am doing. They would need to hire someone to follow me around and keep reminding me what I was working on at the moment but it might make for an interesting Discovery Channel Show...
LOL If you're gonna Dream a Dream don't ever cut yourself short.
When I had the accident I had the house dried in but it was just sticks inside no wiring, plumbing etc. Fortunately I had the siding on already since that took a month but I hadn't bricked the bottom level yet and I managed to do that in about 2 years by putting a white board up in the Foyer and every morning when I arrived I'd write down what I was planning on working on and I finished the house and relearned how to walk and talk since somehow I fell through the medical cracks and was never actually sent to any therapy or rehab but maybe it worked out better this way.
If worse comes to worse I'll just turn this into a stairwell and make an 8 by 12 foot room under one part of the bottom garage floor which according to http://www.fema.gov/hazard/tornado/to_saferoom.shtm
it is the safest place to build a shelter.