Since we are starting from scratch, we want to make sure the foundation will hold up for the long-term. We have had many houses over the years where foundation settlement was a problem. So, we started with new soil borings at our site. One taken to 25′ depth, the other hand bored (due to access limitations) to 6 feet. Not surprisingly, given our proximity to the river, neither boring hit a solid base. The geotech report and our engineer recommended excavation of the native soils, which were high in expansive clays, down to three feet below natural grade. So, today we have a large hole in the ground. Plan is to bring in new non-expansive fill, compact it, and prepare for the foundation forms.