Dale:
In one of your early posts you mention that the ICFs are 4" of foam on one side, 2" on the other, which would give a reasonably insulated wall. (My pet peeve is the extremism of some folks in massively insulating walls/roofs, where they have long reached the point of diminishing returns compared to improving windows or some other system in the design.) Looking at the picture of the cat nearly hitting your wall, the inside and outside foam layers look the same thickness. Is this an illusion, or are both the inner and outer layers at this point 2" (or 4")?
Compared to your situation, we didn't hit a single rock excavating for our house. We're on a mesa (I'm in New Mexico) whose what I'm told is called Aeolian - it's very dense sand deposited over a long period of time by the wind. It's very stable - you can dig a five foot deep trench with straight walls and it requires no shoring. (That's a practical statement, not a matter of safety practice. ) In digging our foundations (42" deep, 3' wide), we didn't encounter a single rock!