We've found a piece of property that still has the remnants of a house that burned to the ground. The entire basement foundation is still there, but it's damaged and unusable, so we'd need to remove it to rebuild. What are the risks of removing that basement foundation and putting in a new one in the same spot? Is it recommended to dig deeper than the original foundation to reach undisturbed ground? Should we consider using a wood, block or poured wall foundation for the new structure because of this situation? Thanks!