OK, I have had this in my head for some time. How do I build an underground room about 10'x10'? The area I would like to build it in is in the back woods, no houses or roads for about a mile, I hit water when I dig 15" down and there are power lines in the area. Another question is do I have to have a special permit or something to do this on when its my land? And what about a tunnel leading to other rooms? Any advise will help.